LowCost Alloy Coatings by Pulsed Electrodeposition for Combustors

A need has been identified for production of lowcost biomass combustors with enhanced durability against high temperatures and corrosive environments. Biomass represents an abundant, renewable fuel source with significant unrealized potential to supplant nonrenewable fossil fuels in providing for the Nation’s energy needs. Combustors are typically fabricated from low cost steels, which do not achieve acceptable lifetimes in biomass combustion applications. Interest has been expressed in novel, lowcost approaches for fireside surface modifications of the base metal that will provide the desired thermal and chemical resistances. General statement of how this problem is being addressed: Identify and develop corrosionresistant coatings for the inner surfaces of biomass combustors to provide the necessary resistance to high temperatures (600900 °C) and corrosion from attack by alkali halides and water. Demonstrate the capability of pulsed electrodeposition to fabricate high performance, long life coatings, with scaleup to coating electrodeposition and testing of combustor bodies on a demonstration scale. What was done in Phase I? Phase I demonstrated a cost effective, scalable, flexible manufacturing process for application of highquality coatings to low cost materials for improved lifetime and durability during operation of biocombustors. Specifically, a range of coating compositions of cobaltnickel with chromemolybdenumiron were deposited onto 1”x4” coupons, and surpassed a 500 hr accelerated high temperature corrosion test. A preliminary analysis showed that pulsed electrodeposition is economically viable for production of a NiCr coating that has the potential to greatly improve biocombustor component lifetime. What is planned for the Phase II project? 1) Optimize cobaltnickel with chromemolybdenumiron coatings on lowalloy materials to meet the performance specifications of biomass combustors, specifically longterm adhesion and corrosion resistance in relevant high temperature environments, 2) Demonstrate enhanced corrosion resistance compared to the base alloy in relevant environments, 3) Build an alphascale prototype and coat biomass combustor parts to demonstrate scalability, 4) Design a system for processing multiple geometries, and 5) Update the economic analysis and continue commercialization efforts. Commercial Applications and Other Benefits: Economical application of corrosionresistant alloy coatings to biomass combustors has the potential to facilitate enhanced economics and utilization of biomass as an energy source. Improved combustor technology will decrease the costofownership; integration with other technological advances would presumably increase the extractible energy per mass of fuel, further enhancing costeffectiveness. The technology has the potential to facilitate a transition of largescale electrical generation to renewable biomass. The potential global market for generation (steadily increasing from 14.6 petawatthours of fossilfired generation in 2011) is substantial. Key Words alloy coatings; electrodeposition; biomass combustors; renewable resource, manufacturing Summary for Members of Congress: This project will develop an economical method for applying corrosionresistant coatings to the inner surface of chambers for burning wood, grass, straw, and other plant matter. These coatings will increase the lifetime of the burners, decreasing the cost of ownership for biomass combustion equipment.