Mechanical properties and ablation resistance of La2O3-modified HfC-SiC coating for SiC-coated C/C composites

Highlights: • The mechanical properties and ablation resistance of La₂O₃-modified HfC-SiC (HSL) coating were evaluated. • The incorporation of La₂O₃ benefits to ameliorating the compactness of HfC-SiC (HS) coating. • HSL coating showed more positive ablation resistance than HS coating given its stable scale structure. • The ablated HSL coating also performed better mechanical properties compared with ablated HS coating. Plasma-sprayed La₂O₃-modified HfC-SiC (HSL) coating was prepared on SiC-coated carbon/carbon composites to obtain an elevated ablation resistance under a heat flux of 2.38 MW/m². The elastic modulus of sprayed HSL coating is about 140.97 GPa, 41.48 % greater than HfC-SiC (HS) coating. HSL coating also performed superior ablation resistance evidenced by integrated scale and stable ablation rates. Besides, the elastic modulus and adhesion strength of ablated HSL coating gained 65.9 % and 26.9 % increase compared with HS coating. Its reliable service performance is primarily attributed to the formed scale constituted by HfO₂ and La₂Hf₂O₇ particles encapsulated by La-Si-O glass.