THE SHRINKAGE, PHASE COMPOSITION AND MECHANICAL PROPERTIES OF CERAMICS WITH DIFFERENT β-SiAlON MAIN CRYSTALLINE PHASES PREPARED BY STEREOLITHOGRAPHY

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 1hour 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 %.