A study on the preparation, antimicrobial property and durability of Ag-based coating deposited by electric spark discharge with silver nitrate solution

With the increased use of antimicrobial drugs, the threat of antimicrobial resistance is becoming a thorny problem. Preparing silver (Ag) based coatings with a certain antimicrobial property on the implants has emerged as an alternative strategy to reduce the use of antibiotics. However, how to prepare antimicrobial Ag-based coatings with good durability simply and efficiently is still an urgent problem to be resolved. In this research, a novel preparation method of Ag-based coating using traditional electrical spark discharge (ESD) deposition technique was proposed. Silver nitrate solution instead of traditional ESD working media and a flexible titanium brush electrode instead of silver brush electrode were used to prepare the Ag-based coating. Besides, a microcolumn array structure was fabricated on the substrate to improve the antimicrobial efficacy and durability of the coating. The experimental results showed that a relatively complete Ag-based coating was prepared successfully on the micro-column textured surface of titanium alloy substrate. Antimicrobial tests showed that the antimicrobial efficacy of the coating sample with micro-column array against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coil) increased by more than 95 %. The ultrasonic vibration tests and wear tests confirmed that the coating sample with micro-column array possessed good adhesion ability and durability. The deposition of Ag in the coating can be attributed to the decomposition of AgNO3 during the electrical spark discharge process.