Fabrication, Characterization And In Vitro Performances Of Calicium Phosphate/Al₂O₃ And Related Composite Biocoatings

Surface biological modification of bioinert materials has received much attention during the past decade. Due to the composition similar to human bone and the corresponding superior biocompatibility, calcium phosphate, such as hydroxyapatite (HA) and tricalcium phosphate (TCP) and so on, is one of the most promising candidates for the surface biological modification of bioinert materials. However, the compositional diversity of coating caused by high process temperature and/or the mismatch of mechanical performances between coating and substrate often lead to the decrease of biocompatibility and the delamination of coating. Therefore, it is interesting to fabricate new biocatings associated with perfect biocompatibility and good mechanical stability under mild conditions.In this dissertation, to simultaneously achieve good inductive and anti-corrosion ability and to enhance the adhesion of coating, calcium phosphate/Al₂O₃ and some related composite biocoatings, in which porous anodic Al₂O₃ acts as intermediate layer, have been developed by combining multiple methods. SEM, TEM, AFM, FT-IR, EDS, XRD and ICP/AES were employed to investigate the morphologies, compositions and in vitro inductive ability of the prepared composite systems. The research on the in vitro anti-corrosion ability of the obtained composite systems in Ringer′s solution was performed by potentiodynamic polarization (Tafel polarization). And the effect of process parameters on the bonding strength of HA/Al₂O₃ composite biocoating on Ti substrate was also determined by tensile test. The main results and conclusions were as followings:(1) Calcium phosphate/Al₂O₃ composite biocating was successfully fabricated on Ti by a hybrid technique of magnetron sputtering physical vapor deposition (MSPVD), anodization and hydrothermal treatment.It was found that the pores of anodic Al₂O₃ became bigger and the atomic ratio of Ca/P contained in anodic Al₂O₃ increased as high anodization voltage was applied. After hydrothermal treatment at 212℃for 8 h, anodic Al₂O₃ containing Ca and P on Ti was transformed to calcium phosphate/Al₂O₃ composite biocating. The crystallization and epitaxial growth of calcium phosphate in the pores of anodic Al₂O₃ resulted in the formation of"T"shape interface between calcium phosphate outer layer and anodic Al₂O₃ intermediate layer.