Study on Brazing of SiC Ceramics with Zr-Cu-Nb Filler Metal

In order to promote the application of SiC ceramics in nuclear reactor cladding materials, the preparation and application of (Zr-20Cu)-10Nb(wt.%) filler metal for SiC brazing were studied. The microstructure morphologies, phase composition and wettability to SiC ceramics of the filler metal prepared by the suction casting method were evaluated. The results show that the filler metal mainly consists of Cu, β-Zr and a diffusely distributed second phase β-Nb, and it can well wet SiC ceramics. In addition, the effects of brazing temperature (1000-1200 °C) and holding time (10-20 min) on the phase composition, microstructure and properties of SiC joints brazed by Zr-Cu-Nb filler metal were investigated, respectively. During the brazing process, the interfacial reactions occur between the filler metal and SiC to produce ZrC, Zr 2 Si and CuZr, and increasing the brazing temperature or holding time will promote the interfacial reactions. The effects of brazing temperature on joint properties are more significant compared to holding time. The shear strength of brazed SiC ceramic joints first increases and then decreases with the increase of brazing temperature or holding time, and the maximum shear strength of 101 MPa could be achieved when brazing at 1100 °C for 15 min.