Sol-gel derived hydroxyapatite coatings on titanium substrate

Biomaterials, in particular those used for orthopaedic prostheses, consist of a metallic substrate, exhibiting excellent mechanical properties, coated with a ceramic layer, which guarantees resistance to the corrosion and an elevated bioactivity. In this paper the preparation of sol-gel films of hyd roxyapatite, HA (Ca-10(PO4)(6)(OH)(2)), on titanium substrate is described. The samples were obtained through the dip-coating method, starting from a colloidal suspension of hydroxyapatite. In order to increase the adhesion b etween the HA film and the metallic substrate, the same substrate has been preliminarily coated either with titanium oxide, TiO2 (in the anatase or ru tile phase), or calcium titanate, CaTiO3 (perovskite). Also these latter fi lms have been deposited from a sol-gel solution. The characterization of th e films through XRD, SEM, and AFM gave good results for the crystallinity o f the deposited HA; for what concerns the sample morphology, the films turn ed out to be homogeneous and crack-free. (C) 2000 Kluwer Academic Publisher s.