Biomimetic hydroxyapatite coating on titanium alloys for biomedical application

Abstract

A bonelike apatite layer was formed on metallic substrate ( Commercial grade Titanium) when Calcium silicate was used as a catalyst for the apatite nucleation, and simulated body fluid was used as a medium for the apatite growth. The apatite-forming ability detected by EDX, the molal' ratio of CajP=1.70, indicating that calcium silicate coatings have the ability to induce the bone-like apatite nucleation and growth on their surfaces from SBF. It is assumed that particular silicate oligomers with structures such as dimer, linear trimer and cyclic tetrarner contribute to the apatite nucleation the most. The apatite layer was formed not only OIl limited surfaces but also on the whole surfaces of Titanium Substrate .. This biomimetic method is expected to enable the bone like apatite coating on various kinds of materials with complex shapes. Apatite interface was observed under a scanning electron microscope after 72 hours soaking in stimulated bodyfluid. The apatite layer formed by the biomimetic process was confirmed to consist of small crystals of apatite from EDX chemical analysis. This type of apatite biocomposite expected to be useful as bone-repairing material! bone implant. The coatings formed on the metal surface were characterized by using X-ray diffractometer, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDXJ, and Atomic Force Microscopy (AFM, tapping mode image). The surface properties such as coaling thickness, topography, roughness, were also measured by AFM and coating hardness and coating strength were measured by scratch test.