Microstructure and mechanical properties of 3D-printed dental Co-Cr alloys, produced by selective laser melting

Abstract

Purpose The aim of present work was to investigate microstructure and mechanical properties of 3D printed by selective laser melting (SLM) Co- Cr alloys, intended for additive manufacturing in dentistry. Methods A scanning electron microscope (SEM), equipped with an integrated Energy-Dispersive X-Ray Spectroscopy (EDS) system was used for investigation of the surface morphology and elemental composition of the 3D- printed Co-Cr sample. The X-ray structural analysis of the 3D - printed Co-Cr sample was made with a Bruker D8 Advance powder X-ray diffractometer. An Atomic force microscopy (AFM) was used for investigation of the surface topography of the sample. Tensile test, a three-point bending test, and nanoindentation experiments were used for investigation of mechanical properties of the 3D-printed Co-Cr sample.The influence of two different strain rates (1 mm/min and 60 mm/min) on the flexural strength was investigated as well. Results Higher values of indentation hardness (6.76 GPa), tensile strength (1016 MPa), yield strength (636.5 MPa) and flexural strength (1908 and 1891 MPa) of the produced by selective laser melting Co-Cr alloys have been obtained compared to cast Co-Cr and Cr-Ni alloys. It was found that increasing the strain rate from 1 mm/min to 60 mm/min caused a proportional increase in recorded flexural strength of ~0.9%. Conclusions The obtained results showed that the laser-sintered Co-Cr alloy can fully replace the cast Co-Cr alloy in dentistry, regards as of its good mechanics properties, as well as the high precision of the final product.