Effect of brazing parameters on the microstructure and mechanical properties of SiC ceramic joint with Zr-Cu-Nb filler metal

Abstract

The excellent properties of SiC ceramic make them possible to replace zirconium alloy and become the 4th generation of nuclear power plant cladding material. In this study, the microstructure and mechanical properties of SiC ceramic joint with Zr-Cu-Nb powder filler metal under different brazing temperature and holding time were investigated. The results show that Zr-Cu-Nb filler metal can effectively braze SiC ceramic at different brazing temperature (950$\sim$1150 °C) with the holding time of 20 min. The primary phases in the interface reaction layer are mainly ZrC and Zr₂Si. The shear strength of the joint first increases and then decreases with the brazing temperature, reaching a maximum of 135 MPa at 1050 °C under the holding time of 20 min. The joint primarily fractures at the reaction layer, exhibiting brittle fracture behavior. The thickness of the interface reaction layer increases with the holding time(5$\sim$60min) under the brazing temperature of 1050 °C. The shear strength of the joint reaches its maximum of 135 MPa at 20 min under the brazing temperature of 1050 °C, with the thickness of the reaction layer being 1.2 $\mu$m. The joint primarily fractures at the reaction layer, exhibiting brittle fracture behavior.