Thermal shock and ablation behavior of alpha-cordierite glass-ceramic coating on porous BN/Si2N2O ceramic

摘要

Thermal shock and ablation behavior of alpha-cordierite glass-ceramic coating on porous BN/Si2N2O ceramic substrate were investigated. The coated sample was fractured after 18 thermal shock cycles without peeling off of the coating, while the porous BN/Si2N2O ceramic was fractured after 3 thermal shock cycles. The coated sample has a baiter thermal shock resistance than the substrate sample, which can be attributed to the strong interface bonding, the cracks self-healing and thermal barrier of the coating. The ablation surface temperature, mass and linear ablation rates of the porousBN/Si2N2O ceramic were all reduced by the coating, indicating that the substrate had a good ablation resistance under the protection of the coating. In the ablation atmosphere of high-temperature-speed oxyacalylene flame, thermochemical reactions, melting loss, and coupling balween them are the ablation mechanism of the coating/substrate composite.