Cailiao Baohu (Sep 2022)
Protection Against Biological Fouling of TB10 Titanium Alloy by Cold - Sprayed Cu (Ag) Coating
Abstract
For improving the biological fouling resistance of TB10 titanium alloy, copper (Cu) and copper - silver (Cu - Ag) coatings were prepared on its surface by cold spraying. The mass fraction of silver in the powder used for manufacturing Cu - Ag coating was 10%. The phase composition of the coatings was detected by X - ray diffraction. The growth trend of sulfate - reducing bacteria in the solution was characterized by using a spectrophotometer to measure the absorbance at 550 nm. Scanning electron microscopy was used to observe the surface morphology of the coatings immersed in the culture medium of sulfate - reducing bacteria for 3, 7 and 12 days for the purpose of evaluating the biological fouling resistance of the coatings. In addition, the polarization curve of the samples in simulated seawater was tested by electrochemical workstation in order to characterize the corrosion resistance of the coatings. Results showed that in the immersion experiment, the number of bacteria adsorbed on the surface of titanium alloy was the largest, and the samples with Cu and Cu - Ag coatings possessed a certain biologic fouling resistance. The Cu - Ag coating had the best biological fouling resistance as the addition of silver promoted the rupture and death of bacteria. Furthermore, the corrosion potentials of the samples of Cu coating, Cu - Ag coating and original TB10 alloy were -300.0, -209.1 and -144.9 mV, and their self - corrosion current densities were 4.16×10-5, 1.81×10-5 and 1.55×10-7 A/cm2 respectively. Comparing with the original titanium alloy, the samples covered with Cu coating and Cu - Ag coating possessed lower corrosion potential and higher corrosion current density, indicating that the coatings could provided some anodic protection on the substrate. After the sealing treatment, the corrosion resistance of coated samples was improved, and the corrosion current density decreased by 2 orders of magnitude. Generally, Cu and Cu - Ag coatings prepared by cold spraying on the titanium alloy surface improved the biological fouling resistance of the titanium alloy. Besides, silver could generate a highly active bactericidal ion layer on the surface, making the antibacterial effect sustained and effective. Furthermore, the durability of the coating could be improved by sealing treatment.
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