Formation Of HA/COL Composite Coatings On The Surface Of Ti And NiTi Alloy

This work is mainly attributed to form HA/COL composite coatings on the surface of Ti and NiTi alloy by adding collagen into SBF (Simulated Body Fluid), of which the component and structure are similar to that of human bone, and further enlarge the application of Ti and NiTi alloy in the biomedical field as hard issue implantation or substitute materials.Formation processes of HA/COL composite coatings on the surface of Ti and NiTi alloy were confirmed by altering the concentrations of collagen and CSBF, and the characteristics of composite coatings were investigated using SEM, XRD, IR, XPS and TEM. At the same time, the growth mechanism of HA/COL composite coatings on the surface of Ti and NiTi alloy was primarily discussed.The results indicated that formation processes of HA/COL composite coatings on the surface of Ti and NiTi alloy were respectively depositing in 0.5g/L CSBF for 12-24h and in 1.0g/L 1.5CSBF for 3d. The composite coatings on the surface of Ti and NiTi alloy were mainly composed of poorly crystallized hydroxyapatite (HA) and collagen.According to the theory and process of biomimetic mineralization, the growth process of HA/COL composite coatings on the surface of Ti and NiTi alloy can be divided to three stages, i.e. pre-nucleation, crystal nucleation and crystal growth. Firstly, electronegative structure and primary crystal nucleus of calcium phosphate were formed on the surface of alloy; then inorganic phases were nucleated on the organic/inorganic interface under the control and influence of collagen; and then crystals were growing under the influence of collagen and the transport and combination velocities of ions in the solution, and finally HA/COL composite coatings were formed on the surface of Ti and NiTi alloy.