Claims
- 1. A method for annealing gold or gold alloy parts comprising the steps of:
- heating said parts in a furnace having a hot zone maintained at a temperature of 600.degree. C. or above;
- injecting into said furnace gaseous nitrogen containing up to 5% by volume oxygen together with a reducing gas, said reducing gas injected into said furnace with a flow rate of about 3.0 times or more the stoichiometric amount required for the complete conversion of residual oxygen in a manner to permit said reaction of oxygen and said reducing gas to be essentially complete prior to said mixture contacting said part; and
- moving said part through said furnace for a time sufficient to achieve the desired heat treated properties in said part.
- 2. A method according to claim 1 wherein said residual oxygen is converted to moisture.
- 3. A method according to claim 1 wherein said residual oxygen is converted to hydrogen, carbon dioxide, moisture, carbon monoxide or mixtures thereof.
- 4. A method according to claim 1 wherein said reducing gas is a mixture of hydrogen and a hydrocarbon and said residual oxygen is converted to hydrogen, carbon dioxide, moisture, carbon monoxide or mixtures thereof.
- 5. A method according to claim 1 wherein said nitrogen is generated by non-cryogenic means.
- 6. A method according to claim 1 wherein said furnace is heated to a temperature of between 600.degree. C. and 800.degree. C.
- 7. A method according to claim 1 wherein said reducing gas is hydrogen.
- 8. A method according to claim 1 wherein said reducing gas is a hydrocarbon.
- 9. A method according to claim 1 wherein said reducing gas is a mixture of hydrogen and a hydrocarbon.
- 10. A method according to claim 1 wherein said reducing gas is selected from the group consisting of methane, ethane, propane, butane, ethylene, propylene, butene, methanol, ethanol, propanol, dimethylether, diethyl ether, methyl-ethyl ether, natural gas, petroleum gas, cooking gas, coke oven gas, town gas, exothermic and endothermic generated gas, dissociated ammonia and mixtures thereof.
- 11. A method according to claim 8 wherein said hydrocarbon is selected from the group consisting of methane, ethane, propane, butane, ethylene, propylene, butene, methanol, ethanol, propanol, dimethylether, diethyl ether, methyl-ethyl ether, natural gas, petroleum gas, cooking gas, coke oven gas, town gas, exothermic and endothermic generated gas, dissociated ammonia and mixtures thereof.
Parent Case Info
This is a division, of application Ser. No. 07/966,258 filed Oct. 26, 1992 which is a division of 07/727,806 filed Jul. 8, 1991now U.S. Pat. No. 5,221,369.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4381955 |
Desai |
May 1983 |
|
4684416 |
Masumoto et al. |
Aug 1987 |
|
5139739 |
Takayanagi et al. |
Aug 1992 |
|
Divisions (2)
|
Number |
Date |
Country |
Parent |
966258 |
Oct 1992 |
|
Parent |
727806 |
Jul 1991 |
|