Nanoparticle-Enhanced Plasma-Electrolytic-Oxidation of Al and Ti Alloys for Hard Chrome Replacement

NanoCoatings, Inc. (NCI) and South Dakota School of Mines & Technology (SDSMT) propose to demonstrate a unique high-voltage anodize process, Plasma Electrolytic Oxidation (PEO), to produce crystalline-oxide conversion surfaces on Al-alloy (e.g., 2024 Al) and Ti-alloy surfaces that provide comparable or higher corrosion and wear-resistance over hard Chromium (Cr) plating. The intended application is to replace Cr-plated Al and Ti parts on the Air Force Sikorsky Combat Rescue Helicopter. PEO-treated surfaces offer a unique combination of excellent adhesion (from conversion of the part surface with no abrupt interface), high wear-resistance from the hard crystalline-alumina material and good corrosion resistance from the noble crystalline-alumina surface. This unique conversion process uses environmentally-friendly, non-hazardous electrolyte solutions that reduce handling and disposal costs. NanoCoatings will demonstrate the intentional additions of selected chemicals (e.g., glycerin) and selected nanoparticles (e.g., oxide, carbide, or nitride) to increase the stability of the process, refine the surface porosity (improved corrosion resistance), and increase the toughness of the crystalline-alumina surface. A systematic test program on PEO-converted Al and Ti alloy surfaces will be conducted by SDSMT to characterize the PEO microstructure, morphology, corrosion, and wear-properties.