Influence of Y2O3 particle size on the microstructure and corrosion behaviour of porous Si3N4 ceramics

Abstract

Abstract In this study, porous silicon nitride ceramics were fabricated by pressureless with different particle size of Y2O3 using as sintering additive. The effects of particle size of Y2O3 particles on sintering behaviour, microstructure and corrosion behaviour of the β-Si3N4 ceramics were studied in detail. As the Y2O3 particles size decreasing from 5 μm to 0.5 μm, the linear shrinkage of porous β-Si3N4 ceramics increased from 14.3% to 18.3%, and the sintering porosity decreased from 25.3% to 17.6%. The smaller Y2O3 particles additions were consisted of finer β-Si3N4 grains and demonstrated more accordant microstructure due to the well-dispersed Y2O3. The finer microstructure resulted in the improvement of mechanical properties, the sintered sample with 0.5 μm Y2O3 addition shown flexural strength of 450 MPa. Significant weight loss was observed after corrosion in 1 M HCl solution at 70°C for different time, due to the assumed formation of the grain boundary phase added to the Y2O3.