Statistical Properties of Indentation Toughness of Ceramics

The toughnesses of a soda-lime glass and a TiC particulate-reinforced alumina com- posite were measured by the direct indentation method. It was found that, for each material, the indentation toughness measured at a given applied indentation load exhibits a large scatter and can be described well with Weibull distribution function. Comparison between the experimental data obtained with different materials revealed that the scatter in the measured indentation tough- ness can be attributed to the effect of microstructural inhomogeneity on the local crack resistance. Based on these findings, it was suggested that, when determining the fracture toughness with the direct indentation method for a given material, a large number of individual measurements should be made at a given indentation load to obtain a complete description for the statistical properties of the measured indentation toughness.