scholarly journals Three-layer structure hot bending/diffusion bonding process of reactive sintering Ti-22Al-25Nb alloy and its load response at high temperature

2021 ◽  
Vol 2011 (1) ◽  
pp. 012076
Author(s):  
YU Long-hai ◽  
Wang Yuan-xin
Keyword(s):  
High Temperature ◽  
Diffusion Bonding ◽  
Layer Structure ◽  
Bonding Process ◽  
Reactive Sintering ◽  
Load Response

Mechanical And Microstructural Performance Evaluation Of Diffusion Bonded Alloy 800H For Very High Temperature Nuclear Service

2021 ◽  
pp. 1-29
Author(s):  
Heramb Mahajan ◽  
Lucas Maciel ◽  
Tasnim Hassan
Keyword(s):  
High Temperature ◽  
Diffusion Bonding ◽  
Elevated Temperatures ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Failure Mechanisms ◽  
Bonding Process ◽  
Atomic Diffusion ◽  
Alloy 800H ◽  
Very High

Abstract Very high temperature reactors (VHTRs) are planned to be operated between 550 to 950°C, and demand a thermally efficient intermediate heat exchanger (IHX) in the heat transport system (HTS). The current technological development of compact heat exchangers (CHXs) for VHTRs is at the ‘proof of concept’ level. A significant development in the CHX technologies is essential for the VHTRs to be efficient, cost-effective, and safe. CHXs have very high thermal efficiency and compactness, making them a prime candidate for IHXs in VHTRs. Photochemically etched plates with the desired channel pattern are stacked and diffusion bonded to fabricate CHXs. All plates are compressed at an elevated temperature over a specified period in the diffusion bonding process, promoting atomic diffusion and grain growth across bond surfaces resulting in a monolithic block. The diffusion bonding process changes the base metal properties, which are unknown for Alloy 800H, a candidate alloy for CHX construction. Hence, developing mechanical response data and understanding failure mechanisms of diffusion bonded Alloy 800H at elevated temperatures is a key step for advancing the technology of IHXs in VHTRs. The ultimate goal of this study is to develop ASME BPVC Section III, Division 5 design rules for CHXs in nuclear service. Towards this goal, mechanical performance and microstructures of diffusion bonded Alloy 800H is investigated through a series of tensile, fatigue, creep, and creep-fatigue tests at temperatures 550 to 760°C. The test results, failure mechanisms, and microstructures of diffusion bonded Alloy 800H is scrutinized and presented.

Simulation and Experiment Investigation on Superplastic Forming/Diffusion Bonding Process of a Ti-6Al-4V Alloy Rear Fuselage Part

2018 ◽  
Vol 385 ◽  
pp. 407-412
Author(s):  
Gui Qiang Guo ◽  
Dong Sheng Li ◽  
Xiao Qiang Li ◽  
Xuan Zhao Huang
Keyword(s):  
Titanium Alloy ◽  
Double Layer ◽  
Diffusion Bonding ◽  
Layer Structure ◽  
Thickness Distribution ◽  
Superplastic Forming ◽  
Bonding Process ◽  
Double Layer Structure ◽  
Simulation And Experiment

Superplastic forming/diffusion bonding (SPF/DB) process is widely used in aviation titanium alloy parts forming. PAM-STAMP was utilized to simulate the SPF/DB process of a Ti-6Al-4V double layer structure part in rear fuselage at 920°C and reach the thickness distribution of the part. Then the part was formed based on simulation. The thickness distribution of the practical part was measured and compared with the simulation result. The results show that the thickness distributions of practical and simulated part fit well with each other.

Ultra-High Temperature Ceramics (UHTCs) via Reactive Sintering

2007 ◽  
Vol 336-338 ◽  
pp. 1159-1163 ◽  
Author(s):  
Guo Jun Zhang ◽  
Wen Wen Wu ◽  
Yan Mei Kan ◽  
Pei Ling Wang
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Oxidation Resistance ◽  
High Performance ◽  
Thermal Protection ◽  
Ambient Pressure ◽  
Stable Phase ◽  
Reactive Sintering ◽  
Dissociation Temperature ◽  
Monolithic Ceramics

Current high temperature ceramics, such as ZrO2, Si3N4 and SiC, cannot be used at temperatures over 1600°C due to their low melting temperature or dissociation temperature. For ultrahigh temperature applications over 1800°C, materials with high melting points, high phase composition stability, high thermal conductivity, good thermal shock and oxidation resistance are needed. The transition metal diborides, mainly include ZrB2 and HfB2, have melting temperatures of above 3000°C, and can basically meet the above demands. However, the oxidation resistance of diboride monolithic ceramics at ultra-high temperatures need to be improved for the applications in thermal protection systems for future aerospace vehicles and jet engines. On the other hand, processing science for making high performance UHTCs is another hot topic in the UHTC field. Densification of UHTCs at mild temperatures through reactive sintering is an attracting way due to the chemically stable phase composition and microstructure as well as clean grain boundaries in the obtained materials. Moreover, the stability studies of the materials in phase composition and microstructures at ultra high application temperatures is also critical for materials manufactured at relatively low temperature. Furthermore, the oxidation resistance in simulated reentry environments instead of in static or flowing air of ambient pressure should be evaluated. Here we will report the concept, advantages and some recent progress on the reactive sintering of diboride–based composites at mild temperatures.

TLP Bonding Technologies for Micro Joining and 3D Packaging

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001221-001252 ◽  
Author(s):  
Kei Murayama ◽  
Mitsuhiro Aizawa ◽  
Mitsutoshi Higashi
Keyword(s):  
High Temperature ◽  
Melting Point ◽  
Low Temperature ◽  
Wafer Bonding ◽  
Bonding Process ◽  
Tlp Bonding ◽  
Hermetic Sealing ◽  
Low Temperature Bonding ◽  
Free Material ◽  
Bonding Technique

The bonding technique for High density Flip Chip(F.C.) packages requires a low temperature and a low stress process to have high reliability of the micro joining ,especially that for sensor MEMS packages requires hermetic sealing so as to ensure their performance. The Transient Liquid Phase (TLP) bonding, that is a kind of diffusion bonding is a technique that connects the low melting point material such as Indium to the higher melting point metal such as Gold by the isothermal solidification and high-melting-point intermetallic compounds are formed. Therefore, it is a unique joining technique that can achieve not only the low temperature bonding and also the high temperature reliability. The Gold-Indium TLP bonding technique can join parts at 180 degree C and after bonding the melting point of the junction is shifted to more than 495 degree C, therefore itfs possible to apply the low temperature bonding lower than the general use as a lead free material such as a SAC and raise the melting point more than AuSn solder which is used for the high temperature reliability usage. Therefore, the heat stress caused by bonding process can be expected to be lowered. We examined wafer bonding and F.C bonding plus annealing technique by using electroplated Indium and Gold as a joint material. We confirmed that the shear strength obtained at the F.C. bonding plus anneal technique was equal with that of the wafer bonding process. Moreover, it was confirmed to ensure sufficient hermetic sealing in silicon cavity packages that had been bonded at 180 degree C. And the difference of the thermal stress that affect to the device by the bonding process was confirmed. In this paper, we report on various possible application of the TLP bonding.

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