Effect of coating composition on the micro-galvanic dissolution behavior and antifouling performance of plasma-sprayed laminated-structured Cu[sbnd]Ti composite coating

Marine biofouling is a critical issue significantly deteriorating the service performance of marine infrastructures. Thus, development of an effective and long-lasting antifouling coating is highly desirable. Here, a laminated-structured copper-titanium (Cu[sbnd]Ti) antifouling coating was fabricated by plasma spraying of mechanically blended Cu and Ti powders. The coating was designed to enable controlled release of Cu ions from Cu/Ti micro-galvanic cells and thus to achieve effective and long-term antifouling performance. The effect of Cu[sbnd]Ti coating composition on its micro-galvanic dissolution behavior and antifouling performance was systematically investigated. The coating compositions were changed by varying Cu content from 8.1 to 65.2%. Analysis of scanning Kelvin probe force microscopy and long-term immersion test results indicated that Cu loading within Cu[sbnd]Ti coating exhibited little influence on the formation and mechanism of Cu/Ti micro-galvanic cells. However, the Cu ions release rate and antifouling duration increased with increasing Cu loading. The antifouling efficiency of Cu[sbnd]Ti coating against bacterial survival increased with the increase in the Cu loading from 8.1 to 19.2% and it reached ~100% when Cu loading exceeded 19.2%. Electrochemical test results revealed that with the variation of Cu loading, the amount of micro-galvanic cells rather than the dissolution rate of each single micro-cell played a more prominent role in deciding the total Cu dissolution rate; and consequently, the Cu ions release rate and self-polishing rate. These results may guide the advanced design of versatile Cu[sbnd]Ti antifouling coatings with environment-friendly, durable, and remarkable antifouling capability for different practical requirements in marine engineering through facilely tailoring coating composition.