HVOF Applied ‘Flash’ Coatings for Hard Chrome Replacement Application of Hydraulic Rods

Hard chrome plating has long been a popular method for increasing the durability and wear resistance of various components due to its cost-effectiveness and efficiency. However, increasing environmental regulations due to hexavalent chromium toxicity have threatened its future as a low-cost coating solution. Conventional thick HVOF carbide coatings have been used for hard chrome plating replacement in applications such as hydraulic rods, actuators and similar components for oil and gas, mining, and aircraft landing gear. The overall cost of such HVOF coatings is higher compared to electroplated hard chrome for several reasons including the material/process cost, as well as greater overall coating thickness and post-deposition finishing requirements (dimensional grinding and subsequent polishing) to achieve surface characteristics that meet application criteria. In this work, the feasibility of depositing flash type coatings (thin, dense and smooth) using HVOF is undertaken for an engineered composition of WC-CoCr along with a condensed post-coating finishing technique to improve cost effectiveness. Spray metrics, coating microstructure, adhesion and corrosion performance are addressed to achieve a solution for hydraulic rod applications. HVOF applied ‘flash’ coatings offer a robust, environmentally friendly alternative to hard chrome, with advantages in wear and corrosion resistance, precision in application, and reduced environmental impact.