Enhancement of coating characteristics via improved plasma electrolytic oxidation set‐up

The plasma electrolytic oxidation process involves high‐temperature operations and exposed to corrosive chemicals. Thus it requires stringent experimental set‐up to produce uniform and high‐quality coatings. This study proposes an enhancement to the current plasma electrolytic oxidation experimental set up to improve: 1) electrode holder; 2) cathode‐anode electrodes, and 3) water‐cooling system. In this paper, the focus is dedicated to the first two items. For the first item, the redesigned electrode holder is developed using 3‐dimensional software. For the second item, results due to cathode via stainless container as well as carbon electrode are discussed. The performance of the new set‐up plasma electrolytic oxidation is compared with the old one by analysing the microstructure and the mechanical properties of titanium dioxide coatings formed on a titanium aluminium vanadium alloy substrate using both set‐ups. Surface morphology shows that the coating produced using the new set‐up is thicker, denser and has lower porosity as compared to the coating deposited using the old set‐up. The mechanical properties of hardness and adhesive strengths of the coating are also improved in the new set‐up. Thus, the use of this set‐up is recommended for improved coating performance to produce a uniform coating having enhanced mechanical performance. With the improved set‐up of plasma electrolytic oxidation, a uniform thin titanium dioxide coating is formed on the titanium alloy substrate. Based on the field emission scanning electron images, the coating produced under the new set‐up exhibits lower porosity as observed by the less number of black contrast. The micro‐hardness measurement also indicates that the coating has greater hardness compared to the coating produced under the old set‐up.