Thermo-mechanical modeling of residual stress and filler metal optimization for SiC cladding joints

This study employed the finite element modeling method to investigate the thermodynamic behavior of brazed joints between silicon carbide (SiC) clad tubes and five metal-based filled alloys (Ti, Ni, Zr, Ta, Nb). A thermally mechanical coupling model was established to simulate the thermal stress and strain distribution within the temperature range of 20 to 1200°C. The research results provide clear criteria for the selection of filled alloys under different temperature conditions. Below 800°C, due to the low coefficient of thermal expansion (CTE) and elastic modulus of ZR-based fillers, they have good compatibility with SiC and the lowest residual stress (63.38 MPa at 360°C and 109.34 MPa at 800°C). At 1200°C, niobium-based fillers exhibit the best performance, with a residual stress of 1189.55 mpa, which is approximately 50% lower than that of Ta-based fillers. Moreover, due to its high melting point, it has stable plastic deformation resistance. However, Ni-based solder generates extremely high stress (1848.68 MPa) at 800°C, far exceeding its yield strength, and has a high risk of interface failure. Ti-based fillers exhibit moderate stress relaxation through plastic deformation near 600°C, but they soften significantly at higher temperatures. Finite element analysis clarified the potential mechanism of residual stress generation caused by CTE mismatch, expanding the discussion space for the hierarchical design of high-integrity silicon carbide clad joints.