Studies on calcium phosphate coatings

Hydroxyapatite, one form of calcium phosphate, is preferred for its ability to interact with living bone, resulting in improvements of implant fixatio n and faster bone healing. The interlayer of nitrides or oxides formed by D C magnetron sputtering improved the bonding strength of plasma-sprayed hydr oxyapatite coating to a maximum of 10 times for iridium oxide, due to the i ncreases in chemical bonding at interfaces of interlayer/hydroxyapatite coa ting. The thin and defects-free layer of calcium phosphate was formed by e- beam evaporation. The Ca/P ratio of film was successfully controlled with t he evaporants having the different ratio of Ca/P with addition of CaO. The Ca/P ratio of film had great effects on the structure formation after heat treatment and the dissolution behavior. The film with the Ca/P ratio of 1.5 showed an extremely low dissolution rate even in the amorphous state. Calc ium phosphate films had the average adhesion strength of 64.8 MPa. (C) 2000 Elsevier Science B.V. All rights reserved.