ADHESION OF THERMALLY SPRAYED HYDROXYAPATITE-BOND-COAT SYSTEMS MEASURED BY A NOVEL PEEL TEST

Ti6Al4V foils, 100 mu m thick, were coated with thin (10-15 mu m) bond coats based on titania and zirconia, and subsequently coated with a t hick (100-120 mu m) hydroxyapatite layer, using atmospheric plasma spr aying. Peel adhesion tests of the coating systems performed on the foi ls showed that titania, and mixed titania/non-stabilized zirconia bond coats improved the adhesion of the ceramic layers to the metallic sub strate in a statistically significant way, while a partially CaO-stabi lized zirconia bond coat led to a decrease of the peel adhesion streng th when compared to hydroxyapatite coatings without a bond coat.