Powder processing method

{
  "publication_number": "US8357251B2",
  "country": "US",
  "kind": "B2",
  "title": "Powder processing method",
  "abstract": "A powder processing method includes degassing a metallic powder in a rotating chamber that is evacuated to a sub-atmospheric pressure. The method may also include storing the metallic powder in a rotating storage chamber that is pressurized to a super-atmospheric pressure with a dry cover gas.",
  "claims": [
    "1. A powder processing method comprising: degassing a metallic powder in a chamber that is evacuated to a sub-atmospheric pressure; agitating the chamber that is evacuated to a sub-atmospheric pressure; and after the degassing, storing the metallic powder in a storage chamber that is pressurized to a super-atmospheric pressure with a dry cover gas.",
    "2. The powder processing method as recited in claim 1, wherein the degassing includes agitating the metallic powder using baffles within the rotating chamber.",
    "3. The powder processing method as recited in claim 1, including conducting the degassing at a temperature of 300-800° F.",
    "4. The powder processing method as recited in claim 1, including conducting the degassing at a temperature of 350-600° F.",
    "5. The powder processing method as recited in claim 1, including conducting the degassing in a first phase at a first temperature followed by a second phase at a second, greater temperature.",
    "6. The powder processing method as recited in claim 5, wherein the first temperature is 300-600° F. and the second temperature is 600-800° F.",
    "7. The powder processing method as recited in claim 1, further comprising agitating the storage chamber.",
    "8. The powder processing method as recited in claim 1, further comprising rotating the storage chamber.",
    "9. A powder processing method comprising: degassing a metallic powder in a rotating chamber that is evacuated to a sub-atmospheric pressure; and prior to the degassing, forming the metallic powder at super-atmospheric pressure and containing the metallic powder in a catch chamber at the super-atmospheric pressure.",
    "10. The powder processing method as recited in claim 9, including maintaining the catch chamber at a dew point less than −85° F.",
    "11. The powder processing method as recited in claim 9, including monitoring a dew point in the catch chamber.",
    "12. The powder processing method as recited in claim 9, further comprising, after the forming, classifying the metallic powder under super-atmospheric pressure with a dew point of less than −85° F.",
    "13. A powder processing method comprising: storing a metallic powder in a rotating chamber that is pressurized to a super-atmospheric pressure with a dry cover gas; and purging moist cover gas from the rotating chamber after a predetermined amount of time and replenishing the rotating chamber with new dry cover gas.",
    "14. The powder processing method as recited in claim 13, wherein the storing includes agitating the metallic powder using baffles within the rotating chamber.",
    "15. The powder processing method as recited in claim 13, including conducting the storing under a temperature of 65-90° F.",
    "16. The powder processing method as recited in claim 13, further comprising establishing a continuous flow of the dry cover gas through the rotating chamber.",
    "17. The powder processing method as recited in claim 16, further comprising maintaining a continuous moisture concentration gradient between the metallic powder and the dry cover gas.",
    "18. The powder processing method as recited in claim 13, including revolving the rotating chamber at a rate of approximately 0.1-1 revolutions per minute.",
    "19. The powder processing method as recited in claim 13, including establishing a dew point of less than −90° F. within the rotating chamber.",
    "20. The powder processing method as recited in claim 13, including pressurizing the chamber using a pressurized gas system having a pressurized gas tank.",
    "21. The powder processing method as recited in claim 13, including monitoring a dew point in the chamber.",
    "22. A powder processing method comprising: degassing a metallic powder in a rotating chamber that is evacuated to a sub-atmospheric pressure; and after the degassing, storing the metallic powder in a rotating storage chamber that is pressurized to a super-atmospheric pressure with a dry cover gas.",
    "23. A powder processing method comprising: storing a metallic powder in a rotating chamber that is pressurized to a super-atmospheric pressure with a dry cover gas; purging moist cover gas from the rotating chamber after a predetermined amount of time and replenishing the rotating chamber with new dry cover gas; and monitoring a level of the dry cover gas in the chamber and, in response to the level, replenishing the dry cover gas in the chamber to maintain a desired pressure."
  ],
  "description_excerpt": "This disclosure relates to handling of metallic powders that are sensitive to picking up moisture during processing. Metallic powders, such as aluminum-based alloys, may be formed by injecting molten alloy into a high pressure inert gas stream to atomize the alloy. In subsequent handling, the powder may be exposed to air from the ambient surrounding environment and may pick up moisture from the air. The moisture does not have a significant influence on typical end uses of the powder, such as paint pigment, and in many cases remains in the powder. If desired, the moisture may be “scrubbed” from the powder at an elevated temperature. Some powder may also be used in a downstream, high temperature processing step, such as in liquid phase sintering, which removes the moisture in the course of powder consolidation.\n\nA disclosed powder processing method includes degassing a metallic powder in a rotating chamber that is evacuated to a sub-atmospheric pressure. Alternatively, or in addition to the degassing, the method may include storing the metallic powder in a rotating storage chamber that is pressurized to a super-atmospheric pressure with a dry cover gas.\n\nThe various features and advantages of the disclosed examples will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. FIG. 1 illustrates an example method for powder processing. FIG. 2 illustrates an example degassing system. FIG. 3 illustrates an example degassing chamber. FIG. 4 illustrates an example storage system.",
  "cpc": [
    "B22F 9/082",
    "B22F 1/08",
    "B22F 1/142",
    "B22F 2998/10",
    "B22F 2999/00",
    "B22F 9/08",
    "B65G 3/04",
    "F26B 11/049"
  ],
  "ipc": [
    "B22F 1/08",
    "B22F 1/142",
    "B22F 9/02"
  ],
  "assignees": [
    "UNITED TECHNOLOGIES CORP",
    "WATSON THOMAS J"
  ],
  "inventors": [
    "WATSON THOMAS J"
  ],
  "filing_date": "2010-07-30",
  "publication_date": "2013-01-22",
  "grant_date": "2013-01-22",
  "priority_date": "2010-07-30",
  "application_number": "US-84742710-A",
  "family_id": "44800314",
  "citations": [
    "CN1537690A",
    "JP2000258064A",
    "US1852583A",
    "US2011189497A1",
    "US4388088A",
    "US4432813A",
    "US5039476A",
    "US5383615A",
    "US5958156A",
    "US6902845B2"
  ]
}