Gradient Bioceremics Composite Coating Produced By Wide-Band Laser Cladding On Surface Of Ti Alloy And Its Cell Biocompatibility

Hydroxyapatite(HA) has excellent biocompatibility and bioactivity, however, the mechanical properties of HA is not satisfied, because its flexural strength and fracture toughness are lower than that of bone. It is restricted to be applied on the human body. Although Ti and its alloy has excellent mechanical properties, they belong to biological implanting material, there is little bio activity. Due to its favorable biocompatibility and mechanical properties, hydroxyapatite-coated Ti alloy has been accepted as one of the most promising implanting materials for orthopaedic and dental applications.In this paper, as to problem on preparing bioceramic coating, wide-band laser cladding and gradient design thought are adopted, biocompatibility and bioactivity of HA coating is increased by adding different kinds of rare earths(RE) class and contents, the bioceramic coating with HA andβ-TCP is fabricated on the Ti alloy, the microstructure of gradient coating with bioactivity was studied with the help of SEM , XRD and microhardness analysis. At last, the biocompatibility of bioceramic coating was estimated from the cytobiology level. The experimental results show that the gradient bioceramic coatings which have excellent chemical metallurgy bonding on the interface consist of metal base, alloy coating and bioceramic coating. The rare earth oxide(CeO₂ and Y₂O₃) can reduce crack susceptibility of coating and refine grainsize during wide-laser cladding. Secondly, CeO₂ and Y₂O₃ plays an important role in inducing to synthesize HA andP-TCP during laser cladding . Thirdly, When Ca/P is 1.5, the ceramic structure is smaller than the 1.4 of Ca/P, and its crystalline state is good. And different CeO₂ contents lead to different amounts of synthesizing HA+β-TCP. When Ca/P is 1.4 and the addition of CeO₂ reaches to 0.4wt.%, the amount of synthesizing HA andβ-TCP is the most; when Ca/P is 1.5 and the amount of CeO₂ is between 0.2wt.% and 0.4wt.%, the the amount of synthesizing HA and P-TCP is also the most.the .fourthly, the coating containing CeO₂ and Y₂O₃ has no toxic effect. The active ceramic phase amounts of calcium(Ca) and phosphorus(P) base on the surface of bioceramic coating effect the appreciation of osteoblastic cell. The bioceramic coating containing CeO₂ and Y₂O₃ has better cell biocompatibility than Ti alloy. When Ca/P is 1.4 and the addition of CeO₂ reach to 0.4wt.%, the amount of osteoblastic cells is the most, and the cell amount on coating withCeO₂ is more than that of coating with Y₂O₃.