Tailorable Environmental Barrier Coatings for Super Alloy Turbine Components in Syngas

72505-Integrated gasification combined cycle (IGCC) coal combustion has the potential for significantly improving the efficiency of converting coal power and for reducing emissions. However, corrosion in the syngas environment limits the lifetime of IGCC components and increases cost. This project will develop low-cost, dip-coated ceramic oxide coatings to prevent the high temperature corrosion of super alloys used in turbine engines that operate in syngas environments. The dense ceramic oxide coating will function as environmental barrier coatings (EBC) on super alloys, providing protection in the aggressive and corrosive conditions found in high temperature turbine applications. In Phase I, the feasibility of applying well bonded graded coatings of oxide compositions was demonstrated. The coatings were in the 2 to 60 micron thickness range, and were crack free and dense. It was demonstrated that the graded oxide coating have excellent corrosion stability in atmospheres composed of syngas, coal and fly ash impurities, and sulfur gas. In tests lasting one thousand hours, the coating showed good thermo-mechanical stability while protecting the alloy from corrosion. In Phase II, longer term exposure tests (10,000 hours) of the oxide coating on super alloy will be demonstrated in corrosive and abrasive environments. A fabrication process for oxide coatings on complex alloy components for use in IGCC systems will be developed. A partnership with a commercial synthetic gas company, to test the coating in real IGCC gas streams, will maximize the chances of developing a commercial viable oxide coating technology. Commercial Applications and Other Benefits as described by awardee: The new coatings would protect the turbine components and process equipments exposed to high temperature syngas environments in IGCC systems, and also would be applicable to other chemical, aerospace, and military processes. The coatings should also be suitable for other applications requiring high temperature corrosion resistance for super alloys, for example Kraft recovery boilers.