Optimizing Si–C reaction bonding for SiC joining: Effects of filler composition, thickness, and surface roughness on joint strength

Abstract

In this study aims, four key questions regarding the joining of silicon carbide (SiC) via Si–C reaction bonding are explored. These questions address the optimal filler composition for minimizing free Si, the effect of surface roughness on the joint strength, the ideal filler thickness for achieving the maximum joint strength, and the typical defects observed at the joint. To investigate these aspects, SiC was joined using a SiC/C filler tape with varying thicknesses of 10–100 μm, followed by molten Si infiltration at 1500℃ for 1 h under vacuum. Additionally, the surface roughness of the SiC base was adjusted to four levels to evaluate its effect on the joint strength, and common defects were identified. The results indicate that a finely polished SiC base joined with SiC/C = 70/30 wt% tape of ≤ 50 μm thickness achieved a high joint strength of ≥ 250 MPa.