Cleaning compositions and methods for removing oxides from superalloy substrates

{
  "publication_number": "US10377968B2",
  "country": "US",
  "kind": "B2",
  "title": "Cleaning compositions and methods for removing oxides from superalloy substrates",
  "abstract": "Methods for cleaning a superalloy substrate having engine deposits on its surface are provided. The method may include applying a permanganate solution onto the surface of the superalloy substrate, and applying a ferric chloride based cleaning composition onto the surface of the superalloy substrate. The ferric chloride based cleaning composition includes ferric chloride and at least one of nitric acid and phosphoric acid, such as within a solvent system (e.g., an aqueous solution including water).",
  "claims": [
    "1. A method of cleaning a superalloy substrate having engine deposits on its surface, the method comprising: applying an alkaline solution to the surface of the superalloy substrate; thereafter, applying an acid solution to the surface of the superalloy substrate, wherein the acid solution comprises a citrate-based organic acid; thereafter, applying a permanganate solution onto the surface of the superalloy substrate; and applying a ferric chloride based cleaning composition onto the surface of the superalloy substrate, wherein the ferric chloride based cleaning composition comprises ferric chloride and at least one of nitric acid and phosphoric acid.",
    "2. The method of claim 1, wherein the ferric chloride based cleaning composition comprises ferric chloride, nitric acid, and phosphoric acid.",
    "3. The method of claim 1, wherein the ferric chloride based cleaning composition further comprises a solvent system.",
    "4. The method of claim 3, wherein the solvent system comprises water.",
    "5. The method of claim 3, wherein the ferric chloride based cleaning composition consists of ferric chloride, nitric acid, phosphoric acid, and the solvent system.",
    "6. The method of claim 1, wherein the ferric chloride based cleaning composition comprises about 130 g/L to about 160 g/L ferric chloride, about 95 g/L to about 115 g/L nitric acid, and about 115 g/L to about 145 g/L phosphoric acid.",
    "7. The method of claim 1, wherein the ferric chloride based cleaning composition comprises about 140 g/L to about 160 g/L ferric chloride, about 95 g/L to about 115 g/L nitric acid, and about 115 g/L to about 145 g/L phosphoric acid.",
    "8. The method of claim 1, wherein the superalloy substrate comprises a nickel-containing base metal or a cobalt-containing base metal.",
    "9. The method of claim 1, further comprising: repeating a series of applying the permanganate solution onto the surface of the superalloy substrate and then applying the ferric chloride based cleaning composition onto the surface of the superalloy substrate.",
    "10. The method of claim 9, wherein the permanganate solution comprises potassium permanganate, sodium permanganate, or a mixture thereof.",
    "11. The method of claim 10, wherein the permanganate solution further comprises sodium hydroxide.",
    "12. The method of claim 1, wherein the alkaline solution comprises sodium hydroxide, sodium gluconate, and a surfactant.",
    "13. The method of claim 1, wherein applying the ferric chloride based cleaning composition onto the surface of the superalloy substrate comprises immersing the superalloy substrate into the ferric chloride based cleaning composition.",
    "14. A method of cleaning a superalloy substrate having engine deposits on its surface, the method comprising: applying an alkaline solution to the surface of the superalloy substrate, wherein the superalloy substrate comprises nickel and/or cobalt-containing base metal; and thereafter, applying an acid solution to the surface of the superalloy substrate, wherein the acid solution comprises a citrate-based organic acid; thereafter, applying a permanganate solution onto the surface of the superalloy substrate; and thereafter, applying a ferric chloride based cleaning composition onto the surface of the superalloy substrate, wherein the ferric chloride based cleaning composition comprises an aqueous solution of ferric chloride, nitric acid, and phosphoric acid.",
    "15. The method of claim 14, wherein the ferric chloride based cleaning composition comprises about 130 g/L to about 160 g/L ferric chloride, about 95 g/L to about 115 g/L nitric acid, and about 115 g/L to about 145 g/L phosphoric acid.",
    "16. The method of claim 14, further comprising: repeating a series of applying the permanganate solution onto the surface of the superalloy substrate and then applying the ferric chloride based cleaning composition onto the surface of the superalloy substrate.",
    "17. The method of claim 16, wherein the series is repeated for at least 5 cycles.",
    "18. The method of claim 14, wherein applying the ferric chloride based cleaning composition onto the surface of the superalloy substrate comprises immersing the superalloy substrate into the ferric chloride based cleaning composition.",
    "19. A method of cleaning a superalloy substrate having engine deposits on its surface, the method comprising: applying an alkaline solution to the surface of the superalloy substrate, wherein the alkaline solution comprises sodium hydroxide, sodium gluconate, and a surfactant; thereafter, applying an acid solution to the surface of the superalloy substrate; thereafter, applying a permanganate solution onto the surface of the superalloy substrate; and applying a ferric chloride based cleaning composition onto the surface of the superalloy substrate, wherein the ferric chloride based cleaning composition comprises ferric chloride and at least one of nitric acid and phosphoric acid.",
    "20. The method of claim 19, wherein the ferric chloride based cleaning composition comprises ferric chloride, nitric acid, phosphoric acid, and a solvent system."
  ],
  "description_excerpt": "This invention relates broadly to a method for removing engine deposits from turbine components, in particular turbine and compressor disks and shafts and rotating seals, using a cleaning composition. This invention further broadly relates to a cleaning composition for use in this method that comprises a ferric chloride solution.\n\nIn an aircraft gas turbine engine, air is drawn into the front of the engine, compressed by a shaft-mounted compressor, and mixed with fuel. The mixture is burned, and the hot exhaust gases are passed through a turbine mounted on the same shaft. The flow of combustion gas turns the turbine by impingement against the airfoil section of the turbine blades, which turns the shaft and provides power to the compressor. The hot exhaust gases flow from the back of the engine, driving it and the aircraft forward. The hotter the combustion and exhaust gases, the more efficient is the operation of the jet engine. Thus, there is incentive to raise the combustion gas temperature.\n\nThe turbine engine includes compressor disks and turbine disks (sometimes termed “compressor rotors” and “turbine rotors”) and/or turbine shafts and other rotating parts. A number of blades are mounted to the turbine disks/shafts and extend radially outwardly therefrom into the gas flow path. As the maximum operating temperature of the turbine engine increases, the turbine disks/shafts, rotating seal elements, frames, cases, and static seal elements are subjected to higher temperatures. As a result, oxidation and corrosion of the disks/shafts and seal elements have become of greater concern.",
  "cpc": [
    "C11D 3/046",
    "C11D 11/0029",
    "C11D 2111/16",
    "C11D 3/042",
    "C11D 3/3947",
    "C23G 1/00",
    "C23G 1/085",
    "C23G 1/19",
    "F01D 25/002",
    "F01D 25/007",
    "F05D 2230/72",
    "F05D 2300/175"
  ],
  "ipc": [
    "C11D 7/10",
    "C23G 1/02",
    "C23G 1/14",
    "C11D 11/00",
    "C11D 3/04",
    "C11D 3/39",
    "C23G 1/00",
    "C23G 1/08",
    "C23G 1/19",
    "F01D 25/00"
  ],
  "assignees": [
    "General Electric Co"
  ],
  "inventors": [
    "William Clarke Brooks",
    "Eric Scott Huron",
    "John Matthew Powers",
    "Ian Thomas Goodall",
    "Evan Jarrett Dolley, JR.",
    "David Edward Trider",
    "Zeynep Bolukoglu",
    "Doga Ulutas",
    "Tugba Aydin"
  ],
  "filing_date": "2017-06-12",
  "publication_date": "2019-08-13",
  "grant_date": "2019-08-13",
  "priority_date": "2017-06-12",
  "application_number": "US-201715619990-A",
  "family_id": "64563255",
  "cited_by_count": 18,
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}