Joining of SiC Ceramic to Graphite Using Ni-51Cr Powders as Filler

Abstract

Joining of SiC ceramic to graphite is important from both technical and economical points of view. High temperature brazing of recrystallized SiC ceramic to high strength graphite has been realized using Ni-51Cr (consisting of Ni + 51wt% Cr powders) powders as filler. The obtained maximum three-point bending strength of joints is 32.3MPa, which is equal to 80.8% of the strength of the graphite. Microstructure and phase analysis reveals that interdiffusions and chemical reactions take place in the weld zone. A reaction layer and an interlayer form in the interfacial area. The reaction layer, of which the thickness is about 60-100μm, is contacted with the SiC ceramic. The interlayer with the thickness of about 200μm exists between the graphite and the reaction layer. The reaction layer is mainly composed of Ni2Si, while the interlayer is mainly composed of Cr23C6 and Ni2Si.