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排序方式: 共有305条查询结果,搜索用时 62 毫秒
1.
Chenglai Xin Rong Yuan Jiang Wu Qingyuan Wang Yanan Zhou 《Ceramics International》2021,47(3):3411-3420
A novel method for fabricating a nano-Cu/Si3N4 ceramic substrate is proposed. The nano-Cu/Si3N4 ceramic substrate is first fabricated using spark plasma sintering (SPS) with the addition of nanoscale multilayer films (Ti/TiN/Ti/TiN/Ti) as transition layers. The microstructures of the nano-Cu metal layer and the interface between Cu and Si3N4 are investigated. The results show that a higher SPS temperature increases the grain size of the nano-Cu metal layer and affects the hardness. The microstructure of the transition layer evolves significantly after SPS. Ti in the transition layer can react with Si3N4 and with nano-Cu to form interfacial reaction layers of TiN and Ti–Cu, respectively; these ensure stronger bonding between nano-Cu and Si3N4. Higher SPS temperatures improve the diffusion ability of Ti and Cu, inducing the formation of Ti3Cu3O compounds in the nano-Cu metal layer and Ti2Cu in the transition layer. This study provides an important strategy for designing and constructing a new type of ceramic substrate. 相似文献
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Influence of Ni Interlayers on the Mechanical Properties of Ti6Al4V/(WC-Co) Friction Welds 总被引:2,自引:0,他引:2
M. Shamanian M. Salehi A. Saatchi T. H. North 《Materials and Manufacturing Processes》2003,18(4):581-598
Ni interlayers were introduced prior to dissimilar friction welding of Ti6Al4V base material to three cemented carbide substrates. The fracture strength of Ti6Al4V/(WC-6 wt% Co) welds were poor and were markedly improved when 20-µm thick Ni interlayers were introduced prior to dissimilar friction welding. These results were only produced when the (WC-6 wt% Co) cermet was electroplated prior to friction welding. When the Ti6Al4V alloy was electroplated prior to friction welding, fractured WC particles and cracking were observed in the (WC-Co) carbide substrate. The fracture strengths of Ti6Al4V/(WC-11 wt% Co) and Ti6Al4V/(WC-24 wt% Co) welds were not improved when 20-µm thick Ni interlayers were introduced prior to friction welding. During mechanical testing, the Ni layer retained at the dissimilar joint interface created a region of weakness. 相似文献
4.
《Journal of the European Ceramic Society》2021,41(15):7507-7515
Monolithic SiC, for the first time, was seamless joined at a low temperature of 1200 °C using electric field-assisted sintering technology. A 300 nm Yb coating on SiC was used as the joining filler to form Yb3Si2C2 via an in-situ reaction with the SiC. A liquid phase was formed by an eutectic reaction between Yb3Si2C2 and SiC. Almost completely seamless joints were formed by the precipitated SiC grains, which were fully consolidated with the SiC matrix with the help of in-situ formed liquid phase, followed by its elimination under the uniaxial pressure. The bending strength of the seamless joint joined at 1500 °C for 15 min was as high as 257.2 ± 31.1 MPa, which was comparable to the strength of the SiC matrix. As a result, the failure occurred in the matrix indicated a sound joint was obtained. The proposed low temperature seamless joining could potentially be used for joining of SiC-based composite. 相似文献
5.
Wolfgang Tillmann Matthias Manka Lukas Wojarski Michael Holewa 《Science & Technology of Welding & Joining》2020,25(4):290-296
ABSTRACTTools for machining are exposed to high loads, wear, and elevated temperatures. Commonly, such tools consist of cemented carbides and tool steel. To combine the advantages of both materials, high-quality-joints with high strengths are desired. When brazing these materials, the main challenge is the mismatch of the Coefficient of Thermal Expansion (CTE) and the poor wettability of cemented carbides by molten filler alloys. In this regard, the feasibility of two custom-made alloys (CuNi12Si5, CuNi12Si5B0.4) was analysed. Besides being a cost-efficient alternative, these alloys offer the possibility to modify their mechanical properties by precipitation hardening to reduce stresses within the final joints. Thus, this paper shows that a temperature of 1060°C is suitable for wetting and brazing tests on different substrates. 相似文献
6.
Laser beam weld-metal microstructure in a yttrium modified directionally solidified Ni3Al-base alloy
The microstructure of laser beam weld-metal of an yttrium doped directionally solidified alloy IC 6A, with chemical composition Ni–16Al–8.5Mo–0.12B–0.05C–0.03Y (at.%) was studied. The dendritic microsegregation observed within the fusion zone indicated that dendrite cores were slightly depleted in molybdenum and aluminum and the interdendritic regions were also considerably enriched in yttrium. Severe cracking in the weld-metal was observed and was found to be closely associated with interdendritic eutectic-type microconstituents identified as consisting of γ, γ′ and Ni–Mo phases. An yttrium-rich phase (Ni3Y) was observed in some interdendritic regions containing the eutectic γ, γ′ and Ni–Mo products. Their formation was discussed in relation to plausible microsegregation induced alteration of primary solidification path during cooling from welding temperatures. 相似文献
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Design formalism for collaborative assembly design 总被引:1,自引:0,他引:1
Kyoung-Yun Kim Author Vitae Yan Wang Author Vitae Obinna S. Muogboh Author Vitae Bartholomew O. Nnaji Author Vitae 《Computer aided design》2004,36(9):849-871
Joints in product design are common because of the limitations of component geometric configurations and material properties, and the requirements of inspection, accessibility, repair, and portability. Collaborative product design is emerging as a viable alternative to the traditional design process. The collaborative assembly design (AsD) methodologies are needed for distributed product development. Existing AsD methodologies have limitations in capturing the non-geometric aspects of designer's intent on joining and are not efficient for a collaborative design environment. This paper introduces an AsD formalism and associated AsD tools to capture joining relations and spatial relationship implications. This AsD formalism allows the joining relations to be modeled symbolically for computer interpretation, and the model can be used for inferring mathematical and physical implications. An AsD model generated from the AsD formalism is used to exchange AsD information transparently in a collaborative AsD environment. An assembly relation model and a generic assembly relationship diagram are to capture assembly and joining information concisely and persistently. As a demonstration, the developed AsD formalism and AsD tools are applied on a connector assembly with arc weld and rivet joints. 相似文献
10.
《Intermetallics》2017
Size effect on growth kinetics of interfacial intermetallic compound (IMC), induced by Cu concentration gradient and pinning effect of Ag3Sn particles during multiple reflows, was investigated in this article. The simulation results, for Cu distributions in solder bulks of different volumes after a single reflow for 60 s at 250 °C, show that Cu concentration gradient in liquid increases with the growing size of solder bump. On the contrary, resistive pressure of nano particles decreases gradually with the increasing bump size. In conclusion, the pinning effect of Ag3Sn particles on IMC grains plays a dominant role in small samples, whereas the inhibiting effect of Cu concentration gradient is mainly functional in big samples. Combining the two factors, solder bump in an intermediate diameter of 800 μm benefits most and has the largest IMC thickness during multiple reflows. 相似文献