Prepration and thermal shock resistance property of γ-Y₂Si₂O₇ ceramic coating on surface of porous silicon nitride

Using γ-Y₂Si₂O₇ and Y₂O₃-Al₂O₃-SiO₂ ternary oxide powders as raw materials, a dense γ-Y₂Si₂O₇ ceramic coating was fabricated on surface of porous Si₃N₄ by using a combined method of slurry spraying and high-temperature melt infiltration. The effects of the composition of raw materials and sintering temperature on structure, organization and thermal shock resistance of coating were studied systematically by XRD and SEM detection methods. The results show that a coating with double-layer structure of dense γ-Y₂Si₂O₇ layer and transition layer is obtained when amount of substance ratio of SiO₂ and Al₂O₃ is high. A single-layer structure is obtained when amount of substance ratio of SiO₂ and Al₂O₃ is low. The coating with double-layer structure has a better thermal shock resistance property than the coating with single-layer structure.