Analysis of the corrosion and wear of WC-10Co-4Cr + GNPs coating applied to HSLA DH-36 steel using HVOF

Abstract

High strength low alloy (HSLA) steels offer unique properties and features that show their utility in harsh conditions. Wear and corrosion are concerns when using HSLA steel in shipbuilding and marine environment. In such harsh conditions, WC-10Co-4Cr is a suitable candidate for applying a protective coating to HSLA steel using High Velocity Oxy-Fuel (HVOF) to improve wear and corrosion resistance. The addition of graphene nano-platelets (GNPs) to WC-10Co-4Cr powder increased its mechanical qualities due to its unique properties such as low wear and excellent corrosion resistance. In this work, WC-10Co-4Cr + 3% GNP was coated on laser-treated DH-36 steel. The corrosion potential for these coatings on pre-laser textured with pitch-to-diameter ratio 1.67 was −0.437V compared to the pristine DH-36 was −0.821V; while corrosion current density was 0.143 × 10−3 & 5.362 × 10−6, respectively. Finally, the dry sliding wear test using the Pin-on-Disc (PoD) method, microhardness using the Vickers Indentor, and corrosion resistance using a potentiometer were utilised to analyse the coated surface. The wear resistance of steel coated with WC-10Co-4Cr + 3% GNPs was about 1.5 times compared to pristine substrate. Microstructure and morphology of corroded surfaces were examined using FE-SEM. The results reveal that GNPs act as a solid lubricant, improving the surface’s wear resistance.