Ultra-high temperature ablation behavior of Ti2AlC ceramics under an oxyacetylene flame

The linear and mass ablation rates of Ti2AlC ceramics under an oxyacetylene flame at a temperature up to 3000 °C were examined by measuring the dimensions and weight change of the ablated samples. The linear ablation rate was decreased from 0.14 μm s−1 for the first 30 s of the ablation to 0.08 μm s−1 after 180 s. Ti2AlC ceramics gained small amounts of weight upon ablation, which is attributed to the formation of oxidation products on the ablated surface. The ablation surface exhibits a two-layer structure: an oxide outer layer, consisting mainly of α-Al2O3 and TiO2 and some Al2TiO5, and a porous sub-surface layer containing Ti2Al1−xC and TiCxOy. With increasing ablation time, the content of TiO2 and Al2TiO5 in the outer layer increased, and more pores developed in the sub-surface layer. The thermal oxidation of Ti2AlC under the flame and scouring of the viscous oxidation products by high-speed flow of gas torch are the main ablation mechanisms.