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1

Study of diffusion bonding of Fe28Al alloy with austenitic stainless steel in vacuum  

Microsoft Academic Search

Diffusion bonding of Fe-28Al alloy with Cr18Ni8 austenitic stainless steel was carried out in vacuum of 10?4Pa and a diffusion-bonded Fe-28Al\\/Cr18Ni8 joint with diffusion reaction layer was formed. Microstructure and reacted phases in the joint were investigated by means of scanning electron microscope (SEM) and X-ray diffractometry (XRD). The reacted phases in the diffusion reaction layer are FeAl, Fe3Al, Ni3Al

Wang Juan; Li Yajiang; Ma Haijun

2005-01-01

2

Vacuum Diffusion Bonding of Flange-foils for X-ray Windows  

SciTech Connect

A vacuum diffusion technology for flange-foil bonding with prevention of the foil oxidation is presented. The application of the technology for the X-ray windows with copper, stainless steel, titan and beryllium foils is discussed. The experimental results for stainless steel-titanium X-ray window are given. The application of the method for the X-ray windows fabrication is proposed.

Avagyan, Vardan; Mikaelyan, Rafael; Petrosyan, Artush [Center for the Advancement of Natural Discoveries using Light Emission, Avan, Acharian 31, 375040 Yerevan (Armenia)

2007-01-19

3

Vacuum Diffusion Bonding of Flange-foils for X-ray Windows  

NASA Astrophysics Data System (ADS)

A vacuum diffusion technology for flange-foil bonding with prevention of the foil oxidation is presented. The application of the technology for the X-ray windows with copper, stainless steel, titan and beryllium foils is discussed. The experimental results for stainless steel-titanium X-ray window are given. The application of the method for the X-ray windows fabrication is proposed.

Avagyan, Vardan; Mikaelyan, Rafael; Petrosyan, Artush

2007-01-01

4

Controlled planar interface synthesis by ultrahigh vacuum diffusion bonding/deposition  

SciTech Connect

An ultrahigh vacuum (UHV) diffusion bonding/deposition instrument was designed and constructed, which can produce homophase and heterophase planar interfaces from a wide array of materials. The interfaces are synthesized in situ by diffusion bonding of two substrates with or without various interfacial layers, at temperatures up to about 1500 degree sign C. Substrate surfaces can be heat treated, ion-beam sputter cleaned, and chemically characterized in situ by Auger electron spectroscopy prior to deposition and/or bonding. Bicrystals can be synthesized by bonding two single-crystal substrates at a specified orientation. Interfacial layers can be deposited by electron beam evaporation and/or sputter deposition in any layered or alloyed combination on the substrates before bonding. The instrument can accommodate cylindrical and/or wafer type specimens whose sizes are sufficient for fracture mechanical testing to measure interface bond strength. A variety of planar interfaces of metals, semiconductors, and ceramics were synthesized. Examples of bonded stainless steel/Ti/stainless steel, Si/Si, and sapphire/sapphire interfaces are presented. (c) 2000 Materials Research Society.

Kim, M. J. [Center for Solid State Science, Science and Engineering of Materials, Arizona State University, Tempe, Arizona 85287-1704 (United States); Carpenter, R. W. [Center for Solid State Science, Science and Engineering of Materials, Arizona State University, Tempe, Arizona 85287-1704 (United States); Cox, M. J. [Center for Solid State Science, Science and Engineering of Materials, Arizona State University, Tempe, Arizona 85287-1704 (United States); Xu, J. [Center for Solid State Science, Science and Engineering of Materials, Arizona State University, Tempe, Arizona 85287-1704 (United States)

2000-04-01

5

The Effects of Intermediate Layer and Surface Nanocrystallization on the Vacuum Diffusion Bonding of Commercially Pure Titanium  

NASA Astrophysics Data System (ADS)

Using cooper foil as intermediate layer, commercially pure titanium (CP-Ti) was vacuum diffusion welded after surface nanocrystallization. The effects of the interlayer and SNC treatment on the bonding state were discussed thereafter. The results showed that about 10 ?m nano-structured surface layer was achieved on CP-Ti. Well bonded joint could be obtained by two original CP-Ti samples welded directly at the conditions of 950C welding temperature and 5 MPa pressure. Excellent bonding between nanocrystalline Ti and cooper substrate was achieved at 850C but lots of cavities were observed on the interface when welded at the same temperature as that for two Ti substrates. Surface nanocrystallite utilization could play a role in promoting interface diffusion procedure by surface atoms activation and large amount of diffusion channels. Cu substrate increased the contact area of interlayer to prevent the possible influence of induced surface roughness on diffusion bonding formation.

Chen, Chunhuan; Liu, Xiaojing; Zhao, Xiujuan; Ren, Ruiming

6

Method for vacuum fusion bonding  

DOEpatents

An improved vacuum fusion bonding structure and process for aligned bonding of large area glass plates, patterned with microchannels and access holes and slots, for elevated glass fusion temperatures. Vacuum pumpout of all components is through the bottom platform which yields an untouched, defect free top surface which greatly improves optical access through this smooth surface. Also, a completely non-adherent interlayer, such as graphite, with alignment and location features is located between the main steel platform and the glass plate pair, which makes large improvements in quality, yield, and ease of use, and enables aligned bonding of very large glass structures.

Ackler, Harold D. (Sunnyvale, CA); Swierkowski, Stefan P. (Livermore, CA); Tarte, Lisa A. (Livermore, CA); Hicks, Randall K. (Stockton, CA)

2001-01-01

7

Fatigue damage of stainless steel diffusion-bonded joints  

Microsoft Academic Search

Vacuum diffusion bonding was carried out on 316L stainless steel. Metallographic inspections and micro-hardness testing were conducted near the interface of diffusion-bonded joints. Fatigue tests were performed to investigate the mechanical performance of diffusion-bonded joints under cyclic loading. Results indicate that, although the static strength of joints closes to that of base metal, fatigue life of the diffusion-bonded joint is

Shu-Xin Li; Fu-Zhen Xuan; Shan-Tung Tu

2008-01-01

8

Diffusion bonding of silicon nitride to  

NASA Astrophysics Data System (ADS)

In this article, the results are presented of an investigation dealing with diffusion bonding of hot-pressed silicon nitride to austenitic stainless steel AISI 316 without the use of a metallic interlayer. Experiments were carried out in vacuum, and it was found that under specific con- ditions, permanent joints can be obtained. Optical microscopy and electron probe microanalysis (EPMA) reveal that the reaction layer formed during the diffusion bonding process consists of a porous zone extending into the ceramic and a diffusion zone extending into the steel. Both zones are similar in chemical composition and contain mainly Fe, Ni, Cr, and Si, whereas the pores appear to contain molecular nitrogen. The formation of the reaction layer can be explained in terms of the decomposition of the silicon nitride, which is promoted under diffusion bonding conditions in vacuum. The free silicon generated by the decomposition reaction diffuses into the steel, whereas the nitrogen is trapped in pores. It appears that the strength of the joint is determined by the residual stresses which develop as a result of the thermal mismatch between the ceramic and the steel. The porous zone has a beneficial influence on the strength, because it partly accommodates the residual stresses.

Stoop, B. T. J.; Ouden, G. Den

1993-08-01

9

Diffusion bonding of titanium to 304 stainless steel  

Microsoft Academic Search

Diffusion bonding between commercially pure titanium and an austenitic stainless steel (AISI 304) has been carried out in the temperature range of 850950 C for 2 h at uniaxial pressure of 3 MPa in vacuum. The microstructure of the diffusion zone has been analysed by optical and scanning electron microscopy (SEM). The interdiffusion of the diffusing species across the interface

M. Ghosh; K. Bhanumurthy; G. B Kale; J. Krishnan; S. Chatterjee

2003-01-01

10

Diffusion bonding of tantalum and stainless steel  

Microsoft Academic Search

This paper describes an investigation of diffusion bonding of commercially pure tantalum and austenitic stainless steel SUS304 in a vacuum of 8 mPa at temperatures ranging between 6001200C. Direct bonding of tantalum and stainless steel results in extremely low joint strength and formation of intermetallic compounds, such as e.g. FeTa, Fe7Ta3, NiTa2, NiTa, Ni2Ta, Ni3Ta, Ni8Ta, and Cr2Ta in the

H. Masumoto; A. Asada; H. Hasuyama; K. Nishio; M. Kato; S. Mukae

1997-01-01

11

Impulse pressuring diffusion bonding of titanium alloy to stainless steel  

Microsoft Academic Search

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=825C, maximum impulse pressure Pmax=50MPa, minimum impulse pressure Pmin=8MPa, number of impulses N=30, impulse frequency f=0.5Hz.

X. J. Yuan; G. M. Sheng; B. Qin; W. Z. Huang; B. Zhou

2008-01-01

12

Phase transformation diffusion bonding of titanium alloy with stainless steel  

Microsoft Academic Search

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 C, minimum cyclic temperature=800 C, number of cycles=10, bonding pressure=5 MPa and heating rate=30 C\\/s.

B.. Qin; G. M. Sheng; J. W. Huang; B. Zhou; S. Y. Qiu; C. Li

2006-01-01

13

Vacuum fusion bonding of glass plates  

DOEpatents

An improved apparatus and method for vacuum fusion bonding of large, patterned glass plates. One or both glass plates are patterned with etched features such as microstructure capillaries and a vacuum pumpout moat, with one plate having at least one hole therethrough for communication with a vacuum pumpout fixture. High accuracy alignment of the plates is accomplished by a temporary clamping fixture until the start of the fusion bonding heat cycle. A complete, void-free fusion bond of seamless, full-strength quality is obtained through the plates; because the glass is heated well into its softening point and because of a large, distributed force that is developed that presses the two plates together from the difference in pressure between the furnace ambient (high pressure) and the channeling and microstructures in the plates (low pressure) due to the vacuum drawn. The apparatus and method may be used to fabricate microcapillary arrays for chemical electrophoresis; for example, any apparatus using a network of microfluidic channels embedded between plates of glass or similar moderate melting point substrates with a gradual softening point curve, or for assembly of glass-based substrates onto larger substrates, such as in flat panel display systems.

Swierkowski, Steve P. (Livermore, CA); Davidson, James C. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

2000-01-01

14

Vacuum fusion bonding of glass plates  

DOEpatents

An improved apparatus and method for vacuum fusion bonding of large, patterned glass plates. One or both glass plates are patterned with etched features such as microstructure capillaries and a vacuum pumpout moat, with one plate having at least one hole therethrough for communication with a vacuum pumpout fixture. High accuracy alignment of the plates is accomplished by a temporary clamping fixture until the start of the fusion bonding heat cycle. A complete, void-free fusion bond of seamless, full-strength quality is obtained through the plates; because the glass is heated well into its softening point and because of a large, distributed force that is developed that presses the two plates together from the difference in pressure between the furnace ambient (high pressure) and the channeling and microstructures in the plates (low pressure) due to the vacuum drawn. The apparatus and method may be used to fabricate microcapillary arrays for chemical electrophoresis; for example, any apparatus using a network of microfluidic channels embedded between plates of glass or similar moderate melting point substrates with a gradual softening point curve, or for assembly of glass-based substrates onto larger substrates, such as in flat panel display systems.

Swierkowski, Steve P. (Livermore, CA); Davidson, James C. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

2001-01-01

15

Diffusion bonding of mismatch dental alloys.  

PubMed

The diffusion bonding of Ti-6Al-4V and Co-Cr-Mo dental alloys has been investigated in terms of the atoms diffusion, the microstructure evolution, and the bonding strength. The bonding performance reveals asymmetry diffusion profiles for both the Co and Cr in Ti-6Al-4V and the Ti in Co-Cr-Mo alloy. Their diffusion coefficients (Arrhenius relations) have been established based on the experiments. Co and Cr diffusion into Ti-6Al-4V leads to alpha --> beta transformation and the intermetallics-formation. Maximum bonding strength occurs at about 840 degrees C. The bonding joint fails under the shear stress in the Ti-6Al-4V side near the bonding interface in brittle manner. The intermetallics in the diffusion layer together with the unbonded areas and other flaws in the bonding interface are responsible for the shear brittle fracture, which also weaken the bonding strength. PMID:19957358

Liu, Honghua; Ni, Jiahua; Wu, Luhai; He, Guo

2010-04-01

16

Electrospray emitters For diffusion vacuum pumps  

E-print Network

Following similar principles as regular diffusion vacuum pumps, an electrospray emitter is set to produce a jet of charged particles that will drag air molecules out of a volume. To be a feasible concept, the emitted ...

Diaz Gmez Maqueo, Pablo (Pablo Ly)

2011-01-01

17

Interface nanochemistry effects on stainless steel diffusion bonding  

Microsoft Academic Search

The diffusion-bonding behavior of single-phase austenitic stainless steel depends strongly on the chemistry of the surfaces\\u000a to be bounded. We found that very smooth (0.5 nm root-mean-square (RMS) roughness), mechanically polished and lapped substrates\\u000a would bond completely in ultrahigh vacuum (UHV) in 1 hour at 1000 C under 3.5 MPa uniaxial pressure, if the native oxide\\u000a on the substrates was

M. J. Cox; R. W. Carpenter; M. J. Kim

2002-01-01

18

Diffusion bonding of titanium-titanium aluminide-alumina sandwich  

SciTech Connect

Diffusion bonding of a metallic-intermetallic-ceramic sandwich is of interest for potential armor applications. Low cost titanium, titanium diboride reinforced titanium aluminide (Ti-48at.%Al), and aluminum oxide are diffusion bonded in a vacuum furnace between 1,000 C and 1,400 C. Metallographic examination of the prior bonding interface showed excellent metallurgical coupling between the Ti-48at.%Al composite and the low cost Ti. A series of microstructures representative of phases consistent with a hypothetical Ti-Al-B phase diagram is visible. The alumina-Ti-48at.%Al interfacial bond is achieved through penetration of titanium-aluminum phases into the existing alumina porosity. A detailed microstructural analysis identifying mechanisms of interfacial bonding will be presented for each interfacial zone.

Wickman, H.A.; Chin, E.S.C. [Army Research Lab., Watertown, MA (United States); Biederman, R.R. [Worcester Polytechnic Inst., MA (United States)

1995-12-31

19

Interface nanochemistry effects on stainless steel diffusion bonding  

NASA Astrophysics Data System (ADS)

The diffusion-bonding behavior of single-phase austenitic stainless steel depends strongly on the chemistry of the surfaces to be bounded. We found that very smooth (0.5 nm root-mean-square (RMS) roughness), mechanically polished and lapped substrates would bond completely in ultrahigh vacuum (UHV) in 1 hour at 1000 C under 3.5 MPa uniaxial pressure, if the native oxide on the substrates was removed by ion-beam cleaning, as shown by in-situ Auger analysis. No voids were observed in these bonded interfaces by transmission electron microscopy (TEM), and the strength was equal to that of the unbounded bare material. No bond formed between the substrates if in-situ ion cleaning was not used. The rougher cleaned substrates partially bonded, indicating that roughness, as well as native oxides, reduced the bonding kinetics.

Cox, M. J.; Carpenter, R. W.; Kim, M. J.

2002-02-01

20

Partial transient liquid phase diffusion bonding of Zircaloy4 to stabilized austenitic stainless steel 321  

Microsoft Academic Search

An innovative method was applied for bonding Zircaloy-4 to stabilized austenitic stainless steel 321 using an active titanium interlayer. Specimens were joined by a partial transient liquid phase diffusion bonding method in a vacuum furnace at different temperatures under 1MPa dynamic pressure of contact. The influence of different bonding temperatures on the microstructure, microindentation hardness, joint strength and interlayer thickness

M. Mazar Atabaki; A. Talebi Hanzaei

2010-01-01

21

Diffusion bonding of stainless steel to Zircaloy4 in the presence of a Ta intermediate layer  

Microsoft Academic Search

Diffusion bonding of stainless steel to Zircaloy-4 in the presence of Ta as interlayer has been investigated using diffusion couples heat treated at 1150 C under vacuum for 3 h. Different types of regions have been observed in stainless steel, Zircaloy-4 and Ta foil. A Cr rich layer formed in stainless steel is found to act as a diffusion barrier.

M. Ahmad; J. I. Akhter; Q. Zaman; M. A Shaikh; M. Akhtar; M. Iqbal; E. Ahmed

2003-01-01

22

Transition joints between Zircaloy-2 and stainless steel by diffusion bonding  

NASA Astrophysics Data System (ADS)

The diffusion bonding between Zircaloy-2 and stainless steel (AISI 304L) using niobium, nickel and copper as intermediate layers has been investigated in the temperature range of 750 to 900C. Bonding was carried out in a vacuum hot press, under compressive loading. Electron probe microanalysis and metallographic analysis showed a good metallurgical compatibility and also indicated the absence of discontunities, micropores and intermetallic compounds at various interfaces. The bond strength of the diffusion bonded assembly was found to be about 400 MPa for the couples bonded at 870C for 2 h. The dimple structure on the fractured surface is indicative of the ductile mode of failure of the bonded assembly.

Bhanumurthy, K.; Krishnan, J.; Kale, G. B.; Banerjee, S.

1994-11-01

23

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

24

Diffusion bonding of Ti coated Zircaloy4 and 316-L stainless steel  

Microsoft Academic Search

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 1000C for 4h and 1050C for 1h. The microstructure of the diffusion zone was investigated by scanning electron microscopy and the phases in the diffusion zone were

J. I. Akhter; M. Ahmad; G. Ali

2009-01-01

25

Effect of interface microstructure on the bond strength of the diffusion welded joints between titanium and stainless steel  

Microsoft Academic Search

Diffusion bonding between commercially pure titanium and 304 stainless steel was carried out at a temperature of 950 C for 30120 min under uniaxial load in a vacuum. The diffusion bonds were characterized by optical and scanning electron microscopy. The diffusion zone contained different reaction bands and their chemical composition was determined using energy dispersive X-ray spectroscopy. The concentration of

M.. Ghosh; S.. Chatterjee

2005-01-01

26

Vacuum pull down method for an enhanced bonding process  

DOEpatents

A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

Davidson, James C. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

1999-01-01

27

A ultra-high-vacuum wafer-fusion-bonding system.  

PubMed

The design of heterojunction devices is typically limited by material integration constraints and the energy band alignment. Wafer bonding can be used to integrate material pairs that cannot be epitaxially grown together due to large lattice mismatch. Control of the energy band alignment can be provided by formation of interface dipoles through control of the surface chemistry. We have developed an ultra-high-vacuum system for wafer-fusion-bonding semiconductors with in situ control and measurement of surface properties relevant to interface dipoles. A wafer-fusion-bonding chamber with annealing capabilities was integrated into an ultra-high-vacuum system with a sputtering chamber and an x-ray photoelectron spectroscopy system for preparing and measuring the surface chemistry of wafers prior to bonding. The design of the system along with initial results for the fusion-bonded InGaAs/Si heterojunction is presented. PMID:22667658

McKay, Kyle; Wolter, Scott; Kim, Jungsang

2012-05-01

28

A ultra-high-vacuum wafer-fusion-bonding system  

NASA Astrophysics Data System (ADS)

The design of heterojunction devices is typically limited by material integration constraints and the energy band alignment. Wafer bonding can be used to integrate material pairs that cannot be epitaxially grown together due to large lattice mismatch. Control of the energy band alignment can be provided by formation of interface dipoles through control of the surface chemistry. We have developed an ultra-high-vacuum system for wafer-fusion-bonding semiconductors with in situ control and measurement of surface properties relevant to interface dipoles. A wafer-fusion-bonding chamber with annealing capabilities was integrated into an ultra-high-vacuum system with a sputtering chamber and an x-ray photoelectron spectroscopy system for preparing and measuring the surface chemistry of wafers prior to bonding. The design of the system along with initial results for the fusion-bonded InGaAs/Si heterojunction is presented.

McKay, Kyle; Wolter, Scott; Kim, Jungsang

2012-05-01

29

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

30

Low temperature diffusion bonding of stainless steel  

Microsoft Academic Search

Diffusion bonding of stainless steel (SS) has been attempted in temperature range of 623773 K using multiple inter-layers\\u000a of nickel, copper and silver. The intermediate layers were electro-deposited taking care to avoid oxidation at the interfaces.\\u000a The bonded area was examined for the formation of any intermetallic compound through electron probe micro-analyzer (EPMA)\\u000a and nano-indentation technique. Results indicate the absence

P. S. Gawde; R. Kishore; A. L. Pappachan; G. B. Kale; G. K. Dey

2010-01-01

31

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

32

Diffusion bonding between commercially pure titanium and micro-duplex stainless steel  

Microsoft Academic Search

Diffusion-bonded joints between commercially pure titanium and micro-duplex stainless steel were prepared in the temperature range of 800950C for 1.5h under 3MPa uniaxial load in vacuum. The diffusion bonds were characterized using light and scanning electron microscopy. The composition of the reaction products were determined by energy dispersive spectroscopy. Up to 850C, ?-Fe+? and ?+FeTi phase mixtures were formed at

S. Kundu; S. Chatterjee

2008-01-01

33

Diffusion bonding of 410 stainless steel to copper using a nickel interlayer  

Microsoft Academic Search

In the present work, plates of stainless steel (grade 410) were joined to copper ones through a diffusion bonding process using a nickel interlayer at a temperature range of 800950C. The bonding was performed through pressing the specimens under a 12-MPa compression load and a vacuum of 10?4torr for 60min. The results indicated the formation of distinct diffusion zones at

H. Sabetghadam; A. Zarei Hanzaki; A. Araee

2010-01-01

34

Radiant heat source, vacuum bag, provide portable bonding oven  

NASA Technical Reports Server (NTRS)

Portable bonding oven is formed to any desired size or configuration to attach doublers and brackets to the surfaces of large structures. A radiant heat source is used in combination with a heat resistant transport vacuum bag and a black heat absorbing cloth.

Nicholls, A. H.

1967-01-01

35

Diffusion bonding of titanium to 304 stainless steel  

NASA Astrophysics Data System (ADS)

Diffusion bonding between commercially pure titanium and an austenitic stainless steel (AISI 304) has been carried out in the temperature range of 850-950 C for 2 h at uniaxial pressure of 3 MPa in vacuum. The microstructure of the diffusion zone has been analysed by optical and scanning electron microscopy (SEM). The interdiffusion of the diffusing species across the interface has been evaluated by electron probe microanalysis (EPMA). The reaction products formed at the interface have been identified by X-ray diffraction technique. It has been observed that the diffusion zone is dominated by the presence of the ? phase close to the stainless steel side and the solid solution of ?-Ti (solutes are Fe, Cr and Ni) close to the titanium. The presence of Fe 2Ti and FeTi has been found in the reaction zone. It has been observed that the bond strength (222 MPa) is highest for the couple processed at 850 C and this value decreases with rise in joining temperature. The variation of strength of the transition joints is co-related with the microstructural characteristics of the diffusion zone.

Ghosh, M.; Bhanumurthy, K.; Kale, G. B.; Krishnan, J.; Chatterjee, S.

2003-11-01

36

Vacuum diffusion welding of sintered materials to low-carbon steel  

Microsoft Academic Search

1.A radically new process has been developed for producing relief pictures by vacuum diffusion welding, which combines the operations of powder compaction, sintering, and weld-bonding.2.The optimum process parameters have been established experimentally for welding steel 15 to sintered PN nickel and sintered PZh2M2 iron.

N. F. Kazakov; L. N. Lado

1969-01-01

37

Vacuum fusion bonded glass plates having microstructures thereon  

DOEpatents

An improved apparatus and method for vacuum fusion bonding of large, patterned glass plates. One or both glass plates are patterned with etched features such as microstructure capillaries and a vacuum pumpout moat, with one plate having at least one hole therethrough for communication with a vacuum pumpout fixture. High accuracy alignment of the plates is accomplished by a temporary clamping fixture until the start of the fusion bonding heat cycle. A complete, void-free fusion bond of seamless, full-strength quality is obtained through the plates; because the glass is heated well into its softening point and because of a large, distributed force that is developed that presses the two plates together from the difference in pressure between the furnace ambient (high pressure) and the channeling and microstructures in the plates (low pressure) due to the vacuum drawn. The apparatus and method may be used to fabricate microcapillary arrays for chemical electrophoresis; for example, any apparatus using a network of microfluidic channels embedded between plates of glass or similar moderate melting point substrates with a gradual softening point curve, or for assembly of glass-based substrates onto larger substrates, such as in flat panel display systems.

Swierkowski, Steve P. (Livermore, CA); Davidson, James C. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

2001-01-01

38

Using Diffusion Bonding in Making Piezoelectric Actuators  

NASA Technical Reports Server (NTRS)

A technique for the fabrication of piezoelectric actuators that generate acceptably large forces and deflections at relatively low applied voltages involves the stacking and diffusion bonding of multiple thin piezoelectric layers coated with film electrodes. The present technique stands in contrast to an older technique in which the layers are bonded chemically, by use of urethane or epoxy agents. The older chemical-bonding technique entails several disadvantages, including the following: It is difficult to apply the bonding agents to the piezoelectric layers. It is difficult to position the layers accurately and without making mistakes. There is a problem of disposal of hazardous urethane and epoxy wastes. The urethane and epoxy agents are nonpiezoelectric materials. As such, they contribute to the thickness of a piezoelectric laminate without contributing to its performance; conversely, for a given total thickness, the performance of the laminate is below that of a unitary piezoelectric plate of the same thickness. The figure depicts some aspects of the fabrication of a laminated piezoelectric actuator by the present diffusion- bonding technique. First, stock sheets of the piezoelectric material are inspected and tested. Next, the hole pattern shown in the figure is punched into the sheets. Alternatively, if the piezoelectric material is not a polymer, then the holes are punched in thermoplastic films. Then both faces of each punched piezoelectric sheet or thermoplastic film are coated with a silver-ink electrode material by use of a silkscreen printer. The electrode and hole patterns are designed for minimal complexity and minimal waste of material. After a final electrical test, all the coated piezoelectric layers (or piezoelectric layers and coated thermoplastic films) are stacked in an alignment jig, which, in turn, is placed in a curved press for the diffusion-bonding process. In this process, the stack is pressed and heated at a specified curing temperature and pressure for a specified curing time. The pressure, temperature, and time depend on the piezoelectric material selected. At the end of the diffusion-bonding process, the resulting laminated piezoelectric actuator is tested to verify the adequacy of the mechanical output as a function of an applied DC voltage.

Sager, Frank E.

2003-01-01

39

Vacuum bag bonding with a high temperature adhesive  

NASA Technical Reports Server (NTRS)

A novel controlled molecular weight form of LARC-TPI polymide that exhibits an exceptionally high degree of melt flow in the 340-360 C temperature range has been developed. This material has been evaluated as a high-temperature adhesive, and because of its flow, cost-effective vacuum bag/oven processing can be used. Comparison of adhesive performance with higher molecular weight forms bonded at higher pressures shows this novel material to be equal in mechanical strength.

Progar, Donald J.; St. Clair, Terry L.

1991-01-01

40

Diffusion bonding of IN 718 to VM 350 grade maraging steel  

NASA Technical Reports Server (NTRS)

Diffusion bonding studies have been conducted on IN 718, VM 350 and the dissimilar alloy couple, IN 718 to maraging steel. The experimental processing parameters critical to obtaining consistently good diffusion bonds between IN 718 and VM 350 were determined. Interrelationships between temperature, pressure and surface preparation were explored for short bending intervals under vacuum conditions. Successful joining was achieved for a range of bonding cycle temperatures, pressures and surface preparations. The strength of the weaker parent material was used as a criterion for a successful tensile test of the heat treated bond. Studies of VM-350/VM-350 couples in the as-bonded condition showed a greater yielding and failure outside the bond region.

Crosby, S. R.; Biederman, R. R.; Reynolds, C. C.

1972-01-01

41

Solid-State Diffusion Bonding of Commercially pure Titanium and Precipitation Hardening Stainless steel  

Microsoft Academic Search

Solid-state direct diffusion bonding of commercially pure Titanium (Cp-Ti) and precipitation hardening stainless steel (PHSS) has been carried out in the temperature range of 800C to 1000C with an interval of 50C for 3.6 ks under 3.5 Mpa uniaxial load in (4 to 6)10-3 Pa vacuum. The effects of temperatures have been investigated with reference to bond strength. The examination

Debasis Poddar

42

Better vacuum by removal of diffusion-pump-oil contaminants  

NASA Technical Reports Server (NTRS)

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 technology were achieved which resulted in a two-decade-or-more lower ultimate pressure. Data are presented to show the overall or individual contaminating effects of commonly used phthalate ester plasticizers of 390 to 530 molecular weight on diffusion pump performance. Methods for removing contaminants from diffusion pump silicone oil during operation and for reclaiming contaminated oil by high-vacuum molecular distillation are described. Conceptual self-cleansing designs and operating procedures are proposed for modifying large diffusion pumps into high-efficiency distillation devices. The potential exists for application of these technological advancements to other disciplines, such as medicine, biomedical materials, metallurgy, refining, and chemical (diffusion-enrichment) processing.

Buggele, A. E.

1975-01-01

43

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

44

Diffusion bonding of commercially pure titanium to 304 stainless steel using copper interlayer  

Microsoft Academic Search

Diffusion bonding was carried out between commercially pure titanium (cpTi) and 304 stainless steel (304ss) using copper as interlayer in the temperature range of 850950C for 1.5h under 3MPa load in vacuum. The microstructures of the transition joints were revealed in optical and scanning electron microscopy (SEM). The study exhibits the presence of different reaction layers in the diffusion zone

S. Kundu; M. Ghosh; A. Laik; K. Bhanumurthy; G. B. Kale; S. Chatterjee

2005-01-01

45

Diffusion bonding of commercially pure titanium and 17-4 precipitation hardening stainless steel  

Microsoft Academic Search

Commercially pure titanium and 17-4 precipitation hardening stainless steel were diffusion bonded in the temperature range of 850950C for 7.2ks under 3.5MPa uniaxial load in vacuum. The transition joints were examined in optical and scanning electron microscope. The chemical compositions of reaction layers in the diffusion zone were determined by energy dispersive spectroscopy and the formation of intermetallics like ?

S. Kundu; M. Ghosh; S. Chatterjee

2006-01-01

46

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 , while the high-quality joining of pure aluminum was infeasible by conventional diffusion bonding at the temperature lower than . 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

2013-10-01

47

Diffusion Bonding Aluminium Alloys and Composites: New Approaches and Modelling  

E-print Network

Diffusion Bonding Aluminium Alloys and Composites: New Approaches and Modelling Amir A. Shirzadi.D. research was to develop new joining methods for these materials for which conventional welding methods have of the research, two new methods for TLP diffusion bonding of aluminium-based composites (aluminium alloys

Cambridge, University of

48

Diffusion in Nickel-Base Superalloys and Bond Coats  

NSDL National Science Digital Library

Nickel-base superalloys are known for their high temperature strengths and their corrosion resistant properties. To increase the service temperatures of the Ni-base superalloys, thermal barrier coatings (TBC) are used in conjunction with a bond coat. The role of the bond coat is to prevent diffusion between the superalloy and the TBC, especially the depletion of Al from the superalloy. Diffusion studies between various bond coat materials and Ni-base superalloys were conducted for two purposes: (1) to better understand the interaction between the bond coats and the superalloys and (2) to provide data to evaluate the current diffusion mobility database. Superalloys considered in this study were Inconel X-750, Inconel 625, Inconel 718, and CMSX-4. Bond coatings considered were RuAl, PtAl, and Ni. Diffusion couples were heat treated at 1150 C and 850 C for various times. For Ni/superalloy couples, diffusion simulations using multicomponent thermodynamics and diffusion mobility databases were performed. Evaluation of the bond coats and the diffusion mobility database required measurement of phase fraction and composition profiles. Optical metallography and image analysis software were used to measure the phasefraction profiles. Electron diffraction spectroscopy (EDS) was used to measure the composition profiles. This data was used to determine how well the bond coatings limited diffusion of Al out of the superalloy and into the bond coat. Comparison of the measured and calculated composition profiles and phase fraction profiles indicated whether specific mobility parameters or thermodynamic descriptions should be re-evaluated.

Mesick, Nathan

2005-01-01

49

AN INTERNAL CONVECTIVE HEATING TECHNIQUE FOR DIFFUSION BONDING ARRAYED MICROCHANNEL ARCHITECTURES  

SciTech Connect

Diffusion bonding cycle times can be a large factor in the production cost of metal microchannel devices. The challenge is to significantly minimize bonding cycle times through rapid heating and cooling within the bonding process. A novel method is described which takes advantage of the internal flow passages within microchannel devices for convective heat transfer during the bonding process. The internal convective heating (ICH) technique makes use of heated inert gas to provide the microchannel assembly with rapid and uniform heat input. Results demonstrate that the ICH technique is feasible, capable of producing microchannels with higher dimensional integrity and shorter bonding cycle times than traditional vacuum hot press methods. Results suggest that this may be due to smaller thermal gradients within microchannel devices during the ICH bonding cycle.

Paul, Brian; Bose, Sumantra; Palo, Daniel R.

2010-01-08

50

Ultrasonic NDT of titanium diffusion bonding with guided waves  

SciTech Connect

An ultrasonic guided wave technique is developed for the NDT of diffusion bonded titanium-to-titanium structures. A three-layer model based on the normal beam experimental results has been proposed. Dispersion curves and wave structure are analyzed to direct the experimental study. Two features related to Lamb waves propagating in diffusion bonded titanium plates, the spectral peak to peak ratios and the wave mode frequency shift, are extracted from the guided wave experimental results for both 2 mm (0.08 in.) and 4 mm (0.16 in.) diffusion bond panels. It is found for some specific modes and frequencies that these two features are sensitive to the diffusion bonding states and, therefore, could be used to distinguish good bond panels from poor bond ones.

Rose, J.L.; Zhu, W. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Engineering Science and Mechanics; Zaidi, M. [Boeing Co., Long Beach, CA (United States)

1998-04-01

51

Interfacial properties of diffusion bonded Ti6Al4V to AISI 304 stainless steel by inserting a Cu interlayer  

Microsoft Academic Search

The joining characteristics of Ti-6Al-4V with AISI 304 stainless steel by inserting a Cu interlayer was investigated in a\\u000a vacuum-free diffusion bonding process. The diffusion bonds were carried out in the temperature range of 820, 850 and 870C\\u000a for 50, 70 and 90minutes, respectively, under 1MPa load in argon atmosphere. The joining performances of diffusion bonded\\u000a Ti-6Al-4V to AISI 304

N. zdemir; B. Bilgin

2009-01-01

52

Superplastic deformation enhanced diffusion bonding of aluminum alloy 7475  

SciTech Connect

The purpose of this work is to determine the feasibility of concurrent solid-state diffusion bonding and superplastic forming of Al alloy 7475. The authors used the concept of superplastic deformation to study the diffusion bonding of superplastic Al alloy 7475. Superplastic alloys attain large plastic elongation through grain-boundary sliding -- i.e., very fine internal grains slide and rotate, allowing neighboring grains to switch. Similarly, if grains on the surface are also sliding and rotating, then the oxide film should be disrupted by new grains coming to the surface. A surface that contains these nonoxidized grains should be able to bond with a minimum of applied contact pressure. Thus, the bonds can be produced easily by applying gas pressure during superplastic forming. This is the hypothesis the authors are attempting to prove in this study. It is difficult to make a direct comparison with other reported data, since the diffusion bonding conditions vary significantly. However, it can be concluded that, for a given 7475 composition, prior thermomechanical processing can influence its diffusion-bonding characteristics. Beginning with this preprocessed material, they used a unique method, never before reported, to obtain diffusion bonding concurrently with superplastic forming to achieve ductile, oxide-free bonds at significantly lower pressures in an argon atmosphere. This work clearly proves that superplastic deformation enhances solid state diffusion bonding of aluminum alloy.

Sunwoo, A.; Lum, R. [Lawrence Livermore National Lab., CA (United States)] [Lawrence Livermore National Lab., CA (United States)

1995-08-15

53

Diffusion bonding of 410 stainless steel to copper using a nickel interlayer  

SciTech Connect

In the present work, plates of stainless steel (grade 410) were joined to copper ones through a diffusion bonding process using a nickel interlayer at a temperature range of 800-950 deg. C. The bonding was performed through pressing the specimens under a 12-MPa compression load and a vacuum of 10{sup -4} torr for 60 min. The results indicated the formation of distinct diffusion zones at both Cu/Ni and Ni/SS interfaces during the diffusion bonding process. The thickness of the reaction layer in both interfaces was increased by raising the processing temperature. The phase constitutions and their related microstructure at the Cu/Ni and Ni/SS diffusion bonding interfaces were studied using optical microscopy, scanning electron microscopy, X-ray diffraction and elemental analyses through energy dispersive spectrometry. The resulted penetration profiles were examined using a calibrated electron probe micro-analyzer. The diffusion transition regions near the Cu/Ni and Ni/SS interfaces consist of a complete solid solution zone and of various phases based on (Fe, Ni), (Fe, Cr, Ni) and (Fe, Cr) chemical systems, respectively. The diffusion-bonded joint processed at 900 deg. C showed the maximum shear strength of about 145 MPa. The maximum hardness was obtained at the SS-Ni interface with a value of about 432 HV.

Sabetghadam, H., E-mail: h.sabetghadam@gmail.com [School of Metallurgical and Materials Engineering, University of Tehran (Iran, Islamic Republic of); Hanzaki, A. Zarei [School of Metallurgical and Materials Engineering, University of Tehran (Iran, Islamic Republic of); Araee, A. [School of Mechanical Engineering, University of Tehran (Iran, Islamic Republic of)

2010-06-15

54

In situ observation of interfacial fatigue crack growth in diffusion bonded joints of austenitic stainless steel  

NASA Astrophysics Data System (ADS)

Micro-fatigue tests were performed on 316LSS vacuum diffusion bonded joints to investigate the interfacial fatigue crack growth behavior with discrete micro-voids located ahead of a pre-existing crack tip. In situ observation of the interfacial fatigue crack propagation and micro-voids evolution was carried out during the whole fatigue testing. SEM of the fracture surface was analyzed. The results showed that the interface failure mechanism of similar diffusion bonded joints is different from that of dissimilar materials joints. A brittle mode is observed in the main crack growth. And the ridge interface formed in diffusion bonded joints due to surface roughness can be a resistance to the crack growth. The location of the fatigue crack initiation and the crack propagation direction derived from SEM observation of the fracture surface of the specimen are in consistent with those obtained from the in situ observation by using the optical microscope.

Li, Shu-xin; Xuan, Fu-Zhen; Tu, Shan-Tung

2007-06-01

55

Diffusion Bonding of Silicon Carbide for MEMS-LDI Applications  

NASA Technical Reports Server (NTRS)

A robust joining approach is critically needed for a Micro-Electro-Mechanical Systems-Lean Direct Injector (MEMS-LDI) application which requires leak free joints with high temperature mechanical capability. Diffusion bonding is well suited for the MEMS-LDI application. Diffusion bonds were fabricated using titanium interlayers between silicon carbide substrates during hot pressing. The interlayers consisted of either alloyed titanium foil or physically vapor deposited (PVD) titanium coatings. Microscopy shows that well adhered, crack free diffusion bonds are formed under optimal conditions. Under less than optimal conditions, microcracks are present in the bond layer due to the formation of intermetallic phases. Electron microprobe analysis was used to identify the reaction formed phases in the diffusion bond. Various compatibility issues among the phases in the interlayer and substrate are discussed. Also, the effects of temperature, pressure, time, silicon carbide substrate type, and type of titanium interlayer and thickness on the microstructure and composition of joints are discussed.

Halbig, Michael C.; Singh, Mrityunjay; Shpargel, Tarah P.; Kiser, J. Douglas

2007-01-01

56

Hydrogen bonds and heat diffusion in ?-helices: a computational study.  

PubMed

Recent evidence has shown a correlation between the heat diffusion pathways and the known allosteric communication pathways in proteins. Allosteric communication in proteins is a central, yet unsolved, problem in biochemistry, and the study and characterization of the structural determinants that mediate energy transfer among different parts of proteins is of major importance. In this work, we characterized the role of hydrogen bonds in diffusivity of thermal energy for two sets of ?-helices with different abilities to form hydrogen bonds. These hydrogen bonds can be a constitutive part of the ?-helices or can arise from the lateral chains. In our in vacuo simulations, it was observed that ?-helices with a higher possibility of forming hydrogen bonds also had higher rates of thermalization. Our simulations also revealed that heat readily flowed through atoms involved in hydrogen bonds. As a general conclusion, according to our simulations, hydrogen bonds fulfilled an important role in heat diffusion in structural patters of proteins. PMID:25105349

Mio, German; Barriga, Raul; Gutierrez, Gonzalo

2014-08-28

57

Application of diffusion bonding to electronic interconnection of flatpack leads  

NASA Technical Reports Server (NTRS)

Diffusion-bonded joints between gold-plated Kovar leads and indium-plated copper circuit pads offer some advantages for electronic circuit packaging. Test results show that consistent high strength bonds stronger than the copper circuit foil are achieved by parallel-gap bonding at relatively low power settings. The bonds are basically formed by the alloying of the gold, indium and copper at the bond interface. Other low melting metals such as tin can also be used; however, tin does not offer the ease of bonding that results in consistent separation of the copper foil during pull testing. The investigation was conducted in three parts consisting of: (1) an evaluation of the physical strength of resulting bonds at ambient and elevated temperature, (2) a metallurgical analysis of bonds using scanning electron microscopy and nondispersive X-ray analysis, and (3) evaluation and development of various schemes for multiple lead flatpack bonding.

Korb, R. W.; Lardenoit, V. F.

1973-01-01

58

Ultrasonic NDE of titanium diffusion bonds using signal phase  

NASA Astrophysics Data System (ADS)

Diffusion bonding is a highly advantageous solid-state welding method. However, its full exploitation in titanium components is currently limited by a lack of robust NDE techniques capable of detecting anything but gross bond-line defects. A novel ultrasonic technique has been developed to address this lack of capability. This technique, based on the ultrasonic signal phase, has been demonstrated in a `single-sided' scenario where only one side of the diffusion bond was accessible. Samples with differing degrees of bond quality were evaluated, and excellent agreement was found between the single-sided and double-sided experiments.

Escobar-Ruiz, E.; Cawley, P.; Nagy, P. B.; Collison, I.; Wright, D.

2013-01-01

59

Partial transient liquid phase diffusion bonding of Zircaloy-4 to stabilized austenitic stainless steel 321  

SciTech Connect

An innovative method was applied for bonding Zircaloy-4 to stabilized austenitic stainless steel 321 using an active titanium interlayer. Specimens were joined by a partial transient liquid phase diffusion bonding method in a vacuum furnace at different temperatures under 1 MPa dynamic pressure of contact. The influence of different bonding temperatures on the microstructure, microindentation hardness, joint strength and interlayer thickness has been studied. The diffusion of Fe, Cr, Ni and Zr has been investigated by scanning electron microscopy and energy dispersive spectroscopy elemental analyses. Results showed that control of the heating and cooling rate and 20 min soaking at 1223 K produces a perfect joint. However, solid-state diffusion of the melting point depressant elements into the joint metal causes the solid/liquid interface to advance until the joint is solidified. The tensile strength of all the bonded specimens was found around 480-670 MPa. Energy dispersive spectroscopy studies indicated that the melting occurred along the interface of the bonded specimens as a result of the transfer of atoms between the interlayer and the matrix during bonding. This technique provides a reliable method of bonding zirconium alloy to stainless steel.

Atabaki, M. Mazar, E-mail: m.mazaratabaki@gmail.com [Department of Materials Engineering, Faculty of Mechanical Engineering, University Technology Malaysia, 81310 (Malaysia); Hanzaei, A. Talebi [Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Tehran (Iran, Islamic Republic of)

2010-10-15

60

Diffusion bonding of silicon nitride to austenitic stainless steel without interlayers  

SciTech Connect

In this article, the results are presented of an investigation dealing with diffusion bonding of hot-pressed silicon nitride to austenitic stainless steel AISI 316 without the use of a metallic interlayer. Experiments were carried out in vacuum, and it was found that under specific conditions, permanent joints can be obtained. Optical microscopy and electron probe microanalysis (EPMA) reveal that the reaction layer formed during the diffusion bonding process consists of a porous zone extending into the ceramic and a diffusion zone extending into the steel. Both zones are similar in chemical composition and contain mainly Fe, Ni, Cr, and Si, whereas the pores appear to contain molecular nitrogen. The formation of the reaction layer can be explained in terms of the decomposition of the silicon nitride, which is promoted under diffusion bonding conditions in vacuum. The free silicon generated by the decomposition reaction diffuses into the steel, whereas the nitrogen is trapped in pores. It appears that the strength of the joint is determined by the residual stresses which develop as a result of the thermal mismatch between the ceramic and the steel. The porous zone has a beneficial influence on the strength, because it partly accommodates the residual stresses.

Stoop, B.T.J.; Ouden, G.D. (Delft Univ. of Technology, Delft (Netherlands))

1993-08-01

61

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

Microsoft Academic Search

Vacuum diffusion bonding of stainless steel to copper was carried out at a temperature ranging from 830 to 950C under an\\u000a axial pressure of 3MPa for 60min with three kinds of interlayer metals: tin-bronze (TB) foil, Au foil, and TB-Au composite\\u000a interlayer. The results showed that the grain boundary wetting was formed within the steel adjacent to the interface due

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

2011-01-01

62

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

Microsoft Academic Search

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 800950C for 10.8ks under a 3MPa uniaxial pressure in vacuum. The interface microstructures and reaction products of the transition joints were investigated by optical and scanning electron microscopy. Up to 850C processing temperature, a 300-?m

S. Kundu; S. Chatterjee

2008-01-01

63

In situ observation of interfacial fatigue crack growth in diffusion bonded joints of austenitic stainless steel  

Microsoft Academic Search

Micro-fatigue tests were performed on 316LSS vacuum diffusion bonded joints to investigate the interfacial fatigue crack growth behavior with discrete micro-voids located ahead of a pre-existing crack tip. In situ observation of the interfacial fatigue crack propagation and micro-voids evolution was carried out during the whole fatigue testing. SEM of the fracture surface was analyzed. The results showed that the

Shu-Xin Li; Fu-Zhen Xuan; Shan-Tung Tu

2007-01-01

64

Joining of Silicon Carbide: Diffusion Bond Optimization and Characterization  

NASA Technical Reports Server (NTRS)

Joining and integration methods are critically needed as enabling technologies for the full utilization of advanced ceramic components in aerospace and aeronautics applications. One such application is a lean direct injector for a turbine engine to achieve low NOx emissions. In the application, several SiC substrates with different hole patterns to form fuel and combustion air channels are bonded to form the injector. Diffusion bonding is a joining approach that offers uniform bonds with high temperature capability, chemical stability, and high strength. Diffusion bonding was investigated with the aid of titanium foils and coatings as the interlayer between SiC substrates to aid bonding. The influence of such variables as interlayer type, interlayer thickness, substrate finish, and processing time were investigated. Optical microscopy, scanning electron microscopy, and electron microprobe analysis were used to characterize the bonds and to identify the reaction formed phases.

Halbig, Michael C.; Singh, Mrityunjay

2008-01-01

65

Diffusion bonds between a stainless steel and zirconia  

Microsoft Academic Search

Extremely strong diffusion bonds can be made directly between Y[sub 2]O[sub 3]-stabilized TZP ZrO[sub 2] and Fe-18Cr-8Ni stainless steel above a critical joining temperature of about 1,100C. Fracture initiates at the metal\\/ceramic interface with plasticity occurring in the metal. Bonding is accompanied by a thin interfacial reaction layer which may possibly lead to local melting during the bonding cycle. This

Cai-Dong Qin; Brian Derby

1993-01-01

66

Effect of hydrogen bond on coal extraction by in-situ vacuum FTIR  

SciTech Connect

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 associated, and OH tetrapolymer hydrogen bond. There was no correlation between the amount of three types of hydrogen bonds and extraction yield. The thermo stability of hydrogen bond in inertinite was stronger than that of vitrinite, especially the thermo stability of hydrogen bond in Pingshuo inertinite.

Li, J.; Feng, J.; Li, W.Y.; Chang, H.Z.; Xie, K.C. [Taiyuan University of Technol, Taiyuan (China)

2009-07-01

67

Fabrication and Characterization of Diffusion Bonds for Silicon Carbide  

NASA Technical Reports Server (NTRS)

Diffusion bonds of silicon carbide (SiC) were fabricated using several different types of titanium (Ti) based interlayers between the SiC substrates. The interlayers were an alloyed Ti foil, a pure Ti foil, and a physically vapor deposited (PVD) Ti coating. Microscopy was conducted to evaluate the cross-sections of the resulting bonds. Microprobe analysis identified reaction formed phases in the diffusion bonded region. Uniform and well adhered bonds were formed between the SiC substrates. In the case where the alloyed Ti foil or a thick Ti coating (i.e. 20 micron) was used as the interlayer, microcracks and several phases were present in the diffusion bonds. When a thinner interlayer was used (i.e. 10 micron PVD Ti), no microcracks were observed and only two reaction formed phases were present. The two phases were preferred and fully reacted phases that did not introduce thermal stresses or microcracks during the cool-down stage after processing. Diffusion bonded samples were evaluated with the non-destructive evaluation (NDE) methods of pulsed thermography and immersion ultrasonic testing. Joined SiC substrates that were fully bonded and that had simulated bond flaws in the interlayer were also evaluated using immersion ultrasound. Pull testing was conducted on the bonds to determine the tensile strength. To demonstrate the joining approach for a complex multilayered component for a low NOx injector application, the diffusion bonding approach was used to join three 4" diameter SiC discs that contained complex fuel and air flow channels.

Halbig, Michael; Singh, Mrityunjay; Martin, Richard E.; Cosgriff, Laura M.

2007-01-01

68

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

69

Variation in the reaction zone and its effects on the strength of diffusion bonded titaniumstainless steel couple  

Microsoft Academic Search

Solid state bonding was carried out between commercially pure titanium and 304 stainless steel at 850C temperature for 30150min under uniaxial load in vacuum. The transition joints were characterized using optical and scanning electron microscopes and revealed the presence of reaction layers in the diffusion zone. The chemical composition of these reaction products was determined by energy dispersive spectroscopy and

M. Ghosh; Samar Das; P. S. Banarjee; S. Chatterjee

2005-01-01

70

HIP diffusion bonding of P\\/M titanium alloy Ti6Al4V and stainless steel 1Cr18Ni9Ti  

Microsoft Academic Search

The HIP diffusion bonding of P\\/M titanium alloy Ti-6Al-4V and stainless steel 1Cr18Ni9Ti using pure Ni as intermediate layer was studied. Bonding joint with complex bonding interface was obtained by HIPing pre-alloyed Ti-6Al-4V powders and stainless steel 1Cr18Ni9Ti in a vacuum canning. The joint strengths were examined and the characteristics of bonding joint were observed. The result shows that the

LANG Ze-bao; WANG Liang

2007-01-01

71

Diffusion bonding of the oxide dispersion strengthened steel PM2000  

NASA Astrophysics Data System (ADS)

Ferritic oxide dispersion strengthened (ODS) steels are well suited as structural materials, e.g. for claddings in fission reactors and for plasma facing components in fusion power plants due to their high mechanical and oxidation stability at high temperatures and their high irradiation resistance. PM2000 is an iron based ODS ferritic steel with homogeneously distributed nanometric yttria particles. Melting joining techniques are not suitable for such ODS materials because of the precipitation and agglomeration of the oxide particles and hence the loss of their strengthening effect. Solid state diffusion bonding is thus chosen to join PM2000 and is investigated in this work with a focus on oxide particles. The diffusion bonding process is aided by the computational modeling, including the influence of the ODS particles. For modeling the microstructure stability and the creep behavior of PM2000 at various, diffusion bonding relevant temperatures (50-80% Tm) are investigated. Particle distribution (TEM), strength (tensile test) and toughness (Charpy impact test) obtained at temperatures relevant for bonding serve as input for the prediction of optimal diffusion bonding parameters. The optimally bonded specimens show comparable strength and toughness relative to the base material.

Sittel, Wiebke; Basuki, Widodo W.; Aktaa, Jarir

2013-11-01

72

Cleaning of diffusion bonding surface by argon ion bombardment treatment  

NASA Astrophysics Data System (ADS)

The specimens of oxygen-free high conductivity copper, SUS304L stainless steel and pure iron were treated by argon ion bombardment and then were bonded by diffusion bonding method. The effects of argon ion bombardment treatment on faying surface morphology, tensile strength of bonding joints and inclusions at the fracture surface were investigated. The results showed that argon ion bombardment treatment was effective to remove the oxide film and contamination at the faying surface and improve the quality of joints. The tensile strength of the bonded joints was improved, and minimum bonding temperature to make the metallic bonding at the interface was lowered by argon ion bombardment treatment. At the joints with argon ion bombardment treatment, ductile fractured surface was seen and the amount of inclusions was obviously decreased.

Wang, Airu; Ohashi, Osamu; Yamaguchi, Norio; Aoki, Masanori; Higashi, Yasuo; Hitomi, Nobuteru

2003-05-01

73

Diffusion bonding stainless steel to alumina using aluminium interlayers  

Microsoft Academic Search

A study has been conducted to identify the effects of fabrication temperatures pressures, times and other variables on the strengths of diffusion-bonded joints between alumina and BS321 stainless steel produced using aluminium foil interlayers. The strengths of the alumina-aluminium and steel-aluminium interfaces were found to be influenced differently by some fabrication parameters, thus increasing the fabrication temperature promoted alumina-aluminium bonding

M. G. Nicholas; R. M. Crispin

1982-01-01

74

Evaluation of diffusion-bonded aluminum alloys to stainless steel  

Microsoft Academic Search

An investigation was made of the diffusion bonding of 316 stainless steel to two types of Al alloys (6061 (T6 condition) and 1100 (0 condition)) and pure Al metal. A 0.05-mm (0.002-in.) thick silver interface applied by hot hollow cathode plating served as the joining medium. The tensile strengths of bond with all three Al alloys decreased after aging at

Calderon

1983-01-01

75

Superplastically formed diffusion bonded metallic structure  

NASA Technical Reports Server (NTRS)

A metallic sandwich structure particularly suited for use in aerospace industries comprising a base plate, a cover plate, and an orthogonally corrugated core is described. A pair of core plates formed of a superplastic alloy are interposed between the base plate and the cover plate and bonded. Each of the core plates is characterized by a plurality of protrusions comprising square-based, truncated pyramids uniformly aligned along orthogonally related axes perpendicularly bisecting the legs of the bases of the pyramids and alternately inverted along orthogonally related planes diagonally bisecting the pyramids, whereby an orthogonally corrugated core is provided.

Ko, W. L. (inventor)

1981-01-01

76

Effect of interface microstructure on the bond strength of the diffusion welded joints between titanium and stainless steel  

SciTech Connect

Diffusion bonding between commercially pure titanium and 304 stainless steel was carried out at a temperature of 950 deg. C for 30-120 min under uniaxial load in a vacuum. The diffusion bonds were characterized by optical and scanning electron microscopy. The diffusion zone contained different reaction bands and their chemical composition was determined using energy dispersive X-ray spectroscopy. The concentration of chemical species indicated the presence of {sigma}, {lambda}, {chi}, FeTi, {beta}-Ti and Fe{sub 2}Ti{sub 4}O phases in the reaction zone and their existence was confirmed by X-ray diffraction. A maximum bond strength of {approx}71% of that of titanium along with 5.8% ductility were obtained for the diffusion couple processed for 30 min due to formation of finer size intermetallics. A rise in joining time increases void generation and growth of intermetallic compounds, which are responsible for a drastic fall in the strength value.

Ghosh, M. [Department of Metallurgy, Bengal Engineering College, Deemed University, Howrah-711103, West Bengal (India)]. E-mail: ghosh_mnk@yahoo.com; Chatterjee, S. [Department of Metallurgy, Bengal Engineering College, Deemed University, Howrah-711103, West Bengal (India)]. E-mail: schatterjee46@yahoo.com

2005-05-15

77

Algorithm for anisotropic diffusion in hydrogen-bonded networks  

E-print Network

In this paper I describe a specialized algorithm for anisotropic diffusion determined by a field of transition rates. The algorithm can be used to describe some interesting forms of diffusion that occur in the study of proton motion in a network of hydrogen bonds. The algorithm produces data that require a nonstandard method of spectral analysis which is also developed here. Finally, I apply the algorithm to a simple specific example.

Edoardo Milotti

2007-04-04

78

Effects of Intermetallic Phases on the Bond Strength of Diffusion-Bonded Joints between Titanium and 304 Stainless Steel Using Nickel Interlayer  

Microsoft Academic Search

Solid-state diffusion bonding was used to join commercially pure titanium (Ti) and 304 stainless steel (SS) with a pure nickel\\u000a (Ni) interlayer of 300-?m thickness in the temperature range of 800?C to 950?C in steps of 50?C for 7.2 ks under 3MPa load in vacuum. Interfaces\\u000a were characterized using light and scanning electron microscopy. The interdiffusion of the chemical species

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

2007-01-01

79

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

80

Investigation of bonding strength and sealing behavior of aluminum/stainless steel bonded at room temperature  

E-print Network

], spark welding [3], explosive bonding [4], and diffusion bonding [5,6]. However, the processing such as diffusion bonding [5,6], friction welding [7e11], vacuum roll bonding [12] and hot roll bonding [13 diffusion and reaction layer at the interfaces are important for the joining of dissimilar metals

Howlader, Matiar R

81

Diffusion Bonding Technology of a Titanium Alloy to a Stainless Steel Web With an Ni Interlayer  

Microsoft Academic Search

The probability and appropriate processing parameters for diffusion bonding of a titanium alloy to a stainless steel web with an Ni interlayer have been investigated. The microstructure of the diffusion bonding joint has been observed by microscopy, SEM, and EPMA, and the main factors affecting diffusion bonding have been analyzed. The results show that atom diffusion and migration between Ti

Peng He; Jiuhai Zhang; Ronglin Zhou; Xiaoqiang Li

1999-01-01

82

Characterization of metallic foil joints using diffusion bonding and diffusion soldering in micro-technology-based energy and chemical systems  

SciTech Connect

The several 316 stainless steel mesoscopic devices were made using diffusing bonding and diffusion soldering. Tensile strength, pressure drop of the devices were measured, and metallurgical examinations were made of the joints. Continuous bonds were observed in both diffusion bonded and diffusion soldered samples. Strengths of the diffusion soldered samples were up to 80% of the strength of the Ag(sub3) Sn joint material or 125 MPa. The pressure drop in diffusion soldered samples was 0.76 psi at the highest flow rates of 2.08 L/min. Diffusion bonded joints had strengths of up to 700 MPa but the back pressures were higher at all flow rates.

Gabriel, Michael (Oregon State Univ.); Paul, Brian K. (Oregon State Univ.); Wilson, Rick D.; Alman, David E.

2001-01-10

83

Characterization of metallic foil joints using diffusion bonding and diffusion soldering in micro-technology-based energy and chemical systems  

SciTech Connect

The several 316 stainless steel mesoscopic devices were made using diffusing bonding and diffusion soldering. Tensile strength, pressure drop of the devices were measured, and metallurgical examinations were made of the joints. Continuous bonds were observed in both diffusion bonded and diffusion soldered samples. Strengths of the diffusion soldered samples were up to 80% of the strength of the Ag3Sn joint material or 125 MPa. The pressure drop in diffusion soldered samples was 0.76 psi at the highest flow rates of 2.08 L/min. Diffusion bonded joints had strengths of up to 700 MPa but the back pressures were higher at all flow rates.

Gabriel, Michael (Oregon State Univ., Corvallis, OR); Paul, B.K. (Oregon State Univ., Corvallis, OR); Wilson, R.D.

2001-01-01

84

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

85

Silver plating ensures reliable diffusion bonding of dissimilar metals  

NASA Technical Reports Server (NTRS)

Dissimilar metals are reliably joined by diffusion bonding when the surfaces are electroplated with silver. The process involves cleaning and etching, anodization, silver striking, and silver plating with a conventional plating bath. It minimizes the formation of detrimental intermetallic phases and provides greater tolerance of processing parameters.

1967-01-01

86

Diffusion bonding of stainless steel to Zircaloy-4 in the presence of a Ta intermediate layer  

NASA Astrophysics Data System (ADS)

Diffusion bonding of stainless steel to Zircaloy-4 in the presence of Ta as interlayer has been investigated using diffusion couples heat treated at 1150 C under vacuum for 3 h. Different types of regions have been observed in stainless steel, Zircaloy-4 and Ta foil. A Cr rich layer formed in stainless steel is found to act as a diffusion barrier. A region observed with the Ta foil in Zircaloy-4 is rich in Cr, Ta, Fe and Zr while two zones are formed in Zircaoly-4 containing Zr, Ta, Cr, Fe and Ni. The zone rich in Zr gives black contrast and the other zone gives grey contrast and these are identified as eutectic phases of the type TaCr 2-Liq.-?-Zr and Ta(Cr,Fe) 2-Liq.-?-Zr.

Ahmad, M.; Akhter, J. I.; Zaman, Q.; Shaikh, M. A.; Akhtar, M.; Iqbal, M.; Ahmed, E.

2003-05-01

87

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

88

Interface characteristics in diffusion bonding of Fe 3Al with Cr18Ni8 stainless steel  

Microsoft Academic Search

Fe3Al and Cr18-Ni8 stainless steel were diffusion-bonded in vacuum and a Fe3Al\\/Cr18-Ni8 interface with reaction layer was formed. Microstructure in the reaction layer at Fe3Al\\/Cr18-Ni8 interface was analyzed by means of scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). The growth of reaction layer with heating temperature (T) and holding time (t) was researched. The results indicate that FeAl,

Juan Wang; Yajiang Li; Yansheng Yin

2005-01-01

89

On the differentiation of diffusion bond strength using the total acoustic energy reflected from the bond  

SciTech Connect

Single frequency reflection coefficients and reflected energy over a broad acoustic band (2-15 MHz), and the mechanical bond strength were evaluated on diffusion bonds in Cu/Cu, Cu/Ni, and Ti-6Al-4V/self. Results indicate that energy data are more sensitive to small bond strength changes as predicted by Parseval`s theorem. In all cases, the energy reflected mainly originates at voids still present at the original interface location. Other microstructural features caused by the interdiffusion appear to diminish the reflected energy. 7 refs., 4 figs.

Ojard, G.C. [Pratt and Whitney, West Palm Beach, FL (United States); Buck, O.; Rehbein, D.K.; Hughes, M.S. [Iowa State Univ. of Science and Technology, Ames, IA (United States). Center for NDE

1992-12-31

90

Evaluation of Amorphous Diffusion Bonding by Nonlinear Ultrasonic Method  

NASA Astrophysics Data System (ADS)

The characteristic of bond interface in amorphous diffusion bonding, of which evaluation is impossible by conventional method, was quantitatively evaluated by the second harmonic amplitude. Steel bars were bonded with Ni-based amorphous film. Conventional ultrasonic method, e.g. the echo height reflected from bond interface, could not identify samples manufactured at different bonding temperatures 1050, 1150 and 1250C. Therefore, nonlinear ultrasonic method was applied for distinguishing the difference of bond strength. The nonlinear ultrasonic method is to measure the higher harmonics generated by nonlinear stress-strain relationship at weak bonds. Measurements were conducted in contact using piezoelectric transducers in through-transmission. The fundamental and second harmonic wave frequencies are 5 and 10 MHz. To measure second harmonic wave amplitude, a commercial superheterodyne receiver and pulse inversion method were used. The pulse inversion method is the digital signal processing to extract only second and even orders harmonic wave by superposing two burst waves with a 180 phase difference after corrected time-lag by cross-correlation function. These results were compared to destructive tests for examining the relationship between tensile strength and the second harmonics. Besides, elemental analysis by EPMA was performed for manifesting the source of second harmonics generation.

Ohara, Y.; Kawashima, K.; Yamada, R.; Horio, H.

2004-02-01

91

Diffusion bonding between Ti6Al4V alloy and ferritic stainless steel  

Microsoft Academic Search

In the present study, Ti6Al4V alloy was diffusion bonded to a ferritic stainless steel. The effect of bonding temperature on the microstructural development across the joint region was investigated. After diffusion bonding, microstructural analysis including metallographic examination, energy dispersive spectrograph (EDS) and shear strength was conduced. From the results, it was seen that bonding on the temperature was affecting the

Bulent Kurt; Nuri Orhan; Ertan Evin; Adnan alik

2007-01-01

92

Amorphous diffusion bonding of steel pipe and its impact toughness  

Microsoft Academic Search

An iron-based amorphous foil (FeNiCrSiB) was used as an interlayer for the amorphous diffusion bonding of low carbon steel\\u000a pipes under argon flux. The microstructure and mechanical properties of the joint were analyzed using an electron probe micro-analyzer\\u000a (EPMA), tensile test, bending test and impact test. The results show that the joint microstructure resembles that of the base\\u000a metal and

Xuegang Wang; Fengjie Yan; Qian Yan; Xingeng Li

2007-01-01

93

Structure and properties of diffusion bonded transition joints between commercially pure titanium and type 304 stainless steel using a nickel interlayer  

Microsoft Academic Search

The solid-state diffusion bonding was carried out between commercially pure titanium and Type 304 stainless steel using nickel\\u000a as an interlayer in the temperature range of 800900?C for 9ks under 3MPa load in vacuum. The transition joints thus formed\\u000a were characterized in the optical and scanning electron microscopes. The inter-diffusion of the chemical species across the\\u000a diffusion interfaces were evaluated

Sukumar Kundu; Subrata Chatterjee

2007-01-01

94

Joining of Silicon Carbide Through the Diffusion Bonding Approach  

NASA Technical Reports Server (NTRS)

In order for ceramics to be fully utilized as components for high-temperature and structural applications, joining and integration methods are needed. Such methods will allow for the fabrication the complex shapes and also allow for insertion of the ceramic component into a system that may have different adjacent materials. Monolithic silicon carbide (SiC) is a ceramic material of focus due to its high temperature strength and stability. Titanium foils were used as an interlayer to form diffusion bonds between chemical vapor deposited (CVD) SiC ceramics with the aid of hot pressing. The influence of such variables as interlayer thickness and processing time were investigated to see which conditions contributed to bonds that were well adhered and crack free. Optical microscopy, scanning electron microscopy, and electron microprobe analysis were used to characterize the bonds and to identify the reaction formed phases.

Halbig, Michael .; Singh, Mrityunjay

2009-01-01

95

Interface Microstructure and Strength Properties of the Diffusion-Bonded Joints of Titanium ?Cu Interlayer ? Stainless Steel  

Microsoft Academic Search

In the present study, copper was used as an intermediate material in diffusion bonding between titanium and stainless steel.\\u000a The process was carried out in the temperature range of 850C to 1000C for 60minutes and at 900C for 30 to 150minutes\\u000a under the compressive stress of 3MPa in a vacuum. The effects of temperature and time on the microstructure of

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

2008-01-01

96

Interfacial microstructure and mechanical properties of diffusion-bonded titaniumstainless steel joints using a nickel interlayer  

Microsoft Academic Search

Diffusion bonding was carried out between commercially pure titanium and 304 stainless steel using nickel interlayer in the temperature range of 800950C for 3.6ks under 3MPa load in vacuum. The transition joints thus formed were characterized in optical and scanning electron microscopes. TiNi3, TiNi and Ti2Ni are formed at the nickeltitanium (NiTi) interface; whereas, stainless steelnickel (SSNi) interface is free

S. Kundu; S. Chatterjee

2006-01-01

97

Mo/Ti Diffusion Bonding for Making Thermoelectric Devices  

NASA Technical Reports Server (NTRS)

An all-solid-state diffusion bonding process that exploits the eutectoid reaction between molybdenum and titanium has been developed for use in fabricating thermoelectric devices based on skutterudite compounds. In essence, the process is one of heating a flat piece of pure titanium in contact with a flat piece of pure molybdenum to a temperature of about 700 C while pushing the pieces together with a slight pressure [a few psi (of the order of 10 kPa)]. The process exploits the energy of mixing of these two metals to form a strong bond between them. These two metals were selected partly because the bonds formed between them are free of brittle intermetallic phases and are mechanically and chemically stable at high temperatures. The process is a solution of the problem of bonding hot-side metallic interconnections (denoted hot shoes in thermoelectric jargon) to titanium-terminated skutterudite n and p legs during the course of fabrication of a unicouple, which is the basic unit cell of a thermoelectric device (see figure). The hot-side operating temperature required for a skutterudite thermoelectric device is 700 C. This temperature precludes the use of brazing to attach the hot shoe; because brazing compounds melt at lower temperatures, the hot shoe would become detached during operation. Moreover, the decomposition temperature of one of the skutterudite compounds is 762 C; this places an upper limit on the temperature used in bonding the hot shoe. Molybdenum was selected as the interconnection metal because the eutectoid reaction between it and the titanium at the ends of the p and n legs has characteristics that are well suited for this application. In addition to being suitable for use in the present bonding process, molybdenum has high electrical and thermal conductivity and excellent thermal stability - characteristics that are desired for hot shoes of thermoelectric devices. The process takes advantage of the chemical potential energy of mixing between molybdenum and titanium. These metals have a strong affinity for each other. They are almost completely soluble in each other and remain in the solid state at temperatures above the eutectoid temperature of 695 C. As a result, bonds formed by interdiffusion of molybdenum and titanium are mechanically stable at and well above the original bonding temperature of about 700 C. Inasmuch as the bonds are made at approximately the operating temperature, thermomechanical stresses associated with differences in thermal expansion are minimized.

Sakamoto, Jeffrey; Kisor, Adam; Caillat, Thierry; Lara, Liana; Ravi, Vilupanur; Firdosy, Samad; Fleuiral, Jean-Pierre

2007-01-01

98

Diffusion Bonding and Characterization of a Dispersion Strengthened Aluminum Alloy  

NASA Astrophysics Data System (ADS)

Aluminum metal matrix composites (Al-MMC's) containing silicon carbide or alumina particle reinforcements are used extensively in automotive and aircraft industries. The addition of a reinforcing phase has led to significant improvements in the mechanical properties of these alloys. However, despite substantial improvements in the properties, the lack of a reliable joining method has restricted their full potential. The differences in physical and metallurgical properties between the ceramic phase and the Al-MMC, prevents the successful application of the fusion welding processes, conventionally used for joining monolithic aluminum alloys. Therefore, alternative techniques that prevent microstructural changes in the base metal need to be developed. In this study, the transient liquid phase diffusion bonding and eutectic bonding of a particle reinforced Al 6061-MMC was investigated to identify a method that could control particle segregation within the joint and increase the final joint strength. The results showed that TLP bonding using Ni-foil was possible at 600C for 10 minutes using a pressure of 0.01 MPa. However, characterization of the bond interface showed a wide particle segregated zone due to the "pushing effect" of the solid/liquid interface during isothermal solidification stage of bonding. The presence of this particle segregated zone was shown to cause low joint strengths. In order to overcome these problems, TLP bonding was performed using electrodeposited coatings of Ni and Ni-Al 2O3 as a way of controlling the volume of eutectic liquid formed at the joint. Theoretical and experimental work showed that the use of thin coatings was successful in reducing the width of the segregated zone formed at the joint and this had the effect of increasing joint shear strength values. Furthermore, lower bonding temperature could also be used as a method of reducing particle segregation and therefore, a Cu-Sn interlayer was used to form a eutectic bond. The experimental results showed that particle segregation could be prevented, but lower joint shear strengths were obtained. Comparative analysis indicated that when Ni-Al2O3 coating was used, shear strength of 92% of the base metal strength was achievable. In comparison, when Ni coating, Ni-foil and Cu-Sn interlayers were used, the maximum joint strengths achievable were 84% 62% and 60% respectively.

Cooke, Kavian Omar

99

Cracking during solidification of diffusion bonded Inconel 625 in the presence of Zircaloy4 interlayer  

Microsoft Academic Search

Diffusion bonded specimens of Inconel 625 in the presence of Zircaloy-4 interlayer have been investigated using scanning electron microscope (SEM) having energy dispersive system (EDS) as an attachment. Cracking is observed in the center of the diffusion zone (DZ) in both the samples bonded at 1050 and 1100C. The bonding of Inconel 625 in the presence of Zircaloy-4 occurs due

M. Ahmad; J. I. Akhter; M. Shahzad; M. Akhtar

2008-01-01

100

Diffusion of co-sputtered metals as bonding materials for 3D interconnects during thermal treatments.  

PubMed

Diffusion behaviors of co-sputtered metals during thermal treatments were investigated, where these co-sputtered metals can be used as bonding materials for 3D Interconnects. In this paper, we report the diffusion behaviors and discuss the diffusion mechanisms of co-sputtered metals before and after annealing. Atom and vacancy volume, vacancy formation energy, and activation energy are proposed to explain the diffusion direction and diffusion rate among different co-sputtered metals. Based on the excellent bonding performance of this method, Cu/metal co-sputtering bonding is considered as a potential candidate for advanced bonding technology. PMID:22755075

Hsu, S Y; Chen, H Y; Chen, K N

2012-03-01

101

Analyzing the Effect of Diffusion Bonding Process Parameters on Bond Characteristics of Mg-Al Dissimilar Joints  

NASA Astrophysics Data System (ADS)

The principle difficulty when joining magnesium (Mg)-aluminium (Al) lies in the existence of formation of oxide films and brittle intermetallic in the bond region. However, diffusion bonding can be used to join these alloys without much difficulty. Temperature, pressure, and holding time are the three main variables which govern the integrity of a diffusion bond. This paper focuses on the effect of these parameters on diffusion layer thickness, hardness and strength of AZ31B magnesium-AA2024 aluminium dissimilar joints. The experiments were conducted based on three factors, five-level, and central composite rotatable design with full replications technique. Empirical relationships were developed to predict diffusion layer thickness, hardness and strength using response surface methodology. From this investigation, it is found that bonding temperature has predominant effect on bond characteristics.

Mahendran, G.; Babu, S.; Balasubramanian, V.

2010-07-01

102

Diffusion bonding\\/superplastic forming of Ti6Al6V-2Sn\\/SUS 304 stainless steel\\/Ti6Al6V-2Sn  

Microsoft Academic Search

The superplasticity of the Ti- 6Al- 6V- 2Sn alloy for different temperatures was evaluated by single-sheet free blowing. The\\u000a optimal superplastic temperature for the Ti- 6Al- 6V- 2Sn alloy was found to be 850 C. Diffusion bonding of Ti- 6Al- 6V-\\u000a 2Sn and 304 stainless steel was carried out in a vacuum. The interface of both bonded alloys was examined

J. S. Shyu; T. H. Chuang

1996-01-01

103

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

104

Microstructure and mechanical properties of diffusion bonded W/steel joint using V/Ni composite interlayer  

SciTech Connect

Diffusion bonding between W and steel using V/Ni composite interlayer was carried out in vacuum at 1050 C and 10 MPa for 1 h. The microstructural examination and mechanical property evaluation of the joints show that the bonding of W to steel was successful. No intermetallic compound was observed at the steel/Ni and V/W interfaces for the joints bonded. The electron probe microanalysis and X-ray diffraction analysis revealed that Ni{sub 3}V, Ni{sub 2}V, Ni{sub 2}V{sub 3} and NiV{sub 3} were formed at the Ni/V interface. The tensile strength of about 362 MPa was obtained for as-bonded W/steel joint and the failure occurred at W near the V/W interface. The nano-indentation test across the joining interfaces demonstrated the effect of solid solution strengthening and intermetallic compound formation in the diffusion zone. - Highlights: Diffusion bonding of W to steel was realized using V/Ni composite interlayer. The interfacial microstructure of the joint was clarified. Several VNi intermetallic compounds were formed in the interface region. The application of V/Ni composite interlayer improved the joining quality.

Liu, W.S.; Cai, Q.S., E-mail: cai2009pm@163.com; Ma, Y.Z.; Wang, Y.Y.; Liu, H.Y.; Li, D.X.

2013-12-15

105

Interface structure of diffusion bonded duplex stainless steel and medium carbon steel couple  

Microsoft Academic Search

Diffusion bonding of duplex stainless steel to medium carbon steel was carried out with different temperatures for sound bonds. In the bonding process, relatively intermediate temperatures such as 750, 800, 850 and 900C were used with a bonding time of 30min. In this study, microstructural changes and mechanical properties in the interface region of duplex stainless steel and medium carbon

Bulent Kurt; Adnan alik

2009-01-01

106

Theoretical and experimental analyses of atom diffusion characteristics on wire bonding interfaces  

NASA Astrophysics Data System (ADS)

The features of ultrasonic bonding interface were inspected by using a high resolution transmission electron microscope. Stress of ultrasonic bonding interface was analysed by the finite elements simulation. Results show that the high stress of bonding interface was caused by ultrasonic vibration, which increased the dislocation density inside the metal crystalline lattice which provides the fast diffusion channels, and provided driving force for atom inter-diffusion. 'Short-circuit diffusion' during ultrasonic bonding is more prominent than crystal diffusion. For the given ultrasonic bonding parameters, depth of atom diffusion at Au/Al interface of ultrasonic bonding was about 100-300 nm in several ten milliseconds, which forms the bonding strength of 0.65 N, and it is an inter-metallic compound of AuAl2. These will be helpful for further analysis.

Li, Junhui; Fuliang, Wang; Han, Lei; Zhong, Jue

2008-07-01

107

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

108

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

109

Effects of Intermetallic Phases on the Bond Strength of Diffusion-Bonded Joints between Titanium and 304 Stainless Steel Using Nickel Interlayer  

NASA Astrophysics Data System (ADS)

Solid-state diffusion bonding was used to join commercially pure titanium (Ti) and 304 stainless steel (SS) with a pure nickel (Ni) interlayer of 300-?m thickness in the temperature range of 800 C to 950 C in steps of 50 C for 7.2 ks under 3 MPa load in vacuum. Interfaces were characterized using light and scanning electron microscopy. The interdiffusion of the chemical species across the diffusion interfaces was evaluated by electron probe microanalysis. Nickel interlayer completely restricted the migration of Ti to SS up to 850 C bonding temperature. However, at 900 C and 950 C processing temperatures, Ni interlayer could not restrict the migration of Ti to SS, and phase mixtures of ? + ? + ?-Fe, ? + ?-Fe, and ? + FeTi + ?-Ti were formed at SS-Ni interface. The occurrence of different intermetallics was confirmed by X-ray diffraction technique. The maximum tensile strength of ~311 MPa and shear strength of 236 MPa along with 9.1 pct elongation were obtained for the diffusion couple processed at 850 C due to better contact between the mating surfaces and without formation of brittle Fe-Ti base intermetallics. With an increase in the bonding temperature to 900 C and above, the bond strength drops due to the formation of brittle Fe-Ti base intermetallics in the diffusion zone. Observation of the fracture surface in a scanning electron microscope (SEM) using energy dispersive spectroscopy demonstrates that failure occurred through Ni-Ti interface of the joints when processed up to 850 C and through SS-Ni interface when processed at 900 C and above.

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

2007-09-01

110

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

111

The interface morphology of diffusion bonded dissimilar stainless steel and medium carbon steel couples  

Microsoft Academic Search

In the present study, a duplex stainless steel and an austenitic stainless steel were diffusion bonded to medium carbon steel. The differences of two dissimilar metal couples at the test temperature on microstructural developments across the joint region were investigated. After diffusion bonding, microstructural analysis including metallographic examination, energy dispersive spectroscopy (EDS) and shear strength tests were performed. From the

Bulent Kurt

2007-01-01

112

Diffusion bonding of a microduplex stainless steel to Ti6Al4V  

Microsoft Academic Search

In this study, a microduplex stainless steel (AVESTA 2205) and Ti6Al4V alloy were bonded for the first time. The bonding variables were chosen on the basis of the importance of grain boundary diffusion in ?-phase of the titanium alloys. The study showed that the formation of FeCrTi intermetallics is more important than ?-phase formation during bonding.

N Orhan; T. I Khan; M Ero?lu

2001-01-01

113

Silver diffusion bonding and layer transfer of lithium niobate to silicon Kenneth Diest,a  

E-print Network

Silver diffusion bonding and layer transfer of lithium niobate to silicon Kenneth Diest,a Melissa J substrates. A silver film was deposited onto both the silicon and lithium niobate surfaces prior to bonding silver grains to replace the as-bonded interface by a single polycrystalline silver film. The transferred

Atwater, Harry

114

Leakage rates and thermal requirements for the diffusion bonding of microchannel arrays via internal convective heating  

SciTech Connect

Diffusion bonding cycle times can be a large cost factor in the production of metal microchannel devices. The challenge is to significantly minimize this cost by reducing the bonding cycle time through rapid and uniform heating and cooling within the bonding process. Heating rates in diffusion bonding processes are typically limited by the need to minimize thermal gradients during bonding. A novel method is described which takes advantage of the internal flow passages within microchannel devices for convective heat transfer during the bonding process. The internal convective heating (ICH) technique makes use of heated inert gas to provide the microchannel assembly with rapid and uniform heat input. This paper will demonstrate the ability to effectively diffusion bond microchannel laminae using the ICH method by investigating the leakage rates.

Bose, Sumantra; Palo, Daniel R.; Paul, Brian

2007-07-24

115

An Investigation of Diffusion in Droplets and of Evaporation of Volatile Components into Vacuum  

Microsoft Academic Search

A numerical investigation is performed of the dynamics of diffusion in droplets and of free-molecule evaporation into vacuum of volatile components of magnesium (Mg) and zinc (Zn) from aluminum alloys. The calculations are performed in application to the conditions of my experiments in high-frequency droplet formation under conditions of centrifugal dispersion in vacuum of rotating (overloads of 704000) blanks by

A. N. Ponomarev

2005-01-01

116

Diffuser/ejector system for a very high vacuum environment  

NASA Technical Reports Server (NTRS)

Turbo jet engines are used to furnish the necessary high temperature, high volume, medium pressure gas to provide a high vacuum test environment at comparatively low cost for space engines at sea level. Moreover, the invention provides a unique way by use of the variable area ratio ejectors with a pair of meshing cones are used. The outer cone is arranged to translate fore and aft, and the inner cone is interchangeable with other cones having varying angles of taper.

Riggs, K. E.; Wojciechowski, C. J. (inventors)

1984-01-01

117

Interface characteristics in diffusion bonding of Fe3Al with Cr18-Ni8 stainless steel.  

PubMed

Fe3Al and Cr18-Ni8 stainless steel were diffusion-bonded in vacuum and a Fe3Al/Cr18-Ni8 interface with reaction layer was formed. Microstructure in the reaction layer at Fe3Al/Cr18-Ni8 interface was analyzed by means of scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). The growth of reaction layer with heating temperature (T) and holding time (t) was researched. The results indicate that FeAl, Fe3Al, Ni3Al, and alpha-Fe (Al) solid solution are formed in the reaction layer. These phases are favorable to promote the element diffusion and to accelerate the formation of the reaction layer at Fe3Al/Cr18-Ni8 interface. The growth of reaction layer obeys the parabolic law and its thickness (X) is expressed by X2 = 7.5 x 10(-4)exp(-83.59/RT)(t - t0). PMID:15797414

Wang, Juan; Li, Yajiang; Yin, Yansheng

2005-05-01

118

Molecular dynamics simulation of diffusion bonding of Al-Cu interface  

NASA Astrophysics Data System (ADS)

The effects of temperature on diffusion bonding of Al-Cu interface have been investigated by using molecular dynamics (MD) technique with the embedded atomic method (EAM) potentials. The simulated results indicate that the Cu atoms predominantly diffuse into the Al side in the process of diffusion bonding, and the thickness of the interfacial region depends on temperature, with higher temperatures resulting in larger thickness. In the course of diffusion bonding, the interfacial region became disordered. In addition, the Cu atoms diffuse at low ratios but can deeply diffuse into the interior of Al, and the Al atoms diffuse at high ratios but hardly diffuse into the interior of Cu. The results show that the appropriate temperature range for diffusion bonding of Al-Cu interface is 750-800 K, and the diffusion activation energies of Al and Cu are 0.77 eV and 0.50 eV, respectively. Finally, in this work, three diffusion mechanisms of Cu atoms in Al lattice have been found and the main diffusion mechanism is the nearest neighbor hopping mechanism.

Li, Chang; Li, Dongxu; Tao, Xiaoma; Chen, Hongmei; Ouyang, Yifang

2014-09-01

119

Lateral diffusion of receptor-ligand bonds in membrane adhesion zones: Effect of thermal membrane roughness  

E-print Network

The adhesion of cells is mediated by membrane receptors that bind to complementary ligands in apposing cell membranes. It is generally assumed that the lateral diffusion of mobile receptor-ligand bonds in membrane-membrane adhesion zones is slower than the diffusion of unbound receptors and ligands. We find that this slowing down is not only caused by the larger size of the bound receptor-ligand complexes, but also by thermal fluctuations of the membrane shape. We model two adhering membranes as elastic sheets pinned together by receptor-ligand bonds and study the diffusion of the bonds using Monte Carlo simulations. In our model, the fluctuations reduce the bond diffusion constant in planar membranes by a factor close to 2 in the biologically relevant regime of small bond concentrations.

H. Krobath; G. J. Schuetz; R. Lipowsky; T. R. Weikl

2007-03-19

120

The application of diffusion bonding in the manufacture of aeroengine components  

NASA Astrophysics Data System (ADS)

Rolls-Royce has developed and optimized diffusion bonding processes for the manufacture of advanced titanium alloy aeroengine structures and components. Both categories of the joining technique - 'liquid-phase' and 'solid-state' - are being applied in the production of both static fabrications and complex rotating parts. In order to utilize diffusion bonding processes in a production environment, the process parameters which contribute to consistent formation of joints of the required strength have been critically examined. Process variables include temperature, pressure, time, surface roughness and, in the case of liquid-phase diffusion bonding, interlayer composition, density and thickness. Mechanical testing (tensile, impact and fatigue) complemented by metallography has predominantly been used to identify the permitted variations in the processes for the realistic and economical production manufacture of high quality lightweight aeroengine fabrications. The development of a high integrity bond via optimized diffusion bonding processes has been fundamental to the development of Rolls-Royce's unique wide chord fan design concept.

Fitzpatrick, J. A.

121

Developing A Laser Shockwave Model For Characterizing Diffusion Bonded Interfaces  

SciTech Connect

12. Other advances in QNDE and related topics: Preferred Session Laser-ultrasonics Developing A Laser Shockwave Model For Characterizing Diffusion Bonded Interfaces 41st Annual Review of Progress in Quantitative Nondestructive Evaluation Conference QNDE Conference July 20-25, 2014 Boise Centre 850 West Front Street Boise, Idaho 83702 James A. Smith, Jeffrey M. Lacy, Barry H. Rabin, Idaho National Laboratory, Idaho Falls, ID ABSTRACT: The US National Nuclear Security Agency has a Global Threat Reduction Initiative (GTRI) which is assigned with reducing the worldwide use of high-enriched uranium (HEU). A salient component of that initiative is the conversion of research reactors from HEU to low enriched uranium (LEU) fuels. An innovative fuel is being developed to replace HEU. The new LEU fuel is based on a monolithic fuel made from a U-Mo alloy foil encapsulated in Al-6061 cladding. In order to complete the fuel qualification process, the laser shock technique is being developed to characterize the clad-clad and fuel-clad interface strengths in fresh and irradiated fuel plates. The Laser Shockwave Technique (LST) is being investigated to characterize interface strength in fuel plates. LST is a non-contact method that uses lasers for the generation and detection of large amplitude acoustic waves to characterize interfaces in nuclear fuel plates. However the deposition of laser energy into the containment layer on specimens surface is intractably complex. The shock wave energy is inferred from the velocity on the backside and the depth of the impression left on the surface from the high pressure plasma pulse created by the shock laser. To help quantify the stresses and strengths at the interface, a finite element model is being developed and validated by comparing numerical and experimental results for back face velocities and front face depressions with experimental results. This paper will report on initial efforts to develop a finite element model for laser shock.

James A. Smith; Jeffrey M. Lacy; Barry H. Rabin

2014-07-01

122

Low-pressure diffusion bonding of SAE 316 stainless steel by inserting a superplastic interlayer  

SciTech Connect

Diffusion bonding is a solid-state joining technique in which two similar or dissimilar materials are brought together under pressure at a temperature below the melting point of the materials. For a material with lower flow stress, the applied pressure needed to provide a intimate contact surface will also be low. Another advantage in this case is that even if the workpieces possess a rougher surface it can be effectively bonded. A superplastic alloy is a typical example of such a material with lower flow stress. Furthermore, a superplastic alloy possesses very fine grains and thus more grain boundary diffusion paths will be present, which provides another beneficial effect for diffusion bonding. However, most commercial technical alloys do not have superplastic characteristics. In order to use the above advantages of lower flow stress and more diffusion paths only existing for superplastic materials, an innovative process has been proposed. By inserting a superplastic interlayer with diffusion bonding compatibility in between the workpieces to be bonded, a better bond may be obtained. In the present study, a SAE 316 stainless steel was diffusion bonded by this method. A SuperDux 65 stainless steel plate was employed as its superplastic interlayer.

Yeh, M.S.; Chuang, T.H. [National Taiwan Univ., Taipei (Taiwan, Province of China)] [National Taiwan Univ., Taipei (Taiwan, Province of China)

1995-10-15

123

Vacuum outgassing from diffuse-absorptive baffle materials  

NASA Astrophysics Data System (ADS)

Quantitative measurements of outgassing for Martin black and a variety of metallic, diffuse absorptive baffle materials under development for stray light management are reported here. 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 x 10 exp -5 and 4 x 10 exp -5 moles/sq cm. Plasma sprayed beryllium, currently under development exhibited approximately an order of magnitude lower total water vapor outgassed during pumpdown.

Egert, Charles M.; Basford, J. A.

1991-01-01

124

Vacuum outgassing from diffuse-absorptive baffle materials  

NASA Astrophysics Data System (ADS)

Quantitative measurements of outgassing for Martin black and a variety of metallic, diffuse absorptive baffle materials under development for stray light management are reported here. 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 x 10 exp -5 and 4 x 10 exp -5 moles/sq cm. Plasma sprayed beryllium, currently under development exhibited approximately an order of magnitude lower total water vapor outgassed during pumpdown.

Egert, C. M.; Basford, J. A.

125

Bonding Mechanisms in Resistance Microwelding of 316 Low-Carbon Vacuum Melted Stainless Steel Wires  

NASA Astrophysics Data System (ADS)

Resistance microwelding (RMW) is an important joining process used in the fabrication of miniature instruments, such as electrical and medical devices. The excellent corrosion resistance of 316 low-carbon vacuum melted (LVM) stainless steel (SS) wire makes it ideal for biomedical applications. The current study examines the microstructure and mechanical properties of crossed resistance microwelded 316LVM wire. Microtensile and microhardness testing was used to analyze the mechanical performance of welds, and fracture surfaces were examined using scanning electron microscopy. Finally, a bonding mechanism is proposed based on optimum joint breaking force (JBF) using metallurgical observations of weld cross sections. Moreover, comparisons with RMWs of Ni, Au-plated Ni, and SUS304 SS wire are discussed.

Khan, M. I.; Kim, J. M.; Kuntz, M. L.; Zhou, Y.

2009-04-01

126

Diffusion bonding and its application to manufacturing. [for joining of metal parts  

NASA Technical Reports Server (NTRS)

In its simplest form diffusion bonding is accomplished by placing clean metal surfaces together under a sufficient load and heating. The natural interatomic attractive force between atoms transforms the interface into a natural grain boundary. Therefore, in principle, the properties of the bond area are identical to those of the parent metal. Other advantages of diffusion bonding over conventional methods of bonding include freedom from residual stresses, excessive deformation, foreign metals, or changed crystal structures. Stainless steels, nickel-base superalloys, and aluminum alloys have all been successfully joined. Complex hardware, including integrated flueric devices, jet engine servovalves, and porous woven structures have been fabricated. The processing involved is discussed, along with such theoretical considerations as the role of metal surfaces, the formation of metal contact junctions, and the mechanisms of material transport in diffusion bonding.

Spurgeon, W. M.

1972-01-01

127

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.

2014-01-01

128

Coupled stress-diffusion analysis for durability study in adhesively bonded joints  

Microsoft Academic Search

Coupled stress-diffusion finite element analyses, which are required to study the durability of adhesively bonded joints aged in hot\\/wet environment, are presented. Two bonded joints have been considered in this study, namely, single lap joint and butt joint. The joints were immersed in water at 60C for up to 60 weeks. For both joints, transient finite element diffusion analyses have

M. M. Abdel Wahab; A. D. Crocombe; A. Beevers; K. Ebtehaj

2002-01-01

129

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

130

Studying of micro-bonding in diffusion welding joint for composite  

Microsoft Academic Search

This paper reports the preliminary investigation of the micro-bonding of reinforcement\\/matrix and reinforcement\\/reinforcement in a diffusion welded joint for Al2O3p\\/6061Al composite and analyzes the microstructure and performance of the welded joint. Experimental results show that the interface of the matrix\\/reinforcement has better bonding only when the diffusion welding temperature is higher than the solid phase line of Al2O3p\\/6061Al composite. It

Liu Liming; Zhu Meili; Pan Longxiu; Wu Lin

2001-01-01

131

Interface Microstructure and Strength Properties of the Diffusion-Bonded Joints of Titanium ?Cu Interlayer ? Stainless Steel  

NASA Astrophysics Data System (ADS)

In the present study, copper was used as an intermediate material in diffusion bonding between titanium and stainless steel. The process was carried out in the temperature range of 850 C to 1000 C for 60 minutes and at 900 C for 30 to 150 minutes under the compressive stress of 3 MPa in a vacuum. The effects of temperature and time on the microstructure of Ti ?Cu ? stainless steel diffusion-bonded joints were studied. The interface microstructures of the bonded assemblies were observed in optical and scanning electron microscopes and an electron probe microanalyzer. Formation of various types of reaction products near the interface was detected using the X-ray diffraction technique. The maximum tensile and shear strength of 101 pct of that of Ti and of 86 pct of that of Ti, respectively, along with 8.5 pct elongation, were obtained at 900 C for 60 minutes. Observation of fracture surfaces demonstrates that failure takes place through the SS-Cu interface.

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

2008-09-01

132

Formation of Nitrogen-Pearlite in the Diffusion Bonding of Sialon to 316L Stainless Steel  

Microsoft Academic Search

The objective of this study is to investigate the interface reaction and diffusion bonding between 316L stainless steel and sialon. Bonding was carried out in a hot press at 1250 C under the pressure of 15 MN\\/m2 for 1 hour and was cooled slowly in the furnace to prevent the mismatch between the sialon and the steel. Scanning Electron microscopy

P. Hussain; O. Mamat; M. Mohammad; W. M. N. W. Jaafar

2010-01-01

133

Diffusion bonding of alumina dispersion-strengthened copper to 316 stainless steel with interlayer metals  

Microsoft Academic Search

Diffusion bonding of alumina dispersion-strengthened copper (DS Cu) to 316 stainless steel was carried out with interlayer metals such as Au, Cu and Ni foil in order to investigate the influence of the interlayer metals and bonding conditions on strength of the joints. The tensile strength of joints with an Au interlayer was superior to those with Cu and Ni

H Nishi; T Araki; M Eto

1998-01-01

134

SOLID-STATE DIFFUSION BONDING OF INCONEL ALLOY 718 TO 17-4 PH STAINLESS STEEL  

Microsoft Academic Search

Solid-state diffusion bonding of Inconel alloy 718 to 17-4 PH stainless steel was studied. Mechanical tests and metallographic examinations were used to evaluate the joint quality. The effect of bonding pressure on the joint integrity was assessed. In all joints, failure occurred nearly without plastic deformation. The thermal residual stress generated from cooling to room temperature was calculated by finite

Zhang Guoge; R. S. Chandel; H. P. Seow

2001-01-01

135

Interface microstructure of diffusion bonded Ni 3Al intermetallic alloy and austenitic stainless steel  

Microsoft Academic Search

The diffusion bonding of a Ni3Al intermetallic alloy to an austenitic stainless steel has been carried out at temperatures 950, 1000 and 1050C. The influence of bonding temperature on the microstructural development and hardness across the joint region has been determined. The microvoids in the interface have been found to decrease with increasing bonding temperature. The intermetallic phase Al3Ni has

Adnan al?k

2009-01-01

136

Electrical and thermal properties of the interface at diffusion-bonded and soldered 304 stainless steel and copper bimetal  

Microsoft Academic Search

The 304 stainless steel and copper were joined by diffusion bonding and soldering with different bonding conditions. The microstructure of the interfaces of diffusion-bonded bimetal was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Electrical resistivity of the interface of the diffusion-bonded samples (ERIDB) and electrical resistivity of the soldered interface (ERIS) were measured in the temperature range

O Yilmaz; H elik

2003-01-01

137

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

138

Bond Graph Modeling of Current Diffusion in Magnetic Cores Herv Morel, Bruno Allard, Sabrine M'Rad, Cyril Buttay  

E-print Network

variational approximation of equation (2) yields to a bond graph of the skin effect in a rectangularBond Graph Modeling of Current Diffusion in Magnetic Cores Hervé Morel, Bruno Allard, Sabrine M, F-69621 Villeurbanne Cedex, France KEYBOARD: Bond Graphs, Variational approximation, Diffusive

Paris-Sud XI, Université de

139

Diffusion welding. [heat treatment of nickel alloys following single step vacuum welding process  

NASA Technical Reports Server (NTRS)

Dispersion-strengthened nickel alloys are sanded on one side and chemically polished. This is followed by a single-step welding process wherein the polished surfaces are forced into intimate contact at 1,400 F for one hour in a vacuum. Diffusion, recrystallization, and grain growth across the original weld interface are obtained during postheating at 2,150 F for two hours in hydrogen.

Holko, K. H. (inventors)

1974-01-01

140

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

141

Diffusion Bonding of Silicon Carbide for a Micro-Electro-Mechanical Systems Lean Direct Injector  

NASA Technical Reports Server (NTRS)

Robust approaches for joining silicon carbide (SiC) to silicon carbide sub-elements have been developed for a micro-electro-mechanical systems lean direct injector (MEMS LDI) application. The objective is to join SiC sub-elements to form a leak-free injector that has complex internal passages for the flow and mixing of fuel and air. Previous bonding technology relied upon silicate glass interlayers that were not uniform or leak free. In a newly developed joining approach, titanium foils and physically vapor deposited titanium coatings were used to form diffusion bonds between SiC materials during hot pressing. Microscopy results show the formation of well adhered diffusion bonds. Initial tests show that the bond strength is much higher than required for the component system. Benefits of the joining technology are fabrication of leak free joints with high temperature and mechanical capability.

Halbig, Michael C.; Singh, Mrityunjay; Shpargel, Tarah P.; Kiser, James D.

2006-01-01

142

Study of the Interface Characteristic of Be\\/HR1 Stainless Steel Following Diffusion Bonding  

Microsoft Academic Search

The interface structure of Be\\/HR-1 stainless steel (SS) joint following diffusion bonding was investigated. Metallurgical observation, electron scanning microscopy, X-ray diffraction and scanning Auger microspectroscopy were performed for basic evaluation of bonded joints. There are intermetallic compounds such as Be11Fe and Be12Cr in the interface region of Be\\/SS joints, which drastically reduce the mechanical strength of the joints. Cu, Ag

Peng-Cheng Zhang; Bin Bai; Jiang-Rong Yang; Jue-Sheng Zou; Shou-Qi Zhou

2003-01-01

143

Diffusion bonding behaviour of austenitic stainless steel containing titanium and alumina  

Microsoft Academic Search

A study has been conducted to identify the function of titanium in 1 Cr18Ni9Ti steel and the effects of fabrication temperature, pressure, time and other variables on the strengths of diffusion-bonded alumina-1Cr18Ni9Ti. At temperatures of 750 to 1200C, 1Cr18Ni9Ti steel was successfully bonded to alumina, with a maximum tensile strength of 19MPa. By EPMA titanium segregated to the interface of

Huang Rong

1992-01-01

144

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

SciTech Connect

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 deg.C and fast neutron fluxes of {approx}3.10{sup 9} n/cm{sup 2}.s. At the moment, little information is available about glass-metal joints suitable for ITER. Therefore, we performed mechanical and thermal tests on some prototypes of an aluminium diffusion bonded optical window. Finite element modeling with Abaqus code was used to understand the experimental results. The prototypes were helium leaking probably due to very tiny cracks in the interaction layer between the steel and the aluminium. However, they were all able to withstand a thermal cycling test up to 200 deg. C; no damage could be seen after the tests by visual inspection. The prototypes successfully passed push-out test with a 500 N load. During the destructive push-out tests the prototypes broke at a 6-12 kN load between the aluminium layer and the steel or the glass, depending on the surface quality of the glass. The microanalysis of the joints has also been performed. The finite element modeling of the push-out tests is in a reasonable agreement with the experiments. According to the model, the highest thermal stress is created in the aluminium layer. Thus, the aluminium joint seems to be the weakest part of the prototypes. If this layer is improved, it will probably make the prototype helium leak tight and as such, a good ITER window candidate. (authors)

Jacobs, M. [Flemish Inst. for Technological Research, Mol (Belgium); Van Oost, G. [Dept. of Applied Physics, Ghent Univ., Ghent (Belgium); Degrieck, J.; De Baere, I. [Dept. of Materials Science and Engineering, Ghent Univ., Ghent (Belgium); Gusarov, A. [Belgian Nuclear Research Center, Mol (Belgium); Gubbels, F. [TNO, Eindhoven (Netherlands); Massaut, V. [Belgian Nuclear Research Center, Mol (Belgium)

2011-07-01

145

Study of the Interface Characteristic of Be/HR-1 Stainless Steel Following Diffusion Bonding  

NASA Astrophysics Data System (ADS)

The interface structure of Be/HR-1 stainless steel (SS) joint following diffusion bonding was investigated. Metallurgical observation, electron scanning microscopy, X-ray diffraction and scanning Auger microspectroscopy were performed for basic evaluation of bonded joints. There are intermetallic compounds such as Be11Fe and Be12Cr in the interface region of Be/SS joints, which drastically reduce the mechanical strength of the joints. Cu, Ag and Al barriers can block effective inter-diffusion of Be and HR-1 stainless steel, then forming brittle phases.

Zhang, Peng-Cheng; Bai, Bin; Yang, Jiang-Rong; Zou, Jue-Sheng; Zhou, Shou-Qi

146

Investigation of micro-crack occurrence conditions in diffusion bonded Cu304 stainless steel couple  

Microsoft Academic Search

Kirkendall effect has been used for calculation of intrinsic diffusion coefficients at the interface of diffusion bonded 304 stainless steel and electrolytic copper. Welding conditions have been chosen at temperatures in the range 700900C for times of up to 30min and pressures of up to 12MPa. Microstructure of samples has been assessed using metallography, tensile testing, and scanning electron microscopy

Osman Yilmaz; Mustafa Aksoy

2002-01-01

147

Solid-state diffusion bonding of closed-cell aluminum foams  

Microsoft Academic Search

Solid-state diffusion bonding (DB) was demonstrated for joining closed-cell aluminum foams (ALPORAS). A superplastic 5083 aluminum alloy sheet was inserted between the foams to assist the DB process. Microscopic observation revealed that the cell wall of the foams penetrated into the 5083 alloy sheet and their boundary partly disappeared. Energy dispersion X-ray spectrometer (EDS) confirmed the diffusion of magnesium element

K Kitazono; A Kitajima; E Sato; J Matsushita; K Kuribayashi

2002-01-01

148

TEM and HRTEM Characterization of TiAl Diffusion Bonds Using Ni/Al Nanolayers.  

PubMed

Diffusion bonding of TiAl alloys can be enhanced by the use of reactive nanolayer thin films as interlayers. Using these interlayers, it is possible to reduce the conventional bonding conditions (temperature, time, and pressure) and obtain sound and reliable joints. The microstructural characterization of the diffusion bond interfaces is a fundamental step toward understanding and identifying the bonding mechanisms and relating them to the strength of the joints. The interface of TiAl samples joined using Ni/Al nanolayers was characterized by transmission electron microscopy and scanning transmission electron microscopy. Microstructural characterization of the bond revealed that the interfaces consist of several thin layers of different composition and grain size (nanometric and micrometric). The bonding temperature (800, 900, or 1,000C) determines the grain size and thickness of the layers present at the interface. Phase identification by high-resolution transmission electron microscopy combined with fast Fourier transform and electron energy-loss spectroscopy analyses reveals the presence of several intermetallic compounds: AlTiNi, NiAl, and Al2TiNi. For bonds produced at 800 and 900C, nanometric grains of Ti were detected at the center of the interface. PMID:25170561

Simes, Snia; Viana, Filomena; Ramos, Ana S; Vieira, Maria T; Vieira, Manuel F

2014-08-29

149

Chemically bonded ceramic matrix composites: Densification and conversion to diffusion bonding  

SciTech Connect

Chemically bonded ceramics appear to be a promising alternative route for near-net shape fabrication of multi-phase ceramic matrix composites (CMC`s). The hydraulic (and refractory) properties of fine mono-calcium aluminate (CaAl{sub 2}O{sub 4}) powders were used as the chemically bonding matrix phase, while calcia stabilized zirconia powders were the second phase material. Samples containing up to 70 wt% (55 vol%) zirconia have been successfully compacted and sintered. Various processing techniques were evaluated. Processing was optimized based on material properties, dilatometry and simultaneous thermal analysis (DTA/TGA). The physical characteristics of this novel CMC were characterized by hardness, density, and fracture toughness testing. Microstructures were evaluated by SEM and phase identification was verified using XRD.

Johnson, B.R.; Guelguen, M.A.; Kriven, W.M. [Univ. of Illinois, Urbana, IL (United States). Dept. of Materials Science and Engineering

1995-10-01

150

Thermomechanical analysis of diffusion-bonded tungsten/EUROFER97 with a vanadium interlayer  

NASA Astrophysics Data System (ADS)

Earlier basic investigations revealed that diffusion bonding between tungsten and RAFM-steel at a relatively low temperature using a thin low-activation vanadium interlayer having a CTE between that of the parent materials can significantly reduce the residual stresses and produce defect-free bond interfaces. The joint has a high strength as well as sufficient ductility and toughness especially at the test temperature of about 550 C. To apply this knowledge in fusion power plants, particularly in divertors, an acceptable lifetime of such structural joints is required, since they are exposed to high thermomechanical cyclic loading. To simulate the possible operational conditions of a He-cooled divertor, diffusion-bonded specimens are loaded by thermal cycling in a temperature range between 350 C and 500 C and a constant tensile stress based on the calculation of the internal pressure of the divertor thimble. The aim of this experimental work is to check the resistance of the diffusion-bonded W/EUROFER97 against ratcheting during thermomechanical loading and analyze the evolution of microstructures of the joint especially along the bond interfaces.

Basuki, Widodo Widjaja; Dahm, Ralf; Aktaa, Jarir

2014-12-01

151

Diffusion bonding of silicon nitride to austenitic stainless steel with metallic interlayers  

Microsoft Academic Search

This article deals with the diffusion bonding of hot-pressed silicon nitride (HPSN) to austenitic stainless steel using metallic interlayers. Experiments were carried out with Fe, Ni, invar, and kovar as the interlayer material. The best results were obtained with invar interlayers. Using these interlayers, joints having an average shear strength of 95 MPa were produced. The reaction layer formed at

B. T. J. Stoop; G. den Ouden

1995-01-01

152

Low-pressure diffusion bonding of SAE 316 stainless steel by inserting a superplastic interlayer  

Microsoft Academic Search

Diffusion bonding is a solid-state joining technique in which two similar or dissimilar materials are brought together under pressure at a temperature below the melting point of the materials. For a material with lower flow stress, the applied pressure needed to provide a intimate contact surface will also be low. Another advantage in this case is that even if the

M. S. Yeh; T. H. Chuang

1995-01-01

153

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

154

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

155

Numerical modelling of transient liquid phase bonding and other diffusion controlled phase changes  

Microsoft Academic Search

Diffusion in material of inhomogeneous composition can induce phase changes, even at a constant temperature. A transient liquid phase (TLP), in which a liquid layer is formed and subsequently solidifies, is one example of such an isothermal phase change. This phenomenon is exploited industrially in TLP bonding and sintering processes. Successful processing requires an understanding of the behaviour of the

T. C. I LLINGWORTH; I. O. GOLOSNOY; T. W. C LYNE

2005-01-01

156

Low cycle fatigue strength of diffusion bonded joints of alumina dispersion-strengthened copper to stainless steel  

Microsoft Academic Search

It is proposed that the first wall and divertor components of ITER employ alumina dispersion-strengthened copper (DS Cu) joined to austenitic stainless steel. In this work, low cycle fatigue tests were performed on a direct diffusion bonded joint, a diffusion bonded joint with a Au interlayer, stainless steel and DS Cu in order to investigate their fatigue strength and fracture

H. Nishi; T Araki

2000-01-01

157

Diffusion bonding of silicon nitride to austenitic stainless steel with metallic interlayers  

NASA Astrophysics Data System (ADS)

This article deals with the diffusion bonding of hot-pressed silicon nitride (HPSN) to austenitic stainless steel using metallic interlayers. Experiments were carried out with Fe, Ni, invar, and kovar as the interlayer material. The best results were obtained with invar interlayers. Using these interlayers, joints having an average shear strength of 95 MPa were produced. The reaction layer formed at the ceramic-interlayer interface during the diffusion-bonding process consists of a porous zone anchored in the silicon nitride and a diffusion zone extending in the interlayer. No silicides were detected. The formation of the joint is governed by the decomposition of the silicon nitride. The free silicon generated by the decomposition reaction diffuses into the interlayer, whereas part of the free nitrogen disappears to the surface, the remainder being trapped in the form of pores. The mechanical strength of the joint depends strongly on the residual stress generated in the joint during cooling from diffusion-bonding temperature to room temperature due to the difference in thermal shrinkage between the ceramic and the metal. The residual stress level is directly related to the thickness of the reaction layer.

Stoop, B. T. J.; den Ouden, G.

1995-01-01

158

Effect of Bonding Time 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)

In the current study, 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 was carried out in vacuum. Uniaxial compressive pressure and temperature were kept at 4 MPa and 1023 K (750 C), respectively, and the bonding time was varied from 30 to 120 minutes in steps of 15 minutes. Scanning electron microscopy images, in backscattered electron mode, revealed the layerwise Ti-Ni-based intermetallics like either Ni3Ti or both Ni3Ti and NiTi at titanium alloy-nickel (TiA/Ni) interface, whereas nickel-stainless steel (Ni/SS) interface was free from intermetallic phases for all the joints. Chemical composition of the reaction layers was determined by energy dispersive spectroscopy (SEM-EDS) and confirmed by X-ray diffraction study. Maximum tensile strength of ~382 MPa along with ~3.7 pct ductility was observed for the joints processed for 60 minutes. It was found that the extent of diffusion zone at Ni/SS interface was greater than that of TiA/Ni interface. From the microhardness profile, fractured surfaces, and fracture path, it was demonstrated that the failure of the joints was initiated and propagated apparently at TiA/Ni interface near Ni3Ti intermetallic for bonding time less than 90 minutes, and through Ni for bonding time 90 minutes and greater.

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

2014-04-01

159

Hot pressing diffusion bonding of a titanium alloy to a stainless steel with an aluminum alloy interlayer  

Microsoft Academic Search

The probability and appropriate processing parameters of hot pressing diffusion bonding (HPDW) of a titanium alloy (TC4) to a stainless steel (1Cr18Ni9Ti) with an aluminum alloy (LF6) interlayer have been investigated. The microstructure of the bonded joints has been observed by optical microscopy, SEM, XRD and EDX, and the main factors affecting hot pressing and diffusion bonding process were analyzed.

P. He; X. Yue; J. H. Zhang

2008-01-01

160

Solid-state diffusion bonding of alumina dispersion-strengthened copper to 316 stainless steel  

NASA Astrophysics Data System (ADS)

Joints of alumina dispersion-strengthened copper (DS Cu) to 316 stainless steel are expected to be used for the cooling pipes of the divertor in the ITER project. In this study, solid-state diffusion bonding has been carried out to investigate the influence of the bonding conditions on the strength of the joints. The bonding temperatures had a greater effect on the strength of the joints than the pressures or hold time. The tensile strength of the joint, which was obtained at a bonding temperature of 1173 K and pressure of 4.8 MPa, was almost the same as that of DS Cu. The absorbed energy of the joints was lower than that of DS Cu, though it increased with increasing temperature. The low cycle fatigue strength of the joint was nearly equal to that of the DS Cu. Intermetallic compounds were observed and had an influence on the impact strength.

Nishi, H.; Muto, Y.; Sato, K.

1994-09-01

161

Microstructural characterization and properties of Al\\/Cu\\/steel diffusion bonded joints  

Microsoft Academic Search

We prepared Al\\/Cu\\/steel composite with a gradient structure using a vacuum hot-pressed diffusion method and investigated the\\u000a Al\\/Cu\\/steel interface. The results show that a supersaturated solid solution with a thickness of about 2 um formed in the\\u000a Cu\\/steel diffusion zone. Two kinds of intermetallic compounds, Cu9Al4 adjacent to the Cu side and CuAl2 adjacent to the Al side, formed at

Xiaole Cheng; Yimin Gao; Hanguang Fu; Jiandong Xing; Bingzhe Bai

2010-01-01

162

Microstructural characterization of the Al\\/Cu\\/steel diffusion bonded joint  

Microsoft Academic Search

A vacuum hot-pressed diffusion method was used to prepare an Al\\/Cu\\/steel composite with a gradient structure. The Al\\/Cu interface\\u000a was investigated layer by layer by means of scanning electron microscopy, energy dispersive X-ray spectrometry, electron probe\\u000a microanalysis, and Vickers microhardness. The results show that two kinds of intermetallic compounds, Cu9Al4 adjacent to the Cu side and CuAl2 adjacent to the

Xiaole Cheng; Bingzhe Bai; Yimin Gao; Chun Feng

2009-01-01

163

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

164

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

165

Microstructure of Diffusion-Bonded Mg-Ag-Al Multilayer Composite Materials  

NASA Astrophysics Data System (ADS)

Mg-Al bonded composite materials expand Mg and Al alloys' applications by combining their unique performances together. However, the formation of Mg-Al intermetallic compounds in interface zone of Mg/Al directly-bonded joint seriously obstructs its further development. To solve this problem, Mg-Ag-Al multilayer composite materials have been successfully prepared by diffusion bonding technology. The effect of key process parameter (bonding temperature) on microstructure of this material has been mainly investigated. The results show that Mg and Al were well bonded by using silver interlayer when the bonding temperature exceeded 370C. But Mg17Al12 and Mg2Al3 compounds were formed in the interface zone at temperatures higher than 420C. By means of controlling the bonding temperature (380 C-420 C), silver interlayer effectively restrained the generation of Mg-Al intermetallic compounds, and Mg-Ag intermetallic compounds (Mg3Ag, MgAg) were formed in the interface zone instead.

Wang, Yiyu; Luo, Guoqiang; Zhang, Jian; Shen, Qiang; Zhang, Lianmeng

2013-03-01

166

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

2014-04-01

167

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

168

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

169

New method to diffusion bond superalloys A. A. Shirzadi and E. R. Wallach  

E-print Network

, such as brazing and transient liquid phase (TLP) diffusion bonding, normally require long bonding times and superalloy PWA647) Superalloy Cr Co Mo W Al Ti B C Si Zr Others Inconel 718 18.3 0.1 2.85 0.5 0.92 0.003 0.02 0.08 0.01 0.08Mn, 0.0004S Inconel 738 16 8.5 1.75 2.6 3.4 3.4 0.01 0.17 0.1 1.75Ta, 0.9Nb C1023 15

Cambridge, University of

170

Visible to vacuum-UV range optical absorption of oxygen dangling bonds in amorphous SiO{sub 2}  

SciTech Connect

Synthetic silica glass with an optical absorption spectrum dominated by oxygen dangling bonds (nonbridging oxygen hole centers, or NBOHCs) and having negligible (<1%) contribution from the usually copresent Si dangling bonds (E'-centers), was prepared by room temperature ultraviolet photobleaching of high SiOH content (''wet'') silica, irradiated by F{sub 2} laser (7.9 eV) at T = 80 K. This allowed us to obtain the up-to-now controversial optical absorption spectrum of NBOHC in the ultraviolet and vacuum-ultraviolet (UV-VUV) region of the spectrum and to show that it is semicontinuous from 4 to 7.8 eV and cannot be represented by a pair of distinct Gaussian bands. Since NBOHC is one of the main UV-VUV range optical absorbers in silica, its spectral shape provides a tool to disentangle contributions of different color centers to optical losses in this spectral region.

Skuja, Linards [Institute of Solid State Physics, University of Latvia, Kengaraga iela 8, LV1063 Riga (Latvia); Kajihara, Koichi [Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji 192-0397 (Japan); Hirano, Masahiro [Frontier Collaborative Research Center, Mail Box S2-13, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Hosono, Hideo [Frontier Collaborative Research Center, Mail Box S2-13, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

2011-11-15

171

Diffusion bonding/superplastic forming of Ti-6Al-6V-2Sn/SUS 304 stainless steel/Ti-6Al-6V-2Sn  

NASA Astrophysics Data System (ADS)

The superplasticity of the Ti- 6Al- 6V- 2Sn alloy for different temperatures was evaluated by single-sheet free blowing. The optimal superplastic temperature for the Ti- 6Al- 6V- 2Sn alloy was found to be 850 C. Diffusion bonding of Ti- 6Al- 6V- 2Sn and 304 stainless steel was carried out in a vacuum. The interface of both bonded alloys was examined by EPMA. The concentration profile of Ni exhibited a peak at the interlayer and a valley adjacent it, whereas that of Cr exhibited a peak where Ni showed the valley. X- ray diffraction (XRD) analyses showed that the Fe 2 Ti, NiTi, and CrMn Intermetallic compounds and the Cr element formed at the interface. The thickness profiles of the blown specimens were measured and compared with theoretical calculations.

Shyu, J. S.; Chuang, T. H.

1996-02-01

172

An experimental investigation of phase transformation superplastic diffusion bonding of titanium alloy to stainless steel  

Microsoft Academic Search

The solid-state direct diffusion bonding of a near ?-phase titanium alloy to an austenitic stainless steel by means of the\\u000a phase transformation superplasticity (PTSP) caused by the cycles of heating and cooling has been carried out. The test results\\u000a showed that, under the conditions of Tmax = 890C, Tmin = 800C, cyclic number of heating and cooling N = 10

G. M. Sheng; J. W. Huang; B. Qin; B. Zhou; S. Y. Qiu; C. Li

2005-01-01

173

Diffusion bonding of silicon nitride to austenitic stainless steel with metallic interlayers  

Microsoft Academic Search

This article deals with the diffusion bonding of hot-pressed silicon nitride (HPSN) to austenitic stainless steel using metallic\\u000a interlayers. Experiments were carried out with Fe, Ni, invar, and kovar as the interlayer material. The best results were\\u000a obtained with invar interlayers. Using these interlayers, joints having an average shear strength of 95 MPa were produced.\\u000a The reaction layer formed at

B. T. J. Stoop; G. den Ouden

1995-01-01

174

Diffusion bonded transition joints of titanium to stainless steel with improved properties  

Microsoft Academic Search

Diffusion bonding was carried out to produce transition joints between commercially pure titanium (cp Ti) and 304 stainless steel (304 ss) in the temperature range of 800950C, under uniaxial pressure of 3 MPa for 5.4 Ks. The transition joints were evaluated by tensile testing, light microscopy, electron probe micro-analysis and X-ray diffraction. The study indicates that transition joints achieve 76%

M. Ghosh; S. Chatterjee

2003-01-01

175

Interface microstructures in the diffusion bonding of a titanium alloy Ti 6242 to an INCONEL 625  

Microsoft Academic Search

A Ti6242 alloy has been diffusion bonded to a superalloy INCONEL 625. The microstructures of the as-processed products have\\u000a been analyzed using optical metallography, scanning electron microscope (SEM), and scanning transmission electron microscope\\u000a (STEM) techniques. The interdiffusion of the different elements through the interface has been determined using energy-dispersive\\u000a spectroscopy (EDS) microanalysis in both a SEM and a STEM. Several

B. Alemn; I. Gutirrez; J. J. Urcola

1995-01-01

176

Numerical modelling of transient liquid phase bonding and other diffusion controlled phase changes  

Microsoft Academic Search

Diffusion in material of inhomogeneous composition can induce phase changes, even at a constant temperature. A transient liquid\\u000a phase (TLP), in which a liquid layer is formed and subsequently solidifies, is one example of such an isothermal phase change.\\u000a This phenomenon is exploited industrially in TLP bonding and sintering processes. Successful processing requires an understanding\\u000a of the behaviour of the

T. C. Illingworth; I. O. Golosnoy; V. Gergely; T. W. Clyne

2005-01-01

177

Influence of silicon dangling bonds on germanium thermal diffusion within SiO{sub 2} glass  

SciTech Connect

We study the influence of silicon dangling bonds on germanium thermal diffusion within silicon oxide and fused silica substrates heated to high temperatures. By using scanning electron microscopy and Rutherford backscattering spectroscopy, we determine that the lower mobility of Ge found within SiO{sub 2}/Si films can be associated with the presence of unsaturated SiO{sub x} chemical bonds. Comparative measurements obtained by x-ray photoelectron spectroscopy show that 10% of silicon dangling bonds can reduce Ge desorption by 80%. Thus, the decrease of the silicon oxidation state yields a greater thermal stability of Ge inside SiO{sub 2} glass, which could enable to considerably extend the performance of Ge-based devices above 1300?K.

Barba, D.; Martin, F.; Ross, G. G. [INRS Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel-Boulet, Varennes, Qubec J3X 1S2 (Canada); Cai, R. S.; Wang, Y. Q. [The Cultivation Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Demarche, J.; Terwagne, G. [LARN, Centre de Recherche en Physique de la Matire et du Rayonnement (PMR), University of Namur (FUNDP), B-5000 Namur (Belgium); Rosei, F. [INRS Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel-Boulet, Varennes, Qubec J3X 1S2 (Canada); Center for Self-Assembled Chemical Structures, McGill University, Montreal, Quebec H3A 2K6 (Canada)

2014-03-17

178

TEM Observation of the Ti Interlayer Between SiC Substrates During Diffusion Bonding  

NASA Technical Reports Server (NTRS)

Diffusion bonding was carried out to join SiC to SiC substrates using titanium interlayers. In this study, 10 m and 20 m thick physical vapor deposited (PVD) Ti surface coatings, and 10 and 20 m thick Ti foils were used. Diffusion bonding was performed at 1250 C for PVD Ti coatings and 1200 C for Ti foil. This study investigates the microstructures of the phases formed during diffusion bonding through TEM and selected-area diffraction analysis of a sample prepared with an FIB, which allows samples to be taken from the reacted area. In all samples, Ti3SiC2, Ti5Si3Cx and TiSi2 phases were identified. In addition, TiC and unknown phases also appeared in the samples in which Ti foils were used as interlayers. Furthermore, Ti3SiC2 phases show high concentration and Ti5Si3Cx formed less when samples were processed at a higher temperature and thinner interlayer samples were used. It appears that the formation of microcracks is caused by the presence of intermediate phase Ti5Si3Cx, which has anisotropic thermal expansion, and by the presence of an unidentified Ti-Si-C ternary phase with relatively low Si content.

Tsuda, Hiroshi; Mori, Shigeo; Halbig, Michael C.; Singh, Mori

2012-01-01

179

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

180

Role of interfacial carbon layer in the thermal diffusivity/conductivity of silicon carbide fiber-reinforced reaction-bonded silicon nitride matrix composites  

NASA Technical Reports Server (NTRS)

Experiments were carried out on samples of reaction-bonded silicon nitride uniaxially reinforced by SiC monofilaments with and without a 3-micron-thick carbon-rich coating. It is found that a combination of a carbon coatings on the fibers and an interfacial gap due to the thermal expansion mismatch in the composite can significantly (by a factor of 2) lower the effective thermal diffusivity in the direction transverse to the fiber. At atmospheric pressure, gaseous conduction across the interfacial gap makes a significant contribution to the heat transfer across the interface, indicated by significantly lower values of the effective thermal diffusivity under vacuum than in nitrogen or helium at atmospheric pressure.

Bhatt, Hemanshu; Donaldson, Kimberly Y.; Hasselman, D. P. H.; Bhatt, Ramakrishna T.

1992-01-01

181

Formation of Nitrogen-Pearlite in the Diffusion Bonding of Sialon to 316L Stainless Steel  

NASA Astrophysics Data System (ADS)

The objective of this study is to investigate the interface reaction and diffusion bonding between 316L stainless steel and sialon. Bonding was carried out in a hot press at 1250 C under the pressure of 15 MN/m2 for 1 hour and was cooled slowly in the furnace to prevent the mismatch between the sialon and the steel. Scanning Electron microscopy (SEM) revealed the interdiffusion and intereaction between the steel and the sialon. The elements diffusing into sialon were illustrated by the Energy Dispersive Spectrometer (EDS) analysis where the presence of Fe, Cr, Ni and Mn are significant. The formation of nitrogen pearlite can be described as a result of the reaction between the stainless steel and the silicon nitride component of sialon which release nitrogen. Mechanical behavior of the nitrogen diffused layer was also investigated using microhardness tester and at the reaction layer an increase in hardness was observed. Conclusion can be deduced that the formation of nitrogen pearlite in the stainless steel is quite significant especially on joining sialon to as-received nitrogen-free austenite stainless steel. The formation of nitrogen pearlite could be understood by the diffusion of nitrogen into the stainless steel. Thus, the continuous precipitates form lamellar nitrogen pearlite.

Hussain, P.; Mamat, O.; Mohammad, M.; Jaafar, W. M. N. W.

2010-03-01

182

Fabrication and Design Aspects of High-Temperature Compact Diffusion Bonded Heat Exchangers  

SciTech Connect

The Very High Temperature Reactor (VHTR) using gas-cooled reactor technology is anticipated to be the reactor type for the Next Generation Nuclear Plant (NGNP). In this reactor concept with an indirect power cycle system, a high-temperature and high integrity Intermediate Heat Exchanger (IHX) with high effectiveness is required to efficiently transfer the core thermal output to a secondary fluid for electricity generation, hydrogen production, and/or industrial process heat applications. At present, there is no proven IHX concept for VHTRs. The current Technology Readiness Level (TRL) status issued by NGNP to all components associated with the IHX for reduced nominal reactor outlet temperatures of 750800 degrees C is 3 on a 110 scale, with 10 indicating omplete technological maturity. Among the various potential IHX concepts available, diffusion bonded heat exchangers (henceforth called printed circuit heat exchangers, or PCHEs) appear promising for NGNP applications. The design and fabrication of this key component of NGNP with Alloy 617, a candidate high-temperature structural material for NGNP applications, are the primary focus of this paper. In the current study, diffusion bonding of Alloy 617 has been demonstrated, although the optimum diffusion bonding process parameters to engineer a quasi interface-free joint are yet to be determined. The PCHE fabrication related processes, i.e., photochemical etching and diffusion bonding are discussed for Alloy 617 plates. In addition, the authors experiences with these non-conventional machining and joining techniques are discussed. Two PCHEs are fabricated using Alloy 617 plates and are being experimentally investigated for their thermal-hydraulic performance in a High-Temperature Helium Facility (HTHF). The HTHF is primarily of Alloy 800H construction and is designed to facilitate experiments at temperatures and pressures up to 800 degrees C and 3 MPa, respectively. Furthermore, some preliminary microstructural and mechanical property characterization studies of representative diffusion bonded Alloy 617 specimens are presented. The characterization studies are restricted and less severe from an NGNP perspective but provide sufficient confidence to ensure safe operation of the heat exchangers in the HTHF. The test results are used to determine the design operating conditions for the PCHEs fabricated.

Sai K. Mylavarapu; Richard N. Christensen; Raymond R. Unocic; Richard E. Glosup; Mike W. Patterson

2012-08-01

183

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

184

Microstructural Characteristics of HIP-bonded Monolithic Nuclear Fuels with a Diffusion Barrier  

SciTech Connect

Due to the limitation of maximum uranium load achievable by dispersion fuel type, the Global Threat Reduction Initiative (GTRI) is developing an advanced monolithic fuel to convert US high performance research reactors to low-enriched uranium. Hot-isostatic-press bonding was the single process down-selected to bond monolithic U-Mo fuel meat to aluminum alloy cladding. A diffusion barrier was applied to the UMo fuel meat by roll-bonding process to prevent extensive interaction between fuel meat and aluminum-alloy cladding. Microstructural characterization was performed on fresh fuel plates fabricated at Idaho National Laboratory. Interfaces between fuel meat, cladding, and diffusion barrier, as well as U10Mo fuel meat and Al6061 cladding were characterized by scanning electron microscopy. Preliminary results indicate that the interfaces contain many different phases while decomposition, second phases, and chemical banding were also observed in the fuel meat. The important attributes of the HIP-bonded monolithic fuel are A typical Zr diffusion barrier of thickness 25 m Transverse cross section that exhibits relatively equiaxed grains with an average grain diameter of 10 m Chemical banding, in some areas more than 100 m in length, that is very pronounced in longitudinal (i.e., rolling) direction with Mo concentration varying from 713 wt% Decomposed areas containing plate-shaped low-Mo phase A typical Zr/cladding interaction layer of thickness 1-2 m A visible UZr2 bearing layer of thickness 1-2 m Mo-rich precipitates (mainly Mo2Zr, forming a layer in some areas) followed by a Mo-depleted sub-layer between the visible UZr2-bearing layer and the UMo matrix No excessive interaction between cladding and the uncoated fuel edge Cladding-to-cladding bonding that exhibits no cracks or porosity with second phases high in Mg, Si, and O decorating the bond line. Some of these attributes might be critical to the irradiation performance of monolithic U-10Mo nuclear fuel. There are several issues or concerns that warrant more detailed study, such as precipitation along cladding-to-cladding bond line, chemical banding, uncovered fuel-zone edge, and interaction layer between UMo fuel meat and zirconium. Future post-irradiation examination results will focus, among other things, on identifying in-reactor failure mechanisms and, eventually, directing further fresh fuel characterization efforts.

Jan-Fong Jue; Dennis D. Keiser, Jr.; Cynthia R. Breckenridge; Glenn A. Moore; Mitchell K. Meyer

2014-05-01

185

Microstructural characteristics of HIP-bonded monolithic nuclear fuels with a diffusion barrier  

NASA Astrophysics Data System (ADS)

Due to the limitation of maximum uranium load achievable by dispersion fuel type, the Global Threat Reduction Initiative is developing an advanced monolithic fuel to convert US high-performance research reactors to low-enriched uranium. Hot-isostatic-press (HIP) bonding was the single process down-selected to bond monolithic U-Mo fuel meat to aluminum alloy cladding. A diffusion barrier was applied to the U-Mo fuel meat by roll-bonding process to prevent extensive interaction between fuel meat and aluminum-alloy cladding. Microstructural characterization was performed on fresh fuel plates fabricated at Idaho National Laboratory. Interfaces between the fuel meat, the cladding, and the diffusion barrier, as well as between the U-10Mo fuel meat and the Al-6061 cladding, were characterized by scanning electron microscopy. Preliminary results indicate that the interfaces contain many different phases while decomposition, second phases, and chemical banding were also observed in the fuel meat. The important attributes of the HIP-bonded monolithic fuel are: diffusion barrier with a thickness of 25 ?m. A transverse cross section that exhibits relatively equiaxed grains with an average grain diameter of 10 ?m. Chemical banding, in some areas more than 100 ?m in length, that is very pronounced in longitudinal (i.e., rolling) direction with Mo concentration varying from 7-13 wt.%. Decomposed areas containing plate-shaped low-Mo phase. A typical Zr/cladding interaction layer with a thickness of 1-2 ?m. A visible UZr2 bearing layer with a thickness of 1-2 ?m. Mo-rich precipitates (mainly Mo2Zr, forming a layer in some areas) followed by a Mo-depleted sub-layer between the visible UZr2-bearing layer and the U-Mo matrix. No excessive interaction between cladding and the uncoated fuel edge. Cladding-to-cladding bonding that exhibits no cracks or porosity with second phases high in Mg, Si, and O decorating the bond line. Some of these attributes might be critical to the irradiation performance of monolithic U-10Mo nuclear fuel. There are several issues or concerns that warrant more detailed study, such as precipitation along the cladding-to-cladding bond line, chemical banding, uncovered fuel-zone edge, and the interaction layer between the U-Mo fuel meat and zirconium. Future post-irradiation examination results will focus, among other things, on identifying in-reactor failure mechanisms and, eventually, directing further fresh fuel characterization efforts.

Jue, Jan-Fong; Keiser, Dennis D.; Breckenridge, Cynthia R.; Moore, Glenn A.; Meyer, Mitchell K.

2014-05-01

186

Verification of the effect of surface preparation on Hot Isostatic Pressing diffusion bonding joints of CLAM steel  

NASA Astrophysics Data System (ADS)

Hot Isostatic Pressing (HIP) diffusion bonding with CLAM steel is the primary candidate fabrication technique for the first wall (FW) of DFLL-TBM. Surface state is one of the key factors for the joints quality. The effect of surface state prepared with grinder and miller on HIP diffusion bonding joints of CLAM steel was investigated. HIP diffusion bonding was performed at 140 MPa and 1373 K within 3 h. The mechanical properties of the joints were investigated with instrumented Charpy V-notch impact tests and the microstructures of the joints were analyzed with scanning electron microscopy (SEM). The results showed that the milled samples with fine surface roughness were more suitable for CLAM steel HIP diffusion bonding.

Zhao, Yanyun; Li, Chunjing; Huang, Bo; Liu, Shaojun; Huang, Qunying

2014-12-01

187

XRD and TEM analysis on the Fe 3Al\\/18-8 stainless steel diffusion bonded interface  

Microsoft Academic Search

Fe3Al intermetallic and 18-8 stainless steel were diffusion-bonded at 1040 C for 60 min. The reacted phase in the Fe3Al\\/18-8 diffusion-bonded interface was determined via X-ray diffractometry (XRD) and the lattice orientation relation between constituent phases was analyzed by transmission electron microscope (TEM). The results indicated that there were Fe3Al, Ni3 Al, FeAl, ?-Fe (Al) solid solution and Fe3C in

Juan Wang; Yajiang Li; Peng Liu

2003-01-01

188

Bonding  

NSDL National Science Digital Library

Bonding Purpose: To review the 3 Types of Bonds and the 4 Intermolecular Forces. Assignment: Answer the following questions on a separate piece of paper: 1) List the 3 types of bonding, give descriptions and one example of each 2) List the 4 intermolecular forces and draw examples of each. Be ...

Cutting, Mrs.

2008-03-08

189

Diffusion bonding of TI6AL4V to AISI 316L stainless steel: mechanical resistance and interface microstructure  

Microsoft Academic Search

The interface microstructure and mechanical strength of joints obtained by diffusion bonding of alloy Ti-6A1-4V to AISI 316L stainless steel are presented. Bonding took place at 850, 900 and 950C, maintained for different lengths of time (60 to 180 min). The highest recorded shear strength was equal to 382 MPa and was displayed by the specimen bonded at 950C\\/180 min.

M. Ferrante; E. V. Pigoretti

2002-01-01

190

Optimizing Diffusion Bonding Parameters in AA6061-T6 Aluminum and AZ80 Magnesium Alloy Dissimilar Joints  

NASA Astrophysics Data System (ADS)

The main difficulty when joining magnesium (Mg) and aluminum (Al) alloys by fusion welding lies in the formation of oxide films and brittle intermetallic in the bond region which affects the integrity of the joints. However, diffusion bonding is a suitable process to join these two materials as no such characteristic defects are produced at the joints. The diffusion bonding process parameters such as bonding temperature, bonding pressure, holding time, and surface roughness of the specimen play a major role in determining the joint strength. In this investigation, an attempt was made to develop empirical relationships to predict the strengths of diffusion bonded AZ80 magnesium and AA6061 aluminum alloys dissimilar joints from the process parameters based on central composite factorial design. Response surface methodology was applied to optimize the process parameters to attain the maximum shear strength and bonding strength of the joint. From this investigation, it was found that the bonds produced with the temperature of 405.87 C, pressure of 7.87 MPa, holding time of 29.02 min and surface roughness of 0.10 ?m exhibited maximum shear strength and bonding strength of 57.70 and 76.90 MPa, respectively. The intermetallic formation at the interface was identified.

Joseph Fernandus, M.; Senthilkumar, T.; Balasubramanian, V.; Rajakumar, S.

2012-11-01

191

On the differentiation of diffusion bond strength using the total acoustic energy reflected from the bond. [Ti-6Al-4V  

SciTech Connect

Single frequency reflection coefficients and reflected energy over a broad acoustic band (2-15 MHz), and the mechanical bond strength were evaluated on diffusion bonds in Cu/Cu, Cu/Ni, and Ti-6Al-4V/self. Results indicate that energy data are more sensitive to small bond strength changes as predicted by Parseval's theorem. In all cases, the energy reflected mainly originates at voids still present at the original interface location. Other microstructural features caused by the interdiffusion appear to diminish the reflected energy. 7 refs., 4 figs.

Ojard, G.C. (Pratt and Whitney, West Palm Beach, FL (United States)); Buck, O.; Rehbein, D.K.; Hughes, M.S. (Iowa State Univ. of Science and Technology, Ames, IA (United States). Center for NDE)

1992-01-01

192

Studies of the pressure induced transition from diffuse to constricted arcing in large vacuum arc furnaces  

SciTech Connect

Vacuum arc remelting (VAR) is a secondary melting process used to produce superalloys. A dc arc is utilized to melt the alloy at normal pressures of {approximately}1 Pa. However, in some instances the pressure in the region of the arc can reach abnormally high values due to CO evolution from the molten ingot, giving rise to a furnace condition known as glow.'' This phenomenon was investigated by studying metal vapor arcs burning on 152 mm diameter Alloy 718 electrodes at 2.3 kA in a modified VAR furnace in CO ambients of 1.3, 13.3, and 66.7 Pa. Electrical signatures and high speed photographic data were recorded at all pressures. At the lowest pressure, the arc was diffuse with cathode spots distributed randomly across the molten electrode surface. Under these conditions, the inter-electrode space appeared to be uniformly filled with plasma. Monochromatic images taken at this pressure show mobile ion channels connecting regions of cathode spot activity with the molten ingot pool. Because spot motion is fast compared to the thermal diffusion speed in the ingot, this arc constitutes a quasi-uniform heat source necessary for successful application of the process. At a CO pressure of 66.7 Pa, the arc was localized and normal cathode spot action had ceased, although normal appearing constricted plasma attachments were observed to spontaneously appear at the bottom of molten metal protuberances as they dripped from the electrode and drew within a few millimeters of the ingot surface. At this pressure, the arc was observed to operate in either of the two modes, one characterized by high'' voltage ({minus}24 V), and the other by low voltage ({minus}19 V). At 13.3 Pa CO the arc was not stable, although heating of the electrode remained quasi-uniform. 14 refs., 12 figs.

Williamson, R.; Zanner, F.; Hareland, W.

1990-01-01

193

Elastic constants for superplastically formed/diffusion-bonded corrugated sandwich core  

NASA Technical Reports Server (NTRS)

Formulas and associated graphs for evaluating the effective elastic constants for a superplastically formed/diffusion bonded (SPF/DB) corrugated sandwich core, are presented. A comparison of structural stiffnesses of the sandwich core and a honeycomb core under conditions of equal sandwich core density was made. The stiffness in the thickness direction of the optimum SPF/DB corrugated core (that is, triangular truss core) is lower than that of the honeycomb core, and that the former has higher transverse shear stiffness than the latter.

Ko, W. L.

1980-01-01

194

Structural properties of superplastically formed/diffusion-bonded orthogonally corrugated core sandwich plates  

NASA Technical Reports Server (NTRS)

This paper describes a new superplastically formed/diffusion-bonded (SPF/DB) orthogonally corrugated sandwich structure, and presents formulae and the associated plots for evaluating the effective elastic constants for the core of this new sandwich structure. Comparison of structural properties of this new sandwich structure with the conventional honeycomb core sandwich structure was made under the condition of equal sandwich density. It was found that the SPF/DB orthogonally corrugated sandwich core has higher transverse shear stiffness than the conventional honeycomb sandwich core. However, the former has lower stiffness in the sandwich core thickness direction than the latter.

Ko, W. L.

1980-01-01

195

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

2013-12-01

196

Vacuum ultraviolet-induced surface modification of cyclo-olefin polymer substrates for photochemical activation bonding  

NASA Astrophysics Data System (ADS)

The surface of cyclo-olefin polymer (COP) was treated with vacuum ultraviolet (VUV) light at 172 nm wavelength to improve the wettability and adhesion properties. Through VUV treatment in air, the terminal groups of the COP surface were oxidized into oxygen functional groups, containing C sbnd O, C dbnd O, and COO components, making the COP surface hydrophilic. The extent of oxygenation was evaluated by XPS and FTIR-ATR spectra, and it was shown that the surface properties, hydrophilicity, and functionalization were dependent on both VUV irradiation distance and irradiation time, which have an effect on the concentration of oxygen functional groups. VUV-light treatment with a short irradiation distance was more effective in introducing oxygen functional groups.

Kim, Young-Jong; Taniguchi, Yoshinao; Murase, Kuniaki; Taguchi, Yoshihiro; Sugimura, Hiroyuki

2009-01-01

197

Microstructure and mechanical strength of diffusion bonded joints between silicon carbide and F82H steel  

NASA Astrophysics Data System (ADS)

The combination of SiC and reduced activation ferritic/martensitic steels is attractive for fusion applications because it is expected to offer high thermal efficiency, high reliability and superior safety characteristic under a neutron irradiation environment. In this paper, diffusion bonding of SiC to F82H steel has been investigated. Direct joining of SiC to F82H was unsuccessful due to a large residual stress generated in the joint. A double W/Cu and a multiple W/Ni/Cu/Ni interlayer were used to reduce the residual stress, and encouraging results were obtained. The interfacial microstructure examination revealed that the various interfaces were bonded well. Diffusion products in the reaction zones were identified. The shear strength of the SiC/F82H joints measured by knife-edge tests at room temperature was found to increase with the increase in the joining temperature, and reached a maximum of 41.3 MPa. The fracture surfaces of the joints were also analyzed.

Zhong, Zhihong; Hinoki, Tatsuya; Kohyama, Akira

2011-10-01

198

Interface microstructures in the diffusion bonding of a titanium alloy Ti 6242 to an Inconel 625  

SciTech Connect

Surveys carried out by some oil companies have shown a recent and clear trend toward drilling wells to greater depths. As the drilling for oil and gas gets deeper, the requirements of materials for tubing become more stringent, due to the rise in temperature and pressure and also because the tubes have to sustain their own weight. In this paper, Ti6242 alloy has been diffusion bonded to a superalloy INCONEL 625. The microstructures of the as-processed products have been analyzed using optical metallography, scanning electron microscope (SEM), and scanning transmission electron microscope (STEM) techniques. The interdiffusion of the different elements through the interface has been determined using energy-dispersive spectroscopy (EDS) microanalysis in both a SEM and a STEM. Several regions around the original interface have been observed. Starting from the superalloy INCONEL 625, first a sigma phase (Cr[sub 4]Ni[sub 3]Mo[sub 2]), followed by several phases like NbNi[sub 3], [eta]Ni[sub 3]Ti, Cr(20 pct Mo), [beta] Cr[sub 2]Ti, NiTi, TiO, TiNi, and Ti[sub 2]Ni intermetallics, just before the Ti6242 have been identified. Because the diffusion of Ni in Ti is faster than the diffusion of Ti in the superalloy, a Kirkendall effect was produced. The sequence of formation of the different phases were in agreement with the ternary Ti-Cr-Ni diagram.

Aleman, B.; Gutierrez, I.; Urcola, J.J. (Centro de Estudios e Investigaciones Tecnicos de Guipuzcoa, San Sebastian (Spain). Dept. of Materials)

1995-02-01

199

A Comparison Between Cold-Welded and Diffusion-Bonded Al/Cu Bimetallic Rods Produced by ECAE Process  

NASA Astrophysics Data System (ADS)

In this research, the application of equal channel angular extrusion process to produce both the cold-welded and diffusion-bonded Al/Cu bimetallic rods is assessed. The joints shear strength for both of the methods are measured and compared. The microstructure examinations were also carried out using scanning electron microscope equipped with EDX system and x-ray diffraction analysis. The results exhibit that the strength of the bond in cold-welded specimens is dependent on the amount of stretch and pressure at the materials interface. But in the diffusion-bonded specimens, it is depended on the struggle between the oxidation rate of the mating surfaces accompanied by inter-metallic compounds formation and the aluminum and copper atoms ability to diffuse in the joint interface.

Eslami, P.; Karimi Taheri, A.; Zebardast, M.

2013-10-01

200

Investigations of diffusion-bonded stacked GaAs for infrared quasi-phase-matched parametric oscillation  

NASA Astrophysics Data System (ADS)

We are developing the diffusion-bonded stacked (DBS) structure for quasi-phasematched interactions to meet the need for high- power nonlinear conversions in the infrared. In our preliminary investigations, we have compared optical and thermal properties of some potential DBS materials. Theoretical projections of device performance were compared for DBS GaAs and ZnSe and birefringent crystals ZnGeP2 and AgGaSe2 for both second- harmonic generation (SHG) of 10-micrometers radiation and 2-micrometers pumped optical parametric oscillators (OPOs). We are refining bonding processes for GaAs and have initial diffusion bonding results for ZnSe. We have fabricated and tested DBS GaAs structures for SHG, demonstrating that the crystal orientation is conserved during the bonding process, and that the nonlinear generation of the individual layers sums coherently. These studies indicate that DBS materials have potential for application in high-average-power OPOs.

Gordon, Leslie A.; Eckardt, Robert C.; Byer, Robert L.

1994-06-01

201

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

202

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

203

Application of superplastically formed and diffusion bonded aluminum to a laminar flow control leading edge  

NASA Technical Reports Server (NTRS)

NASA sponsored the Aircraft Energy Efficiency (ACEE) program in 1976 to develop technologies to improve fuel efficiency. Laminar flow control was one such technology. Two approaches for achieving laminar flow were designed and manufactured under NASA sponsored programs: the perforated skin concept used at McDonnell Douglas and the slotted design used at Lockheed-Georgia. Both achieved laminar flow, with the slotted design to a lesser degree (JetStar flight test program). The latter design had several fabrication problems concerning springback and adhesive flow clogging the air flow passages. The Lockheed-Georgia Company accomplishments is documented in designing and fabricating a small section of a leading edge article addressing a simpler fabrication method to overcome the previous program's manufacturing problems, i.e., design and fabrication using advanced technologies such as diffusion bonding of aluminum, which has not been used on aerospace structures to date, and the superplastic forming of aluminum.

Goodyear, M. D.

1987-01-01

204

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

205

Characterization of the interface to diffusion bonding of zircaloy-4 and stainless steel  

NASA Astrophysics Data System (ADS)

The assembly of various materials by the conventional methods finds its limits in certain specific applications. We approach a study on the solid state diffusion bonding between zircaloy (Zy4) and stainless steel (304L) for an application in the sector of the nuclear power. The diffusion couples prepared underwent treatments at the temperatures ranging between 850 ?C and 1020 ?C in a controlled atmosphere and under dynamic pressures of contact. We give a particular attention to the morphology of the interface, formed, with the chemical reactions of exchange which proceed between two entities Zy4/304L like with the determination of the nature of the compounds formed with the interface. The observations and chemical analysis are realized by optics microscopy's and electronics (ESEM-EDX) and with X ray diffraction (XRD). The quantitative distributions as well as the detailed localization of the basic chemical elements are defined by chemical profiles, characteristics of each element. The junction with the interface of diffusion consists of three zones distinct, formed from a solid solution ?FeCr, rich in Cr in the form of a homogeneous edge, localized in steel side. The zone of the center and that of side Zy4 are two-phase. They are made up, for one, of ?FeCr- Zr(Fe, Cr)2 and for the other, Zy4 side, the solid solution ?Zr and the intermetallic compound Zr2 (Fe1-xNix) where X is understood enters 0,15 and 0,25. The detailed results obtained, are a stepping, between those obtained from the observations and chemical analyses and radio crystallographic. The values of the measured microhardnesses give a very heterogeneous filiations to the level of the interface of the two entities.

Taouinet, M.; Lebaili, S.; Souami, N.

2009-11-01

206

The environment assisted cracking of diffusion bonded stainless to carbon steel joints in an aqueous chloride solution  

Microsoft Academic Search

Procedures for making sound direct and indirect diffusion bonds between austenitic stainless and carbon steels are described. The details of the microstructure near the interface have been studied. Data are presented for the strengths achievable in inert environments. The resistance to stress corrosion cracking of the joints in a hot aqueous chloride environment has been assessed as a function of

S. M. Shushan; E. A. Charles; J. Congleton

1996-01-01

207

Low cycle fatigue strength of diffusion bonded joints of alumina dispersion-strengthened copper to stainless steel  

NASA Astrophysics Data System (ADS)

It is proposed that the first wall and divertor components of ITER employ alumina dispersion-strengthened copper (DS Cu) joined to austenitic stainless steel. In this work, low cycle fatigue tests were performed on a direct diffusion bonded joint, a diffusion bonded joint with a Au interlayer, stainless steel and DS Cu in order to investigate their fatigue strength and fracture behavior. For the direct diffusion bonded joint, the fatigue strength in the small strain range was considerably lower than that of the DS Cu, while in the large strain range the fatigue strength was similar to that of the DS Cu. The low cycle fatigue strength of the Au interlayer joint increased compared with the direct diffusion bonded joint, and was the same as that of the DS Cu. The strain distribution in joint specimens was not uniform, because the deformation stress was different between the 316 stainless steel and the DS Cu. The fracture locations for the joint specimens varied depending on their strain distribution.

Nishi, H.; Araki, T.

2000-12-01

208

Method for producing components with internal architectures, such as micro-channel reactors, via diffusion bonding sheets  

DOEpatents

This invention relates to a method for producing components with internal architectures, and more particularly, this invention relates to a method for producing structures with microchannels via the use of diffusion bonding of stacked laminates. Specifically, the method involves weakly bonding a stack of laminates forming internal voids and channels with a first generally low uniaxial pressure and first temperature such that bonding at least between the asperites of opposing laminates occurs and pores are isolated in interfacial contact areas, followed by a second generally higher isostatic pressure and second temperature for final bonding. The method thereby allows fabrication of micro-channel devices such as heat exchangers, recuperators, heat-pumps, chemical separators, chemical reactors, fuel processing units, and combustors without limitation on the fin aspect ratio.

Alman, David E. (Corvallis, OR); Wilson, Rick D. (Corvallis, OR); Davis, Daniel L. (Albany, OR)

2011-03-08

209

Studies of the pressure induced transition from diffuse to constricted arcing in large vacuum arc furnaces  

Microsoft Academic Search

Vacuum arc remelting (VAR) is a secondary melting process used to produce superalloys. A dc arc is utilized to melt the alloy at normal pressures of 1 Pa. However, in some instances the pressure in the region of the arc can reach abnormally high values due to CO evolution from the molten ingot, giving rise to a furnace condition known

R. Williamson; F. Zanner; W. Hareland

1990-01-01

210

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

NASA Astrophysics Data System (ADS)

Many from within manufacturing industry consider superplastic forming (SPF) to be high tech, but it is often criticized as too complicated, expensive, slow and, in general, an unstable process when compared to other methods of manipulating sheet materials. Perhaps, the fundamental cause of this negative perception of SPF, and also of diffusion bonding (DB), is the fact that the current process of SPF/DB relies on indirect sources of heating to produce the conditions necessary for the material to be formed. Thus, heat is usually derived from the electrically heated platens of hydraulic presses, to a lesser extent from within furnaces and, sometimes, from heaters imbedded in ceramic moulds. Recent evaluations of these isothermal methods suggest they are slow, thermally inefficient and inappropriate for the process. In contrast, direct heating of only the material to be formed by modern, electrically efficient, lasers could transform SPF/DB into the first choice of designers in aerospace, automotive, marine, medical, architecture and leisure industries. Furthermore, variable temperature direct heating which, in theory, is possible with a laser beam(s) may provide a means to control material thickness distribution, a goal of enormous importance as fuel efficient, lightweight structures for transportation systems are universally sought. This paper compares, and contrasts, the two systems and suggests how a change to laser heating might be achieved.

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

2010-06-01

211

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

NASA Technical Reports Server (NTRS)

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 electron microscopic techniques as well as Charpy V-notch impact tests at temperatures of 77 and 300 K. Results are discussed in terms of a postulated model for the bonding process.

Wigley, D. A.

1981-01-01

212

Diffusion Bonding Behavior and Characterization of Joints Made Between 316L Stainless Steel Alloy and AZ31 Magnesium Alloy  

NASA Astrophysics Data System (ADS)

The 316L austenitic stainless steel and AZ31 magnesium alloy have physical and mechanical properties which makes these alloys suitable in a number of high technology based industries such as the aerospace and automotive sectors. However, for these alloys to be used in engineering applications, components must be fabricated and joined successfully. The differences in the physical and metallurgical properties between these two alloys prevents the use of conventional fusion welding processes commonly employed in aerospace and transport industry. Therefore, alternative techniques need to be developed and diffusion bonding technology is a process that has considerable potential to join these two dissimilar alloys. In this research work both solid-state and transient liquid phase (TLP) bonding processes were applied. The solid-state bonding of 316L steel to AZ31 magnesium alloy was possible at a bonding temperature of 550C for 120 minutes using a pressure of 1.3 MPa. The interface characterization of the joint showed a thin intermetallic zone rich in Fe-Al was responsible for providing a metallurgical bond. However, low joint shear strengths were recorded and this was attributed to the poor surface to surface contact. The macro-deformation of the AZ31 alloy prevented the use of higher bonding pressures and longer bonding times. In order to overcome these problems, the TLP bonding process was implemented using pure Cu and Ni foils as interlayers which produced a eutectic phase at the bonding temperature. This research identified the bonding mechanism through microstructural and differential scanning calorimetry investigations. The microstructural characterization of the TLP joints identified intermetallics which became concentrated along the 316L steel/AZ31 bond interface due to the "pushing effect" of the solid/liquid interface during isothermal solidification stage of bonding. The size and concentration of the intermetallics had a noticeable effect on the final joint strength properties. TLP bonding using electrodeposited coatings of Cu and Ni were used as a way of controlling the volume of eutectic liquid formed at the joint. Theoretical and experimental work showed that the use of thin coatings was successful in reducing the size and amount of intermetallics formed at the joint and this had the effect on increasing joint shear strength values.

Elthalabawy, Waled Mohamed

213

Structural dynamics of hydrogen bonded methanol oligomers: Vibrational transient hole burning studies of spectral diffusion  

E-print Network

Structural dynamics of hydrogen bonded methanol oligomers: Vibrational transient hole burning donate and receive hydrogen bonds have an inhomogeneously broadened hydroxyl stretch absorption line the dynamics are attributed to fluctuations in the local hydrogen bond network, which is consistent with recent

Fayer, Michael D.

214

Development of a Low-Cost Process for Manufacturing of Ti-Metal Matrix Composite by Roll-Diffusion Bonding  

NASA Astrophysics Data System (ADS)

Composite materials with titanium-alloy matrix are currently the class of material with the highest specific resistance at temperatures up to 800 C. The main hurdle to their application is their final cost. Even if it is clear that the costs of constituent materials are decreasing due to volume production effects, the production processing costs remain high due to the batch production approach. Centro Sviluppo Materialis (CSM) efforts have focused on the manufacturing process in order to obtain an innovative solution to reduce the manufacturing costs with respect to the hot isostatic pressing (HIP) process that represents the standard production process for this class of materials. The new approach can allow a cost reduction of about 40%; this result was obtained by developing an experimental diffusion bonding plant for co-rolling at high temperature in a superplastic rolling regime, sheets of titanium alloy and monofilament silicon carbide fabrics. The experimental pilot plant was proposed for patent with RM2006A000261 in May 2006. This paper describes the manufacturing phases and process results. Moreover, has been shown that the diffusion in the solid state was obtained in a process window that was at least 100 times faster than that of HIP. High-temperature tensile tests were carried out on specimens machined from metallic matrix composite materials produced with the roll-diffusion bonding (RDB) process. The samples produced were also submitted to electrochemical dissolution tests of the metallic matrix in order to verify the geometric integrity of the fibers inside the matrix after the bonding phase. The results achieved as well as the process knowledge acquired with the CSM pilot plant are the base for further development of industrial application of the titanium roll-diffusion bonding.

Testani, C.; Ferraro, F.

2010-06-01

215

Superplastic forming and diffusion bonding of rapidly solidified, dispersion strengthened aluminum alloys for elevated temperature structural applications  

NASA Technical Reports Server (NTRS)

Rapidly solidified alloys, based upon the Al-Fe-V-Si system and designed for elevated temperature applications, were evaluated for superplasticity and diffusion bonding behavior. Alloys with 8, 16, 27, and 36 volume percent silicide dispersoids were produced; dispersoid condition was varied by rolling at 300, 400, and 500 C (572, 752, and 932 F). Superplastic behavior was evaluated at strain rates from 1 x 10(exp -6)/s to 8.5/s at elevated temperatures. The results indicate that there was a significant increase in elongation at higher strain rates and at temperatures above 600 C (1112 F). However, the exposure of the alloys to temperatures greater than 600 C (1112 F) resulted in the coarsening of the strengthening dispersoid and the degradation of mechanical properties. Diffusion bonding was possible using low gas pressure at temperatures greater than 600 C (1112 F) which also resulted in degraded properties. The bonding of Al-Fe-V-Si alloys to 7475 aluminum alloy was performed at 516 C (960 F) without significant degradation in microstructure. Bond strengths equal to 90 percent that of the base metal shear strength were achieved. The mechanical properties and microstructural characteristics of the alloys were investigated.

Ting, E. Y.; Kennedy, J. R.

1989-01-01

216

Photodissociation of CS2 in the vacuum ultraviolet - Determination of bond dissociation energy from the lowest vibrational level of the ground state CS2.  

NASA Technical Reports Server (NTRS)

Photolysis in the vacuum ultraviolet results almost exclusively in the production of S(super-3)P atoms, which is in apparent violation of spin conservation. The threshold energy of incident photons required to produce fluorescence was used to calculate the bond dissociation energy (from the lowest vibrational level of the ground state), and the result agrees with the value previously derived from the photoionization of CS2. The fluorescence excitation spectrum shows peaks corresponding to Rydberg series I and II, indicating that the observed photodissociation of CS2 in the vacuum ultraviolet is mainly the result of predissociation from Rydberg states. The absorption coefficient of CS2 was measured in the region of 1200 to 1400 A.

Okabe, H.

1972-01-01

217

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

2011-11-01

218

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

2014-02-01

219

The effect of intermetallics on the strength properties of diffusion bonds formed between Ti5.5Al2.4V and 304 stainless steel  

Microsoft Academic Search

Solid-state diffusion bonding was done to produce transition joints between Ti5.5Al2.4V and type 304 austenitic stainless steel in the temperature range of 850950C under uniaxial load for 1h. The diffusion-bonded couples thus produced were evaluated by optical microscopy, scanning electron microscopy, X-ray diffraction and tensile testing. Scanning electron microscopy in back scattered mode reveals the presence of different reaction bands

M Ghosh; S Chatterjee; B Mishra

2003-01-01

220

An investigation on diffusion bonding of aluminum to copper using equal channel angular extrusion process  

PubMed Central

A new method for production of bimetallic rods, utilizing the equal channel angular extrusion (ECAE) process has been introduced before by previous researchers, but no attempt has been made to assess the effect of different temperatures and holding times in order to achieve a diffusional bond between the mating surfaces. In present research copper sheathed aluminum rods have been ECAEed at room temperature and subsequently held at a constant ECAE pressure, at different temperatures and holding times to produce a diffusional bond between the copper sheath and the aluminum core. The bonding quality of the joints was examined by shear strength test and a sound bonding interface was achieved. Based on the results, a bonding temperature of 200C and holding time of 6080min yielded the highest shear strength value. PMID:21760654

Eslami, P.; Taheri, A. Karimi

2011-01-01

221

An investigation on diffusion bonding of aluminum to copper using equal channel angular extrusion process.  

PubMed

A new method for production of bimetallic rods, utilizing the equal channel angular extrusion (ECAE) process has been introduced before by previous researchers, but no attempt has been made to assess the effect of different temperatures and holding times in order to achieve a diffusional bond between the mating surfaces. In present research copper sheathed aluminum rods have been ECAEed at room temperature and subsequently held at a constant ECAE pressure, at different temperatures and holding times to produce a diffusional bond between the copper sheath and the aluminum core. The bonding quality of the joints was examined by shear strength test and a sound bonding interface was achieved. Based on the results, a bonding temperature of 200C and holding time of 60-80min yielded the highest shear strength value. PMID:21760654

Eslami, P; Taheri, A Karimi

2011-06-30

222

Microstructural evolution in the partial transient liquid phase diffusion bonding of Zircaloy4 to stainless steel 321 using active titanium filler metal  

Microsoft Academic Search

Microstructural evolution of the partial transient liquid phase diffusion bonded Zircaloy-4 and stainless steel 321 using an active Ti-base interlayer were studied at different temperatures. Additionally, simple analytical models were developed to predict the evolution of the interlayer and intermetallics during the bonding operation. Bonds were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. Precision measurement of the

M. Mazar Atabaki

2010-01-01

223

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

224

Effect of High Temperature Storage in Vacuum, Air, and Humid Conditions on Degradation of Gold/Aluminum Wire Bonds in PEMs  

NASA Technical Reports Server (NTRS)

Microcircuits encapsulated in three plastic package styles were stored in different environments at temperatures varying from 130 C to 225 C for up to 4,000 hours in some cases. To assess the effect of oxygen, the parts were aged at high temperatures in air and in vacuum chambers. The effect of humidity was evaluated during long-term highly accelerated temperature and humidity stress testing (HAST) at temperatures of 130 C and 150 C. High temperature storage testing of decapsulated microcircuits in air, vacuum, and HAST chambers was carried out to evaluate the role of molding compounds in the environmentally-induced degradation and failure of wire bonds (WB). This paper reports on accelerating factors of environment and molding compound on WB failures. It has been shown that all environments, including oxygen, moisture, and the presence of molding compounds reduce time-to-failures compared to unencapsulated devices in vacuum conditions. The mechanism of the environmental effect on KB degradation is discussed.

Teverovsky, Alexander

2006-01-01

225

Transient Liquid Phase Diffusion Bonding of Magnesium Alloy (Mg-AZ31) to Titanium Alloy (Ti-6Al-4V)  

NASA Astrophysics Data System (ADS)

The magnesium alloy Mg-AZ31 and titanium alloy Ti-6Al-4V have physical characteristics and mechanical properties that makes it attractive for a wide range of engineering applications in the aerospace and automotive industries. However, the differences in melting temperature and coefficient of thermal expansion hinder the use of traditional fusion welding techniques. Transient liquid phase (TLP) bonding of magnesium alloy Mg-AZ31 and titanium alloy Ti-6Al- 4V was performed and different interlayer types and configurations were used to facilitate joint formation. The joining of these alloys using Ni foils was successful at a bonding temperature of 515C, bonding pressure 0.2 MPa, for bonding time of 5 minutes. At the Ni/Mg-AZ31 bond interface, the formation of a eutectic liquid between Mg and Ni was observed. The formation of Mg2Ni and Mg3AlNi2 were identified along the bond interface resulting in an isothermally solidified joint. At the Ni/Ti-6Al-4V interface, the solid-state diffusion process results in joint formation. The use of double Ni-Cu sandwich joint resulted in further enhancement in joint formation and this produced joints with greater shear strength values. The configuration of Mg-AZ31/Cu- Ni/Ti-6Al-4V or Mg-AZ31/Ni-Cu/Ti-6Al-4V influence the mechanism of bonding and the type of intermetallics formed within the joint. The application of thin Ni electrodeposited coatings resulted in further enhancements of joint quality due to better surface-to-surface contact and a reduction in the formation of intermetallics at the joint. The effect of Cu nano-particles in the coatings was found to decrease the eutectic zone width and this resulted in an increase the shear strength of the joints. The highest shear strength of 69 MPa was possible with bonds made using coatings containing Cu nano-particle dispersion.

Atieh, Anas Mahmoud

226

The effect of hydrogen bonding on the diffusion of water in n-alkanes and n-alcohols measured with a novel single microdroplet method  

PubMed Central

While the StokesEinstein (SE) equation predicts that the diffusion coefficient of a solute will be inversely proportional to the viscosity of the solvent, this relation is commonly known to fail for solutes, which are the same size or smaller than the solvent. Multiple researchers have reported that for small solutes, the diffusion coefficient is inversely proportional to the viscosity to a fractional power, and that solutes actually diffuse faster than SE predicts. For other solvent systems, attractive solute-solvent interactions, such as hydrogen bonding, are known to retard the diffusion of a solute. Some researchers have interpreted the slower diffusion due to hydrogen bonding as resulting from the effective diffusion of a larger complex of a solute and solvent molecules. We have developed and used a novel micropipette technique, which can form and hold a single microdroplet of water while it dissolves in a diffusion controlled environment into the solvent. This method has been used to examine the diffusion of water in both n-alkanes and n-alcohols. It was found that the polar solute water, diffusing in a solvent with which it cannot hydrogen bond, closely resembles small nonpolar solutes such as xenon and krypton diffusing in n-alkanes, with diffusion coefficients ranging from 12.510?5 cm2?s for water in n-pentane to 1.1510?5 cm2?s for water in hexadecane. Diffusion coefficients were found to be inversely proportional to viscosity to a fractional power, and diffusion coefficients were faster than SE predicts. For water diffusing in a solvent (n-alcohols) with which it can hydrogen bond, diffusion coefficient values ranged from 1.7510?5 cm2?s in n-methanol to 0.36410?5 cm2?s in n-octanol, and diffusion was slower than an alkane of corresponding viscosity. We find no evidence for solute-solvent complex diffusion. Rather, it is possible that the small solute water may be retarded by relatively longer residence times (compared to non-H-bonding solvents) as it moves through the liquid. PMID:20113048

Su, Jonathan T.; Duncan, P. Brent; Momaya, Amit; Jutila, Arimatti; Needham, David

2010-01-01

227

Diffusion welding of SUS304L stainless steel to titanium  

Microsoft Academic Search

The purposes of this study are first to investigate the relationship between the diffusion welding parameters and quality of SUS304L stainless steel\\/titanium diffusion?welded joints, and second to develop a bonding method to obtain sound joints, by vacuum heat treatment for surface control. The equipment used consists of an ultra?high vacuum chamber and surface analysis chamber with Auger device.The strength of

O. O. Hashi; K. El; H. Irie

1996-01-01

228

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

229

Effect of electron energy distribution functions on plasma generated vacuum ultraviolet in a diffusion plasma excited by a microwave surface wave  

SciTech Connect

Plasma generated vacuum ultraviolet (VUV) in diffusion plasma excited by a microwave surface wave has been studied by using dielectric-based VUV sensors. Evolution of plasma VUV in the diffusion plasma as a function of the distance from the power coupling surface is investigated. Experimental results have indicated that the energy and spatial distributions of plasma VUV are mainly controlled by the energy distribution functions of the plasma electrons, i.e., electron energy distribution functions (EEDFs). The study implies that by designing EEDF of plasma, one could be able to tailor plasma VUV in different applications such as in dielectric etching or photo resist smoothing.

Zhao, J. P.; Chen, L.; Funk, M.; Sundararajan, R. [Austin Plasma Laboratory, Tokyo Electron America, Inc., Austin, Texas 78741 (United States); Nozawa, T. [Tokyo Electron Limited, TEL Technology Center Sendai, 2-1 Osawa 3-chome, Izumi-ku, Sendai 981-3137 (Japan); Samukawa, S. [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2013-07-15

230

M3B2 and M5B3 Formation in Diffusion-Affected Zone During Transient Liquid Phase Bonding Single-Crystal Superalloys  

NASA Astrophysics Data System (ADS)

Precipitates in the diffusion-affected zone (DAZ) during transient liquid phase bonding (TLP) single-crystal superalloys were observed and investigated. Small size and dendritic-shaped precipitates were identified to be M3B2 borides and intergrowth of M3B2/M5B3 borides. The orientation relationships among M3B2, M5B3, and matrix were determined using transmission electron microscope (TEM). Composition characteristics of these borides were also analyzed by TEM energy-dispersive spectrometer. Because this precipitating phenomenon deviates from the traditional parabolic transient liquid phase bonding model which assumed a precipitates free DAZ during TLP bonding, some correlations between the deviation of the isothermal solidification kinetics and these newly observed precipitating behaviors were discussed and rationalized when bonding the interlayer containing the high diffusivity melting point depressant elements and substrates of low solubility.

Sheng, Naicheng; Hu, Xiaobing; Liu, Jide; Jin, Tao; Sun, Xiaofeng; Hu, Zhuangqi

2015-01-01

231

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] [Univ. Complutense, Madrid (Spain). Dept. de Ciencia de los Materiales e Ingenieria Metalurgica

1996-12-01

232

Ceramic-to-metal vacuum seal  

NASA Technical Reports Server (NTRS)

Knife-edge sealing technique forms reliable, vacuum-tight bonds between materials having very different thermal-expansion characteristics. Seal is thin and flexible and absorb shear, hoop, and bonding stresses at joint so that seal remains vacuum tight.

Sackerlotzky, O. H.

1979-01-01

233

Evaluation of superplastic forming and co-diffusion bonding of Ti-6Al-4V titanium alloy expanded sandwich structures  

NASA Technical Reports Server (NTRS)

The application of the superplastic forming/diffusion bonding (SPF/DB) process to supersonic cruise research is investigated. The capability of an SPF/DB titanium structure to meet the structural requirements of the inner wing area of the NASA arrow-wing advanced supersonic transport design is evaluated. Selection of structural concepts and their optimization for minimum weight, SPF/DB process optimization, fabrication of representative specimens, and specimen testing and evaluation are described. The structural area used includes both upper and lower wing panels, where the upper wing panel is used for static compression strength evaluation and the lower panel, in tension, is used for fracture mechanics evaluations. The individual test specimens, cut from six large panels, consist of 39 static specimens, 10 fracture mechanics specimens, and one each full size panel for compression stability and fracture mechanics testing. Tests are performed at temperatures of -54 C (-65 F), room temperature, and 260 C (500 F).

Arvin, G. H.; Israeli, L.; Stolpestad, J. H.; Stacher, G. W.

1981-01-01

234

Fabrication and evaluation of enhanced diffusion bonded titanium honeycomb core sandwich panels with titanium aluminide face sheets  

NASA Technical Reports Server (NTRS)

A joining process was developed for fabricating lightweight, high temperature sandwich panels for aerospace applications using Ti-14Al-21Nb face sheets and Ti-3Al-2.5V honeycomb core. The process, termed Enhanced Diffusion Bonding (EDB), relies on the formation of a eutectic liquid through solid-state diffusion at elevated temperatures and isothermal solidification to produce joints in thin-gage titanium and titanium aluminide structural components. A technique employing a maskant on the honeycomb core was developed which permitted electroplating a controlled amount of EDB material only on the edges of the honeycomb core in order to minimize the structural weight and metallurgical interaction effects. Metallurgical analyses were conducted to determine the interaction effects between the EDB materials and the constituents of the sandwich structure following EDB processing. The initial mechanical evaluation was conducted with butt joint specimens tested at temperatures from 1400 - 1700 F. Further mechanical evaluation was conducted with EDB sandwich specimens using flatwise tension tests at temperatures from 70 - 1100 F and edgewise compression tests at ambient temperature.

Hoffmann, E. K.; Bird, R. K.; Bales, T. T.

1989-01-01

235

Preliminary carburizing of medium-carbon steel as a factor increasing corrosion resistance of diffusion layers produced by means of vacuum chromizing process  

SciTech Connect

Diffusion layers produced on a steel surface by means of the vacuum chromizing process has been studied. The effect of preliminary carburizing of medium-carbon steel on a chromized layer structure and its corrosion resistance has been investigated. Studies of layer thickness, its morphology, the phase composition, and Cr and Fe depth profiles in the diffusion zone of chromized steel specimens in the aggressive media of the food industry has been determined. For corrosion resistance tests chromized layers of different structure have been used: two-phase layers (consisting of a carbide layer and a solution zone) produced on the medium-carbon steel, monophase carbide layers produced on the surface of preliminary carburized medium-carbon steel and monophase solution layers produced on Armco iron. It has been proved that the corrosion resistance of monophase hard carbide layers, as well as of monophase solution layers is higher than that for two-phase layers. The results obtained by the described method indicate that the preliminary carburizing of medium-carbon steel significantly increases corrosion resistance of diffusion layers produced by means of the vacuum chromizing process.

Kasprzycka, E.; Tacikowski, J. [Inst. of Precision Mechanics, Warsaw (Poland); Liliental, W. [Nitrex Metal Inc., Montreal, Quebec (Canada)

1995-12-31

236

Diffusion  

NSDL National Science Digital Library

Diffusion is the net movement of particles from areas of high concentration (number of particles per unit area) to low concentration. In this activity, students use a molecular dynamics model to view the behavior of diffusion in gases and liquids.

2012-07-19

237

Microstructural evolution in the partial transient liquid phase diffusion bonding of Zircaloy-4 to stainless steel 321 using active titanium filler metal  

NASA Astrophysics Data System (ADS)

Microstructural evolution of the partial transient liquid phase diffusion bonded Zircaloy-4 and stainless steel 321 using an active Ti-base interlayer were studied at different temperatures. Additionally, simple analytical models were developed to predict the evolution of the interlayer and intermetallics during the bonding operation. Bonds were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. Precision measurement of the interlayer width was made as a function of the bonding temperature. The liquid film migration occurred as a result of chemical solubility differences between the stable and metastable phases. The formation and growth model of the intermetallic compounds at the interfaces of Zircaloy-4/Ti-base interlayer and stainless steel 321/Ti-base interlayer for controlling the bonding process was studied considering the diffusion kinetics and the thermodynamics. The evolution of the interlayer thickness indicated a good agreement between the calculation and experimental measurement. It was also demonstrated that the low isothermal solidification kinetic was not only due to the enrichment of the liquid phase with the base alloying elements such as Ti and Zr, but also the reduction of solid solubility limit of Cu in the base alloys contributed to the reduction of isothermal solidification kinetic.

Atabaki, M. Mazar

2010-11-01

238

Diffusion Monte Carlo Study of Bond Dissociation Energies for BH2, B(OH)2, BCl2, and BCl  

NASA Astrophysics Data System (ADS)

On basis of bond dissociation energies (BDEs) for BH2, B(OH)2, BCl2, and BCl, the diffusion Monte Carlo (DMC) method is applied to explore the BDEs of HB-H, HOB-OH, ClB-Cl, and B-Cl. The effect of the choice of orbitals, as well as the backflow transformation, is studied. The Slater-Jastrow DMC algorithm gives BDEs of 359.10.12 kJ/mol for HB-H, 410.50.50 kJ/mol for HOB-OH, 357.81.46 kJ/mol for ClB-Cl, and 504.50.96 kJ/mol for B-Cl using B3PW91 orbitals and similar BDEs when B3LYP orbitals are used. DMC with backflow corrections (BF-DMC) gives a HB-H BDE of 369.90.12 kJ/mol which is close to one of the available experimental value (375.8 kJ/mol). In the case of HOB-OH BDE, the BF-DMC calculation is 446.01.84 kJ/mol that is closer to the experimental BDE. The BF-DMC BDE for ClB-Cl is 343.22.34 kJ/mol and the BF-DMC B-Cl BDE is 523.30.33 kJ/mol, which are close to the experimental BDEs, 341.9 and 530.0 kJ/mol, respectively.

Li, Hui-ran; Cheng, Xin-lu; Zhang, Hong

2012-02-01

239

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

240

Diffusion welding of SiCp\\/2014Al composites using Ni as interlayer  

Microsoft Academic Search

SiCp\\/2014Al composites were bonded with the vacuum diffusion welding technique using Ni as the interlayer metal. Ni and Al were interdiffused and there were intermetallic compounds formed in the inter transition layer, which was composed of Ni3Al\\/\\/NiAl\\/\\/NiAl3. The relation between the diffusion distance and the element concentration was calculated according to Fick's second law. The relations of the diffusion concentration

Tao Feng; Xizhang Chen; Luhai Wu; Songnian Lou

2006-01-01

241

In Situ Characterization of NiTi/Ti6Al4V Joints During Reaction-Assisted Diffusion Bonding Using Ni/Ti Multilayers  

NASA Astrophysics Data System (ADS)

Reaction-assisted diffusion bonding process of NiTi and Ti6Al4V was studied in situ. For this purpose, experiments were carried out at the High Energy Materials Science beamline (P-07) at PETRA-III (DESY). Ni/Ti multilayer thin films 2.5 ?m thick with 12 and 25 nm modulation periods were directly deposited by magnetron sputtering onto the materials being joined. The NiTi and Ti6Al4V coated parts were placed with the films facing each other in a dilatometer equipped with Kapton windows for the x-ray beams. Microjoining was promoted by applying a 10 MPa pressure and inductively heating the materials, while simultaneously acquiring x-ray diffraction scans across the bond interface. Sound joints were produced at 750 C. The formation of the NiTi2 phase could not be avoided.

Cavaleiro, A. J.; Ramos, A. S.; Braz Fernandes, F. M.; Schell, N.; Vieira, M. T.

2014-05-01

242

Modified diffusion bonding for both Cu and SiO2 at 150 C in ambient air  

Microsoft Academic Search

This paper presents the vapor-assisted bonding method that is applicable to Cu and SiO2 at 150 C at atmospheric pressure. Considering a future three-dimensional integration of highly flattened substrates, such a bonding technology is expected to be effective in generating high binding energy on both the metal electrodes and the insulation layer at the same time. To interconnect the materials

Akitsu Shigetou; Tadatomo Suga

2010-01-01

243

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

244

Role of the interfacial thermal barrier in the effective thermal diffusivity/conductivity of SiC-fiber-reinforced reaction-bonded silicon nitride  

NASA Technical Reports Server (NTRS)

Experimental thermal diffusivity data transverse to the fiber direction for composites composed of a reaction bonded silicon nitride matrix reinforced with uniaxially aligned carbon-coated silicon carbide fibers indicate the existence of a significant thermal barrier at the matrix-fiber interface. Calculations of the interfacial thermal conductances indicate that at 300 C and 1-atm N2, more than 90 percent of the heat conduction across the interface occurs by gaseous conduction. Good agreement is obtained between thermal conductance values for the oxidized composite at 1 atm calculated from the thermal conductivity of the N2 gas and those inferred from the data for the effective composite thermal conductivity.

Bhatt, Hemanshu; Donaldson, Kimberly Y.; Hasselman, D. P. H.; Bhatt, R. T.

1990-01-01

245

Diffusion  

NSDL National Science Digital Library

Since the advent of the internet, a number of artists and related organizations have become interested in utilizing the web to promulgate new forms of artistic creation and their subsequent dissemination. Supported by the Arts Council of England, these Diffusion eBooks are essentially pdf files that readers can download, print out and make into booklets. As the site suggests, "the Diffusion format challenges conventions of interactivity-blending the physical and the virtual and breaking the dominance of mouse and screen as the primary forms of human computer interaction...the format's aim is to take the reader away from the screen and computer and engage them in the process of production." There are a number of creative booklets available here for visitors, complete with instruction on how to assemble them for the desired effect. For anyone with even a remote interest in the possibilities afforded by this rather curious new form of expression, this website is worth a look.

246

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.

247

The characteristics of atmospheric ice nuclei measured at the top of Huangshan (the Yellow Mountains) in Southeast China using a newly built static vacuum water vapor diffusion chamber  

NASA Astrophysics Data System (ADS)

A newly built static vacuum water vapor diffusion chamber was built to measure the concentration of ice nuclei (INs) at the top of Huangshan (the Yellow Mountains) in Southeast China. The experiments were conducted under temperatures between - 15 C and - 23 C and supersaturations with respect to ice between 4% and 25%. The results show that the average IN concentration was in the range of 0.27 to 7.02 L- 1, when the temperature was varied from - 15 C to - 23 C. The changes in IN concentrations with time were correlated with the change of number concentration of the aerosol particles of 0.5-20 ?m in diameter. The square correlation coefficients (R2) between IN and coarse aerosol particles (0.5-20 ?m in diameter) were all higher than 0.60, much higher than that (0.10) between IN and smaller particles (0.01-0.5 ?m). The concentration of ice nuclei at 14:00 LST was significantly higher than that at 08:00 LST, which is correlated with the diurnal variation of the concentration of aerosol particles. A parametric equation was developed based on measurements to represent the variations of IN concentration with temperature and supersaturation.

Jiang, Hui; Yin, Yan; Su, Hang; Shan, Yunpeng; Gao, Renjie

2015-02-01

248

A Stable Diffusion-Bonded Tm:YLF Bulk Laser with High Power Output at a Wavelength of 1889.5 nm  

NASA Astrophysics Data System (ADS)

A high power diode-pumped diffusion-bonded Tm:YLF laser operating at 1889.5 nm with a FWHM linewidth of less than 0.1 nm is reported. A Brewster plate and two FabryPerot etalons are inserted in the laser cavity for spectral narrowing and stabilization. Under an incident pump power of 136.8 W, 46.1 W of output power is achieved, corresponding to an optical-to-optical conversion efficiency of 33.7% and a slope efficiency of 42.8%. The laser wavelength shift of only 0.07 nm with the incident pump power from 20.1 W to 136.8 W is observed. The M2 factor at maximum output power is calculated to be 2.3 in the x-axis and 2.0 in the y-axis, respectively.

Duan, Xiao-Ming; Ding, Yu; Yao, Bao-Quan; Dai, Tong-Yu; Li, Ying-Yi; Jia, Fu-Li

2014-07-01

249

Structural changes and diffusion of vacancy clusters in diamond and paracyclophane cycloaddition: Insights into unusual carbon bonding  

NASA Astrophysics Data System (ADS)

High energy irradiation of diamond produces point defects that are observable by spectroscopy. While many defects have been confirmed such as the monovacancy V1, the divacancy V2, and various interstitials, most remain unidentified. The prediction of the properties of these defects through computational modeling is an important ally in solving these mysteries. Computational work on smaller vacancy clusters Vn in diamond had previously been performed with n up to 14 but these were always done with assumptions about that structures of the low energy clusters. A novel generational algorithm has allowed for the identification of the low energy clusters without structural bias. By going beyond n=14 insights have been made into the structural optimizations of large voids in carbon materials, which is important in helping describe Carbide-derived carbons (CDCs) at the atomistic level. Studying the mechanism of V2 formation has uncovered multiple stable non-contiguous divacancy structures with high spin that may be found in the ESR. The unique environment of vacancy clusters, within the rigid framework of the diamond lattice, gives rise to unusual carbon-carbon bond lengths. Molecular analogous where this kind of bonding can be found are rare but paracylophanes---which undergo [4+4] cycloaddition, spanning the spectrum of sp2 to sp3-hybridized carbon---are one example. This process mimics the diamond-to-graphite transition, the modeling of which offers valuable insight.

Slepetz, Brad M.

250

Plates for vacuum thermal fusion  

DOEpatents

A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

Davidson, James C. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

2002-01-01

251

Bonding thermoplastic polymers  

DOEpatents

We demonstrate a new method for joining patterned thermoplastic parts into layered structures. The method takes advantage of case-II permeant diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. It is capable of producing bonds characterized by cohesive failure while preserving the fidelity of patterned features in the bonding surfaces. This approach is uniquely suited to production of microfluidic multilayer structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometer length scales. The bond enhancing procedure is easily integrated in standard process flows and requires no specialized equipment.

Wallow, Thomas I. (Fremont, CA); Hunter, Marion C. (Livermore, CA); Krafcik, Karen Lee (Livermore, CA); Morales, Alfredo M. (Livermore, CA); Simmons, Blake A. (San Francisco, CA); Domeier, Linda A. (Danville, CA)

2008-06-24

252

Method for vacuum pressing electrochemical cell components  

NASA Technical Reports Server (NTRS)

Assembling electrochemical cell components using a bonding agent comprising aligning components of the electrochemical cell, applying a bonding agent between the components to bond the components together, placing the components within a container that is essentially a pliable bag, and drawing a vacuum within the bag, wherein the bag conforms to the shape of the components from the pressure outside the bag, thereby holding the components securely in place. The vacuum is passively maintained until the adhesive has cured and the components are securely bonded. The bonding agent used to bond the components of the electrochemical cell may be distributed to the bonding surface from distribution channels in the components. To prevent contamination with bonding agent, some areas may be treated to produce regions of preferred adhesive distribution and protected regions. Treatments may include polishing, etching, coating and providing protective grooves between the bonding surfaces and the protected regions.

Andrews, Craig C. (Inventor); Murphy, Oliver J. (Inventor)

2004-01-01

253

Stainless steel and silicon direct interface synthesis: Chemical bonding effects  

NASA Astrophysics Data System (ADS)

Planar stainless steel/stainless steel interfaces, with and without a titanium interlayer and silicon/silicon interfaces have been produced in an ultra high vacuum (UHV) diffusion bonding/deposition instrument. Interface synthesis was accomplished by diffusion bonding two substrates after subjecting the substrate surfaces to a variety of pre-bonding treatments including heat treating, ion-beam sputter cleaning and thin film deposition. Chemical characterization was performed in situ by Auger electron spectroscopy (AES) prior to deposition and/or bonding and ex situ by energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). Additionally, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study interfaces before and after bonding. Diffusion bonding behavior of stainless steel depends strongly on the chemistry of the surfaces to be bonded. Very smooth, mechanically polished and lapped substrates would bond completely in UHV in 1 hour at 1000C under 3.5 MPa uniaxial pressure, if the native oxide on the substrates was removed by ion beam cleaning. No voids were observed in these bonded interfaces as studied by TEM and the strength was equal to the unbonded bare material. When an electron beam deposited, 200 A titanium interlayer was added to the stainless steel interface, while bonding under the same conditions, mechanical tensile testing resulted in very low strength when compared with that of chemically clean stainless steel interfaces. Analytical inspection of the interfaces, performed with EELS, EDS, and convergent beam electron diffraction (CBED) coupled with images from TEM and SEM, showed the reason for the significantly reduced strength is a result of limited contact area and delamination between titanium carbide particles precipitated in the interface. Silicon wafers bicrystals were synthesized by bonding two single-crystal substrates. Silicon wafers were plasma or ion cleaned, chemically treated, and UHV thermal desorption annealed in different combinations to find the best method for providing smooth, contamination free substrates that will produce an atomically flat, chemically clean silicon/silicon bonded interface. Plasma cleaned wafers which were subsequently HF and de-ionized water dipped resulted in a flat and void free wafer bonded interface that was structurally sharp on the atomic scale.

Cox, Michael J.

254

Vacuum Plasma Spraying Replaces Electrodeposition  

NASA Technical Reports Server (NTRS)

Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

1992-01-01

255

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

256

Vacuum mechatronics  

NASA Technical Reports Server (NTRS)

The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.

Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo

1989-01-01

257

Vacuum Energy  

E-print Network

There appears to be three, perhaps related, ways of approaching the nature of vacuum energy . The first is to say that it is just the lowest energy state of a given, usually quantum, system. The second is to equate vacuum energy with the Casimir energy. The third is to note that an energy difference from a complete vacuum might have some long range effect, typically this energy difference is interpreted as the cosmological constant. All three approaches are reviewed, with an emphasis on recent work. It is hoped that this review is comprehensive in scope. There is a discussion on whether there is a relation between vacuum energy and inertia. The solution suggested here to the nature of the vacuum is that Casimir energy can produce short range effects because of boundary conditions, but that at long range there is no overall effect of vacuum energy, unless one considers lagrangians of higher order than Einstein's as vacuum induced. No original calculations are presented in support of this position. This is not a review of the cosmological constant {\\it per se}, but rather vacuum energy in general, my approach to the cosmological constant is not standard.

Mark D. Roberts

2000-12-07

258

Vacuum Virtues  

ERIC Educational Resources Information Center

Upright vacuums, like cars, vary in quality, features and performance. Like automobiles, some uprights are reliable, others may be problematic, and some become a problem as a result of neglect or improper use. So, how do education institutions make an informed choice and, having done so, ensure that an upright vacuum goes the distance? In this

Rathey, Allen

2007-01-01

259

Gravitational vacuum  

NASA Astrophysics Data System (ADS)

The existence of a special gravitational vacuum is considered in this paper. A phenomenological method differing from the traditional Einsteinian formalization is utilized. Vacuum, metric and matter form a complex determined by field equations and at great distances from gravitational masses vacuum effects are small but could be large in powerful fields. Singularities and black holes justify the approach as well as the Ambartsmyan theory concerning the existence of supermassive and superdense prestallar bodies that then disintegrate. A theory for these superdense bodies is developed involving gravitational field equations that describe the vacuum by an energy momentum tensor and define the field and mass distribution. Computations based on the theory for gravitational radii with incompressible liquid models adequately reflecting real conditions indicate that a gravitational vacuum could have considerable effects on superdense stars and could have radical effects for very large masses.

Grigoryan, L. S.; Saakyan, G. S.

1984-09-01

260

Microstructural evolution during transient liquid phase bonding of Inconel 738LC using AMS 4777 filler alloy  

SciTech Connect

IN-738LC nickel-based superalloy was joined by transient liquid phase diffusion bonding using AMS 4777 filler alloy. The bonding process was carried out at 1050 Degree-Sign C under vacuum atmosphere for various hold times. Microstructures of the joints were studied by optical and scanning electron microscopy. Continuous centerline eutectic phases, characterized as nickel-rich boride, chromium-rich boride and nickel-rich silicide were observed at the bonds with incomplete isothermal solidification. In addition to the centerline eutectic products, precipitation of boron-rich particles was observed in the diffusion affected zone. The results showed that, as the bonding time was increased to 75 min, the width of the eutectic zone was completely removed and the joint was isothermally solidified. Homogenization of isothermally solidified joints at 1120 Degree-Sign C for 300 min resulted in the elimination of intermetallic phases formed at the diffusion affected zone and the formation of significant {gamma} Prime precipitates in the joint region. - Highlights: Black-Right-Pointing-Pointer TLP bonding of IN-738LC superalloy was performed using AMS 4777 filler alloy. Black-Right-Pointing-Pointer Insufficient diffusion time resulted in the formation of eutectic product. Black-Right-Pointing-Pointer Precipitation of B-rich particles was observed within the DAZ. Black-Right-Pointing-Pointer The extent of isothermal solidification increased with increasing holding time. Black-Right-Pointing-Pointer Homogenizing of joints resulted in the dissolution of DAZ intermetallics.

Jalilvand, V., E-mail: jalilvand@aut.ac.ir [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413 (Iran, Islamic Republic of); Omidvar, H. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413 (Iran, Islamic Republic of)] [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413 (Iran, Islamic Republic of); Shakeri, H.R. [Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada)] [Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada); Rahimipour, M.R. [Department of Ceramic, Materials and Energy Research Center, Karaj 31787-316 (Iran, Islamic Republic of)] [Department of Ceramic, Materials and Energy Research Center, Karaj 31787-316 (Iran, Islamic Republic of)

2013-01-15

261

Fusion bonding and alignment fixture  

DOEpatents

An improved vacuum fusion bonding structure and process for aligned bonding of large area glass plates, patterned with microchannels and access holes and slots, for elevated glass fusion temperatures. Vacuum pumpout of all the components is through the bottom platform which yields an untouched, defect free top surface which greatly improves optical access through this smooth surface. Also, a completely non-adherent interlayer, such as graphite, with alignment and location features is located between the main steel platform and the glass plate pair, which makes large improvements in quality, yield, and ease of use, and enables aligned bonding of very large glass structures.

Ackler, Harold D. (Sunnyvale, CA); Swierkowski, Stefan P. (Livermore, CA); Tarte, Lisa A. (Livermore, CA); Hicks, Randall K. (Stockton, CA)

2000-01-01

262

Vacuum mounting for piezoelectric transducers  

NASA Technical Reports Server (NTRS)

Special housing couples piezoelectric transducers to nonporous surfaces for ultrasonic or acoustic-emission testing. Device, while providing sound isolation on flat or nonflat surfaces, can be attached and detached quickly. Vacuum sealing mechanism eliminates need for permanent or semipermanent bonds, viscous coupling liquids, weights, magnets, tape, or springs ordinarily used.

Tiede, D. A.

1977-01-01

263

Bent Bonds and Multiple Bonds.  

ERIC Educational Resources Information Center

Considers carbon-carbon multiple bonds in terms of Pauling's bent bond model, which allows direct calculation of double and triple bonds from the length of a CC single bond. Lengths of these multiple bonds are estimated from direct measurements on "bent-bond" models constructed of plastic tubing and standard kits. (CS)

Robinson, Edward A.; Gillespie, Ronald J.

1980-01-01

264

ESR vacuum system for the photon factory  

NASA Astrophysics Data System (ADS)

The vacuum system for the electron storage ring in the Photon Factory project is now under construction. In the beginning, we chose aluminum as the predominant material for the beam duct because of its cooling and forming properties, and ICF flanges for the connections because of its high reliability. These choices compelled us to employ some kind of transition material. Our tests showed that the transition between aluminum alloy (Al) and stainless steel (SUS) can be made either by using an Al-SUS clad plate (by explosion- and diffusion-bonding) or TIG welding with Ag and Ni plates in the spaces between. The vacuum system forms an elliptical ring with circumference of 187 m, and is mainly composed of three kinds of beam ducts and their pumping units. A B-type duct made of Al is installed at every bending magnet section, and has a passage for the distributed ion pump (DIP) along it inner arc wall. Q-type ducts can be classified into two kinds of straight ducts, types a and type b. Type-a duct made of Al is partially indented for the in-situ Ar discharge cleaning electrode, while type-b duct is made of SUS without any additional component. About 28 DIP units, 48 sputter ion pumps and 6 units of roughing pump will be installed around the ring. The design of the rough pumping units is in progress.

Kobayashi, Masanori; Horikoshi, Gen'ichi; Mizuno, Hajime

1980-11-01

265

Inorganic bonding of semiconductor strain gages  

NASA Technical Reports Server (NTRS)

Inorganic bonding materials minimize outgassing and improve electrical and mechanical properties of semiconductor strain-gage transducers in high-vacuum and high-temperature operations. The two basic methods described are ceramic-glass-bonding and metallic bond formation between the strain gage and the substrate.

Woodruff, N. L.

1970-01-01

266

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

267

Numerical simulation of transient liquid phase bonding under temperature gradient.  

E-print Network

??Transient Liquid Phase bonding under Temperature Gradient (TG-TLP bonding) is a relatively new process of TLP diffusion bonding family for joining difficult-to-weld aerospace materials. Earlier (more)

Ghobadi Bigvand, Arian

2013-01-01

268

Stoichiomeetric interlayer bonding of NiAl  

SciTech Connect

New joining methods must be developed in order to fully utilize the high temperature properties of advanced intermetallic alloys such as NiAl. In this study, a liquid-assisted diffusion bonding method is evaluated which eliminates the need for foreign melting-point depressants. Instead, the intermetallic compound, NiAl, is synthesized within the joint by isothermal reaction of elemental Ni and Al coatings preplaced in stoichiometric proportions on the surfaces to be joined. The kinetics of this bonding process were evaluated from a series of interrupted thermal treatments. Single-crystal NiAl substrates were coated with a stoichiometric proportion of Al on one side of the joint and Ni on the other by electron beam evaporation. The joints were heated in vacuum above the aluminum liquidus (1200{degrees}C) but below the melting point of the NiAl substrates for times between 1 and 32 h. Relatively thick interlayers, 0.25 mm (0.010 in.) Al and 0.165 mm (0.0065 in.) Ni, were used to facilitate characterization of the bond evolution. The composition profiles across the joints were measured by electron probe microanalysis. The liquid Al readily wet the Ni interlayer such that a commercial stop-off agent was required to control liquid spreading at 1200{degrees}C. Isothermal solidification was completed after approximately 1 h at 1200{degrees}C and a residual layer of Ni solid-solution fully transformed to NiAl within 4 h at 1200{degrees}C. Grain boundary migration across the joint interface was observed for all heat treatments. The process of stoichiometric interlayer bonding was demonstrated to be a feasible, and potentially very useful method for joining intermetallic compounds such as NiAl. Single-phase NiAl bonds were produced at relatively low temperatures, without applied pressure, and without the addition of foreign melting-point depressants.

Strum, M.J.; Henshall, G.A. [Lawrence Livermore National Lab., CA (United States)

1994-12-31

269

Reliability of dual compounds carbide composite+steel produced by diffusion welding  

Microsoft Academic Search

This paper focuses on the reliability (strength and residual welding stresses) of the dual compound of TiC-based composite+steel and WC-based hardmetal+steel produced by diffusion bonding (welding). Vacuum brazing was used as a reference technology. The influence of some metallurgical factors on the properties and structure of joints was investigated by SEM and EPMA. It was found that the TiC-based cermet

H. Klaasen; J. Kbarsepp; A. Laansoo; M. Viljus

2010-01-01

270

A Study of the Effect of Nanosized Particles on Transient Liquid Phase Diffusion Bonding Al6061 Metal-Matrix Composite (MMC) Using Ni/Al2O3 Nanocomposite Interlayer  

NASA Astrophysics Data System (ADS)

Transient liquid phase (TLP) diffusion bonding of Al-6061 containing 15 vol pct alumina particles was carried out at 873 K (600 C) using electrodeposited nanocomposite coatings as the interlayer. Joint formation was attributed to the solid-state diffusion of Ni into the Al-6061 alloy followed by eutectic formation and isothermal solidification of the joint region. An examination of the joint region using an electron probe microanalyzer (EPMA), transmission electron microscopy (TEM), wavelength-dispersive spectroscopy (WDS), and X-ray diffraction (XRD) showed the formation of intermetallic phases such as Al3Ni, Al9FeNi, and Ni3Si within the joint zone. The result indicated that the incorporation of 50 nm Al2O3 dispersions into the interlayer can be used to improve the joint significantly.

Cooke, Kavian O.

2012-06-01

271

Changing the diffusion mechanism of Ge-Si dimers on Si(001) using an electric field.  

PubMed

We change the diffusion mechanism of adsorbed Ge-Si dimers on Si(001) using the electric field of a scanning tunneling microscope tip. By comparing the measured field dependence with first-principles calculations we conclude that, in negative field, i.e., when electrons are attracted towards the vacuum, the dimer diffuses as a unit, rotating as it translates, whereas, in positive field the dimer bond is substantially stretched at the transition state as it slides along the substrate. Furthermore, the active mechanism in positive fields facilitates intermixing of Ge in the Si lattice, whereas intermixing is suppressed in negative fields. PMID:14683380

Sanders, L M; Stumpf, R; Mattsson, T R; Swartzentruber, B S

2003-11-14

272

Antibacterial activity of four dentin bonding systems  

Microsoft Academic Search

The antibacterial action of bonding systems Gluma 2000, Syntac, Prisma Universal Bond 3, Scotchbond Multipurpose and Prime-Bond was tested against 32 strains of the caries-producing bacteria Streptococcus spp., Lactobacillus spp., Actinomyces spp., Porphyromonas spp. and Clostridium spp. An agar plate diffusion method was used with chlorhexidine as the positive control. Assays were performed in triplicate for each component (primer and

Manuela Herrera; Paula Carrin; Manuel Bravo; Ana Castillo

2000-01-01

273

High Temperature Adhesives for Bonding Kapton  

NASA Technical Reports Server (NTRS)

Experimental polyimide resins were developed and evaluated as potential high temperature adhesives for bonding Kapton polyimide film. Lap shear strengths of Kapton/Kapton bonds were obtained as a function of test temperature, adherend thickness, and long term aging at 575K (575 F) in vacuum. Glass transition temperatures of the polyimide/Kapton bondlines were monitored by thermomechanical analysis.

Stclair, A. K.; Slemp, W. S.; Stclair, T. L.

1978-01-01

274

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

275

Vacuum plasma spray coating  

NASA Technical Reports Server (NTRS)

Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

Holmes, Richard R.; Mckechnie, Timothy N.

1989-01-01

276

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, John D. (Richland, WA)

1993-01-01

277

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

278

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

279

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, John D. (Kennewick, WA)

1995-01-01

280

Considerations in vacuum tribology (adhesion, friction, wear, and solid lubrication in vacuum)  

Microsoft Academic Search

The success of many tribological products used or tribological systems operated in vacuum depends on adequate control of adhesion between two or more materials. Adhesion (e.g., in adhesive bonding) is the mechanical force or strength required to separate the surfaces in contact. This foreword is concerned with adhesion, which has greatly contributed, and should continue to contribute, to tribological problems,

Kazuhisa Miyoshi

1999-01-01

281

Numerical Simulation of Transient Liquid Phase Bonding under Temperature Gradient  

NASA Astrophysics Data System (ADS)

Transient Liquid Phase bonding under Temperature Gradient (TG-TLP bonding) is a relatively new process of TLP diffusion bonding family for joining difficult-to-weld aerospace materials. Earlier studies have suggested that in contrast to the conventional TLP bonding process, liquid state diffusion drives joint solidification in TG-TLP bonding process. In the present work, a mass conservative numerical model that considers asymmetry in joint solidification is developed using finite element method to properly study the TG-TLP bonding process. The numerical results, which are experimentally verified, show that unlike what has been previously reported, solid state diffusion plays a major role in controlling the solidification behavior during TG-TLP bonding process. The newly developed model provides a vital tool for further elucidation of the TG-TLP bonding process.

Ghobadi Bigvand, Arian

282

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.

Boettcher, Gordon E. (Albuquerque, NM)

1990-01-01

283

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

284

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

285

Vacuum probe surface sampler  

NASA Technical Reports Server (NTRS)

A vacuum probe surface sampler is described for rapidly sampling relatively large surface areas which possess relatively light loading densities of micro-organism, drug particles or the like. A vacuum head with a hollow handle connected to a suitable vacuum source is frictionally attached to a cone assembly terminating in a flared tip adapted to be passed over the surface to be sampled. A fine mesh screen carried by the vacuum head provides support for a membrane filter which collects the microorganisms or other particles. The head assembly is easily removed from the cone assembly without contacting the cone assembly with human hands.

Zahlava, B. A. (inventor)

1973-01-01

286

NSLS II Vacuum System  

SciTech Connect

National Synchrotron Light Source II, being constructed at Brookhaven, is a 3-GeV, 500 mA, 3rd generation synchrotron radiation facility with ultra low emittance electron beams. The storage ring vacuum system has a circumference of 792 m and consists of over 250 vacuum chambers with a simulated average operating pressure of less than 1 x 10{sup -9} mbar. A summary of the update design of the vacuum system including girder supports of the chambers, gauges, vacuum pumps, bellows, beam position monitors and simulation of the average pressure will be shown. A brief description of the techniques and procedures for cleaning and mounting the chambers are given.

Ferreira, M.; Doom, L.; Hseuh, H.; Longo, C.; Settepani, P.; Wilson, K.; Hu, J.

2009-09-13

287

A fluxless bonding technology using indium-silver multilayer composites  

Microsoft Academic Search

A fluxless bonding process has been developed using indium-silver multilayer composites deposited on silicon and GaAs wafers in one high vacuum cycle to inhibit the oxidation of the bonding media. The in situ formation of AgIn2 intermetallic outer layer protects the inner media from oxidation when exposed to atmosphere. The bonding process is performed at 180C temperature in inert environment

Yi-Chia Chen; William W. So; Chin C. Lee

1997-01-01

288

Bonded Lubricants  

NASA Technical Reports Server (NTRS)

Another spinoff to the food processing industry involves a dry lubricant developed by General Magnaplate Corp. of Linden, N.J. Used in such spacecraft as Apollo, Skylab and Viking, the lubricant is a coating bonded to metal surfaces providing permanent lubrication and corrosion resistance. The coating lengthens equipment life and permits machinery to be operated at greater speed, thus increasing productivity and reducing costs. Bonded lubricants are used in scores of commercia1 applications. They have proved particularly valuable to food processing firms because, while increasing production efficiency, they also help meet the stringent USDA sanitation codes for food-handling equipment. For example, a cookie manufacturer plagued production interruptions because sticky batter was clogging the cookie molds had the brass molds coated to solve the problem. Similarly, a pasta producer faced USDA action on a sanitation violation because dough was clinging to an automatic ravioli-forming machine; use of the anti-stick coating on the steel forming plates solved the dual problem of sanitation deficiency and production line downtime.

1977-01-01

289

Adhesive wafer-to-wafer bonding using contact imprinting  

NASA Astrophysics Data System (ADS)

The present work proposes an adhesive bonding technique, at wafer level, using SU-8 negative photoresist as intermediate layer. The adhesive was selective imprint on one of the bonding surface. The main applications are in microfluidic area where a low temperature bonding is required. The method consists of three major steps. First the adhesive layer is deposited on one of the bonding surface by contact imprinting from a dummy wafer where the SU-8 photoresist was initially spun, or from a Teflon cylinder. Second, the wafers to be bonded are placed in contact and aligned. In the last step, the bonding process is performed at temperatures between 100C and 200C, a pressure of 1000 N in vacuum on a classical wafer bonding system. The results indicate a low stress value induced by the bonding technique. In the same time the process presents a high yield: 95-100%. The technique was successfully tested in the fabrication process of a dielectrophoretic device.

Yu, Liming; Pang, Ah Ju; Chen, Bangtao; Tay, Francis E. H.; Iliescu, Ciprian

2006-12-01

290

Vacuum Vessel Remote Handling  

E-print Network

FIRE Vacuum Vessel and Remote Handling Overview B. Nelson, T. Burgess, T. Brown, H-M Fan, G. Jones · Vacuum Vessel - Design requirements - Design concept and features - Analysis to date - Status and summary Replacement Time Estimates - Balance of RH Equipment · Design and analysis are consistent with pre

291

The ultimate vacuum  

Microsoft Academic Search

The ultimate vacuum, defined as the lowest pressure that can be produced and measured reproducibly in a vacuum system at room temperature, has decreased by a factor of about 1014 since the first measurement of sub-atmospheric pressure by Robert Boyle in about 1660. A brief historical review is presented of the key advances that caused significant decreases in the ultimate

P. A. Redhead

1999-01-01

292

Microfabricated triggered vacuum switch  

DOEpatents

A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

Roesler, Alexander W. (Tijeras, NM); Schare, Joshua M. (Albuquerque, NM); Bunch, Kyle (Albuquerque, NM)

2010-05-11

293

ELETTRA vacuum system  

NASA Astrophysics Data System (ADS)

A status report of the vacuum system of ELETTRA, the 2 GeV, 400 mA light source under construction in Trieste, will be described. The Vacuum project, presented at ``Synchrotron Radiation Vacuum Workshop'' at Riken (Japan 22-24 March 1990) and more recently at EVC-2, the European Vacuum Conference at Trieste (Italy 21-26 May 1990), is now in the phase of testing a prototype sector, which is 1/24 of the ring circumference. Details and some technological aspects of the fabrication will be reviewed together with the vacuum performances. Results of laboratory experiments on components, standard or not, allowed us to finalize the main choices in light of the general philosophy of the project and will be properly summarized.

Bernardini, M.

1991-08-01

294

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

295

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.

Affinito, John D. (Kennewick, WA)

1996-01-01

296

Partial-Transient-Liquid-Phase Bonding of Advanced Ceramics Using Surface-Modified Interlayers  

E-print Network

Diffusion-Controlled Formation of Liquid Intermediate Phase." WeldingDiffusion Bonding of Nickel Base Alloys." Transactions of the Japan WeldingDiffusion Bonded Nb-Al 2 O 3 and Cu-Al 2 O 3 Joints - the Role of Welding

Reynolds, Thomas Bither

2012-01-01

297

Transient-Liquid-Phase (TLP) Bonding of Al2O3 Using Nb-based Multilayer Interlayers  

E-print Network

Thin-Film Diffusion-Brazed Titanium. Welding Journal, vol.Diffusion-Controlled Formation of Liquid Intermediate Phase. WeldingDiffusion Bonding of Nickel Base Alloys. Transactions of the Japan Welding

Hong, Sung Moo

2009-01-01

298

Evading death by vacuum  

NASA Astrophysics Data System (ADS)

In the Standard Model, the Higgs potential allows only one minimum at tree level. But the open possibility that there might be two scalar doublets enriches the vacuum structure, allowing for the risk that we might now be in a metastable state, which we dub the panic vacuum. Current experiments at the LHC are probing the Higgs particle predicted as a result of the spontaneous symmetry breaking. Remarkably, in the two Higgs model with a softly broken U(1) symmetry, the LHC experiments already allow to exclude many panic vacuum solutions.

Barroso, A.; Ferreira, P. M.; Ivanov, I. P.; Santos, Rui; Silva, Joo P.

2013-09-01

299

Evading death by vacuum  

E-print Network

In the Standard Model, the Higgs potential allows only one minimum at tree-level. But the open possibility that there might be two scalar doublets enriches the vacuum structure, allowing for the risk that we might now be in a metastable state, which we dub the panic vacuum. Current experiments at the LHC are probing the Higgs particle predicted as a result of the spontaneous symmetry breaking. Remarkably, in the two Higgs model with a softly broken U(1) symmetry, the LHC experiments already preclude panic vacuum solutions.

A. Barroso; P. M. Ferreira; I. P. Ivanov; Rui Santos; Joo P. Silva

2012-11-26

300

Nanocrystal-enabled solid state bonding  

Microsoft Academic Search

In this project, we performed a preliminary set of sintering experiments to examine nanocrystal-enabled diffusion bonding (NEDB) in Ag-on-Ag and Cu-on-Cu using Ag nanoparticles. The experimental test matrix included the effects of material system, temperature, pressure, and particle size. The nanoparticle compacts were bonded between plates using a customized hot press, tested in shear, and examined post mortem using microscopy

Joseph David Puskar; Veena Tikare; Cristina Garcia Cardona; Mark Reece; Luke N. Brewer; Elizabeth Ann Holm

2010-01-01

301

Tungsten diffusion in olivine  

NASA Astrophysics Data System (ADS)

Diffusion of tungsten has been characterized in synthetic forsterite and natural olivine (Fo90) under dry conditions. The source of diffusant was a mixture of magnesium tungstate and olivine powders. Experiments were prepared by sealing the source material and polished olivine under vacuum in silica glass ampoules with solid buffers to buffer at NNO or IW. Prepared capsules were annealed in 1 atm furnaces for times ranging from 45 min to several weeks, at temperatures from 1050 to 1450 C. Tungsten distributions in the olivine were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for W diffusion in forsterite: D=1.010-8exp(-36528 kJ mol/RT) m s Diffusivities for the synthetic forsterite and natural Fe-bearing olivine are similar, and tungsten diffusion in olivine shows little dependence on crystallographic orientation or oxygen fugacity. The slow diffusivities measured for W in olivine indicate that Hf-W ages in olivine-metal systems will close to diffusive exchange at higher temperatures than other chronometers commonly used in cosmochronology, and that tungsten isotopic signatures will be less likely to be reset by subsequent thermal events.

Cherniak, D. J.; Van Orman, J. A.

2014-03-01

302

Use of vacuum bagging for fabricating thermoplastic microfluidic devices.  

PubMed

In this work we present a novel thermal bonding method for thermoplastic microfluidic devices. This simple method employs a modified vacuum bagging technique, a concept borrowed from the aerospace industry, to produce conventional thick substrate microfluidic devices, as well as multi-layer film devices. The bonds produced using this method are superior to those obtained using conventional thermal bonding methods, including thermal lamination, and are capable of sustaining burst pressures in excess of 550 kPa. To illustrate the utility of this method, thick substrate devices were produced, as well as a six-layer film device that incorporated several complex features. PMID:25329244

Cassano, Christopher L; Simon, Andrew J; Liu, Wei; Fredrickson, Carl; Hugh Fan, Z

2014-12-01

303

Vacuum Camera Cooler  

NASA Technical Reports Server (NTRS)

Acquiring cheap, moving video was impossible in a vacuum environment, due to camera overheating. This overheating is brought on by the lack of cooling media in vacuum. A water-jacketed camera cooler enclosure machined and assembled from copper plate and tube has been developed. The camera cooler (see figure) is cup-shaped and cooled by circulating water or nitrogen gas through copper tubing. The camera, a store-bought "spy type," is not designed to work in a vacuum. With some modifications the unit can be thermally connected when mounted in the cup portion of the camera cooler. The thermal conductivity is provided by copper tape between parts of the camera and the cooled enclosure. During initial testing of the demonstration unit, the camera cooler kept the CPU (central processing unit) of this video camera at operating temperature. This development allowed video recording of an in-progress test, within a vacuum environment.

Laugen, Geoffrey A.

2011-01-01

304

Pumpdown and Vacuum Pumps  

NSDL National Science Digital Library

This is a link to a PDF version of lecture slides that discuss vacuum pumpdown. Graphics are included which depict pumpdown procedure, venting procedure, pressure curves and system pumpdown. Keywords: Outgassing, pressure range, rotary vane, rotary piston, roots blower

Rack, Philip D.

305

FLOW ANALYSIS OF DIFFUSER-GETTER-DIFFUSER SYSTEMS  

SciTech Connect

Tritium clean-up systems typically deploy gas processing technologies between stages of palladium-silver (Pd/Ag) diffusers/permeators. The number of diffusers positioned before and after a gas clean-up process to obtain optimal system performance will vary with feed gas inert composition. A simple method to analyze optimal diffuser configuration is presented. The method assumes equilibrium across the Pd/Ag tubes and system flows are limited by diffuser vacuum pump speeds preceding or following the clean-up process. A plot of system feed as a function of inert feed gas composition for various diffuser configuration allows selection of a diffuser configuration for maximum throughput based on feed gas composition.

Klein, J; Dave W. Howard, D

2007-07-24

306

Vacuum plasma spray applications on liquid fuel rocket engines  

Microsoft Academic Search

The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z,

T. N. McKechnie; F. R. Zimmerman; M. A. Bryant

1992-01-01

307

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

308

Bonding with Your Baby  

MedlinePLUS

... the child's social and cognitive development. Why Is Bonding Important? Bonding is essential for a baby. Studies ... as biological parents and their children. Back Continue Bonding With Daddy Men these days spend more time ...

309

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

310

Bonding Diamond To Metal In Electronic Circuits  

NASA Technical Reports Server (NTRS)

Improved technique for bonding diamond to metal evolved from older technique of soldering or brazing and more suitable for fabrication of delicate electronic circuits. Involves diffusion bonding, developed to take advantage of electrically insulating, heat-conducting properties of diamond, using small diamond bars as supports for slow-wave transmission-line structures in traveling-wave-tube microwave amplifiers. No fillets or side coats formed because metal bonding strips not melted. Technique also used to mount such devices as transistors and diodes electrically insulated from, but thermally connected to, heat sinks.

Jacquez, Andrew E.

1993-01-01

311

29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.  

Code of Federal Regulations, 2013 CFR

...bonds, separate bonds and additional bonding. 2580.412-20 Section 2580...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules ...

2013-07-01

312

29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.  

Code of Federal Regulations, 2010 CFR

...bonds, separate bonds and additional bonding. 2580.412-20 Section 2580...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules ...

2010-07-01

313

29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.  

Code of Federal Regulations, 2012 CFR

...bonds, separate bonds and additional bonding. 2580.412-20 Section 2580...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules ...

2012-07-01

314

29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.  

Code of Federal Regulations, 2011 CFR

...bonds, separate bonds and additional bonding. 2580.412-20 Section 2580...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules ...

2011-07-01

315

29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.  

Code of Federal Regulations, 2014 CFR

...bonds, separate bonds and additional bonding. 2580.412-20 Section 2580...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules ...

2014-07-01

316

Microstructural characteristics of Au/Al bonded interfaces  

SciTech Connect

Fracture characteristics at the interface of ultrasonic bonds between Au and Al were characterized by SEM following pull-testing to effect separation of the bonded joints. Vertical sections at the bonding point were produced by ion-sputter thinning, and were examined by TEM. Results show that the thickness of the Au/Al atomic diffusion interface was about 500 nm due to combined effects of ultrasonic and thermal energy. Ultrasonic vibration activates dislocations in the crystalline lattice and increases atomic diffusion. The fracture morphology on the lift-off interface was dimpled rupture. Tensile fracture occurred during the pull-test not at the bonded interface but in the base material; the bond strength at the interface was enhanced by the diffusion reactions that occurred across the interface due to the combined ultrasonic and thermal energy.

Li Junhui [Mechanical-Electronical Engineering College, Central South University, Changsha, Hunan 410083 (China)]. E-mail: lijunhui@mail.csu.edu.cn; Han Lei [Mechanical-Electronical Engineering College, Central South University, Changsha, Hunan 410083 (China); Duan Jian [Mechanical-Electronical Engineering College, Central South University, Changsha, Hunan 410083 (China); Zhong Jue [Mechanical-Electronical Engineering College, Central South University, Changsha, Hunan 410083 (China)

2007-02-15

317

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

318

Cation Diffusion in Fluorapatite  

NASA Astrophysics Data System (ADS)

Diffusion of manganese and uranium has been characterized in natural and synthetic fluorapatite under dry conditions. The source of diffusant for Mn experiments were mixtures of ground synthetic or natural fluorapatite and MnO powder, heated in sealed silica glass capsules prior to diffusion anneals. Mn experiments were run by sealing source and apatite in silica glass capsules under vacuum, and annealing capsules in 1 atm furnaces for times ranging from thirty minutes to a few months, at temperatures from 650 to 1050C. The Mn distributions in the apatite were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for Mn diffusion in natural Durango fluorapatite, for diffusion parallel to c: DMn = 5.4x10-7exp(-288 kJ mol-1/RT)m2sec-1. Mn diffusion normal to c appears to be similar to diffusion parallel to c, and diffusivities in natural and synthetic fluorapatite are the same within experimental uncertainties. Uranium diffusion experiments were run with a U-doped microcrystalline apatite source, made through solid-state reaction of UO2, CaF2 and Ca3(PO4)2 under buffered (NNO) conditions. The source and apatite specimens were loaded into Pt capsules, then sealed under vacuum in silica glass capsules with a solid buffer (NNO). Preliminary results over the temperature range 1150-1250C yield the following Arrhenius relation: DU = 1.4x10-2exp(-511 kJ mol-1/RT)m2sec-1. Diffusivities of Mn are comparable to those of Sr (Cherniak and Ryerson, 1993), and slightly slower than Pb (Cherniak et al., 1991) in apatite. The ionic radii for divalent Mn, Sr, and Pb are 0.90, 1.21 and 1.23 , respectively, in 7-fold coordination (Shannon, 1976), and 1.00, 1.31, and 1.35 in 9-fold. The similar diffusion rates for Sr and Mn, despite their significant differences in cationic radii, suggest that cation size does not exert strong influence on diffusion of divalent cations in apatite, a finding consistent with that observed for the trivalent REE. Cation charge, however, does seem to more significantly influence diffusivities in apatite. U diffusion is about 4 orders of magnitude slower than Mn diffusion, and about 2 orders of magnitude slower than REE diffusion (Cherniak, 2000). Further, these results suggest that the activation energy for U diffusion is significantly higher than those for divalent cations or trivalent REE. Cherniak et al. (1991) GCA 55, 1663-1673; Cherniak and Ryerson (1993) GCA 57, 4653-4662; Cherniak (2000) GCA 64, 3871-3885; Shannon (1976) Acta Cryst. A32, 751-767.

Cherniak, D. J.

2002-12-01

319

Bond University Queensland, Australia  

E-print Network

Bond University Queensland, Australia About: Bond University is a private university located institutions, Bond has a strong component of international students who hail from some 80 countries worldwide. Bond's small size, internationalized-student body, 14-week trimesters, and fabulous Gold Coast location

Duchowski, Andrew T.

320

Vacuum driven accelerated expansion  

E-print Network

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.

Bogus?aw Broda; Piotr Bronowski; Marcin Ostrowski; Micha? Szanecki

2008-12-29

321

The beginnings of surface diffusion studies  

NASA Astrophysics Data System (ADS)

Studies of surface diffusion on solids, from its discovery by Hamburger in 1918 and later by Volmer and colleagues, to the first quantitative diffusion measurements, by Langmuir and Taylor and later, are briefly reviewed, together with work done in the first few years after World War 2. The aim is to trace how the field developed in its early stages. After its discovery, surface diffusion was accepted rapidly by the scientific community, but significant quantitative measurements under good vacuum conditions took a long time to achieve. It was only after the period covered here that quantitative diffusivity measurements and studies on single atom diffusion over surfaces were finally accomplished.

Antczak, Grazyna; Ehrlich, Gert

2005-09-01

322

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.

323

Durability predictions for adhesively bonded joints in humid environments  

Microsoft Academic Search

The research objective of this study was to develop an understanding of the cohesive failure of adhesively bonded joints under load in aggressive environments. Such an understanding could then be used to predict the durability of adhesively bonded joints in humid environments. The problem was to have been approached by first examining the diffusion kinetics and then modeling the deformation

G. J. Rodin; K. M. Liechti

1993-01-01

324

Bonding soft rubber or plasticized elastomers to metal  

NASA Technical Reports Server (NTRS)

Approach using bond-cover coat of unplasticized rubber between soft rubber and adhesive eliminates diffusion problem. Approach is useful in making improved seals in automobile engines, industrial and public plumbing, and in other areas using soft-rubber-to-metal bonds. Seals and gaskets made this way would not have to be replaced very often, reducing cost of maintenance.

Clemons, J. M.; Ledbetter, F. E., III; White, W. T.

1980-01-01

325

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.

326

LET'S BOND! A Chemical Bonding Webquest  

NSDL National Science Digital Library

Today we are going to use the internet to explore chemical bonding! Even though there are just a few questions for each website, you need to read the entire content. Don't worry about understanding all of it, but make sure that you are familiar with it! Stay on task and have fun! Let's start with some basics. Click on the link below and answer the questions on your worksheet under "Bonding Basics". Bonding Basics Good job! Lets move on and talk about ions. Ions are a big part of bonding, so make sure you get this section down pat! Click on the ...

Hicken, Mrs.

2009-04-08

327

Vaneless diffusers  

Microsoft Academic Search

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

Y. Senoo

1984-01-01

328

Vacuum Packaging of MEMS With Multiple Internal Seal Rings  

NASA Technical Reports Server (NTRS)

A proposed method of design and fabrication of vacuum-packaged microelectromechanical systems (MEMS) and of individual microelectromechanical devices involves the use of multiple internal seal rings (MISRs) in conjunction with vias (through holes plated with metal for electrical contacts). The proposed method is compatible with mass production in a wafer-level fabrication process, in which the dozens of MEMS or individual microelectromechanical devices on a typical wafer are simultaneously vacuum packaged by bonding a capping wafer before the devices are singulated (cut apart by use of a dicing saw). In addition to being compatible with mass production, the proposed method would eliminate the need for some complex and expensive production steps and would yield more reliable vacuum seals. Conventionally, each MEMS or individual microelectromechanical device is fabricated as one of many identical units on a device wafer. Vacuum packaging is accomplished by bonding the device wafer to a capping wafer with metal seal rings (one ring surrounding each unit) that have been formed on the capping wafer. The electrical leads of each unit are laid out on what would otherwise be a flat surface of the device wafer, against which the seal ring is to be pressed for sealing. The resulting pattern of metal lines and their insulating oxide coverings presents a very rough and uneven surface, upon which it is difficult to pattern the sealing metal. Consequently, the seal is prone to leakage unless additional costly and complex planarization steps are performed before patterning the seal ring and bonding the wafers.

Hayworth, Ken; Yee, Karl; Shcheglov, Kirill; Bae, Youngsam; Wiberg, Dean; Peay, Chris; Challoner, Anthony

2008-01-01

329

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

330

A vacuum chamber feedthrough  

NASA Technical Reports Server (NTRS)

Simple and inexpensive microwave feedthrough has been designed which transfers 130 ns, 5kV pulse into vacuum chamber. Feedthrough may be used over wide range and is adaptable to most coaxial cables, since either multistrand or single strand center conductor cable can be used.

Brown, V. D.

1973-01-01

331

Vacuum ultraviolet holography  

NASA Technical Reports Server (NTRS)

The authors report the first demonstration of holographic techniques in the vacuum ultraviolet spectral region. Holograms were produced with coherent 1182 A radiation. The holograms were recorded in polymethyl methacrylate and read out with an electron microscope. A holographic grating with a fringe spacing of 836 A was produced and far-field Fraunhofer holograms of sub-micron particles were recorded.

Bjorklund, G. C.; Harris, S. E.; Young, J. F.

1974-01-01

332

Vacuum ultraviolet holography  

NASA Technical Reports Server (NTRS)

We report the first demonstration of holographic techniques in the vacuum ultraviolet spectral region. Holograms were produced with coherent 1182-A radiation. The holograms were recorded in polymethyl methacrylate and examined with an electron microscope. A holographic grating with a fringe spacing of 386 A was produced and far-field Fraunhofer holograms of submicron particles were recorded.

Bjorklund, G. C.; Harris, S. E.; Young, J. F.

1974-01-01

333

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

334

On Lovelock vacuum solution  

E-print Network

We show that the asymptotic large $r$ limit of all Lovelock vacuum and electrovac solutions with $\\Lambda$ is always the Einstein solution in $d \\geq 2n+1$ dimensions. It is completely free of the order $n$ of the Lovelock polynomial indicating universal asymptotic behaviour.

Naresh Dadhich

2010-12-18

335

Diffusion welding of aluminum to stainless steel  

Microsoft Academic Search

Use of Ag films evaporated from a hot hollow cathode source improves the diffusion welding of Al to stainless steel. High-strength metallurgical bonds were reliably achieved at 204°C and 117 MPa for 10 minutes. At ambient temperatures, bond integrity is of long duration. (DLC)

E. R. Naimon; J. H. Doyle; C. R. Rice; D. Vigil; D. R. Walmsley

1981-01-01

336

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

337

Cryogenic evaluation of epoxy bond strength  

NASA Astrophysics Data System (ADS)

The purpose of the work presented here was to determine methods of optimizing the adhesion of a particular epoxy (CTD-101K, Composite Technology Development Inc.) to a particular nickel-based alloy substrate (Incoloy 908, Inco Alloys International) for cryogenic applications. Initial efforts were focused on surface preparation of the substrate material via various mechanical and chemical cleaning techniques. Test samples, fabricated to simulate the conduit-to-insulation interface, were put through a mock heat treat and vacuum/pressure impregnation process. Samples were compression/shear load tested to compare the bond strengths at room temperature and liquid nitrogen temperature. The resulting data indicate that acid etching creates a higher bond strength than the other tested techniques and that the bond formed is stronger at cryogenic temperatures than at room temperature. A description of the experiment along with the resulting data is presented here.

Albritton, N.; Young, W.

338

Hydroxide-catalyzed bonding  

NASA Technical Reports Server (NTRS)

A method of bonding substrates by hydroxide-catalyzed hydration/dehydration involves applying a bonding material to at least one surface to be bonded, and placing the at least one surface sufficiently close to another surface such that a bonding interface is formed between them. A bonding material of the invention comprises a source of hydroxide ions, and may optionally include a silicate component, a particulate filling material, and a property-modifying component. Bonding methods of the invention reliably and reproducibly provide bonds which are strong and precise, and which may be tailored according to a wide range of possible applications. Possible applications for bonding materials of the invention include: forming composite materials, coating substrates, forming laminate structures, assembly of precision optical components, and preparing objects of defined geometry and composition. Bonding materials and methods of preparing the same are also disclosed.

Gwo, Dz-Hung (Inventor)

2003-01-01

339

Channel Bonding Notes 03/25/2004 Channel Bonding Notes  

E-print Network

Channel Bonding Notes 03/25/2004 Channel Bonding Notes Luke Hindman Department of Computer Science by attempting to use the Linux kernel bonding driver (bonding.o) to implement channel bonding on the master node. However, each time I would bring up the bonded interface (bond0) I would loose communication

Jain, Amit

340

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.

341

Realization of MEMS-IC Vertical Integration Utilizing Smart Bumpless Bonding  

NASA Astrophysics Data System (ADS)

This paper reports fundamental technologies, properties, and new experimental results of SBB (Smart Bumpless Bonding) to realize MEMS-IC vertical integration. Although conventional bonding technologies have had difficulties integrating MEMS and its processing circuit because of their rough bonding surfaces, fragile structures, and thermal restriction, SBB technology realized the vertical integration without thermal treatment, any adhesive materials including bumps, and chemical mechanical polishing. The SBB technology bonds sealing parts for vacuum sealing and electrodes for electrical connection simultaneously as published in previous experimental study. The plasma CVD SiO2 is utilized to realize vacuum sealing as sealing material. And Au projection studs are formed on each electrode and connected electrically between two wafers by compressive plastic deformation and surface activation. In this paper, new experimental results including vacuum sealing properties, electrical improvement, IC bonding results on the described fundamental concept and properties are reported.

Shiozaki, Masayoshi; Moriguchi, Makoto; Sasaki, Sho; Oba, Masatoshi

342

Solid state bonding of Zircaloy-2 with stainless steel  

NASA Astrophysics Data System (ADS)

Zircaloy-2 and stainless steel have been diffusion bonded together with titanium and iron as barriers. Electron microprobe and optical microscopy studies reveal that no intermetallic compound/intermediate phase forms at the interfaces involved. Layer growth kinetics of diffusion zones have also been studied and the absence of these intermediate phases have been discussed with respect to their nucleation and growth parameters.

Kale, G. B.; Bhanumurthy, K.; Ratnakala, K. C.; Khera, S. K.

1986-03-01

343

Vacuum application of thermal barrier plasma coatings  

NASA Technical Reports Server (NTRS)

Coatings are presently applied to Space Shuttle Main Engine (SSME) turbine blades for protection against the harsh environment realized in the engine during lift off-to-orbit. High performance nickel, chromium, aluminum, and yttrium (NiCrAlY) alloy coatings, which are applied by atmospheric plasma spraying, crack and spall off because of the severe thermal shock experienced during start-up and shut-down of the engine. Ceramic coatings of yttria stabilized zirconia (ZrO2-Y2O3) were applied initially as a thermal barrier over coating to the NiCrAlY but were removed because of even greater spalling. Utilizing a vacuum plasma spraying process, bond coatings of NiCrAlY were applied in a low pressure atmosphere of argon/helium, producing significantly improved coating-to-blade bonding. The improved coatings showed no spalling after 40 MSFC burner rig thermal shock cycles, cycling between 1700 and -423 F. The current atmospheric plasma NiCrAlY coatings spalled during 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2-Y2O3 to the turbine blades of first stage high-pressure fuel turbopumps utilizing the vacuum plasma process. The improved thermal barrier coating has successfully passed 40 burner rig thermal shock cycles without spalling. Hot firing in an SSME turbine engine is scheduled for the blades. Tooling was installed in preparation for vacuum plasma spray coating other SSME hardware, e.g., the titanium main fuel valve housing (MFVH) and the fuel turbopump nozzle/stator.

Holmes, R. R.; Mckechnie, T. N.

1988-01-01

344

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

345

Diffusely Reflecting Paints Containing TFE  

NASA Technical Reports Server (NTRS)

Highly reflective, diffused coatings developed by incorporating polytetrafluoroethylene (TFE) pigment with alcohol-soluble binders. Alcohol and binder mixed together in blender before adding TFE. TFE preferably outgassed in mechanical-pump vacuum for typical interval of 4 hours before adding to liquid. Like wetting agent, vacuum treatment helps to prevent clumping of TFE and eases dispersion throughout mixture. Mixture blended for 3 to 5 minutes before used. Coatings useful on reflectance-standard surfaces for calibrating radiometric instruments in both laboratory and field. Paints washable and usable as optical reference surfaces.

Shai, M. C.; Schutt, J. B.

1985-01-01

346

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

347

Portable vacuum object handling device  

SciTech Connect

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 actuable to apply the vacuum to lift the object.

Anderson, G.H.

1981-07-30

348

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.

Anderson, Gordon H. (Los Alamos, NM)

1983-08-09

349

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

350

Nanocrystal-enabled solid state bonding.  

SciTech Connect

In this project, we performed a preliminary set of sintering experiments to examine nanocrystal-enabled diffusion bonding (NEDB) in Ag-on-Ag and Cu-on-Cu using Ag nanoparticles. The experimental test matrix included the effects of material system, temperature, pressure, and particle size. The nanoparticle compacts were bonded between plates using a customized hot press, tested in shear, and examined post mortem using microscopy techniques. NEDB was found to be a feasible mechanism for low-temperature, low-pressure, solid-state bonding of like materials, creating bonded interfaces that were able to support substantial loads. The maximum supported shear strength varied substantially within sample cohorts due to variation in bonded area; however, systematic variation with fabrication conditions was also observed. Mesoscale sintering simulations were performed in order to understand whether sintering models can aid in understanding the NEDB process. A pressure-assisted sintering model was incorporated into the SPPARKS kinetic Monte Carlo sintering code. Results reproduce most of the qualitative behavior observed in experiments, indicating that simulation can augment experiments during the development of the NEDB process. Because NEDB offers a promising route to low-temperature, low-pressure, solid-state bonding, we recommend further research and development with a goal of devising new NEDB bonding processes to support Sandia's customers.

San Diego State University, San Diego, CA; Puskar, Joseph David; Tikare, Veena; Garcia Cardona, Cristina (San Diego State University, San Diego, CA); Reece, Mark; Brewer, Luke N. (Naval Postgraduate School, Monterey, CA); Holm, Elizabeth Ann

2010-10-01

351

Essays on corporate bonds  

E-print Network

This thesis consists of three empirical essays on corporate bonds, examining the role of both credit risk and liquidity. In the first chapter, I test the ability of structural models of default to price corporate bonds in ...

Bao, Jack (Jack C.)

2009-01-01

352

Compact vacuum insulation  

DOEpatents

An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

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

1993-01-01

353

Compact vacuum insulation embodiments  

DOEpatents

An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

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

1992-01-01

354

Compact vacuum insulation  

DOEpatents

An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point'' or line'' contacts with the metal wall sheets. In the case of monolithic spacers that form line'' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point'' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

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

1993-01-05

355

Integrated structure vacuum tube  

NASA Technical Reports Server (NTRS)

High efficiency, multi-dimensional thin film vacuum tubes suitable for use in high temperature, high radiation environments are described. The tubes are fabricated by placing thin film electrode members in selected arrays on facing interior wall surfaces of an alumina substrate envelope. Cathode members are formed using thin films of triple carbonate. The photoresist used in photolithography aids in activation of the cathodes by carbonizing and reacting with the reduced carbonates when heated in vacuum during forming. The finely powdered triple carbonate is mixed with the photoresist used to delineate the cathode locations in the conventional solid state photolithographic manner. Anode and grid members are formed using thin films of refractory metal. Electron flow in the tubes is between grid elements from cathode to anode as in a conventional three-dimensional tube.

Dimeff, J.; Kerwin, W. J. (inventors)

1976-01-01

356

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

357

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

358

The vacuum energy crisis  

E-print Network

The smallness of the vacuum energy density and its near coincidence with the average matter density of the universe are naturally explained by anthropic selection. An alternative explanation, based on the cyclic model of Steinhardt and Turok, does not address the coincidence problem and is therefore less convincing. This article appeared in ``Science'' (4 May 2006) as a ``perspective'' for Steinhardt and Turok's paper in the same issue (astro-ph/0605173).

Alexander Vilenkin

2006-05-09

359

Is vacuum dispersive?  

E-print Network

The question we ask is: does the speed of light {\\it{in vacuo}} depend on its frequency? While the answer is NO in the frame of classical physics, we point out that the opposite could be true if one takes into account the polarization of Dirac sea. We estimate the dependence of the index of refraction of vacuum + Dirac sea versus the wavelength of an incoming beam, and suggest a way to test this effect.

Yves Pomeau

2014-09-02

360

Bonding silicones with epoxies  

SciTech Connect

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 surface energy of the silicone and thus provides a lower water contact angle. This phenomenon allows the epoxy adhesive to wet the silicone surface and ultimately bond. Bond strengths are sufficiently high to result in failures in the silicone materials rather than the adhesive bond.

Tira, J.S.

1980-01-01

361

The LHC Vacuum System  

NASA Astrophysics Data System (ADS)

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 K and therefore a very good cryo-pump. To reduce the cryogenic power consumption, the heat load from synchrotron radiation and from the image currents in the vacuum chamber will be absorbed on a 'beam screen', which operates between 5 and 20 K, inserted in the magnet cold bore. The design pressure necessary for operation must provide a lifetime of many days and a stringent requirement comes from the power deposition in the superconducting magnet coils due to protons scattered on the residual gas which could lead to a magnet quench. Cryo-pumping of gas on the cold surfaces provides the necessary low gas densities but it must be ensured that the vapour pressure of cryo-sorbed molecules, of which H2 and He would be the most critical species, remains within acceptable limits. The room temperature sections of the LHC, specifically in the experiments, the vacuum must be stable against ion induced desorption and ISR-type 'pressure bumps'.

Grbner, O.

1997-05-01

362

Rapid adhesive bonding concepts  

NASA Technical Reports Server (NTRS)

Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

1984-01-01

363

Local Currency Bond Markets  

Microsoft Academic Search

This paper analyzes the development of 49 local bond markets. The main finding is that policies and laws matter: countries with stable inflation rates and strong creditor rights have more developed local bond markets and rely less on foreign- currency-denominated bonds. The results suggest that \\

FRANCIS E. WARNOCK

2006-01-01

364

Acrylic mechanical bond tests  

SciTech Connect

The tensile strength of bonded acrylic is tested as a function of bond joint thickness. 0.125 in. thick bond joints were found to posses the maximum strength while the acceptable range of joints varied from 0.063 in. to almost 0.25 in. Such joints are used in the Sudbury Neutrino Observatory.

Wouters, J.M.; Doe, P.J.

1991-02-01

365

Braze alloy holds bonding strength over wide temperature range  

NASA Technical Reports Server (NTRS)

Copper-based quaternary alloys of the solid solution type is used for vacuum furnace brazing of large stainless steel components at a maximum temperature of 1975 deg F. The alloy has high bonding strength and good ductility over a temperature range extending from the cryogenic region to approximately 800 deg F.

1966-01-01

366

Diffusion of highly charged cations in olivine  

NASA Astrophysics Data System (ADS)

Diffusion of tungsten, titanium and phosphorus have been measured in natural iron-bearing olivine (~Fo90) and synthetic forsterite. Experiments were run under buffered conditions (with iron-wustite or Ni-NiO buffers) in 1-atm furnaces. The sources of diffusant for experiments were MgWO4 for tungsten diffusion, Mg2TiO4 for Ti diffusion, and AlPO4 for P diffusion; in all cases these compounds were pre-reacted at high temperature with Mg2SiO4 or Fe-bearing olivine prior to diffusion anneals. Samples were placed with the source materials in noble metal or silica capsules, which were sealed under vacuum in silica glass ampoules with solid buffers. Rutherford backscattering spectrometry (RBS) was used to measure depth profiles for all sets of experiments; measurements of P were also made with Nuclear Reaction Analysis using the 31P(?,p)34S reaction. These new data suggest marked differences among diffusivities of these cations, with titanium diffusion faster than diffusion of tungsten, but slower than diffusion of phosphorus over the conditions investigated. Diffusivities of all of these elements appear significantly slower than those of divalent cations in olivine. These results will be discussed in context with extant diffusion data for major, trace and minor elements in olivine. The effects of oxygen fugacity and olivine composition on diffusion, and potential implications for diffusion mechanisms will also be considered.

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

2012-12-01

367

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

368

Low Temperature Transient Liquid Phase (LTTLP) Bonding for Au/Cu  

E-print Network

) ) M. M. Hou Low Temperature Transient Liquid Phase (LTTLP) Bonding for Au/Cu and Cu of Technology, Cambridge, MA 02139 TheLow Temperature TransientLiquidPhase Diffusion Bonding (LTTLP) process has been bonded to copper heatsink.s at temperatures less than 160"C, using /n-Sn eutectic solders. After

Eagar, Thomas W.

369

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

370

Chemical Bonding, Interfaces and Defects in Hafnium Oxide/Germanium Oxynitride Gate Stacks on Ge (100)  

SciTech Connect

Correlations among interface properties and chemical bonding characteristics in HfO{sub 2}/GeO{sub x}N{sub y}/Ge MIS stacks were investigated using in-situ remote nitridation of the Ge (100) surface prior to HfO{sub 2} atomic layer deposition (ALD). Ultra thin ({approx}1.1 nm), thermally stable and aqueous etch-resistant GeO{sub x}N{sub y} interfaces layers that exhibited Ge core level photoelectron spectra (PES) similar to stoichiometric Ge{sub 3}N{sub 4} were synthesized. To evaluate GeO{sub x}N{sub y}/Ge interface defects, the density of interface states (D{sub it}) was extracted by the conductance method across the band gap. Forming gas annealed (FGA) samples exhibited substantially lower D{sub it} ({approx} 1 x 10{sup 12} cm{sup -2} eV{sup -1}) than did high vacuum annealed (HVA) and inert gas anneal (IGA) samples ({approx} 1x 10{sup 13} cm{sup -2} eV{sup -1}). Germanium core level photoelectron spectra from similar FGA-treated samples detected out-diffusion of germanium oxide to the HfO{sub 2} film surface and apparent modification of chemical bonding at the GeO{sub x}N{sub y}/Ge interface, which is related to the reduced D{sub it}.

Oshima, Yasuhiro; /Stanford U., Materials Sci. Dept.; Sun, Yun; /SLAC, SSRL; Kuzum, Duygu; /Stanford U.; Sugawara, Takuya; Saraswat, Krishna C.; Pianetta, Piero; /SLAC, SSRL; McIntyre, Paul C.; /Stanford U., Materials Sci. Dept.

2008-10-31

371

Particle bonding, annealing response, and mechanical properties of dynamically consolidated type 304 stainless steel powders  

Microsoft Academic Search

The nature of interparticle bonding in explosively consolidated, centrifugally atomized (CA), and vacuum gas-atomized (VGA) Type 304 stainless steel powders has been examined. Stress waves with sufficient amplitude to produce full density do not necessarily produce metallurgical bonds between particles; the local strain and strain rate are found to determine the degree of local heating and, in turn, the degree

R. N. Wright; G. E. Korth; J. E. Flinn

1989-01-01

372

Prospective bonding applications  

NASA Astrophysics Data System (ADS)

Adhesive bonding in industry and in the laboratory is surveyed and prospects for its wider utilization are assessed. The economic impact of bonding technology on industry is discussed. Research is reviewed, centering on the development of nondestructive testing and inspection techniques. Traditional (wood) as well as new materials susceptible to bonding are considered. Applications in construction and civil engineering, in aeronautics, and in the automobile industry are covered. The use of glues in mechanical constructions, in assembling cylindrical parts, and in metal-metal bonding are examined. Hybrid assembling and bonding of composite materials are included.

Ancenay, H.; Benazet, D.

1981-07-01

373

Bonding of reinforced Teflon to metals  

NASA Technical Reports Server (NTRS)

Reinforced FEP Teflon composite material is bonded to a metal substrate by applying a thin layer of copper on the metal surface and disposing irregularly shaped copper particles on the coated surface. The reinforced Teflon is then assembled in contact with the particles, and the assembly is heated under pressure at an elevated temperature below the melting point of the Teflon. A diffusion bond stronger than the reinforced Teflon component is produced, thus enabling the fabrication of self-lubricating bodies with relatively high strength.

Laiacona, F. P. (inventor)

1971-01-01

374

Hydroxide catalysis bonding for astronomical instruments  

NASA Astrophysics Data System (ADS)

Hydroxide catalysis bonding (HCB) as a jointing technique has been under development for astronomical applications since 1998 (patented by D.-H. Gwo). It uses an aqueous hydroxide solution to form a chemical bond between oxide or oxidisable materials (e.g., SiO2, sapphire, silicon and SiC). It forms strong, extremely thin bonds, and is suitable for room temperature bonding, precision alignment, operation in ultra-low vacuum and down to temperatures of 2.5 K. It has been applied in the NASA satellite mission Gravity Probe B and in the ground-based gravitational wave (GW) detector GEO600. It will soon fly again on the ESA LISA Pathfinder mission and is currently being implemented in the Advanced LIGO and Virgo ground-based GW detectors. This technique is also of considerable interest for use in other astronomical fields and indeed more broadly, due to its desirable, and adjustable, combination of properties. This paper gives an overview of how HCB has been and can be applied in astronomical instruments, including an overview of the current literature on the properties of hydroxide catalysis bonds.

van Veggel, Anna-Maria A.; Killow, Christian J.

2014-06-01

375

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

376

Vacuum plasma spray applications on liquid fuel rocket engines  

NASA Technical Reports Server (NTRS)

The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z, combustion chamber liners, and structural nickel base material, Inconel 718, for nozzle and combustion chamber support jackets.

Mckechnie, T. N.; Zimmerman, F. R.; Bryant, M. A.

1992-01-01

377

Avoiding Death by Vacuum  

NASA Astrophysics Data System (ADS)

The two-Higgs doublet model (2HDM) can have two electroweak breaking, CP-conserving, minima. The possibility arises that the minimum which corresponds to the known elementary particle spectrum is metastable, a possibility we call the "panic vacuum". We present analytical bounds on the parameters of the softly broken Peccei-Quinn 2HDM which are necessary and sufficient conditions to avoid this possibility. We also show that, for this particular model, the current LHC data already tell us that we are necessarily in the global minimum of the theory, regardless of any cosmological considerations about the lifetime of the false vacua.

Barroso, A.; Ferreira, P. M.; Ivanov, I.; Santos, R.; Silva, Joo P.

2013-07-01

378

What is vacuum?  

E-print Network

Vacuum can be defined with exact mathematical precision as the state which remains when a fermion, with all its special characteristics, is created out of absolutely nothing. The definition leads to a special form of relativistic quantum mechanics, which only requires the construction of a creation operator. This form of quantum mechanics is especially powerful for analytic calculation, at the same time as explaining, from first principles, many aspects of the Standard Model of particle physics. In particular, the characteristics of the weak, strong and electric interactions can be derived from the structure of the creation operator itself.

Peter Rowlands

2008-10-01

379

Development and evaluation of vacuum pressure gauge components from carbon and graphite  

NASA Technical Reports Server (NTRS)

A prototype all carbon triode ultrahigh vacuum gage was fabricated and tested. The gage exhibited a sensitivity of 3.7 per torr for nitrogen and an X-ray background approximately 0.1 as large as would be expected of a metal gage of the same design. The gage made from these materials, showed good sensitivity and durability. A practical technique was developed for bonding carbon components together without metal fasteners. The bond is made with a cross-linked phenolic resin which is converted to vitreous carbon by a careful pyrolysis procedure. The resulting bonds are strong, electrically conductive, and can withstand repeated excursions to 2500 K in vacuum. Measurements of adsorption and outgassing characteristics of four refractory carbons have confirmed that such materials are suitable for use in ultrahigh vacuum and that some are superior refractory metals in man respects.

Benson, D. K.; Beitel, G. A.

1972-01-01

380

R&D ERL: Vacuum  

SciTech Connect

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 insulating the 5-cell Superconducting RF Cavity and the Superconducting e-gun structures. The last ERL vacuum volume not shown in the schematic is the laser transport line. The beamline vacuum regions are separated by electropneumatic gate valves. The beam dump is common with loop beamline but is considered a separate volume due to geometry and requirements. Vacuum in the 5-cell SRF cavity is maintained in the {approx}10{sup -9} torr range at room temperature by two 20 l/s ion pumps and in the e-gun SRF cavity by one 60 l/s ion pump. Vacuum in the SRF cavities operated at 2{sup o}K is reduced to low 10{sup -11} torr via cryopumping of the cavity walls. The cathode of the e-gun must be protected from poisoning, which can occur if vacuum adjacent to the e-gun in the injection line exceeds 10-11 torr range in the injection warm beamline near the e-gun exit. The vacuum requirements for beam operation in the loop and beam dump are 10-9 torr range. The beamlines are evacuated from atmospheric pressure to high vacuum level with a particulate free, oil free turbomolecular pumping cart. 25 l/s shielded ion pumps distributed throughout the beamlines maintain the vacuum requirement. Due to the more demanding vacuum requirement of the injection beamline proximate to the e-gun, a vacuum bakeout of the injection beamline is required. In addition, two 200 l/s diode ion pumps and supplemental pumping provided by titanium sublimation pumps are installed in the injection line just beyond the exit of the e-gun. Due to expected gas load a similar pumping arrangement is planned for the beam dump. The cryostat vacuum thermally insulating the SRF cavities need only reduce the convective heat load such that heat loss is primarily radiation through several layers of multi-layer insulation and conductive end-losses which are contained by 5{sup o}K thermal transitions. Prior to cool down rough vacuum {approx}10{sup -5} torr range is established and maintained by a dedicated turbomolecular pump station. Cryopumping by the cold mass and heat shields reduces the insulating vacuum to 10{sup -7} torr range after cool down.

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

2010-01-01

381

Dynamic strength of molecularly bonded surfaces  

NASA Astrophysics Data System (ADS)

This study reports a theoretical analysis of the forced separation of two adhesive surfaces linked via a large number of parallel noncovalent bonds. To describe the bond kinetics, we implement a three-state reaction model with kinetic rates obtained from a simple integral expression of the mean first passage time for diffusive barrier crossing in a pulled-distance-dependent potential. We then compute the rupture force for the separation of adhesive surfaces at a constant rate. The results correspond well with a Brownian dynamics simulation of the same system. The separation rate relative to the intrinsic relaxation time of the bonds defines three loading regimes and the general dependence of the adhesion on kinetic or thermodynamic parameters of the bonds. In the equilibrium regime, the rupture force asymptotically approaches the equilibrium rupture force, which increases linearly with the equilibrium bond energy. In the near-equilibrium regime, the rupture force increases with the separation rate and increasingly correlates with the bond rupture barrier. In the far-from-equilibrium regime where rebinding is irrelevant, the rupture force varies linearly with the rupture barrier.

Li, Fang; Leckband, Deborah

2006-11-01

382

The vacuum arc centrifuge  

NASA Astrophysics Data System (ADS)

The separation of elements and isotopes by means of rotating magnetized plasma columns using a laser-triggered vacuum arc centrifuge is described. This vacuum arc centrifuge is sustained by the erosion and ionization of the cathode material, thus producing relatively pure, highly ionized, rotating plasma columns of the cathode material. Any solid metal, or mixture of metals, can be converted into plasma, and the constituent isotopes partially separated in the centrifuge, by fabricating the arc cathode out of the desired metals. The device also offers the possibility of operation with nonconducting solid elements or compounds by imbedding the desired substance in a conducting matrix. A wide variety of metals and combinations of metals were studied, ranging from C through Cu to Cd/Sn. Typical angular rotation frequencies of approx. 100,000 rad/sec were measured, with concomitant enrichments up to a factor of two for Cu 65. The device in its present form is not a viable source of partially enriched stable isotopes at a competitive cost.

Krishnan, M.; Hirshfield, J. L.

383

The LHC Vacuum System  

E-print Network

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 1.9 K and therefore a very good cryopump. To reduce the cryogeni c power consumption, the heat load from synchrotron radiation and from the image currents in the vacuum chamber will be absorbed on a 'beam screen', which operates between 5 and 20 K, inserted in the magnet cold bore. The design pressure necessary for operation must provide a lifetime of several days and a further stringent requirement comes from the power deposition in the superconducting magnet coils due to protons scattered on the residual gas which could lead to a magnet quench. Cryopumping of gas on the cold surfaces provides the necessary low gas densities but it must be ensured that the vapour pressure of cr...

Grbner, Oswald

1998-01-01

384

LHC vacuum system  

E-print Network

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 inner 'cold bore' walls of the magnets. These magnets operate at 1.9 K, and thus serve as very good cryo-pumps. In order to reduce the cryogenic power consumption, both the heat load from synchrotron radiation emitted by the proton beams and the resistive power dissipation by the beam image currents have to be absorbed on a 'beam screen', which operates between 5 and 20 K and is inserted inside the vacuum chamber. The design of this beam screen represents a technological challenge in view of the numerous and often conflicting requirements and the very tight mechanical tolerances imposed. The synchrotron radiation produces strong outgassing from the...

Grbner, Oswald

1999-01-01

385

Vacuum system of the cyclotrons in VECC, Kolkata  

SciTech Connect

The vacuum system of the K=130 Room Temperature Cyclotron (RTC) (operational since 1978) has been recently modernized and the same of the K{sub bend}=520 Superconducting Cyclotron (SCC), currently under commissioning, is being deployed for remote monitoring and control. The vacuum system of RTC is designed to achieve and maintain vacuum level of 2 X 10{sup -6} mbar inside 23 m{sup 3} volume of Resonator tank and DEE tank. This has been upgraded by replacing several valves, Freon units, gauges and pumps. The relay based manual control system has been replaced by PLC based automated system. The SCC vacuum system also has an elaborate arrangement comprising of turbo molecular pumping modules with associated isolation valves and characteristic gauges. This paper describes essential elements, typically used to obtain high (1X10{sup -7} mbar) vacuum using rotary pumps, diffusion pumps and cold traps/turbo-molecular pumps and other system components such as valves, gauges and baffles. The supervisory control methodology/scheme of both the vacuum systems, developed in-house using EPICS (Experimental Physics and Industrial Control System), a standard open-source software tool for designing distributed control system, is also elaborated here. (author)

Roy, Anindya; Bhole, R.B.; Akhtar, J.; Yadav, R.C.; Pal, Sarbajit; Sarkar, D.; Bhandari, R.K., E-mail: r_ani@vecc.gov.in, E-mail: rbb@vecc.gov.in, E-mail: javed@vecc.gov.in, E-mail: yadav@vecc.gov.in, E-mail: sarbajit@vecc.gov.in, E-mail: dsarkar@vecc.gov.in, E-mail: bhandari@vecc.gov.in [Variable Energy Cyclotron Centre, Kolkata (India)

2011-07-01

386

Vacuum disconnectors an application study  

Microsoft Academic Search

The ageing of vacuum interrupters with combined functions of disconnector and circuit-breaker or switch is studied for compact shielded solid insulated switchgear. Different prototypes are manufactured to investigate the influence of contact materials and contact designs. A test program is presented that realistically represents the ageing as described in the standards. The feasibility to create vacuum disconnecting circuit-breakers, vacuum switch-disconnectors

H. Schellekens; T. Shioiri; M. Homma; P. Picot; K. Sasage; D. Mazzucchi

2010-01-01

387

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

388

Four-year Water Degradation of Total-etch Adhesives Bonded to Dentin  

Microsoft Academic Search

Resin-dentin bonds degrade over time. The objective of this study was to evaluate the influence of variables like hybridization effectiveness and diffusion\\/elution of interface components on degradation. Hypotheses tested were: (1) There is no difference in degradation over time between two-and three-step total-etch adhesives; and (2) a composite-enamel bond protects the adjacent composite-dentin bond against degradation. The micro-tensile bond strength

J. De Munck; B. Van Meerbeek; Y. Yoshida; S. Inoue; M. Vargas; K. Suzuki; P. Lambrechts; G. Vanherle

2003-01-01

389

Bonded semiconductor substrate  

DOEpatents

Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600.degree. C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.

Atwater, Jr.; Harry A. (South Pasadena, CA), Zahler; James M. (Pasadena, CA)

2010-07-13

390

Low partial discharge vacuum feedthrough  

NASA Technical Reports Server (NTRS)

Relatively discharge free vacuum feedthrough uses silver-plated copper conductor jacketed by carbon filled silicon semiconductor to reduce concentrated electric fields and minimize occurrence of partial discharge.

Benham, J. W.; Peck, S. R.

1979-01-01

391

Vacuum insulation on the moon  

NASA Astrophysics Data System (ADS)

This paper presents recent concepts and analysis on vacuum insulation issues in the lunar environment, including dust initiated breakdown, thermal management, gas contamination, and solar radiation effects.

Gordon, Lloyd B.; Gaustad, Krista L.

1994-05-01

392

Cu-Cu direct bonding achieved by surface method at room temperature  

SciTech Connect

The metal bonding is a key technology in the processes for the microelectromechanical systems (MEMS) devices and the semiconductor devices to improve functionality and higher density integration. Strong adhesion between surfaces at the atomic level is crucial; however, it is difficult to achieve close bonding in such a system. Cu films were deposited on Si substrates by vacuum deposition, and then, two Cu films were bonded directly by means of surface activated bonding (SAB) at room temperature. The two Cu films, with the surface roughness Ra about 1.3nm, were bonded by using SAB at room temperature, however, the bonding strength was very weak in this method. In order to improve the bonding strength between the Cu films, samples were annealed at low temperatures, between 323 and 473 K, in air. As the result, the Cu-Cu bonding strength was 10 times higher than that of the original samples without annealing.

Utsumi, Jun [Advanced Technology Research Center, Mitsubishi Heavy Industries, Ltd., 1-8-1 Sachiura, Kanazawa-ku, Yokohama 236-8515 (Japan); Ichiyanagi, Yuko, E-mail: yuko@ynu.ac.jp [Department of Physics, Graduate School of Engineering, Yokohama National University, Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan)

2014-02-20

393

Chemical bonding technology  

NASA Technical Reports Server (NTRS)

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 status of the program is described along with the progress toward developing two general purpose primers for ethylene vinyl acetate (EVA), one for glass and metals, and another for plastic films.

Plueddemann, E.

1986-01-01

394

Energy pulse bonding  

NASA Technical Reports Server (NTRS)

To eliminate many of the present termination problems a technique called energy pulse bonding (EPB) was developed. The process demonstrated the capability of: (1) joining conductors without prior removal of insulations, (2) joining conductors without danger of brittle intermetallics, (3) increased joint temperature capability, (4) simultaneous formation of several bonds, (5) capability of higher joint density, and (6) a production oriented process. The following metals were successfully bonded in the solid state: copper, beryllium copper, phosphor bronze, aluminum, brass, and Kovar.

Smith, G. C.

1972-01-01

395

Ti Diffusion in Pyroxene  

NASA Astrophysics Data System (ADS)

Diffusion of titanium has been characterized in natural enstatite and diopside under buffered conditions and in air. The sources of diffusant for the enstatite experiments were mixtures of Mg, Si and Ti oxide powders, which were combined and heated at 1300C overnight, and then thoroughly mixed with synthesized enstatite powder and heated for an additional day at 1300C. Sources for diopside experiments were prepared similarly, using Ca, Mg, Si, and Ti oxide powders combined with synthesized diopside powder, with heating of source materials at 1200C. Buffered experiments were prepared by enclosing source material and pyroxene (polished and pre-annealed under conditions comparable to those to be experienced in the experiment) in AgPd or platinum capsules, placing the metal capsule in a silica glass capsule with a solid buffer (to buffer at NNO or IW) and sealing the assembly under vacuum. Some experiments on enstatite were run in air; sample and source were placed in Pt capsules and crimped shut. Prepared capsules were then annealed in 1 atm furnaces for times ranging from 8 hours to a few months, at temperatures from 950 to 1200C. The Ti distributions in the pyroxene were profiled with Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for Ti diffusion in a natural enstatite, for diffusion normal to the (210) cleavage face (950 - 1150C, experiments run in air): DTi = 1.910-10 exp(-300 44 kJ mol-1/RT) m2 sec-1. Diffusion under NNO and IW-buffered conditions is similar to that for experiments run in air, suggesting little dependence of Ti diffusion on oxygen fugacity. There is also little evidence of anisotropy, as diffusion normal to (001) does not differ significantly from diffusion for the other orientation. Preliminary findings for Ti diffusion in diopside suggest diffusivities similar to those for enstatite. Ti diffusivities in enstatite are similar to those of the trivalent REEs (Cherniak and Liang, 2007), but more than two orders of magnitude slower than those of Fe-Mg (ter Heege et al., 2006) and Cr (Ganguly et al., 2007). These respective variations may reflect the interplay of cation size and charge, or may point to the substitution of Ti on the tetrahedral site. Measurements of diffusion under a broader range of conditions and for other high field strength elements are underway to better interpret these findings. Major and trace element zoning in pyroxenes have been observed in residual peridotites and mafic cumulates. The large differences in cation mobility among Ti, Cr, and Fe-Mg in pyroxene may allow us to distinguish the dominant process that gives rise to the chemical disequilibria. In contrast to those produced by subsolidus reequilibration during cooling, the apparent diffusive boundary layer thicknesses as measured by major and trace elements in a pyroxene grain are not sensitive to the respective cation diffusion rates if zoning is produced by magmatic processes that involves dissolution- precipitation. Examples of zoning in pyroxenes produced by magmatic and subsolidus processes will be discussed. Ganguly et al. (2007) GCA 71, 3915-3925; ter Heege et al. (2006) Eos Trans. AGU 87, Fall Mtg. Suppl. MR21A-0004; Cherniak and Liang (2007) GCA 71, 1324-1340

Cherniak, D.; Liang, Y.

2008-12-01

396

Teachers' Domain: Covalent Bonding  

NSDL National Science Digital Library

This Flash interactive tutorial explores covalent bonding, a type of chemical bond that involves sharing of electrons. Learners investigate the attractive and repulsive forces that act on atomic particles and how the sharing of electrons can keep atoms together. See how two hydrogen atoms interact with each other to create a covalent bond. Learn about patterns in the periodic table and how electrostatic potential energy determines the bond length. Teachers' Domain is a growing collection of more than 1,000 free educational resources compiled by researchers and experienced teachers to promote the use of digital resources in the classroom.

2011-08-16

397

Hydrogen bonding and anaesthesia  

NASA Astrophysics Data System (ADS)

General anaesthetics act by perturbing intermolecular associations without breaking or forming covalent bonds. These associations might be due to a variety of van der Waals interactions or hydrogen bonding. Neurotransmitters all contain OH or NH groups, which are prone to form hydrogen bonds with those of the neurotransmitter receptors. These could be perturbed by anaesthetics. Aromatic rings in amino acids can act as weak hydrogen bond acceptors. On the other hand the acidic hydrogen in halothane type anaesthetics are weak proton donors. These two facts together lead to a probable mechanism of action for all general anaesthetics.

Sndorfy, C.

2004-12-01

398

Mg self-diffusion in pyrope garnet  

Microsoft Academic Search

Mg self-diffusion coefficients were experimentally determined for natural pyrope-alman- dine garnet in a I atm CO-C02 gas-mixing furnace at temperatures of 800-1000 DC. Diffusion couples consist of polished garnet crystals covered with a thin film of enriched stable-isotope oxide produced by high-vacuum thermal evaporation of 25MgO. Experi- ments conducted at quartz + fayalite + magnetite f02 provide 25Mgdiffusion coefficients as

CRAIG S. ScHWANDT; HENRY R. WESTRICH

399

Bonding and Sealing Evaluations for Cryogenic Tanks  

NASA Technical Reports Server (NTRS)

Several different cryogenic tank concepts are being considered for reusable launch vehicles (RLV'S) . Though different tank concepts are being considered, many will require that the cryogenic insulation be evacuated and be bonded to a structure. In this work, an attempt was made to evaluate the effectiveness of maintaining a vacuum on a specimen where foam or honeycomb core was encased within Gr/Ep. In addition to these tests, flatwise adhesion pull off tests were performed at room temperature with PR 1664, EA 9394, FM-300, Crest 3170, and HT 435 adhesives. The materials bonded included Gr/Ep, Gr/BMI, Al, and stainless steel facesheets, and Ti honeycomb, Hexcel honeycomb, and Rohacell foam core materials.

Glass, David E.

1997-01-01

400

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.

401

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

402

Vacuum Gas Tungsten Arc Welding  

NASA Technical Reports Server (NTRS)

A two-year program investigated vacuum gas tungsten arc welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. After a vacuum chamber and GTAW power supply were modified, several difficult-to-weld materials were studied and key parameters developed. Finally, Incoloy 903 weld overlays were produced without microfissures.

Weeks, J. L.; Todd, D. T.; Wooten, J. R.

1997-01-01

403

Braneworld dynamics with vacuum polarization  

E-print Network

We investigate the cosmological dynamics of a brane Universe when quantum corrections from vacuum polarization are taken into account. New vacuum de Sitter points existing on Randall-Sundrum brane are described. We show also that quantum correction can destroy the DGP de Sitter solution on induced gravity brane.

A. V. Toporensky; P. V. Tretyakov

2005-12-15

404

Vacuum Enhanced Cutaneous Biopsy Instrument  

SciTech Connect

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

1999-06-25

405

Detecting leaks in vacuum bags  

NASA Technical Reports Server (NTRS)

Small leaks in vacuum bag can be readily detected by eye, using simple chemical reaction: combination of ammonia and acetic acid vapors to produce cloudy white smoke. Technique has been successfully used to test seam integrity and to identify minute pinholes in vacuum bag used in assembly of ceramic-tile heat shield for Space Shuttle Orbiter.

Carlstrom, E. E.

1980-01-01

406

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

407

On simplicity of vacuum modules  

Microsoft Academic Search

We find necessary and sufficient conditions of irreducibility of vacuum modules over affine Lie algebras and superalgebras. From this we derive conditions of simplicity of minimal W-algebras. Moreover, in the case of the Virasoro and NeveuSchwarz algebras we obtain explicit formulas for the vacuum determinants.

Maria Gorelik; Victor Kac

2007-01-01

408

Purifying Aluminum by Vacuum Distillation  

NASA Technical Reports Server (NTRS)

Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.

Du Fresne, E. R.

1985-01-01

409

Statistical mechanics of the vacuum  

E-print Network

The vacuum is full of virtual particles which exist for short moments of time. In this paper we construct a chaotic model of vacuum fluctuations associated with a fundamental entropic field that generates an arrow of time. The dynamics can be physically interpreted in terms of fluctuating virtual momenta. This model leads to a generalized statistical mechanics that distinguishes fundamental constants of nature.

Christian Beck

2011-12-07

410

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

411

??????????????????????????????????????????? Vacuum Cooling Process of Lettuce  

Microsoft Academic Search

The aim of this research work is to study the moisture and the temperature variation of lettuce under vacuum cooling processes. The experiment was carried out in a rectangular vacuum chamber having a volume of 0.036 m3. The experimental results showed that the cooling rate at the first stage of running was considerably high. the chamber temperature profile during the

Phanlop Saranyachoet; Naris Pratinthong; Thanit Swasdisevi

412

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

2006-04-01

413

Interfacial bonding stability  

NASA Technical Reports Server (NTRS)

Interfacial bonding stability by in situ ellipsometry was investigated. It is found that: (1) gamma MPS is an effective primer for bonding ethylene vinyl acetate (EVA) to aluminum; (2) ellipsometry is an effective in situ technique for monitoring the stability of polymer/metal interfaces; (3) the aluminized back surface of silicon wafers contain significant amounts of silicon and may have glass like properties.

Boerio, J.

1984-01-01

414

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

415

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

416

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.

417

Interactive Pi Bonding Effects  

NSDL National Science Digital Library

This application demonstrates the effect of pi bonding on the one-electron ligand field splitting in an octahedral. By clicking on the appropriate buttons students can see how D changes when you move from ligands with no pi bonding capability to pi donor and pi acceptor ligands.

418

Vacuum energy as dark matter  

NASA Astrophysics Data System (ADS)

We consider the vacuum energy of massive quantum fields in an expanding universe. We define a conserved renormalized energy-momentum tensor by means of a comoving cutoff regularization. Using exact solutions for de Sitter space-time, we show that in a certain range of mass and renormalization scales there is a contribution to the vacuum energy density that scales as nonrelativistic matter and that such a contribution becomes dominant at late times. By means of the WKB approximation, we find that these results can be extended to arbitrary Robertson-Walker geometries. We study the range of parameters in which the vacuum energy density would be compatible with current limits on dark matter abundance. Finally, by calculating the vacuum energy in a perturbed Robertson-Walker background, we obtain the speed of sound of density perturbations and show that the vacuum energy density contrast can grow on sub-Hubble scales as in standard cold dark matter scenarios.

Albareti, F. D.; Cembranos, J. A. R.; Maroto, A. L.

2014-12-01

419

Wood Bond Testing  

NASA Technical Reports Server (NTRS)

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

420

Shape Bonding method  

NASA Technical Reports Server (NTRS)

The present invention is directed to a method of bonding at least two surfaces together. The methods step of the present invention include applying a strip of adhesive to a first surface along a predefined outer boundary of a bond area and thereby defining a remaining open area there within. A second surface, or gusset plate, is affixed onto the adhesive before the adhesive cures. The strip of adhesive is allowed to cure and then a second amount of adhesive is applied to cover the remaining open area and substantially fill a void between said first and second surfaces about said bond area. A stencil may be used to precisely apply the strip of adhesive. When the strip cures, it acts as a dam to prevent overflow of the subsequent application of adhesive to undesired areas. The method results in a precise bond area free of undesired shapes and of a preferred profile which eliminate the drawbacks of the prior art bonds.

Pontius, James T. (Inventor)

2010-01-01

421

Vacuum ultraviolet photoionization of carbohydrates and nucleotides  

SciTech Connect

Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5{sup ?}-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2nm photons are associated with endocyclic CC and CO ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results.

Shin, Joong-Won, E-mail: jshin@govst.edu [Division of Science, Governors State University, University Park, Illinois 60484-0975 (United States) [Division of Science, Governors State University, University Park, Illinois 60484-0975 (United States); Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872 (United States); Bernstein, Elliot R., E-mail: erb@lamar.colostate.edu [Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872 (United States)

2014-01-28

422

Vacuum ultraviolet photoionization of carbohydrates and nucleotides  

NASA Astrophysics Data System (ADS)

Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5'-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C-C and C-O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results.

Shin, Joong-Won; Bernstein, Elliot R.

2014-01-01

423

Cleaning of a thermal vacuum chamber with shrouds in place  

NASA Technical Reports Server (NTRS)

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 required for the shroud removal was also of concern. These concerns prompted us to attempt to clean the chamber without removing the shrouds.

Bond, William R.

1992-01-01

424

Thermal analysis of vacuum-shield multilayer insulation  

Microsoft Academic Search

A method is presented for calculating heat transfer in vacuum-shield multilayer thermal insulation, taking into account the interaction of the radiation and molecules with the heat-sensing surfaces of the system within the framework of a specular-diffuse reflection model. An arbitrary number of coaxial cylindrical (or concentric spherical) bodies is considered, the length of the bodies being much greater than the

S. S. Filimonov; B. A. Khrustalev; I. M. Mazilin

1981-01-01

425

Influence of process parameters on microstructure of transient liquid phase bonded Inconel 738LC superalloy with Amdry DF3 interlayer  

Microsoft Academic Search

The effect of bonding temperature and time on microstructure of diffusion brazed joint of nickel base superalloy Inconel 738LC using Amdry DF-3 filler, alloy was investigated. It was observed that the formation of eutectic microconstituents, within the joint regions, was significantly influenced by the brazing temperature and time. A deviation from the conventional transient liquid phase (TLP) bonding diffusion models

N. P. Wikstrom; O. A. Ojo; M. C. Chaturvedi

2006-01-01

426

Invisibility cloaking in the diffusive-light limit (presentation video)  

NASA Astrophysics Data System (ADS)

Albert Einstein's theory of relativity imposes stringent limitations to making macroscopic objects invisible with respect to electromagnetic light waves propagating in vacuum. These limitations are not relevant though for propagation of light in diffusive media like fog or milk because the effective energy speed is significantly lower than in vacuum due to multiple scattering events. Here, by exploiting the close mathematical analogy between the electrostatic or near-field limit of optics on the one hand and light diffusion on the other hand, we design, fabricate, and characterize simple core-shell cloaking structures for diffusive light propagation in cylindrical and spherical geometry.

Schittny, Robert; Kadic, Muamer; Wegener, Martin

2014-09-01

427

Vacuum phenomenon: Clinical relevance.  

PubMed

Vacuum phenomenon (VP) is an anatomical entity of potential confusion in the diagnosis and evaluation of joint pathology. Observation of this phenomenon has been demonstrated on basic radiographs, computed tomography, and magnetic resonance imaging. Although VP is most often associated with degenerative joint disease, it is observed with other pathologies. Two problematic scenarios can occur: a false-positive diagnosis of serious pathology instead of benign VP and a false-negative diagnosis of benign VP with a more serious underlying process Despite this potential for confusion, criteria for distinguishing VP from other causes of joint pain and for evaluating a suspected case of VP have not been fully established. We reviewed the literature to determine underlying mechanism, symptomology, associated pathologies, and clinical importance of VP. The formation of VP can be explained by gas solubility, pressure-volume relationships, and human physiology. CT, GRE-MRI, and multipositional views are the best imaging studies to view VP. Although most cases of VP are benign, it can be associated with clinical signs and symptoms. VP outside the spine is an underreported finding on imaging studies. VP should be on the differential diagnosis for joint pain, especially in the elderly. We have proposed criteria for diagnosing VP and generated a basic algorithm for its workup. Underreporting of this phenomenon shows a lack of awareness of VP on the part of physicians. By identifying true anatomic VP, we can prevent harm from suboptimal treatment of patients. PMID:24288359

Gohil, Ishan; Vilensky, Joel A; Weber, Edward C

2014-04-01

428

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

429

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

430

Precooler Ring Vacuum System  

SciTech Connect

The precooler vacuum system, as proposed by FNAL, is based on a suitable modification of the existing Electron Cooling Ring System. Because of the magnetic cycle of the bending magnets, distributed ion pumping, as exists in the Electron Cooling Ring, is not applicable. Instead, the proposed pumping will be done with commercial appendage ion pumps mounted approximately every two meters around the circumference of the ring. The loss of effective pumping speed and non-uniformity of system pressure with appendage pumps may not be major considerations but the large number required does effect experimental and analytical equipment placement considerations. There is a distributed pumping technique available which: (1) is not affected by the magnetic cycle of the bending magnets; (2) will provide a minimum of four times the hydrogen pumping speed of the proposed appendage ion pumps; (3) will require no power during pumping after the strip is activated; (4) will provide the heat source for bakeout; (5) is easily replaceable; and (6) can be purchased, installed, and operated at a generous economic advantage over the presently proposed ion pumped system. The pumping technique referred to is non-evaporable gettering with ST101 Zr/Al pumping strip. A technical description of this pumping strip is given on Data Sheet 1 and 2 attached to this report.

Moenich, J.

1980-10-02

431

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

432

Diffusion tube  

NASA Technical Reports Server (NTRS)

The diffusion tube was designed to operate below about 0.25 percent of water supersaturation. It is simply a long tube lined on the inside with a damp chamois cloth, and heated isothermally to a few degrees centigrade above the incoming air. The diffusion coefficient for water vapor is slightly larger than that for heat, making it possible to supersaturate the airflow. This is the same principle by which transient supersaturations may occur in parallel plate cloud chambers. Only the diffusion of vapor and heat from the walls into the moving air are considered.

Leaitch, R.; Megaw, W. J.

1981-01-01

433

Vacuum energy and cosmological evolution  

E-print Network

An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary description of a true dynamical vacuum energy variable that is evolving from the inflationary epoch to the present day. We can compare the evolving vacuum energy with a Casimir device where the parallel plates slowly move apart ("expand"). The total vacuum energy density cannot be measured, only the effect associated to the presence of the plates, and then also their increasing separation with time. In the universe there is a nonvanishing spacetime curvature $R$ as compared to Minkowskian spacetime that is changing with the expansion. The vacuum energy density must change accordingly, and we naturally expect $\\delta\\Lambda\\sim R\\sim H^2$. A class of dynamical vacuum models that trace such rate of change can be constructed. They are compatible with the current cosmological data, and conveniently extended can account for the complete cosmic evolution from the inflationary epoch till the present days. These models are very close to the $\\Lambda$CDM model for the late universe, but very different from it at the early times. Traces of the inherent vacuum dynamics could be detectable in our recent past.

Joan Sola

2014-02-27

434

Vacuum Brazing of Accelerator Components  

NASA Astrophysics Data System (ADS)

Commonly used materials for accelerator components are those which are vacuum compatible and thermally conductive. Stainless steel, aluminum and copper are common among them. Stainless steel is a poor heat conductor and not very common in use where good thermal conductivity is required. Aluminum and copper and their alloys meet the above requirements and are frequently used for the above purpose. The accelerator components made of aluminum and its alloys using welding process have become a common practice now a days. It is mandatory to use copper and its other grades in RF devices required for accelerators. Beam line and Front End components of the accelerators are fabricated from stainless steel and OFHC copper. Fabrication of components made of copper using welding process is very difficult and in most of the cases it is impossible. Fabrication and joining in such cases is possible using brazing process especially under vacuum and inert gas atmosphere. Several accelerator components have been vacuum brazed for Indus projects at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore using vacuum brazing facility available at RRCAT, Indore. This paper presents details regarding development of the above mentioned high value and strategic components/assemblies. It will include basics required for vacuum brazing, details of vacuum brazing facility, joint design, fixturing of the jobs, selection of filler alloys, optimization of brazing parameters so as to obtain high quality brazed joints, brief description of vacuum brazed accelerator components etc.

Singh, Rajvir; Pant, K. K.; Lal, Shankar; Yadav, D. P.; Garg, S. R.; Raghuvanshi, V. K.; Mundra, G.

2012-11-01

435

Kissing bonds A kissing bond is adhesively bonded but holds little of the strength usually  

E-print Network

Kissing bonds · A kissing bond is adhesively bonded but holds little of the strength usually weight saving and excellent stress transfer. · The ability to reliably assess defects in adhesive bonds · To develop a non destructive method to assess the integrity of adhesive bonds using pulsed phase thermography

Sóbester, András

436

Wafer-Level Thermocompression Bonds  

E-print Network

Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding without the application of an electric field or complicated pre-bond cleaning procedure. The presence of a ductile ...

Tsau, Christine H.

437

Free radicals created by plasmas cause autohesive bonding in polymers  

SciTech Connect

We find that plasma immersion ion implantation of polymer surfaces enhances their autohesive bond strength when pressed together by more than a factor of five. Both polymerising (CH{sub 4}/O{sub 2}) and nonpolymerising (Ar) plasmas are effective. There is currently no satisfactory theory for predicting this remarkable phenomenon. We propose that free radicals created by the plasma treatment process diffuse to the interface and cause covalent bonds to form. This theory predicts the dependence of bond strength on plasma bias voltage, treatment time, and autohesive process conditions.

Awaja, Firas; McKenzie, David R. [School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia); Zhang Shengnan [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, New South Wales 2006 (Australia); James, Natalie [Cochlear Limited, 14 Mars Road, Lane Cove New South Wales 2066 (Australia)

2011-05-23

438

Diffuse radiation  

NASA Technical Reports Server (NTRS)

A diffuse celestial radiation which is isotropic at least on a course scale were measured from the soft X-ray region to about 150 MeV, at which energy the intensity falls below that of the galactic emission for most galactic latitudes. The spectral shape, the intensity, and the established degree of isotropy of this diffuse radiation already place severe constraints on the possible explanations for this radiation. Among the extragalactic theories, the more promising explanations of the isotropic diffuse emission appear to be radiation from exceptional galaxies from matter antimatter annihilation at the boundaries of superclusters of galaxies of matter and antimatter in baryon symmetric big bang models. Other possible sources for extragalactic diffuse gamma radiation are discussed and include normal galaxies, clusters of galaxies, primordial cosmic rays interacting with intergalactic matter, primordial black holes, and cosmic ray leakage from galaxies.

1981-01-01

439

New Phases of Hydrogen-Bonded Systems at Extreme Conditions  

SciTech Connect

We study the behavior of hydrogen-bonded systems under high-pressure and temperature. First principle calculations of formic acid under isotropic pressure up to 70 GPa reveal the existence of a polymerization phase at around 20 GPa, in support of recent IR, Raman, and XRD experiments. In this phase, covalent bonding develops between molecules of the same chain through symmetrization of hydrogen bonds. We also performed molecular dynamics simulations of water at pressures up to 115 GPa and 2000 K. Along this isotherm, we are able to define three different phases. We observe a molecular fluid phase with superionic diffusion of the hydrogens for pressure 34 GPa to 58 GPa. We report a transformation to a phase dominated by transient networks of symmetric O-H hydrogen bonds at 95-115 GPa. As in formic acid, the network can be attributed to the symmetrization of the hydrogen bond, similar to the ice VII to ice X transition.

Manaa, M R; Goldman, N; Fried, L E

2006-10-23

440

Junk-Bond Colleges.  

ERIC Educational Resources Information Center

Describes how a long-predicted decline in the fortunes of small private colleges is beginning to show up in the bond market, as the number of colleges now rated in the junk category has nearly doubled. (EV)

Van Der Werf, Martin

2003-01-01

441

Gold Thermocompression Wafer Bonding  

E-print Network

Thermocompression bonding of gold is a promising technique for the fabrication and packaging microelectronic and MEMS devices. The use of a gold interlayer and moderate temperatures and pressures results in a hermetic, ...

Spearing, S. Mark

442

Dynamic Simulation of the Thermal Decomposition of Pyrite Under Vacuum  

NASA Astrophysics Data System (ADS)

The ultrasoft pseudopotential plane wave method is applied to dynamic simulation of the thermal decomposition mechanism of FeS2 under vacuum. The FeS2 (100), (111), and (210) surface relaxation and the geometric and electronic structure of the reactants and products are calculated. The results indicate that FeS2 (100) is the most preferred surface to dissociate and also the most common cleavage surface. The thermal decomposition mechanism of FeS2 is explained by dynamic simulation on a micro stratum: in general, the S-Fe bond gradually elongated until it fractured, the S-S bond strengthened gradually, the S-Fe bond was cleaved to form S, the force is relatively weaker between different layers, and thermal decomposition occurred easily between the layers. Simultaneously, the intermediate products, such as Fe x S y , were formed. Evidence of Fe pyrolysis into Fe metal was not found, and the intermediate products decomposed further. The contributions of the p and d orbitals of Fe increased, whereas that of the s orbital decreased. The contributions of the s and p orbitals of S decreased. The results obtained from FeS2 thermal decomposition experiments under vacuum and differential thermal analysisthermogravimetry are consistent with the results of calculation and simulation.

Deng, Jiushuai; Wen, Shuming; Chen, Xiumin; Xian, Yongjun; Wu, Dandn

2014-05-01

443

Einstein-?tsuki vacuum equations  

NASA Astrophysics Data System (ADS)

The generalisation of the Einstein vacuum theory to ?tsuki geometry is considered. It is shown that the theory based on Lagrangian density ?-gR is consistent and leads to a theory that is classically indistinguishable from the Einstein theory.

Smrz, P. K.

1993-01-01

444

Inhomogeneous and Interacting Vacuum Energy  

NASA Astrophysics Data System (ADS)

Vacuum energy is a simple model for dark energy driving an accelerated expansion of the universe. If the vacuum energy is inhomogeneous in spacetime then it must be interacting. We present the general equations for a spacetime-dependent vacuum energy in cosmology, including inhomogeneous perturbations. We show how any dark energy cosmology can be described by an interacting vacuum+matter. Different models for the interaction can lead to different behaviour (e.g., sound speed for dark energy perturbations) and hence could be distinguished by cosmological observations. As an example we present the cosmic microwave microwave background anisotropies and the matter power spectrum for two different versions of a generalised Chaplygin gas cosmology.

De-Santiago, Josue; Wands, David; Wang, Yuting

445

Vacuum lamination of photovoltaic modules  

NASA Technical Reports Server (NTRS)

Vacuum lamination of terrestrial photovoltaic modules is a new high volume process requiring new equipment and newly develop materials. Equipment development, materials research, and some research in related fields and testing methods are discussed.

Burger, D. R.

1982-01-01

446

Vacuum system pump down analysis  

SciTech Connect

My assignment on the SP-100 Vacuum Vessel Vacuum System Team was to perform a transient pump down analysis for the vacuum vessel that will house the SP-100 reactor during testing. Pump down time was calculated for air and helium. For all cases the proposed vacuum system will be able to pump down the vessel within the required time. The use of a larger rotary piston pump (DUO250) improves the pump down time by 35 minutes and therefore should be considered. The 6-inch duct for the roughing line is optimal, however, because all cases are well below the 24 hour time frame, the 4-inch duct is sufficient. The use of the single turbomolecular pump during pump down is sufficient. A pump down with helium in the vessel and a helium inleakage delays the time to achieve the base pressure marginally and is acceptable.

Rohrdanz, D.R.

1990-08-01

447

Water's Hydrogen Bond Strength  

E-print Network

Water is necessary both for the evolution of life and its continuance. It possesses particular properties that cannot be found in other materials and that are required for life-giving processes. These properties are brought about by the hydrogen bonded environment particularly evident in liquid water. Each liquid water molecule is involved in about four hydrogen bonds with strengths considerably less than covalent bonds but considerably greater than the natural thermal energy. These hydrogen bonds are roughly tetrahedrally arranged such that when strongly formed the local clustering expands, decreasing the density. Such low density structuring naturally occurs at low and supercooled temperatures and gives rise to many physical and chemical properties that evidence the particular uniqueness of liquid water. If aqueous hydrogen bonds were actually somewhat stronger then water would behave similar to a glass, whereas if they were weaker then water would be a gas and only exist as a liquid at sub-zero temperatures. The overall conclusion of this investigation is that water's hydrogen bond strength is poised centrally within a narrow window of its suitability for life.

Martin Chaplin

2007-06-10

448

Pneumatically Actuated Miniature Peristaltic Vacuum Pumps  

NASA Technical Reports Server (NTRS)

Pneumatically actuated miniature peristaltic vacuum pumps have been proposed for incorporation into advanced miniature versions of scientific instruments that depend on vacuum for proper operation. These pumps are expected to be capable of reaching vacuum-side pressures in the torr to millitorr range (from .133 down to .0.13 Pa). Vacuum pumps that operate in this range are often denoted roughing pumps. In comparison with previously available roughing pumps, these pumps are expected to be an order of magnitude less massive and less power-hungry. In addition, they would be extremely robust, and would operate with little or no maintenance and without need for oil or other lubricants. Portable mass spectrometers are typical examples of instruments that could incorporate the proposed pumps. In addition, the proposed pumps could be used as roughing pumps in general laboratory applications in which low pumping rates could be tolerated. The proposed pumps could be designed and fabricated in conventionally machined and micromachined versions. A typical micromachined version (see figure) would include a rigid glass, metal, or plastic substrate and two layers of silicone rubber. The bottom silicone layer would contain shallow pump channels covered by silicone arches that could be pushed down pneumatically to block the channels. The bottom silicone layer would be covered with a thin layer of material with very low gas permeability, and would be bonded to the substrate everywhere except in the channel areas. The top silicone layer would be attached to the bottom silicone layer and would contain pneumatic- actuation channels that would lie crosswise to the pump channels. This version is said to be micromachined because the two silicone layers containing the channels would be fabricated by casting silicone rubber on micromachined silicon molds. The pneumatic-actuation channels would be alternately connected to a compressed gas and (depending on pump design) either to atmospheric pressure or to a partial vacuum source. The design would be such that the higher pneumatic pressure would be sufficient to push the silicone arches down onto the substrates, blocking the channels. Thus, by connecting pneumatic- actuation channels to the two pneumatic sources in spatial and temporal alternation, waves of opening and closing, equivalent to peristalsis, could be made to move along the pump channels. A pump according to this concept could be manufactured inexpensively. Pneumatic sources (compressors and partial vacuum sources) similar those needed for actuation are commercially available; they typically have masses of .100 g and power demands of the order of several W. In a design-optimization effort, it should be possible to reduce masses and power demands below even these low levels and to integrate pneumatic sources along with the proposed pumps into miniature units with overall dimensions of no more than a few centimeters per side.

Feldman, Sabrina; Feldman, Jason; Svehla, Danielle

2003-01-01

449

PREPARATIVE COMPOUND CLASS SEPARATION OF HEAVY OIL VACUUM RESIDUA BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY  

Microsoft Academic Search

An HPLC system is used to separate deasphalted vacuum resids of heavy oils, into saturates, aromatics and two types of resins at preparative scale. The separation is achieved using two silica and one cyano bonded silica columns, and cyclopentane, a mixture of chloroform-methanol and dichleramethane as solvents. Automated repetitive injection is required. Recoveries of the sample are around 100%.

Lante Carbognani; Alejandro Izquierdo

1990-01-01

450

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

451

Vacuum Refining of Molten Silicon  

NASA Astrophysics Data System (ADS)

Metallurgical fundamentals for vacuum refining of molten silicon and the behavior of different impurities in this process are studied. A novel mass transfer model for the removal of volatile impurities from silicon in vacuum induction refining is developed. The boundary conditions for vacuum refining systemthe equilibrium partial pressures of the dissolved elements and their actual partial pressures under vacuumare determined through thermodynamic and kinetic approaches. It is indicated that the vacuum removal kinetics of the impurities is different, and it is controlled by one, two, or all the three subsequent reaction mechanismsmass transfer in a melt boundary layer, chemical evaporation on the melt surface, and mass transfer in the gas phase. Vacuum refining experimental results of this study and literature data are used to study the model validation. The model provides reliable results and shows correlation with the experimental data for many volatile elements. Kinetics of phosphorus removal, which is an important impurity in the production of solar grade silicon, is properly predicted by the model, and it is observed that phosphorus elimination from silicon is significantly increased with increasing process temperature.

Safarian, Jafar; Tangstad, Merete

2012-12-01

452

Fair Scheduling on Parallel Bonded Channels with Intersecting Bonding Groups  

E-print Network

Fair Scheduling on Parallel Bonded Channels with Intersecting Bonding Groups Gongbing Hong, James for providing weighted sharing of aggregate capacity in networks having parallel bonded channels in which a single channel may simultaneously be a member of multiple bonding groups. Our work is motivated

Martin, Jim

453

30 CFR 581.33 - Bonds and bonding requirements.  

Code of Federal Regulations, 2013 CFR

...Resources 2 2013-07-01 2013-07-01 false Bonds and bonding requirements. 581.33 Section 581.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations 581.33 Bonds and bonding requirements. (a) When the leasing notice...

2013-07-01

454

Leave with Pay Bond/Waiver of Bond Form  

E-print Network

Leave with Pay Bond/Waiver of Bond Form Submit to: The Office of Faculty Affairs and Professional Development, ADM 451 I. As you were granted a leave with pay, you must either post a bond in the amount of the salary to be paid during the leave or be granted a waiver of the bond. Most faculty members request

455

30 CFR 281.33 - Bonds and bonding requirements.  

Code of Federal Regulations, 2011 CFR

...Resources 2 2011-07-01 2011-07-01 false Bonds and bonding requirements. 281.33 Section 281.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations 281.33 Bonds and bonding requirements. (a) When the leasing notice...

2011-07-01

456

30 CFR 581.33 - Bonds and bonding requirements.  

Code of Federal Regulations, 2014 CFR

...Resources 2 2014-07-01 2014-07-01 false Bonds and bonding requirements. 581.33 Section 581.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations 581.33 Bonds and bonding requirements. (a) When the leasing notice...

2014-07-01

457

30 CFR 581.33 - Bonds and bonding requirements.  

Code of Federal Regulations, 2012 CFR

...Resources 2 2012-07-01 2012-07-01 false Bonds and bonding requirements. 581.33 Section 581.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations 581.33 Bonds and bonding requirements. (a) When the leasing notice...

2012-07-01

458

30 CFR 281.33 - Bonds and bonding requirements.  

Code of Federal Regulations, 2010 CFR

...Resources 2 2010-07-01 2010-07-01 false Bonds and bonding requirements. 281.33 Section 281.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations 281.33 Bonds and bonding requirements. (a) When the leasing notice...

2010-07-01

459

Wafer-level vacuum/hermetic packaging technologies for MEMS  

NASA Astrophysics Data System (ADS)

An overview of wafer-level packaging technologies developed at the University of Michigan is presented. Two sets of packaging technologies are discussed: (i) a low temperature wafer-level packaging processes for vacuum/hermeticity sealing, and (ii) an environmentally resistant packaging (ERP) technology for thermal and mechanical control as well as vacuum packaging. The low temperature wafer-level encapsulation processes are implemented using solder bond rings which are first patterned on a cap wafer and then mated with a device wafer in order to encircle and encapsulate the device at temperatures ranging from 200 to 390 C. Vacuum levels below 10 mTorr were achieved with yields in an optimized process of better than 90%. Pressures were monitored for more than 4 years yielding important information on reliability and process control. The ERP adopts an environment isolation platform in the packaging substrate. The isolation platform is designed to provide low power oven-control, vibration isolation and shock protection. It involves batch flip-chip assembly of a MEMS device onto the isolation platform wafer. The MEMS device and isolation structure are encapsulated at the wafer-level by another substrate with vertical feedthroughs for vacuum/hermetic sealing and electrical signal connections. This technology was developed for high performance gyroscopes, but can be applied to any type of MEMS device.

Lee, Sang-Hyun; Mitchell, Jay; Welch, Warren; Lee, Sangwoo; Najafi, Khalil

2010-02-01

460

An Investigation of Bonding Mechanism in Metal Cladding by Warm Rolling  

E-print Network

coefficients of aluminum and iron are estimated through experimental method. A thermo-mechanical model was developed to describe the rolling plastic deformation of component metal sheets and the diffusion evolution during a roll bonding process of dissimilar...

Yang, Wei

2012-02-14

461

Space simulation ultimate pressure lowered two decades by removal of diffusion pump oil contaminants during operation  

NASA Technical Reports Server (NTRS)

The complex problem why large space simulation chambers do not realize the true ultimate vacuum was investigated. Some contaminating factors affecting diffusion pump performance have been identified and some advances in vacuum/distillation/fractionation technology have been achieved which resulted in a two decade or more lower ultimate pressure. Data are presented to show the overall or individual contaminating effect of commonly used phthalate ester plasticizers of 390 to 530 molecular weight on diffusion pump performance. Methods for removing contaminants from diffusion pump silicone oil during operation and reclaiming contaminated oil by high vacuum molecular distillation are described.

Buggele, A. E.

1973-01-01

462

Bond Markets with Stochastic Volatility  

E-print Network

Bond Markets with Stochastic Volatility Rafael DeSantiago Jean-Pierre Fouque Knut Sølna September 27, 2007 Abstract We analyze stochastic volatility effects in the context of the bond market- nection to defaultable bonds. Contents 1 Introduction 2 2 Pricing Bonds 3 2.1 The Term Structure Equation

Solna, Knut

463

Acid diffusion through polymer films  

NASA Astrophysics Data System (ADS)

In order to perform 0.2 micrometer processes, one needs to study the diffusion of photoacid generators within the photoresist system, since diffusion during post exposure bake time has an influence on the critical dimension (CD). We have developed a new method to study the diffusion of photoacid generators within a polymer film. This new method is based on monitoring the change of the fluorescence intensity of a pH- sensitive fluorescent dye caused by the reaction with photoacid. A simplified version of this experiment has been conducted by introducing acid vapor to quench the fluorescence intensity of this pH sensor. A thin polymer film is spin cast onto the sensor to create a barrier to the acid diffusion process. During the acid diffusion process, the fluorescence intensity of this pH sensor is measured in situ, using excitation and emission wavelengths at 466 nm and 516 nm, respectively. Fluoresceinamine, the pH sensitive fluorescent dye, is covalently bonded onto the treated quartz substrate to form a single dye layer. Poly(hydroxystyrene) (Mn equals 13k, Tg equals 180 degrees Celsius) in PGMEA (5% - 18% by weight) is spin cast onto this quartz substrate to form films with varying thickness. The soft bake time is 60 seconds at 90 degrees Celsius and a typical film has a thickness of 1.4 micrometers. Trifluoroacetic acid is introduced into a small chamber while the fluorescence from this quartz window is observed. Our study focuses on finding the diffusion constant of the vaporized acid (trifluoroacetic acid) in the poly(hydroxystyrene) polymer film. By applying the Fick's second law, (It - Io)/(I(infinity ) - Io) equals erfc [L/(Dt)1/2] is obtained. The change of fluorescence intensity with respect to the diffusion time is monitored. The above equation is used for the data analysis, where L represents the film thickness and t represents the average time for the acid to diffuse through the film. The diffusion constant is calculated to be at the order of 10-10 cm2/s to 10-12 cm2/s. All the experiments are conducted at room temperature and are valid only for acid vapor. With different film thickness, it was found that the acid diffuses through the film with a similar diffusion constant. The diffusion is faster with increased solvent residue in the film (controlled by spin coating speed). The theoretical computer modeling of the local acid concentration with respect to acid diffusion is also performed.

Zhang, P. Linda; Eckert, Andrew R.; Willson, C. Grant; Webber, Stephen E.; Byers, Jeffrey D.

1997-07-01

464

Antibacterial activity of dentinal bonding agents.  

PubMed

The susceptibility of five bacterial species to seven dentinal bonding agents was examined in vitro. Agar diffusion tests using filterpaper disks containing 10 microL each of conditioner, primer, or resin were performed on blood agar and mitis salivarius bacitracin agar. Chlorhexidine (0.2%) was used as a positive control. After incubation, zones of inhibited bacterial growth were measured. Of all the compounds tested, Gluma cleanser and Gluma etchant showed the strongest growth inhibition for all bacterial strains. No antibacterial effect was noted for Prisma Universal Bond 2 and Superlux Universal Bond 2 systems. The primers of Gluma, Denthesive, and Scotchbond 2 displayed antibacterial activity that, in some cases, was comparable to that of 0.2% chlorhexidine. Zones of inhibition were seen for the resin materials of Scotchbond 2 and Tripton with Streptococcus mutans, Streptococcus sanguis and Actinomyces viscosus. No inhibition was seen after these resins were cured, whereas the antibacterial effect of XR-Bond on S sanguis and A viscosus was not affected by light curing. PMID:8210322

Emilson, C G; Bergenholtz, G

1993-07-01

465

Surface analysis in composite bonding  

NASA Technical Reports Server (NTRS)

The role of the interfacial region in determining the bond strength and durability of composite bonds is discussed. The characterization of a variety of carbon fibers including Celion 6000 using both scanning electron microscopy and X-ray photoelectron spectroscopy is discussed. The emphasis is on composite bonding, that is, the adhesive bonding between composites in contrast to fiber-matrix interaction. The primary objective of the research is the characterization of composite surfaces before adhesive bonding and after fracture of bonded specimens. Work done on the analysis of composite samples pretreated in a number of ways prior to bonding is detailed.

Messick, D. L.; Wightman, J. P.

1982-01-01

466

Unstable, metastable, or stable halogen bonding interaction involving negatively charged donors? A statistical and computational chemistry study.  

PubMed

The noncovalent halogen bonding could be attributed to the attraction between the positively charged ?-hole and a nucleophile. Quantum mechanics (QM) calculation indicated that the negatively charged organohalogens have no positively charged ?-hole on their molecular surface, leading to a postulation of repulsion between negatively charged organohalogens and nucleophiles in vacuum. However, PDB survey revealed that 24% of the ligands with halogen bonding geometry could be negatively charged. Moreover, 36% of ionizable drugs in CMC (Comprehensive Medicinal Chemistry) are possibly negatively charged at pH 7.0. QM energy scan showed that the negatively charged halogen bonding is probably metastable in vacuum. However, the QM calculated bonding energy turned negative in various solvents, suggesting that halogen bonding with negatively charged donors should be stable in reality. Indeed, QM/MM calculation on three crystal structures with negatively charged ligands revealed that the negatively charged halogen bonding was stable. Hence, we concluded that halogen bonding with negatively charged donors is unstable or metastable in vacuum but stable in protein environment, and possesses similar geometric and energetic characteristics as conventional halogen bonding. Therefore, negatively charged organohalogens are still effective halogen bonding donors for medicinal chemistry and other applications. PMID:25390886

Yang, Zhuo; Xu, Zhijian; Liu, Yingtao; Wang, Jinan; Shi, Jiye; Chen, Kaixian; Zhu, Weiliang

2014-12-11

467

Shear bond strength of four orthodontic bonding systems.  

PubMed

Recently new orthodontic bonding systems have been developed for attachment of brackets to the etched facial surfaces of teeth. Two of these new systems use bonding agents that contain solvents. It is claimed that this improves the polymerization of the unfilled resin primer and may increase bond strength. A new light-cured restorative enamel/dentin-bonding agent has also recently been introduced. Its value in orthodontic bonding has not been determined. The aim of this investigation was to evaluate the shear bond strengths of the three new bonding systems and to compare these with a conventional orthodontic bonding system. Forty-eight enamel specimens were prepared with 600-grit silicone carbide paper, acid etched with 37% phosphoric acid, and assigned to four enamel-bonding treatment groups: (A) Saga sealant; (B) Maximum Cure; (C) Scotchbond-2; and (D) Concise enamel bond. After enamel priming, the specimens were bonded to Concise orthodontic bonding resin. The bonded specimens were thermocycled (15 degrees C to 45 degrees C) and then stored in distilled water at 37 degrees C for 7 days. Shear bond strength was tested with an Instron testing machine at a strain rate of 0.02 in/min. The mean shear bond strengths and standard deviations reported in MN/m2 were (A) 20.34 (5.37); (B) 25.33 (5.96); (C) 14.59 (5.25); and (D) 20.13 (4.98). The mean shear bond strengths for groups A, B, and D were significantly greater (p less than 0.05) than that for group C. The addition of solvents to the new orthodontic bonding systems does not appear to have a clinically significant effect. The new restorative bonding resin does not provide comparable enamel bond strengths. PMID:2405634

Coreil, M N; McInnes-Ledoux, P; Ledoux, W R; Weinberg, R

1990-02-01

468

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 2.3510 neutrons per cm. 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

469

Kinetics of scrap tyre pyrolysis under vacuum conditions  

SciTech Connect

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 12 K in the reaction starting temperature. The kinetic constant at 503 K for devolatilization of volatile additives at 0.25 atm is 1.7 times higher than that at 1 atm, and that corresponding to styrene-butadiene rubber at 723 K 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.

Lopez, Gartzen; Aguado, Roberto [Departamento de Ingenieria Quimica, Universidad del Pais Vasco, Apartado 644, 48080 Bilbao (Spain); Olazar, Martin [Departamento de Ingenieria Quimica, Universidad del Pais Vasco, Apartado 644, 48080 Bilbao (Spain)], E-mail: martin.olazar@ehu.es; Arabiourrutia, Miriam; Bilbao, Javier [Departamento de Ingenieria Quimica, Universidad del Pais Vasco, Apartado 644, 48080 Bilbao (Spain)

2009-10-15

470

Insulation bonding test system  

NASA Technical Reports Server (NTRS)

A method and a system for testing the bonding of foam insulation attached to metal is described. The system involves the use of an impacter which has a calibrated load cell mounted on a plunger and a hammer head mounted on the end of the plunger. When the impacter strikes the insulation at a point to be tested, the load cell measures the force of the impact and the precise time interval during which the hammer head is in contact with the insulation. This information is transmitted as an electrical signal to a load cell amplifier where the signal is conditioned and then transmitted to a fast Fourier transform (FFT) analyzer. The FFT analyzer produces energy spectral density curves which are displayed on a video screen. The termination frequency of the energy spectral density curve may be compared with a predetermined empirical scale to determine whether a igh quality bond, good bond, or debond is present at the point of impact.

Beggs, J. M.; Johnston, G. D.; Coleman, A. D.; Portwood, J. N.; Saunders, J. M.; Redmon, J. W.; Porter, A. C. (inventors)

1984-01-01