Slurry-based selective laser sintering of polymer-coated ceramic powders to fabricate high strength alumina parts

Instead of conventional powder-based selective laser sintering, a novel slurry-based process to fabricate high strength ceramic parts is proposed. A slurry which was composed of alumina powder coated with water-insoluble semi-crystalline polyvinyl alcohol (PVA) as a structure material, water-soluble PVA as an organic binder, ammonium polymethacrylate (DARVAN C–N) as a dispersant, and deionized water as a solution, could be prepared with colloidal processing. A rigid green block could be built with a self-made rapid prototyping apparatus. The polymers contained in the scanned region were melted to connect the alumina powders, but transformed to be water-insoluble. However, the un-scanned region remained water-soluble. Due to dissolving of the polymers in water, the un-scanned region could collapse to obtain the green part. After binder removing and sintering, an alumina ceramic part could be obtained. An average flexural strength of 363.5 MPa and a relative density of 98% were achieved.