In-situ formation of fine-grained carbide composite interlayer during diffusion bonding of SiC ceramic

摘要

SiC ceramic was successfully diffusion bonded to itself with a powder mixture of TiH2, Si and graphite by spark plasma sintering in the temperatures from 1150?°C to 1450?°C. The microstructure, phase formation and evolution, and the mechanical properties of the joints were evaluated. In-situ reaction in the powder mixture produced fine-grained Ti3SiC2and TiCx(TiC and TiC0.625) composite in the joint. The grain morphology and size of carbides were determined. No reaction between the carbides and SiC ceramic was observed. The fraction of Ti3SiC2in the composite joint had a strong effect on the joint strength, which increased with the increasing of Ti3SiC2content. The highest shear strength of 80.5?±?7.4?MPa was obtained at 1350?°C, due to the uniform distribution and inherent toughening characteristic of Ti3SiC2phase. The decomposition of Ti3SiC2occurred at 1450?°C led to the formation of TiCxand TiSi2, thereby lowering the shear strength. The hardness of the interlayer was dependent mainly on the fraction of TiCxphase.