Preparation Technology And Performance Of Ceramic Coatings On Biomedical Ti-6Al-4V Alloys Through Micro-arc Oxidation

In the past few years, the pain of bone and bone organization torture the patients a f physically and psychologically. The bone tissue replacement technology is a more effective method of treatment to such diseases. The focus of the resent research is to strengthen the artificial joint and improve the quality of the patient’s daily life. Ti-6Al-4V alloy has become one of the most widely used metallic materials for medical applications, due to its light weight, high strength, corrosion resistance, high temperature resistance, good biocompatibility, excellent performance. But it still need surface modification and processing because of the poor biological activity.The paper takes the Ti-6Al-4V alloy which is a surgical implant material as the research object. The porous biological ceramic coating containing Ca and P element was fabricated in electrolytic solutions by micro-arc oxidation technology on biomedical Ti-6Al-4V alloys. In this paper, the effect of electrolyte system and electrical parameters for micro-arc oxidation ceramic coating microstructure morphology and elemental composition of the coating were systematic study.The results show that: the best recipe for electrolyte is as follows: K2HPO4·3H2O 6.8g/L, Ca(CH3COO)2,25.8 g/L, EDTA·2Na 20 g/L, Na2SiO3, 6 g/L; corresponding optimal electrical parameters is as follows: voltage parameters 350 V, pulse frequency 600 Hz,oxidation time 10 min. The micro-arc oxidation ceramic coating by this process conditions has high surface porosity, best wear resistance and corrosion resistance, best biocompatibility, porosity up to 15.16% and Ca to P atomic ratio of 1.70, which is very close to that of Hydroxyapatite.Micro-arc oxidation ceramic layer was mainly composed of anatase TiO2 and rutile TiO2. Calcium concentration slightly affects the porosity of the film and the atomic ratio of Ca to P. Adding EDTA·2Na to the electrolyte, Ceramic coating has higher surface porosity and bigger aperture than before. The optimal concentration of EDTA·2Na was 20 g/L. As the current density increased, the pulse frequency reduced and oxidation time increased,the relative content of rutile TiO2 in ceramic coating increase, the film porosity and pore size increase initially and then decrease. When the voltage parameters kept at 350 V, the pulse frequency kept at 600 Hz, oxidation time kept at 10 min., the best wear and corrosion resistance were obtained.