Hot Corrosion of Coated Superalloys in a Gas Turbine Environment.

摘要

The final results of a hot corrosion rig test evaluation of 45 coating-alloy combinations are presented. Alloys included in the program were B1900, 713C, IN-100, Rene' 41, SEL-15, U-700, U-710, MAR-M-246, WI-52 and X-40. Rig tests were performed for up to 150 hours at 1650F and 1800F on nickel-base alloys and 1800F and 2000F on cobalt-base alloys in a high-velocity environment obtained from the combustion of JP-5 fuel and air and ingestion of 35 parts sea salt per one million parts air. The coatings tested were commercially available and were essentially beta NiAl or beta CoAl with numerous secondary phases, some of which were formed from the reaction of coating elements and substrate and some of which were formed by elements codeposited with aluminum. The effects of coatings, processing conditions, and long-term high temperature exposures on the mechanical properties of the nickel- and cobalt-base alloys were also evaluated. Data are presented on (1) the low-cycle fatigue life of the ten alloys uncoated as-received, uncoated and coated after 500 hours exposure at high temperature, and (2) the elevated temperature stress rupture properties of the coated alloys after long term exposures and after coating stripping and recoating operations to simulate repair of used blades and vanes. (Author)