Production of fine hydroxyapatite films using the well-controlled thermal plasma

Hydroxyapatite (HAP)-coated implants on metallic substrates have been used as biomaterials. The problem is that HAP coating on metallic substrates is easily exfoliated at the boundary between HAP and metallic substrates, i.e. titanium (Ti). Therefore, Ti–HAP Functionally Graded Coating (FGC) is considered to improve adhesion of Ti–HAP coatings. In this paper, preparation of Ti–HAP FGC is studied in detail by using the well-controlled DC plasma jet. Properties of Ti–HAP FGC films (i.e. the c-axis orientation, the bond strength and the hardness) are also discussed in relation to spraying conditions.