Wetting behavior and brazing of titanium-coated SiC ceramics using Sn0.3Ag0.7Cu filler

By coating active titanium, Sn0.3Ag0.7Cu (SAC) filler wetted SiC effectively, as the contact angle decreased significantly from similar to 145 degrees to similar to 10 degrees. Ti3SiC2 and TiOx (x <= 1) reaction layers were formed at the droplet/SiC interface, leading to the reduction of contact angle. Reliable brazing of SiC was achieved using titanium deposition at 900 degrees C for 10 minutes, and the typical interfacial microstructure of Ti-coated SiC/SAC was SiC/TiOx + Ti3SiC2/Sn(s,s). Comparing to direct brazing, Ti-Sn compounds in the brazing seam were effectively reduced and the mechanical property of joints was dramatically improved by titanium coating. The optimal average shear strength of SiC joints reached 25.3 MPa using titanium coating- assisted brazing, which was similar to 62% higher than that of SiC brazed joints using SAC-Ti filler directly.