Effect of HfC addition on ablation behavior of SiBCN ceramics

To improve ablation resistance of SiBCN ceramics, an ultra-high temperature ceramics (UHTCs) phase of HfC was introduced into SiBCN ceramics via high-energy ball milling and hot press sintering methods. The micro-structures, phase compositions, ablation properties and mechanism of SiBCN/HfC composites under a plasma flame ablation environment were investigated. The composite exhibited excellent ablation resistance under a heat flux density of 4.02 MW/m(2) for 60 s. The mass ablation rate of the SiBCN/HfC composite is evaluated to be 2.3 x 10(-5) mg/mm(2).s, which is an order of magnitude lower than that of SiBCN-based ceramics. The result showed that the introduction of HfC provided a skeleton support structure for the oxide layer that can significantly improve the ablation resistance. Furthermore, HfO2 that originated from the oxidation of HfC can serve as the skeleton for reducing the fluidity of the continuous SiO2 glass protective layer. It also suggests that HfC can be an optional addition to improve the ablation properties of the SiBCN ceramic.