High toughness Al2O3/LaPO4/Al2O3 composites fabricated by slurry impregnation sintering process

Continuous Al2O3 fiber-reinforced Al2O3 matrix (Al2O3/Al2O3) composites, aimed at aerospace applications, are recognized for their low density, high strength, and resistance to oxidation but suffer from limited toughness. To address this problem, a study was undertaken that utilized a slurry infiltration and sintering (SIS) process for the fabrication of Al2O3/Al2O3 composites with enhanced toughness. Composites have a microstructure that fine Al2O3 matrix filled the voids of coarse Al2O3 matrix, enhancing the tortuosity of crack propagation paths and thereby increasing the toughness of the composites. Additionally, the incorporation of LaPO4 coatings was explored as a means to further augment toughness. Findings indicate that the optimal Al2O3/Al2O3 composites, exhibiting superior performance, were fabricated at 1200 °C, achieving a density of 2.97 g/cm3, flexural strength of 209 ±20 MPa, and fracture toughness of 13 ±3 MPa·m1/2. A 320 nm LaPO4 coating was found to enhance the fracture toughness of the composites by approximately 20.70%. Consequently, the SIS technique, complemented by the application of LaPO4 coatings, represents a highly effective approach for the production of Al2O3/Al2O3 composites with significantly improved toughness.