| In-situ synthesis ceramics were prepared on Ti6A14V (TC4) surface by micro-arc oxidation (MAO) technique. The optimal preparation technology for preparing MAO ceramic films were confirmed by means of X-ray Photoelectron Spectroscopy (EDS), X-ray diffractometer (XRD) and scanning electron microscope (SEM), etc. Results by optimizing the experimental conditions, we got the optimum parameters for MAO ceramic film. The MAO ceramic film got before was used for carrying forward our animal experiment which cooperated with Kunming Medical University. Biocompatibility and the early promote bone healing performance of the MAO ceramic film were tested by cellular compatibility test, tissue slice and X-ray test.The main indexes of constant voltage orthogonal experiment and constant current response surface are film thickness and corrosion resistance. Thickness and roughness of the film increase with increasing of electrolyte concentration, forward current, forward voltage and time; and the corrosion resistance is mainly related to the frequency, current, voltage and time. The temperature and voltage during the MAO process is increase with increasing of the electrolyte concentration, and there are more Ca2+、PO43- ions under effect of electric field to diffusion and migrate to surface of the anode to participate in forming the ceramic film; the bigger current and bigger voltage are necessarily go with bigger discharge energy, which always causing breakdown of film for twice or many times, and the micro pores become bigger, the melt become more and the surface become more irregularity. There is more bioactivator form when the time is longer, and the longer time is also advantage to crystallization of the HA, at beginning of the oxidation, film thickness increase fast, with time prolong, the increase rate decrease, the too long time can cause the outer loose film fall off from the interface; The lower single discharge energy is along with the greater frequency, and the thickness is smaller, the pores on the surface is smaller and the surface is more uniformity. The high roughness and porosity of surface got by MAO is advantage for attached growth of osteoblast, content of Ca and P increase with increasing of frequency, rutile is stable structure of TiO2, and which is transformed by anatase under the high tempreture. The differences of laws got by constant voltage and constant current are very small, but the ceramic morphology got by constant current is more evenly.Through the constant voltage orthogonal test and its optimization, we got the optimum parameters:the voltage is 500V, Ca/P of electrolyte is 1.67, the frequency is 300Hz and the MAO time is 20min; the optimization for constant current process parameters are:the current is 2.5A, Ca/P of electrolyte is 2.5, the frequency is 300Hz and the MAO time is 15min.The MAO ceramic films prepared under different experimental conditions were implanted into distal femur of Japanese rabbit, then take samples from the executed animal after 4W,12W and 24W. Results showed that, there is no phenomenon of infection and bone resorption after implanting, and there are new bone cells growth after implanting, and the biological combination- bone growth gradually formed, the implant materials has a good biological activity. |
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