Wettability and joining of SiC by Sn-Ti: Microstructure and mechanical properties

Reliable SiC/Sn-Ti/SiC joints were obtained by brazing (950 °C/10 min) and soldering (250 °C/2 min) following premetallization depend on the wettability of Sn-Ti on SiC. The microstructures of Sn-Ti/SiC interface were characterized by scanning electron microscopy, X-ray diffraction and transmission electron microscopy, and the mechanical properties of joints were evaluated by shear tests. Active Ti enhanced the wettability of Sn on SiC with the decrease of contact angle from 150° to 20°. Ti direct reacted with SiC to produce TiC and combines with released Si forming Ti₅Si₃. Much lower Ti concentration per contacting area in brazing and metallization, compared to wetting, resulted in defective bonding of Sn-Ti/SiC and few amounts of interfacial products (thin TiC layer or partial covered TiC layer with Ti₅Si₃). All of the SiC/SiC joints possess a similar shear strength of 27–32 MPa and rupture through β-Sn matrix in ductile fracture.