Formation of an oxide layer on a biomaterial Co-Cr-Mo alloy by using a hollow-cathode glow discharge plasma with argon-oxygen and neon-oxygen mixed gases

Abstract

A plasma treatment was investigated as a way to form an oxide layer on a biomaterial Co-Cr-Mo alloy (CCM alloy); the method uses a hollow-cathode-type glow discharge as the atomization/reaction source, and it is under in situ monitoring of the emission signal from the plasma. This study focused on how the plasma condition could be optimized to form a stable passivation layer on the CCM alloy based on the spectrometric information. For this purpose, a hollow-cathode-type glow discharge source was employed to form an oxide layer with a pure chromium target to be sputtered in argon-oxygen and neon-oxygen mixed gas plasmas. The thickness of the layer gradually became elevated with increasing oxygen gas partial pressure, and the layer grew more rapidly when neon mixed gas was used in place of argon. A notable feature of this method is that a surface layer of Cr2O3 can be produced with a thickness of up to several hundred nanometers after a treatment time of only a few minutes, which could occur when neon mixed gas plasma was operated under the optimized discharge condition.