Effect of Sputtered Ni and Ni/Al on Vacuum Brazing Performance of SiC Ceramics

In this work,Ni film and Ni/Al double-layer thin film were sputtered on the surface of SiC ceramics by magnetron sputtering,and then the brazed joint with Al as filler metal was prepared by vacuum brazing. The effect of Ni and Ni/Al sputtered on the interface bonding of SiC vacuum brazed joint was studied. The results show that the average shear strength of SiC brazed joint sputtered with Ni film is 69.4 MPa,and that of SiC brazed joint sputtered with Ni/Al film is 113.8 MPa,both are higher than that of unmodified SiC brazed joint(48.4 MPa). The reason is that Ni and Ni/Al films are deposited on the SiC surface by sputtering. On the one hand,it can avoid the reduction of interfacial bonding strength caused by the formation of brittle reaction phase Al₄C₃;on the other hand,it is helpful to improve the wettability of aluminum solder on SiC surface. In addition,compared with sputtered single-layer Ni film,the shear strength of SiC brazed joint modified by Ni/Al double-layer film is greatly improved because the distribution of Al₃Ni phase is more concentrated,which plays the role of "anchoring" the weld.