Oxidation protection performance of ZrB2-LaB6 modified SiC coating at 1700 ℃

Abstract

In response to the problem of high-temperature oxidation and volatilization of SiC coatings on carbon materials at 1700 ℃, this paper proposes to prepare ZrB2-LaB6 modified SiC coatings on graphite substrate surface by spark plasma sintering. The oxidation protection performance of five different ZrB2-LaB6-SiC coatings with different ratios of ZrB2 and LaB6 was tested at 1700 ℃ isothermal environment and thermal shock environment. The results showed that the oxidation protection efficiency of the coated samples with LaB6 content of 0, 3, 5, 8 and 10 wt% after oxidation for 100 min at 1700 ℃ was 96.6%, 98.0%, 96.9%, 96.4% and 95.5%, respectively. The coating with 3 wt% LaB6 had the best oxidation protection effect with the coating still maintaining its integrity and high oxidation protection efficiency after 20 thermal shock cycles with an overall oxidation protection efficiency after thermal cycling of 97.7%.