Method for hvof or lpps restoration coating repair of a nickel-base superalloy article

A method for repairing a nickel-base superalloy article comprising the steps of

• providing the nickel-base superalloy article comprising a gas turbine stationary flowpath shroud having flowpath cooling holes therein that has previously been in service, wherein the article has a nominal composition in weight percent of about 7.5 percent cobalt, about 7.0 percent chromium, about 1.5 percent molybdenum, about 5 percent tungsten, about 3 percent rhenium, about 6.5 percent tantalum, about 6.2 percent aluminum, about 0.15 percent hafnium, about 0.05 percent carbon, about 0.004 percent boron, about 0.01 percent yttrium, balance nickel and impurities;
• and
• applying a restoration to a surface of the article by the steps of
• providing a restoration nickel-base alloy, wherein the restoration nickel-base alloy has a nominal composition in weight percent of about 3.1 percent cobalt, about 7.6 percent chromium, about 0.1 percent maximum molybdenum, about 3.85 percent tungsten, about 0.02 percent maximum titanium, about 1.65 percent rhenium, about 0.55 percent silicon, about 5.45 percent tantalum, about 7.8 percent aluminum, about 0.15 percent hafnium, about 0.02 percent carbon, balance nickel and impurities, thereafter
• applying a restoration coating of the restoration nickel-base alloy to the surface of the article by a hyper-velocity oxyfuel metal spray process or a low-pressure plasma spray process, and thereafter
• heating the article with the restoration coating applied to the surface thereof to a temperature of about 2050° F. to diffusion bond the restoration coating to the surface of the article, prior to returning the article to service.

A method for repairing a nickel-base superalloy article comprising the steps of

• providing the nickel-base superalloy article that has previously been in service, wherein the article is a gas turbine stationary flowpath shroud having flowpath cooling holes therein;
• applying a restoration to a surface of the article by the steps of
• providing a restoration nickel-base alloy, thereafter
• applying a restoration coating of the restoration nickel-base alloy to the surface of the article by a hyper-velocity oxyfuel metal spray process or a low-pressure plasma spray process, and thereafter
• heating the article with the restoration coating applied to the surface thereof to a sufficiently high temperature to diffusion bond the restoration coating to the surface of the article;
• and
• redrilling the cooling holes,
• wherein the restoration nickel-base alloy has a composition in weight percent of 0.01-0.03 percent carbon, 0.1 percent maximum manganese, 0.5-0.6 percent silicon, 0.01 percent maximum phosphorus, 0.004 percent maximum sulfur, 7.4-7.8 percent chromium, 2.9-3.3 percent cobalt, 0.01 percent maximum molybdenum, 3.7-4.0 percent tungsten, 5.3-5.6 percent tantalum, 0.02 percent maximum titanium, 7.6-8.0 percent aluminum, 1.5-1.8 percent rhenium, 0.005 percent maximum selenium, 0.3 percent maximum platinum, 0.01-0.02 percent boron, 0.03 percent maximum zirconium, 0.12-0.18 percent hafnium, 0.1 percent maximum niobium, 0.1 percent maximum vanadium, 0.1 percent maximum copper, 0.2 percent maximum iron, 0.0035 percent maximum magnesium, 0.01 percent maximum oxygen, 0.01 percent maximum nitrogen, balance nickel with other elements 0.5 percent maximum.