Study on Ag bio-coatings on titanium alloy by ultrasonic auxiliary micro-arc oxidation

Putting forward ultrasonic auxiliary micro-arc oxidation new technology(UMAO) to fabricate Ca, P and Ag antibacterial biocoatings on titanium alloy by adding proper AgNO₃ into the electrolyte according to the security value of Ag elements of human bone, which could improve bone repair speeding and decrease probability of implant inflammation. The micro-morphology and structure of coatings were analyzed by SEM, EDS and XRD. The porosity and thickness of the coatings were investigated. The antibacterial property was tested according to AATCC100-2004 and GB/T21866-2008 standards. The bioactivity of coatings and the bone strength were evaluated by hemolytic test in vitro and implanting in animals, respectively. The results indicated that the coatings prepared on titanium alloy by UMAO were porous and contained Ca, P and Ag elements. The porosity and thickness of the coatings were 23% - 26% and 76.22 μm - 81.64 μm, respectively. The coatings were composed of rutile TiO₂ and anatase TiO₂. The hemolytic ratio of coatings contained Ag in vitro was 1.1%. The coatings without Ag and with Ag were both negative in acute systemic toxicity test. The antibacterial ratio of coatings containing Ag was 61% to 92%. The put out strength of implants in animals for 4 weeks, 8 weeks and 12 weeks were 35 MPa, 55 MPa and 59 MPa, which increased by 4.8, 1.3 and 0.3 times compared with Ca, P coatings, respectively. The biocoatings on titanium alloy with Ag had better antibacterial property and bone formation ability.