Eggshell derived hydroxyapatite reinforced nickel electrodeposition via post-supercritical-CO2 approach: Enhanced electrochemical corrosion resistance for seascape applications.

• We proposed post-SC-CO 2 electrodeposition approach of the preparation of Ni/HAP coating. • The post-SC-CO 2 process demonstrates a novel function surpassing both SC-CO 2 and conventional electrodeposition methods. • Post-SC-CO 2 method prepared Ni/HAP coating exhibits 70.86% higher corrosion resistance than conventional methods. The corrosion resistance of brass materials, commonly used in PCBs, MEMS, and the automobile industry, is significantly compromised in chlorine-containing environments prevalent in marine, chemical, and petroleum industries. To address this issue, we proposed the development of a nickel/hydroxyapatite (Ni/HAP) composite coating using a post-supercritical carbon dioxide (post-SC-CO 2) approach, aiming to enhance corrosion resistance compared to conventional methods. The study evaluates the effectiveness of the post-SC-CO 2 process against SC-CO 2 and conventional electrodeposition techniques. The fabricated Ni/HAP coatings are examined through various physico-chemical characterizations to elucidate their surface morphology, phase purity, and chemical compositions. The surface morphology of Ni/HAP coating from post-SC-CO 2 method features micro-cones, indicating SC-CO 2 phenomena at atmospheric pressure. The electrochemical impedance spectroscopy analysis demonstrates that the conventionally electrodeposited Ni/HAP coating attains a corrosion resistance of 4.331 × 104 Ω cm2, 31.59 % enhancement in protection efficiency compared to a standalone Ni coating. In contrast, coatings fabricated using SC-CO 2 and post-SC-CO 2 methods exhibit corrosion protection efficiencies that are 92.97 % and 70.84 % higher, respectively, compared to the conventional electrodeposition technique. These findings highlight the superior performance of the post-SC-CO 2 electrodeposition method in improving corrosion resistance, indicating its significant potential for industrial applications. [ABSTRACT FROM AUTHOR]