Recovery Act - Nanocomposite Coatings for Life Extension in Zinc Pot Rolls

The coating of steel sheet by continuous hot dipping in a molten metal bath of zinc or in a Zn-Al melt is the most efficient and economical method for providing corrosion protection to steel sheet. However, the processing of metals in liquid metal results in the reaction of the liquid metal with the tooling and can result in dross build-up and damage to the work piece. In order to address this, self-lubricating, nanocomposite coatings are being proposed to minimize adhesion of the liquid metal to the tooling as well as to reduce system wear and corrosion. The addition of solid lubricants to the metal-working tooling can decrease contact and dynamic friction which results in reduced adhesion of the work material to the tooling. The addition of ceramic nano-particles serves to enhance the wear and mechanical properties of the coatings. During the Phase I project several coating compositions were evaluated for wear and liquid metal corrosion. Initial wear properties were evaluated using ASTM G-65 Rubber Wheel Sand Erosion testing. Commercial Applications and Other Benefits: The coatings were evaluated for liquid metal adhesion and corrosion by immersion of coated coupons in a zinc bath. During the Phase II project, coating composition and application parameters will be optimized, coating durability in other liquid metal and metal-working environments will be studied, and a set of zinc pot roll bearings will be coated for testing in a galvanizing plant. Coating durability will be evaluated using a sub-scale zinc galvanizing simulator where both the pot roll face and bearings can be tested. Test parameters will be determined by an industry panel. Nano-composite coatings containing solid lubricant materials can be used in a variety of applications including die-casting, metal forming, metal trimming, diesel engines, and aerospace applications. Other potential applications include areas where elevated temperature wear is an issue or where sliding wear is prevalent.