Thermal shock resistance and ablation behaviour of titanium diboride-copper-nickle FGM via SHS

TiB₂-Cu-Ni functionally graded materials (FGM) and TiB₂-Cu-Ni homogeneous cermet were fabricated by self-propagating high-temperature synthesis under conditions of Pseudo Hot Isostatic Pressing. The microstructure and compositions of FGM and cermet were examined by SEM, EPMA and EDX. FGM and TiB₂-Cu-Ni cermet were heated for twenty seconds by plasma torch arc heater to investigate thermal shock resistance and ablation behavior. The results indicated that the stacked interface between layer and layer of FGM was obscure, which showed that the bonding of layer and layer was in a good quality. On the ablation surface of cermet, a crack was found, while no crack appeared on the ablation surface of FGM. The mass loss of cermet after ablation experiment is 0.9g, while that of FGM is only 0.5g. The properties of thermal shock resistance, resistance to ablation and erosion of FGM are better than those of cermet due to the graded composition distribution, the higher overall ceramic content and higher relative density of ablation surface of FGM. The ablation results were analyzed and the transpiration of metal and mechanical erosion was considered as the main mechanisms of ablation.