RAPID MANUFACTURING OF CERAMIC PARTS BY SELECTIVE LASER MELTING

摘要

An additive manufacturing technique for high-strength oxide ceramics is presented. Based on selective laser melting (SLM), a new approach has been developed that allows for tool-less manufacturing of complex shaped ceramic components directly from CAD data. Components are built layer by layer in a powder bed. In the new approach, a purely ceramic powder is completely melted by a laser beam. The powder does not contain any binder or glassy or metallic additives. This way, a density of the ceramic component of almost 100% is achieved directly by the SLM process, without any post-sintering, and thus without any shrinkage. The ceramic component is created by solidification from melt. In order to avoid crack formation, the ceramic is preheated to a temperature above 1600°C during the whole build-up process. Using a zirconia-alumina (ZrO2 - Al2O3) material, a fine-grained microstructure can be achieved and specimens with a flexural strength of more than 500 MPa have been manufactured. Complex shaped ceramic components have been manufactured for demonstration purposes. The build-up rate is comparable to that of SLM for metallic materials. The development of the technique is not yet completed and is still ongoing. The technique has the potential to be used e.g. for manufacturing ceramic functional prototypes, all-ceramic dental restorations or complicated geometries that can not be manufactured by conventional techniques.