The shrinkage, phase composition and mechanical properties of ceramics with different β-sialon main crystalline phases prepared by stereolithography

Abstract

In this paper, using Si3N4, Al2O3 and AlN particles as raw materials, β-SiAlON ceramics with different main crystal phases were designed. The green body of the β-SiAlON-matrix ceramic samples were obtained by using stereolithography (SLA) additive manufacturing. After degreasing, dense β-SiAlON ceramics with different SiAlON phases were fabricated through gas pressure sintering at 1800 °C for 1 hour at GPa. The effects of the different Al2O3 contents on the shrinkage, phase composition, relative density, microstructure, mechanical property and hardness were studied. The results indicate that the main phase of the ceramics was β-SiAlON and the specific chemical compositions of it were Si5AlON7, Si3.1Al2.9O2.9N5.1 and Si2Al4O4N4. The intergranular phases that exists were mainly Y3Al5O12, YAlO3 and Al2O3. With a relative density of 90.03 %, the Vickers hardness (Hv5), bending strength and fracture toughness of the fabricated β-Si5AlON7 ceramics were 16.8 GPa, 465 MPa and 4.84 MPa·m1/2, respectively. Meanwhile, the shrinkage of the materials was 28.7 %.