| 摘要 |
PROBLEM TO BE SOLVED: To remove sludge (Cr2O3/NiO) without any influence on a base material by utilizing decomposition reaction by supplying gaseous hydrogen fluoride into an air cooling hole of a gas turbine blade formed of a heat resisting alloy material having the base material of a cobalt base alloy or a nickel base alloy and containing chrome(Cr) more than designated. SOLUTION: As apparent from the standard generation free energyΔG, Cr2O3 or NiO remaining on the inner wall surface of an air cooling hole is liable to cause a decomposition reaction (3HF+1/2 Cr2O3=CrF3+3/2 H2O, 3HF+NiO=NiF2+H2O) with a temperature rise. WhenΔG is a negative value (under 600 deg.C), the reaction is stopped or reverse reaction is caused. On the other hand, since the heat resisting cobalt base or nickel base alloy material which is the base material of a gas turbine blade has a solution temperature of 1100 to 1150 deg.C, the temperature for causing the decomposition reaction is held below 1100 deg.C. When gaseous hydrogen fluoride is supplied into the air cooling hole of the gas turbine blade heated to 600 to 1000 deg.C, the decomposition reaction occurs to thereby discharge sludge as reaction product (CrF3/NiF3) and water vapor (H2O) to the outside.
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