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1

Diffusion bonding  

DOEpatents

1. A method for joining beryllium to beryllium by diffusion bonding, comprising the steps of coating at least one surface portion of at least two beryllium pieces with nickel, positioning a coated surface portion in a contiguous relationship with an other surface portion, subjecting the contiguously disposed surface portions to an environment having an atmosphere at a pressure lower than ambient pressure, applying a force upon the beryllium pieces for causing the contiguous surface portions to abut against each other, heating the contiguous surface portions to a maximum temperature less than the melting temperature of the beryllium, substantially uniformly decreasing the applied force while increasing the temperature after attaining a temperature substantially above room temperature, and maintaining a portion of the applied force at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions.

Anderson, Robert C. (Oak Ridge, TN)

1976-06-22

2

Diffusion bonding of beryllium-copper alloys  

Microsoft Academic Search

A process has been developed for diffusion-bonding identical beryllium-copper alloy, 1.8 to 2.0 wt% Be, which has produced bond strengths comparable to that of the bulk. Bonding resulted from self-diffusion between two Be-Cu samples, brought into intimate contact and heated in a high vacuum. Metallurgical analyses of the diffusion bonds revealed the bond interface to be a continuous high-angle planar

D. C. Eckman; B. Z. Rosenblum; C. Q. Bowles

1992-01-01

3

Diffusion bonding of beryllium-copper alloys  

Microsoft Academic Search

A process has been developed for diffusion-bonding identical beryllium-copper alloy, 1.8 to 2.0 wt% Be, which has produced\\u000a bond strengths comparable to that of the bulk. Bonding resulted from self-diffusion between two Be-Cu samples, brought into\\u000a intimate contact and heated in a high vacuum. Metallurgical analyses of the diffusion bonds revealed the bond interface to\\u000a be a continuous high-angle planar

D. C. Eckman; B. Z. Rosenblum; C. Q. Bowles

1992-01-01

4

[Diffusion bonding of hydroxyapatite ceramics and biometals].  

PubMed

To improve the mechanical characteristics of hydroxyapatite (HAP) ceramics, a metal-ceramic composite formed by a solid state direct diffusion bonding system was studied. The joining treatment was carried out of a high vacuum and high temperature, for the bioactive ceramics (HAP) and the following biometals; platinum, gold-platinum alloy, titanium and titanium alloys, zirconium, niobium and aluminium alloy. The effects of the variations of thermal expansion mismatch and the interactive reactions at the interface were investigated by fractographic observation (SEM), X-ray diffraction method and EPMA analysis. On some of these joining combinations, the bonding strength had the same bonding strength as the adhesive materials. The results of interface observations showed that the bonding strength is affected by the interface reactions and the diffusion phenomena. PMID:2135505

Yamane, F

1990-03-01

5

Diffusion bonding of Stratapax for drill bits  

SciTech Connect

A process has been developed for the diffusion bonding of General Electric's Stratapax drill blanks to support studs for cutter assemblies in drill bits. The diffusion bonding process is described and bond strength test data are provided for a variety of materials. The extensive process details, provided in the Appendices, should be sufficient to enable others to successfully build diffusion-bonded drill bit cutter assemblies.

Middleton, J.N.; Finger, J.T.

1983-01-01

6

DEVELOPMENT OF DIFFUSION-TYPE BONDING TECHNIQUES FOR BERYLCO-25 ALLOY  

Microsoft Academic Search

Bond tensile strengths in excess of 90,000 psi in joining precipitation-; hardened beryllium -copper have been obtained by diffusion techniques. Ordinary ; brazing techniques for beryllium--copper have resulted in an average of 40,000-; psi tensile strength in the bond. Bonds with tensile strengths averaging 108,400 ; psi have been developed using high-vacuum, diffusion-type bonding techniques. ; Hardnesses averaging 38 Rockwell

G. R. Baxter; J. A. Hoffman; R. C. Bertossa; B. R. Cottrell

1961-01-01

7

Better Vacuum by Removal of Diffusion-Pump-Oil Contaminants.  

National Technical Information Service (NTIS)

The complex problem of why large space simulation chambers do not realize true ultimate vacuum was investigated. Some contaminating factors affecting diffusion pump performance were identified, and some advances in vacuum distillation-fractionation techno...

A. E. Buggele

1975-01-01

8

Impulse pressuring diffusion bonding of titanium alloy to stainless steel  

SciTech Connect

Impulse pressuring diffusion bonding between a titanium alloy TA17 and an austenitic stainless steel 0Cr18Ni9Ti has been carried out in vacuum. Relationships between the bonding parameters and the tensile strength of the joints were investigated, and the optimum bond parameters were obtained: bonding temperature T = 825 deg. C, maximum impulse pressure P{sub max} = 50 MPa, minimum impulse pressure P{sub min} = 8 MPa, number of impulses N = 30, impulse frequency f = 0.5 Hz. The maximum tensile strength of the joint was 321 MPa and the effective bonding time was only 180 s. The reaction products and the interface structure of the joints were investigated by optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and X-ray diffraction (XRD). The study revealed the existence of FeTi, Fe{sub 2}Ti, {sigma} phase and {beta}-Ti in the reaction zone. Brittle Fe-Ti intermetallic phases lower the strength and ductility of the impulse pressuring diffusion bonded couples significantly. This technique provides a reliable and efficient bonding method of titanium alloy and stainless steel.

Yuan, X.J. [College of Materials Science and Engineering, Chongqing University, 400044 (China)], E-mail: cqu_y@sina.com.cn; Sheng, G.M. [College of Materials Science and Engineering, Chongqing University, 400044 (China)], E-mail: gmsheng@cqu.edu.cn; Qin, B.; Huang, W.Z.; Zhou, B. [College of Materials Science and Engineering, Chongqing University, 400044 (China)

2008-07-15

9

Diffusion bonding of Ti coated Zircaloy-4 and 316-L stainless steel  

SciTech Connect

Diffusion bonding of Zircaloy-4 and Type 316-L stainless steel was carried out by coating the joining surfaces with Ti to minimize the interlayer effect. Bonding heat treatments were carried out in vacuum at 1000 deg. C for 4 h and 1050 deg. C for 1 h. The microstructure of the diffusion zone was investigated by scanning electron microscopy and the phases in the diffusion zone were analyzed by energy dispersive spectroscopy. It is observed that Ti coating at the interface produced a dendritic structure in the diffusion zone formed in the Zircaloy-4. The concentration of the dendrites increases with an increase in bonding temperature.

Akhter, J.I. [Physics Division, Pakistan Institute of Nuclear Science and Technology, P. O. Nilore, Islamabad (Pakistan)], E-mail: jiakhter@yahoo.com; Ahmad, M.; Ali, G. [Physics Division, Pakistan Institute of Nuclear Science and Technology, P. O. Nilore, Islamabad (Pakistan)

2009-03-15

10

Phase transformation diffusion bonding of titanium alloy with stainless steel  

SciTech Connect

Phase transformation diffusion bonding between a titanium alloy (TA17) and an austenitic stainless steel (0Cr18Ni9Ti) has been carried out in vacuum. Relationships between the bonding parameters and the tensile strength of the joints were investigated, and the optimum bond parameters were obtained: maximum cyclic temperature = 890 deg. C, minimum cyclic temperature = 800 deg. C, number of cycles = 10, bonding pressure = 5 MPa and heating rate = 30 deg. C/s. The maximum tensile strength of the joint was 307 MPa. The reaction products and the interface structure of the joints were investigated by light optical and scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The study indicated the existence of {sigma} phase, Fe{sub 2}Ti, Fe-Ti intermetallic and {beta}-Ti in the reaction zone. The presence of the brittle Fe-Ti intermetallic phase lowered both the strength and the ductility of the phase transformation diffusion-bonded joint significantly.

Qin, B. [College of Materials Science and Engineering, Chongqing University, 400044 (China)]. E-mail: jjj-jenny@163.com; Sheng, G.M. [College of Materials Science and Engineering, Chongqing University, 400044 (China); Huang, J.W. [College of Materials Science and Engineering, Chongqing University, 400044 (China); Zhou, B. [College of Materials Science and Engineering, Chongqing University, 400044 (China); Qiu, S.Y. [National Key Laboratory for Nuclear Fuel and Materials, Sichuan, Chengdu, 610041 (China); Li, C. [National Key Laboratory for Nuclear Fuel and Materials, Sichuan, Chengdu, 610041 (China)

2006-01-15

11

Development of the Diffusion Bonding Process.  

National Technical Information Service (NTIS)

The diffusion bonding process was adapted for a unique low-temperature application involving the attachment of thin copper materials used in the flexible printed circuit industry. The work completed to date has demonstrated the feasibility of welding 0.00...

J. J. Kwiatkowski W. H. Jones

1987-01-01

12

Self-assembly of Epitaxial Monolayers for Vacuum Wafer Bonding  

Microsoft Academic Search

Self-assembled epitaxial metal monolayers can be used for hetero-integration of mismatched semiconductors, leading to simultaneously low interfacial resistance and high optical transparency. Lattice-mismatched wafers of Si(100) and Si(111) were bonded at room temperature in situ after vacuum deposition of a single atomic layer of Ag on them. The interfacial resistance was measured to be 3.9x 10-4 ohm. cm^ 2 and

Igor Altfeder; Biqin Huang; Ian Appelbaum; Barry Walker

2007-01-01

13

Strength, ultrasonic and metallurgical evaluation of diffusion bonds  

SciTech Connect

Diffusion bonding allows similar and dissimilar materials to be bonded together in near net shape. However, differentiation of almost perfect diffusion bonds, with little variation in their acoustic response, is of critical importance since relatively significant changes in bond strength may be a consequence. Challenge is to find ultrasonic techniques sensitive enough to detect small imperfections at interface. Diffusion bonds have been produced that show only a slight variation in a single frequency reflection measurement. The total energy, reflected from bond line, can differentiate these diffusion bonds. This evaluation is based on Parseval`s theorem which states that energy in time domain is proportional to energy in the frequency domain. This measurement takes advantage of presence of voids in the diffusion bonds as well as of the interdiffusion zone. Cu and Ni were chosen as the materials to be bonded due to the case of microstructural control. Diffusion bonds fabricated of Ti-6Al-4V are also discussed.

Ojard, G.C.; Buck, O.; Rehbein, D.K.

1993-10-01

14

Diffusion bonding of silicon nitride to titanium  

Microsoft Academic Search

The use of ceramic has gradually increased over the past few years. Si3N4 is one of the most important ceramics used as structural material for high temperature applications. The practical use of advanced ceramics depends on the reliability of ceramic\\/metal joining techniques and the properties of the resulting interfaces. This work focuses on various aspects of diffusion bonding of Si3N4

Jose Lemus-Ruiz

2001-01-01

15

Measurement of Charged Particle Current Diffused from Vacuum Arc  

NASA Astrophysics Data System (ADS)

Particles diffused from vacuum arc can be used for thin film formation. Diffusion of particles from vacuum arc influences current breaking properties of a vacuum interrupter. For these application it is essential to clarify the behavior of particles diffused from vacuum arc at around current zero point. In this paper dependence of diffused charged particles current on the crest value of arc current before current interruption point was shown with Faraday cup in case of oxygen-free copper electrodes and CuCr (Cu:Cr=50:50) electrodes. Experimental results were as follows. Ions and electrons diffused from vacuum arc entered into the Faraday cup with pulsive and intermittent states, when vacuum arc of DC 100 A?150 A was generated in case of oxygen-free copper electrodes. This phenomenon corresponds to the behavior of cathode spots. Electron current value was about 100 times as large as ion current value. The pulse width is about 1?10?s. When the crest value of arc current were 2,000 A?10,000 A in case of oxygen-free copper electrodes and CuCr (Cu:Cr=50:50) electrodes, the amount of charged particle current for CuCr before the current interruption point was larger than those for Cu. The ratios of the ion current to the electron current diffused from vacuum arc were calculated by the waveforms of electron and ion currents. The current ratios of 0?0.02 were taken when the crest value of arc current 2,000 A?10,000 A.

Furesawa, Masamichi; Yamano, Yasushi; Kobayashi, Shinichi

16

On the Direct Diffusion Bonding of Titanium Alloy to Stainless Steel  

Microsoft Academic Search

In the present study, direct diffusion bonding of Ti-6Al-4V to 304L stainless steel has been carried out in vacuum in the temperature range of 850950C using 3MPa uniaxial load for 30 to 90min durations. Different reaction layers in the diffusion zone have been examined by optical microscopy, scanning electron microscopy (SEM) using the back scattered mode, X-ray diffraction (XRD), and

Swarup K. Ghosh; S. Chatterjee

2010-01-01

17

DIFFUSION BONDING BERYLLIUM COPPER FOR ULTRA HIGH-STRENGTH JOINTS  

Microsoft Academic Search

Bond strengths averaging 108, 400 psi were developed in joining ; precipitation-hardened beryllium -copper by diffusion techniques. This is in ; contrast with an average of 40,000 psi obtained by ordinary brazing techniques. ; The method of diffusion bonding studied in this program involved the use of ; molten alloys of silver and gold to fill discontinuities at the bond

J. A. Hoffman; G. R. Baxter; R. C. Bertossa; B. R. Cottrell

1962-01-01

18

Diffusion bonding of silicon nitride to titanium  

NASA Astrophysics Data System (ADS)

The use of ceramic has gradually increased over the past few years. Si3N4 is one of the most important ceramics used as structural material for high temperature applications. The practical use of advanced ceramics depends on the reliability of ceramic/metal joining techniques and the properties of the resulting interfaces. This work focuses on various aspects of diffusion bonding of Si3N4 to Ti as well as on the use of Ti-foil interlayer during the self-joining of Si3N4. Si3N4/Ti and Si3N 4/Ti-foil/Si3N4 combinations were diffusion joined by hot-uniaxial pressing and the microstructural characterization of the resulting interfaces was carried out by SEM, EPMA, and X-ray diffraction. Diffusion bonding was carried out at temperatures ranging from 1200 to 1500C using different holding times, pressures, and surface roughness of the joining materials. The results showed that Si3N4 could not be bonded to Ti at temperatures lower than 1400C, however successful joining at higher temperatures. Joining occurred by the formation of a reactive interface on the Ti side of the joint. At temperatures greater than 1330C, liquid formation occurred by the interaction of Ti with Si promoting bonding, as well as the high affinity of Ti for Si resulted in rapid interface formation of silicides, initially Ti5Si3. EPMA and X-ray diffraction confirmed the presence of Ti5Si3, TiSi, and TiN at the interface. The surface roughness of the joining materials plays an important role since thicker interfaces were obtained for polished samples compared to as-ground samples. The interfaces grew in a parabolic fashion with the formation of various Ti-silicides (Ti5Si3 and TiSi) as well as Ti-nitride (TiN) at the interface. Evaluation of joint strengths as a function of the experimental parameters such as, joining temperature and time was obtained by four-point bending test performed on Si3N4/Ti/Si3N4 joints. Strong joints were produced at joining temperatures greater than 1450C with average bend strength of more than 100 MPa. The maximum joint strength was obtained in samples hot-pressed at 1500C and 120 minutes reaching a value of 147 MPa.

Lemus-Ruiz, Jose

2001-07-01

19

The effects of various finished surfaces on diffusion bonding  

NASA Astrophysics Data System (ADS)

Using a theoretical model for diffusion bonding, which contains the real information of the intended bonding surfaces and considers the effect of the limited diffusion distance in a definite time, effects of various finished surfaces on diffusion bonding were investigated. The simulation results indicate that, under the same bonding condition with the exception of the surface finish method, the bonding couples with surfaces prepared by the turning technique exhibit a higher bonding rate than the couples with as-ground surfaces and show a slower bonding rate than the couples with the intended bonding surfaces ground by fine-SiC abrasive paper. Contributions from each operating mechanism to the interfacial void closure vary with bonding time, surface roughness and the surface finish method of the intended bonding surfaces.

Wu, G. Q.; Li, Z. F.; Luo, G. X.; Huang, Z.

2008-12-01

20

Low-temperature diffusion bonding of pure aluminum  

NASA Astrophysics Data System (ADS)

1 keV argon ion beam was employed to remove the oxide film of pure aluminum before diffusion bonding. A sound joint of pure aluminum was obtained by ion activation-assisted diffusion bonding at the low temperature of 350C, while the high-quality joining of pure aluminum was infeasible by conventional diffusion bonding at the temperature lower than 500C. The residual oxide film ratios of joints decreased with the increase of ion cleaning time. When the specimens were cleaned for 120 min, the joint with the maximum tensile strength of 62.3 MPa and the elongation of 14.1 % was obtained. The argon ion beam etching surface treatment provides a new route for the low-temperature diffusion bonding. The reliable diffusion bonded joint of pure aluminum indicates that low-temperature diffusion bonding is feasible for bulk materials, especially for materials with the outstanding plasticity.

Chen, Haiyan; Cao, Jian; Tian, Xiaoyu; Li, Rui; Feng, Jicai

2013-08-01

21

Signal analysis approach to ultrasonic evaluation of diffusion bond quality  

SciTech Connect

Solid state bonds like the diffusion bond are attractive techniques for joining dissimilar materials since they are not prone to the defects that occur with fusion welding. Ultrasonic methods can detect the presence of totally unbonded regions but have difficulty sensing poor bonded areas where the substrates are in intimate contact. Standard ultrasonic imaging is based on amplitude changes in the signal reflected from the bond interface. Unfortunately, amplitude alone is not sensitive to bond quality. We demonstrated that there is additional information in the ultrasonic signal that correlates with bond quality. In our approach, we interrogated a set of dissimilar diffusion bonded samples with broad band ultrasonic signals. The signals were digitally processed and the characteristics of the signals that corresponded to bond quality were determined. These characteristics or features were processed with pattern recognition algorithms to produce predictions of bond quality. The predicted bond quality was then compared with the destructive measurement to assess the classification capability of the ultrasonic technique.

Thomas, Graham; Chinn, Diane [Manufacturing and Materials Engineering Department, Lawrence Livermore National Laboratory, Livermore, California, 94550 (United States)

1999-12-02

22

Vacuum packaging technology using localized aluminum\\/silicon-to-glass bonding  

Microsoft Academic Search

A vacuum package based on localized aluminum\\/silicon-to-glass bonding has been successfully demonstrated. With 3.4 watts heating power, ~0.2 MPa applied contact pressure, and 90 minutes wait time before bonding, vacuum encapsulation at 25 mtorr can be achieved. Folded-beam comb drive ?-resonators are encapsulated and used as pressure monitors. Long-term testing of un-annealed vacuum-packaged ?-resonators with a Q of 2500 has

Y. T. Cheng; W. T. Hsu; L. Lin; C. T. Nguyen; K. Najafi

2001-01-01

23

Gold-indium Transient Liquid Phase (TLP) wafer bonding for MEMS vacuum packaging  

Microsoft Academic Search

This paper reports the first wafer-level vacuum packages created with gold-indium transient liquid phase (TLP) wafer bonding. The packages were bonded at 200degC for 1 hour under a vacuum environment in a commercially available wafer bonder. After bonding, the integrated getters were activated for 1 hour resulting in internal pressures as low as 200 mTorr. The pressures have been stable

Warren C. Welch; Khalil Najafi

2008-01-01

24

Diffusion bonding and brazing of high purity copper for linear collider accelerator structures  

NASA Astrophysics Data System (ADS)

Diffusion bonding and brazing of high purity copper were investigated to develop procedures for joining precision machined copper components for the Next Linear Collider (NLC). Diffusion bonds were made over a range of temperatures from 400 C to 1000 C, under two different loading conditions [3.45 kPa (0.5 psi) and 3.45 MPa (500 psi)], and on two different diamond machined surface finishes. Brazes were made using pure silver, pure gold, and gold-nickel alloys, and different heating rates produced by both radiation and induction heating. Braze materials were applied by both physical vapor deposition (PVD) and conventional braze alloy shims. Results of the diffusion bonding experiments showed that bond strengths very near that of the copper base metal could be made at bonding temperatures of 700 C or higher at 3.45 MPa bonding pressure. At lower temperatures, only partial strength diffusion bonds could be made. At low bonding pressures (3.45 kPa), full strength bonds were made at temperatures of 800 C and higher, while no bonding (zero strength) was observed at temperatures of 700 C and lower. Observations of the fracture surfaces of the diffusion bonded samples showed the effects of surface finish on the bonding mechanism. These observations clearly indicate that bonding began by point asperity contact, and flatter surfaces resulted in a higher percentage of bonded area under similar bonding conditions. Results of the brazing experiments indicated that pure silver worked very well for brazing under both conventional and high heating rate scenarios. Similarly, pure silver brazed well for both the PVD layers and the braze alloy shims. The gold and gold-containing brazes had problems, mainly due to the high diffusivity of gold in copper. These problems led to the necessity of overdriving the temperature to ensure melting, the presence of porosity in the joint, and very wide braze joints. Based on the overall findings of this study, a two-step joining method is proposed for fabricating the NLC structures. The structure would be assembled with pure silver braze inserts using a self-aligning step joint design, then the assembly would be vacuum diffusion bonded at 700 C and 3.45 MPa pressure to seal the critical inner portion of the assembly. Finally, during the same furnace cycle, the temperature would be increased to 800 C in order to react the silver with the copper to form a liquid braze alloy that would join and seal the outer portion of the cells together.

Elmer, J. W.; Klingmann, J.; van Bibber, K.

2001-05-01

25

Effect of Hydrogen Bond on Coal Extraction by In-situ Vacuum FTIR  

Microsoft Academic Search

Coal chemical formation environment might result in different properties of hydrogen bonds in coal structure. The thermo stability, amount and types of hydrogen bond in six typical Chinese coal macerals were investigated by in situ vacuum Fourier transform infrared spectroscopy (FTIR). It was found that three types of hydrogen bond were involved in coal structure, which were OH-N, OH self

J. Li; J. Feng; W.-Y. Li; H.-Z. Chang; K.-C. Xie

2009-01-01

26

Ultrasonic evaluation of beryllium-copper diffusion bonds  

SciTech Connect

A study was performed to compare the effectiveness of several advanced ultrasonic techniques when used to determine the strength of diffusion bonded beryllium-copper, which heretofore have each been applied to only a few material systems. The use of integrated backscatter calculations, frequency domain reflection coefficients, and time-of-flight variance was compared in their ability to characterize the bond strength in a series of beryllium-copper diffusion bond samples having a wide variation in bond quality. Correlation of integrated backscatter calculations and time-of-flight variance with bond strength was good. Some correlation of the slope of the frequency based reflection coefficient was shown for medium and high strength bonds, while its Y-intercept showed moderate correlation for all bond strengths.

Jamieson, E.E.

2000-06-08

27

Strength, ultrasonic and metallurgical evaluation of diffusion bonds of dissimilar materials.  

National Technical Information Service (NTIS)

Diffusion bonding is a well known metallurgical joining technique which allows materials to be bonded together to near net shape. Diffusion bonds between dissimilar materials are of unique interest due to the complex interactions at the bond line. Previou...

G. C. Ojard

1991-01-01

28

Diffuser-ejector system for a very high vacuum environment  

SciTech Connect

A system for testing space engines at sea level under a very low pressure environment. The system includes a space simulation chamber connected to a diffuser, which has two variable area ratio ejectors connected to it in tandem. Each of the ejectors is driven by a jet engine, preferably a turbo jet. The system is capable of providing a low pressure environment of about three or four millimeters of mercury for testing of engines mounted in the space simulation chamber. The system also may be used for other purposes requiring very high vacuum, such as evaporation and dehydration of food products or drugs.

Riggs, K.E.

1984-06-19

29

NickelTin Transient Liquid Phase (TLP) Wafer Bonding for MEMS Vacuum Packaging  

Microsoft Academic Search

This paper reports vacuum data for nickel-tin transient liquid phase (TLP) wafer bonding. Two wafers, one with a titanium getter and another with Pirani vacuum sensors, were bonded for 1.5 hours at 300 C. Initial pressures were as low as 200 mTorr and have remained stable for half a month. After several days, some of the packages were heated to

W. C. Welch; K. Najafi

2007-01-01

30

Fineblanking, Diffusion Bonding, and Testing of Fluidic Laminates.  

National Technical Information Service (NTIS)

Two manufacturing processes that show promise of improving the performance of laminated aluminum fluidic components are fineblanking and semi-solid-state diffusion bonding. A representative three-stage amplifier design was used as the basis for evaluating...

L. K. Pecan

1980-01-01

31

Micro thermal shear stress sensor based on vacuum anodic bonding and bulk-micromachining  

NASA Astrophysics Data System (ADS)

This paper describes a micro thermal shear stress sensor with a cavity underneath, based on vacuum anodic bonding and bulk micromachined technology. A Ti/Pt alloy strip, 2?m 100?m, is deposited on the top of a thin silicon nitride diaphragm and functioned as the thermal sensor element. By using vacuum anodic bonding and bulk-si anisotropic wet etching process instead of the sacrificial-layer technique, a cavity, functioned as the adiabatic vacuum chamber, 200?m 200?m 400?m, is placed between the silicon nitride diaphragm and glass (Corning 7740). This method totally avoid adhesion problem which is a major issue of the sacrificial-layer technique.

Yi, Liang; Ou, Yi; Shi, Sha-Li; Ma, Jin; Chen, Da-Peng; Ye, Tian-Chun

2008-06-01

32

Influence of interface microstructure on the mechanical properties of titanium\\/17-4 PH stainless steel solid state diffusion bonded joints  

Microsoft Academic Search

In the present study, titanium was diffusion bonded to a type 17-4 precipitation hardening stainless steel in vacuum at different temperatures and times. Bonded samples were characterized using light microscopy, scanning electron microscopy (SEM) and X-ray diffraction technique (XRD). The inter-diffusion of the chemical species across the diffusion interface was evaluated by electron probe microanalysis (EPMA). Up to 850C for

S. Kundu; D. Roy; S. Chatterjee; D. Olson; B. Mishra

33

Superplastic Forming & Diffusion Bonding of CORONA 5.  

National Technical Information Service (NTIS)

The processing of CORONA 5 (Ti-4.5 Al-5 Mo-1.5 Cr) to cold-rolled sheet and the subsequent evaluation of this sheet for superplastic formability, diffusion bondability and post-forming heat treatment response is discussed. Two heats of CORONA 5, one of 's...

J. Chesnutt C. H. Hamilton C. F. Yolton

1981-01-01

34

Diffusion bonding resistant valve development for sodium service  

SciTech Connect

Unanticipated functional failures occurred in valves undergoing containment integrity testing for liquid sodium service. The failures resulted from diffusion bonding of the Stellite 6B valve plug to the Type 316 stainless steel (SS) seat. As a result of these failures, a valve development program was undertaken. A modified valve incorporating a Tribaloy 800 plug showed significant improvement in resistance to diffusion bonding but still failed after long term exposure in a closed position. A second modified valve using Tribaloy 800 in both the valve plug and seat successfully resisted diffusion bonding failure. This paper reports the details of the testing and posttest valve examinations. The results of scanning electron microscopy, dispersive x-ray spectrometry, and metallography provide the characteristics of the valve failures. Limitations of the various valve designs are also discussed.

Crandall, D.L.; Low, J.O.; Chung, D.T.; Loop, R.B.

1984-04-16

35

Diffusion bonding of commercially pure Ni using Cu interlayer  

SciTech Connect

The concentration dependence of diffusivity in a multi-component diffusion system makes it complicated to predict the concentration profiles of diffusing species. This so called chemical diffusivity can be expressed as a function of thermodynamic and kinetic data. DICTRA software can calculate the concentration profiles using appropriate mobility and thermodynamic data. It can also optimize the diffusivity data using experimental diffusivity data. Then the optimized diffusivity data is stored as mobility data which is a linear function of temperature. In this work, diffusion bonding of commercially pure Ni using Cu interlayers is reported. The mobility parameters of Ni-Cu alloy binary systems were optimized using DICTRA/Thermocalc software from the available self-, tracer and chemical diffusion coefficients. The optimized mobility parameters were used to simulate concentration profiles of Ni-Cu diffusion joints using DICTRA/Thermocalc software. The calculated and experimental concentration profiles agreed well at 1100 Degree-Sign C. Agreement between the simulated and experimental profiles was less good at 1050 Degree-Sign C due to the grain boundary contribution to the overall diffusion. - Highlights: Black-Right-Pointing-Pointer The concentration profiles of Cu in Ni-Cu diffusion joints are modeled. Black-Right-Pointing-Pointer Interdiffusion coefficients in Ni-Cu system are optimized. Black-Right-Pointing-Pointer Optimized interdiffusion coefficients are expressed as mobility parameters. Black-Right-Pointing-Pointer Simulated profiles are comparable with experimental profiles.

Rahman, A.H.M.E., E-mail: a.rahman@my.und.edu; Cavalli, M.N.

2012-07-15

36

Characterization of diffusion bonded joint between titanium and 304 stainless steel using a Ni interlayer  

SciTech Connect

Solid-state diffusion bonded joints were prepared between commercially pure titanium and 304 stainless steel with nickel as an intermediate material in the temperature range of 800-950 deg. C for 10.8 ks under a 3 MPa uniaxial pressure in vacuum. The interface microstructures and reaction products of the transition joints were investigated by optical and scanning electron microscopy. Up to 850 deg. C processing temperature, a 300-{mu}m nickel interlayer completely restricts the diffusion of titanium to stainless steel. However, the nickel interlayer cannot block the diffusion of Ti to the stainless side and {lambda} + {chi} + {alpha}-Fe, {lambda} + FeTi and {lambda} + FeTi + {beta}-Ti phase mixtures are formed at the SS-Ni interface, when bonding was processed at 900 deg. C and above. These reaction products were confirmed by X-ray diffraction. A maximum tensile strength of {approx} 270 MPa and shear strength of {approx} 194 MPa, along with 6.2% ductility, were obtained for the diffusion bonded joint processed at 850 deg. C. Fracture surface observation in SEM using EDS demonstrates that failure occurred through the Ni-Ti interface of the joints when processed up to 850 deg. C and through the SS-Ni interface when processed at and above 900 deg. C.

Kundu, S. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah - 711103 (India)], E-mail: erskundu@yahoo.com; Chatterjee, S. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah - 711103 (India)], E-mail: schatterjee46@yahoo.com

2008-05-15

37

Reliable vacuum packaging using NanoGetters and glass frit bonding  

Microsoft Academic Search

A new approach to vacuum packaging micromachined resonant, tunneling, and display devices will be covered in this paper. A multi-layer, thin-film getter, called a NanoGetter, which is particle free and does not increase the chip size of the microsystem has been developed and integrated into conventional wafer-to-wafer bonding processes. Experimental data taken with chip-scale packages using glass frit bonding between

Douglas Sparks; Sonbol Massoud-Ansari; Nader Najafi

2003-01-01

38

Silicon layer transfer by hydrogen implantation combined with wafer bonding in ultrahigh vacuum  

SciTech Connect

A layer transfer method was developed by combining in situ photothermal activation of hydrogen passivated surfaces, ultrahigh vacuum bonding, and hydrogen-implantation induced splitting. Structural and electrical investigations showed that ultrathin, single crystalline silicon layers can be transferred to appropriate substrates without the involvement of an intermediate layer such as an oxide or solder. Significant current flow across such produced silicon-silicon bonded interfaces was observed, making this approach very attractive for material integration.

Fecioru, Alin Mihai; Senz, Stephan; Scholz, Roland; Goesele, Ulrich [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany)

2006-11-06

39

A local view of bonding and diffusion at metal surfaces  

SciTech Connect

First-principles density functional calculations and corresponding experimental results underline the importance of basic chemical concepts, such as coordination, valence saturation and promotion-hybridization energetics, in understanding bonding and diffusion of atoms at and on metal surfaces. Several examples are reviewed, including outer-layer relaxations of clean hcp(0001) surfaces, liquid-metal-embrittlement energetics, separation energies of metal-adatom dimers, concerted substitutional self-diffusion on fcc(001) surfaces, and adsorption and diffusion barrier sites for adatoms near steps.

Feibelman, P.J.

1996-09-01

40

Diffusion bonding resistant valve development for sodium service  

Microsoft Academic Search

Unanticipated functional failures occurred in valves undergoing containment integrity testing for liquid sodium service. The failures resulted from diffusion bonding of the Stellite 6B valve plug to the Type 316 stainless steel (SS) seat. As a result of these failures, a valve development program was undertaken. A modified valve incorporating a Tribaloy 800 plug showed significant improvement in resistance to

D. L. Crandall; J. O. Low; D. T. Chung; R. B. Loop

1984-01-01

41

Diffusion Bonding System for Steel Tubes and Pipes.  

National Technical Information Service (NTIS)

A high-speed diffusion bonding system for joining small and medium diameter tubulars using amorphous metals has been newly developed. Amorphous metal welding is an innovative method that results in less deterioration of the heat affected zone and less the...

Y. Komizo F. Kashimoto S. Kishi K. Kitano M. Tomabechi

1990-01-01

42

Vacuum packaging technology using localized aluminum\\/silicon-to-glass bonding  

Microsoft Academic Search

A glass vacuum package based on localized aluminum\\/silicon-to-glass bonding has been successfully demonstrated. A constant heat flux model shows that heating can be confined locally in the dielectric layer underneath a microheater as long as the width of the microheater and the thickness of silicon substrate are much smaller than the die size and a good heat sink is placed

Y.-T. Cheng; Wan-Tai Hsu; K. Najafi; C. T.-C. Nguyen; Liwei Lin

2002-01-01

43

Effect of vacuum on high-temperature degradation of gold\\/aluminum wire bonds in PEMs  

Microsoft Academic Search

Gold\\/aluminum wire bond degradation is one of the major failure mechanisms limiting reliability of plastic encapsulated microcircuits (PEMs) at high temperatures, It is known also that oxidative degradation is the major cause of failures in epoxy composite materials; however, the effect of oxygen and\\/or vacuum conditions on degradation of PEMs has not been studied yet. In this work, three groups

Alexander Teverovsky

2004-01-01

44

Reliable vacuum packaging using NanoGetters and glass frit bonding  

NASA Astrophysics Data System (ADS)

A new approach to vacuum packaging micromachined resonant, tunneling, and display devices will be covered in this paper. A multi-layer, thin-film getter, called a NanoGetter, which is particle free and does not increase the chip size of the microsystem has been developed and integrated into conventional wafer-to-wafer bonding processes. Experimental data taken with chip-scale packages using glass frit bonding between the Pyrex and silicon wafers, has resulted in silicon resonators in which Q values in excess of 37,000 have been obtained. Reliability data for vacuum-sealed diaphragms and resonators will be presented. Unlike previous reliability studies without getters, no degradation in Q has been noted with NanoGetter parts after extended high temperature storage. Applications for this technology include gyroscopes, accelerometers, displays, flow sensors, density meters, IR sensors, microvacuum tubes, RF-MEMS, pressure sensors and other vacuum sealed devices.

Sparks, Douglas; Massoud-Ansari, Sonbol; Najafi, Nader

2003-12-01

45

DIFFUSION BONDING HIGH-TEMPERATURE ALLOYS WITH BERYLLIUM. BERYLLIUM TRANSPORT ALLOY STRIPS PRODUCE DIFFUSION-BONDED JOINTS IN 1 OVER 2 TO 5 MIN AT 1940 TO 2100 F BONDING TEMPERATURES  

Microsoft Academic Search

The concepts and advantages of diffusion bonding hightemperature alloys ; with beryllium are discussed, and a practical method for diffusion bonding is ; presented. Results show that beryllium is a useful primary diffuser element for ; diffusion-bonding iron, nickel, and cobaltbase high temperature alloys. ; Beryllium-transport alloys are also developed that facilitate preplacement of ; beryllium at interfaces between base

W. Feduska; W. L. Horigan

1962-01-01

46

Contacting surfaces; A problem in fatigue and diffusion bonding  

SciTech Connect

Contact between surfaces usually occurs at asperities under compression or at connecting ligaments, depending on how the interface is formed. This paper deals with the nondestructive evaluation of the topology of contact and with the use of this information to predict the effects that loads borne by these contacts have on mechanical properties. Two specific examples are discussed: a fatigue crack and a diffusion bond. Asperity contact along the fracture surface of a fatigue crack partially shields the crack tip from the externally applied driving force. Using information from acoustic experiments, the geometry of the asperities, the contacting stress, and the shielding stress intensity factor have been estimated. Acoustically, a diffusion bonded interface looks very similar to that joining the two sides of a partially closed crack. In this particular case, the acoustically determined geometry of well-bonded ligaments can be verified by fractography of destructively tested samples whose bond strength has also been determined. Models to determine the bond strength from the ligament geometry are suggested.

Buck, O.; Thompson, R.B.; Rehbein, D.K.; Brasche, L.J.H. (Ames Lab., IA (USA)); Palmer, D.D. (Burns and McDonnell Engineering Co., Kansas City, MO (USA))

1989-04-01

47

Evolution of Copper Vapor from the Cathode of a Diffuse Vacuum Arc  

Microsoft Academic Search

The metal-vapor evolution from the cathode of a diffuse vacuum arc is described by a model that starts from the expression for the collisionless expansion into vacuum of atoms originating from an instantaneous point source. The velocity distribution is assumed to be Maxwellian at the moment the atoms are released from the source. By convolution with the vapor generation rate,

G. Lins

1987-01-01

48

Use of a vacuum-formed plastic sheet to aid in transferring and bonding metal splints.  

PubMed

Mobile teeth with compromised periodontal support may shift from their unstressed position during clinical splinting procedures and be stabilized in an incorrect position, resulting in occlusal interferences and unnecessary adjustment. A technique is presented that can be helpful to splint mobile teeth with a metal device. Using a vacuum or pressure device to create a mold using a cast transfers the splint intraorally for bonding. This thermoplastic sheet maintains mobile teeth in the desired position during the splinting procedure. PMID:17854626

Mountouris, George; Anagnostou, Maria; Papazoglou, Efstratios

2007-09-01

49

Diffusion bonding of grey cast iron to ARMCO iron and a carbon steel  

Microsoft Academic Search

The microstructure transformations produced during the diffusion bonding of grey cast iron to pure iron (ARMCO iron) and to a hypoeutectic steel (0.55% C) have been studied. The indirect determination of the carbon concentration profiles has produced a diffusion equation that relates the microstructure of the bond interface to the bonding temperature and time. A new tensile test specimen is

F. A. Calvo; A. Urea; J. M. Gomez de Salazar; F. Molleda

1989-01-01

50

Diffusion Bonding of Stainless Steel to Copper with Tin Bronze and Gold Interlayers  

NASA Astrophysics Data System (ADS)

Vacuum diffusion bonding of stainless steel to copper was carried out at a temperature ranging from 830 to 950 C under an axial pressure of 3 MPa for 60 min with three kinds of interlayer metals: tin-bronze (TB) foil, Au foil, and TB-Au composite interlayer. The results showed that the grain boundary wetting was formed within the steel adjacent to the interface due to the contact melting between TB and Au when TB-Au composite interlayer was used. The grain boundary wetting could occur at a relatively low temperature of 830 C and becomes significant with the increase of temperature. The tensile strength of the joint with TB-Au was higher than that with TB or Au interlayer separately and could be 228 MPa at the joining temperature of 850 C. Furthermore, the axial compression ratio of the specimen joined at 850 C was approximately 1.2%. Therefore, a reliable and precise joining of stainless steel to copper could be realized by diffusion bonding with the TB-Au composite interlayer at a comparatively low temperature.

Xiong, Jiang-Tao; Xie, Qing; Li, Jing-Long; Zhang, Fu-Sheng; Huang, Wei-Dong

2012-01-01

51

The diffusion bonding of silicon carbide and boron carbide using refractory metals  

SciTech Connect

Joining is an enabling technology for the application of structural ceramics at high temperatures. Metal foil diffusion bonding is a simple process for joining silicon carbide or boron carbide by solid-state, diffusive conversion of the metal foil into carbide and silicide compounds that produce bonding. Metal diffusion bonding trials were performed using thin foils (5 {micro}m to 100 {micro}m) of refractory metals (niobium, titanium, tungsten, and molybdenum) with plates of silicon carbide (both {alpha}-SiC and {beta}-SiC) or boron carbide that were lapped flat prior to bonding. The influence of bonding temperature, bonding pressure, and foil thickness on bond quality was determined from metallographic inspection of the bonds. The microstructure and phases in the joint region of the diffusion bonds were evaluated using SEM, microprobe, and AES analysis. The use of molybdenum foil appeared to result in the highest quality bond of the metal foils evaluated for the diffusion bonding of silicon carbide and boron carbide. Bonding pressure appeared to have little influence on bond quality. The use of a thinner metal foil improved the bond quality. The microstructure of the bond region produced with either the {alpha}-SiC and {beta}-SiC polytypes were similar.

Cockeram, B.V.

1999-10-01

52

Microstructures of diffusion bonded SiC ceramics using Ti and Mo interlayers  

NASA Astrophysics Data System (ADS)

SiC plates were diffusion bonded using metallic interlayers of Ti and Mo foils. For the joining, a uniaxial pressure of 7 MPa was applied at 1400 C for 1 h in a vacuum. The interfacial microstructures along with their atomic compositions of the SiC/SiC joints were analyzed. For the Ti interlayer, Ti was converted into a Ti3SiC2 phase owing to the diffusion of silicon and carbon from the SiC part. A crystallographic orientation relationship was found between the SiC and Ti3SiC2 grains. At the middle of the Ti interlayer, a TiSi2 phase also existed, forming a dual-phase region. For the Mo interlayer, the diffusion of silicon into Mo induced the formation of the Mo5Si3C phase at the SiC/Mo interface. An unreacted metallic phase was still observed in the middle of the Mo insert. The shear strengths of the joints were 67 MPa and 76 MPa for the Ti and Mo interlayers, respectively.

Jung, Yang-Il; Kim, Sun-Han; Kim, Hyun-Gil; Park, Jeong-Yong; Kim, Weon-Ju

2013-10-01

53

Diffusion layers produced on carbon steel surface by means of vacuum chromizing process  

NASA Astrophysics Data System (ADS)

This work investigated diffusion layers produced on carbon (C) steel surfaces in the vacuum chromizing process. Studies of layer, thickness, morphology, and chromium (Cr), C, and iron (Fe) concentration depth profiles in the diffusion zone of chromized layers were carried out. The effect of process parameters such as time and temperature on the kinetics of layer growth on steel surface was investigated. The tribocorrosion resistance of chromized layers was determined.

Kasprzycka, Ewa; Senatorski, Jan; Nakonieczny, Aleksander; Babul, Tomasz

2003-12-01

54

Visualization and characterization of high-current diffuse vacuum arcs on axial magnetic field contacts  

Microsoft Academic Search

We have investigated the behavior of drawn vacuum arcs for several designs of axial magnetic field (AMF) contacts using high-speed digital photography and arc voltage measurements, As the peak current was increased, a gradual transition occurred in the arc appearance from a multiple cathode-spot arc to the high-current diffuse mode, and then to a high-current diffuse columnar mode. Two relatively

Michael B. Schulman; Hans Schellekens

2000-01-01

55

The metallurgical integrity of the frit vent assembly diffusion bond  

SciTech Connect

Iridium alloy clad vent sets (CVSs) are now being made by Energy Systems at the Oak Ridge Y-12 Plant. These CVSs are being made for the US Department of Energy`s (NE-53) General Purpose Heat Source- Radioisotope Thermoelectric Generator (GPHS-RTG) program, which is to supply electrical power for the National Aeronautics and Space Administration`s Cassini mission to Saturn. A GPHS-RTG has 72 CVSs. Each CVS encapsulates one {sup 238}PuO{sub 2} fuel pellet. The helium gas produced from the alpha decay of the {sup 238}Pu is vented through a nominal 0.45-mm-diam hole in the vent cup of each CVS. A frit vent assembly that is electron beam welded over the vent hole allows helium gas to escape but prevents plutonia fines from exiting. The metallurgical integrity of frit vent assemblies produced by Martin Marietta Energy Systems, Inc. (Energy Systems) were compared with those produced earlier by EG&G-Mound Applied Technology, Inc. (EG&G-MAT). Scanning electron microscope (SEM) photographs were taken (at magnifications of from 126X to 1,000X) of the starting frit vent powder and the diffusion-bonded powder in finished frit vent assemblies produced by Energy Systems and EG&G-MAT. Frit vent assemblies also were metallographically prepared and visually examined/photographed at magnifications of from 50X to 1,000X. The SEM and metallographic examinations of the particle-to-particle and particle-to-foil component diffusion bonds indicated that the Energy Systems-produced and EG&G-MAT-produced frit vent assemblies have comparable metallurgical integrity. Statistical analysis of the Energy Systems production data shows that the frit vent manufacturing yield is 91%.

Ulrich, G.B. [Oak Ridge Y-12 Plant, TN (United States). Process Metallurgy Dept.

1994-06-01

56

Transition from constricted to diffuse vacuum arc modes during high-current interruption  

Microsoft Academic Search

Modes of high current vacuum arc between butt contacts at a fixed gap of 10 mm during the decrease of current to zero were characterised. Three groups of arc modes were featured: (i) constricted-without a significant share of individual cathode spots; (ii) constricted-with a considerable number of cathode spots beyond the concentrated cathode root; and (iii) diffuse modes. It was

Z. Zalucki; J. Janiszewski

1998-01-01

57

On the Formation of a Diffusion Bond from Cold-Spray Coatings  

NASA Astrophysics Data System (ADS)

To understand the development of diffusion bonding, which can increase the bonding strength, three different cold-sprayed coating/substrate systems were investigated, Ni/Cu, Cu/Cu, and Al/Mg, by annealing at increased temperatures for various times. The formation of intermetallic compounds in the Al/Mg system reduced the bonding strength dramatically. In Cu/Cu and Ni-Cu, diffusion bonds developed at lower temperatures as Ni-Cu forms an isomorphous system, which increased the bonding strength effectively. However, higher temperature annealing reduced bonding strength ultimately because of the Kirkendall pores.

Wang, Qiang; Birbilis, Nick; Zhang, Ming-Xing

2012-05-01

58

Effects of Pulse Current on Transient Liquid Phase (TLP) Diffusion Bonding of SiCp/2024Al Composites Sheet Using Mixed Al, Cu, and Ti Powder Interlayer  

NASA Astrophysics Data System (ADS)

The effects of pulse current on transient liquid phase (TLP) diffusion bonding of SiCp/2024Al composites sheet were investigated at 853 K (580 C) using a mixed slurry of Al, Cu, and Ti powder interlayer. The process parameters were as follows: the pulse current density of 1.15 102 A/mm2, the original pressure of 0.5 MPa, the vacuum of 1.3 10-3 Pa, and the bonding time from 15 to 60 minutes. Moreover, the bonding mechanism in correlation with the microstructural and mechanical properties variation was analyzed.

Wang, Bo; Jiang, Shaosong; Zhang, Kaifeng

2012-09-01

59

Vacuum outgassing from diffuse-absorptive baffle materials  

SciTech Connect

Measurements of outgassing have been made from Martin black and a variety of diffuse absorptive baffle materials under development for radiation resistant stray light management. Outgassing measurements were made during pumpdown from atmosphere at room temperature. Mass scans indicate water was the major outgassing species for all materials tested. Calibrated measurements of water vapor outgassing as a function of time were also made for each baffle material. Most baffle materials exhibited total water vapor outgassed during pumpdown of between 1 {times} 10{sup {minus}5} and 4 {times} 10{sup {minus}5} moles/cm{sup 2}. Plasma sprayed beryllium currently under development exhibited approximately an order of magnitude lower total water vapor outgassed during pumpdown. 7 figs., 2 tabs.

Egert, C.M. (Oak Ridge National Lab., TN (USA)); Basford, J.A. (Oak Ridge Y-12 Plant, TN (USA))

1990-01-01

60

Microlens array coated as a high-efficiency reflective diffuser for the vacuum ultraviolet  

NASA Astrophysics Data System (ADS)

The stimulus for ultraviolet flat fields (STUFF) was developed to supply spatially flat, broadband, far ultraviolet irradiance in thermal vacuum testing of the Solar Blind Channel (SBC) of the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) which will fly on Servicing Mission 3b in mid-2001. Because the SBC's 1K X 1K multi-anode microchannel array (MAMA) detector has a global count rate limit of about 300,000 events/s, it takes a minimum of roughly 10 hours of expensive test time in thermal vacuum to collect a deep flat field having 10,000 signal counts in each pixel (1% certainty in Poisson statistics). As such, a diffuser with far ultraviolet (FUV) throughput substantially higher than conventional state-of-the-art Lambertian diffuser material was sought to insure that the length of flat field exposures could be minimized. An FUV diffuser with concentrating properties was conceived as the overcoating of the convex lens side of commercially available microlens array material with Goddard Space Flight Center's (GSFC) standard aluminum-magnesium fluoride coating optimized for reflectance at 120 nm. The concept for this diffuser, a geometric optical model of its performance, visible light measurements to test that model, and the diffuser's FUV performance in STUFF relative to conventional diffuser material is presented.

Leviton, Douglas B.; Miner, Linda A.; Rice, Stephen H.; Struss, Sharon M.; Norton, Todd A.; McNeil, Brian

2000-12-01

61

Research on Transient Liquid Phase Diffusion Bonding of Steel Sandwich Panels Under Small Plastic Deformation  

Microsoft Academic Search

Plastic deformation was newly introduced in transient liquid phase (TLP) diffusion bonding of steel sandwich panels. The effect\\u000a of plastic deformation on bonding strength was investigated through lab experiments. It was assumed that three factors, including\\u000a newly generated metal surface area, deformation heat, and lattice distortion, contribute to the acceleration of interface\\u000a atoms diffusion and increase of diffusion coefficients. A

H. Li; Z. X. Li

2008-01-01

62

High-current diffuse vacuum arcs on axial magnetic field contacts: arc visualization and contact temperature  

Microsoft Academic Search

We have investigated the behavior of drawn vacuum arcs for several designs of axial magnetic field (AMF) CuCr contacts using high-speed digital photography, arc voltage measurements and near IR photography of the contacts after current zero. As the peak current was increased, a gradual transition occurred in the arc appearance from a multiple cathode-spot arc to the high-current diffuse mode,

H. Schellekensa; M. B. Schulmanb

2000-01-01

63

A Batch Wafer Scale LIGA Assembly and Packaging Technique vai Diffusion Bonding  

SciTech Connect

A technique using diffusion bonding (or solid-state welding) has been used to achieve batch fabrication of two- level nickel LIGA structures. Interlayer alignment accuracy of less than 1 micron is achieved using press-fit gauge pins. A mini-scale torsion tester was built to measure the diffusion bond strength of LIGA formed specimens that has shown successful bonding at temperatures of 450"C at 7 ksi pressure with bond strength greater than 100 Mpa. Extensions to this basic process to allow for additional layers and thereby more complex assemblies as well as commensurate packaging are discussed.

Christenson, T.R.; Schmale, D.T.

1999-01-27

64

Diffusion Bonding of Microduplex Stainless Steel and Ti Alloy with and without Interlayer: Interface Microstructure and Strength Properties  

NASA Astrophysics Data System (ADS)

The interface microstructure and strength properties of solid state diffusion bonding of microduplex stainless steel (MDSS) to Ti alloy (TiA) with and without a Ni alloy (NiA) intermediate material were investigated at 1173 K (900 C) for 0.9 to 5.4 ks in steps of 0.9 ks in vacuum. The effects of bonding time on the microstructure of the bonded joint have been analyzed by light optical microscopy and scanning electron microscopy in the backscattered mode. In the direct bonded joints of MDSS and TiA, the layer-wise ? phase and the ? + FeTi phase mixture were observed at the bond interface when the joint was processed for 2.7 ks and above holding times. However, when NiA was used as an intermediate material, the results indicated that TiNi3, TiNi, and Ti2Ni are formed at the NiA-TiA interface, and the irregular shaped particles of Fe22Mo20Ni45Ti13 have been observed within the TiNi3 intermetallic layer. The stainless steel-NiA interface is free from intermetallics and the layer of austenitic phase was observed at the stainless steel side. A maximum tensile strength of ~520 MPa, shear strength of ~405 MPa, and impact toughness of ~18 J were obtained for the directly bonded joint when processed for 2.7 ks. However, when nickel base alloy was used as an intermediate material in the same materials, the bond tensile and shear strengths increase to ~640 and ~479 MPa, respectively, and the impact toughness to ~21 J when bonding was processed for 4.5 ks. Fracture surface observations in scanning electron microscopy using energy dispersive spectroscopy demonstrate that in MDSS-TiA joints, failure takes place through the FeTi + ? phase when bonding was processed for 2.7 ks; however, failure takes place through ? phase for the diffusion joints processed for 3.6 ks and above processing times. However, in MDSS-NiA-TiA joints, the fracture takes place through NiTi2 layer at the NiA-TiA interface for all bonding times.

Kundu, S.; Sam, S.; Mishra, B.; Chatterjee, S.

2013-10-01

65

Diffusion bonding of electroless Ni plated WC composite to Cu and AISI 316 stainless steel  

Microsoft Academic Search

In this study, a composite containing WC (Tungsten Carbide) and Ni was produced by two different processing routes. Electroless\\u000a Ni coated WC powders were consolidated and sintered at 1200 C. Diffusion bonding couples of WC(Ni)-electrolytic Cu, WC(Ni)-AISI\\u000a 316 stainless steel and WC(Ni)-WC(Ni) were manufactured by using a preloaded compression system under Ar atmosphere. Diffusion\\u000a bonding was carried out at varying

Ahmet Ynetken; Mehmet akmakkaya; Ayhan Erol; ?kr Tala?

2011-01-01

66

Diffusion bonding and brazing of high purity copper for linear collider accelerator structures  

Microsoft Academic Search

Diffusion bonding and brazing of high purity copper were investigated to develop procedures for joining precision machined copper components for the Next Linear Collider (NLC). Diffusion bonds were made over a range of temperatures from 400 C to 1000 C, under two different loading conditions [3.45 kPa (0.5 psi) and 3.45 MPa (500 psi)], and on two different diamond machined

J. W. Elmer; J. Klingmann; K. van Bibber

2001-01-01

67

Technologies of joining between ITER reference grade beryllium and copper alloys by diffusion bonding process  

Microsoft Academic Search

The design of plasma-facing components for ITER relies on the use of junctions for coupling the armor materials to the heat sink and cooling tubes. A suitable diffusion bonding process for manufacturing the high heat flux components of ITER has been developed. The dependence of the load applied on the sample, the bonding temperature, the dwell time and surface preparation

E. Visca; E. Di Pietro; G. Ceccotti; G. Mercurio

1996-01-01

68

Superconducting joint of Bi-2223/Ag superconducting tapes by diffusion bonding  

NASA Astrophysics Data System (ADS)

61-Filaments Bi-2223/Ag superconducting tapes have been joined by diffusion bonding. The critical currents (ICs) of the joints are obtained by using standard four probe method under no magnetic field in the liquid nitrogen. The microstructures of the joints are evaluated by the electron microscope in electron backscatter diffraction mode and the phase compositions of the superconducting cores of the joint and the original tape are determined by X-ray diffraction (XRD). The results show diffusion bonding is effective bonding technique for HTS tapes, and the bonding time is reduced greatly from hundreds of hours to a few hours, and the bonding pressure also changes from 140-4000 MPa to 3 MPa. Furthermore, the diffusion bonding joints sustain superconducting properties, and the critical current ratios (CCRO) of the joints are in the range of 35%-80%. Microstructures of the typical joint display a good bonding and some defects existed in traditional method are avoided. XRD results show that the phase compositions of the superconducting cores have no obvious changes before and after diffusion bonding, which offers physical and material bases for high superconducting property of the joints.

Guo, Wei; Zou, Guisheng; Wu, Aiping; Wang, Yanjun; Bai, Hailin; Ren, Jialie

2009-11-01

69

Fracture and Fatigue of Diffusion, Adhesive, and Roll Bonded Aluminum, Titanium, and Ultrahigh Carbon Steel Laminates.  

National Technical Information Service (NTIS)

The fracture characteristics of twelve different diffusion bonded Al/Al, Ti/Ti and Ultrahigh Carbon Steel/Iron and adhesively bonded Al/Epoxy laminates were evaluated. The effects of periodic overloads on the fatigue crack retardation behavior in a roll b...

R. M. Johnson

1978-01-01

70

Effect of Vacuum on the Diffusion Mobility of Ni in Mo (Vliyanie Yakuuma na Diffuzionnuyu Podvizhnost Nikel ya v Molibdene).  

National Technical Information Service (NTIS)

The rate of diffusion of the isotope Ni-63 in single crystals of Mo is measured at 1350C in vacuums of 0.1 and 0.00001 Torr. Within the accuracy and precision of the experiment, no significant difference in diffusion coefficients (2.4 vs 3.2 x 10 to the -...

N. A. Makhlin L. I. Ivanov

1974-01-01

71

A Study on Diffusion Pump Oil by the Mass Spectrometer and the Gas Analysis of the Final Vacuum  

Microsoft Academic Search

Diffusion pump oil is analysed by the mass spectrometer, especially for the purpose of obtaining some knowledge about the residual gases at the final vacuum when we use oil diffusion pumps. As a sample, we take alkyl-naphtalene and its spectrum is given graphically. The results of our analyses of residual gases confirm the conclusions obtained by Hickman and Blears.

Kazuo Hisatake; Kazuhisa Matsuda

1953-01-01

72

The fabrication of all-silicon micro gas chromatography columns using gold diffusion eutectic bonding  

NASA Astrophysics Data System (ADS)

Temperature programming of gas chromatography (GC) separation columns accelerates the elution rate of chemical species through the column, increasing the speed of analysis, and hence making it a favorable technique to speedup separations in microfabricated GCs (micro-GC). Temperature-programmed separations would be preferred in an all-silicon micro-column compared to a silicon-Pyrex micro-column given that the thermal conductivity and diffusivity of silicon is 2 orders of magnitude higher than Pyrex. This paper demonstrates how to fabricate all-silicon micro-columns that can withstand the temperature cycling required for temperature-programmed separations. The columns were sealed using a novel bonding process where they were first bonded using a gold eutectic bond, then annealed at 1100 C to allow gold diffusion into silicon and form what we call a gold diffusion eutectic bond. The gold diffusion eutectic-bonded micro-columns when examined using scanning electron microscopy (SEM), scanning acoustic microscopy (SAM) and blade insertion techniques showed bonding strength comparable to the previously reported anodic-bonded columns. Gas chromatography-based methane injections were also used as a novel way to investigate proper sealing between channels. A unique methane elution peak at various carrier gas inlet pressures demonstrated the suitability of gold diffusion eutectic-bonded channels as micro-GC columns. The application of gold diffusion eutectic-bonded all-silicon micro-columns to temperature-programmed separations (120 C min-1) was demonstrated with the near-baseline separation of n-C6 to n-C12 alkanes in 35 s.

Radadia, A. D.; Salehi-Khojin, A.; Masel, R. I.; Shannon, M. A.

2010-01-01

73

Diffusion bonding of beryllium to CuCrZr for ITER applications.  

SciTech Connect

Low temperature diffusion bonding of beryllium to CuCrZr was investigated for fusion reactor applications. Hot isostatic pressing was accomplished using various metallic interlayers. Diffusion profiles suggest that titanium is effective at preventing Be-Cu intermetallics. Shear strength measurements suggest that acceptable results were obtained at temperatures as low as 540C.

Cadden, Charles H.; Puskar, Joseph David; Goods, Steven Howard

2008-08-01

74

Diffusion bonding of a superplastic Inconel 718SPF superalloy by electroless nickel plating  

SciTech Connect

Although intimate contact can be obtained for diffusion bonding of a superplastic Inconel 718SPF superalloy under a low pressure of 7 MPa, the precipitates formed at the interface retarded achievement of a sound joint. The shear strength was only 41.5 MPa for an overlap length of 12 T (T = 1.3 mm, sheet thickness). The diffusion bondability of t his Inconel 718SPF superalloy was enhanced by electroless nickel plating. In this situation, the bonding shear strength increased to 70.4 MPa for the same overlap length of 12 T under the same bonding condition, regardless of the roughness of the surface to be bonded. Upon decreasing the overlap length from 12 to 6T, the bonding strength remained constant.

Yeh, M.S.; Chang, C.B.; Chuang, T.H.

2000-02-01

75

Microstructure and strength of diffusion-bonded joints of TiAl base alloy to steel  

SciTech Connect

Diffusion bonding of TiAl-based alloy to steel was carried out at 850-1100 deg. C for 1-60 min under a pressure of 5-40 MPa in this paper. The relationship of the bond parameters and tensile strength of the joints was discussed, and the optimum bond parameters were obtained. When products are diffusion-bonded, the optimum bond parameters are as follows: bonding temperature is 930-960 deg. C, bonding pressure is 20-25 MPa, bonding time is 5-6 min. The maximum tensile strength of the joint is 170-185 MPa. The reaction products and the interface structures of the joints were investigated by scanning electron microscopy (SEM), electron probe X-ray microanalysis (EPMA) and X-ray diffraction (XRD). Three kinds of reaction products were observed to have formed during the diffusion bonding of TiAl-based alloy to steel, namely Ti{sub 3}Al+FeAl+FeAl{sub 2} intermetallic compounds formed close to the TiAl-based alloy. A decarbonised layer formed close to the steel and a face-centered cubic TiC formed in the middle. The interface structure of diffusion-bonded TiAl/steel joints is TiAl/Ti{sub 3}Al+FeAl+FeAl{sub 2}/TiC/decarbonised layer/steel, and this structure will not change with bond time once it forms. The formation of the intermetallic compounds results in the embrittlement of the joint and poor joint properties. The thickness of each reaction layer increases with bonding time according to a parabolic law. The activation energy Q and the growth velocity K{sub 0} of the reacting layer Ti{sub 3}Al+FeAl+FeAl{sub 2}+TiC in the diffusion-bonded joints of TiAl base alloy to steel are 203 kJ/mol and 6.07 mm{sup 2}/s, respectively. Careful control of the growth of the reacting layer Ti{sub 3}Al+FeAl+FeAl{sub 2}+TiC can influence the final joint strength.

He, P.; Feng, J.C.; Zhang, B.G.; Qian, Y.Y

2002-07-15

76

Diffusion bonding titanium to stainless steel using Nb/Cu/Ni multi-interlayer  

SciTech Connect

By using Nb/Cu/Ni structure as multi-interlayer, diffusion bonding titanium to austenitic stainless steel has been conducted. The effects of bonding temperature and bonding time on the interfacial microstructure were analyzed by scanning electron microscope equipped with energy dispersive spectroscope, and the joint strength was evaluated by tensile test. The results showed that Ni atoms aggregated at the Cu-Nb interface, which promoted Cu solution in Nb. This phenomenon forms a Cu-Nb solution strengthening effect. However, such effect would decay by using long bonding time that dilutes Ni atom aggregation, or be suppressed by using high bonding temperature that embrittles the Cu-Nb interface due to the formation of large grown intermetallic compounds. The sound joint was obtained by promoted parameters as 850 Degree-Sign C for 30-45 min, under which a bonding strength around 300 MPa could be obtained. - Highlights: Black-Right-Pointing-Pointer Titanium was diffusion bonded to stainless steel using Nb/Cu/Ni multi-interlayer. Black-Right-Pointing-Pointer The effects of bonding parameters on microstructure and joint strength were studied. Black-Right-Pointing-Pointer Nickel aggregation promotes Cu solution in Nb which can strengthen the joint. Black-Right-Pointing-Pointer The sound joint with strength of around 300 MPa was obtained by promoted parameters.

Li Peng [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072 (China); Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072 (China); Li Jinglong, E-mail: lijinglg@nwpu.edu.cn [Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072 (China); Xiong Jiangtao; Zhang Fusheng; Raza, Syed Hamid [Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072 (China)

2012-06-15

77

A probabilistic, semi-empirical approach to modeling diffusion bond strength.  

SciTech Connect

Manufacture of critical diffusion bonded components could benefit from predictive models of diffusion bond joint strength. Existing models focus on porosity closure, which is a necessary but not sufficient condition for acceptable joint strength. The present work identifies modeled dynamics intrinsic to manufacturing but not captured in existing models. Controls regulating these dynamics are proposed, and the topography of real engineering surfaces is described by distribution functions. Pore closure kinetics then can successfully link initial surface topography and final porosity distribution, which in turn correlates to joint strength given experimental data linking porosity to joint strength.

Dave, V. R. (Vivek R.); Hartman, D. A. (Daniel A.); Barieri, J. M. (Joann M.)

2001-01-01

78

Design and fabrication of high performance wafer-level vacuum packaging based on glass-silicon-glass bonding techniques  

NASA Astrophysics Data System (ADS)

In this paper, a high performance wafer-level vacuum packaging technology based on GSG triple-layer sealing structure for encapsulating large mass inertial MEMS devices fabricated by silicon-on-glass bulk micromachining technology is presented. Roughness controlling strategy of bonding surfaces was proposed and described in detail. Silicon substrate was thinned and polished by CMP after the first bonding with the glass substrate and was then bonded with the glass micro-cap. Zr thin film was embedded into the concave of the micro-cap by a shadow-mask technique. The glass substrate was thinned to about 100 m, wet etched through and metalized for realizing vertical feedthrough. During the fabrication, all patterning processes were operated carefully so as to reduce extrusive fragments to as little as possible. In addition, a high-performance micro-Pirani vacuum gauge was integrated into the package for monitoring the pressure and the leak rate further. The result shows that the pressure in the package is about 120 Pa and has no obvious change for more than one year indicating 10-13 stdcc s-1 leak rate.

Zhang, Jinwen; Jiang, Wei; Wang, Xin; Zhou, Jilong; Yang, Huabing

2012-12-01

79

Modification of a metallic surface in a vacuum arc discharge plasma using thermally stimulated ion diffusion  

NASA Astrophysics Data System (ADS)

A new process for modifying a metallic surface in a vacuum arc discharge plasma using thermally stimulated ion diffusion is considered. The effect of the bias voltage (negative substrate potential) on the processes that occur on the surface of a treated part is studied when the substrate material interacts with an accelerated metallic-ion flow. The phase and elemental compositions of the modified layer are studied for substrates made of nickel-based superalloys, austenitic and martensitic steels, and titanium-based alloys. The heat resistance, the salt corrosion resistance, and the corrosion cracking resistance of steels and titanium-based alloys are investigated after their modification in vacuum arc plasmas of pure metals (Ti, Zr, Al, Cr, Y) and related alloys. The surface modification caused by the thermally stimulated ion saturation of the surfaces of parts made from structural materials is shown to change the structural-phase states of their surfaces and, correspondingly, the properties of these materials in relation to the state of the surface.

Muboyadzhyan, S. A.

2008-12-01

80

The use of Kirkendall effect for calculating intrinsic diffusion coefficients in a 316L/Ti6242 diffusion bonded couple  

SciTech Connect

Some extreme applications require the metallurgical bonding of a corrosion resistant clad alloy and a high strength steel, since it is difficult to achieve the required mechanical properties and corrosion resistance in a single material. Ti alloys are good candidates to be used as the corrosion resistant cladding material, thus several combinations of steels and Ti alloys have been analyzed. Carbon steels are not suitable for this application because the carbon reacts with Ti and gives rise to the formation of Ti-carbides at the interface which impede the diffusion of the substitutional elements. Here the diffusion processes that take place across the interface are studied in more detail.

Aleman, B.; Gutierrez, I.; Urcola, J.J.

1997-03-01

81

The Breathing Orbital Valence Bond Method in Diffusion Monte Carlo: C-H Bond Dissociation ofAcetylene  

SciTech Connect

This study explores the use of breathing orbital valence bond (BOVB) trial wave functions for diffusion Monte Carlo (DMC). The approach is applied to the computation of the carbon-hydrogen (C-H) bond dissociation energy (BDE) of acetylene. DMC with BOVB trial wave functions yields a C-H BDE of 132.4 {+-} 0.9 kcal/mol, which is in excellent accord with the recommended experimental value of 132.8 {+-} 0.7 kcal/mol. These values are to be compared with DMC results obtained with single determinant trial wave functions, using Hartree-Fock orbitals (137.5 {+-} 0.5 kcal/mol) and local spin density (LDA) Kohn-Sham orbitals (135.6 {+-} 0.5 kcal/mol).

Domin, D.; Braida, Benoit; Lester Jr., William A.

2008-05-30

82

Transition to the diffuse mode for high-current drawn arcs in vacuum with an axial magnetic field  

Microsoft Academic Search

The opening of electrical contacts while passing current generates a drawn arc. In vacuum, the arc begins as a bridge of molten metal connecting the contacts, which then ruptures to form a bridge column arc. For butt contacts without an AMF at currents up to 16 kA peak, the bridge evolves into a transition mode before switching to a diffuse

Erik D. Taylor; Eaton Cutler-Hammer

2002-01-01

83

Beryllium-copper diffusion bonding for an ITER first wall application  

Microsoft Academic Search

Several different joint assemblies were evaluated in support of a manufacturing technology for diffusion bonding a beryllium armor tile to a copper alloy heat sink for fusion reactor applications. Because beryllium reacts with all but a few elements to form intermetallic compounds, this study considered several different surface treatments as a means of both inhibiting these reactions and promoting a

Ben C. Odegard Jr; C. H. Cadden

1997-01-01

84

Diffusion bonding of aluminium oxide to stainless steel using stress relief interlayers  

Microsoft Academic Search

Aluminium oxide was diffusion bonded to AISI 304 steel using Ti, Cu or Mo as interlayer materials. It was observed that Ti joins easily to both ceramic and steel parts, giving an average shear strength equal to 20 MPa. However, within the experimental conditions applied, the adhesion between Al2O3 and Cu or Mo was unsuccessful. A finite element modelling (FEM)

Dilermando Travessa; Maurizio Ferrante; Gert den Ouden

2002-01-01

85

Investigation of intergranular corrosion of 316L stainless steel diffusion bonded joint by electrochemical potentiokinetic reactivation  

Microsoft Academic Search

Electrochemical potentiokinetic reactivation technique (EPR) was employed to assess degree of sensitization in 316L stainless steel diffusion bonded joint (DBJ). The result showed the degree of sensitization of DBJ was much smaller than that of base material (BM). No chromium carbides precipitated at grain boundaries in DBJ after 100h treatment at 650C, while chromium carbides could be seen clearly in

Shu-Xin Li; Lei Li; Shu-Rong Yu; R. Akid; Hong-Bo Xia

2011-01-01

86

Spf\\/db hollow core fan blade. [SuperPlastically Formed\\/Diffusion Bonded  

Microsoft Academic Search

A hollow core rotor blade for a turbine engine, comprising: a generally airfoil-shaped outer structure comprised of a superplastically formed, diffusion bonded sheet material, the outer structure having a trailing edge and a leading edge and being comprised of a matrix structure, with generally longitudinally oriented composite fibers being embedded within the superplastically formed material to increase the bending stiffness

Velicki

1993-01-01

87

Diffusion Bonded EDM Electrode with Micro Holes for Jetting Dielectric Liquid  

Microsoft Academic Search

This paper describes improvement of machining characteristics of electrical discharge machining of deep slots using a tool electrode which has micro holes for jetting dielectric liquid over the working surface. The tool electrode was made by the diffusion bonding of two copper plates, over an interface on which micro grooves for jetting the dielectric fluid were formed using electrolyte jet

T. Shibayama; M. Kunieda

2006-01-01

88

Investigation of the process of diffusion bonding of alloys based on titanium nickelide  

Microsoft Academic Search

The results of investigations of diffusion bonding of an alloy based on titanium nickelide are presented. The effect of the welding conditions on the strength of the joint in sheet semi-finished products is investigated. The experimental results show that the main reason for the reduction in the mechanical properties of the welded joint is the interaction of the weld surfaces

K. S. Senkevich; S. D. Shlyapin

2012-01-01

89

Materials evaluation of diffusion bonded steel bar and its impact characteristics  

Microsoft Academic Search

When we apply non-destructive test for evaluating the soundness of weld joints it is necessary to know the mechanical properties of the joints by destructive test. In this paper we tried to obtain the correlation between the data by ultrasonic C-scope method and the absorbed energy by Charpy impact test for diffusion bonded steel bars. The surface roughness of specimens

Mitsuaki Katoh; Kazumasa Nishio; Tomiko Yamaguchi

2002-01-01

90

TEM characterization of diffusion bonding of superplastic 8090 Al-Li alloy  

SciTech Connect

In recent years there has been a growing interest in developing a joining process compatible with other fabrication technologies used in the aeronautical industry for superplastic aluminum-lithium alloys, and it is shown in numerous publications. There have been important advances in the research of the aluminum-lithium alloys diffusion bonding, and specially for the AA8090. However, joining of aluminum alloys by diffusion bonding encounters inherent problems which have not been solved yet. Most of these limitations come from the formation of protective oxide film (Al{sub 2}O{sub 3}) which covers the aluminum based materials. In spite of these unresolved difficulties, most of the investigators, among them are the present authors, have agreed that aluminum alloys which contain lithium as alloying element, present a higher weldability than Li-free aluminum ones. To explain this enhanced diffusion weldability in Li-doped alloys, it has been argued that Li favors the partial elimination of the unsoluble and tenacious alumina film, which acts as a diffusion barrier, through the formation of more soluble and brittle complex spinel (Al-Li-O). Nevertheless, the elimination of these oxides is not complete, resulting, in the most advantageous conditions, in a discontinuous distribution of oxide particles along the bonding interface which controls the final properties of the bond.

Urena, A.; Gomez de Salazar, J.M.; Quinones, J.; Martin, J.J. [Universidad Complutense de Madrid (Spain)

1996-02-15

91

3J-6 Diffusion-Bonded Transducers for Ultrasonic Flow Measuring and NDT Applications  

Microsoft Academic Search

This paper presents results related to design ultrasonic transducers with metallic waveguides on the base of copper and aluminum alloys and diffusion welding and brazing them to the external surface of the pipe wall. This approach provided reliable bonding clamp-on transducers and increasing the accuracy of flow measurements and the resolution in detecting defects. The choice of the Lamb wave

V. K. Hamidullin; V. N. Parfenov; G. R. Osokin; A. A. Gnedov; S. V. Nagaevski

2006-01-01

92

Ambient-temperature creep failure of silver-aided diffusion bonds between steel  

SciTech Connect

It has long been known that thin (e.g., 1 {mu}m {minus} 1 mm) interlayer bonds between higher strength base materials may have high ultimate tensile or rupture strengths despite the relatively low strength of the filler metal. The high strength of the joint is due to the mechanical constraint provided by the stronger base metals which restricts transverse contraction of the interlayer. The constraint produces a triaxial state or stress and reduces the effective stress, thus reducing the tendency for the interlayer to plastically deform. Plasticity of the base metal reduces the constraint and decreases the strength of the bond. The purpose of this work was twofold. First, the validity of the base-metal- accelerated'' delayed-failure theory for bonds utilizing plastic base metals was checked. Creep-rupture tests were performed on diffusion-bonded specimens using silver interlayers deposited by planar-magnetron sputtering (PMS), a physical vapor-deposition process. The PMS process was preferred because of the superior quality and strength of the bond and because this modern low-temperature joining process is increasingly utilized for joining ceramic and composite materials. The role of plastic base metals in the fracture process was further investigated by conducting tensile-rupture tests of diffusion bonds made with stainless steel base metals of different yield strengths, and therefore different creep rates. The second purpose was to determine whether delayed failure occurs in interlayer bonds between elastic base metals, which do not creep over the range of applied stresses. This question is particularly relevant since many alloys, ceramics and composites fall within this category. Again, ambient and near-ambient temperature creep-rupture tests were performed at a variety of stresses below the UTS of the bond. 25 refs., 7 figs.

Henshall, G.A.; Kassner, M.E.; Rosen, R.S.

1990-01-15

93

Development and analysis of diffusion bonding techniques for LBE-cooled spallation targets  

NASA Astrophysics Data System (ADS)

Spallation sources incorporating solid targets may be driven to utilize liquid metal coolants by neutronics or temperature concerns. If tungsten is chosen as the target material, it will require cladding given its poor performance under irradiation. One option to meet this need are ferritic/martensitic stainless steel alloys. This study investigates possible diffusion bonding techniques suitable to clad tungsten targets with HT9, a high chromium stainless steel familiar to the nuclear industry. A test bonding matrix was performed to identify bonding conditions and process parameters suitable for the three material systems of interest (HT9/Ta, HT9/W, and HT9/HT9). Temperatures of 900 and 1060 C were investigated along with bonding pressures of 7 and 70 MPa. A nominal soak time of 3 h was used for all tests. Three interlayers were investigated: pure nickel, Ni-6P, and vanadium. Finally, different surface preparation techniques for the tungsten were explored in order to gage their effect on the bond quality. Following joining, the bonds were characterized using an array of microscopy and micromechanical techniques to determine the resulting interface character. The nickel and NiP coatings were found to stabilize austenite at the HT9 surface during bonding, while the vanadium remained generally inert given good solubility in each of the three systems. Intermetallic formation is also a significant concern at elevated bonding temperatures as FeTa, FeW, NiTa, and NiW each rapidly form during interdiffusion. Multiple failures were observed through crack propagation parallel to the interface along the intermetallic phases. Differing contraction rates among the base materials also resulted in brittle fracture within the tungsten during cooling from bonding temperatures. Bonding performed at 900 C under 70 MPa for 3 h with the inclusion of a vanadium interlayer was found to be superior of the conditions explored in this work.

Nelson, A. T.; Hosemann, P.; Maloy, S. A.

2012-12-01

94

Effect of Bonding Temperature on Interfacial Reaction and Mechanical Properties of Diffusion-Bonded Joint Between Ti-6Al-4V and 304 Stainless Steel Using Nickel as an Intermediate Material  

NASA Astrophysics Data System (ADS)

An investigation was carried out on the solid-state diffusion bonding between Ti-6Al-4V (TiA) and 304 stainless steel (SS) using pure nickel (Ni) of 200-?m thickness as an intermediate material prepared in vacuum in the temperature range from 973 K to 1073 K (700 C to 800 C) in steps of 298 K (25 C) using uniaxial compressive pressure of 3 MPa and 60 minutes as bonding time. Scanning electron microscopy images, in backscattered electron mode, had revealed existence of layerwise Ti-Ni-based intermetallics such as either Ni3Ti or both Ni3Ti and NiTi at titanium alloy-nickel (TiA/Ni) interface, whereas nickel-stainless steel (Ni/SS) diffusion zone was free from intermetallic phases for all joints processed. Chemical composition of the reaction layers was determined in atomic percentage by energy dispersive spectroscopy and confirmed by X-ray diffraction study. Room-temperature properties of the bonded joints were characterized using microhardness evaluation and tensile testing. The maximum hardness value of ~800 HV was observed at TiA/Ni interface for the bond processed at 1073 K (800 C). The hardness value at Ni/SS interface for all the bonds was found to be ~330 HV. Maximum tensile strength of ~206 MPa along with ~2.9 pct ductility was obtained for the joint processed at 1023 K (750 C). It was observed from the activation study that the diffusion rate at TiA/Ni interface is lesser than that at the Ni/SS interface. From microhardness profile, fractured surfaces and fracture path, it was demonstrated that failure of the joints was initiated and propagated apparently at the TiA/Ni interface near Ni3Ti intermetallic phase.

Thirunavukarasu, Gopinath; Kundu, Sukumar; Mishra, Brajendra; Chatterjee, Subrata

2013-08-01

95

A new technology for diffusion bonding intermetallic TiAl to steel with composite barrier layers  

SciTech Connect

In this study, intermetallic TiAl and steel are diffusion bonded successfully by using composite barrier layers of titanium/vanadium/copper. The relationship of the bond parameters and tensile strength of the joints is discussed, and the optimum bond parameters were obtained. The reaction products and the interface structures of the joints were investigated by SEM, EPMA, and XRD. In this case, a dual phase Ti{sub 3}Al+TiAl layer and a Ti solid solution, which enhances the strength of the joint, are obtained at the TiAl/Ti interface. A formation mechanism at the interface of TiAl/Ti was proposed. The whole reaction process can be divided into three stages. In the first stage, Ti (Al{sub ss}) layer is formed at the interface TiAl/titanium. In the second stage, the continuous diffusion of Al atoms from TiAl to titanium leads to the formation of Ti{sub 3}Al, a TiAl+Ti{sub 3}Al layer is formed adjacent to TiAl. In the last stage, the thickness of each reaction layer increases with bonding time according to a parabolic law. The interface of TiAl/titanium/vanadium/copper/steel was free from intermetallic compounds and other brittle phases, and the strength of the joint was as high as 420 MPa, very close to that of the TiAl base. This method provides a reliable bonding method of intermetallic TiAl and steel.

He, P.; Feng, J.C.; Zhang, B.G.; Qian, Y.Y

2003-01-15

96

Contributions of atomic diffusion and plastic deformation to the plasma surface activation assisted diffusion bonding of zirconium-based bulk metallic glass  

NASA Astrophysics Data System (ADS)

A mathematical model was established to estimate the contributions of atomic diffusion and plastic deformation to the diffusion bonding of zirconium-based bulk metallic glasses. Additionally, the surface state was introduced into the model since oxide film is the main barrier to atomic bonding across interface. The model calculation displayed that the contribution of plastic deformation to void closure was six orders of magnitude higher than atomic diffusion. The joints with ion etching before bonding were achieved to verify the model. The experimental strength of joints had a sound fit with the theoretical strength calculated by the model.

Chen, H. Y.; Cao, J.; Song, X. G.; Feng, J. C.

2012-05-01

97

Diffusion Bonding Beryllium to Reduced Activation Ferritic Martensitic Steel: Development of Processes and Techniques  

NASA Astrophysics Data System (ADS)

Only a few materials are suitable to act as armor layers against the thermal and particle loads produced by magnetically confined fusion. These candidates include beryllium, tungsten, and carbon fiber composites. The armor layers must be joined to the plasma facing components with high strength bonds that can withstand the thermal stresses resulting from differential thermal expansion. While specific joints have been developed for use in ITER (an experimental reactor in France), including beryllium to CuCrZr as well as tungsten to stainless steel interfaces, joints specific to commercially relevant fusion reactors are not as well established. Commercial first wall components will likely be constructed front Reduced Activation Ferritic Martensitic (RAFM) steel, which will need to be coating with one of the three candidate materials. Of the candidates, beryllium is particularly difficult to bond, because it reacts during bonding with most elements to form brittle intermetallic compounds. This brittleness is unacceptable, as it can lead to interface crack propagation and delamination of the armor layer. I have attempted to overcome the brittle behavior of beryllium bonds by developing a diffusion bonding process of beryllium to RAFM steel that achieves a higher degree of ductility. This process utilized two bonding aids to achieve a robust bond: a. copper interlayer to add ductility to the joint, and a titanium interlayer to prevent beryllium from forming unwanted Be-Cu intermetallics. In addition, I conducted a series of numerical simulations to predict the effect of these bonding aids on the residual stress in the interface. Lastly, I fabricated and characterized beryllium to ferritic steel diffusion bonds using various bonding parameters and bonding aids. Through the above research, I developed a process to diffusion bond beryllium to ferritic steel with a 150 M Pa tensile strength and 168 M Pa shear strength. This strength was achieved using a Hot Isostatic Pressing (HIP) process (at a temperature between 700 C and 750 C for 2 hours at 103 M Pa) with 10 mu m of titanium and 20 mum of copper deposited between substrates. Without the copper and titanium interlayers, the bond formed an intermetallic that lead to fracture from internal residual stresses. Also, slowing the rate of cooling and adding an intermediate hold temperature during cool-down significantly increased bond strength. These beneficial effects were confirmed by the numerical simulations, which showed reduced residual stress resulting from all bonding techniques. Both metals interlayers, as well as the reduced cooling rate were critical in overcoming the otherwise brittle quality of the beryllium to ferritic steel joint. However, the introduced interlayers are not an ideal solution to the problem. They introduced both Be-Ti and Cu-Ti compounds, which proved to be the eventual failure location in the bond. Further optimization of this joint is necessary, and can potentially be achieved with variation of cooling rates. To make the joint ready for implementation will require larger scale fabrication to verify reliability and to test the joint under operational loads.

Hunt, Ryan Matthew

98

Gas Diffusion and Free Volume Behavior of Ethylene Vinyl Alcohol Copolymers: Effect of Hydrogen Bonding Interaction  

NASA Astrophysics Data System (ADS)

The main objective of this work was to develop fundamental understanding of oxygen transport in a broad range of EVOH copolymers as it is related to free volume characteristics and hydrogen bonding interaction. FTIR was used to directly characterize H-bonding network as a function of copolymer composition and temperature. Positron annihilation lifetime spectroscopy (PALS) was used to study free volume behavior. The measure of intermolecular interaction, cohesive energy density, was calculated through group contribution methods and also obtained using molecular dynamics computer simulations. Oxygen transport characteristics of the copolymers, i.e. permeability, diffusivity, and solubility were measured at various temperatures, and the apparent activation energy parameters calculated.

Brandt, Justin; Nazarenko, Sergei; Olson, Brian; Jamieson, Alexander

2009-03-01

99

Si-based multilayered print circuit board for MEMS packaging fabricated by Si deep etching, bonding, and vacuum metal casting  

NASA Astrophysics Data System (ADS)

In our previous works, metal injection technique into small diameter (10 -100micrometers ) through holes was developed and applied for fabrication of Si based print circuit board. In the present work, we present the metal filling technology by vacuum casting into 3 dimensional through holes and trenches structure fabricated in stacked layered Si wafers prepared by fusion bonding of ICP etched Si wafers. Metal electrical feed through was successfully prepared by the method. Conventional print circuit boards have been fabricated with Epoxy resin based materials. In recent years Si is regarded as a candidate for next generation materials for print circuit board substrates, as the substrate whose thermal elongation same as the mounted chips is an ideal solution to residual stress problems in the elevated temperature application. In this report, we developed the double sided mountable stacked circuit board using Si deep etching technology and fusion bonding. This technology is expected to lead to the realization of the assembling of sensors, actuators and ICs, i.e. 3 dimensional MEMS packaging. In this report, we adopted micromachining technology to this application area and the special emphasis is placed on the low cost and reliable process development. The detailed items to be developed are shown as follows; 1) Development of Si wafer through holes penetration and trench formation by ICP etching. 2) Alignment and bonding of micromachined wafers. 3) Development of insulating layer with oxidation. 4) Development of formation of electrical feed through for stacked layers.

Murakoshi, Yoichi; Hanada, Kotaro; Li, Yaomin; Uchino, Kazuyoshi; Suzuki, Takaaki; Maeda, Ryutaro

2001-11-01

100

Low temperature diffusion bonding of Pd-based composite membranes with metallic module for hydrogen separation  

Microsoft Academic Search

A diffusion-bonding procedure at a low temperature, i.e. 500C, based on the high mobility of silver atoms was developed with a newly designed plate-and-frame type hydrogen purification membrane module consisting of a unit cell and a housing. Two membranes made of palladium and copper sputtered on polished porous nickel supports (PNS) followed by Cu-reflow at 750C, respectively, were assembled in

Shin-Kun Ryi; Jong-Soo Park; Sung-Hyun Kim; Dong-Won Kim; Hyun-Keun Kim

2009-01-01

101

Indirect Versus Direct Heating of Sheet Materials: Superplastic Forming and Diffusion Bonding Using Lasers  

Microsoft Academic Search

Many from within manufacturing industry consider superplastic forming (SPF) to be high tech, but it is often criticized\\u000a as too complicated, expensive, slow and, in general, an unstable process when compared to other methods of manipulating sheet\\u000a materials. Perhaps, the fundamental cause of this negative perception of SPF, and also of diffusion bonding (DB), is the fact\\u000a that the current

Alan Jocelyn; Aravinda Kar; Alexander Fanourakis; Terence Flower; Mike Ackerman; Allen Keevil

2010-01-01

102

Diffusion Bonding of 17-4 Precipitation Hardening Stainless Steel to Ti Alloy With and Without Ni Alloy Interlayer: Interface Microstructure and Mechanical Properties  

NASA Astrophysics Data System (ADS)

In the present study, the diffusion bonding of 17-4 precipitation hardening stainless steel to Ti alloy with and without nickel alloy as intermediate material was carried out in the temperature range of 1073 K to 1223 K (800 C to 950 C) in steps of 298 K (25 C) for 60 minutes in vacuum. The effects of bonding temperature on interfaces microstructures of bonded joint were analyzed by light optical and scanning electron microscopy. In the case of directly bonded stainless steel and titanium alloy, the layerwise ?-Fe + ?, ?, FeTi + ?, FeTi + ?-Ti phase, and phase mixture were observed at the bond interface. However, when nickel alloy was used as an interlayer, the interfaces indicate that Ni3Ti, NiTi, and NiTi2 are formed at the nickel alloy-titanium alloy interface and the PHSS-nickel alloy interface is free from intermetallics up to 1148 K (875 C) and above this temperature, intermetallics were formed. The irregular-shaped particles of Fe5Cr35Ni40Ti15 have been observed within the Ni3Ti intermetallic layer. The joint tensile and shear strength were measured; a maximum tensile strength of ~477 MPa and shear strength of ~356.9 MPa along with ~4.2 pct elongation were obtained for the direct bonded joint when processed at 1173 K (900 C). However, when nickel base alloy was used as an interlayer in the same materials at the bonding temperature of 1148 K (875 C), the bond tensile and shear strengths increase to ~523.6 and ~389.6 MPa, respectively, along with 6.2 pct elongation.

Kundu, S.; Anand, G.; Chatterjee, S.

2013-05-01

103

Measurements of the behaviour of neutral atom density in a diffuse vacuum arc by laser-induced fluorescence (LIF)  

Microsoft Academic Search

The method of laser-induced fluorescence was used to study the behavior of the absolute neutral vapor density of a diffuse vacuum arc on FeCu contacts. The local and temporal resolutions were 1 mm3 and 10 ?s, respectively. The arc current had a sinusoidal shape of 5.8-ms duration with peak values of 90 and 510 A. It was found that the

ERHARD HAYESS; BURKHARD JUTTNER; GERD LIEDER; WERNER NEUMANN; HEINZ PURSCH; LEONHARD WEIXELBAUM

1989-01-01

104

Model of a diffuse column vacuum arc with cathode jets burning in parallel with a high-current plasma column  

Microsoft Academic Search

The behavior of the high-current diffuse columnar arc in vacuum is considered. A single cathode spot jet appearing to the side of a high-current plasma column is studied using a two-dimensional magnetohydrodynamic model. The plasma expansion and current flow in the jet are affected by the presence of the main column and the applied axial magnetic field (AMF). Increasing the

Michael Keidar; Michael Bruce Schulman; Erik D. Taylor

2004-01-01

105

Reaction diffusion behaviors for interface between Ni-based super alloys and vacuum plasma sprayed MCrAlY coatings  

Microsoft Academic Search

The object of this study is overlay coatings of MCrAlY alloy sprayed by a vacuum plasma spray (VPS) process for the protection against high-temperature corrosion and oxidation in the field of gas turbine components. Reaction diffusion behaviors at the interface between the MCrAlY coatings and the substrate, which have an important effect on coating degradation, have not always been clarified.

Y. Itoh; M. Tamura

1999-01-01

106

Diffusion bonding of commercially pure titanium to low carbon steel using a silver interlayer  

SciTech Connect

Titanium and low carbon steel plates were joined through diffusion bonding using a silver interlayer at various temperatures for various diffusion times. In order to determine the strength of the resulting joints, tensile-shear tests and hardness tests were applied. Additionally, optical, scanning electron microscopy examinations and energy dispersive spectrometry elemental analyses were carried out to determine the interface properties of the joint. The work showed that the highest interface strength was obtained for the specimens joined at 850 deg. C for 90 min. It was seen from the hardness results that the highest hardness value was obtained for the interlayer material and the hardness values on the both sides of the interlayer decreased gradually as the distance from the joint increased. In energy dispersive spectrometry analyses, it was seen that the amount of silver in the interlayer decreased markedly depending on the temperature rise. In addition, increasing diffusion time also caused some slight decrease in the amount of silver.

Atasoy, Evren [Tokat Adocim Cement Factory, 60100, Tokat (Turkey); Kahraman, Nizamettin [Karabuk University, Technical Education Faculty, 78050, Karabuk (Turkey)], E-mail: nizamettinkahraman@gmail.com

2008-10-15

107

Diffusion ordered spectroscopy for resolution of double bonded cis, trans-isomers  

NASA Astrophysics Data System (ADS)

NMR spectroscopic separation of double bonded cis- and trans-isomers, that have different molecular shapes but identical mass have been carried out using Diffusion Ordered Spectroscopy (DOSY). The mixtures of fumaric acid and maleic acid, that have similar hydrodynamic radii, have resolved been 'on the basis of their diffusion coefficients arising due to their different tendencies to associate with micelles or reverse micelles. Sodium dodecyl sulfate (SDS) and Dioctyl sulfosuccinate sodium salt (AOT) have been used as the media to mimic the chromatographic conditions, modify the average mobility and to achieve differential diffusion rates. The best separation of the components has been achieved by Dioctyl sulfosuccinate sodium salt (AOT) in D2O solution.

Chaudhari, Sachin Rama; Suryaprakash, N.

2012-06-01

108

Characterisation of GFRP surfaces amenable for bonding and their effect on the strength of co-cured vacuum resin infused single lap joints  

Microsoft Academic Search

The choice of a fabrication method is of primary importance in order to optimise and control the performance of composite materials. This becomes increasingly crucial when the fabrication method itself becomes in parallel an adhesive bonding co-cure technique. In this paper, the manufacturing process of the vacuum resin infusion jointing is introduced and specimens of co-cured single lap joints are

D. Tzetzis

2012-01-01

109

Diffusion bonding of Al7075 alloy to titanium aluminum vanadate alloy  

NASA Astrophysics Data System (ADS)

The aluminum alloy (Al7075) and titanium alloy (Ti-6Al-4V) are used in a variety of applications in the aerospace industry. However, the high cost of Ti-6Al-4V alloy has been a major factor which has limited its use and therefore, the ability to join Al7075 alloy to Ti-6Al-4V alloy can provide a product that is less costly, but retains the high strength and light weight properties necessary for the transport industry. However, the large difference in the physical properties between these two alloys prevents the use of conventional joining techniques such as fusion welding to join these dissimilar alloys. Therefore, the diffusion bonding technique was used to join Al7075 alloy to Ti-6Al-4V alloy with the objective of minimizing microstructural changes of the two alloys during the bonding process. In this thesis, solid state and liquid phase bonding processes were undertaken. Solid state bonding was employed without interlayers and was successful at 510C and 7 MPa. The bond interface showed an absence of the oxides due to the dissolution of oxygen into the titanium solution. Bonds made using copper interlayers at a temperature sufficient enough to form eutectic liquid formation between copper and aluminum were produced. The intermetallics theta(Al2Cu), S(Al2CuMg) and T(Al2Mg3Zn3) were identified at the aluminum interface while Cu3Ti2 intermetallic was identified at the titanium interface. Bonds made using tin based alloys interlayers and copper coatings were successful and gave the highest shear strength. The eutectic formation on the Al7075 alloy was responsible for joint formation at the aluminum interface while the formation of Sn3Ti5 intermetallic was responsible for the joint formation at titanium interface. The corrosion rate of the bonds decreased with increasing bonding time for joints made using the tin based interlayer in 3% NaCl solution. However, the presence of copper within the joint increased the corrosion rate of the bonds and this was attributed to the corrosive effect of copper in the Al7075 alloy.

Alhazaa, Abdulaziz Nasser

110

Molecular Dynamics Study of the Disruption of H-BONDS by Water Molecules and its Diffusion Behavior in Amorphous Cellulose  

NASA Astrophysics Data System (ADS)

Hydrolysis is an important component of the aging of cellulose, and it severely affects the insulating performance of cellulosic materials. The diffusion behavior of water molecules in amorphous cellulose and their destructive effect on the hydrogen bonding structure of cellulose were investigated by molecular dynamics. The change in the hydrogen bonding structure indicates that water molecules have a considerable effect on the hydrogen bonding structure within cellulose: both intermolecular and intramolecular hydrogen bonds decreased with an increase in ingressive water molecules. Moreover, the stabilities of the cellulose molecules were disrupted when the number of intermolecular hydrogen bonds declined to a certain degree. Both the free volumes of amorphous cells and water molecule-cellulose interaction affect the diffusion of water molecules. The latter, especially the hydrogen bonding interaction between water molecules and cellulose, plays a predominant role in the diffusion behavior of water molecules in the models of which the free volume rarely varies. The diffusion coefficient of water molecules has an excellent correlation with water molecule-cellulose interaction and the average hydrogen bonds between each water molecule and cellulose; however, this relationship was not apparent between the diffusion coefficient and free volume.

Liao, Ruijin; Zhu, Mengzhao; Zhou, Xin; Zhang, Fuzhou; Yan, Jiaming; Zhu, Wenbin; Gu, Chao

2012-06-01

111

Thermal expansion behavior and performance of VLP diffusion-bonded joints of SiC p\\/A356 composites  

Microsoft Academic Search

Effects of the bonding thermal cycle and heat treatment on thermal expansion behaviors and mechanical performance of SiCp\\/A356 composites and their joints were investigated. Joints were made by using the vibration liquid phase (VLP) diffusion bonding process, and treated by the solution and aging. It has been found that the CTE of the base metal is not significantly influenced by

Zhiwu Xu; Jiuchun Yan; Weiwei Zhao; Huibin Xu; Shiqin Yang

2005-01-01

112

Advanced diffuser technology helps reduce vent-up times while maintaining wafer integrity on vacuum tools loadlock chambers  

NASA Astrophysics Data System (ADS)

Wafer throughput and particle counts are key metrics for any semiconductor manufacturer's yield enhancement programs. Recent advancements in diffuser technology have helped manufacturers enhance these metrics while improving the attributes for most vacuum processes. These processes include dry etch, chemical vapor deposition (CVD), physical vapor deposition (PVD), rapid thermal processing (RTP) and Epitaxial deposition (Epi). Execution of membrane diffuser technology dramatically decreases required vent time and has become a highly effective tool upgrade option. An early implementation of this technology was used on 200mm batch-style loadlocks that had an inherently large internal volume. The loadlock was prone to long vent cycles to prevent particle contamination. As the industry transitioned to a 300mm wafer platform, factories increased their development of single-wafer loadlocks (SWLL) in an effort to boost tool throughput. Gas diffusers with ultra fine filtration membranes solved these issues. Compared to the 200mm batch-style loadlocks, the SWLLs had extremely low internal volumes and were designed to cycle vacuum to atmosphere very quickly. With the low volumes inherent in the SWLL, the velocity of the incoming vent gas became critical, since any particles on the bottom of the loadlock chamber would easily sweep onto the wafer should they be hit with a high velocity gas. Particles are typically present in the loadlock due to mechanical wafer handling devices and environmental exposure. Gas diffusers allowed a large, uniform volumetric flowrate of gas into the loadlock chamber at low downstream gas velocities. While now standard on most 300mm loadlocks, the majority of 200mm tools in the field do not utilize membrane diffusers. Typically a screen, frit and/or soft vent procedure is used to control the flow into the loadlock. However, these tools can now be retrofitted with membrane diffuser technology. The result is a large reduction in particle count while maintaining throughput levels at a low cost with minimal downtime.

Vroman, Chris; Quartaro, Chris; Randolph, Marshall

2008-04-01

113

Diffusion Bonding of Ti-6Al-4V Sheet with Ti-6Al-4V Foam for Biomedical Implant Applications  

NASA Astrophysics Data System (ADS)

Advanced metallic bone implants are designed to have a porous surface to improve osseointegration and reduce risks of loosening. An alternative approach to existing surface treatments to create a porous surface is to bond separately produced metallic foams onto the implant. To assess the feasibility of this approach, a Ti-6Al-4V foam was diffusion bonded onto bulk Ti-6Al-4V in an argon atmosphere at temperatures between 1173 K and 1223 K (900 C and 950 C) for times between 45 and 75 minutes. These specimens were tested in tension to determine bond quality: failures occurred in the foam, indicating a strong diffusion-bonded interface. The quality of the bond was confirmed by metallographic studies, indicating that this approach, which can also be applied to creating of sandwich with porous cores, is successful.

Hamilton, Brittany; Oppenheimer, Scott; Dunand, David C.; Lewis, Daniel

2013-10-01

114

Diffusion Bonding Technology of Tungsten and SiC/SiC Composites for Nuclear Applications  

NASA Astrophysics Data System (ADS)

Silicon carbide (SiC) is a candidate for the structural material in the next generation nuclear plants. Use of SiC/SiC composites is expected to increase the operation temperature of system over 1000 C. For the high temperature system, refractory metals are planned to be used for several components. Tungsten is a candidate of armor on the divertor component in fusion, and is planned to be used for an upper-end plug of SiC/SiC fuel pin in a Gas cooled Fast Reactor (GFR). Joining technique of the SiC/SiC composites and tungsten is an important issue for nuclear systems in future. Nano-Infiltration and Transient Eutectoid (NITE) method is able to provide dense stable and high strength SiC/SiC composites having high resistance against pressure at elevated temperature, a diffusion bonding technique is usable to join the materials. Present research produces a NITE-SiC/SiC composite and tungsten as the similar dimension as a projected cladding tube of fuel pin for GFR using diffusion bonding, and investigated microstructure and mechanical properties.

Kishimoto, Hirotatsu; Shibayama, Tamaki; Abe, Takahiro; Shimoda, Kazuya; Kawamura, Satoshi; Kohyama, Akira

2011-10-01

115

Nonproportionality in Bayard-Alpert Ionization Gauge and the Ultimate Vacuum Determination of Diffusion Pumps  

Microsoft Academic Search

The nonproportionality between the ion current and the electron current in a Bayard-Alpert ionization gauge is systematically examined and theoretically treated. The effective pumping speed is so modified as to include the effect of back diffusion of oil vapor from the diffusion pump and the contribution of ionization pumping. The theory is experimentally verified in some respects to deduce a

Y. Mizushima; Z. Oda

1959-01-01

116

Low-distortion, high-strength bonding of thermoplastic microfluidic devices employing case-II diffusion-mediated permeant activation.  

PubMed

We demonstrate a new method for joining thermoplastic surfaces to produce microfluidic devices. The method takes advantage of the sharply defined permeation boundary of case-II diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. The technique is capable of producing bonds that exhibit cohesive failure, while preserving the fidelity of fine features in the bonding interface. This approach is uniquely suited to production of layered microfluidic structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometre length scales. Distortions in microfluidic device channels are limited to the size scale of the permeant-swollen layer; 6 microm deep channels are routinely produced with no detectable cross-sectional distortions. Conventional thermal diffusion bonding of identical parts yields less strongly bonded microfluidic structures with increasingly severe dimensional compressions as bonding temperatures approach the thermoplastic glass-transition temperature: a preliminary rheological analysis is consistent with the observed compressions. The bond-enhancing procedure is easily integrated in standard process flows, uses inexpensive reagents, and requires no specialized equipment. PMID:18030407

Wallow, Thomas I; Morales, Alfredo M; Simmons, Blake A; Hunter, Marion C; Krafcik, Karen Lee; Domeier, Linda A; Sickafoose, Shane M; Patel, Kamlesh D; Gardea, Andy

2007-09-19

117

Contact temperature and erosion in high-current diffuse vacuum arcs on axial magnetic field contacts  

Microsoft Academic Search

We have investigated the surface heating effects of drawn vacuum arcs for several industrial designs of axial magnetic field (AMF) contacts, using near infrared (IR) photography of the Cu-Cr arcing surfaces with an image-intensified charge-coupled device (CCD) camera and an IR pyrometer. This enables detailed contact temperature mapping immediately after a half-cycle of arc current. The very homogeneous temperature distribution

H. Schellekens; M. B. Schulman

2001-01-01

118

Strength and fracture behaviour of diffusion bonded joints in Al-Li (8090) alloy. III - Peel strength  

NASA Astrophysics Data System (ADS)

Peel strengths at room temperature and under superplastic forming conditions at 530 C were measured for diffusion-bonded joints in Al-Li 8090 alloy sheet. The bonds were made in the solid state, or via a transient liquid phase using interlayers. The effect of strain rate, sheet thickness and heat treatment were investigated. The significance of these results for the testing of DB joints and for their use in DB/SPF structures is discussed.

Dunford, D. V.; Partridge, P. G.

1992-11-01

119

Diffusion bonding of a CuCrZr alloy to stainless steel and tungsten using nickel as an interlayer  

Microsoft Academic Search

In the present work, diffusion bonding of Cu-1wt.% Cr-0.1wt.% Zr alloy to tungsten as well as to stainless steel 316 (SS) has been attempted using nickel as an interlayer. This could be achieved in a single step and the bonds were found to be metallurgically sound with the strength exceeding that of the sintered tungsten used in this work.

I. S. Batra; G. B. Kale; T. K. Saha; A. K. Ray; J. Derose; J. Krishnan

2004-01-01

120

Theoretical study on the diffusive transport of 2,4,6-trinitrotoluene in polymer-bonded explosive  

Microsoft Academic Search

Molecular dynamics (MD) simulations were performed to study the migration of 2,4,6-trinitrotoluene (TNT) in the fluorine rubber\\u000a binder of polymer-bonded explosives (PBX) over a wide range of temperatures. The diffusion coefficient (D) of TNT is determined via microcanonical (NVE) MD simulation using the COMPASS force field. The calculated diffusion coefficient\\u000a (D) was then used to compute the migration time of

Yang Zhou; XinPing Long; XingWen Wei

121

The effect of the nature of H-bonding groups on diffusion through PDMS membranes saturated with octanol and toluene.  

PubMed

The permeation of a series of structurally related compounds across silicone membranes (PDMS) was studied. The PDMS was saturated either with toluene, to mimic a functionally inert barrier, or octanol, to mimic the polar/hydrogen bonding environment of the stratum corneum lipid barrier. Phenol, salicylic acid, benzoic acid, anisole, phenylethanol and benzyl alcohol were chosen in an attempt to relate permeation to their different H-bonding capabilities. The flux was lower through the octanol system suggesting retardation by polar/H-bonding interactions. Separation of the permeability coefficient into its thermodynamic (partition coefficient) and kinetic (diffusion coefficient) terms suggests that the effect of altering polarity within the membrane has a greater impact on the diffusion of permeant rather than its chemical potential within the membrane. PMID:11803132

Du Plessis, Jeanetta; Pugh, W John; Judefeind, Anja; Hadgraft, Jonathan

2002-02-01

122

The Structure and Properties of Diffusion Assisted Bonded Joints in 17-4 Ph, Type 347, 15-5 Ph and Nitronic 40 Stainless Steels.  

National Technical Information Service (NTIS)

Diffusion assisted bonds are formed in 17-4 PH, 15-5 PH, type 347 and Nitronic 40 stainless steels using electrodeposited copper as the bonding agent. The bonds are analyzed by conventional metallographic, electron microprobe analysis, and scanning electr...

D. A. Wigley

1981-01-01

123

Levitation effect: role of symmetry and dependence of diffusivity on the bond length of homonuclear and heteronuclear diatomic species.  

PubMed

Molecular dynamics investigation of model diatomic species confined to the ?-cages of zeolite NaY is reported. The dependence of self-diffusivity on the bond length of the diatomic species has been investigated. Three different sets of runs have been carried out. In the first set, the two atoms of the diatomic molecule interact with the zeolite atoms with equal strength (example, O(2), the symmetric case). In the second and third sets which correspond to asymmetric cases, the two atoms of the diatomic molecule interact with unequal strengths (example, CO). The result for the symmetric case exhibits a well-defined maximum in self-diffusivity for an intermediate bond length. In contrast to this, the intermediate asymmetry leads to a less pronounced maximum. For the large asymmetric case, the maximum is completely absent. These findings are analyzed by computing a number of related properties. These results provide a direct confirmation at the microscopic level of the suggestion by Derouane that the supermobility observed experimentally by Kemball has its origin in the mutual cancellation of forces. The maximum in diffusivity from molecular dynamics is seen at the value predicted by the levitation effect. Further, these findings suggest a role for symmetry in the existence of a diffusivity maximum as a function of diameter of the diffusant often referred to as the levitation effect. The nature of the required symmetry for the existence of anomalous diffusivity is interaction symmetry which is different from that normally encountered in crystallography. PMID:21401037

Sharma, Manju; Yashonath, S

2011-03-14

124

Evaluation of Cu as an interlayer in Be/F82H diffusion bonds for ITER TBM  

NASA Astrophysics Data System (ADS)

Copper has been investigated as a potential interlayer material for diffusion bonds between beryllium and Reduced Activation Ferritic/Martensitic (RAFM) steel. Utilizing Hot Isostatic Pressing (HIP), copper was directly bonded to a RAFM steel, F82H, at 650 C, 700 C, 750 C, 800 C and 850 C, under 103 MPa for 2 h. Interdiffusion across the bonded interface was limited to 1 ?m or less, even at the highest HIP'ing temperature. Through mechanical testing it was found that samples HIP'ed at 750 C and above remain bonded up to 211 MPa under tensile loading, at which point ductile failure occurred in the bulk copper. As titanium will be used as a barrier layer to prevent the formation of brittle Be/Cu intermetallics, additional annealing studies were performed on copper samples coated with a titanium thin film to study Ti/Cu interdiffusion characteristics. Samples were heated to temperatures between 650 C and 850 C for 2 h in order to mimic the range of likely HIP temperatures. A correlation was drawn between HIP temperature and diffusion depth for use in determining the minimum Ti film thickness necessary to block diffusion in the Be/F82H joint.

Hunt, R. M.; Goods, S. H.; Ying, A.; Dorn, C. K.; Abdou, M.

2011-10-01

125

16-microm infrared generation by difference-frequency mixing in diffusion-bonded-stacked GaAs.  

PubMed

Tunable 90-ps 15.6-17.6-microm coherent radiation was generated by means of difference-frequency mixing in diffusion-bonded-stacked GaAs. The sample consisted of 24 alternately rotated layers with a total length of 6 mm and with low optical loss to achieve third-order quasi-phase matching. The wavelength-tuning curve was close to the theoretical prediction, demonstrating that the bonding process maintained nonlinear optical phase matching over the entire interaction length. Maximum conversion efficiency of 0.7%, or 5% internal quantum efficiency, was measured at 16.6 microm, consistent with the theoretical predictions. PMID:18087412

Zheng, D; Gordon, L A; Wu, Y S; Feigelson, R S; Fejer, M M; Byer, R L; Vodopyanov, K L

1998-07-01

126

On the testing of diffusion-bonded overlap joints between clad Al-Zn-Mg alloy(7010) sheet  

Microsoft Academic Search

The shear strengths of diffusion-bonded overlap joints between silver-coated clad 7010 Al-alloy sheets of thicknesst = 3.2 mm have been determined for various overlap lengths (L) end out-of-plane bending constraints. The measured shear strength decreased with increase inL due to increased bending and peel stresses associated with the asymmetry of the loading path. For overlaps greater than about 1.25 to

P. G. Partridge; D. V. Dunford

1987-01-01

127

Diffusion Bonding of Tungsten to Reduced Activation Ferritic\\/Martensitic Steel F82H Using a Titanium Interlayer  

Microsoft Academic Search

\\u000a Development of materials and related fabrication process is one of the most important technologies for fusion energy development.\\u000a In fusion reactor, joining of tungsten (W) to reduced activation ferritic\\/martensitic steel is required. In this work, diffusion\\u000a bonding between W and ferritic\\/martensitic steel F82H using a Ti interlayer was investigated. The results indicated that all\\u000a the joints were successfully obtained. The

Zhihong Zhong; Tatsuya Hinoki; Akira Kohyama

128

High energy X-ray diffraction analysis of strain and residual stress in silicon nitride ceramic diffusion bonds  

Microsoft Academic Search

High resolution X-ray scanning diffractometry is used to study the residual stress in binary metal\\/ceramic (Ni\\/Si3N4) diffusion bonds fabricated by simultaneous high temperature heating and uniaxial pressing. In order to diminish the experimental error on the stress determination, the method consists of three steps: (i) to measure the axial and radial strains following some selected lines at the inner volume

M. Vila; C. Prieto; P. Miranzo; M. I. Osendi; A. E. Terry; G. B. M. Vaughan

2005-01-01

129

Thermal fatigue testing of a diffusion-bonded beryllium divertor mock-up under ITER relevant conditions  

SciTech Connect

Thermal response and thermal fatigue tests of four 5 mm thick beryllium tiles on a Russian divertor mock-up were completed on the Electron Beam Test System at Sandia National Laboratories. The beryllium tiles were diffusion bonded onto an OFHC copper saddleblock and a DSCu (MAGT) tube containing a porous coating. Thermal response tests were performed on the tiles to an absorbed heat flux of 5 MW/m{sup 2} and surface temperatures near 300{degrees}C using 1.4 MPa water at 5.0 m/s flow velocity and an inlet temperature of 8-15{degrees}C. One tile was exposed to incrementally increasing heat fluxes up to 9.5 MW/m{sup 2} and surface temperatures up to 690{degrees}C before debonding at 10 MW/m{sup 2}. A third tile debonded after 9200 thermal fatigue cycles at 5 MW/m{sup 2}, while another debonded after 6800 cycles. In all cases, fatigue failure occurred in the intermetallic layers between the beryllium and copper. No fatigue cracking of the bulk beryllium was observed. During thermal cycling, a gradual loss of porous coating produced increasing sample temperatures. These experiments indicate that diffusion-bonded beryllium tiles can survive several thousand thermal cycles under ITER relevant conditions without failure. However, the reliability of the diffusion bonded Joint remains a serious issue.

Youchison, D.L. [Pennsylvania State Univ., University Park, PA (United States); Guiniiatouline, R. [D.V. Efremov Scientific Research Institute of Electrophysical Apparatus, St. Petersburg (Russian Federation); Watson, R.D. [Sandia National Labs., Albuquerque, NM (United States)] [and others

1994-12-31

130

Theoretical study on the diffusive transport of 2,4,6-trinitrotoluene in polymer-bonded explosive.  

PubMed

Molecular dynamics (MD) simulations were performed to study the migration of 2,4,6-trinitrotoluene (TNT) in the fluorine rubber binder of polymer-bonded explosives (PBX) over a wide range of temperatures. The diffusion coefficient (D) of TNT is determined via microcanonical (NVE) MD simulation using the COMPASS force field. The calculated diffusion coefficient (D) was then used to compute the migration time of TNT based on Fick's second law and the results agree well with the experimental data. The relation between D of TNT and temperature was confirmed and the results confirm the temperature-dependence of diffusion coefficients of TNT in the binder, but a break is seen about the melt point (the temperature at which the elastomeric state of the binder changes to a viscosity state) in the Arrhenius plot of ln(D) versus 1/T. PMID:21360179

Zhou, Yang; Long, Xinping; Wei, Xingwen

2011-03-01

131

Preparation and Bond Properties of Thermal Barrier Coatings on Mg Alloy with Sprayed Al or Diffused Mg-Al Intermetallic Interlayer  

NASA Astrophysics Data System (ADS)

Sprayed Al or diffused Mg-Al layer was designed as interlayer between the thermal barrier coatings (TBCs) and Mg alloy substrate. The effects of the interlayer on the bond properties of the coats were investigated. Al layers were prepared by arc spraying and atmospheric plasma spraying (APS), respectively. Mg-Al diffused layer was obtained after the heat treatment of the sprayed sample (Mg alloy with APS Al coat) at 400 C. The results show that sprayed Al interlayer does not improve the bond stability of TBCs. The failure of the TBCs on Mg alloy with Al interlayer occurs mainly due to the low strength of Al layer. Mg-Al diffused layer improves corrosion resistance of substrate and the bond interface. The TBCs on Mg alloy with Mg-Al diffused interlayer shows better bond stability than the sample of which the TBCs is directly sprayed on Mg alloy substrate by APS.

Fan, Xizhi; Wang, Ying; Zou, Binglin; Gu, Lijian; Huang, Wenzhi; Cao, Xueqiang

2013-09-01

132

Formation of dendritic structure in the diffusion zone of the bonded Zircaloy4 and stainless steel 316L in the presence of Ti interlayer  

Microsoft Academic Search

Microstructure of the diffusion bonded samples of stainless steel 316L and Zircaloy-4 in the presence of Ti interlayer at 1000C and 1050C is investigated by scanning electron microscopy (SEM) and the phases in the diffusion zone (DZ) have been analyzed by energy dispersive system (EDS) attached with SEM. Five distinct regions have been observed in the sample bonded at 1000C

J. I. Akhter; M. Ahmad; M. Iqbal; M. Akhtar; M. A. Shaikh

2005-01-01

133

Study of diffusion bond development in 6061 aluminum and its relationship to future high density fuels fabrication.  

SciTech Connect

Powder metallurgy dispersions of uranium alloys and silicides in an aluminum matrix have been developed by the RERTR program as a new generation of proliferation-resistant fuels. Testing is done with miniplate-type fuel plates to simulate standard fuel with cladding and matrix in plate-type configurations. In order to seal the dispersion fuel plates, a diffusion bond must exist between the aluminum coverplates surrounding the fuel meat. Four different variations in the standard method for roll-bonding 6061 aluminum were studied. They included mechanical cleaning, addition of a getter material, modifications to the standard chemical etching, and welding methods. Aluminum test pieces were subjected to a bend test after each rolling pass. Results, based on 400 samples, indicate that at least a 70% reduction in thickness is required to produce a diffusion bond using the standard rollbonding method versus a 60% reduction using the Type II method in which the assembly was welded 100% and contained open 9mm holes at frame corners.

Prokofiev, I.; Wiencek, T.; McGann, D.

1997-10-07

134

Microstructure of Reaction Zone Formed During Diffusion Bonding of TiAl with Ni/Al Multilayer  

NASA Astrophysics Data System (ADS)

In this article, the characterization of the interfacial structure of diffusion bonding a TiAl alloy is presented. The joining surfaces were modified by Ni/Al reactive multilayer deposition as an alternative approach to conventional diffusion bonding. TiAl substrates were coated with alternated Ni and Al nanolayers. The nanolayers were deposited by dc magnetron sputtering with 14 nm of period (bilayer thickness). Joining experiments were performed at 900 C for 30 and 60 min with a pressure of 5 MPa. Cross sections of the joints were prepared for characterization of their interfaces by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), high resolution TEM (HRTEM), energy dispersive x-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Several intermetallic compounds form at the interface, assuring the bonding of the TiAl. The interface can be divided into three distinct zones: zone 1 exhibits elongated nanograins, very small equiaxed grains are observed in zone 2, while zone 3 has larger equiaxed grains. EBSD analysis reveals that zone 1 corresponds to the intermetallic Al2NiTi and AlNiTi, and zones 2 and 3 to NiAl.

Simes, Snia; Viana, Filomena; Koak, Mustafa; Ramos, A. Sofia; Vieira, M. Teresa; Vieira, Manuel F.

2012-05-01

135

Tensile and creep properties of diffusion bonded titanium alloy IMI 834 to gamma titanium aluminide IHI alloy 01A  

SciTech Connect

Diffusion bonding of the Ti-alloy Ti-5.8Al-4.0Sn-3.5Zr-0.7Nb-0.5Mo-0.35Se-0.06C (wt%) to the intermetallic {gamma}-based alloy Ti-33Al-2Fe-1.8V-0.1B (wt%) using hot isostatic pressing at 900 C, 200 MPa held for 1 h was studied. Sound joints without any pores or cracks with a width of approximately 5--7 {micro}m could be produced. Tensile testing showed that the strengths of the joints are similar to the strength of the {gamma}-TiAl base material at temperatures between room temperature and 600 C. The fracture occurs either at the joint or in the {gamma}-TiAl material. The fracture initiation process is a competition between initiation in the {gamma}-TiAl base material and initiation at the {gamma}-TiAl/diffusion bond interface. Creep testing showed that most of the creep elongation occurs in the Ti-alloy, but failure is initiated in the joint bond line. Creep causes degradation and pore formation in this line. Interlinkage of these pores creates a crack which grows slowly until the fracture toughness of the {gamma}-TiAl is exceeded and the crack starts to propagate in the {gamma}-TiAl material and terminates creep life.

Holmquist, M.; Recina, V.; Pettersson, B. [Volvo Aero Corp., Trollhaettan (Sweden)

1999-04-23

136

Physical and theoretical aspects of a new vacuum arc control technology-self arc diffusion by electrode: SADE  

Microsoft Academic Search

Our new vacuum arc control technology: SADE doubles the high current interruption capability of our conventional AMF technology. First, we describe the vacuum arc motion behavior recorded by a high speed CCD video camera. This arc behavior is closely related to axial magnetic field intensity. In particular, it depends on the profile of the externally generated axial magnetic field. The

M. Homma; H. Somei; Y. Niwa; K. Yokokura; I. Ohshima

1998-01-01

137

Physical and theoretical aspects of a new vacuum arc control technology-self arc diffusion by electrode: SADE  

Microsoft Academic Search

Our new vacuum arc control technology SADE doubles the high current interruption capability of our conventional axial magnetic field technology. First, we describe the vacuum arc motion behavior recorded by a high speed charge-coupled device video camera. This arc behavior is closely related to axial magnetic field intensity. In particular, it depends on the profile of the externally generated axial

Mitsutaka Homma; H. Somei; Y. Niwa; K. Yokokura; I. Ohshima

1999-01-01

138

Transition to the diffuse mode for high-current drawn arcs in vacuum with an axial magnetic field  

Microsoft Academic Search

The opening of electrical contacts while passing current generates a drawn arc. In vacuum, the arc begins as a bridge of molten metal connecting the contacts, which then ruptures to form a bridge column arc. Previous work observing the development of drawn arcs in vacuum with an imposed axial magnetic field (AMF) measured the time required for the bridge column

Erik D. Taylor; Paul G. Slade; Michael Bruce Schulman

2003-01-01

139

A comparative study of high velocity oxygen fuel, vacuum plasma spray, and axial plasma spray for the deposition of CoNiCrAlY bond coat alloy  

NASA Astrophysics Data System (ADS)

In the aerospace field as well as in the stationary gas turbine field, thermally sprayed coatings are used to improve the surface properties of nickel-super-alloys materials. Coatings are commonly used as bond coat and antioxidation materials (mainly MCrAlY alloys) and as thermal barrier coatings (mainly yttria partially stabilized zirconia). The purpose of the current study was to assess the properties of thermally sprayed bond coat CoNiCrAlY alloys comparing the performance of three different techniques: vacuum plasma spray (VPS), high velocity oxygen fuel (HVOF), and axial plasma spray (AxPS). The quality of the deposited films has been assessed and compared from the point of view of microstructural (porosity, oxide concentration, unmelted particles presence) and mechanical (hardness) characteristics. The surface composition and morphology of the coatings were also determined. Specific efficiency tests were performed for the three examined technologies. The highest quality coatings are obtained by VPS, but also high velocity oxygen fuel and AxPS sprayed films have interesting properties, which can make their use interesting for some applications.

Scrivani, A.; Bardi, U.; Carrafiello, L.; Lavacchi, A.; Niccolai, F.; Rizzi, G.

2003-12-01

140

Testing and modeling of diffusion bonded prototype optical windows under ITER conditions  

Microsoft Academic Search

Glass-metal joints are a part of ITER optical diagnostics windows. These joints must be leak tight for the safety (presence of tritium in ITER) and to preserve the vacuum. They must also withstand the ITER environment: temperatures up to 220 C and fast neutron fluxes of ?3109 n\\/cm2s. At the moment, little information is available about glass-metal joints suitable for

Marijke Jacobs; Guido Van Oost; Joris Degrieck; Ives De Baere; Andrei Gusarov; Frits Gubbels; Vincent Massaut

2011-01-01

141

Dynamics of supercritical methanol of varying density from first principles simulations: Hydrogen bond fluctuations, vibrational spectral diffusion, and orientational relaxation  

NASA Astrophysics Data System (ADS)

A first principles study of the dynamics of supercritical methanol is carried out by means of ab initio molecular dynamics simulations. In particular, the fluctuation dynamics of hydroxyl stretch frequencies, hydrogen bonds, dangling hydroxyl groups, and orientation of methanol molecules are investigated for three different densities at 523 K. Apart from the dynamical properties, various equilibrium properties of supercritical methanol such as the local density distributions and structural correlations, hydrogen bonding aspects, frequency-structure correlations, and dipole distributions of methanol molecules are also investigated. In addition to the density dependence of various equilibrium and dynamical properties, their dependencies on dispersion interactions are also studied by carrying out additional simulations using a dispersion corrected density functional for all the systems. It is found that the hydrogen bonding between methanol molecules decreases significantly as we move to the supercritical state from the ambient one. The inclusion of dispersion interactions is found to increase the number of hydrogen bonds to some extent. Calculations of the frequency-structure correlation coefficient reveal that a statistical correlation between the hydroxyl stretch frequency and the nearest hydrogen-oxygen distance continues to exist even at supercritical states of methanol, although it is weakened with increase of temperature and decrease of density. In the supercritical state, the frequency time correlation function is found to decay with two time scales: One around or less than 100 fs and the other in the region of 250-700 fs. It is found that, for supercritical methanol, the times scales of vibrational spectral diffusion are determined by an interplay between the dynamics of hydrogen bonds, dangling OD groups, and inertial rotation of methanol molecules and the roles of these various components are found to vary with density of the supercritical solvent. Effects of system size on the calculated structural and dynamical properties are also investigated in the present study.

Yadav, Vivek Kumar; Chandra, Amalendu

2013-06-01

142

Ambient-temperature creep failure of silver-aided diffusion bonds between steel  

Microsoft Academic Search

It has long been known that thin (e.g., 1 μm - 1 mm) interlayer bonds between higher strength base materials may have high ultimate tensile or rupture strengths despite the relatively low strength of the filler metal. The high strength of the joint is due to the mechanical constraint provided by the stronger base metals which restricts transverse contraction of

G. A. Henshall; M. E. Kassner; R. S. Rosen

1990-01-01

143

On the modelling of diffusion bonding in materials: superplastic Super Alpha2  

Microsoft Academic Search

Studies of microduplex Super Alpha-2 sheet have shown that the material has a considerable potential for superplastic deformation at temperatures in the range 940980C. Sound bonds were produced using isostatic pressure for different surface finishes at temperatures of 960 and 980C under conditions which were fully consistent with the predictions of the model described in the paper, and within the

J. Pilling; N. Ridley; M. F. Islam

1996-01-01

144

Atomic force microscopy imaging of TiO{sub 2} surfaces active for C-C bond formation reactions in ultrahigh vacuum  

SciTech Connect

TiO{sub 2}(001) single crystal surfaces active for a variety of different chemistries were examined using atomic force microscopy (AFM). C-C bond forming reactions previously identified on these surfaces include carboxylic acid ketonization, aldol condensation, reductive carbonyl coupling, and alkyne cyclotrimerization. The surfaces were prepared in ultrahigh vacuum (UHV) and examined by AFM in air. Surfaces examined included the (011)-faceted surface, (114)-faceted surface, and argon-ion-bombarded surfaces, as well as the mechanically polished single-crystal surface prior to treatment in UHV. The one unifying feature of all the images was their extreme flatness. Root-mean-square roughnesses were routinely less than 10 {Angstrom} in 500 x 500 nm scans. These same scans showed the surfaces to have surface areas exceeding that of an ideal flat surface by no more than 1.2%. Images of the polished surface revealed a variety of surface features, including polishing scratches and particle-like features. The argon-ion-bombarded surface and the faceted surfaces were composed of large flat plateaus ranging in size from 21 to 75 nm. The size of the plateaus was essentially the same for the ion bombarded surface and the (011)-faceted surface. The (114)-faceted surfaced exhibited slightly smaller plateau regions than the other surfaces. The images indicate that argon-ion bombardment, while disordering the surface and causing significant composition changes, does not lead to observable morphological changes on this scale. The relative uniformity of the surfaces examined is consistent with the selectivity of carbon-carbon bond-forming reactions that have been shown to take place on these surfaces. The images also reveal how the surface topography on the scale of the plateau structures observed is only slightly changed during the transformation of the surface unit cell structure from the (011)- to the (114)-faceted surface. 29 refs., 6 figs., 1 tab.

Watson, B.A.; Barteau, M.A. [Univ. of Delaware, Newark, DE (United States)

1994-06-01

145

Diffusion bonding of an aluminum-copper alloy reinforced with silicon carbide particles (AA2014/SiC/13p) using metallic interlayers  

SciTech Connect

In this work, the application of solid state diffusion bonding to a SiC particulate reinforced aluminium-copper alloy (AA2014) has been studied. The use of metallic interlayers such as an aluminum-lithium alloy and pure silver, has been tested. Bonding interfaces were microstructural characterized using scanning electron (SEM) and transmission electron microscopies (TEM). Joint strengths were evaluated by shear mechanical tests, completed with fractographic studies to determine the failure mechanisms of each kind of joint.

Urena, A.; Gomez de Salazar, J.M.; Escalera, M.D. [Univ. Complutense, Madrid (Spain). Dept. de Ciencia de los Materiales e Ingenieria Metalurgica

1996-12-01

146

Extra-thermodynamic study on surface diffusion in reversed-phase liquid chromatography using silica gels bonded with alkyl ligands of different chain lengths  

Microsoft Academic Search

Surface diffusion on adsorbents made of silica gels bonded to C, C, C, and C alkyl ligands was studied in reversed-phase liquid chromatography (RPLC) from the viewpoints of two extrathermodynamic relationships: enthalpy-entropy compensation (EEC) and linear free-energy relationship (LFER). First, the values of the surface diffusion coefficient (D{sub s}), normalized by the density of the alkyl ligands, were analyzed with

Kanji Miyabe; Georges A Guiochon

2005-01-01

147

MEMS Vacuum Packaging Technology and Applications  

Microsoft Academic Search

Many MEMS (micro electro-mechanic systems) parts have to meet the requirements for vacuum packaging. In vacuum packaging, leakage and gas permeation, which affects the normal function of the components, are major problems. Hermetic sealing is one of the most important technologies for reliable vacuum packaging. In this paper, several hermetic sealing technologies for vacuum packaging was presented, including eutectic bonding,

Jin Yufeng; Zhang Jiaxun

2005-01-01

148

MEMS vacuum packaging technology and applications  

Microsoft Academic Search

Vacuum packaging is essential for various kinds of microelectromechanical system (MEMS) devices for enhancing the performance and reliability. This paper presents our works on research on vacuum packaging of MEMS devices. A hermetical sealing technique has been developed, which involves the processes of anodic bonding for silicon and glass wafers with imperfect interface, adhesive bonding, glass frit bonding and silicon-to-gold

Y. Jin; Z. F. Wang; P. C. Lim; D. Y. Pan; J. Wei; C. K. Wong

2003-01-01

149

Optical Properties of Some Silicone Diffusion-Pump Oils in the Vacuum UltravioletUsing an Open-Dish Technique  

Microsoft Academic Search

The optical properties of Dow Corning-704 and -705 diffusion-pump oils have been measured from 4?24.8 eV using an open-dish technique. These are the first liquids for which optical constants have been obtained above 11.8 eV. In the region above 10.6 eV, the real part of the dielectric constant is structureless. A collective oscillation involving ? and ? electrons is seen

G. D. Kerr; M. W. Williams; R. D. Birkhoff; L. R. Painter

1971-01-01

150

Optical Properties of Some Silicone Diffusion-Pump Oils in the Vacuum UltravioletUsing a Closed-Cell Technique  

Microsoft Academic Search

The optical properties of Dow Corning-704 and -705 diffusion-pump oils have been measured from 2?10.6 eV using a closed-cell technique. The data are interpreted in terms of molecular excitations of ?, ?, and nonbonding electrons in the complex pump oil molecules and in terms of collective oscillations of electrons in the liquids. The optical constants of Dow Corning-200, another silicone

B. L. Sowers; M. W. Williams; R. N. Hamm; E. T. Arakawa

1971-01-01

151

Effect of Processing Temperature on the Texture and Shear Mechanical Properties of Diffusion Bonded Ti-6Al-4V Multilayer Laminates  

NASA Astrophysics Data System (ADS)

Two multilayer materials based on Ti-6Al-4V alloy have been processed by diffusion bonding at two different temperatures [1023 K and 1173 K (750 C and 900 C)]. The influence of the processing temperature on microstructure, texture, and mechanical properties of the two multilayer materials has been analyzed. Scanning electron microscopy, X-ray diffraction, electron backscatter diffraction, and shear tests have been used as experimental techniques. The multilayer laminate processed at the lowest temperature of 1023 K (750 C) exhibits mainly transversal texture in the longitudinal plane, which provides an anisotropic mechanical behavior, showing higher shear modulus and maximum shear strength under one of the shear test directions considered. In contrast, diffusion bonding at 1173 K (900 C) leads to basal/transversal texture because of the partial ? ? ? ? ? transformation, which provides more isotropic mechanical properties. Accordingly, this laminate shows similar shear modulus and maximum shear strength in different shear test orientations.

Cepeda-Jimnez, Carmen M.; Orozco-Caballero, Alberto; Sarkeeva, Aigul; Kruglov, Aleksey; Lutfullin, Ramil; Ruano, Oscar A.; Carreo, Fernando

2013-10-01

152

A first principles theoretical study of vibrational spectral diffusion and hydrogen bond dynamics in aqueous ionic solutions: D2O in hydration shells of Cl- ions  

NASA Astrophysics Data System (ADS)

A theoretical study of vibrational spectral diffusion and hydrogen bond dynamics in aqueous ionic solutions is presented from first principles without employing any empirical potential models. The present calculations are based on ab initio molecular dynamics for trajectory generation and wavelet analysis of the simulated trajectories for time dependent frequency calculations. Results are obtained for two different deuterated aqueous solutions: the first one is a relatively dilute solution of a single Cl- ion and the second one is a concentrated solution of NaCl (~3M) dissolved in liquid D2O. It is found that the frequencies of OD bonds in the anion hydration shell, i.e., those which are hydrogen bonded to the chloride ion, have a higher stretch frequency than those in the bulk water. Also, on average, the frequencies of hydration shell OD modes are found to increase with increase in the anion-water hydrogen bond distance. On the dynamical side, when the vibrational spectral diffusion is calculated exclusively for the hydration shell water molecules in the first solution, the dynamics reveals three time scales: a short-time relaxation (~200 fs) corresponding to the dynamics of intact ion-water hydrogen bonds, a slower relaxation (~3 ps) corresponding to the lifetimes of chloride ion-water hydrogen bonds, and another longer-time constant (~20 ps) corresponding to the escape dynamics of water from the anion hydration shell. Existence of such three time scales for hydration shell water molecules was also reported earlier for water containing a single iodide ion using classical molecular dynamics [B. Nigro et al., J. Phys. Chem. A 110, 11237 (2006)]. Hence, the present study confirms the basic results of this earlier work using a different methodology. However, when the vibrational spectral diffusion is calculated over all the OD modes, only two time scales of ~150 fs and ~2.7 ps are found without the slowest component of ~20 ps. This is likely because of the very small weight that the hydration shell water molecules carry to the overall spectral diffusion in the solution containing a single ion. For the concentrated solution also, the slowest component of ~20 ps is not found in the spectral diffusion of all water molecules because a distinct separation between the hydration shell and bulk water in terms of their stretch frequencies does not hold at this high concentration regime. The present first principles results are compared with those of the available experiments and classical simulations.

Mallik, Bhabani S.; Semparithi, A.; Chandra, Amalendu

2008-11-01

153

Diffusion Bonding of Zirconia.  

National Technical Information Service (NTIS)

The present research deals with the joining of the ceramic material zirconia to other materials and to itself. During the last decades a strong interest has evolved for ceramic materials. Many new types of ceramic materials were developed in view of their...

R. H. Vegter

1999-01-01

154

Direct diffusion bonding of Ti{sub 3}SiC{sub 2} and Ti{sub 3}AlC{sub 2}  

SciTech Connect

Two typical layered ternary compounds, Ti{sub 3}SiC{sub 2} and Ti{sub 3}AlC{sub 2}, were joined directly by solid-state diffusion bonding method. By various bonding tests at 1100-1300 deg. C for 30-120 min under 10-30 MPa, and characterizing the microstructure and diffusion reactive phases of the joints by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD), the optimal condition for direct joining of Ti{sub 3}SiC{sub 2} and Ti{sub 3}AlC{sub 2} was obtained. Strong joints of Ti{sub 3}SiC{sub 2}/Ti{sub 3}AlC{sub 2} can be achieved via diffusion bonding, which is attributed to remarkable interdiffusion of Si and Al at the joint interface. The shear strength of the Ti{sub 3}SiC{sub 2}/Ti{sub 3}AlC{sub 2} joints was determined.

Yin Xiaohui [School of Materials Science and Engineering, Anhui University of Technology, Ma'anshan 243002, Anhui Province (China); Li Meishuan, E-mail: mshli@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, No. 72, Wenhua Road, Shenyang 110016, Liaoning Province (China); Xu Jingjun; Zhang Jie; Zhou Yanchun [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, No. 72, Wenhua Road, Shenyang 110016, Liaoning Province (China)

2009-06-03

155

Characterization of Transient Liquid-Phase Bonded Joints in a Copper-Beryllium Alloy with Silver-base Interlayer  

NASA Astrophysics Data System (ADS)

Transient liquid-phase diffusion bonding was employed to join copper-beryllium alloy using three silver-base interlayers. The bonding process was carried out at different temperatures under argon and vacuum atmospheres for various hold times. Interfacial microstructures were examined by scanning electron microscopy. Microhardness, tensile, and fatigue tests were used for evaluating the mechanical properties. Maximum tensile strength of 156.45 MPa was obtained for bonds processed at 780 C. Fatigue strength of bonds fabricated in vacuum was higher than those of bonds prepared in argon atmosphere. The diffusion of the main elements from the interlayers into the base metal was the main controlling factor pertaining to the microstructural evolution of the joint interface.

Mazar Atabaki, M.

2012-06-01

156

The formation of nitride phases during diffusion bonding of Ni-Cr alloys with Si{sub 3}N{sub 4}-ceramic  

SciTech Connect

Interaction between dense silicon nitride ceramics and Ni and/or Ni-Cr alloys during diffusion bonding at 1,398 K was investigated. The reaction phenomena in these systems can be explained by assuming a high nitrogen pressure (fugacity), which is built up at the contact surface. Experimental results on diffusion couples were compared with those of direct nitriding of Ni-Cr(Si) alloys from the gas atmosphere (1--6,000 bar). Based on experimental data and thermodynamic considerations of the Ni-Cr-Si-N system, evidence for ``up hill`` diffusion of nitrogen near the precipitation front in the reaction zone between dense Si{sub 3}N{sub 4} and Ni-Cr alloys with 10--18 at% of Cr was found. This can be attributed to the relative instability of cubic chromium nitride (CrN) and the strong Cr-N interaction in the nickel-based solid solution.

Kodentsov, A.A.; Loo, F.J.J. van [Eindhoven Univ. of Technology (Netherlands). Lab. of Solid State Chemistry and Materials Science; Kivilahti, J.K. [Helsinki Univ. of Technology, Espoo (Finland). Dept. of Materials Science and Engineering

1995-08-01

157

Comparison of Diffusion Coefficients of Aryl Carbonyls and Aryl Alcohols in Hydroxylic Solvents. Evidence that the Diffusion of Ketyl Radicals in Hydrogen-Bonding Solvents is Not Anomalous?  

SciTech Connect

The diffusion coefficients of a benzyl-, sec-phenethyl-, and diphenylmethyl alcohol and the corresponding aryl carbonyls (benzaldehyde, acetophenone and benzophenone) were measured by Taylor's dispersion method in both ethyl and isopropyl alcohol. The experimental values are compared to published transient grating measurements of the corresponding aryl ketyl radicals (benzyl-, sec-phenethyl-, and diphenylmethyl-ketyl radical). In general, the diffusion coefficient of the aryl alcohols and the corresponding aryl ketyl radicals are equivalent within experimental error. This work shows that the diffusion of ketyl radicals is not anomalously slow and that aryl alcohols are significantly better models than the corresponding aryl ketones for analyzing the diffusion of aryl ketyl radicals in both ethyl and isopropyl alcohol. Empirical estimates of the diffusion coefficients of aryl alcohols using the Spernol-Wirtz and Wilke-Chang modifications to the Stokes-Einstein diffusion equation do not adequately account for the interactions between the aryl ketyl radicals or aryl alcohols with the hydroxylic solvents ethyl and isopropyl alcohol. The excellent agreement between the experimental diffusion coefficients of the aryl alcohols and the corresponding ketyl radicals show that the transient grating method can provide accurate estimates for the diffusion coefficients of transient species. This is especially important when a stable model is not available, for example the pyranyl radical.

Autrey, S Thomas (BATTELLE (PACIFIC NW LAB)); Camaioni, Donald M. (BATTELLE (PACIFIC NW LAB)); Kandanarachchi, Pramod H. (ASSOC WESTERN UNIVERSITY); Franz, James A. (BATTELLE (PACIFIC NW LAB))

2000-12-01

158

Ultrahigh Vacuum Twist Compression Apparatus  

Microsoft Academic Search

A new apparatus is described which is used for bonding of metals in ultrahigh vacuum by the twist compression technique. It is shown that adhesion between hard metal specimens can be readily measured in ultrahigh vacuum after some initial mechanical abrasion of the surfaces, while adhesion tests in air at atmospheric pressure do not yield measurable adhesion coefficients. Experimental results

J. M. Bradford; K. B. Wear; M. E. Sikorski

1970-01-01

159

Diffusion  

NSDL National Science Digital Library

Diffusion is the movement of particles from an area of high concentration to an area of low concentration. The molecules move until equilibrium is reached. If a perfume is sprayed on one side of the room, the perfume molecules will eventually spread out all over the room until there are equal concentrations of the molecules throughout the space.

Christopher Thomas (None;)

2006-11-09

160

Extra-thermodynamic study on surface diffusion in reversed-phase liquid chromatography using silica gels bonded with alkyl ligands of different chain lengths  

SciTech Connect

Surface diffusion on adsorbents made of silica gels bonded to C{sub 1}, C{sub 4}, C{sub 8}, and C{sub 18} alkyl ligands was studied in reversed-phase liquid chromatography (RPLC) from the viewpoints of two extrathermodynamic relationships: enthalpy-entropy compensation (EEC) and linear free-energy relationship (LFER). First, the values of the surface diffusion coefficient (D{sub s}), normalized by the density of the alkyl ligands, were analyzed with the modified Arrhenius equation, following the four approaches proposed in earlier research. This showed that an actual EEC resulting from substantial physicochemical effects occurs for surface diffusion and suggested a mechanistic similarity of molecular migration by surface diffusion, irrespective of the alkyl chain length. Second, a new model based on EEC was derived to explain the LFER between the logarithms of D{sub s} measured under different RPLC conditions. This showed that the changes of free energy, enthalpy, and entropy of surface diffusion are linearly correlated with the carbon number in the alkyl ligands of the bonded phases and that the contribution of the C{sub 18} ligand to the changes of the thermodynamic parameters corresponds to that of the C{sub 10} ligand. The new LFER model correlates the slope and intercept of the LFER to the compensation temperatures derived from the EEC analyses and to several parameters characterizing the molecular contributions to the changes in enthalpy and entropy. Finally, the new model was used to estimate D{sub s} under various RPLC conditions. The values of D{sub s} that were estimated from only two original experimental D{sub s} data were in agreement with corresponding experimental D{sub s} values, with relative errors of {approx}20%, irrespective of some RPLC conditions.

Miyabe, Kanji [Toyama University, Japan; Guiochon, Georges A [ORNL

2005-06-01

161

Extrathermodynamic study of surface diffusion in reversed-phase liquid chromatography with silica gels bonded with alkyl ligands of different chain lengths.  

PubMed

Surface diffusion on adsorbents made of silica gels bonded to C1, C4, C8, and C18 alkyl ligands was studied in reversed-phase liquid chromatography (RPLC) from the viewpoints of two extrathermodynamic relationships: enthalpy-entropy compensation (EEC) and linear free-energy relationship (LFER). First, the values of the surface diffusion coefficient (D(s)), normalized by the density of the alkyl ligands, were analyzed with the modified Arrhenius equation, following the four approaches proposed in earlier research. This showed that an actual EEC resulting from substantial physicochemical effects occurs for surface diffusion and suggested a mechanistic similarity of molecular migration by surface diffusion, irrespective of the alkyl chain length. Second, a new model based on EEC was derived to explain the LFER between the logarithms of D(s) measured under different RPLC conditions. This showed that the changes of free energy, enthalpy, and entropy of surface diffusion are linearly correlated with the carbon number in the alkyl ligands of the bonded phases and that the contribution of the C18 ligand to the changes of the thermodynamic parameters corresponds to that of the C10 ligand. The new LFER model correlates the slope and intercept of the LFER to the compensation temperatures derived from the EEC analyses and to several parameters characterizing the molecular contributions to the changes in enthalpy and entropy. Finally, the new model was used to estimate D(s) under various RPLC conditions. The values of D(s) that were estimated from only two original experimental D(s) data were in agreement with corresponding experimental D(s) values, with relative errors of approximately 20%, irrespective of some RPLC conditions. PMID:16852485

Miyabe, Kanji; Guiochon, Georges

2005-06-23

162

Diffusion of Mobile Ions and Bond Fluctuations in Superionic Conductor CuI from ab initio Molecular-Dynamics Simulations  

Microsoft Academic Search

The dynamic properties of mobile Cu ions in the superionic conductor CuI are studied by ab initio molecular-dynamics simulations. To investigate the bonding nature of the material, the gross charge of each ion and the overlap population between each Cu-I pair are calculated by the population analysis as a function of time. It is shown that the covalent bonding around

Fuyuki Shimojo; Masaru Aniya

2003-01-01

163

Chemical behavior in diffusion bonding of Si{sub 3}N{sub 4}-Ni and Si{sub 3}N{sub 4}-superalloy IN-738  

SciTech Connect

The bulk chemical reactions between Si{sub 3}N{sub 4} and Ni have been investigated from a thermodynamics perspective by Klomp et al. and Heikinheimo et al., and from experiments by Suganuma et al., Schuster et al., Brito et al., Ishikawa et al., and Heikinheimo et al. The chemical interaction between Si{sub 3}N{sub 4} and Ni-based alloy was investigated by Benett et al., Mehan et al., and Peteves et al. In this work, instead of the Ni-Cr, or model Ni-based superalloy (Ni-Cr-Al alloy), the industrial superalloy, IN-738, was used. For comparing the different chemical behaviors between the pure Ni and Ni-based superalloy with Si{sub 3}N{sub 4}, solid state diffusion bonding of Ni/Si{sub 3}N{sub 4} and IN-738/Si{sub 3}N{sub 4} were bonded in the same bonding conditions, except Ni/Si{sub 3}N{sub 4} specimens whose bonding time were longer than that of IN-738/Si{sub 3}N{sub 4} specimen.

Chen, Y.C.; Iwamoto, C.; Ishida, Y. [Univ. of Tokyo (Japan). Dept. of Material Science

1996-09-15

164

Pulsed gradient spin echo (PGSE) diffusion measurements as a tool for the elucidation of a new type of hydrogen-bonded bicapsular aggregate.  

PubMed

Compounds formed by linking two tris(ureidobenzyl)amine modules with a hexamethylene tether are described. These compounds self-assemble to form bicapsular aggregates featuring two rings of six hydrogen-bonded ureas. (1)H and (1)H/(1)H ROESY NMR spectroscopy, together with pulsed gradient spin echo (PGSE) NMR diffusion measurements, have been used to characterize the dimers in solution. The results have been compared with energy-minimized structures. The new compounds are kinetically stable on the NMR timescale, and their thermodynamic stabilities are comparable to other capsular aggregates derived from tris(ureidobenzyl)amines. PMID:16187374

Alajarn, Mateo; Pastor, Aurelia; Orenes, Ral-Angel; Martnez-Viviente, Elosa; Pregosin, Paul S

2006-01-11

165

Bonding characterization, density measurement, and thermal diffusivity studies of amorphous silicon carbon nitride and boron carbon nitride thin films  

Microsoft Academic Search

Thermal diffusivity (?) of amorphous silicon carbon nitride (a-SiCxNy) and boron carbon nitride (a-BCxNy) thin films on crystalline silicon has been studied as a function of the carbon content and thickness of the films using the traveling wave technique. The thermal diffusivity showed a steady fall from ?0.35 to about 0.15 cm2\\/s for a-SiCxNy films as the carbon content increased

S. Chattopadhyay; L. C. Chen; S. C. Chien; S. T. Lin; K. H. Chen

2002-01-01

166

Bonding characterization, density measurement, and thermal diffusivity studies of amorphous silicon carbon nitride and boron carbon nitride thin films  

Microsoft Academic Search

Thermal diffusivity (alpha) of amorphous silicon carbon nitride (a-SiCxNy) and boron carbon nitride (a-BCxNy) thin films on crystalline silicon has been studied as a function of the carbon content and thickness of the films using the traveling wave technique. The thermal diffusivity showed a steady fall from approx0.35 to about 0.15 cm2\\/s for a-SiCxNy films as the carbon content increased

S. Chattopadhyay; L. C. Chen; S. C. Chien; S. T. Lin; K. H. Chen

2002-01-01

167

Nickel nanoparticles-assisted diffusion brazing of stainless steel 316 for microfluidic applications  

NASA Astrophysics Data System (ADS)

Transient liquid-phase diffusion brazing is used in precision, hermetic joining applications as a replacement for diffusion bonding to reduce cycle times, reduce bonding pressure and improve yields. Studies showed that the interlayer used in diffusion brazing can be detrimental due to the use of melting point depressants (MPDs). The goal of this study was to investigate the role of nanoparticles and their size distribution in reducing bonding temperature of stainless steel surfaces for Microfluidic applications, as nanoparticles have inherently lower melting point and higher diffusivity than that of their bulk counterpart. The conventional interlayer has been replaced by a nickel nanoparticle (NiNP) film without any MPDs for diffusion brazing of stainless steel 316L laminae. Brazing was carried out in a uni-axial vacuum hot press at temperatures 750C, 800C, 900C and 1000C; at a bonding pressure of 10 MPa; at a heating rate of 10C/min and dwell times of 1 and 2 hrs at each temperature. Comparison among the conventionally diffusion bonded, diffusion brazed and NiNP diffusion brazed samples is made with regard to microstructural evolution, diffusional profile and bond strength. Taken together, the results show that NiNP-assisted diffusion brazed samples have continuous bond line with low void fraction and high shear strength compared to conventionally diffusion bonded and brazed samples. Also, comparing within the NiNP diffusion brazed group, the samples brazed at 900C have the best results. Effect of particle size on diffusion brazing of stainless steel 316 was also studied with the help of two different sets of nanoparticles (N1: average particle size of 46.7+/-6.2 nm and N2: average particle size 8.8+/-0.9 nm.) Results showed that the sample brazed with 8.8 nm particles indicated better results with a more homogeneous bondline structure. The findings of this work have positive implications for the economics of NP-assisted diffusion brazing.

Tiwari, Santosh K.

168

Random walk properties from lattice bond enumeration: Anisotropic diffusion in lattices with periodic and randomly distributed scatterers  

PubMed Central

A lattice bond enumeration method recently devised for the study of random walk problems is used to rederive, with relative ease, the classic Maxwell-Rayleigh formulas for the effective de conductivity of a heterogeneous solid composed of periodically (or randomly) arrayed spheres in a medium of a different material.

Shuler, Kurt E.; Mohanty, Udayan

1981-01-01

169

VACUUM TRAP  

DOEpatents

An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.

Gordon, H.S.

1959-09-15

170

End-to-end distance distributions and intrachain diffusion constants in unfolded polypeptide chains indicate intramolecular hydrogen bond formation  

Microsoft Academic Search

Characterization of the unfolded state is essential for the understanding of the protein folding reaction. We performed time-resolved FRET measurements to gain information on the dimensions and the internal dynamics of unfolded polypeptide chains. Using an approach based on global analysis of data obtained from two different donor-acceptor pairs allowed for the determination of distance distribution functions and diffusion constants

Andreas Mglich; Karin Joder; Thomas Kiefhaber

2006-01-01

171

Vacuum Technology  

SciTech Connect

The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in electronics, manufacturing and semiconductor fabrication. In conclusion, an understanding of the basic principles of vacuum technology as presented in this summary is essential for the successful execution of all projects that involve vacuum technology. Using the principles described above, a practitioner of vacuum technology can design a vacuum system that will achieve the project requirements.

Biltoft, P J

2004-10-15

172

High heat load properties of actively cooled W/CuCrZr mock-ups by cladding and diffusion bonding with a two-step process  

NASA Astrophysics Data System (ADS)

The surface of W was grooved into an arc wave surface, on which a Cu layer was then clad at 1150-1200 C to form a pre-joining clad sample. The clad sample was then diffusion bonded to a CuCrZr at 450 C to form an actively cooled mock-up. The thermal response and thermal fatigue properties were investigated by active cooling technology. The results showed that no cracks and voids occurred at the interface of W/CuCrZr mock-ups after thermal response test with a heat flux from 0 to 10 MW/m2, which survived up to 200 cycles under 10 MW/m2. The residual stresses of the mock-up were estimated by Finite Element Analysis. The simulation results indicated that the residual stresses were more beneficial to crack arrest for the mock-up using an arc wave interface instead of a flat interface. This technique provides an available method of bonding W to CuCrZr.

Li, Jun; Yang, Jian-Feng; Chen, Jun-Ling

2011-11-01

173

Vacuum Ultraviolet Photochemistry of Tetrahydrothiophene and Sulfolane.  

National Technical Information Service (NTIS)

The vacuum uv photolysis of tetrahydrothiophene (THT) involves the breaking of the S to alpha -C bond. Besides ethylene, C sub 3 H sub 6 and 1,3-butadiene are also formed. Photolyses of THT, tetrahydrofuran, and pyrrolidine are similar. The vacuum uv phot...

A. A. Scala I. Colon

1979-01-01

174

Vacuum Gauges  

NSDL National Science Digital Library

This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. Semiconductor manufacturing equipment requires the use of many different types of vacuum gauges. Selection is based on range of process operations and production requirements. This MATEC module explores the theory and functionality of vacuum gauges and provides many examples of different types of gauges. The focus is on understanding the operating ranges and application constraints of each type of gauge. Mathematical equations are used to explain calibration, sensitivity, and overall operations of each type of gauge.

2012-11-28

175

Effect of H-bond active sites on transport properties of poly(ethylene oxide) dissolved in its monomers: Shear viscosity and diffusion coefficient studies  

NASA Astrophysics Data System (ADS)

The possibility of dissolving poly(ethylene oxide) [PEO:H-(O-CH2-CH2)n-OH] in its monomeric liquid ethylene glycol [EG:H-(O-CH2-CH2)-OH] represents the only way to verify the complex polymer-monomer interactions, through the OH end groups, resulting in the scaling law R~N?. We report viscosity results, in conjunction with photon correlation spectroscopy data, on different molecular weight PEO samples, in a wide range of concentrations, dissolved in EG. In order to distinguish among various interaction mechanisms, we also studied PEO dissolved in EG monomethyl ether [EGmE:CH3-(O-CH2-CH2)-OH] and EG dimethyl ether [EGdE:CH3-(O-CH2-CH2)OCH3], the latter not having in its chemical structure OH hydroxylic groups available to give rise to hydrogen bond interactions. In particular, the quality (good-theta-poor) of the solvents has been analyzed by verifying the well-known Mark-Houwink-Sakurada scaling law and the effects of the polymer-solvent interactions on the coils diffusive properties.

Crupi, V.; Faraone, A.; Maisano, G.; Majolino, D.; Migliardo, P.; Venuti, V.; Villari, V.

2000-03-01

176

Vacuum Technique  

Microsoft Academic Search

Let me say from the beginning that it was a pleasure to peruse this book and I recommend it to researchers and engineers from the field of Cryogenics, both as an introduction and for use in day-to-day work.There are many areas in pure science in which vacuum conditions are required for conducting an experiment, such as solid state physics at

L N Rozanov

2002-01-01

177

Edge conduction in vacuum glazing  

SciTech Connect

Vacuum glazing is a form of low-conductance double glazing using in internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. An array of small support pillars separates the sheets; fused solder glass forms the edge seal. Heat transfer through the glazing occurs by radiation across the vacuum gap, conduction through the support pillars, and conduction through the bonded edge seal. Edge conduction is problematic because it affects stresses in the edge region, leading to possible failure of the glazing; in addition, excessive heat transfer because of thermal bridging in the edge region can lower overall window thermal performance and decrease resistance to condensation. Infrared thermography was used to analyze the thermal performance of prototype vacuum glazings, and, for comparison, atmospheric pressure superwindows. Research focused on mitigating the edge effects of vacuum glazings through the use of insulating trim, recessed edges, and framing materials. Experimentally validated finite-element and finite-difference modeling tools were used for thermal analysis of prototype vacuum glazing units and complete windows. Experimental measurements of edge conduction using infrared imaging were found to be in good agreement with finite-element modeling results for a given set of conditions. Finite-element modeling validates an analytic model developed for edge conduction.

Simko, T.M.; Collins, R.E. [Sydney Univ., NSW (Australia). Dept. of Applied Physics; Beck, F.A.; Arasteh, D. [Lawrence Berkeley Lab., CA (United States)

1995-03-01

178

Reliability of MEMS packaging: vacuum maintenance and packaging induced stress  

Microsoft Academic Search

In this study, the dominant reliability issues of MEMS packaging that include vacuum maintenance and packaging induced stress, are discussed, and design considerations to improve the reliability are presented. The MEMS vibratory gyroscope sensor is fabricated with anodically bonded wafer level vacuum packaging followed by die-bonding and wire-bonding processes. The epoxy-molding compound (EMC) is applied to encapsulate the gyroscope sensor.

Sung-Hoon Choa

2005-01-01

179

Wafer bonding of wide bandgap materials  

NASA Astrophysics Data System (ADS)

Wafer bonding is a powerful technique for integration of materials. It enables creation of junctions and structures not attainable by the epitaxial growth due to lattice mismatch. Wafer bonding may involve no intermediate layer and allow the joined wafers to be stable at elevated temperatures. Atomically smooth and flat wafers of almost any material spontaneously bond to each other even at room temperature, although further annealing might be required to increase the strength of bonding. High values of surface roughness make the bonding process more challenging. In this case, high temperature combined with applied stress is an effective route for a successful process. The goal of the current work was to assess the potential of pressure assisted wafer bonding technique applied to diamond/silicon and silicon carbide/silicon carbide systems, where the wafer surface smoothness was limited. Polished and unpolished (100) highly oriented diamond (HOD) films with an RMS roughness of 5 nm and 150 nm, respectively, as well as polished, polycrystalline diamond films with an RMS roughness of 15 nm were bonded to single-side polished silicon in ultra high vacuum at 32 MPa of applied uniaxial pressure. Successful fusion of unpolished HOD and polished polycrystalline diamond was observed at temperatures as low as 950C while bonding of polished HOD to silicon was achieved at 850C. Fusion of polished polycrystalline diamond to silicon resulted in the formation of a non-uniform bonded interface. An abrupt boundary between the two wafers existed only in some regions of the interface, while other regions contained an up to 40 nm thick amorphous interlayer consisting of C, Si and O. A local phase transformation of diamond to graphite near the diamond surface asperities followed by inter-diffusion of C and Si has been suggested. Fusion of polished HOD to Si resulted in the formation of the abrupt interface between the wafers, in the areas away from the diamond grain boundaries. Voids, partially filled with amorphous material, were observed at the fused interface near the diamond grain boundaries. Diamond polishing defects, potential out-diffusion of hydrogen from diamond and oxygen from Si are believed to have contributed to the observed non-uniformity of the bonded interface. SiC wafers with an RMS roughness of 2 run were successfully bonded at temperatures as low as 800C. Cross-section transmission electron microscopy (XTEM) of specimens bonded at 1100C revealed an atomically abrupt interface between the bonded wafers without any intermediate layer between them. The bonded SiC retained its high crystalline quality; no extended defects emanating from the interface were observed within the sampling region. Electrical measurements showed that azimuthal orientation of the bonded couple significantly influences the electrical character of the junction. A low resistance Ohmic interface can be created by high temperature fusion of aligned 6H-SiC/6H-SiC wafers.

Yushin, Gleb Nikolayevich

180

Method of Bonding Molybdenum to Steel.  

National Technical Information Service (NTIS)

A thin layer of silver metal is formed between a molybdenum surface and a steel surface. The silver metal layer is diffusion bonded to the molybdenum surface and diffusion bonded to the steel surface, thus bonding the molybdenum and steel surfaces togethe...

W. A. Ferrando S. D. Karmarkar S. M. Hoover A. P. Divecha

1992-01-01

181

D-Zero Vacuum System  

SciTech Connect

The system pumping speed was calculated by taking the reciprocal of the sum of the reciprocal pump speed and the reciprocal line conductances. The conductances of the pipe were calculated from the following formulas taken from the Varian vacuum manual. This report updates the original to reflect the pumping curves and basic vacuum system characteristics for the purchased components and installed piping of the D-Zero vacuum system. The system consists of two Edward's E2M275 two stage mechanical pumps, a Leybold-Heraeus WSU2000 Blower and three Varian 4' diffusion pumps (one for each cryostat). Individual pump and system pumping speed curves and a diagram of the system is included.

Wintercorn, S.J.; /Fermilab

1986-04-07

182

Vacuum ultraviolet photochemistry of tetrahydrothiophene and sulfolane  

Microsoft Academic Search

The vacuum uv photolysis of tetrahydrothiophene (THT) involves the breaking of the S to ..cap alpha..-C bond. Besides ethylene, CH and 1,3-butadiene are also formed. Photolyses of THT, tetrahydrofuran, and pyrrolidine are similar. The vacuum uv photolysis of tetramethylene sulfone (sulfolane) was also studied; products are SO, cyclobutane, 1-butene, and ethylene. No cis-2-butene was observed. (DLC)

A. A. Scala; I. Colon

1979-01-01

183

Vacuum deposition and curing of liquid monomers  

DOEpatents

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of ``standard`` polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Affinito, J.D.

1995-03-07

184

Vacuum deposition and curing of liquid monomers  

DOEpatents

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of standard polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Affinito, J.D.

1993-11-09

185

A Study on the Breakdown Mechanism of an Electroless-Plated Ni(P) Diffusion Barrier for Cu/Sn/Cu 3D Interconnect Bonding Structures  

NASA Astrophysics Data System (ADS)

This study examined the thermal stability of an electroless-plated Ni(P) barrier layer inserted between Sn and Cu in the bonding structure of Cu/Sn/Cu for three-dimensional (3D) interconnect applications. A combination of transmission electron microscopy (TEM) and scanning electron microscopy allowed us to fully characterize the bonding morphology of the Cu/Ni(P)/Sn/Ni(P)/Cu joints bonded at various temperatures. The barrier suppressed Cu and Sn interdiffusion very effectively up to 300C; however, an interfacial reaction between Ni(P) and Sn led to gradual decomposition into Ni3P and Ni3Sn4. Upon 350C bonding, the interfacial reaction brought about complete disintegration of the barrier in local areas, which allowed unhindered interdiffusion between Cu and Sn.

Lee, Byunghoon; Jeon, Haseok; Jeon, Seong-Jae; Kwon, Kee-Won; Lee, Hoo-Jeong

2012-01-01

186

A Vacuum Drying Model for Mango Pulp  

Microsoft Academic Search

Vacuum drying of mango pulp at varying conditions of pulp thickness (2, 3, and 4mm) and vacuum chamber plate temperature (65, 70, and 75C) was carried out under 3050mm of mercury absolute pressure. A model based on moisture diffusivity was found to give close prediction to moisture content of the pulp at different times of drying with correlation coefficient varying

S. Jaya; H. Das

2003-01-01

187

The Vacuum Bubble Nucleation  

SciTech Connect

We study the nucleation of a vacuum bubble via the vacuum-to-vacuum tunneling transition in curved spacetime. We consider Coleman-de Luccia's semiclassical approximation at zero temperature in pure Einstein theory of gravity and the theory with nonminimal coupling. We discuss the dynamics of a nucleated vacuum bubble.

Lee, Bum-Hoon [Department of Physics and Center for Quantum Spacetime, Sogang University Seoul 121-742 (Korea, Republic of); Lee, Wonwoo [Center for Quantum Spacetime, Sogang University, Seoul 121-742 (Korea, Republic of)

2009-07-10

188

Performance tests of large thin vacuum windows  

SciTech Connect

Tests of thin composition vacuum windows of the type used for the Tagger in Hall B at the Thomas Jefferson National Accelerator Facility are described. Three different tests have been performed. These include: (1) measurement of the deformation and durability of a window under long term (>8 years) almost continuous vacuum load, (2) measurement of the deformation as a function of flexing of the window as it is cycled between vacuum and atmosphere, and (3) measurement of the relative diffusion rate of gas through a variety of thin window membranes.

Hall Crannell

2011-02-01

189

DIFFUSION PUMP  

DOEpatents

A high-vacuum diffusion pump is described, featuring a novel housing geometry for enhancing pumping speed. An upright, cylindrical lower housing portion is surmounted by a concentric, upright, cylindrical upper housing portion of substantially larger diameter; an uppermost nozzle, disposed concentrically within the upper portion, is adapted to eject downwardly a conical sheet of liquid outwardly to impinge upon the uppermost extremity of the interior wall of the lower portion. Preferably this nozzle is mounted upon a pedestal rising coaxially from within the lower portion and projecting up into said upper portion. (AEC)

Levenson, L.

1963-09-01

190

Diffuse reflectance Fourier transform infrared spectroscopic study of chemical bonding and hydrothermal stability of an amino silane on metal oxide surfaces. Technical report  

Microsoft Academic Search

Fourier transform infrared spectroscopy is used to study the metal oxide\\/silane interface. Structures of gamma-aminopropyldimethylethoxysilane (gamma-APDMES) coupling agent on the surface of metal oxide powders are proposed. The structure depends on the surface characteristics of the substrate. The amine group of the silane molecule forms a hydrogen bond with the silica surface. The enhanced intensity of the amine band around

S. Naviroj; J. L. Koenig; H. Ishida

1982-01-01

191

Vacuum drying of oak wood  

SciTech Connect

Vacuum drying, i.e., drying under absolute gas pressure of about 10{sup 4} Pa, is an efficient means of reducing the process period and of producing good quality wood. The authors will examine here continuous vacuum drying where the plank surfaces are kept at a constant temperature, which remains above the boiling point, and moisture flowing to the surface is extracted from the kiln. They have carried out an experimental study of oak drying under such conditions. The drying rate and moisture content profile of the sample (40 mm thick) are recorded during the whole drying period. A model of continuous drying is established from general conservation equations with the main approximation that the air is rapidly extracted. The two constitutive equations of the model which describe temperature and water content fields are of a diffusive type and coupled through coefficients. The adequate boundary equation is not a convective one, but expresses a hygroscopic equilibrium between the vapor in the chamber and the wood surface. The mass diffusive coefficient can be adjusted to the drying rates through capillary pressure and bound water diffusion functions. The wood heterogeneity (seasonal growth) is the main factor of discrepancy in these functions. The simulated drying rates correspond with the experimental ones.

Fohr, J.P.; Chakir, A.; Arnaud, G.; Peuty, M.A. du [L.E.T.-UA CNRS, Poitiers (France)

1995-12-31

192

Chemical Bonds  

NSDL National Science Digital Library

Electrons are key to forming the two broad categories of chemical bonds: covalent and ionic. Atoms, which have a nucleus surrounded by electrons, are represented in several different ways. In the Chemical Bonds activity, students explore the different kinds of chemical bonds that can form, ranging from non-polar covalent to ionic. In the model depicted above students adjust the electronegativity of two atoms and see the effect it has on electron distribution and bond type.

Consortium, The C.

2011-12-11

193

Educational Vacuum Trainers  

NSDL National Science Digital Library

Have you inherited a bell jar vacuum system and are scratching your head over how to set it up or are unsure of its operations or capabilities? Or do you want to do more with your bell jar vacuum? The forum on Bell Jar Vacuums - with the topic Vacuum Trainers can help you. The intent of this forum is for this to be a place where technical issues, classroom exercises, activities, etc. can be discussed. There's no endorsement by manufacturers and commercial issues are off limits. Steve Hansen (bell jar expert) gives some brief descriptions of the vacuum trainers that are or have been available over the past decade or so - Varian, MKS, Science Source, American Vacuum Society. Links are provided to various data sheets, articles and online exercises. Steve, the forum moderator has experience in all of these.Keywords: vacuum, "vacuum trainer","bell jar" and/or belljar, MKSVarian, VPAL, VTS, sputtering, plasma

Hansen, Steve

2012-07-31

194

Optimizing process vacuum condensers  

SciTech Connect

Vacuum condensers play a critical role in supporting vacuum processing operations. Although they may appear similar to atmospheric units, vacuum condensers have their own special designs, considerations and installation needs. By adding vacuum condensers, precondensers and intercondensers, system cost efficiency can be optimized. Vacuum-condensing systems permit reclamation of high-value product by use of a precondenser, or reduce operating costs with intercondensers. A precondenser placed between the vacuum vessel and ejector system will recover valuable process vapors and reduce vapor load to an ejector system--minimizing the system`s capital and operating costs. Similarly, an intercondenser positioned between ejector stages can condense motive steam and process vapors and reduce vapor load to downstream ejectors as well as lower capital and operating costs. The paper describes vacuum condenser systems, types of vacuum condensers, shellside condensing, tubeside condensing, noncondensable gases, precondenser pressure drop, system interdependency, equipment installation, and equipment layout.

Lines, J.R.; Tice, D.W. [Graham Mfg. Co., Batavia, NY (United States)

1997-09-01

195

Sticker Bonding.  

ERIC Educational Resources Information Center

|Introduces a science activity on the bonding of chemical compounds. Assigns students the role of either a cation or anion and asks them to write the ions they may bond with. Assesses students' understanding of charge, bonding, and other concepts. (YDS)|

Frazier, Laura Corbin

2000-01-01

196

Sticker Bonding.  

ERIC Educational Resources Information Center

Introduces a science activity on the bonding of chemical compounds. Assigns students the role of either a cation or anion and asks them to write the ions they may bond with. Assesses students' understanding of charge, bonding, and other concepts. (YDS)

Frazier, Laura Corbin

2000-01-01

197

New vacuum arc control technology and its application  

Microsoft Academic Search

This paper presents the vacuum arc characteristics and the high current interruption ability of several sizes of electrodes which are applied in the authors' new vacuum arc control method named SADE: self arc diffusion by electrode. The arc behavior of the test electrode during the arcing period was observed by a high speed video camera. For extremely high interruption current,

Y. Niwa; K. Nitta; K. Yokokura; H. Somei; E. Kaneko

2000-01-01

198

Variable Orifice for Differential Pumping in a Vacuum System.  

National Technical Information Service (NTIS)

In differential pumping, the pumping speed has in the past been controlled by the size of the orifice between the vacuum chamber and the diffusion pump. This fixed orifice is usually in the valve gate of a high-vacuum valve (or in a baffle plate). To chan...

R. Beeman S. Brajkovich

1976-01-01

199

Strength and leak testing of plasma activated bonded interfaces  

Microsoft Academic Search

Bond strength and hermeticity of plasma activated bonded (PAB) SiSi interfaces are reported. Bonding of 100mm Si(100) wafers was performed. An average bond strength of 9.03.9MPa was achieved without performing any annealing steps. Cavities bonded in vacuum were found to be hermetic based on detection of changes in membrane deflections. The detection limit for leak was 8E?13mbarl\\/s. For comparison, strength

M. M. Visser; S. Weichel; R. de Reus; A. B. Hanneborg

2002-01-01

200

Vacuum properties of palladium thin film coatings  

Microsoft Academic Search

A recent development, carried out at CERN for particle accelerator applications, showed that a vacuum chamber coated with a thin getter film and then exposed to ambient air may be transformed into a pump by in situ heating at temperatures as low as 180C.Heating activates the diffusion into the film of the oxygen present in the surface passivation layer. Repeated

C. Benvenuti; P. Chiggiato; F. Cicoira; Y. LAminot; V. Ruzinov

2004-01-01

201

The Classical Vacuum.  

ERIC Educational Resources Information Center

|The classical vacuum of physics is not empty, but contains a distinctive pattern of electromagnetic fields. Discovery of the vacuum, thermal spectrum, classical electron theory, zero-point spectrum, and effects of acceleration are discussed. Connection between thermal radiation and the classical vacuum reveals unexpected unity in the laws of

Boyer, Timothy H.

1985-01-01

202

Vacuum String Field Theory  

Microsoft Academic Search

This is a brief review of vacuum string field theory, a new approach to open string field theory based on the stable vacuum of the tachyon. We discuss the sliver state explaining its role as a projector in the space of half-string functionals. We review the construction of D-brane solutions in vacuum string field theory, both in the algebraic approach

Leonardo Rastelli; Ashoke Sen; Barton Zwiebach

2001-01-01

203

The Classical Vacuum.  

ERIC Educational Resources Information Center

The classical vacuum of physics is not empty, but contains a distinctive pattern of electromagnetic fields. Discovery of the vacuum, thermal spectrum, classical electron theory, zero-point spectrum, and effects of acceleration are discussed. Connection between thermal radiation and the classical vacuum reveals unexpected unity in the laws of

Boyer, Timothy H.

1985-01-01

204

Rehydration Behavior of Vacuum-Microwave-Dried Potato Cubes  

Microsoft Academic Search

Rehydration properties and microstructure of vacuum-microwave and hot airdried potato cubes were examined. Two kinds of models were considered to describe the hydration kinetics: a diffusion model for a cube and two empirical equations, Peleg and Weibull. The values of the effective moisture diffusivity of soaked potatoes were in the range 1.17נ10 to 4.73נ10m\\/s. The vacuum-microwave drying technique resulted in

Marek Markowski; Joanna Bondaruk; Wioletta B?aszczak

2009-01-01

205

Encapsulation of vacuum sensors in a wafer level package using a gold-silicon eutectic  

Microsoft Academic Search

A vacuum package based on gold-silicon eutectic wafer bonding has been developed and evaluated using high sensitivity poly-Si Pirani vacuum sensors. Encapsulation of the devices was achieved by bonding a silicon cap wafer to a device wafer using a Au-Si eutectic solder at or above 390C in a vacuum bonder. The Au-Si eutectic solder encircled the devices, providing an airtight

Jay Mitchell; G. R. Lahiji; K. Najafi

2005-01-01

206

Germanium detector vacuum encapsulation  

SciTech Connect

The encapulation of germanium detectors has been a long sought after goal. We have begun to develop encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented in the paper.

Madden, N.W.; Malone, D.F.; Phel, R.H.; Cork, C.P.; Luke, P.N.; Landis, D.A.; Pollard, M.J. (Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720 (United States))

1991-08-01

207

Vacuum pump aids ejectors  

SciTech Connect

The steam ejector/vacuum pump hybrid system has been operating satisfactorily since the summer of 1981. This system has essentially been as troublefree as the all-ejector system and, of course, has provided a substantial cost savings. Construction is currently under way to convert the vacuum system of another crude still which is equipped with steam ejectors and barometric condensers to the hybrid system of steam ejectors, surface condensers, and vacuum pumps. This current project is even more financially attractive because it allows a dirty water cooling tower which serves the barometric condensers to be shut down. Providing a vacuum for crude distillation vacuum towers with this hybrid system is by no means the only application of this technique. Any vacuum system consisting of all steam ejectors would be a candidate for this hybrid system and the resulting savings in energy.

Nelson, R.E.

1982-12-01

208

Baffles for Oil Diffusion Pumps  

Microsoft Academic Search

Although in the use of oil diffusion pumps for the production of high vacuum, extremely cold traps in the usual sense are not required, some means must be provided to prevent both direct backstreaming and diffusion of the oil vapor. The relative advantages of (1) charcoal traps, (2) cold traps, (3) hot baffles, (4) electrical baffles, (5) mechanical baffles are

Richard S. Morse

1940-01-01

209

?-vacuum and inflationary bispectrum  

Microsoft Academic Search

In this paper, we discuss the non-Gaussianity originated from the ?-vacuum on the CMB anisotropy. For ?-vacuum, there exist correlation between points in the acausal two patches of de Sitter spactime. Such kind of correlation can lead to large local form non-Gaussianity in ?-vacuum. For the single field slow- roll inflationary scenario, the spacetime is in a quasi-de Sitter phase

Wei Xue

2009-01-01

210

Vacuuming radioactive sludge  

ScienceCinema

Vacuuming an estimated 55 cubic yards of radioactive sludge from the floor of Hanford's K East Basin was a complicated process. Workers stood on grates suspended above the 20-foot deep basin and manipulated vacuuming equipment at the end of long poles--using underwater cameras to guide their work.

211

Working in a Vacuum  

ERIC Educational Resources Information Center

|In this article, the author discusses several myths about vacuum cleaners and offers tips on evaluating and purchasing this essential maintenance tool. These myths are: (1) Amps mean performance; (2) Everyone needs high-efficiency particulate air (HEPA): (3) Picking up a "bowling ball" shows cleaning power; (4) All vacuum bags are the same; (5)

Rathey, Allen

2005-01-01

212

Vacuum technology for ITER  

Microsoft Academic Search

The vacuum systems for ITER are characterized by the requirements for tritium compatibility, tolerance of high magnetic and radiation fields and remote maintainability. In addition, although the vacuum levels are relatively modest, high pumping speeds are needed to achieve the high gas throughputs required. The design solutions adopted, the status of the development programme and the issues still to be

D. Murdoch; A. Antipenkov; C. Caldwell-Nichols; C. Day; M. Dremel; H. Haas; V. Hauer; H. Jensen

2008-01-01

213

The ITER vacuum systems  

Microsoft Academic Search

ITER is a large vacuum facility which comprises many service, diagnostic and monitoring vacuum sub-systems as well as three large cryogenic pumping systems for evacuation and maintenance of the required pressure levels. Control of the gas throughput is one of the key issues affecting the performance and achievable burn time of a fusion reactor. The main pumping systems are the

C. Day; D. Murdoch

2008-01-01

214

Vacuum driven accelerated expansion  

Microsoft Academic Search

It has been shown that an improved estimation of quantum vacuum energy can yield not only acceptable but also experimentally sensible results. The very idea consists in a straightforward extraction of gravitationally interacting part of the full quantum vacuum energy by means of gauge transformations. The implementation of the idea has been performed in the formalism of effective action, in

B. Broda; P. Bronowski; Marcin Ostrowski; Micha? Szanecki

2008-01-01

215

Influence of Joining Conditions on Bonding Strength of Joints: Efficacy of Low-Temperature Bonding Using Cu Nanoparticle Paste  

NASA Astrophysics Data System (ADS)

We investigated a new low-temperature bonding process utilizing Cu nanoparticle paste without addition of sintering promoter. Joint bonding strengths above 30 MPa were achieved even at a low bonding temperature of 250C. We attribute the higher bonding strengths of joints fabricated using the vacuum preheating process to the rapid progression of Cu nanoparticle sintering due to the activated nanoparticle surface at lower temperatures. The increase in bonding strength depended on the applied pressure, in addition to the bonding temperature. The formation of a dimple-like morphology was confirmed in the ductile fracture area. This indicated that the joint bonded strongly with the bonding layer, in agreement with the results of bonding tests carried out on strongly bonded joints. The bonding ability of the joints obtained using Cu nanoparticle paste could be improved by controlling the joint fabrication conditions.

Yamakawa, Tomohiro; Takemoto, Tadashi; Shimoda, Masayoshi; Nishikawa, Hiroshi; Shiokawa, Kunio; Terada, Nobuto

2013-06-01

216

Synthesis of ultrathin carbon films by direct current filtered cathodic vacuum arc  

NASA Astrophysics Data System (ADS)

Filtered cathodic vacuum arc was used to synthesize ultrathin carbon films on silicon substrates. The depth profiles, near-surface chemical composition, fractions of tetrahedral (sp3) and trigonal (sp2) carbon atom hybridizations, roughness, and hardness of the carbon films were determined from Monte Carlo (T-DYN) simulations and x-ray reflectivity (XRR), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and surface force microscopy (SFM) measurements, respectively. Films of thickness of only a few nanometers possessed smaller sp3 fractions than much thicker films. The effective hardness was found to depend on the sp3 fraction and silicon-carbon composition profile. The formation of different carbon atom bonds, film growth mechanisms, and optimum process conditions for synthesizing ultrathin carbon films are interpreted in the context of T-DYN, XRR, XPS, AFM, and SFM results and surface bombardment, adsorption, and diffusion mechanisms.

Zhang, H.-S.; Komvopoulos, K.

2009-04-01

217

Investigations of Pulsed Vacuum Gap.  

National Technical Information Service (NTIS)

Past research and the current status of understanding of electrical breakdown of vacuum is reviewed. This review includes DC, AC and pulsed vacuum gap breakdown. Measurements have been performed to determine the role of microparticles in pulsed vacuum gap...

J. E. Thompson T. S. Sudarshan J. M. Butner

1981-01-01

218

Vacuum deposition and curing of liquid monomers apparatus  

DOEpatents

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of ``standard`` polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface. 3 figs.

Affinito, J.D.

1996-08-20

219

Electrode erosion under high current vacuum arcs  

Microsoft Academic Search

Electrode erosion was measured under conditions of practical high current and axial magnetic field (AMF). Arc interruptions were made in a demountable vacuum chamber. Electrode erosion was assessed by weighting. It is shown that the rate of electrode erosion with AMF is 39.8 ?g\\/C and that without AMF it is 1.3 mg\\/C; the anode gains 15 ?g\\/C for diffused arcs

Zou Ji-Yan; Cheng Li-Chun

1989-01-01

220

Vacuum deposition system  

SciTech Connect

The Physics Section vacuum deposition system is available for several types of thin film techniques. This vacuum evaporation system operates in the high vacuum range. The evaporation source is a resistive heating element, either a boat or a filament design. Coating is then line of sight from the source. Substrates to be coated can have a maximum diameter of 17 inches. At this time the variations in the thickness of the coatings can be controlled, by monitor, to within about 100 angstroms. The system diagrams follow the Operation Procedures and the Sample Coating Procedures provided in this document. 3 figs.

Austin, S.; Bark, D.

1990-05-31

221

Li diffusion in zircon  

NASA Astrophysics Data System (ADS)

Diffusion of Li under anhydrous conditions at 1 atm and under fluid-present elevated pressure (1.0-1.2 GPa) conditions has been measured in natural zircon. The source of diffusant for 1-atm experiments was ground natural spodumene, which was sealed under vacuum in silica glass capsules with polished slabs of zircon. An experiment using a Dy-bearing source was also conducted to evaluate possible rate-limiting effects on Li diffusion of slow-diffusing REE+3 that might provide charge balance. Diffusion experiments performed in the presence of H2O-CO2 fluid were run in a piston-cylinder apparatus, using a source consisting of a powdered mixture of spodumene, quartz and zircon with oxalic acid added to produce H2O-CO2 fluid. Nuclear reaction analysis (NRA) with the resonant nuclear reaction 7Li(p,?)8Be was used to measure diffusion profiles for the experiments. The following Arrhenius parameters were obtained for Li diffusion normal to the c-axis over the temperature range 703-1.151C at 1 atm for experiments run with the spodumene source: D_{text{Li}} = 7.17 10^{ - 7} { exp }( - 275 11 {text{kJmol}}^{ - 1} /{text{RT}}){text{m}}2 {text{s}}^{ - 1}. Diffusivities are similar for transport parallel to the c-axis, indicating little anisotropy for Li diffusion in zircon. Similar Li diffusivities were also found for experiments run under fluid-present conditions and for the experiment run with the Dy-bearing source. Li diffusion is considerably faster than diffusion of other cations in zircon, with a smaller activation energy for diffusion. Although Li diffusion in zircon is comparatively rapid, zircons will be moderately retentive of Li signatures at mid-crustal metamorphic temperatures, but they are unlikely to retain this information for geologically significant times under high-grade metamorphism.

Cherniak, D. J.; Watson, E. B.

2010-09-01

222

Collapse of vacuum bubbles in a vacuum  

SciTech Connect

We revisit the dynamics of a false vacuum bubble in a background de Sitter spacetime. We find that there exists a large parameter space that allows the bubble to collapse into a black hole or to form a wormhole. This may have interesting implications for the creation of a baby universe in the laboratory, the string landscape where the bubble nucleation takes place among a plenitude of metastable vacua, and the inflationary physics.

Ng, Kin-Wang; Wang, Shang-Yung [Institute of Physics, Academia Sinica, Taipei, Taiwan 11529 (China); Department of Physics, Tamkang University, Tamsui, Taiwan 25137 (China)

2011-02-15

223

Vacuum Pump Explosion Study.  

National Technical Information Service (NTIS)

An investigation was made into explosions and backfires occurring in vacuum pumps used on Navy oxygen component test stands. Research and testing uncovered several fire and toxicity hazards on these pumps which carry gaseous oxygen flows. Corrective recom...

H. H. Yuen T. D. Weikel

1972-01-01

224

Vacuum Erection Devices  

Microsoft Academic Search

Vacuum erection devices (VEDs) are safe, effective treatments for erectile dysfunction with few side effects. Vacuum negative\\u000a pressure more than 100 mmHg causes a combination of arterial and venous blood to fill the corpora cavernosum. The use of an\\u000a elastic band to trap the blood within the penis allows sufficient rigidity for penetration. Devices approved by the Food and\\u000a Drug

Hunter Wessells

225

Vacuum chamber-free centrifuge with magnetic bearings  

NASA Astrophysics Data System (ADS)

Centrifuges are devices that separate particles of different densities and sizes through the application of a centrifugal force. If a centrifuge could be operated under atmospheric conditions, all vacuum-related components such as the vacuum chamber, vacuum pump, diffusion pump, and sealing could be removed from a conventional centrifuge system. The design and manufacturing procedure for centrifuges could then be greatly simplified to facilitate the production of lightweight centrifuge systems of smaller volume. Furthermore, the maintenance costs incurred owing to wear and tear due to conventional ball bearings would be eliminated. In this study, we describe a novel vacuum chamber-free centrifuge supported by magnetic bearings. We demonstrate the feasibility of the vacuum chamber-free centrifuge by presenting experimental results that verify its high-speed support capability and motoring power capacity.

Park, Cheol Hoon; Kim, Soohyun; Kim, Kyung-Soo

2013-09-01

226

Strength of hydrogen bonds in helices  

Microsoft Academic Search

The intramolecular helix backbone C O - - - H N hydrogen . bonding energies in poly L-alanine a helices have been estimated both in vacuum and in an aqueous environment using the parameter sets of five of the most commonly used force fields for modeling biomolecules, namely AMBER, CHARMM, ECEPP, GROMOS, and OPLS. The relative capabilities of these force

Nidhi Arora; B. Jayaram

1997-01-01

227

Vacuum Technology and Space Simulation  

Microsoft Academic Search

Market: Those involved in vacuum technology and complex vacuum facilities. While specific projects have changed in the 30 years since this book was first published, the need for large complex vacuum facilities has not. And despite new developments in pumping, measurement, and outgassing, this book will remain for many years to come the standard of practical vacuum operation.

D. J. Santeler; D. H. Hokeboer; D. W. Jones; F. Pagano

1993-01-01

228

System Study, Vacuum Sewage Collection.  

National Technical Information Service (NTIS)

An effectiveness/cost comparison was made between gravity sewer systems and vacuum sewer systems for use in Navy advanced bases. The vacuum systems considered were single pipe system where vacuum toilets are connected directly to a vacuum sewer while the ...

R. Waller C. W. Mallory

1971-01-01

229

R&D ERL: Vacuum  

Microsoft Academic Search

The ERL Vacuum systems are depicted in a figure. ERL has eight vacuum volumes with various sets of requirements. A summary of vacuum related requirements is provided in a table. Five of the eight volumes comprise the electron beamline. They are the 5-cell Superconducting RF Cavity, Superconducting e-gun, injection, loop and beam dump. Two vacuum regions are the individual cryostats

M. Mapes; L. Smart; D. Weiss; A. Steszyn; R. Todd

2010-01-01

230

Surface activated bonding of silicon wafers at room temperature  

Microsoft Academic Search

A method to bond silicon wafers directly at room temperature was developed. In this method, surfaces of two silicon samples are activated by argon atom beam etching and brought into contact in a vacuum. By the infrared microscope and KOH etching method, no void at the bonded interface was detected in all the specimens tested. In the tensile test, fracture

H. Takagi; K. Kikuchi; R. Maeda; T. R. Chung; T. Suga

1996-01-01

231

Functionally graded vacuum plasma sprayed and magnetron sputtered tungsten/EUROFER97 interlayers for joints in helium-cooled divertor components  

NASA Astrophysics Data System (ADS)

Two coating technologies, magnetron sputtering and vacuum plasma spraying, have been investigated for their capability in producing functionally graded tungsten/EUROFER97 layers. In a first step, non-graded layers with different mixing ratios were deposited on tungsten substrates and characterized by nanoindentation, macroindentation, X-ray diffraction, transmission, Auger and scanning electron microscopy. The thermal stability of the sprayed layers against heat treatments at 800-1100 C for 60 min was further analyzed. In a second step, the produced functionally graded layers deposited on tungsten substrates were joined to EUROFER97 bulk-material by diffusion bonding. The bonding and the graded joints were microscopically characterized and exposed to thermal cycles between 20 C and 650 C. Results from this study show that both coating technologies are ideal for the synthesis of functionally graded tungsten/EUROFER97 coatings. This is important in providing insights for future development of joints with functionally graded interlayers.

Weber, T.; Stber, M.; Ulrich, S.; Vaen, R.; Basuki, W. W.; Lohmiller, J.; Sittel, W.; Aktaa, J.

2013-05-01

232

Li diffusion in zircon  

Microsoft Academic Search

Diffusion of Li under anhydrous conditions at 1atm and under fluid-present elevated pressure (1.01.2GPa) conditions has\\u000a been measured in natural zircon. The source of diffusant for 1-atm experiments was ground natural spodumene, which was sealed\\u000a under vacuum in silica glass capsules with polished slabs of zircon. An experiment using a Dy-bearing source was also conducted\\u000a to evaluate possible rate-limiting effects

D. J. CherniakE; E. B. Watson

2010-01-01

233

Material processing with vacuum  

NASA Astrophysics Data System (ADS)

The use of controlled atmosphere, especially vacuum, is the integral part of much the materials processing effort involving special materials. The underlying reasons that warrant the presence of vacuum along with high temperatures in these processing schemes are rooted in the thermodynamic properties of the materials particularly in relation to their interaction with gases and other interstitials. Apart from this pressure is also a highly usable process parameter that can be tailored to establish the desired heterogeneous equilibrium, in turn determined by the material to be produced or process to be executed. The range and depth of vacuum metallurgy or vacuum materials processing is vast. The present paper covers a selection of materials processing activities that have been carried out in the Materials Group, BARC involving production of materials, their processing and also basic property determination. A range of vacuum and furnace systems have been used and the practice of designing the process from fundamentals and executing through various batch sizes, and the solution of issues involved are all covered.

Krishnamurthy, N.; Suri, A. K.

2008-05-01

234

ISABELLE vacuum systems  

SciTech Connect

The Intersecting Storage Accelerator (ISABELLE) consists of two rings having a circumference of 3.8 km each. In these rings superconducting magnets, held at 4 K, bend and focus the proton beam which is accelerated up to 400 GeV. Due to very different pressure requirements, ISABELLE has two completely independent vacuum systems. One, which operates at 1 x 10/sup -11/ Torr, provides a very clean environment for the circulating proton beam. Here only ion and titanium sublimation pumps are used to provide the vacuum. The other system maintains superconducting magnet vessels at a pressure below 1 x 10/sup -4/ Torr, since at this pressure the gas conduction becomes negligible. In this so-called insulating vacuum system, turbomolecular pumps pump the inadvertent small helium leaks. Other gases are cryocondensed on the cold surfaces of the cryogenic system. The basic element of ISABELLE known as Full Cell containing 45 meters of beam tube, 8 pumping stations, 8 superconducting magnets and complete instrumentation has been constructed, leak checked and tested. All design parameters have been achieved in both vacuum systems. The two vacuum systems are described with particular emphasis on the influence of superconducting magnets in the selection of materials and UHV components.

Halama, H J

1980-01-01

235

Vacuum Technology in the study of Graphene  

NASA Astrophysics Data System (ADS)

Graphene, an allotrope of carbon is a two-dimensional sheet of covalently bonded carbon atoms that has been attracting great attention in the field of electronics. In a recent review graphene is defined as a flat monolayer of carbon atoms tightly packed into a 2-D honeycomb lattice. A survey has been made of the production processes and instrumentation for characterization of graphene. In the production of graphene, the methods mainly used are Epitaxial growth, oxide reduction, growth from metal-carbon melts, growth from sugar. In the characterization of graphene, the instruments that are mainly used to study the atomic properties, electronic properties, optical properties, spin properties are Scanning Electron Microscopy, Transmission Electron Microscopy, Raman Spectroscopy. In all these instruments high or ultra-high vacuum is required. This paper attempts to correlate vacuum technology in the production and characterization of graphene.

Ghoshal, A. K.; Banerjee, S. N.; Chakraborty, D.

2012-11-01

236

Cladding Metals by Continuous Strip Rolling in Vacuum.  

National Technical Information Service (NTIS)

Equipment and procedure for the continuous roll bonding of metal strips are described. The reels, mill rolls, and furnace were located within a vacuum chamber capable of operation at a residual gas pressure of 0.0001 to 0.00001 torr. Several metals were s...

R. Blickensderfer

1980-01-01

237

Vacuum-assisted delivery.  

PubMed

The literature seems to allow certain general conclusions regarding the choice of instrument for assisted vaginal delivery. Both forceps and vacuum extraction offer certain advantages and drawbacks. Forceps are more difficult to apply, more prone to potentially significant facial injuries, require generally better maternal analgesia, and are associated with increased maternal soft tissue trauma. Vacuum extractors in general are easier to apply, are more likely to result in scalp trauma, and may be associated with increased rates of intracranial trauma. It seems likely that factors particular to each patient may play a significant role in the genesis of delivery associated with maternal and neonatal morbidity. Because of the ease of application, vacuum extractors may be used potentially in circumstances in which forceps assistance would not be attempted, allowing an operator of average experience to perform rotational deliveries. The use of vacuum extraction does appear to decrease the incidence of cesarean section in delivery populations. Given the apparent association between difficult assisted deliveries and increased neonatal morbidity, it is incumbent on the operator to attempt delivery only when vaginal delivery seems to be a safe option. Furthermore, the operator in such circumstances must be willing to reassess the attempt if initial attempts are not met with success. The minimal rates of significant intracranial injury associated with vacuum extraction in randomized studies of the method demonstrate the relative safety of the vacuum extraction when used judiciously. The ultimate choice of the route of delivery and method of assisted delivery should reflect a consideration of the fetal station, presentation, and maternal and fetal circumstances. It is hoped that further investigations in this area may clarify some of the issues discussed in this article. PMID:8665766

Williams, M C

1995-12-01

238

Vacuum pseudoscalar susceptibility  

SciTech Connect

We derive a novel model-independent result for the pion susceptibility in QCD via the isovector-pseudoscalar vacuum polarization. In the neighbourhood of the chiral limit, the pion susceptibility can be expressed as a sum of two independent terms. The first expresses the pion-pole contribution. The second is identical to the vacuum chiral susceptibility, which describes the response of QCD's ground state to a fluctuation in the current-quark mass. In this result one finds a straightforward explanation of a mismatch between extant estimates of the pion susceptibility.

Chang Lei [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Liu Yuxin [Department of Physics, Peking University, Beijing 100871 (China); State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000 (China); Roberts, Craig D. [Department of Physics, Peking University, Beijing 100871 (China); Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Shi Yuanmei [Department of Physics, Nanjing Xiaozhuang College, Nanjing 211171 (China); Sun Weimin; Zong Hongshi [Department of Physics, Nanjing University, Nanjing 210093 (China); Joint Center for Particle, Nuclear Physics and Cosmology, Nanjing 210093 (China)

2010-03-15

239

Vacuum driven accelerated expansion  

NASA Astrophysics Data System (ADS)

It has been shown that an improved estimation of quantum vacuum energy can yield not only acceptable but also experimentally sensible results. The very idea consists in a straightforward extraction of gravitationally interacting part of the full quantum vacuum energy by means of gauge transformations. The implementation of the idea has been performed in the formalism of effective action, in the language of Schwinger's proper time and the Seeley-DeWitt heat kernel expansion, in the background of the Friedmann-Robertson-Walker geometry.

Broda, B.; Bronowski, P.; Ostrowski, M.; Szanecki, M.

2008-11-01

240

Computer design and analysis of vacuum systems  

SciTech Connect

A computer program has been developed for an IBM compatible personal computer to assist in the design and analysis of vacuum systems. The program has a selection of 12 major schematics with several thousand minor variants incorporating diffusion, turbomolecular, cryogenic, ion, mechanical, and sorption pumps as well as circular tubes, bends, valves, traps, and purge gas connections. The gas throughput versus the inlet pressure of the pump is presented on a log--log graphical display. The conductance of each series component is sequentially added to the graph to obtain the net system behavior Q/sub (//sub P//sub )/. The component conductances may be calculated either from the inlet area and the transmission probability or from the tube length and the diameter. The gas-flow calculations are valid for orifices, short tubes, and long tubes throughout the entire pressure range from molecular through viscous to choked and nonchoked exit flows. The roughing-pump and high-vacuum-pump characteristic curves are numerically integrated to provide a graphical presentation of the system pumpdown. Outgassing data for different materials is then combined to produce a graph of the net system ''outgassing pressure.'' Computer routines are provided for differentiating a real pumpdown curve for system analysis. The computer program is included with the American Vacuum Society course, ''Advanced Vacuum System Design and Analysis,'' or it may be purchased from Process Applications, Inc.

Santeler, D.J.

1987-07-01

241

Room-Temperature Wafer Bonding of Silicon and Lithium Niobate by Means of Argon-Beam Surface Activation  

Microsoft Academic Search

We have developed a method to bond silicon and piezoelectric ceramics wafers at room temperature. In the method, the wafers are bonded in vacuum after sputter etching by argon beam. It is not necessary to apply high pressure to force two specimens together in the bonding process. A 3-inch single crystal lithium niobate wafers was successfully bonded to a 4-inch

H. Takagi; R. Maeda; T. Suga

2002-01-01

242

Fluxless flip chip bonding processes and aerial fluxless bonding technology  

NASA Astrophysics Data System (ADS)

New fluxless flip chip processes of Sn-rich non-eutectic Au-Sn solder bumps were developed using vacuum deposition and electroplating technique. It is believed that this is the first report that non-eutectic Au-Sn flip chip solder bonding is achieved without the use of flux. In order to make 200mum diameter and 10mum thick Au-Sn solder bump 0.03mum of Cr, 10mum of Sn and 0.3mum of Au were vacuum deposited on the Si wafer through the high carbon steal stencil mask. Nearly void-free solder bumps with small grains of AuSn4 intermetallic compound were achieved. The re-melting temperature of solder bumps was measured to be 220C. In the second part, first, the fluxless bonding process was performed in hydrogen environment with electroplated 4 mm x 4mm Au-Sn multi-layer chips if electroplating technique is compatible with our process. High quality and nearly void free solder joint was successfully achieved with this new process. After proving compatibility of the process, tall electroplated Sn/Au bumps (50 mum) were produced by photolithography method using Su-8 photoresist. The bumps in the chip were flip chip bonded to the borosilicate glass wafer coated with Cr (0.03 mum) and Au (0.05 mum) pads without using any flux. Fluxless and lead-free bonding technology in air ambient based on non eutectic 5 at. % Au-95 at. % Sn and eutectic 57 at. %Sn-43 at. % Bi with Au capping layer have been developed and studied. To understand the fluxless bonding principles in air ambient, phase formation mechanism of Au-Sn intermetallics embedded in Bi matrix has been postulated. The Au-Sn intermetallic-capping layer covers most outer surface of the samples and inhibits formation of oxide layer due to the minimizing exposure of (beta-Sn) phase to the air. In conclusion, new-lead free and fluxless bonding processes for flip chip packages were developed. In this work, Sn-rich Au-Sn flip chip solder bumps using vacuum deposition and electroplating process were successfully produced. It is believed that the processes presented in this dissertation offer additional process windows to lead-free flip chip technology and have various applications where flux cannot be used such as optoelectronic devices, biomedical devices, and MEMS (MicroElectroMechanical Systems) devices. Aerial fluxless bonding technology was also reported for the first time in my knowledge. Although conventional fluxless bonding processes has been successfully adopted in many application, the need of specific ambient gases such as forming gas or hydrogen is not compatible with pick-and-place bonding machines in the electronic industry. Thus, fluxless bonding technology in air ambient could provide a valuable and economical alternative way to the electronic and photonic packaging industries. (Abstract shortened by UMI.)

Kim, Dongwook

243

Quantum Vacuum Pathway Theory  

Microsoft Academic Search

It is theorized that the quantum vacuum is a random electromagnetic field that permeates the universe. It will be shown that acceleration between a quark and a random electromagnetic energy field is an analog of the reaction between a charge moving at constant velocity with respect to an organized electromagnetic field. The difference is that with a quark any natural

Eric John Habegger

2005-01-01

244

Vacuum Kundt waves  

NASA Astrophysics Data System (ADS)

We discuss the invariant classification of vacuum Kundt waves using the Cartan-Karlhede algorithm and determine the upper bound on the number of iterations of the Karlhede algorithm to classify the vacuum Kundt waves (Collins (1991 Class. Quantum Grav. 8 1859-69), Machado Ramos (1996 Class. Quantum Grav. 13 1589)). By choosing a particular coordinate system we partially construct the canonical coframe used in the classification to study the functional dependence of the invariants arising at each iteration of the algorithm. We provide a new upper bound, q ? 4, and show that this bound is sharp by analyzing the subclass of Kundt waves with invariant count beginning with (0, 1,) to show that the class with invariant count (0, 1, 3, 4, 4) exists. This class of vacuum Kundt waves is shown to be unique as the only set of metrics requiring the fourth covariant derivatives of the curvature. We conclude with an invariant classification of the vacuum Kundt waves using a suite of invariants.

McNutt, David; Milson, Robert; Coley, Alan

2013-03-01

245

Electrospray deposition in vacuum  

Microsoft Academic Search

We have used the established technique of electrospray in developing a portable vacuum electrospray system which can deposit, in vacuo, dissolved molecules onto a sample which may then be analysed by UHV techniques. As an initial test of the system we have analysed silicon samples with an electrosprayed layer of poly(ethylene) oxide (PEO) using atomic force microscopy (AFM). The polymer

Janine C. Swarbrick; J. Ben Taylor; James N. O'Shea

2006-01-01

246

Vacuum System at IUAC  

NASA Astrophysics Data System (ADS)

Vacuum technology is an integral part of any accelerator system. At IUAC we have a 15UD PELLETRON, superconduting LINAC, Low Energy Ion beam Facility and a 1.7MV pelletron. Vacuum requirement in these accelerators is ~10-8 torr. Various types of Vacuum pump are used in different zones of the accelerators depending on load. Since the whole accelerator is quite long, distributed pumps are placed in different sections as per load. In ion sources displacement type pump viz turbo-pumps are usually used as the gas load is quite high. In other parts of the accelerator combination of getter and ion pumps are used. It is very much necessary to isolate different sections for maintenance purpose. Proper valves are used to isolate the sections and to avoid vacuum accidents proper interlock system is introduced. If air goes in some sections accidentally, valves will close automatically to protect other sections. The talk will cover different types of pumps and interlock used in accelerators at IUAC.

Mandal, A.

2012-11-01

247

Ultra high vacuum technology  

Microsoft Academic Search

A short introduction for some basic facts and equations. Subsquently, discussion about: Building blocks of an ultrahigh vacuum system - Various types of pumps required to reach uhv and methods to reduce these effects - Outgassing phenomena induced by the presence of a particle beam and the most common methods to reduce these effects It will be given some practical

Oswald Grbner

2001-01-01

248

Langmuir vacuum and superconductivity  

NASA Astrophysics Data System (ADS)

It is shown that, in the "jelly" model of cold electron-ion plasma, the interaction between electrons and the quantum electromagnetic vacuum of Langmuir waves involves plasma superconductivity with an energy gap proportional to the energy of the Langmuir quantum.

Veklenko, B. A.

2012-06-01

249

Vacuum configurations for superstrings  

Microsoft Academic Search

We study candidate vacuum configurations in ten-dimensional O(32) and E8 E8 supergravity and superstring theory that have unbroken N = 1 supersymmetry in four dimensions. This condition permits only a few possibilities, all of which have vanishing cosmological constant. In the E8 E8 case, one of these possibilities leads to a model that in four dimensions has an

P. Candelas; Gary T. Horowitz; Andrew Strominger; Edward Witten

1985-01-01

250

Large Rotary Vacuum Seal  

Microsoft Academic Search

A seal is described which permits rotation of large circular sections or ; ports in the walls of a vacuum chamber. The seal is an unlubricated Tec-Ring (a ; Teflon O-ring with a core of rubber), and the friction is low even at large ; diameters. The behavior of such a seal is compared with that of a lubricated ;

D. E. Armstrong; Normand Blais

1963-01-01

251

Vacuum in Multicolor QCD.  

National Technical Information Service (NTIS)

It is assumed that among asymptotic solutions to the Makeenko-Migdal equation of the form exp(-aA - bL) (A = area, L = perimeter, A and L are large) there is also the solution which has asymptotic freedom at small distances. It is then shown that vacuum i...

P. Olesen

1980-01-01

252

Type D Vacuum Metrics  

Microsoft Academic Search

Using the Newman-Penrose formalism, the vacuum field equations are solved for Petrov type D. An exhaustive set of ten metrics is obtained, including among them a new rotating solution closely related to the Ehlers-Kundt ``C'' metric. They all possess at least two Killing vectors and depend only on a small number of arbitrary constants.

William Kinnersley

1969-01-01

253

Vacuum arc recovery phenomena  

Microsoft Academic Search

The present experimental and theoretical study has been designed to uncover the mechanism underlying the rapid recovery of electrical strength of a short vacuum gap after arcing. In the experiment the contacts were of gas-free silver and the contact area and gap length were varied. Recovery strength was measured following the forced extinction of a 250 amp arc in 0.5

J. A. Rich; G. A. Farrall

1964-01-01

254

Various unique vacuum holders  

SciTech Connect

Glassblowers use vacuum holding devices to support a flat plate in the glassflowing lathe to seal onto the end of, or inside of, a glass cylinder. Glassblowing blowhose swivels tend to leak; a rotating union from the hydraulics industry is better. Various graphite holder designs are described.

Gregar, J.S.

1992-12-01

255

Cryogenic vacuum pump design  

Microsoft Academic Search

This paper is a review of the problems and tradeoffs involved in cryogenic vacuum pump analysis, design and manufacture. Particular attention is paid to the several issues unique to cryopumps, e.g., radiation loading, adsorption of noncondensible gases, and regeneration. A general algorithm for cryopump design is also proposed.

A. J. Bartlett; P. A. Lessard

1984-01-01

256

The LHC Vacuum System  

Microsoft Academic Search

The Large Hadron Collider (LHC) at CERN, involves two proton storage rings with colliding beams of 7 TeV. The machine will be housed in the existing LEP tunnel and requires 16 m long superconducting b ending magnets. The vacuum chamber will be the inner wall of the cryostat and hence at the temperature of the magnet cold bore, i.e. at

Oswald Grbner

1998-01-01

257

Electtra vacuum system  

Microsoft Academic Search

Elettra is a third-generation synchrotron light source which is being built especially for the use of high brilliance radiation from insertion devices and bending magnets. The UHV conditions in a storage ring lead to a longer beam lifetime-one of the most important criterion. The Elettra vacuum system presents some peculiarities which cannot be found in any already existing machine. The

M. Bernardini; F. Daclon; F. Giacuzzo; R. Kersevan; J. Miertusova; F. Pradal

1993-01-01

258

Vacuum insulator coating development  

Microsoft Academic Search

The authors discuss the electrical and mechanical requirements for vacuum insulators in high peak power generators. To increase the lifetime of these insulators, they have developed a coating called Dendresist. This coating has extended the insulator lifetime on the PITHON, DM2, CASINO, and Double-EAGLE pulsed power generators. They describe its development, and compare its electrical and mechanical strength to that

I. S. Roth; P. S. Sincerny; L. Mandelcorn; M. Mendelsohn; D. Smith; T. G. Engel; L. Schlitt; C. M. Cooke

1997-01-01

259

RF Vacuum Electronics.  

National Technical Information Service (NTIS)

We summarize our second quarter progress and discuss third quarter plans for the development of an edge emitter based vacuum triode with performance goals of 10 microA/micrometer emission current density at less than 250V and which can be modulated at1 GH...

D. Arch J. Holmen P. Bauhahn T. Akinwande T. Ohnstein

1992-01-01

260

Interpreting cosmological vacuum decay  

SciTech Connect

The cosmological vacuum decay scenario recently proposed by Wang and Meng [Classical Quantum Gravity 22, 283 (2005)] is rediscussed. From thermodynamic arguments it is found that the {epsilon} parameter quantifying the vacuum decay rate must be positive in the presence of particle creation. If there is no particle creation, the proper mass of Cold Dark Matter (CDM) particles is necessarily a time-dependent quantity, scaling as m(t)=m{sub o}a(t){sup {epsilon}}. By considering the presence of baryons in the cosmological scenario, it is also shown that their dynamic effect is to alter the transition redshift z{sub *} (the redshift at which the Universe switches from decelerating to accelerating expansion), predicting values of z{sub *} compatible with current estimates based on type Ia supernova. In order to constrain the {omega}{sub m}-{epsilon} plane, a joint statistical analysis involving the current supernovae observations, gas mass fraction measurements in galaxy clusters and CMB data is performed. At 95% c.l. it is found that the vacuum decay rate parameter lies on the interval {epsilon}=0.06{+-}0.10. The possibility of a vacuum decay into photons is also analyzed. In this case, the energy density of the radiation fluid scales as {rho}{sub r}={rho}{sub ro}a{sup -4+{epsilon}}, and its temperature evolution law obeys T(t)=T{sub o}a(t){sup {epsilon}}{sup /4-1}.

Alcaniz, J.S.; Lima, J.A.S. [Departamento de Astronomia, Observatorio Nacional, 20921-400 Rio de Janeiro - RJ (Brazil); Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, USP, 05508-900 Sao Paulo, SP (Brazil)

2005-09-15

261

Triggered vacuum gaps  

Microsoft Academic Search

Characteristics of a sealed vacuum gap are described and the difficulties encountered in applying this gap as an overvoltage protection device are discussed. It is shown how these difficulties can be ameliorated by the use of gas-free electrode materials and by triggering the gap when breakdown is required. Several methods of triggering are discussed and some practical triggering devices are

J. M. Lafferty

1966-01-01

262

ISAC target vacuum system  

SciTech Connect

The Isotope Separator and Accelerator (ISAC) facility at TRIUMF has been in full operation since 1999. The ISAC east and west targets use proton beam from the cyclotron to produce various radioactive isotopes, which are then ionized and extracted. The ions are then passed through the mass separator and selected ions are transferred to the low energy experiments or injected into a radio frequency quadrupole accelerator. The accompanying radioactive contamination from the production of radioactive ions requires a complex vacuum system. The main target vacuum space consists of two semiseparate (primary and secondary) volumes pumped by turbo-molecular pumps. The primary volume uses four pumps while the secondary volume uses two pumps. Two hermetic rotary vane pumps are used as backing pumps. The nominal vacuum in both volumes is about 1.33x10{sup -4} Pa (1.0x10{sup -6} Torr). The pressure is monitored by two cold cathode and two hot filament ion gauges. The cold cathode gauges are used to interlock the system, which is critical during the bake out of the target and beam production. The exhaust gas from the vacuum pumps can be radioactive. Three gas storage tanks (decay tanks) are used for temporary storage of the radioactive exhaust and its controlled release to the atmosphere. Gas-species insensitive membrane gauges are used for monitoring the pressure in the storage tanks. This article describes the details of the ISAC target vacuum system as well as some procedures related to the handling of the exhaust gas with traces of radioactive contamination produced by the targets.

Yosifov, Dimo; Sekachev, Igor [TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, British Columbia V6T 2A3 (Canada)

2006-07-15

263

Vacuum requirements for RHIC  

SciTech Connect

In this note the lifetime due to inelastic scattering of beam and residual gas ions is calculated in units of pressure (Torr). In addition, the transverse emittance growth due to elastic scattering is expressed in units of pressure. The definition of inelastic scattering includes both capture of an electron from a residual gas ion and central nuclear collisions between beam ion and gas atom. Emittance growth via elastic scattering is a simple consequence of multiple Coulomb scattering. Is is important to note that in an accelerator only the density of residual gas atoms is relevant to the machine operation. The measure of this density is the vacuum gauge, where this gauge is calibrated in pressure units at some known temperature T{sub G}. The vacuum unit or pressure is of course temperature dependent, and thus when quoting vacuum requirements for RHIC it is vital to state the temperature at which the pressure is computed. It might be necessary to scale any computed gas density to the pressure appropriate for the measurement with the vacuum gauge. Typically, the vacuum gauge operates at room temperature {approximately}300{degree}K. An explanation on how to rescale pressure as a function of temperature is given in the text. This note assumes the residual gas density in the so-called warm section (300{degree}K) of RHIC to be composed of 90% H{sub 2}, 5% CH{sub 4} and 5% CO. The gas in the cold section (5{degree}K) is assumed to be 100% He. The beam ions are taken to be {sup 197}Au{sup 79+}.

Rhoades-Brown, M.J.; Harrison, M.

1991-12-01

264

Demonstrations with a Vacuum: Old Demonstrations for New Vacuum Pumps.  

ERIC Educational Resources Information Center

|Explains mechanisms of 19th-century vacuum pumps. Describes demonstrations using the pump including guinea and feather tube, aurora tube, electric egg, Gassiots cascade, air mill, bell in vacuum, density and buoyancy of air, fountain in vacuum, mercury shower, palm and bladder glasses, Bacchus demonstration, pneumatic man-lifter, and Magdeburg

Greenslade, Thomas B., Jr.

1989-01-01

265

Demonstrations with a Vacuum: Old Demonstrations for New Vacuum Pumps.  

ERIC Educational Resources Information Center

Explains mechanisms of 19th-century vacuum pumps. Describes demonstrations using the pump including guinea and feather tube, aurora tube, electric egg, Gassiots cascade, air mill, bell in vacuum, density and buoyancy of air, fountain in vacuum, mercury shower, palm and bladder glasses, Bacchus demonstration, pneumatic man-lifter, and Magdeburg

Greenslade, Thomas B., Jr.

1989-01-01

266

Tritium handling in vacuum systems  

SciTech Connect

This report provides a course in Tritium handling in vacuum systems. Topics presented are: Properties of Tritium; Tritium compatibility of materials; Tritium-compatible vacuum equipment; and Tritium waste treatment.

Gill, J.T. [Monsanto Research Corp., Miamisburg, OH (United States). Mound Facility; Coffin, D.O. [Los Alamos National Lab., NM (United States)

1986-10-01

267

Wafer Direct Bonding: From Advanced Substrate Engineering to Future Applications in Micro\\/Nanoelectronics  

Microsoft Academic Search

Wafer direct bonding refers to the process of adhesion of two flat mirror-polished wafers without using any intermediate gluing layers in ambient air or vacuum at room temperature. The adhesion of the two wafers occurs due to attractive long range van der Waals or hydrogen bonding forces. At room temperature the bonding energy of the interface is low and higher

Silke H. Christiansen; Rajendra Singh; Ulrich Gosele

2006-01-01

268

Numerical simulation of high-current vacuum arcs with an external axial magnetic field  

Microsoft Academic Search

Numerical simulations are presented for physical behavior and heat flux to the anode of high-current diffuse of arcs as found in vacuum interrupters. The magnetohydrodynamic approach is applied. Of importance is the consideration of energy balance. Heat flux densities to the anode are predicted in the right order of magnitude and essential physical details of the high-current vacuum arc are

Ekkehard Schade; Dmitry Leonidovich Shmelev

2003-01-01

269

Vacuum Mechanisms of Nanoscale Precision  

Microsoft Academic Search

The principles of design of vacuum mechanims of nanoscale precision are presented. Physical basics of the mechanisms nanoscale\\u000a precision are discussed. Vacuum multicoordinate drives and manipulators are also shown.\\u000a \\u000a The analysis of vacuum technological equipment and vacuum research equipment shows that the most strict requirements for the\\u000a object transference are in electron beam micro lithography equipment. For example, electron beam

E. A. Deulin; V. P. Mikhailov; Yu. V. Panfilov; R. A. Nevshupa

270

A radiation hard vacuum switch  

DOEpatents

A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

Boettcher, G.E.

1988-07-19

271

REE Diffusion in Olivine  

NASA Astrophysics Data System (ADS)

Diffusion of rare earth elements has been characterized in synthetic forsterite and natural olivine (Fo90) under dry conditions. The source of diffusant was a mixture of REE aluminate garnet powder and synthetic forsterite powder in 3:1 proportions. Experiments were prepared by enclosing source material and polished forsterite in platinum capsules, which were crimped shut. For experiments on natural olivine, samples were placed with the source in AgPd capsules, which were sealed under vacuum in silica glass ampoules with a solid buffer to buffer at NNO. Prepared capsules were then annealed in 1 atm furnaces for times ranging from an hour to several weeks, at temperatures from 850 to 1300C. REE distributions in the olivine were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for Dy diffusion in forsterite: D = 2.3x10-10 exp(-273 kJ mol-1/RT) m2sec-1. Diffusivities of Yb and La in forsterite appear similar, and preliminary results for Dy diffusion in natural olivine also suggest similar diffusivities. REE diffusivities in forsterite are about an order of magnitude faster than those of REE+3 in enstatite (Cherniak and Liang, 2007). However, if the Arrhenius relation above is extrapolated up to 1450C, it yields diffusivities about three orders of magnitude smaller than those determined for REE diffusion in olivine by Spandler et al. (2007). Work is currently underway in further characterizing diffusion in Fe-bearing olivine. If an Arrhenius relation similar to that for forsterite is found to apply, timescales for preservation of REE signatures in olivine-hosted melt inclusions may be relatively long. Cherniak and Liang (2007) GCA 71, 1324-1340; Spandler et al. (2007) Nature 447, 303-306.

Cherniak, D. J.

2007-12-01

272

Basics of Fidelity Bonding.  

ERIC Educational Resources Information Center

|Fidelity bonds are important for an agency to hold to protect itself against any financial loss that can result from dishonest acts by its employees. Three types of fidelity bonds are available to an agency: (1) public official bonds; (2) dishonesty bonds; and (3) faithful performance bonds. Public official bonds are required by state law to be

Kahn, Steven P.

273

Cleaning of a Thermal Vacuum Chamber with Shrouds in Place.  

National Technical Information Service (NTIS)

In February, 1991, a failure of a rotary booster pump caused the diffusion pumps to backstream into a 10 ft x 15 ft thermal vacuum chamber. Concerns existed about the difficulty of removing and reinstalling the shrouds without causing leaks. The time requ...

W. R. Bond

1992-01-01

274

VACUUM OSMOTIC DEHYDRATION OF FRUITS  

Microsoft Academic Search

Vacuum osmotic dehydration leads a special behaviour of mass transfer in fruit-sugar soluion system.Vacuum treatments intensify the capillary flow function and increase water transfer ratio.but have no significant influence on sugar uptake.Fruits such as pineapples which have higher porosity are more suitable to be treated under vacuum during the osmotic dehydration.

Xian Quan Shi; Pedro Fito Maupoey

1993-01-01

275

Surge-damping vacuum valve  

DOEpatents

A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

Bullock, Jack C. (Pleasanton, CA); Kelly, Benjamin E. (Tracy, CA)

1980-01-01

276

Insertion device vacuum system designs  

SciTech Connect

Synchrotron light source insertion device vacuum systems now in operation and systems proposed for the future are reviewed. An overview of insertion devices is given and four generic vacuum chamber designs, transition section design and pumping considerations are discussed. Examples of vacuum chamber systems are presented.

Hoyer, E.

1988-05-01

277

Challenges For Vacuum Interrupter Design  

Microsoft Academic Search

Vacuum interrupters form the key component of a medium voltage (MV) vacuum switchgear design. Vacuum interrupter technology is now well established and key manufacturers across the world are routinely producing interrupters for ratings up to 52kVrms. Manufacturers have focused on reducing the cost of interrupter components by adapting to more efficient contact geometry, improved contact materials, finite element modelling for

R. Parashar; A. Baker; A. Sitzia

2006-01-01

278

Vacuum chuck having vacuum-nipples wafer support  

US Patent & Trademark Office Database

A vacuum chuck is disclosed which has nipples as support structure and for vacuum delivery. In the preferred embodiment, two types of nipples are used: "plain" nipples which provide only support and vacuum nipples which provide support and deliver vacuum to retain the wafer on the chuck. The contact surface of the plain nipples is made smaller than that of the vacuum nipples. The chuck is secured to a stage using special supports which have limited flexibility in two axis with respect to the chuck, so as to prevent warping the chuck. Special vacuum nipples are disclosed which do not deliver vacuum unless the wafer exerts sufficient predetermined pressure on the nipple. The chuck is designed to hold both 200 mm and 300 mm wafers.

2001-07-10

279

Vacuum tool manipulator  

DOEpatents

Apparatus for manipulating a vacuum hose in a reactor vessel comprises a housing with two opposing openings, an arm carried by the housing and deployable from a stowed position essentially completely within the housing to an extended position where the arm extends through the two openings in a generally horizontal position. The arm preferably has a two-fingered gripping device for gripping the vacuum hose but may carry a different end effector such as a grinding wheel. The fingers are opened and closed by one air cylinder. A second air cylinder extends the device. A third air cylinder within the housing pivotally pulls the opposing end of the arm into the housing via a pivoting member pivotally connected between the third air cylinder shaft and the arm. 6 figures.

Zollinger, W.T.

1993-11-23

280

Vacuum tool manipulator  

DOEpatents

Apparatus for manipulating a vacuum hose in a reactor vessel comprises a housing with two opposing openings, an arm carried by the housing and deployable from a stowed position essentially completely within the housing to an extended position where the arm extends through the two openings in a generally horizontal position. The arm preferably has a two-fingered gripping device for gripping the vacuum hose but may carry a different end effector such as a grinding wheel. The fingers are opened and closed by one air cylinder. A second air cylinder extends the device. A third air cylinder within the housing pivotally pulls the opposing end of the arm into the housing via a pivoting member pivotally connected between the third air cylinder shaft and the arm.

Zollinger, William T. (3927 Almon Dr., Martinez, GA 30907)

1993-01-01

281

Dry vacuum pumps  

NASA Astrophysics Data System (ADS)

For decades and for ultimate pressure below 1 mbar, oil-sealed Rotary Vane Pumps have been the most popular solution for a wide range of vacuum applications. In the late 80ies, Semiconductor Industry has initiated the development of the first dry roughing pumps. Today SC applications are only using dry pumps and dry pumping packages. Since that time, pumps manufacturers have developed dry vacuum pumps technologies in order to make them attractive for other applications. The trend to replace lubricated pumps by dry pumps is now spreading over many other market segments. For the Semiconductor Industry, it has been quite easy to understand the benefits of dry pumps, in terms of Cost of Ownership, process contamination and up-time. In this paper, Technology of Dry pumps, its application in R&D/industries, merits over conventional pumps and future growth scope will be discussed.

Sibuet, R.

2008-05-01

282

Edison's vacuum technology patents  

NASA Astrophysics Data System (ADS)

During 1879 Thomas Edison's Menlo Park, New Jersey laboratory developed the means to evacuate glass lamp globes to less than a mTorr in 20 min and in mid-1880 began production of carbon-filament incandescent lamps. Among Edison's nearly 1100 U.S. patents are five for vacuum pump improvements, and at least eight others that are vacuum-related; all applied for between 1880 and 1886. Inspired by an 1878 article by De La Rue and Mller [Philos. Trans. R. Soc. London, Ser. A 169, 155 (1878)] on studies of glow discharges, Edison devised a combination pump using the Geissler pump as a rough pump and the Sprengel pump for continuous exhaustion. Edison's patents described means to control the mercury flow and automate the delivery of the mercury to banks of up to a hundred pumps. Other patents described various means to remove residual gases during lamp processing.

Waits, Robert K.

2003-07-01

283

An automated vacuum system  

SciTech Connect

Software tools available with the Ground Test Accelerator (GTA) control system provide the capability to express a control problem as a finite state machine. System states and transitions are expressed in terms of accelerator parameters and actions are taken based on state transitions. This is particularly useful for sequencing operations which are modal in nature or are unwieldy when implemented with conventional programming. State diagrams are automatically translated into code which is executed by the control system. These tools have been applied to the vacuum system for the GTA accelerator to implement automatic sequencing of operations. With a single request, the operator may initiate a complete pump-down sequence. He can monitor the progress and is notified if an anomaly occurs requiring intervention. The operator is not required to have detailed knowledge of the vacuum system and is protected from taking inappropriate actions. 1 ref., 6 figs.

Atkins, W.H. (Oak Ridge National Lab., TN (USA)); Vaughn, G.D. (Los Alamos National Lab., NM (USA)); Bridgman, C. (Grumman Corp., Bethpage, NY (USA))

1991-01-01

284

Vacuum actuated gas delivery  

Microsoft Academic Search

The new Vacuum Actuated Cylinder (VACTM) gas source provides sub-atmospheric pressure delivery of the metal fluorides commonly used as dopants for ion implant. The VAC gas source is a mechanical system based on an embedded pressure control device located inside the cylinder. A pre-set sub-atmospheric pressure must be achieved in the delivery manifold before flow is permitted from the cylinder.

W. K. Olander; M. Donatucci; J. Mayer; L. Wang

2000-01-01

285

LHC vacuum system  

Microsoft Academic Search

The Large Hadron Collider (LHC) project, now in the advanced construction phase at CERN, comprises two proton storage rings with colliding beams of 7-TeV energy. The machine is housed in the existing LEP tunnel with a circumference of 26.7 km and requires a bending magnetic field of 8.4 T with 14-m long superconducting magnets. The beam vacuum chambers comprise the

Oswald Grbner

1999-01-01

286

The LHC vacuum system  

Microsoft Academic Search

The Large Hadron Collider (LHC) at CERN, involves two proton storage rings with colliding beams of 7 TeV. The machine will be housed in the existing LEP tunnel and requires 16 m long superconducting bending magnets. The vacuum chamber will be the inner wall of the cryostat and hence at the temperature of the magnet cold bore, i.e. at 1.9

O. Grbner

1997-01-01

287

The ITER vacuum systems  

NASA Astrophysics Data System (ADS)

ITER is a large vacuum facility which comprises many service, diagnostic and monitoring vacuum sub-systems as well as three large cryogenic pumping systems for evacuation and maintenance of the required pressure levels. Control of the gas throughput is one of the key issues affecting the performance and achievable burn time of a fusion reactor. The main pumping systems are the torus exhaust pumping, the cryopumps for the neutral beam injection systems for plasma heating, and the cryopumps for the ITER cryostat. All customized cryosorption pumps are force-cooled with supercritical helium and share a similar modular design of cryosorption pumping panels. For regeneration of the cryopumps as well as for roughing down the system volumes prior to operation, four identical sets of forepump trains are used. This paper will focus on the areas of the ITER vacuum systems which require customized developments and cannot rely on commercial solutions. The complex pumps have been tailored for the very specific applications and requirements at ITER, especially characterised by the need to be tritium compatible. An outline of the development path which was needed to come up with a sound design for the ITER cryopumps is given. The way of development is culminating in the manufacturing of 1:1 scale prototypes, which will be extensively tested in dedicated test facilities to ensure compatibility with all design requirements.

Day, C.; Murdoch, D.

2008-05-01

288

Multiple station thermal diffusivity instrument  

SciTech Connect

A multiple furnace laser flash thermal diffusivity system has been developed. The system is equipped with a movable Nd:Glass laser unit, two IR detectors and furnaces for precise measurements of thermal diffusivity over the temperature range from {minus}150{degree}C to 2500{degree}C. All furnaces can operate in vacuum and inert gas; the environmental effects furnace also supports oxidizing and reducing environments. To increase testing speed the graphite and aluminum furnaces are both equipped with six-sample carousels. Thermal diffusivity measurements of three standard reference materials show excellent results over the entire temperature range.

Wang, H.; Dinwiddie, R.B. [Oak Ridge National Lab., TN (United States); Gaal, P.S. [Anter Corp., Pittsburgh (United States)

1995-12-31

289

The Diffusion Process  

NSDL National Science Digital Library

This website includes an animation which illustrates the diffusion process. The two models that have been developed to explain the mechanism for the diffusion of dopants into silicon are the Vacancy model and the Interstitial model. It is the different bonding characteristics of the dopants with silicon that determine the diffusion mechanism. Although each model is based on these differences, they are not mutually exclusive. Objective: Explain the difference between the Vacancy and Interstitial diffusion models. You can find this animation under the heading "Process & Equipment III." This simulation is from Module 019 of the Process & Equipment III Cluster of the MATEC Module Library (MML). To view other clusters or for more information about the MML visit http://matec.org/ps/library3/process_I.shtmlKey

2012-11-22

290

Understand vacuum-system fundamentals  

SciTech Connect

Crude vacuum unit heavy vacuum gas-oil (HVGO) yield is significantly impacted by ejector-system performance, especially at conditions below 20 mmHg absolute pressure. A deepcut vacuum unit, to reliably meet the yields, calls for proper design of all the major pieces of equipment. Ejector-system performance at deepcut vacuum column pressures may be independently or concurrently affected by: atmospheric column overflash, stripper performance or cutpoint; vacuum column top temperature and heat balance; light vacuum gas-oil (LVGO) pumparound entrainment to the ejector system; cooling-water temperature; motive steam pressure; non-condensible loading, either air leakage or cracked light-end hydrocarbons; condensible hydrocarbons; intercondenser or aftercondenser fouling ejector internal erosion or product build-up; and system vent back pressure. The paper discusses gas-oil yields; ejector-system fundamentals; condensers; vacuum-system troubleshooting; process operations; and a case study of deepcut operations.

Martin, G.R. (Process Consulting Services, Grapevine, TX (United States)); Lines, J.R. (Graham Manufacturing Co., Inc., Batavia, NY (United States)); Golden, S.W. (Glitsch, Inc., Dallas, TX (United States))

1994-10-01

291

A vacuum-driven peristaltic micropump with valved actuation chambers  

NASA Astrophysics Data System (ADS)

This paper presents a simple peristaltic micropump design incorporated with valved actuation chambers and propelled by a pulsed vacuum source. The vacuum-driven peristaltic micropump offers high pumping rates, low backflow, appreciable tolerance to air bubbles, and minimal destruction to fluid contents. The pumping device, fabricated by laser micromachining and plasma bonding of three polydimethylsiloxane (PDMS) layers, includes a pneumatic network, actuation membranes, and microfluidic channels. As the key to peristaltic motion, the sequential deflection of the elastic membranes is achieved by periodic pressure waveforms (negative) traveling through the pneumatic network, provided by a vacuum source regulated by an electromagnetic valve. This configuration eliminates the complicated control logic typically required in peristaltic motion. Importantly, the valved actuation chambers substantially reduce backflow and improve the pumping rates. In addition, the pneumatic network with negative pressure provides a means to effectively remove air bubbles present in the microflow through the gas-permeable PDMS membrane, which can be highly desired in handling complex fluidic samples. Experimental characterization of the micropump performance has been conducted by controlling the resistance of the pneumatic network, the number of normally closed valves, the vacuum pressure, and the frequency of pressure pulses. A maximal flow rate of 600 L min-1 has been optimized at the pulsed vacuum frequency of 30 Hz with a vacuum pressure of 50 kPa, which is comparable to that of compressed air-actuated peristaltic micropumps.

Cui, Jianguo; Pan, Tingrui

2011-06-01

292

Semiconductor wafer bonding  

Microsoft Academic Search

When mirror-polished, flat, and clean wafers are brought into contact, they are locally attracted to each other and adhere or bond. This phenomenon is known as semiconductor wafer bonding. Different adhesion forces (van der Waals forces, hydrogen bonding) are the reason for the bonding effect at room temperature. The different bonding mechanisms acting in dependence on the surface conditions (hydrophilic,

M. Reiche

2006-01-01

293

Energetic Deposition in Vacuum  

SciTech Connect

In hoping to improve Niobium deposition on Copper cavity, a vacuum deposition system has been built to test the idea of Nb energetic condensation on copper substrate. The system directly uses microwave power to create the pure Nb plasma, which can be used to extract energetic Nb ion flux to do direct deposition on copper substrate. In this paper, we briefly describe the system, discuss the potential benefit of this technique and report the initial result of Nb plasma creation and Niobium thin film deposition.

G. Wu; L. Phillips; R. Sundelin; T. Goodman

2001-09-01

294

Fabrication of Germanium-on-Insulator by low temperature direct wafer bonding  

Microsoft Academic Search

A Germanium-on-Insulator (GeOI) wafer was fabricated using low temperature direct wafer bonding method. A hydrogen implanted Ge donor wafer was bonded to a thermally oxided Si handle wafer with in-situ oxygen radical activation before bonding in a vacuum chamber. Ex-situ anneals were use to enhance the bond strength or exfoliate the implanted Ge wafer. The insight into the exfoliation mechanism

Ran Yu; Ki Yeol Byun; I. Ferain; D. Angot; R. Morrison; C. Colinge

2010-01-01

295

Flash vacuum pyrolysis of lignin model compounds  

SciTech Connect

Despite the extensive research into the pyrolysis of lignin, the underlying chemical reactions that lead to product formation are poorly understood. Detailed mechanistic studies on the pyrolysis of biomass and lignin under conditions relevant to current process conditions could provide insight into utilizing this renewable resource for the production of chemicals and fuel. Currently, flash or fast pyrolysis is the most promising process to maximize the yields of liquid products (up to 80 wt %) from biomass by rapidly heating the substrate to moderate temperatures, typically 500{degrees}C, for short residence times, typically less than two seconds. To provide mechanistic insight into the primary reaction pathways under process relevant conditions, we are investigating the flash vacuum pyrolysis (FVP) of lignin model compounds that contain a {beta}-ether. linkage and {alpha}- or {gamma}-alcohol, which are key structural elements in lignin. The dominant products from the FVP of PhCH{sub 2}CH{sub 2}OPh (PPE), PhC(OH)HCH{sub 2}OPh, and PhCH{sub 2}CH(CH{sub 2}OH)OPh at 500{degrees}C can be attributed to homolysis of the weakest bond in the molecule (C-O bond) or 1,2-elimination. Surprisingly, the hydroxy-substituent dramatically increases the decomposition of PPE. It is proposed that internal hydrogen bonding is accelerating the reaction.

Cooney, M.J.; Britt, P.F.; Buchanan, A.C. III

1997-03-01

296

What Determines Bond Costs. Municipal Bonds Series.  

ERIC Educational Resources Information Center

|Public officials in small towns who participate infrequently in the bond market need information about bond financing. This publication, one in a series of booklets published by the Western Rural Development Center using research gathered between 1967-77, discusses factors influencing the marketability and cost of bond financing for towns and

Young, Douglas; And Others

297

Chemical Bonding Technology.  

National Technical Information Service (NTIS)

Primers employed in bonding together the various material interfaces in a photovoltaic module are being developed. The approach develops interfacial adhesion by generating actual chemical bonds between the various materials bonded together. The current st...

E. Plueddemann

1986-01-01

298

RF vacuum electronics  

NASA Astrophysics Data System (ADS)

We summarize our second quarter progress and discuss third quarter plans for the development of an edge emitter based vacuum triode with performance goals of 10 micro-A/micron emission current density at less than 250 V and which can be modulated at 1 GHz for 1 hour. Design and layout of the emitter test mask was completed and fabrication of two process runs of edge emitter diodes were completed. These diode emitters utilize a comb emitter design where high resistivity TaN thin films act as current limiters to prevent edge burnout. Testing of these devices will start during the third quarter. Initial design work on the edge emitter triode was started and is described. Extensive finite element modeling (FEM) and analysis to aid in the triode design took place and is described. Significant process development also took place. Experimental studies of dielectrics such as sputtered SiO2, Si3N4, and PECVD SiO2 and Si3N4 were carried out to understand their leakage characteristics and, thus, to understand their impact on emitter performance. A description of our vacuum test station is also given.

Akinwande, T.; Bauhahn, P.; Ohnstein, T.; Holmen, J.; Arch, D.

1992-04-01

299

Accelerator Vacuum Protection System  

NASA Astrophysics Data System (ADS)

A new and elaborate automatic vacuum protection system using fast acting valve has been installed to avoid accidental venting of accelerator from experimental chamber side. To cover all the beam lines and to reduce the system cost, it has been installed at a common point from where all the seven beam lines originate. The signals are obtained by placing fast response pressure sensing gauges (HV SENSOR) near all the experimental stations. The closing time of the fast valve is 10 milli-second. The fast closing system protects only one vacuum line at a time. At IUAC, we have seven beam lines so one sensor was placed in each of the beam lines near experimental chamber and a multiplexer was incorporated into the fast closing system. At the time of experiment, the sensor of the active beam line is selected through the multiplexer and the Fast closing valve is interlocked with the selected sensor. As soon as the pressure sensor senses the pressure rise beyond a selected pressure, the signal is transferred and the fast valve closes within 10 to 12 millisecond.

Barua, Pradip; Kothari, Ashok; Archunan, M.; Joshi, Rajan

2012-11-01

300

MOLECULAR VACUUM PUMP  

DOEpatents

A multiple molecular vacuum pump capable of producing a vacuum of the order of 10/sup -9/ mm Hg is described. The pump comprises a casing of an aggregate of paired and matched cylindrical plates, a recessed portion on one face of each plate concentrically positioned formed by a radially extending wall and matching the similarly recessed portion of its twin plate of that pair of plates and for all paired and matched plates; a plurality of grooves formed in the radially extending walls of each and all recesses progressing in a spiral manner from their respective starting points out at the periphery of the recess inwardly to the central area; a plurality of rotors rotatably mounted to closely occupy the spaces as presented by the paired and matched recesses between all paired plates; a hollowed drive-shaft perforated at points adjacent to the termini of all spiral grooves; inlet ports at the starting points of all grooves and through all plates at common points to each respectively; and a common outlet passage presented by the hollow portion of the perforated hollowed drive-shaft of the molecular pump. (AEC)

Eckberg, E.E.

1960-09-27

301

Portable vacuum object handling device  

DOEpatents

The disclosure relates to a portable device adapted to handle objects which are not to be touched by hand. A piston and bore wall form a vacuum chamber communicating with an adaptor sealably engageable with an object to be lifted. The piston is manually moved and set to establish vacuum. A valve is manually actuatable to apply the vacuum to lift the object. 1 fig.

Anderson, G.H.

1983-08-09

302

Uncooled IRFPA with chip scale vacuum package  

NASA Astrophysics Data System (ADS)

We have developed an uncooled IRFPA with a chip scale vacuum package and succeeded in obtaining excellent IR images of less than 60 mK in NETD. This package consists of a device chip and a silicon lid. The chip in this study is a 160 x 120 SOI diode IRFPA with a 25 ?m pixel pitch. The size of the package is 14.5(L) x 13.5(W) x 1.2(H) mm. The gap between the device chip and the lid is controlled by the thickness of the vacuum sealing material. The lid is prepared by a wafer process and diced just before vacuum sealing. We use DLC (diamond like carbon) as the AR coat because of its high IR transmittance and high endurance in the wafer process. DLC films are deposited on both sides of the silicon lid wafer, and then a ring-shaped metal pattern for solder bonding is formed on one side of the lid wafer. Solder is mounted on the metal pattern by a molten solder ejection method. The patterned thin-film getter is formed on the lid wafer. Because of the use of patterned thin-film getter, there is no need to form a cavity on the lid to allow installation of getter or to insert a spacer between the device chip and the lid. Then the lid wafer is diced into individual lids. The device wafer and the lids are set in a vacuum chamber, which has a heater to melt the solder, so as to pair each die and lid. After pumping the chamber, the patterned thin-film getters are activated and then the lids are bonded simultaneously to the device wafer. Finally the device wafer is diced into individual chips. The measured pressure of the package is less than 0.5 Pa which is sufficient for obtaining high thermal isolation. In this technique, only the good dies in a wafer are packaged in chip scale simultaneously. Thus, a reduction in the size and cost of the package has been achieved.

Hata, Hisatoshi; Nakaki, Yoshiyuki; Inoue, Hiromoto; Kosasayama, Yasuhiro; Ohta, Yasuaki; Fukumoto, Hiroshi; Seto, Toshiki; Kama, Keisuke; Takeda, Munehisa; Kimata, Masafumi

2006-06-01

303

Effect of Ti, Nb, and Ti + Nb Coatings on the Bond Strength-Structure Relationship in Al/Al2O3 Joints  

NASA Astrophysics Data System (ADS)

There is a growing interest in metal-ceramic bonding for wide range of applications in electronic devices and high technology industry for fabrication of metal matrix composites and bonding of ceramic components to metals. The object of the work was to study the effect of Ti, Nb, and Ti + Nb thin films deposited by PVD method on alumina substrates on structure and bond strength properties of Al/Al2O3 joints. The joints were fabricated using the results of a wetting experiment and the sessile drop method at a temperature of 1223 K in a vacuum of 0.2 MPa for 30 min of contact. The structure of the metal/ceramic interface was investigated using scanning electron microscopy. The elemental distribution at the metal-ceramic interface was analyzed using energy dispersive x-ray spectroscopy. Transmission electron microscopy was also used to investigate some aspects of the metal/ceramic interface. The bond strength properties of joints were measured using shear test. The shear strength results demonstrated significant improvement of shear strength of Al/Al2O3 joints due to the application of Ti + Nb thin film on alumina substrate. Microstructural investigations of the interface indicated that Al/coating/Al2O3 couples have diffusion transition interface which influences the strengthening of these joints. A conclusion could be drawn that the presence of thin film layers changes the character of interaction and leads to the formation of new reaction products in the bonding layer.

Ksiazek, Marzanna; Richert, Maria; Tchorz, Aam; Boron, Lukasz

2012-05-01

304

Vacuum-Packaging Technology for IRFPAs  

Microsoft Academic Search

We developed vacuum-packaging equipment and low-cost vacuum packaging technology for IRFPAs. The equipment is versatile and can process packages with various materials and structures. Getters are activated before vacuum packaging, and we can solder caps\\/ceramic-packages and caps\\/windows in a high-vacuum condition using this equipment. We also developed a micro-vacuum gauge to measure pressure in vacuum packages. The micro-vacuum gauge uses

Takeshi Matsumura; Takayuki Tokuda; Akinobu Tsutinaga; Masafumi Kimata; Hideyuki Abe; Naotaka Tokashiki

2010-01-01

305

Vacuum Technology:. Principles and Applications  

NASA Astrophysics Data System (ADS)

This work is devoted on principles and applications of vacuum technology. Classification and properties of vacuum are discussed. Various pumping mechanisms as well as three basic flow regimes namely viscous, intermediate and molecular are briefly presented. Gas-surface interaction concepts including physisorption and chemisorption states with their distinctive character as well as desorption phenomenon are considered. Two types of surface reaction mechanisms, Langmuir-Hinshelwood and Eley-Rideal are introduced. Applications of vacuum technology in the field of surface science, microfabrication, particle accelerators and analytical techniques are described. Finally, the use of vacuum in different industries with their corresponding applications is briefly reviewed.

Moshfegh, A. Z.

2004-06-01

306

Diffusion /Osmosis  

NSDL National Science Digital Library

This project is use to review the concepts of diffusion and osmosis 1. Watch the tutorials on diffusion and osmosis. Take the online quiz at the end of each one. Diffusion Animation Osmosis Animation 2. Do the interactive lab on diffusion. Stop when you get to the calculating water potential section. Diffusion/Osmosis Interactive Demo 3. Play the Quia review games. Quia Games- matching/concetration Quia Jeopardy 4. Check out the Elodea leaf cells. Be able to ...

Jensen

2007-11-26

307

Neutron radiation hardness of vacuum compatible two-component adhesives  

NASA Astrophysics Data System (ADS)

This paper reports the investigation of the irradiation dependent bonding strength of two-component glues which have low outgassing compatible with vacuum applications. The strength of the glue joints is compared before and after exposure to a thermal neutron fluence of 2.3510neutronspercm. The goal of this work is to establish a glue which is applicable to join glass and metal parts of the ultra-cold neutron (UCN) guide system at the Paul Scherrer Institute's UCN source.

Bertsch, J.; Goeltl, L.; Kirch, K.; Lauss, B.; Zubler, R.

2009-04-01

308

A large high vacuum, high pumping speed space simulation chamber for electric propulsion  

NASA Astrophysics Data System (ADS)

Testing high power electric propulsion devices poses unique requirements on space simulation facilities. Very high pumping speeds are required to maintain high vacuum levels while handling large volumes of exhaust products. These pumping speeds are significantly higher than those available in most existing vacuum facilities. There is also a requirement for relatively large vacuum chamber dimensions to minimize facility wall/thruster plume interactions and to accommodate far field plume diagnostic measurements. A 4.57 m (15 ft) diameter by 19.2 m (63 ft) long vacuum chamber at NASA Lewis Research Center is described. The chamber utilizes oil diffusion pumps in combination with cryopanels to achieve high vacuum pumping speeds at high vacuum levels. The facility is computer controlled for all phases of operation from start-up, through testing, to shutdown. The computer control system increases the utilization of the facility and reduces the manpower requirements needed for facility operations.

Grisnik, Stanley P.; Parkes, James E.

1994-01-01

309

Fluxless bondings of silicon to alumina substrate using electroplated eutectic Au-Sn solder  

Microsoft Academic Search

Large 6 mm times 9 mm silicon dice have been successfully bonded on alumina substrate with electroplated Au80Sn20 eutectic alloy. Eutectic AuSn is one of the best known hard solders having excellent fatigue-resistance and mechanical properties. A fluxless bonding process in 50 militorrs of vacuum environment is presented. Vacuum environment is employed to prevent tin oxidation during the process. The

Jong S. Kim; Won S. Choi; A. Shkel; C. C. Lee

2006-01-01

310

Moisture diffusivity in food materials.  

PubMed

This paper investigates whether moisture diffusion can be predicted for food materials. We focus especially on mixtures of glucose homopolymers and water. The predictions are based on three theories: (1) the Darken relation, linking the mutual diffusivity to the self diffusivities, (2) the generalised Stokes-Einstein relation for the solute self diffusivity, and (3) the free volume theory for water self diffusivity. Using literature data obtained for the whole class of glucose homopolymer, we show that these theories predict the moisture diffusivity for the whole range of volume fractions, from zero to one, and a broad range of temperatures. Furthermore, we show that the theories equally holds for other hydrophilic biopolymers one finds in food. In the concentrated regime, all experimental data collapse to a single curve. This universal behaviour arises because these biopolymers form a hydrogen bonded network, where water molecules move via rearrangement of the free volume. PMID:23411242

van der Sman, R G M; Meinders, M B J

2012-11-12

311

Control Dewar Secondary Vacuum Container  

SciTech Connect

This engineering note provides background information regarding the control dewar secondary vacuum container. The secondary vacuum container has it's origin with the CDP control dewar design. The name secondary vacuum container replaced the CDP term 'Watt can' which was named after Bob Watt (SLAC), a PAC/DOE review committee member who participated in a review of CDP and recommended a secondary vacuum enclosure. One of the most fragile parts of the control dewar design is the ceramic electrical feed throughs located in the secondary vacuum container. The secondary vacuum container is provided to guard against potential leaks in these ceramic insulating feed throughs. The secondary vacuum container has a pumping line separate from the main solenoid/control dewar insulating vacuum. This pumping line is connected to the inlet of the turbo pump for initial pumpdown. Under normal operation the container is isolated. Should a feedthrough develop a small leak, alternate pumping arrangements for the secondary vacuum container could be arranged. The pressure in the secondary vacuum container should be kept in a range that the breakdown voltage is kept at a maximum. The breakdown voltage is known to be a function of pressure and is described by a Paschen curve. I cannot find a copy of the curve at this time, but from what I remember, the breakdown voltage is a minimum somewhere around 10-3 torr. Ideally the pressure in the secondary vacuum can should be kept very low, around 10 E-6 or 10 E-7 torr for maximum breakdown voltage. If however a leak developed and this was not possible, then one could operate at a pressure higher than the minima point.

Rucinski, R.; /Fermilab

1993-10-04

312

Entrapment Type Vacuum Pumps  

NSDL National Science Digital Library

This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. Entrapment type pumps operate primarily in the high to ultra-high vacuum ranges. The discussion in this MATEC module includes applications, theory of operation, operating range and preventative maintenance. The focus is on three major types of pumps: cryosorption, cryogenic and sputter-ion. The overall performance of these types of pumps depends on a variety of parameters. For example, it is important that learners understand the balance between pumping speed and capacity. Competency is demonstrated as the learners specify systems for defined process applications.

2012-12-20

313

Pseudoredundant vacuum energy  

NASA Astrophysics Data System (ADS)

We discuss models that can account for todays dark energy. The underlying cosmological constant may be Planck scale but starts as a redundant coupling which can be eliminated by a field redefinition. The observed vacuum energy arises when the redundancy is explicitly broken, say by a nonminimal coupling to curvature. We give a recipe for constructing models, including R+1/R-type models, that realize this mechanism and satisfy all solar system constraints on gravity. A similar model, based on Gauss-Bonnet gravity, provides a technically natural explanation for dark energy and exhibits an interesting seesaw behavior: a large underlying cosmological constant gives rise to both low- and high-curvature solutions. Such models could be statistically favored in the string landscape.

Batra, Puneet; Hinterbichler, Kurt; Hui, Lam; Kabat, Daniel

2008-08-01

314

THERMOCOUPLE VACUUM GAUGE  

DOEpatents

A protector device is described for use in controlling the pressure within a cyclotron. In particular, an electrical circuit functions to actuate a vacuum pump when a predetermined low pressure is reached and disconnect the pump when the pressure increases abcve a certain value. The principal feature of the control circuit lies in the use of a voltage divider network at the input to a relay control tube comprising two parallel, adjustable resistances wherein one resistor is switched into the circuit when the relay connects the pump to a power source. With this arrangement the relay is energized at one input level received from a sensing element within the cyclotron chamber and is de-energized when a second input level, representing the higher pressure limit, is reached.

Price, G.W.

1954-08-01

315

Atomic carbide bonding leading to superior graphene networks.  

PubMed

A versatile method for achieving atomic carbide-bonded graphene networks on both metallic and non-metallic substrates is described. This consists of vacuum-assisted thermal exfoliation and floatation of functional graphenes at elevated temperatures, followed by deposition on substrates and in situ formation of carbide bonds. The cross-linked graphene networks with an interlayer distance of angstroms exhibits a unique combination of unprecedented properties. PMID:23852915

Huang, Wenyi; Yu, Jianfeng; Kwak, Kwang Joo; Gallego-Perez, Daniel; Liao, Wei-Ching; Yang, Hao; Ouyang, Xilian; Li, Lei; Lu, Wu; Lafyatis, Gregory P; Lee, L James

2013-07-15

316

Thermal behaviors of petn base polymer bonded explosives  

Microsoft Academic Search

The thermal behaviors of three pentaerythritol tetranitrate (PETN) base polymer bonded explosives (PBX), Detasheet A (EL506A,\\u000a red) and Datasheet C (EL506C, yellow-green) that supply by DuPont Co., PBXN-301 were investigated using thermal techniques\\u000a in this work. The thermal properties of PETN base polymer bonded explosives, such as vacuum thermal stability (VTS), time\\u000a to ignition, auto-ignition and shelf life of PBX

K.-S. Jaw; J.-S. Lee

2008-01-01

317

Regional Contagion: Social, Economic, Health and Population Crisis Diffusion.  

National Technical Information Service (NTIS)

Since the fall of the Iron Curtain and subsequent governance vacuum, the globe has seen more instability than any time in recent history. In this environment, multiple crises have escalated and diffused through spatial, temporal and population networks, l...

R. J. Passinault

2008-01-01

318

CC Cryostat Vacuum Pumping Efficiency  

Microsoft Academic Search

This report calculates the effect of the conductances of the pumping lines on the pumping speeds of the vacuum pumps being used to pump the inner vessel, and annular space, vacuum tight during the CC Cryostat testing. Effective pumping speeds were calculated for various values of pressure via the above stated formulas (see calculations). Conductances of valves, elbows, and tees

J. B. Fitzpatrick

1987-01-01

319

Chemical pumping in vacuum technology  

Microsoft Academic Search

Chemical pumping in vacuum technology has gained an ever increasing importance during the last two decades. It is based on the capability of metals, such as Zr, Ti, Ba and others, in pure or (more usually) alloy forms, to chemisorb the active residual gases present in vacuum devices or systems. These metals, used in powder form or in many different

B Ferrario

1996-01-01

320

Vacuum Technology:. Principles and Applications  

Microsoft Academic Search

This work is devoted on principles and applications of vacuum technology. Classification and properties of vacuum are discussed. Various pumping mechanisms as well as three basic flow regimes namely viscous, intermediate and molecular are briefly presented. Gas-surface interaction concepts including physisorption and chemisorption states with their distinctive character as well as desorption phenomenon are considered. Two types of surface reaction

A. Z. Moshfegh

2004-01-01

321

Vacuum Requirements for LAMPF II.  

National Technical Information Service (NTIS)

The LAMPF II accelerator will require sufficient vacuum to prevent beam loss or beam blowup within the time the beam is in the accelerator. Because this time is quite short (tau < 0.03 s), the vacuum requirements should be somewhat less strict than for th...

D. Neuffer

1984-01-01

322

Edge conduction in vacuum glazing.  

National Technical Information Service (NTIS)

Vacuum glazing is a form of low-conductance double glazing using in internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. Edge conduction is problematic because it affects stresses in the edge region, l...

T. M. Simko R. E. Collins F. A. Beck D. Arasteh

1995-01-01

323

Vacuum Dewatering During Paper Manufacturing  

Microsoft Academic Search

Water removal during paper making is one of the most energy-intensive and capital-intensive processes. Vacuum dewatering is one of the intermediate stages of water removal on the paper machine where the compressible, wet mat is dewatered using applications of higher vacuum. A summary of the various stages of dewatering on the paper machine wire and the potential mechanisms of dewatering

S. Ramaswamy

2003-01-01

324

Vacuum flash evaporated polymer composites  

DOEpatents

A method for fabrication of polymer composite layers in a vacuum is disclosed. More specifically, the method of dissolving salts in a monomer solution, vacuum flash evaporating the solution, condensing the flash evaporated solution as a liquid film, and forming the condensed liquid film into a polymer composite layer on a substrate is disclosed.

Affinito, J.D.; Gross, M.E.

1997-10-28

325

Vacuum enhanced cutaneous biopsy instrument  

DOEpatents

A syringe-like disposable cutaneous biopsy instrument equipped with a tubular blade at its lower end, and designed so that a vacuum is created during use, said vacuum serving to retain undeformed a plug of tissue cut from a patient's skin.

Collins, Joseph (St. Petersburg, FL)

2000-01-01

326

Manufacturing Processes for Roll Bonded Titanium Alloy Structural Sections.  

National Technical Information Service (NTIS)

The roll diffusion bonding manufacturing process program has resulted in the successful fabrication of a closed section airfoil shape. The airfoil is typical of jet engine inlet guide vanes, compressor stator blades and helicopter rotor blades. The airfoi...

R. D. Brunken

1968-01-01

327

Bond Paths Are Not Chemical Bonds  

NASA Astrophysics Data System (ADS)

This account takes to task papers that criticize the definition of a bond path as a criterion for the bonding between the atoms it links by mistakenly identifying it with a chemical bond. It is argued that the notion of a chemical bond is too restrictive to account for the physics underlying the broad spectrum of interactions between atoms and molecules that determine the properties of matter. A bond path on the other hand, as well as being accessible to experimental verification and subject to the theorems of quantum mechanics, is applicable to any and all of the interactions that account for the properties of matter. It is shown that one may define a bond path operator as a Dirac observable, making the bond path the measurable expectation value of a quantum mechanical operator. Particular attention is given to van der Waals interactions that traditionally are assumed to represent attractive interactions that are distinct from chemical bonding. They are assumed by some to act in concert with Pauli repulsions to account for the existence of condensed states of molecules. It is such dichotomies of interpretation that are resolved by the experimental detection of bond paths and the delineation of their properties in molecular crystals. Specific criticisms of the stabilization afforded by the presence of bond paths derived from spectroscopic measurements performed on dideuteriophenanthrene are shown to be physically unsound. The concept of a bond path as a "bridge of density" linking bonded atoms was introduced by London in 1928 following the definition of the electron density by Schrdinger in 1926. These papers marked the beginning of the theory of atoms in molecules linked by bond paths.

Bader, Richard F. W.

2009-09-01

328

The AGS Booster vacuum systems  

SciTech Connect

The AGS Booster is a synchrotron for the acceleration of both protons and heavy ions. The design pressure of low 10{sup {minus}11} mbar is required to minimize beam loss of the partially stripped heavy ions. To remove contaminants and to reduce outgassing, the vacuum chambers and the components located in them will be chemically cleaned, vacuum fired, baked then treated with nitric oxide. The vacuum sector will be insitu baked to a minimum of 200{degree}C and pumped by the combination of sputter ion pumps and titanium sublimation pumps. This paper describes the design and the processing of this ultra high vacuum system, and the performance of some half-cell vacuum chambers. 9 refs., 7 figs.

Hseuh, H.C.

1989-01-01

329

Cosmology with decaying vacuum energy  

SciTech Connect

Motivated by recent attempts to solve the cosmological constant problem, we examine the observational consequences of a vacuum energy density which decays in time. For all times later than t approx. 1 sec, the ratio of the vacuum to the total energy density of the universe must be small. Although the vacuum cannot provide the ''missing mass'' required to close the universe today, its presence earlier in the history of the universe could have important consequences. We discuss restrictions on the vacuum energy arising from primordial nucleosynthesis, the microwave and gamma ray background spectra, and galaxy formation. A small vacuum component at the era of nucleosynthesis, 0.01 < rho/sub vac//rho/sup rad/ < 0.1, increase the number of allowed neutino species to N/sup nu/ > 5, but in some cases would severely distort the microwave spectrum. 9 refs., 3 figs.

Freese, K.; Adams, F.; Frieman, J.; Mottola, E.

1987-09-01

330

Savings Bonds Value Calculator  

NSDL National Science Digital Library

From the Federal Reserve Bank of New York, this site computes the redemption value of users's US savings bonds. Easy-to-use pull-down menus allow visitors to enter information such as the date of issue and face value of their Series E bonds, Series EE bonds, and Series S bonds. After entering the information, the Calculator will then show a chart of issue dates and denominations and actual worth of the bonds, if cashed within a set period of time.

331

Rotary bayonets for cryogenic and vacuum service.  

National Technical Information Service (NTIS)

Rotary bayonets were designed, tested, and installed for liquid nitrogen, liquid argon, and vacuum service. This paper will present the design, testing, and service record for two sizes of vacuum jacketed cryogenic rotary bayonets and two sizes of vacuum ...

R. A. Rucinski K. D. Dixon R. Krasa K. J. Krempetz G. T. Mulholland

1993-01-01

332

14 CFR 25.1433 - Vacuum systems.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Vacuum systems. 25.1433 Section...AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES...Equipment § 25.1433 Vacuum systems. There must be...discharge lines from the vacuum air pump when the...

2013-01-01

333

14 CFR 29.1433 - Vacuum systems.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Vacuum systems. 29.1433 Section...AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT...Equipment § 29.1433 Vacuum systems. (a) There...unsafe. (b) Each vacuum air system line and...

2013-01-01

334

Vacuum Packaging for Microelectromechanical Systems (MEMS).  

National Technical Information Service (NTIS)

The Vacuum Packaging for MEMS Program focused on the development of an integrated set of packaging technologies which in totality provide a low cost, high volume product-neutral vacuum packaging capability which addresses all MEMS vacuum packaging require...

T. Schimert R. Howe M. Schmidt S. Montague

2002-01-01

335

Holographic diffusers  

NASA Astrophysics Data System (ADS)

Holographic diffusers are prepared using silver halide (Agfa 8E75 and Kodak 649F) and photopolymer (Polaroid DMP 128 and DuPont 600, 705, and 150 series) media. It is possible to control the diffusion angle in three ways: by selection of the properties of the source diffuser, by control of its subtended angle, and by selection of the holographic medium. Several conventional diffusers based on refraction or scattering of light are examined for comparison.

Wadle, Stephen; Wuest, Daniel; Cantalupo, John; Lakes, Roderic S.

1994-01-01

336

Bonded ultrasonic transducer and method for making  

DOEpatents

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.

Dixon, Raymond D. (Los Alamos, NM); Roe, Lawrence H. (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)

1995-01-01

337

Bonded ultrasonic transducer and method for making  

DOEpatents

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.

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

1995-11-14

338

Diffusion MRI  

NASA Astrophysics Data System (ADS)

Recent advances of magnetic resonance imaging have been described, especially stressed on the diffusion sequences. We have recently applied the diffusion sequence to functional brain imaging, and found the appropriate results. In addition to the neurosciences fields, diffusion weighted images have improved the accuracies of clinical diagnosis depending upon magnetic resonance images in stroke as well as inflammations.

Fukuyama, Hidenao

339

Investing in Bonds.com  

NSDL National Science Digital Library

Investing in Bonds was created by the Bond Market Association to educate investors about the benefits of bonds investing. The Investor's Guide to Bond Basics educates investors about the types of bonds available, criteria for evaluating a bond, a guide to buying bonds, bond investment strategies and a glossary of bond market terms. The Bond Market section provides an overview of the U.S. bond market while the Investor's Checklist section takes the investor step-by-step through the bond investment decision process. Investors will also find sections with information on municipal bonds, corporate bonds, mortgage securities and U.S. Inflation-Indexed Securities.

340

Convergent electron gun with bonded nonintercepting control grid  

Microsoft Academic Search

The bonded grid is a metal-insulator-metal sandwich attached directly to impregnated tungsten cathodes. The metallic top surface of the grid structure is the control grid, and the metallic surface on the bottom provides a diffusion barrier for barium between cathode and insulator. A bonded grid for use in microwave triodes was developed and described in a paper at IEDM in

G. V. Miram; E. L. Lien

1978-01-01

341

The electrical resistance of vacuum  

NASA Astrophysics Data System (ADS)

This paper deals with the physics of electrical conduction in vacuum between two parallel conducting planes (planar vacuum diode). After reviewing known features of conduction in the high-voltage range, we turn to the low-voltage range. An ohmic current-voltage characteristic is calculated in the case of identical cathodic and anodic electrodes, whence an electrical resistance of the vacuum gap can be defined. The inverse resistance involves the elemental conductance 2e 2/h and the number of conductance channels between the two electrodes. The channels are thermally populated from the electrodes and the population is analytically calculable from the Poisson equation of electrostatics and the Boltzmann law of thermal equilibrium. The observed resistance of a real vacuum diode (Mullard's EB 91) is accounted for without adjusting parameters. The paper also examines the link-up between Joule's law, involving dissipation, and Ohm's law, with vacuum being contrasted with a material conducting medium; the origin of dissipation in vacuum is understood. Quantum and statistical physics are kept at the undergraduate level. Finally, the results obtained for the vacuum diode shed light upon the quantized conductance of nanoscale semiconductor wires, a topic usually handled only in graduate courses.

Bringuier, E.

2013-07-01

342

Surface micromachined structures fabricated with silicon fusion bonding  

Microsoft Academic Search

A surface micromachining technique has been developed which makes use of silicon fusion bonding. Many of the same types of micromechanical devices previously fabricated from polycrystalline have been fabricated from single-crystal silicon. Bridges and beams suspended near the substrate surface, complex thermally isolated designs, diaphragms suspended over shallow vacuum cavities, vertically and laterally resonant structures, fluid control devices, and fully

Kurt Petersen; Dale Gee; F. Pourahmade; R. Craddock; J. Brown; L. Christel

1991-01-01

343

NCSX Vacuum Vessel Fabrication  

SciTech Connect

The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in conjunction with the Oak Ridge National Laboratory (ORNL). The goal of this experiment is to develop a device which has the steady state properties of a traditional stellarator along with the high performance characteristics of a tokamak. A key element of this device is its highly shaped Inconel 625 vacuum vessel. This paper describes the manufacturing of the vessel. The vessel is being fabricated by Major Tool and Machine, Inc. (MTM) in three identical 120 vessel segments, corresponding to the three NCSX field periods, in order to accommodate assembly of the device. The port extensions are welded on, leak checked, cut off within 1" of the vessel surface at MTM and then reattached at PPPL, to accommodate assembly of the close-fitting modular coils that surround the vessel. The 120 vessel segments are formed by welding two 60 segments together. Each 60 segment is fabricated by welding ten press-formed panels together over a collapsible welding fixture which is needed to precisely position the panels. The vessel is joined at assembly by welding via custom machined 8" (20.3 cm) wide spacer "spool pieces." The vessel must have a total leak rate less than 5 X 10-6 t-l/s, magnetic permeability less than 1.02?, and its contours must be within 0.188" (4.76 mm). It is scheduled for completion in January 2006.

Viola, M. E.; Brown, T.; Heitzenroeder, P.; Malinowski, F.; Reiersen, W.; Sutton, L.; Goranson, P.; Nelson, B.; Cole, M.; Manuel, M.; McCorkle, D.

2005-10-07

344

Compact vacuum insulation  

DOEpatents

Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases therebetween are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and variious laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels.

Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

1992-01-01

345

Compact vacuum insulation  

DOEpatents

Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases there between are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and various laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels. 35 figs.

Benson, D.K.; Potter, T.F.

1992-10-27

346

Corrosion fatigue of steels with vacuum-diffusion coating  

Microsoft Academic Search

The fatigue and corrosion-fatigu e tests were carried out on an MVP-10,000 machine with pure bending of rotating standard test pieces 7.5 mm in diameter (GOST 2860-65) with 107 to 5 ?9 107 cycles. The test pieces were tested at 24,400, and 600~ in 4% solutions of common salt and nitric acid. The chemically reactive liquid was applied to the

E. P. Ponomarenko; D. M. Petergerya; A. A. Domio; V. G. Rastorgueva

1974-01-01

347

Temperature Gradient Vacuum Furnace for Diffusion Studies to 2000C  

Microsoft Academic Search

An rf induction-heated furnace has been designed that produces a stable linear temperature gradient greater than 1000 C?cm and a maximum specimen temperature of 2000C. Methods of measuring temperature in a temperature gradient have been evaluated and the performance of the furnace and its power requirements are discussed.

R. O. Meyer; J. C. Voglewede

1971-01-01

348

Tentorial hemorrhage associated with vacuum extraction.  

PubMed

The clinical and radiologic descriptions of three neonates with tentorial hemorrhage after vacuum extraction are reported. All patients were full term, with Apgar scores of 8 or more; one patient experienced fetal distress during delivery. Within 36 hours after birth, the neonates had multiple generalized seizures; computed tomography or magnetic resonance imaging outlined distinctive tentorial hemorrhages with extension over the superior surface of the cerebellum or inferior surface of the occipital lobe. One patient had diffuse hypoxic-ischemic injury, and another had bilateral temporal lobe infarcts. Treatment included medical control of seizures and intracranial hypertension; one patient had surgical evacuation of bilateral subdural hematomas. Follow-up from 1 to 5 years showed significant developmental delays in two patients. These cases demonstrate that the forces generated on the fetal cranium by vacuum extraction are similar to those produced by forceps and result in tentorial laceration, venous rupture, and subdural hemorrhage. Because these hemorrhages may be associated with significant ischemic injury, serial radiologic evaluation is recommended for the detection of persistent structural abnormalities. PMID:2314967

Hanigan, W C; Morgan, A M; Stahlberg, L K; Hiller, J L

1990-04-01

349

The Bond Market Association  

NSDL National Science Digital Library

The Bond Market Association "represents securities firms and banks that underwrite, trade and sell debt securities." Their web site is divided into several sections. The Research Desk presents the results of research conducted by the association, including forecasts of economic growth and analysis of bond market trends. The Legislative Issues and Regulatory sections provide a summary of legislative and regulatory developments of interest to the bond market community. Market Practices contains guidelines and procedures to be followed in the bond market. The site also provides information to investors on how to invest in corporate bonds, tax-exempt municipal bonds, and mortgage securities.

1998-01-01

350

Low temperature Cu-Cu direct bonding using formic acid vapor pretreatment  

Microsoft Academic Search

This paper describes a novel low temperature Cu-Cu direct bonding method using formic acid vapor pretreatment. The in situ dry process of reduction using formic acid vapor is developed to realize Cu-Cu direct bonding at low temperature and in low vacuum. In order to analyze the Cu film surface reduction by formic acid vapor, the CMP Cu film surface is

Wenhua Yang; Hiroyuki Shintani; Masatake Akaike; Tadatomo Suga

2011-01-01

351

Vacuum-Assisted Vaginal Delivery  

PubMed Central

Approximately 5% (1 in 20) of all deliveries in the United States are operative vaginal deliveries. The past 20 years have seen a progressive shift away from the use of forceps in favor of the vacuum extractor as the instrument of choice. This article reviews in detail the indications, contraindications, patient selection criteria, choice of instrument, and technique for vacuum-assisted vaginal delivery. The use of vacuum extraction at the time of cesarean delivery will also be discussed. With vacuum extraction becoming increasingly popular, it is important that obstetric care providers are aware of the maternal and neonatal risks associated with such deliveries and of the options available to effect a safe and expedient delivery.

Ali, Unzila A; Norwitz, Errol R

2009-01-01

352

APS storage ring vacuum system  

SciTech Connect

The Advanced Photon Source synchrotron radiation facility, under construction at the Argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's experimental program. The Storage Ring's 1104 m circumference is divided into 40 functional sectors. The sectors include vacuum, beam transport, control, acceleration and insertion device components. The vacuum system, which is designed to operate at a pressure of 1 n Torr, consists of 240 connected sections, the majority of which are fabricated from an aluminum alloy extrusion. The sections are equipped with distributed NeG pumping, photon absorbers with lumped pumping, beam position monitors, vacuum diagnostics and valving. The details of the vacuum system design, selected results of the development program and general construction plans are presented. 11 refs., 6 figs., 3 tabs.

Niemann, R.C.; Benaroya, R.; Choi, M.; Dortwegt, R.J.; Goeppner, G.A.; Gonczy, J.; Krieger, C.; Howell, J.; Nielsen, R.W.; Roop, B.; Wehrle, R.B.

1990-01-01

353

APS storage ring vacuum system  

SciTech Connect

The advanced Photon Source synchrotron radiation facility, under construction at the argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's experimental program. The Storage Ring's 1104 m circumference is divided into 40 functional sectors. The sectors include vacuum, beam transport, control, acceleration and insertion device components. The vacuum system, which is designed to operate at a pressure of 1 nTorr, consists of 240 connected sections, the majority of which are fabricated from an aluninum alloy extrusion. The sections are equipped with distributed NeG pumping, photon absorbers with lumped pumping, beam position monitors, vacuum diagnostics and valving. The detaileds of the vacuum system design, selected results of the development program and general construction plans are presented.

Niemann, R.C.; Benaroya, R.; Choi, M.; Dortwegt, R.J.; Goeppner, G.A.; Gonczy, J.; Krieger, C.; Howell, J.; Nielsen, R.W.; Roop, B.; Wehrle, R.B. (Argonne National Laboratory, Argonne, Illinois 60439 (United States))

1991-08-20

354

Vacuum microelectronic devices [and prolog  

Microsoft Academic Search

In this review\\/tutorial paper, we cover the history, physics, and current status of vacuum microelectronic devices. First we overview the performance requirements of vacuum microelectronic devices necessary for them to replace, or fill voids left by, solid state devices. Next we discuss the physical characteristics of micro-field-emission sources important to device applications. These characteristics include fundamental features, such as current-voltage

IVOR BRODIE; PAUL RICHARD SCHWOEBEL

1994-01-01

355

Vacuum frying of potato chips  

Microsoft Academic Search

Vacuum frying was tested as an alternative technique to develop low oil content potato chips. The effect of oil temperature (118, 132, 144 C) and vacuum pressure (16.661, 9.888, and 3.115 kPa) on the drying rate and oil absorption of potato chips and on the product quality attributes such as shrinkage, color, and texture was investigated. Furthermore, the characteristics of

Jagoba Garayo; Rosana Moreira

2002-01-01

356

Vacuum Variable Medium Temperature Blackbody  

Microsoft Academic Search

This article describes the vacuum variable medium-temperature blackbody (VMTBB) constructed to serve as a highly stable reference\\u000a source with an aperture diameter of 20mm in the temperature range from 150C to 430C under medium-vacuum conditions (10?3 Pa) and in a reduced background environment (liquid-nitrogen-cooled shroud). The VMTBB was realized for the calibration facility\\u000a at the PTB in the field of

S. P. Morozova; N. A. Parfentiev; B. E. Lisiansky; U. A. Melenevsky; B. Gutschwager; C. Monte; J. Hollandt

2010-01-01

357

Wafer-level hermetic packaging of 3D microsystems with low-temperature Cu-to-Cu thermo-compression bonding and its reliability  

NASA Astrophysics Data System (ADS)

Low-temperature wafer-level Cu-to-Cu thermo-compression bonding and its reliability for hermetic sealing application have been investigated in this work. The volume of the encapsulated cavities is about 1.410-3 cm3 in accordance with the MIL-STD-883E standard prescribed for microelectronics packaging hermeticity measurement. The samples under test are bonded at 300 C under a bonding force of 5500 N for 1 h in vacuum (2.5 10-4 mbar) with a 300 nm thick Cu diffusion layer and 50 nm thick Ti barrier layer which are deposited in an e-beam evaporator. The reliability test is accomplished through a temperature cycling test (TCT) from -40 to 125 C up to 1000 cycles and a humidity test based on IPC/JEDEC J-STD-020 standard. In addition, an immersion in acid/base solution is applied to verify the corrosion resistance of the Cu frame for hermetic application. Excellent helium leak rate which is smaller than the reject limit defined by the MIL-STD-883E standard (method 1014.10) is detected for all the samples. These excellent helium leak rates show an outstanding bonding quality against harsh environment for hermetic encapsulation in 3D integration applications.

Fan, J.; Peng, L.; Li, K. H.; Tan, C. S.

2012-10-01

358

Remarks on the use of perfluoropolyether fluids in particle accelerator vacuum systems  

Microsoft Academic Search

A systematic series of tests was performed to investigate the advantages of using standard cuts of perfluoropolyether fluids (Fomblin Y) as vacuum fluids for the pumpdown of ion source and particle accelerator vacuum systems. Vacua in the low 10⁻³ and 10⁻⁷ Torr ranges were obtained by a rotary and an unbaffled diffusion pump, respectively. A residual gas analysis shows the

A. Luches; M. R. Perrone

1976-01-01

359

High repetition rate Bose-Einstein condensate production in a compact, transportable vacuum system  

Microsoft Academic Search

This thesis reports on the design and implementation of a compact (5 x 10 x 30 cm) two chamber system for rapidly producing 87Rb Bose-Einstein condensates (BEC) on an atom chip with the future goal of a transportable BEC based sensor. We present the first use of anodic bonding to fabricate multi-chamber vacuum systems suitable for BEC production. Anodic bonding

Matthew B. Squires

2008-01-01

360

Direct Bonding between Silicone and Glass by Atmospheric-Pressure Surface Modification  

NASA Astrophysics Data System (ADS)

We experimentally demonstrated the differences of surface modification effects on silicon-based polymer of soft-type silicone-rubber and hard-type silicone-resin in contact angle and bonding strength by exposure of oxygen plasma, atmospheric pressure plasma, and vacuum-ultraviolet light, in order to investigate the availability of non-vacuum process of atmospheric plasma and vacuum-ultraviolet light for high-throughput surface modifications and bonding. We also propose the use of a hard silicone-resin for Micro Electro Mechanical Systems (MEMS) and Micro-Total Analysis Systems (?-TAS) material to overcome drawbacks of silicone-rubber, such as easy deformation and destruction of micro / nano structures caused by its softness. As a result, any modification method successfully modified the surface of both silicone-rubber and silicone-resin up to about 10 in contact angle, and bonded to glass. However, the bonding strength between silicone-resin and glass by vacuum ultraviolet light was one order of magnitude smaller than that by oxygen plasma and atmospheric plasma bonding. The results suggest that atmospheric plasma satisfies both high-speed non-vacuum process and high-efficient way for surface modification and the following bonding.

Okada, Wataru; Yamamoto, Takatoki

361

Mechanisms for room temperature direct wafer bonding  

NASA Astrophysics Data System (ADS)

Reducing the temperature needed for high strength bonding which was and is driven by the need to reduce effects of coefficient of thermal expansion mismatch, reduce thermal budgets, and increase throughput has led to the development of plasma treatment procedures capable of bonding Si wafers below 300 C with a bond strength equivalent to Si bulk. Despite being widely used, the physical and chemical mechanisms enabling low temperature wafer bonding have remained poorly understood. We developed an understanding of the beneficial surface modifications by plasma and a model based on short range low temperature diffusion through bonding experiments combined with results from spectroscopic ellipsometry, depth resolving Auger electron spectroscopy, and transmission electron microscopy measurements. We also present experimental results showing that even at room temperature reasonable bond strength can be achieved. We conclude that the gap closing mechanism is therefore a process which balances the lowering of the total energy by minimizing the sum of the free surface energy (maximizing the contact area between the surfaces) and strain energy in the oxide at the bond interface.

Plach, T.; Hingerl, K.; Tollabimazraehno, S.; Hesser, G.; Dragoi, V.; Wimplinger, M.

2013-03-01

362

Vacuum deposited polycrystalline silicon films for solar cell applications. Quarterly report, 1 April-30 June 1980  

SciTech Connect

Polycrystalline p-type films were vacuum deposited onto TiB/sub 2/ coated alumina and sapphire substrates. Epitaxial layers were also formed on single crystal silicon substrates. Junctions in the layers were created by both gaseous diffusion in a tube furnace and by vacuum deposition. The TiB/sub 2/ vacuum deposited bottom electrodes have resistivities between 30 and 40 ..mu.. ..cap omega..-cm. All-vacuum-deposited solar cells were fabricated for the first time. Efficiencies approaching those in the diffused junction devices were achieved. The n-layers were deposited on the previously deposited p-layer/TiB/sub 2//ceramic sandwiches by vacuum deposition of silicon in a phosphine (PH/sub 3/) atmosphere. Photovoltaic data in diffused junction samples, including efficiency and spectral response measurements, indicate that crystallite size may no longer be the limiting factor in achieving high efficiency; rather, performance is now being limited by the presence of impurities in the vacuum deposition silicon base region.

Feldman, C.; Arrington, III, C. H.; Blum, N. A.; Satkiewicz, F. G.

1980-08-01

363

Societal Bonding and Delinquency  

Microsoft Academic Search

Travis Hirschi's (1969) theory of control has amassed considerable empirical support since its development and has become one of the dominant explanations of delinquent behavior. Control theory's basic premise is that people with strong bonds to society are less likely to deviate from conventional behavior than those with weak bonds. In this article bonding theory is applied to a severely

Karen Witchcoff Knight; Tony Tripodi

1996-01-01

364

Bonded flexible pipe  

Microsoft Academic Search

This paper presents an overview of bonded flexible pipe improvements primarily driven by environmental safety as applied to offshore development using mobile production systems. Bonded pipe is a flexible pipe where the steel reinforcement is integrated and bonded to a vulcanized elastomeric material. Textile material is included in the structure to obtain additional structural reinforcement or to separate elastomeric layers.

Val M. Northcutt

2000-01-01

365

Thin die bonding techniques  

Microsoft Academic Search

Picking and bonding 50-micron thick chips presents new challenges to the die bonder industry. Extensive development efforts have identified a number of process challenges and solutions. This paper summarizes Esec's most recent learning's pertaining to the thin die bonding process. Problems with standard die bonding chip pick up and epoxy-dispensing techniques are discussed and solutions identified. Two novel pick solutions

J. Medding; R. Stalder; M. Niederhauser; P. Stoessel

2004-01-01

366

Hydrophobic silicon wafer bonding  

Microsoft Academic Search

Silicon wafers with hydrophilic surfaces can be bonded at room temperature (RT). This has been attributed to the presence of OH groups on the mating surfaces that form hydrogen bonds between the two wafers.19 Hydrophobic Si wafers prepared by a dip in diluted HF without subsequent water rinse have shown a similar RT bonding performance.3 Dispersion van der Waals forces

Q.-Y. Tong; E. Schmidt; U. Gsele; M. Reiche

1994-01-01

367

Vacuum and beam transport lines: main principles  

Microsoft Academic Search

Some details of vacuum system designs of beam transport lines are presented. The effect of gas desorption on vacuum equilibrium and stability and ion-induced pressure instability in the beam transport lines are discussed. Main vacuum relationships are also given as a basis for understanding the vacuum system configuration of beam transport lines. Residual gas spectra together with specific outgassing rates

J. Pivar?; K. D. Tumanov

1997-01-01

368

Bonded multilayer Laue Lens for focusing hard x-rays.  

SciTech Connect

We have fabricated partial Multilayer Laue Lens (MLL) linear zone plate structures with thousands of alternating WSi{sub 2} and Si layers and various outermost zone widths according to the Fresnel zone plate formula. Using partial MLL structures, we were able to focus hard X-rays to line foci with a width of 30 nm and below. Here, we describe challenges and approaches used to bond these multilayers to achieve line and point focusing. Bonding was done by coating two multilayers with AuSn and heating in a vacuum oven at 280-300 C. X-ray reflectivity measurements confirmed that there was no change in the multilayers after heating to 350 C. A bonded MLL was polished to a 5-25 {micro}m wedge without cracking. SEM image analyses found well-positioned multilayers after bonding. These results demonstrate the feasibility of a bonded full MLL for focusing hard X-rays.

Liu, C.; Conley, R.; Qian, J.; Kewish, C.M.; Macrander, A.T.; Maser, J.; Kang, H.C.; Yan, H.; Stephenson, G.B.; Advanced Photonics Research Institute; Gwangju Institute of Science and Technology

2007-11-11

369

Silicate and direct bonding of low thermal expansion materials  

NASA Astrophysics Data System (ADS)

Joining of materials becomes an issue, when high stability at large temperature variation is required. Stress from thermal mismatch of auxiliary materials and corresponding distortions are often unavoidable. We describe the use of two inorganic bonding technologies for joining low thermal expansion glasses. The techniques of silicate and direct bonding were applied to join ultra-low thermal expansion glass elements of 150 mm diameter to from light-weight and high precision opto-mechanical compounds. Related bond strengths were investigated on separate reference specimen. Dimensional stability of the bonded systems during thermal cycling in vacuum was investigated by Fizeau interferometry at temperatures between 78 K and 335 K with high accuracy. The results illustrate the great potential of both bonding technologies for glass based precision engineering applications to be used under highly demanding environmental conditions, like in space.

Kalkowski, Gerhard; Fabian, Simone; Rothhardt, Carolin; Zeller, Paul; Risse, Stefan

2013-09-01

370

A Two-Stage Oil Diffusion Pump  

Microsoft Academic Search

A two-stage oil diffusion pump built of glass is described which makes possible the utilization of the advantages of oil without requiring the use of an unusually good coarse vacuum. The novelty of the pump resides in the first stage which is so designed that it cannot clog even with the small clearances needed to work against high pressures.

Joseph E. Henderson

1935-01-01

371

Use of Silicones as Diffusion Pump Oils  

Microsoft Academic Search

Comparative performances of Litton C, Octoil, Narcoil, and two typical silicones in a non-fractionating diffusion pump are presented with a discussion of vapor pressure, stability to heat and oxidation, and the ability to operate against high forepressures. Extrapolated vapor pressure, temperature data, and test results show the high boiling silicone to produce the highest vacuum as indicated by an untrapped

Gordon P. Brown

1945-01-01

372

On the Rate of Decomposition of Diffusion Pump Oil  

Microsoft Academic Search

The rate of decomposition of diffusion pump oil under the working condition seems to be an important quantity in reference to the vacuum. The following experiment was carried out to give an answer to the problems, ``Whether various metals really catalyse the decomposition of diffusion pump oil ? and ``Will the gaseous components of the decomposition products limit the ultimate

Chikara Hayashi

1954-01-01

373

Hydrogen multicentre bonds  

NASA Astrophysics Data System (ADS)

The concept of a chemical bond stands out as a major development in the process of understanding how atoms are held together in molecules and solids. Lewis' classical picture of chemical bonds as shared-electron pairs evolved to the quantum-mechanical valence-bond and molecular-orbital theories, and the classification of molecules and solids in terms of their bonding type: covalent, ionic, van der Waals and metallic. Along with the more complex hydrogen bonds and three-centre bonds, they form a paradigm within which the structure of almost all molecules and solids can be understood. Here, we present evidence for hydrogen multicentre bonds-a generalization of three-centre bonds-in which a hydrogen atom equally bonds to four or more other atoms. When substituting for oxygen in metal oxides, hydrogen bonds equally to all the surrounding metal atoms, becoming fourfold coordinated in ZnO, and sixfold coordinated in MgO. These multicentre bonds are remarkably strong despite their large hydrogen-metal distances. The calculated local vibration mode frequency in MgO agrees with infrared spectroscopy measurements. Multicoordinated hydrogen also explains the dependence of electrical conductivity on oxygen partial pressure, resolving a long-standing controversy on the role of point defects in unintentional n-type conductivity of ZnO (refs 8-10).

Janotti, Anderson; van de Walle, Chris G.

2007-01-01

374

EFFECTS OF PARAMETER MATCH ON BONDABILITY AND RELIABILITY IN THERMOSONIC GOLD BONDING  

Microsoft Academic Search

Wire chemistry and bonding conditions are found to affect the Au-Al intermetallic compounds formation and growth. Bonding achieved when these two metals come into intimate contact between each other by interactions of ultrasonic energy, force, temperature and time. Inter diffusion of the joining metals at the interface activated the formation of stoichiometric intermetallic. This paper investigates the effects of bonding

A. Jalar; M. F. Rosle; M. A. A. Hamid

2008-01-01

375

Reduce costs with vacuum excavation  

SciTech Connect

Although vacuum excavation equipment and methods are in their infancy, this developing technology offers tremendous promise for the future. The author explains Brooklyn Union Gas Co.'s experience with five vacuum trucks and the procedures that are used. In recent years, the higher cost of natural gas has increased the need for gas utilities to reduce their operating expenses. One way, which has been successful at Brooklyn Union Gas, is the use of vacuum excavation. Although vacuum excavation equipment and techniques are in their infancy, this developing technology offers substantial savings today and tremendous promise for the future. Brooklyn Union started its vacuum digging program by locating keyhole cutoffs--small surface openings ranging from 1 ft by 1 ft to 1 1/2 ft by 1 1/2 ft (0.3 m to 0.45 m square). It is no easy task to accurately locate a service that was installed 60 years ago. Reading the street indications, locating an existing curb valve or repair opening, gaining access to the building, making a physical lineup, and using an M-scope, plus any other tools available, have produced a high success rate.

Vitale, S.A.

1983-09-01

376

On the generation and annealing of dangling bond defects in hydrogenated amorphous silicon  

Microsoft Academic Search

We show that, through the diffusive re-arrangement of Si-H bonds, the a-Si:H lattice is able to establish thermal equilibrium between the densities of band tail trapped charge carriers and dangling bond defects. When this equilibrium is disturbed by changes in temperature, carrier injection or illumination, dangling bond defects have to be generated or annealed out via H-diffusion processes. Based on

G. Mller

1988-01-01

377

On the generation and annealing of dangling bond defects in hydrogenated amorphous silicon  

Microsoft Academic Search

It is shown that, through the diffusive rearrangement of Si-H bonds, the a-Si:H lattice is able to establish thermal equilibrium between the densities of band-tail-trapped charge carriers and dangling bond defects. When this equilibrium is disturbed by changes in temperature, carrier injection, or illumination, dangling bond defects have to be generated or annealed out via H-diffusion processes. Based on the

Gerhard Mueller

1988-01-01

378

Kinetics of scrap tyre pyrolysis under vacuum conditions.  

PubMed

Scrap tyre pyrolysis under vacuum is attractive because it allows easier product condensation and control of composition (gas, liquid and solid). With the aim of determining the effect of vacuum on the pyrolysis kinetics, a study has been carried out in thermobalance. Two data analysis methods have been used in the kinetic study: (i) the treatment of experimental data of weight loss and (ii) the deconvolution of DTG (differential thermogravimetry) curve. The former allows for distinguishing the pyrolysis of the three main components (volatile components, natural rubber and styrene-butadiene rubber) according to three successive steps. The latter method identifies the kinetics for the pyrolysis of individual components by means of DTG curve deconvolution. The effect of vacuum in the process is significant. The values of activation energy for the pyrolysis of individual components of easier devolatilization (volatiles and NR) are lower for pyrolysis under vacuum with a reduction of 12K in the reaction starting temperature. The kinetic constant at 503K for devolatilization of volatile additives at 0.25atm is 1.7 times higher than that at 1atm, and that corresponding to styrene-butadiene rubber at 723K is 2.8 times higher. Vacuum enhances the volatilization and internal diffusion of products in the pyrolysis process, which contributes to attenuating the secondary reactions of the repolymerization and carbonization of these products on the surface of the char (carbon black). The higher quality of carbon black is interesting for process viability. The large-scale implementation of this process in continuous mode requires a comparison to be made between the economic advantages of using a vacuum and the energy costs, which will be lower when the technologies used for pyrolysis require a lower ratio between reactor volume and scrap tyre flow rate. PMID:19589669

Lopez, Gartzen; Aguado, Roberto; Olazar, Martn; Arabiourrutia, Miriam; Bilbao, Javier

2009-07-08

379

Partial Transient Liquid-Phase Bonding, Part I: A Novel Selection Procedure for Determining Ideal Interlayer Combinations, Validated Against Al2O3 PTLP Bonding Experience  

NASA Astrophysics Data System (ADS)

Partial transient liquid-phase (PTLP) bonding is a bonding process that can bond hard-to-join materials, such as ceramics. The process uses a multi-layer interlayer composed of a thick refractory core and thin diffusant layers on each side. Upon heating, the diffusant material melts, and diffusion occurs until the liquid isothermally solidifies. Selecting interlayer materials is a key problem in producing strong, reliable PTLP bonds; materials are usually selected empirically or system by system. This article presents a novel selection procedure that provides a generalized, comprehensive, first-principles-based approach. Components of the selection procedure are linked directly to key characteristics of PTLP bonding. A filtering routine that provides structure for the selection procedure is summarized in this article and detailed in a companion article. Specific capabilities of the routine, such as non-symmetric bonds, add to its effectiveness in identifying additional PTLP bond candidates. By way of example, output from the selection procedure, in conjunction with sessile drop data, is used to analyze all Al2O3 PTLP bonds in the current literature. All analyzed bonds are included in various outputs from the selection procedure, validating its comprehensiveness. Also, Al2O3 PTLP bonds are analyzed as a whole, leading to the identification of important trends that result in increased bond strength. Finally, additional interlayer combinations for PTLP bonding of Al2O3 are presented based on output from the selection procedure and existing sessile drop data.

Cook, Grant O.; Sorensen, Carl D.

2013-09-01

380

Impedances of Laminated Vacuum Chambers  

SciTech Connect

First publications on impedance of laminated vacuum chambers are related to early 70s: those are of S. C. Snowdon [1] and of A. G. Ruggiero [2]; fifteen years later, a revision paper of R. Gluckstern appeared [3]. All the publications were presented as Fermilab preprints, and there is no surprise in that: the Fermilab Booster has its laminated magnets open to the beam. Being in a reasonable mutual agreement, these publications were all devoted to the longitudinal impedance of round vacuum chambers. The transverse impedance and the flat geometry case were addressed in more recent paper of K. Y. Ng [4]. The latest calculations of A. Macridin et al. [5] revealed some disagreement with Ref. [4]; this fact stimulated us to get our own results on that matter. Longitudinal and transverse impendances are derived for round and flat laminated vacuum chambers. Results of this paper agree with Ref. [5].

Burov, A.; Lebedev, V.; /Fermilab

2011-06-22

381

Mathematical theory of physical vacuum  

NASA Astrophysics Data System (ADS)

This article sets out mathematical basics of unifying fundamental physical theory, with a single postulate of nonvoid physical vacuum. It will be shown that all basic equations of classical electrodynamics, quantum mechanics and gravitation theory could be derived from two nonlinear equations, which define dynamics of physical vacuum in three-dimensional Euclidean space and, in turn, are derived from equations of Newtonian mechanics. Through the characteristics of physical vacuum, namely its density and propagation velocity of various densitys perturbations, such principal physical conceptions as matter and antimatter, electric, magnetic and gravitational fields, velocity of light, electron, photon and other elementary particles, internal energy, mass, charge, spin, quantum properties, Planck constant and fine structure constant will have clear and sane definitions.

Magnitskii, N. A.

2011-06-01

382

Gravity-Induced Vacuum Dominance  

SciTech Connect

It has been widely believed that, except in very extreme situations, the influence of gravity on quantum fields should amount to just small, subdominant contributions. This view seemed to be endorsed by the seminal results obtained over the last decades in the context of renormalization of quantum fields in curved spacetimes. Here, however, we argue that this belief is false by showing that there exist well-behaved spacetime evolutions where the vacuum energy density of free quantum fields is forced, by the very same background spacetime, to become dominant over any classical energy-density component. By estimating the time scale for the vacuum energy density to become dominant, and therefore for backreaction on the background spacetime to become important, we argue that this (infrared) vacuum dominance may bear unexpected astrophysical and cosmological implications.

Lima, William C. C.; Vanzella, Daniel A. T. [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, CEP 15980-900, Sao Carlos, SP (Brazil)

2010-04-23

383

Diffusion and phase transformation behavior in poly-synthetically-twinned (PST) titanium-aluminum/titanium diffusion couple  

NASA Astrophysics Data System (ADS)

Motivated by the great potential applications of gamma titanium aluminide based alloys and the important effect of diffusion on the properties of gamma-TiAl/alpha2-Ti3Al two-phase lamellar structure, we conduct this thesis research to explore the microstructural evolution and interdiffusion behavior, and their correlations in multi-phase solid state diffusion couples made up of pure titanium and polysynthetically-twinned (PST) Ti-49.3 at.% Al "single" crystal, in the temperature range of 973--1173 K. The diffusion couples are prepared by high vacuum hot-pressing, with the diffusion direction parallel to the lamellar planes. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) are employed to observe the microstructure at various interfaces/interphases. A reaction zone (RZ) of polycrystalline alpha 2-Ti3Al phase forms along the PST Ti-Al/Ti bonding interface having a wavy interface with the PST crystal and exhibits deeper penetration in alpha2 lamellae, consisting of many fine alpha2 and secondary gamma laths, than in primary gamma lamellae. Direct measurement of the RZ thickness on SEM back-scattered electron images reveals a parabolic growth of the RZ, indicating a macroscopically diffusion-controlled growth. Concentration profiles from Ti, through the RZ, into the alpha2 lamellae of the PST crystal are measured by quantitative energy-dispersive x-ray spectroscopy (EDS) in a scanning transmission electron microscope (STEM). A plateau of composition adjacent to the RZ/(mixed alpha2 lath in PST) interface forms in the deeply penetrated RZ grains, implying a diffusion barrier crossing the interface and some extent of interface control in the RZ grain growth. The interdiffusion coefficient is evaluated both independent of composition and as a function of composition. No significant concentration dependence of the interdiffusion coefficients is observed using Boltzmann-Matano analysis. The temperature dependence of the interdiffusion coefficients obeys the Arrhenius relationship with a pre-exponential factor of D 0 = (7.56 +/- 7.14) x 10-5 m2/s and an activation enthalpy of Q = 255.6+8.9-8.3 kJ/mol = (2.65 +/- 0.09) eV/atom. The initial nucleation stage of the RZ grains plays an important role in the later microstructural evolution as does the local mass balance. The interfacial energy and the strain energy in the deeply penetrated RZ grains are possible reasons for the plateau.

Pan, Ling

384

Photocarrier generation and transport in ?-bonded polysilanes  

NASA Astrophysics Data System (ADS)

Polysilanes, even those containing no ? electrons, are found to be excellent photoconductors. In the materials studied to date, only holes are mobile but they have a well-defined mobility of about 10-4 cm2/Vat room temperature. In poly(phenylmethylsilane), the material we have studied most intensely, the hole-generation quantum efficiency is about 1% at high electric fields and the experimental results indicate that the holes are generated when excitons, formed when a photon is absorbed, diffuse to the surface of the film. The exciton diffusion length is found to be 500 Å. These results help confirm the existence of extensive conjugation among ? bonds in polysilanes.

Kepler, R. G.; Zeigler, J. M.; Harrah, L. A.; Kurtz, S. R.

1987-02-01

385

Observations of the Vacuum Arc and Metal Transfer During Vacuum Consumable Arc Remelting.  

National Technical Information Service (NTIS)

Observations have been made using high speed color photography of the vacuum arc and electrode surfaces during vacuum consumable arc remelting of a maraging steel alloy. Events on the film are coordinated with electrical signals from the vacuum arc. Based...

F. J. Zanner

1979-01-01

386

Quantum vacuum magneto-optics  

NASA Astrophysics Data System (ADS)

In this article we report on the recent experimental activities concerning the magneto-optics of quantum vacuum performed by our team based at the LNCMI of Toulouse. In particular, we will deal with quantum vacuum Cotton-Mouton and inverse Cotton-Mouton effects which have been predicted in the framework of Quantum electrodynamics. Finally, we will present our experiment on photon oscillations into massive particles in the presence of a magnetic field, an effect that could be a signature of physics beyond the standard model.

Battesti, Rmy; Berceau, Paul; Fouch, Mathilde; Rikken, Geert L. J. A.; Rizzo, Carlo

2013-01-01

387

Vaneless diffusers  

NASA Astrophysics Data System (ADS)

The influence of vaneless diffusers on flow in centrifugal compressors, particularly on surge, is discussed. A vaneless diffuser can demonstrate stable operation in a wide flow range only if it is installed with a backward leaning blade impeller. The circumferential distortion of flow in the impeller disappears quickly in the vaneless diffuser. The axial distortion of flow at the diffuser inlet does not decay easily. In large specific speed compressors, flow out of the impeller is distorted axially. Pressure recovery of diffusers at distorted inlet flow is considerably improved by half guide vanes. The best height of the vanes is a little 1/2 diffuser width. In small specific speed compressors, flow out of the impeller is not much distorted and pressure recovery can be predicted with one-dimensional flow analysis. Wall friction loss is significant in narrow diffusers. The large pressure drop at a small flow rate can cause the positive gradient of the pressure-flow rate characteristic curve, which may cause surging.

Senoo, Y.

388

Surface Impurities Encapsulated by Silicon Wafer Bonding  

NASA Astrophysics Data System (ADS)

Wafer bonding techniques are shown to provide an important addition to methods used for the detection of residual impurities on the surfaces of polished and cleaned silicon wafers. Impurities were encapsulated in the interface made by wafer bonding, and analyzed by SIMS depth profiling. Significant concentrations of H, C, N, O, F and Cl were detected. The concentration of these elements did not change after two hour wafer bonding anneals in the range of 200C to 800C. For anneals at 1000C and above both the diffusion of H and C from the bonded interface, and the aggregation of N and O were observed. It was confirmed by IR absorption and HR-TEM that oxygen in CZ crystals outdiffuses into the bonded interface and produces an SiO2 layer. Low-oxygen FZ wafers were used as a reference comparison. Elements such as F and Cl contained in the chemicals used to clean the wafers remained fixed at the bonded interface for the entire temperature range tested.

Abe, Takao; Uchiyama, Atsuo; Yoshizawa, Katsuo; Nakazato, Yasuaki; Miyawaki, Mamoru; Ohmi, Tadahiro

1990-12-01

389

The hydrogen bond  

Microsoft Academic Search

The concept of the hydrogen bond is a century old but remains youthful because of its vital role in so many branches of science and because of continued advances in experiment, theory and simulation. We discuss the structural and energetic characteristics of normal hydrogen bonds XHY as well as some exceptions to the normal, including proton-shared and ion-pair bonds. We

A. D. Buckingham; J. E. Del Bene; S. A. C. McDowell

2008-01-01

390

BONDING ALUMINUM METALS  

DOEpatents

A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

Noland, R.A.; Walker, D.E.

1961-06-13

391

Semiconductor Wafer Bonding  

Microsoft Academic Search

When mirror-polished, flat, and clean wafers of almost any material are brought into contact at room temperature, they are locally attracted to each other by van der Waals forces and adhere or bond. This phenomenon is referred to as wafer bonding. The most prominent applications of wafer bonding are silicon-on-insulator (SOI) devices, silicon-based sensors and actuators, as well as optical

U. Gosele; Q.-Y. Tong

1998-01-01

392

Femtosecond dynamics in hydrogen-bonded solvents  

SciTech Connect

We present results on the ultrafast dynamics of pure hydrogen-bonding solvents, obtained using femtosecond Fourier-transform optical-heterodyne-detected, Raman-induced Kerr effect spectroscopy. Solvent systems we have studied include the formamides, water, ethylene glycol, and acetic acid. Inertial and diffusive motions are clearly resolved. We comment on the effect that such ultrafast solvent motions have on chemical reactions in solution.

Castner, E.W. Jr.; Chang, Y.J.

1993-09-01

393

One Bond Strategy  

NSDL National Science Digital Library

Provided by SmartMoney.com (see the May 20, 1999 Scout Report for Business & Economics), this quick and easy yet thorough guide takes readers through the process of developing a bond portfolio. At the site, users will find help on deciding how much to invest in bonds, how to divide their portfolio, and tips on investing for both income and profit. First, however, visitors might want to wet their feet in the bond primer section, which covers all the basics, explains the yield curve, offers a calculator and glossary, and throws in "ten things your broker won't tell you about bonds" for good measure.

2001-01-01

394

Minkowski vacuum stress tensor fluctuations  

Microsoft Academic Search

We study the fluctuations of the stress tensor for a massless scalar field in two- and four-dimensional Minkowski spacetime in the vacuum state. Covariant expressions for the stress tensor correlation function are obtained as sums of derivatives of a scalar function. These expressions allow one to express spacetime averages of the correlation function as finite integrals. We also study the

Thomas A. Roman; L. H. Ford

2005-01-01

395

Vacuum Distillation of Americium Metal.  

National Technical Information Service (NTIS)

High-purity americium metal has been distilled in multigram quantities from a plutonium-americium alloy. The procedure consisted of a two-stage vacuum distillation carried out at 1200 exp 0 C and 10 exp -6 torr pressure. Four batches of americium metal we...

J. W. Berry J. B. Knighton C. A. Nannie

1982-01-01

396

Quantum Vacuum Structure and Cosmology  

SciTech Connect

Contemporary physics faces three great riddles that lie at the intersection of quantum theory, particle physics and cosmology. They are: (1) The expansion of the universe is accelerating - an extra factor of two appears in the size; (2) Zero-point fluctuations do not gravitate - a matter of 120 orders of magnitude; and (3) The 'True' quantum vacuum state does not gravitate. The latter two are explicitly problems related to the interpretation and the physical role and relation of the quantum vacuum with and in general relativity. Their resolution may require a major advance in our formulation and understanding of a common unified approach to quantum physics and gravity. To achieve this goal we must develop an experimental basis and much of the discussion we present is devoted to this task. In the following, we examine the observations and the theory contributing to the current framework comprising these riddles. We consider an interpretation of the first riddle within the context of the universe's quantum vacuum state, and propose an experimental concept to probe the vacuum state of the universe.

Rafelski, Johann; Labun, Lance; Hadad, Yaron; /Arizona U. /Munich U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC

2011-12-05

397

Vacuum-injection-molding processing  

SciTech Connect

An improved processing technique for the manufacture of glass or glass-ceramic headers has been developed. Vacuum-injection molding is a relatively easy processing technique that has been used successfully in the fabrication of several different advantages in certain applications over the present fabrication process which uses glass preforms.

Kramer, D.P.; Massey, R.T.

1982-01-01

398

A simple triggered vacuum gap  

Microsoft Academic Search

A simple triggered vacuum gap has previously been described by the authors in this journal (see ibid., vol.5, 415, 1972). Further studies have resulted in improvement of the performance with regard to sensitivity and consistency of the trigger characteristics and immunity from bridging due to metal particles eroded from the arc. The earlier design suffered from rather frequent bridging of

N. Vidyardhi; R. S. N. Rau

1973-01-01

399

High Temperature Ultrahigh Vacuum Valves.  

National Technical Information Service (NTIS)

All-metal valves heatable up to 300 to 400 C in closed and open position were developed for handling aggressive gases such as UF6 in high vacuum technology. Sealing aspects of valves with large nominal width, such as transfer valve NW 150 and corner valve...

W. Baechler G. Jokisch H. P. Kabelitz K. Teutenberg

1976-01-01

400

Vacuum pumping system for TPX  

SciTech Connect

The design of the vacuum pumping system for is discussed, and progress in the research and development effort is summarized. The TPX vacuum system will use cryocondensation pumps for hydrogenic divertor pumping and turbomolecular pumps for torus evacuation, glow discharge cleaning, and deuterium-helium divertor pumping. A set of poloidally and toroidally symmetric vacuum ducts will connect the torus to the vacuum pumps; this symmetry will permit simultaneous equal pumping speed at the upper and lower divertors, and it will minimize toroidal variations in divertor pumping speed. At the divertor plena the total cryocondensation pumping speed for D{sub 2} at 65 C and 1 mTorr will be 80 m{sup 3}/s and the total turbomolecular pumping speed for D{sub 2} or He at 65 C and 1 mTorr will be 18 m{sup 3}/s; the system will be compatible with upgrades to improve pumping speed, to operate continuously, or to operate with D-T fuel. The cryocondensation pumps will be custom units capable of completing a low temperature regeneration cycle in 1 hour.

St. Onge, K.D.

1995-12-31

401

Vacuum Pyrolysis of Sodium Stearate.  

National Technical Information Service (NTIS)

Vacuum pyrolysis of sodium stearate was studied to provide useful information for Green River oil shale pyrolysis. Sodium stearate is a typical compound of carboxylic acid salts amounting to 3.6% of total organic materials in the oil shale by methanol ext...

S. L. Chong

1985-01-01

402

Sizing the vacuum chambers conservatively  

SciTech Connect

This note will examine many different scenarios, both optimistic and pessimistic, for the performance of the B Factory. The primary reason for this is to establish limits for the emittances in the two rings. This information will be needed to ensure that the vacuum chambers are sized to permit the maximum flexibility. 3 refs., 3 tabs.

Hutton, A.

1990-05-21

403

APS storage ring vacuum system  

Microsoft Academic Search

The advanced Photon Source synchrotron radiation facility, under construction at the argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's experimental program. The Storage Ring's 1104 m circumference is divided into 40 functional sectors. The sectors include vacuum, beam transport, control, acceleration and insertion device components.

R. C. Niemann; R. Benaroya; M. Choi; R. J. Dortwegt; G. A. Goeppner; J. Gonczy; C. Krieger; J. Howell; R. W. Nielsen; B. Roop; R. B. Wehrle

1991-01-01

404

HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM  

SciTech Connect

The objective of this project is to improve the productivity and lower the expense of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCBs, and lead-based paint and provides worker protection by continuously recycling the material and dust for the decontamination tasks. The proposed work would increase the cleaning rate and provide safe and cost-effective decontamination of the DOE sites. This work focuses on redesigning and improving existing vacuum blasting technology including blast head nozzles, ergonomic handling of the blast head by reducing its weight; brush-ring design, vacuum level regulator, efficiency of the dust separator, and operational control sensors. The redesign is expected to enhance the productivity and economy of the vacuum blasting system by at least 50% over current vacuum blasting systems. There are three phases in the project. Phase I consists of developing and testing mathematical models. Phase II consists of pre-prototype design and fabrication and pre-prototype unit testing. Phase III consists of prototype design and field verification testing. In phase I, mathematical models are developed and analyzed for the nozzle, blast head, wind curtain, and dust separator, first as individual devices and then combined as an integrated model. This allows study of respective airflow and design parameters. The Contractor shall, based on the results of the mathematical modeling studies, design experimental models of the components and test these models. In addition, the Contractor shall develop sensors to detect the relationship of the blast head to the blast surfaces and controls to minimize the dependency on an operator's skill and judgment to obtain optimum positioning, as well as real-time characterization sensors to determine as the blast head is moving the depth to which coatings must be removed, thereby improving production and minimizing waste. In phase II, the Contractor shall design and construct a pre-prototype of the nozzle, blast head with wind curtain, sensors, and dust separator and test this system to assess the performance of the new design under controlled conditions at the contractor's facility. In phase III, the Contractor shall design and construct a prototype of the High Productivity Vacuum Blasting System, based on the results of the pre-prototype design and testing performed. This unit will be a full-scale prototype and will be tested at a designated Department of Energy (DOE) facility. Based on the results, the system performance, the productivity, and the economy of the improved vacuum blasting system will be evaluated.

William S. McPhee

1999-05-31

405

Eutectic bonding of austenitic stainless steel 316L to magnesium alloy AZ31 using copper interlayer  

Microsoft Academic Search

The eutectic bonding of magnesium alloy (AZ31) to austenitic stainless steel alloy (316L) was performed using pure Cu interlayers.\\u000a The effect of hold time on the microstructural developments across the joint region and the related effect on bond shear strength\\u000a were studied at a bonding temperature of 530C. The bonding process took place through a sequential occurrence of solid-state\\u000a diffusion

Waled M. Elthalabawy; Tahir I. Khan

2011-01-01

406

Vacuum arc deposited DLC based coatings  

SciTech Connect

The great interest in the use of diamond-like carbon (DLC) films as a coating material is justified by the superior wear resistance and hardness, chemical inertness, and very low friction coefficients of these coatings. Vacuum arc deposition is well suited to prepare superhard films with high sp{sup 3}/sp{sup 2} ratios. However, the high level of internal stresses originating during growth prevents the deposition of thick films, and their hardness makes it difficult for DLC layers to comply with substrate deformations. In order to overcome these limitations, different approaches are possible. Multilayer structures are one means to maintain the surface mechanical properties of the DLC while relieving the internal stresses. Another possibility is to dope the DLC films in order to reduce the internal stress and to stabilize the desirable sp{sup 3} bonds to higher temperatures. At higher doses of dopants, the formation of nanocrystals is possible and the properties of the coatings change drastically. All these approaches were investigated on films prepared by cathodic arc and a synthesis of the results is presented here.

Monteiro, Othon R.; Delplancke-Ogletree, Marie-Paule

2002-05-01

407

Development of a Vacuum Superinsulation Panel.  

National Technical Information Service (NTIS)

A vacuum superinsulation system with pressure resistant, temperature resistant thermal insulation of high efficiency was developed. Vacuum-tight sealing, compression and evacuation of powder filling as well as special material investigations were performe...

H. Timm D. Seefeldt C. Nitze

1983-01-01

408

Development of a Vacuum Superinsulation Panel.  

National Technical Information Service (NTIS)

After completion of the investigations the vacuum-insulated panel is available as prototype. The aim of the investigations was to optimize and to finalize the vacuum superinsulation system with regard to a pressure-resistant, temperature-resistant thermal...

H. Timm D. Seefeldt C. Nitze

1983-01-01

409

Materials for ultra-high vacuum  

SciTech Connect

This report discusses materials for use in ultrahigh vacuum systems of 1 {times} 10{sup {minus}9} Torr or lower. The author briefly discusses alloys, solders, insulators and joining methods for vacuum systems. (JDL)

Lee, G.

1989-08-15

410

14 CFR 29.1433 - Vacuum systems.  

Code of Federal Regulations, 2010 CFR

...pressure in the discharge lines from the vacuum air pump when the delivery temperature of the air becomes unsafe. (b) Each vacuum air system line and fitting on the discharge side of the pump that might contain flammable...

2010-01-01

411

14 CFR 29.1433 - Vacuum systems.  

Code of Federal Regulations, 2010 CFR

...pressure in the discharge lines from the vacuum air pump when the delivery temperature of the air becomes unsafe. (b) Each vacuum air system line and fitting on the discharge side of the pump that might contain flammable...

2009-01-01

412

Visionlearning: Chemical Bonding  

NSDL National Science Digital Library

This digital learning module provides an easily-understood overview of chemical bonding for users with little formal background in chemistry or physics. It explores ionic bonding through the example of sodium (an alkali metal) reacting with chlorine gas to produce common table salt. A concept simulation further illustrates the process.

Carpi, Anthony

2011-07-12

413

Halogen bonding: Recent advances  

Microsoft Academic Search

Halogen bonding (XB), as a directional interaction between covalently bound halogen atoms (XB donor) and Lewis bases (A, XB acceptor), has been recently intensively investigated as a powerful tool in crystal engineering. After a short review on the origin and general features of halogen bonding, current developments towards (i) the elaboration of three-dimensional networks, (ii) the interaction with anionic XB

Marc Fourmigu

2009-01-01

414

The Sibling Bond.  

ERIC Educational Resources Information Center

|The relationships among brothers and sisters are infinitely varied, but whatever their characteristics, these bonds last throughout life. This book examines the sibling relationship as a distinctive emotional, passionate, painful, and solacing power. Chapter 1, "Unraveling the Sibling Bond," addresses research on siblings and development of the

Bank, Stephen P.; Kahn, Michael D.

415

The dissociative bond.  

PubMed

Dissociation leaves a psychic void and a lingering sense of psychic absence. How do 2 people bond while they are both suffering from dissociation? The author explores the notion of a dissociative bond that occurs in the aftermath of trauma--a bond that holds at its core an understanding and shared detachment from the self. Such a bond is confined to unspoken terms that are established in the relational unconscious. The author proposes understanding the dissociative bond as a transitional space that may not lead to full integration of dissociated knowledge yet offers some healing. This is exemplified by R. Prince's (2009) clinical case study. A relational perspective is adopted, focusing on the intersubjective aspects of a dyadic relationship. In the dissociative bond, recognition of the need to experience mutual dissociation can accommodate a psychic state that yearns for relationship when the psyche cannot fully confront past wounds. Such a bond speaks to the need to reestablish a sense of human relatedness and connection when both parties in the relationship suffer from disconnection. This bond is bound to a silence that becomes both a means of protection against the horror of traumatic memory and a way to convey unspoken gestures toward the other. PMID:23282044

Gordon, Nirit

2013-01-01

416

Planning Successful Bond Campaigns.  

ERIC Educational Resources Information Center

|This document contains specific recommendations for conducting bond campaigns. It outlines the three major considerations of any bond campaign: (1) committee organization and appointment; (2) time lines; and (3) getting out the vote. The publication focuses on the need for total community involvement and outlines some of the components for

North Carolina State Dept. of Public Instruction, Raleigh. Div. of School Support.

417

Bond-quality characterization of silicon-glass anodic bonding  

Microsoft Academic Search

A simple testing method is presented that allows the comparison of the bond quality for anodically bonded wafers. An array of parallel metal lines of predetermined thickness is formed on a glass wafer. The estimation of the bond quality can be performed by visual inspection after the bonding. This method enables comparison of the anodic-bonding process performance for different glasses,

Svetlana Tatic-Lucic; John Ames; Bill Boardman; David McIntyre; Paul Jaramillo; Larry Starr; Myoungho Lim

1997-01-01

418

Wood Bond Testing  

NASA Astrophysics Data System (ADS)

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.

1989-01-01

419

Vacuum-plasma technology for obtaining protective coatings from complex alloys  

Microsoft Academic Search

Abtract This work is devoted to obtaining coatings from M - Cr - Al - Y alloys by the vacuum-plasma method using 10 103 eV particle energies. In this energy range we can realize predominant precipitation (condensation) of the coating, ionic (dry) etching, or the formation of a diffuse layer on the surface depending on the particle type and the

S. A. Muboyadzhan; E. N. Kablov; S. A. Budinovskii

1995-01-01

420

Fabrication and lateral transport measurement of gold nanowires in ultra-high vacuum  

Microsoft Academic Search

A technique for fabricating gold nanowires on a clean Si(111) surface in ultra-high vacuum has been developed. Gold was transferred from the cantilever tip of an atomic force microscope (AFM) onto a sample surface during contact mode operation, due to the chemical activeness of clean silicon surfaces and diffusiveness of gold at room temperature. This technique allows production of seemingly

Takashi Uchihashi; Urs Ramsperger; Hitoshi Nejoh

2001-01-01

421

Use of a Novel Fluorinated Organosulfur Compound To Isolate Bacteria Capable of Carbon-Sulfur Bond Cleavage  

Microsoft Academic Search

The vacuum residue fraction of heavy crudes contributes to the viscosity of these oils. Specific microbial cleavage of COS bonds in alkylsulfide bridges that form linkages in this fraction may result in dramatic viscosity reduction. To date, no bacterial strains have been shown conclusively to cleave COS bonds within alkyl chains. Screening for microbes that can perform this activity was

Jonathan D. Van Hamme; Phillip M. Fedorak; Julia M. Foght; Murray R. Gray; Heather D. Dettman

2004-01-01

422

The History of Vacuum Regulation Technology  

Microsoft Academic Search

An inordinate amount of time, money and anguish has been invested in changing the ways that vacuum is controlled in milking machines. These extraordinary efforts have not resulted in a commensurate improvement in milking performance. There are two fundamental methods of influencing the vacuum in the milking machine: 1) a device to regulate 'system' vacuum, usually located near the receiver

Douglas J. Reinemann

423

Drying leather with vacuum and toggling sequentially  

Technology Transfer Automated Retrieval System (TEKTRAN)

We investigated a drying method that will enable leather to be dried under vacuum and stretch sequentially to improve area yield. Vacuum drying offers fast speed at a low temperature, which would be advantageous to heat-vulnerable chrome-free leather. Adding a toggle action after vacuum drying cou...

424

High rate vacuum deposition of polymer electrolytes  

Microsoft Academic Search

Two new, high rate, vacuum processes have been developed for the deposition of polymer electrolyte layers on wide web substrates. One method involves the vacuum extrusion of monomer salt solutions followed by e-beam or ultraviolet (UV) curing. The second method involves the vacuum flash evaporation of the monomer salt solution followed by e-beam or UV curing. Each method is compatible

J. D. Affinito; M. E. Gross; C. A. Coronado; G. C. Dunham; P. M. Martin

1996-01-01

425

Development of a vacuum superinsulation panel  

Microsoft Academic Search

A vacuum superinsulation system with pressure resistant, temperature resistant thermal insulation of high efficiency was developed. Vacuum-tight sealing, compression and evacuation of powder filling as well as special material investigations were performed. Applications include coverings of linings with high temperature and\\/or pressure requirements. A vacuum insulated panel prototype was built.

H. Timm; D. Seefeldt; C. Nitze

1983-01-01

426

Rotary bayonets for cryogenic and vacuum service  

Microsoft Academic Search

Rotary bayonets were designed, tested, and installed for liquid nitrogen, liquid argon, and vacuum service. This paper will present the design, testing, and service record for two sizes of vacuum jacketed cryogenic rotary bayonets and two sizes of vacuum service rotary bayonets. Materials used in construction provide electrical isolation across the bayonet joint. The joint permits 360 degrees of rotation

R. A. Rucinski; K. D. Dixon; R. Krasa; K. J. Krempetz; G. T. Mulholland; G. R. Trotter; J. B. Urbin

1993-01-01

427

Increasing electric standoff between conductors in vacuum  

Microsoft Academic Search

Pulsed power systems have limitations on power delivery. One limitation is the breakdown potential between conductive surfaces in vacuum. In a vacuum breakdown, a vacuum arc is generated between the surfaces. The microscopic limit on the breakdown potential is at the onset of field emission from the surface. The microscopic field for the onset of field emission is in excess

Donald Pellinen

2007-01-01

428

Charging and Discharge in Vacuum and Space  

Microsoft Academic Search

Success of vacuum electronic devices often depends on secure electrical insulation of the components. The presence of solid insulator significantly decreases the insulation strength of the vacuum apparatus. Charging of solid insulator in the pre-breakdown process enhances the electric field near the triple junction and leads to electrical discharge. Electrostatic discharge (ESD) on spacecraft surface is similar to other vacuum

Mengu Cho

2007-01-01

429

14 CFR 25.1433 - Vacuum systems.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Vacuum systems. 25.1433 Section...Miscellaneous Equipment § 25.1433 Vacuum systems. There must be means...pressure in the discharge lines from the vacuum air pump when the delivery temperature...

2010-01-01

430

14 CFR 25.1433 - Vacuum systems.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Vacuum systems. 25.1433 Section...Miscellaneous Equipment § 25.1433 Vacuum systems. There must be means...pressure in the discharge lines from the vacuum air pump when the delivery temperature...

2009-01-01

431

Transient liquid phase bonding of ferritic oxide dispersion strengthened alloys  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened (ODS) alloys possess excellent properties including resistance to oxidation, corrosion, creep and thermal fatigue. In addition, ferritic ODS alloys exhibit resistance to void swelling and are of particular interest to the nuclear industry. The present study involves the joining of fuel cans to end caps that will be utilized in the nuclear industry. Mechanically alloyed (MA) ODS alloys possess coarse columnar grain structure strengthened with nanosize yttria dispersoids. In that past, fusion welding techniques resulted in microstructural disruption leading to poor joints. This work investigated joining of two ferritic MA ODS alloys, MA956 and PM2000, using; (a) Transient liquid phase (TLP) bonding and (b) Solid-state diffusion bonding. TLP bonds were prepared with MA956 and PM2000 in the unrecrystallized and recrystallized conditions using electron beam physical vapor deposited (EBPVD) boron thin films as interlayers. The use of thin interlayers reduced the amount of substrate dissolution and minimized the bondline microstructural disruption. Different bond orientations were also investigated. Successful bonds with better microstructural continuity were obtained when substrates were joined in the unrecrystallized condition followed by post bond recrystallization heat treatment with the substrate faying surface aligned along the working (extrusion or rolling) direction than when substrates were aligned perpendicular to the working direction. This was attributed to the number of yttria stringers cut by the bondline, which is less when the substrate faying surface is lying parallel to the working direction than when the substrate faying surface is lying perpendicular to the working direction. Solid-state diffusion bonding was conducted using MA956 and PM2000 in the unrecrystallized and recrystallized conditions. Bonding occurred only when an unrecrystallized substrate was involved. Bonding occurred at unusually low stresses. This may be attributed to the grain boundary diffusion, owing to submicron grain size of the unrecrystallized substrates. Post bond heat treatment was conducted in order to induce recrystallization in the bonds. Room temperature mechanical testing was conducted on the bonds and the bulk. Bond shear strengths and tensile strengths of up to 80% and 110% of bulk, respectively, were obtained. Defects in the bulk material such as porosity and unwanted fine grain formation were observed. Pore formation at the bondline during post bond heat treatment seems to decrease the bond strength. These defects were attributed to prior thermomechanical history of the materials.

Krishnardula, Venu Gopal

432

49 CFR 570.56 - Vacuum brake assist unit and vacuum brake system.  

Code of Federal Regulations, 2010 CFR

... 6 2010-10-01 2010-10-01 false Vacuum brake assist unit and vacuum brake system. 570.56 Section 570.56 ...GVWR of More Than 10,000 Pounds § 570.56 Vacuum brake assist unit and vacuum brake system....

2010-10-01

433

49 CFR 570.56 - Vacuum brake assist unit and vacuum brake system.  

Code of Federal Regulations, 2010 CFR

... 6 2009-10-01 2009-10-01 false Vacuum brake assist unit and vacuum brake system. 570.56 Section 570.56 ...GVWR of More Than 10,000 Pounds § 570.56 Vacuum brake assist unit and vacuum brake system....

2009-10-01

434

Cold vacuum drying residual free water test description  

SciTech Connect

Residual free water expected to remain in a Multi-Canister Overpack (MCO) after processing in the Cold Vacuum Drying (CVD) Facility is investigated based on three alternative models of fuel crevices. Tests and operating conditions for the CVD process are defined based on the analysis of these models. The models consider water pockets constrained by cladding defects, water constrained in a pore or crack by flow through a porous bed, and water constrained in pores by diffusion. An analysis of comparative reaction rate constraints is also presented indicating that a pressure rise test can be used to show MCO`s will be thermally stable at operating temperatures up to 75 C.

Pajunen, A.L.

1997-12-23

435

Holographic diffusers  

NASA Astrophysics Data System (ADS)

Diffusers are playing an increasingly important role in optics as a means to either improve uniformity of light applied for illumination of an object, or to improve visibility of an image created by an optical system from a wider range of angles. Probably the most popular applications of the first kind are milky light bulbs commonly used as light sources in our houses or flat panel displays with backlight illumination used in portable computers. The best known application of the second kind is an ordinary wall used as a screen for slide or film projector. Other examples of this type are diffusers in the view finding systems of some photographic and film cameras and in a variety of rear image projection systems (like microfiche readers or rear TV projection systems, for example). It is obvious, in this context, that demand for diffusers will increase with expansion of such systems.

Pawluczyk, Romuald

1994-01-01

436

A vacuum disengager for tritium removal from HYLIFE-II Reactor Flibe  

SciTech Connect

We have designed a vacuum disengager system to remove tritium from the Flibe (Li{sub 2}BeF{sub 4}) molten salt coolant of the HYLIFE-II fusion reactor. There is a two-stage vacuum disengager in each of three intermediate heat exchanger (IHX) loops. Each stage consists of a vacuum chamber 4 m in diameter and 7 m tall. As 0.2 mm diameter molten salt droplets fall vertically downward into the vacuum, most of the tritium diffuses out of the droplets and is pumped away. A fraction {Phi} {approximately}10{sup {minus}5} of the 8.6 MCi/day tritium source (from breeding in the Flibe and from unburned fuel) remains in the Flibe as it leaves the vacuum disengagers, and about 21% of that permeates into the intermediate coolant loop, so about 20 Ci/day leak into the steam system. With Flibe primary coolant and a vacuum disengager, it appears that an intermediate coolant loop is not needed to prevent tritium from leaking into the steam system. An experiment is needed to demonstrate Flibe vacuum disengager operation.

Dolan, T.J.; Longhurst, G.R. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Garcia-Otero, E. (Missouri Univ., Columbia, MO (United States). Dept. of Nuclear Engineering)

1992-01-01

437

A vacuum disengager for tritium removal from HYLIFE-II Reactor Flibe  

SciTech Connect

We have designed a vacuum disengager system to remove tritium from the Flibe (Li{sub 2}BeF{sub 4}) molten salt coolant of the HYLIFE-II fusion reactor. There is a two-stage vacuum disengager in each of three intermediate heat exchanger (IHX) loops. Each stage consists of a vacuum chamber 4 m in diameter and 7 m tall. As 0.2 mm diameter molten salt droplets fall vertically downward into the vacuum, most of the tritium diffuses out of the droplets and is pumped away. A fraction {Phi} {approximately}10{sup {minus}5} of the 8.6 MCi/day tritium source (from breeding in the Flibe and from unburned fuel) remains in the Flibe as it leaves the vacuum disengagers, and about 21% of that permeates into the intermediate coolant loop, so about 20 Ci/day leak into the steam system. With Flibe primary coolant and a vacuum disengager, it appears that an intermediate coolant loop is not needed to prevent tritium from leaking into the steam system. An experiment is needed to demonstrate Flibe vacuum disengager operation.

Dolan, T.J.; Longhurst, G.R. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Garcia-Otero, E. [Missouri Univ., Columbia, MO (United States). Dept. of Nuclear Engineering

1992-09-01

438

Taming the {alpha}-vacuum  

SciTech Connect

An interacting scalar field theory in de Sitter space appears to be nonrenormalizable for a generic {alpha}-vacuum state. This pathology arises since the usual propagator used allows for a constructive interference among propagators in loop corrections, which produces divergences that are not proportional to standard counterterms. This interference can be avoided by defining a new propagator for the {alpha}-vacuum based on a generalized time-ordering prescription. The generating functional associated with this propagator contains a source that couples to the field both at a point and at its antipode. To one loop order, we show that a set of theories with very general antipodal interactions is causal and renormalizable.

Collins, Hael; Holman, R. [Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

2004-10-15

439

Decoherence delays false vacuum decay  

NASA Astrophysics Data System (ADS)

We show that gravitational interactions between massless thermal modes and a nucleating Coleman-de Luccia bubble may lead to efficient decoherence and strongly suppress metastable vacuum decay for bubbles that are small compared to the Hubble radius. The vacuum decay rate including gravity and thermal photon interactions has the exponential scaling \\Gamma \\sim \\Gamma _{CDL}^{2}, where ?CDL is the Coleman-de Luccia decay rate neglecting photon interactions. For the lowest metastable initial state an efficient quantum Zeno effect occurs due to thermal radiation of temperatures as low as the de Sitter temperature. This strong decoherence effect is a consequence of gravitational interactions with light external mode. We argue that efficient decoherence does not occur for the case of Hawking-Moss decay. This observation is consistent with requirements set by Poincar recurrence in de Sitter space.

Bachlechner, Thomas C.

2013-05-01

440

HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM  

SciTech Connect

The Department of Energy (DOE) needs improved technologies to decontaminate large areas of both concrete and steel surfaces. The technology should have high operational efficiency, minimize exposures to workers, and produce low levels of secondary waste. In order to meet the DOE's needs, an applied research and development project for the improvement of a current decontamination technology, Vacuum Blasting, is proposed. The objective of this project is to improve the productivity and lower the expense of the existing vacuum blasting technology which has been widely used in DOE sites for removing radioactive contamination, PCBs, and lead-based paint. The proposed work would increase the productivity rate and provide safe and cost-effective decontamination of the DOE sites.

William S. McPhee

2001-08-31

441

Mirror fusion vacuum technology developments  

SciTech Connect

Magnetic Mirror Fusion experiments, such as MFTF-B+T (Mirror Fusion Test Facility-B, Tritium Upgrade) and foreseeable follow-on devices, have operational and maintenance requirements that have not yet been fully demonstrated. Among those associated with vacuum technology are the very-high continuous-pumping speeds, 10/sup 7/ to 10/sup 8/ l/s for D/sub 2/, T/sub 2/ and, to a lesser extent, He; the early detection of water leaks from the very-high heat-flux neutral-beam dumps and the detection and location of leaks in the superconducting magnets not protected by guard vacuums. Possible solutions to these problems have been identified and considerable progress has been made toward successfully demonstrating their feasibility.

Batzer, T.H.; Call, W.R.

1983-11-21

442

27 CFR 24.147 - Operations bond or unit bond.  

Code of Federal Regulations, 2013 CFR

...TREASURY ALCOHOL WINE Establishment and Operations Bonds and Consents of Surety § 24.147 Operations bond or unit bond. Notwithstanding the provisions of § 24.146, each person intending to commence or to continue business...

2013-04-01

443

Vacuum distillation of americium metal  

Microsoft Academic Search

High-purity americium metal has been distilled in multigram quantities from a plutonium-americium alloy. The procedure consisted of a two-stage vacuum distillation carried out at 1200°C and 10⁻⁶ torr pressure. Four batches of americium metal were produced ranging in weight from 13.3 grams to 54.1 grams. The purity of the americium product ranged from 99.27 to 99.79%.

J. W. Berry; J. B. Knighton; C. A. Nannie

1982-01-01

444

Quantum vacuum and accelerated expansion  

NASA Astrophysics Data System (ADS)

A new approach to extraction of quantum vacuum energy, in the context of the accelerated expansion, is proposed, and it is shown that experimentally realistic orders of values can be derived. The idea has been implemented in the framework of the Friedmann-Lematre-Robertson-Walker geometry in the language of the effective action in the relativistic formalism of Schwinger's proper time and Seeley-DeWitt's heat kernel expansion.

Broda, B.; Szanecki, M.

445

Vacuum Ultraviolet Irradiation of Polymers  

Microsoft Academic Search

The interest in incoherent sources for wavelength-selective photochemistry has increased lately, but little is still known about the behavior of polymers when exposed to far UV and vacuum UV (VUV) radiation. The same dearth of information exists regarding UV (VUV) radiation emitted by low-pressure plasmas during polymer treatment. In order to study VUV-UV effects on several polymers (polyethylene - PE,

A. C. Fozza; J. E. Klemberg-Sapieha; Michael R. Wertheimer

1999-01-01

446

Vacuum stability of Standard Model++  

NASA Astrophysics Data System (ADS)

The latest results of the ATLAS and CMS experiments point to a preferred narrow Higgs mass range (m_h \\simeq 124 - 126 GeV) in which the effective potential of the Standard Model (SM) develops a vacuum instability at a scale 10^{9} -10^{11} GeV, with the precise scale depending on the precise value of the top quark mass and the strong coupling constant. Motivated by this experimental situation, we present here a detailed investigation about the stability of the SM^{++} vacuum, which is characterized by a simple extension of the SM obtained by adding to the scalar sector a complex SU(2) singlet that has the quantum numbers of the right-handed neutrino, H", and to the gauge sector an U(1) that is broken by the vacuum expectation value of H". We derive the complete set of renormalization group equations at one loop. We then pursue a numerical study of the system to determine the triviality and vacuum stability bounds, using a scan of 10^4 random set of points to fix the initial conditions. We show that, if there is no mixing in the scalar sector, the top Yukawa coupling drives the quartic Higgs coupling to negative values in the ultraviolet and, as for the SM, the effective potential develops an instability below the Planck scale. However, for a mixing angle -0.35 \\alt \\alpha \\alt -0.02 or 0.01 \\alt \\alpha \\alt 0.35, with the new scalar mass in the range 500 GeV \\alt m_{h"} \\alt 8 TeV, the SM^{++} ground state can be absolutely stable up to the Planck scale. These results are largely independent of TeV-scale free parameters in the model: the mass of the non-anomalous U(1) gauge boson and its branching fractions.

Anchordoqui, Luis A.; Antoniadis, Ignatios; Goldberg, Haim; Huang, Xing; Lst, Dieter; Taylor, Tomasz R.; Vlcek, Brian

2013-02-01

447

Vacuum barrier for excimer lasers  

DOEpatents

This invention is comprised of a barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yearns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput.

Shurter, R.P.

1990-10-10

448

Vacuum pyrolysis of sodium stearate  

Microsoft Academic Search

Vacuum pyrolysis of sodium stearate was studied to provide useful information for Green River oil shale pyrolysis. Sodium stearate is a typical compound of carboxylic acid salts amounting to 3.6% of total organic materials in the oil shale by methanol extraction. Sodium stearate contained in a stainless steel miniature reactor was heated at 450°C in a fluidized sand bath. Pyrolysis

Chong

1985-01-01

449

Holographic Description of Vacuum Bubbles  

NASA Astrophysics Data System (ADS)

We discuss a holographic description of vacuum bubbles, with possible implications for a consistent description of the multiverse. In particular, we elaborate on the recent observation by Maldacena, that the interior of AdS bubbles can be described in terms of CFT degrees of freedom living on the worldsheet of the bubble wall. We consider the scattering of bulk gravitons in the ambient parent vacuum, off the bubble wall. In the dual description, the transmission coefficient is interpreted as the probability that a graviton is absorbed by the worldsheet CFT degrees of freedom. The result is in agreement with intuitive expectations. Conformal invariance is not exact in this setup, and the leading corrections due to the IR and UV cut-offs are displayed. Aside from bulk scattering states, we find that when a bubble nucleates within a parent dS vacuum, there is a zero mode of the graviton which describes lower dimensional gravity with a finite Newton's constant. This massless graviton lives within one Hubble radius away from the bubble wall. Possible implications for a fully holographic description of the inflating multiverse are briefly discussed.

Garriga, J.

450

Investigation of the Reliability of Copper Ball Bonds to Aluminum Electrodes  

Microsoft Academic Search

The reliability of Cu\\/Al bonds was compared with that of Au\\/Al bonds to establish reliable copper ball bonding for IC's. Diffusion-controlled intermetallic compound phases of CuAl and. CuAl2were identified in. the interfaces of the Cu\\/Al bonds after isothermal aging by micro-X-ray diffraction. In addition, diffusion-controlled compound phases of Au4Al, Au5Al2, Au2Al, AuAl, and. AuAl2were identified in the. interfaces of Au\\/Al

Jin Onuki; M. Koizumi; I. Araki

1987-01-01

451

Vacuum Technology and Standardization-An Update  

NASA Astrophysics Data System (ADS)

Vacuum technology has been vital for the progress in almost every field of modern industrial & scientific research and technological developments. Research in this field is therefore important for the rapid progress in other sophisticated technologies. The modern society require precise know-how of vacuum metrology for its complex and sophisticated manufacturing processes and research activities. Accuracy in vacuum measurements is therefore an essential need for every application. The required accuracy is achieved with the help of well-calibrated vacuum gauges and this is possible only, if there exist proper vacuum standards of required range and accuracy. In this paper, a brief review of recently developed different vacuum standards, namely Standard Mercury Manometer, Standard Volume Expansion System and Standard Orifice Flow System will be presented, employed for the calibration of low, medium and high vacuum gauges respectively. Our recently developed standards are simple in design, least in vibration & degassing rate with desired accuracy, ease of operation and cost effective.

Akram, H. M.; Rashid, H.

2011-06-01

452

29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.  

Code of Federal Regulations, 2013 CFR

...long as a particular bond meets the requirements...this part as to the persons required to be bonded...c) Use of separate bonds. The choice of whether persons required to be bonded...separately or under the same bond, whether given...

2013-07-01

453

Demonstrating Diffusion  

ERIC Educational Resources Information Center

|Two demonstrations are described. Materials and instructions for demonstrating movement of molecules into cytoplasm using agar blocks, phenolphthalein, and sodium hydroxide are given. A simple method for demonstrating that the rate of diffusion of a gas is inversely proportional to its molecular weight is also presented. (AJ)|

Foy, Barry G.

1977-01-01

454

From diffusion pumps to cryopumps: The conversion of GSFC's space environment simulator  

Microsoft Academic Search

The SES (Space Environmental Simulator), largest of the Thermal Vacuum Facilities at The Goddard Space Flight Center, recently was converted from an oil diffusion pumped chamber to a Cryopumped chamber. This modification was driven by requirements of flight projects. The basic requirement was to retain or enhance the operational parameters of the chamber such as pumping speed, ultimate vacuum, pump

Ron Cary

1992-01-01

455

Mechanical design of the Tandem Mirror Experiment Upgrade vacuum system  

Microsoft Academic Search

The Tandem Mirror Experiment Upgrade (TMX Upgrade) vacuum system uses most of the vacuum system from the original TMX and substantially increases its capabilities. The vacuum system provides the main structure for the experimental apparatus, as well as providing and maintaining the vacuum environment. The vacuum vessel provides the structure supporting all magnets, as they are contained inside the vacuum

D. D. Lang; M. O. Calderon; S. R. Thomas; D. R. Garner

1981-01-01

456

Bonding aerogels with polyurethanes  

SciTech Connect

Aerogels, porous silica glasses with ultra-fine cell size (30nm), are made by a solution gelation (sol-gel) process. The resulting gel is critical point dried to densities from 0.15--0.60 g/cc. This material is machinable, homogeneous, transparent, coatable and bondable. To bond aerogel an adhesive should have long cure time, no attack on the aerogel structure, and high strength. Several epoxies and urethanes were examined to determine if they satisfied these conditions. Bond strengths above 13 psi were found with double bubble and DP-110 epoxies and XI-208/ODA-1000 and Castall U-2630 urethanes. Hardman Kalex Tough Stuff'' A-85 hardness urethane gave 18 psi bond strength. Hardman A-85, Tuff-Stuff'' was selected for further evaluation because it produced bond strengths comparable to the adherend cohesive strength. 5 refs., 2 figs.

Matthews, F.M.; Hoffman, D.M.

1989-11-01

457

Adhesive for composite bonding.  

National Technical Information Service (NTIS)

Adhesive bonding is a viable option for structural joining of carbon fiber reinforced epoxy composites. Recent examples from laboratory programs include a composite tube joined to a flared composite collar (skirt) to provide a means for mechanical attachm...

R. E. Lyon C. M. Walkup J. T. Matthews.

1989-01-01

458

Bonding Silicones with Epoxies.  

National Technical Information Service (NTIS)

It is shown that silicones, both room temperature vulcanizing (RTV) and millable rubber (press cured) can be successfully bonded to other materials using plasma treatment and epoxy adhesives. The plasma treatment using dry air atmosphere increases the sur...

J. S. Tira

1980-01-01

459

Vacuum Energy and Inflation: 2. A Vacuum Energy Universe  

NASA Astrophysics Data System (ADS)

In most of our undergraduate physics courses, we study what can happen in space, but space itself plays a passive role. In basic cosmology, the opposite is true. It is the behavior of space that plays the major role. In this, paper #2, we first discuss the nature of a simple expanding space, and then look at the consequence of applying Newton's law of gravity in this space. The calculations are particularly simple if most of the energy behaves like the vacuum energy discussed earlier in paper #1.1 The calculation is easy but the results are spectacular.

Huggins, Elisha

2013-10-01

460

Halogen bonding: the ?-hole  

Microsoft Academic Search

Halogen bonding refers to the non-covalent interactions of halogen atoms X in some molecules, RX, with negative sites on others.\\u000a It can be explained by the presence of a region of positive electrostatic potential, the ?-hole, on the outermost portion\\u000a of the halogens surface, centered on the RX axis. We have carried out a natural bond order B3LYP analysis of

Timothy Clark; Matthias Hennemann; Jane S. Murray; Peter Politzer

2007-01-01

461

Metal vapor plasma behavior during vacuum arc remelting of alloy 718  

SciTech Connect

A production vacuum arc remelt (VAR) furnace was modified to enable direct viewing of the metal vapor arc and molten electrode tip during melting of 432 mm dia. alloy 718 electrodes into 508 mm dia. ingots. Diffuse and constricted arcing conditions were characterized using high speed cinematography, standard video format, and monochromatic imaging. Constricted arcing was observed while melting electrodes contaminated with oxide slag of the type used for refractory linings in vacuum induction furnaces. Monochromatic imaging was used in visualize the ion distribution in the arc plasma; these images clearly showed whether the arc operated in a diffuse or constricted model. Diffuse arc melting conditions were very similar to those previously reported in the literature for smaller laboratory sized melts.

Zanner, F.J.; Maguire, M.C.; Williamson, R.L. (Sandia National Labs., Albuquerque, NM (United States)); Adasczik, C.B. (Teledyne Allvac Corp., Monroe, NC (United States)); Roberts, R.R. (Concarsc Corp., Rancocas, NJ (United States)); Strohecker, R. (Strohecker Corp., East Palestine, OH (United States))

1992-01-01

462

Steel bonded dense silicon nitride compositions and method for their fabrication  

DOEpatents

A two-stage bonding technique for bonding high density silicon nitride and other ceramic materials to stainless steel and other hard metals, and multilayered ceramic-metal composites prepared by the technique are disclosed. The technique involves initially slurry coating a surface of the ceramic material at about 1500/sup 0/C in a vacuum with a refractory material and the stainless steel is then pressure bonded to the metallic coated surface by brazing it with nickel-copper-silver or nickel-copper-manganese alloys at a temperature in the range of about 850/sup 0/ to 950/sup 0/C in a vacuum. The two-stage bonding technique minimizes the temperature-expansion mismatch between the dissimilar materials.

Landingham, R.L.; Shell, T.E.

1985-05-20

463

Description of an innovative vacuum pumping and energy absorption system for a multi-megawatt electric propulsion test facility  

SciTech Connect

The development of high power magnetoplasmadynamic (MPD) thrusters is rapidly approaching an impasse to further development: the lack of a facility with adequate vacuum pumping and energy removal capacity to support the resolution of key MPD life and performance issues by FY-93. Several studies have been performed that identify vacuum systems or facility concepts that would alleviate this problem. Although feasible, the proposed vacuum systems require significant research and development; and the proposed facility concepts all require the added development of a gas dynamic diffuser. 8 refs., 4 figs.

Coomes, E.P.; Bennett, D.W.; Lundgren, R.A.; McClanahan, E.D.; Moss, R.W.

1988-03-01

464

Design and simulation of a vacuum micropump  

NASA Astrophysics Data System (ADS)

The majority of micropumps developed result in pressure differences of less than about 3 mH2O. In this work, a vacuum micropump with cascaded chambers is proposed; it is composed of two layers of reciprocal actuated membranes and two layers of check valves. Design of the vacuum micropump with electrostatic and piezoelectric actuators as well as cantilever check valves is proposed. The selection of actuation modes and actuation valves is addressed. Two theoretical design functions are derived to calculate the maximum attainable vacuum with the operation rounds of the membranes and the cascaded stage number. The analyses suggest that large membrane displacement, small dead volume of the chamber, and small backward leakage rate are preferred in obtaining higher vacuum. The increase of chamber stage numbers results in an exponential increase of the vacuum. The relationship between the vacuum and operation rounds is also similar to that between the vacuum and stage numbers: the more rounds the vacuum micropump is operated for, the higher the vacuum is obtained. The designed vacuum micropump can be integrated into the current IC techniques with batch production and high pumping ability.

Cui, Zhenjiang; Takoudis, Christos G.

2001-09-01

465

Relational Bonds and Loyalty: The Bonds that Tie  

Microsoft Academic Search

This paper explores the effect of financial, social and structural bonds on the loyalty of Arabic five star hotel guests. Three different measures of loyalty are used; attitudinal, behavioural and combined to identify how the three relational bonds affect loyalty. The results show that social and structural bonds increase all types of loyalty whereas financial bonds only increase attitudinal and

Ahmad Shammout; Michael Polonsky; Michael Edwardson

466

Ultra high vacuum seal arrangement  

DOEpatents

Arrangement for demountably sealing two concentric metallic tubes in an ultra high vacuum system which facilitates remote actuation. A tubular seal includes integral spaced lips which circumferentially engage the metallic tubes. The lips plastically deform the metallic tubes by mechanical forces resulting from a martensite to austenite transformation of the tubular seal upon application of a predetermined temperature. The sealing force is released upon application of another temperature which causes a transformation from the stronger austenite to the weaker martensite. Use of a dual acting sealing ring and driving ring circumferentially contacting the sealing ring is particularly applicable to sealing larger diameter concentric metallic members.

Flaherty, Robert (Mt. Lebanon, PA)

1981-01-01

467

Leak Detection in Vacuum Technology  

NSDL National Science Digital Library

This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. This module explains the importance of determining vacuum system integrity through leak qualification tests. Learners are introduced to a systematic set of methods for determining the existence of a leak, as well as its size, type and location. Emphasis is placed on the use of a helium mass spectrometer leak detector (MSLD). The centerpiece of this module is a computer program that simulates leak detection with an MSLD.

2012-12-26

468

Vacuum friction in rotating particles.  

PubMed

We study the frictional torque acting on particles rotating in empty space. At zero temperature, vacuum friction transforms mechanical energy into light emission and produces particle heating. However, particle cooling relative to the environment occurs at finite temperatures and low rotation velocities. Radiation emission is boosted and its spectrum significantly departed from a hot-body emission profile as the velocity increases. Stopping times ranging from hours to billions of years are predicted for materials, particle sizes, and temperatures accessible to experiment. Implications for the behavior of cosmic dust are discussed. PMID:20867571

Manjavacas, A; Garca de Abajo, F J

2010-09-08

469

Vacuum Friction in Rotating Particles  

SciTech Connect

We study the frictional torque acting on particles rotating in empty space. At zero temperature, vacuum friction transforms mechanical energy into light emission and produces particle heating. However, particle cooling relative to the environment occurs at finite temperatures and low rotation velocities. Radiation emission is boosted and its spectrum significantly departed from a hot-body emission profile as the velocity increases. Stopping times ranging from hours to billions of years are predicted for materials, particle sizes, and temperatures accessible to experiment. Implications for the behavior of cosmic dust are discussed.

Manjavacas, A.; Garcia de Abajo, F. J. [Instituto de Optica--CSIC, Serrano 121, 28006 Madrid (Spain)

2010-09-10

470

Extraordinary vacuum black string solutions  

SciTech Connect

In addition to the boosted static solution there are two other classes of stationary stringlike solutions of the vacuum Einstein equation in (4+1) dimensions. Each class is characterized by three parameters of mass, tension, and momentum flow along the fifth coordinate. We analyze the metric properties of one of the two classes, which was previously assumed to be naked singular, and show that the solution spectrum contains black string and wormhole in addition to the known naked singularity as the momentum flow to mass ratio increases. Interestingly, there does not exist new zero momentum solution in these cases.

Kim, Hyeong-Chan; Lee, Jungjai [Department of Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Department of Physics, Daejin University, Pocheon, 487-711 (Korea, Republic of)

2008-01-15

471

Laser-triggered vacuum switch  

DOEpatents

A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable. 10 figs.

Brannon, P.J.; Cowgill, D.F.

1990-12-18

472

Laser-triggered vacuum switch  

DOEpatents

This invention pertains to a laser-triggered vacuum switch that has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable. 6 figs.

Brannon, P.J.; Cowgill, D.F.

1988-09-27

473

Laser-triggered vacuum switch  

DOEpatents

A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable.

Brannon, Paul J. (Albuquerque, NM); Cowgill, Donald F. (Danville, CA)

1990-01-01

474

Steel bonded dense silicon nitride compositions and method for their fabrication  

Microsoft Academic Search

A two-stage bonding technique for bonding high density silicon nitride and other ceramic materials to stainless steel and other hard metals, and multilayered ceramic-metal composites prepared by the technique are disclosed. The technique involves initially slurry coating a surface of the ceramic material at about 1500.degree. C. in a vacuum with a refractory material and the stainless steel is then

Richard L. Landingham; Thomas E. Shell

1987-01-01

475

Steel bonded dense silicon nitride compositions and method for their fabrication  

Microsoft Academic Search

A two-stage bonding technique for bonding high density silicon nitride and other ceramic materials to stainless steel and other hard metals, and multilayered ceramic-metal composites prepared by the technique are disclosed. The technique involves initially slurry coating a surface of the ceramic material at about 1500°C in a vacuum with a refractory material and the stainless steel is then pressure

R. L. Landingham; T. E. Shell

1985-01-01

476

Annealing of amorphous Ru-Si-O and Ir-Si-O films in vacuum or dry oxygen  

NASA Astrophysics Data System (ADS)

Films about 200 nm thick of composition Ru17Si16O67 (~50% RuO2+50% SiO2) and Ir18Si15O67 (~55% IrO2+45% SiO2) deposited on oxidized silicon wafers by reactive magnetron sputtering with an argon-oxygen gas mixture from bielemental targets have been annealed in vacuum or in oxygen. As deposited, the films are amorphous by x-ray diffraction as well as by transmission electron microscopy. Upon annealing in vacuum, grains of metal dioxide nucleate and grow in both films, as x-ray diffraction scans reveal. These grains dissociate into metal grains and oxygen. The process is well underway in the Ir18Si15O67 film at 700 C after 12 h while it has barely begun at 800 C after 5 h in the Ru17Si16O67 film. 2.0 MeV 4He++ backscattering spectra establish that oxygen in the amount initially bonded to the metal escapes out of the film that thins down as a result, but remains dense nonetheless. The results are qualitatively consistent with a diffusion-controlled outward flow of oxygen in a heterogeneous medium of metal dioxide and silica. Thermodynamic calculations for the two systems show that oxygen has the highest partial pressure of all gaseous species in both cases, but in the iridium case the oxygen partial pressure exceeds that in the ruthenium case by at least 100-fold. The dissimilar behavior under annealing in vacuum evidently has a thermodynamic component at its origin. When heated in oxygen, a Ru17Si16O67 film is quite unstable, and increasingly so with rising oxygen pressure. The iridium-based films remain essentially unchanged upon annealing at 700 C for 5 min under 760 Torr of dry oxygen. This dissimilarity between the Ru-Si-O and Ir-Si-O films is rooted in the existence of the volatile RuO4 phase that has no analogue species in the iridium-oxygen system. The high stability of amorphous Ir18Si15O67 films under thermal annealing in an oxidizing ambient is significant for applications where electrically conducting films are required that can withstand such exposures essentially unchanged.

Giauque, P. H.; Nicolet, M.-A.

2003-04-01

477

Halogen bonds as orthogonal molecular interactions to hydrogen bonds  

Microsoft Academic Search

Halogen bonds (X-bonds) are shown to be geometrically perpendicular to and energetically independent of hydrogen bonds (H-bonds) that share a common carbonyl oxygen acceptor. This orthogonal relationship is accommodated by the in-plane and out-of-plane electronegative potentials of the oxygen, which are differentially populated by H- and X-bonds. Furthermore, the local conformation of a peptide helps to define the geometry of

Andrea Regier Voth; Patricia Khuu; Keita Oishi; P. Shing Ho

2009-01-01

478

Science and technology of plasma activated direct wafer bonding  

NASA Astrophysics Data System (ADS)

This dissertation studied the kinetics of silicon direct wafer bonding with emphasis on low temperature bonding mechanisms. The project goals were to understand the topological requirements for initial bonding, develop a tensile test to measure the bond strength as a function of time and temperature and, using the kinetic information obtained, develop lower temperature methods of bonding. A reproducible surface metrology metric for bonding was best described by power spectral density derived from atomic force microscopy measurements. From the tensile strength kinetics study it was found that low annealing temperatures could be used to obtain strong bonds, but at the expense of longer annealing times. Three models were developed to describe the kinetics. A diffusion controlled model and a reaction rate controlled model were developed for the higher temperature regimes (T > 600spC), and an electric field assisted oxidation model was proposed for the low temperature range. An in situ oxygen plasma treatment was used to further enhance the field-controlled mechanism which resulted in dramatic increases in the low temperature bonding kinetics. Multiple internal transmission Fourier transform infrared spectroscopy (MIT-FTIR) was used to monitor species evolution at the bonded interface and a capacitance-voltage (CV) study was undertaken to investigate charge distribution and surface states resulting from plasma activation. A short, less than a minute, plasma exposure prior to contacting the wafers was found to obtain very strong bonds for hydrophobic silicon wafers at very low temperatures (100spC). This novel bonding method may enable new technologies involving heterogeneous material systems or bonding partially fabricated devices to become realities.

Roberds, Brian Edward

479

Properties of chemically bonded phases  

Microsoft Academic Search

Retention on non-polar chemically-bonded stationary phases depends on the silica carrier, the kind of bonded silane, the surface concentration of bonded alkyl groups and the number of surface silanol groups before and after chemical modification. The influence of carbon content of bonded phases, column temperature and how the eluent mixture has been prepared on solute retention is demonstrated. For comparison

H. Engelhardt; G. Ahr

1981-01-01

480

Bakeable, all-metal demountable vacuum seal to a flat glass surface  

NASA Astrophysics Data System (ADS)

A technique is described for making a demountable vacuum seal of reasonably good quality between an all-metal evacuation cup and a flat glass surface. The seal is bakeable to temperatures close to the softening point of glass. The stainless steel evacuation cup has two concentric and coplanar sealing surfaces. The regions defined by these surfaces are differentially pumped. Pressures typically below 1 Torr are achieved in the annular space between the two sealing surfaces using a conventional rotary pump. The center region inside the inner sealing surface is typically evacuated to below 10-4 Torr using conventional diffusion or turbomolecular pumps. copyright 2002 American Vacuum Society.

Ng, N.; Collins, R. E.; Lenzen, M.

2002-07-01

481

Physical disorder and optical properties in the vacuum ultraviolet region of amorphous SiO(2).  

PubMed

The optical absorption of point-defect-free SiO(2) glass in the vacuum ultraviolet region is primarily controlled by the concentrations of three- and four-membered ring structures composed of heavily strained Si-O-Si bonds. The main channel of color center formation by F(2) excimer laser (7.9 eV) irradiation is not Frenkel-defect generation of oxygen via two-photon absorption processes but a pair generation of E' and nonbridging oxygen hole centers by the one-photon excitation of these strained bonds with 7.9 eV photons. PMID:11690278

Hosono, H; Ikuta, Y; Kinoshita, T; Kajihara, K; Hirano, M

2001-10-04

482