US4547228A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Surface treatment of metals
Assignee: Allstate Financial Corp
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Filing: 1983-05-26
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Granted: 1985-10-15
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Expires: 2003-05-26
Abstract
Abstract This application disclosed a method and apparatus for conducting various metal treatment processes including nitriding, carbonitriding, nitrocarburizing, surface activation, and selective oxidation in any desired sequence in the same fluidized bed furnace. The apparatus comprises a fluidized bed furnace having a humidifier system including a humidifier and superheater and the method involves exposing a metal workpiece sequentially to at least two separate metal treatment atmospheres in a fluidized bed furnace.
Inventors
- 👤 Carol A. Girrell
- 👤 Joseph E. Japka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:49
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/06; C23C8/34; C21; C21D; C21D1/00; C21D1/34; C21D1/53
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
65 words
A method for treating metals, which comprises the steps of: providing a fluidized bed; placing a metal workpiece in the fluidized bed; sequentially exposing the metal workpiece to at least two separate metal treatment atmospheres in the same fluidized bed at least one of said atmospheres being humidified for surface treatment of the metal workpieces to modify the chemistry of the surface of the workpiece.
Claim 2
Independent Claim
65 words
A method for treating metals, which comprises the steps of: providing a fluidized bed; placing a metal workpiece in the fluidized bed; sequentially exposing the metal workpiece to at least two separate metal treatment atmospheres in the same fluidized bed at least one of said atmospheres being humidified for surface treatment of the metal workpieces to modify the chemistry of the surface of the workpiece.
Claim 3
Dependent Claim
27 words
The method of claim 1, wherein at least one of the metal treatment atmospheres contains ammonia; and at least one of the metal treatment atmospheres contains water.
Claim 4
Dependent Claim
22 words
The method recited in claim 2 wherein the water is added to the metal treatment atmosphere by means of a humidified gas.
Claim 5
Dependent Claim
17 words
The method recited in claim 3, wherein the gas is humidified by sparging it through heated water.
Claim 6
Dependent Claim
23 words
The method recited in claim 4 further comprising the step of superheating the humidified gas before introducing it to the metal treatment atmosphere.
Claim 7
Independent Claim
52 words
A method for oxynitriding metals comprising the steps of: placing a metal workpiece in a heated fluidized bed; and passing a mixture of gases containing ammonia and a humidified inert gas through the fluidized bed for surface treatment of the metal workpieces to modify the chemistry of the surface of the workpiece.
Claim 8
Independent Claim
52 words
A method for oxynitriding metals comprising the steps of: placing a metal workpiece in a heated fluidized bed; and passing a mixture of gases containing ammonia and a humidified inert gas through the fluidized bed for surface treatment of the metal workpieces to modify the chemistry of the surface of the workpiece.
Claim 9
Independent Claim
48 words
A method for preconditioning metal workpieces for nitriding, which comprises: placing a metal workpiece in a fluidized bed; heating the fluidized bed and passing a humidified gas through the fluidized bed for surface treatment of the metal workpieces to modify the chemistry of the surface of the workpiece.
Claim 10
Independent Claim
48 words
A method for preconditioning metal workpieces for nitriding, which comprises: placing a metal workpiece in a fluidized bed; heating the fluidized bed and passing a humidified gas through the fluidized bed for surface treatment of the metal workpieces to modify the chemistry of the surface of the workpiece.
Claim 11
Dependent Claim
14 words
The method recited in claim 7 wherein the humidified gas is an inert gas.
Claim 12
Dependent Claim
45 words
A metal treatment process which comprises: exposing a metal workpiece to a metal treatment atmosphere including a humidified gas and a hydrocarbon bearing gas in a fluidized bed for surface treatment of the metal workpieces to modify the chemistry of the surface of the workpiece.
Claim 13
Dependent Claim
45 words
A metal treatment process which comprises: exposing a metal workpiece to a metal treatment atmosphere including a humidified gas and a hydrocarbon bearing gas in a fluidized bed for surface treatment of the metal workpieces to modify the chemistry of the surface of the workpiece.
Claim 14
Dependent Claim
18 words
The method recited in claim 1, wherein one of the metal treatment atmospheres is a hydrocarbon bearing gas.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-14 | 1989-04-15 | 1989-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-14 | 1993-04-15 | 1993-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-14 | 1997-04-15 | 1997-10-15 | $7700.00 | Window Closed / Lapsed |