Joining of SiC ceramic by hot pressing reaction joining process using Ni-51Cr powders as filler

Joining of ceramics is of importance from both technical and economical points of view. Joining of recrystallized SiC ceramic to itself has been realized by hot pressing reaction joining process using Ni-51Cr powders (consisting of Ni+51 wt%Cr powders) as filler. The optimized technological parameters have been obtained by orthogonal experiment, which are joining temperature of 1150 degrees C, holding time of 20min, joining pressure of 10MPa and cooling rate of 0.25 degrees C/s. The most effective factor to influence the weld strength is joining pressure within the range of testing. Under the optimized conditions, the maximum relative bending strength of joint, 70.7%, is achieved. The microstructure and phase composition of the weld zone were examined by SEM, EDX and XRD. The results show that interdiffusions and chemical reactions take place in the joining process. A reaction layer, which is mainly composed of Ni2Si and Ni3C with a little Cr, exists between the welding base material SiC ceramic and the filler reaction product layer called as interlayer, which is mainly composed of Ni2Si and Cr.