Method of making sound interface in overcast bimetal components

Patent metadata

Field	Value
Publication number	US-9770757-B2
Application number	US-201514825238-A
Country	US
Kind code	B2
Filing date	Aug 13, 2015
Priority date	Aug 13, 2015
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

A method of forming a bi-metallic casting. The method includes providing a metal preform of a desired base shape defining a substrate surface and removing a natural oxide layer and surface contamination from the substrate surface to yield a cleaned metal preform. The method further includes galvanizing the cleaned metal preform, yielding a galvanized metal preform followed by electroplating a thin nickel film on at least a portion of the substrate surface of the galvanized metal preform. Additionally, the method includes metallurgically bonding the portion of the metal preform having the nickel film with an overcast metal to form a bi-metallic casting. The nickel film promotes a metallurgical bond between the metal preform and the overcast metal.

First claim

What is claimed is:

1. A method of forming a bi-metallic casting, the method comprising:
providing a metal preform of a desired base shape defining a substrate surface;
removing an oxide layer and surface contamination from the substrate surface, yielding a cleaned metal preform;
galvanizing the cleaned metal preform, yielding a galvanized metal preform;
electroplating a thin nickel film on at least a portion of the substrate surface of the galvanized metal preform; and
metallurgically bonding the portion of the metal preform having the nickel film with an overcast metal to form a bi-metallic casting, wherein the nickel film promotes a metallurgical bond between the metal preform and the overcast metal.

2. The method of claim 1 , further comprising preheating the metal preform having the nickel film prior to metallurgically bonding the metal preform with the overcast metal.

3. The method of claim 1 , comprising providing the nickel film having a thickness sufficient to prevent a re-formation of the oxide layer.

4. The method of claim 3 , wherein the nickel film is formed having a thickness of about 1 μm to about 5 μm.

5. The method of claim 1 , wherein removing the oxide layer from the substrate surface comprises:
degreasing the substrate surface;
treating the substrate surface with an alkali etching solution; and
pickling the substrate surface.

6. The method of claim 1 , wherein galvanizing the cleaned metal preform comprises:
treating the substrate surface with a zinc galvanizing solution;
treating the substrate surface with nitric acid; and
treating the substrate surface a second time with a zinc galvanizing solution.

7. The method of claim 1 , wherein metallurgically bonding the portion of the metal preform having the nickel film with the overcast metal comprises a metal casting process using a molten metal.

8. The method of claim 7 , wherein the overcast metal is an aluminum alloy which is heated to between 680° C. and 740° C.

9. The method of claim 8 , wherein the metal casting process comprises squeeze casting.

10. The method of claim 1 , wherein the metal preform comprises an aluminum alloy.

11. The method of claim 1 , wherein the overcast metal comprises an aluminum alloy.

12. The method of claim 1 , wherein the nickel film is formed on an entirety of the substrate surface, and the overcast metal is metallurgically bonded to an entirety of the metal preform.

13. A method of forming a bi-metallic casting with improved bonding between metal components, the method comprising:
providing an aluminum preform of a desired base shape defining a substrate surface;
removing a natural oxide layer from the substrate surface;
etching the substrate surface;
galvanizing the substrate surface;
electroplating a thin nickel film on the substrate surface;
preheating the aluminum preform to 150° C. to 350° C.; and
forming a metallurgical bond between at least a portion of the aluminum preform and an overcast metal having a composition different from both the aluminum preform and the nickel film, wherein the nickel film promotes the metallurgical bond between the aluminum preform and the overcast metal.

14. The method of claim 13 , wherein the nickel film is formed having a thickness of less than about 5 μm.

15. The method of claim 12 , wherein removing the natural oxide layer from the substrate surface comprises degreasing the substrate surface prior to etching the substrate surface.

16. The method of claim 15 , wherein etching the substrate surface comprises treating the substrate surface with an alkali etching solution followed by pickling the substrate surface.

17. The method of claim 13 , wherein galvanizing the substrate surface comprises:
treating the substrate surface with a zinc galvanizing solution;
treating the substrate surface with nitric acid; and
treating the substrate surface a second time with a zinc galvanizing solution.

18. A method of forming a bi-metallic casting with an aluminum preform, the method comprising:
removing a natural oxide layer from a surface of an aluminum preform;
immersing the aluminum preform into a galvanizing bath;
electroplating a thin nickel film having a thickness of less than about 5 μm on the surface of the aluminum preform;
preheating the aluminum preform to 150° C. to 350° C.; and

contacting at least a portion of the aluminum preform with a molten aluminum heated to between 680° C. and 740° C. to form a bi-metallic casting, wherein the nickel film substantially remains on the surface of the aluminum preform as an interface promoting a metallurgical bond between the aluminum preform and the molten aluminum.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Wang Qigui
• Ye Bing
• Jiang Haiyan

Classifications

• B22D21/007

  with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C · CPC title

• C23C22/83

  Chemical after-treatment · CPC title

• C23C22/78

  Pretreatment of the material to be coated · CPC title

• C23G1/24

  with neutral solutions · CPC title

• C23C22/66

  Treatment of aluminium or alloys based thereon · CPC title