Composition design of Sn-based active solder for soldering SiC ceramic using density functional theory calculation
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Composition design of Sn‑based active solder for soldering SiC ceramic using density functional theory calculation Zongyu She1 · Weibing Guo1,2 · Haitao Xue1 · Xiaoming Zhang1 Received: 16 March 2020 / Accepted: 3 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Soldering SiC using Sn-based solder can lower residual interface stress due to low soldering temperature. Active elements can play key roles in interfacial bonding between Sn-based solder and SiC ceramics. In this study, density functional theory (DFT) calculation was performed to evaluate whether Ti, Al, Zr and Ag atoms can act as active elements to solder SiC. Work of adhesion (Wad), charge density difference and density of states were used to study the interfaces without and with active elements. β-Sn(001)/β-SiC(111) interface was built first and the C-terminated hollow site interface was found to have the largest Wad of 3.13 J/m2. It is found that with doping of Ti and Zr atoms, Wad values of interfaces increase to 5.70 and 5.35 J/m2, and thermodynamics stability of interfaces are also improved. In contrasting, Al and Ag atoms have the opposite effects. The electronic structure analysis shows that Ti and Zr can form strong ionic bonds with C atoms. Therefore, Sn–Ti and Sn–Zr alloys can be used as active solders to join SiC ceramic at low temperature. Keywords Ceramics · Interfaces · Sn active solder · DFT calculation
1 Introduction SiC ceramics have been widely used in the fields of nuclear power, electronics and aerospace for their high mechanical properties and thermal stability. Joining process is always needed to prepare complex SiC ceramic components [1]. Among the available joining processes, the active brazing and soldering have been extensively studied for their low cost and convenience [2]. SiC ceramic is a covalent material and hardly wetted by pure metals [3]. Small content of Ti element in Ag-based filler metal can lower the wetting angle due to the active reaction at the interface. Xiong et al. [4] brazed carbon fiber-reinforced SiC and TC4 with AgCuTi alloy powder. Ti in the filler could react with SiC to produce TiC, Ti3SiC2 and Ti5Si3 compounds at the interface, which could also promote interfacial wetting and bonding. Zhong et al. [5] brazed SiC ceramic with Cr3C2 particulate-reinforced AgCuTi alloys. TiC reaction layer with a thickness * Weibing Guo [email protected] 1
School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, China
State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
2
about 100 nm was observed at the interface. Ti5Si3 silicide phases were also observed near the reaction layer. The shear strength of the joint could reach up to 212.8 MPa. It can be concluded that active Ti element in Ag-based filler can react with SiC to form TiC layer at the interface, and the strength of joint is relatively high. However, brazing SiC with Agbased filler always need operating te
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