Formation Of HA/BMP,HA/COL/BMP Composite Coatings On The Surface Of NiTi Alloy

This work is mainly attributed to form HA/BMP, HA/COL/BMP composite coatings on the surface of NiTi alloy after adding Bone Morphogenetic Protein (BMP), Collagen (COL) into Simulate Body Fluids (SBF) and Modified Simulate Body Fluids (MSBF). The components and micrograph of calcium phosphate coatings were investigated by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), and Infrared Spectroscopy (IR). Modified process conditions and the growth mechanism of HA/BMP, HA/COL/BMP composite coatings on the surface of NiTi alloy was discussed.The results indicated: When the concentration ranged from 10mg/L to 100mg/L, It will promote the coating formation. After deposited in MSBF, CMSBF with 50-100mg/L BMP for 3days, It formed uniformity meshy composite coatings on the alloy surface.Crystal was flake perpendicular to the substrate surface,sized between 100-300nm. Protein in the coatings interacted with Ca2+. The morphologies of BMP in the coating is granular, and the collagen is fibriform.The growth process of composite coating on the surface of NiTi alloy could be divided into two stages, i.e. crystal nucleation and crystal growth. With protein in SBF, critical nucleus size was reduced, growing time was delayed and quantity of nucleus was increased, which was propitious to form mesh structure. Functional group of protein interacted with Ca2+ primarily then absorbed PO43-. Finally composite coatings were formed on the surface of NiTi alloy.