Improvement for Ti₃SiC₂/Cu joint brazed using composite fillers with abnormal expansion ceramic particulates

Abstract

Reducing the residual stresses and improving the mechanical strength of largescale ceramic/metal brazing joints is an important problem that must be solved for its practical engineering application. Using composite filler with solid-state phase transformation ceramic particulates, it is theoretically feasible to relieve the residual stress and improve the mechanical properties of ceramic/metal brazed joints. In this study, Cu mesh, Ag-28Cu-2Ti (wt.%), and yttria-stabilized zirconia (0.6 mol.% YSZ solid-state phase transformation ceramic particulates) composite power fillers were used in the brazing of Ti 3 SiC 2 ceramic and pure copper. The microstructure of joints and YSZ particulates in the interface was investigated and confirmed by scanning electron microscopy (SEM), energydispersive X-ray spectroscopy (EDS), scanning transmission electron microscopy (STEM), and transmission electron microscopy (TEM). In addition, the effect of YSZ particulates content on the mechanical properties of joints was investigated and evaluated by the shear strength. The results show that the interfacial phases were mainly Ti 5 Si 3 , TiC, Ti x Cu, Ag (s, s), Cu (s, s), and YSZ particulates. Moreover, most of YSZ particulates undergo the solid-state phase transformation from tetragonal zirconia (t-ZrO 2 ) to monoclinic zirconia (m-ZrO 2 ) during the cooling process of brazing. The abnormal volume expansion of the solid-state phase transformation reduced the thermal mismatch between Ti 3 SiC 2 ceramic and filler, thereby reducing the residual stress in the interface of joint. When using composite filler with 6 wt.% YSZ particulates, the shear strength of Ti 3 SiC 2 /Cu joint reached the maximum. The maximum average shear strength of the joints was 80.2 MPa, which was about 103.6% more than the joint without YSZ particulates.

Microstructure and mechanical property of thick Cu/AlN joints formed at low temperature

“…11 On the other hand, the large difference in the coefficient of thermal expansion between Cu and ceramic induces high detrimental stress at the Cu/ceramic interface. 12 The larger thickness of Cu also increases the stress concentration and weakens the ceramic/Cu joint. 4,13 Thus, manufacturing thick Cu and ceramic joints is challenging.…”

“…Various bonding methods for Cu and ceramic, such as direct bonding copper, 1,7,14,15 direct plating copper, 8,16 active metal bonding, 10,12 and laser activation metallization 9,17 which limits the current carrying capacity. In direct plating copper technology, the ceramic is first surface modified by vacuum sputtering, and then electro-plated Cu is made on the ceramic via chemical bonding at a low temperature of ∼300 • C. 8 The thickness of Cu is limited to below 1 mm for a low plating rate of several µm/h.…”

“…On the one hand, the stable covalent and ionic bonds in ceramics lead to their poor wettability 11 . On the other hand, the large difference in the coefficient of thermal expansion between Cu and ceramic induces high detrimental stress at the Cu/ceramic interface 12 . The larger thickness of Cu also increases the stress concentration and weakens the ceramic/Cu joint 4,13 .…”

“…Various bonding methods for Cu and ceramic, such as direct bonding copper, 1,7,14,15 direct plating copper, 8,16 active metal bonding, 10,12 and laser activation metallization 9,17 technologies, have been reported. The most used method is direct bonding copper technology.…”

Determination of the Pressure Dependence of Raman Mode for an Alumina–Glass Pair in Hertzian Contact

“…Improving the performance of a ceramic material requires a deeper understanding of these materials. This new knowledge makes it possible to optimise the manufacturing processes and prolong its products’ operating conditions [ 1 , 2 , 3 ]. Determining residual stresses in the volume and on the material’s surface is essential to achieve this goal.…”