Studies On The HA Bioceramic Coating Material

Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂,HA) bioceramic coating material was the hotspot of the researches on the bioceramics. It has very good bio-compatibility with bone and certain mechanical property, and is being widely used in medical bone prostheses and substitutions.In this research, hydroxyapatite powder was prepared by the self-combustion method. Optimum technical parameters were achieved through adjusting the ratio of reagents, temperature of combustion, and so on. And the structure, size, and surface area of the HA powder were analyzed. Results showed that the optimum technical parameters of the mole ratio of Ca/P and Ca²⁺/(citric acid) were 1.67 and 1 respectively, and the n(H₂O)/n(Ca²⁺) ratio was 32.5. The pH value of the mixture was between 2～2.5. Then the mixture was heated at 80℃to form gel before was fired at 350℃, and was further calcined at 750℃for 1 hour to form the purer HA powder with fine particles. XRD analysis showed that the sample is pure-phase HA. The average particle size measured by granulometer was 1.830μm, and the surface area was 8.153m2 /g.Titanium oxide film was prepared by anode oxidation. And the thickness of titanium oxide film increased with the increasing voltage and time of anode oxidation. Also the rigidity of titanium oxide film increased with the increasing electrolyte concentration, voltage, and time of anode oxidation. Results showed that titanium oxide film with fine morphology can be obtained using 20% H2SO4, voltage of 120V, time of 10min.HA coatings on the titanium surface with anodic oxidized film by both electrophoresis co-deposition and autoclave treatment methods were prepared. Effects of electrolyte concentration, voltage, time and temperature on the anodic oxidized film and HA coating were studied. Results showed that HA coatings with fine morphology can be obtained using HA content of 15g/l, voltage of 250V, time of 3min for the electrophoresis co-deposition method, and using voltage of 55V, time of 60min, autoclave treated at 200℃for 8 hours and calcined at 700℃for 4 hours for the autoclave method.