Preparation and thermophysical properties of (GdYb)2Zr2O7-LiAlSiO4 composite ceramics

Abstract

Rare-earth zirconates are highly competitive ceramic materials for thermal/environmental barrier coatings (T/EBCs) due to their high melting point, high corrosion resistance, excellent high-temperature phase stability, and very low thermal conductivity. However, they are susceptible to thermal mismatch with the substrate, leading to localized thermal stress concentration and generation of cracks in the coating, which eventually affect their service life and practical applications. In this study, (GdYb)₂Zr₂O₇-LiAlSiO₄ (GYbZ-LAS) composite ceramics were successfully prepared by high-temperature solid-phase method to reduce the coefficient of thermal expansion (CTE) of the GYbZ matrix. The incorporation of the LAS phase reduced the composite ceramic density while enhancing particle size distribution uniformity. Compared to pristine GYbZ, the fracture toughness of the composite ceramic doubled from 1.29 to 2.56 MPa·m^1/2, accompanied by a marked improvement in mechanical properties. Furthermore, the LAS phase effectively mitigated microcrack formation in GYbZ at elevated temperatures, reducing the overall CTE from 11.05 × 10⁻⁶ to −4.07 × 10⁻⁶ K⁻¹, thereby significantly enhancing the composite's thermal stability. The research on GYbZ-LAS provides important theoretical foundation and reference directions for the development of T/EBCs for engines operating in high-temperature environments.