Selective laser sintering of coated Si₃N₄ ceramic powders

Efforts were focused on the improvement of fusibility of selective laser sintering (SLS) ceramic powders by the approach of coating some low melt-point binders on them. Methylmethacrylate monomer and butylmethacrylate monomer were synthesized and prepared as sintering binder. The infrared spectrum and DSC/TG method were employed to analyze the copolymer. The results showed the main composition of the copolymer is polymethylmethacrylate and polybutylmethacrylate, the glass transition temperature is 102.0℃ and the heat decomposition was beyond 80% between 300-400℃. The self-made copolymer and the inorganic binder NH₄H₂PO₄ were mixed together by a proper proportion. The binders were used to coat Si₃N₄ ceramic powders by mechanical mixing and spray drying. The coated powders were sintered successfully by SLS.