IMPROVED COATING COMPOSITIONS AND ITS IMPROVED METHOD FOR THE PROTECTION OF SUPERALLOYS AT ELEVATED TEMPERATURES

摘要

The coating resists oxidation and corrosion at high temperatures, and contains 5-40 wt.% Cr, 8-35 wt.% Al, 0.1-7 wt.% Si, 0.1-2 wt.% Hf, up to 2 wt.% of an element reacting with O2 and in IIIB of the periodic system, a lanthanide and/or an actinide, and the balance Ni and/or Co. For Ni-base substrates, the coating contains (I) 15-25 wt.% Cr, 10-20 wt.% Al, up to 30 wt.% CO, the rest Ni, but with 15-25 wt.% Co when good ductility is required. Another coating contains (II) 15-35 wt.% Cr, 10-20 wt.% Al, up to 35 wt.% Ni, balance Co. For use above 1150 deg.C, the coating contains up to 2 wt.% Si. For coating gas turbine parts made of Ni-base superalloys, coating (I) is used, whereas coating (II) is used for Co-base superalloys.