Microstructure and Shear Strength of SiC Joint Brazed with LiAlSiO4 Reinforced AgCuTi Composite Filler

Abstract

In this work, SiC ceramics were successfully brazed at 900 °C using a composite brazing filler, and the effects of holding time and LiAlSiO4 addition on the interfacial microstructure and mechanical properties of the joints were systematically investigated. The results showed that the brazed joints were devoid of obvious defects, and the joint structure was mainly composed of SiC/Ti5Si3/TiC + TiCu2 + TiO2 + LAS + LiAlSi2O6 + Cu (s, s) + Ag (s, s)/Ti5Si3/TiC/SiC. When the brazing temperature was 900 °C for 10 min and the LiAlSiO4 addition was 1 wt%, the SiC brazed joints reached a maximum shear strength of 106.47 MPa, which was 4.7 times higher than that of the joints without LiAlSiO4 addition under the same conditions. According to theoretical calculations, the addition of LAS can successfully reduce residual stresses in SiC brazed joints and enhance the joint strength.