Thermal Shock Resistance of Silicon Nitrides Using an Indentation-Quench Test
S K. Lee, J D. Moretti, Brian R. Lawn
The thermal shock resistance of silicon nitrides is investigated using an indentation-quench procedure. Four grades of commercially available silicon nitrides with different microstructures are investigated. The extension of Vickers radial cracks is measured as a function of thermal quenching for each material, up to the critical quench temperature for failure. The highest critical quench temperatures are shown by the toughest silicon nitrides. An indentation fracture mechanics analysis is used to account for the crack responses, with due allowance for R-curve behavior. The analysis confirms the important roles of microstructure and initial flaw size in thermal shock resistance.