Influence of crystallite morphology on the ablative behaviors of CVD-TaC coatings prepared on C/C composites beyond 2100 °C

Three types of TaC coatings with different crystallite morphologies were successfully fabricated on carbon/carbon composites by chemical vapor deposition, and their ablation performance was investigated. The TaC coating with acicular crystal exhibited a more favorable ablation resistance as certified by the compact surface morphology and lower ablation rates due to the formation of a stable oxide layer. As for others, the powdering of TaC coating with nano crystal induced by gas evaporation of acute oxidation, and the exfoliation of TaC coating with columnar crystal caused by grain overgrowth all resulted in their weak protection for C/C substrates during ablation. • CVD-TaC coatings with 3 kinds of crystallite morphologies were prepared. • The ablative behavior of TaC coating is greatly affected by crystallite morphology. • Acicular-crystal TaC coating exhibited a favorable ablation resistance. • Acute oxidation led to the powdering of nano-crystal TaC coating. • Grain overgrowth resulted in the exfoliation of columnar-crystal TaC coating.