Evaluation of Performance of Cast and Laser-Sintered Cr-Co Alloys for Dental Applications

摘要

Dental prostheses may be built by additive layer manufacturing, specifically by direct metal laser sintering (DMLS). This innovative process allows a high percentage of unmanned work and the direct fabrication of parts from CAD data. Even if, in the product and production development field, these techniques are studied since last '80, up today there is a lack of knowledge about mechanical performance in the medical application. The target of this paper is to investigate the mechanical and functional characteristics, with respect to traditional cast parts. Tensile specimens were built in accordance with ASTM E8M both by DMLS (EOSINT-M270) and traditional lost-wax casting, using the same Cr-Co alloy. An experimental plan was designed to evaluate the effect of all process phases. Tensile performances, hardness, roughness and dimensional measurement, rupture surfaces SEM observation and porosity evaluation were performed. Sintered parts are rougher and proved to have Rockwell hardness values higher confront to cast ones. No significant dimensional variations were noticed among different processes. Some of the cast specimens present defects (macro porosity) that are absent in the sintered ones. UTS of all sintered specimens (～1400MPa) is almost double than of cast ones, whereas are more fragile (εb～5 vs 20%). The porosity in zone free of defects are comparable. Cr-Co specimen produced by DMLS show excellent strength and absence of defects with respect to traditional casting. Low εb values are not critical, since deformation of the final prostheses is limited by the ceramic layer fragility.