Ablation mechanism and properties of in-situ SiAlON reinforced BN–SiO2 ceramic composite under an oxyacetylene torch environment

Ablation mechanism and properties of in-situ SiAlON reinforced BN–SiO2 ceramic composites have been carefully studied under different ablation time. Results showed that the ablation properties depend on the ablation time. When the ablation time increases from 10 s to 60 s, the mass ablation rate increases from 0.20 mg/s to 6.24 mg/s and the linear ablation rate increases from 9.0 μm/s to 28.1 μm/s. The phases of ablation products mainly consist of amorphous SiO2, Mullite, Corundum and B2O. Four time-dependent ablation behaviors contributed to the various ablation regions: oxidation of matrix which includes BN and Si2Al3O7N; evaporation of B2O3(l) and softening of SiO2(s); scouring away of SiO2(l) and Al2O3(l) by high-speed gas stream; evaporation of SiO2(l) and Al2O3(l).