ALUMINIUM ALLOY PRODUCTS, AND METHODS OF MAKING SUCH ALLOY PRODUCTS

• US 20160102388A1
• Filed: 05/07/2014
• Published: 04/14/2016
• Est. Priority Date: 05/07/2013
• Status: Active Grant

• Current Assignee: Charles Grant Purnell, Henry Dickinson
• Original Assignee: Charles Grant Purnell
• Inventors: PURNELL, CHARLES GRANT, DICKINSON, HENRY
• Granted Patent: US 10,640,851 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B22F 1/09 Mixtures of metallic powders
• CPC Class Codes: B22F 1/105 containing inorganic lubricating or binding agents, e.g. metal salts
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/02 Compacting only
• CPC Class Codes: B22F 3/1003 Use of special medium during sintering, e.g. sintering aid
• CPC Class Codes: B22F 3/12 Both compacting and sintering by forging B22F3/17
• CPC Class Codes: B22F 3/26 Impregnating making ferrous alloys by impregnation C22C33/0242
• CPC Class Codes: B22F 9/08 by casting, e.g. through sieves or in water, by atomising or spraying using electric discharge B22F9/14
• CPC Class Codes: B22F 9/082 atomising using a fluid using centrifugal force B22F9/10
• CPC Class Codes: C22C 1/0416 Aluminium-based alloys
• CPC Class Codes: C22C 21/00 Alloys based on aluminium
• CPC Class Codes: C22C 21/02 with silicon as the next major constituent
• CPC Class Codes: C22C 21/14 with silicon
• CPC Class Codes: C22C 21/16 with magnesium
• CPC Class Codes: C25D 11/04 of aluminium or alloys based thereon

Abstract

Aluminium-silicon powder mixtures comprising a hypereutectic Al—Si powder, a near eutectic Al—Si powder, and a third powder which is aluminium or a hypoeutectic aluminium alloy containing alloying constituents other than silicon and less than 9 wt % silicon, with a sintering aid comprising a fourth, zinc-containing powder, are pressed and sintered to provide powder metallurgy products suitable for automotive component use in particular. The third powder in the composition permits such Al-Si powder mixtures to be compressed to a density approaching that obtained by use of an annealed powder mixture, but without the annealing step.

Claims

1. A metal powder source material for making an aluminium-based sintered product by a powder metallurgy route, comprising a mixture of first, second and third aluminium-containing powders;

wherein the first powder is of a hypereutectic aluminium-silicon-copper-magnesium alloy, the second powder is of a near-eutectic aluminium-silicon alloy containing from 9 to 13 wt % silicon, and the third powder is of aluminium or a hypoeutectic aluminium alloy containing alloying constituents other than silicon and less than 9 wt % silicon;

the first and second powders are present in relative proportions to one another lying in the range 35;

65 wt % to 65;

35 wt %; and

the third powder is present in a proportion of up to 35 wt % of the total weight of the three said aluminium-containing powders.

2. A metal powder source material according to claim 1, wherein at least one of the first, second and third aluminium-containing powders has been produced by an atomizing step and not subsequently annealed.

3. A metal powder source material according to claim 2, wherein at least the first and second aluminium-containing powders have been produced by an atomizing step and not subsequently annealed.

4. A metal powder source material according to any one of the preceding claims, wherein the hypereutectic aluminium-silicon-copper-magnesium alloy of the first powder has a copper content of at least 1 wt %.

5. A metal powder source material according to claim 4, wherein the hypereutectic aluminium-silicon-copper-magnesium alloy of the first powder has a copper content of at least 2 wt %.

6. A metal powder source material according to any one of the preceding claims, wherein the hypereutectic aluminium-silicon-copper-magnesium alloy of the first powder has a magnesium content of at least 0.2 wt %.

7. A metal powder source material according to any one of the preceding claims, wherein the third powder is of substantially pure aluminium.

8. A metal powder source material according to any one of claims 1 to 6, wherein the third powder is a hypoeutectic aluminium alloy having a silicon content of less than 0.6 wt %.

9. A metal powder source material according to any one of the preceding claims, wherein the third powder is present as 5 to 35% of the total weight of the first three powders.

10. A metal powder source material according to claim 9, wherein the third powder is present as at least 10% of the total weight of the first three powders.

11. A metal powder mix suitable for making an aluminium-based sintered product by a powder metallurgy route, comprising a metal powder source material according to any one of the preceding claims, mixed with a sintering aid comprising a fourth, zinc-containing powder, wherein the zinc-containing powder is present as at least 0.5 wt % of the total metal powder mixture.

12. A metal powder mix according to claim 11, wherein the fourth powder comprises 2 to 6 wt % of the total metal powder mixture.

13. A metal powder mix according to claim 11 or claim 12, further incorporating from 1 to 5 wt % of a solid lubricant.

14. A metal powder mix according to claim 13, wherein the solid lubricant is graphite.

15. A green pressed composite formed by shaping and compacting a metal powder mix according to any one of claims 11 to 14.

16. A powder metallurgy product obtained from a metal powder mix according to any one of claims 11 to 14 by pressing and sintering, or from a green pressed composite according to claim 15 by sintering, having a microstructure characterised by interpenetrating reticular structures derived from the original alloy powder particles, including a first structure derived from the first alloy powder and a second structure derived from the other aluminium-based powders.

17. A powder metallurgy product according to claim 16 impregnated with an oil or a sealant.

18. A powder metallurgy product according to claim 16 having an anodized or coated surface.

19. An automotive component comprising a powder metallurgy product according to any one of claims 16 to 18 having a sliding contact bearing surface formed therein.

20. A method of making an aluminium-based sintered product by a powder metallurgy route, comprising producing a mixture of first, second and third aluminium-containing powders and a sintering aid comprising a fourth, zinc-containing powder, compacting the mixture, and sintering the compacted mixture to produce the product;

wherein the first powder is of a hypereutectic aluminium-silicon-copper-magnesium alloy, the second powder is of a near-eutectic aluminium-silicon alloy containing from 9 to 13 wt % silicon, the third powder is of aluminium or a hypoeutectic aluminium alloy containing alloying constituents other than silicon and less than 9 wt % silicon, and the fourth powder is a sintering aid comprising zinc or a zinc-based alloy;

the first and second powders being present in relative proportions to one another lying in the range 35;

65 wt % to 65;

35 wt %, the third powder being present in a proportion of up to 35 wt % of the total weight of the three said aluminium-containing powders, and the zinc-containing powder being present as at least 0.5 wt % of the total metal powder mixture.

21. A method according to claim 20, wherein at least one of the first, second and third aluminium-containing powders is produced by an atomizing step without being subsequently annealed.

22. A method according to claim 21, wherein at least the first and second aluminium-containing powders are produced by an atomizing step without being subsequently annealed.

23. A method according to any one of claims 20 to 22, wherein the hypereutectic aluminium-silicon-copper-magnesium alloy of the first powder has a copper content of at least 1 wt %.

24. A method according to claim 23, wherein the hypereutectic aluminium-silicon-copper-magnesium alloy of the first powder has a copper content of at least 2 wt %.

25. A method according to any one of claims 20 to 24, wherein the hypereutectic aluminium-silicon-copper-magnesium alloy of the first powder has a magnesium content of at least 0.2 wt %.

26. A method according to any one of claims 20 to 25, wherein the third powder is of substantially pure aluminium.

27. A method according to any one of claims 20 to 25, wherein the third powder is a hypoeutectic aluminium alloy having a silicon content of less than 0.6 wt %.

28. A method according to any one of claims 20 to 27, wherein the third powder is present as 5 to 35% of the total weight of the first three powders.

29. A method according to claim 28, wherein the third powder is present as at least 10% of the total weight of the first three powders.

30. A method according to any one of claims 20 to 29, wherein the fourth powder comprises 2 to 6 wt % of the total metal powder mixture.

31. A method according to any one of claims 20 to 30, further including the step of incorporating from 1 to 5 wt % of a solid lubricant into the powder before the compaction step.

32. A method according to claim 31, wherein the solid lubricant is graphite.

33. A method according to any one of claims 20 to 32, including the further step of re-striking the sintered product to densify it.

34. A method according to any one of claims 20 to 32, wherein the sintered product exhibits interconnected porosity and is subjected to the further step of impregnating the product with an oil or a sealant.

35. A method according to any one of claims 20 to 34, including the further step of anodizing the sintered product.

36. A method according to claim 20, substantially as described with reference to the specific Example.