Interfacial reaction mechanism of SiC joints joined by pure nickel foil

To investigate the reaction mechanism of Ni/SiC system, 0.1 pm-thick pure nickel foil is used to join SiC ceramic at 1245 degrees C for different times. Interfacial melting is calculated to occur at 964 degrees C along the interface due to the low eutectic point of theta-Ni2Si and NiSi, a periodical layered structure, consisting alternating layers of silicides/ silicides+graphite, is formed along the interface due to periodical detachment of graphite from SiC reaction interface during the reactions between Ni-Si liquid phase and SiC. The reaction products of Ni/SiC are successfully predicted by CALPHAD method, based on a home-made Ni-Si-C ternary database. The reaction processes between Ni and SiC and the morphology changes of the joined seam are discussed in detail in this paper. The average shear strengths of SiC joints held for 15 min, 30 min and 60 min are tested to be 16.53 MPa, 19.32 MPa and 29.43 MPa, respectively.