1989 Volume 97 Issue 1127 Pages 710-714
Joining of SiC ceramics by active metal brazing method was studied. Sintered bodies of TiC, Ti5Si3 and Ti3SiC2, which have been reported to be the reaction products between SiC and active metal Ti, were fabricated. Some properties for these products, i.e., microhardness, four point bending strength and thermal expansion coefficient, were investigated. Their influences on the joining strength were discussed: the formation of Ti5Si3 is thought to be undesirable as a reaction product due to its weakness, and the large difference of thermal expansion coefficients between the reaction products and SiC, which means that the thicker the reaction layer grows, the larger the residual thermal stress develops. Some possibilities for the good wettability of Ag-Cu-2% Ti braze to SiC were discussed, while Ag-Cu braze did not wet. The wetting behavior of Ag-Cu and Ag-Cu-2% Ti alloys on SiC and the reaction products mentioned above was investigated by the sessile drop method. The variations of their contact angles as a function of temperature were observed, which showed the same behaviors on SiC and the reaction products, respectively. These results are thought to mean that the phenomenon that Ti promotes the wetting of Ag-Cu-2% Ti alloy on SiC does not depend on reaction products, but on adsorption.