Mechanical Surface Properties of CoCr Alloys After Nitrogen PIII

Initial experiments were performed to improve the mechanical surface properties of CoCr alloys by nitrogen plasma immersion ion implantation (PIII). Fast thermally activated diffusion with an activation energy of 0.6 eV was observed. A detailed investigation of the phase formation by X-ray diffraction revealed a variable phase composition with CrN and Cr2N being dominating at higher temperatures and additional fcc phases being present. The hardness of the surface layer increased from about 300 HV by a factor of 3-5 while the wear rate was reduced by a factor of up to ten as a result of the PIII treatment.