US3000756A

US3000756A - Hot dip aluminum coating

Info

Publication number: US3000756A
Application number: US677214A
Authority: US
Inventors: John E Logan
Original assignee: Wean Engineering Co Inc
Current assignee: Wean Engineering Co Inc
Priority date: 1957-08-09
Filing date: 1957-08-09
Publication date: 1961-09-19
Anticipated expiration: 1978-09-19

Description

United States Patent 3,000,756 HOT DIP ALUMINUM COATING John Logan, Pittsburgh, Pa., assignor to The Wean Engineering Company, Inc., Warren, Ohio, a corporation of Ohio No Drawing. Filed Aug. 9, 1957, Ser. No. 677,214 18 Claims. (Cl. 117-51) This invention relates to the coating of metallic objects with an adherent ductile coating of aluminum. It is particularly useful in coating steel wire, steel strip and the like with aluminum.

It has long been customary to coat steel and other base metals with coating metals for the purpose of protecting the base metal against corrosion or to provide other surface qualities not inherent in the base metal. Such metals have been applied by hot dip processes, by electrolytic plating, or by rolling slabs of different metals together. To the best of my knowledge, all present methods of coating a base metal, such as steel, with aluminum have marked disadvantages in that they require a protective atmosphere as well as the installation of expensive equipment. Hot dip processes have been employed to deposit aluminum on steel, but even in the presence of various fluxes, they have been only partially successful. The coatings heretofore produced by the hot dipping of metallic objects in aluminum have produced coatings which are brittle. Some, for example, adhere satisfactorily only after passing the coated metal through a rolling mill. Such coatings do not adhere satisfactorily to wire. In many instances, the fluxes which have been employed for hot dipping in aluminum are poisonous, corrosive, or otherwise extremely diflicult to handle.

I provide a flux selected from the group comprising phosphorus and compounds of phosphorus with sulphur. It is essential that the flux not contain oxygen in order to produce satisfactory results. I prefer to employ phosphorus free of oxygen but find that compounds of phosphorus and sulphur also produce satisfactory results.

A few examples will serve to illustrate my invention. Red phosphorus was applied to various steel specimens. For example, the phosphorus was reduced to a fine powder and then suspended in water. The phosphorus and water were then sprayed on the specimens. Upon evaporation of the water, a fine coating of phosphorus remained adhering to the metal. After application of the phosphorus, the metal was dipped in a pot of molten aluminum for a preferred time of two or three seconds under the following conditions:

Tempera- Dipping Example Flux ture of Al, Time,

1*. seconds 1 Powdered P4 in hot water 1, 290 5 sprayed on steel strip. Powdered P4 in cold water 1, 290 3 sprayed on steel strip. Powdered P4 in hot Water 1. 290 3 sprayed on steel strip.

Alternatively, finely divided phosphorus may be suspended in an organic carrying agent such as alcohol.

Patented Sept. 19, 1961 ice Tempera- Dipping Example Flux ture of Al, Time,

F. seconds 8 Powdered P4 rubbed on 1, 260 3 steel strip with a cloth. 9 Powdered P4 rubbed 0n 1, 290 3 steel Wire with a cloth.

When phosphorus is applied to clean mild steel in the manner described, a ductile and highly adherent coating of aluminum is produced. For example, when ordinary steel wire is coated in accordance with the invention herein, repeated flexing of the wire will not break or separate the aluminum coating from the steel until the steel itself is at the point of rupture from work hardening resulting from the repeated flexure. As noted above, the coating is apparently less ductile if the temperature of the aluminum bath and the dipping time are increased.

Compounds of phosphorus with sulphur have also been employed as fluxes with satisfactory results. For example, phosphorus pentasulfide, P 8 has been employed in the same manner described for red phosphorus and has produced a satisfactory coating. The following examples are illustrative.

'Ie'mpera- Dipping Example Flux ture of Al, Time,

F. seconds 10 Powdered P255 in methyl- 1, 260 3 ene chloride sprayed on steel strip. 11 Steel strip dipped in carbon 1, 330 3 disulfide suspending P285. 12 P285 rubbed on steel strip 1, 290 3 with a cloth. 13 Powdered P585 rubbed on 1, 290 6 steel Wire with a. cloth dipped in carbon disulfide.

In the same manner, phosphorus trisulfide, P 8 has been employed to produce a useful product. The coating has, however, been less satisfactory than that produced using red phosphorus or phosphorus pentasulfide. The following example is noted as producing a reasonably satisfactory coating.

Tempera Dipping Example Flux ture of Al, Time,

F. seconds 14 Steel strip dipped in carbon 1, 310

disulfide in which powdered P43 was suspended.

from the group consisting of phosphorus and compounds of phosphorus with sulphur, and then immersing the metal in molten aluminum.

2. The product of the process of claim 1.

3. The method of coating a ferrous metal with aluminum which comprises fluxing the metal with a member selected from the group consisting of phosphorus and compounds of phosphorus with sulphur, and then immersing the metal in molten aluminum.

4. The method of coating a ferrous metal with aluminum which comprises fluxing the metal with red phosphorus, and then immersing the metal in molten aluminum.

5. The product of the process of claim 4.

6. The method of coating a ferrous metal with aluminum which comprises fluxing the metal with P 8 and then immersing the metal in molten aluminum.

7. The product of the process of claim 6.

8. The method of coating 21 ferrous metal with aluminum which comprises fluxing the metal with P 8 and then immersing the metal in molten aluminum.

9. The product of the process of claim 8.

10. The method of coating a metal with aluminum which comprises cleaning the metal, coating the surface of the metal with a flux selected from the group consisting of phosphorus and compounds of phosphorus with sulphur, immersing the metal in a bath of molten aluminum and then withdrawing it therefrom.

11. The method of coating a ferrous metal with aluminum which comprises cleaning the ferrous metal, coating the surface of the metal with a flux of red phosphorus, immersing the metal in a bath of molten aluminum and then withdrawing it therefrom.

12. The product of the process of claim 11.

13. The method of coating a ferrous metal with aluminum which comprises cleaning the ferrous metal, coating the surface of the metal with a flux of P 8 immersing the metal in a bath of molten aluminum and then with drawing it therefrom.

14. The method of coating a ferrous metal with aluminum which comprises cleaning the ferrous metal, coating the surface of the metal with a flux of P 8 immersing the metal in a bath of molten aluminum and then withdrawing it therefrom.

15. The method of coating a metal with aluminum which comprises mixing a liquid with a flux selected from the group consisting of phosphorus and compounds of phosphorus with sulphur, spraying the mixture on said metal, allowing the liquid to evaporate and then immersing the metal in a bath molten aluminum and withdrawing it therefrom.

16. The method of coating a metal with aluminum which comprises mixing water and a flux selected from the group consisting of phosphorus and compounds of phosphorus with sulphur, spraying the mixture on said metal, allowing the water to evaporate and then immersing the metal in a bath of molten aluminum and withdrawing it therefrom.

17. The method of coating a metal with aluminum which comprises mixing alcohol and a flux selected from the group consisting of phosphorus and compounds of phosphorus with sulphur, spraying the mixture on said metal, allowing the alcohol to evaporate and then immersing the metal in a bath of molten aluminum and withdrawing it therefrom.

18. The method of coating 21 ferrous metal with aluminum which comprises mixing water and a flux of powdered red phosphorus, spraying the mixture on the metal, allowing the water to evaporate and then immersing the metal in a bath of molten aluminum and withdrawing it therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 750,511 Wherry Jan. 26, 1904 750,512 Wherry Jan. 26, 1904 1,456,274 Keep May 22, 1923 1,501,293 Staack July 15, 1924 1,910,385 Fisher et al May 23, 1933 'UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,000,756 September 19 196 John E Logan It is hereby certified that error appears injzhe above numbered patentrequiring correction and that the said Letters Patent should read as "corrected below.

Column 2 third table thereof, column 3,, line .1 thereof, insert 3 column 4 line 10 after "bath" insert of Signed and sealed this 13th day of February 1962'o (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

Claims

1. THE METHOD OF COATING A METAL WITH ALUMINUM WHICH COMPRISES FLUXING THE METAL WITH A MEMBER SELECTED FROM THE GROUP CONSISTING OF PHOSPHORUS AND COMPOUNDS OF PHOSPHORUS WITH SULPHUR, AND THEN IMMERSING THE METAL IN MOLTEN ALUMINUM.