scholarly journals A Low-Temperature Alumina/Copper Diffusion Bonding Process using La-Doped Titanium Interlayers

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 401 ◽  
Author(s):  
Cherng-Yuh Su ◽  
Jia-Liang Huang ◽  
Po-Chun Chen ◽  
Hsin-Jung Yu ◽  
Dai-Liang Ma ◽  
...  
Keyword(s):  
Low Temperature ◽  
Diffusion Bonding ◽  
Bonding Temperature ◽  
Oxygen Affinity ◽  
Temperature Stability ◽  
High Strength ◽  
High Temperature Stability ◽  
Transmission Electron ◽  
Temperature Diffusion ◽  
La Doped

Ceramic-to-metal heterojunctions have been established to improve high-temperature stability for applications in aerospace and harsh environments. In this work, we employed low-temperature diffusion bonding to realize an alumina/Cu heterogeneous joint. Using a thin layer of lanthanum-doped titanium (La-doped Ti) to metallize the alumina surface, we achieved the bonding at a temperature range of 250–350 °C. We produced a uniform, thermally stable, and high-strength alumina/Cu joint after a hot-press process in vacuum. Signals from X-ray diffraction (XRD) suggested the successful diffusion of Ti and La into the alumina substrate, as Ti can easily substitute Al in alumina, and La has a better oxygen affinity than that of Al. The transmission electron microscopy and XRD results also showed the existence of CuxTiyO phases without CuxTiy or LaOx. In addition, the bonding strength of alumina/copper hot-pressed at 250, 300, and 350 °C were 7.5, 9.8 and 15.0 MPa, respectively. The process developed in this study successfully lowered the bonding temperature for the alumina/copper joint.

UNS R54620

Alloy Digest ◽  
1987 ◽  
Vol 36 (7) ◽  
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Time Use ◽  
Temperature Stability ◽  
High Strength ◽  
Heat Treating ◽  
High Temperature Stability ◽  
Beta Titanium Alloy ◽  
Beta Titanium ◽  
Long Time

Abstract UNS No. R54620 is an alpha-beta titanium alloy. It has an excellent combination of tensile strength, creep strength, toughness and high-temperature stability that makes it suitable for service to 1050 F. It is recommended for use where high strength is required. It has outstanding advantages for long-time use at temperatures to 800 F. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and bend strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ti-86. Producer or source: Titanium alloy mills.

scholarly journals Performance and Microstructure of Cold Recycled Mixes Using Asphalt Emulsion with Different Contents of Cement

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2548 ◽  
Author(s):  
Yanhai Yang ◽  
Ye Yang ◽  
Baitong Qian
Keyword(s):  
Low Temperature ◽  
Temperature Stability ◽  
Hydration Products ◽  
High Temperature Stability ◽  
Asphalt Emulsion ◽  
Moisture Susceptibility ◽  
Pavement Maintenance ◽  
Maintenance And Rehabilitation ◽  
Low Temperature Cracking ◽  
Temperature Crack

Cold recycled mixes using asphalt emulsion (CRME) is an economical and environmentally-friendly technology for asphalt pavement maintenance and rehabilitation. In order to determine the optimum range of cement contents, the complex interaction between cement and asphalt emulsion and the effects of cement on performance of CRME were investigated with different contents of cement. The microstructure and chemical composition of the fracture surface of CRME with different contents of cement were analyzed in this paper as well. Results show that the high-temperature stability and moisture susceptibility of CRME increased with the contents of cement increasing. The low-temperature crack resistance ability gradually increased when the content of cement is increased from 0% to 1.5%. However, it gradually decreased when the content of cement is increased from 1.5% to 4%. Cold recycled mixes had better low-temperature cracking resistance when the contents of cement were in the range from 1% to 2%. The results of microstructure and energy spectrum analysis show that the composite structure is formed by hydration products and asphalt emulsion. The study will be significant to better know the effects of cement and promote the development of CRME.

Characteristics of Different Warm Mix Asphalt Compacted at Low Temperature

2011 ◽  
Vol 255-260 ◽  
pp. 3166-3170
Author(s):  
Li Ming Wang ◽  
Yi Qiu Tan ◽  
Zhen Wu Shi
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Crack Resistance ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Obvious Effect ◽  
Water Sensitivity ◽  
Active Additive ◽  
Surface Active ◽  
Temperature Crack

Additives on low temperature compaction and performances of compacted mixtures, the author devised low temperature environment compaction test, and then, comparison tests of volume parameters, high temperature stability, low temperature crack resistance and water sensitivity were conducted. Tests results showed that the wax additives and the surface-active additive can significantly contribute to mixtures low-temperature compactibility. The wax additive helps to improve high temperature stability obviously, and has no significant contribution to low temperature crack resistance and water sensitivity. The surface-active additive directly reduces water sensitivity, the wax additive indirectly plays the role of reducing water sensitivity by increasing the density of mixture, and the foam additive has no obvious effect on the water sensitivity.

Low Temperature Direct Cu-Cu Immersion Bonding for 3D Integration

2009 ◽  
Vol 1156 ◽  
Author(s):  
Rahul Agarwal ◽  
Wouter Ruythooren
Keyword(s):  
Citric Acid ◽  
Low Temperature ◽  
Bonding Temperature ◽  
Atmospheric Condition ◽  
High Strength ◽  
Bonding Process ◽  
3D Integration ◽  
Temperature And Pressure ◽  
Low Temperature Bonding

AbstractHigh yielding and high strength Cu-Cu thermo-compression bonds have been obtained at temperatures as low as 175°C. Plated Cu bumps are used for bonding, without any surface planarization step or plasma treatment, and bonding is performed at atmospheric condition. In this work the 25μm diameter bumps are used at a bump pitch of 100μm and 40μm. Low temperature bonding is achieved by using immersion bonding in citric acid. Citric acid provides in-situ cleaning of the Cu surface during the bonding process. The daisy chain electrical bonding yield ranges from 84%-100% depending on the bonding temperature and pressure.

Impact of Rheological Properties of Fiber Asphalt Mortar on Mixture Road Performance

2013 ◽  
Vol 734-737 ◽  
pp. 2287-2291 ◽  
Author(s):  
De Dong Guo
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Rheological Properties ◽  
Asphalt Mixture ◽  
Temperature Stability ◽  
Fiber Content ◽  
High Temperature Stability ◽  
Temperature Performance ◽  
Low Temperature Performance ◽  
Asphalt Mortar

Fiber asphalt concrete has been more and more widely used in highway construction. For analyzing high and low temperature performance of fiber asphalt mixture, rheological properties of fiber asphalt mortar were studied through indoor test. Impact of Rheological properties of the fiber asphalt mortar on high temperature and low temperature properties of asphalt mixture was analyzed. Results showed that the larger fiber content was, the better performance of asphalt mixture's high temperature stability, fiber asphalt mortar rut factor and rutting tests results of asphalt mixture were linear correlation, reflecting the high temperature performance of asphalt mixture; With the increase of fiber content, variation of stiffness modulus, creep rate indicators and mixture low temperature performance was consistent, and rheological properties of fiber asphalt mortar could characterize low temperature performance of asphalt mixture.

scholarly journals Study on Laboratory Experimental Pavement Performances of SEAM Modified Asphalt Mixture

2019 ◽  
Vol 136 ◽  
pp. 03010
Author(s):  
Ma Qingna ◽  
Zhao Zhiqin ◽  
Xu Qian ◽  
Sun Feng
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Asphalt Mixture ◽  
Temperature Stability ◽  
Water Stability ◽  
High Temperature Stability ◽  
Modified Asphalt ◽  
The Road ◽  
Road Performance ◽  
Property Index

Adding sulphur dilution asphalt modifier SEAM to asphalt mixture is not only a modifier of asphalt mixture, but also an additive of asphalt mixture. When the modifier is added into the asphalt mixture, the road performance of the asphalt mixture can be improved. This paper studies SEAM modified asphalt mixture the Marshall property index, temperature stability, Water stability and fatigue feature in the Laboratory. On the based of the result of the experiment and analysis, SEAM can improve the high temperature stability, Water stability and fatigue feature. But the low temperature stability can’t improve.

scholarly journals The Mechanism of High-Strength Quenching-Partitioning-Tempering Martensitic Steel at Elevated Temperatures

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 94 ◽  
Author(s):  
Ke Zhang ◽  
Maoyuan Zhu ◽  
Bitong Lan ◽  
Ping Liu ◽  
Wei Li ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Elevated Temperatures ◽  
Martensitic Steel ◽  
Lath Martensite ◽  
Temperature Stability ◽  
High Strength ◽  
High Temperature Stability ◽  
High Deformation ◽  
Heat Treated ◽  
The Relationship

High-strength medium-carbon martensitic steel was heat treated through a quenching-partitioning-tempering (Q-P-T) treatment. Both the mechanism for improved ductility and the high temperature stability of austenite were investigated. The Q-P-T martensitic steel showed good products of strength and elongation (PSE) at various deformation temperatures ranging within 25–350 °C. The optimum PSE value (>57,738 MPa%) was achieved at 200 °C. The microstructure of the Q-P-T steel is constituted of laths martensite with dislocations, retained austenite located within lath martensite and small niobium carbides (NbC), and/or transitional ε-carbides that precipitated in the lath martensite. The good ductility can be mainly attributed to the laminar-like austenite that remained within the lath-martensite. The austenite can effectively enhance ductility through the effect of dislocation absorption by the retained austenite and through transformation-induced plasticity. The relationship between the microstructures and mechanical properties was investigated at high deformation temperatures.

Hexaaluminate Catalysts for Fuel Reforming

2008 ◽  
Author(s):  
Nicholas E. McGuire ◽  
Neal P. Sullivan ◽  
Robert J. Kee ◽  
Huayang Zhu ◽  
James A. Nabity ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Exchange Process ◽  
Catalyst Support ◽  
Temperature Stability ◽  
Metal Exchange ◽  
High Temperature Stability ◽  
Fuel Reforming ◽  
Transmission Electron ◽  
Wide Range ◽  
Hexaaluminate Catalysts

Hexaaluminate catalysts offer excellent high-temperature stability compared to the equivalent metal-based catalysts. Their stability also lends well to use as a catalyst support. However, use of novel hexaaluminates is limited in fuel processing for fuel-cell applications. In this paper, we report on the performance of hexaaluminates as a catalyst support in the steam reforming of methane. The hexaaluminates are synthesized by a metal-exchange process using alumoxane precursors that enable a wide range of metal substitutions. Performance is evaluated using a unique stagnation-flow reactor that enables detailed probing of the boundary layer above the catalyst-impregnated stagnation surface. Experimental results are compared with models to understand fundamental reaction kinetics and optimize catalyst performance. RhSr-substituted hexaaluminates with a Rh impregnation are shown to yield the best performance. Scanning- and Transmission-Electron Microscopy are used to characterize the different types of hexaaluminates, and to examine the effect of aging on catalyst structure.

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