Effects of Some Variables on R.F. Magnetron Sputtered Hydroxyapatite Coatings on Titanium

Abstract

RF sputtering may be used to produce thin, well adherent bioactive coatings with long term stability to ensure contact with bone tissue. RF Sputtered Hydroxyapatite (HA) coatings were produced onto Ti at 200 and 150 W. S.E.M. analysis indicated that films obtained with 200 W were thicker than those with 150 W. Significant variations were observed, depending on the location of the substrates with respect to the sample holder in the sputtering chamber, with thickness ranging from 1.8 to 3.2 mm. EDS analysis of 200 W films revealed the presence of Ca and P, in ratios typical of HA. XPS of thinner films obtained at 150 W, showed Ca and P, but also some carbonate probably partially substituting OH -. Anodic polarisation curves of samples coated at 200 W and 150 W and for different sputtering times, compared to Ti substrate, indicate that HA films were protective and that the degree of protection increased with film thickness, i.e., with power intensity and time of deposition.