Rhodium-containing superalloy coatings and methods of making same
AssigneeChromalloy American Corporation
InventorsGregor Baladjanian, Eugene V. Clark
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Abstract
Superalloy structures, such as high temperature components for jet engines and the like, are provided with aluminum-containing diffusion coatings enabling guantum extensions of service life through unique distributions therein of rhodium. The rhodium is prediffused into the alloy structure, and the resultant distribution minimizes aluminum migration into the structure and thus maximizes protective coating performance.
Claims19
Method of forming a diffusion coating on a nickel base or cobalt base alloy structure which includes applying onto the structure surface to be coated an adherent layer of rhodium having a depth equal to between 5 percent and 35 percent of the intended depth of the diffusion coated base, prediffusing said rhodium layer into the structure surface under a nonoxidizing nonreactive atmosphere at a temperature between about 1400.degree.F. and 2350.degree.F., and thereafter diffusing aluminum into the prediffused rhodium containing structure surface at an elevated temperature and for a time sufficient to form with the rhodium and base metal said diffusion coating, whereby as a result of said prediffusing said alloy structure has a diffusion coating the inner boundary portion of which is relatively rich in rhodium.
Cobalt or nickel base alloy structure having a diffusion coating, said coating consisting essentially of between 15 and 40 percent by weight aluminum, from 5 to 50 percent by weight rhodium, and the balance base metal, the inner boundary portion of said diffusion coating being between about 5 percent and 20 percent of the ultimate diffusion coating depth and relatively rich in rhodium to contain up to about 80 percent by weight rhodium, said diffusion coating being formed by prediffusing a rhodium coating having a thickness between 5 and 35 percent of said ultimate diffusion coating depth into the structure surface under a nonoxidizing nonreactive atmosphere at a temperature between about 1400.degree.F. and 2350.degree.F., and thereafter diffusing aluminum into the diffused-rhodium-containing structure surface.
Dependencies are inferred from the claim text.