In Situ Formation of Y2Si2O7–Corundum–Mullite Ceramic Composites with Enhanced Thermal Shock Resistance

HighlightsA Y2O3-SiC synergistic strategy enables in situ formation of Y2Si2O7in corundum–mullite ceramics.Y2Si2O7promotes densification and strengthens grain boundaries during sintering.The optimized sample exhibits improved strength and thermal shock resistance.Y2Si2O7improves crack healing and thermal shock resistance after thermal cycling.The strategy balances strength and thermal shock resistance in multiphase ceramics.Provides guidance for gas turbine combustion chamber insulation materials.The continuous drive for higher efficiency in gas turbines has led to increased combustion temperatures, making the thermal shock resistance of thermal insulation tiles a critical factor limiting performance. Corundum–mullite multiphase ceramics are widely used in such applications; however, their performance is often constrained by an inherent trade-off between mechanical strength and thermal shock resistance. In this work, a synergistic modification strategy based on rare-earth disilicate phases was developed, wherein Y2O3and SiC were incorporated into a corundum–mullite matrix to enable in situ formation and controlled distribution of Y2Si2O7via gel casting. During sintering, Y2Si2O7acts as a transient liquid phase, facilitating densification and grain boundary strengthening; upon thermal shock, it migrates to fill and heal grain boundaries and microcracks, thereby significantly enhancing thermal shock resistance. The optimized sample S5, sintered at 1400 °C, exhibited a bulk density of 2.12 g/cm3and a bending strength of 68.43 MPa. Notably, after 30 thermal shock cycles (air cooling from 1000 °C to RT), its bending strength increased to 79.71 MPa, corresponding to a 16.48% enhancement. This work provides an effective strategy for incorporating rare-earth disilicates into multiphase ceramics and offers valuable guidance for the development of high-performance components for gas turbines.