Thermoablative resistance of Ta/TaHfC2-laminated composites under plasma flame

A strong and tough Ta/TaHfC2-laminated composite was proposed and investigated in terms of its thermoablative behavior under plasma flame for a medium-long time (30-120 s) beyond 2517 K. In comparison to TaHfC2, the composite performed a better thermal shock resistance but an equivalent linear ablation rate (-5.40 vs. -4.08 mu m/s) after ablation for 30 s. With extending the ablation time, the linear ablation rate of the composite increases. Combined with the characterization results of the ablative layer and the established volatile phase diagram at 2273 K, it was found that the composite mainly undergoes active oxidation, passive oxidation, and dissolution of oxygen during the ablation, whereas its ablative layer mainly experiences the sintering, solid solution, and loss processes of oxides. The reason the composite possesses a good ablation resistance is because the introduction of Ta-foil-improved toughness as well as protective effect of the ablative layer of TaHfC2.