The Effect of Particle Size of Silicon Nitride Powder on Properties of Silicon Nitride Ceramic Balls

Abstract

The micron-sized silicon nitride raw powder was ball-milled into submicron powders of different particle sizes, the silicon nitride ceramic balls were prepared by gas pressure sintering with cerium oxide and aluminium oxide as sintering aids. The microstructures and phase composition of the ceramic balls were characterized by SEM and XRD. The effects of particle size of silicon nitride powders on sintering properties and mechanical properties were investigated. The results show that the relative density, hardness and crushing load of silicon nitride ceramic balls increased with the decrease of the particle size of silicon nitride ceramic powder, and the ceramic balls prepared by small particle size have low porosity and uniform grains. The powder with the longest grinding time has a particle size of 0.40 μm, and the density of the silicon nitride ceramic ball is 3.245 g/cm3, the hardness is15.2 GPa, the fracture toughness is 7.6 MPa·m−2, and the crushing load ratio of the steel ball is 51.2%.