Preparation and properties of Ag-loaded zinc oxide antibacterial coating on medical cobalt-chromium alloy

Medical cobalt-chromium alloy has been widely used in oral implants due to its excellent mechanical properties, corrosion resistance, etc. However, its antibacterial properties should be improved as an implant. In this paper, nano-zinc oxide and Ag-loaded zinc oxide coating were prepared on cobalt-chromium alloy using the hydrothermal and photoreduction methods, and the influencing factors of the preparation process were studied. The effects of pH, hydrothermal temperature and time on the morphology of nano-sized zinc oxide were investigated. The results show that the zinc oxide has satisfactory morphology when the hydrothermal time is 3.0 h, hydrothermal temperature is 100 ℃, and pH value is 9.5. The effects of light intensity, illumination duration and AgNO3 concentration on the size and dispersion of silver nanoparticles on the Ag-loaded zinc oxide were studied. The results show that the Ag-loaded zinc oxide has satisfactory morphology under the illumination intensity of 0.6 W/m2 , illumination duration of 60 min and AgNO3 concentration of 1.0 mol/L. By analyzing the morphology, phase, quality and thickness of zinc oxide and Ag-loaded zinc oxide coating, it is found that the needle-like zinc oxide array is uniformly loaded with silver particles. The average thickness of the coatings is 6.80 μm, and the average weight is 1.67 mg. The antibacterial test shows that the Ag-loaded zinc oxide coating has better antibacterial performance than the pure zinc oxide coating, both of which were better than the blank control sample.