Wetting and spreading behavior of Sn-Ti alloys on SiC

The isothermal wetting behavior of Sn-Ti alloys in contact with SiC were studied by the sessile drop method in the 900 °C-1000 °C temperature range, and the interfacial microstructures were characterized. Ti additions led the system to evolve from a non-wetting (? = 151°) to a wetting state with the formation of interfacial layers (TiC and TiSi). As the Ti concentration increased, more TiSi phases grew on the TiC layer and lower final contact angles were obtained. The lowest value ? = 20° was obtained at 1000 °C for the Sn-2.0Ti/SiC system. The Sn-5.0Ti melt kept the contact angle of 20° as well, whereas the formation of solid Sn-Ti intermetallics inhibited the kinetics of spreading. Lower temperatures had no influence on the final contact angles, only slowed down the spreading rate. The spreading of Sn-Ti melts on SiC consisted of three stages: (i) reaction-limited stage, (ii) transition stage and (iii) diffusion-limited stage. The activation energy of the first stage was calculated to be 210.3 kJ/mol. These results offer important information to optimize SiC brazing and for the preparing SiC-based composites.