Simulation of cracking phenomena during laser brazing of ceramics and cemented carbide

To investigate the mechanism of the occurrence of the microcracks produced in laser brazing of silicon carbide and cemented carbide using a silver–copper–titanium alloy as the filler metal, a numerical simulation for thermal cycle and thermal stress was performed using the finite element method. The laser-irradiated area of the cemented carbide was heated selectively, and almost uniform temperature distribution in the filler metal was obtained. The tensile thermal stress in the silicon carbide appeared near the interface between the silicon carbide and the filler metal, and the maximum principle stress at about 400 K during the cooling process reached the fracture strength of the silicon carbide. This resulted in the formation of microcracks in the silicon carbide which was observed in the experiment.