METHOD OF COATING HEAT-RESISTANT ALLOYS Russian patent published in 2002 - IPC

FIELD: thermochemical treatment of metals and alloys; applicable in manufacture of aircraft engines for protection of parts operating under unfavorable conditions, for instance, under high temperatures. SUBSTANCE: method consists in thermodiffusion treatment of alloys in powder mixture containing, wt. %: chromium, 30-40; aluminum, 3-12; activator, 0.2-0.5; nickel-yttrium, 4-6; aluminum oxide, the balance up to 100%. Thermodiffusion treatment is carried out by steps in vacuum for at least 9 h, cooled, hardened at temperature of 1180-1280 C for at least 1 h, and tempering at temperature of at least 900 C for at least 2 h. Activator is used in the form of ammonium chloride or ammonium bromide, or aluminum chloride, or aluminum iodide. Nickel-yttrium alloying composition contains 5-20% of yttrium and 80-95% of nickel. Proposed method may be used for application of primary coatings during coating of new parts and also in secondary application of coatings to parts whose surface layer has a diffusion zone preserved after pickling of earlier applied coatings. EFFECT: new heat-resistant coating possessing high strength properties and durability under thermomechanical loads. 4 cl, 2 dwg, 2 tbl