Structure And Property Study By Nitrogen And Fluoride Plasma Based Ion Implantation On Ti6Al4V Alloy

In this paper, surface modification of Ti6Al4V alloy was nitrogen and fluorideplasma based ion implantation. The effects of process parameters after implantationon microstructure, anti-oxidation, corrosion resistance, nanohardness and elasticmodulus, frictional behaviors and biocompatibilities were studied systematically.The surface roughness and morphology of the modified layer were observed byatomic force microscopy （AFM）. The surface composition and structure of modifiedlayer were determined using X-ray photoelectron spectroscopy （XPS）. Theelectrochemical corrosion behavior in saline was investigated. The nanohardnessand modulus of elasticity were measured by mechanical microprobe, also the wearscar profile. The friction properties were measured by ball disc wear experimentalinstrument. The oxide morphology, corrosion morphology, morphology of dippinginto SBF and wear scar morphology were determined by scanning electronmicroscopy （SEM）. EDS spectrum investigeted the element content of oxide layerand SBF surface sediments elements.The results showed that the roughness was non-monotonic changes. Modifiedsamples’ surface composed of titanium（Ti）, oxygen（O）, carbon（C）, nitrogen（N） andfluorine（F）, the elements combined TiO₂, TiF₃, TiF₄, TiN, CN, N₂and Al2O3.Modified samples’ oxidation cracks were shorter, lighter than substrate andconcentrated in the surface and did not have in-depth internal cracks. Nitrogen-fluoride ion implanted samples’ corrosion potential was lower and the corrosioncurrent was higher than the substrate. The corrosion resistance decreased mostgently when the fluoride implanted bias was equal to the nitrogen implanted bias.The corrosion happened along the grain boundary. The surface sediments of nitrogen–fluoride implantation and single fluoride implantation were uniform distribution.The Ca/P ratio was close to hydroxyapatie. The biocompatibilities were improvedsignificantly than substrate and single nitrogen implanted samples. The biocompa–tibilities were relatively poor when the fluoride implanted bias higher thannitrogen’s.Nitrogen-fluoride implantated sample’s elastic modulus increased compared tosubatrate, single nitrogen implanted and single fluoride implanted samples. Thenanohardness of nitrogen-fluoride ion implantated samples whose injected fluoridebias is higher than the nitrogen’s was lower than substrate and single nitrogenimplanted samples. The nanohardness of nitrogen-fluoride ion implantated sampleswhose injected fluoride bias is lower than the nitrogen’s was higher than substrate. Nitrogen implantated sample’s elastic modulus reduced, but the nanohardnessincreased significantly. Fluoride implantated samples’ elastic modulus andnanohardness decreased. Nitrogen-fluoride and single nitrogen implanted samples’friction coefficient and wear volume decreased compared to the substrate. The wearresistance improved. Fluoride implanted sample’s friction coefficient increased. Theunhandled substrate is more severe adhesive and oxidative wear composited. Themodified samples were oxidative and abrasive wear both, dispersed particles of wearscar appeared. We can see no more serious adhesive ditch in the sliding time100s.There appeared wear debris and furrows morphology in the time500s.