Study On Subsonic Thermal Spraying (HA-BG)/(Ti-G) Compound Biocoatings Characteristics

Fabrication technique of bioceramic coatings on the Ti alloy has been emphasis in the biomaterial field as one kind of hard tissue in plantation recently. But the differences between metal matrix and ceramic coatings, especially for heat dilatability and elastic module are so large that they may cause ceramic coatings to rupture or fall off. In order to resolve the problems, the method in which the bioactive glaze glass was added to the Ti powder to relax the stress and enhance the bonding between coatings and matrix. Bioglass (BG) was introduced to regulate bioactivity of coatings during the preparation process. The compound coatings with bioactivity were prepared and their mechanical performance, composition, microstructure and interface features were further investigated in the present research.Hydroxyapatite(HA), bottom glaze glass(G), bioglass(BG) powders and complex powders were prepared firstly. The results showed that, fine original and dispersing powders by spraying dryness technique could obtain homogeneously, and avoided powder aggregating. The melt ing and smashing bottom glaze glass and bioglass(BG) by calcining could form Ca5(PO4)3F and Ca5(PO4)3F phases as a new type of biomaterial, which possessed the properties of excellent bone connection and good stabilityTi-G bottom layer prepared by subsonic thermal spraying technique meet with bonding strength requirement was. The results indicated that bonding strength and microstructure of Ti/G bottom layer were dependent of complex powder granularity, bottom glaze glass content, powders feeding and crystallization treatment. After 700℃crystallization treatment, Ti-G bottom layer consisted of main anatase and minor rutile TiO2, and some TiN. The precipitation of crystal TiO2 at coating cracks in the coatings benefited to heal up cracks and prevent from dissolving poisonous material to the organism. Adding bottom glaze glass, which granularity was less than 50μm, could produce Na2Ti6O13 and Na2Ti6O13 owning bioactivity and resistance corrosive properties on the coating surface. After crystallization treatment, the residual stress of Ti/G bottom layer was significant to enhance the bonding strength of coating, which lay on the content and granulation of the bottom glaze glass among compound powders.Bioactive coatings with 8ti2g as bottom layer and ha-bg as working layer were prepared by subsonic thermal spraying technique. The results showed that bg made action of dispersion strengthen therefore the bonding strength of the coatings was enhanced. The dispersion strengthen degree depended on the bioglass granulation. The coating structure decided by the compound powders granulation. Ha-bg coating through 700℃crystallization treatment, formed primary crystal ha, and produced na2ca(po4)f by adding bg. When ha-bg granulation was less than 10μm the crystal ha grain size decreased, and bg restrained ha grain growth.