How La2O3 Content Effects the Chemical, Mechanical and Physical Properties, and Biological Function of a Calcium Phosphate Bioceramic Coating Produced by Laser Cladding
Y. Bai, Q.B. Liu, P. Xu1, L. Li and Y.Z. Zhu
A calcium phosphate bioceramic coating with β-Ca3(PO4)2(β-TCP) and hydroxyapatite (HA) on a titanium alloy was prepared by means of the laser cladding technique using a CO2 laser. The surface morphology, microstructure and microhardness were analysed. The experimental results indicate that this kind of gradient coating is comprised of bioceramic coating, alloying layer and heat affected zone (HAZ) as well as the substrate. There is an excellent metallurgical bonding among layers. The phases of coating mainly contains CaTiO3, TiO2, β-TCP and HA. The bioactivity of calcium phosphate bioceramic coating is directly related to the amount of synthesizing HA and β-TCP. The rare earth oxide La2O3 can affect the formation of β-TCP and HA. Also, the rare earth oxide La2O3 has great influence on crack susceptibility of the coating. The surface of coating is smooth and the quality is improved by adding La2O3. The bioceramic coating was immersed in SBF to examine its bioactivity for two weeks. The surface of the bioceramic with La2O3 has formed a large amount of bone-like apatite.
Keywords: CO2 laser, titanium alloy, Ti-6Al-4V(TC4), rare earth oxide, La2O3, laser cladding, calcium phosphate ceramic coating, microstructure, microhardness, bioactivity