Experimental and first-principles simulation study on oxidation behavior at 1700 °C of Lu2O3-SiC-HfB2 ternary coating for SiC coated carbon/carbon composites

The oxidation behavior and microstructure evolution of Lu2O3-SiC-HfB2 ceramic coating specimen at 1700 degrees C were investigated systematically by experimental study and first-principles simulation. The prepared ternary coating possesses a compact morphology, which effectively defends C/C substrate against oxidation at 1700 degrees C for 130 h, showing a good antioxidant property. The formed HfSiO4, Lu2Si2O7, and HfO2 with high melting points play an active role in developing the thermal stability of the oxidized scale. Besides, Lu and Hf atoms incline to diffuse into SiO2, which enhances its structural stability. The improved thermal property of the oxidized scale for the Lu2O3-SiC-HfB2/SiC ceramic coating can delay the effective delivery of oxygen inwardly and thus prolong its oxidation protection time. The quick volatilization of SiO2 at 1700 degrees C induces that some glass phase evaporates with being not completely stabilized, which causes the formation of holes and the consumption of the inner coating.

Automated summary

The oxidation behavior and microstructure evolution of Lu2O3-SiC-HfB2 ceramic coating at 1700 degrees C were investigated. The ternary coating showed good antioxidant property and improved thermal stability, prolonging the oxidation protection time.