Claims
- 1. A method of controlling bulk absorption of atomic hydrogen and facilitating degassing of hydrogen from a metal or metal alloy workpiece during heat treatments in furnaces with ambient and/or moisture-laden atmospheres, the method comprising:
- exposing the surface of said workpiece to an inorganic salt solution or dispersion acidified with hydrochloric acid, with the inorganic salt of the solution containing a transition metal cation and a sulfate, phosphate or nitrate anion, before being subjected to said heat-treatment, said transition metal cation having an equal or positive standard reduction half-reaction potential relative to metal or metal alloy workpiece;
- subjecting said workpiece exposed to said hydrochloric acidified transition metal sulfate, phosphate or nitrate salt solution or dispersion to a heat treatment; and
- using the hydrochloric acidified transition metal sulfate, phosphate or nitrate salt solution or dispersion to substantially decrease the amount of atomic hydrogen entering the bulk of the workpiece during heat treatment and to facilitate removal of atomic and molecular hydrogen from the bulk of the aluminum alloy workpiece.
- 2. The method of claim 1 wherein the hydrochloric acid is in the amount lying in the range of 0.01 to 5 percent of the solution or dispersion.
- 3. The method of claim 1 in which the solution or dispersion is a solvent comprised predominantly of water.
- 4. The method of claim 1 in which the inorganic salt is a transition metal sulfate, phosphate or nitrate salt having a concentration in the range of 0.05 to 47.0 percent of the total weight of the solution or dispersion.
- 5. The method in claim 4 in which the inorganic salt is ferric or ferrous sulfate, having a concentration in the range of two to ten percent of the total weight of the solution or dispersion.
- 6. The method of claim 1 wherein the pH of solution or dispersion ranges between 0.1 and 2.5.
- 7. The method of claim 1 wherein the metal or metal alloy workpiece is exposed to the solution for a minimum exposure time of five seconds and the solution is applied by dipping, coating or spraying onto the workpiece.
- 8. The method of claim 1 wherein the surface of the metal or metal alloy workpiece exposed to the acidified inorganic salt solution or dispersion is subjected to the heat treatment without wiping or rinsing the workpiece surface prior to such heat treatment.
- 9. The method of claim 1 wherein the metal or metal alloy workpiece is subjected to cleaning or degreasing with a solvent or alkaline etch followed by a deionized water rinse and/or an acidic desmutting step, followed by a deionized water rinse, prior to treatment with the acidified inorganic salt solution or dispersion.
- 10. The method of claim 1 wherein a wetting agent or dispersant is incorporated in the acidified inorganic salt solution or dispersion to facilitate uniform treatment of metal or metal alloy workpiece.
- 11. The method of claim 1 wherein a solvent-based formulation is added to the acidified inorganic salt solution or dispersion to aid drying or wetting the metal or metal alloy workpiece surface before the workpiece is subjected to heat treatment.
- 12. The method of claim 11 wherein the solvent of the added solvent-based formulation is selected from the group consisting essentially of alcohols, glycols, and glycolether acetates and low molecular weight, nonaromatic hydrocarbons.
Parent Case Info
This application is a continuation-in-part of U.S. patent application Ser. No. 08/756,289, filed Nov. 25, 1996 now U.S. Pat. No. 5,753,056.
US Referenced Citations (7)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0143715 |
May 1985 |
EPX |
54-221286 |
Feb 1977 |
JPX |
54-36908 |
Nov 1979 |
JPX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
756289 |
Nov 1996 |
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