Properties of plasma-spray coated hydroxyapatite on carbon/carbon composites pretreated by an argon plasma

Carbon/carbon composites pretreated by an argon plasma were coated by hydroxyapatite (HA) using a plasma spraying method. The morphology, the compositions of the coating and bond strength between HA and substrate were investigated by scanning electron microscopy, X-ray diffraction, infrared spectrometry and a scratching test. Results indicate that although the morphology and phase compositions of the HA coating are similar, the substrate critical load, above which apparent spallation of the coating occurs, was 14.0 and 8.9 N with or without the pretreatment respectively, indicating that the argon plasma pretreatment improves the bond strength between the coating and the substrate.