Preparation and properties of SiC ceramics <i>via</i> SLS/CIP process

Abstract

With the spray-dried SiC-Al2O3-Y2O3 powder as raw material, composite powder prepared by mechanical mixing was used to fabricate SiC ceramics by selective laser sintering/cold isostatic pressing combined with liquid phase sintering.The material phase composition, microstructure, flexural strength and density of SiC ceramics were characterized. The results show that spray-dried powder has an average diameter of 39.43μm with fine sphericity and flowability, which is suitable for SLS process. With the optimum parameters (laser power of 7W, scanning speed of 2200mm/s, scanning space of 0.15mm and layer thickness of 0.15mm) and CIP pressure of 80MPa, the green bodies show the superior quality with flexural strength of (2.23±0.10)MPa and bulk density of (1.31±0.05)g/cm3. After being sintered at 1950℃ for 2h, samples are densified that the bulk density and relative density of SiC ceramics are (1.95±0.17)g/cm3 and (60.81±5.31)%, respectively and the flexural strength is (55.43±4.04)MPa.

Keywords

• SiC ceramics
• selective laser sintering
• cold isostatic pressing
• liquid phase sintering
• spray drying