Assessing fracture toughness in sintered Al2O3-ZrO2(3Y)-SiC ceramic composites through indentation technique

Al2O3-ZrO2(3Y)-SiC ceramic composites were prepared by spark plasma sintering. The fracture toughness (K-IC) of the material was evaluated by indentation technique using different types of empirical formulas between 29.4 N and 98 N. The calculated K-IC values depend on the crack profile and the applied load. By analyzing the relationship between the indentation radius and the crack length and the crack profile, the crack form of the composite is determined as a Palmqvist crack. Raman spectra result shows that ZrO2 has a significant martensitic phase transformation when the applied load is 5 kg or higher. Additionally, the KIC value decreases slightly as the load increases. The equation based on the Palmqvist crack system and the curve fitting equation are more suitable for the calculation of the K-IC value of the material. The composite exhibits a combination of various toughening mechanisms, such as crack deflection and bridging, thereby improving the fracture toughness of the material.