Elastic properties, hardness and indentation fracture toughness of β-sialons

Dense samples of β-sialons (with z from 1 to 4) were pressuressly sintered for different time (15-240 minutes) and at relatively low temperature of 1600 C using single-phase β-sialon powders synthesized by combustion nitridation. The samples were characterized using ultrasonic method for determination of elastic properties (E,G,μ). Also, hardness by Knoop and fracture toughness by Vickers indentation microfracture method was estimated. With increasing z number Young's modulus decreases from 293 to 179 GPa. Simultaneously Poisson ratio increases by about 30%. The highest values of hardness and fracture toughness were obtained for sialon with z equal to 1. (orig.)