NEW ASPECTS CONCERNING Co-Cr ALLOYS

A new generation of cobalt-chronnum alloys doped with precious metals (Au, Pt, Ru) recently came on the market with the idea to improve the corrosion resistance The goal of this study was to verify this hypothesis, by testing 4 different such alloys Different investigations were carried out microstructural identification of the constituents by energy-dispersive X-ray spectroscopy, hardness values determination and electrochemical testing. The microstructures of alloys A and D exhibited round "inclusions" with a diameter up to 0 1 mm The hardness values for all 4 tested alloys are lower than of Co-Cr classical alloy Potentiodynanuc polarization curves in linear system of alloys A to D in comparison with a conventional Co-Cr alloy reveal important differences in the behavior of the studied alloys (A- D) as compared to the conventional Co-Cr alloy From the point of view of corrosion behaviour, the classical Co-Cr alloy is the best material followed by the alloys B and C with addition of respectively 4 % and 25 % precious metals The worst alloys were A and D, with only addition of 2 % of Au Due to their poor behaviour, using the dental Co-Cr alloys enriched with precious metals, as an alternative to conventional Co-Cr alloys, is not justified