Microstructure evolution and joining mechanism of brazing (C_f-SiC_f)/SiBCN to Nb with TiZrNiCu

In this work, TiZrNiCu was proposed to realize the joining of the improved high temperature ceramic (C _f-SiC_f)/SiBCN and Nb. The effects of brazing temperature and holding time on interface microstructure and mechanical properties were investigated, and the joining mechanism was detailed described. The joint shear strength reached maximum of 36 MPa at 900℃/20 min, in which typical interface structure was SiBCN/TiC+ZrC/Ti ₅Si₃ +Zr ₅Si₃/(Ti,Zr) ₂ (Cu,Ni)/(Ti-Nb)ss/Nb. During the brazing process, Cu-Si brittle compounds were formed in the ceramic by infiltration of Cu into the (C _f-SiC_f)/SiBCN, responsible for the fracture path extended from the solder layer to the ceramic side in most cases. When the holding time was 30 min, the joint was directly broken on the ceramic base material due to the excessive penetration effect of Cu; at excessive temperature, the fracture occured in the filler, since the large difference between the (Ti-Nb)ss and the solder materials.