Study On Selective Laser Sintering Of SiC And Post Process

SiC have many good properties, such as low value of density, thermal expansion coefficient and high value of thermal conductivity, hardness, elastics modules, flexural strength and thermal shock resistance. So it has wide application field and well prospect. But its high hardness and strength led to the difficulty of process. However, Selective Laser Sintering(SLS) can produce parts with complex shape directly from their CAD models. Foreign countries have done some initial research about that, but there is no paper present in domestic. So the purpose of this paper is focus on indirect selective laser sintering SiC ceramic and its post processing technology. The main research contents and results are as follows:The principle and characteristic of SiC by SLS have been discussed. The mechanisms and differences of CO₂ and YAG laser sintering ceramic are analyzed. Several binders are compared and Epoxy resin has been chosen. The critical parameters of sintering are been optimised, and the best process parameters are as follows: SiC powders(-280#), E06 as the binder and The least proportion is 2wt%, CO₂ laser, T=40℃, P=15w, v=2000mm/s, D=0.1mm, H=0.1mm.Debinding processes temperature, keeping time and protection atmosphere are analysed according to the DSC and TG analysis of binder. Mechanism and process parameter and shrinkage of high temperature sintering also been discussed, the porosity after debinding and sintering is 54.9%.The infiltration processes of composition resins(E-42 and Novolac) for producing Polymer Matrix Composite parts have been investigated,and the bending strength is 65.3Mpa; Ceramic Matrix Composites with high precision also can be produced successfully from their CAD models directly by combination of SLS and DIMOX, The ceramic and metals are continuous forming three dimensions networks and there are 45.1Vol% of SiC, 32.7Vol% of Al₂O₃, 18.0Vol% of Al and 4.2% of porosity in the material, its bending strength is 361.2MPa.According to the systemic research of SLS and post process, SiC and its composites parts can be manufactured by SLS. The research is very helpful for inducing SLS to the fabrication fields of ceramic and composites materials in future.