Ultrasonic Guided Waves for Aging Wire Insulation Assessment

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Madaras, Eric I.

2001-01-01

Environmentally aged wire insulation can become brittle and crack and thus expose the underlying conductive wire to the potential for short circuits and fire. The feasibility of using ultrasonic guided waves to measure insulation condition was examined. First a simple model to study guided wave propagation in a bare and thin plastic coated wire was examined and then some aviation grade wire samples that had been heat-damaged. Initial measurements indicate that ultrasonic guided wave velocity can be used to monitor insulation stiffness.

Transducer Joint for Kidney-Stone Ultrasonics

NASA Technical Reports Server (NTRS)

Angulo, E. D.

1983-01-01

Ultrasonic therapy for kidney stones improved by new way of connecting wire-probe ultrasonic waveguide to transducer. Improved mounting allows joint to last long enough for effective treatment. Sheath and rubber dampers constrain lateral vibration of wire waveguide. Combination of V-shaped mounting groove, sheath, and rubber dampers increases life expectancy of wire 15 times or more.

A Method For The Verification Of Wire Crimp Compression Using Ultrasonic Inspection

NASA Technical Reports Server (NTRS)

Cramer, K. E.; Perey, Daniel F.; Yost, William t.

2010-01-01

The development of a new ultrasonic measurement technique to assess quantitatively wire crimp terminations is discussed. The amplitude change of a compressional ultrasonic wave propagating at right angles to the wire axis and through the junction of a crimp termination is shown to correlate with the results of a destructive pull test, which is a standard for assessing crimp wire junction quality. To demonstrate the technique, the case of incomplete compression of crimped connections is ultrasonically tested, and the results are correlated with pull tests. Results show that the nondestructive ultrasonic measurement technique consistently predicts good crimps when the ultrasonic transmission is above a certain threshold amplitude level. A quantitative measure of the quality of the crimped connection based on the ultrasonic energy transmitted is shown to respond accurately to crimp quality. A wave propagation model, solved by finite element analysis, describes the compressional ultrasonic wave propagation through the junction during the crimping process. This model is in agreement within 6% of the ultrasonic measurements. A prototype instrument for applying this technique while wire crimps are installed is also presented. The instrument is based on a two-jaw type crimp tool suitable for butt-splice type connections. A comparison of the results of two different instruments is presented and shows reproducibility between instruments within a 95% confidence bound.

Distributed temperature sensing using a SPIRAL configuration ultrasonic waveguide

NASA Astrophysics Data System (ADS)

Periyannan, Suresh; Balasubramaniam, Krishnan

2017-02-01

Distributed temperature sensing has important applications in the long term monitoring of critical enclosures such as containment vessels, flue gas stacks, furnaces, underground storage tanks and buildings for fire risk. This paper presents novel techniques for such measurements, using wire in a spiral configuration and having special embodiments such a notch for obtaining wave reflections from desired locations. Transduction is performed using commercially available Piezo-electric crystal that is bonded to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes were employed. Time of fight (TOF) differences between predefined reflectors located on the waveguides are used to infer temperature profile in a chamber with different temperatures. The L(0,1) wave mode (pulse echo approach) was generated/received in a spiral waveguide at different temperatures for this work. The ultrasonic measurements were compared with commercially available thermocouples.

Process for Nondestructive Evaluation of the Quality of a Crimped Wire Connector

NASA Technical Reports Server (NTRS)

Yost, William T. (Inventor); Cramer, Karl E. (Inventor); Perey, Daniel F. (Inventor); Williams, Keith A. (Inventor)

2014-01-01

A process and apparatus for collecting data for nondestructive evaluation of the quality of a crimped wire connector are provided. The process involves providing a crimping tool having an anvil and opposing jaw for crimping a terminal onto a stranded wire, moving the jaw relative to the anvil to close the distance between the jaw and the anvil and thereby compress the terminal against the wire, while transmitting ultrasonic waves that are propagated through the terminal-wire combination and received at a receiving ultrasonic transducer as the jaw is moved relative to the anvil, and detecting and recording the position of the jaw relative to the anvil as a function of time and detecting and recording the amplitude of the ultrasonic wave that is received at the receiving ultrasonic transducer as a function of time as the jaw is moved relative to the anvil.

Application of Ultrasonic Guided Waves for Evaluating Aging Wire Insulation

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Madaras, Eric I.

2005-01-01

Aging wiring has become a critical issue to the aerospace and aircraft industries due to Shuttle and aircraft incidents. The problem is that over time the insulation on wire becomes brittle and cracks. This exposes the underlying conductive wire to the potential for short circuits and fire. Popular methods of monitoring aging wire problems focuses on applying electrical sensing techniques that are sensitive to the conductor's condition, but not very sensitive to the wire insulation's condition. Measurement of wire insulation stiffness and ultrasonic properties by ultrasonic guided waves is being examined. Experimental measurements showed that the lowest order extensional mode could be sensitive to stiffness changes in the wire insulation. To test this theory conventional wire samples were heat damaged in an oven, in a range of heating conditions. The samples were 12, 16, and 20 gauge and the heat damage introduced material changes in the wire insulation that made the originally flexible insulation brittle and darker in color. Results showed that extensional mode phase velocity increased for the samples that were exposed to heat for longer duration.

Ultrasonics Equipped Crimp Tool: A New Technology for Aircraft Wiring Safety

NASA Technical Reports Server (NTRS)

Yost, William T.; Perey, Daniel F.; Cramer, Elliott

2006-01-01

We report on the development of a new measurement technique to quantitatively assess the condition of wire crimp connections. This ultrasonic (UT) method transmits high frequency sound waves through the joint under inspection. The wire-crimp region filters and scatters the ultrasonic energy as it passes through the crimp and wire. The resulting output (both time and frequency domains) provides a quantitative measure of the joint quality that is independent and unaffected by current. Crimps of poor mechanical and electrical quality will result in low temporal output and will distort the spectrum into unique and predictable patterns, depending on crimp "quality". This inexpensive, real-time measurement system can provide certification of crimps as they are made and recertification of existing wire crimps currently in service. The measurements for re-certification do not require that the wire be disconnected from its circuit. No other technology exists to measure in-situ the condition of wire joints (no electrical currents through the crimp are used in this analytical technique). We discuss the signals obtained from this instrument, and correlate these signals with destructive wire pull tests.

The Application of Ultrasonic Inspection to Crimped Electrical Connections

NASA Technical Reports Server (NTRS)

Cramer, K. Elliott; Perey, Daniel F.; Yost, William T.

2010-01-01

The development of a new ultrasonic measurement technique to quantitatively assess wire crimp terminations is discussed. The development of a prototype instrument, based on a modified, commercially available, crimp tool, is demonstrated for applying this technique when wire crimps are installed. The crimp tool has three separate crimping locations that accommodate the three different ferrule diameters. The crimp tool in this study is capable of crimping wire diameters ranging from 12 to 26 American Wire Gauge (AWG). A transducer design is presented that allows for interrogation of each of the three crimp locations on the crimp tool without reconfiguring the device. An analysis methodology, based on transmitted ultrasonic energy and timing of the first received pulse is shown to correlate to both crimp location in the tool and the AWG of the crimp/ferrule combination. The detectability of a number of the crimp failure pathologies, such as missing strands, partially inserted wires and incomplete crimp compression, is discussed. A wave propagation model, solved by finite element analysis, describes the compressional ultrasonic wave propagation through the junction during the crimping process.

Rapid bonding enhancement by auxiliary ultrasonic actuation for the fabrication of cyclic olefin copolymer (COC) microfluidic devices

NASA Astrophysics Data System (ADS)

Yu, H.; Tor, S. B.; Loh, N. H.

2014-11-01

Thermal compression bonding is a straightforward, inexpensive and widely used method for enclosing open microchannels in thermoplastic microfluidic devices. It is advantageous over adhesive, solvent and grafting bonding methods in retaining material homogeneity. However, the trade-off between high bond strength and low microchannel deformation is always a crucial consideration in thermal compression bonding. In this study, an effective method for improving bond strength while retaining the microchannel integrity with negligible distortion is proposed and analyzed. Longitudinal ultrasonic actuation was applied to the preheated cyclic olefin copolymer (COC) substrates to achieve accelerated and enhanced bonding with an ultrasonic welding system. Intimate contact between the bonding surfaces before the ultrasonic actuation was found to be an important prior condition. With improper contact, several bonding defects would occur, such as voids, localized spot melting and edge melting. Under auxiliary ultrasonic vibration, within 10 s, the bond strength developed at the bonding interface could be dramatically improved compared with those achieved without ultrasonic actuation. The enhanced bond strength obtained at a preheating temperature of 20 °C lower than its Tg could be comparable to the strength for pure thermal compression at 5 °C higher than its Tg. It is believed that the ultrasonic energy introduced could elevate the interfacial temperature and facilitate the interdiffusion of molecular chain segments at the interface, consequently resulting in rapidly enhanced bonding. Also, the microchannel distortion after ultrasonic actuation was found to be satisfactory—another important requirement. From dynamic mechanical analysis, the glass transition temperature of COC was found to increase with increasing frequency, and the temperature of the bulk polymer under ultrasonic actuation was still well under Tg; therefore the deformation is minor under ultrasonic actuation.

Characteristics of coated copper wire specimens using high frequency ultrasonic complex vibration welding equipments.

PubMed

Tsujino, J; Ihara, S; Harada, Y; Kasahara, K; Sakamaki, N

2004-04-01

Welding characteristic of thin coated copper wires were studied using 40, 60, 100 kHz ultrasonic complex vibration welding equipments with elliptical to circular vibration locus. The complex vibration systems consisted of a longitudinal-torsional vibration converter and a driving longitudinal vibration system. Polyurethane coated copper wires of 0.036 mm outer diameter and copper plates of 0.3 mm thickness and the other dimension wires were used as welding specimens. The copper wire part is completely welded on the copper substrate and the insulated coating material is driven from welded area to outsides of the wire specimens by high frequency complex vibration.

Aging Wire Insulation Assessment by Phase Spectrum Examination of Ultrasonic Guided Waves

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Madaras, Eric I.

2003-01-01

Wire integrity has become an area of concern to the aerospace community including DoD, NASA, FAA, and Industry. Over time and changing environmental conditions, wire insulation can become brittle and crack. The cracks expose the wire conductor and can be a source of equipment failure, short circuits, smoke, and fire. The technique of using the ultrasonic phase spectrum to extract material properties of the insulation is being examined. Ultrasonic guided waves will propagate in both the wire conductor and insulation. Assuming the condition of the conductor remains constant then the stiffness of the insulator can be determined by measuring the ultrasonic guided wave velocity. In the phase spectrum method the guided wave velocity is obtained by transforming the time base waveform to the frequency domain and taking the phase difference between two waveforms. The result can then be correlated with a database, derived by numerical model calculations, to extract material properties of the wire insulator. Initial laboratory tests were performed on a simple model consisting of a solid cylinder and then a solid cylinder with a polymer coating. For each sample the flexural mode waveform was identified. That waveform was then transformed to the frequency domain and a phase spectrum was calculated from a pair of waveforms. Experimental results on the simple model compared well to numerical calculations. Further tests were conducted on aircraft or mil-spec wire samples, to see if changes in wire insulation stiffness can be extracted using the phase spectrum technique.

Experimental study on titanium wire drawing with ultrasonic vibration.

PubMed

Liu, Shen; Shan, Xiaobiao; Guo, Kai; Yang, Yuancai; Xie, Tao

2018-02-01

Titanium and its alloys have been widely used in aerospace and biomedical industries, however, they are classified as difficult-to-machine materials. In this paper, ultrasonic vibration is imposed on the die to overcome the difficulties during conventional titanium wire drawing processes at the room temperature. Numerical simulations were performed to investigate the variation of axial stress within the contacting region and study the change of the drawing stress with several factors in terms of the longitudinal amplitude and frequency of the applied ultrasonic vibration, the diameter reduction ratio, and the drawing force. An experimental testing equipment was established to measure the drawing torque and rotational velocity of the coiler drum during the wire drawing process. The result indicates the drawing force increases with the growth of the drawing velocity and the reduction ratio, whether with or without vibrations. Application of either form of ultrasonic vibrations contributes to the further decrease of the drawing force, especially the longitudinal vibration with larger amplitude. SEM was employed to detect the surface morphology of the processed wires drawn under the three circumstances. The surface quality of the drawn wires with ultrasonic vibrations was apparently improved compared with those using conventional method. In addition, the longitudinal and torsional composite vibration was more effective for surface quality improvement than pure longitudinal vibration, however, at the cost of weakened drawing force reduction effect. Copyright © 2017 Elsevier B.V. All rights reserved.

Transurethral ultrasonic ureterolithotripsy using a solid-wire probe.

PubMed

Chaussy, C; Fuchs, G; Kahn, R; Hunter, P; Goodfriend, R

1987-05-01

A multicenter study evaluates a new technique for transurethral ultrasonic ureterolithotripsy utilizing a solid-wire probe. The transverse vibrations of the probe cause greater stone disintegration. A small ureteroscope is used and a basket is not required. There was a 96.6 per cent success rate in 118 cases. This technique has significantly improved ultrasonic lithotripsy. It has proved to be useful for upper ureteral stones not amenable to extracorporeal shock-wave lithotripsy and lower ureteral stones including "steinstrasse."

Body of Knowledge (BOK) for Copper Wire Bonds

NASA Technical Reports Server (NTRS)

Rutkowski, E.; Sampson, M. J.

2015-01-01

Copper wire bonds have replaced gold wire bonds in the majority of commercial semiconductor devices for the latest technology nodes. Although economics has been the driving mechanism to lower semiconductor packaging costs for a savings of about 20% by replacing gold wire bonds with copper, copper also has materials property advantages over gold. When compared to gold, copper has approximately: 25% lower electrical resistivity, 30% higher thermal conductivity, 75% higher tensile strength and 45% higher modulus of elasticity. Copper wire bonds on aluminum bond pads are also more mechanically robust over time and elevated temperature due to the slower intermetallic formation rate - approximately 1/100th that of the gold to aluminum intermetallic formation rate. However, there are significant tradeoffs with copper wire bonding - copper has twice the hardness of gold which results in a narrower bonding manufacturing process window and requires that the semiconductor companies design more mechanically rigid bonding pads to prevent cratering to both the bond pad and underlying chip structure. Furthermore, copper is significantly more prone to corrosion issues. The semiconductor packaging industry has responded to this corrosion concern by creating a palladium coated copper bonding wire, which is more corrosion resistant than pure copper bonding wire. Also, the selection of the device molding compound is critical because use of environmentally friendly green compounds can result in internal CTE (Coefficient of Thermal Expansion) mismatches with the copper wire bonds that can eventually lead to device failures during thermal cycling. Despite the difficult problems associated with the changeover to copper bonding wire, there are billions of copper wire bonded devices delivered annually to customers. It is noteworthy that Texas Instruments announced in October of 2014 that they are shipping microcircuits containing copper wire bonds for safety critical automotive applications. An evaluation of copper wire bond technology for applicability to spaceflight hardware may be warranted along with concurrently compiling a comprehensive understanding of the failure mechanisms involved with copper wire bonded semiconductor devices.

Apparatus for disintegrating kidney stones

NASA Technical Reports Server (NTRS)

Angulo, E. D. (Inventor)

1984-01-01

The useful life of the wire probe in an ultrasonic kidney stone disintegration instrument is enhanced and prolonged by attaching the wire of the wire probe to the tip of an ultrasonic transducer by means of a clamping arrangement. Additionally, damping material is applied to the wire probe in the form of a damper tube through which the wire probe passes in the region adjacent the transducer tip. The damper tube extends outwardly from the transducer tip a predetermined distance, terminating in a resilient soft rubber joint. Also, the damper tube is supported intermediate its length by a support member. The damper system thus acts to inhibit lateral vibrations of the wire in the region of the transducer tip while providing little or no damping to the linear vibrations imparted to the wire by the transducer.

Microlens array for focusing airborne ultrasound using heated wire grid

NASA Astrophysics Data System (ADS)

Cai, Liang-Wu; Sánchez-Dehesa, José

2007-10-01

This letter reports on the focusing of airborne ultrasound by a simple grid of heated wires. The focusing is analogous to that of an array of optical microlenses. The focusing pattern is determined by the spacing between wires, and the focusing areas are tightly confined with a great "depth of field." Such acoustical microlens arrays have great potentials for shaping beams produced by ultrasonic transducers, in applications such as ultrasonic cleaning and nondestructive testing.

Nucleation and growth of zinc oxide nanorods directly on metal wire by sonochemical method.

PubMed

Rayathulhan, Ruzaina; Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

2017-03-01

ZnO nanorods were directly grown on four different wires (silver, nickel, copper, and tungsten) using sonochemical method. Zinc nitrate hexahydrate and hexamethylenetetramine (HMT) were used as precursors. Influence of growth parameters such as precursors' concentration and ultrasonic power on the grown nanorods were determined. The results demonstrated that the precursor concentration affected the growth structure and density of the nanorods. The morphology, distribution, and orientation of nanorods changed as the ultrasonic power changed. Nucleation of ZnO nanorods on the wire occurred at lower ultrasonic power and when the power increased, the formation and growth of ZnO nanorods on the wires were initiated. The best morphology, size, distribution, and orientation of the nanorods were observed on the Ag wire. The presence of single crystal nanorod with hexagonal shaped was obtained. This shape indicates that the ZnO nanorods corresponded to the hexagonal wurtzite structure with growth preferential towards the (002) direction. Copyright © 2016 Elsevier B.V. All rights reserved.

Proceedings of the Second Annual Symposium for Nondestructive Evaluation of Bond Strength

NASA Technical Reports Server (NTRS)

Roberts, Mark J. (Compiler)

1999-01-01

Ultrasonics, microwaves, optically stimulated electron emission (OSEE), and computational chemistry approaches have shown relevance to bond strength determination. Nonlinear ultrasonic nondestructive evaluation methods, however, have shown the most effectiveness over other methods on adhesive bond analysis. Correlation to changes in higher order material properties due to microstructural changes using nonlinear ultrasonics has been shown related to bond strength. Nonlinear ultrasonic energy is an order of magnitude more sensitive than linear ultrasound to these material parameter changes and to acoustic velocity changes caused by the acoustoelastic effect when a bond is prestressed. Signal correlations between non-linear ultrasonic measurements and initialization of bond failures have been measured. This paper reviews bond strength research efforts presented by university and industry experts at the Second Annual Symposium for Nondestructive Evaluation of Bond Strength organized by the NDE Sciences Branch at NASA Langley in November 1998.

Anisotropic effect of the magnetic sensor formed from metal/high-Tc superconductor contact

NASA Astrophysics Data System (ADS)

Miyake, S.; Aoyama, T.; Suzuki, Y.; Kusaka, T.; Yotsuya, T.

1991-03-01

The magnetic sensor formed via a metal/high-Tc superconductor small contact shows anisotropic properties below the lower critical field. An Ag wire was connected directly to the superconductor by an ultrasonic bonding method. It is shown that the resistance was changed by the field parallel to the superconductor surface, while it was not affected by the vertical field. The change is estimated to be 5 x 10 to the -5th ohm/G. No hysteresis is observed. Magnetic field direction can be detected by using these properties and a deferential measuring method of the resistance.

1 mil gold bond wire study.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huff, Johnathon; McLean, Michael B.; Jenkins, Mark W.

2013-05-01

In microcircuit fabrication, the diameter and length of a bond wire have been shown to both affect the current versus fusing time ratio of a bond wire as well as the gap length of the fused wire. This study investigated the impact of current level on the time-to-open and gap length of 1 mil by 60 mil gold bond wires. During the experiments, constant current was provided for a control set of bond wires for 250ms, 410ms and until the wire fused; non-destructively pull-tested wires for 250ms; and notched wires. The key findings were that as the current increases, themore » gap length increases and 73% of the bond wires will fuse at 1.8A, and 100% of the wires fuse at 1.9A within 60ms. Due to the limited scope of experiments and limited data analyzed, further investigation is encouraged to confirm these observations.« less

Investigating the Use of Ultrasonic Guided Waves for Aging Wire Insulation Assessment

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Madaras, Eric I.

2002-01-01

Aging wiring has become a critical issue to DoD, NASA, FAA, and Industry. The problem is that insulation on environmentally aged wire becomes brittle and cracks. This exposes the underlying conductive wire to the potential for short circuits and fire. The difficulty is that techniques to monitor aging wire problems focus on applying electrical sensing techniques that are not very sensitive to the wire insulation. Thus, the development of methods to quantify and monitor aging wire insulation is highly warranted. Measurement of wire insulation stiffness by ultrasonic guided waves is being examined. Initial laboratory tests were performed on a simple model consisting of a solid cylinder and then a solid cylinder with a polymer coating. Experimental measurements showed that the lowest order axisymmetric mode may be sensitive to stiffness changes in the wire insulation. To test this theory, mil-spec wire samples MIL-W-81381, MIL-W-22759/34, and MIL-W-22759/87 (typically found in aircraft) were heat-damaged in an oven, in a range of heating conditions. The samples were 12, 16, and 20 gauge and the heat-damage introduced material changes in the wire-insulation that made the originally flexible insulation brittle and darker in color. Axisymmetric mode phase velocity increased for the samples that were exposed to heat for longer duration. For example, the phase velocity in the 20-gauge MIL-W-22759/34 wire changed from a baseline value of 2790m/s to 3280m/s and 3530m/s for one-hour exposures to 3490C and 3990C, respectively. Although the heat-damage conditions are not the same as environmental aging, we believe that with further development and refinements, the ultrasonic guided waves can be used to inspect wire-insulation for detrimental environmental aging conditions.

Cutting head for ultrasonic lithotripsy

NASA Technical Reports Server (NTRS)

Anguluo, E. D.; Goodfriend, R. (Inventor)

1985-01-01

A cutting head for attachment to the end of the wire probe of an ultrasonic kidney stone disintegration instrument is described. The cutting head has a plurality of circumferentially arranged teeth formed at one end thereof to provide a cup shaped receptacle for kidney stones encountered during the disintegration procedure. An integral reduced diameter collar diminishes stress points in the wire and reduce breakage thereof.

Cutting Head for Ultrasonic Lithotripsy

NASA Technical Reports Server (NTRS)

Angulo, Earl D. (Inventor); Goodfriend, Roger (Inventor)

1989-01-01

A cutting head for attachment to the end of the wire probe of an ultrasonic kidney stone disintegration instrument. The cutting head has a plurality of circumferentially arranged teeth formed at one end thereof to provide a cup-shaped receptacle for kidney stones encountered during the disintegration procedure. An integral reduced diameter collar diminishes stress points in the wire and reduces breakage thereof.

49 CFR 234.271 - Insulated rail joints, bond wires, and track connections.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Insulated rail joints, bond wires, and track connections. 234.271 Section 234.271 Transportation Other Regulations Relating to Transportation (Continued... joints, bond wires, and track connections. Insulated rail joints, bond wires, and track connections shall...

49 CFR 234.271 - Insulated rail joints, bond wires, and track connections.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Insulated rail joints, bond wires, and track connections. 234.271 Section 234.271 Transportation Other Regulations Relating to Transportation (Continued... joints, bond wires, and track connections. Insulated rail joints, bond wires, and track connections shall...

Wire-bonder-assisted integration of non-bondable SMA wires into MEMS substrates

NASA Astrophysics Data System (ADS)

Fischer, A. C.; Gradin, H.; Schröder, S.; Braun, S.; Stemme, G.; van der Wijngaart, W.; Niklaus, F.

2012-05-01

This paper reports on a novel technique for the integration of NiTi shape memory alloy wires and other non-bondable wire materials into silicon-based microelectromechanical system structures using a standard wire-bonding tool. The efficient placement and alignment functions of the wire-bonding tool are used to mechanically attach the wire to deep-etched silicon anchoring and clamping structures. This approach enables a reliable and accurate integration of wire materials that cannot be wire bonded by traditional means.

Ultrasonic Non Linearity Characterization of the Stainless Steel Wire Reinforced Aluminium Composite

NASA Astrophysics Data System (ADS)

Kim, C. S.; Park, T. S.; Park, I. K.; Hyun, C. Y.

2009-03-01

The effectiveness of the ultrasonic nonlinearity measurement for nearly closed cracks was demonstrated for hot pressing and extrusion of stainless steel 304 short wire reinforced aluminum composite. Aluminum based composites show considerable potential in the aerospace industry and the automotive industry due to their high specific strength and low thermal expansion coefficient. The ultrasonic nonlinearity (β/β0) increased with the volume fraction of SSF and aging heat treatment because of the generation of microvoids resulted from localized SSF and matrix precipitation. This study demonstrates the potential for characterization of reinforced composite materials fabricated by the powder metallurgy technique.

Numerical and Experimental Characterization of a Composite Secondary Bonded Adhesive Lap Joint Using the Ultrasonics method

NASA Astrophysics Data System (ADS)

Kumar, M. R.; Ghosh, A.; Karuppannan, D.

2018-05-01

The construction of aircraft using advanced composites have become very popular during the past two decades, in which many innovative manufacturing processes, such as cocuring, cobonding, and secondary bonding processes, have been adopted. The secondary bonding process has become less popular than the other two ones because of nonavailability of process database and certification issues. In this article, an attempt is made to classify the quality of bonding using nondestructive ultrasonic inspection methods. Specimens were prepared and tested using the nondestructive ultrasonic Through Transmission (TT), Pulse Echo (PE), and air coupled guided wave techniques. It is concluded that the ultrasonic pulse echo technique is the best one for inspecting composite secondary bonded adhesive joints.

Portable wireless ultrasonic systems for remote inspection

NASA Astrophysics Data System (ADS)

Zhong, C. H.; Croxford, A. J.; Wilcox, P. D.

2015-03-01

The weight and power storage of conventional wire and active wireless systems limit their applications to composite structures such as wind turbines and aerospace structures. In this paper, a structurally-integrated, inert, wireless guided wave system for rapid composite inspection is demonstrated. The wireless interface is based on electromagnetic coupling between three coils, one of which is physically connected to an ultrasonic piezoelectric transducer and embedded in the structure, while the other two are in a separate probing unit. Compact encapsulated sensor units are designed, built and successfully embedded into carbon fibre composite panel at manufacture. Chirp-based excitation is used to enable single-shot measurements with high signal-to-noise ratios to be obtained. Results from sensors embedded in carbon fibre reinforced composite panel show that signal amplitude obtained by embedding the sensor into composite is almost twice that of a surface-bonded sensor. The promising results indicate that the developed sensor can be potentially used for impact damage in a large composite structure.

Ultrasonic guided wave monitoring of composite wing skin-to-spar bonded joints in aerospace structures

NASA Astrophysics Data System (ADS)

Matt, Howard; Bartoli, Ivan; Lanza di Scalea, Francesco

2005-10-01

The monitoring of adhesively bonded joints by ultrasonic guided waves is the general topic of this paper. Specifically, composite-to-composite joints representative of the wing skin-to-spar bonds of unmanned aerial vehicles (UAVs) are examined. This research is the first step towards the development of an on-board structural health monitoring system for UAV wings based on integrated ultrasonic sensors. The study investigates two different lay-ups for the wing skin and two different types of bond defects, namely poorly cured adhesive and disbonded interfaces. The assessment of bond state is based on monitoring the strength of transmission through the joints of selected guided modes. The wave propagation problem is studied numerically by a semi-analytical finite element method that accounts for viscoelastic damping, and experimentally by ultrasonic testing that uses small PZT disks preferably exciting and detecting the single-plate s0 mode. Both the models and the experiments confirm that the ultrasonic energy transmission through the joint is highly dependent on the bond conditions, with defected bonds resulting in increased transmission strength. Large sensitivity to the bond conditions is found at mode coupling points, as a result of the large interlayer energy transfer.

Effect of gold wire bonding process on angular correlated color temperature uniformity of white light-emitting diode.

PubMed

Wu, Bulong; Luo, Xiaobing; Zheng, Huai; Liu, Sheng

2011-11-21

Gold wire bonding is an important packaging process of lighting emitting diode (LED). In this work, we studied the effect of gold wire bonding on the angular uniformity of correlated color temperature (CCT) in white LEDs whose phosphor layers were coated by freely dispersed coating process. Experimental study indicated that different gold wire bonding impacts the geometry of phosphor layer, and it results in different fluctuation trends of angular CCT at different spatial planes in one LED sample. It also results in various fluctuating amplitudes of angular CCT distributions at the same spatial plane for samples with different wire bonding angles. The gold wire bonding process has important impact on angular uniformity of CCT in LED package. © 2011 Optical Society of America

Comparison of three different orthodontic wires for bonded lingual retainer fabrication

PubMed Central

Uysal, Tancan; Gul, Nisa; Alan, Melike Busra; Ramoglu, Sabri Ilhan

2012-01-01

Objective We evaluated the detachment force, amount of deformation, fracture mode, and pull-out force of 3 different wires used for bonded lingual retainer fabrication. Methods We tested 0.0215-inch five-stranded wire (PentaOne, Masel; group I), 0.016 × 0.022-inch dead-soft eight-braided wire (Bond-A-Braid, Reliance; group II), and 0.0195-inch dead-soft coaxial wire (Respond, Ormco; group III). To test detachment force, deformation, and fracture mode, we embedded 94 lower incisor teeth in acrylic blocks in pairs. Retainer wires were bonded to the teeth and vertically directed force was applied to the wire. To test pull-out force, wires were embedded in composite that was placed in a hole at the center of an acrylic block. Tensile force was applied along the long axis of the wire. Results Detachment force and mode of fracture were not different between groups. Deformation was significantly higher in groups II and III than in group I (p < 0.001). Mean pull-out force was significantly higher for group I compared to groups II and III (p < 0.001). Conclusions Detachment force and fracture mode were similar for all wires, but greater deformations were seen in dead-soft wires. Wire pull-out force was significantly higher for five-stranded coaxial wire than for the other wires tested. Five-stranded coaxial wires are suggested for use in bonded lingual retainers. PMID:23112930

Performance of PIN-PMN-PT Single Crystal Piezoelectric versus PZT8 Piezoceramic Materials in Ultrasonic Transducers

NASA Astrophysics Data System (ADS)

DeAngelis, D. A.; Schulze, G. W.

The recent advancements in the manufacturing of single crystal PIN-PMN-PT piezoelectric materials now make them a cost-competitive alternative to PZT4 and PZT8 (Navy Types I and III) piezoceramic materials, which have been the workhorse of power ultrasonic applications (e.g., welding, cutting, sonar, etc.) for over 50 years. Although there are great benefits to the use of single crystal materials with respect to high output, as well as added actuating and sensing abilities, many transducer designers are still reluctant to explore these materials due to inadequate design guidelines for substituting the familiar PZT materials; for example, what are the implications of the higher capacitance, sensitivity to chipping/cracks, aging effects, frequency shifts, or how much preload can be used are all common questions. This research is a case study on the performance of identical ultrasonic transducer bodies, used for semiconductor wire bonding, assembled with either PZT8 or PIN-PMN-PT piezo material. The main purpose of the study is to establish rule-of-thumb design guidelines for direct substitution of single crystal materials in existing PZT8 transducer designs, along with a side-by-side performance comparison to highlight benefits. Several metrics are investigated such as impedance, frequency, displacement gain, quality factor and electromechanical coupling factor.

Performance of PZT8 Versus PZT4 Piezoceramic Materials in Ultrasonic Transducers

NASA Astrophysics Data System (ADS)

DeAngelis, Dominick A.; Schulze, Gary W.

PZT8 and PZT4 are the common "hard" piezoceramic materials used in power ultrasonic transducers (e.g., welding, cutting, sonar, etc.). PZT8 is perceived as the better choice for resonant devices, primarily due to its higher mechanical quality factor Qm. PZT8 is also considered a "harder" material compared to PZT4, since it has better stability at higher preloads and drive levels. Many transducer designers never consider PZT4 for their applications, even though it has clear advantages such as higher output (i.e., higher d33). Even the perceived advantage of PZT8 regarding Qm may not be significant for most Langevin, bolted stack type transducers if the mechanical joint losses dominate. This research is a case study on the performance of identical ultrasonic transducers used for semiconductor wire bonding, assembled with either PZT8 or PZT4 materials. The main purpose of the study is to establish rule-of-thumb transducer design guidelines for the selection of PZT8 versus PZT4 materials. Several metrics are investigated such as impedance, frequency, capacitance, dielectric loss, Qm, heating, displacement gain, and electro-mechanical coupling factor. The experimental and theoretical research methods include Bode plots, thermal IR camera imaging, scanning laser vibrometry and coupled-field finite element analysis.

Advanced Bode Plot Techniques for Ultrasonic Transducers

NASA Astrophysics Data System (ADS)

DeAngelis, D. A.; Schulze, G. W.

The Bode plot, displayed as either impedance or admittance versus frequency, is the most basic test used by ultrasonic transducer designers. With simplicity and ease-of-use, Bode plots are ideal for baseline comparisons such as spacing of parasitic modes or impedance, but quite often the subtleties that manifest as poor process control are hard to interpret or are nonexistence. In-process testing of transducers is time consuming for quantifying statistical aberrations, and assessments made indirectly via the workpiece are difficult. This research investigates the use of advanced Bode plot techniques to compare ultrasonic transducers with known "good" and known "bad" process performance, with the goal of a-priori process assessment. These advanced techniques expand from the basic constant voltage versus frequency sweep to include constant current and constant velocity interrogated locally on transducer or tool; they also include up and down directional frequency sweeps to quantify hysteresis effects like jumping and dropping phenomena. The investigation focuses solely on the common PZT8 piezoelectric material used with welding transducers for semiconductor wire bonding. Several metrics are investigated such as impedance, displacement/current gain, velocity/current gain, displacement/voltage gain and velocity/voltage gain. The experimental and theoretical research methods include Bode plots, admittance loops, laser vibrometry and coupled-field finite element analysis.

Reliability Criteria for Thick Bonding Wire.

PubMed

Dagdelen, Turker; Abdel-Rahman, Eihab; Yavuz, Mustafa

2018-04-17

Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire.

Reliability Criteria for Thick Bonding Wire

PubMed Central

Yavuz, Mustafa

2018-01-01

Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire. PMID:29673194

Research on Melt Degassing Processes of High Conductivity Hard Drawn Aluminum Wire

NASA Astrophysics Data System (ADS)

Xu, Xuexia; Feng, Yanting; Wang, Qing; Li, Wenbin; Fan, Hui; Wang, Yong; Li, Guowei; Zhang, Daoqian

2018-03-01

Degassing effects of ultrasonic and vacuum processes on high conductivity hard drawn aluminum melt were studied. Results showed that the degassing efficiency improved with the increase of ultrasonic power within certain range, stabilizing at 70% with 240W. For vacuum degassing process, hydrogen content of aluminum melt decreased with the loading time and was linear with logarithm of vacuum degree. Comparison of degassing effects of ultrasonic, vacuum, vacuum-ultrasonic degassing process showed that vacuum-ultrasonic process presented optimal effect.

An Ultrasonic Technique to Determine the Residual Strength of Adhesive Bonds

NASA Technical Reports Server (NTRS)

Achenbach, J. D.; Tang, Z.

1999-01-01

In this work, ultrasonic techniques to nondestructively evaluate adhesive bond degradation have been studied. The key to the present approach is the introduction of an external factor which pulls the adhesive bond in the nonlinear range, simultaneously with the application of an ultrasonic technique. With the aid of an external static tensile loading, a superimposed longitudinal wave has.been used to obtain the slopes of the stress-strain curve of an adhesive bond at a series of load levels. The critical load, at which a reduction of the slope is detected by the superimposed longitudinal wave, is an indication of the onset of nonlinear behavior of the adhesive bond, and therefore of bond degradation. This approach has been applied to the detection of adhesive bond degradation induced by cyclic fatigue loading. Analogously to the longitudinal wave case, a superimposed shear wave has been used to obtain the effective shear modulus of adhesive layers at different shear load levels. The onset of the nonlinear behavior of an adhesive bond under shear loading has been detected by the use of a superimposed shear wave. Experiments show that a longitudinal wave can also detect the nonlinear behavior when an adhesive bond is subjected to shear loading. An optimal combination of ultrasonic testing and mechanical loading methods for the detection of degradation related nonlinear behavior of adhesive bonds has been discussed. For the purpose of a practical application, an ultrasonic technique that uses a temperature increase as an alternative to static loading has also been investigated. A general strain-temperature correspondence principle that relates a mechanical strain to a temperature has been presented. Explicit strain-temperature correspondence relations for both the tension and shear cases have been derived. An important parameter which quantifies the relation between the wave velocity and temperature has been defined. This parameter, which is indicative of adhesive bond nonlinearity and which can be conveniently obtained by an ultrasonic measurement, has been used as an indication of adhesive bond degradation. Experimental results have shown that the temperature increase method is a convenient and productive alternative to static loading. A technique which uses the reflected waveform data to obtain the fundamental ultrasonic parameters (transit time, reflection coefficient and attenuation coefficient) of an adhesive bond has also been presented.

Fine pitch thermosonic wire bonding: analysis of state-of-the-art manufacturing capability

NASA Astrophysics Data System (ADS)

Cavasin, Daniel

1995-09-01

A comprehensive process characterization was performed at the Motorola plastic package assembly site in Selangor, Malaysia, to document the current fine pitch wire bond process capability, using state-of-the-art equipment, in an actual manufacturing environment. Two machines, representing the latest technology from two separate manufacturers, were operated one shift per day for five days, bonding a 132 lead Plastic Quad Flat Pack. Using a test device specifically designed for fine pitch wire bonding, the bonding programs were alternated between 107 micrometers and 92 micrometers pad pitch, running each pitch for a total of 1600 units per machine. Wire, capillary type, and related materials were standardized and commercially available. A video metrology measurement system, with a demonstrated six sigma repeatability band width of 0.51 micrometers , was utilized to measure the bonded units for bond dimensions and placement. Standard Quality Assurance (QA) metrics were also performed. Results indicate that state-of-the-art thermosonic wire bonding can achieve acceptable assembly yields at these fine pad pitches.

The decolouration of methyl orange using aluminum foam, ultrasound and direct electric current

NASA Astrophysics Data System (ADS)

Liu, C. M.; Huang, X. Y.; Zhang, H. Y.; Dai, J. D.; Ning, C. C.

2018-01-01

The decolouration of methyl orange (MO) using aluminum (Al) foam, ultrasound and direct electric current (DC) is investigated. The decolouration rate (DR) of MO using only Al foam is low because there is a passivation oxide layer on the Al foam surface. Due to the low utilization of ultrasound in MO water solution medium, the DR of MO using only ultrasonic irradiation is also poor. The DR of MO is greatly increased when Al foam, ultrasonic irradiation and DC are used together. There is good synergistic effect between Al foam, ultrasound and DC in decolouration of MO. This enhancement of DR may be related to the cavitation, cleaning of Al foam surface and water electrolysis. Due to the surface charge on wire carrying stationary current, Al foam with DC acts like a serious anodes and cathodes and makes water electrolysis giving hydrogen gas to cleavage azo bond. The DC applied on Al foam is beneficial for reductive decolouration of MO. Our results show that DC is a new way for the reductive decolouration MO in water.

Comparative Reliability Studies and Analysis of Au, Pd-Coated Cu and Pd-Doped Cu Wire in Microelectronics Packaging

PubMed Central

Chong Leong, Gan; Uda, Hashim

2013-01-01

This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (Do) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, β of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires. PMID:24244344

Aluminum-Scandium: A Material for Semiconductor Packaging

NASA Astrophysics Data System (ADS)

Geissler, Ute; Thomas, Sven; Schneider-Ramelow, Martin; Mukhopadhyay, Biswajit; Lang, Klaus-Dieter

2016-10-01

A well-known aluminum-scandium (Al-Sc) alloy, already used in lightweight sports equipment, is about to be established for use in electronic packaging. One application for Al-Sc alloy is manufacture of bonding wires. The special feature of the alloy is its ability to harden by precipitation. The new bonding wires with electrical conductivity similar to pure Al wires can be processed on common wire bonders for aluminum wedge/wedge (w/w) bonding. The wires exhibit very fine-grained microstructure. Small Al3Sc particles are the main reason for its high strength and prevent recrystallization and grain growth at higher temperatures (>150°C). After the wire-bonding process, the interface is well closed. Reliability investigations by active power cycling demonstrated considerably improved lifetime compared with pure Al heavy wires. Furthermore, the Al-Sc alloy was sputter-deposited onto silicon wafer to test it as chip metallization in copper (Cu) ball/wedge bonding technology. After deposition, the layers exhibited fine-grained columnar structure and small coherent Al3Sc particles with dimensions of a few nanometers. These particles inhibit softening processes such as Al splashing in fine wire bonding processes and increase the thickness of remnant Al under the copper balls to 85% of the initial thickness.

Evaluating Thermally Damaged Polyimide Insulated Wiring (MIL-W-81381) with Ultrasound

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Anastasi, Robert F.

2002-01-01

A series of experiments to investigate the use of ultrasound for measuring wire insulation have been conducted. Initial laboratory tests were performed on MIL-W-81381/7,/12, and /21 aviation wire, a wire that has polyimide (Kapton Registered Trademark) layers for insulation. Samples of this wiring were exposed to 370C temperatures for different periods of time to induce a range of thermal damage. For each exposure, 12 samples of each gauge (12, 16, and 20 gauges) were processed. The velocity of the lowest order axisymmetric ultrasonic guided mode, a mode that is sensitive to the geometry and stiffness of the wire conductor and insulation, was measured. The phase velocity for the 20-gauge MIL-W-81381/7 wire had a baseline value of 3023 +/- 78 m/s. After exposure to the high temperatures, the wire's phase velocity rapidly increased, and reached an asymptotic value of 3598 +/- 20 m/s after 100 hours exposure. Similar behavior was measured for the 16 gauge MIL-W-81381/21 wire and 12 gauge MIL-W-81381/12 wire which had baseline values of 3225 +/- 22 m/s and 3403 +/- 33 m/s respectively, and reached asymptotic values of 3668 +/- 19 m/s, and 3679 +/- 42 m/s respectively. These measured velocity changes represent changes of 19, 14, and 8 percent respectively for the 20, 16, and 12 gauge wires. Finally, some results for a wire with an ethylene tetrafluoroethylene insulation are reported. Qualitatively similar behaviors are noted ultrasonically.

Development and Status of Cu Ball/Wedge Bonding in 2012

NASA Astrophysics Data System (ADS)

Schneider-Ramelow, Martin; Geißler, Ute; Schmitz, Stefan; Grübl, Wolfgang; Schuch, Bernhard

2013-03-01

Starting in the 1980s and continuing right into the last decade, a great deal of research has been published on Cu ball/wedge (Cu B/W) wire bonding. Despite this, the technology has not been established in industrial manufacturing to any meaningful extent. Only spikes in the price of Au, improvements in equipment and techniques, and better understanding of the Cu wire-bonding process have seen Cu B/W bonding become more widespread—initially primarily for consumer goods manufacturing. Cu wire bonding is now expected to soon be used for at least 20% of all ball/wedge-bonded components, and its utilization in more sophisticated applications is around the corner. In light of this progress, the present paper comprehensively reviews the existing literature on this topic and discusses wire-bonding materials, equipment, and tools in the ongoing development of Cu B/W bonding technology. Key bonding techniques, such as flame-off, how to prevent damage to the chip (cratering), and bond formation on various common chip and substrate finishes are also described. Furthermore, apart from discussing quality assessment of Cu wire bonds in the initial state, the paper also provides an overview of Cu bonding reliability, in particular regarding Cu balls on Al metalization at high temperatures and in humidity (including under the influence of halide ions).

Ultrasonic and radiographic evaluation of advanced aerospace materials: Ceramic composites

NASA Technical Reports Server (NTRS)

Generazio, Edward R.

1990-01-01

Two conventional nondestructive evaluation techniques were used to evaluate advanced ceramic composite materials. It was shown that neither ultrasonic C-scan nor radiographic imaging can individually provide sufficient data for an accurate nondestructive evaluation. Both ultrasonic C-scan and conventional radiographic imaging are required for preliminary evaluation of these complex systems. The material variations that were identified by these two techniques are porosity, delaminations, bond quality between laminae, fiber alignment, fiber registration, fiber parallelism, and processing density flaws. The degree of bonding between fiber and matrix cannot be determined by either of these methods. An alternative ultrasonic technique, angular power spectrum scanning (APSS) is recommended for quantification of this interfacial bond.

Interconnect mechanisms in microelectronic packaging

NASA Astrophysics Data System (ADS)

Roma, Maria Penafrancia C.

Global economic, environmental and market developments caused major impact in the microelectronics industry. Astronomical rise of gold metal prices over the last decade shifted the use of copper and silver alloys as bonding wires. Environmental legislation on the restriction of the use of Pb launched worldwide search for lead-free solders and platings. Finally, electrical and digital uses demanded smaller, faster and cheaper devices. Ultra-fine pitch bonding, decreasing bond wire sizes and hard to bond substrates have put the once-robust stitch bond in the center of reliability issues due to stitch bond lift or open wires .Unlike the ball bond, stitch bonding does not lead to intermetallic compound formation but adhesion is dependent on mechanical deformation, interdiffusion, solid solution formation, void formation and mechanical interlocking depending on the wire material, bond configuration, substrate type , thickness and surface condition. Using Au standoff stitch bonds on NiPdAu plated substrates eliminated stitch bond lift even when the Au and Pd layers are reduced. Using the Matano-Boltzmann analysis on a STEM (Scanning Transmission Analysis) concentration profile the interdiffusion coefficient is measured to be 10-16 cm 2/s. Wire pull strength data showed that the wire pull strength is 0.062N and increases upon stress testing. Meanwhile, coating the Cu wire with Pd, not only increases oxidation resistance but also improved adhesion due to the formation of a unique interfacial adhesion layers. Adhesion strength as measured by pull showed the Cu wire bonded to Ag plated Cu substrate (0.132N) to be stronger than the Au wire bonded on the same substrate (0.124N). Ag stitch bonded to Au is predicted to be strong but surface modification made the adhesion stronger. However, on the Ag ball bonded to Al showed multiple IMC formation with unique morphology exposed by ion milling and backscattered scanning electron microscopy. Adding alloying elements in the Ag wire alloy showed differences in adhesion strength and IMC formation. Bond strength by wire pull testing showed the 95Ag alloy with higher values while shear bond testing showed the 88Ag higher bond strength. Use of Cu pillars in flip chips and eutectic bonding in wafer level chip scale packages are direct consequences of diminishing interconnect dimension as a result of the drive for miniaturization. The combination of Cu-Sn interdiffusion, Kirkendall mechanism and heterogeneous vacancy precipitation are the main causes of IMC and void formation in Cu pillar - Sn solder - Cu lead frame sandwich structure. However, adding a Ni barrier agent showed less porous IMC layer as well as void formation as a result of the modified Cu and Sn movement well as the void formation. Direct die to die bonding using Al-Ge eutectic bonds is necessary when 3D integration is needed to reduce the footprint of a package. Hermeticity and adhesion strength are a function of the Al/Ge thickness ratio, bonding pressure, temperature and time. Scanning Electron Microscope (SEM) and Focused Ion Beam (FIB) allowed imaging of interfacial microstructures, porosity, grain morphology while Scanning Transmission Electron microscope (STEM) provided diffusion profile and confirmed interdiffusion. Ion polishing technique provided information on porosity and when imaged using backscattered mode, grain structure confirmed mechanical deformation of the bonds. Measurements of the interfacial bond strength are made by wire pull tests and ball shear tests based on existing industry standard tests. However, for the Al-Ge eutectic bonds, no standard strength is available so a test is developed using the stud pull test method using the Dage 4000 Plus to yield consistent results. Adhesion strengths of 30-40 MPa are found for eutectic bonded packages however, as low as 20MPa was measured in low temperature bonded areas.

Evaluation of Die-Attach Bonding Using High-Frequency Ultrasonic Energy for High-Temperature Application

NASA Astrophysics Data System (ADS)

Lee, Jong-Bum; Aw, Jie-Li; Rhee, Min-Woo

2014-09-01

Room-temperature die-attach bonding using ultrasonic energy was evaluated on Cu/In and Cu/Sn-3Ag metal stacks. The In and Sn-3Ag layers have much lower melting temperatures than the base material (Cu) and can be melted through the heat generated during ultrasonic bonding, forming intermetallic compounds (IMCs). Samples were bonded using different ultrasonic powers, bonding times, and forces and subsequently aged at 300°C for 500 h. After aging, die shear testing was performed and the fracture surfaces were inspected by scanning electron microscopy. Results showed that the shear strength of Cu/In joints reached an upper plateau after 100 h of thermal aging and remained stable with aging time, whereas that of the Cu/Sn-3Ag joints decreased with increasing aging time. η-Cu7In4 and (Cu,Au)11In9 IMCs were observed at the Cu/In joint, while Cu3Sn and (Ag,Cu)3Sn IMCs were found at the Cu/Sn-3Ag joint after reliability testing. As Cu-based IMCs have high melting temperatures, they are highly suitable for use in high-temperature electronics, but can be formed at room temperature using an ultrasonic approach.

Shear bond strength of different retainer wires and bonding adhesives in consideration of the pretreatment process.

PubMed

Reicheneder, Claudia; Hofrichter, Bernd; Faltermeier, Andreas; Proff, Peter; Lippold, Carsten; Kirschneck, Christian

2014-11-28

We aimed to compare the shear bond strength (SBS) of three different retainer wires and three different bonding adhesives in consideration of the pretreatment process of enamel surface sandblasting. 400 extracted bovine incisors were divided into 10 groups of 20 paired specimens each. 10 specimens of each group were pretreated by enamel sandblasting. The retainer wires Bond-A-Braid™, GAC-Wildcat®-Twistflex and everStick®ORTHO were bonded to the teeth with the adhesives Transbond™-LR, Tetric-EvoFlow™ and Stick®FLOW and then debonded measuring the SBS. While sandblasting generally increased SBS for all tested combinations, the retainer wires bonded with Transbond™-LR showed the highest SBS both with and without prior sandblasting. Significantly lower SBS were found for Tetric-EvoFlow™ that were comparable to those for everStick®ORTHO. Pretreatment of enamel surfaces by sandblasting increased the SBS of all retainer-wires. Transbond™-LR showed the best results compared to Tetric-EvoFlow™ and everStick®ORTHO, while all combinations used provided sufficient bonding strengths for clinical use.

Ultrasonic assessment of bonding integrity in foam-based hybrid composite materials

NASA Astrophysics Data System (ADS)

Chen, M. Y.; Ko, R. T.; Hoppe, W. C.; Blackshire, J. L.

2013-01-01

Ultrasonic assessment of the bonding integrity between a composite layer and a foam substrate in foam-based hybrid composite materials was explored. The challenges of this task are: (1) the foam has air-like acoustic impedance and (2) contact surface wave generation on polymer matrix composites (PMC) is not conventional. To meet these challenges, a novel wedge made of a low velocity material was developed. The results showed that the bonding condition in these composites can be identified by monitoring the amplitude of the ultrasonic signals received.

Wood Bond Testing

NASA Technical Reports Server (NTRS)

1989-01-01

A joint development program between Hartford Steam Boiler Inspection Technologies and The Weyerhaeuser Company resulted in an internal bond analyzer (IBA), a device which combines ultrasonics with acoustic emission testing techniques. It is actually a spinoff from a spinoff, stemming from a NASA Lewis invented acousto-ultrasonic technique that became a system for testing bond strength of composite materials. Hartford's parent company, Acoustic Emission Technology Corporation (AET) refined and commercialized the technology. The IBA builds on the original system and incorporates on-line process control systems. The IBA determines bond strength by measuring changes in pulsar ultrasonic waves injected into a board. Analysis of the wave determines the average internal bond strength for the panel. Results are displayed immediately. Using the system, a mill operator can adjust resin/wood proportion, reduce setup time and waste, produce internal bonds of a consistent quality and automatically mark deficient products.

Investigation of Adhesive Bond Cure Conditions using Nonlinear Ultrasonic Methods

NASA Technical Reports Server (NTRS)

Berndt, Tobias P.; Green, Robert E., Jr.

1999-01-01

The objective of this presentation is to investigate various cure conditions of adhesive bonds using nonlinear ultrasonic methods with water coupling. Several samples were used to obtain normal incidence, oblique incidence, and wave mixing.

Ultrasonic Inspection to Quantify Failure Pathologies of Crimped Electrical Connections

NASA Technical Reports Server (NTRS)

Cramer, K. Elliott; Perey, Daniel F.; Yost, William T.

2014-01-01

Previous work has shown that ultrasonic inspection provides a means of assessing electrical crimp quality that ensures the electrical and mechanical integrity of an initial crimp before the installation process is completed. The amplitude change of a compressional ultrasonic wave propagating at right angles to the wire axis and through the junction of a crimp termination was shown to correlate with the results of destructive pull tests, which is a standard for assessing crimp wire junction quality. Of additional concern are crimps made at high speed assembly lines for wiring harnesses, which are used for critical applications, such as in aircraft. During high-speed assembly it is possible that many faulty crimps go undetected until long after assembly, and fail in service. The position and speed of the crimping jaw become factors as the high-speed crimp is formed. The work presented in this paper is designed to cover the more difficult and more subtle area of high-speed crimps by taking into account the rate change of the measurements. Building on the previous work, we present an analysis methodology, based on transmitted ultrasonic energy and timing of the first received pulse that is shown to correlate to the gauge of the crimp/ferrule combination and the position of the crimping jaw. Results demonstrating the detectability of a number of the crimp failure pathologies, such as missing strands, partially inserted wires and incomplete crimp compression, are presented. The ability of this technique to estimate crimp height, a mechanical measure of crimp quality, is discussed.

Ultrasonic inspection to quantify failure pathologies of crimped electrical connections

NASA Astrophysics Data System (ADS)

Cramer, K. Elliott; Perey, Daniel F.; Yost, William T.

2015-03-01

Previous work has shown that ultrasonic inspection provides a means of assessing electrical crimp quality that ensures the electrical and mechanical integrity of an initial crimp before the installation process is completed. The amplitude change of a compressional ultrasonic wave propagating at right angles to the wire axis and through the junction of a crimp termination was shown to correlate with the results of destructive pull tests, which is a standard for assessing crimp wire junction quality. Of additional concern are crimps made at high speed assembly lines for wiring harnesses, which are used for critical applications, such as in aircraft. During high-speed assembly it is possible that many faulty crimps go undetected until long after assembly, and fail in service. The position and speed of the crimping jaw become factors as the high-speed crimp is formed. The work presented in this paper is designed to cover the more difficult and more subtle area of high-speed crimps by taking into account the rate change of the measurements. Building on the previous work, we present an analysis methodology, based on transmitted ultrasonic energy and timing of the first received pulse that is shown to correlate to the gauge of the crimp/ferrule combination and the position of the crimping jaw. Results demonstrating the detectability of a number of the crimp failure pathologies, such as missing strands, partially inserted wires and incomplete crimp compression, are presented. The ability of this technique to estimate crimp height, a mechanical measure of crimp quality, is discussed.

77 FR 5728 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-06

... between bonding lead and the harness, due to over length of the bonding lead. As the affected wire is not... chafing of the wires, and corrective actions, if necessary. We are proposing this AD to detect and correct contact or chafing of wires and bonding leads which, if not detected could be a source of sparks in the...

Bi-directional ultrasonic wave coupling to FBGs in continuously bonded optical fiber sensing.

PubMed

Wee, Junghyun; Hackney, Drew; Bradford, Philip; Peters, Kara

2017-09-01

Fiber Bragg grating (FBG) sensors are typically spot-bonded onto the surface of a structure to detect ultrasonic waves in laboratory demonstrations. However, to protect the rest of the optical fiber from any environmental damage during real applications, bonding the entire length of fiber, called continuous bonding, is commonly done. In this paper, we investigate the impact of continuously bonding FBGs on the measured Lamb wave signal. In theory, the ultrasonic wave signal can bi-directionally transfer between the optical fiber and the plate at any adhered location, which could potentially produce output signal distortion for the continuous bonding case. Therefore, an experiment is performed to investigate the plate-to-fiber and fiber-to-plate signal transfer, from which the signal coupling coefficient of each case is theoretically estimated based on the experimental data. We demonstrate that the two coupling coefficients are comparable, with the plate-to-fiber case approximately 19% larger than the fiber-to-plate case. Finally, the signal waveform and arrival time of the output FBG responses are compared between the continuous and spot bonding cases. The results indicate that the resulting Lamb wave signal output is only that directly detected at the FBG location; however, a slight difference in signal waveform is observed between the two bonding configurations. This paper demonstrates the practicality of using continuously bonded FBGs for ultrasonic wave detection in structural health monitoring (SHM) applications.

Non-bonded ultrasonic transducer

DOEpatents

Eoff, J.M.

1984-07-06

A mechanically assembled non-bonded ultrasonic transducer includes a substrate, a piezoelectric film, a wetting agent, a thin metal electrode, and a lens held in intimate contact by a mechanical clamp. No epoxy or glue is used in the assembly of this device.

The Influence of Pd-Doped Au Wire Bonding on HAZ Microstructure and Looping Profile in Micro-Electromechanical Systems (MEMS) Packaging

NASA Astrophysics Data System (ADS)

Ismail, Roslina; Omar, Ghazali; Jalar, Azman; Majlis, Burhanuddin Yeop

2015-07-01

Wire bonding processes has been widely adopted in micro-electromechanical systems (MEMS) packaging especially in biomedical devices for the integration of components. In the first process sequence in wire bonding, the zone along the wire near the melted tips is called the heat-affected zone (HAZ). The HAZ plays an important factor that influenced the looping profiles of wire bonding process. This paper investigates the effect of dopants on microstructures in the HAZ. One precent palladium (Pd) was added to the as-drawn 4N gold wire and annealed at 600°C. The addition of Pd was able to moderate the grain growth in the HAZ by retarding the heat propagation to the wire. In the formation of the looping profile, the first bending point of the looping is highly associated with the length of the HAZ. The alloyed gold wire (2N gold) has a sharp angle at a distance of about 30 m from the neck of the wire with a measured bending radius of about 40 mm and bending angle of about 40° clockwise from vertical axis, while the 4N gold wire bends at a longer distance. It also shows that the HAZ for 4N gold is longer than 2N gold wire.

Influence of aluminum oxide film on thermocompression bonding of gold wire to evaporated aluminum film

NASA Technical Reports Server (NTRS)

Iwata, S.; Ishizaka, A.; Yamamoto, H.

1984-01-01

The influence of Al surface condition on the thermocompression bonding of Au wires to Al electrodes for integrated electric circuits was studied. Au wires were connected to Al electrodes by nail-head bonding after various Al surface treatments. Bonding was evaluated by measuring the wire pull strength and fraction of the number of failures at Au-Al bonds to the total number of failures. Dependence of the fraction on applied load was derived theoretically with a parameter named critical load to take into consideration the differences in Al surface condition. The relation also held explicately for various surface treatments. Characterization of the Al surface was carried out by electron microscopy for chemical analysis.

Non-bonded piezoelectric ultrasonic transducer

DOEpatents

Eoff, James M.

1985-01-01

A mechanically assembled non-bonded ultrasonic transducer includes a substrate, a piezoelectric film, a wetting agent, a thin metal electrode, and a lens held in intimate contact by a mechanical clamp. No epoxy or glue is used in the assembly of this device.

Tensile test and interface retention forces between wires and composites in lingual fixed retainers.

PubMed

Paolone, Maria Giacinta; Kaitsas, Roberto; Obach, Patricia; Kaitsas, Vasilios; Benedicenti, Stefano; Sorrenti, Eugenio; Barberi, Fabrizio

2015-06-01

In daily orthodontic clinical practice retention is very important, and lingual retainers are part of this challenge. The failure of lingual retainers may be due to many factors. The aim of this study was to assess the retention forces and mechanical behavior of different types of wires matched with different kinds of composites in lingual retainers. A tensile test was performed on cylindrical composite test specimens bonded to orthodontic wires. The specimens were constructed using four different wires: a straight wire (Remanium .016×.022″ Dentaurum), two round twisted wires (Penta One .0215″ Masel, Gold Penta Twisted .0215″ Gold N'braces) and a rectangular braided wire (D-Rect .016×.022″ Ormco); and three composites: two micro-hybrids (Micro-Hybrid Enamel Plus HFO Micerium, and Micro-Hybrid SDR U Dentsply) and a micro-nano-filled composite (Micro-Nano-Filled Transbond LR 3M). The test was performed at a speed of 10mm/min on an Inström device. The wire was fixed with a clamp. The results showed that the bonding between wires and composites in lingual fixed retainers seemed to be lowest for rectangular smooth wires and increased in round twisted and rectangular twisted wires where the bonding was so strong that the maximum tension/bond strength was greater than the ultimate tensile strength of the wire. The highest values were in rectangular twisted wires. Concerning the composites, hybrid composites had the lowest interface bonding values and broke very quickly, while the nano- and micro-composites tolerated stronger forces and displayed higher bonding values. The best results were observed with the golden twisted wire and reached 21.46 MPa with the Transbond composite. With the rectangular braided wire the retention forces were so high that the Enamel Plus composite fractured when the load exceeded 154.6 N/MPa. When the same wire was combined with the Transbond LR either the wire or the composite broke when the force exceeded 240 N. The results of this study show that, when selecting a lingual retainer in daily clinical practice, not only must the patient's compliance and dependability be considered but also the mechanical properties and composition of different combinations of composites and wires. Copyright © 2015 CEO. Published by Elsevier Masson SAS. All rights reserved.

Biofilm formation on stainless steel and gold wires for bonded retainers in vitro and in vivo and their susceptibility to oral antimicrobials.

PubMed

Jongsma, Marije A; Pelser, Floris D H; van der Mei, Henny C; Atema-Smit, Jelly; van de Belt-Gritter, Betsy; Busscher, Henk J; Ren, Yijin

2013-05-01

Bonded retainers are used in orthodontics to maintain treatment result. Retention wires are prone to biofilm formation and cause gingival recession, bleeding on probing and increased pocket depths near bonded retainers. In this study, we compare in vitro and in vivo biofilm formation on different wires used for bonded retainers and the susceptibility of in vitro biofilms to oral antimicrobials. Orthodontic wires were exposed to saliva, and in vitro biofilm formation was evaluated using plate counting and live/dead staining, together with effects of exposure to toothpaste slurry alone or followed by antimicrobial mouthrinse application. Wires were also placed intra-orally for 72 h in human volunteers and undisturbed biofilm formation was compared by plate counting and live/dead staining, as well as by denaturing gradient gel electrophoresis for compositional differences in biofilms. Single-strand wires attracted only slightly less biofilm in vitro than multi-strand wires. Biofilms on stainless steel single-strand wires however, were much more susceptible to antimicrobials from toothpaste slurries and mouthrinses than on single-strand gold wires and biofilms on multi-strand wires. Also, in vivo significantly less biofilm was found on single-strand than on multi-strand wires. Microbial composition of biofilms was more dependent on the volunteer involved than on wire type. Biofilms on single-strand stainless steel wires attract less biofilm in vitro and are more susceptible to antimicrobials than on multi-strand wires. Also in vivo, single-strand wires attract less biofilm than multi-strand ones. Use of single-strand wires is preferred over multi-strand wires, not because they attract less biofilm, but because biofilms on single-strand wires are not protected against antimicrobials as in crevices and niches as on multi-strand wires.

Reliability of copper wire bonds on a novel over-pad metallization

NASA Astrophysics Data System (ADS)

Kawashiro, Fumiyoshi; Itoh, Satoshi; Maeda, Takehiko; Hirose, Tetsuya; Yajima, Akira; Etoh, Takaki; Nishikawa, Hiroshi

2015-05-01

Wire bonding technology is used in most semiconductor products. Recently, high gold prices have forced semiconductor manufacturers to replace Au wires with Cu wires. Because Cu wire bonds are vulnerable to high temperature and humidity, they remain unpopular in automotive and industrial applications with narrow-bond-pad pitches and small deformed ball diameters. To avoid forming the corrosive Cu-rich intermetallic compound Cu9Al4, the use of a Ni/Pd(/Au) over-pad metallization (OPM) structure produced by electroless plating on the Al metallization has been proposed. However, certain technical issues must be overcome, such as variations in the purity and thickness of the plating. To tackle these issues, a novel OPM structure produced by physical vapor deposition is proposed and evaluated in this study.

Finite Element Bond Modeling for Indented Wires in Pretensioned Concrete Crossties

DOT National Transportation Integrated Search

2016-04-12

Indented wires have been increasingly employed by : concrete crosstie manufacturers to improve the bond between : prestressing steel reinforcements and concrete, as bond can : affect several critical performance measures, including transfer : length,...

Nondestructive Evaluation of Adhesive Bonds via Ultrasonic Phase Measurements

NASA Technical Reports Server (NTRS)

Haldren, Harold A.; Perey, Daniel F.; Yost, William T.; Cramer, K. Elliott; Gupta, Mool C.

2016-01-01

The use of advanced composites utilizing adhesively bonded structures offers advantages in weight and cost for both the aerospace and automotive industries. Conventional nondestructive evaluation (NDE) has proved unable to reliably detect weak bonds or bond deterioration during service life conditions. A new nondestructive technique for quantitatively measuring adhesive bond strength is demonstrated. In this paper, an ultrasonic technique employing constant frequency pulsed phased-locked loop (CFPPLL) circuitry to monitor the phase response of a bonded structure from change in thermal stress is discussed. Theoretical research suggests that the thermal response of a bonded interface relates well with the quality of the adhesive bond. In particular, the effective stiffness of the adhesive-adherent interface may be extracted from the thermal phase response of the structure. The sensitivity of the CFPPLL instrument allows detection of bond pathologies that have been previously difficult-to-detect. Theoretical results with this ultrasonic technique on single epoxy lap joint (SLJ) specimens are presented and discussed. This technique has the potential to advance the use of adhesive bonds - and by association, advanced composite structures - by providing a reliable method to measure adhesive bond strength, thus permitting more complex, lightweight, and safe designs.

A Reference-Free and Non-Contact Method for Detecting and Imaging Damage in Adhesive-Bonded Structures Using Air-Coupled Ultrasonic Transducers.

PubMed

Yonathan Sunarsa, Timotius; Aryan, Pouria; Jeon, Ikgeun; Park, Byeongjin; Liu, Peipei; Sohn, Hoon

2017-12-08

Adhesive bonded structures have been widely used in aerospace, automobile, and marine industries. Due to the complex nature of the failure mechanisms of bonded structures, cost-effective and reliable damage detection is crucial for these industries. Most of the common damage detection methods are not adequately sensitive to the presence of weakened bonding. This paper presents an experimental and analytical method for the in-situ detection of damage in adhesive-bonded structures. The method is fully non-contact, using air-coupled ultrasonic transducers (ACT) for ultrasonic wave generation and sensing. The uniqueness of the proposed method relies on accurate detection and localization of weakened bonding in complex adhesive bonded structures. The specimens tested in this study are parts of real-world structures with critical and complex damage types, provided by Hyundai Heavy Industries ® and IKTS Fraunhofer ® . Various transmitter and receiver configurations, including through transmission, pitch-catch scanning, and probe holder angles, were attempted, and the obtained results were analyzed. The method examines the time-of-flight of the ultrasonic waves over a target inspection area, and the spatial variation of the time-of-flight information was examined to visualize and locate damage. The proposed method works without relying on reference data obtained from the pristine condition of the target specimen. Aluminum bonded plates and triplex adhesive layers with debonding and weakened bonding were used to examine the effectiveness of the method.

A Reference-Free and Non-Contact Method for Detecting and Imaging Damage in Adhesive-Bonded Structures Using Air-Coupled Ultrasonic Transducers

PubMed Central

Yonathan Sunarsa, Timotius; Aryan, Pouria; Jeon, Ikgeun; Park, Byeongjin; Liu, Peipei

2017-01-01

Adhesive bonded structures have been widely used in aerospace, automobile, and marine industries. Due to the complex nature of the failure mechanisms of bonded structures, cost-effective and reliable damage detection is crucial for these industries. Most of the common damage detection methods are not adequately sensitive to the presence of weakened bonding. This paper presents an experimental and analytical method for the in-situ detection of damage in adhesive-bonded structures. The method is fully non-contact, using air-coupled ultrasonic transducers (ACT) for ultrasonic wave generation and sensing. The uniqueness of the proposed method relies on accurate detection and localization of weakened bonding in complex adhesive bonded structures. The specimens tested in this study are parts of real-world structures with critical and complex damage types, provided by Hyundai Heavy Industries® and IKTS Fraunhofer®. Various transmitter and receiver configurations, including through transmission, pitch-catch scanning, and probe holder angles, were attempted, and the obtained results were analyzed. The method examines the time-of-flight of the ultrasonic waves over a target inspection area, and the spatial variation of the time-of-flight information was examined to visualize and locate damage. The proposed method works without relying on reference data obtained from the pristine condition of the target specimen. Aluminum bonded plates and triplex adhesive layers with debonding and weakened bonding were used to examine the effectiveness of the method. PMID:29292752

A short review on thermosonic flip chip bonding

NASA Astrophysics Data System (ADS)

Suppiah, Sarveshvaran; Ong, Nestor Rubio; Sauli, Zaliman; Sarukunaselan, Karunavani; Alcain, Jesselyn Barro; Shahimin, Mukhzeer Mohamad; Retnasamy, Vithyacharan

2017-09-01

This review is to study the evolution and key findings, critical technical challenges, solutions and bonding equipment of thermosonic flip chip bonding. Based on the review done, it was found that ultrasonic power, bonding time and force are the three main critical parameters need to be optimized in order to achieve sound and reliable bonding between the die and substrate. A close monitoring of the ultrasonic power helped to prevent over bonding phenomena on flexible substrate. Gold stud bumping is commonly used in thermosonic bonding compared to solder due to its better reliability obtained in the LED and optoelectronic packages. The review comprised short details on the available thermosonic bonding equipment in the semiconductor industry as well.

Reliability Assessment and Activation Energy Study of Au and Pd-Coated Cu Wires Post High Temperature Aging in Nanoscale Semiconductor Packaging.

PubMed

Gan, C L; Hashim, U

2013-06-01

Wearout reliability and high temperature storage life (HTSL) activation energy of Au and Pd-coated Cu (PdCu) ball bonds are useful technical information for Cu wire deployment in nanoscale semiconductor device packaging. This paper discusses the influence of wire type on the wearout reliability performance of Au and PdCu wire used in fine pitch BGA package after HTSL stress at various aging temperatures. Failure analysis has been conducted to identify the failure mechanism after HTSL wearout conditions for Au and PdCu ball bonds. Apparent activation energies (Eaa) of both wire types are investigated after HTSL test at 150 °C, 175 °C and 200 °C aging temperatures. Arrhenius plot has been plotted for each ball bond types and the calculated Eaa of PdCu ball bond is 0.85 eV and 1.10 eV for Au ball bond in 110 nm semiconductor device. Obviously Au ball bond is identified with faster IMC formation rate with IMC Kirkendall voiding while PdCu wire exhibits equivalent wearout and or better wearout reliability margin compare to conventional Au wirebond. Lognormal plots have been established and its mean to failure (t 50 ) have been discussed in this paper.

Ultrasonic Nondestructive Characterization of Adhesive Bonds

NASA Technical Reports Server (NTRS)

Qu, Jianmin

1999-01-01

Adhesives and adhesive joints are widely used in various industrial applications to reduce weight and costs, and to increase reliability. For example, advances in aerospace technology have been made possible, in part, through the use of lightweight materials and weight-saving structural designs. Joints, in particular, have been and continue to be areas in which weight can be trimmed from an airframe through the use of novel attachment techniques. In order to save weight over traditional riveted designs, to avoid the introduction of stress concentrations associated with rivet holes, and to take full advantage of advanced composite materials, engineers and designers have been specifying an ever-increasing number of adhesively bonded joints for use on airframes. Nondestructive characterization for quality control and remaining life prediction has been a key enabling technology for the effective use of adhesive joints. Conventional linear ultrasonic techniques generally can only detect flaws (delamination, cracks, voids, etc) in the joint assembly. However, more important to structural reliability is the bond strength. Although strength, in principle, cannot be measured nondestructively, a slight change in material nonlinearity may indicate the onset of failure. Furthermore, microstructural variations due to aging or under-curing may also cause changes in the third order elastic constants, which are related to the ultrasonic nonlinear parameter of the polymer adhesive. It is therefore reasonable to anticipate a correlation between changes in the ultrasonic nonlinear acoustic parameter and the remaining bond strength. It has been observed that higher harmonics of the fundamental frequency are generated when an ultrasonic wave passes through a nonlinear material. It seems that such nonlinearity can be effectively used to characterize bond strength. Several theories have been developed to model this nonlinear effect. Based on a microscopic description of the nonlinear interface binding force, a quantitative method was presented. Recently, a comparison between the experimental and simulated results based on a similar theoretical model was presented. A through-transmission setup for water immersion mode-converted shear waves was used to analyze the ultrasonic nonlinear parameter of an adhesive bond. In addition, ultrasonic guided waves have been used to analyze adhesive or diffusion bonded joints. In this paper, the ultrasonic nonlinear parameter is used to characterize the curing state of a polymer/aluminum adhesive joint. Ultrasonic through-transmission tests were conducted on samples cured under various conditions. The magnitude of the second order harmonic was measured and the corresponding ultrasonic nonlinear parameter was evaluated. A fairly good correlation between the curing condition and the nonlinear parameter is observed. The results show that the nonlinear parameter might be used as a good indicator of the cure state for adhesive joints.

A cMUT probe for ultrasound-guided focused ultrasound targeted therapy.

PubMed

Gross, Dominique; Coutier, Caroline; Legros, Mathieu; Bouakaz, Ayache; Certon, Dominique

2015-06-01

Ultrasound-mediated targeted therapy represents a promising strategy in the arsenal of modern therapy. Capacitive micromachined ultrasonic transducer (cMUT) technology could overcome some difficulties encountered by traditional piezoelectric transducers. In this study, we report on the design, fabrication, and characterization of an ultrasound-guided focused ultrasound (USgFUS) cMUT probe dedicated to preclinical evaluation of targeted therapy (hyperthermia, thermosensitive liposomes activation, and sonoporation) at low frequency (1 MHz) with simultaneous ultrasonic imaging and guidance (15 to 20 MHz). The probe embeds two types of cMUT arrays to perform the modalities of targeted therapy and imaging respectively. The wafer-bonding process flow employed for the manufacturing of the cMUTs is reported. One of its main features is the possibility of implementing two different gap heights on the same wafer. All the design and characterization steps of the devices are described and discussed, starting from the array design up to the first in vitro measurements: optical (microscopy) and electrical (impedance) measurements, arrays' electroacoustic responses, focused pressure field mapping (maximum peak-to-peak pressure = 2.5 MPa), and the first B-scan image of a wire-target phantom.

Microstructural evolution of SiC joints soldered using Zn-Al filler metals with the assistance of ultrasound.

PubMed

Wu, Bingzhi; Leng, Xuesong; Xiu, Ziyang; Yan, Jiuchun

2018-06-01

SiC ceramics were successfully soldered with the assistance of ultrasound. Two kinds of filler metals, namely non-eutectic Zn-5Al-3Cu and eutectic Zn-5Al alloys, were used. The effects of ultrasonic action on the microstructure and mechanical properties of the soldered joints were investigated. The results showed that ultrasound could promote the wetting and bonding between the SiC ceramic and filler metals within tens of seconds. For the Zn-5Al-3Cu solder, a fully grain-refined structure in the bond layer was obtained as the ultrasonic action time increased. This may lead to a substantial enhancement in the strength of the soldered joints. For the Zn-5Al solder, the shear strength of the soldered joints was only ∼102 MPa when the ultrasonic action time was shorter, and fractures occurred in the brittle lamellar eutectic phases in the center of the bond layer. With increasing ultrasonic action time, the lamellar eutectic phase in the bond layer of SiC joints could be completely transformed to a fine non-lamellar eutectic structure. Meanwhile, the grains in the bond layer were obviously refined. Those results led to the remarkable enhancement of the shear strength of the joints (∼138 MPa) using the Zn-5Al solder, which had approached that enhancement using the Zn-5Al-3Cu solder. The enhanced mechanical properties of the joints were attributed to the significant refinement of the grains and the change in the eutectic structure in the bond layer. Prolonged enhanced heterogeneous nucleation triggered by ultrasonic cavitation is the predominant refinement mechanism of the bond metals of the SiC joints. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of confining pressure due to external jacket of steel plate or shape memory alloy wire on bond behavior between concrete and steel reinforcing bars.

PubMed

Choi, Eunsoo; Kim, Dongkyun; Park, Kyoungsoo

2014-12-01

For external jackets of reinforced concrete columns, shape memory alloy (SMA) wires are easy to install, and they provide active and passive confining pressure; steel plates, on the other hand, only provide passive confining pressure, and their installation on concrete is not convenient because of the requirement of a special device. To investigate how SMA wires distinctly impact bond behavior compared with steel plates, this study conducted push-out bond tests of steel reinforcing bars embedded in concrete confined by SMA wires or steel plates. For this purpose, concrete cylinders were prepared with dimensions of 100 mm x 200 mm, and D-22 reinforcing bars were embedded at the center of the concrete cylinders. External jackets of 1.0 mm and 1.5 mm thickness steel plates were used to wrap the concrete cylinders. Additionally, NiTiNb SMA wire with a diameter of 1.0 mm was wound around the concrete cylinders. Slip of the reinforcing bars due to pushing force was measured by using a displacement transducer, while the circumferential deformation of specimens was obtained by using an extensometer. The circumferential deformation was used to calculate the circumferential strains of the specimens. This study assessed the radial confining pressure due to the external jackets on the reinforcing bars at bond strength from bond stress-slip curves and bond stress-circumferential strain curves. Then, the effects of the radial confining pressure on the bond behavior of concrete are investigated, and an equation is suggested to estimate bond strength using the radial confining pressure. Finally, this study focused on how active confining pressure due to recovery stress of the SMA wires influences bond behavior.

Porous coatings from wire mesh for bone implants

DOEpatents

Sump, Kenneth R.

1986-01-01

A method of coating areas of bone implant elements and the resulting implant having a porous coating are described. Preselected surface areas are covered by a preform made from continuous woven lengths of wire. The preform is compressed and heated to assure that diffusion bonding occurs between the wire surfaces and between the surface boundaries of the implant element and the wire surfaces in contact with it. Porosity is achieved by control of the resulting voids between the bonded wire portions.

Thermoelectric Mechanism and Interface Characteristics of Cyanide-Free Nanogold-Coated Silver Wire

NASA Astrophysics Data System (ADS)

Tseng, Yi-Wei; Hung, Fei-Yi; Lui, Truan-Sheng

2016-01-01

Traditional bath-plated gold contains a cyanide complex, which is an environmental hazard. In response, our study used a green plating process to produce cyanide-free gold-coated silver (cyanide-free ACA) bonding wire that has been proven to be a feasible alternative to gold bonding wire in semiconductor packaging. In this work, ACA wire annealed at 550°C was found to have stable microstructure and superior mechanical properties. Intermetallic compounds Ag2Al and AuAl2 grew from Ag-Au balls and Al pads after aging at 175°C for 500 h. After current testing, ACA wire was found to have improved electrical properties due to equiaxed grain growth. The gold nanolayer on the Ag surface increased the oxidation resistance. These results provide insights regarding the reliability of ACA wire in advanced bonding processes.

Development of explosively bonded TZM wire reinforced Columbian sheet composites

NASA Technical Reports Server (NTRS)

Otto, H. E.; Carpenter, S. H.

1972-01-01

Methods of producing TZM molybdenum wire reinforced C129Y columbium alloy composites by explosive welding were studied. Layers of TZM molybdenum wire were wound on frames with alternate layers of C129Y columbium alloy foil between the wire layers. The frames held both the wire and foils in place for the explosive bonding process. A goal of 33 volume percent molybdenum wire was achieved for some of the composites. Variables included wire diameter, foil thickness, wire separation, standoff distance between foils and types and amounts of explosive. The program was divided into two phases: (1) development of basic welding parameters using 5 x 10-inch composites, and (2) scaleup to 10 x 20-inch composites.

Embedded spacecraft thermal control using ultrasonic consolidation

NASA Astrophysics Data System (ADS)

Clements, Jared W.

Research has been completed in order to rapidly manufacture spacecraft thermal control technologies embedded in spacecraft structural panels using ultrasonic consolidation. This rapid manufacturing process enables custom thermal control designs in the time frame necessary for responsive space. Successfully embedded components include temperature sensors, heaters, wire harnessing, pre-manufactured heat pipes, and custom integral heat pipes. High conductivity inserts and custom integral pulsating heat pipes were unsuccessfully attempted. This research shows the viability of rapid manufacturing of spacecraft structures with embedded thermal control using ultrasonic consolidation.

The acousto-ultrasonic approach

NASA Technical Reports Server (NTRS)

Vary, Alex

1987-01-01

The nature and underlying rationale of the acousto-ultrasonic approach is reviewed, needed advanced signal analysis and evaluation methods suggested, and application potentials discussed. Acousto-ultrasonics is an NDE technique combining aspects of acoustic emission methodology with ultrasonic simulation of stress waves. This approach uses analysis of simulated stress waves for detecting and mapping variations of mechanical properties. Unlike most NDE, acousto-ultrasonics is less concerned with flaw detection than with the assessment of the collective effects of various flaws and material anomalies. Acousto-ultrasonics has been applied chiefly to laminated and filament-wound fiber reinforced composites. It has been used to assess the significant strength and toughness reducing effects that can be wrought by combinations of essentially minor flaws and diffuse flaw populations. Acousto-ultrasonics assesses integrated defect states and the resultant variations in properties such as tensile, shear, and flexural strengths and fracture resistance. Matrix cure state, porosity, fiber orientation, fiber volume fraction, fiber-matrix bonding, and interlaminar bond quality are underlying factors.

Aircraft components structural health monitoring using flexible ultrasonic transducer arrays

NASA Astrophysics Data System (ADS)

Liu, W.-L.; Jen, C.-K.; Kobayashi, M.; Mrad, N.

2011-04-01

A damage detection capability based on a flexible ultrasonic transducer (FUT) array bonded onto a planar and a curved surface is presented. The FUT array was fabricated on a 75 μm titanium substrate using sol-gel spray technique. Room temperature curable adhesive is used as the bonding agent and ultrasonic couplant between the transducer and the test article. The bonding agent was successfully tested for aircraft environmental temperatures between -80 °C and 100 °C. For a planar test article, selected FUT arrays were able to detect fasteners damage within a planar distance of 176 mm, when used in the pulse-echo mode. Such results illustrate the effectiveness of the developed FUT transducer as compared to commercial 10MHz ultrasonic transducer (UT). These FUT arrays were further demonstrated on a curved test article. Pulse-echo measurements confirmed the reflected echoes from the specimen. Such measurement was not possible with commercial UTs due to the curved nature of the test article and its accessibility, thus demonstrating the suitability and superiority of the developed flexible ultrasonic transducer capability.

Effect of ultrasonic agitation on push-out bond strength and adaptation of root-end filling materials

PubMed Central

2018-01-01

Objectives This study evaluated the effect of ultrasonic agitation of mineral trioxide aggregate (MTA), calcium silicate-based cement (CSC), and Sealer 26 (S26) on adaptation at the cement/dentin interface and push-out bond strength. Materials and Methods Sixty maxillary canines were divided into 6 groups (n = 10): MTA, S26, and CSC, with or without ultrasonic activation (US). After obturation, the apical portions of the teeth were sectioned, and retrograde cavities were prepared and filled with cement by hand condensation. In the US groups, the cement was activated for 60 seconds: 30 seconds in the mesio-distal direction and 30 seconds in the buccal-lingual direction, using a mini Irrisonic insert coupled with the ultrasound transducer. After the materials set, 1.5-mm thick sections were obtained from the apexes. The presence of gaps and the bond between cement and dentin were analyzed using low-vacuum scanning electron microscopy. Push-out bond strength was measured using a universal testing machine. Results Ultrasonic agitation increased the interfacial adaptation of the cements. The S26 US group showed a higher adaptation value than MTA (p < 0.05). US improved the push-out bond strength for all the cements (p < 0.05). Conclusions The US of retrograde filling cements enhanced the bond to the dentin wall of the root-end filling materials tested. PMID:29765903

Effect of ultrasonic agitation on push-out bond strength and adaptation of root-end filling materials.

PubMed

Alcalde, Murilo Priori; Vivan, Rodrigo Ricci; Marciano, Marina Angélica; Duque, Jussaro Alves; Fernandes, Samuel Lucas; Rosseto, Mariana Bailo; Duarte, Marco Antonio Hungaro

2018-05-01

This study evaluated the effect of ultrasonic agitation of mineral trioxide aggregate (MTA), calcium silicate-based cement (CSC), and Sealer 26 (S26) on adaptation at the cement/dentin interface and push-out bond strength. Sixty maxillary canines were divided into 6 groups ( n = 10): MTA, S26, and CSC, with or without ultrasonic activation (US). After obturation, the apical portions of the teeth were sectioned, and retrograde cavities were prepared and filled with cement by hand condensation. In the US groups, the cement was activated for 60 seconds: 30 seconds in the mesio-distal direction and 30 seconds in the buccal-lingual direction, using a mini Irrisonic insert coupled with the ultrasound transducer. After the materials set, 1.5-mm thick sections were obtained from the apexes. The presence of gaps and the bond between cement and dentin were analyzed using low-vacuum scanning electron microscopy. Push-out bond strength was measured using a universal testing machine. Ultrasonic agitation increased the interfacial adaptation of the cements. The S26 US group showed a higher adaptation value than MTA ( p < 0.05). US improved the push-out bond strength for all the cements ( p < 0.05). The US of retrograde filling cements enhanced the bond to the dentin wall of the root-end filling materials tested.

Bonding and nondestructive evaluation of graphite/PEEK composite and titanium adherends with thermoplastic adhesives

NASA Technical Reports Server (NTRS)

Hodges, W. T.; Tyeryar, J. R.; Berry, M.

1985-01-01

Bonded single overlap shear specimens were fabricated from Graphite/PEEK (Polyetheretherketone) composite adherends and titanium adherends. Six advanced thermoplastic adhesives were used for the bonding. The specimens were bonded by an electromagnetic induction technique producing high heating rates and high-strength bonds in a few minutes. This contrasts with conventionally heated presses or autoclaves that take hours to process comparable quality bonds. The Graphite/PEEK composites were highly resistant to delamination during the testing. This allowed the specimen to fail exclusively through the bondline, even at very high shear loads. Nondestructive evaluation of bonded specimens was performed ultrasonically by energizing the entire thickness of the material through the bondline and measuring acoustic impedance parameters. Destructive testing confirmed the unique ultrasonic profiles of strong and weak bonds, establishing a standard for predicting relative bond strength in subsequent specimens.

Effect of Pd Surface Roughness on the Bonding Process and High Temperature Reliability of Au Ball Bonds

NASA Astrophysics Data System (ADS)

Huang, Y.; Kim, H. J.; McCracken, M.; Viswanathan, G.; Pon, F.; Mayer, M.; Zhou, Y. N.

2011-06-01

A 0.3- μm-thick electrolytic Pd layer was plated on 1 μm of electroless Ni on 1 mm-thick polished and roughened Cu substrates with roughness values ( R a) of 0.08 μm and 0.5 μm, respectively. The rough substrates were produced with sand-blasting. Au wire bonding on the Ni/Pd surface was optimized, and the electrical reliability was investigated under a high temperature storage test (HTST) during 800 h at 250°C by measuring the ball bond contact resistance, R c. The average value of R c of optimized ball bonds on the rough substrate was 1.96 mΩ which was about 40.0% higher than that on the smooth substrate. The initial bondability increased for the rougher surface, so that only half of the original ultrasonic level was required, but the reliability was not affected by surface roughness. For both substrate types, HTST caused bond healing, reducing the average R c by about 21% and 27%, respectively. Au diffusion into the Pd layer was observed in scanning transmission electron microscopy/ energy dispersive spectroscopy (STEM-EDS) line-scan analysis after HTST. It is considered that diffusion of Au or interdiffusion between Au and Pd can provide chemically strong bonding during HTST. This is supported by the R c decrease measured as the aging time increased. Cu migration was indicated in the STEM-EDS analysis, but its effect on reliability can be ignored. Au and Pd tend to form a complete solid solution at the interface and can provide reliable interconnection for high temperature (250°C) applications.

Improvement of modulation bandwidth in electroabsorption-modulated laser by utilizing the resonance property in bonding wire.

PubMed

Kwon, Oh Kee; Han, Young Tak; Baek, Yong Soon; Chung, Yun C

2012-05-21

We present and demonstrate a simple and cost-effective technique for improving the modulation bandwidth of electroabsorption-modulated laser (EML). This technique utilizes the RF resonance caused by the EML chip (i.e., junction capacitance) and bonding wire (i.e, wire inductance). We analyze the effects of the lengths of the bonding wires on the frequency responses of EML by using an equivalent circuit model. To verify this analysis, we package a lumped EML chip on the sub-mount and measure its frequency responses. The results show that, by using the proposed technique, we can increase the modulation bandwidth of EML from ~16 GHz to ~28 GHz.

Carbon nanotube wires and cables: Near-term applications and future perspectives

NASA Astrophysics Data System (ADS)

Jarosz, Paul; Schauerman, Christopher; Alvarenga, Jack; Moses, Brian; Mastrangelo, Thomas; Raffaelle, Ryne; Ridgley, Richard; Landi, Brian

2011-11-01

Wires and cables are essential to modern society, and opportunities exist to develop new materials with reduced resistance, mass, and/or susceptibility to fatigue. This article describes how carbon nanotubes (CNTs) offer opportunities for integration into wires and cables for both power and data transmission due to their unique physical and electronic properties. Macroscopic CNT wires and ribbons are presently shown as viable replacements for metallic conductors in lab-scale demonstrations of coaxial, USB, and Ethernet cables. In certain applications, such as the outer conductor of a coaxial cable, CNT materials may be positioned to displace metals to achieve substantial benefits (e.g. reduction in cable mass per unit length (mass/length) up to 50% in some cases). Bulk CNT materials possess several unique properties which may offer advantages over metallic conductors, such as flexure tolerance and environmental stability. Specifically, CNT wires were observed to withstand greater than 200,000 bending cycles without increasing resistivity. Additionally, CNT wires exhibit no increase in resistivity after 80 days in a corrosive environment (1 M HCl), and little change in resistivity with temperature (<1% from 170-330 K). This performance is superior to conventional metal wires and truly novel for a wiring material. However, for CNTs to serve as a full replacement for metals, the electrical conductivity of CNT materials must be improved. Recently, the conductivity of a CNT wire prepared through simultaneous densification and doping has exceeded 1.3 × 106 S/m. This level of conductivity brings CNTs closer to copper (5.8 × 107 S/m) and competitive with some metals (e.g. gold) on a mass-normalized basis. Developments in manipulation of CNT materials (e.g. type enrichment, doping, alignment, and densification) have shown progress towards this goal. In parallel with efforts to improve bulk conductivity, integration of CNT materials into cabling architectures will require development in electrical contacting. Several methods for contacting bulk CNT materials to metals are demonstrated, including mechanical crimping and ultrasonic bonding, along with a method for reducing contact resistance by tailoring the CNT-metal interface via electroless plating. Collectively, these results summarize recent progress in CNT wiring technologies and illustrate that nanoscale conductors may become a disruptive technology in cabling designs.

Carbon nanotube wires and cables: near-term applications and future perspectives.

PubMed

Jarosz, Paul; Schauerman, Christopher; Alvarenga, Jack; Moses, Brian; Mastrangelo, Thomas; Raffaelle, Ryne; Ridgley, Richard; Landi, Brian

2011-11-01

Wires and cables are essential to modern society, and opportunities exist to develop new materials with reduced resistance, mass, and/or susceptibility to fatigue. This article describes how carbon nanotubes (CNTs) offer opportunities for integration into wires and cables for both power and data transmission due to their unique physical and electronic properties. Macroscopic CNT wires and ribbons are presently shown as viable replacements for metallic conductors in lab-scale demonstrations of coaxial, USB, and Ethernet cables. In certain applications, such as the outer conductor of a coaxial cable, CNT materials may be positioned to displace metals to achieve substantial benefits (e.g. reduction in cable mass per unit length (mass/length) up to 50% in some cases). Bulk CNT materials possess several unique properties which may offer advantages over metallic conductors, such as flexure tolerance and environmental stability. Specifically, CNT wires were observed to withstand greater than 200,000 bending cycles without increasing resistivity. Additionally, CNT wires exhibit no increase in resistivity after 80 days in a corrosive environment (1 M HCl), and little change in resistivity with temperature (<1% from 170-330 K). This performance is superior to conventional metal wires and truly novel for a wiring material. However, for CNTs to serve as a full replacement for metals, the electrical conductivity of CNT materials must be improved. Recently, the conductivity of a CNT wire prepared through simultaneous densification and doping has exceeded 1.3 × 10(6) S/m. This level of conductivity brings CNTs closer to copper (5.8 × 10(7) S/m) and competitive with some metals (e.g. gold) on a mass-normalized basis. Developments in manipulation of CNT materials (e.g. type enrichment, doping, alignment, and densification) have shown progress towards this goal. In parallel with efforts to improve bulk conductivity, integration of CNT materials into cabling architectures will require development in electrical contacting. Several methods for contacting bulk CNT materials to metals are demonstrated, including mechanical crimping and ultrasonic bonding, along with a method for reducing contact resistance by tailoring the CNT-metal interface via electroless plating. Collectively, these results summarize recent progress in CNT wiring technologies and illustrate that nanoscale conductors may become a disruptive technology in cabling designs.

Feasibility of recanalization of human coronary arteries using high-intensity ultrasound.

PubMed

Ernst, A; Schenk, E A; Woodlock, T J; Alliger, H; Gottlieb, S; Child, S Z; Meltzer, R S

1994-01-15

To investigate the feasibility of ultrasonic recanalization of obstructed human coronary arteries in vitro, high-intensity ultrasound was applied to 16 coronary arteries obtained at autopsy, using a prototype instrument enabling insonification through a catheter tip. It was a 119 cm long, 0.95 mm thick wire in an 8Fr catheter connected to an external ultrasonic transformer and power generator. A 5 MHz phased-array 2-dimensional echocardiography instrument was used to determine minimal luminal diameter and percent diameter narrowing before and after ultrasound application. The ultrasonic energy was delivered at 21.5 kHz and with a 52 +/- 19 micrometer average amplitude of tip displacement. The mean percent luminal diameter narrowing, flow rate and mean pressure gradient before ultrasound exposure were 74 +/- 11%, 97 +/- 61 ml/min, and 92 +/- 18 mm Hg, respectively. After recanalization, the mean percent luminal diameter narrowing decreased to 45 +/- 17% (p < 0.001), the mean flow rate increased to 84 +/- 92 ml/min (p < 0.001), and the mean pressure gradient was reduced to 45 +/- 24 mm Hg (p < 0.001). Of the debris particles, 95% had a diameter < 9 microns (range 5 to 12). Arterial perforation occurred in 5 of 16 arteries (31%) and all 5 occurred due to stiff wire manipulation and without ultrasound application. Mechanical fracture of the wire occurred in 8 cases (50%). No signs of thermal injury were found on histology. Thus, ultrasonic recanalization of human coronary arteries in vitro is feasible. It may reduce obstruction and improve blood flow. Debris sizes are sufficiently small to minimize the hazard of peripheral embolization.

Effect of ultrasonic tip and root-end filling material on bond strength.

PubMed

Vivan, Rodrigo Ricci; Guerreiro-Tanomaru, Juliane Maria; Bernardes, Ricardo Affonso; Reis, José Mauricio Santos Nunes; Hungaro Duarte, Marco Antonio; Tanomaru-Filho, Mário

2016-11-01

The objective of this study was to evaluate the bond strength of three root-end filling materials (MTAA-MTA Angelus, MTAS-experimental MTA Sealer, and ZOE- zinc oxide and eugenol cement) in retrograde preparations performed with different ultrasonic tips (CVD, Trinity, and Satelec). Ninety 2-mm root sections from single-rooted human teeth were used. The retrograde cavities were prepared by using the ultrasonic tips, coupled to a device for position standardization. The specimens were randomly divided into nine groups: CVD MTAA; CVD MTAS; CVD ZOE; Trinity MTAA; Trinity MTAS; Trinity ZOE; Satelec MTAA; Satelec MTAS; Satelec ZOE. Each resin disc/dentin/root-end filling material was placed in the machine to perform the push-out test. The specimens were examined in a stereomicroscope to evaluate the type of failure. Data were submitted to statistical analysis using ANOVA and Tukey tests (α = 0.05). The highest bond strength was observed for the CVD tip irrespective of the material used (P < 0.05). There was no significant difference for the Trinity TU-18 diamond and S12 Satelec tips (P > 0.05). MTAA and MTAS showed highest bond strength. The most common type of failure was adhesion between the filling material and dentin wall, except for ZOE, where mixed failure was predominant. The CVD tip favored higher bond strength of the root-end filling materials. MTA Angelus and experimental MTAS presented bond strength to dentin prepared with ultrasonic tips. Root-end preparation with the CVD tip positively influences the bond strength of root-end filling materials. MTA Angelus and experimental MTAS present bond strength to be used as root-end filling materials.

Comparison of Ultrasound with Tensile Testing of Thermally Damaged Polyimide Insulated Wiring (MIL-W-81381)

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Anastasi, Robert F.

2002-01-01

Ultrasonic measurements were performed on MIL-W-81381/7, /12, and /21 wire, a polyimide (Kapton) insulated wire. The phase velocity for the 20-gauge MIL-W-81381/7 wire had a baseline value of 3023 plus or minus 78 m/s. After exposure to high temperatures, the wire's phase velocity rapidly increased, and reached an asymptotic value of 3598 plus or minus 20 m/s after 100 hours exposure. Similar responses were measured in other gauges. The baseline measurements of Young's moduli resulted in values of 5636 plus or minus 486, 7714 plus or minus 505, and 8767 plus or minus 292 KSI for the 20 ga, 16 ga, and 12 ga. wires respectively.

Silane and Germane Molecular Electronics.

PubMed

Su, Timothy A; Li, Haixing; Klausen, Rebekka S; Kim, Nathaniel T; Neupane, Madhav; Leighton, James L; Steigerwald, Michael L; Venkataraman, Latha; Nuckolls, Colin

2017-04-18

This Account provides an overview of our recent efforts to uncover the fundamental charge transport properties of Si-Si and Ge-Ge single bonds and introduce useful functions into group 14 molecular wires. We utilize the tools of chemical synthesis and a scanning tunneling microscopy-based break-junction technique to study the mechanism of charge transport in these molecular systems. We evaluated the fundamental ability of silicon, germanium, and carbon molecular wires to transport charge by comparing conductances within families of well-defined structures, the members of which differ only in the number of Si (or Ge or C) atoms in the wire. For each family, this procedure yielded a length-dependent conductance decay parameter, β. Comparison of the different β values demonstrates that Si-Si and Ge-Ge σ bonds are more conductive than the analogous C-C σ bonds. These molecular trends mirror what is seen in the bulk. The conductance decay of Si and Ge-based wires is similar in magnitude to those from π-based molecular wires such as paraphenylenes However, the chemistry of the linkers that attach the molecular wires to the electrodes has a large influence on the resulting β value. For example, Si- and Ge-based wires of many different lengths connected with a methyl-thiomethyl linker give β values of 0.36-0.39 Å -1 , whereas Si- and Ge-based wires connected with aryl-thiomethyl groups give drastically different β values for short and long wires. This observation inspired us to study molecular wires that are composed of both π- and σ-orbitals. The sequence and composition of group 14 atoms in the σ chain modulates the electronic coupling between the π end-groups and dictates the molecular conductance. The conductance behavior originates from the coupling between the subunits, which can be understood by considering periodic trends such as bond length, polarizability, and bond polarity. We found that the same periodic trends determine the electric field-induced breakdown properties of individual Si-Si, Ge-Ge, Si-O, Si-C, and C-C bonds. Building from these studies, we have prepared a system that has two different, alternative conductance pathways. In this wire, we can intentionally break a labile, strained silicon-silicon bond and thereby shunt the current through the secondary conduction pathway. This type of in situ bond-rupture provides a new tool to study single molecule reactions that are induced by electric fields. Moreover, these studies provide guidance for designing dielectric materials as well as molecular devices that require stability under high voltage bias. The fundamental studies on the structure/function relationships of the molecular wires have guided the design of new functional systems based on the Si- and Ge-based wires. For example, we exploited the principle of strain-induced Lewis acidity from reaction chemistry to design a single molecule switch that can be controllably switched between two conductive states by varying the distance between the tip and substrate electrodes. We found that the strain intrinsic to the disilaacenaphthene scaffold also creates two state conductance switching. Finally, we demonstrate the first example of a stereoelectronic conductance switch, and we demonstrate that the switching relies crucially on the electronic delocalization in Si-Si and Ge-Ge wire backbones. These studies illustrate the untapped potential in using Si- and Ge-based wires to design and control charge transport at the nanoscale and to allow quantum mechanics to be used as a tool to design ultraminiaturized switches.

Development of Active Catheter,Active Guide Wire and Micro Sensor Systems

PubMed Central

Haga, Y.; Mineta, T.; Totsu, K.; Makishi, W.; Esashi, M.

2001-01-01

Summary Active catheters and active guide wires which move like a snake have been developed for catheter-based minimally invasive diagnosis and therapy. Communication and control IC chips in the active catheter reduce the number of lead wires for control. The active catheter can be not only bent but also torsioned and extended. An ultra minature fiber-optic pressure sensor; a forward-looking ultrasonic probe and a magnetic position and orientation sensor have been developed for catheters and guide wires. These moving mechanisms and several sensors which are fitted near the tip of the catheter and the guide wire will provide detailed information near the tip and enable delicate and effective catheter intervention. PMID:20663389

Bonded ultrasonic transducer and method for making

DOEpatents

Dixon, Raymond D.; Roe, Lawrence H.; Migliori, Albert

1995-01-01

An ultrasonic transducer is formed as a diffusion bonded assembly of piezoelectric crystal, backing material, and, optionally, a ceramic wear surface. The mating surfaces of each component are silver films that are diffusion bonded together under the application of pressure and heat. Each mating surface may also be coated with a reactive metal, such as hafnium, to increase the adhesion of the silver films to the component surfaces. Only thin silver films are deposited, e.g., a thickness of about 0.00635 mm, to form a substantially non-compliant bond between surfaces. The resulting transducer assembly is substantially free of self-resonances over normal operating ranges for taking resonant ultrasound measurements.

Evaluation of mechanical properties in metal wire mesh supported selective catalytic reduction (SCR) catalyst structures

NASA Astrophysics Data System (ADS)

Rajath, S.; Siddaraju, C.; Nandakishora, Y.; Roy, Sukumar

2018-04-01

The objective of this research is to evaluate certain specific mechanical properties of certain stainless steel wire mesh supported Selective catalytic reduction catalysts structures wherein the physical properties of the metal wire mesh and also its surface treatments played vital role thereby influencing the mechanical properties. As the adhesion between the stainless steel wire mesh and the catalyst material determines the bond strength and the erosion resistance of catalyst structures, surface modifications of the metal- wire mesh structure in order to facilitate the interface bonding is therefore very important to realize enhanced level of mechanical properties. One way to enhance such adhesion properties, the stainless steel wire mesh is treated with the various acids, i.e., chromic acid, phosphoric acid including certain mineral acids and combination of all those in various molar ratios that could generate surface active groups on metal surface that promotes good interface structure between the metal- wire mesh and metal oxide-based catalyst material and then the stainless steel wire mesh is dipped in the glass powder slurry containing some amount of organic binder. As a result of which the said catalyst material adheres to the metal-wire mesh surface more effectively that improves the erosion profile of supported catalysts structure including bond strength.

Simulation of transducer-couplant effects on broadband ultrasonic signals

NASA Technical Reports Server (NTRS)

Vary, A.

1980-01-01

The increasing use of broadband, pulse-echo ultrasonics in nondestructive evaluation of flaws and material properties has generated a need for improved understanding of the way signals are modified by coupled and bonded thin-layer interfaces associated with transducers. This understanding is most important when using frequency spectrum analyses for characterizing material properties. In this type of application, signals emanating from material specimens can be strongly influenced by couplant and bond-layers in the acoustic path. Computer synthesized waveforms were used to simulate a range of interface conditions encountered in ultrasonic transducer systems operating in the 20 to 80 MHz regime. The adverse effects of thin-layer multiple reflections associated with various acoustic impedance conditions are demonstrated. The information presented is relevant to ultrasonic transducer design, specimen preparation, and couplant selection.

Physical interpretation and development of ultrasonic nondestructive evaluation techniques applied to the quantitative characterization of textile composite materials

NASA Technical Reports Server (NTRS)

Miller, James G.

1993-01-01

In this Progress Report, we describe our current research activities concerning the development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the characterization of stitched composite materials and bonded aluminum plate specimens. One purpose of this investigation is to identify and characterize specific features of polar backscatter interrogation which enhance the ability of ultrasound to detect flaws in a stitched composite laminate. Another focus is to explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize bonded aluminum lap joints. As an approach to implementing quantitative ultrasonic inspection methods to both of these materials, we focus on the physics that underlies the detection of flaws in such materials.

Finite element bond models for seven-wire prestressing strands in concrete crossties.

DOT National Transportation Integrated Search

2015-03-23

Seven-wire strands are commonly used in pretensioned : concrete ties, but its bonding mechanism with concrete needs : further examination to provide a better understanding of some : concrete tie failure modes. As a key component in the finite : eleme...

Design, fabrication, and testing of an ultrasonic de-icing system for helicopter rotor blades

NASA Astrophysics Data System (ADS)

Palacios, Jose Luis

A low-power, non-thermal ultrasonic de-icing system is introduced as a possible substitute for current electro-thermal systems. The system generates delaminating ultrasonic transverse shear stresses at the interface of accreted ice. A PZT-4 disk driven at 28.5 KHz (radial resonance of the disk) instantaneously de-bonds 2 mm thick freezer ice layers. The ice layers are accreted to a 0.7 mm thick, 30.4 cm x 30.4 cm steel plate at an environment temperature of -20°C. A power input of 50 Watts is applied to the actuator (50 V, 19.6 KV/m), which translates to a de-icing power of 0.07 W/cm2. A finite element model of the actuator bonded to the isotropic plate is used to guide the design of the system, and predicts the transverse shear stresses at the ice interface. Wind tunnel icing tests were conducted to demonstrate the potential use of the proposed system under impact icing conditions. Both glaze ice and rime ice were generated on steel and composite plates by changing the cloud conditions of the wind tunnel. Continuous ultrasonic vibration prevented impact ice formation around the actuator location at an input power not exceeding 0.18 W/cm 2 (1.2 W/in2). As ice thickness reached a critical thickness of approximately 1.2 mm, shedding occurred on those locations where ultrasonic transverse shear stresses exceeded the shear adhesion strength of the ice. Finite element transverse shear stress predictions correlate with observed experimental impact ice de-bonding behavior. To increase the traveling distance of propagating ultrasonic waves, ultrasonic shear horizontal wave modes are studied. Wave modes providing large modal interface transverse shear stress concentration coefficients (ISCC) between the host structure (0.7 mm thick steel plate) and accreted ice (2.5 mm thick ice layer) are identified and investigated for a potential increase in the wave propagation distance. Ultrasonic actuators able to trigger these optimum wave modes are designed and fabricated. Despite exciting wave modes with high ISCC values, instantaneous ice de-bonding is not observed at input powers under 100 Watts. The two triggered ultrasonic wave modes of the structure occur at high excitation frequencies, 202 KHz and 500 KHz respectively. At these frequencies, the ultrasonic actuators do not provide large enough transverse shear stresses to exceed the shear adhesion strength of the ice layer. Neither the actuator exciting the SH1 mode (202 KHz), nor the actuator triggering the SH2 mode (500 KHz) instantaneously de-bonds ice layers with an input power under 100 Watts.

Auto-Gopher: A Wire-Line Rotary-Hammer Ultrasonic Drill

NASA Technical Reports Server (NTRS)

Badescu, Mircea; Sherrit, Stewart; Bao, Xiaogi; Bar-Cohen, Yoseph; Chen, Beck

2011-01-01

Developing technologies that would enable NASA to sample rock, soil, and ice by coring, drilling or abrading at a significant depth is of great importance for a large number of in-situ exploration missions as well as for earth applications. Proven techniques to sample Mars subsurface will be critical for future NASA astrobiology missions that will search for records of past and present life on the planet, as well as, the search for water and other resources. A deep corer, called Auto-Gopher, is currently being developed as a joint effort of the JPL's NDEAA laboratory and Honeybee Robotics Corp. The Auto-Gopher is a wire-line rotary-hammer drill that combines rock breaking by hammering using an ultrasonic actuator and cuttings removal by rotating a fluted bit. The hammering mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) that has been developed as an adaptable tool for many of drilling and coring applications. The USDC uses an intermediate free-flying mass to transform the high frequency vibrations of the horn tip into a sonic hammering of a drill bit. The USDC concept was used in a previous task to develop an Ultrasonic/Sonic Ice Gopher. The lessons learned from testing the ice gopher were implemented into the design of the Auto-Gopher by inducing a rotary motion onto the fluted coring bit. A wire-line version of such a system would allow penetration of significant depth without a large increase in mass. A laboratory version of the corer was developed in the NDEAA lab to determine the design and drive parameters of the integrated system. The design configuration lab version of the design and fabrication and preliminary testing results are presented in this paper

Bonded ultrasonic transducer and method for making

DOEpatents

Dixon, R.D.; Roe, L.H.; Migliori, A.

1995-11-14

An ultrasonic transducer is formed as a diffusion bonded assembly of piezoelectric crystal, backing material, and, optionally, a ceramic wear surface. The mating surfaces of each component are silver films that are diffusion bonded together under the application of pressure and heat. Each mating surface may also be coated with a reactive metal, such as hafnium, to increase the adhesion of the silver films to the component surfaces. Only thin silver films are deposited, e.g., a thickness of about 0.00635 mm, to form a substantially non-compliant bond between surfaces. The resulting transducer assembly is substantially free of self-resonances over normal operating ranges for taking resonant ultrasound measurements. 12 figs.

Processing and Characterization of Liquid-Phase Sintered NiTi Woven Structures

NASA Astrophysics Data System (ADS)

Erdeniz, Dinc; Weidinger, Ryan P.; Sharp, Keith W.; Dunand, David C.

2018-03-01

Porous NiTi is of interest for bone implants because of its unique combination of biocompatibility (encouraging osseointegration), high strength (to prevent fracture), low stiffness (to reduce stress shielding), and shape memory or superelasticity (to deploy an implant). A promising method for creating NiTi structures with regular open channels is via 3D weaving of NiTi wires. This paper presents a processing method to bond woven NiTi wire structures at contact points between wires to achieve structural integrity: (i) a slurry consisting of a blend of NiTi and Nb powders is deposited on the surface of the NiTi wires after the weaving operation; (ii) the powders are melted to create a eutectic liquid phase which collects at contact points; and (iii) the liquid is solidified and binds the NiTi woven structures. The bonded NiTi wire structures exhibited lower transformation temperatures compared to the as-woven NiTi wires because of Nb diffusion into the NiTi wires. A bonded woven sample was deformed in bending and showed near-complete recovery up to 6% strain and recovered nearly half of the deformation up to 19% strain.

Preparation of well-adhered γ-Al 2O 3 washcoat on metallic wire mesh monoliths by electrophoretic deposition

NASA Astrophysics Data System (ADS)

Sun, Hong; Quan, Xie; Chen, Shuo; Zhao, Huimin; Zhao, Yazhi

2007-01-01

Washcoat deposited on metallic wire mesh monoliths was prepared using γ-alumina powders by electrophoretic deposition under a relatively low electric voltage. The microstructure, phase structure and adhesion of washcoat were investigated by SEM, XRD, ultrasonic vibration and thermal shock. The results showed that the loading and adhesion of washcoat were affected obviously by the properties of suspension, such as the zeta potential and the amount of adding binders. A small quantity of aluminum isopropoxide could promote the cohesive affinity of washcoat in thermal shock. The adhesion of washcoat in ultrasonic vibration could be reinforced by increasing calcined temperature and adding a certain aluminum particles. It was also found that the washcoat immersed metal nitrate has excellent vibration-resistant ability.

Bond between smooth prestressing wires and concrete : finite element model and transfer length analysis for pretensioned concrete crossties.

DOT National Transportation Integrated Search

2014-04-03

Pretensioned concrete ties are increasingly employed in railroad high speed : and heavy haul applications. The bond between prestressing wires or strands and : concrete plays an important role in determining the transfer length of pretensioned : conc...

Research of Adhesion Bonds Between Gas-Thermal Coating and Pre-Modified Base

NASA Astrophysics Data System (ADS)

Kovalevskaya, Z.; Zaitsev, K.; Klimenov, V.

2016-08-01

Nature of adhesive bonds between gas-thermal nickel alloy coating and carbon steel base was examined using laser profilometry, optical metallography, transmission and scanning electron microscopy. The steel surface was plastically pre-deformed by an ultrasonic tool. Proved that ultrasound pre-treatment modifies the steel surface. Increase of dislocation density and formation of sub micro-structure are base elements of surface modification. While using high-speed gas-flame, plasma and detonation modes of coatings, surface activation occurs and durable adhesion is formed. Ultrasonic pre-treatment of base material is effective when sprayed particles and base material interact through physical-chemical bond formation. Before applying high-speed gas flame and plasma sprayed coatings, authors recommend ultrasonic pretreatment, which creates periodic wavy topography with a stroke of 250 microns on the steel surface. Before applying detonation sprayed coatings, authors recommend ultrasound pretreatment that create modified surface with a uniform micro-topography.

Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres.

PubMed

Cao, Siyang; Pyatt, Simon; Anthony, Carl J; Kubba, Ammar I; Kubba, Ali E; Olatunbosun, Oluremi

2016-06-21

The safety of the driving experience and manoeuvrability of a vehicle can be improved by detecting the strain in tyres. To measure strain accurately in rubber, the strain sensor needs to be flexible so that it does not deform the medium that it is measuring. In this work, a novel flexible bond wire capacitive strain sensor for measuring the strain in tyres is developed, fabricated and calibrated. An array of 25 micron diameter wire bonds in an approximately 8 mm × 8 mm area is built to create an interdigitated structure, which consists of 50 wire loops resulting in 49 capacitor pairs in parallel. Laser machining was used to pattern copper on a flexible printed circuit board PCB to make the bond pads for the wire attachment. The wire array was finally packaged and embedded in polydimethylsiloxane (PDMS), which acts as the structural material that is strained. The capacitance of the device is in a linear like relationship with respect to the strain, which can measure the strain up to at least ±60,000 micro-strain (±6%) with a resolution of ~132 micro-strain (0.013%). In-tyre testing under static loading has shown the ability of the sensor to measure large tyre strains. The technology used for sensor fabrication lends itself to mass production and so the design is considered to be consistent with low cost commercialisable strain sensing technology.

Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres

PubMed Central

Cao, Siyang; Pyatt, Simon; Anthony, Carl J.; Kubba, Ammar I.; Kubba, Ali E.; Olatunbosun, Oluremi

2016-01-01

The safety of the driving experience and manoeuvrability of a vehicle can be improved by detecting the strain in tyres. To measure strain accurately in rubber, the strain sensor needs to be flexible so that it does not deform the medium that it is measuring. In this work, a novel flexible bond wire capacitive strain sensor for measuring the strain in tyres is developed, fabricated and calibrated. An array of 25 micron diameter wire bonds in an approximately 8 mm × 8 mm area is built to create an interdigitated structure, which consists of 50 wire loops resulting in 49 capacitor pairs in parallel. Laser machining was used to pattern copper on a flexible printed circuit board PCB to make the bond pads for the wire attachment. The wire array was finally packaged and embedded in polydimethylsiloxane (PDMS), which acts as the structural material that is strained. The capacitance of the device is in a linear like relationship with respect to the strain, which can measure the strain up to at least ±60,000 micro-strain (±6%) with a resolution of ~132 micro-strain (0.013%). In-tyre testing under static loading has shown the ability of the sensor to measure large tyre strains. The technology used for sensor fabrication lends itself to mass production and so the design is considered to be consistent with low cost commercialisable strain sensing technology. PMID:27338402

Comparative evaluation of microleakage of lingual retainer wires bonded with three different lingual retainer composites: an in vitro study.

PubMed

Nimbalkar-Patil, Smita; Vaz, Anna; Patil, Pravinkumar G

2014-11-01

To evaluate microleakage when two types of retainer wires were bonded with two light cured and a self cured lingual retainer composites. Total 120 freshly extracted human mandibular incisor teeth were collected and separated into six subgroups of 20 teeth each. Two different wires, a 0.036 inch hard round stainless steel (HRSS) wire sandblasted at the ends and 0.0175 inch multistranded wire bonded onto the lingual surfaces of the incisors with three different types of composite resins of 3M company; Concise Orthodontic (self-cure), Transbond XT (light-cure) and Transbond LR (light-cure). Specimens were further sealed with a nail varnish, stained with 0.5% basic fuchsine for 24 hours, sectioned and examined under a stereomicroscope, and scored for microleakage for the enamel-composite and wire-composite interfaces. Statistical analysis was performed by Kruskal-Wallis and Mann-Whitney U-tests. For HRSS wire, at the enamel-composite interface, the microleakage was least with Transbond LR followed by Concise Orthodontic and greatest for Transbond XT (p<0.05). At the wire composite interface too, the microleakage was in order of Transbond LR

Advanced NDE techniques for quantitative characterization of aircraft

NASA Technical Reports Server (NTRS)

Heyman, Joseph S.; Winfree, William P.

1990-01-01

Recent advances in nondestructive evaluation (NDE) at NASA Langley Research Center and their applications that have resulted in quantitative assessment of material properties based on thermal and ultrasonic measurements are reviewed. Specific applications include ultrasonic determination of bolt tension, ultrasonic and thermal characterization of bonded layered structures, characterization of composite materials, and disbonds in aircraft skins.

In vivo biofilm formation on stainless steel bonded retainers during different oral health-care regimens.

PubMed

Jongsma, Marije A; van der Mei, Henny C; Atema-Smit, Jelly; Busscher, Henk J; Ren, Yijin

2015-03-23

Retention wires permanently bonded to the anterior teeth are used after orthodontic treatment to prevent the teeth from relapsing to pre-treatment positions. A disadvantage of bonded retainers is biofilm accumulation on the wires, which produces a higher incidence of gingival recession, increased pocket depth and bleeding on probing. This study compares in vivo biofilm formation on single-strand and multi-strand retention wires with different oral health-care regimens. Two-centimetre wires were placed in brackets that were bonded to the buccal side of the first molars and second premolars in the upper arches of 22 volunteers. Volunteers used a selected toothpaste with or without the additional use of a mouthrinse containing essential oils. Brushing was performed manually. Regimens were maintained for 1 week, after which the wires were removed and the oral biofilm was collected to quantify the number of organisms and their viability, determine the microbial composition and visualize the bacteria by electron microscopy. A 6-week washout period was employed between regimens. Biofilm formation was reduced on single-strand wires compared with multi-strand wires; bacteria were observed to adhere between the strands. The use of antibacterial toothpastes marginally reduced the amount of biofilm on both wire types, but significantly reduced the viability of the biofilm organisms. Additional use of the mouthrinse did not result in significant changes in biofilm amount or viability. However, major shifts in biofilm composition were induced by combining a stannous fluoride- or triclosan-containing toothpaste with the mouthrinse. These shifts can be tentatively attributed to small changes in bacterial cell surface hydrophobicity after the adsorption of the toothpaste components, which stimulate bacterial adhesion to the hydrophobic oil, as illustrated for a Streptococcus mutans strain.

In vivo biofilm formation on stainless steel bonded retainers during different oral health-care regimens

PubMed Central

Jongsma, Marije A; van der Mei, Henny C; Atema-Smit, Jelly; Busscher, Henk J; Ren, Yijin

2015-01-01

Retention wires permanently bonded to the anterior teeth are used after orthodontic treatment to prevent the teeth from relapsing to pre-treatment positions. A disadvantage of bonded retainers is biofilm accumulation on the wires, which produces a higher incidence of gingival recession, increased pocket depth and bleeding on probing. This study compares in vivo biofilm formation on single-strand and multi-strand retention wires with different oral health-care regimens. Two-centimetre wires were placed in brackets that were bonded to the buccal side of the first molars and second premolars in the upper arches of 22 volunteers. Volunteers used a selected toothpaste with or without the additional use of a mouthrinse containing essential oils. Brushing was performed manually. Regimens were maintained for 1 week, after which the wires were removed and the oral biofilm was collected to quantify the number of organisms and their viability, determine the microbial composition and visualize the bacteria by electron microscopy. A 6-week washout period was employed between regimens. Biofilm formation was reduced on single-strand wires compared with multi-strand wires; bacteria were observed to adhere between the strands. The use of antibacterial toothpastes marginally reduced the amount of biofilm on both wire types, but significantly reduced the viability of the biofilm organisms. Additional use of the mouthrinse did not result in significant changes in biofilm amount or viability. However, major shifts in biofilm composition were induced by combining a stannous fluoride- or triclosan-containing toothpaste with the mouthrinse. These shifts can be tentatively attributed to small changes in bacterial cell surface hydrophobicity after the adsorption of the toothpaste components, which stimulate bacterial adhesion to the hydrophobic oil, as illustrated for a Streptococcus mutans strain. PMID:25572920

Experimental Investigation of the Acoustic Nonlinear Behavior in Granular Polymer Bonded Explosives with Progressive Fatigue Damage

PubMed Central

Yang, Zhanfeng; Tian, Yong; Li, Weibin; Zhou, Haiqiang; Zhang, Weibin; Li, Jingming

2017-01-01

The measurement of acoustic nonlinear response is known as a promising technique to characterize material micro-damages. In this paper, nonlinear ultrasonic approach is used to characterize the evolution of fatigue induced micro-cracks in polymer bonded explosives. The variations of acoustic nonlinearity with respect to fatigue cycles in the specimens are obtained in this investigation. The present results show a significant increase of acoustic nonlinearity with respect to fatigue cycles. The experimental observation of the correlation between the acoustic nonlinearity and fatigue cycles in carbon/epoxy laminates, verifies that an acoustic nonlinear response can be used to evaluate the progressive fatigue damage in the granular polymer bonded explosives. The sensitivity comparison of nonlinear and linear parameters of ultrasonic waves in the specimens shows that nonlinear acoustic parameters are more promising indicators to fatigue induced micro-damage than linear ones. The feasibility study of the micro-damage assessment of polymer bonded explosives by nonlinear ultrasonic technique in this work can be applied to damage identification, material degradation monitoring, and lifetime prediction of the explosive parts. PMID:28773017

Experimental Investigation of the Acoustic Nonlinear Behavior in Granular Polymer Bonded Explosives with Progressive Fatigue Damage.

PubMed

Yang, Zhanfeng; Tian, Yong; Li, Weibin; Zhou, Haiqiang; Zhang, Weibin; Li, Jingming

2017-06-16

The measurement of acoustic nonlinear response is known as a promising technique to characterize material micro-damages. In this paper, nonlinear ultrasonic approach is used to characterize the evolution of fatigue induced micro-cracks in polymer bonded explosives. The variations of acoustic nonlinearity with respect to fatigue cycles in the specimens are obtained in this investigation. The present results show a significant increase of acoustic nonlinearity with respect to fatigue cycles. The experimental observation of the correlation between the acoustic nonlinearity and fatigue cycles in carbon/epoxy laminates, verifies that an acoustic nonlinear response can be used to evaluate the progressive fatigue damage in the granular polymer bonded explosives. The sensitivity comparison of nonlinear and linear parameters of ultrasonic waves in the specimens shows that nonlinear acoustic parameters are more promising indicators to fatigue induced micro-damage than linear ones. The feasibility study of the micro-damage assessment of polymer bonded explosives by nonlinear ultrasonic technique in this work can be applied to damage identification, material degradation monitoring, and lifetime prediction of the explosive parts.

Adaptive Process Controls and Ultrasonics for High Temperature PEM MEA Manufacture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walczyk, Daniel F.

2015-08-26

The purpose of this 5-year DOE-sponsored project was to address major process bottlenecks associated with fuel cell manufacturing. New technologies were developed to significantly reduce pressing cycle time for high temperature PEM membrane electrode assembly (MEA) through the use of novel, robust ultrasonic (U/S) bonding processes along with low temperature (<100°C) PEM MEAs. In addition, greater manufacturing uniformity and performance was achieved through (a) an investigation into the causes of excessive variation in ultrasonically and thermally bonded MEAs using more diagnostics applied during the entire fabrication and cell build process, and (b) development of rapid, yet simple quality control measurementmore » techniques for use by industry.« less

Decrease of contact resistance at the interface of carbon nanotube/electrode by nanowelding

NASA Astrophysics Data System (ADS)

Zhao, Bo; Wang, Yanfang; Zhang, Yafei

2017-03-01

Reliable interconnection between carbon nanotubes (CNTs) and external circuit is one of the prerequisite in CNT electronics. In this work, ultrasonic nanowelding was used to bond CNTs with metal electrodes. By exerting ultrasonic energy at the interface of CNT/electrode, a reliable joint with negligible contact resistance was obtained between CNTs and electrodes. The performance of welding is susceptible to the ultrasonic parameters such as ultrasonic power and clamping force, as well as the metal type. It is found that the metals with good ductility or low melting point are easier to achieve effective joints. Moreover, interfacial compounds are formed at the welded surface of metal Al and Fe, which is resulted from the interacting and chemical bonding of carbon and metal atoms. After nanowelding, the contact resistance between CNTs and electrode is decreased dramatically, and the two-terminal resistance of the sample approximates to the intrinsic resistance of the CNT itself.

Ultrasonic and micromechanical study of damage and elastic properties of SiC/RBSN ceramic composites. [Reaction Bonded Silicon Nitride

NASA Technical Reports Server (NTRS)

Chu, Y. C.; Hefetz, M.; Rokhlin, S. I.; Baaklini, G. Y.

1992-01-01

Ultrasonic techniques are employed to develop methods for nondestructive evaluation of elastic properties and damage in SiC/RBSN composites. To incorporate imperfect boundary conditions between fibers and matrix into a micromechanical model, a model of fibers having effective anisotropic properties is introduced. By inverting Hashin's (1979) microstructural model for a composite material with microscopic constituents the effective fiber properties were found from ultrasonic measurements. Ultrasonic measurements indicate that damage due to thermal shock is located near the surface, so the surface wave is most appropriate for estimation of the ultimate strength reduction and critical temperature of thermal shock. It is concluded that bonding between laminates of SiC/RBSN composites is severely weakened by thermal oxidation. Generally, nondestructive evaluation of thermal oxidation effects and thermal shock shows good correlation with measurements previously performed by destructive methods.

Ultrasonic Fingerprint Sensor With Transmit Beamforming Based on a PMUT Array Bonded to CMOS Circuitry.

PubMed

Jiang, Xiaoyue; Tang, Hao-Yen; Lu, Yipeng; Ng, Eldwin J; Tsai, Julius M; Boser, Bernhard E; Horsley, David A

2017-09-01

In this paper, we present a single-chip 65 ×42 element ultrasonic pulse-echo fingerprint sensor with transmit (TX) beamforming based on piezoelectric micromachined ultrasonic transducers directly bonded to a CMOS readout application-specific integrated circuit (ASIC). The readout ASIC was realized in a standard 180-nm CMOS process with a 24-V high-voltage transistor option. Pulse-echo measurements are performed column-by-column in sequence using either one column or five columns to TX the ultrasonic pulse at 20 MHz. TX beamforming is used to focus the ultrasonic beam at the imaging plane where the finger is located, increasing the ultrasonic pressure and narrowing the 3-dB beamwidth to [Formula: see text], a factor of 6.4 narrower than nonbeamformed measurements. The surface of the sensor is coated with a poly-dimethylsiloxane (PDMS) layer to provide good acoustic impedance matching to skin. Scanning laser Doppler vibrometry of the PDMS surface was used to map the ultrasonic pressure field at the imaging surface, demonstrating the expected increase in pressure, and reduction in beamwidth. Imaging experiments were conducted using both PDMS phantoms and real fingerprints. The average image contrast is increased by a factor of 1.5 when beamforming is used.

Welding Wires To Thin Thermocouple Films

NASA Technical Reports Server (NTRS)

Holanda, Raymond; Kim, Walter S.; Danzey, Gerald A.; Pencil, Eric; Wadel, Mary

1993-01-01

Parallel-gap resistance welding yields joints surviving temperatures of about 1,000 degrees C. Much faster than thermocompression bonding. Also exceeds conductive-paste bonding and sputtering thin films through porous flame-sprayed insulation on prewelded lead wires. Introduces no foreign material into thermocouple circuit and does not require careful control of thickness of flame-sprayed material.

49 CFR 177.837 - Class 3 materials.

Code of Federal Regulations, 2014 CFR

2014-10-01

... through an open filling hole, one end of a bond wire shall be connected to the stationary system piping or... interconnected.) This connection must be made before any filling hole is opened, and must remain in place until after the last filling hole has been closed. Additional bond wires are not needed around All-Metal...

49 CFR 177.837 - Class 3 materials.

Code of Federal Regulations, 2012 CFR

2012-10-01

... through an open filling hole, one end of a bond wire shall be connected to the stationary system piping or... interconnected.) This connection must be made before any filling hole is opened, and must remain in place until after the last filling hole has been closed. Additional bond wires are not needed around All-Metal...

49 CFR 177.837 - Class 3 materials.

Code of Federal Regulations, 2013 CFR

2013-10-01

... through an open filling hole, one end of a bond wire shall be connected to the stationary system piping or... interconnected.) This connection must be made before any filling hole is opened, and must remain in place until after the last filling hole has been closed. Additional bond wires are not needed around All-Metal...

49 CFR 177.837 - Class 3 materials.

Code of Federal Regulations, 2011 CFR

2011-10-01

... through an open filling hole, one end of a bond wire shall be connected to the stationary system piping or integrally connected steel framing, and the other end to the shell of the cargo tank to provide a continuous... after the last filling hole has been closed. Additional bond wires are not needed around All-Metal...

49 CFR 177.837 - Class 3 materials.

Code of Federal Regulations, 2010 CFR

2010-10-01

... through an open filling hole, one end of a bond wire shall be connected to the stationary system piping or integrally connected steel framing, and the other end to the shell of the cargo tank to provide a continuous... after the last filling hole has been closed. Additional bond wires are not needed around All-Metal...

Splicing Wires Permanently With Explosives

NASA Technical Reports Server (NTRS)

Bement, Laurence J.; Kushnick, Anne C.

1990-01-01

Explosive joining process developed to splice wires by enclosing and metallurgically bonding wires within copper sheets. Joints exhibit many desirable characteristics, 100-percent conductivity and strength, no heat-induced annealing, no susceptibility to corrosion in contacts between dissimilar metals, and stability at high temperature. Used to join wires to terminals, as well as to splice wires. Applicable to telecommunications industry, in which millions of small wires spliced annually.

Direct mapping of electrical noise sources in molecular wire-based devices

PubMed Central

Cho, Duckhyung; Lee, Hyungwoo; Shekhar, Shashank; Yang, Myungjae; Park, Jae Yeol; Hong, Seunghun

2017-01-01

We report a noise mapping strategy for the reliable identification and analysis of noise sources in molecular wire junctions. Here, different molecular wires were patterned on a gold substrate, and the current-noise map on the pattern was measured and analyzed, enabling the quantitative study of noise sources in the patterned molecular wires. The frequency spectra of the noise from the molecular wire junctions exhibited characteristic 1/f2 behavior, which was used to identify the electrical signals from molecular wires. This method was applied to analyze the molecular junctions comprising various thiol molecules on a gold substrate, revealing that the noise in the junctions mainly came from the fluctuation of the thiol bonds. Furthermore, we quantitatively compared the frequencies of such bond fluctuations in different molecular wire junctions and identified molecular wires with lower electrical noise, which can provide critical information for designing low-noise molecular electronic devices. Our method provides valuable insights regarding noise phenomena in molecular wires and can be a powerful tool for the development of molecular electronic devices. PMID:28233821

Direct mapping of electrical noise sources in molecular wire-based devices

NASA Astrophysics Data System (ADS)

Cho, Duckhyung; Lee, Hyungwoo; Shekhar, Shashank; Yang, Myungjae; Park, Jae Yeol; Hong, Seunghun

2017-02-01

We report a noise mapping strategy for the reliable identification and analysis of noise sources in molecular wire junctions. Here, different molecular wires were patterned on a gold substrate, and the current-noise map on the pattern was measured and analyzed, enabling the quantitative study of noise sources in the patterned molecular wires. The frequency spectra of the noise from the molecular wire junctions exhibited characteristic 1/f2 behavior, which was used to identify the electrical signals from molecular wires. This method was applied to analyze the molecular junctions comprising various thiol molecules on a gold substrate, revealing that the noise in the junctions mainly came from the fluctuation of the thiol bonds. Furthermore, we quantitatively compared the frequencies of such bond fluctuations in different molecular wire junctions and identified molecular wires with lower electrical noise, which can provide critical information for designing low-noise molecular electronic devices. Our method provides valuable insights regarding noise phenomena in molecular wires and can be a powerful tool for the development of molecular electronic devices.

Designing an in-situ ultrasonic nondestructive evaluation system for ultrasonic additive manufacturing

NASA Astrophysics Data System (ADS)

Nadimpalli, Venkata K.; Nagy, Peter B.

2018-04-01

Ultrasonic Additive Manufacturing (UAM) is a solid-state layer by layer manufacturing process that utilizes vibration induced plastic deformation to form a metallurgical bond between a thin layer and an existing base structure. Due to the vibration based bonding mechanism, the quality of components at each layer depends on the geometry of the structure. In-situ monitoring during and between UAM manufacturing steps offers the potential for closed-loop control to optimize process parameters and to repair existing defects. One interface that is most prone to delamination is the base/build interface and often UAM component height and quality are limited by failure at the base/build interface. Low manufacturing temperatures and favorable orientation of typical interface defects in UAM make ultrasonic NDE an attractive candidate for online monitoring. Two approaches for in-situ NDE are discussed and the design of the monitoring system optimized so that the quality of UAM components is not affected by the addition of the NDE setup. Preliminary results from in-situ ultrasonic NDE indicate the potential to be utilized for online qualification, closed-loop control and offline certification of UAM components.

Inorganic spark chamber frame and method of making the same

NASA Technical Reports Server (NTRS)

Heslin, T. M. (Inventor)

1982-01-01

A spark chamber frame, manufactured using only inorganic materials is described. The spark chamber frame includes a plurality of beams formed from inorganic material, such as ceramic or glass, and are connected together at ends with inorganic bonding material having substantially the same thermal expansion as the beam material. A plurality of wires formed from an inorganic composition are positioned between opposed beams so that the wires are uniformly spaced and form a grid. A plurality of hold down straps are formed of inorganic material such as ceramic or glass having substantially the same chemical and thermal properties as the beam material. Hold down straps overlie wires extending over the beams and are bonded thereto with inorganic bonding material.

Wiring design for the control of electromagnetic interference (EMI)

NASA Technical Reports Server (NTRS)

Kopasakis, George

1995-01-01

Wiring design is only one important aspect of EMI control. Other important areas for EMI are: circuit design, filtering, grounding, bonding, shielding, lighting, electrostatic discharge (ESD), transient suppression, and electromagnetic pulse (EMP). Topics covered include: wire magnetic field emissions at low frequencies; wire radiated magnetic field emissions at frequencies; wire design guidelines for EMI control; wire design guidelines for EMI control; high frequency emissions from cables; and pulse frequency spectra.

Ultrasonic thermometry using pulse techniques.

NASA Technical Reports Server (NTRS)

Lynnworth, L. C.; Carnevale, E. H.

1972-01-01

Ultrasonic pulse techniques have been developed which, when applied to inert gases, provide temperature measurements up to 8000 K. The response time can be less than 1 msec. This is a significant feature in studying shock-heated or combusting gases. Using a momentary contact coupling technique, temperature has been measured inside steel from 300 to 1500 K. Thin-wire sensors have been used above 2000 K in nuclear and industrial applications where conditions preclude the use of thermocouples, resistance devices, or optical pyrometers. At 2500 K, temperature sensitivity of 0.1% is obtained in Re wire sensors 5 cm long by timing five round trips with an electronic instrument that resolves the time interval between selected echoes to 0.1 microsec. Sensors have been operated at rotational speeds over 2000 rpm and in noisy environments. Temperature profiling of up to ten regions using only a single guided path or beam has also been accomplished.

Explosive bonding of metal-matrix composites

NASA Technical Reports Server (NTRS)

Reece, O. Y.

1969-01-01

Explosive bonding process produces sheet composites of aluminum alloy reinforced by high-strength stainless steel wires. The bonds are excellent metallurgically, no external heat is required, various metals can be bonded, and the process is inexpensive.

Ultrasonic Determination of Combinations of Third-Order Elastic Constants of Small Cubic Single Crystals

DTIC Science & Technology

1981-05-01

crystals Cesium cadmium fluoride Ultrasonic wave propagation Potassium zinc fluoride Nonlinear acoustics 20. A’?S1 RACT (Continue on reverse side If...is the stray capacitance of the detector, L is the inductance of the wire leading from the banana jack to the BNC connector (shown in Figure 111-2). Z...The samples on which measurements were made included [lO0] and [1111 copper samples, a sample of potassium zinc fluoride (KZnF 3 ) and a sample of

Ultrasonic-assisted soldering of fine-grained 7034 aluminum alloy using Sn-Zn solders below 300°C.

PubMed

Guo, Weibing; Luan, Tianmin; He, Jingshan; Yan, Jiuchun

2018-01-01

The fine-grained Al alloys prefer to be soldered at as low as temperature to keep their mechanical properties. Solders of Sn-4Zn, Sn-9Zn, and Sn-20Zn alloys were used to solder fine-grained 7034 Al alloy pieces by ultrasonic-assisted soldering below 300°C in air. The joint using Sn-4Zn solder had the highest tensile strength of 201MPa and the fractures occurred in both β-Sn and Sn-Zn eutectic phases. Such joint was much stronger than the 1060 Al joint using Sn-4Zn solder, and its strength had approached the strength of 7034 Al joint using Zn-5Al solder. The strength of the joints using Sn-9Zn and Sn-20Zn solders dropped to∼160MPa due to the appearance of weak interfaces between η-Zn and eutectic phases in the bond layers. All the joints using Sn-Zn solders had very strong interfacial bonding, and alumina interlayers were identified at all the interfaces. Al dissolved in the bond layer reacted with the O rapidly to form alumina interlayers at the interfaces under the ultrasonic action. Zn segregated at the interface and formed strong bonds with both the Al terminated surface of alumina and the bond layer, resulting in strong interfacial bonding between Sn-Zn solders and Al alloys. Copyright © 2017 Elsevier B.V. All rights reserved.

Cyclic and low temperature effects on microcircuits

NASA Technical Reports Server (NTRS)

Weissflug, V. A.; Sisul, E. V.

1977-01-01

Cyclic temperature and low temperature operating life tests, and pre-/post-life device evaluations were used to determine the degrading effects of thermal environments on microcircuit reliability. Low power transistor-transistor-logic gates and linear devices were included in each test group. Device metallization systems included aluminum metallization/aluminum wire, aluminum metallization/gold wire, and gold metallization/gold wire. Fewer than 2% electrical failures were observed during the cyclic and low temperature life tests and the post-life evaluations revealed approximately 2% bond pull failures. Reconstruction of aluminum die metallization was observed in all devices and the severity of the reconstruction appeared to be directly related to the magnitude of the temperature excursion. All types of bonds except the gold/gold bonds were weakened by exposure to repeated cyclic temperature stress.

Applying a nonlinear, pitch-catch, ultrasonic technique for the detection of kissing bonds in friction stir welds.

PubMed

Delrue, Steven; Tabatabaeipour, Morteza; Hettler, Jan; Van Den Abeele, Koen

2016-05-01

Friction stir welding (FSW) is a promising technology for the joining of aluminum alloys and other metallic admixtures that are hard to weld by conventional fusion welding. Although FSW generally provides better fatigue properties than traditional fusion welding methods, fatigue properties are still significantly lower than for the base material. Apart from voids, kissing bonds for instance, in the form of closed cracks propagating along the interface of the stirred and heat affected zone, are inherent features of the weld and can be considered as one of the main causes of a reduced fatigue life of FSW in comparison to the base material. The main problem with kissing bond defects in FSW, is that they currently are very difficult to detect using existing NDT methods. Besides, in most cases, the defects are not directly accessible from the exposed surface. Therefore, new techniques capable of detecting small kissing bond flaws need to be introduced. In the present paper, a novel and practical approach is introduced based on a nonlinear, single-sided, ultrasonic technique. The proposed inspection technique uses two single element transducers, with the first transducer transmitting an ultrasonic signal that focuses the ultrasonic waves at the bottom side of the sample where cracks are most likely to occur. The large amount of energy at the focus activates the kissing bond, resulting in the generation of nonlinear features in the wave propagation. These nonlinear features are then captured by the second transducer operating in pitch-catch mode, and are analyzed, using pulse inversion, to reveal the presence of a defect. The performance of the proposed nonlinear, pitch-catch technique, is first illustrated using a numerical study of an aluminum sample containing simple, vertically oriented, incipient cracks. Later, the proposed technique is also applied experimentally on a real-life friction stir welded butt joint containing a kissing bond flaw. Copyright © 2016 Elsevier B.V. All rights reserved.

En-masse retraction with a preformed nickel-titanium and stainless steel archwire assembly and temporary skeletal anchorage devices without posterior bonding

PubMed Central

Jee, Jeong-Hyun; Ahn, Hyo-Won; Seo, Kyung-Won; Kook, Yoon-Ah; Chung, Kyu-Rhim; Nelson, Gerald

2014-01-01

Objective To evaluate the therapeutic effects of a preformed assembly of nickel-titanium (NiTi) and stainless steel (SS) archwires (preformed C-wire) combined with temporary skeletal anchorage devices (TSADs) as the sole source of anchorage and to compare these effects with those of a SS version of C-wire (conventional C-wire) for en-masse retraction. Methods Thirty-one adult female patients with skeletal Class I or II dentoalveolar protrusion, mild-to-moderate anterior crowding (3.0-6.0 mm), and stable Class I posterior occlusion were divided into conventional (n = 15) and preformed (n = 16) C-wire groups. All subjects underwent first premolar extractions and en-masse retraction with pre-adjusted edgewise anterior brackets, the assigned C-wire, and maxillary C-tubes or C-implants; bonded mesh-tube appliances were used in the mandibular dentition. Differences in pretreatment and post-retraction measurements of skeletal, dental, and soft-tissue cephalometric variables were statistically analyzed. Results Both groups showed full retraction of the maxillary anterior teeth by controlled tipping and space closure without altered posterior occlusion. However, the preformed C-wire group had a shorter retraction period (by 3.2 months). Furthermore, the maxillary molars in this group showed no significant mesialization, mesial tipping, or extrusion; some mesialization and mesial tipping occurred in the conventional C-wire group. Conclusions Preformed C-wires combined with maxillary TSADs enable simultaneous leveling and space closure from the beginning of the treatment without maxillary posterior bonding. This allows for faster treatment of dentoalveolar protrusion without unwanted side effects, when compared with conventional C-wire, evidencing its clinical expediency. PMID:25309863

Cutting Head for Ultrasonic Lithotripsy

NASA Technical Reports Server (NTRS)

Angulo, E. D.; Goodfriend, R.

1987-01-01

Kidney stones lodged in urinary tract disintegrated with increased safety and efficiency by cutting head attached to end of vibrated wire probe. Aligns probe with stone and enables probe to vibrate long enough to disintegrate stone. Design of cutting head reduces risk of metal-fatigue-induced breakage of probe tip leaving metal fragments in urinary tract. Teeth of cutting head both seat and fragment kidney stone, while extension of collar into catheter lessens mechanical strain in probe wire, increasing probe life and lessening danger of in situ probe breakage.

Sub-Kelvin resistance thermometer

NASA Technical Reports Server (NTRS)

Castles, Stephen H. (Inventor)

1992-01-01

A device capable of accurate temperature measurement down to 0.01 K of a particular object is discussed. The device is comprised of the following: a heat sink wafer; a first conducting pad bonded near one end of the heat sink wafer; a second conducting pad bonded near the other end of the heat sink wafer; and an oblong doped semiconductor crystal such as germanium. The oblong doped semiconductor crystal has a third conducting pad bonded on its bottom surface with the oblong doped semiconductor crystal bonded to the heat sink wafer by having the fourth conducting pad bonded to the first conducting pad. A wire is bonded between the second and third conducting pads. Current and voltage wires bonded to the first and second conducting pads measure the change in resistance of the oblong doped semiconductor crystal; this indicates the temperature of the object whose temperature is to be measured.

Joining of polypropylene/polypropylene and glass fiber reinforced polypropylene composites

NASA Astrophysics Data System (ADS)

Zhang, Jianguang

Joining behavior of polypropylene (PP) to PP and long glass fiber reinforced polypropylene (LFT) to LFT were investigated. Adhesive bonding was used to join PP/PP. Both adhesive bonding and ultrasonic welding were used to join LFT/LFT. Single-lap shear testing and low velocity impact (LVI) testing were used to evaluate the performance of bonded structures. The two-part acrylic adhesive DP8005 was determined to be the best among the three adhesive candidates, which was attributed to its low surface energy. The impact resistance of LFT/LFT joints, normalized with respect to thickness, was higher than that of PP/PP joints because of higher stiffness of LFT/LFT joints. The stress states in the adhesive layer of adhesively bonded structures were analyzed using ANSYS and LS-DYNA to simulate the single-lap shear testing and LVI testing, respectively. The shear and peel stresses peaked at the edges of the adhesive layer. Compared to LFT/LFT joints, higher peel stress occurred in the adhesive layer in the PP/PP joints in tension. Impact response of adhesively bonded structures as evaluated by LS-DYNA showed good agreement with the experimental results. The effect of weld time and weld pressure on the shear strength of ultrasonically welded LFT/LFT was evaluated. With higher weld pressure, less time was required to obtain a complete weld. At longer weld times, lower weld pressure was required. From the 15 weld conditions studied, a weld map was obtained that provides conditions to achieve a complete weld. Nanoindentation was used to evaluate the effect of ultrasonic weld on the modulus and hardness of the PP matrix. Modulus and hardness of the PP matrix were slightly decreased by ultrasonic welding possibly due to the decrease in the molecular weight. The temperature profile in LFT/LFT in the transverse direction during ultrasonic welding was analyzed by two ANSYS-based thermal models: (a) one in which heat generated by interfacial friction was treated as a heat flux and (b) one in which heat was generated in a thin slab at the interface. The weld map obtained from the thin slab model was closer to the one obtained experimentally.

A High-Frequency Linear Ultrasonic Array Utilizing an Interdigitally Bonded 2-2 Piezo-Composite

PubMed Central

Cannata, Jonathan M.; Williams, Jay A.; Zhang, Lequan; Hu, Chang-Hong; Shung, K. Kirk

2011-01-01

This paper describes the development of a high-frequency 256-element linear ultrasonic array utilizing an interdigitally bonded (IB) piezo-composite. Several IB composites were fabricated with different commercial and experimental piezoelectric ceramics and evaluated to determine a suitable formulation for use in high-frequency linear arrays. It was found that the fabricated fine-scale 2–2 IB composites outperformed 1–3 IB composites with identical pillar- and kerf-widths. This result was not expected and lead to the conclusion that dicing damage was likely the cause of the discrepancy. Ultimately, a 2–2 composite fabricated using a fine-grain piezoelectric ceramic was chosen for the array. The composite was manufactured using one IB operation in the azimuth direction to produce approximately 19-μm-wide pillars separated by 6-μm-wide kerfs. The array had a 50 μm (one wavelength in water) azimuth pitch, two matching layers, and 2 mm elevation length focused to 7.3 mm using a polymethylpentene (TPX) lens. The measured pulse-echo center frequency for a representative array element was 28 MHz and −6-dB band-width was 61%. The measured single-element transmit −6-dB directivity was estimated to be 50°. The measured insertion loss was 19 dB after compensating for the effects of attenuation and diffraction in the water bath. A fine-wire phantom was used to assess the lateral and axial resolution of the array when paired with a prototype system utilizing a 64-channel analog beamformer. The −6-dB lateral and axial resolutions were estimated to be 125 and 68 μm, respectively. An anechoic cyst phantom was also imaged to determine the minimum detectable spherical inclusion, and thus the 3-D resolution of the array and beamformer. The minimum anechoic cyst detected was approximately 300 μm in diameter. PMID:21989884

Effect of cleaning methods after reduced-pressure air abrasion on bonding to zirconia ceramic.

PubMed

Attia, Ahmed; Kern, Matthias

2011-12-01

To evaluate in vitro the influence of different cleaning methods after low-pressure air abrasion on the bond strength of a phosphate monomer-containing luting resin to zirconia ceramic. A total of 112 zirconia ceramic disks were divided into 7 groups (n = 16). In the test groups, disks were air abraded at low pressure (L) 0.05 MPa using 50-μm alumina particles. Prior to bonding, the disks were ultrasonically (U) cleaned either in isopropanol alcohol (AC), hydrofluoric acid (HF), demineralized water (DW), or tap water (TW), or they were used without ultrasonic cleaning. Disks air abraded at a high (H) pressure of 0.25 MPa and cleaned ultrasonically in isopropanol served as positive control; original (O) milled disks used without air abrasion served as the negative control group. Plexiglas tubes filled with composite resin were bonded with the adhesive luting resin Panavia 21 to the ceramic disks. Prior to testing tensile bond strength (TBS), each main group was further subdivided into 2 subgroups (n=8) which were stored in distilled water either at 37°C for 3 days or for 30 days with 7500 thermal cycles. Statistical analyses were conducted with two- and one-way analyses of variance (ANOVA) and Tukey's HSD test. Initial tensile bond strength (TBS) ranged from 32.6 to 42.8 MPa. After 30 days storage in water with thermocycling, TBS ranged from 21.9 to 36.3 MPa. Storage in water and thermocycling significantly decreased the TBS of test groups which were not air abraded (p = 0.05) or which were air abraded but cleaned in tap water (p = 0.002), but not the TBS of the other groups (p > 0.05). Also, the TBS of air-abraded groups were significantly higher than the TBS of the original milled (p < 0.01). Cleaning procedures did not significantly affect TBS either after 3 days or 30 days storage in water and thermocycling (p > 0.05). Air abrasion at 0.05 MPa and ultrasonic cleaning are important factors for improving bonding to zirconia ceramic.

Assessment of damage in ceramics and ceramic matrix composites using ultrasonic techniques

NASA Technical Reports Server (NTRS)

Chu, Y. C.; Baaklini, G. Y.; Rokhlin, S.I.

1993-01-01

This paper addresses the application of ultrasonic sensing to damage assessment in ceramics and ceramic matrix composites. It focuses on damage caused by thermal shock or oxidation at elevated temperatures, which often results in elastic anisotropy. This damaged-induced anisotropy is determined by measuring the velocities of ultrasonic waves in different propagation directions. Thermal shock damage is assessed in ceramic samples of reaction bonded silicon nitride (RBSN). Thermal shock treatment from different temperatures up to 1000 C is applied to produce the microcracks. Results indicate that most microcracks produced by thermal shock are located near sample surfaces. Ultrasonic measurements using the surface wave method are found to correlate well with measurements of degradation of mechanical properties obtained independently by other authors using destructive methods. Oxidation damage is assessed in silicon carbide fiber/reaction bonded silicon nitride matrix (SCS-6/RBSN) composites. The oxidation is done by exposing the samples in a flowing oxygen environment at elevated temperatures, up to 1400 C, for 100 hr. The Youngs' modulus in the fiber direction as obtained from ultrasonic measurements decreases significantly at 600 C but retains its original value at temperatures above 1200 C. This agrees well with the results of destructive tests by other authors. On the other hand, the transverse moduli obtained from ultrasonic measurements decrease continually until 1200 C. Measurements on the shear stiffnesses show behavior similar to the transverse moduli. The results of this work show that the damage-induced anisotropy in both ceramics and ceramic matrix composites can be determined successfully by ultrasonic methods. This suggests the possibility of assessing damage severity using ultrasonic techniques.

Tapered capillary optics

DOEpatents

Hirsch, Gregory

1998-01-01

A metal or glass wire is etched with great precision into a very narrowly tapering cone which has the shape of the desired final capillary-optics bore. By controlling the rate of removal of the wire from an etchant bath, a carefully controlled taper is produced. A sensor measures the diameter of the wire as it leaves the surface of the etchant. This signal is used for feedback control of the withdrawal speed. The etched wire undergoes a treatment to produce an extremely low surface-roughness. The etched and smoothed wire is coated with the material of choice for optimizing the reflectivity of the radiation being focused. This could be a vacuum evaporation, sputtering, CVD or aqueous chemical process. The coated wire is either electroplated, built up with electroless plating, or encapsulated in a polymer cylinder such as epoxy to increase the diameter of the wire for easier handling and greater robustness. During this process, the wire is vertically oriented and tensioned to assure that the wire is absolutely straight. The coated and electroformed wire is bonded to a flat, rigid substrate and is then periodically segmented by cutting or etching a series of narrow slits or grooves into the wire. The wire is vertically oriented and tensioned during the bonding process to assure that it is straight. The original wire material is then chemically etched away through the slits or otherwise withdrawn to leave the hollow internal bore of the final tapered-capillary optical element.

The effects of silver coating on friction coefficient and shear bond strength of steel orthodontic brackets.

PubMed

Arash, Valiollah; Anoush, Keivan; Rabiee, Sayed Mahmood; Rahmatei, Manuchehr; Tavanafar, Saeid

2015-01-01

Aims of the present study was to measure frictional resistance between silver coated brackets and different types of arch wires, and shear bond strength of these brackets to the tooth. In an experimental clinical research 28 orthodontic brackets (standard, 22 slots) were coated with silver ions using electroplate method. Six brackets (coated: 3, uncoated: 3) were evaluated with Scanning Electron Microscopy and Atomic Force Microscopy. The amount of friction in 15 coated brackets was measured with three different kinds of arch wires (0.019 × 0.025-in stainless steel [SS], 0.018-in stainless steel [SS], 0.018-in Nickel-Titanium [Ni-Ti]) and compared with 15 uncoated steel brackets. In addition, shear bond strength values were compared between 10 brackets with silver coating and 10 regular brackets. Universal testing machine was used to measure shear bond strength and the amount of friction between the wires and brackets. SPSS 18 was used for data analysis with t-test. SEM and AFM results showed deposition of a uniform layer of silver, measuring 8-10 μm in thickness on bracket surfaces. Silver coating led to higher frictional forces in all the three types of arch wires, which was statistically significant in 0.019 × 0.025-in SS and 0.018-in Ni-Ti, but it did not change the shear bond strength significantly. Silver coating with electroplating method did not affect the bond strength of the bracket to enamel; in addition, it was not an effective method for decreasing friction in sliding mechanics. © Wiley Periodicals, Inc.

Flexible ultrasonic pipe inspection apparatus

DOEpatents

Jenkins, C.F.; Howard, B.D.

1998-06-23

A flexible, modular ultrasonic pipe inspection apparatus, comprises a flexible, hollow shaft that carries a plurality of modules, including at least one rotatable ultrasonic transducer, a motor/gear unit, and a position/signal encoder. The modules are connected by flexible knuckle joints that allow each module of the apparatus to change its relative orientation with respect to a neighboring module, while the shaft protects electrical wiring from kinking or buckling while the apparatus moves around a tight corner. The apparatus is moved through a pipe by any suitable means, including a tether or drawstring attached to the nose or tail, differential hydraulic pressure, or a pipe pig. The rotational speed of the ultrasonic transducer and the forward velocity of the apparatus are coordinated so that the beam sweeps out the entire interior surface of the pipe, enabling the operator to accurately assess the condition of the pipe wall and determine whether or not leak-prone corrosion damage is present. 7 figs.

Flexible ultrasonic pipe inspection apparatus

DOEpatents

Jenkins, Charles F.; Howard, Boyd D.

1998-01-01

A flexible, modular ultrasonic pipe inspection apparatus, comprising a flexible, hollow shaft that carries a plurality of modules, including at least one rotatable ultrasonic transducer, a motor/gear unit, and a position/signal encoder. The modules are connected by flexible knuckle joints that allow each module of the apparatus to change its relative orientation with respect to a neighboring module, while the shaft protects electrical wiring from kinking or buckling while the apparatus moves around a tight corner. The apparatus is moved through a pipe by any suitable means, including a tether or drawstring attached to the nose or tail, differential hydraulic pressure, or a pipe pig. The rotational speed of the ultrasonic transducer and the forward velocity of the apparatus are coordinated so that the beam sweeps out the entire interior surface of the pipe, enabling the operator to accurately assess the condition of the pipe wall and determine whether or not leak-prone corrosion damage is present.

Composite Bus Structure for the SMEX/WIRE Satellite

NASA Technical Reports Server (NTRS)

Rosanova, Giulio G.

1998-01-01

In an effort to reduce the weight and optimize the structural design of the Small Explorer (SMEX) Wide-Field Infrared Explorer (WIRE) spacecraft, it has become desirable to change the material and construction from mechanically fastened aluminum structure to a fully bonded fiber-reinforced composite (FRC) structure. GSFC has developed the WIRE spacecraft structural bus design concept, including the instrument and launch vehicle requirements. The WIRE Satellite is the fifth of a series of SMEX satellites to be launched once per year. GSFC has chosen Composite Optics Inc. (COI) as the prime contractor for the development and procurement of the WIRE composite structure. The detailed design of the fully bonded FRC structure is based on COI's Short Notice Accelerated Production SATellite ("SNAPSAT") approach. SNAPSAT is a state of the art design and manufacturing technology for advanced composite materials which utilizes flat-stock detail parts bonded together to produce a final structural assembly. The structural design approach adopted for the WIRE structure provides a very viable alternative to both traditional aluminum construction as well as high tech. molded type composite structures. This approach to composite structure design is much less costly than molded or honeycomb sandwich type composite construction, but may cost slightly more than conventional aluminum construction on the subsystem level. However on the overall program level the weight saving achieved is very cost effective, since the primary objective is to allocate more mass for science payloads.

Physical interpretation and development of ultrasonic nondestructive evaluation techniques applied to the quantitative characterization of textile composite materials

NASA Technical Reports Server (NTRS)

Miller, James G.

1995-01-01

In this Progress Report, the author describes the continuing research to explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize complex materials. Images obtained using an unmodified medical ultrasonic imaging system of a bonded aluminum plate sample with a simulated disbond region are presented. The disbond region was produced by adhering a piece of plain white paper to a piece of cellophane tape and applying the paper-tape combination to one of the aluminum plates. Because the area under the paper was not adhesively bonded to the aluminum plate, this arrangement more closely simulates a disbond. Images are also presented for an aluminum plate sample with an epoxy strip adhered to one side to help provide information for the interpretation of the images of the bonded aluminum plate sample containing the disbond region. These images are compared with corresponding conventional ultrasonic contact transducer measurements in order to provide information regarding the nature of the disbonded region. The results of this on-going investigation may provide a step toward the development of a rapid, real-time, and portable method of ultrasonic inspection and characterization based on linear array technology. In Section 2 of this Progress Report, the preparation of the aluminum plate specimens is described. Section 3 describes the method of linear array imaging. Sections 4 and 5 present the linear array images and results from contact transducer measurements, respectively. A discussion of the results are presented in Section 6.

Nondestructive Evaluation of Adhesive Bond Quality: State of the Art Review

DTIC Science & Technology

1989-06-01

conducted using a and Harnik (6) developed a quantitative medium-focused, 1/4-inch diameter, 10-MHz method of testing adhesive bonded joints transducer...Couchman." Spectral Analysis Tech- E. Harnik . "The Testing of Adhesive- nique of Ultrasonic NDT of Advanced Bonded Joints by a Very High Resolu

Nondestructive test of regenerative chambers

NASA Technical Reports Server (NTRS)

Malone, G. A.; Stauffis, R.; Wood, R.

1972-01-01

Flat panels simulating internally cooled regenerative thrust chamber walls were fabricated by electroforming, brazing and diffusion bonding to evaluate the feasibility of nondestructive evaluation techniques to detect bonds of various strength integrities. Ultrasonics, holography, and acoustic emission were investigated and found to yield useful and informative data regarding the presence of bond defects in these structures.

The effect of different final irrigant activation techniques on the bond strength of an epoxy resin-based endodontic sealer: a preliminary study.

PubMed

Topçuoğlu, Hüseyin Sinan; Tuncay, Öznur; Demirbuga, Sezer; Dinçer, Asiye Nur; Arslan, Hakan

2014-06-01

The aim of this study was to evaluate whether or not different final irrigation activation techniques affect the bond strength of an epoxy resin-based endodontic sealer (AH Plus; Dentsply DeTrey, Konstanz, Germany) to the root canal walls of different root thirds. Eighty single-rooted human mandibular premolars were prepared by using the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) to size F4, and a final irrigation regimen using 3% sodium hypochlorite and 17% EDTA was performed. The specimens were randomly divided into 4 groups (n = 20) according to the final irrigation activation technique used as follows: no activation (control), manual dynamic activation (MDA), CanalBrush (Coltene Whaledent, Altststten, Switzerland) activation, and ultrasonic activation. Five specimens from each group were prepared for scanning electron microscopic observation to assess the smear layer removal after the final irrigation procedures. All remaining roots were then obturated with gutta-percha and AH Plus sealer. A push-out test was used to measure the bond strength between the root canal dentin and AH Plus sealer. The data obtained from the push-out test were analyzed using 2-way analysis of variance and Tukey post hoc tests. The bond strength values mostly decreased in the coronoapical direction (P < .001). In the coronal and middle thirds, ultrasonic activiation showed a higher bond strength than other groups (P < .05). In the apical third, MDA displayed the highest bond strength to root dentin (P < .05). The majority of specimens exhibited cohesive failures. The bond strength of AH Plus sealer to root canal dentin may improve with ultrasonic activation in the coronal and middle thirds and MDA in the apical third. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Improved formula for continuous-wave measurements of ultrasonic phase velocity

NASA Technical Reports Server (NTRS)

Chern, E. J.; Cantrell, J. H., Jr.; Heyman, J. S.

1981-01-01

An improved formula for continuous-wave ultrasonic phase velocity measurements using contact transducers is derived from the transmission line theory. The effect of transducer-sample coupling bonds is considered for measurements of solid samples even though it is often neglected because of the difficulty of accurately determining the bond thickness. Computer models show that the present formula is more accurate than previous expressions. Laboratory measurements using contacting transducers with the present formula are compared to measurements using noncontacting (hence effectively correction-free) capacitive transducers. The results of the experiments verify the validity and accuracy of the new formula.

[Individual indirect bonding technique (IIBT) using set-up model].

PubMed

Kyung, H M

1989-01-01

There has been much progress in Edgewise Appliance since E.H. Angle. One of the most important procedures in edgewise appliance is correct bracket position. Not only conventional edgewise appliance but also straight wire appliance & lingual appliance cannot be used more effectively unless the bracket position is accurate. Improper bracket positioning may reveal much problems during treatment, especially in finishing state. It may require either rebonding after the removal of the malpositioned bracket or the greater number of arch wire and the more complex wire bending, causing much difficulty in performing effective treatments. This made me invent Individual Indirect Bonding Technique with the use of multi-purpose set-up model in order to determine a correct and objective bracket position according to individual patients. This technique is more accurate than former indirect bonding techniques in bracket positioning, because it decides the bracket position on a set-up model which has produced to have the occlusal relationship the clinician desired. This technique is especially effective in straight wire appliance and lingual appliance in which the correct bracket positioning is indispensible.

Measurement and Modeling of Dispersive Pulse Propagation in Drawn Wire Waveguides

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Kohl, Thomas W.; Rogers, Wayne P.

1995-01-01

An analytical model of dispersive pulse propagation in semi-infinite cylinders due to transient axially symmetric end conditions has been experimentally investigated. Specifically, the dispersive propagation of the first axially symmetric longitudinal mode in thin wire waveguides, which have ends in butt contact with longitudinal piezoelectric ultrasonic transducers, is examined. The method allows for prediction of a propagated waveform given a measured source waveform, together with the material properties of the cylinder. Alternatively, the source waveform can be extracted from measurement of the propagated waveform. The material properties required for implementation of the pulse propagation model are determined using guided wave phase velocity measurements. Hard tempered aluminum 1100 and 304 stainless steel wires, with 127, 305, and 406 micron diam., were examined. In general, the drawn wires were found to behave as transversely isotropic media.

Measurement and modeling of dispersive pulse propagation in draw wire waveguides

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Kohl, Thomas W.; Rogers, Wayne P.

1995-01-01

An analytical model of dispersive pulse propagation in semi-infinite cylinders due to transient axially symmetric end conditions has been experimentally investigated. Specifically, the dispersive propagation of the first axially symmetric longitudinal mode in thin wire waveguides, which have ends in butt contact with longitudinal piezoelectric ultrasonic transducers, is examined. The method allows for prediction of a propagated waveform given a measured source waveform, together with the material properties of the cylinder. Alternatively, the source waveform can be extracted from measurement of the propagated waveform. The material properties required for implementation of the pulse propagation model are determined using guided wave phase velocity measurements. Hard tempered aluminum 1100 and 304 stainless steel wires, with 127, 305, and 406 micron diam., were examined. In general, the drawn wires were found to behave as transversely isotropic media.

An integrated circuit with transmit beamforming flip-chip bonded to a 2-D CMUT array for 3-D ultrasound imaging.

PubMed

Wygant, Ira O; Jamal, Nafis S; Lee, Hyunjoo J; Nikoozadeh, Amin; Oralkan, Omer; Karaman, Mustafa; Khuri-Yakub, Butrus T

2009-10-01

State-of-the-art 3-D medical ultrasound imaging requires transmitting and receiving ultrasound using a 2-D array of ultrasound transducers with hundreds or thousands of elements. A tight combination of the transducer array with integrated circuitry eliminates bulky cables connecting the elements of the transducer array to a separate system of electronics. Furthermore, preamplifiers located close to the array can lead to improved receive sensitivity. A combined IC and transducer array can lead to a portable, high-performance, and inexpensive 3-D ultrasound imaging system. This paper presents an IC flip-chip bonded to a 16 x 16-element capacitive micromachined ultrasonic transducer (CMUT) array for 3-D ultrasound imaging. The IC includes a transmit beamformer that generates 25-V unipolar pulses with programmable focusing delays to 224 of the 256 transducer elements. One-shot circuits allow adjustment of the pulse widths for different ultrasound transducer center frequencies. For receiving reflected ultrasound signals, the IC uses the 32-elements along the array diagonals. The IC provides each receiving element with a low-noise 25-MHz-bandwidth transimpedance amplifier. Using a field-programmable gate array (FPGA) clocked at 100 MHz to operate the IC, the IC generated properly timed transmit pulses with 5-ns accuracy. With the IC flip-chip bonded to a CMUT array, we show that the IC can produce steered and focused ultrasound beams. We present 2-D and 3-D images of a wire phantom and 2-D orthogonal cross-sectional images (Bscans) of a latex heart phantom.

Bond strength evaluation in adhesive joints using NDE and DIC methods

NASA Astrophysics Data System (ADS)

Poudel, Anish

Adhesive bonding of graphite epoxy composite laminates to itself or traditional metal alloys in modern aerospace and aircraft structural applications offers an excellent opportunity to use the most efficient and intelligent combination of materials available thus providing an attractive package for efficient structural designs. However, one of the major issues of adhesive bonding is the occasional formation of interfacial defects such as kissing or weak bonds in the bondline interface. Also, there are shortcomings of existing non-destructive evaluation (NDE) methods to non-destructively detect/characterize these interfacial defects and reliably predicting the bond shear strength. As a result, adhesive bonding technology is still not solely implemented in primary structures of an aircraft. Therefore, there is a greater demand for a novel NDE tool that can meet the existing aerospace requirement for adhesive bondline characterization. This research implemented a novel Acoustography ultrasonic imaging and digital image correlation (DIC) technique to detect and characterize interfacial defects in the bondline and determine bond shear strength in adhesively bonded composite-metal joints. Adhesively bonded Carbon Fiber Reinforced Plastic (CFRP) laminate and 2024-T3 Aluminum single lap shear panels subjected to various implanted kissing/weak bond defects were the primary focus of this study. Kissing/weak bonds were prepared by controlled surface contamination in the composite bonding surface and also by improperly mixing the adhesive constituent. SEM analyses were also conducted to understand the surface morphology of substrates and their interaction with the contaminants. Morphological changes were observed in the microscopic scale and the chemical analysis confirmed the stability of the contaminant at or very close to the interface. In addition, it was also demonstrated that contaminants migrated during the curing of the adhesive from CFRP substrate which caused a decrease of bond shear strength in single lap shear test samples. Through-transmission ultrasonics (TTU) Acoustography at 3.8 MHz showed promising results on the detectability of bondline defects in adhesively bonded CFRP-Al lap shear test samples. A correlation between Acoustography ultrasonic attenuation and average bond shear strength in CFRP-Al lap shear panels demonstrated that differential attenuation increased with the reduction of the bond shear strength. Similarly, optical DIC tests were conducted to identify and quantify kissing bond defects in CFRP-Al single lap shear joints. DIC results demonstrated changes in the normal strain (epsilonyy) contour map of the contaminated specimens at relatively lower load levels (15% ~ 30% of failure loads). Kissing bond regions were characterized by negative strains, and these were attributed to high compressive bending strains and the localized disbonding taking placed at the bondline interface as a result of the load application. It was also observed that contaminated samples suffered from more compressive strains (epsilonyy) compared to the baseline sample along the loading direction and they suffered from less compressive strains (epsilonxx) compared to the baseline sample perpendicular to the loading direction. This demonstrated the adverse effect of the kissing bond on the adhesive joint integrity. This was a very significant finding for the reason that hybrid ultrasonic DIC is being developed as a faster, more efficient, and more reliable NDE technique for determining bond quality and predicting bond shear strength in adhesively bonded structures.

Ultrasonic Non-destructive Prediction of Spot Welding Shear Strength

NASA Astrophysics Data System (ADS)

Himawan, R.; Haryanto, M.; Subekti, R. M.; Sunaryo, G. R.

2018-02-01

To enhance a corrosion resistant of ferritic steel in reactor pressure vessel, stainless steel was used as a cladding. Bonding process between these two steels may result a inhomogenity either sub-clad crack or un-joined part. To ensure the integrity, effective inspection method is needed for this purpose. Therefore, in this study, an experiment of ultrasonic test for inspection of two bonding plate was performed. The objective of this study is to develop an effective method in predicting the shear fracture load of the join. For simplicity, these joined was modelled with two plate of stainless steel with spot welding. Ultrasonic tests were performed using contact method with 5 MHz in frequency and 10 mm in diameter of transducer. Amplitude of reflected wave from intermediate layer was used as a quantitative parameter. A set of experiment results show that shear fracture load has a linear correlation with amplitude of reflected wave. Besides, amplitude of reflected wave also has relation with nugget diameter. It could be concluded that ultrasonic contact method could be applied in predicting a shear fracture load.

Laser Indirect Shock Welding of Fine Wire to Metal Sheet.

PubMed

Wang, Xiao; Huang, Tao; Luo, Yapeng; Liu, Huixia

2017-09-12

The purpose of this paper is to present an advanced method for welding fine wire to metal sheet, namely laser indirect shock welding (LISW). This process uses silica gel as driver sheet to accelerate the metal sheet toward the wire to obtain metallurgical bonding. A series of experiments were implemented to validate the welding ability of Al sheet/Cu wire and Al sheet/Ag wire. It was found that the use of a driver sheet can maintain high surface quality of the metal sheet. With the increase of laser pulse energy, the bonding area of the sheet/wire increased and the welding interfaces were nearly flat. Energy dispersive spectroscopy (EDS) results show that the intermetallic phases were absent and a short element diffusion layer which would limit the formation of the intermetallic phases emerging at the welding interface. A tensile shear test was used to measure the mechanical strength of the welding joints. The influence of laser pulse energy on the tensile failure modes was investigated, and two failure modes, including interfacial failure and failure through the wire, were observed. The nanoindentation test results indicate that as the distance to the welding interface decreased, the microhardness increased due to the plastic deformation becoming more violent.

Optical fiber interferometer for the study of ultrasonic waves in composite materials

NASA Technical Reports Server (NTRS)

Claus, R. O.; Zewekh, P. S.; Turner, T. M.; Wade, J. C.; Rogers, R. T.; Garg, A. O.

1981-01-01

The possibility of acoustic emission detection in composites using embedded optical fibers as sensing elements was investigated. Optical fiber interferometry, fiber acoustic sensitivity, fiber interferometer calibration, and acoustic emission detection are reported. Adhesive bond layer dynamical properties using ultrasonic interface waves, the design and construction of an ultrasonic transducer with a two dimensional Gaussian pressure profile, and the development of an optical differential technique for the measurement of surface acoustic wave particle displacements and propagation direction are also examined.

Ultrasonic guided wave bondline evaluation of thick metallic structures with viscoelastic coatings and the demonstration of a novel mode sweep technique

NASA Astrophysics Data System (ADS)

Bostron, Jason

Ultrasonic guided waves are becoming more widely used in nondestructive evaluation applications due to their efficiency in defect detection, ability to inspect hidden areas, and other reasons. This dissertation addresses two main topics: ultrasonic guided wave bond evaluation of thin and thick coatings on thick metallic structures, and the use of a novel phased array technique for optimal guided wave mode and frequency selection. (Abstract shortened by UMI.).

Ultrahigh Frequency (100 MHz–300 MHz) Ultrasonic Transducers for Optical Resolution Medical Imagining

PubMed Central

Fei, Chunlong; Chiu, Chi Tat; Chen, Xiaoyang; Chen, Zeyu; Ma, Jianguo; Zhu, Benpeng; Shung, K. Kirk; Zhou, Qifa

2016-01-01

High resolution ultrasonic imaging requires high frequency wide band ultrasonic transducers, which produce short pulses and highly focused beam. However, currently the frequency of ultrasonic transducers is limited to below 100 MHz, mainly because of the challenge in precise control of fabrication parameters. This paper reports the design, fabrication, and characterization of sensitive broadband lithium niobate (LiNbO3) single element ultrasonic transducers in the range of 100–300 MHz, as well as their applications in high resolution imaging. All transducers were built for an f-number close to 1.0, which was achieved by press-focusing the piezoelectric layer into a spherical curvature. Characterization results demonstrated their high sensitivity and a −6 dB bandwidth greater than 40%. Resolutions better than 6.4 μm in the lateral direction and 6.2 μm in the axial direction were achieved by scanning a 4 μm tungsten wire target. Ultrasonic biomicroscopy images of zebrafish eyes were obtained with these transducers which demonstrate the feasibility of high resolution imaging with a performance comparable to optical resolution. PMID:27329379

Next Generation Wiring

NASA Technical Reports Server (NTRS)

Medelius, Petro; Jolley, Scott; Fitzpatrick, Lilliana; Vinje, Rubiela; Williams, Martha; Clayton, LaNetra; Roberson, Luke; Smith, Trent; Santiago-Maldonado, Edgardo

2007-01-01

Wiring is a major operational component on aerospace hardware that accounts for substantial weight and volumetric space. Over time wire insulation can age and fail, often leading to catastrophic events such as system failure or fire. The next generation of wiring must be reliable and sustainable over long periods of time. These features will be achieved by the development of a wire insulation capable of autonomous self-healing that mitigates failure before it reaches a catastrophic level. In order to develop a self-healing insulation material, three steps must occur. First, methods of bonding similar materials must be developed that are capable of being initiated autonomously. This process will lead to the development of a manual repair system for polyimide wire insulation. Second, ways to initiate these bonding methods that lead to materials that are similar to the primary insulation must be developed. Finally, steps one and two must be integrated to produce a material that has no residues from the process that degrades the insulating properties of the final repaired insulation. The self-healing technology, teamed with the ability to identify and locate damage, will greatly improve reliability and safety of electrical wiring of critical systems. This paper will address these topics, discuss the results of preliminary testing, and remaining development issues related to self-healing wire insulation.

Stainless hooks to bond lower lingual retainer.

PubMed

Durgekar, Sujala G; Nagaraj, K

2011-01-01

We introduced a simple and economical technique for precise placement of lower lingual retainers. Two stainless steel hooks made of 0.6mm wire are placed interdentally in the embrasure area between canine and lateral incisor bilaterally to lock the retainer wire in the correct position. Etch, rinse and dry the enamel surfaces with the retainer passively in place, then bond the retainer with light-cured adhesive. Hooks are simple to fabricate and eliminate the need for a transfer tray.

The effect of prior sandblasting of the wire on the shear bond strength of two different types of lingual retainers.

PubMed

Kilinç, Delal Dara; Sayar, Gülşilay

2018-04-07

The aim of this study was to evaluate the effect of total surface sandblasting on the shear bond strength of two different retainer wires. The null hypothesis was that there is no difference in the bond strength of the two types of lingual retainer wires when they are sandblasted. One hundred and sixty human premolar teeth were equally divided into four groups (n=40). A pair of teeth was embedded in self-curing acrylic resin and polished. Retainer wires were applied on the etched and rinsed surfaces of the teeth. Four retainers were used: group 1: braided retainer (0.010×0.028″, Ortho Technology); group 2: sandblasted braided retainer (0.010×0.028″, Ortho Technology); group 3: coaxial retainer (0.0215″ Coaxial, 3M) and group 4: sandblasted coaxial retainer (0.0215″ Coaxial, 3M). The specimens were tested using a universal test machine in shear mode with a crosshead speed of one mm/min. One-way analysis of variance (Anova) was used to determine the significant differences among the groups. There was no significant difference (P=0.117) among the groups according to this test. The null hypothesis was accepted. There was no statistically significant difference among the shear bond strength values of the four groups. Copyright © 2018 CEO. Published by Elsevier Masson SAS. All rights reserved.

Attaching Copper Wires to Magnetic-Reed-Switch Leads

NASA Technical Reports Server (NTRS)

Kamila, Rudolf

1987-01-01

Bonding method reliably joins copper wires to short iron-alloy leads from glass-encased dry magnetic-reed switch without disturbing integrity of glass-to-metal seal. Joint resistant to high temperatures and has low electrical resistance.

Universal behavior of surface-dangling bonds in hydrogen-terminated Si, Ge, and Si/Ge nanowires.

NASA Astrophysics Data System (ADS)

Nunes, Ricardo; Kagimura, Ricardo; Chacham, Hélio

2007-03-01

We report an ab initio study of the electronic properties of surface dangling bond (SDB) states in hydrogen-terminated Si, Ge, and Si/Ge nanowires with diameters between 1 and 2 nm. We find that the charge transition levels ɛ(+/-) of SDB states are deep in the bandgap for Si wires, and shallow (near the valence band edge) for Ge wires. In both Si and Ge wires, the SDB states are localized. We also find that the SDB ɛ(+/-) levels behave as a ``universal" energy reference level among Si, Ge, and Si/Ge wires within a precision of 0.1 eV. By computing the average bewteen the electron affinity and ionization energy in the atomi limit of several atoms from the III, IV and V columns, we conjecture that the universality is a periodic-table atomic property.

Measured opening characteristics of an electromagnetically opened diaphragm for the Langley expansion tunnel

NASA Technical Reports Server (NTRS)

Moore, J. A.

1976-01-01

Results from an experimental study of the opening characteristics of an electromagnetically opened, 15.24 cm diameter diaphragm are presented. This diaphragm consists of a polyester film bonded to a preformed wire and is opened by passing a current pulse (capacitor discharge) through the wire. The diaphragm separates the acceleration section of the expansion tunnel from the nozzle so that the nozzle may be at a lower pressure than the acceleration section prior to a test. Opening times and cleanness of the opened area were examined for dependence on diaphragm thickness, on wire diameter, on technique of bonding the wire to the diaphragm, and on voltage and energy level of the energy source. Time histories of the pitot pressure measured at the expansion-tunnel nozzle entrance location are presented for (1) no diaphragm, (2) a flow-opened diaphragm, and (3) an electromagnetically opened diaphragm.

Rapid adhesive bonding of advanced composites and titanium

NASA Technical Reports Server (NTRS)

Stein, B. A.; Tyeryart, J. R.; Hodgest, W. T.

1985-01-01

Rapid adhesive bonding (RAB) concepts utilize a toroid induction technique to heat the adhesive bond line directly. This technique was used to bond titanium overlap shear specimens with 3 advanced thermoplastic adhesives and APC-2 (graphite/PEEK) composites with PEEK film. Bond strengths equivalent to standard heated-platen press bonds were produced with large reductions in process time. RAB produced very strong bonds in APC-2 adherend specimens; the APC-2 adherends were highly resistant to delamination. Thermal cycling did not significantly affect the shear strengths of RAB titanium bonds with polyimide adhesives. A simple ultrasonic non-destructive evaluation process was found promising for evaluating bond quality.

Laser Indirect Shock Welding of Fine Wire to Metal Sheet

PubMed Central

Wang, Xiao; Huang, Tao; Luo, Yapeng; Liu, Huixia

2017-01-01

The purpose of this paper is to present an advanced method for welding fine wire to metal sheet, namely laser indirect shock welding (LISW). This process uses silica gel as driver sheet to accelerate the metal sheet toward the wire to obtain metallurgical bonding. A series of experiments were implemented to validate the welding ability of Al sheet/Cu wire and Al sheet/Ag wire. It was found that the use of a driver sheet can maintain high surface quality of the metal sheet. With the increase of laser pulse energy, the bonding area of the sheet/wire increased and the welding interfaces were nearly flat. Energy dispersive spectroscopy (EDS) results show that the intermetallic phases were absent and a short element diffusion layer which would limit the formation of the intermetallic phases emerging at the welding interface. A tensile shear test was used to measure the mechanical strength of the welding joints. The influence of laser pulse energy on the tensile failure modes was investigated, and two failure modes, including interfacial failure and failure through the wire, were observed. The nanoindentation test results indicate that as the distance to the welding interface decreased, the microhardness increased due to the plastic deformation becoming more violent. PMID:28895900

Low-cost ultrasonic lamb-wave transducer

NASA Technical Reports Server (NTRS)

Kammerer, C. C.

1978-01-01

Transducer propagates Lamb wave through thin aluminum sheet material. Model includes two elements that measure effects of damping and loading which, in turn, are indirectly equated to bond integrity. Transducer has been used to evaluate bond integrity of aluminum facing adhesively bonded to aluminum facing. Because of versatility, it is now possible to inspect many objects of different configurations that could not be reached with earlier transducers.

Ultrasonic fingerprint sensor using a piezoelectric micromachined ultrasonic transducer array integrated with complementary metal oxide semiconductor electronics

NASA Astrophysics Data System (ADS)

Lu, Y.; Tang, H.; Fung, S.; Wang, Q.; Tsai, J. M.; Daneman, M.; Boser, B. E.; Horsley, D. A.

2015-06-01

This paper presents an ultrasonic fingerprint sensor based on a 24 × 8 array of 22 MHz piezoelectric micromachined ultrasonic transducers (PMUTs) with 100 μm pitch, fully integrated with 180 nm complementary metal oxide semiconductor (CMOS) circuitry through eutectic wafer bonding. Each PMUT is directly bonded to a dedicated CMOS receive amplifier, minimizing electrical parasitics and eliminating the need for through-silicon vias. The array frequency response and vibration mode-shape were characterized using laser Doppler vibrometry and verified via finite element method simulation. The array's acoustic output was measured using a hydrophone to be ˜14 kPa with a 28 V input, in reasonable agreement with predication from analytical calculation. Pulse-echo imaging of a 1D steel grating is demonstrated using electronic scanning of a 20 × 8 sub-array, resulting in 300 mV maximum received amplitude and 5:1 contrast ratio. Because the small size of this array limits the maximum image size, mechanical scanning was used to image a 2D polydimethylsiloxane fingerprint phantom (10 mm × 8 mm) at a 1.2 mm distance from the array.

Ultrasonic Detection of Delamination and Material Characterization of Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Chen, Hung-Liang Roger; Zhang, Binwei; Alvin, Mary Anne; Lin, Yun

2012-12-01

This article describes ultrasonic nondestructive evaluation (NDE) to detect the changes of material properties and provide early warning of delamination in thermal barrier coating (TBC) systems. NDE tests were performed on single-crystal René N5 superalloy coupons that were coated with a commercially available MCrAlY bond coat and an air plasma sprayed 7% yttria-stabilized zirconia (YSZ) top coat deposited by Air Plasma Spray method, as well as Haynes 230 superalloy coupons coated with MCrA1Y bond coat, and an electron beam physical vapor deposit of 7% YSZ top coat. The TBC coupons were subjected to either cyclic or isothermal exposure for various lengths of time at temperatures ranging from 900 to 1100 °C. The ultrasonic measurements performed on the coupons had provided an early warning of delamination along the top coat/TGO interface before exposure time, when delamination occurred. The material's property (Young's modulus) of the top coat was estimated using the measured wave speeds. Finite element analysis (FEA) of the ultrasonic wave propagation was conducted on a simplified TBC system to verify experimental observations. The technique developed was also demonstrated on an as-manufactured turbine blade to estimate normalized top coat thickness measurements.

Bundled monocapillary optics

DOEpatents

Hirsch, Gregory

2002-01-01

A plurality of glass or metal wires are precisely etched to form the desired shape of the individual channels of the final polycapillary optic. This shape is created by carefully controlling the withdrawal speed of a group of wires from an etchant bath. The etched wires undergo a subsequent operation to create an extremely smooth surface. This surface is coated with a layer of material which is selected to maximize the reflectivity of the radiation being used. This reflective surface may be a single layer of material, or a multilayer coating for optimizing the reflectivity in a narrower wavelength interval. The collection of individual wires is assembled into a close-packed multi-wire bundle, and the wires are bonded together in a manner which preserves the close-pack configuration, irrespective of the local wire diameter. The initial wires are then removed by either a chemical etching procedure or mechanical force. In the case of chemical etching, the bundle is generally segmented by cutting a series of etching slots. Prior to removing the wire, the capillary array is typically bonded to a support substrate. The result of the process is a bundle of precisely oriented radiation-reflecting hollow channels. The capillary optic is used for efficiently collecting and redirecting the radiation from a source of radiation which could be the anode of an x-ray tube, a plasma source, the fluorescent radiation from an electron microprobe, a synchrotron radiation source, a reactor or spallation source of neutrons, or some other source.

ZnO nanorod arrays and direct wire bonding on GaN surfaces for rapid fabrication of antireflective, high-temperature ultraviolet sensors

NASA Astrophysics Data System (ADS)

So, Hongyun; Senesky, Debbie G.

2016-11-01

Rapid, cost-effective, and simple fabrication/packaging of microscale gallium nitride (GaN) ultraviolet (UV) sensors are demonstrated using zinc oxide nanorod arrays (ZnO NRAs) as an antireflective layer and direct bonding of aluminum wires to the GaN surface. The presence of the ZnO NRAs on the GaN surface significantly reduced the reflectance to less than 1% in the UV and 4% in the visible light region. As a result, the devices fabricated with ZnO NRAs and mechanically stable aluminum bonding wires (pull strength of 3-5 gf) showed higher sensitivity (136.3% at room temperature and 148.2% increase at 250 °C) when compared with devices with bare (uncoated) GaN surfaces. In addition, the devices demonstrated reliable operation at high temperatures up to 300 °C, supporting the feasibility of simple and cost-effective UV sensors operating with higher sensitivity in high-temperature conditions, such as in combustion, downhole, and space exploration applications.

Fast and reliable method to estimate losses of single-mode waveguides with an arbitrary 2D trajectory.

PubMed

Negredo, F; Blaicher, M; Nesic, A; Kraft, P; Ott, J; Dörfler, W; Koos, C; Rockstuhl, C

2018-06-01

Photonic wire bonds, i.e., freeform waveguides written by 3D direct laser writing, emerge as a technology to connect different optical chips in fully integrated photonic devices. With the long-term vision of scaling up this technology to a large-scale fabrication process, the in situ optimization of the trajectory of photonic wire bonds is at stake. A prerequisite for the real-time optimization is the availability of a fast loss estimator for single-mode waveguides of arbitrary trajectory. Losses occur because of the bending of the waveguides and at transitions among sections of the waveguide with different curvatures. Here, we present an approach that resides on the fundamental mode approximation, i.e., the assumption that the photonic wire bonds predominantly carry their energy in a single mode. It allows us to predict in a quick and reliable way the pertinent losses from pre-computed modal properties of the waveguide, enabling fast design of optimum paths.

Improvements in the Formation of Boron-Doped Diamond Coatings on Platinum Wires Using the Novel Nucleation Process (NNP)

PubMed Central

Fhaner, Mathew; Zhao, Hong; Bian, Xiaochun; Galligan, James J.; Swain, Greg M.

2010-01-01

In order to increase the initial nucleation density for the growth of boron-doped diamond on platinum wires, we employed the novel nucleation process (NNP) originally developed by Rotter et al. and discussed by others [1–3]. This pretreatment method involves (i) the initial formation of a thin carbon layer over the substrate followed by (ii) ultrasonic seeding of this “soft” carbon layer with nanoscale particles of diamond. This two-step pretreatment is followed by the deposition of boron-doped diamond by microwave plasma-assisted CVD. Both the diamond seed particles and sites on the carbon layer itself function as the initial nucleation zones for diamond growth from an H2-rich source gas mixture. We report herein on the characterization of the pre-growth carbon layer formed on Pt as well as boron-doped films grown for 2, 4 and 6 h post NNP pretreatment. Results from scanning electron microscopy, Raman spectroscopy and electrochemical studies are reported. The NNP method increases the initial nucleation density on Pt and leads to the formation of a continuous diamond film in a shorter deposition time than is typical for wires pretreated by conventional ultrasonic seeding. The results indicate that the pregrowth layer itself consists of nanoscopic domains of diamond and functions well to enhance the initial nucleation of diamond without any diamond powder seeding. PMID:21617759

Flowable composites for bonding orthodontic retainers.

PubMed

Tabrizi, Sama; Salemis, Elio; Usumez, Serdar

2010-01-01

To test the null hypothesis that there are no statistically significant differences between flowables and an orthodontic adhesive tested in terms of shear bond strength (SBS) and pullout resistance. To test the SBS of Light Bond, FlowTain, Filtek Supreme, and Tetric Flow were applied to the enamel surfaces of 15 teeth. Using matrices for application, each composite material was cured for 40 seconds and subjected to SBS testing. To test pullout resistance, 15 samples were prepared for each composite in which a wire was embedded; then the composite was cured for 40 seconds. Later, the ends of the wire were drawn up and tensile stress was applied until the resin failed. Findings were analyzed using an ANOVA and a Tukey HSD test. The SBS values for Light Bond, FlowTain, Filtek Supreme, and Tetric Flow were 19.0 +/- 10.9, 14.7 +/- 9.3, 22.4 +/- 16.3, and 16.8 +/- 11.8 MPa, respectively, and mean pullout values were 42.2 +/- 13.0, 24.0 +/- 6.9, 26.3 +/- 9.4, and 33.8 +/- 18.0 N, respectively. No statistically significant differences were found among the groups in terms of SBS (P > .05). On the other hand, Light Bond yielded significantly higher pullout values compared with the flowables Filtek Supreme and Flow-Tain (P < .01). However, there were no significant differences among the pullout values of flowables, nor between Light Bond and Tetric Flow (P > .05). The hypothesis is rejected. Light Bond yielded significantly higher pullout values compared with the flowables Filtek Supreme and FlowTain. However, flowable composites provided satisfactory SBS and wire pullout values, comparable to a standard orthodontic resin, and therefore can be used as an alternative for direct bonding of lingual retainers.

A Novel Method to Quantify Soil Aggregate Stability by Measuring Aggregate Bond Energies

NASA Astrophysics Data System (ADS)

Efrat, Rachel; Rawlins, Barry G.; Quinton, John N.; Watts, Chris W.; Whitmore, Andy P.

2016-04-01

Soil aggregate stability is a key indicator of soil quality because it controls physical, biological and chemical functions important in cultivated soils. Micro-aggregates are responsible for the long term sequestration of carbon in soil, therefore determine soils role in the carbon cycle. It is thus vital that techniques to measure aggregate stability are accurate, consistent and reliable, in order to appropriately manage and monitor soil quality, and to develop our understanding and estimates of soil as a carbon store to appropriately incorporate in carbon cycle models. Practices used to assess the stability of aggregates vary in sample preparation, operational technique and unit of results. They use proxies and lack quantification. Conflicting results are therefore drawn between projects that do not provide methodological or resultant comparability. Typical modern stability tests suspend aggregates in water and monitor fragmentation upon exposure to an un-quantified amount of ultrasonic energy, utilising a laser granulometer to measure the change in mean weight diameter. In this project a novel approach has been developed based on that of Zhu et al., (2009), to accurately quantify the stability of aggregates by specifically measuring their bond energies. The bond energies are measured operating a combination of calorimetry and a high powered ultrasonic probe, with computable output function. Temperature change during sonication is monitored by an array of probes which enables calculation of the energy spent heating the system (Ph). Our novel technique suspends aggregates in heavy liquid lithium heteropolytungstate, as opposed to water, to avoid exposing aggregates to an immeasurable disruptive energy source, due to cavitation, collisions and clay swelling. Mean weight diameter is measured by a laser granulometer to monitor aggregate breakdown after successive periods of calculated ultrasonic energy input (Pi), until complete dispersion is achieved and bond energy (Pb; input energy used in aggregate breakdown) can be calculated by the following equation: ΣPi - Ph = Pb The novel technique was tested by comparing the bond energies measured from a series of soil aggregates sampled from different land management histories, to the samples corresponding stability measurement obtained from standard modern stability tests. The effectiveness of the heavy liquid as a suspension (as opposed to water) was evaluated by comparing the bond energies of samples measured in both suspensions. Our results determine i) how disruptive water is in aggregate stability tests, ii) how accurate and representative standard aggregate stability tests are, and iii) how bond strength varies depending on land use. Keywords: Aggregate; Bond; Fragmentation; Soil; Sonication; Stability References: Zhu, Z. L., Minasny, B. & Field D. J. 2009. Measurement of aggregate bond energy using ultrasonic dispersion. European Journal of Soil Science, 60, 695-705

Structural Properties of Single-Strand Orthodontic Wires from a Proposed Alternative Standard Flexure Test.

DTIC Science & Technology

1984-01-01

structural system the orthodontic appliance consists intraorally of bands or bonded pads and the attached brackets , the arch wires, the ligatures, and any...RD-Ali5B 994 STRUCTURAL PROPERTIES OF SINGLE-STRAND ORTHODONTIC i/i WIRES FROM A PROPOSED__(U) AIR FORCE INST OF TECH WRIGHT-PATTERSON RFB OH M L... Orthodontic Wires From A Proposed Alternative - Standard Flexure Test 6. PERPOMING o1. REPORT NUMBER AUTNOR(e) I. CONTRACT O& GRANT NUMUER(a) Marion L

Non-destructive testing techniques based on nonlinear methods for assessment of debonding in single lap joints

NASA Astrophysics Data System (ADS)

Scarselli, G.; Ciampa, F.; Ginzburg, D.; Meo, M.

2015-04-01

Nonlinear ultrasonic non-destructive evaluation (NDE) methods can be used for the identification of defects within adhesive bonds as they rely on the detection of nonlinear elastic features for the evaluation of the bond strength. In this paper the nonlinear content of the structural response of a single lap joint subjected to ultrasonic harmonic excitation is both numerically and experimentally evaluated to identify and characterize the defects within the bonded region. Different metallic samples with the same geometry were experimentally tested in order to characterize the debonding between two plates by using two surface bonded piezoelectric transducers in pitch-catch mode. The dynamic response of the damaged samples acquired by the single receiver sensor showed the presence of higher harmonics (2nd and 3rd) and subharmonics of the fundamental frequencies. These nonlinear elastic phenomena are clearly due to nonlinear effects induced by the poor adhesion between the two plates. A new constitutive model aimed at representing the nonlinear material response generated by the interaction of the ultrasonic waves with the adhesive joint is also presented. Such a model is implemented in an explicit FE software and uses a nonlinear user defined traction-displacement relationship implemented by means of a cohesive material user model interface. The developed model is verified for the different geometrical and material configurations. Good agreement between the experimental and numerical nonlinear response showed that this model can be used as a simple and useful tool for understanding the quality of the adhesive joint.

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites.

PubMed

Florián-Algarín, David; Marrero, Raúl; Li, Xiaochun; Choi, Hongseok; Suárez, Oscar Marcelo

2018-03-10

This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl₂O₃ nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl₂O₃ nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al-γAl₂O₃ nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires' electrical conductivity compared with that of pure aluminum and aluminum-copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding.

High resolution structural characterisation of laser-induced defect clusters inside diamond

NASA Astrophysics Data System (ADS)

Salter, Patrick S.; Booth, Martin J.; Courvoisier, Arnaud; Moran, David A. J.; MacLaren, Donald A.

2017-08-01

Laser writing with ultrashort pulses provides a potential route for the manufacture of three-dimensional wires, waveguides, and defects within diamond. We present a transmission electron microscopy study of the intrinsic structure of the laser modifications and reveal a complex distribution of defects. Electron energy loss spectroscopy indicates that the majority of the irradiated region remains as sp3 bonded diamond. Electrically conductive paths are attributed to the formation of multiple nano-scale, sp2-bonded graphitic wires and a network of strain-relieving micro-cracks.

Design and demonstration of automated data analysis algorithms for ultrasonic inspection of complex composite panels with bonds

NASA Astrophysics Data System (ADS)

Aldrin, John C.; Forsyth, David S.; Welter, John T.

2016-02-01

To address the data review burden and improve the reliability of the ultrasonic inspection of large composite structures, automated data analysis (ADA) algorithms have been developed to make calls on indications that satisfy the detection criteria and minimize false calls. The original design followed standard procedures for analyzing signals for time-of-flight indications and backwall amplitude dropout. However, certain complex panels with varying shape, ply drops and the presence of bonds can complicate this interpretation process. In this paper, enhancements to the automated data analysis algorithms are introduced to address these challenges. To estimate the thickness of the part and presence of bonds without prior information, an algorithm tracks potential backwall or bond-line signals, and evaluates a combination of spatial, amplitude, and time-of-flight metrics to identify bonded sections. Once part boundaries, thickness transitions and bonded regions are identified, feature extraction algorithms are applied to multiple sets of through-thickness and backwall C-scan images, for evaluation of both first layer through thickness and layers under bonds. ADA processing results are presented for a variety of complex test specimens with inserted materials and other test discontinuities. Lastly, enhancements to the ADA software interface are presented, which improve the software usability for final data review by the inspectors and support the certification process.

Raman spectroscopy as a tool to investigate the structure and electronic properties of carbon-atom wires

PubMed Central

Milani, Alberto; Tommasini, Matteo; Russo, Valeria; Li Bassi, Andrea; Lucotti, Andrea; Cataldo, Franco

2015-01-01

Summary Graphene, nanotubes and other carbon nanostructures have shown potential as candidates for advanced technological applications due to the different coordination of carbon atoms and to the possibility of π-conjugation. In this context, atomic-scale wires comprised of sp-hybridized carbon atoms represent ideal 1D systems to potentially downscale devices to the atomic level. Carbon-atom wires (CAWs) can be arranged in two possible structures: a sequence of double bonds (cumulenes), resulting in a 1D metal, or an alternating sequence of single–triple bonds (polyynes), expected to show semiconducting properties. The electronic and optical properties of CAWs can be finely tuned by controlling the wire length (i.e., the number of carbon atoms) and the type of termination (e.g., atom, molecular group or nanostructure). Although linear, sp-hybridized carbon systems are still considered elusive and unstable materials, a number of nanostructures consisting of sp-carbon wires have been produced and characterized to date. In this short review, we present the main CAW synthesis techniques and stabilization strategies and we discuss the current status of the understanding of their structural, electronic and vibrational properties with particular attention to how these properties are related to one another. We focus on the use of vibrational spectroscopy to provide information on the structural and electronic properties of the system (e.g., determination of wire length). Moreover, by employing Raman spectroscopy and surface enhanced Raman scattering in combination with the support of first principles calculations, we show that a detailed understanding of the charge transfer between CAWs and metal nanoparticles may open the possibility to tune the electronic structure from alternating to equalized bonds. PMID:25821689

Magnetism in Mn-nanowires and -clusters as δ-doped layers in group IV semiconductors (Si, Ge)

NASA Astrophysics Data System (ADS)

Simov, K. R.; Glans, P.-A.; Jenkins, C. A.; Liberati, M.; Reinke, P.

2018-01-01

Mn doping of group-IV semiconductors (Si/Ge) is achieved by embedding nanostructured Mn-layers in group-IV matrix. The Mn-nanostructures are monoatomic Mn-wires or Mn-clusters and capped with an amorphous Si or Ge layer. The precise fabrication of δ-doped Mn-layers is combined with element-specific detection of the magnetic signature with x-ray magnetic circular dichroism. The largest moment (2.5 μB/Mn) is measured for Mn-wires with ionic bonding character and a-Ge overlayer cap; a-Si capping reduces the moment due to variations of bonding in agreement with theoretical predictions. The moments in δ-doped layers dominated by clusters is quenched with an antiferromagnetic component from Mn-Mn bonding.

Superconducting Multilayer High-Density Flexible Printed Circuit Board for Very High Thermal Resistance Interconnections

NASA Astrophysics Data System (ADS)

de la Broïse, Xavier; Le Coguie, Alain; Sauvageot, Jean-Luc; Pigot, Claude; Coppolani, Xavier; Moreau, Vincent; d'Hollosy, Samuel; Knarosovski, Timur; Engel, Andreas

2018-05-01

We have successively developed two superconducting flexible PCBs for cryogenic applications. The first one is monolayer, includes 552 tracks (10 µm wide, 20 µm spacing), and receives 24 wire-bonded integrated circuits. The second one is multilayer, with one track layer between two shielding layers interconnected by microvias, includes 37 tracks, and can be interconnected at both ends by wire bonding or by connectors. The first cold measurements have been performed and show good performances. The novelty of these products is, for the first one, the association of superconducting materials with very narrow pitch and bonded integrated circuits and, for the second one, the introduction of a superconducting multilayer structure interconnected by vias which is, to our knowledge, a world-first.

Length-dependent structural stability of linear monatomic Cu wires

NASA Astrophysics Data System (ADS)

Singh, Gurvinder; Kumar, Krishan; Singh, Baljinder; Moudgil, R. K.

2018-05-01

We present first-principle calculations based on density functional theory for the finite-length monatomic Cu atom linear wires. The structure and its stability with increasing wire length in terms of number of atoms (N) is determined. Interestingly, the bond length is found to exhibit an oscillatory structure (the so-called magic length phenomenon), with a qualitative change in oscillatory behavior as one moves from even N wire to odd N wire. The even N wires follow simple even-odd oscillations whereas odd N wires show a phase change at the half length of the wires. The stability of the wire structure, determined in terms of the wire formation energy, also contains even-odd oscillation as a function of wire length. However, the oscillations in formation energy reverse its phase after the wire length is increased beyond N=12. Our findings are seen to be qualitatively consistent with recent simulations for a similar class finite-length metal atom wires.

System Model for MEMS based Laser Ultrasonic Receiver

NASA Technical Reports Server (NTRS)

Wilson, William C.

2002-01-01

A need has been identified for more advanced nondestructive Evaluation technologies for assuring the integrity of airframe structures, wiring, etc. Laser ultrasonic inspection instruments have been shown to detect flaws in structures. However, these instruments are generally too bulky to be used in the confined spaces that are typical of aerospace vehicles. Microsystems technology is one key to reducing the size of current instruments and enabling increased inspection coverage in areas that were previously inaccessible due to instrument size and weight. This paper investigates the system modeling of a Micro OptoElectroMechanical System (MOEMS) based laser ultrasonic receiver. The system model is constructed in software using MATLAB s dynamical simulator, Simulink. The optical components are modeled using geometrical matrix methods and include some image processing. The system model includes a test bench which simulates input stimuli and models the behavior of the material under test.

Contact and Length Dependent Effects in Single-Molecule Electronics

NASA Astrophysics Data System (ADS)

Hines, Thomas

Understanding charge transport in single molecules covalently bonded to electrodes is a fundamental goal in the field of molecular electronics. In the past decade, it has become possible to measure charge transport on the single-molecule level using the STM break junction method. Measurements on the single-molecule level shed light on charge transport phenomena which would otherwise be obfuscated by ensemble measurements of groups of molecules. This thesis will discuss three projects carried out using STM break junction. In the first project, the transition between two different charge transport mechanisms is reported in a set of molecular wires. The shortest wires show highly length dependent and temperature invariant conductance behavior, whereas the longer wires show weakly length dependent and temperature dependent behavior. This trend is consistent with a model whereby conduction occurs by coherent tunneling in the shortest wires and by incoherent hopping in the longer wires. Measurements are supported with calculations and the evolution of the molecular junction during the pulling process is investigated. The second project reports controlling the formation of single-molecule junctions by means of electrochemically reducing two axial-diazonium terminal groups on a molecule, thereby producing direct Au-C covalent bonds in-situ between the molecule and gold electrodes. Step length analysis shows that the molecular junction is significantly more stable, and can be pulled over a longer distance than a comparable junction created with amine anchoring bonds. The stability of the junction is explained by the calculated lower binding energy associated with the direct Au-C bond compared with the Au-N bond. Finally, the third project investigates the role that molecular conformation plays in the conductance of oligothiophene single-molecule junctions. Ethyl substituted oligothiophenes were measured and found to exhibit temperature dependent conductance and transition voltage for molecules with between two and six repeat units. While the molecule with only one repeat unit shows temperature invariant behavior. Density functional theory calculations show that at higher temperatures the oligomers with multiple repeat units assume a more planar conformation, which increases the conjugation length and decreases the effective energy barrier of the junction.

Ultrasonic Sensor Signals and Optimum Path Forest Classifier for the Microstructural Characterization of Thermally-Aged Inconel 625 Alloy

PubMed Central

de Albuquerque, Victor Hugo C.; Barbosa, Cleisson V.; Silva, Cleiton C.; Moura, Elineudo P.; Rebouças Filho, Pedro P.; Papa, João P.; Tavares, João Manuel R. S.

2015-01-01

Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ” and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF) classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 °C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms) and accurate (accuracy of 88.75% and harmonic mean of 89.52) for the application proposed. PMID:26024416

Ultrasonic sensor signals and optimum path forest classifier for the microstructural characterization of thermally-aged inconel 625 alloy.

PubMed

de Albuquerque, Victor Hugo C; Barbosa, Cleisson V; Silva, Cleiton C; Moura, Elineudo P; Filho, Pedro P Rebouças; Papa, João P; Tavares, João Manuel R S

2015-05-27

Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ'' and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF) classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 °C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms) and accurate (accuracy of 88.75%" and harmonic mean of 89.52) for the application proposed.

Laser ablated micropillar energy directors for ultrasonic welding of microfluidic systems

NASA Astrophysics Data System (ADS)

Esben Poulsen, Carl; Kistrup, Kasper; Korsgaard Andersen, Nis; Taboryski, Rafael; Fougt Hansen, Mikkel; Wolff, Anders

2016-06-01

We present a new type of energy director (ED) for ultrasonic welding of microfluidic systems. These micropillar EDs are based on the replication of cone like protrusion structures introduced using a pico-second laser and may therefore be added to any mould surface accessible to a pico-second laser beam. The technology is demonstrated on an injection moulded microfluidic device featuring high-aspect ratio (h  ×  w  =  2000 μm  ×  550 μm) and free-standing channel walls, where bonding is achieved with no detectable channel deformation. The bonding strength is similar to conventional EDs and the fabricated system can withstand pressures of over 9.5 bar.

Ultrasonic fingerprint sensor using a piezoelectric micromachined ultrasonic transducer array integrated with complementary metal oxide semiconductor electronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Y.; Fung, S.; Wang, Q.

2015-06-29

This paper presents an ultrasonic fingerprint sensor based on a 24 × 8 array of 22 MHz piezoelectric micromachined ultrasonic transducers (PMUTs) with 100 μm pitch, fully integrated with 180 nm complementary metal oxide semiconductor (CMOS) circuitry through eutectic wafer bonding. Each PMUT is directly bonded to a dedicated CMOS receive amplifier, minimizing electrical parasitics and eliminating the need for through-silicon vias. The array frequency response and vibration mode-shape were characterized using laser Doppler vibrometry and verified via finite element method simulation. The array's acoustic output was measured using a hydrophone to be ∼14 kPa with a 28 V input, in reasonable agreement with predication from analyticalmore » calculation. Pulse-echo imaging of a 1D steel grating is demonstrated using electronic scanning of a 20 × 8 sub-array, resulting in 300 mV maximum received amplitude and 5:1 contrast ratio. Because the small size of this array limits the maximum image size, mechanical scanning was used to image a 2D polydimethylsiloxane fingerprint phantom (10 mm × 8 mm) at a 1.2 mm distance from the array.« less

Use of an ultrasonic device for the determination of elastic modulus of dentin.

PubMed

Miyazaki, Masashi; Inage, Hirohiko; Onose, Hideo

2002-03-01

The mechanical properties of dentin substrate are one of the important factors in determining bond strength of dentin bonding systems. The purpose of this study was to determine the elastic modulus of dentin substrate with the use of an ultrasonic device. The dentin disks of about 1 mm thickness were obtaining from freshly extracted human third molars, and the dentin disk was shaped in a rectangular form with a line diamond point. The size and weight of each specimen was measured to calculate the density of the specimen. The ultrasonic equipment employed in this study was composed of a Pulser-Receiver (Model 5900PR, Panametrics), transducers (V155, V156, Panametrics) and an oscilloscope. The measured two-way transit time through the dentin disk was divided by two to account for the down-and-back travel path, and then multiplied by the velocity of sound in the test material. Measuring the longitudinal and share wave sound velocity determine elastic modulus. The mean elastic modulus of horizontally sectioned specimens was 21.8 GPa and 18.5 GPa for the vertically sectioned specimens, and a significant difference was found between the two groups. The ultrasonic method used in this study shows considerable promise for determination of the elastic modulus of the tooth substrate.

Thermal injury through intraradicular heat transfer using ultrasonic devices: precautions and practical preventive strategies.

PubMed

Gluskin, Alan H; Ruddle, Clifford J; Zinman, Edwin J

2005-09-01

The use of ultrasonic energy is a highly efficient method of removing obstructions and cements within the root canal space when re-treatment or rehabilitation of that ultrasonic energy dislodges and removes cemented objects from the bonded interface of the canal wall. When using this method, there is less potential for structural loss or root damage and significantly less operator stress than when using other methods. There is little evidence in published research of the considerable heat transfer that occurs during use of ultrasonic devices to remove posts, pastes and separated instruments in teeth. The authors present three cases of patients who experienced serious burn injuries during application of ultrasonic energy for restorative dentistry. The authors also offer techniques and strategies for safe and effective use of ultrasonic devices. On the basis of the best available evidence, the authors recommend strategies to provide safe and effective therapy while using ultrasonic devices in intraradicular obstruction removal. The intent of the suggested protocols is to provide advanced and sophisticated therapies in a safe and regulated manner with patient safety as an overriding priority.

Fast synthesize ZnO quantum dots via ultrasonic method.

PubMed

Yang, Weimin; Zhang, Bing; Ding, Nan; Ding, Wenhao; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

2016-05-01

Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots. Copyright © 2015 Elsevier B.V. All rights reserved.

Lingual straight wire method.

PubMed

Takemoto, Kyoto; Scuzzo, Giuseppe; Lombardo, L U C A; Takemoto, Y U I

2009-12-01

The mushroom arch-wire is mainly used in lingual orthodontic treatment but the complicated wire bending it requires affects both the treatment results and the time spent at the chair. The author proposes a new lingual straight wire method (LSW) in order to facilitate arch coordination and simplify the mechanics. The attention paid to the set-up model and bracket positioning and bonding plus the use of the new LSW method will also improve patient comfort. Copyright 2009 Collège Européen d'Orthodontie. Published by Elsevier Masson SAS.. All rights reserved.

Ultrasonic Welding of Hybrid Joints

NASA Astrophysics Data System (ADS)

Wagner, Guntram; Balle, Frank; Eifler, Dietmar

2012-03-01

A central research field of the Institute of Materials Science and Engineering at the University of Kaiserslautern (WKK), Germany, is the realization of innovative hybrid joints by ultrasonic metal welding. This article gives an overview of suitable ultrasonic welding systems as well as of essential machine and material parameters, which influence the quality of the welds. Besides the ultrasonic welding of dissimilar metals such as Al to Cu or Al to steels, the welds between newly developed materials like aluminum foam sandwiches or flat flexible cables also can be realized. Moreover, the joining of glass and ceramic to sheet metals is a point of interest at the WKK. By using the ultrasonic metal welding process, it is possible to realize metal/glass welds with tensile shear strengths of 50 MPa. For metal/ceramic joints, the shear strengths values up to 150 MPa were measured. Finally, selected results about the occurring bonding mechanisms will be discussed.

Ultrasonic test of resistance spot welds based on wavelet package analysis.

PubMed

Liu, Jing; Xu, Guocheng; Gu, Xiaopeng; Zhou, Guanghao

2015-02-01

In this paper, ultrasonic test of spot welds for stainless steel sheets has been studied. It is indicated that traditional ultrasonic signal analysis in either time domain or frequency domain remains inadequate to evaluate the nugget diameter of spot welds. However, the method based on wavelet package analysis in time-frequency domain can easily distinguish the nugget from the corona bond by extracting high-frequency signals in different positions of spot welds, thereby quantitatively evaluating the nugget diameter. The results of ultrasonic test fit the actual measured value well. Mean value of normal distribution of error statistics is 0.00187, and the standard deviation is 0.1392. Furthermore, the quality of spot welds was evaluated, and it is showed ultrasonic nondestructive test based on wavelet packet analysis can be used to evaluate the quality of spot welds, and it is more reliable than single tensile destructive test. Copyright © 2014 Elsevier B.V. All rights reserved.

Microstructural evolution and micromechanical properties of gamma-irradiated Au ball bonds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yusoff, Wan Yusmawati Wan, E-mail: yusmawati@upnm.edu.my; Ismail, Roslina, E-mail: roslina.ismail@ukm.my; Jalar, Azman, E-mail: azmn@ukm.my

2014-07-01

The effect of gamma radiation on the mechanical and structural properties of gold ball bonds was investigated. Gold wires from thermosonic wire bonding were exposed to gamma rays from a Cobalt-60 source at a low dose (5 Gy). The load–depth curve of nanoindentation for the irradiated gold wire bond has an apparent staircase shape during loading compared to the as-received sample. The hardness of the specimens calculated from the nanoindentation shows an increase in value from 0.91 to 1.09 GPa for specimens after exposure. The reduced elastic modulus for irradiated specimens significantly increased as well, with values from 75.18 tomore » 98.55 GPa. The change in intrinsic properties due to gamma radiation was investigated using dual-focused ion beam and high-resolution transmission electron microscope analysis. The dual-focused ion beam and high-resolution transmission electron microscope images confirmed the changes in grain structure and the presence of dislocations. The scanning electron microscope micrographs of focused ion beam cross sections showed that the grain structure of the gold became elongated and smaller after exposure to gamma rays. Meanwhile, high-resolution transmission electron microscopy provided evidence that gamma radiation induced dislocation of the atomic arrangement. - Highlights: • Nanoindentation technique provides a detailed characterisation of Au ball bond. • P–h curve of irradiated Au ball bond shows an apparent pop-in event. • Hardness and reduced modulus increased after exposure. • Elongated and smaller grain structure in irradiated specimens • Prevalent presence of dislocations in the atomic arrangement.« less

Destructive and non-destructive evaluation of cu/cu diffusion bonding with interlayer aluminum

NASA Astrophysics Data System (ADS)

Santosh Kumar, A.; Mohan, T.; Kumar, S. Suresh; Ravisankar, B.

2018-03-01

The current study is established an inspection procedure for assessing quality of diffusion bonded joints using destructive and non-destructive method. Diffusion bonding of commercially pure copper with aluminium interlayer was carried out uniaxial load at 15MPa for different temperatures under holding time 60 min in vacuum atmosphere. The bond qualities were determined by destructive and non-destructive testing method (ultrasonic C- scan). The bond interface and bonded samples were analysed using optical and scanning electron microscopy (SEM). The element composition of the fractured and bonded area is determined using the Energy Dispersive Spectrometry (EDS). The bond quality obtained by both testing methods and its parameters are correlated. The optimized bonding parameter for best bonding characteristics for copper diffusion bonding with aluminum interlayer is reported.

Acoustic Monitoring of Adhesive Bond Curing in Wood Laminates.

NASA Astrophysics Data System (ADS)

Biernacki, Jacek Marek

Challenges in manufacturing of wood products, such as glulam, include difficulty in controlling bonding variables and assessing bond quality. This dissertation investigates an ultrasonic method as a means of monitoring of curing and assessing bond quality in wood laminates. The effect of curing on ultrasonic transmission was studied using specimens of clear Douglas-fir, 100 x 200 x 600 mm, with the adhesive bond in the center of the specimen. Monitoring was performed simultaneously at normal and angular (5 ^circ nominal) incidence to the bond plane. Acoustic measurements were supplemented with destructive cure monitoring, standard bond strength measurement, monitoring of bulk viscosity curing, gel time measurement, and microscopic (SEM) examination. Angular incidence gave greater sensitivity to bond quality and curing status than did normal incidence. Analysis of wave propagation showed that displacement for transmission at a small angle (on the order of 5^circ ) was nearly parallel to the bond, which seems to explain greater sensitivity of angular incidence. Experimental results showed that this method was effective in detection of curing phases, such as spread, penetration, and hardening, defective bonds, and the effect of clamping pressure. An "unloading effect", measured as a relative transmission reduction after the clamping load was released, was sensitive to defective bonds, including uncured (kissing), underspread, and uneven spread bonds. Thick bonds (0.5 and 1.0 mm) caused the greatest increase in transmission, since waves at start of curing were highly attenuated. In angular transmission, thick-bond curing curves showed a characteristic inflection, which may be used to identify thick bonds and measure the curing rate. The results of this dissertation could be utilized to develop commercial systems in glulam manufacturing, which could evaluate: (a) phase of and completion of curing (b) bond quality (c) optimum clamping pressure. Similar systems could also be developed to monitor lumber and panel products curing at high temperature, such as LVL (laminated veneer lumber), OSB (oriented strandboard) and particleboard.

High-Temperature High-Power Packaging Techniques for HEV Traction Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elshabini, Aicha; Barlow, Fred D.

A key issue associated with the wider adoption of hybrid-electric vehicles (HEV) and plug in hybrid-electric vehicles (PHEV) is the implementation of the power electronic systems that are required in these products. One of the primary industry goals is the reduction in the price of these vehicles relative to the cost of traditional gasoline powered vehicles. Today these systems, such as the Prius, utilize one coolant loop for the engine at approximately 100 C coolant temperatures, and a second coolant loop for the inverter at 65 C. One way in which significant cost reduction of these systems could be achievedmore » is through the use of a single coolant loop for both the power electronics as well as the internal combustion engine (ICE). This change in coolant temperature significantly increases the junction temperatures of the devices and creates a number of challenges for both device fabrication and the assembly of these devices into inverters and converters for HEV and PHEV applications. Traditional power modules and the state-of-the-art inverters in the current HEV products, are based on chip and wire assembly and direct bond copper (DBC) on ceramic substrates. While a shift to silicon carbide (SiC) devices from silicon (Si) devices would allow the higher operating temperatures required for a single coolant loop, it also creates a number of challenges for the assembly of these devices into power inverters. While this traditional packaging technology can be extended to higher temperatures, the key issues are the substrate material and conductor stability, die bonding material, wire bonds, and bond metallurgy reliability as well as encapsulation materials that are stable at high operating temperatures. The larger temperature differential during power cycling, which would be created by higher coolant temperatures, places tremendous stress on traditional aluminum wire bonds that are used to interconnect power devices. Selection of the bond metallurgy and wire bond geometry can play a key role in mitigating this stress. An alternative solution would be to eliminate the wire bonds completely through a fundamentally different method of forming a reliable top side interconnect. Similarly, the solders used in most power modules exhibit too low of a liquidus to be viable solutions for maximum junction temperatures of 200 C. Commonly used encapsulation materials, such as silicone gels, also suffer from an inability to operate at 200 C for extended periods of time. Possible solutions to these problems exist in most cases but require changes to the traditional manufacturing process used in these modules. In addition, a number of emerging technologies such as Si nitride, flip-chip assembly methods, and the elimination of base-plates would allow reliable module development for operation of HEV and PHEV inverters at elevated junction temperatures.« less

Iridium Interfacial Stack - IrIS

NASA Technical Reports Server (NTRS)

Spry, David

2012-01-01

Iridium Interfacial Stack (IrIS) is the sputter deposition of high-purity tantalum silicide (TaSi2-400 nm)/platinum (Pt-200 nm)/iridium (Ir-200 nm)/platinum (Pt-200 nm) in an ultra-high vacuum system followed by a 600 C anneal in nitrogen for 30 minutes. IrIS simultaneously acts as both a bond metal and a diffusion barrier. This bondable metallization that also acts as a diffusion barrier can prevent oxygen from air and gold from the wire-bond from infiltrating silicon carbide (SiC) monolithically integrated circuits (ICs) operating above 500 C in air for over 1,000 hours. This TaSi2/Pt/Ir/Pt metallization is easily bonded for electrical connection to off-chip circuitry and does not require extra anneals or masking steps. There are two ways that IrIS can be used in SiC ICs for applications above 500 C: it can be put directly on a SiC ohmic contact metal, such as Ti, or be used as a bond metal residing on top of an interconnect metal. For simplicity, only the use as a bond metal is discussed. The layer thickness ratio of TaSi2 to the first Pt layer deposited thereon should be 2:1. This will allow Si from the TaSi2 to react with the Pt to form Pt2Si during the 600 C anneal carried out after all layers have been deposited. The Ir layer does not readily form a silicide at 600 C, and thereby prevents the Si from migrating into the top-most Pt layer during future anneals and high-temperature IC operation. The second (i.e., top-most) deposited Pt layer needs to be about 200 nm to enable easy wire bonding. The thickness of 200 nm for Ir was chosen for initial experiments; further optimization of the Ir layer thickness may be possible via further experimentation. Ir itself is not easily wire-bonded because of its hardness and much higher melting point than Pt. Below the iridium layer, the TaSi2 and Pt react and form desired Pt2Si during the post-deposition anneal while above the iridium layer remains pure Pt as desired to facilitate easy and strong wire-bonding to the SiC chip circuitry.

Structural Health Monitoring of Above-Ground Storage Tank Floors by Ultrasonic Guided Wave Excitation on the Tank Wall.

PubMed

Lowe, Premesh S; Duan, Wenbo; Kanfoud, Jamil; Gan, Tat-Hean

2017-11-04

There is an increasing interest in using ultrasonic guided waves to assess the structural degradation of above-ground storage tank floors. This is a non-invasive and economically viable means of assessing structural degradation. Above-ground storage tank floors are ageing assets which need to be inspected periodically to avoid structural failure. At present, normal-stress type transducers are bonded to the tank annular chime to generate a force field in the thickness direction of the floor and excite fundamental symmetric and asymmetric Lamb modes. However, the majority of above-ground storage tanks in use have no annular chime due to a simplified design and/or have a degraded chime due to corrosion. This means that transducers cannot be mounted on the chime to assess structural health according to the present technology, and the market share of structural health monitoring of above-ground storage tank floors using ultrasonic guided wave is thus limited. Therefore, the present study investigates the potential of using the tank wall to bond the transducer instead of the tank annular chime. Both normal and shear type transducers were investigated numerically, and results were validated using a 4.1 m diameter above-ground storage tank. The study results show shear mode type transducers bonded to the tank wall can be used to assess the structural health of the above-ground tank floors using an ultrasonic guided wave. It is also shown that for the cases studied there is a 7.4 dB signal-to-noise ratio improvement at 45 kHz for the guided wave excitation on the tank wall using shear mode transducers.

Structural Health Monitoring of Above-Ground Storage Tank Floors by Ultrasonic Guided Wave Excitation on the Tank Wall

PubMed Central

Kanfoud, Jamil; Gan, Tat-Hean

2017-01-01

There is an increasing interest in using ultrasonic guided waves to assess the structural degradation of above-ground storage tank floors. This is a non-invasive and economically viable means of assessing structural degradation. Above-ground storage tank floors are ageing assets which need to be inspected periodically to avoid structural failure. At present, normal-stress type transducers are bonded to the tank annular chime to generate a force field in the thickness direction of the floor and excite fundamental symmetric and asymmetric Lamb modes. However, the majority of above-ground storage tanks in use have no annular chime due to a simplified design and/or have a degraded chime due to corrosion. This means that transducers cannot be mounted on the chime to assess structural health according to the present technology, and the market share of structural health monitoring of above-ground storage tank floors using ultrasonic guided wave is thus limited. Therefore, the present study investigates the potential of using the tank wall to bond the transducer instead of the tank annular chime. Both normal and shear type transducers were investigated numerically, and results were validated using a 4.1 m diameter above-ground storage tank. The study results show shear mode type transducers bonded to the tank wall can be used to assess the structural health of the above-ground tank floors using an ultrasonic guided wave. It is also shown that for the cases studied there is a 7.4 dB signal-to-noise ratio improvement at 45 kHz for the guided wave excitation on the tank wall using shear mode transducers. PMID:29113058

Joining Tubes With Adhesive

NASA Technical Reports Server (NTRS)

Bateman, W. A.

1984-01-01

Cylindrical tubes joined together, end to end, by method employing adhesive, tapered ends, and spacing wires. Tapered joint between tubular structural elements provides pressure between bonding surfaces during adhesive curing. Spacing wires prevent adhesive from being scraped away when one element inserted in other. Method developed for assembling structural elements made of composite materials.

46 CFR 35.35-5 - Electrical bonding-TB/ALL.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 1 2013-10-01 2013-10-01 false Electrical bonding-TB/ALL. 35.35-5 Section 35.35-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-5 Electrical bonding—TB/ALL. The use of a vessel/shore bonding cable or wire is permissible only if...

46 CFR 35.35-5 - Electrical bonding-TB/ALL.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 1 2014-10-01 2014-10-01 false Electrical bonding-TB/ALL. 35.35-5 Section 35.35-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-5 Electrical bonding—TB/ALL. The use of a vessel/shore bonding cable or wire is permissible only if...

One kilometer (1 km) electric solar wind sail tether produced automatically.

PubMed

Seppänen, Henri; Rauhala, Timo; Kiprich, Sergiy; Ukkonen, Jukka; Simonsson, Martin; Kurppa, Risto; Janhunen, Pekka; Hæggström, Edward

2013-09-01

We produced a 1 km continuous piece of multifilament electric solar wind sail tether of μm-diameter aluminum wires using a custom made automatic tether factory. The tether comprising 90,704 bonds between 25 and 50 μm diameter wires is reeled onto a metal reel. The total mass of 1 km tether is 10 g. We reached a production rate of 70 m/24 h and a quality level of 1‰ loose bonds and 2‰ rebonded ones. We thus demonstrated that production of long electric solar wind sail tethers is possible and practical.

Thermoelectric performance of various benzo-difuran wires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Péterfalvi, Csaba G.; Grace, Iain; Manrique, Dávid Zs.

2014-05-07

Using a first principles approach to electron transport, we calculate the electrical and thermoelectrical transport properties of a series of molecular wires containing benzo-difuran subunits. We demonstrate that the side groups introduce Fano resonances, the energy of which is changing with the electronegativity of selected atoms in it. We also study the relative effect of single, double, or triple bonds along the molecular backbone and find that single bonds yield the highest thermopower, approximately 22 μV/K at room temperature, which is comparable with the highest measured values for single-molecule thermopower reported to date.

3D Modeling of Ultrasonic Wave Interaction with Disbonds and Weak Bonds

NASA Technical Reports Server (NTRS)

Leckey, C.; Hinders, M.

2011-01-01

Ultrasonic techniques, such as the use of guided waves, can be ideal for finding damage in the plate and pipe-like structures used in aerospace applications. However, the interaction of waves with real flaw types and geometries can lead to experimental signals that are difficult to interpret. 3-dimensional (3D) elastic wave simulations can be a powerful tool in understanding the complicated wave scattering involved in flaw detection and for optimizing experimental techniques. We have developed and implemented parallel 3D elastodynamic finite integration technique (3D EFIT) code to investigate Lamb wave scattering from realistic flaws. This paper discusses simulation results for an aluminum-aluminum diffusion disbond and an aluminum-epoxy disbond and compares results from the disbond case to the common artificial flaw type of a flat-bottom hole. The paper also discusses the potential for extending the 3D EFIT equations to incorporate physics-based weak bond models for simulating wave scattering from weak adhesive bonds.

Integrating Fiber Optic Strain Sensors into Metal Using Ultrasonic Additive Manufacturing

NASA Astrophysics Data System (ADS)

Hehr, Adam; Norfolk, Mark; Wenning, Justin; Sheridan, John; Leser, Paul; Leser, Patrick; Newman, John A.

2018-03-01

Ultrasonic additive manufacturing, a rather new three-dimensional (3D) printing technology, uses ultrasonic energy to produce metallurgical bonds between layers of metal foils near room temperature. This low temperature attribute of the process enables integration of temperature sensitive components, such as fiber optic strain sensors, directly into metal structures. This may be an enabling technology for Digital Twin applications, i.e., virtual model interaction and feedback with live load data. This study evaluates the consolidation quality, interface robustness, and load sensing limits of commercially available fiber optic strain sensors embedded into aluminum alloy 6061. Lastly, an outlook on the technology and its applications is described.

Rationalization of anisotropic mechanical properties of Al-6061 fabricated using ultrasonic additive manufacturing

DOE PAGES

Sridharan, Niyanth; Gussev, Maxim; Seibert, Rachel; ...

2016-09-01

Ultrasonic additive manufacturing (UAM) is a solid-state process, which uses ultrasonic vibrations at 20 kHz along with mechanized tape layering and intermittent milling operation, to build fully functional three-dimensional parts. In the literature, UAM builds made with low power (1.5 kW) exhibited poor tensile properties in Z-direction, i.e., normal to the interfaces. This reduction in properties is often attributed to the lack of bonding at faying interfaces. The generality of this conclusion is evaluated further in 6061 aluminum alloy builds made with very high power UAM (9 kW). Tensile deformation behavior along X and Z directions were evaluated with small-scalemore » in-situ mechanical testing equipped with high-resolution digital image correlation, as well as, multi-scale characterization of builds. Interestingly, even with complete metallurgical bonding across the interfaces without any discernable voids, poor Z-direction properties were observed. This reduction is correlated to coalescence of pre-existing shear bands at interfaces into micro voids, leading to strain localization and spontaneous failure on tensile loading.« less

Evaluation of bond strength of various epoxy resin based sealers in oval shaped root canals.

PubMed

Cakici, Fatih; Cakici, Elif Bahar; Ceyhanli, Kadir Tolga; Celik, Ersan; Kucukekenci, Funda Fundaoglu; Gunseren, Arif Onur

2016-09-30

The aim of this study was to evaluate the bond strength of AH plus, Acroseal, and Adseal to the root canal dentin. A total of 36 single-rooted, mandibular premolar teeth were used. Root canal shaping procedures were performed with ProTaper rotary instruments (Dentsply Maillefer) up to size F4. The prepared samples were then randomly assembled into 3 groups (n = 12). For each group, an ultrasonic tip (size 15, 0.02 taper) which was also coated with an epoxy resin based sealer and placed 2 mm shorter than the working length. The sealer was then activated for 10 s. A push-out test was used to measure the bond strength between the root canal dentine and the sealer. Kruskal-Wallis test to evaluate the push-out bond strength of epoxy based sealer (P = 0.05). The failure mode data were statistically analyzed using Pearson's chi square test (P = 0.05). Kruskal-Wallis test indicated that there were no statistically significant difference among the push out bond strength values of 3 mm (p = 0.123) and 6 mm (P = 0.057) for groups, there was statistically significant difference push out bond strength value of 9 mm (P = 0.032). Pearson's chi square test showed statistically significant differences for the failure types among the groups. Various epoxy resin based sealers activated ultrasonically showed similar bond strength in oval shaped root canals. Apical sections for all groups have higher push out bond strength values than middle and coronal sections.

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites

PubMed Central

Marrero, Raúl; Li, Xiaochun; Choi, Hongseok

2018-01-01

This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl2O3 nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl2O3 nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al–γAl2O3 nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires’ electrical conductivity compared with that of pure aluminum and aluminum–copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding. PMID:29534441

The fabrication of a double-layer atom chip with through silicon vias for an ultra-high-vacuum cell

NASA Astrophysics Data System (ADS)

Chuang, Ho-Chiao; Lin, Yun-Siang; Lin, Yu-Hsin; Huang, Chi-Sheng

2014-04-01

This study presents a double-layer atom chip that provides users with increased diversity in the design of the wire patterns and flexibility in the design of the magnetic field. It is more convenient for use in atomic physics experiments. A negative photoresist, SU-8, was used as the insulating layer between the upper and bottom copper wires. The electrical measurement results show that the upper and bottom wires with a width of 100 µm can sustain a 6 A current without burnout. Another focus of this study is the double-layer atom chips integrated with the through silicon via (TSV) technique, and anodically bonded to a Pyrex glass cell, which makes it a desired vacuum chamber for atomic physics experiments. Thus, the bonded glass cell not only significantly reduces the overall size of the ultra-high-vacuum (UHV) chamber but also conducts the high current from the backside to the front side of the atom chip via the TSV under UHV (9.5 × 10-10 Torr). The TSVs with a diameter of 70 µm were etched through by the inductively coupled plasma ion etching and filled by the bottom-up copper electroplating method. During the anodic bonding process, the electroplated copper wires and TSVs on atom chips also need to pass the examination of the required bonding temperature of 250 °C, under an applied voltage of 1000 V. Finally, the UHV test of the double-layer atom chips with TSVs at room temperature can be reached at 9.5 × 10-10 Torr, thus satisfying the requirements of atomic physics experiments under an UHV environment.

Ultrasonically bonded value assembly

NASA Technical Reports Server (NTRS)

Salvinski, R. J. (Inventor)

1975-01-01

A valve apparatus capable of maintaining a fluid-tight seal over a relatively long period of time by releasably bonding a valve member to its seat is described. The valve member is bonded or welded to the seat and then released by the application of the same energy to the bond joint. The valve member is held in place during the bonding by a clamping device. An appropriate force device can activate the opening and closing of the valve member. Various combinations of material for the valve member and valve seat can be utilized to provide an adequate sealing bond. Aluminum oxide, stainless steel, inconel, tungsten carbide as hard materials and copper, aluminum, titanium, silver, and gold as soft materials are suggested.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodenbeck, Christopher T; Girardi, Michael

Internal nodes of a constituent integrated circuit (IC) package of a multichip module (MCM) are protected from excessive charge during plasma cleaning of the MCM. The protected nodes are coupled to an internal common node of the IC package by respectively associated discharge paths. The common node is connected to a bond pad of the IC package. During MCM assembly, and before plasma cleaning, this bond pad receives a wire bond to a ground bond pad on the MCM substrate.

The Effect of Nano Loading and Ultrasonic Compounding of EVA/LDPE/Nano-magnesium Hydroxide on Mechanical Properties and Distribution of Nano Particles

NASA Astrophysics Data System (ADS)

Azman, I. A.; Salleh, R. M.; Alauddin, S. M.; Shueb, M. I.

2018-05-01

Blends of Ethylene Vinyl Acetate (EVA) and Low-Density Polyethylene (LDPE) are promising composite which have good mechanical properties to environmental stress cracking. However, they lack fire resistant properties, which limits it usage in wire and cable industry. In order to improve flame retardancy ability, a range of nano-magnesium hydroxide (nano-MH) loading which is from 0 phr to maximum of 20 phr with ultrasonic extrusion 0-100 kHz frequencies have been introduced. Ultrasonic extrusion was used to improve the distribution of nano-MH. It was found that, 10 phr of nano loading with 100 kHz ultrasonic assisted has greater tensile strength compared to the nanocomposite without ultrasonication. Further increase of nano MH loading, will decrease the tensile properties. Better elongation at break was observed at10 phr nano-MH with the frequency of 50 kHz. The sample of 20 phr of nanoMH assisted with 50 kHz ultrasonic exhibits good flexural properties while 10 phr of nano-MH without the ultrasonic assisted demonstrates good in izod impact properties. From the evaluation of mechanical properties studied, it was found that 10 phr of nano-MH has shown the best performance among all the samples tested for EVA/LDPE/nano-MH composites. Transmission Electron Microscopy (TEM) has been conducted on 10 phr sample with different frequencies in order to observe the distribution of nano-MH particles. The sample with 100 kHz frequency shows more uniform dispersion of nano-MH in EVA/LDPE composites. This investigation indicates that the ultrasonic technology can enhance the mechanical properties studied as well as the dispersion of nano particles in the composite.

Ultrasonic characterization of the fiber-matrix interfacial bond in aerospace composites.

PubMed

Aggelis, D G; Kleitsa, D; Matikas, T E

2013-01-01

The properties of advanced composites rely on the quality of the fiber-matrix bonding. Service-induced damage results in deterioration of bonding quality, seriously compromising the load-bearing capacity of the structure. While traditional methods to assess bonding are destructive, herein a nondestructive methodology based on shear wave reflection is numerically investigated. Reflection relies on the bonding quality and results in discernable changes in the received waveform. The key element is the "interphase" model material with varying stiffness. The study is an example of how computational methods enhance the understanding of delicate features concerning the nondestructive evaluation of materials used in advanced structures.

Fabricating capacitive micromachined ultrasonic transducers with a novel silicon-nitride-based wafer bonding process.

PubMed

Logan, Andrew; Yeow, John T W

2009-05-01

We report the fabrication and experimental testing of 1-D 23-element capacitive micromachined ultrasonic transducer (CMUT) arrays that have been fabricated using a novel wafer-bonding process whereby the membrane and the insulation layer are both silicon nitride. The membrane and cell cavities are deposited and patterned on separate wafers and fusion-bonded in a vacuum environment to create CMUT cells. A user-grown silicon-nitride membrane layer avoids the need for expensive silicon-on-insulator (SOI) wafers, reduces parasitic capacitance, and reduces dielectric charging. It allows more freedom in selecting the membrane thickness while also providing the benefits of wafer-bonding fabrication such as excellent fill factor, ease of vacuum sealing, and a simplified fabrication process when compared with the more standard sacrificial release process. The devices fabricated have a cell diameter of 22 microm, a membrane thickness of 400 nm, a gap depth of 150 nm, and an insulation thickness of 250 nm. The resonant frequency of the CMUT in air is 17 MHz and has an attenuation compensated center frequency of approximately 9 MHz in immersion with a -6 dB fractional bandwidth of 123%. This paper presents the fabrication process and some characterization results.

Health monitoring of prestressing tendons in post-tensioned concrete structures

NASA Astrophysics Data System (ADS)

Salamone, Salvatore; Bartoli, Ivan; Nucera, Claudio; Phillips, Robert; Lanza di Scalea, Francesco

2011-04-01

Currently 90% of bridges built in California are post-tensioned box-girder. In such structures the steel tendons are the main load-carrying components. The loss of prestress, as well as the presence of defects or the tendon breakage, can be catastrophic for the entire structure. Unfortunately, today there is no well-established method for the monitoring of prestressing (PS) tendons that can provide simultaneous information related to the presence of defects and the level of prestress in a continuous, real time manner. If such a monitoring system were available, considerable savings would be achieved in bridge maintenance since repairs would be implemented in a timely manner without traffic disruptions. This paper presents a health monitoring system for PS tendons in post-tensioned structures of interest to Caltrans. Such a system uses ultrasonic guided waves and embedded sensors to provide simultaneously and in real time, (a) measurements of the level of applied prestress, and (b) defect detection at early grow stages. The proposed PS measurement technique exploits the sensitivity of ultrasonic waves to the inter-wire contact developing in a multi-wire strand as a function of prestress level. In particular the nonlinear ultrasonic behavior of the tendon under changing levels of prestress is monitored by tracking higher-order harmonics at (nω) arising under a fundamental guided-wave excitation at (ω). Moreover this paper also present real-time damage detection and location in post-tensioned bridge joints using Acoustic Emission techniques. Experimental tests on large-scale single-tendon PT joint specimens, subjected to multiple load cycles, will be presented to validate the monitoring of PS loads (through nonlinear ultrasonic probing) and the monitoring of damage progression and location (through acoustic emission techniques). Issues and potential for the use of such techniques to monitor post-tensioned bridges in the field will be discussed.

Maxillary molar derotation and distalization by using a nickel-titanium wire fabricated on a setup model

PubMed Central

Jung, Jong Moon; Wi, Young Joo; Koo, Hyun Mo; Kim, Min Ji

2017-01-01

The purpose of this article is to introduce a simple appliance that uses a setup model and a nickel-titanium (Ni-Ti) wire for correcting the mesial rotation and drift of the permanent maxillary first molar. The technique involves bonding a Ni-Ti wire to the proper position of the target tooth on a setup model, followed by the fabrication of the transfer cap for indirect bonding and its transfer to the patient's teeth. This appliance causes less discomfort and provides better oral hygiene for the patients than do conventional appliances such as the bracket, pendulum, and distal jet. The treatment time is also shorter with the new appliance than with full-fixed appliances. Moreover, the applicability of the new appliance can be expanded to many cases by using screws or splinting with adjacent teeth to improve anchorage. PMID:28670568

Method for making an elastomeric member with end pieces

DOEpatents

Hoppie, L.O.; McNinch, J.H. Jr.; Nowell, G.C.

1984-10-23

A molding process is described for molding an elongated elastomeric member with wire mesh sleeves bonded to the ends. A molding preform of elastomeric material is positioned within a seamless mold cylinder, and the open ends of the wire mesh sleeves are mounted to end plug assemblies slidably received into the mold cylinder and positioned against the ends of the preform. A specialized profile is formed into surfaces of the respective end plug assemblies and by heating of the mold, the ends of the elastomeric preform are molded to the profile, as well as bonded to the reinforcing wire mesh sleeves. Vacuum is applied to the interior of the mold to draw outgassing vapors through relief spaces there through. The completed elastomeric member is removed from the mold cylinder by stretching, the consequent reduction in diameter enabling ready separation from the mold cylinder and removal thereof. 9 figs.

Maxillary molar derotation and distalization by using a nickel-titanium wire fabricated on a setup model.

PubMed

Jung, Jong Moon; Wi, Young Joo; Koo, Hyun Mo; Kim, Min Ji; Chun, Youn Sic

2017-07-01

The purpose of this article is to introduce a simple appliance that uses a setup model and a nickel-titanium (Ni-Ti) wire for correcting the mesial rotation and drift of the permanent maxillary first molar. The technique involves bonding a Ni-Ti wire to the proper position of the target tooth on a setup model, followed by the fabrication of the transfer cap for indirect bonding and its transfer to the patient's teeth. This appliance causes less discomfort and provides better oral hygiene for the patients than do conventional appliances such as the bracket, pendulum, and distal jet. The treatment time is also shorter with the new appliance than with full-fixed appliances. Moreover, the applicability of the new appliance can be expanded to many cases by using screws or splinting with adjacent teeth to improve anchorage.

Design and Demonstration of Automated Data Analysis Algorithms for Ultrasonic Inspection of Complex Composite Panels with Bonds

DTIC Science & Technology

2016-02-01

certification process. INTRODUCTION The ultrasonic inspection of aerospace composites has been demonstrated to be one of the most effective methods to...normal part conditions. Anomalous indications studied in this program include inserted materials, porosity, ply ‘laps and gaps’, and wrinkles . Inserted...partially scanned inserts at the radii. Wrinkles , laps and gaps have also been included in the truth table, but detection rates for these flaws are

The role of oxide structure on copper wire to the rubber adhesion

NASA Astrophysics Data System (ADS)

Su, Yea-Yang; Shemenski, Robert M.

2000-07-01

Most metals have an oxide layer on the surface. However, the structure of the oxide varies with the matrix composition, and depends upon the environmental conditions. A bronze coating, nominal composition of 98.5% Cu and balance of Sn, is applied to steel wire for reinforcing pneumatic tire beads and to provide adhesion to rubber. This work studied the influence of copper oxides on the bronze coating on adhesion during vulcanization. To emphasize the oxide structures, electrolytic tough pitch (ETP) copper wire was used instead of the traditional bronze-coated tire bead wire. Experimental results confirmed the hypothesis that cuprous oxide (Cu 2O) could significantly improve bonding between copper wire and rubber, and demonstrated that the interaction between rubber and oxide layer on wire is an electrochemical reaction.

Note: Piezoelectric polymers as transducers for the ultrasonic-reflection method and the application in mechanical property-screening of coatings

NASA Astrophysics Data System (ADS)

Wegener, Michael; Oehler, Harald; Lellinger, Dirk; Alig, Ingo

2012-01-01

In the last years, non-destructive ultrasonic testing methods are more and more frequently employed in order to investigate the drying and curing processes of different coatings. Among them an ultrasonic reflection method was developed allowing the simultaneous measurement with longitudinal and transversal waves. In order to generate the ultrasonic pulse, piezoelectric ceramics or oxides are usually used as transducer materials which are connected to a delay line. Here, we demonstrate a similar approach for the ultrasonic reflection method installing piezoelectric polymers as ultrasonic transducer materials. In detail, poly(vinylidene fluoride and trifluoroethylene) [P(VDF-TrFE)] copolymers were prepared as piezoelectric transducer layers directly onto the metallization of glass delay lines avoiding additional bonding processes. The film preparation was carried out by solvent casting the polymer onto an area with a diameter of 12 mm and is optimized so that relatively homogeneous polymer layers with thicknesses between 14 and 35 μm are adjusted by the deposited amount of the polymer. Electrical poling renders the polymer piezoelectric. The ultrasonic properties of the P(VDF-TrFE) transducer and their usability for the ultrasonic reflection method are described also in comparison to previous measurements using LiNbO3 transducer.

Investigation of Electrostatic Charge in Hose Lines

DTIC Science & Technology

2006-10-01

of the system. A INSULATORINSULATOR Ir1 Q Q dH vH A INSULATORINSULATOR Ir2 Q dm dl 2 vm LmLH S1 S2 S3EXTERNAL WIRE BRAID ON HOSE vl 2vm dm Lm dl...sizes of fuel hoses , including hoses with and without integrally bonded grounding wire braid ; (4) Different lengths of hose test sections; (5...Different earth grounding contact conditions along the hose test section, such as: (i) Complete insulation from the ground; (ii) Wire braid conductor along

KommonBase - A precise direct bonding system for labial fixed appliances.

PubMed

Miyashita, Wataru; Komori, Akira; Takemoto, Kyoto

2017-09-01

"KommonBase" is a system designed to customize the bracket base by means of an extended resin base covering the tooth. This system enables precise bracket placement and accurate fit on teeth. Moreover, KommonBase can be easily fabricated in a laboratory and bonded on each tooth using simple clinical procedures. Straight-wire treatment without wire bending was achieved in the clinical cases presented in this article using the KommonBase system for a labial fixed appliance. The application of KommonBase to the vestibular side enables efficient orthodontic treatment using simple mechanics. Copyright © 2017 CEO. Published by Elsevier Masson SAS. All rights reserved.

Integrated Inductors for RF Transmitters in CMOS/MEMS Smart Microsensor Systems

PubMed Central

Kim, Jong-Wan; Takao, Hidekuni; Sawada, Kazuaki; Ishida, Makoto

2007-01-01

This paper presents the integration of an inductor by complementary metal-oxide-semiconductor (CMOS) compatible processes for integrated smart microsensor systems that have been developed to monitor the motion and vital signs of humans in various environments. Integration of radio frequency transmitter (RF) technology with complementary metal-oxide-semiconductor/micro electro mechanical systems (CMOS/MEMS) microsensors is required to realize the wireless smart microsensors system. The essential RF components such as a voltage controlled RF-CMOS oscillator (VCO), spiral inductors for an LC resonator and an integrated antenna have been fabricated and evaluated experimentally. The fabricated RF transmitter and integrated antenna were packaged with subminiature series A (SMA) connectors, respectively. For the impedance (50 Ω) matching, a bonding wire type inductor was developed. In this paper, the design and fabrication of the bonding wire inductor for impedance matching is described. Integrated techniques for the RF transmitter by CMOS compatible processes have been successfully developed. After matching by inserting the bonding wire inductor between the on-chip integrated antenna and the VCO output, the measured emission power at distance of 5 m from RF transmitter was -37 dBm (0.2 μW).

Degradation behavior and products of malathion and chlorpyrifos spiked in apple juice by ultrasonic treatment.

PubMed

Zhang, Yuanyuan; Xiao, Zhiyong; Chen, Fang; Ge, Yiqiang; Wu, Jihong; Hu, Xiaosong

2010-01-01

Apple juice (13 degrees Brix) spiked with malathion and chlorpyrifos (2-3 mg l(-1) of each compound) was treated under different ultrasonic irradiations. Results showed that ultrasonic treatment was effective for the degradation of malathion and chlorpyrifos in apple juice, and the output power and treatment time significantly influenced the degradation of both pesticides (p<0.05). The maximum degradations were achieved for malathion (41.7%) and chlorpyrifos (82.0%) after the ultrasonic treatment at 500 W for 120 min. The degradation kinetics of both pesticides were fitted to the first-order kinetics model well (R(2)>or=0.90). The kinetics parameters indicated that chlorpyrifos was much more labile to ultrasonic treatment than malathion. Furthermore, malaoxon and chlorpyrifos oxon were identified as the degradation products of malathion and chlorpyrifos by gas chromatography-mass spectrometry (GC-MS), respectively. The oxidation pathway through the hydroxyl radical attack on the P=S bond of pesticide molecules was proposed.

Distributed temperature sensors development using an stepped-helical ultrasonic waveguide

NASA Astrophysics Data System (ADS)

Periyannan, Suresh; Rajagopal, Prabhu; Balasubramaniam, Krishnan

2018-04-01

This paper presents the design and development of the distributed ultrasonic waveguide temperature sensors using some stepped-helical structures. Distributed sensing has several applications in various industries (oil, glass, steel) for measurement of physical parameters such as level, temperature, viscosity, etc. This waveguide incorporates a special notch or bend for obtaining ultrasonic wave reflections from the desired locations (Gage-lengths) where local measurements are desired. In this paper, a multi-location measurement wave-guide, with a measurement capability of 18 locations in a single wire, has been fabricated. The distribution of these sensors is both in the axial as well as radial directions using a stepped-helical spring configuration. Also, different high temperature materials have been chosen for the wave-guide. Both lower order axi-symmetric guided ultrasonic modes (L(0,1) and T(0,1)) were employed. These wave modes were generated/received (pulse-echo approach) using conventional longitudinal and shear transducers, respectively. Also, both the wave modes were simultaneously generated/received and compared using shear transducer for developing the distributed helical wave-guide sensors. The effect of dispersion of the wave modes due to curvature effects will also be discussed.

Three-dimensional quantification of pretorqued nickel-titanium wires in edgewise and prescription brackets.

PubMed

Mittal, Nitika; Xia, Zeyang; Chen, Jie; Stewart, Kelton T; Liu, Sean Shih-Yao

2013-05-01

To quantify the three-dimensional moments and forces produced by pretorqued nickel-titanium (NiTi) rectangular archwires fully engaged in 0.018- and 0.022-inch slots of central incisor and molar edgewise and prescription brackets. Ten identical acrylic dental models with retroclined maxillary incisors were fabricated for bonding with various bracket-wire combinations. Edgewise, Roth, and MBT brackets with 0.018- and 0.022-inch slots were bonded in a simulated 2 × 4 clinical scenario. The left central incisor and molar were sectioned and attached to load cells. Correspondingly sized straight and pretorqued NiTi archwires were ligated to the brackets using 0.010-inch ligatures. Each load cell simultaneously measured three force (Fx, Fy, Fz) and three moment (Mx, My, Mz) components. The faciolingual, mesiodistal, and inciso-occluso/apical axes of the teeth corresponded to the x, y, and z axes of the load cells, respectively. Each wire was removed and retested seven times. Three-way analysis of variance (ANOVA) examined the effects of wire type, wire size, and bracket type on the measured orthodontic load systems. Interactions among the three effects were examined and pair-wise comparisons between significant combinations were performed. The force and moment components on each tooth were quantified according to their local coordinate axes. The three-way ANOVA interaction terms were significant for all force and moment measurements (P < .05), except for Fy (P > .05). The pretorqued wire generates a significantly larger incisor facial crown torquing moment in the MBT prescription compared to Roth, edgewise, and the straight NiTi wire.

Sagittal and vertical load-deflection and permanent deformation of transpalatal arches connected with palatal implants: an in-vitro study.

PubMed

Crismani, Adriano G; Celar, Ales G; Burstone, Charles J; Bernhart, Thomas G; Bantleon, Hans-Peter; Mittlboeck, Martina

2007-06-01

The purposes of this laboratory investigation were to (1) measure the sagittal and vertical deflection of loaded transpalatal arches (TPAs) connected to a palatal implant, (2) measure the extent of permanent deformation of the connecting TPA in the sagittal and vertical directions, (3) test various wire dimensions in terms of deflection behavior, and (4) evaluate soldering vs laser welding vs adhesive bonding of TPAs in terms of load deflection behavior. Stainless steel wires of 6 dimensions were tested: 0.8 x 0.8, 0.9, 1, 1.1, 1.2, and 1.2 x 1.2 mm. For each dimension, 10 specimens were soldered to the palatal implant abutment, 10 were laser welded, and 10 were adhesively bonded to the implant abutment (total, 180 specimens). The measuring device applied increments of force of 50 cN, from 0 to 500 cN. Then the specimens were unloaded. The values were statistically described and analyzed with ANOVA and Wilcoxon rank sum tests. Absolute orthodontic anchorage without deformation of TPAs was not observed with the wire dimensions tested. To prevent loss of anchorage greater than 370 mum (sagittal deflection of 1.2 x 1.2 mm adhesively bonded TPA at 500 cN force level), wires thicker than 1.2 x 1.2 mm or cast anchorage elements must be considered for clinical practice. However, larger cross sections might cause more patient discomfort, and laboratory procedures increase costs.

75 FR 82337 - Airworthiness Directives; The Boeing Company Model 777-200, -300, and -300ER Series Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-30

... hardware; and making certain wiring changes. This proposed AD was prompted by results from fuel system... a new P302 panel on the right side of the airplane, and changing the wiring; and performing certain bonding resistance measurements and reworking the airplane installation to verify that [[Page 82339...

Synthesis of one-dimensional metal-containing insulated molecular wire with versatile properties directed toward molecular electronics materials.

PubMed

Masai, Hiroshi; Terao, Jun; Seki, Shu; Nakashima, Shigeto; Kiguchi, Manabu; Okoshi, Kento; Fujihara, Tetsuaki; Tsuji, Yasushi

2014-02-05

We report, herein, the design, synthesis, and properties of new materials directed toward molecular electronics. A transition metal-containing insulated molecular wire was synthesized through the coordination polymerization of a Ru(II) porphyrin with an insulated bridging ligand of well-defined structure. The wire displayed not only high linearity and rigidity, but also high intramolecular charge mobility. Owing to the unique properties of the coordination bond, the interconversion between the monomer and polymer states was realized under a carbon monoxide atmosphere or UV irradiation. The results demonstrated a high potential of the metal-containing insulated molecular wire for applications in molecular electronics.

Ultrasonic, microwave, and millimeter wave inspection techniques for adhesively bonded stacked open honeycomb core composites

NASA Astrophysics Data System (ADS)

Thomson, Clint D.; Cox, Ian; Ghasr, Mohammad Tayeb Ahmed; Ying, Kuang P.; Zoughi, Reza

2015-03-01

Honeycomb sandwich composites are used extensively in the aerospace industry to provide stiffness and thickness to lightweight structures. A common fabrication method for thick, curved sandwich structures is to stack and bond multiple honeycomb layers prior to machining core curvatures. Once bonded, each adhesive layer must be inspected for delaminations and the presence of unwanted foreign materials. From a manufacturing and cost standpoint, it can be advantageous to inspect the open core prior to face sheet closeout in order to reduce end-article scrap rates. However, by nature, these honeycomb sandwich composite structures are primarily manufactured from low permittivity and low loss materials making detection of delamination and some of the foreign materials (which also are low permittivity and low loss) quite challenging in the microwave and millimeter wave regime. Likewise, foreign materials such as release film in adhesive layers can be sufficiently thin as to not cause significant attenuation in through-transmission ultrasonic signals, making them difficult to detect. This paper presents a collaborative effort intended to explore the efficacy of different non-contact NDI techniques for detecting flaws in a stacked open fiberglass honeycomb core panel. These techniques primarily included air-coupled through-transmission ultrasonics, single-sided wideband synthetic aperture microwave and millimeter-wave imaging, and lens-focused technique. The goal of this investigation has been to not only evaluate the efficacy of these techniques, but also to determine their unique advantages and limitations for evaluating parameters such as flaw type, flaw size, and flaw depth.

Full-field ultrasonic inspection for a composite sandwich plate skin-core debonding detection using laser-based ultrasonics

NASA Astrophysics Data System (ADS)

Chong, See Yenn; Victor, Jared J.; Todd, Michael D.

2017-04-01

In this paper, a full-field ultrasonic guided wave method is proposed to inspect a composite sandwich specimen made for an aircraft engine nacelle. The back skin/core interface of the specimen is built with two fabricated disbond defects (diameters of 12.7 mm and 25.4 mm) by removing areas of the adhesive used to bond the back skin to the core. A laser ultrasonic interrogation system (LUIS) incorporated with a disbond detection algorithm is developed. The system consists of a 1-kHz laser ultrasonic scanning system and a single fixed ultrasonic sensor to interrogate ultrasonic guided waves in the sandwich specimen. The interest area of 400 mm × 400 mm is scanned at a 0.5 mm scan interval. The corresponding full-field ultrasonic data is obtained and generated in the three-dimensional (3-D) space-time domain. Then, the 3-D full-field ultrasonic data is Fourier transformed and the ultrasonic frequency spectra are analyzed to determine the dominant frequency that is sensitive to the disbond defects. Continuous wavelet transform (CWT) based on fast Fourier transform (FFT) is implemented as a single-frequency bandpass filter to filter the full-field ultrasonic data in the 3-D space-time domain at the selected dominant frequency. The LUIS has shown the ability to detect the disbond with diameters of 11 mm and 23 mm which match to the pre-determined disbond sizes well. For future research, a robust signal processing algorithm and a model-based matched filter will be investigated to make the detection process autonomous and improve detectability

A study of tape adhesive strength on endotracheal tubes.

PubMed

Fenje, N; Steward, D J

1988-03-01

A method of assessing the adhesive bond of tapes used to secure endotracheal (ET) tubes is described. Five kinds of tape and six different ET tubes including two silicone rubber, wire-reinforced tubes were tested. There are significant differences in the adhesive strength of different tapes, and in the adhesive bond formed by different ET tube materials. On the Portex clear ET tube, silk tape adhered best (p less than 0.001), followed by waterproof, cloth, dermiclear, and micropore tapes. Adhesive bonding by silk tape was significantly greater (p less than 0.001) for the three clear ET tubes (Portex clear, NCC clear, and Portex ivory) than for the Portex blue and the silicone rubber, wire-reinforced ET tubes. All tapes showed very poor or negligible adhesion to the Sheridan and Portex reinforced ET tubes. Adhesion to these tubes was greatly improved by wrapping them tightly with an "op site" dressing prior to applying tape.

Development of Multiple-Frequency Ultrasonic Imaging System Using Multiple Resonance Piezoelectric Transducer

NASA Astrophysics Data System (ADS)

Akiyama, Iwaki; Yoshizumi, Natsuki; Saito, Shigemi; Wada, Yuji; Koyama, Daisuke; Nakamura, Kentaro

2012-07-01

The authors have developed a multiple frequency imaging system using a multiple resonance transducer (MRT) consisting of 1-3 composite materials with a low mechanical quality factor Q bonded together. The MRT has a structure consisting of thin and thick piezoelectric plates, two matching layers, and a backing layer. This makes it possible to obtain B-mode images of satisfactory resolution using ultrasonic pulses owing to their short duration. In this paper, the vibration property of the MRT derived through equivalent-circuit analysis is first shown. By utilizing the result, an MRT capable of transmitting ultrasonic pulses for generation of the images of biological tissues with satisfactory resolution is designed and prototyped. Setting the prototype transducer in the mechanical sector probe of commercial ultrasonic diagnosis equipment, the speckle reduction effect is demonstrated using images of various phantoms to mimic biological tissues and a human thyroid.

Ultrasonic and spectral studies on charge transfer complexes of anisole and certain aromatic amines

NASA Astrophysics Data System (ADS)

Rajesh, R.; Raj Muhamed, R.; Justin Adaikala Baskar, A.; Kannappan, V.

2016-10-01

Stability constants of two complexes of anisole with aniline and N-methylaniline (NMA) are determined from the measured ultrasonic velocity in n-hexane medium at four different temperatures. Acoustic and excess thermo acoustic parameters [excess ultrasonic velocity (uE), excess molar volume (VE), excess internal pressure (πiE)] are reported for these systems at four different temperatures. The trend in acoustic and excess parameters with concentration in the two systems establishes the formation of hydrogen bonded complexes between anisole and the two amines. Thermodynamic properties are computed for the two complexes from the variation in K with temperature. The formation of these complexes is also established by UV spectral method and their spectral characteristics and stability constants are determined. K values of these complexes obtained by ultrasonic and UV spectroscopic techniques agree well. Aniline forms more stable complex than N-methylaniline with anisole in n-hexane medium.

Synthesis of phosphonic acid silver-graphene oxide nanomaterials with photocatalytic activity through ultrasonic-assisted method.

PubMed

Li, Yongshen; Song, Yunna; Ma, Zheng; Niu, Shuai; Li, Jihui; Li, Ning

2018-06-01

In this article, phosphonic acid silver-graphene oxide nanomaterials (Nano-PAS-GO) was synthesized from silver nitrate (AgNO 3 ) solution and phosphoric graphene oxide (PGO) via the convenient ultrasonic-assisted method, and the structure and morphology were characterized, and the photocatalytic activity and recyclability were evaluated through photocatalyzing degradation of Rhodamin B (RhB) aqueous solution, and the possible photocatalytic mechanism was also discussed. Based on those, it was confirmed that Nano-PAS-GO has been synthesized from AgNO 3 solution and PGO colloidal suspension under ultrasonic-assisted condition, and Nano-PAS-GO has consisted of phosphoric acid silver nanoparticles and GO with 2D lattice (2D GO lattice) connected in the form of C-P bonds, and the photodegradation rate of Nano-PAS-GO for RhB aqueous solution has reached 93.99%, and Nano-PAS-GO has possessed the nicer recyclability when the photocatalytic time was 50 min. From those results, the strong and stable interface . between PAS nanoparticles and 2D GO lattice connected in the form of the covalent bonds has effectively inhibited the occurrence of the photocorrosion phenomenon. Copyright © 2018 Elsevier B.V. All rights reserved.

A New High-Temperature Ultrasonic Transducer for Continuous Inspection.

PubMed

Amini, Mohammad Hossein; Sinclair, Anthony N; Coyle, Thomas W

2016-03-01

A novel design of piezoelectric ultrasonic transducer is introduced, suitable for operation at temperatures of up to 700 °C-800 °C. Lithium niobate single crystal is chosen as the piezoelectric element primarily due to the high Curie temperature of 1200 °C. A backing element based on a porous ceramic is designed for which the pore volume fraction and average pore diameter in the ceramic matrix can be controlled in the manufacturing process; this enables the acoustic impedance and attenuation to be selected to match their optimal values as predicted by a one-dimensional transducer model of the entire transducer. Porous zirconia is selected as the ceramic matrix material of the backing element to obtain an ultrasonic signal with center frequency of 2.7-3 MHz, and 3-dB bandwidth of 90%-95% at the targeted operating temperature. Acoustic coupling of the piezocrystal to the backing element and matching layer is investigated using commercially available high-temperature adhesives and brazing alloys. The performance of the transducer as a function of temperature is studied. Stable bonding and clear signals were obtained using an aluminum brazing alloy as the bonding agent.

Durability Evaluation of a Thin Film Sensor System With Enhanced Lead Wire Attachments on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Kiser, J. Douglas; Singh, Mrityunjay; Cuy, Mike; Blaha, Charles A.; Androjna, Drago

2000-01-01

An advanced thin film sensor system instrumented on silicon carbide (SiC) fiber reinforced SiC matrix ceramic matrix composites (SiC/SiC CMCs), was evaluated in a Mach 0.3 burner rig in order to determine its durability to monitor material/component surface temperature in harsh environments. The sensor system included thermocouples in a thin film form (5 microns thick), fine lead wires (75 microns diameter), and the bonds between these wires and the thin films. Other critical components of the overall system were the heavy, swaged lead wire cable (500 microns diameter) that contained the fine lead wires and was connected to the temperature readout, and ceramic attachments which were bonded onto the CMCs for the purpose of securing the lead wire cables, The newly developed ceramic attachment features a combination of hoops made of monolithic SiC or SiC/SiC CMC (which are joined to the test article) and high temperature ceramic cement. Two instrumented CMC panels were tested in a burner rig for a total of 40 cycles to 1150 C (2100 F). A cycle consisted of rapid heating to 1150 C (2100 F), a 5 minute hold at 1150 C (2100 F), and then cooling down to room temperature in 2 minutes. The thin film sensor systems provided repeatable temperature measurements for a maximum of 25 thermal cycles. Two of the monolithic SiC hoops debonded during the sensor fabrication process and two of the SiC/SiC CMC hoops failed during testing. The hoops filled with ceramic cement, however, showed no sign of detachment after 40 thermal cycle test. The primary failure mechanism of this sensor system was the loss of the fine lead wire-to-thin film connection, which either due to detachment of the fine lead wires from the thin film thermocouples or breakage of the fine wire.

TAB interconnects for space concentrator solar cell arrays

NASA Technical Reports Server (NTRS)

Avery, J.; Bauman, J. S.; Gallagher, P.; Yerkes, J. W.

1993-01-01

The Boeing Company has evaluated the use of Tape Automated Bonding (TAB) and Surface Mount Technology (SMT) for a highly reliable, low cost interconnect for concentrator solar cell arrays. TAB and SMT are currently used in the electronics industry for chip interconnects and printed circuit board assembly. TAB tape consists of sixty-four 3-mil/1-oz tin-plated copper leads on 8-mil centers. The leads are thermocompression gang bonded to GaAs concentrator solar cell with silver contacts. This bond, known as an Inner Lead Bond (ILB), allows for pretesting and sorting capability via nondestruct wire bond pull and flash testing. Destructive wire pull tests resulted in preferred mid-span failures. Improvements in fill factor were attributed to decreased contact resistance on TAB bonded cells. Preliminary thermal cycling and aging tests were shown excellent bond strength and metallurgical results. Auger scans of bond sites reveals an Ag-Cu-Tin composition. Improper bonds are identified through flash testing as a performance degradation. On going testing of cells are underway at Lewis Research Center. SMT techniques are utilized to excise and form TAB leads post ILB. The formed leads' shape isolates thermal mismatches between the cells and the flex circuit they are mounted on. TABed cells are picked and placed with a gantry x-y-z positioning system with pattern recognition. Adhesives are selected to avoid thermal expansion mismatch and promote thermal transfer to the flex circuit. TAB outer lead bonds are parallel gap welded (PGW) to the flex circuit to finish the concentrator solar cell subassembly.

Fabrication of thin layer beta alumina

NASA Technical Reports Server (NTRS)

Tennenhouse, G. J.

1977-01-01

Beta alumina tubes having walls 700 microns, 300 microns, and 140 microns were processed by extrusion and sintering utilizing Ford proprietary binder and fabrication systems. Tubes prepared by this method have properties similar to tubes prepared by isostatic pressing and sintering, i.e. density greater than 98% of theoretical and a helium leak rate less than 3 x 10 to the -9th power cc/sq cm/sec. Ford ultrasonic bonding techniques were used for bonding beta alumina end caps to open ended beta -alumina tubes prior to sintering. After sintering, the bond was hermetic, and the integrity of the bonded area was comparable to the body of the tube.

Dental Hygiene and Orthodontics: Effect of Ultrasonic Instrumentation on Bonding Efficacy of Different Lingual Orthodontic Brackets.

PubMed

Scribante, Andrea; Sfondrini, Maria Francesca; Collesano, Vittorio; Tovt, Gaia; Bernardinelli, Luisa; Gandini, Paola

2017-01-01

Dental hygienists are often faced with patients wearing lingual orthodontic therapy, as ultrasonic instrumentation (UI) is crucial for oral health. As the application of external forces can lead to premature bonding failure, the aim of this study was to evaluate the effect of UI on shear bond strength (SBS) and on adhesive remnant index (ARI) of different lingual orthodontic brackets. 200 bovine incisors were divided into 10 groups. Four different lingual (STB, Ormco; TTR, Rocky Mountain Orthodontics; Idea, Leone; 2D, Forestadent) and vestibular control (Victory, 3M) brackets were bonded. UI was performed in half of specimens, whereas the other half did not receive any treatment. All groups were tested with a universal testing machine. SBS and ARI values were recorded. Statistical analysis was performed (significance: P = 0.05). TTR, Idea, and 2D lingual brackets significantly lowered SBS after UI, whereas for other braces no effect was recorded. Appliances with lower mesh area significantly reduced their adhesion capacity after UI. Moreover groups subjected to UI showed higher ARI scores than controls. UI lowered SBS of lingual appliances of small dimensions so particular care should be posed avoiding prolonged instrumentation around bracket base during plaque removal. Moreover, UI influenced also ARI scores.

Dental Hygiene and Orthodontics: Effect of Ultrasonic Instrumentation on Bonding Efficacy of Different Lingual Orthodontic Brackets

PubMed Central

Collesano, Vittorio; Tovt, Gaia; Bernardinelli, Luisa; Gandini, Paola

2017-01-01

Dental hygienists are often faced with patients wearing lingual orthodontic therapy, as ultrasonic instrumentation (UI) is crucial for oral health. As the application of external forces can lead to premature bonding failure, the aim of this study was to evaluate the effect of UI on shear bond strength (SBS) and on adhesive remnant index (ARI) of different lingual orthodontic brackets. 200 bovine incisors were divided into 10 groups. Four different lingual (STB, Ormco; TTR, Rocky Mountain Orthodontics; Idea, Leone; 2D, Forestadent) and vestibular control (Victory, 3M) brackets were bonded. UI was performed in half of specimens, whereas the other half did not receive any treatment. All groups were tested with a universal testing machine. SBS and ARI values were recorded. Statistical analysis was performed (significance: P = 0.05). TTR, Idea, and 2D lingual brackets significantly lowered SBS after UI, whereas for other braces no effect was recorded. Appliances with lower mesh area significantly reduced their adhesion capacity after UI. Moreover groups subjected to UI showed higher ARI scores than controls. UI lowered SBS of lingual appliances of small dimensions so particular care should be posed avoiding prolonged instrumentation around bracket base during plaque removal. Moreover, UI influenced also ARI scores. PMID:28904955

Additive Manufacturing of Thermoplastic Matrix Composites Using Ultrasonics

NASA Astrophysics Data System (ADS)

Olson, Meghan

Advanced composite materials have great potential for facilitating energy efficient product design and their manufacture if improvements are made to current composite manufacturing processes. This thesis focuses on the development of a novel manufacturing process for thermoplastic composite structures entitled Laser-Ultrasonic Additive Manufacturing ('LUAM'), which is intended to combine the benefits of laser processing technology, developed by Automated Dynamics Inc., with ultrasonic bonding technology that is used commercially for unreinforced polymers. These technologies used together have the potential to significantly reduce the energy consumption and void content of thermoplastic composites made using Automated Fiber Placement (AFP). To develop LUAM in a methodical manner with minimal risk, a staged approach was devised whereby coupon-level mechanical testing and prototyping utilizing existing equipment was accomplished. Four key tasks have been identified for this effort: Benchmarking, Ultrasonic Compaction, Laser Assisted Ultrasonic Compaction, and Demonstration and Characterization of LUAM. This thesis specifically addresses Tasks 1 and 2, i.e. Benchmarking and Ultrasonic Compaction, respectively. Task 1, fabricating test specimens using two traditional processes (autoclave and thermal press) and testing structural performance and dimensional accuracy, provide results of a benchmarking study by which the performance of all future phases will be gauged. Task 2, fabricating test specimens using a non-traditional process (ultrasonic conpaction) and evaluating in a similar fashion, explores the the role of ultrasonic processing parameters using three different thermoplastic composite materials. Further development of LUAM, although beyond the scope of this thesis, will combine laser and ultrasonic technology and eventually demonstrate a working system.

Molecular mechanism of H+ conduction in the single-file water chain of the gramicidin channel.

PubMed

Pomès, Régis; Roux, Benoît

2002-05-01

The conduction of protons in the hydrogen-bonded chain of water molecules (or "proton wire") embedded in the lumen of gramicidin A is studied with molecular dynamics free energy simulations. The process may be described as a "hop-and-turn" or Grotthuss mechanism involving the chemical exchange (hop) of hydrogen nuclei between hydrogen-bonded water molecules arranged in single file in the lumen of the pore, and the subsequent reorganization (turn) of the hydrogen-bonded network. Accordingly, the conduction cycle is modeled by two complementary steps corresponding respectively to the translocation 1) of an ionic defect (H+) and 2) of a bonding defect along the hydrogen-bonded chain of water molecules in the pore interior. The molecular mechanism and the potential of mean force are analyzed for each of these two translocation steps. It is found that the mobility of protons in gramicidin A is essentially determined by the fine structure and the dynamic fluctuations of the hydrogen-bonded network. The translocation of H+ is mediated by spontaneous (thermal) fluctuations in the relative positions of oxygen atoms in the wire. In this diffusive mechanism, a shallow free-energy well slightly favors the presence of the excess proton near the middle of the channel. In the absence of H+, the water chain adopts either one of two polarized configurations, each of which corresponds to an oriented donor-acceptor hydrogen-bond pattern along the channel axis. Interconversion between these two conformations is an activated process that occurs through the sequential and directional reorientation of water molecules of the wire. The effect of hydrogen-bonding interactions between channel and water on proton translocation is analyzed from a comparison to the results obtained previously in a study of model nonpolar channels, in which such interactions were missing. Hydrogen-bond donation from water to the backbone carbonyl oxygen atoms lining the pore interior has a dual effect: it provides a coordination of water molecules well suited both to proton hydration and to high proton mobility, and it facilitates the slower reorientation or turn step of the Grotthuss mechanism by stabilizing intermediate configurations of the hydrogen-bonded network in which water molecules are in the process of flipping between their two preferred, polarized states. This mechanism offers a detailed molecular model for the rapid transport of protons in channels, in energy-transducing membrane proteins, and in enzymes.

Worms Expelled With the Urine From a Bosniak Cyst III of the Left Kidney.

PubMed

Yang, Jie; Li, Pu; Su, Chuan; Zhang, Jia-Yi; Gu, Min

2016-07-01

An old fishman presented with left lumbago and finding worms in his urine. Type-B ultrasonic inspection and computed tomography scan found a Bosniak cyst III, containing several wire-like elements, in the middle of the left kidney. Expelled worms were confirmed to be Dioctophyma renale. After two courses of albendazole, the man was cured. Copyright © 2016 Elsevier Inc. All rights reserved.

Thermophysical Properties of Matter - The TPRC Data Series. Volume 3. Thermal Conductivity - Nonmetallic Liquids and Gases

DTIC Science & Technology

1970-01-01

design and experimentation. I. The Shock- Tube Method Smiley [546] introduced the use of shock waves...one of the greatest disadvantages of this technique. Both the unique adaptability of the shock tube method for high -temperature measurement of...Line-Source Flow Method H. The Hot-Wire Thermal Diffusion Column Method I. The Shock- Tube Method J. The Arc Method K. The Ultrasonic Method .

Ultrasonic Vocalizations by Adult Rats (Rattus norvegicus)

DTIC Science & Technology

1991-12-01

1. In addition, female lordosis intensity and female agonistic behavior (turning away, kicking, boxing attack) were scored. Results indicated that pre...ejaculatory 22 kHz calls were associated with lower lordosis intensity and higher levels of aggression by the female. The results indicate that 22...in the receiving cage which was wired to serve as a speaker. Sexual behavior (darting and lordosis ) of the receiving female was observed for a 10-min

Amplifier Module for 260-GHz Band Using Quartz Waveguide Transitions

NASA Technical Reports Server (NTRS)

Padmanabhan, Sharmila; Fung, King Man; Kangaslahti, Pekka P.; Peralta, Alejandro; Soria, Mary M.; Pukala, David M.; Sin, Seth; Samoska, Lorene A.; Sarkozy, Stephen; Lai, Richard

2012-01-01

Packaging of MMIC LNA (monolithic microwave integrated circuit low-noise amplifier) chips at frequencies over 200 GHz has always been problematic due to the high loss in the transition between the MMIC chip and the waveguide medium in which the chip will typically be used. In addition, above 200 GHz, wire-bond inductance between the LNA and the waveguide can severely limit the RF matching and bandwidth of the final waveguide amplifier module. This work resulted in the development of a low-loss quartz waveguide transition that includes a capacitive transmission line between the MMIC and the waveguide probe element. This capacitive transmission line tunes out the wirebond inductance (where the wire-bond is required to bond between the MMIC and the probe element). This inductance can severely limit the RF matching and bandwidth of the final waveguide amplifier module. The amplifier module consists of a quartz E-plane waveguide probe transition, a short capacitive tuning element, a short wire-bond to the MMIC, and the MMIC LNA. The output structure is similar, with a short wire-bond at the output of the MMIC, a quartz E-plane waveguide probe transition, and the output waveguide. The quartz probe element is made of 3-mil quartz, which is the thinnest commercially available material. The waveguide band used is WR4, from 170 to 260 GHz. This new transition and block design is an improvement over prior art because it provides for better RF matching, and will likely yield lower loss and better noise figure. The development of high-performance, low-noise amplifiers in the 180-to- 700-GHz range has applications for future earth science and planetary instruments with low power and volume, and astrophysics array instruments for molecular spectroscopy. This frequency band, while suitable for homeland security and commercial applications (such as millimeter-wave imaging, hidden weapons detection, crowd scanning, airport security, and communications), also has applications to future NASA missions. The Global Atmospheric Composition Mission (GACM) in the NRC Decadel Survey will need low-noise amplifiers with extremely low noise temperatures, either at room temperature or for cryogenic applications, for atmospheric remote sensing.

Permanent wire splicing by an explosive joining process

NASA Technical Reports Server (NTRS)

Bement, Laurence J. (Inventor); Kushnick, Anne C. (Inventor)

1991-01-01

The invention is an apparatus and method for wire splicing using an explosive joining process. The apparatus consists of a prebent, U-shaped strap of metal that slides over prepositioned wires. A standoff means separates the wires from the strap before joining. An adhesive means holds two ribbon explosives in position centered over the U-shaped strap. A detonating means connects to the ribbon explosives. The process involves spreading strands of each wire to be joined into a flat plane. The process then requires alternating each strand in alignment to form a mesh-like arrangement with an overlapped area. The strap slides over the strands of the wires, and the standoff means is positioned between the two surfaces. The detonating means then initiates the ribbon explosives that drive the strap to accomplish a high velocity, angular collision between the mating surfaces. This collision creates surface melts and collision bonding results in electron sharing linkups.

Infrared spectral marker bands characterizing a transient water wire inside a hydrophobic membrane protein.

PubMed

Wolf, Steffen; Freier, Erik; Cui, Qiang; Gerwert, Klaus

2014-12-14

Proton conduction along protein-bound "water wires" is an essential feature in membrane proteins. Here, we analyze in detail a transient water wire, which conducts protons via a hydrophobic barrier within a membrane protein to create a proton gradient. It is formed only for a millisecond out of three water molecules distributed at inactive positions in a polar environment in the ground state. The movement into a hydrophobic environment causes characteristic shifts of the water bands reflecting their different chemical properties. These band shifts are identified by time-resolved Fourier Transform Infrared difference spectroscopy and analyzed by biomolecular Quantum Mechanical/Molecular Mechanical simulations. A non-hydrogen bonded ("dangling") O-H stretching vibration band and a broad continuum absorbance caused by a combined vibration along the water wire are identified as characteristic marker bands of such water wires in a hydrophobic environment. The results provide a basic understanding of water wires in hydrophobic environments.

Method for making an elastomeric member with end pieces

DOEpatents

Hoppie, Lyle O.; McNinch, Jr., Joseph H.; Nowell, Gregory C.

1984-01-01

A molding process for molding an elongated elastomeric member (60) with wire mesh sleeves (16) bonded to the ends (14). A molding preform (10) of elastomeric material is positioned within a seamless mold cylinder (26), and the open ends of the wire mesh sleeves (16) are mounted to end plug assemblies (30) slidably received into the mold cylinder (26) and positioned against the ends (14) of the preform (10). A specialized profile is formed into surfaces (44) of the respective end plug assemblies (30) and by heating of the mold (26), the ends (14) of the elastomeric preform (10) are molded to the profile, as well as bonded to the reinforcing wire mesh sleeves (16). Vacuum is applied to the interior of the mold to draw outgassing vapors through relief spaces therethrough. The completed elastomeric member (60) is removed from the mold cylinder (26) by stretching, the consequent reduction in diameter enabling ready separation from the mold cylinder (26) and removal thereof.

Microstructures and mechanical properties of bonding layers between low carbon steel and alloy 625 processed by gas tungsten arc welding

NASA Astrophysics Data System (ADS)

Lou, Shuai; Lee, Seul Bi; Nam, Dae-Geun; Choi, Yoon Suk

2017-11-01

A filler metal wire, Alloy 625, was cladded on a plate of a low carbon streel, SS400, by gas tungsten arc welding, and the morphology of the weld bead and resulting dilution ratio were investigated under different welding parameter values (the input current, weld speed and wire feed speed). The wire feed speed was found to be most influential in controlling the dilution ratio of the weld bead, and seemed to limit the influence of other welding parameters. Two extreme welding conditions (with the minimum and maximum dilution ratios) were identified, and the corresponding microstructures, hardness and tensile properties near the bond line were compared between the two cases. The weld bead with the minimum dilution ratio showed superior hardness and tensile properties, while the formation lath martensite (due to relatively fast cooling) affected mechanical properties in the heat affected zone of the base metal with the maximum dilution ratio.

Silicon dendritic web material

NASA Technical Reports Server (NTRS)

Meier, D. L.; Campbell, R. B.; Sienkiewicz, L. J.; Rai-Choudhury, P.

1982-01-01

The development of a low cost and reliable contact system for solar cells and the fabrication of several solar cell modules using ultrasonic bonding for the interconnection of cells and ethylene vinyl acetate as the potting material for module encapsulation are examined. The cells in the modules were made from dendritic web silicon. To reduce cost, the electroplated layer of silver was replaced with an electroplated layer of copper. The modules that were fabricated used the evaporated Ti, Pd, Ag and electroplated Cu (TiPdAg/Cu) system. Adherence of Ni to Si is improved if a nickel silicide can be formed by heat treatment. The effectiveness of Ni as a diffusion barrier to Cu and the ease with which nickel silicide is formed is discussed. The fabrication of three modules using dendritic web silicon and employing ultrasonic bonding for interconnecting calls and ethylene vinyl acetate as the potting material is examined.

Silicon dendritic web material

NASA Astrophysics Data System (ADS)

Meier, D. L.; Campbell, R. B.; Sienkiewicz, L. J.; Rai-Choudhury, P.

1982-03-01

The development of a low cost and reliable contact system for solar cells and the fabrication of several solar cell modules using ultrasonic bonding for the interconnection of cells and ethylene vinyl acetate as the potting material for module encapsulation are examined. The cells in the modules were made from dendritic web silicon. To reduce cost, the electroplated layer of silver was replaced with an electroplated layer of copper. The modules that were fabricated used the evaporated Ti, Pd, Ag and electroplated Cu (TiPdAg/Cu) system. Adherence of Ni to Si is improved if a nickel silicide can be formed by heat treatment. The effectiveness of Ni as a diffusion barrier to Cu and the ease with which nickel silicide is formed is discussed. The fabrication of three modules using dendritic web silicon and employing ultrasonic bonding for interconnecting calls and ethylene vinyl acetate as the potting material is examined.

Design of highly uniform spool and bar horns for ultrasonic bonding.

PubMed

Kim, Sun-Rak; Lee, Jae Hak; Yoo, Choong D; Song, Jun-Yeob; Lee, Seung S

2011-10-01

Although the groove and slot have been widely utilized for horn design to achieve high uniformity, their effects on uniformity have not been analyzed thoroughly. In this work, spool and bar horns for ultrasonic bonding are designed in a systematic way using the design of experiments (DOE) to achieve high amplitude uniformity of the horn. Three-dimensional modal analysis is conducted to predict the natural frequency, amplitude, and stress of the horns, and the DOE is employed to analyze the effects of the groove and slot on the amplitude uniformity. The design equations are formulated to determine the optimum dimensions of the groove and slot, and the uniformity is found to be influenced most significantly by the groove depth and slot width. Displacements of the spool and bar horns were measured using a laser Doppler vibrometer (LDV), and the predicted results are in good agreement with the experimental data.

The Image Understanding Architecture Project

DTIC Science & Technology

1988-04-01

The error resulted in the frame being reduced in size and incorrectly bonded . The problem has been corrected and3 the design has been re-submitted...Promotional literature, Beaverton, OR, 1985. Nii, 1986] Nil, H.P., The Blackboard Model of Problem Solving and the Evolution of Blackboard...microns. This resulted in a reduction in pad sizes to two thirds of the minimum required for safe bonding . All chips had many wire bonds on the die

Nondestructive tests of regenerative chambers. [evaluating nondestructive methods of determining metal bond integrity

NASA Technical Reports Server (NTRS)

Malone, G. A.; Vecchies, L.; Wood, R.

1974-01-01

The capabilities and limitations of nondestructive evaluation methods were studied to detect and locate bond deficiencies in regeneratively cooled thrust chambers for rocket engines. Flat test panels and a cylinder were produced to simulate regeneratively cooled thrust chamber walls. Planned defects with various bond integrities were produced in the panels to evaluate the sensitivity, accuracy, and limitations of nondestructive methods to define and locate bond anomalies. Holography, acoustic emission, and ultrasonic scan were found to yield sufficient data to discern bond quality when used in combination and in selected sequences. Bonding techniques included electroforming and brazing. Materials of construction included electroformed nickel bonded to Nickel 200 and OFHC copper, electroformed copper bonded to OFHC copper, and 300 series stainless steel brazed to OFHC copper. Variations in outer wall strength, wall thickness, and defect size were evaluated for nondestructive test response.

New Approaches to the Synthesis of Novel Organosilanes.

DTIC Science & Technology

1983-10-01

through" electrode composed of RVC ( reticulated vitreous carbon ), a highly conductive sponge of carbonized material. Both of these flow systems...effective in promoting silicon- carbon bond cleavage and reformation to give cyclic and cage compounds readily and in good yields: (tA*3-9)(CŖ). n 2-S...silicon to carbon bonds and has broad based applications in research and industrial labs. The increase in reaction rate and yield with ultrasonic waves

An investigation into the use of surface waves for the real-time inspection of polymer composites during fabrication

NASA Astrophysics Data System (ADS)

Linstrom, Elizabeth Jane

A new approach to the nondestructive evaluation of polymer matrix/graphite fiber composites is presented. This technique permits the determination of the top ply bond strength of a laminate based on the results of ultrasonic testing. This technique is designed to be used for the real-time, nondestructive evaluation of composites during tape laying. By separately bonding the top ply of thermoset and thermoplastic polymer composite laminates, a poor ply bond was achieved solely at the interface of the top ply and the rest of the laminate. Using angled incidence, a 5 MHz, 4 musecond ultrasonic pulse was induced into the composite samples. This created waves traveling along the surface of the composite samples that were picked up by a receiving transducer. The received signal was cross-correlated with an artificially constructed replica of the input signal. The maximum amplitude of the cross-correlated signal was recorded. The cross-correlated signal was then converted to the frequency spectra using a fast Fourier transform. The maximum amplitude of the frequency spectra was then recorded. These measurements were repeated at 18 to 30 different locations on each composite sample. The resulting collection of maximum amplitudes of cross-correlated signals and frequency spectra were fit to two parameter Weibull distributions. The composite samples were destructively evaluated using a flat-wise tensile test. The B-basis values of the ultrasonic data Weibull distributions were compared to the B-basis values of the Weibull distribution of the strength data. A good correlation was found.

Improved Sensing Coils for SQUIDs

NASA Technical Reports Server (NTRS)

Penanen, Konstantin; Hahn, Inseob; Eom, Byeong Ho

2007-01-01

An improvement in the design and fabrication of sensing coils of superconducting quantum interference device (SQUID) magnetometers has been proposed to increase sensitivity. It has been estimated that, in some cases, it would be possible to increase sensitivity by about half or to reduce measurement time correspondingly. The pertinent aspects of the problems of design and fabrication can be summarized as follows: In general, to increase the sensitivity of a SQUID magnetometer, it is necessary to maximize the magnetic flux enclosed by the sensing coil while minimizing the self-inductance of this coil. It is often beneficial to fabricate the coil from a thicker wire to reduce its self-inductance. Moreover, to optimize the design of the coil with respect to sensitivity, it may be necessary to shape the wire to other than a commonly available circular or square cross-section. On the other hand, it is not practical to use thicker superconducting wire for the entire superconducting circuit, especially if the design of a specific device requires a persistent-current loop enclosing a remotely placed SQUID sensor. It may be possible to bond a thicker sensing-coil wire to thinner superconducting wires leading to a SQUID sensor, but it could be difficult to ensure reliable superconducting connections, especially if the bonded wires are made of different materials. The main idea is to mold the sensing coil in place, to more nearly optimum cross sectional shape, instead of making the coil by winding standard pre-fabricated wire. For this purpose, a thin superconducting wire loop that is an essential part of the SQUID magnetometer would be encapsulated in a form that would serve as a mold. A low-melting-temperature superconducting metal (e.g., indium, tin, or a lead/tin alloy) would be melted into the form, which would be sized and shaped to impart the required cross section to the coil thus formed.

Contamination control in hybrid microelectronic modules. Part 2: Selection and evaluation of coating materials

NASA Technical Reports Server (NTRS)

Himmel, R. P.

1975-01-01

The selection, test, and evaluation of organic coating materials for contamination control in hybrid circuits is reported. The coatings were evaluated to determine their suitability for use as a conformal coating over the hybrid microcircuit (including chips and wire bonds) inside a hermetically sealed package. Evaluations included ease of coating application and repair and effect on thin film and thick film resistors, beam leads, wire bonds, transistor chips, and capacitor chips. The coatings were also tested for such properties as insulation resistance, voltage breakdown strength, and capability of immobilizing loose particles inside the packages. The selected coatings were found to be electrically, mechanically, and chemically compatible with all components and materials normally used in hybrid microcircuits.

Surface induced phonon decay rates in thin film nano-structures

NASA Astrophysics Data System (ADS)

Photiadis, D. M.

2007-12-01

Nano-scale structure significantly impacts phonon transport and related phonon relaxation rates, with order of magnitude effects on the thermal conductivity of dielectric thin films and quantum wires, and even larger effects on the lifetimes of ultrasonic phonons of micro- (nano-) oscillators. In both cases, efforts to explain the data have been hampered by our lack of knowledge of the effects of confined dimensionality on phonon-phonon scattering rates. Using a phonon Boltzmann equation with appropriate boundary conditions on the free surfaces to take surface roughness into account, we have obtained an expression yielding phonon lifetimes in 2-D dielectric nanostructures(thin films) resulting from phonon-phonon scattering in conjunction with phonon-surface scattering. We present these theoretical results and, in the limit in which surface induced losses dominate, obtain explicit predictions for the phonon lifetimes. The predicted temperature dependence of the ultrason! ic loss does not explain the observed saturation of the loss at low temperatures(τ(T) → const), but does give results of the order of magnitude of measured ultrasonic lifetimes.

Adhesive luting of indirect restorations.

PubMed

Krämer, N; Lohbauer, U; Frankenberger, R

2000-11-01

To describe the potential of adhesive luting procedures with respect to (1) material characteristics and classifications, (2) film thickness, (3) overhang control, (4) bonding to different inlay materials, (5) adhesion to tooth substrates and the problem of hypersensitivities, (6) wear of luting composites, and (7) clinical performance. A literature review of relevant studies of various in vitro and in vivo studies enables an overview of possibilities and limitations of adhesively luted indirect restorations. (1) Resin-based composites are the material of choice for adhesive luting. Both material properties and wear behavior of fine particle hybrid-type resin-based composites are superior to other materials. The use of compomers is questionable due to hygroscopic expansion and possible crack formation as proven for IPS Empress caps in vitro and in vivo. (2) Recent luting cements exhibit excellent flow characteristics with mean film thicknesses ranging between 8 microm and 21 microm. The ultrasonic insertion technique is recommended for viscous luting composites or conventional restorative composites utilizing their thixotropic properties. (3) For successful overhang control, good fit of the restoration (during luting) and high radiopacity of the cement (after luting) are indispensable. Overhang control is estimated easier when the ultrasonic insertion technique is applied. (4) The pre-treatments of ceramic inlays using hydrofluoric acid or silica coating result in effective bonding; for pre-treatment of resin-based composite inlays, silica coating is promising as well. (5) Bonding to enamel and dentin is proven clinically acceptable, but it should be performed with multi-step systems providing separate primers and bonding agents producing a perfect internal seal with almost no hypersensitivities. Dual-cured multi-step bonding agents provide the most promising potential. (6) The viscosity and filler content of the resin composite used for luting does not influence the wear characteristics within the marginal luting area in vivo. However, the ultrasonic insertion technique involving high viscosity materials provides enhanced handling characteristics for luting of tooth-colored inlays. (7) Clinical results with tooth-colored inlays and veneers are promising over periods of up to 10 yrs, including use in severely destroyed teeth.

Hermetic edge sealing of photovoltaic modules

NASA Astrophysics Data System (ADS)

1983-02-01

The edge sealing technique is accomplished by a combination of a chemical bond between glass and aluminum, formed by electrostatic bonding, and a metallurgical bond between aluminum and aluminum, formed by ultrasonic welding. Such a glass to metal seal promises to provide a low cost, long lifetime, highly effective hermetic seal which can protect module components from severe environments. Development of the sealing techniques and demonstration of their effectiveness by fabricating a small number of dummy modules, up to eight inches square in size, and testing them for hermeticity using helium leak testing methods are reviewed. Non-destructive test methods are investigated.

Hermetic edge sealing of photovoltaic modules

NASA Technical Reports Server (NTRS)

1983-01-01

The edge sealing technique is accomplished by a combination of a chemical bond between glass and aluminum, formed by electrostatic bonding, and a metallurgical bond between aluminum and aluminum, formed by ultrasonic welding. Such a glass to metal seal promises to provide a low cost, long lifetime, highly effective hermetic seal which can protect module components from severe environments. Development of the sealing techniques and demonstration of their effectiveness by fabricating a small number of dummy modules, up to eight inches square in size, and testing them for hermeticity using helium leak testing methods are reviewed. Non-destructive test methods are investigated.

Thin film solar cells with Si nanocrystallites embedded in amorphous intrinsic layers by hot-wire chemical vapor deposition.

PubMed

Park, Seungil; Parida, Bhaskar; Kim, Keunjoo

2013-05-01

We investigated the thin film growths of hydrogenated silicon by hot-wire chemical vapor deposition with different flow rates of SiH4 and H2 mixture ambient and fabricated thin film solar cells by implementing the intrinsic layers to SiC/Si heterojunction p-i-n structures. The film samples showed the different infrared absorption spectra of 2,000 and 2,100 cm(-1), which are corresponding to the chemical bonds of SiH and SiH2, respectively. The a-Si:H sample with the relatively high silane concentration provides the absorption peak of SiH bond, but the microc-Si:H sample with the relatively low silane concentration provides the absorption peak of SiH2 bond as well as SiH bond. Furthermore, the microc-Si:H sample showed the Raman spectral shift of 520 cm(-1) for crystalline phase Si bonds as well as the 480 cm(-1) for the amorphous phase Si bonds. These bonding structures are very consistent with the further analysis of the long-wavelength photoconduction tail and the formation of nanocrystalline Si structures. The microc-Si:H thin film solar cell has the photovoltaic behavior of open circuit voltage similar to crystalline silicon thin film solar cell, indicating that microc-Si:H thin film with the mixed phase of amorphous and nanocrystalline structures show the carrier transportation through the channel of nanocrystallites.

Advanced signal processing methods applied to guided waves for wire rope defect detection

NASA Astrophysics Data System (ADS)

Tse, Peter W.; Rostami, Javad

2016-02-01

Steel wire ropes, which are usually composed of a polymer core and enclosed by twisted wires, are used to hoist heavy loads. These loads are different structures that can be clamshells, draglines, elevators, etc. Since the loading of these structures is dynamic, the ropes are working under fluctuating forces in a corrosive environment. This consequently leads to progressive loss of the metallic cross-section due to abrasion and corrosion. These defects can be seen in the forms of roughened and pitted surface of the ropes, reduction in diameter, and broken wires. Therefore, their deterioration must be monitored so that any unexpected damage or corrosion can be detected before it causes fatal accident. This is of vital importance in the case of passenger transportation, particularly in elevators in which any failure may cause a catastrophic disaster. At present, the widely used methods for thorough inspection of wire ropes include visual inspection and magnetic flux leakage (MFL). Reliability of the first method is questionable since it only depends on the operators' eyes that fails to determine the integrity of internal wires. The later method has the drawback of being a point by point and time-consuming inspection method. Ultrasonic guided wave (UGW) based inspection, which has proved its capability in inspecting plate like structures such as tubes and pipes, can monitor the cross-section of wire ropes in their entire length from a single point. However, UGW have drawn less attention for defect detection in wire ropes. This paper reports the condition monitoring of a steel wire rope from a hoisting elevator with broken wires as a result of corrosive environment and fatigue. Experiments were conducted to investigate the efficiency of using magnetostrictive based UGW for rope defect detection. The obtained signals were analyzed by two time-frequency representation (TFR) methods, namely the Short Time Fourier Transform (STFT) and the Wavelet analysis. The location of the defect and its severity were successfully identified and characterized.

Memotain: A CAD/CAM nickel-titanium lingual retainer.

PubMed

Kravitz, Neal D; Grauer, Dan; Schumacher, Pascal; Jo, Yong-Min

2017-04-01

Approximately 1/2 of maxillary and 1/5 of mandibular multi-stranded lingual retainers fail during retention in some form, either bond failure or wire breakage. Memotain is a new CAD/CAM fabricated lingual retainer wire made of custom-cut nickel-titanium, as an alternative to multi-stranded lingual retainers. It offers numerous perceived advantages to the traditional multi-stranded stainless steel wire, including precision fit, avoidance of interferences, corrosion resistance and even the potential for minor tooth movement as an active lingual retainer. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Shear horizontal guided wave modes to infer the shear stiffness of adhesive bond layers.

PubMed

Le Crom, Bénédicte; Castaings, Michel

2010-04-01

This paper presents a non-destructive, ultrasonic technique to evaluate the quality of bonds between substrates. Shear-horizontally polarized (SH) wave modes are investigated to infer the shear stiffness of bonds, which is necessarily linked to the shear resistance that is a critical parameter for bonded structures. Numerical simulations are run for selecting the most appropriate SH wave modes, i.e., with higher sensitivity to the bond than to other components, and experiments are made for generating-detecting pre-selected SH wave modes and for measuring their phase velocities. An inverse problem is finally solved, consisting of the evaluation of the shear stiffness modulus of a bond layer at different curing times between a metallic plate and a composite patch, such assembly being investigated in the context of repair of aeronautical structures.

Picosecond ultrasonics study of the vibrational modes of a nanostructure

NASA Astrophysics Data System (ADS)

Antonelli, G. Andrew; Maris, Humphrey J.; Malhotra, Sandra G.; Harper, James M. E.

2002-03-01

We report experiments in which a subpicosecond pump light pulse is used to excite vibrations in a nanostructure consisting of a periodic array of copper wires embedded in a glass matrix on a silicon substrate. The motion of the wires after excitation is detected using a time-delayed probe light pulse. From the measured data, it is possible to determine the frequencies νn and damping rates Γn of a number of the normal modes of the structure. These modes have frequencies lying in the range 1-30 GHz. By comparison of the measured νn and Γn with the frequencies and damping rates calculated from a computer simulation of the vibrations of the nanostructure, we have been able to deduce the vibration patterns of six of the normal modes.

A three-mask process for fabricating vacuum-sealed capacitive micromachined ultrasonic transducers using anodic bonding.

PubMed

Yamaner, F Yalçın; Zhang, Xiao; Oralkan, Ömer

2015-05-01

This paper introduces a simplified fabrication method for vacuum-sealed capacitive micromachined ultrasonic transducer (CMUT) arrays using anodic bonding. Anodic bonding provides the established advantages of wafer-bondingbased CMUT fabrication processes, including process simplicity, control over plate thickness and properties, high fill factor, and ability to implement large vibrating cells. In addition to these, compared with fusion bonding, anodic bonding can be performed at lower processing temperatures, i.e., 350°C as opposed to 1100°C; surface roughness requirement for anodic bonding is more than 10 times more relaxed, i.e., 5-nm rootmean- square (RMS) roughness as opposed to 0.5 nm for fusion bonding; anodic bonding can be performed on smaller contact area and hence improves the fill factor for CMUTs. Although anodic bonding has been previously used for CMUT fabrication, a CMUT with a vacuum cavity could not have been achieved, mainly because gas is trapped inside the cavities during anodic bonding. In the approach we present in this paper, the vacuum cavity is achieved by opening a channel in the plate structure to evacuate the trapped gas and subsequently sealing this channel by conformal silicon nitride deposition in the vacuum environment. The plate structure of the fabricated CMUT consists of the single-crystal silicon device layer of a silicon-on-insulator wafer and a thin silicon nitride insulation layer. The presented fabrication approach employs only three photolithographic steps and combines the advantages of anodic bonding with the advantages of a patterned metal bottom electrode on an insulating substrate, specifically low parasitic series resistance and low parasitic shunt capacitance. In this paper, the developed fabrication scheme is described in detail, including process recipes. The fabricated transducers are characterized using electrical input impedance measurements in air and hydrophone measurements in immersion. A representative design is used to demonstrate immersion operation in conventional, collapse-snapback, and collapse modes. In collapsemode operation, an output pressure of 1.67 MPa pp is shown at 7 MHz on the surface of the transducer for 60-Vpp, 3-cycle sinusoidal excitation at 30-V dc bias.

Electronics Reliability Fracture Mechanics, Volume 2. Fracture Mechanics

DTIC Science & Technology

1992-05-01

alloy or strength level. Aluminum alloy 2024 - T351 was selected as being representative of the aluminum wire, and the fatigue ...to bracket the bond wire fatigue tests. 3-41 Also shown for comparison are two curves, which are the crack growth rates for 2024 aluminum alloy (Ref...is very similar to that for 2024 aluminum alloy . 3.2.6 Discussion of Loop Vibration Fatigue Testing Results This experimental and

Damage detection and locating using tone burst and continuous excitation modulation method

NASA Astrophysics Data System (ADS)

Li, Zheng; Wang, Zhi; Xiao, Li; Qu, Wenzhong

2014-03-01

Among structural health monitoring techniques, nonlinear ultrasonic spectroscopy methods are found to be effective diagnostic approach to detecting nonlinear damage such as fatigue crack, due to their sensitivity to incipient structural changes. In this paper, a nonlinear ultrasonic modulation method was developed to detect and locate a fatigue crack on an aluminum plate. The method is different with nonlinear wave modulation method which recognizes the modulation of low-frequency vibration and high-frequency ultrasonic wave; it recognizes the modulation of tone burst and high-frequency ultrasonic wave. In the experiment, a Hanning window modulated sinusoidal tone burst and a continuous sinusoidal excitation were simultaneously imposed on the PZT array which was bonded on the surface of an aluminum plate. The modulations of tone burst and continuous sinusoidal excitation was observed in different actuator-sensor paths, indicating the presence and location of fatigue crack. The results of experiments show that the proposed method is capable of detecting and locating the fatigue crack successfully.

Simultaneous treatment of washing, disinfection and sterilization using ultrasonic levitation, silver electrolysis and ozone oxidation.

PubMed

Ueda, Toyotoshi; Hara, Masanori; Odagawa, Ikumi; Shigihara, Takanori

2009-03-01

A new type of ultrasonic washer-disinfector-sterilizer, able to clean, disinfect and sterilize most kinds of reusable medical devices, has been developed by using the ultrasonic levitation function with umbrella-shape oscillators and ozone bubbling together with sterilization carried out by silver electrolysis. We have examined the biomedical and physicochemical performance of this instrument. Prokariotic and gram-negative Escherichia coli and eukariotic Saccharomyces cerevisiae were killed by silver electrolysis in 18 min and 1 min, respectively. Prokariotic and gram-positive Geobacillus stearothermophilus and Bacillus atrophaeus, which are most resistant to autoclave and gas sterilization, respectively, were killed by silver electrolysis within 20 min. Prokariotic and gram-negative Pseudomonas aeruginosa was also killed by silver electrolysis in 10 min. The intensity distribution of the ultrasonic levitation waves was homogeneous throughout the tank. The concentration of ozone gas was 2.57 mg/ kg. The concentration of dissolved silver ions was around 0.17 mg/L. The disulfide bond in proteins was confirmed to be destroyed by silver electrolysis.

Sandwich Panels Evaluated With Ultrasonic Spectroscopy

NASA Technical Reports Server (NTRS)

Cosgriff, Laura M.

2004-01-01

Enhanced, lightweight material systems, such as 17-4PH stainless steel sandwich panels are being developed for use as fan blades and fan containment systems for next-generation engines. The bond strength between the core and face sheets is critical in maintaining the structural integrity of the sandwich structure. To improve the inspection and production of these systems, researchers at the NASA Glenn Research Center are using nondestructive evaluation (NDE) techniques, such as ultrasonic spectroscopy, to evaluate the brazing quality between the face plates and the metallic foam core. The capabilities and limitations of a swept-frequency approach to ultrasonic spectroscopy were evaluated with respect to these sandwich structures. This report discusses results from three regions of a sandwich panel representing different levels of brazing quality between the outer face plates and a metallic foam core. Each region was investigated with ultrasonic spectroscopy. Then, on the basis of the NDE results, three shear specimens sectioned from the sandwich panel to contain each of these regions were mechanically tested.

Detection of bondline delaminations in multilayer structures with lossy components

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Winfree, William P.; Smith, B. T.; Heyman, Joseph H.

1988-01-01

The detection of bondline delaminations in multilayer structures using ultrasonic reflection techniques is a generic problem in adhesively bonded composite structures such as the Space Shuttles's Solid Rocket Motors (SRM). Standard pulse echo ultrasonic techniques do not perform well for a composite resonator composed of a resonant layer combined with attenuating layers. Excessive ringing in the resonant layer tends to mask internal echoes emanating from the attenuating layers. The SRM is made up of a resonant steel layer backed by layers of adhesive, rubber, liner and fuel, which are ultrasonically attenuating. The structure's response is modeled as a lossy ultrasonic transmission line. The model predicts that the acoustic response of the system is sensitive to delaminations at the interior bondlines in a few narrow frequency bands. These predictions are verified by measurements on a fabricated system. Successful imaging of internal delaminations is sensitive to proper selection of the interrogating frequency. Images of fabricated bondline delaminations are presented based on these studies.

Design and performance testing of an ultrasonic linear motor with dual piezoelectric actuators.

PubMed

Smithmaitrie, Pruittikorn; Suybangdum, Panumas; Laoratanakul, Pitak; Muensit, Nantakan

2012-05-01

In this work, design and performance testing of an ultrasonic linear motor with dual piezoelectric actuator patches are studied. The motor system consists of a linear stator, a pre-load weight, and two piezoelectric actuator patches. The piezoelectric actuators are bonded with the linear elastic stator at specific locations. The stator generates propagating waves when the piezoelectric actuators are subjected to harmonic excitations. Vibration characteristics of the linear stator are analyzed and compared with finite element and experimental results. The analytical, finite element, and experimental results show agreement. In the experiments, performance of the ultrasonic linear motor is tested. Relationships between velocity and pre-load weight, velocity and applied voltage, driving force and applied voltage, and velocity and driving force are reported. The design of the dual piezoelectric actuators yields a simpler structure with a smaller number of actuators and lower stator stiffness compared with a conventional design of an ultrasonic linear motor with fully laminated piezoelectric actuators.

Influence of power density on polymerization behavior and bond strengths of dual-cured resin direct core foundation systems.

PubMed

Oto, Tatsuki; Yasuda, Genta; Tsubota, Keishi; Kurokawa, Hiroyasu; Miyazaki, Masashi; Platt, Jeffrey A

2009-01-01

This study examined the influence of power density on dentin bond strength and polymerization behavior of dual-cured direct core foundation resin systems. Two commercially available dual-cured direct core foundation resin systems, Clearfil DC Core Automix with Clearfil DC Bond and UniFil Core with Self-Etching Bond, were studied. Bovine mandibular incisors were mounted in autopolymerizing resin and the facial dentin surfaces were ground wet on 600-grit SiC paper. Dentin surfaces were treated according to manufacturer's recommendations. The resin pastes were condensed into the mold and cured with the power densities of 0 (no irradiation), 100, 200, 400 and 600 mW/cm2. Ten specimens per group were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute in a universal testing machine. An ultrasonic measurement device was used to measure the ultrasonic velocities through the core foundation resins. The power densities selected were 0 (no irradiation), 200, and 600 mW/cm2, and ultrasonic velocity was calculated. ANOVA and Tukey HSD tests were performed at a level of 0.05. The highest bond strengths were obtained when the resin pastes were cured with the highest power density for both core foundation systems (16.8 +/- 1.9 MPa for Clearfil DC Core Automix, 15.6 +/- 2.9 MPa for UniFil Core). When polymerized with the power densities under 200 mW/cm2, significantly lower bond strengths were observed compared to those obtained with the power density of 600 mW/cm2. As the core foundation resins hardened, the sonic velocities increased and this tendency differed among the power density of the curing unit. When the sonic velocities at three minutes after the start of measurements were compared, there were no significant differences among different irradiation modes for UniFil Core, while a significant decrease in sonic velocity was obtained when the resin paste was chemically polymerized compared with dual-polymerization for Clearfil DC Core Automix. The data suggests that the dentin bond strengths and polymerization behavior of the dual-cured, direct core foundation systems are still affected by the power density of the curing unit. With a careful choice of the core foundation systems and power density of the curing unit, the benefit of using resin composites to endodontically-treated teeth might be acceptable.

Large scale generation of micro-droplet array by vapor condensation on mesh screen piece

PubMed Central

Xie, Jian; Xu, Jinliang; He, Xiaotian; Liu, Qi

2017-01-01

We developed a novel micro-droplet array system, which is based on the distinct three dimensional mesh screen structure and sintering and oxidation induced thermal-fluid performance. Mesh screen was sintered on a copper substrate by bonding the two components. Non-uniform residue stress is generated along weft wires, with larger stress on weft wire top location than elsewhere. Oxidation of the sintered package forms micro pits with few nanograsses on weft wire top location, due to the stress corrosion mechanism. Nanograsses grow elsewhere to show hydrophobic behavior. Thus, surface-energy-gradient weft wires are formed. Cooling the structure in a wet air environment nucleates water droplets on weft wire top location, which is more “hydrophilic” than elsewhere. Droplet size is well controlled by substrate temperature, air humidity and cooling time. Because warp wires do not contact copper substrate and there is a larger conductive thermal resistance between warp wire and weft wire, warp wires contribute less to condensation but function as supporting structure. The surface energy analysis of drops along weft wires explains why droplet array can be generated on the mesh screen piece. Because the commercial material is used, the droplet system is cost effective and can be used for large scale utilization. PMID:28054635

Large scale generation of micro-droplet array by vapor condensation on mesh screen piece.

PubMed

Xie, Jian; Xu, Jinliang; He, Xiaotian; Liu, Qi

2017-01-05

We developed a novel micro-droplet array system, which is based on the distinct three dimensional mesh screen structure and sintering and oxidation induced thermal-fluid performance. Mesh screen was sintered on a copper substrate by bonding the two components. Non-uniform residue stress is generated along weft wires, with larger stress on weft wire top location than elsewhere. Oxidation of the sintered package forms micro pits with few nanograsses on weft wire top location, due to the stress corrosion mechanism. Nanograsses grow elsewhere to show hydrophobic behavior. Thus, surface-energy-gradient weft wires are formed. Cooling the structure in a wet air environment nucleates water droplets on weft wire top location, which is more "hydrophilic" than elsewhere. Droplet size is well controlled by substrate temperature, air humidity and cooling time. Because warp wires do not contact copper substrate and there is a larger conductive thermal resistance between warp wire and weft wire, warp wires contribute less to condensation but function as supporting structure. The surface energy analysis of drops along weft wires explains why droplet array can be generated on the mesh screen piece. Because the commercial material is used, the droplet system is cost effective and can be used for large scale utilization.

Large scale generation of micro-droplet array by vapor condensation on mesh screen piece

NASA Astrophysics Data System (ADS)

Xie, Jian; Xu, Jinliang; He, Xiaotian; Liu, Qi

2017-01-01

We developed a novel micro-droplet array system, which is based on the distinct three dimensional mesh screen structure and sintering and oxidation induced thermal-fluid performance. Mesh screen was sintered on a copper substrate by bonding the two components. Non-uniform residue stress is generated along weft wires, with larger stress on weft wire top location than elsewhere. Oxidation of the sintered package forms micro pits with few nanograsses on weft wire top location, due to the stress corrosion mechanism. Nanograsses grow elsewhere to show hydrophobic behavior. Thus, surface-energy-gradient weft wires are formed. Cooling the structure in a wet air environment nucleates water droplets on weft wire top location, which is more “hydrophilic” than elsewhere. Droplet size is well controlled by substrate temperature, air humidity and cooling time. Because warp wires do not contact copper substrate and there is a larger conductive thermal resistance between warp wire and weft wire, warp wires contribute less to condensation but function as supporting structure. The surface energy analysis of drops along weft wires explains why droplet array can be generated on the mesh screen piece. Because the commercial material is used, the droplet system is cost effective and can be used for large scale utilization.

Explosive Spot Joining of Metals

NASA Technical Reports Server (NTRS)

Bement, Laurence J. (Inventor); Perry, Ronnie B. (Inventor)

1997-01-01

The invention is an apparatus and method for wire splicing using an explosive joining process. The apparatus consists of a prebend, U-shaped strap of metal that slides over prepositioned wires. A standoff means separates the wires from the strap before joining. An adhesive means holds two ribbon explosives in position centered over the U-shaped strap. A detonating means connects to the ribbon explosives. The process involves spreading strands of each wire to be joined into a flat plane. The process then requires alternating each strand in alignment to form a mesh-like arrangement with an overlapped area. The strap slides over the strands of the wires. and the standoff means is positioned between the two surfaces. The detonating means then initiates the ribbon explosives that drive the strap to accomplish a high velocity. angular collision between the mating surfaces. This collision creates surface melts and collision bonding resulting in electron-sharing linkups.

Experimental validation of ultrasonic guided modes in electrical cables by optical interferometry.

PubMed

Mateo, Carlos; de Espinosa, Francisco Montero; Gómez-Ullate, Yago; Talavera, Juan A

2008-03-01

In this work, the dispersion curves of elastic waves propagating in electrical cables and in bare copper wires are obtained theoretically and validated experimentally. The theoretical model, based on Gazis equations formulated according to the global matrix methodology, is resolved numerically. Viscoelasticity and attenuation are modeled theoretically using the Kelvin-Voigt model. Experimental tests are carried out using interferometry. There is good agreement between the simulations and the experiments despite the peculiarities of electrical cables.

High Temperature Ultrasonic Transducer for Real-time Inspection

NASA Astrophysics Data System (ADS)

Amini, Mohammad Hossein; Sinclair, Anthony N.; Coyle, Thomas W.

A broadband ultrasonic transducer with a novel porous ceramic backing layer is introduced to operate at 700 °C. 36° Y-cut lithium niobate (LiNbO3) single crystal was selected for the piezoelectric element. By appropriate choice of constituent materials, porosity and pore size, the acoustic impedance and attenuation of a zirconia-based backing layer were optimized. An active brazing alloy with high temperature and chemical stability was selected to bond the transducer layers together. Prototype transducers have been tested at temperatures up to 700 °C. The experiments confirmed that transducer integrity was maintained.

Phenomenally High Transduction Air/gas Transducers for Practical Non-Contact Ultrasonic Applications

NASA Astrophysics Data System (ADS)

Bhardwaj, Mahesh C.

2009-03-01

Based on novel acoustic impedance matching layers and high coupling piezoelectric materials this paper describes exceptionally high air/gas transduction ultrasonic transducers. By providing applications oriented performance of these transducers we also usher in the era of much desired Non-Contact Ultrasound (NCU) testing and analysis of a wide range of materials including early stage formation of materials such as uncured composite prepregs, green ceramics and powder metals, plastics, elastomers, porous, hygroscopic, chemically bonded and other materials. Besides quality control, ultimately NCU offers timely opportunities for cost-effective materials production, energy savings, and environment protection.

Functionally Graded Shape Memory Alloy Composites Optimized for Passive Vibration Control

DTIC Science & Technology

2006-11-20

Nitinol , it is anticipated that the wire can only experience an incomplete hysteresis. 2.1. SMA wires in sleeves continuously bonded to the plate...Gilheany, J. 1995. Control of the natural frequencies of nitinol -reinforced composite beams, Journal of Sound and Vibrations, Vol. 185, 171-185. 3 Ro...J., and Baz, A., 1995. Nitinol -reinforced plates: Part III, Dynamic characteristics, Composites Engineering, Vol. 5, 91-106. 4 Epps, J and Chandra

A traveling wave ultrasonic motor of high torque.

PubMed

Chen, Y; Liu, Q L; Zhou, T Y

2006-12-22

A traveling wave ultrasonic motor of high torque with a new configuration is proposed in this paper. In the new design, a part of the motor serves as the stator. The rotor is the vibrator consisting of a toothed metal ring with piezoelectric ceramic bonded, which generates ultrasonic vibration. The rotor is in contact with the shell of motor and is driven by the friction between the rotor and the stator. This configuration not only removes the rotor in a conventional type of traveling wave ultrasonic motor but also changes the interaction between the rotor and the stator of the motor so that it improves the output performance of the motor. Although an electric brush is added to the ultrasonic motor, it is easy to be fabricated because of the low speed of motor. The finite element method was used to compute the vibration modes of an ultrasonic motor with a diameter of 100mm to optimize the design of the motor. A 9th mode was chosen as the operation mode with a resonance frequency about 25 kHz. According to the design, a prototype was fabricated. Its performance was measured. The rotation speed-torque curves for various frequencies were obtained. The result shows that its stall torque is greater than 4 Nm within a range of 400 Hz. This ultrasonic motor was used to drive the window glass of a mobile car and the result was satisfactory. In the further the research on the friction material between the stator and the rotor is under way to improve the efficiency of the ultrasonic motor.

A tool for measuring the bending length in thin wires

NASA Astrophysics Data System (ADS)

Lorenzini, M.; Cagnoli, G.; Cesarini, E.; Losurdo, G.; Martelli, F.; Piergiovanni, F.; Vetrano, F.; Viceré, A.

2013-03-01

Great effort is currently being put into the development and construction of the second generation, advanced gravitational wave detectors, Advanced Virgo and Advanced LIGO. The development of new low thermal noise suspensions of mirrors, based on the experience gained in the previous experiments, is part of this task. Quasi-monolithic suspensions with fused silica wires avoid the problem of rubbing friction introduced by steel cradle arrangements by directly welding the wires to silica blocks bonded to the mirror. Moreover, the mechanical loss level introduced by silica (ϕfs ˜ 10-7 in thin fused silica wires) is by far less than the one associated with steel. The low frequency dynamical behaviour of the suspension can be computed and optimized, provided that the wire bending shape under pendulum motion is known. Due to the production process, fused silica wires are thicker near the two ends (necks), so that analytical bending computations are very complicated. We developed a tool to directly measure the low frequency bending parameters of fused silica wires, and we tested it on the wires produced for the Virgo+ monolithic suspensions. The working principle and a set of test measurements are presented and explained.

A tool for measuring the bending length in thin wires.

PubMed

Lorenzini, M; Cagnoli, G; Cesarini, E; Losurdo, G; Martelli, F; Piergiovanni, F; Vetrano, F; Viceré, A

2013-03-01

Great effort is currently being put into the development and construction of the second generation, advanced gravitational wave detectors, Advanced Virgo and Advanced LIGO. The development of new low thermal noise suspensions of mirrors, based on the experience gained in the previous experiments, is part of this task. Quasi-monolithic suspensions with fused silica wires avoid the problem of rubbing friction introduced by steel cradle arrangements by directly welding the wires to silica blocks bonded to the mirror. Moreover, the mechanical loss level introduced by silica (φfs ∼ 10(-7) in thin fused silica wires) is by far less than the one associated with steel. The low frequency dynamical behaviour of the suspension can be computed and optimized, provided that the wire bending shape under pendulum motion is known. Due to the production process, fused silica wires are thicker near the two ends (necks), so that analytical bending computations are very complicated. We developed a tool to directly measure the low frequency bending parameters of fused silica wires, and we tested it on the wires produced for the Virgo+ monolithic suspensions. The working principle and a set of test measurements are presented and explained.

Field deployable processing methods for stay-in-place ultrasonic transducers

NASA Astrophysics Data System (ADS)

Malarich, Nathan; Lissenden, Cliff J.; Tittmann, Bernhard R.

2018-04-01

Condition monitoring provides key data for managing the operation and maintenance of mechanical equipment in the power generation, chemical processing, and manufacturing industries. Ultrasonic transducers provide active monitoring capabilities by wall thickness measurements, elastic property determination, crack detection, and other means. In many cases the components operate in harsh environments that may include high temperature, radiation, and hazardous chemicals. Thus, it is desirable to have permanently affixed ultrasonic transducers for condition monitoring in harsh environments. Spray-on transducers provide direct coupling between the active element and the substrate, and can be applied to curved surfaces. We describe a deposition methodology for ultrasonic transducers that can be applied in the field. First, piezoceramic powders mixed into a sol-gel are air-spray deposited onto the substrate. Powder constituents are selected based on the service environment in which the condition monitoring will be performed. Then the deposited coating is pyrolyzed and partially densified using an induction heating system with a custom work coil designed to match the substrate geometry. The next step, applying the electrodes, is more challenging than might be expected because of the porosity of the piezoelectric coating and the potential reactivity of elements in the adjacent layers. After connecting lead wires to the electrodes the transducer is poled and a protective coating can be applied prior to use. Processing of a PZT-bismuth titanate transducer on a large steel substrate is described along with alternate methods.

Removal of distal protein–water hydrogen bonds in a plant epoxide hydrolase increases catalytic turnover but decreases thermostability

PubMed Central

Thomaeus, Ann; Naworyta, Agata; Mowbray, Sherry L.; Widersten, Mikael

2008-01-01

A putative proton wire in potato soluble epoxide hydrolase 1, StEH1, was identified and investigated by means of site-directed mutagenesis, steady-state kinetic measurements, temperature inactivation studies, and X-ray crystallography. The chain of hydrogen bonds includes five water molecules coordinated through backbone carbonyl oxygens of Pro186, Leu266, His269, and the His153 imidazole. The hydroxyl of Tyr149 is also an integrated component of the chain, which leads to the hydroxyl of Tyr154. Available data suggest that Tyr154 functions as a final proton donor to the anionic alkylenzyme intermediate formed during catalysis. To investigate the role of the putative proton wire, mutants Y149F, H153F, and Y149F/H153F were constructed and purified. The structure of the Y149F mutant was solved by molecular replacement and refined to 2.0 Å resolution. Comparison with the structure of wild-type StEH1 revealed only subtle structural differences. The hydroxyl group lost as a result of the mutation was replaced by a water molecule, thus maintaining a functioning hydrogen bond network in the proton wire. All mutants showed decreased catalytic efficiencies with the R,R-enantiomer of trans-stilbene oxide, whereas with the S,S-enantiomer, k cat/K M was similar or slightly increased compared with the wild-type reactions. k cat for the Y149F mutant with either TSO enantiomer was increased; thus the lowered enzyme efficiencies were due to increases in K M. Thermal inactivation studies revealed that the mutated enzymes were more sensitive to elevated temperatures than the wild-type enzyme. Hence, structural alterations affecting the hydrogen bond chain caused increases in k cat but lowered thermostability. PMID:18515642

Removal of distal protein-water hydrogen bonds in a plant epoxide hydrolase increases catalytic turnover but decreases thermostability.

PubMed

Thomaeus, Ann; Naworyta, Agata; Mowbray, Sherry L; Widersten, Mikael

2008-07-01

A putative proton wire in potato soluble epoxide hydrolase 1, StEH1, was identified and investigated by means of site-directed mutagenesis, steady-state kinetic measurements, temperature inactivation studies, and X-ray crystallography. The chain of hydrogen bonds includes five water molecules coordinated through backbone carbonyl oxygens of Pro(186), Leu(266), His(269), and the His(153) imidazole. The hydroxyl of Tyr(149) is also an integrated component of the chain, which leads to the hydroxyl of Tyr(154). Available data suggest that Tyr(154) functions as a final proton donor to the anionic alkylenzyme intermediate formed during catalysis. To investigate the role of the putative proton wire, mutants Y149F, H153F, and Y149F/H153F were constructed and purified. The structure of the Y149F mutant was solved by molecular replacement and refined to 2.0 A resolution. Comparison with the structure of wild-type StEH1 revealed only subtle structural differences. The hydroxyl group lost as a result of the mutation was replaced by a water molecule, thus maintaining a functioning hydrogen bond network in the proton wire. All mutants showed decreased catalytic efficiencies with the R,R-enantiomer of trans-stilbene oxide, whereas with the S,S-enantiomer, k (cat)/K (M) was similar or slightly increased compared with the wild-type reactions. k (cat) for the Y149F mutant with either TSO enantiomer was increased; thus the lowered enzyme efficiencies were due to increases in K (M). Thermal inactivation studies revealed that the mutated enzymes were more sensitive to elevated temperatures than the wild-type enzyme. Hence, structural alterations affecting the hydrogen bond chain caused increases in k (cat) but lowered thermostability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sridharan, Niyanth; Gussev, Maxim; Seibert, Rachel

Ultrasonic additive manufacturing (UAM) is a solid-state process, which uses ultrasonic vibrations at 20 kHz along with mechanized tape layering and intermittent milling operation, to build fully functional three-dimensional parts. In the literature, UAM builds made with low power (1.5 kW) exhibited poor tensile properties in Z-direction, i.e., normal to the interfaces. This reduction in properties is often attributed to the lack of bonding at faying interfaces. The generality of this conclusion is evaluated further in 6061 aluminum alloy builds made with very high power UAM (9 kW). Tensile deformation behavior along X and Z directions were evaluated with small-scalemore » in-situ mechanical testing equipped with high-resolution digital image correlation, as well as, multi-scale characterization of builds. Interestingly, even with complete metallurgical bonding across the interfaces without any discernable voids, poor Z-direction properties were observed. This reduction is correlated to coalescence of pre-existing shear bands at interfaces into micro voids, leading to strain localization and spontaneous failure on tensile loading.« less

A study of the vibrational modes of a nanostructure with picosecond ultrasonics

NASA Astrophysics Data System (ADS)

Antonelli, G. Andrew; Maris, Humphrey J.; Malhotra, Sandra G.; Harper, James M. E.

2002-05-01

We describe experiments in which a sub-picosecond pump light pulse is used to excite vibrations in a nanostructure. The sample consists of a periodic array of copper wires embedded in a glass matrix on a silicon substrate. The motion of the wires after excitation is detected using a time-delayed probe light pulse. From the data, it is possible to determine the frequencies νn and damping rates Γn of a number of the normal modes of the structure. These modes have frequencies lying in the range 1-30 GHz. By comparison of the measured νn and Γn with the frequencies and damping rates calculated from a computer simulation of the vibrations of the nanostructure, we have been able to identify the different normal modes and deduce their vibration patterns.

Advance High Temperature Inspection Capabilities for Small Modular Reactors: Part 1 - Ultrasonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bond, Leonard J.; Bowler, John R.

The project objective was to investigate the development non-destructive evaluation techniques for advanced small modular reactors (aSMR), where the research sought to provide key enabling inspection technologies needed to support the design and maintenance of reactor component performance. The project tasks for the development of inspection techniques to be applied to small modular reactor are being addressed through two related activities. The first is focused on high temperature ultrasonic transducers development (this report Part 1) and the second is focused on an advanced eddy current inspection capability (Part 2). For both inspection techniques the primary aim is to develop in-servicemore » inspection techniques that can be carried out under standby condition in a fast reactor at a temperature of approximately 250°C in the presence of liquid sodium. The piezoelectric material and the bonding between layers have been recognized as key factors fundamental for development of robust ultrasonic transducers. Dielectric constant characterization of bismuth scantanate-lead titanate ((1-x)BiScO 3-xPbTiO 3) (BS-PT) has shown a high Curie temperature in excess of 450°C , suitable for hot stand-by inspection in liquid metal reactors. High temperature pulse-echo contact measurements have been performed with BS-PT bonded to 12.5 mm thick 1018-low carbon steel plate from 20C up to 260 C. High temperature air-backed immersion transducers have been developed with BS-PT, high temperature epoxy and quarter wavlength nickel plate, needed for wetting ability in liquid sodium. Ultrasonic immersion measurements have been performed in water up to 92C and in silicone oil up to 140C. Physics based models have been validated with room temperature experimental data with benchmark artifical defects.« less

Nondestructive characterization of thermal barrier coating by noncontact laser ultrasonic technique

NASA Astrophysics Data System (ADS)

Zhao, Yang; Chen, Jianwei; Zhang, Zhenzhen

2015-09-01

We present the application of a laser ultrasonic technique in nondestructive characterization of the bonding layer (BL) in a thermal barrier coating (TBC). A physical mode of a multilayered medium is established to describe the propagation of a longitudinal wave generated by a laser in a TBC system. Furthermore, the theoretical analysis on the ultrasonic transmission in TBC is carried out in order to derive the expression of the BL transmission coefficient spectrum (TCS) which is used to determine the velocity of the longitudinal wave in the BL. We employ the inversion method combined with TCS to ascertain the attenuation coefficient of the BL. The experimental validations are performed with TBC specimens produced by an electron-beam physical vapor deposition method. In those experiments, a pulsed laser with a width of 10 ns is used to generate an ultrasonic signal while a two-wave mixing interferometer is created to receive the ultrasonic signals. By introducing the wavelet soft-threshold method that improves the signal-to-noise ratio, the laser ultrasonic testing results of TBC with an oxidation of 1 cycle, 10 cycles, and 100 cycles show that the attenuation coefficients of the BL become larger with an increase in the oxidation time, which is evident for the scanning electron microscopy observations, in which the thickness of the thermally grown oxide increases with oxidation time.

Anodic bonding using SOI wafer for fabrication of capacitive micromachined ultrasonic transducers

NASA Astrophysics Data System (ADS)

Bellaredj, M.; Bourbon, G.; Walter, V.; Le Moal, P.; Berthillier, M.

2014-02-01

In medical ultrasound imaging, mostly piezoelectric crystals are used as ultrasonic transducers. Capacitive micromachined ultrasonic transducers (CMUTs) introduced around 1994 have been shown to be a good alternative to conventional piezoelectric transducers in various aspects, such as sensitivity, transduction efficiency or bandwidth. This paper focuses on a fabrication process for CMUTs using anodic bonding of a silicon on insulator wafer on a glass wafer. The processing steps are described leading to a good control of the mechanical response of the membrane. This technology makes possible the fabrication of large membranes and can extend the frequency range of CMUTs to lower frequencies of operation. Silicon membranes having radii of 50, 70, 100 and 150 µm and a 1.5 µm thickness are fabricated and electromechanically characterized using an auto-balanced bridge impedance analyzer. Resonant frequencies from 0.6 to 2.3 MHz and an electromechanical coupling coefficient around 55% are reported. The effects of residual stress in the membranes and uncontrolled clamping conditions are clearly responsible for the discrepancies between experimental and theoretical values of the first resonance frequency. The residual stress in the membranes is determined to be between 90 and 110 MPa. The actual boundary conditions are between the clamped condition and the simply supported condition and can be modeled with a torsional stiffness of 2.10-7 Nm rad-1 in the numerical model.

Piezoelectric micromachined ultrasonic transducers for fingerprint sensing

NASA Astrophysics Data System (ADS)

Lu, Yipeng

Fingerprint identification is the most prevalent biometric technology due to its uniqueness, universality and convenience. Over the past two decades, a variety of physical mechanisms have been exploited to capture an electronic image of a human fingerprint. Among these, capacitive fingerprint sensors are the ones most widely used in consumer electronics because they are fabricated using conventional complementary metal oxide semiconductor (CMOS) integrated circuit technology. However, capacitive fingerprint sensors are extremely sensitive to finger contamination and moisture. This thesis will introduce an ultrasonic fingerprint sensor using a PMUT array, which offers a potential solution to this problem. In addition, it has the potential to increase security, as it allows images to be collected at various depths beneath the epidermis, providing images of the sub-surface dermis layer and blood vessels. Firstly, PMUT sensitivity is maximized by optimizing the layer stack and electrode design, and the coupling coefficient is doubled via series transduction. Moreover, a broadband PMUT with 97% fractional bandwidth is achieved by utilizing a thinner structure excited at two adjacent mechanical vibration modes with overlapping bandwidth. In addition, we proposed waveguide PMUTs, which function to direct acoustic waves, confine acoustic energy, and provide mechanical protection for the PMUT array. Furthermore, PMUT arrays were fabricated with different processes to form the membrane, including front-side etching with a patterned sacrificial layer, front-side etching with additional anchor, cavity SOI wafers and eutectic bonding. Additionally, eutectic bonding allows the PMUT to be integrated with CMOS circuits. PMUTs were characterized in the mechanical, electrical and acoustic domains. Using transmit beamforming, a narrow acoustic beam was achieved, and high-resolution (sub-100 microm) and short-range (~1 mm) pulse-echo ultrasonic imaging was demonstrated using a steel phantom. Finally, a novel ultrasonic fingerprint sensor was demonstrated using a 24x8 array of 22 MHz PMUTs with 100 microm pitch, fully integrated with 180 nm CMOS circuitry through eutectic wafer bonding. Each PMUT is directly bonded to a dedicated CMOS receive amplifier, minimizing electrical parasitics and eliminating the need for through-silicon vias. Pulse-echo imaging of a 1D steel grating is demonstrated using electronic scanning of a 20x8 sub-array, resulting in 300 mV maximum received amplitude and 5:1 contrast ratio. Because the small size of this array limits the maximum image size, mechanical scanning was used to image a 2D PDMS fingerprint phantom (10 mm by 8 mm) at a 1.2 mm distance from the array.

Effects of sandblasting and silica-coating procedures on pure titanium.

PubMed

Kern, M; Thompson, V P

1994-10-01

Silica coating titanium improves chemomechanical bonding. Sandblasting is recommended as a pretreatment to thermal silica coating (Silicoater MD) or as part of a tribochemical silica coating process (Rocatec). This study evaluated the effects of sandblasting and coating techniques on volume loss, surface morphology and composition changes in pure titanium. Volume loss of titanium was similar to values reported for base alloys and does not seem to be critical for the clinical fit of restorations. Embedded alumina particles were found in the titanium after sandblasting and the alumina content increased to a range of 27.5-39.3 wt% as measured by EDS. Following tribochemical silica coating, a layer of small silica particles remained on the surface, increasing the silica content to a range of 17.9-19.5 wt%. Ultrasonic cleaning removed loose alumina or silica particles from the surface, resulting in only slight decreases in alumina or silica contents, suggesting firm attachment of most of the alumina and silica to the titanium surface. Silica content following thermal silica coating treatment increased only slightly from the sandblasted specimen to 1.4 wt%. The silica layer employed by these silica coating methods differs widely in both morphology and thickness. These results provide a basis for explanation of adhesive failure modes in bond strength tests and for developing methods to optimize resin bonding. Clinically, ultrasonic cleaning of sandblasted and tribochemically silica coated titanium should improve resin bonding as loose surface particles are removed without relevant changes in composition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Rui; Gao, Liming, E-mail: liming.gao@sjtu.edu.cn; Li, Ming, E-mail: mingli90@sjtu.edu.cn

As the continuous shrinkage of the interconnect line width in microelectronics devices, there is a growing concern about the electromigration (EM) failure of bonding wire. In addition, an innovative Ag–8Au–3Pd alloy wire has shown promise as an economical substitute for gold wire interconnects due to the cost pressure of gold in the last decade. In present study of the Ag–8Au–3Pd alloy wire, the surface diffusion occupied the dominant position during EM failure, and the activation energy was found to be 0.61 eV. In order to reveal the failure mechanism, the cross-sections of the Ag–8Au–3Pd alloy wire during EM were preparedmore » by focused ion beam (FIB) micro-machining for electron backscatter diffraction (EBSD) analysis. The microstructure evolution of the Ag–8Au–3Pd alloy wire was characterized by the grain size and grain boundary. As a result, the EM failure originates in the atom transportation, which causes grain size increasing and atom diffusion on the wire surface. - Highlights: • The activation energy of Ag–8Au–3Pd alloy wire was obtained as 0.61 eV. • During EM, the silver atoms diffused from negative to the positive terminal on the wire surface. • The microstructure (grain size and grain boundary) was characterized by FIB-EBSD. • During EM, the atom transportation was found to cause grain size growth and atom diffusion on the wire surface.« less

Pulling monatomic gold wires with single molecules: an Ab initio simulation.

PubMed

Krüger, Daniel; Fuchs, Harald; Rousseau, Roger; Marx, Dominik; Parrinello, Michele

2002-10-28

Car-Parrinello molecular dynamics simulations demonstrate that pulling a single thiolate molecule anchored on a stepped gold surface does not preferentially break the sulfur-gold chemical bond. Instead, it is found that this process leads to the formation of a monoatomic gold nanowire, followed by breaking a gold-gold bond with a rupture force of about 1.2 nN. The simulations also indicate that previous single-molecule thiolate-gold and gold-gold rupture experiments both probe the same phenomenon, namely, the breaking of a gold-gold bond within a gold nanowire.

Microfabricated Electrical Connector for Atomic Force Microscopy Probes with Integrated Sensor/Actuator

NASA Astrophysics Data System (ADS)

Akiyama, Terunobu; Staufer, Urs; Rooij, Nico F. de

2002-06-01

A microfabricated, electrical connector is proposed for facilitating the mounting of atomic force microscopy (AFM) probes, which have an integrated sensor and/or actuator. Only a base chip, which acts as a socket, is permanently fixed onto a printed circuit board and electronically connected by standard wire bonding. The AFM chip, the “plug”, is flipped onto the base chip and pressed from the backside by a spring. Electrical contact with the eventual stress sensors, capacitive or piezoelectric sensor/actuators, is provided by contact bumps. These bumps of about 8 μm height are placed onto the base chip. They touch the pads on the AFM chip that were originally foreseen to be for wire bonding and thus provide the electrical contact. This connector schema was successfully used to register AFM images with piezoresistive cantilevers.

Feasibility study of silicon nitride protection of plastic encapsulated semiconductors

NASA Technical Reports Server (NTRS)

Peters, J. W.; Hall, T. C.; Erickson, J. J.; Gebhart, F. L.

1979-01-01

The application of low temperature silicon nitride protective layers on wire bonded integrated circuits mounted on lead frame assemblies is reported. An evaluation of the mechanical and electrical compatibility of both plasma nitride and photochemical silicon nitride (photonitride) passivations (parallel evaluations) of integrated circuits which were then encapsulated in plastic is described. Photonitride passivation is compatible with all wire bonded lead frame assemblies, with or without initial chip passivation. Plasma nitride passivation of lead frame assemblies is possible only if the chip is passivated before lead frame assembly. The survival rate after the environmental test sequence of devices with a coating of plasma nitride on the chip and a coating of either plasma nitride or photonitride over the assembled device is significantly greater than that of devices assembled with no nitride protective coating over either chip or lead frame.

Engineering and experimental analyses of the tensile loads applied during strength testing of direct bonded orthodontic brackets.

PubMed

Katona, T R; Chen, J

1994-08-01

The stress levels within the cement layer (hence, the apparent strength) of a direct bonded orthodontic bracket depends, to a large extent, on the alignment of the tensile loads that are applied to the specimen. The purpose of this analysis was to determine how the construction of a ligature wire harness affects the alignment of the applied loads. Tensile tests conducted on a modified bracket/cement system showed large variations in the force-elongation curve profiles. An engineering model was developed to explain these deviations. The results indicate that it is virtually impossible to evenly apply tensile loads to the bracket. It was also proposed that long harnesses constructed with thin ligature wire, prestressing the harness, and lubrication may reduce some of the effects of unavoidable load-bracket misalignment.

Design, fabrication and actuation of a MEMS-based image stabilizer for photographic cell phone applications

NASA Astrophysics Data System (ADS)

Chiou, Jin-Chern; Hung, Chen-Chun; Lin, Chun-Ying

2010-07-01

This work presents a MEMS-based image stabilizer applied for anti-shaking function in photographic cell phones. The proposed stabilizer is designed as a two-axis decoupling XY stage 1.4 × 1.4 × 0.1 mm3 in size, and adequately strong to suspend an image sensor for anti-shaking photographic function. This stabilizer is fabricated by complex fabrication processes, including inductively coupled plasma (ICP) processes and flip-chip bonding technique. Based on the special designs of a hollow handle layer and a corresponding wire-bonding assisted holder, electrical signals of the suspended image sensor can be successfully sent out with 32 signal springs without incurring damage during wire-bonding packaging. The longest calculated traveling distance of the stabilizer is 25 µm which is sufficient to resolve the anti-shaking problem in a three-megapixel image sensor. Accordingly, the applied voltage for the 25 µm moving distance is 38 V. Moreover, the resonant frequency of the actuating device with the image sensor is 1.123 kHz.

Hydrogen Bond Networks and Hydrophobic Effects in the Amyloid β30-35 Chain in Water: A Molecular Dynamics Study.

PubMed

Jong, KwangHyok; Grisanti, Luca; Hassanali, Ali

2017-07-24

We have studied the conformational landscape of the C-terminal fragment of the amyloid protein Aβ 30-35 in water using well-tempered metadynamics simulations and found that it resembles an intrinsically disordered protein. The conformational fluctuations of the protein are facilitated by a collective reorganization of both protein and water hydrogen bond networks, combined with electrostatic interactions between termini as well as hydrophobic interactions of the side chains. The stabilization of hydrophobic interactions in one of the conformers involves a collective collapse of the side chains along with a squeeze-out of water sandwiched between them. The charged N- and C-termini play a critical role in stabilizing different types of protein conformations, including those involving contact-ion salt bridges as well as solvent-mediated interactions of the termini and the amide backbone. We have examined this by probing the distribution of directed water wires forming the hydrogen bond network enveloping the polypeptide. Water wires and their fluctuations form an integral part of structural signature of the protein conformation.

Hot wire anemometer measurements in the unheated air flow tests of the SRB nozzle-to-case joint

NASA Technical Reports Server (NTRS)

Ramachandran, N.

1988-01-01

Hot-Wire Anemometer measurements made in the Solid Rocket Booster (SRB) nozzle-to-case joint are discussed. The study was undertaken to glean additional information on the circumferential flow induced in the SRB nozzle joint and the effect of this flow on the insulation bonding flaws. The tests were conducted on a full-scale, 2-D representation of a 65-in long segment of the SRB nozzle joint, with unheated air as the working fluid. Both the flight Mach number and Reynolds number were matched simultaneously and different pressure gradients imposed along the joint face were investigated. Hot-wire anemometers were used to obtain velocity data for different joint gaps and debond configurations. The procedure adopted for hot-wire calibration and use is outlined and the results from the tests summarized.

Attachment of Free Filament Thermocouples for Temperature Measurements on Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Cuy, Michael D.; Wnuk, Stephen P.

1998-01-01

At the NASA Lewis Research Center, a new installation technique utilizing convoluted wire thermocouples (TC's) was developed and proven to produce very good adhesion on CMC's, even in a burner rig environment. Because of their unique convoluted design, such TC's of various types and sizes adhere to flat or curved CMC specimens with no sign of delamination, open circuits, or interactions-even after testing in a Mach 0.3 burner rig to 1200 C (2200 F) for several thermal cycles and at several hours at high temperatures. Large differences in thermal expansion between metal thermocouples and low-expansion materials, such as CMC's, normally generate large stresses in the wires. These stresses cause straight wires to detach, but convoluted wires that are bonded with strips of coating allow bending in the unbonded portion to relieve these expansion stresses.

Baseline UT Measurements for Armor Inspection

NASA Astrophysics Data System (ADS)

Margetan, Frank J.; Richter, Nate; Barnard, Dan; Hsu, David; Gray, Tim; Brasche, Lisa; Bruce Thompson, R.

2010-02-01

Some prototype armor panels are fabricated from several layers of dissimilar material bonded together. These may include ceramics, graphite composites, fiberglass composites and rubber. The ultrasonic properties of these layers influence inspections for armor defects. In this paper we describe measurements of ultrasonic velocity, attenuation, sound beam distortion and signal fluctuations for the individual layers comprising one armor prototype. We then discuss how knowledge of these properties can be used when choosing an optimum frequency for an ultrasonic pitch/catch immersion inspection. In our case an effective inspection frequency near 1.5 MHz affords: (1) adequate strength of through-transmitted signals in unflawed armor; (2) adequate lateral resolution for detecting small disbonds at interfaces; and (3) low levels of UT signal fluctuations due to the natural inhomogeneity of certain armor layers. The utility of this approach is demonstrated using armor panels containing artificial disbonds at selected interfaces.

Effects of intraoral aging on surface properties of coated nickel-titanium archwires.

PubMed

Rongo, Roberto; Ametrano, Gianluca; Gloria, Antonio; Spagnuolo, Gianrico; Galeotti, Angela; Paduano, Sergio; Valletta, Rosa; D'Antò, Vincenzo

2014-07-01

To evaluate the effects of intraoral aging on surface properties of esthetic and conventional nickel-titanium (NiTi) archwires. Five NiTi wires were considered for this study (Sentalloy, Sentalloy High Aesthetic, Superelastic Titanium Memory Wire, Esthetic Superelastic Titanium Memory Wire, and EverWhite). For each type of wire, four samples were analyzed as received and after 1 month of clinical use by an atomic force microscope (AFM) and a scanning electronic microscope (SEM). To evaluate sliding resistance, two stainless steel plates with three metallic or three monocrystalline brackets, bonded in passive configuration, were manufactured; four as-received and retrieved samples for every wire were pulled five times at 5 mm/min for 1 minute by means of an Instron 5566, recording the greatest friction value (N). Data were analyzed by one-way analysis of variance and by Student's t-test. After clinical use, surface roughness increased considerably. The SEM images showed homogeneity for the as-received control wires; however, after clinical use esthetic wires exhibited a heterogeneous surface with craters and bumps. The lowest levels of friction were observed with the as-received Superelastic Titanium Memory Wire on metallic brackets. When tested on ceramic brackets, all the wires exhibited an increase in friction (t-test; P < .05). Furthermore, all the wires, except Sentalloy, showed a statistically significant increase in friction between the as-received and retrieved groups (t-test; P < .05). Clinical use of the orthodontic wires increases their surface roughness and the level of friction.

Characteristics of the First Longitudinal-Fourth Bending Mode Linear Ultrasonic Motors

NASA Astrophysics Data System (ADS)

Park, Taegone; Kim, Beomjin; Kim, Myong-Ho; Uchino, Kenji

2002-11-01

Linear ultrasonic motors using a combination of the first longitudinal mode and the fourth bending mode were designed and fabricated. The driving characteristics of the motors, which were composed of a straight metal bar bonded with piezoelectric ceramic vibrators as a driving element, were measured. Unimorph and bimorph ceramic vibrators were attached on three kinds of metal bars for constructing the stators of the linear motors. As results, motors made with the bimorph ceramic vibrators had higher velocity than motors of the unimorph vibrators. As a metal bar for stator, magnesium alloy, which has lower elastic coefficient than aluminum alloy, was better for the motors.

Non-Destructive Evaluation of Kissing Bonds using Local Defect Resonance (LDR) Spectroscopy: A Simulation Study

NASA Astrophysics Data System (ADS)

Delrue, S.; Tabatabaeipour, M.; Hettler, J.; Van Den Abeele, K.

With the growing demand from industry to optimize and further develop existing Non-Destructive Testing & Evaluation (NDT&E) techniques or new methods to detect and characterize incipient damage with high sensitivity and increased quality, ample efforts have been devoted to better understand the typical behavior of kissing bonds, such as delaminations and cracks. Recently, it has been shown experimentally that the nonlinear ultrasonic response of kissing bonds could be enhanced by using Local Defect Resonance (LDR) spectroscopy. LDR spectroscopy is an efficient NDT technique that takes advantage of the characteristic fre- quencies of the defect (defect resonances) in order to provide maximum acoustic wave-defect interaction. In fact, for nonlinear methodologies, the ultrasonic excitation of the sample should occur at either multiples or integer ratios of the characteristic defect resonance frequencies, in order to obtain the highest signal-to-noise response in the nonlinear LDR spectroscopy. In this paper, the potential of using LDR spectroscopy for the detection, localization and characterization of kissing bonds is illustrated using a 3D simulation code for elastic wave propagation in materials containing closed but dynamically active cracks or delaminations. Using the model, we are able to define an appropriate method, based on the Scaling Subtraction Method (SSM), to determine the local defect resonance frequencies of a delamination in a composite plate and to illustrate an increase in defect nonlinearity due to LDR. The simulation results will help us to obtain a better understanding of the concept of LDR and to assist in the further design and testing of LDR spectroscopy for the detection, localization and characterization of kissing bonds.

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1972-01-01

Activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices are described. Topics investigated include: measurements of transistor delay time; application of the infrared response technique to the study of radiation-damaged, lithium-drifted silicon detectors; and identification of a condition that minimizes wire flexure and reduces the failure rate of wire bonds in transistors and integrated circuits under slow thermal cycling conditions. Supplementary data concerning staff, standards committee activities, technical services, and publications are included as appendixes.

Universal solar-cell terminal

NASA Technical Reports Server (NTRS)

Bashin, S.; Kelley, F. G.

1977-01-01

Terminal, which replaces stakes or lugs in conventional design with loop receptacles for wires from cell and harness, uses dissimilar bonding properties (metal-to-glass and/or ceramics) of iron-nickel-cobalt alloy in conjunction with standard termination.

Customized Hermetic Feedthrough Developed to Isolate Fluids

NASA Technical Reports Server (NTRS)

Meredith, Roger D.

1999-01-01

A common problem occurs when refrigerant fluids wick inside the insulation of thermocouple wires through a compressor's casing feedthrough and then leak into the adjacent disconnect box outside the casing. Leaking fluids create an unfavorable situation inside the disconnect box and may contaminate the fluids. To address this problem, NASA Lewis Research Center s Manufacturing Engineering Division developed a customized hermetic feedthrough for a bank of Worthington compressors. In these compressors, bearing temperatures are measured by internal thermocouples embedded in bearings located inside the compressor casings. The thermocouple wires need to be routed outside the casing and read at another location. These wires are short and are terminated to a disconnect strip inside the casing. The bearings operate at about 170 F, but because the casing is filled with R12 refrigerant oil, the casing has a maximum temperature of about 100 F. The operating conditions of these compressors permit the use of an epoxy that is compatible with the R12 fluid. The desired finished product is a stainless steel tube that has been filled solid with epoxy after thermocouple wires bonded and sealed by epoxy have been inserted through its length. Shrink tubing extends from both ends of the tube. The process that was developed to isolate the thermocouple wires from the R12 fluid follows. For this application, use an 8-in.-long piece of 0.500-in. 304 stainless steel tube with six pairs of 24-gauge stranded, PTFE-insulated (polytetrafluoroethylene) type "T" thermocouple wires for each feedthrough. Use shrink tubing to strain relief the insulated wires at their exit from the stainless steel tube. Cut the wire to length and identify the location of the stainless steel tube sleeve with masking tape. Then, remove the outer insulation from a 2-in. section of wire that will be inside the tube, and carefully strip to bare wire a 1-in. section in the middle of the section with the outer insulation removed. For an effective seal, the epoxy must penetrate between the strands when stranded conductors are used. Make the seal with epoxy bond on the bare wire. The bare wire must be encapsulated with a thin layer of the epoxy that leaves only a very low profile. These encapsulated wires must cure before the assembly can be continued. Then, inspect the cured wires for complete encapsulation before going to the next step. Insert the wires in the stainless steel tube and orient them so that the epoxied stripped sections are staggered within the tube; then, apply shrink tubing to one end of the cleaned wires, positioning it inside the edge of the tube. The small gaps between the wires on the other end will be used to inject the epoxy into the tube. Let the epoxy cure inside the tube, free of any voids. Then, continue to fill the tube until the entire 8-in. length is nearly filled, allowing room for the other strain-relieving shrink tubing. Since this first design, the process has been adjusted to fit many needs and situations. Customized feedthroughs have been assembled from various wire types, wire gauges, and/or stainless steel tube passages. The fittings selected to mount these feedthroughs allow their use in other areas, such as pressure or vacuum systems.

Proton transfer events in GFP.

PubMed

Di Donato, Mariangela; van Wilderen, Luuk J G W; Van Stokkum, Ivo H M; Stuart, Thomas Cohen; Kennis, John T M; Hellingwerf, Klaas J; van Grondelle, Rienk; Groot, Marie Louise

2011-09-28

Proton transfer is one of the most important elementary processes in biology. Green fluorescent protein (GFP) serves as an important model system to elucidate the mechanistic details of this reaction, because in GFP proton transfer can be induced by light absorption. Illumination initiates proton transfer through a 'proton-wire', formed by the chromophore (the proton donor), water molecule W22, Ser205 and Glu222 (the acceptor), on a picosecond time scale. To obtain a more refined view of this process, we have used a combined approach of time resolved mid-infrared spectroscopy and visible pump-dump-probe spectroscopy to resolve with atomic resolution how and how fast protons move through this wire. Our results indicate that absorption of light by GFP induces in 3 ps (10 ps in D(2)O) a shift of the equilibrium positions of all protons in the H-bonded network, leading to a partial protonation of Glu222 and to a so-called low barrier hydrogen bond (LBHB) for the chromophore's proton, giving rise to dual emission at 475 and 508 nm. This state is followed by a repositioning of the protons on the wire in 10 ps (80 ps in D(2)O), ultimately forming the fully deprotonated chromophore and protonated Glu222.

Tapered monocapillary-optics for point source applications

DOEpatents

Hirsch, Gregory

2000-01-01

A glass or metal wire is precisely etched to form the paraboloidal or ellipsoidal shape of the final desired capillary optic. This shape is created by carefully controlling the withdrawal speed of the wire from an etchant bath. In the case of a complete ellipsoidal capillary, the etching operation is performed twice in opposite directions on adjacent wire segments. The etched wire undergoes a subsequent operation to create an extremely smooth surface. This surface is coated with a layer of material which is selected to maximize the reflectivity of the radiation. This reflective surface may be a single layer for wideband reflectivity, or a multilayer coating for optimizing the reflectivity in a narrower wavelength interval. The coated wire is built up with a reinforcing layer, typically by a plating operation. The initial wire is removed by either an etching procedure or mechanical force. Prior to removing the wire, the capillary is typically bonded to a support substrate. One option for attaching the wire to the substrate produces a monolithic structure by essentially burying it under a layer of plating which covers both the wire and the substrate. The capillary optic is used for efficiently collecting and redirecting the divergent radiation from a source which could be the anode of an x-ray tube, a plasma source, the fluorescent radiation from an electron microprobe, or some other source of radiation.

Towards a Reduced-Wire Interface for CMUT-Based Intravascular Ultrasound Imaging Systems

PubMed Central

Lim, Jaemyung; Tekes, Coskun; Degertekin, F. Levent; Ghovanloo, Maysam

2016-01-01

Having intravascular ultrasound (IVUS) imaging capability on guide wires used in cardiovascular interventions may eliminate the need for separate IVUS catheters and expand the use of IVUS in a larger portion of the vasculature. High frequency capacitive micro machined ultrasonic transducer (CMUT) arrays should be integrated with interface electronics and placed on the guide wire for this purpose. Besides small size, this system-on-a-chip (SoC) front-end should connect to the back-end imaging system with a minimum number of wires to preserve the critical mechanical properties of the guide wire. We present a 40 MHz CMUT array interface SoC, which will eventually use only two wires for power delivery and transmits image data using a combination of analog-to-time conversion (ATC) and an impulse radio ultra-wideband (IR-UWB) wireless link. The proof-of-concept prototype ASIC consumes only 52.8 mW and occupies 4.07 mm2 in a 0.35-μm standard CMOS process. A rectifier and regulator power the rest of the SoC at 3.3 V from a 10 MHz power carrier that is supplied through a 2.4 m micro-coax cable with an overall efficiency of 49.1%. Echo signals from an 8-element CMUT array are amplified by a transimpedance amplifier (TIA) array and down-converted to baseband by quadrature sampling using a 40 MHz clock, derived from the power carrier. The ATC generates pulse-width-modulated (PWM) samples at 2 × 10 MS/s with 6 bit resolution, while the entire system achieved 5.1 ENOB. Preliminary images from the prototype system are presented, and alternative data transmission and possible future directions towards practical implementation are discussed. PMID:27662686

Towards a Reduced-Wire Interface for CMUT-Based Intravascular Ultrasound Imaging Systems.

PubMed

Lim, Jaemyung; Tekes, Coskun; Degertekin, F Levent; Ghovanloo, Maysam

2017-04-01

Having intravascular ultrasound (IVUS) imaging capability on guide wires used in cardiovascular interventions may eliminate the need for separate IVUS catheters and expand the use of IVUS in a larger portion of the vasculature. High frequency capacitive micro machined ultrasonic transducer (CMUT) arrays should be integrated with interface electronics and placed on the guide wire for this purpose. Besides small size, this system-on-a-chip (SoC) front-end should connect to the back-end imaging system with a minimum number of wires to preserve the critical mechanical properties of the guide wire. We present a 40 MHz CMUT array interface SoC, which will eventually use only two wires for power delivery and transmits image data using a combination of analog-to-time conversion (ATC) and an impulse radio ultra-wideband (IR-UWB) wireless link. The proof-of-concept prototype ASIC consumes only 52.8 mW and occupies 4.07 [Formula: see text] in a 0.35- [Formula: see text] standard CMOS process. A rectifier and regulator power the rest of the SoC at 3.3 V from a 10 MHz power carrier that is supplied through a 2.4 m micro-coax cable with an overall efficiency of 49.1%. Echo signals from an 8-element CMUT array are amplified by a transimpedance amplifier (TIA) array and down-converted to baseband by quadrature sampling using a 40 MHz clock, derived from the power carrier. The ATC generates pulse-width-modulated (PWM) samples at 2 × 10 MS/s with 6 bit resolution, while the entire system achieved 5.1 ENOB. Preliminary images from the prototype system are presented, and alternative data transmission and possible future directions towards practical implementation are discussed.

'There were more wires than him': the potential for wireless patient monitoring in neonatal intensive care.

PubMed

Bonner, Oliver; Beardsall, Kathryn; Crilly, Nathan; Lasenby, Joan

2017-02-01

The neonatal intensive care unit (NICU) can be one of the most stressful hospital environments. Alongside providing intensive clinical care, it is important that parents have the opportunity for regular physical contact with their babies because the neonatal period is critical for parent-child bonding. At present, monitoring technology in the NICU requires multiple wired sensors to track each baby's vital signs. This study describes the experiences that parents and nurses have with the current monitoring methods, and reports on their responses to the concept of a wireless monitoring system. Semistructured interviews were conducted with six parents, each of whom had babies on the unit, and seven nurses who cared for those babies. The interviews initially focused on the participants' experiences of the current wired system and then on their responses to the concept of a wireless system. The transcripts were analysed using a general inductive approach to identify relevant themes. Participants reported on physical and psychological barriers to parental care, the ways in which the current system obstructed the efficient delivery of clinical care and the perceived benefits and risks of a wireless system. The parents and nurses identified that the wires impeded baby-parent bonding; physically and psychologically. While a wireless system was viewed as potentially enabling greater interaction, staff and parents highlighted potential concerns, including the size, weight and battery life of any new device. The many wires required to safely monitor babies within the NICU creates a negative environment for parents at a critical developmental period, in terms of physical and psychological interactions. Nurses also experience challenges with the existing system, which could negatively impact the clinical care delivery. Developing a wireless system could overcome these barriers, but there remain challenges in designing a device suitable for this unique environment.

Fundamental study of microelectronic chip response under laser ultrasonic-interferometric inspection using C-scan method

NASA Astrophysics Data System (ADS)

Yang, Lei; Gong, Jie; Ume, I. Charles

2014-02-01

In modern surface mount packaging technologies, such as flip chips, chip scale packages, and ball grid arrays(BGA), chips are attached to the substrates/printed wiring board (PWB) using solder bump interconnections. The quality of solder bumps between the chips and the substrate/board is difficult to inspect. Laser ultrasonic-interferometric technique was proved to be a promising approach for solder bump inspection because of its noncontact and nondestructive characteristics. Different indicators extracted from received signals have been used to predict the potential defects, such as correlation coefficient, error ratio, frequency shifting, etc. However, the fundamental understanding of the chip behavior under laser ultrasonic inspection is still missing. Specifically, it is not sure whether the laser interferometer detected out-of-plane displacements were due to wave propagation or structural vibration when the chip was excited by pulsed laser. Plus, it is found that the received signals are chip dependent. Both challenges impede the interpretation of acquired signals. In this paper, a C-scan method was proposed to study the underlying phenomenon during laser ultrasonic inspection. The full chip was inspected. The response of the chip under laser excitation was visualized in a movie resulted from acquired signals. Specifically, a BGA chip was investigated to demonstrate the effectiveness of this method. By characterizing signals using discrete wavelet transform(DWT), both ultrasonic wave propagation and vibration were observed. Separation of them was successfully achieved using ideal band-pass filter and visualized in resultant movies, too. The observed ultrasonic waves were characterized and their respective speeds were measured by applying 2-D FFT. The C-scan method, combined with different digital signal processing techniques, was proved to be an very effective methodology to learn the behavior of chips under laser excitation. This general procedure can be applied to any unknown chip before inspection. A wealth of information can be provided by this learning procedure, which greatly benefits the interpretation of inspection signals afterwards.

Military Handbook. Grounding, Bonding, and Shielding for Electronic Equipments and Facilities. Volume 1. Basic Theory

DTIC Science & Technology

1987-12-29

when the air or gas stream contains particulate matter. b. Pulverized materials passing through chutes or pneumatic conveyors . c. Nonconductive power...Hanover NH, 1971, AD 722 221. 146.Oakley, R.J., "Surface Transfer Impedance and Cable Shielding Design ," Wire Journal, Vol 4, No. 3, March 1971, pp...including considerations of grounding, bonding, and shielding in all phases of design , construction, operation, and maintenance of electronic equipment

Design and Fabrication of an Implantable Cortical Semiconductor Integrated Circuit Electrode Array

DTIC Science & Technology

1990-12-01

25 Array Pads....................25 Polyimide ....................26 III. METHODOLOGY.........................27 Brain Chip Electronics...38 Ionic Permeation. .................. 38 Polyimide . ................... 38 Implantation. .................... 39 Wire Bonding...53 Pad Sensitivity ................. 53 Ionic Permeat:.on. .................. 54 Polyimide . ................... 54 Implantation

An evaluation of the electric arc spray and (HPPS) processes for the manufacturing of high power plasma spraying MCrAIY coatings

NASA Astrophysics Data System (ADS)

Sacriste, D.; Goubot, N.; Dhers, J.; Ducos, M.; Vardelle, A.

2001-06-01

The high power plasma torch (PlazJet) can be used to spray refractory ceramics with high spray rates and deposition efficiency. It can provide dense and hard coating with high bond strengths. When manufacturing thermal barrier coatings, the PlazJet gun is well adapted to spraying the ceramic top coat but not the MCrAIY materials that are used as bond coat. Arc spraying can compete with plasma spraying for metallic coatings since cored wires can be used to spray alloys and composites. In addition, the high production rate of arc spraying enables a significant decrease in coating cost. This paper discusses the performances of the PlazJet gun, and a twin-wire are spray system, and compares the properties and cost of MCrAIY coatings made with these two processes. For arc spraying, the use of air or nitrogen as atomizing gas is also investigated.

Composite metal foil and ceramic fabric materials

DOEpatents

Webb, B.J.; Antoniak, Z.I.; Prater, J.T.; DeSteese, J.G.

1992-03-24

The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed. 11 figs.

The UT 19-channel DC SQUID based neuromagnetometer.

PubMed

ter Brake, H J; Flokstra, J; Jaszczuk, W; Stammis, R; van Ancum, G K; Martinez, A; Rogalla, H

1991-01-01

A 19-channel DC SQUID based neuromagnetometer is under construction at the University of Twente (UT). Except for the cryostat all elements of the system are developed at the UT. It comprises 19 wire-wound first-order gradiometers in a hexagonal configuration. The gradiometers are connected to planar DC SQUIDs fabricated with a Nb/Al, AlO kappa/Nb technology. For this connection we developed a method to bond a Nb wire to a Nb thin-film. The SQUIDs are placed in compartmentalised Nb modules. Further, external feedback is incorporated in order to eliminate cross talk between the gradiometers. The electronics basically consist of a phase-locked loop operating with a modulation frequency of 100 kHz. Between SQUID and preamplifier a small transformer is used to limit the noise contribution of the preamplifier. In the paper the overall system is described, and special attention is paid to the SQUID module (bonding, compartments, external-feedback setup, output transformer).

Dopant activation mechanism of Bi wire-δ-doping into Si crystal, investigated with wavelength dispersive fluorescence x-ray absorption fine structure and density functional theory.

PubMed

Murata, Koichi; Kirkham, Christopher; Shimomura, Masaru; Nitta, Kiyofumi; Uruga, Tomoya; Terada, Yasuko; Nittoh, Koh-Ichi; Bowler, David R; Miki, Kazushi

2017-04-20

We successfully characterized the local structures of Bi atoms in a wire-δ-doped layer (1/8 ML) in a Si crystal, using wavelength dispersive fluorescence x-ray absorption fine structure at the beamline BL37XU, in SPring-8, with the help of density functional theory calculations. It was found that the burial of Bi nanolines on the Si(0 0 1) surface, via growth of Si capping layer at 400 °C by molecular beam epitaxy, reduced the Bi-Si bond length from [Formula: see text] to [Formula: see text] Å. We infer that following epitaxial growth the Bi-Bi dimers of the nanoline are broken, and the Bi atoms are located at substitutional sites within the Si crystal, leading to the shorter Bi-Si bond lengths.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, Steffen; Gerwert, Klaus, E-mail: gerwert@bph.rub.de; Department of Biophysics, Chinese Academy of Sciences, Max-Planck-Gesellschaft Partner Institute for Computational Biology, 320 Yue Yang Road, 200031 Shanghai

Proton conduction along protein-bound “water wires” is an essential feature in membrane proteins. Here, we analyze in detail a transient water wire, which conducts protons via a hydrophobic barrier within a membrane protein to create a proton gradient. It is formed only for a millisecond out of three water molecules distributed at inactive positions in a polar environment in the ground state. The movement into a hydrophobic environment causes characteristic shifts of the water bands reflecting their different chemical properties. These band shifts are identified by time-resolved Fourier Transform Infrared difference spectroscopy and analyzed by biomolecular Quantum Mechanical/Molecular Mechanical simulations.more » A non-hydrogen bonded (“dangling”) O–H stretching vibration band and a broad continuum absorbance caused by a combined vibration along the water wire are identified as characteristic marker bands of such water wires in a hydrophobic environment. The results provide a basic understanding of water wires in hydrophobic environments.« less

Motor for High Temperature Applications

NASA Technical Reports Server (NTRS)

Roopnarine (Inventor)

2013-01-01

A high temperature motor has a stator with poles formed by wire windings, and a rotor with magnetic poles on a rotor shaft positioned coaxially within the stator. The stator and rotor are built up from stacks of magnetic-alloy laminations. The stator windings are made of high temperature magnet wire insulated with a vitreous enamel film, and the wire windings are bonded together with ceramic binder. A thin-walled cylinder is positioned coaxially between the rotor and the stator to prevent debris from the stator windings from reaching the rotor. The stator windings are wound on wire spools made of ceramic, thereby avoiding need for mica insulation and epoxy/adhesive. The stator and rotor are encased in a stator housing with rear and front end caps, and rear and front bearings for the rotor shaft are mounted on external sides of the end caps to keep debris from the motor migrating into the bearings' races.

A one-pot gold seed-assisted synthesis of gold/platinum wire nanoassemblies and their enhanced electrocatalytic activity for the oxidation of oxalic acid

NASA Astrophysics Data System (ADS)

Bai, Juan; Fang, Chun-Long; Liu, Zong-Huai; Chen, Yu

2016-01-01

Three-dimensional (3D) noble metal nanoassemblies composed of one-dimensional (1D) nanowires have been attracting much interest due to the unique physical and chemical properties of 1D nanowires as well as the particular interconnected open-pore structure of 3D nanoassemblies. In this work, well-defined Au/Pt wire nanoassemblies were synthesized by using a facile NaBH4 reduction method in the presence of a branched form of polyethyleneimine (PEI). A study of the growth mechanism indicated the morphology of the final product to be highly related to the molecular structure of the polymeric amine. Also, the preferred Pt-on-Pt deposition contributed to the formation of the 1D Pt nanowires. The Au/Pt wire nanoassemblies were functionalized with PEI at the same time that these nanoassemblies were synthesized due to the strong N-Pt bond. The chemically functionalized Au/Pt wire nanoassemblies exhibited better electrocatalytic activity for the electro-oxidation of oxalic acid than did commercial Pt black.Three-dimensional (3D) noble metal nanoassemblies composed of one-dimensional (1D) nanowires have been attracting much interest due to the unique physical and chemical properties of 1D nanowires as well as the particular interconnected open-pore structure of 3D nanoassemblies. In this work, well-defined Au/Pt wire nanoassemblies were synthesized by using a facile NaBH4 reduction method in the presence of a branched form of polyethyleneimine (PEI). A study of the growth mechanism indicated the morphology of the final product to be highly related to the molecular structure of the polymeric amine. Also, the preferred Pt-on-Pt deposition contributed to the formation of the 1D Pt nanowires. The Au/Pt wire nanoassemblies were functionalized with PEI at the same time that these nanoassemblies were synthesized due to the strong N-Pt bond. The chemically functionalized Au/Pt wire nanoassemblies exhibited better electrocatalytic activity for the electro-oxidation of oxalic acid than did commercial Pt black. Electronic supplementary information (ESI) available: Experimental details and additional physical characterization. See DOI: 10.1039/c5nr08150e

Rapid ultrasound-induced transient-liquid-phase bonding of Al-50Si alloys with Zn interlayer in air for electrical packaging application.

PubMed

Wang, Qian; Chen, Xiaoguang; Zhu, Lin; Yan, Jiuchun; Lai, Zhiwei; Zhao, Pizhi; Bao, Juncheng; Lv, Guicai; You, Chen; Zhou, Xiaoyu; Zhang, Jian; Li, Yuntao

2017-01-01

Al-50Si alloys were joined by rapid ultrasound-induced transient-liquid-phase bonding method using Zn foil as interlayer at 390°C in air, below the melt point of interlayer. The fracture of oxide films along the edge of Si particles led to contact and inter-diffusion between aluminum substrate and Zn interlayer, and liquefied Zn-Al alloys were developed. The width of Zn-Al alloys gradually decreased with increasing the ultrasonic vibration time due to liquid squeezing out and accelerated diffusion. A stage of isothermal solidification existed, and the completion time was significantly shortened. In the liquid metal, the acoustic streaming and ultrasonic cavitations were induced. As the process developed, much more Si particles, which were particulate-reinforced phases of Al-50Si, gradually migrated to the center of soldering seam. The highest average shear strength of joints reached to 94.2MPa, and the fracture mainly occurred at the base metal. Copyright © 2016 Elsevier B.V. All rights reserved.

Ion-water wires in imidazolium-based ionic liquid/water solutions induce unique trends in density.

PubMed

Ghoshdastidar, Debostuti; Senapati, Sanjib

2016-03-28

Ionic liquid/water binary mixtures are rapidly gaining popularity as solvents for dissolution of cellulose, nucleobases, and other poorly water-soluble biomolecules. Hence, several studies have focused on measuring the thermophysical properties of these versatile mixtures. Among these, 1-ethyl-3-methylimidazolium ([emim]) cation-based ILs containing different anions exhibit unique density behaviours upon addition of water. While [emim][acetate]/water binary mixtures display an unusual rise in density with the addition of low-to-moderate amounts of water, those containing the [trifluoroacetate] ([Tfa]) anion display a sluggish decrease in density. The density of [emim][tetrafluoroborate] ([emim][BF4])/water mixtures, on the other hand, declines rapidly in close accordance with the experimental reports. Here, we unravel the structural basis underlying this unique density behavior of [emim]-based IL/water mixtures using all-atom molecular dynamics (MD) simulations. The results revealed that the distinct nature of anion-water hydrogen bonded networks in the three systems was a key in modulating the observed unique density behaviour. Vast expanses of uninterrupted anion-water-anion H-bonded stretches, denoted here as anion-water wires, induced significant structuring in [emim][Ac]/water mixtures that resulted in the density rise. Conversely, the presence of intermittent large water clusters disintegrated the anion-water wires in [emim][Tfa]/water and [emim][BF4]/water mixtures to cause a monotonic density decrease. The differential nanostructuring affected the dynamics of the solutions proportionately, with the H-bond making and breaking dynamics found to be greatly retarded in [emim][Ac]/water mixtures, while it exhibited a faster relaxation in the other two binary solutions.

Oxytocin and mutual communication in mother-infant bonding

PubMed Central

Nagasawa, Miho; Okabe, Shota; Mogi, Kazutaka; Kikusui, Takefumi

2012-01-01

Mother-infant bonding is universal to all mammalian species. In this review, we describe the manner in which reciprocal communication between the mother and infant leads to mother-infant bonding in rodents. In rats and mice, mother-infant bond formation is reinforced by various social stimuli, such as tactile stimuli and ultrasonic vocalizations (USVs) from the pups to the mother, and feeding and tactile stimulation from the mother to the pups. Some evidence suggests that mother and infant can develop a cross-modal sensory recognition of their counterpart during this bonding process. Neurochemically, oxytocin in the neural system plays a pivotal role in each side of the mother-infant bonding process, although the mechanisms underlying bond formation in the brains of infants has not yet been clarified. Impairment of mother-infant bonding, that is, deprivation of social stimuli from the mother, strongly influences offspring sociality, including maternal behavior toward their own offspring in their adulthood, implying a “non-genomic transmission of maternal environment,” even in rodents. The comparative understanding of cognitive functions between mother and infants, and the biological mechanisms involved in mother-infant bonding may help us understand psychiatric disorders associated with mother-infant relationships. PMID:22375116

Characterization and Modeling of Fine-Pitch Copper Ball Bonding on a Cu/Low- k Chip

NASA Astrophysics Data System (ADS)

Che, F. X.; Wai, L. C.; Zhang, Xiaowu; Chai, T. C.

2015-02-01

Cu ball bonding faces more challenges than Au ball bonding, for example, excessive deformation of the bond pad and damage of Cu/low- k structures, because of the much greater hardness of Cu free air balls. In this study, dynamic finite-element analysis (FEA) modeling with displacement control was developed to simulate the ball-bonding process. The three-dimensional (3D) FEA simulation results were confirmed by use of stress-measurement data, obtained by use of stress sensors built into the test chip. Stress comparison between two-dimensional (2D) and 3D FEA models showed the 2D plain strain model to be a reasonable and effective model for simulation of the ball-bonding process without loss of accuracy; it also saves computing resources. The 2D FEA model developed was then used in studies of a Cu/low- k chip to find ways of reducing Al bond pad deformation and stresses of low- k structures. The variables studied included Al pad properties, capillary geometry, bond pad design (Al pad thickness, Al pad coated with Ni layer), and the effect of ultrasonic bonding power.

Tungsten-reinforced tantalum

NASA Technical Reports Server (NTRS)

Bacigalupi, R. J.; Breitwieser, R.

1972-01-01

Method is described for producing tungsten-reinforced tantalum, a material possessing the high temperature strength of tungsten and room temperature ductility and weldability of tantalum. This material is produced by bonding together and overlaying structure of tungsten wires with chemical vapor deposited tantalum.

Interdigital pair bonding for high frequency (20-50 MHz) ultrasonic composite transducers.

PubMed

Liu, R; Harasiewicz, K A; Foster, F S

2001-01-01

Interdigital pair bonding is a novel methodology that enables the fabrication of high frequency piezoelectric composites with high volume fractions of the ceramic phase. This enhancement in ceramic volume fraction significantly reduces the dimensional scale of the epoxy phase and increases the related effective physical parameters of the composite, such as dielectric constant and the longitudinal sound velocity, which are major concerns in the development of high frequency piezoelectric composites. In this paper, a method called interdigital pair bonding (IPB) is used to prepare 1-3 piezoelectric composite with a pitch of 40 microns, a kerf of 4 microns, and a ceramic volume fraction of 81%. The composites prepared in this fashion exhibited a very pure thickness-mode resonance up to a frequency of 50 MHz. Unlike the 2-2 piezoelectric composites with the same ceramic and epoxy scales developed earlier, the anticipated lateral modes between 50 to 100 MHz were not observed in the current 1-3 composites. The mechanisms for the elimination of the lateral modes at high frequency are discussed. The effective electromechanical coupling coefficient of the composite was 0.72 at a frequency of 50 MHz. The composites showed a high longitudinal sound velocity of 4300 m/s and a high clamped dielectric constant of 1111 epsilon 0, which will benefit the development of high frequency ultrasonic transducers and especially high frequency transducer arrays for medical imaging.

Evaluation of removal forces of implant-supported zirconia copings depending on abutment geometry, luting agent and cleaning method during re-cementation

PubMed Central

Rödiger, Matthias; Rinke, Sven; Ehret-Kleinau, Fenja; Pohlmeyer, Franziska; Lange, Katharina; Bürgers, Ralf

2014-01-01

PURPOSE To evaluate the effects of different abutment geometries in combination with varying luting agents and the effectiveness of different cleaning methods (prior to re-cementation) regarding the retentiveness of zirconia copings on implants. MATERIALS AND METHODS Implants were embedded in resin blocks. Three groups of titanium abutments (pre-fabricated, height: 7.5 mm, taper: 5.7°; customized-long, height: 6.79 mm, taper: 4.8°; customized-short, height: 4.31 mm, taper: 4.8°) were used for luting of CAD/CAM-fabricated zirconia copings with a semi-permanent (Telio CS) and a provisional cement (TempBond NE). Retention forces were evaluated using a universal testing machine. Furthermore, the influence of cleaning methods (manually, manually in combination with ultrasonic bath or sandblasting) prior to re-cementation with a provisional cement (TempBond NE) was investigated with the pre-fabricated titanium abutments (height: 7.5 mm, taper: 5.7°) and SEM-analysis of inner surfaces of the copings was performed. Significant differences were determined via two-way ANOVA. RESULTS Significant interactions between abutment geometry and luting agent were observed. TempBond NE showed the highest level of retentiveness on customized-long abutments, but was negatively affected by other abutment geometries. In contrast, luting with Telio CS demonstrated consistent results irrespective of the varying abutment geometries. Manual cleaning in combination with an ultrasonic bath was the only cleaning method tested prior to re-cementation that revealed retentiveness levels not inferior to primary cementation. CONCLUSION No superiority for one of the two cements could be demonstrated because their influences on retentive strength are also depending on abutment geometry. Only manual cleaning in combination with an ultrasonic bath offers retentiveness levels after re-cementation comparable to those of primary luting. PMID:25006388

Correlation of Fiber Composite Tensile Strength with the Ultrasonic Stress Wave Factor

NASA Technical Reports Server (NTRS)

Vary, A.; Lark, R. F.

1978-01-01

An ultrasonic-acoustic technique was used to indicate the strength variations of tensile specimens of a graphite-epoxy composite. A stress wave factor was determined and its value was found to depend on variations of the fiber-resin bonding as well as fiber orientation. The fiber orientations studied were 0 deg (longitudinal), 10 deg (off-axis), 90 deg (transverse), 0 deg + or - 45 deg/0 deg symmetrical, and + or - 45 deg] symmetrical. The stress wave factor can indicate variations of the tensile and shear strengths of composite materials. The stress wave factor was also found to be sensitive to strength variations associated with microporosity and differences in fiber-resin ratio.

Ultrasonic studies of aluminium-substituted Bi(Pb)-2223 superconductors

NASA Astrophysics Data System (ADS)

Solunke, M. B.; Sharma, P. U.; Pandya, M. P.; Lakhani, V. K.; Modi, K. B.; Venugopal Reddy, P.; Shah, S. S.

2005-09-01

The compositional dependence of elastic properties of Al^{3+}-substitu- ted Bi(Pb)-2223 superconducting system with the general formula Bi_{1.7-x}Al_xPb_{0.3}Sr_2Ca_2- Cu_3O_y (x = 0.0, 0.1, 0.2 and 0.3) have been studied by means of ultrasonic pulse transmission (UPT) technique at 1 MHz (300 K). The elastic moduli of the specimens are computed and corrected to zero porosity. The observed variation of elastic constants with aluminium substitution has been explained on the basis of the strength of interatomic bonding. The applicability of heterogeneous metal mixture rule for estimating elastic constants and transition temperature has been tested.

Measurement of the degree of cure in epoxies with ultrasonic velocity

NASA Technical Reports Server (NTRS)

Winfree, W. P.; Parker, F. R.

1986-01-01

The use of ultrasonic longitudinal velocity values to measure the degree of cure (defined for an epoxide system as the concentration of epoxide/amine bonds divided by the initial epoxide concentration) in epoxy resins is investigated. The experimental setup used to measure the changes in longitudinal velocity with time is described, together with the technique used to calculate the degree of cure from the acoustic data, using the principle of additive module. Measurements were done with diglycidyl ether of bisphenol A epoxy resin cured with an amine adduct agent. Good qualitative agreement was shown between the time dependence of the acoustically measured degree of cure and the predicted rate of reaction.

Decontamination of blood soaked electronic devices using ultrasonic technology.

PubMed

Dudeck, Kimberly C; Brennan, Tamara C; Embury, Daniel J

2012-01-10

With advancements in technology allowing for the miniaturization of consumer electronics, criminal investigations of all types frequently involve the forensic examination of electronic devices, such as cellular telephones, smartphones, and portable flash memory; in some extreme, violent cases, these devices are found covered in blood. Due to the complexity of such devices, standard operating procedures for the complete removal of blood had not previously been established by the Royal Canadian Mounted Police prior to this study. The electronics industry has adopted the use of the ultrasonic cleaner for sanitizing printed circuit boards (PCBs) by removing residues and contaminants. High frequency sound waves created by the machine penetrate and remove dirt and residues; however, early research during the 1950s recorded these sound waves breaking the internal bonds of integrated circuit chips. Experimentation with modern ultrasonic technology was used to determine if internal components were damaged, as well as if ultrasonic cleaning was the most suitable method for the removal of dried and liquid blood from a PCB. Several disinfectant solutions were compared against the 0.5% Triton(®) X-100 detergent solution in the ultrasonic cleaner, including: 10% sodium hypochlorite bleach, 85% isopropyl alcohol, and Conflikt(®) disinfectant spray. The results not only demonstrated that the ultrasonic cleaner did not damage the vital memory chip on the PCB, but also, with the assistance of Conflikt(®), was able to remove all traces of blood as indicated by Hemastix(®) reagent strips. Of five methods experimented with, two cycles of ultrasonic cleaning followed by sanitization with Conflikt(®) proved to be the only procedure capable of removing all traces of blood, as confirmed with both Hemastix(®) reagent strips and the hemochromogen test. Crown Copyright © 2011. Published by Elsevier Ireland Ltd. All rights reserved.

Control and Measurement of an Xmon with the Quantum Socket

NASA Astrophysics Data System (ADS)

McConkey, T. G.; Bejanin, J. H.; Earnest, C. T.; McRae, C. R. H.; Rinehart, J. R.; Weides, M.; Mariantoni, M.

The implementation of superconducting quantum processors is rapidly reaching scalability limitations. Extensible electronics and wiring solutions for superconducting quantum bits (qubits) are among the most imminent issues to be tackled. The necessity to substitute planar electrical interconnects (e.g., wire bonds) with three-dimensional wires is emerging as a fundamental pillar towards scalability. In a previous work, we have shown that three-dimensional wires housed in a suitable package, named the quantum socket, can be utilized to measure high-quality superconducting resonators. In this work, we set out to test the quantum socket with actual superconducting qubits to verify its suitability as a wiring solution in the development of an extensible quantum computing architecture. To this end, we have designed and fabricated a series of Xmon qubits. The qubits range in frequency from about 6 to 7 GHz with anharmonicity of 200 MHz and can be tuned by means of Z pulses. Controlling tunable Xmons will allow us to verify whether the three-dimensional wires contact resistance is low enough for qubit operation. Qubit T1 and T2 times and single qubit gate fidelities are compared against current standards in the field.

PROCESSING OF HIGH-PERFORMANCE Nb{sub 3}Sn WIRES THROUGH A NEW DIFFUSION REACTION USING Sn BASED ALLOYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tachikawa, K.; Sasaki, H.; Yamaguchi, M.

Tightly consolidated Sn-Ta and Sn-B based alloys have been prepared by the reaction among constituent metal powders at 750-775 deg. C. Sn-Ta and Sn-B based alloys exhibit quite similar microstructures. A small amount of Ti addition seems to improve the bonding between Ta or B particles and Sn matrix. Nb{sub 3}Sn wires have been fabricated by the Jelly Roll (JR) and Multi-rod (MR) process using Sn based alloy sheet and rod, respectively. Thick Nb{sub 3}Sn layers with nearly stoichiometric A15 composition are synthesized through a new diffusion mechanism between Nb and Sn based alloy. B{sub c2}(4.2 K)'s of 26.9 Tmore » (mid) and 26.5 T (mid) have been obtained in the JR and MR processed wires, respectively, using Sn-Ta based alloy. These wires exhibit enough non-Cu J{sub c} to be used above 20 T and 4.2 K. T{sub c} of JR wires using Sn-B based sheet is 18.14 K (offset) which is slightly higher than that of wires using Sn-Ta based sheet.« less

Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method

NASA Astrophysics Data System (ADS)

Gopi, D.; Indira, J.; Kavitha, L.; Sekar, M.; Mudali, U. Kamachi

Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology.

Evaluation of composite adhesive bonds using digital image correlation

NASA Astrophysics Data System (ADS)

Shrestha, Shashi Shekhar

Advanced composite materials are widely used for many structural applications in the aerospace/aircraft industries today. Joining of composite structures using adhesive bonding offers several advantages over traditional fastening methods. However, this technique is not yet employed for fastening the primary structures of aircrafts or space vehicles. There are several reasons for this: There are not any reliable non-destructive evaluation (NDE) methods that can quantify the strength of the bonds, and there are no certifications of quality assurance for inspecting the bond quality. Therefore, there is a significant need for an effective, reliable, easy to use NDE method for the analysis of composite adhesive joints. This research aimed to investigate an adhesively bonded composite-aluminum joints of variable bond strength using digital image correlation (DIC). There are many future possibilities in continuing this research work. As the application of composite materials and adhesive bond are increasing rapidly, the reliability of the composite structures using adhesive bond should quantified. Hence a lot of similar research using various adhesive bonds and materials can be conducted for characterizing the behavior of adhesive bond. The results obtained from this research will set the foundation for the development of ultrasonic DIC as a nondestructive approach for the evaluation of adhesive bond line.

Through-Metal-Wall Power Delivery and Data Transmission for Enclosed Sensors: A Review

PubMed Central

Yang, Ding-Xin; Hu, Zheng; Zhao, Hong; Hu, Hai-Feng; Sun, Yun-Zhe; Hou, Bao-Jian

2015-01-01

The aim of this review was to assess the current viable technologies for wireless power delivery and data transmission through metal barriers. Using such technologies sensors enclosed in hermetical metal containers can be powered and communicate through exterior power sources without penetration of the metal wall for wire feed-throughs. In this review, we first discuss the significant and essential requirements for through-metal-wall power delivery and data transmission and then we: (1) describe three electromagnetic coupling based techniques reported in the literature, which include inductive coupling, capacitive coupling, and magnetic resonance coupling; (2) present a detailed review of wireless ultrasonic through-metal-wall power delivery and/or data transmission methods; (3) compare various ultrasonic through-metal-wall systems in modeling, transducer configuration and communication mode with sensors; (4) summarize the characteristics of electromagnetic-based and ultrasound-based systems, evaluate the challenges and development trends. We conclude that electromagnetic coupling methods are suitable for through thin non-ferromagnetic metal wall power delivery and data transmission at a relatively low data rate; piezoelectric transducer-based ultrasonic systems are particularly advantageous in achieving high power transfer efficiency and high data rates; the combination of more than one single technique may provide a more practical and reliable solution for long term operation. PMID:26694392

Development of Integrated Preamplifier for High-Frequency Ultrasonic Transducers and Low-Power Handheld Receiver

PubMed Central

Choi, Hojong; Li, Xiang; Lau, Sien-Ting; Hu, ChangHong; Zhou, Qifa; Shung, K. Kirk

2012-01-01

This paper describes the design of a front-end circuit consisting of an integrated preamplifier with a Sallen-Key Butterworth filter for very-high-frequency ultrasonic transducers and a low-power handheld receiver. This preamplifier was fabricated using a 0.18-μm 7WL SiGe bi-polar complementary metal oxide semiconductor (BiCMOS) process. The Sallen-Key filter is used to increase the voltage gain of the front-end circuit for high-frequency transducers which are generally low in sensitivity. The measured peak voltage gain of the frontend circuits for the BiCMOS preamplifier with the Sallen-Key filter was 41.28 dB at 100 MHz with a −6-dB bandwidth of 91%, and the dc power consumption of the BiCMOS preamplifier was 49.53 mW. The peak voltage gain of the front-end circuits for the CMOS preamplifier with the Sallen-Key filter was 39.52 dB at 100 MHz with a −6-dB bandwidth of 108%, and the dc power consumption of the CMOS preamplifier was 43.57 mW. Pulse-echo responses and wire phantom images with a single-element ultrasonic transducer have been acquired to demonstrate the performance of the front-end circuit. PMID:23443700

Dynamic breaking of a single gold bond

NASA Astrophysics Data System (ADS)

Pobelov, Ilya V.; Lauritzen, Kasper Primdal; Yoshida, Koji; Jensen, Anders; Mészáros, Gábor; Jacobsen, Karsten W.; Strange, Mikkel; Wandlowski, Thomas; Solomon, Gemma C.

2017-07-01

While one might assume that the force to break a chemical bond gives a measure of the bond strength, this intuition is misleading. If the force is loaded slowly, thermal fluctuations may break the bond before it is maximally stretched, and the breaking force will be less than the bond can sustain. Conversely, if the force is loaded rapidly it is more likely that the maximum breaking force is measured. Paradoxically, no clear differences in breaking force were observed in experiments on gold nanowires, despite being conducted under very different conditions. Here we explore the breaking behaviour of a single Au-Au bond and show that the breaking force is dependent on the loading rate. We probe the temperature and structural dependencies of breaking and suggest that the paradox can be explained by fast breaking of atomic wires and slow breaking of point contacts giving very similar breaking forces.

Intraocular lens fabrication

DOEpatents

Salazar, M.A.; Foreman, L.R.

1997-07-08

This invention describes a method for fabricating an intraocular lens made from clear Teflon{trademark}, Mylar{trademark}, or other thermoplastic material having a thickness of about 0.025 millimeters. These plastic materials are thermoformable and biocompatable with the human eye. The two shaped lenses are bonded together with a variety of procedures which may include thermosetting and solvent based adhesives, laser and impulse welding, and ultrasonic bonding. The fill tube, which is used to inject a refractive filling material is formed with the lens so as not to damage the lens shape. A hypodermic tube may be included inside the fill tube. 13 figs.

Intraocular lens fabrication

DOEpatents

Salazar, Mike A.; Foreman, Larry R.

1997-01-01

This invention describes a method for fabricating an intraocular lens made rom clear Teflon.TM., Mylar.TM., or other thermoplastic material having a thickness of about 0.025 millimeters. These plastic materials are thermoformable and biocompatable with the human eye. The two shaped lenses are bonded together with a variety of procedures which may include thermosetting and solvent based adhesives, laser and impulse welding, and ultrasonic bonding. The fill tube, which is used to inject a refractive filling material is formed with the lens so as not to damage the lens shape. A hypodermic tube may be included inside the fill tube.

Nylon screws make inexpensive coil forms

NASA Technical Reports Server (NTRS)

Aucoin, G.; Rosenthal, C.

1978-01-01

Standard nylon screws act as coil form copper wire laid down in spiral thread. Completed coil may be bonded to printed-circuit board. However, it is impossible to tune coil by adjusting spacing between windings, technique sometimes used with air-core coils.

The Quantum Socket: Wiring for Superconducting Qubits - Part 2

NASA Astrophysics Data System (ADS)

Bejanin, J. H.; McConkey, T. G.; Rinehart, J. R.; Bateman, J. D.; Earnest, C. T.; McRae, C. H.; Rohanizadegan, Y.; Shiri, D.; Mariantoni, M.; Penava, B.; Breul, P.; Royak, S.; Zapatka, M.; Fowler, A. G.

Quantum computing research has reached a level of maturity where quantum error correction (QEC) codes can be executed on linear arrays of superconducting quantum bits (qubits). A truly scalable quantum computing architecture, however, based on practical QEC algorithms, requires nearest neighbor interaction between qubits on a two-dimensional array. Such an arrangement is not possible with techniques that rely on wire bonding. To address this issue, we have developed the quantum socket, a device based on three-dimensional wires that enables the control of superconducting qubits on a two-dimensional grid. In this talk, we present experimental results characterizing this type of wiring. We will show that the quantum socket performs exceptionally well for the transmission and reflection of microwave signals up to 10 GHz, while minimizing crosstalk between adjacent wires. Under realistic conditions, we measured an S21 of -5 dB at 6 GHz and an average crosstalk of -60 dB. We also describe time domain reflectometry results and arbitrary pulse transmission tests, showing that the quantum socket can be used to control superconducting qubits.

Improvisation of mechanical and electrical properties of Cu by reinforcing MWCNT using modified electro-co-deposition process

NASA Astrophysics Data System (ADS)

Belgamwar, Sachin U.; Sharma, N. N.

2018-04-01

Multi-walled Carbon nanotubes–copper (MWCNT/Cu) composite powders with variable MWCNT content were synthesized by modified electro-co-deposition method. The electro-co-deposited MWCNT/Cu powders were consolidated by conventional compaction and sintering process. The consolidated products were then hot rolled and cold drawn to fine wires. The MWCNT/Cu composite wire samples were characterized for electrical and mechanical properties. We have been able to achieve an increase of around 8% in electrical conductivity of the form wires repeatedly. It has been observed that there was gradual improvement in the properties with reinforcement of MWCNT in the copper matrix. The betterment of electrical property has been achieved with simultaneous improvement in mechanical properties of the wire. The yield strength of MWCNT/Cu composite wire was found to be four times and the tensile strength two times greater than that of pure copper. The improved properties are attributed to the proper distribution of MWCNTs in the copper matrix and excellent interfacial bonding between MWCNT and composite copper fabricated by the modified method.

Recent developments in wireless recording from the nervous system with ultrasonic neural dust (Conference Presentation)

NASA Astrophysics Data System (ADS)

Maharbiz, Michel M.

2017-05-01

The emerging field of bioelectronic medicine seeks methods for deciphering and modulating electrophysiological activity in the body to attain therapeutic effects at target organs. Current approaches to interfacing with peripheral nerves and muscles rely heavily on wires, creating problems for chronic use, while emerging wireless approaches lack the size scalability necessary to interrogate small-diameter nerves. Furthermore, conventional electrode-based technologies lack the capability to record from nerves with high spatial resolution or to record independently from many discrete sites within a nerve bundle. We recently demonstrated (Seo et al., arXiV, 2013; Seo et al., Neuron, 2016) "neural dust," a wireless and scalable ultrasonic backscatter system for powering and communicating with implanted bioelectronics. There, we showed that ultrasound is effective at delivering power to mm-scale devices in tissue; likewise, passive, battery-less communication using backscatter enabled high-fidelity transmission of electromyogram (EMG) and electroneurogram (ENG) signals from anesthetized rats. In this talk, I will review recent developments from my group and collaborators in this area.

Totally Implantable Wireless Ultrasonic Doppler Blood Flowmeters: Toward Accurate Miniaturized Chronic Monitors.

PubMed

Rothfuss, Michael A; Unadkat, Jignesh V; Gimbel, Michael L; Mickle, Marlin H; Sejdić, Ervin

2017-03-01

Totally implantable wireless ultrasonic blood flowmeters provide direct-access chronic vessel monitoring in hard-to-reach places without using wired bedside monitors or imaging equipment. Although wireless implantable Doppler devices are accurate for most applications, device size and implant lifetime remain vastly underdeveloped. We review past and current approaches to miniaturization and implant lifetime extension for wireless implantable Doppler devices and propose approaches to reduce device size and maximize implant lifetime for the next generation of devices. Additionally, we review current and past approaches to accurate blood flow measurements. This review points toward relying on increased levels of monolithic customization and integration to reduce size. Meanwhile, recommendations to maximize implant lifetime should include alternative sources of power, such as transcutaneous wireless power, that stand to extend lifetime indefinitely. Coupling together the results will pave the way for ultra-miniaturized totally implantable wireless blood flow monitors for truly chronic implantation. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Hermetic edge sealing of photovoltaic modules

NASA Astrophysics Data System (ADS)

Nowlan, M. J.

1983-07-01

The feasibility of using an electrostatic bonding (ESB) and ultrasonic welding process to produce hermetic edge seals on terrestrial solar cell modules was investigated. The fabrication sequence is to attach an aluminum foil "gasket' to the perimeter of a glass sheet. A cell circuit is next encapsulated inside the gasket, and its aluminum foil back cover is seam welded ultrasonically to the gasket. An ESB process for sealing aluminum to glass was developed in an ambient air atmosphere, which eliminates the requirement for a vacuum or pressure vessel. An ultrasonic seam welding process was also developed which did not degrade the quality of the ESB seal. Good quality welds with minimal deformation were produced. The effectiveness of the above described sealing techniques was tested by constructing 400 sq cm (8 x 8 s64 sq in) sample modules, and then subjecting them to nondestructive fine and gross leak tests. The gross leak tests identified several different causes of leaks which were then eliminated by modifying the assembly process.

Hermetic edge sealing of photovoltaic modules

NASA Technical Reports Server (NTRS)

Nowlan, M. J.

1983-01-01

The feasibility of using an electrostatic bonding (ESB) and ultrasonic welding process to produce hermetic edge seals on terrestrial solar cell modules was investigated. The fabrication sequence is to attach an aluminum foil "gasket' to the perimeter of a glass sheet. A cell circuit is next encapsulated inside the gasket, and its aluminum foil back cover is seam welded ultrasonically to the gasket. An ESB process for sealing aluminum to glass was developed in an ambient air atmosphere, which eliminates the requirement for a vacuum or pressure vessel. An ultrasonic seam welding process was also developed which did not degrade the quality of the ESB seal. Good quality welds with minimal deformation were produced. The effectiveness of the above described sealing techniques was tested by constructing 400 sq cm (8 x 8 s64 sq in) sample modules, and then subjecting them to nondestructive fine and gross leak tests. The gross leak tests identified several different causes of leaks which were then eliminated by modifying the assembly process.

Ultrasonic Characterization of Aerospace Composites

NASA Technical Reports Server (NTRS)

Leckey, Cara; Johnston, Patrick; Haldren, Harold; Perey, Daniel

2015-01-01

Composite materials have seen an increased use in aerospace in recent years and it is expected that this trend will continue due to the benefits of reduced weight, increased strength, and other factors. Ongoing work at NASA involves the investigation of the large-scale use of composites for spacecraft structures (SLS components, Orion Composite Crew Module, etc). NASA is also involved in work to enable the use of composites in advanced aircraft structures through the Advanced Composites Project (ACP). In both areas (space and aeronautics) there is a need for new nondestructive evaluation and materials characterization techniques that are appropriate for characterizing composite materials. This paper will present an overview of NASA's needs for characterizing aerospace composites, including a description of planned and ongoing work under ACP for the detection of composite defects such as fiber waviness, reduced bond strength, delamination damage, and microcracking. The research approaches include investigation of angle array, guided wave, and phase sensitive ultrasonic methods. The use of ultrasonic simulation tools for optimizing and developing methods will also be discussed.

Extreme temperature packaging: challenges and opportunities

NASA Astrophysics Data System (ADS)

Johnson, R. Wayne

2016-05-01

Consumer electronics account for the majority of electronics manufactured today. Given the temperature limits of humans, consumer electronics are typically rated for operation from -40°C to +85°C. Military applications extend the range to -65°C to +125°C while underhood automotive electronics may see +150°C. With the proliferation of the Internet of Things (IoT), the goal of instrumenting (sensing, computation, transmission) to improve safety and performance in high temperature environments such as geothermal wells, nuclear reactors, combustion chambers, industrial processes, etc. requires sensors, electronics and packaging compatible with these environments. Advances in wide bandgap semiconductors (SiC and GaN) allow the fabrication of high temperature compatible sensors and electronics. Integration and packaging of these devices is required for implementation into actual applications. The basic elements of packaging are die attach, electrical interconnection and the package or housing. Consumer electronics typically use conductive adhesives or low melting point solders for die attach, wire bonds or low melting solder for electrical interconnection and epoxy for the package. These materials melt or decompose in high temperature environments. This paper examines materials and processes for high temperature packaging including liquid transient phase and sintered nanoparticle die attach, high melting point wires for wire bonding and metal and ceramic packages. The limitations of currently available solutions will also be discussed.

Bonded composite to metal scarf joint performance in an aircraft landing gear drag strut. [for Boeing 747 aircraft

NASA Technical Reports Server (NTRS)

Howell, W. E.

1974-01-01

The structural performance of a boron-epoxy reinforced titanium drag strut, which contains a bonded scarf joint and was designed to the criteria of the Boeing 747 transport, was evaluated. An experimental and analytical investigation was conducted. The strut was exposed to two lifetimes of spectrum loading and was statically loaded to the tensile and compressive design ultimate loads. Throughout the test program no evidence of any damage in the drag strut was detected by strain gage measurements, ultrasonic inspection, or visual observation. An analytical study of the bonded joint was made using the NASA structural analysis computer program NASTRAN. A comparison of the strains predicted by the NASTRAN computer program with the experimentally determined values shows excellent agreement. The NASTRAN computer program is a viable tool for studying, in detail, the stresses and strains induced in a bonded joint.

Tunable smart digital structure (SDS) to modularly assemble soft actuators with layered adhesive bonding

NASA Astrophysics Data System (ADS)

Jin, Hu; Dong, Erbao; Xu, Min; Xia, Qirong; Liu, Shuai; Li, Weihua; Yang, Jie

2018-01-01

Many shape memory alloy (SMA)-based soft actuators have specific composite structures and manufacture processes, and are therefore unique. However, these exclusive characteristics limit their capabilities and applications, so in this article a soft and smart digital structure (SDS) is proposed that acts like a modular unit to assemble soft actuators by a layered adhesive bonding process. The SDS is a fully soft structure that encapsulates a digital skeleton consisting of four groups of parallel and independently actuated SMA wires capable of outputting a four-channel tunable force. The layered adhesive bonding process modularly bonds several SDSs with an elastic backbone to fabricate a layered soft actuator where the elastic backbone is used to recover the SDSs in a cooling process using the SMA wires. Two kinds of SDS-based soft actuators were modularly assembled, an actuator, SDS-I, with a two-dimensional reciprocal motion, and an actuator, SDS-II, capable of bi-directional reciprocal motion. The thermodynamics and phase transformation modeling of the SDS-based actuator were analyzed. Several extensional soft actuators were also assembled by bonding the SDS with an anomalous elastic backbone or modularly assembling the SDS-Is and SDS-IIs. These modularly assembled soft actuators delivered more output channels and a complicated motion, e.g., an actinomorphic soft actuator with four SDS-Is jumps in a series of hierarchical heights and directional movement by tuning the input channels of the SDSs. This result showed that the SDS can modularly assemble multifarious soft actuators with diverse capabilities, steerability and tunable outputs.

Cathodic Corrosion of a Bulk Wire to Nonaggregated Functional Nanocrystals and Nanoalloys

PubMed Central

2018-01-01

A key enabling step in leveraging the properties of nanoparticles (NPs) is to explore new, simple, controllable, and scalable nanotechnologies for their syntheses. Among “wet” methods, cathodic corrosion has been used to synthesize catalytic aggregates with some control over their size and preferential faceting. Here, we report on a modification of the cathodic corrosion method for producing a range of nonaggregated nanocrystals (Pt, Pd, Au, Ag, Cu, Rh, Ir, and Ni) and nanoalloys (Pt50Au50, Pd50Au50, and AgxAu100–x) with potential for scaling up the production rate. The method employs poly(vinylpyrrolidone) (PVP) as a stabilizer in an electrolyte solution containing nonreducible cations (Na+, Ca2+), and cathodic corrosion of the corresponding wires takes place in the electrolyte under ultrasonication. The ultrasonication not only promotes particle–PVP interactions (enhancing NP dispersion and diluting locally high NP concentration) but also increases the production rate by a factor of ca. 5. Further increase in the production rate can be achieved through parallelization of electrodes to construct comb electrodes. With respect to applications, carbon-supported Pt NPs prepared by the new method exhibit catalytic activity and durability for methanol oxidation comparable or better than the commercial benchmark catalyst. A variety of AgxAu100–x nanoalloys are characterized by ultraviolet–visible absorption spectroscopy and high-resolution transmission electron microscopy. The protocol for NP synthesis by cathodic corrosion should be a step toward its further use in academic research as well as in its practical upscaling. PMID:29446912

Evaluation of multiple-channel OFDM based airborne ultrasonic communications.

PubMed

Jiang, Wentao; Wright, William M D

2016-09-01

Orthogonal frequency division multiplexing (OFDM) modulation has been extensively used in both wired and wireless communication systems. The use of OFDM technology allows very high spectral efficiency data transmission without using complex equalizers to correct the effect of a frequency-selective channel. This work investigated OFDM methods in an airborne ultrasonic communication system, using commercially available capacitive ultrasonic transducers operating at 50kHz to transmit information through the air. Conventional modulation schemes such as binary phase shift keying (BPSK) and quadrature amplitude modulation (QAM) were used to modulate sub-carrier signals, and the performances were evaluated in an indoor laboratory environment. Line-of-sight (LOS) transmission range up to 11m with no measurable errors was achieved using BPSK at a data rate of 45kb/s and a spectral efficiency of 1b/s/Hz. By implementing a higher order modulation scheme (16-QAM), the system data transfer rate was increased to 180kb/s with a spectral efficiency of 4b/s/Hz at attainable transmission distances up to 6m. Diffraction effects were incorporated into a model of the ultrasonic channel that also accounted for beam spread and attenuation in air. The simulations were a good match to the measured signals and non-LOS signals could be demodulated successfully. The effects of multipath interference were also studied in this work. By adding cyclic prefix (CP) to the OFDM symbols, the bit error rate (BER) performance was significantly improved in a multipath environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Wiring up pre-characterized single-photon emitters by laser lithography

NASA Astrophysics Data System (ADS)

Shi, Q.; Sontheimer, B.; Nikolay, N.; Schell, A. W.; Fischer, J.; Naber, A.; Benson, O.; Wegener, M.

2016-08-01

Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time.

Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits

DTIC Science & Technology

2016-01-20

Figure 7 4×4 GMAPD array wire bonded to CMOS timing circuits Figure 8 Low‐fill‐factor APD design used in lidar sensors The APD doping...epitaxial growth and the pixels are isolated by mesa etch. 128×32 lidar image sensors were built by bump bonding the APD arrays to a CMOS timing...passive image sensor with this large a format based on hybridization of a GMAPD array to a CMOS readout. Fig. 14 shows one of the first images taken

Electroless epitaxial etching for semiconductor applications

DOEpatents

McCarthy, Anthony M.

2002-01-01

A method for fabricating thin-film single-crystal silicon on insulator substrates using electroless etching for achieving efficient etch stopping on epitaxial silicon substrates. Microelectric circuits and devices are prepared on epitaxial silicon wafers in a standard fabrication facility. The wafers are bonded to a holding substrate. The silicon bulk is removed using electroless etching leaving the circuit contained within the epitaxial layer remaining on the holding substrate. A photolithographic operation is then performed to define streets and wire bond pad areas for electrical access to the circuit.

Chip-to-chip interconnects based on 3D stacking of optoelectrical dies on Si

NASA Astrophysics Data System (ADS)

Duan, P.; Raz, O.; Smalbrugge, B. E.; Duis, J.; Dorren, H. J. S.

2012-01-01

We demonstrate a new approach to increase the optical interconnection bandwidth density by stacking the opto-electrical dies directly on the CMOS driver. The suggested implementation is aiming to provide a wafer scale process which will make the use of wire bonding redundant and will allow for impedance matched metallic wiring between the electronic driving circuit and its opto-electronic counter part. We suggest the use of a thick photoresist ramp between CMOS driver and opto-electrical dies surface as the bridge for supporting co-plannar waveguides (CPW) electrically plated with lithographic accuracy. In this way all three dimensions of the interconnecting metal layer, width, length and thickness can be completely controlled. In this 1st demonstration all processing is done on commercially available devices and products, and is compatible with CMOS processing technology. To test the applicability of CPW instead of wire bonds for interconnecting the CMOS circuit and opto-electronic chips, we have made test samples and tested their performance at speeds up to 10 Gbps. In this demonstration, a silicon substrate was used on which we evaporated gold co-planar waveguides (CPW) to mimic a wire on the driver. An optical link consisting of a VCSEL chip and a photodiode chip has been assembled and fully characterized using optical coupling into and out of a multimode fiber (MMF). A 10 Gb/s 27-1 NRZ PRBS signal transmitted from one chip to another chip was detected error free. A 4 dB receiver sensitivity penalty is measured for the integrated device compared to a commercial link.

"Grinding" cavities in polyurethane foam

NASA Technical Reports Server (NTRS)

Brower, J. R.; Davey, R. E.; Dixon, W. F.; Robb, P. H.; Zebus, P. P.

1980-01-01

Grinding tool installed on conventional milling machine cuts precise cavities in foam blocks. Method is well suited for prototype or midsize production runs and can be adapted to computer control for mass production. Method saves time and materials compared to bonding or hot wire techniques.

Sandblasting and silica-coating of dental alloys: volume loss, morphology and changes in the surface composition.

PubMed

Kern, M; Thompson, V P

1993-05-01

Silica-coating alloys improves chemo-mechanical bonding. Sandblasting is recommended as pretreatment to thermal silica-coating or as part of a tribochemical silica-coating process. This study evaluated the effects of sandblasting and coating techniques on volume loss, surface morphology and compositional changes in noble (AuAgCu) and base alloys (NiCr and CoCr). Volume loss was statistically significantly higher in the noble as compared to the base alloys but does not seem to be critical for the clinical fit of restorations. Embedded alumina particles were found in all alloys after sandblasting and the alumina content increased to a range of 14 to 37 wt% as measured by EDS. Following tribochemical silica-coating, a layer of small silica particles remained on the surface, increasing the silica content to between 12 and 20 wt%. Ultrasonic cleaning removed loose alumina or silica particles from the surface, resulting in only slight decreases in alumina or silica contents, thus suggesting firm attachment of the major part of alumina and silica to the alloy surface. Clinically, ultrasonic cleaning of sandblasted and tribochemically silica-coated alloys might improve resin bonding as loose surface particles are removed without relevant changes in composition. Silica content following thermal silica-coating treatment increased only slightly from the sandblasted specimen. The silica layer employed by these silica-coating methods differs widely in both morphology and thickness. These results provide a basis for explanation of adhesive failure modes in bond strength tests which will possibly optimize resin bonding. Further research is needed to characterize the outermost surface layers after these treatments and the exact location of adhesive failures.

An EMAT-based shear horizontal (SH) wave technique for adhesive bond inspection

NASA Astrophysics Data System (ADS)

Arun, K.; Dhayalan, R.; Balasubramaniam, Krishnan; Maxfield, Bruce; Peres, Patrick; Barnoncel, David

2012-05-01

The evaluation of adhesively bonded structures has been a challenge over the several decades that these structures have been used. Applications within the aerospace industry often call for particularly high performance adhesive bonds. Several techniques have been proposed for the detection of disbonds and cohesive weakness but a reliable NDE method for detecting interfacial weakness (also sometimes called a kissing bond) has been elusive. Different techniques, including ultrasonic, thermal imaging and shearographic methods, have been proposed; all have had some degree of success. In particular, ultrasonic methods, including those based upon shear and guided waves, have been explored for the assessment of interfacial bond quality. Since 3-D guided shear horizontal (SH) waves in plates have predominantly shear displacement at the plate surfaces, we conjectured that SH guided waves should be influenced by interfacial conditions when they propagate between adhesively bonded plates of comparable thickness. This paper describes a new technique based on SH guided waves that propagate within and through a lap joint. Through mechanisms we have yet to fully understand, the propagation of an SH wave through a lap joint gives rise to a reverberation signal that is due to one or more reflections of an SH guided wave mode within that lap joint. Based upon a combination of numerical simulations and measurements, this method shows promise for detecting and classifying interfacial bonds. It is also apparent from our measurements that the SH wave modes can discriminate between adhesive and cohesive bond weakness in both Aluminum-Epoxy-Aluminum and Composite-Epoxy-Composite lap joints. All measurements reported here used periodic permanent magnet (PPM) Electro-Magnetic Acoustic Transducers (EMATs) to generate either or both of the two lowest order SH modes in the plates that comprise the lap joint. This exact configuration has been simulated using finite element (FE) models to describe the SH mode generation, propagation and reception. Of particular interest is that one SH guided wave mode (probably SH0) reverberates within the lap joint. Moreover, in both simulations and measurements, features of this so-called reverberation signal appear to be related to interfacial weakness between the plate (substrate) and the epoxy bond. The results of a hybrid numerical (FE) approach based on using COMSOL to calculate the driving forces within an elastic solid and ABAQUS to propagate the resulting elastic disturbances (waves) within the plates and lap joint are compared with measurements of SH wave generation and reception in lap joint specimens having different interfacial and cohesive bonding conditions.

Monolithic CMUT on CMOS Integration for Intravascular Ultrasound Applications

PubMed Central

Zahorian, Jaime; Hochman, Michael; Xu, Toby; Satir, Sarp; Gurun, Gokce; Karaman, Mustafa; Degertekin, F. Levent

2012-01-01

One of the most important promises of capacitive micromachined ultrasonic transducer (CMUT) technology is integration with electronics. This approach is required to minimize the parasitic capacitances in the receive mode, especially in catheter based volumetric imaging arrays where the elements need to be small. Furthermore, optimization of the available silicon area and minimized number of connections occurs when the CMUTs are fabricated directly above the associated electronics. Here, we describe successful fabrication and performance evaluation of CMUT arrays for intravascular imaging on custom designed CMOS receiver electronics from a commercial IC foundry. The CMUT on CMOS process starts with surface isolation and mechanical planarization of the CMOS electronics to reduce topography. The rest of the CMUT fabrication is achieved by modifying a low temperature micromachining process through the addition of a single mask and developing a dry etching step to produce sloped sidewalls for simple and reliable CMUT to CMOS interconnection. This CMUT to CMOS interconnect method reduced the parasitic capacitance by a factor of 200 when compared with a standard wire bonding method. Characterization experiments indicate that the CMUT on CMOS elements are uniform in frequency response and are similar to CMUTs simultaneously fabricated on standard silicon wafers without electronics integration. Experiments on a 1.6 mm diameter dual-ring CMUT array with a 15 MHz center frequency show that both the CMUTs and the integrated CMOS electronics are fully functional. The SNR measurements indicate that the performance is adequate for imaging CTOs located 1 cm away from the CMUT array. PMID:23443701

The Quantum Socket: Wiring for Superconducting Qubits - Part 1

NASA Astrophysics Data System (ADS)

McConkey, T. G.; Bejanin, J. H.; Rinehart, J. R.; Bateman, J. D.; Earnest, C. T.; McRae, C. H.; Rohanizadegan, Y.; Shiri, D.; Mariantoni, M.; Penava, B.; Breul, P.; Royak, S.; Zapatka, M.; Fowler, A. G.

Quantum systems with ten superconducting quantum bits (qubits) have been realized, making it possible to show basic quantum error correction (QEC) algorithms. However, a truly scalable architecture has not been developed yet. QEC requires a two-dimensional array of qubits, restricting any interconnection to external classical systems to the third axis. In this talk, we introduce an interconnect solution for solid-state qubits: The quantum socket. The quantum socket employs three-dimensional wires and makes it possible to connect classical electronics with quantum circuits more densely and accurately than methods based on wire bonding. The three-dimensional wires are based on spring-loaded pins engineered to insure compatibility with quantum computing applications. Extensive design work and machining was required, with focus on material quality to prevent magnetic impurities. Microwave simulations were undertaken to optimize the design, focusing on the interface between the micro-connector and an on-chip coplanar waveguide pad. Simulations revealed good performance from DC to 10 GHz and were later confirmed against experimental measurements.

Investigation of current transfer in built-up superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, J.R.; Dresner, L.; Lue, J.W.

1977-01-01

Superconductors carrying 10 kA or more have been widely suggested for use in fusion research and reactor magnets. Built-up or cable conductors have been proposed in which superconductor is concentrated in part of the conductor or part of the strands while the stabilizer occupies the rest. This scheme leads to substantial saving in manufacturing cost and to reduction of ac losses. Simplified analysis indicates that the current transfer from superconducting wire to normal wire takes place over a characteristic length depending on the resistivity of the contact barrier, the resistivity of the stabilizer, and the geometry of the conductor. Furthermore,more » the cold-end recovery suffers a reduction. Two types of conductors were constructed for the experimental test. Triplex conductors consisting of either three superconducting wires or two superconducting plus one copper wire were used to simulate cables. Laminated superconductor and copper strips with different soldering bonds were used for build-ups. Normal zone propagation and recovery experiments have been performed and results are compared with the theory.« less

Microstructure and Properties of Lap Joint Between Aluminum Alloy and Galvanized Steel by CMT

NASA Astrophysics Data System (ADS)

Niu, Song; Chen, Su; Dong, Honggang; Zhao, Dongsheng; Zhang, Xiaosheng; Guo, Xin; Wang, Guoqiang

2016-05-01

Lap joining of 1-mm-thick Novelist AC 170 PX aluminum alloy to 1.2-mm-thick ST06 Z galvanized steel sheets for automotive applications was conducted by cold metal transfer advanced welding process with ER4043 and ER4047 filler wires. Under the optimized welding parameters with ER4043 filler wire, the tensile shear strength of joint was 189 MPa, reaching 89% of the aluminum alloy base metal. Microstructure and elemental distribution were characterized by optical metalloscope and electron probe microanalysis. The lap joints with ER4043 filler wire had smaller wetting angle and longer bonded line length with better wettability than with ER4047 filler wire during welding with same parameters. The needle-like Al-Fe-Si intermetallic compounds (IMCs) were spalled into the weld and brought negative effect to the tensile strength of joints. With increasing welding current, the needle-like IMCs grew longer and spread further into the weld, which would deteriorate the tensile shear strength.

Ultrasonic sensing of powder densification

NASA Technical Reports Server (NTRS)

Lu, Yichi; Wadley, Haydn N. G.; Parthasarathi, Sanjai

1992-01-01

An independent scattering theory has been applied to the interpretation of ultrasonic velocity measurements made on porous metal samples produced either by a cold or a high-temperature compaction process. The results suggest that the pores in both processes are not spherical, an aspect ration of 1:3 fitting best with the data for low (less than 4 percent) pore volume fractions. For the hot compacted powders, the pores are smooth due to active diffusional processes during processing. For these types of voids, the results can be extended to a pore fraction of 10 percent, at which point voids form an interconnected network that violates the model assumptions. The cold pressed samples are not as well predicted by the theory because of poor particle bonding.

Apparatus for ultrasonic nebulization

DOEpatents

Olson, Kenneth W.; Haas, Jr., William J.; Fassel, Velmer A.

1978-08-29

An improved apparatus for ultrasonic nebulization of liquid samples or suspensions in which the piezoelectric transducer is protected from chemical attack and erosion. The transducer is protected by being bonded to the inner surface of a glass plate which forms one end wall of a first hollow body provided with apparatus for circulating a fluid for cooling and stabilizing the transducer. The glass plate, which is one-half wavelength in thickness to provide an acoustically coupled outer nebulizing surface, seals an opening in a second hollow body which encloses an aerosol mixing chamber. The second body includes apparatus for delivering the sample solution to the nebulizing surface, a gas inlet for providing a flow of carrier gas for transporting the aerosol of the nebulized sample and an aerosol outlet.

Salt-Assisted Ultrasonicated De-Aggregation and Advanced Redox Electrochemistry of Detonation Nanodiamond

PubMed Central

Gupta, Sanju; Evans, Brendan; Henson, Alex; Carrizosa, Sara B.

2017-01-01

Nanodiamond particles form agglomerates in the dry powder state and this poses limitation to the accessibility of their diamond-like core thus dramatically impacting their technological advancement. In this work, we report de-agglomeration of nanodiamond (ND) by using a facile technique namely, salt-assisted ultrasonic de-agglomeration (SAUD). Utilizing ultrasound energy and ionic salts (sodium chloride and sodium acetate), SAUD is expected to break apart thermally treated nanodiamond aggregates (~50–100 nm) and produce an aqueous slurry of de-aggregated stable colloidal nanodiamond dispersions by virtue of ionic interactions and electrostatic stabilization. Moreover, the SAUD technique neither has toxic chemicals nor is it difficult to remove impurities and therefore the isolated nanodiamonds produced are exceptionally suited for engineered nanocarbon for mechanical (composites, lubricants) and biomedical (bio-labeling, biosensing, bioimaging, theranostic) applications. We characterized the microscopic structure using complementary techniques including transmission electron microscopy combined with selected-area electron diffraction, optical and vibrational spectroscopy. We immobilized SAUD produced NDs on boron-doped diamond electrodes to investigate fundamental electrochemical properties. They included surface potential (or Fermi energy level), carrier density and mapping electrochemical (re)activity using advanced scanning electrochemical microscopy in the presence of a redox-active probe, with the aim of understanding the surface redox chemistry and the interfacial process of isolated nanodiamond particles as opposed to aggregated and untreated nanoparticles. The experimental findings are discussed in terms of stable colloids, quantum confinement and predominantly surface effects, defect sites (sp2–bonded C and unsaturated bonds), inner core (sp3–bonded C)/outer shell (sp2–bonded C) structure, and surface functionality. Moreover, the surface electronic states give rise to midgap states which serve as electron donors (or acceptors) depending upon the bonding (or antibonding). These are important as electroanalytical platforms for various electrocatalytic processes. PMID:29125547

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1973-01-01

This progress report describes NBS activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices. Significant accomplishments during this reporting period include design of a plan to provide standard silicon wafers for four-probe resistivity measurements for the industry, publication of a summary report on the photoconductive decay method for measuring carrier lifetime, publication of a comprehensive review of the field of wire bond fabrication and testing, and successful completion of organizational activity leading to the establishment of a new group on quality and hardness assurance in ASTM Committee F-1 on Electronics. Work is continuing on measurement of resistivity of semiconductor crystals; characterization of generation-recombination-trapping centers in silicon; study of gold-doped silicon; development of the infrared response technique; evaluation of wire bonds and die attachment; and measurement of thermal properties of semiconductor devices, delay time and related carrier transport properties in junction devices, and noise properties of microwave diodes.

High-speed receiver based on waveguide germanium photodetector wire-bonded to 90nm SOI CMOS amplifier.

PubMed

Pan, Huapu; Assefa, Solomon; Green, William M J; Kuchta, Daniel M; Schow, Clint L; Rylyakov, Alexander V; Lee, Benjamin G; Baks, Christian W; Shank, Steven M; Vlasov, Yurii A

2012-07-30

The performance of a receiver based on a CMOS amplifier circuit designed with 90nm ground rules wire-bonded to a waveguide germanium photodetector is characterized at data rates up to 40Gbps. Both chips were fabricated through the IBM Silicon CMOS Integrated Nanophotonics process on specialty photonics-enabled SOI wafers. At the data rate of 28Gbps which is relevant to the new generation of optical interconnects, a sensitivity of -7.3dBm average optical power is demonstrated with 3.4pJ/bit power-efficiency and 0.6UI horizontal eye opening at a bit-error-rate of 10(-12). The receiver operates error-free (bit-error-rate < 10(-12)) up to 40Gbps with optimized power supply settings demonstrating an energy efficiency of 1.4pJ/bit and 4pJ/bit at data rates of 32Gbps and 40Gbps, respectively, with an average optical power of -0.8dBm.

Effect of High Temperature Storage in Vacuum, Air, and Humid Conditions on Degradation of Gold/Aluminum Wire Bonds in PEMs

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander

2006-01-01

Microcircuits encapsulated in three plastic package styles were stored in different environments at temperatures varying from 130 C to 225 C for up to 4,000 hours in some cases. To assess the effect of oxygen, the parts were aged at high temperatures in air and in vacuum chambers. The effect of humidity was evaluated during long-term highly accelerated temperature and humidity stress testing (HAST) at temperatures of 130 C and 150 C. High temperature storage testing of decapsulated microcircuits in air, vacuum, and HAST chambers was carried out to evaluate the role of molding compounds in the environmentally-induced degradation and failure of wire bonds (WB). This paper reports on accelerating factors of environment and molding compound on WB failures. It has been shown that all environments, including oxygen, moisture, and the presence of molding compounds reduce time-to-failures compared to unencapsulated devices in vacuum conditions. The mechanism of the environmental effect on KB degradation is discussed.

A guided-wave system for monitoring the wing skin-to-spar bond in unmanned aerial vehicles

NASA Astrophysics Data System (ADS)

Matt, Howard; Bartoli, Ivan; Lanza di Scalea, Francesco; Marzani, Alessandro; Coccia, Stefano; Oliver, Joseph; Kosmatka, John; Rizzo, Piervincenzo; Restivo, Gaetano

2005-05-01

Unmanned Aerial Vehicles (UAVs) are being increasingly used in military as well as civil applications. A critical part of the structure is the adhesive bond between the wing skin and the supporting spar. If not detected early, bond defects originating during manufacturing or in service flight can lead to inefficient flight performance and eventual global failure. This paper will present results from a bond inspection system based on attached piezoelectric disks probing the skin-to-spar bondline with ultrasonic guided waves in the hundreds of kilohertz range. The test components were CFRP composite panels of two different fiber layups bonded to a CFRP composite tube using epoxy adhesive. Three types of bond conditions were simulated, namely regions of poor cohesive strength, regions with localized disbonds and well bonded regions. The root mean square and variance of the received time-domain signals and their discrete wavelet decompositions were computed for the dominant modes propagating through the various bond regions in two different inspection configurations. Semi-analytical finite element analysis of the bonded multilayer joint was also carried out to identify and predict the sensitivity of the predominant carrier modes to the different bond defects. Emphasis of this research is based upon designing a built-in system for monitoring the structural integrity of bonded joints in UAVs and other aerospace structures.

Structural Characterization of N-Alkylated Twisted Amides: Consequences for Amide Bond Resonance and N-C Cleavage.

PubMed

Hu, Feng; Lalancette, Roger; Szostak, Michal

2016-04-11

Herein, we describe the first structural characterization of N-alkylated twisted amides prepared directly by N-alkylation of the corresponding non-planar lactams. This study provides the first experimental evidence that N-alkylation results in a dramatic increase of non-planarity around the amide N-C(O) bond. Moreover, we report a rare example of a molecular wire supported by the same amide C=O-Ag bonds. Reactivity studies demonstrate rapid nucleophilic addition to the N-C(O) moiety of N-alkylated amides, indicating the lack of n(N) to π*(C=O) conjugation. Most crucially, we demonstrate that N-alkylation activates the otherwise unreactive amide bond towards σ N-C cleavage by switchable coordination. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrasonically Activated Diffusion Bonding for Fluidic Control Assembly

DTIC Science & Technology

1979-02-01

CONTROL ASSEMBLY SONOBOND CORPORATION SUBSIDIARY OF CHRISTIAN METALS CORPORATION WEST CHESTER, PENNSYLVANIA HOWARD A. SCHEETZ PAUL L. COPPA JANET...FLUIDIC CONTROL ASSEMBLY Howard A. Scheetz Paul L. Coppa Janet Devine Sonobond Corporation Subsidiary of Christiana Metals Corporation West... Paul L. Coppa Janet Devine fl. CONTRACT OR GRANT NUMBERS.) Contract No. DAAA21-76-C-0136 ». PERFORMING ORGANIZATION N AM t AND ADDRESS

Angle-Beam Shear Wave Scattering from Buried Crack-like Defects in Bonded Specimens (Postprint)

DTIC Science & Technology

2017-02-01

wavenumber filtering and spatial windowing is proposed and implemented as an alternative approach to quantify scattering from damage. 15. SUBJECT...TERMS Backscattering . Ultrasonography . Spatial filtering . Ultrasonic scattering . Scattering measurement 16. SECURITY CLASSIFICATION OF: 17...of frequency- wavenumber filtering and spatial windowing is proposed and implemented as an alternative approach to quantify scattering from damage

Impact of different rectangular wires on torsional expression of different sizes of buccal tube.

PubMed

Ajami, Shabnam; Boroujeni, Afshar-Rasti

2018-01-01

Torsions in rectangular wires are the essential part of corrections in the finishing stage of treatment. Moreover the greatest amounts of torques are applied in the molar areas. a clinically effective moment is between 5 and 20 Nmm. In this study we have decided to evaluate the impact of different tube sizes and different dimensions of wires with different modulus of elasticities on the amount torsional bond strength of molar tubes. 60 human impacted molar teeth were collected. A buccal tube was bonded on the buccal surface of all the samples by using light cured adhesive resin. After that, the teeth were mounted in a hard acrylic block. According to the size of buccal tube and the rectangular wires to be tested 4 groups will be designed. Torsional force was applied by instron machine. The torque angle at 5Nmm and at 20Nmm point will be calculated: which means, how many degrees of torque is required to reach the maximum 20Nmm moment from the minimum 5Nmm.One-way ANOVA was used to compare torque angle in all of the groups. The least amount of clinically significant angle was 2.2 ᵒ in the 0.017×0.025 SS and the largest amount of it was 23.7 ᵒ in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. But, this angle was 19.9 ᵒand 13.6 ᵒ in 0.019×0.025 SS and 0.019×0.025 TMA archwire in 0.022×0.028 molar tube. The 0.017×0.025 SS archwire in 0.018×0.025 molar tube had the lowest clinically significant angle. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube. Key words: Torsional efficacy, rectangular wires, buccal tubes, torque angle.

Impact of different rectangular wires on torsional expression of different sizes of buccal tube

PubMed Central

Boroujeni, Afshar-Rasti

2018-01-01

Background Torsions in rectangular wires are the essential part of corrections in the finishing stage of treatment. Moreover the greatest amounts of torques are applied in the molar areas. a clinically effective moment is between 5 and 20 Nmm. In this study we have decided to evaluate the impact of different tube sizes and different dimensions of wires with different modulus of elasticities on the amount torsional bond strength of molar tubes. Material and Methods 60 human impacted molar teeth were collected. A buccal tube was bonded on the buccal surface of all the samples by using light cured adhesive resin. After that, the teeth were mounted in a hard acrylic block. According to the size of buccal tube and the rectangular wires to be tested 4 groups will be designed. Torsional force was applied by instron machine. The torque angle at 5Nmm and at 20Nmm point will be calculated: which means, how many degrees of torque is required to reach the maximum 20Nmm moment from the minimum 5Nmm.One-way ANOVA was used to compare torque angle in all of the groups. Results The least amount of clinically significant angle was 2.2 ᵒ in the 0.017×0.025 SS and the largest amount of it was 23.7 ᵒ in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. But, this angle was 19.9 ᵒand 13.6 ᵒ in 0.019×0.025 SS and 0.019×0.025 TMA archwire in 0.022×0.028 molar tube. Conclusions The 0.017×0.025 SS archwire in 0.018×0.025 molar tube had the lowest clinically significant angle. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube. Key words: Torsional efficacy, rectangular wires, buccal tubes, torque angle. PMID:29670712

Electrostatically focused intensified charge coupled devices

NASA Technical Reports Server (NTRS)

Walker, J. W.

1977-01-01

Work performed to develop intensified charge coupled devices (ICCDs) is presented. Four ICCDs, containing 100 x 160 arrays, were fabricated. Electron gains up to 3200 at 15 keV were achieved. Photocathode sensitivities ranged from 190 to 410 micro A/lumen. Dark currents varied from 11 nA/sq cm to 37 nA/sq cm. There was serious concern about the reliability of the bonding scheme for ICCDs due to occassional bond failure. Two solutions to this problem were developed. One involved a modification of the existing bonding technique, and the other was the development of a protected bond pad employing a barrier metal between the aluminum metallization and the gold bond wire. An accumulation process was characterized with respect to its most critical variable. This characterization led to the achievement of reproducible spectral response and the discovery and elimination of dark current increase associated with this process.

Cold Pad-Batch dyeing method for cotton fabric dyeing with reactive dyes using ultrasonic energy.

PubMed

Khatri, Zeeshan; Memon, Muhammad Hanif; Khatri, Awais; Tanwari, Anwaruddin

2011-11-01

Reactive dyes are vastly used in dyeing and printing of cotton fibre. These dyes have a distinctive reactive nature due to active groups which form covalent bonds with -OH groups of cotton through substitution and/or addition mechanism. Among many methods used for dyeing cotton with reactive dyes, the Cold Pad Batch (CPB) method is relatively more environment friendly due to high dye fixation and non requirement of thermal energy. The dyed fabric production rate is low due to requirement of at least twelve hours batching time for dye fixation. The proposed CPB method for dyeing cotton involves ultrasonic energy resulting into a one third decrease in batching time. The dyeing of cotton fibre was carried out with CI reactive red 195 and CI reactive black 5 by conventional and ultrasonic (US) method. The study showed that the use of ultrasonic energy not only shortens the batching time but the alkalis concentrations can considerably be reduced. In this case, the colour strength (K/S) and dye fixation (%F) also enhances without any adverse effect on colour fastness of the dyed fabric. The appearance of dyed fibre surface using scanning electron microscope (SEM) showed relative straightening of fibre convolutions and significant swelling of the fibre upon ultrasonic application. The total colour difference values ΔE (CMC) for the proposed method, were found within close proximity to the conventionally dyed sample. Copyright © 2011 Elsevier B.V. All rights reserved.

Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method.

PubMed

Gopi, D; Indira, J; Kavitha, L; Sekar, M; Mudali, U Kamachi

2012-07-01

Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology. Copyright © 2012 Elsevier B.V. All rights reserved.

NDE of Fiber Reinforced Foam Composite Structures for Future Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Walker, james; Roth, Don; Hopkins, Dale

2010-01-01

This slide presentation reviews the complexities of non-destructive evaluation (NDE) of fiber reinforced foam composite structures to be used for aerospace vehicles in the future.Various views of fiber reinforced foam materials are shown and described. Conventional methods of NDE for composites are reviewed such as Micro-computed X-Ray Tomography, Thermography, Shearography, and Phased Array Ultrasonics (PAUT). These meth0ods appear to work well on the face sheet and face sheet ot core bond, they do not provide adequate coverage for the webs. There is a need for additional methods that will examine the webs and web to foam core bond.

Interactions between graphene oxide and wide band gap semiconductors

NASA Astrophysics Data System (ADS)

Kawa, M.; Podborska, A.; Szaciłowski, K.

2016-09-01

The graphene oxide (GO) and GO@TiO2 nanocomposite have been synthesised by using modified Hummers method and ultrasonics respectively. The materials were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy and UV-Vis absorption spectroscopy. It was found that the interaction between GO and TiO2 affects the average interlayer spacing in carbonaceous material. The formation of bonds between various oxygen-containing functional groups and surface of titanium dioxide was investigated. One of them formed between the quinone structures (occur in graphene oxide) and titanium atoms exhibited 1.5 bond order. Furthermore the charge-transfer processes in GO@TiO2 composite were observed.

A digital, constant-frequency pulsed phase-locked-loop instrument for real-time, absolute ultrasonic phase measurements

NASA Astrophysics Data System (ADS)

Haldren, H. A.; Perey, D. F.; Yost, W. T.; Cramer, K. E.; Gupta, M. C.

2018-05-01

A digitally controlled instrument for conducting single-frequency and swept-frequency ultrasonic phase measurements has been developed based on a constant-frequency pulsed phase-locked-loop (CFPPLL) design. This instrument uses a pair of direct digital synthesizers to generate an ultrasonically transceived tone-burst and an internal reference wave for phase comparison. Real-time, constant-frequency phase tracking in an interrogated specimen is possible with a resolution of 0.000 38 rad (0.022°), and swept-frequency phase measurements can be obtained. Using phase measurements, an absolute thickness in borosilicate glass is presented to show the instrument's efficacy, and these results are compared to conventional ultrasonic pulse-echo time-of-flight (ToF) measurements. The newly developed instrument predicted the thickness with a mean error of -0.04 μm and a standard deviation of error of 1.35 μm. Additionally, the CFPPLL instrument shows a lower measured phase error in the absence of changing temperature and couplant thickness than high-resolution cross-correlation ToF measurements at a similar signal-to-noise ratio. By showing higher accuracy and precision than conventional pulse-echo ToF measurements and lower phase errors than cross-correlation ToF measurements, the new digitally controlled CFPPLL instrument provides high-resolution absolute ultrasonic velocity or path-length measurements in solids or liquids, as well as tracking of material property changes with high sensitivity. The ability to obtain absolute phase measurements allows for many new applications than possible with previous ultrasonic pulsed phase-locked loop instruments. In addition to improved resolution, swept-frequency phase measurements add useful capability in measuring properties of layered structures, such as bonded joints, or materials which exhibit non-linear frequency-dependent behavior, such as dispersive media.

Physical interpretation and development of ultrasonic nondestructive evaluation techniques applied to the quantitative characterization of textile composite materials

NASA Technical Reports Server (NTRS)

Miller, James G.

1994-01-01

In this Progress Report, we describe our continuing research activities concerning the development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the inspection and characterization of complex composite structures. We explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize complex materials. As an initial step toward the application of linear array imaging technology to the interrogation of a wide range of complex composite structures, we present images obtained using an unmodified medical ultrasonic imaging system of two epoxy-bonded aluminum plate specimens, each with intentionally disbonded regions. These images are compared with corresponding conventional ultrasonic contact transducer measurements in order to assess whether these images can detect disbonded regions and provide information regarding the nature of the disbonded region. We present a description of a standoff/delay fixture which has been designed, constructed, and implemented on a Hewlett-Packard SONOS 1500 medical imaging system. This standoff/delay fixture, when attached to a 7.5 MHz linear array probe, greatly enhances our ability to interrogate flat plate specimens. The final section of this Progress Report describes a woven composite plate specimen that has been specially machined to include intentional flaws. This woven composite specimen will allow us to assess the feasibility of applying linear array imaging technology to the inspection and characterization of complex textile composite materials. We anticipate the results of this on-going investigation may provide a step toward the development of a rapid, real-time, and portable method of ultrasonic inspection and characterization based on linear array technology.

H+-type and OH--type biological protonic semiconductors and complementary devices

NASA Astrophysics Data System (ADS)

Deng, Yingxin; Josberger, Erik; Jin, Jungho; Rousdari, Anita Fadavi; Helms, Brett A.; Zhong, Chao; Anantram, M. P.; Rolandi, Marco

2013-10-01

Proton conduction is essential in biological systems. Oxidative phosphorylation in mitochondria, proton pumping in bacteriorhodopsin, and uncoupling membrane potentials by the antibiotic Gramicidin are examples. In these systems, H+ hop along chains of hydrogen bonds between water molecules and hydrophilic residues - proton wires. These wires also support the transport of OH- as proton holes. Discriminating between H+ and OH- transport has been elusive. Here, H+ and OH- transport is achieved in polysaccharide- based proton wires and devices. A H+- OH- junction with rectifying behaviour and H+-type and OH--type complementary field effect transistors are demonstrated. We describe these devices with a model that relates H+ and OH- to electron and hole transport in semiconductors. In turn, the model developed for these devices may provide additional insights into proton conduction in biological systems.

H+-type and OH−-type biological protonic semiconductors and complementary devices

PubMed Central

Deng, Yingxin; Josberger, Erik; Jin, Jungho; Rousdari, Anita Fadavi; Helms, Brett A.; Zhong, Chao; Anantram, M. P.; Rolandi, Marco

2013-01-01

Proton conduction is essential in biological systems. Oxidative phosphorylation in mitochondria, proton pumping in bacteriorhodopsin, and uncoupling membrane potentials by the antibiotic Gramicidin are examples. In these systems, H+ hop along chains of hydrogen bonds between water molecules and hydrophilic residues – proton wires. These wires also support the transport of OH− as proton holes. Discriminating between H+ and OH− transport has been elusive. Here, H+ and OH− transport is achieved in polysaccharide- based proton wires and devices. A H+- OH− junction with rectifying behaviour and H+-type and OH−-type complementary field effect transistors are demonstrated. We describe these devices with a model that relates H+ and OH− to electron and hole transport in semiconductors. In turn, the model developed for these devices may provide additional insights into proton conduction in biological systems. PMID:24089083

Cement-based materials' characterization using ultrasonic attenuation

NASA Astrophysics Data System (ADS)

Punurai, Wonsiri

The quantitative nondestructive evaluation (NDE) of cement-based materials is a critical area of research that is leading to advances in the health monitoring and condition assessment of the civil infrastructure. Ultrasonic NDE has been implemented with varying levels of success to characterize cement-based materials with complex microstructure and damage. A major issue with the application of ultrasonic techniques to characterize cement-based materials is their inherent inhomogeneity at multiple length scales. Ultrasonic waves propagating in these materials exhibit a high degree of attenuation losses, making quantitative interpretations difficult. Physically, these attenuation losses are a combination of internal friction in a viscoelastic material (ultrasonic absorption), and the scattering losses due to the material heterogeneity. The objective of this research is to use ultrasonic attenuation to characterize the microstructure of heterogeneous cement-based materials. The study considers a real, but simplified cement-based material, cement paste---a common bonding matrix of all cement-based composites. Cement paste consists of Portland cement and water but does not include aggregates. First, this research presents the findings of a theoretical study that uses a set of existing acoustics models to quantify the scattered ultrasonic wavefield from a known distribution of entrained air voids. These attenuation results are then coupled with experimental measurements to develop an inversion procedure that directly predicts the size and volume fraction of entrained air voids in a cement paste specimen. Optical studies verify the accuracy of the proposed inversion scheme. These results demonstrate the effectiveness of using attenuation to measure the average size, volume fraction of entrained air voids and the existence of additional larger entrapped air voids in hardened cement paste. Finally, coherent and diffuse ultrasonic waves are used to develop a direct relationship between attenuation and water to cement (w/c) ratio. A phenomenological model based on the existence of fluid-filled capillary voids is used to help explain the experimentally observed behavior. Overall this research shows the potential of using ultrasonic attenuation to quantitatively characterize cement paste. The absorption and scattering losses can be related to the individual microstructural elements of hardened cement paste. By taking a fundamental, mechanics-based approach, it should be possible to add additional components such as scattering by aggregates or even microcracks in a systematic fashion and eventually build a realistic model for ultrasonic wave propagation study for concrete.

Development of lead-free single-element ultrahigh frequency (170 – 320 MHz) ultrasonic transducers

PubMed Central

Lam, Kwok Ho; Ji, Hong Fen; Zheng, Fan; Ren, Wei; Zhou, Qifa; Shung, K. Kirk

2013-01-01

This paper presents the design, fabrication and characterization of single-element ultrahigh frequency (UHF) ultrasonic transducers in which the center frequency ranged from 170 to 320 MHz. The center frequency of > 300 MHz is the highest value of lead-free ceramic ultrasonic transducers ever reported. With concern in the environmental pollution of lead-based materials, the transducer elements presented in this work were lead-free K0.5Na0.5NbO3/Bi0.5Na0.5TiO3 (KNN/BNT) composite thick films. All transducers were evaluated in a pulse-echo arrangement. The measured −6 dB bandwidth of the transducers ranged from 35 to 64 %. With the optimized piezoelectric properties of the composite film, the insertion loss of the UHF transducers was measured and determined to range from −50 to −60 dB. In addition to the pulse-echo measurement, a 6-μm tungsten wire phantom was also imaged with a 205 MHz transducer to demonstrate the imaging capability. The measured −6 dB axial and lateral resolutions were found to be 12 μm and 50 μm, respectively. The transducer performance presented in this work is shown to be better or comparable to previously reported results even though the frequency is much higher. PMID:23485349

Dispersed Sensing Networks in Nano-Engineered Polymer Composites: From Static Strain Measurement to Ultrasonic Wave Acquisition

PubMed Central

Li, Yehai; Wang, Kai

2018-01-01

Self-sensing capability of composite materials has been the core of intensive research over the years and particularly boosted up by the recent quantum leap in nanotechnology. The capacity of most existing self-sensing approaches is restricted to static strains or low-frequency structural vibration. In this study, a new breed of functionalized epoxy-based composites is developed and fabricated, with a graphene nanoparticle-enriched, dispersed sensing network, whereby to self-perceive broadband elastic disturbance from static strains, through low-frequency vibration to guided waves in an ultrasonic regime. Owing to the dispersed and networked sensing capability, signals can be captured at any desired part of the composites. Experimental validation has demonstrated that the functionalized composites can self-sense strains, outperforming conventional metal foil strain sensors with a significantly enhanced gauge factor and a much broader response bandwidth. Precise and fast self-response of the composites to broadband ultrasonic signals (up to 440 kHz) has revealed that the composite structure itself can serve as ultrasound sensors, comparable to piezoceramic sensors in performance, whereas avoiding the use of bulky cables and wires as used in a piezoceramic sensor network. This study has spotlighted promising potentials of the developed approach to functionalize conventional composites with a self-sensing capability of high-sensitivity yet minimized intrusion to original structures. PMID:29724032

A high-sensitivity magnetocardiography system with a divided gradiometer array inside a low boil-off Dewar

NASA Astrophysics Data System (ADS)

Lee, Y. H.; Yu, K. K.; Kim, J. M.; Kwon, H.; Kim, K.

2009-11-01

We fabricated a low-noise 64-channel first-order axial gradiometer system for measuring magnetocardiography (MCG) signals. The key technical features of the system are the compact structure of the gradiometer, division of the sensor array plate, direct mounting of the sensor plates into the Dewar bottom, reduced neck diameter of the liquid He Dewar, and compact readout electronics. To make the refill interval of liquid He longer, the distance between the compensation coil of the gradiometer and the input coil pads of the superconducting quantum interference device (SQUID) was reduced to 20 mm. By using direct ultrasonic bonding of Nb wires between the pickup coil wires and input coil pads, the superconductive connection structure became simple. The baseline of the first-order gradiometer is 70 mm, a little longer than for typical conventional axial gradiometers, to provide a larger signal amplitude for deep sources. The 64-channel gradiometer array consists of four blocks, and each block is fixed separately onto the bottom of the Dewar. The neck diameter of the He Dewar (192 mm) is smaller than the bottom diameter (280 mm) in which the gradiometers are distributed. The average boil-off rate of the Dewar is 3 l per day when the 64-channel system is in operation every day. Double relaxation oscillation SQUIDs (DROSs) having large flux-to-voltage transfer coefficients were used to operate SQUIDs via compact electronics. The magnetically shielded room (MSR) has a wall thickness of 80 mm, and consists of two layers of permalloy and one layer of aluminum. When the 64-channel system was installed inside the MSR, the field noise level of the system was about 3.5 fTrms Hz-1/2 at 100 Hz. MCG measurements with high signal quality were done successfully using the developed system. In addition to the parameter analysis method, we developed software for the three-dimensional imaging of the myocardial current on a realistic image of the heart based on the anatomical image of the torso.

Study of a reinforced concrete beam strengthened using a combination of SMA wire and CFRP plate

NASA Astrophysics Data System (ADS)

Liu, Zhi-qiang; Li, Hui

2006-03-01

Traditional methods used for strengthening of reinforced concrete (RC) structures, such as bonding of steel plates, suffer from inherent disadvantages. In recent years, strengthening of RC structures using carbon fiber reinforced polymer (CFRP) plates has attracted considerable attentions around the world. Most existing research on CFRP plate bonding for flexural strengthening of RC beams has been carried out for the strength enhancement. However, little research is focused on effect of residual deformations on the strengthening. The residual deformations have an important effect on the strengthening by CFRP plates. There exists a very significant challenge how the residual deformations are reduced. Shape memory alloy (SMA) has showed outstanding functional properties as an actuator. It is a possibility that SMA can be used to reduce the residual deformation and make cracks of concrete close by imposing the recovery forces on the concrete in the tensile zone. It is only an emergency damage repair since the SMA wires need to be heated continuously. So, an innovative method of a RC beam strengthened by CFRP plates in combination with SMA wires was first investigated experimentally in this paper. In addition, the nonlinear finite element software of ABAQUS was employed to further simulate the behavior of RC beams strengthened through the new strengthening method. It can be found that this is an excellent and effective strengthening method.

A review of recent developments in joining high-performance thermoplastic composites

NASA Astrophysics Data System (ADS)

Cole, K. C.

1991-06-01

There is currently a great deal of interest in the use of thermoplastic polymers as matrices in fiber reinforced composites for high performance applications, such as those encountered in the aerospace industry. These materials include polyether ether ketone (PEEK), polyphenylene sulphide (PPS), polyetherimide (PEI), polyamideimide (PAI), polyamides, polyimides, and polysulphones. A literature review is provided on the different ways of joining high performance thermoplastic composites by adhesive and fusion bonding. The discussion on adhesive bonding includes examination of the performance of specific adhesive/thermoplastic combinations and of techniques for the preparation of composite surfaces: abrasion, etching, flame, and plasma treatments. Thermoplastic composite welding techniques discussed in depth include the following: heated press welding, resistance welding, induction welding, and ultrasonic welding. Works which examine or compare applications for these bonding techniques are also reviewed.

Respectful Youth Cultures

ERIC Educational Resources Information Center

Laursen, Erik K.

2014-01-01

Children are social beings who rely on interactions with others to survive and thrive. Since the human brain is wired to connect, cultures in schools and youth organizations must be designed so youth can bond to supportive peers and adults. Children learn through observation, modeling, and responding to people in their environments. Bronfenbrenner…

Development of Integrated and Flexible Ultrasonic Transducers for Aerospace Applications

NASA Astrophysics Data System (ADS)

Wu, Kuo-Ting

2011-12-01

High temperature (HT) integrated (IUTs) and flexible ultrasonic transducers (FUTs) for potential aerospace applications in the area of nondestructive testing (NDT) and structural health monitoring (SHM) are developed. The main merits are that IUTs can be fabricated on-site and FUTs are feasible and attractive for on-site installation. The piezoelectric composite films of these HT ultrasonic transducers (HTUTs) are made by sol-gel spray fabrication. Lead-zirconate titanate composite (PZT-c), bismuth titanate composite (BIT-c), or lithium niobate composite (LiNbO3-c) films were coated onto metallic substrates with planar and curved surfaces and investigated as IUTs. Their maximum operating temperatures were demonstrated at up to 150°C, 400°C, and 800°C, respectively. PZT-c or BIT-c films were coated onto 75 mum or 38 mum thick metallic membranes and were investigated as FUTs. They can be bonded onto flat or curved surfaces for NDT and SHM. An FUT made of BIT-c film coated onto a stainless steel membrane glued onto a steel plate was performed at up to 300°C. Besides being coated onto metallic materials, sol-gel sprayed composite films were also coated onto graphite/epoxy (Gr/Ep) plates as IUTs and 50 mum thick polyimide films as FUTs for the thickness and delamination evaluation. Using acoustic mode conversion techniques, HTUTs for shear (S) wave, surface acoustic wave (SAW), and plate acoustic wave (PAW), have been developed. HT ultrasonic probes simultaneously producing one longitudinal (L) and two orthogonally polarized S waves were demonstrated in metallic and Plexiglas probes. The potential applications of these probes were discussed. Also applying mode conversion approaches, HT symmetrical, anti-symmetrical, and shear horizontal (SH) PAWs UTs for NDT and SHM were developed. The results showed that the SH PAWs may be the best candidate for NDT and SHM purposes for plate structures. Generation and detection of guided acoustic waves for NDT were demonstrated by using IUTs or FUTs with metallic wedges, mechanical gratings or interdigital transducers as well. The experiments with these three approaches were performed at up to 300°C. Furthermore, two non-contact ultrasonic measurement techniques by sol-gel sprayed composite films were presented in this thesis. One is using lasers to generate ultrasound and IUTs as receivers, and the other is using induction-based non-contact ultrasonic measurement technique with IUTs. NDT of bonded composite patches on aluminum plates was performed using laser generated ultrasound and IUT receivers. The induction-based ultrasonic measurement of a Gr/Ep composite plate rotated at 1000 rpm was demonstrated. The IUTs and FUTs developed in this thesis are able to provide signals with good signal-to-noise ratios at elevated temperature on structures and parts having a curved surface. They are light weight and miniature in size. They may be used for real-time, in situ, nondestructive local and global (large area) damage detection and assessment in aerospace NDT and SHM applications.

Influence of metal bonding layer on strain transfer performance of FBG

NASA Astrophysics Data System (ADS)

Liu, Hao; Chen, Weimin; Zhang, Peng; Liu, Li; Shu, Yuejie; Wu, Jun

2013-01-01

Metal bonding layer seriously affects the strain transfer performance of Fiber Bragg Grating (FBG). Based on the mode of FBG strain transfer, the influence of the length, the thickness, Poisson's ratio, elasticity modulus of metal bonding layer on the strain transfer coefficient of FBG is analyzed by numerical simulation. FBG is packaged to steel wire using metal bonding technology of FBG. The tensile tests of different bonding lengths and elasticity modulus are carried out. The result shows the strain transfer coefficient of FBGs are 0.9848,0.962 and their average strain sensitivities are 1.076 pm/μɛ,1.099 pm/μɛ when the metal bonding layer is zinc, whose lengths are 15mm, 20mm, respectively. The strain transfer coefficient of FBG packaged by metal bonding layer raises 8.9 percent compared to epoxy glue package. The preliminary experimental results show that the strain transfer coefficient increases with the length of metal bonding layer, decreases with the thickness of metal bonding layer and the influence of Poisson's ratio can be ignored. The experiment result is general agreement with the analysis and provides guidance for metal package of FBG.

Ultrasonically assisted synthesis of lead oxide nanoflowers using ball milling

NASA Astrophysics Data System (ADS)

Bangi, Uzma K. H.; Park, Hyung-Ho; Han, Wooje; Prakshale, Vipul M.; Deshmukh, Lalasaheb P.

2017-05-01

The experimental results on the ultrasonically assisted synthesis of lead oxide nanoflowers using ball milling have been reported in the present work. Lead oxide nanoflowers were prepared employing mixed ligands by subjecting the formed precipitate to ultrasonication and grinding/ball milling. The effect of ball milling as well as fine grinding in agate mortar on the microstructure and surface morphology of the lead oxide was studied. The characteristics of synthesized PbO were studied using X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and field emission scanning electron microscopy techniques. XRD results demonstrated the tetragonal phase of PbO with crystallite size of around 25 nm and strain of 3.6 × 10-3 calculated from Williamson-Hall plot. FESEM images manifested the formation of nanodiscs and nanoflowers with a diameter of around 300 nm and thickness of 50 nm. XPS spectra revealed the formation of PbO with photoelectron peak of Pb 4f and O 1 s lied at 137.68 and 529.96 eV. Moreover, FTIR spectrum exhibited Pb-O bond peak in the range of 400-530 cm-1.

Further testing and development of simulation models for UT inspections of armor

NASA Astrophysics Data System (ADS)

Margetan, Frank J.; Richter, Nathaniel; Thompson, R. Bruce

2012-05-01

In previous work we introduced an approach for simulating ultrasonic pulse/echo immersion inspections of multi-layer armor panels. Model inputs include the thickness, density, velocity and attenuation of each armor layer, the focal properties of the transducer, and a measured calibration signal. The basic model output is a response-versus-time waveform (ultrasonic A-scan) which includes echoes from all interfaces including those arising from reverberations within layers. Such A-scans can be predicted both for unflawed panels and panels containing a large disbond at any given interface. In this paper we continue our testing of the simulation software, applying it now to an armor panel consisting of SiC ceramic tiles fully embedded in a titanium-alloy matrix. An interesting specimen of such armor became available in which some tile/metal interfaces appear to be well bonded, while others have disbonded areas of various sizes. We compare measured and predicted A-scans for UT inspections, and also demonstrate an extension of the model to predict ultrasonic C-scans over regions containing a small, isolated disbond.

Ultrasonic level sensors for liquids under high pressure

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J.; Mazel, D. S.; Hodges, D. Y.

1986-01-01

An ultrasonic level sensor of novel design continuously measures the level of a liquid subjected to a high pressure (up to about 40 MPa), as is sometimes required for the effective transfer of the liquid. The sensor operates as a composite resonator fabricated from a standard high-pressure plug. A flat-bottom hole is machined into the plug along its center line. An ultrasonic transducer is bonded rigidly to the interior surface of the bottom wall, while the exterior surface is in contact with the liquid. Although the bottom wall is designed to satisfy the pressure code, it is still sufficiently thin to permit ready excitation of the axisymmetric plate modes of vibration. The liquid level is measured by a conventional pulse-echo technique. A prototype sensor was tested successfully in a 2300-l water vessel at pressures up to about 37 MPa. A spectral analysis of the transmitted pulse reveals that the flexural, extensional, thickness-shear, and radial plate modes are excited into vibration, but none of these appears to be significantly affected by the pressurization of the liquid.

Ultrasound-assisted chemoenzymatic epoxidation of soybean oil by using lipase as biocatalyst.

PubMed

Bhalerao, Machhindra S; Kulkarni, Vaishali M; Patwardhan, Anand V

2018-01-01

The present work reports the use of ultrasonic irradiation for enhancing lipase catalyzed epoxidation of soybean oil. Higher degree of unsaturated fatty acids, present in the soybean oil was converted to epoxidized soybean oil by using an immobilized lipase, Candida antarctica (Novozym 435). The effects of various parameters on the relative percentage conversion of the double bond to oxirane oxygen were investigated and the optimum conditions were established. The parameters studied were temperature, hydrogen peroxide to ethylenic unsaturation mole ratio, stirring speed, solvent ratio, catalyst loading, ultrasound frequency, ultrasound input power and duty cycle. The main objective of this work was to intensify chemoenzymatic epoxidation of the soybean oil by using ultrasound, to reduce the time required for epoxidation. Epoxidation of the soybean oil was achieved under mild reaction conditions by indirect ultrasonic irradiations (using ultrasonic bath). The relative percentage conversion to oxirane oxygen of 91.22% was achieved within 5h. The lipase was remarkably stable under optimized reaction conditions, later was recovered and reused six times to produce epoxidized soybean oil (ESO). Copyright © 2017 Elsevier B.V. All rights reserved.

Composite biaxially textured substrates using ultrasonic consolidation

DOEpatents

Blue, Craig A; Goyal, Amit

2013-04-23

A method of forming a composite sheet includes disposing an untextured metal or alloy first sheet in contact with a second sheet in an aligned opposing position; bonding the first sheet to the second sheet by applying an oscillating ultrasonic force to at least one of the first sheet and the second sheet to form an untextured intermediate composite sheet; and annealing the untextured intermediate composite sheet at a temperature lower than a primary re-crystallization temperature of the second sheet and higher than a primary re-crystallization temperature of the first sheet to convert the untextured first sheet into a cube textured sheet, wherein the cube texture is characterized by a .phi.-scan having a FWHM of no more than 15.degree. in all directions, the second sheet remaining untextured, to form a composite sheet.

Nondestructive testing of Scout rocket motors

NASA Technical Reports Server (NTRS)

Oaks, A. E.

1972-01-01

The nondestructive tests applied to Scout rocket motors were reviewed and appraised. Analytical techniques were developed to evaluate the capabilities of the radiographic and ultrasonic procedures used. Major problem areas found were the inadequacy of high voltage radiography for detecting unbonds and propellant cracks having narrow widths, the inability to relate the ultrasonic signals received from flat-bottomed holes in standards to those received from real defects and in the general area of the specification of acceptance criteria and how these were to be met. To counter the deficiencies noted, analyses were conducted to the potential utility of radiometric, acoustic, holographic and thermographic techniques for motor and nozzle bond inspection, a new approach to qualifying magnetic particle inspection and the application of acoustic emission analysis to the evaluation of proof and leak test data.

Ultrasonic Signal Processing for Structural Health Monitoring

NASA Astrophysics Data System (ADS)

Michaels, Jennifer E.; Michaels, Thomas E.

2004-02-01

Permanently mounted ultrasonic sensors are a key component of systems under development for structural health monitoring. Signal processing plays a critical role in the viability of such systems due to the difficulty in interpreting signals received from structures of complex geometry. This paper describes a differential feature-based approach to classifying signal changes as either "environmental" or "structural". Data are presented from piezoelectric discs bonded to an aluminum specimen subjected to both environmental changes and introduction of artificial defects. The classifier developed as part of this study was able to correctly identify artificial defects that were not part of the initial training and evaluation data sets. Central to the success of the classifier was the use of the Short Time Cross Correlation to measure coherency between the signal and reference as a function of time.

Nondestructive Evaluation Methods for the Ares I Common Bulkhead

NASA Technical Reports Server (NTRS)

Walker, James

2010-01-01

A large scale bonding demonstration test article was fabricated to prove out manufacturing techniques for the current design of the NASA Ares I Upper Stage common bulkhead. The common bulkhead serves as the single interface between the liquid hydrogen and liquid oxygen portions of the Upper Stage propellant tank. The bulkhead consists of spin-formed aluminum domes friction stir welded to Y-rings and bonded to a perforated phenolic honeycomb core. Nondestructive evaluation methods are being developed for assessing core integrity and the core-to-dome bond line of the common bulkhead. Detection of manufacturing defects such as delaminations between the core and face sheets as well as service life defects such as crushed or sheared core resulting from impact loading are all of interest. The focus of this work will be on the application of thermographic, shearographic, and phased array ultrasonic methods to the bonding demonstration article as well as various smaller test panels featuring design specific defect types and geometric features.

Measurements of the Young's modulus of hydroxide catalysis bonds, and the effect on thermal noise in ground-based gravitational wave detectors

NASA Astrophysics Data System (ADS)

Phelps, Margot; van Veggel, Anna-Maria; Hough, James; Messenger, Chris; Hughes, David; Cunningham, William; Haughian, Karen; Rowan, Sheila

2018-05-01

With the outstanding results from the detection and observation of gravitational waves from coalescing black holes and neutron star inspirals, it is essential that pathways to further improve the sensitivities of the LIGO and VIRGO detectors are explored. There are a number of factors that potentially limit the sensitivities of the detectors. One such factor is thermal noise, a component of which results from the mechanical loss in the bond material between the silica fibre suspensions and the test mass mirrors. To calculate its magnitude, the Young's modulus of the bond material has to be known with reasonable accuracy. In this paper we present a new combination of ultrasonic technology and Bayesian analysis to measure the Young's modulus of hydroxide catalysis bonds between fused silica substrates. Using this novel technique, we measure the bond Young's modulus to be 18.5 ±2.32.0 GPa . We show that by applying this value to thermal noise models of bonded test masses with suitable attachment geometries, a reduction in suspension thermal noise consistent with an overall design sensitivity improvement allows a factor of 5 increase in event rate to be achieved.

Fabrication and Characterization of Diffusion Bonds for Silicon Carbide

NASA Technical Reports Server (NTRS)

Halbig, Michael; Singh, Mrityunjay; Martin, Richard E.; Cosgriff, Laura M.

2007-01-01

Diffusion bonds of silicon carbide (SiC) were fabricated using several different types of titanium (Ti) based interlayers between the SiC substrates. The interlayers were an alloyed Ti foil, a pure Ti foil, and a physically vapor deposited (PVD) Ti coating. Microscopy was conducted to evaluate the cross-sections of the resulting bonds. Microprobe analysis identified reaction formed phases in the diffusion bonded region. Uniform and well adhered bonds were formed between the SiC substrates. In the case where the alloyed Ti foil or a thick Ti coating (i.e. 20 micron) was used as the interlayer, microcracks and several phases were present in the diffusion bonds. When a thinner interlayer was used (i.e. 10 micron PVD Ti), no microcracks were observed and only two reaction formed phases were present. The two phases were preferred and fully reacted phases that did not introduce thermal stresses or microcracks during the cool-down stage after processing. Diffusion bonded samples were evaluated with the non-destructive evaluation (NDE) methods of pulsed thermography and immersion ultrasonic testing. Joined SiC substrates that were fully bonded and that had simulated bond flaws in the interlayer were also evaluated using immersion ultrasound. Pull testing was conducted on the bonds to determine the tensile strength. To demonstrate the joining approach for a complex multilayered component for a low NOx injector application, the diffusion bonding approach was used to join three 4" diameter SiC discs that contained complex fuel and air flow channels.

Metal oxide, Group V-VI chalcogenides and GaN/AlGaN photodetectors

NASA Astrophysics Data System (ADS)

Hasan, Md. Rezaul

In this work, a simple, low-cost and catalyst free one-step solution processing of onedimensional Sb2S3 nanostructures on polyimide substrates was done. This structure demonstrated its potential application as a photoconductor in the UV and visible regime. Using-field emission scanning electron microscopy (SEM), grazing incidence X-Ray diffraction, Raman spectra and transmission electron microscopy measurements, it was shown that the Sb 2S3 films have high crystallinity, uniform morphology and nearstoichiometric composition. Further, using tauc plot, it was found that the films have a direct bandgap of 1.67 eV. MSM photodetectors, fabricated using these films showed a clear photo response in both UV as well as visible wavelength. These devices showed UV on/off ratio as high as 160 under the light intensity of 30 mW/cm2 and a small rise time and fall time of 44 ms 28 ms respectively. The effect of geometry of metal pad and bonding wire orientation of a multi-channel FET on the coupling of THz radiation was studied. The spatial variation images were taken by raster scan with the resolution of 0.07 mm steps in both x and y directions. An effective gate bias, where the effect of noise is minimum and photoresponse is maximum, was used for imaging. By applying VGS =-2.8V and VDS =380mV, the images were taken for all different combinations of activated bonding wires and metal pads. It was observed that, effect of bonding wire orientation is negligible for the large source pad as the radiation is coupled basically between drain and gate pad. Effect of drain bonding wire on coupling depends on the maximum width or diameter of metal pad and the incoming wavelength. In this work, Position of activated Drain pad and orientation of respective bonding wire defined the image tilting angle. Voltage drop across the shorting metal between drain pads, also played a role in increasing the asymmetry by selectively exciting a certain portion of FET Channels more than the other portion. Position of gate pad defined the center point of the image without tilting the image as the geometry of the gate pads were parallel to each other. And there was no effect of gate pad bonding wire orientation because of the larger width of gate pads. For the GaN/AlGaNHEMT, the effect of Al mole fraction in AlGaN layer and the effect of gate oxide on the DC and low frequency noise characterization was studied. MOSHEMT with SiO2 improved the Id(on)/I d(off) ratio up to more than 8 orders, while it is only 10 times in conventional HEMT. It was shown that the gate leakage and isolation leakage suppression efficiency improved dramatically with the oxide. Subthreshold swing (SS) of MOS-HEMTs with different Al mole fraction (from 20% to 35%) vary slightly from 72 mV/decade to 79 mV/decade, but the conventional GaN/AlGaN HEMT showed SS of 2.4V/decade. Low frequency noise study revealed the difference in transport mechanism between HEMT and MOS-HEMTs. By using Carrier Number Fluctuation (CNF) model on the measured data, it was found that the noise is predominantly coming from the surface states. While generation-recombination is very prominent in conventional HEMT, it is very weak and insignificant in both MOS-HEMTs at much higher frequencies. This study reveals that very high number of surface states assisting the tunneling in schottky/AlGaN barrier is responsible for unusually high leakage and higher noise level in conventional HEMT. Leakage level is improved from mA/mm range for HEMT to pA/mm range for MOS-HEMTs. Leakage suppression improvement and minimization of noise level can be mainly attributed to high quality SiO2. Hooge's constant was in the order of 5-6x10-3 in MOS-HEMTs, which is 5x10 -2 for conventional HEMT indicating much lower noise level in the MOS-HEMTs. (Abstract shortened by ProQuest.).

The role of functional monomers in bonding to enamel: acid-base resistant zone and bonding performance.

PubMed

Li, Na; Nikaido, Toru; Takagaki, Tomohiro; Sadr, Alireza; Makishi, Patricia; Chen, Jihua; Tagami, Junji

2010-09-01

To investigate the effects of two functional monomers on caries-inhibition potential and bond strength of two-step self-etching adhesive systems to enamel. Clearfil SE Bond and similar experimental formulations different in the functional monomer were used. Four combinations of primer and bonding agents were evaluated: (1) Clearfil SE Bond which contains MDP in both primer and bonding (M-M); (2) Clearfil SE Bond primer and Phenyl-P in bonding (M-P); (3) Phenyl-P in primer and Clearfil SE Bond bonding (P-M); (4) Phenyl-P in primer and bonding (P-P). Ground buccal enamel surfaces of human sound premolars were treated with one of the systems and the bonded interface was exposed to an artificial demineralising solution (pH 4.5) for 4.5 h, and then 5% NaOCl with ultrasonication for 30 min. After argon-ion etching, the interfacial ultrastructure was observed using SEM. Micro-shear bond strength to enamel was measured for all groups and results were analysed using one-way ANOVA and Turkey's HSD, while failure modes were analysed by chi-square test. An acid-base resistant zone (ABRZ) was found with all adhesive systems containing MDP either in primer or bond; however, ultramorphology and crystallite arrangement in the ABRZ were different among groups. P-P was the only group devoid of this protective zone. Micro-shear bond strength in M-M was significantly higher than those in M-P, P-M and P-P, while the latter three were not different from each other. Failure modes were significantly different (p<0.05). Functional monomers in two-step self-etching systems influence both the bonding performance and the formation of ABRZ on enamel. Copyright 2010 Elsevier Ltd. All rights reserved.

A cost-effective 25-Gb/s EML TOSA using all-in-one FPCB wiring and metal optical bench.

PubMed

Han, Young-Tak; Kwon, Oh-Kee; Lee, Dong-Hun; Lee, Chul-Wook; Leem, Young-Ahn; Shin, Jang-Uk; Park, Sang-Ho; Baek, Yongsoon

2013-11-04

We present a cost-effective 25-Gb/s electro-absorption modulator integrated laser (EML) transmitter optical sub-assembly (TOSA) using all-in-one flexible printed circuit board (FPCB) wiring and a metal optical bench (MOB). For a low cost and high bandwidth TOSA, internal and external wirings and feed-through of the TOSA to transmit radio-frequency (RF) signal are configured all-in-one using the FPCB. The FPCB is extended from an exterior of the TOSA package up to an EML chip inside the package through the slit formed on a rear sidewall of the package and die-bonded on the MOB. The EML TOSA shows a modulated output power of more than 3.5 dBm and a clear eye pattern with a dynamic extinction ratio of ~8.4 dB at a data rate of 25.78 Gb/s.

Two-probe STM experiments at the atomic level.

PubMed

Kolmer, Marek; Olszowski, Piotr; Zuzak, Rafal; Godlewski, Szymon; Joachim, Christian; Szymonski, Marek

2017-11-08

Direct characterization of planar atomic or molecular scale devices and circuits on a supporting surface by multi-probe measurements requires unprecedented stability of single atom contacts and manipulation of scanning probes over large, nanometer scale area with atomic precision. In this work, we describe the full methodology behind atomically defined two-probe scanning tunneling microscopy (STM) experiments performed on a model system: dangling bond dimer wire supported on a hydrogenated germanium (0 0 1) surface. We show that 70 nm long atomic wire can be simultaneously approached by two independent STM scanners with exact probe to probe distance reaching down to 30 nm. This allows direct wire characterization by two-probe I-V characteristics at distances below 50 nm. Our technical results presented in this work open a new area for multi-probe research, which can be now performed with precision so far accessible only by single-probe scanning probe microscopy (SPM) experiments.

Improvement of orthodontic friction by coating archwire with carbon nitride film

NASA Astrophysics Data System (ADS)

Wei, Songbo; Shao, Tianmin; Ding, Peng

2011-10-01

In order to reduce frictional resistance between archwire and bracket during orthodontic tooth movement, carbon nitride (CNx) thin films were deposited on the surface of archwires with ion beam assisted deposition (IBAD). The energy-dispersive X-ray spectrometer (EDS) analysis showed that the CNx film was successfully deposited on the surface of the orthodontic wires. X-ray photoelectron spectroscopy (XPS) analysis suggested that the deposited CNx film was sp 2 carbon dominated structures, and diversiform bonds (N sbnd C, N tbnd C, et al.) coexisted in the film. The friction tests indicated that the CNx film significantly reduced the wire-bracket friction both in ambient air and in artificial saliva. The sp 2C rich structure of the CNx film as well as its protection function for the archwire was responsible for the low friction of the wire-bracket sliding system.

IEEE 1988 International Symposium on Electromagnetic Compatibility, Seattle, WA, Aug. 2-4, 1988, Record

NASA Astrophysics Data System (ADS)

Various papers on electromagnetic compatibility are presented. Some of the optics considered include: field-to-wire coupling 1 to 18 GHz, SHF/EHF field-to-wire coupling model, numerical method for the analysis of coupling to thin wire structures, spread-spectrum system with an adaptive array for combating interference, technique to select the optimum modulation indices for suppression of undesired signals for simultaneous range and data operations, development of a MHz RF leak detector technique for aircraft harness surveillance, and performance of standard aperture shielding techniques at microwave frequncies. Also discussed are: spectrum efficiency of spread-spectrum systems, control of power supply ripple produced sidebands in microwave transistor amplifiers, an intership SATCOM versus radar electromagnetic interference prediction model, considerations in the design of a broadband E-field sensing system, unique bonding methods for spacecraft, and review of EMC practice for launch vehicle systems.

Adsorption and Reaction of Acetaldehyde on Shape-Controlled CeO2 Nanocrystals: Elucidation of Structure-function Relationships

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mann, Amanda K; Wu, Zili; Calaza, Florencia

2014-01-01

CeO2 cubes with {100} facets, octahedra with {111} facets, and wires with highly defective structures were utilized to probe the structure-dependent reactivity of acetaldehyde. Using temperature-programmed desorption (TPD), temperature-programmed surface reactions (TPSR), and in situ infrared spectroscopy it was found that acetaldehyde desorbs unreacted or undergoes reduction, coupling, or C-C bond scission reactions depending on the surface structure of CeO2. Room temperature FTIR indicates that acetaldehyde binds primarily as 1-acetaldehyde on the octahedra, in a variety of conformations on the cubes, including coupling products and acetate and enolate species, and primarily as coupling products on the wires. The percent consumptionmore » of acetaldehyde follows the order of wires > cubes > octahedra. All the nanoshapes produce the coupling product crotonaldehyde; however, the selectivity to produce ethanol follows the order wires cubes >> octahedra. The selectivity and other differences can be attributed to the variation in the basicity of the surfaces, defects densities, coordination numbers of surface atoms, and the reducibility of the nanoshapes.« less

Developments in GHz-ultrasonic interferometry for elasticity studies in geophysics and materials science: application to diamond

NASA Astrophysics Data System (ADS)

Chang, Y.; Jacobsen, S. D.; Holl, C. M.; Bina, C. R.

2009-12-01

Elastic properties of solids are fundamentally important in Earth and materials science because they govern seismic wave propagation at the geophysical scale, but are controlled at the atomic scale by the nature of interatomic bonding. GHz-ultrasonic interferometry utilizes thin-film piezoelectric transducers driven by pulse modulated, microwave-range carrier frequencies at 0.5-2.0 GHz to measure sound wave travel times in sub-millimeter sized samples (Spetzler et al. 1993). Travel times are determined from the spacing of interference fringes produced by measuring the amplitude of overlapping echoes scanned in frequency (wavelength) from opposite polished faces of single crystals. The ultrasonic signals are near-optical in wavelength at 5-20 km/s in high-modulus materials, allowing study of samples as small as a few tens of micrometers in thickness, including micro-crystals loaded in diamond-anvil cells at high pressures and temperatures. Following Jacobsen et al. (2004), both longitudinal and shear-wave measurements are possible. Although relative changes in travel time on compression or heating are measured with standard deviation of about 0.02 nanoseconds out of 20-200 ns (depending on sample thickness), the absolute accuracy of ultrasonic measurements at standard conditions, required to anchor high P-T measurements, has been limited by our ability to measure sample thickness mechanically at STP, with only 1-2 micrometer accuracy out of 20-200 μm for typical samples. Thus, we have recently installed a commercial heterodyne optical interferometer to determine ultrasonic sample lengths at STP conditions. Using a double-pass laser interferometer we achieve λ/4 fundamental optical resolution with λ/128 (about 5 nm) system resolution through software-based interpolation. By adding real-time corrections for air temperature, humidity, and pressure applied to the laser wavelength, we achieve high accuracy with standard deviations of about 0.02 micrometers in the thickness measurements. Using this new setup, we determined the C11 and C44 elastic constants of natural type IIA single-crystal diamond with unprecedented precision: C11 = 1076.2(6) GPa and C44 = 575.8(4) GPa, improving the reported uncertainty in moduli of diamond by about one order of magnitude over previous ultrasonic measurements (e.g. McSkimin and Bond 1957). This technique will allow us to ascertain whether or not reported variability in elastic properties various forms of synthetic diamond are significant. We plan to use the instrument to study both natural and synthetic diamond elasticity and variations in equations of state with defect structure and pressure, as well as other superhard materials intended for use in future societal applications.

Effect of ultrasonic degradation of hyaluronic acid extracted from rooster comb on antioxidant and antiglycation activities.

PubMed

Hafsa, Jawhar; Chaouch, Mohamed Aymen; Charfeddine, Bassem; Rihouey, Christophe; Limem, Khalifa; Le Cerf, Didier; Rouatbi, Sonia; Majdoub, Hatem

2017-12-01

Recently, low-molecular-weight hyaluronic acid (LMWHA) has been reported to have novel features, such as free radical scavenging activities, antioxidant activities and dietary supplements. In this study, hyaluronic acid (HA) was extracted from rooster comb and LMWHA was obtained by ultrasonic degradation in order to assess their antioxidant and antiglycation activities. Molecular weight (Mw) and the content of glucuronic acid (GlcA) were used as the index for comparison of the effect of ultrasonic treatment. The effects on the structure were determined by ultraviolet (UV) spectra and Fourier transform infrared spectra (FTIR). The antioxidant activity was determined by three analytical assays (DPPH, NO and TBARS), and the inhibitory effect against glycated-BSA was also assessed. The GlcA content of HA and LMWHA was estimated at about 48.6% and 47.3%, respectively. The results demonstrate that ultrasonic irradiation decreases the Mw (1090-181 kDa) and intrinsic viscosity (1550-473 mL/g), which indicate the cleavage of the glycosidic bonds. The FTIR and UV spectra did not significantly change before and after degradation. The IC 50 value of HA and LWMHA was 1.43, 0.76 and 0.36 mg/mL and 1.20, 0.89 and 0.17 mg/mL toward DPPH, NO and TBARS, respectively. Likewise LMWHA exhibited significant inhibitory effects on the AGEs formation than HA. The results demonstrated that the ultrasonic irradiation did not damage and change the chemical structure of HA after degradation; furthermore, decreasing Mw and viscosity of LMWHA after degradation may enhance the antioxidant and antiglycation activity.

Acoustic backing in 3-D integration of CMUT with front-end electronics.

PubMed

Berg, Sigrid; Rønnekleiv, Arne

2012-07-01

Capacitive micromachined ultrasonic transducers (CMUTs) have shown promising qualities for medical imaging. However, there are still some problems to be investigated, and some challenges to overcome. Acoustic backing is necessary to prevent SAWs excited in the surface of the silicon substrate from affecting the transmit pattern from the array. In addition, echoes resulting from bulk waves in the substrate must be removed. There is growing interest in integrating electronic circuits to do some of the beamforming directly below the transducer array. This may be easier to achieve for CMUTs than for traditional piezoelectric transducers. We will present simulations showing that the thickness of the silicon substrate and thicknesses and acoustic properties of the bonding material must be considered, especially when designing highfrequency transducers. Through simulations, we compare the acoustic properties of 3-D stacks bonded with three different bonding techniques; solid-liquid interdiffusion (SLID) bonding, direct fusion bonding, and anisotropic conductive adhesives (ACA). We look at a CMUT array with a center frequency of 30 MHz and three silicon wafers underneath, having a total silicon thickness of 100 μm. We find that fusion bonding is most beneficial if we want to prevent surface waves from damaging the array response, but SLID and ACA are also promising if bonding layer thicknesses can be reduced.

Ultrasonic Nondestructive Characterization of Adhesive Bonds

NASA Technical Reports Server (NTRS)

Qu, Jianmin

1997-01-01

Qualitative measurements of adhesion or binding forces can be accomplished, for example, by using the reflection coefficient of an ultrasound or by using thermal waves (Light and Kwun, 1989, Achenbach and Parikh, 1991, and Bostrom and wickham, 1991). However, a quantitative determination of binding forces is rather difficult. It has been observed that higher harmonics of the fundamental frequency are generated when an ultrasound passes through a nonlinear material. It seems that such non-linearity can be effectively used to characterize the bond strength. Several theories have been developed to model this nonlinear effect (Adler and Nagy, 1991; Achenbach and Parikh, 1991; Parikh and Achenbach, 1992; and Hirose and Kitahara, 1992; Anastasi and Roberts, 1992). Based on a microscopic description of the nonlinear interface binding force, a quantitative method was presented by Pangraz and Arnold (1994). Recently, Tang, Cheng and Achenbach (1997) made a comparison between the experimental and simulated results based on this theoretical model. A water immersion mode-converted shear wave through-transmission setup was used by Berndt and Green (1997) to analyze the nonlinear acoustic behavior of the adhesive bond. In this project, the nonlinear responses of an adhesive joint was investigated through transmission tests of ultrasonic wave and analyzed by the finite element simulations. The higher order harmonics were obtained in the tests. It is found that the amplitude of higher harmonics increases as the aging increases, especially the 3dorder harmonics. Results from the numerical simulation show that the material nonlinearity does indeed generate higher order harmonics. In particular, the elastic-perfect plastic behavior generates significant 3rd and 5th order harmonics.

Mutual mother-infant recognition in mice: The role of pup ultrasonic vocalizations.

PubMed

Mogi, Kazutaka; Takakuda, Ayaka; Tsukamoto, Chihiro; Ooyama, Rumi; Okabe, Shota; Koshida, Nobuyoshi; Nagasawa, Miho; Kikusui, Takefumi

2017-05-15

The importance of the mother-infant bond for the development of offspring health and sociality has been studied not only in primate species but also in rodent species. A social bond is defined as affiliative behaviors toward a specific partner. However, controversy remains concerning whether mouse pups can distinguish between their own mother and an alien mother, and whether mothers can differentiate their own pups from alien pups. In this study, we investigated whether mutual recognition exists between mother and infant in ICR mice. Furthermore, we studied pup ultrasonic vocalizations (USVs), which are emitted by pups when isolated from their mothers, to determine whether they constituted an individual signature used by the mother for pup recognition. We conducted a variety of two-choice tests and selective-retrieving tests. In a two-choice test for mother recognition by the pup, pups between the ages of 17 and 21days preferred their own mothers to alien mothers. In a two-choice test for pup recognition by its mother, the mothers located their own pups faster than alien pups at the beginning of the test, yet displayed similar retrieving activity for both their own and alien pups in the subsequent selective-retrieving test. Furthermore, after recording USVs from pups from subject and alien mothers, then playing them simultaneously, subject mothers displayed a preference for pup USVs emitted by their own pups. Overall, our findings support the existence of mother-infant bonding in mice and suggest that pup USVs contribute to pup recognition by mothers. Copyright © 2016. Published by Elsevier B.V.

Electromagnetically Clean Solar Arrays

NASA Technical Reports Server (NTRS)

Stem, Theodore G.; Kenniston, Anthony E.

2008-01-01

The term 'electromagnetically clean solar array' ('EMCSA') refers to a panel that contains a planar array of solar photovoltaic cells and that, in comparison with a functionally equivalent solar-array panel of a type heretofore used on spacecraft, (1) exhibits less electromagnetic interferences to and from other nearby electrical and electronic equipment and (2) can be manufactured at lower cost. The reduction of electromagnetic interferences is effected through a combination of (1) electrically conductive, electrically grounded shielding and (2) reduction of areas of current loops (in order to reduce magnetic moments). The reduction of cost is effected by designing the array to be fabricated as a more nearly unitary structure, using fewer components and fewer process steps. Although EMCSAs were conceived primarily for use on spacecraft they are also potentially advantageous for terrestrial applications in which there are requirements to limit electromagnetic interference. In a conventional solar panel of the type meant to be supplanted by an EMCSA panel, the wiring is normally located on the back side, separated from the cells, thereby giving rise to current loops having significant areas and, consequently, significant magnetic moments. Current-loop geometries are chosen in an effort to balance opposing magnetic moments to limit far-0field magnetic interactions, but the relatively large distances separating current loops makes full cancellation of magnetic fields problematic. The panel is assembled from bare photovoltaic cells by means of multiple sensitive process steps that contribute significantly to cost, especially if electomagnetic cleanliness is desired. The steps include applying a cover glass and electrical-interconnect-cell (CIC) sub-assemble, connecting the CIC subassemblies into strings of series-connected cells, laying down and adhesively bonding the strings onto a panel structure that has been made in a separate multi-step process, and mounting the wiring on the back of the panel. Each step increases the potential for occurrence of latent defects, loss of process control, and attrition of components. An EMCSA panel includes an integral cover made from a transparent material. The silicone cover supplants the individual cover glasses on the cells and serves as an additional unitary structural support that offers the advantage, relative to glass, of the robust, forgiving nature of the silcone material. The cover contains pockets that hold the solar cells in place during the lamination process. The cover is coated with indium tin oxide to make its surface electrically conductive, so that it serves as a contiguous, electrically grounded shield over the entire panel surface. The cells are mounted in proximity to metallic printed wiring. The painted-wiring layer comprises metal-film traces on a sheet of Kapton (or equivalent) polyimide. The traces include contact pads on one side of the sheet for interconnecting the cells. Return leads are on the opposite side of the sheet, positioned to form the return currents substantially as mirror images of, and in proximity to, the cell sheet currents, thereby minimizing magnetic moments. The printed-wiring arrangement mimics the back-wiring arrangement of conventional solar arrays, but the current-loop areas and the resulting magnetic moments are much smaller because the return-current paths are much closer to the solar-cell sheet currents. The contact pads are prepared with solder fo electrical and mechanical bonding to the cells. The pocketed cover/shield, the solar cells, the printed-wiring layer, an electrical bonding agent, a mechanical-bonding agent, a composite structural front-side face sheet, an aluminum honeycomb core, and a composite back-side face sheet are all assembled, then contact pads are soldered to the cells and the agents are cured in a single lamination process.

Nondestructive evaluation of defects in carbon fiber reinforced polymer (CFRP) composites

NASA Astrophysics Data System (ADS)

Ngo, Andrew C. Y.; Goh, Henry K. H.; Lin, Karen K.; Liew, W. H.

2017-04-01

Carbon fiber reinforced polymer (CFRP) composites are increasingly used in aerospace applications due to its superior mechanical properties and reduced weight. Adhesive bonding is commonly used to join the composite parts since it is capable of joining incompatible or dissimilar components. However, insufficient adhesive or contamination in the adhesive bonds might occur and pose as threats to the integrity of the plane during service. It is thus important to look for suitable nondestructive testing (NDT) techniques to detect and characterize the sub-surface defects within the CFRP composites. Some of the common NDT techniques include ultrasonic techniques and thermography. In this work, we report the use of the abovementioned techniques for improved interpretation of the results.

Detection of thermally grown oxides in thermal barrier coatings by nondestructive evaluation

NASA Astrophysics Data System (ADS)

Fahr, A.; Rogé, B.; Thornton, J.

2006-03-01

The thermal-barrier coatings (TBC) sprayed on hot-section components of aircraft turbine engines commonly consist of a partially stabilized zirconia top-coat and an intermediate bond-coat applied on the metallic substrate. The bond-coat is made of an aluminide alloy that at high engine temperatures forms thermally grown oxides (TGO). Although formation of a thin layer of aluminum oxide at the interface between the ceramic top-coat and the bond-coat has the beneficial effect of protecting the metallic substrate from hot gases, oxide formation at splat boundaries or pores within the bond-coat is a source of weakness. In this study, plasma-sprayed TBC specimens are manufactured from two types of bond-coat powders and exposed to elevated temperatures to form oxides at the ceramic-bond-coat boundary and within the bond-coat. The specimens are then tested using nondestructive evaluation (NDE) and destructive metallography and compared with the as-manufactured samples. The objective is to determine if NDE can identify the oxidation within the bond-coat and give indication of its severity. While ultrasonic testing can provide some indication of the degree of bond-coat oxidation, the eddy current (EC) technique clearly identifies severe oxide formation within the bond-coat. Imaging of the EC signals as the function of probe location provides information on the spatial variations in the degree of oxidation, and thereby identifies which components or areas are prone to premature damage.

KSC-05PD-0730

NASA Technical Reports Server (NTRS)

2005-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility at NASAs Kennedy Space Center, United Space Alliance tile technician Jimmy Carter works on instrument wire spot bonding on Atlantis vertical tail/rudder speed brake. Atlantis is being processed for launch on the second Return to Flight mission, STS-121, which is scheduled to fly in July.

KSC-05PD-0731

NASA Technical Reports Server (NTRS)

2005-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility at NASAs Kennedy Space Center, United Space Alliance tile technician Jimmy Carter works on instrument wire spot bonding on Atlantis vertical tail/rudder speed brake. Atlantis is being processed for launch on the second Return to Flight mission, STS-121, which is scheduled to fly in July.

Embedded Ultrasonics for SHM of Space Applications

DTIC Science & Technology

2012-07-30

information on material properties and other forms of damage such as cracks, structural fatigue and/or impact events. This synergistic aspect of the embedded...larger the phase shift. However, high excitation levels could contribute to sensor fatigue and levels in a range 15 to 20 (110 to 130 volts) are...joints each featuring three bolts. Piezoelectric wafers ( PZT ) with UNF electrodes were bonded to the isogrid panels using 3M 2216 epoxy

Resistance welding graphite-fiber composites

NASA Technical Reports Server (NTRS)

Lamoureux, R. T.

1980-01-01

High-strength joints are welded in seconds in carbon-reinfored thermoplastic beams. Resistance-welding electrode applies heat and pressure to joint and is spring-loaded to follow softening material to maintain contact; it also holds parts together for cooling and hardening. Both transverse and longitudinal configurations can be welded. Adhesive bonding and encapsulation are more time consuming methods and introduce additional material into joint, while ultrasonic heating can damage graphite fibers in composite.

An energy harvesting type ultrasonic motor.

PubMed

Wang, Guangqing; Xu, Wentan; Gao, Shuaishuai; Yang, Binqiang; Lu, Guoli

2017-03-01

An energy harvesting type ultrasonic motor is presented in this work. The novel motor not only can drive and/or position the motion mechanism, but also can harvest and convert the vibration-induced energy of the stator into electric energy to power small electronic devices. In the new motor, the stator is a sandwich structure of two PZT rings and an elastic metal body. The PZT ring bonded on the bottom surface is used to excite the stator metal body to generate a traveling wave with converse piezoelectric effect, and the other PZT ring bonded on top surface is used to harvest and convert the vibration-induced energy of the stator into electric energy with direct piezoelectric effect. Finite element method is adopted to analyze the vibration characteristics and the energetic characteristic. After the fabrication of a prototype, the mechanical output and electric energy output abilities are measured. The maximum no-load speed and maximum output torque of the prototype are 117rpm and 0.65Nm at an exciting voltage with amplitude of 134 V p-p and frequency of 40kHz, and the maximum harvesting output power of per sector area of the harvesting PZT is 327mW under an optimal equivalent load resistance of 6.9kΩ. Copyright © 2016 Elsevier B.V. All rights reserved.

Manufacturing and testing VLPC hybrids

NASA Astrophysics Data System (ADS)

Adkins, L. R.; Ingram, C. M.; Anderson, E. J.

1998-11-01

To insure that the manufacture of VLPC devices is a reliable, cost-effective technology, hybrid assembly procedures and testing methods suitable for large scale production have been developed. This technology has been developed under a contract from Fermilab as part of the D-Zero upgrade program. Each assembled hybrid consists of a VLPC chip mounted on an AlN substrate. The VLPC chip is provided with bonding pads (one connected to each pixel) which are wire bonded to gold traces on the substrate. The VLPC/AlN hybrids are mated in a vacuum sealer using solder preforms and a specially designed carbon boat. After mating, the VLPC pads are bonded to the substrate with an automatic wire bonder. Using this equipment we have achieved a thickness tolerance of ±0.0007 inches and a production rate of 100 parts per hour. After assembly the VLPCs are tested for optical response at an operating temperature of 7K. The parts are tested in a custom designed continuous-flow dewar with a capacity 15 hybrids, and one Lake Shore DT470-SD-11 calibrated temperature sensor mounted to an AlN substrate. Our facility includes five of these dewars with an ultimate test capacity of 75 parts per day. During the course of the Dzero program we have assembled more than 4,000 VLPC hybrids and have tested more than 2,500 with a high yield.

AIN-Based Packaging for SiC High-Temperature Electronics

NASA Technical Reports Server (NTRS)

Savrun, Ender

2004-01-01

Packaging made primarily of aluminum nitride has been developed to enclose silicon carbide-based integrated circuits (ICs), including circuits containing SiC-based power diodes, that are capable of operation under conditions more severe than can be withstood by silicon-based integrated circuits. A major objective of this development was to enable packaged SiC electronic circuits to operate continuously at temperatures up to 500 C. AlN-packaged SiC electronic circuits have commercial potential for incorporation into high-power electronic equipment and into sensors that must withstand high temperatures and/or high pressures in diverse applications that include exploration in outer space, well logging, and monitoring of nuclear power systems. This packaging embodies concepts drawn from flip-chip packaging of silicon-based integrated circuits. One or more SiC-based circuit chips are mounted on an aluminum nitride package substrate or sandwiched between two such substrates. Intimate electrical connections between metal conductors on the chip(s) and the metal conductors on external circuits are made by direct bonding to interconnections on the package substrate(s) and/or by use of holes through the package substrate(s). This approach eliminates the need for wire bonds, which have been the most vulnerable links in conventional electronic circuitry in hostile environments. Moreover, the elimination of wire bonds makes it possible to pack chips more densely than was previously possible.

Method for Surface Texturing Titanium Products

NASA Technical Reports Server (NTRS)

Banks, Bruce A. (Inventor)

1998-01-01

The present invention teaches a method of producing a textured surface upon an arbitrarily configured titanium or titanium alloy object for the purpose of improving bonding between the object and other materials such as polymer matrix composites and/or human bone for the direct in-growth of orthopaedic implants. The titanium or titanium alloy object is placed in an electrolytic cell having an ultrasonically agitated solution of sodium chloride therein whereby a pattern of uniform "pock mark" like pores or cavities are produced upon the object's surface. The process is very cost effective compared to other methods of producing rough surfaces on titanium and titanium alloy components. The surface textures produced by the present invention are etched directly into the parent metal at discrete sites separated by areas unaffected by the etching process. Bonding materials to such surface textures on titanium or titanium alloy can thus support a shear load even if adhesion of the bonding material is poor.

Fatigue disbonding analysis of wide composite panels by means of Lamb waves

NASA Astrophysics Data System (ADS)

Michalcová, Lenka; Rechcígel, Lukáš; Bělský, Petr; Kucharský, Pavel

2018-03-01

Guided wave-based monitoring of composite structures plays an important role in the area of structural health monitoring (SHM) of aerospace structures. Adhesively bonded joints have not yet fulfilled current airworthiness requirements; hence, assemblies of carbon fibre-reinforced parts still require mechanical fasteners, and a verified SHM method with reliable disbonding/delamination detection and propagation assessment is needed. This study investigated the disbonding/delamination propagation in adhesively bonded panels using Lamb waves during fatigue tests. Analyses focused on the proper frequency and mode selection, sensor placement and selection of parameter sensitive to the growth of disbonding areas. Piezoelectric transducers placed across the bonded area were used as actuators and sensors. Lamb wave propagation was investigated considering the actual shape of the crack front and the mode of the crack propagation. The actual cracked area was determined by ultrasonic A-scans. A correlation between the crack propagation rate and the A0 mode velocity was found.

The use of plastic optical fibres and shape memory alloys for damage assessment and damping control in composite materials

NASA Astrophysics Data System (ADS)

Kuang, K. S. C.; Cantwell, W. J.

2003-08-01

This paper reports the use of a plastic fibre sensor for detecting impact damage in carbon fibre epoxy cantilever beams by monitoring their damping response under free vibration loading conditions. The composite beams were impacted at impact energies up to 8 J. The residual strengths and stiffnesses of the damaged laminates were measured in order to relate reductions in their mechanical properties to changes in their damping characteristics. Here, optical fibre sensors were surface bonded to carbon fibre composite beams which were subjected to free vibration tests to monitor their dynamic response. In the second part of this study, Ni-Ti shape memory alloy (SMA) wires were employed to control and modify the damping response of a composite beam. The SMA wires were initially trained to obtain the desired shape when activated. Here, the trained SMA wires were heated locally using a nickel/chromium wire that was wrapped around the trained region of the SMA. By using this method to activate the SMA wire (as opposed to direct electrical heating), it is possible to obtain localized actuation without heating the entire length of the wire. This procedure minimizes any damage to the host material that may result from local heat transfer between the SMA wire and the composite structure. In addition, the reduction in power requirements to achieve SMA activation permits the use of small-size power packs which can in turn lead to a potential weight reduction in weight-critical applications. The findings of this study demonstrate that a trained SMA offers a superior damping capability to that exhibited by an 'as-supplied' flat-annealed wire.

Monolithic CMUT-on-CMOS integration for intravascular ultrasound applications.

PubMed

Zahorian, Jaime; Hochman, Michael; Xu, Toby; Satir, Sarp; Gurun, Gokce; Karaman, Mustafa; Degertekin, F Levent

2011-12-01

One of the most important promises of capacitive micromachined ultrasonic transducer (CMUT) technology is integration with electronics. This approach is required to minimize the parasitic capacitances in the receive mode, especially in catheter-based volumetric imaging arrays, for which the elements must be small. Furthermore, optimization of the available silicon area and minimized number of connections occurs when the CMUTs are fabricated directly above the associated electronics. Here, we describe successful fabrication and performance evaluation of CMUT arrays for intravascular imaging on custom-designed CMOS receiver electronics from a commercial IC foundry. The CMUT-on-CMOS process starts with surface isolation and mechanical planarization of the CMOS electronics to reduce topography. The rest of the CMUT fabrication is achieved by modifying a low-temperature micromachining process through the addition of a single mask and developing a dry etching step to produce sloped sidewalls for simple and reliable CMUT-to-CMOS interconnection. This CMUT-to-CMOS interconnect method reduced the parasitic capacitance by a factor of 200 when compared with a standard wire-bonding method. Characterization experiments indicate that the CMUT-on-CMOS elements are uniform in frequency response and are similar to CMUTs simultaneously fabricated on standard silicon wafers without electronics integration. Ex- periments on a 1.6-mm-diameter dual-ring CMUT array with a center frequency of 15 MHz show that both the CMUTs and the integrated CMOS electronics are fully functional. The SNR measurements indicate that the performance is adequate for imaging chronic total occlusions located 1 cm from the CMUT array.

Sol-gel approach for fabrication of coated anodized titanium wire for solid-phase microextraction: highly efficient adsorbents for enrichment of trace polar analytes.

PubMed

Jia, Jing; Xu, Lili; Wang, Shuai; Wang, Licheng; Liu, Xia

2014-05-01

Nanotubular titania film was prepared in situ on titanium wire and was used as the fiber substrate for solid-phase microextraction (SPME) because of its high surface-to-volume ratio, easy preparation, and mechanical stability. Three different functional coatings, β-cyclodextrin (β-CD), β-cyclodextrin-co-poly(ethylenepropylene glycol) (β-CD/PEG), and polyethylene glycol (PEG)-based sorbents were chemically bonded to the nanostructured wire surface via sol-gel technology to further enhance the absorbing capability and extraction selectivity. Coupled to gas chromatography-flame ionic detection (GC-FID), the prepared SPME fibers were investigated using diverse compounds. The results indicated that the fibers showed good mechanical strength, excellent thermal stability, and wonderful capacity and selectivity to polar compounds, including polar aromatic compounds, alcohols, and ketones. Combining the superior hydrophilic property of a bonded functional molecule and the highly porous structure of a fiber coating, the prepared PEG-coated SPME fiber showed much higher adsorption affinity to ephedrine and methylephedrine than β-CD and β-CD/PEG fibers. The as-established PEG-coated SPME-GC analytical method provided excellent sensitivity (LODs, 0.004 and 0.001 ng mL(-1) for ephedrine and methylephedrine, respectively) and better linear range (0.01-2 000 μg L(-1)). In addition, it has surprising repeatability and reproducibility. Finally, the present approach was used to analyze ephedrine and methylephedrine from real urine samples, and reliable results were obtained.

The increase in conductance of a gold single atom chain during elastic elongation

NASA Astrophysics Data System (ADS)

Tavazza, F.; Barzilai, S.; Smith, D. T.; Levine, L. E.

2013-02-01

The conductance of monoatomic gold wires has been studied using ab initio calculations and the transmission was found to vary with the elastic strain. Counter-intuitively, the conductance was found to increase for the initial stages of the elongation, where the structure has a zigzag shape and the bond angles increase from ≈140° toward ≈160°. After a certain elongation limit, where the angles are relatively high, the bond length elongation associated with a Peierls distortion reverses this trend and the conductance decreases. These simulations are in good agreement with previously unexplained experimental results.

Adaptation of ion beam technology to microfabrication of solid state devices and transducers

NASA Technical Reports Server (NTRS)

Topich, J. A.

1977-01-01

It was found that ion beam texturing of silicon surfaces can be used to increase the effective surface area of MOS capacitors. There is, however, a problem with low dielectric breakdown. Preliminary work was begun on the fabrication of ion implanted resistors on textured surfaces and the potential improvement of wire bond strength by bonding to a textured surface. In the area of ion beam sputtering, the techniques for sputtering PVC were developed. A PVC target containing valinomycin was used to sputter an ion selective membrane on a field effect transistor to form a potassium ion sensor.

High density pixel array

NASA Technical Reports Server (NTRS)

McFall, James Earl (Inventor); Wiener-Avnear, Eliezer (Inventor)

2004-01-01

A pixel array device is fabricated by a laser micro-milling method under strict process control conditions. The device has an array of pixels bonded together with an adhesive filling the grooves between adjacent pixels. The array is fabricated by moving a substrate relative to a laser beam of predetermined intensity at a controlled, constant velocity along a predetermined path defining a set of grooves between adjacent pixels so that a predetermined laser flux per unit area is applied to the material, and repeating the movement for a plurality of passes of the laser beam until the grooves are ablated to a desired depth. The substrate is of an ultrasonic transducer material in one example for fabrication of a 2D ultrasonic phase array transducer. A substrate of phosphor material is used to fabricate an X-ray focal plane array detector.

Antenna coupling explains unintended thermal injury caused by common operating room monitoring devices.

PubMed

Townsend, Nicole T; Jones, Edward L; Paniccia, Alessandro; Vandervelde, Joel; McHenry, Jennifer R; Robinson, Thomas N

2015-04-01

Unintended thermal injury from patient monitoring devices (eg, electrocardiogram pads, neuromonitoring leads) results in third-degree burns. A mechanism for these injuries is not clear. The monopolar "bovie" emits radiofrequency energy that transfers to nearby, nonelectrically active cables or wires without direct contact by capacitive and antenna coupling. The purpose of this study was to determine if, and to what extent, radiofrequency energy couples to common patient monitoring devices. In an ex vivo porcine model, monopolar radiofrequency energy was delivered to a handheld "bovie" pencil. Nonelectrically active neuromonitoring and cardiac-monitoring leads were placed in proximity to the monopolar pencil and its cord. Temperature changes of tissue touched by the monitoring lead were measured using a thermal camera immediately after a 5-second activation. The energy-device cords were then separated by 15 cm, the power was reduced from 30 W coag to 15 W coag and different cord angulation was tested. An advanced bipolar device, a plasma-based device, and an ultrasonic device were also tested at standard settings. The neuromonitoring lead increased tissue temperature at the insertion site by 39 ± 13°C (P<0.001) creating visible char at the skin. The electrocardiogram lead raised tissue temperature by 1.3 ± 0.5°C (P<0.001). Decreasing generator power from 30 W to 15 W and separating the bovie cord from the neuromonitoring cord by 15 cm significantly reduced the temperature change (39 ± 13°C vs. 26±5°C; P<0.001 and 39 ± 13°C vs. 10 ± 5°C; P<0.001, respectively). Lastly, monopolar energy increased tissue temperatures significantly more than argon beam energy (34 ± 15°C), advanced bipolar energy (0.2 ± 0.4°C), and ultrasonic energy (0 ± 0.3°C) (all P<0.001). Stray energy couples to commonly used patient monitoring devices resulting in potentially significant thermal injury. The handheld bovie cord transfers energy via antenna coupling to neuromonitoring leads that can raise tissue temperatures over 100°F (39°C) using standard settings. The most effective ways to decrease this energy coupling is to reduce generator power, increase the separation between wires, or utilize lower voltage energy devices such as ultrasonic or bipolar energy.

A study on the compatibility between one-bottle dentin adhesives and composite resins using micro-shear bond strength.

PubMed

Song, Minju; Shin, Yooseok; Park, Jeong-Won; Roh, Byoung-Duck

2015-02-01

This study was performed to determine whether the combined use of one-bottle self-etch adhesives and composite resins from same manufacturers have better bond strengths than combinations of adhesive and resins from different manufacturers. 25 experimental micro-shear bond test groups were made from combinations of five dentin adhesives and five composite resins with extracted human molars stored in saline for 24 hr. Testing was performed using the wire-loop method and a universal testing machine. Bond strength data was statistically analyzed using two way analysis of variance (ANOVA) and Tukey's post hoc test. Two way ANOVA revealed significant differences for the factors of dentin adhesives and composite resins, and significant interaction effect (p < 0.001). All combinations with Xeno V (Dentsply De Trey) and Clearfil S(3) Bond (Kuraray Dental) adhesives showed no significant differences in micro-shear bond strength, but other adhesives showed significant differences depending on the composite resin (p < 0.05). Contrary to the other adhesives, Xeno V and BondForce (Tokuyama Dental) had higher bond strengths with the same manufacturer's composite resin than other manufacturer's composite resin. Not all combinations of adhesive and composite resin by same manufacturers failed to show significantly higher bond strengths than mixed manufacturer combinations.

Fundamental phenomena on fuel decomposition and boundary-layer combustion processes with applications to hybrid rocket motors

NASA Technical Reports Server (NTRS)

Kuo, Kenneth K.; Lu, Yeu-Cherng; Chiaverini, Martin J.; Harting, George C.; Johnson, David K.; Serin, Nadir

1995-01-01

The experimental study on the fundamental processes involved in fuel decomposition and boundary-layer combustion in hybrid rocket motors is continuously being conducted at the High Pressure Combustion Laboratory of The Pennsylvania State University. This research will provide a useful engineering technology base in the development of hybrid rocket motors as well as a fundamental understanding of the complex processes involved in hybrid propulsion. A high-pressure, 2-D slab motor has been designed, manufactured, and utilized for conducting seven test firings using HTPB fuel processed at PSU. A total of 20 fuel slabs have been received from the Mcdonnell Douglas Aerospace Corporation. Ten of these fuel slabs contain an array of fine-wire thermocouples for measuring solid fuel surface and subsurface temperatures. Diagnostic instrumentation used in the test include high-frequency pressure transducers for measuring static and dynamic motor pressures and fine-wire thermocouples for measuring solid fuel surface and subsurface temperatures. The ultrasonic pulse-echo technique as well as a real-time x-ray radiography system have been used to obtain independent measurements of instantaneous solid fuel regression rates.

Toward a reduced-wire readout system for ultrasound imaging.

PubMed

Lim, Jaemyung; Arkan, Evren F; Degertekin, F Levent; Ghovanloo, Maysam

2014-01-01

We present a system-on-a-chip (SoC) for use in high-frequency capacitive micromachined ultrasonic transducer (CMUT) imaging systems. This SoC consists of trans-impedance amplifiers (TIA), delay locked loop (DLL) based clock multiplier, quadrature sampler, and pulse width modulator (PWM). The SoC down converts RF echo signal to baseband by quadrature sampling which facilitates modulation. To send data through a 1.6 m wire in the catheter which has limited bandwidth and is vulnerable to noise, the SoC creates a pseudo-digital PWM signal which can be used for back telemetry or wireless readout of the RF data. In this implementation, using a 0.35-μm std. CMOS process, the TIA and single-to-differential (STD) converter had 45 MHz bandwidth, the quadrature sampler had 10.1 dB conversion gain, and the PWM had 5-bit ENoB. Preliminary results verified front-end functionality, and the power consumption of a TIA, STD, quadrature sampler, PWM, and clock multiplier was 26 mW from a 3 V supply.

Toward a Reduced-Wire Readout System for Ultrasound Imaging

PubMed Central

Lim, Jaemyung; Arkan, Evren F.; Degertekin, F. Levent; Ghovanloo, Maysam

2015-01-01

We present a system-on-a-chip (SoC) for use in high-frequency capacitive micromachined ultrasonic transducer (CMUT) imaging systems. This SoC consists of trans-impedance amplifiers (TIA), delay locked loop (DLL) based clock multiplier, quadrature sampler, and pulse width modulator (PWM). The SoC down converts RF echo signal to baseband by quadrature sampling which facilitates modulation. To send data through a 1.6 m wire in the catheter which has limited bandwidth and is vulnerable to noise, the SoC creates a pseudo-digital PWM signal which can be used for back telemetry or wireless readout of the RF data. In this implementation, using a 0.35-μm std. CMOS process, the TIA and single-to-differential (STD) converter had 45 MHz bandwidth, the quadrature sampler had 10.1 dB conversion gain, and the PWM had 5-bit ENoB. Preliminary results verified front-end functionality, and the power consumption of a TIA, STD, quadrature sampler, PWM, and clock multiplier was 26 mW from a 3 V supply. PMID:25571135

Fundamental phenomena on fuel decomposition and boundary-layer combustion processes with applications to hybrid rocket motors

NASA Astrophysics Data System (ADS)

Kuo, Kenneth K.; Lu, Yeu-Cherng; Chiaverini, Martin J.; Harting, George C.; Johnson, David K.; Serin, Nadir

The experimental study on the fundamental processes involved in fuel decomposition and boundary-layer combustion in hybrid rocket motors is continuously being conducted at the High Pressure Combustion Laboratory of The Pennsylvania State University. This research will provide a useful engineering technology base in the development of hybrid rocket motors as well as a fundamental understanding of the complex processes involved in hybrid propulsion. A high-pressure, 2-D slab motor has been designed, manufactured, and utilized for conducting seven test firings using HTPB fuel processed at PSU. A total of 20 fuel slabs have been received from the Mcdonnell Douglas Aerospace Corporation. Ten of these fuel slabs contain an array of fine-wire thermocouples for measuring solid fuel surface and subsurface temperatures. Diagnostic instrumentation used in the test include high-frequency pressure transducers for measuring static and dynamic motor pressures and fine-wire thermocouples for measuring solid fuel surface and subsurface temperatures. The ultrasonic pulse-echo technique as well as a real-time x-ray radiography system have been used to obtain independent measurements of instantaneous solid fuel regression rates.

Sequentially bridged graphene sheets with high strength, toughness, and electrical conductivity

PubMed Central

Wan, Sijie; Li, Yuchen; Mu, Jiuke; Aliev, Ali E.; Fang, Shaoli; Kotov, Nicholas A.; Jiang, Lei; Cheng, Qunfeng; Baughman, Ray H.

2018-01-01

We here show that infiltrated bridging agents can convert inexpensively fabricated graphene platelet sheets into high-performance materials, thereby avoiding the need for a polymer matrix. Two types of bridging agents were investigated for interconnecting graphene sheets, which attach to sheets by either π–π bonding or covalent bonding. When applied alone, the π–π bonding agent is most effective. However, successive application of the optimized ratio of π–π bonding and covalent bonding agents provides graphene sheets with the highest strength, toughness, fatigue resistance, electrical conductivity, electromagnetic interference shielding efficiency, and resistance to ultrasonic dissolution. Raman spectroscopy measurements of stress transfer to graphene platelets allow us to decipher the mechanisms of property improvement. In addition, the degree of orientation of graphene platelets increases with increasing effectiveness of the bonding agents, and the interlayer spacing increases. Compared with other materials that are strong in all directions within a sheet, the realized tensile strength (945 MPa) of the resin-free graphene platelet sheets was higher than for carbon nanotube or graphene platelet composites, and comparable to that of commercially available carbon fiber composites. The toughness of these composites, containing the combination of π–π bonding and covalent bonding, was much higher than for these other materials having high strengths for all in-plane directions, thereby opening the path to materials design of layered nanocomposites using multiple types of quantitatively engineered chemical bonds between nanoscale building blocks. PMID:29735659

Air-Coupled Ultrasonic Receivers with High Electromechanical Coupling PMN-32%PT Strip-Like Piezoelectric Elements

PubMed Central

Kazys, Rymantas J.; Sliteris, Reimondas; Sestoke, Justina

2017-01-01

For improvement of the efficiency of air-coupled ultrasonic transducers PMN-32%PT piezoelectric crystals which possess very high piezoelectric properties may be used. The electromechanical coupling factor of such crystals for all main vibration modes such as the thickness extension and transverse extension modes is more than 0.9. Operation of ultrasonic transducers with such piezoelectric elements in transmitting and receiving modes is rather different. Therefore, for transmission and reception of ultrasonic signals, separate piezoelectric elements with different dimensions must be used. The objective of this research was development of novel air-coupled ultrasonic receivers with PMN-32%PT strip-like piezoelectric elements vibrating in a transverse-extension mode with electromechanically controlled operation and suitable for applications in ultrasonic arrays. Performance of piezoelectric receivers made of the PMN-32%PT strip-like elements vibrating in this mode may be efficiently controlled by selecting geometry of the electrodes covering side surfaces of the piezoelectric element. It is equivalent to introduction of electromechanical damping which does not require any additional backing element. For this purpose; we have proposed the continuous electrodes to divide into two pairs of electrodes. The one pair is used to pick up the electric signal; another one is exploited for electromechanical damping. Two types of electrodes may be used—rectangular or non-rectangular—with a gap between them directed at some angle, usually 45°. The frequency bandwidth is wider (up to 9 kHz) in the case of non-rectangular electrodes. The strip-like acoustic matching element bonded to the tip of the PMN-32%PT crystal may significantly enhance the performance of the ultrasonic receiver. It was proposed to use for this purpose AIREX T10.110 rigid polymer foam, the acoustic impedance of which is close to the optimal value necessary for matching with air. It was found that in order to get a wide bandwidth the length of the matching strip should be selected not a quarter wavelength λ/4 at the antiresonance frequency but at lower frequency. It allowed achieving the frequency bandwidth (14–18)% with respect to the central frequency at −3 dB level. PMID:29035348

Air-Coupled Ultrasonic Receivers with High Electromechanical Coupling PMN-32%PT Strip-Like Piezoelectric Elements.

PubMed

Kazys, Rymantas J; Sliteris, Reimondas; Sestoke, Justina

2017-10-16

For improvement of the efficiency of air-coupled ultrasonic transducers PMN-32%PT piezoelectric crystals which possess very high piezoelectric properties may be used. The electromechanical coupling factor of such crystals for all main vibration modes such as the thickness extension and transverse extension modes is more than 0.9. Operation of ultrasonic transducers with such piezoelectric elements in transmitting and receiving modes is rather different. Therefore, for transmission and reception of ultrasonic signals, separate piezoelectric elements with different dimensions must be used. The objective of this research was development of novel air-coupled ultrasonic receivers with PMN-32%PT strip-like piezoelectric elements vibrating in a transverse-extension mode with electromechanically controlled operation and suitable for applications in ultrasonic arrays. Performance of piezoelectric receivers made of the PMN-32%PT strip-like elements vibrating in this mode may be efficiently controlled by selecting geometry of the electrodes covering side surfaces of the piezoelectric element. It is equivalent to introduction of electromechanical damping which does not require any additional backing element. For this purpose; we have proposed the continuous electrodes to divide into two pairs of electrodes. The one pair is used to pick up the electric signal; another one is exploited for electromechanical damping. Two types of electrodes may be used-rectangular or non-rectangular-with a gap between them directed at some angle, usually 45°. The frequency bandwidth is wider (up to 9 kHz) in the case of non-rectangular electrodes. The strip-like acoustic matching element bonded to the tip of the PMN-32%PT crystal may significantly enhance the performance of the ultrasonic receiver. It was proposed to use for this purpose AIREX T10.110 rigid polymer foam, the acoustic impedance of which is close to the optimal value necessary for matching with air. It was found that in order to get a wide bandwidth the length of the matching strip should be selected not a quarter wavelength λ/4 at the antiresonance frequency but at lower frequency. It allowed achieving the frequency bandwidth (14-18)% with respect to the central frequency at -3 dB level.

Microstructural Characterization of Irradiated U0.7ZrH1.6 Using Ultrasonic Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramuhalli, Pradeep; Jacob, Richard E.; MacFarlan, Paul J.

In recent years, there has been an increased level of effort to understand the changes in microstructure that occur due to irradiation of nuclear fuel. The primary driver for this increased effort is the potential for designing new fuels that are safer and more reliable, in turn enabling new and improved reactor technologies. Much of the data on microstructural change in irradiated fuels is generated through a host of post irradiation examination techniques such as optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to determine grain structure, porosity, crack geometry, etc. in irradiated fuels. Such “traditional”more » examination techniques were recently used to characterize a novel new fuel consisting of U0.17ZrH1.6 pellets bonded to zircaloy-2 cladded with lead-bismuth eutectic before and after irradiation. However, alternative methods such as ultrasonic inspection can provide an opportunity for nondestructively assessing microstructure in both in-pile and post-irradiation examinations. In this paper, we briefly describe initial results of ultrasonic examination of the U0.17ZrH1.6 pellets (unirradiated and irradiated), in a post-irradiation examination study. Data indicate some correlation with microstructural changes due to irradiation; however, it is not clear what the specific microstructural changes are that are influencing the ultrasonic measurements. Interestingly, specimens with nominally identical burnup show differences in ultrasonic signatures, indicating apparent microstructural differences between these specimens. A summary of the experimental study, preliminary data and findings are presented in this short paper. Additional details of the analysis will be included in the presentation.« less

Effects of Parasitic Reactance on Lattice Circuit Slotline Switch

NASA Technical Reports Server (NTRS)

Ponchak, George E.

2016-01-01

A slotline lattice switch has recently been proposed and demonstrated. In that paper, ideal diode characteristics were assumed. In this paper, the effects of parasitic reactances, due to the diode and the wire bonds that connect it to the circuit, are investigated. The switch is compared to a traditional slotline switch with a single diode across the slot.

Micro-Energy Rates for Damage Tolerance and Durability of Composite Structures

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Minnetyan, Levon

2006-01-01

In this paper, the adhesive bond strength of lap-jointed graphite/aluminum composites is examined by computational simulation. Computed micro-stress level energy release rates are used to identify the damage mechanisms associated with the corresponding acoustic emission (AE) signals. Computed damage regions are similarly correlated with ultrasonically scanned damage regions. Results show that computational simulation can be used with suitable NDE methods for credible in-service monitoring of composites.

Manufacturing Methods and Technology Project Summary Reports.

DTIC Science & Technology

1980-12-01

deposition of chrome-copper (Cr- Cu ), dry-film photoresist application, photolithographic masking, spray etching, die bonding, ultrasonic...4) cold roll forging. Of these, the cold roll forging process is the most widely used for the pro- duction of steel and low alloy blades. It provides... sprayed Mo- Al -Ni both provide relatively good wear resistance, see Figure 1. The powder -flame sprayed aluminum bronze did not perform as well. 147 -S t. I

An Ultrasonic Guided Wave Method to Estimate Applied Biaxial Loads (Preprint)

DTIC Science & Technology

2011-11-01

VALIDATION A fatigue test was performed with an array of six surface-bonded PZT transducers on a 6061 aluminum plate as shown in Figure 4. The specimen...direct paths of propagation are oriented at different angles. This method is applied to experimental sparse array data recorded during a fatigue test...and the additional complication of the resulting fatigue cracks interfering with some of the direct arrivals is addressed via proper selection of

Alleviation of mandibular anterior crowding with copper-nickel-titanium vs nickel-titanium wires: a double-blind randomized control trial.

PubMed

Pandis, Nikolaos; Polychronopoulou, Argy; Eliades, Theodore

2009-08-01

The purpose of this study was to investigate the efficiency of copper-nickel-titanium (CuNiTi) vs nickel-titanium (NiTi) archwires in resolving crowding of the anterior mandibular dentition. Sixty patients were included in this single-center, single-operator, double-blind randomized trial. All patients were bonded with the In Ovation-R self-ligating bracket (GAC, Central Islip, NY) with a 0.022-in slot, and the amount of crowding of the mandibular anterior dentition was assessed by using the irregularity index. The patients were randomly allocated into 2 groups of 30 patients, each receiving a 0.016-in CuNiTi 35 degrees C (Ormco, Glendora, Calif) or a 0.016-in NiTi (ModernArch, Wyomissing, Pa) wire. The type of wire selected for each patient was not disclosed to the provider or the patient. The date that each patient received a wire was recorded, and all patients were followed monthly for a maximum of 6 months. Demographic and clinical characteristics between the 2 wire groups were compared with the t test or the chi-square test and the Fisher exact test. Time to resolve crowding was explored with statistical methods for survival analysis, and alignment rate ratios for wire type and crowding level were calculated with Cox proportional hazards multivariate modeling. The type of wire (CuNiTi vs NiTi) had no significant effect on crowding alleviation (129.4 vs 121.4 days; hazard ratio, 1.3; P >0.05). Severe crowding (>5 on the irregularity index) showed a significantly higher probability of crowding alleviation duration relative to dental arches with a score of <5 (138.5 vs 113.1 days; hazard ratio, 2.2; P=0.02). The difference of the loading pattern of wires in laboratory and clinical conditions might effectively eliminate the laboratory-derived advantage of CuNiTi wires.

Application of IDT Sensors for Structural Health Monitoring of Windmill Turbine Blades Made of Composite Material

NASA Astrophysics Data System (ADS)

Nalladega, V.; Na, J. K.; Druffner, C.

2011-06-01

Interdigital transducers (IDT) generate and receive ultrasonic surface waves without the complexity involved with secondary devices such as angled wedges or combs. The IDT sensors have been successfully applied for the NDE of homogeneous materials like metals in order to detect cracks and de-bond. However, these transducers have not been yet adapted for complex and anisotropic materials like fiber-reinforced composites. This work presents the possibility of using IDT sensors for monitoring structural damages in wind turbine blades, typically made of fiberglass composites. IDT sensors with a range of operating frequency between 250 kHz and 1 MHz are initially tested on representative composite test panels for ultrasonic surface wave properties including beam spread, propagation distance and effect of material's anisotropy. Based on these results, an optimum frequency range for the IDT sensor is found to be 250-500 kHz. Subsequently, IDT sensors with operating frequency 500 kHz are used to detect and quantify artificial defects created in the composite test samples. Discussions are made on the interaction of ultrasonic fields with these defects along with the effects of fiber directionality and composite layer stacking.

Estimation of corrosion damage in steel reinforced mortar using waveguides

NASA Astrophysics Data System (ADS)

Reis, Henrique; Ervin, Benjamin L.; Kuchma, Daniel A.; Bernhard, Jennifer

2005-05-01

Corrosion of reinforced concrete is a chronic infrastructure problem, particularly in areas with deicing salt and marine exposure. To maintain structural integrity, a testing method is needed to identify areas of corroding reinforcement. For purposes of rehabilitation, the method must also be able to evaluate the degree, rate and location of damage. Towards the development of a wireless embedded sensor system to monitor and assess corrosion damage in reinforced concrete, reinforced mortar specimens were manufactured with seeded defects to simulate corrosion damage. Taking advantage of waveguide effects of the reinforcing bars, these specimens were then tested using an ultrasonic approach. Using the same ultrasonic approach, specimens without seeded defects were also monitored during accelerated corrosion tests. Both the ultrasonic sending and the receiving transducers were mounted on the steel rebar. Advantage was taken of the lower frequency (<250 kHz) fundamental flexural propagation mode because of its relatively large displacements at the interface between the reinforcing steel and the surrounding concrete. Waveform energy (indicative of attenuation) is presented and discussed in terms of corrosion damage. Current results indicate that the loss of bond strength between the reinforcing steel and the surrounding concrete can be detected and evaluated.

Complete modeling of rotary ultrasonic motors actuated by traveling flexural waves

NASA Astrophysics Data System (ADS)

Bao, Xiaoqi; Bar-Cohen, Yoseph

2000-06-01

Ultrasonic rotary motors have the potential to meet this NASA need and they are developed as actuators for miniature telerobotic applications. These motors are being adapted for operation at the harsh space environments that include cryogenic temperatures and vacuum and analytical tools for the design of efficient motors are being developed. A hybrid analytical model was developed to address a complete ultrasonic motor as a system. Included in this model is the influence of the rotor dynamics, which was determined experimentally to be important to the motor performance. The analysis employs a 3D finite element model to express the dynamic characteristics of the stator with piezoelectric elements and the rotor. The details of the stator including the teeth, piezoelectric ceramic, geometry, bonding layer, etc. are included to support practical USM designs. A brush model is used for the interface layer and Coulomb's law for the friction between the stator and the rotor. The theoretical predictions were corroborated experimentally for the motor. In parallel, efforts have been made to determine the thermal and vacuum performance of these motors. To explore telerobotic applications for USMs a robotic arm was constructed with such motors.

Scanning of the internal structure part with laser ultrasonic in aviation industry.

PubMed

Swornowski, Pawel J

2011-01-01

The detection of internal defects is a major production and safety issue for the newest generations of aircraft. New materials and manufacturing processes in the aircraft industry demand efficient quality assurance in manufacturing and inspection in maintenance. Advanced metallic material processes (titanium) are used or developed for the production of heavily loaded flying components (in fan blade construction). The inspection of these parts mainly made out of titanium (or CFRP) requires the determination of the percentage of bonded grain sizes around 10-30 µm. This is primarily due to the advantages of a high signal-to-noise ratio and good detection sensitivity. In this article, a diagnosing method of the blade interior by means of the laser ultrasonic is presented. Identification of small fatigue cracks presents a challenging problem during nondestructive testing of fatigue-damaged structures. Laser ultrasonic is a technique that uses two laser beams; one with a short pulse for the generation of ultrasound and another with a long pulse or continuous coupled to an optical interferometer for detection. The results of research of the internal blade structure are presented. Copyright © 2011 Wiley Periodicals, Inc.

Characterization of Bond Strength of U-Mo Fuel Plates Using the Laser Shockwave Technique: Capabilities and Preliminary Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. A. Smith; D. L. Cottle; B. H. Rabin

2013-09-01

This report summarizes work conducted to-date on the implementation of new laser-based capabilities for characterization of bond strength in nuclear fuel plates, and presents preliminary results obtained from fresh fuel studies on as-fabricated monolithic fuel consisting of uranium-10 wt.% molybdenum alloys clad in 6061 aluminum by hot isostatic pressing. Characterization involves application of two complementary experimental methods, laser-shock testing and laser-ultrasonic imaging, collectively referred to as the Laser Shockwave Technique (LST), that allows the integrity, physical properties and interfacial bond strength in fuel plates to be evaluated. Example characterization results are provided, including measurement of layer thicknesses, elastic properties ofmore » the constituents, and the location and nature of generated debonds (including kissing bonds). LST provides spatially localized, non-contacting measurements with minimum specimen preparation, and is ideally suited for applications involving radioactive materials, including irradiated materials. The theoretical principles and experimental approaches employed in characterizing nuclear fuel plates are described, and preliminary bond strength measurement results are discussed, with emphasis on demonstrating the capabilities and limitations of these methods. These preliminary results demonstrate the ability to distinguish bond strength variations between different fuel plates. Although additional development work is necessary to validate and qualify the test methods, these results suggest LST is viable as a method to meet fuel qualification requirements to demonstrate acceptable bonding integrity.« less

Fabrication of All-SiC Fiber-Optic Pressure Sensors for High-Temperature Applications

PubMed Central

Jiang, Yonggang; Li, Jian; Zhou, Zhiwen; Jiang, Xinggang; Zhang, Deyuan

2016-01-01

Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1–0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature. PMID:27763494

Fabrication of All-SiC Fiber-Optic Pressure Sensors for High-Temperature Applications.

PubMed

Jiang, Yonggang; Li, Jian; Zhou, Zhiwen; Jiang, Xinggang; Zhang, Deyuan

2016-10-17

Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1-0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature.

IMPROVED BONDING METHOD

DOEpatents

Padgett, E.V. Jr.; Warf, D.H.

1964-04-28

An improved process of bonding aluminum to aluminum without fusion by ultrasonic vibrations plus pressure is described. The surfaces to be bonded are coated with an aqueous solution of alkali metal stearate prior to assembling for bonding. (AEC) O H19504 Present information is reviewed on steady state proliferation, differentiation, and maturation of blood cells in mammals. Data are cited from metabolic tracer studies, autoradiographic studies, cytologic studies, studies of hematopoietic response to radiation injuries, and computer analyses of blood cell production. A 3-step model for erythropoiesis and a model for granulocyte kinetics are presented. New approaches to the study of lymphocytopoiesis described include extracorporeal blood irradiation to deplete lymphocytic tissue without direct injury to the formative tissues as a means to study the stressed system, function control, and rates of proliferation. It is pointed out that present knowledge indicates that lymphocytes comprise a mixed family, with diverse life spans, functions, and migration patterns with apparent aimless recycling from modes to lymph to blood to nodes that has not yet been quantitated. Areas of future research are postulated. (70 references.) (C.H.)

Nondestructive Evaluation of Adhesively Bonded Joints

NASA Technical Reports Server (NTRS)

Nayeb-Hashemi, Hamid; Rossettos, J. N.

1997-01-01

The final report consists of 5 published papers in referred journals and a technical letter to the technical monitor. These papers include the following: (1) Comparison of the effects of debonds and voids in adhesive; (2) On the peak shear stresses in adhesive joints with voids; (3) Nondestructive evaluation of adhesively bonded joints by acousto-ultrasonic technique and acoustic emission; (4) Multiaxial fatigue life evaluation of tubular adhesively bonded joints; (5) Theoretical and experimental evaluation of the bond strength under peeling loads. The letter outlines the progress of the research. Also included is preliminary information on the study of nondestructive evaluation of composite materials subjected to localized heat damage. The investigators studied the effects of localized heat on unidirectional fiber glass epoxy composite panels. Specimens of the fiber glass epoxy composites were subjected to 400 C heat for varying lengths of time. The specimens were subjected to nondestructive tests. The specimens were then pulled to their failure and acoustic emission of these specimens were measured. The analysis of the data was continuing as of the writing of the letter, and includes a finite element stress analysis of the problem.

In vitro tensile bond strength of adhesive cements to new post materials.

PubMed

O'Keefe, K L; Miller, B H; Powers, J M

2000-01-01

The purpose of this study was to measure the in vitro tensile bond strength of 3 types of adhesive resin cements to stainless steel, titanium, carbon fiber-reinforced resin, and zirconium oxide post materials. Disks of post materials were polished to 600 grit, air abraded, and ultrasonically cleaned. Zirconium oxide bonding surfaces were pretreated with hydrofluoric acid and silanated. Bis-Core, C&B Metabond, and Panavia cements were bonded to the post specimens and placed in a humidor for 24 hours. Post specimens were debonded in tension. Means and standard deviations (n = 5) were analyzed by 2-way analysis of variance. Tukey-Kramer intervals at the 0.05 significance level were calculated. Failure modes were observed. Panavia 21 provided the highest bond strengths for all types of post materials, ranging from 22 MPa (zirconium oxide) to 37 MPa (titanium). C&B Metabond bonded significantly more strongly to stainless steel (27 MPa) and titanium (22 MPa) than to zirconium oxide (7 MPa). Bis-Core results were the lowest, ranging from 16 MPa (stainless steel) to 8 MPa (zirconium oxide). In most cases, bonds to carbon fiber post materials were weaker than to stainless steel and titanium, but stronger than to zirconium oxide. In general, higher bond strengths resulted in a higher percentage of cohesive failures within the cement. Panavia 21 provided the highest bond strengths to all post materials, followed by C&B Metabond. In most cases, adhesive resins had higher bond strengths to stainless steel, titanium, and carbon fiber than to zirconium oxide.

High-Temperature, Thin-Film Strain Gages Improved

NASA Technical Reports Server (NTRS)

2005-01-01

Conventional resistance strain gage technology uses "bonded" strain gages. These foil or wire gages are bonded onto the surface of the test article with glue, ceramic cements, or flame-sprayed ceramics. These bonding agents can, in some instances, limit both the degree of strain transmission from the test structure to the gage and the maximum working temperature of the gage. Also, the bulky, bonded gage normally disrupts aerodynamic gas flow on the surface of the test structure because of its intrusive character. To respond to the urgent needs in aeronautic and aerospace research where stress and temperature gradients are high, aerodynamic effects need to be minimized, and higher operational temperatures are required, the NASA Lewis Research Center developed a thin film strain gage. This gage, a vacuum-deposited thin film formed directly on the surface of a test structure, operates at much higher temperatures than commercially available gages do and with minimal disruption of the aerodynamic flow. The gage uses an alloy, palladium-13 wt % chromium (hereafter, PdCr), which was developed by United Technologies Research Center under a NASA contract. PdCr is structurally stable and oxidation resistant up to at least 1100 C (2000 F); its temperature-induced resistance change is linear, repeatable, and not sensitive to the rates of heating and cooling. An early strain gage, which was made of 25-micrometer-diameter PdCr wire and demonstrated to be useable to 800 C, won an R&D 100 award in 1991. By further improving the purity of the material and by developing gage fabrication techniques that use sputter-deposition, photolithography patterning, and chemical etching, we have made an 8- to 10-m PdCr thin-film strain gage that can measure dynamic and static strain to at least 1100 C. For static strain measurements, a 5-m-thick Pt element serves as a temperature compensator to further minimize the temperature effect of the gage. These thin-film gages provide the advantage of minimally intrusive surface strain measurements and give highly repeatable readings with low drift at temperatures from ambient to 1100 C. This is a 300 C advance in operating temperature over the PdCr wire gage and a 500 C advance over commercially available gages made of other materials.

Ultrasonic soldering of Cu alloy using Ni-foam/Sn composite interlayer.

PubMed

Xiao, Yong; Wang, Qiwei; Wang, Ling; Zeng, Xian; Li, Mingyu; Wang, Ziqi; Zhang, Xingyi; Zhu, Xiaomeng

2018-07-01

In this study, Cu alloy joints were fabricated with a Ni-foam reinforced Sn-based composite solder with the assistance of ultrasonic vibration. Effects of ultrasonic soldering time on the microstructure and mechanical properties of Cu/Ni-Sn/Cu joints were investigated. Results showed that exceptional metallurgic bonding could be acquired with the assistance of ultrasonic vibration using a self-developed Ni-foam/Sn composite solder. For joint soldered for 5 s, a (Cu,Ni) 6 Sn 5 intermetallic compound (IMC) layer was formed on the Cu substrate surface, Ni skeletons distributed randomly in the soldering seam and a serrated (Ni,Cu) 3 Sn 4 IMC layer was formed on the Ni skeleton surface. Increasing the soldering time to 20 s, the (Ni,Cu) 3 Sn 4 IMC layer grew significantly and exhibited a loose porous structure on the Ni skeleton surface. Further increase the soldering time to 30 s, Ni skeletons were largely dissolved in the Sn base solder, and micro-sized (Ni,Cu) 3 Sn 4 particles were formed and dispersed homogeneously in the soldering seam. The formation of (Ni,Cu) 3 Sn 4 particles was mainly ascribed to acoustic cavitations induced erosion and grain refining effects. The joint soldered for 30 s exhibited the highest shear strength of 64.9 ± 3.3 MPa, and the shearing failure mainly occurred at the soldering seam/Cu substrate interface. Copyright © 2018 Elsevier B.V. All rights reserved.

Thin-disk piezoceramic ultrasonic motor. Part I: design and performance evaluation.

PubMed

Wen, Fuh Liang; Yen, Chi Yung; Ouyang, Minsun

2003-08-01

The purpose of this study is to gain the knowledge and experience in the design of thin-disk piezoceramic-driving ultrasonic actuator dedicated. In this paper, the design and construction of an innovative ultrasonic actuator is developed as a stator, which is a composite structure consisting of piezoceramic (PZT) membrane bonded on a metal sheet. Such a concentric PZT structure possesses the electrical and mechanical coupling characteristics in flexural wave. The driving ability of the actuator comes from the mechanical vibration of extension and shrinkage of a metal sheet due to the converse piezoelectric effect, corresponding to the frequency of a single-phase AC power. By applying the constraints on the specific geometry positions on the metal sheet, the various behaviors of flexural waves have been at the different directions. The rotor is impelled by the actuator with rotational speeds of 600 rpm in maximum using a friction-contact mechanism. Very high actuating and braking abilities are obtained. This simple and inexpensive structure of actuator demonstrates that the mechanical design of actuator and rotor could be done separately and flexibly according to the requirements for various applications. And, its running accuracy and positioning precision are described in Part II.A closed loop servo positioning control i.e. sliding mode control (SMC) is used to compensate automatically for nonlinearly mechanical behaviors such as dry friction, ultrasonic vibrating, slip-stick phenomena. Additionally, SMC scheme has been successfully applied to position tracking to prove the excellent robust performance in noise rejection.

Length-Dependent Nanotransport and Charge Hopping Bottlenecks in Long Thiophene-Containing π-Conjugated Molecular Wires.

PubMed

Smith, Christopher E; Odoh, Samuel O; Ghosh, Soumen; Gagliardi, Laura; Cramer, Christopher J; Frisbie, C Daniel

2015-12-23

Self-assembled conjugated molecular wires containing thiophene up to 6 nm in length were grown layer-by-layer using click chemistry. Reflection-absorption infrared spectroscopy, ellipsometry and X-ray photoelectron spectroscopy were used to follow the stepwise growth. The electronic structure of the conjugated wires was studied with cyclic voltammetry and UV-vis spectroscopy as well as computationally with density functional theory (DFT). The current-voltage curves (±1 V) of the conjugated molecular wires were measured with conducting probe atomic force microscopy (CP-AFM) in which the molecular wire film bound to a gold substrate was contacted with a conductive AFM probe. By systematically measuring the low bias junction resistance as a function of length for molecules 1-4 nm long, we extracted the structure dependent tunneling attenuation factor (β) of 3.4 nm(-1) and a contact resistance of 220 kΩ. The crossover from tunneling to hopping transport was observed at a molecular length of 4-5 nm with an activation energy of 0.35 eV extracted from Arrhenius plots of resistance versus temperature. DFT calculations revealed localizations of spin densities (polarons) on molecular wire radical cations. The calculations were employed to gauge transition state energies for hopping of polarons along wire segments. Individual estimated transition state energies were 0.2-0.4 eV, in good agreement with the experimental activation energy. The transition states correspond to flattening of dihedral angles about specific imine bonds. These results open up possibilities to further explore the influence of molecular architecture on hopping transport in molecular junctions, and highlight the utility of DFT to understand charge localization and associated hopping-based transport.