Microstructural and mechanical characterizations of SiC-304SS joints brazed with Cu-10TiH2 filler

A high-quality brazed joint of SiC ceramic and 304 stainless steel (SiC-304SS) was achieved by Cu-10TiH2 brazing alloy. The effects of brazing temperature on the interfacial microstructure and mechanical properties of SiC-304SS were analyzed. The typical interfacial microstructure of joints brazed at 1030 degrees C for 10 min was 304SS/sigma-phase/(Fe, Cr) Ti/Fe2Ti/Cu(s,s) + Fe2Ti + TiC/SiC ceramic. With the brazing temperature increasing, the element Fe continued diffusing into the brazing seam and reacted with the element Ti. Then the width of sigma-phase and the amount of Fe2Ti phase became increasing, and Fe2Ti phase became continuous. While, due to the reaction between Fe and Si, a buffer layer formed in SiC-304SS joints brazed at 1040 degrees C and 1050 degrees C. The main component of the buffer layer was FeSi2, TiC phases and carbon particles. In addition, the buffer layer contributed to forming a good gradient transition of coefficient of thermal expansion (CTE), releasing residual stress and improving shear strength of the joints. When brazing at 1050 degrees C for 10 min, the maximum shear strength of the joint was 100 MPa at room temperature and 53 MPa at 600 degrees C.