Infrared radiative performance and anti-ablation behaviour of Sm2O3 modified ZrB2/SiC coatings

To improve the emissivity of ZrB2/SiC coatings for serving in more serious environment, ZrB2/SiC coatings with varying contents of high emissivity Sm2O3 were fabricated using atmospheric plasma spraying. The micro-structure, infrared radiative performance and anti-ablation behaviour of the modified coatings were investigated. The results showed that as the content of Sm2O3 increased, the density of the coatings increased because of the low melting point of Sm2O3. When the content of Sm2O3 was 10 vol%, the coating had the highest emissivity in the 2.5-5 mu m band at 1000 degrees C, up to 0.85, because of the oxygen vacancies promoting additional electronic transitions. Due to the high emissivity, the surface temperature of the coating modified with 10 vol% Sm2O3 decreased by 300 degrees C, which led to little volatilisation of the sealing phase. Further, the mass ablation ratio of the above coating was 3.19 x 10(-4) g/s, decreasing 31% compared to that of a ZrB2/SiC coating. The formed dense surface structure of the coatings showed considerable oxygen obstructive effects. These findings indicate that the modified coatings show considerable anti-ablation performance, which provides effective anti-ablation protection for the C/C composite substrate.

Automated summary

By adding Sm2O3, the density of ZrB2/SiC coatings increased, leading to improved emissivity in harsh environments and showing good anti-ablation performance.