Aluminium alloy composition for a sliding element

Abstract

An Aluminium alloy composition for a sliding element may include: 4 wt % to 8 wt % of Tin; 4 wt % to 8 wt % of Silicon; 0.4 wt % to 1.7 wt % of Copper; and 0.1 wt % to 1 wt % of Manganese. The composition may also include at least one of: 0.4 wt % to 2.0 wt % of Nickel; 0.01 wt % to 0.3 wt % of Zirconium; 0.05 wt % to 0.3 wt % of Vanadium; 0.05 wt % to 0.5 wt % of Scandium; and 0.05 wt % to 1 wt % of Erbium. The composition may also include at least one of: 0.005 wt % to 0.2 wt % of Titanium; 0.003 wt % to 0.2 wt % of Strontium; 0.005 wt % to 0.5 wt % of Antimony; 0.005 wt % to 0.1 wt % of Europium; and 0.001 wt % to 0.02 wt % of Carbon. The balance of the composition, apart from any incidental impurities, may be Aluminium.

Claims

1. An Aluminium alloy composition for a sliding element, consisting of: 4 wt % to 8 wt % of Tin; 4 wt % to 8 wt % of Silicon; 0.4 wt % to 1.7 wt % of Copper; 0.1 wt % to 1 wt % of Manganese; at least one of: 0.4 wt % to 2.0 wt % of Nickel; 0.01 wt % to 0.3 wt % of Zirconium; 0.05 wt % to 0.3 wt % of Vanadium; 0.05 wt % to 0.5 wt % of Scandium; 0.05 wt % to 1 wt % of Erbium; at least one of: 0.003 wt % to 0.2 wt % of Strontium; 0.005 wt % to 0.5 wt % of Antimony; 0.005 wt % to 0.1 wt % of Europium; 0.001 wt % to 0.02 wt % of Carbon; and a balance of the composition, apart from any incidental impurities, of Aluminium.

2. The Aluminium alloy composition according to claim 1, consisting of: 4 wt % to 8 wt % of Tin; 4 wt % to 8 wt % of Silicon; 0.4 wt % to 1.7 wt % of Copper; 0.1 wt % to 1 wt % of Manganese; 0.01 wt % to 0.1 wt % of Zirconium; 0.4 wt % to 2.0 wt % of Nickel; 0.05 wt % to 0.3 wt % of Vanadium; 0.01 wt % to 0.2 wt % of Titanium; 0.003 wt % to 0.2 wt % of Strontium; and the balance of the composition, apart from any incidental impurities, of Aluminium.

3. The Aluminium alloy composition according to claim 1, consisting of: 4 wt % to 8 wt % of Tin; 4 wt % to 8 wt % of Silicon; 0.4 wt % to 1.7 wt % of Copper; 0.1 wt % to 1 wt % of Manganese; 0.4 wt % to 2.0 wt % of Nickel; 0.05 wt % to 0.3 wt % of Zirconium; 0.05 wt % to 0.3 wt % of Vanadium; 0.005 wt % to 0.2 wt % of Titanium; 0.003 wt % to 0.2 wt % of Strontium; and the balance of the composition, apart from any incidental impurities, of Aluminium.

4. The Aluminium alloy composition according to claim 1, wherein the Silicon content ranges from about 4 wt % to about 7 wt %.

5. The Aluminium alloy composition according to claim 1, wherein the Silicon content ranges from about 5.5 wt % to about 7 wt %.

6. The Aluminium alloy composition according to claim 1, wherein the Silicon content is about 6 wt %.

7. The Aluminium alloy composition according to claim 1, wherein the Tin content ranges from about 5 wt % to about 7 wt %.

8. The Aluminium alloy composition according to claim 1, wherein the Manganese content ranges from about 0.2 to about 0.4 wt %.

9. The Aluminium alloy composition according to claim 1, wherein the Carbon content ranges from about 0.0005 wt % to about 0.02 wt %.

10. The Aluminium alloy composition according to claim 1, wherein a minimum content of elements, where present, consists of: about 0.7 wt % min of Copper; about 0.7 wt % min of Nickel; about 0.05% wt % min of Zirconium; about 0.13 wt % min of Vanadium; about 0.05 wt % min of Scandium; about 0.05 wt % min of Erbium; about 0.01 wt % min of Titanium; about 0.01 wt % min of Strontium; about 0.005 wt % min of Antimony; about 0.005 wt % min of Europium; and about 0.001 wt % min of Carbon.

11. The Aluminium alloy composition according to claim 1, wherein a maximum content of elements, where present, consists of: about 1.3 wt % max of Copper; about 2.0 wt % max of Nickel; about 0.2 wt % max of Zirconium; about 0.2 wt % max of Vanadium; about 0.2 wt % max of Scandium; about 0.8 wt % max of Erbium; about 0.05 wt % max of Titanium; about 0.05 wt % max of Strontium; about 0.4 wt % max of Antimony; about 0.05 wt % max of Europium; about 0.01 wt % max of Carbon.

12. The Aluminium alloy composition according to claim 1, wherein the composition has 0.01 wt % to 0.07 wt % of Zirconium.

13. The Aluminium alloy composition according to claim 1, wherein the composition has 0.05 wt % to 0.5 wt % of Scandium and 0.01 wt % to 0.3 wt % of Zirconium.

14. The Aluminium alloy composition according to claim 13, wherein a ratio of Zirconium to Scandium is about one to one.

15. A sliding element comprising an Aluminium alloy composition including: 4 wt % to 8 wt % of Tin; 4 wt % to 8 wt % of Silicon; 0.4 wt % to 1.7 wt % of Copper; 0.1 wt % to 1 wt % of Manganese; 0.01 wt % to 0.07 wt % of Zirconium; at least one of: 0.4 wt % to 2.0 wt % of Nickel; 0.05 wt % to 0.3 wt % of Vanadium; 0.05 wt % to 0.5 wt % of Scandium; 0.05 wt % to 1 wt % of Erbium; at least one of: 0.003 wt % to 0.2 wt % of Strontium; 0.005 wt % to 0.5 wt % of Antimony; 0.005 wt % to 0.1 wt % of Europium; 0.001 wt % to 0.02 wt % of Carbon; and a balance of the composition, apart from any incidental impurities, of Aluminium.

16. The sliding element according to claim 15, further comprising a backing layer of one of steel and bronze.

17. The sliding element according to claim 16, further comprising an Aluminium intermediate layer between the backing layer and the Aluminium alloy composition.

18. The sliding element according to claim 15, wherein a minimum content of elements, where present, includes: about 0.7 wt % min of Copper; about 0.7 wt % min of Nickel; about 0.05% wt % min of Zirconium; about 0.13 wt % min of Vanadium; about 0.05 wt % min of Scandium; about 0.05 wt % min of Erbium; about 0.01 wt % min of Titanium; about 0.01 wt % min of Strontium; about 0.005 wt % min of Antimony; about 0.005 wt % min of Europium; and about 0.001 wt % min of Carbon.

19. The sliding element according to claim 15, wherein a maximum content of elements, where present, includes: about 1.3 wt % max of Copper; about 2.0 wt % max of Nickel; about 0.2 wt % max of Zirconium; about 0.2 wt % max of Vanadium; about 0.2 wt % max of Scandium; about 0.8 wt % max of Erbium; about 0.05 wt % max of Titanium; about 0.05 wt % max of Strontium; about 0.4 wt % max of Antimony; about 0.05 wt % max of Europium; about 0.01 wt % max of Carbon.

20. A bi-metal bearing comprising an Aluminium alloy composition including: 4 wt % to 8 wt % of Tin; 4 wt % to 8 wt % of Silicon; 0.4 wt % to 1.7 wt % of Copper; 0.1 wt % to 1 wt % of Manganese; 0.05 wt % to 0.5 wt % of Scandium; 0.01 wt % to 0.3 wt % of Zirconium; at least one of: 0.4 wt % to 2.0 wt % of Nickel; 0.05 wt % to 0.3 wt % of Vanadium; 0.05 wt % to 1 wt % of Erbium; at least one of: 0.003 wt % to 0.2 wt % of Strontium; 0.005 wt % to 0.5 wt % of Antimony; 0.005 wt % to 0.1 wt % of Europium; 0.001 wt % to 0.02 wt % of Carbon; and a balance of the composition, apart from any incidental impurities, of Aluminium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order that the present invention may be more fully understood, some example embodiments of the present invention will now be described by way of illustration only with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a cross section through part of a bi-metal bearing utilising the Aluminium alloy composition of the present invention and showing the constituent layers; and

(3) FIG. 2 provides the results of some block-on-ring wear tests using two preferred example compositions of the Aluminium alloy composition and two Baseline compositions corresponding to the composition of two of the existing bearings with an Aluminium alloy running layer.

DETAILED DESCRIPTION

(4) FIG. 1 shows a sliding element, specifically a bi-metal plain bearing 1 comprising: a backing 2, an interlayer or intermediate layer 3 and an Aluminium alloy running layer 4.

(5) The backing is made from steel and may optionally comprise up to about 1 wt % copper. The interlayer is made from pure Aluminium (apart from incidental impurities). The Aluminium alloy running layer comprises the Aluminium alloy composition of the first or the second preferred embodiment described above.

(6) Sliding elements (e.g. bi-metal plain bearings) comprising the Aluminium alloy composition may be made using a known method comprising continuous strip casting (e.g. belt-caster, roll-caster or similar casting technology) followed by thermo-mechanical processing such as heat treatment, cold-rolling, cladding and steel cold roll-bonding or such as direct bonding onto steel by the means of hot-bonding with prior heat treatment and cold-rolling operations.

(7) For example, sheet material which may, for example, be about 16 mm thick, may be heat treated by annealing and then rolled down to, for example, about 0.5 mm thick. If necessary, the rolling step may be carried out in a number of passes to reduce the thickness more gradually. However, ideally the number of passes will be minimised so as to keep the manufacturing cost to a minimum. The addition of copper into the Aluminium alloy composition increases the strength of the composition compared to a composition in which the copper is not present and helps to reduce the number of passes required.

(8) The wt % content of the various elements referred to in the following examples is the wt % content of the relevant element in the final Aluminium alloy composition as applied to a sliding element component (for example to a bearing for an engine or motor) rather than the wt % content of the initial mixture used to form the Aluminium alloy composition.

(9) An Aluminium alloy composition according to a first preferred embodiment of the invention that is particularly suitable for use in start-stop bearing applications comprises the following preferred combination of elements comprises the following preferred combination of elements:

(10) TABLE-US-00001 Element Weight percent of Aluminium alloy Purpose Tin About 4 wt % to about 8 wt %, or Solid lubricant (Sn) preferably about 5 wt % to about 7 wt % Silicon About 4 wt % to about 8 wt %, or Hard particle for (Si) preferably about 4 wt % to about increasing wear 7 wt %, or more preferably about resistance of 5 wt % to about 7 wt %, or more Aluminium alloy preferably about 6 wt % composition Copper About 0.4 wt % to about 1.7 wt %, Increase high (Cu) or preferably about 0.5 wt % to temperature strength about 1.5 wt % of the Aluminium alloy Manganese About 0.1 wt % to about 1 wt % Secondary (Mn) or preferably about 0.3 wt % to strengthening elements/ about 0.9 wt %, or preferably about re-crystallisation 0.2 wt % to about 0.8 wt % inhibitor for the Aluminium Nickel About 0.4 wt % to about 1.7 wt %, Increase high (Ni) or preferably about 0.5 wt % to temperature strength about 1.5 wt %, or more preferably of the Aluminium alloy about 0.5 wt % to about 1.3 wt % Zirconium About 0.01 wt % to about 0.3 wt % Secondary (Zr) or preferably about 0.02 wt % to strengthening elements/ about 0.25 wt %, or preferably re-crystallisation about 0.05 wt % to about 0.15 inhibitor for the wt %, preferably about 0.07 wt % Aluminium Titanium About 0.01 wt % to about 0.2 wt % Grain refiner (Ti) or preferably about 0.015 wt % to about 0.15 wt %, or more preferably about 0.02 wt % to about 0.1 wt % Strontium About 0.003 wt % to about Silicon modifier for (Sr) 0.2 wt % or preferably about 0.004 modifying the Silicon wt % to about 0.15 wt %, or more grain structure preferably about 0.005 wt % to about 0.1 wt % Aluminium Balance (apart from incidental Bulk (Al) impurities)

(11) The example embodiment of the Aluminium alloy composition in the table above may comprise one or more of the other constituents describe elsewhere in this specification. For example, it may comprise a Carbon (C) content of about 0.0005 wt % to about 0.02 wt %, preferably about 0.0007 wt % to about 0.015 wt %, more preferably about 0.001 wt % to about 0.01 wt % which acts as a grain refiner. The balance (accounting for any other optional constituents) is Aluminium.

(12) An Aluminium alloy composition according to a second preferred embodiment of the invention that is particularly suitable for use in start stop bearing applications comprises the following preferred combination of elements:

(13) TABLE-US-00002 Element Weight percent of Aluminium alloy Purpose Tin About 4 wt % to about 8 wt %, or Solid lubricant (Sn) preferably about 5 wt % to about 7 wt % Silicon About 4 wt % to about 8 wt %, or Hard particle for (Si) preferably about 4 wt % to about increasing wear 7 wt %, or more preferably about resistance of 5 wt % to about 7 wt %, or more Aluminium alloy preferably about 6 wt % composition Copper About 0.4 wt % to about 1.7 wt %, Increase high (Cu) or preferably about 0.5 wt % to temperature strength about 1.5 wt % of the Aluminium alloy Manganese About 0.1 wt % to about 1 wt % Secondary (Mn) or preferably about 0.3 wt % to strengthening elements/ about 0.9 wt %, or preferably about re-crystallisation 0.2 wt % to about 0.8 wt % inhibitor for the Aluminium Nickel About 0.4 wt % to about 1.7 wt %, Increase high (Ni) or preferably about 0.5 wt % to temperature strength about 1.5 wt %, or more preferably of the Aluminium alloy about 0.5 wt % to about 1.3 wt % Zirconium About 0.01 wt % to about 0.3 wt % Secondary (Zr) or preferably about 0.02 wt % to strengthening elements/ about 0.25 wt %, or preferably re-crystallisation about 0.05 wt % to about 0.15 inhibitor for the wt %, preferably about 0.07 wt % Aluminium Vanadium About 0.05 wt % to about 0.3 wt % Secondary (V) or preferably about 0.1 wt % to strengthening elements/ about 0.25 wt %, or more re-crystallisation preferably about 0.1 wt % to about inhibitor for the 0.2 wt % Aluminium Titanium About 0.01 wt % to about 0.2 wt % Grain refiner (Ti) or preferably about 0.01 wt % to about 0.15 wt %, or more preferably about 0.01 wt % to about 0.1 wt % Strontium About 0.003 wt % to about 0.2 Silicon modifier for (Sr) wt % or preferably about 0.004 modifying the Silicon wt % to about 0.15 wt %, or more grain structure preferably about 0.005 wt % to about 0.1 wt %

(14) The example embodiment of the Aluminium alloy composition in the table above may comprise one or more of the other constituents describe elsewhere in this specification. For example, it may comprise a Carbon (C) content of about 0.0005 wt % to about 0.02 wt %, preferably about 0.0007 wt % to about 0.015 wt %, more preferably about 0.001 wt % to about 0.01 wt % which acts as a grain refiner. The balance (accounting for any other optional constituents) is Aluminium.

(15) The following table provides some further variant of the Aluminium alloy composition according to further preferred embodiments of the present invention:

(16) TABLE-US-00003 Sn Si Cu Mn Ni Zr V Ti Sr Variant (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) 1 5.5-7.0 5.5-6.5 0.7-1.3 0.2-0.3 0.05-0.10 0.01-0.05 2 5.5-7.0 5.0-7.0 0.7-1.3 0.2-0.3 0.7-1.3 0.13-0.19 0.01-0.05 0.01-0.05 3 5.5-7.0 5.0-7.0 0.7-1.3 0.2-0.3 0.7-1.3 0.05-0.15 0.13-0.19 0.01-0.05 0.01-0.05 4 4.0-5.5 5.5-6.5 0.7-1.3 0.2-0.4 1.0-2.0 0.1-0.2 0.01-0.05 0.01-0.05 Baseline 1 10.0-14.0 3.5-5.0 0.7-1.3 0.01-0.05 0.01-0.05 Baseline 2 5.5-7.0 1.5-3.0 0.7-1.3 0.2-0.3 0.7-1.3 0.13-0.19 0.01-0.05 0.01-0.05

(17) Any of the variants in the table above may comprise one or more of the other constituents describe elsewhere in this specification and the balance of each of these variants (accounting for any other optional constituents) is Aluminium.

(18) A bearing having an Aluminium composition of Baseline 1 is described in GB2144149. A bearing having an Aluminium composition of Baseline 2 is described in EP1108797.

(19) FIG. 2 provides the results of some block-on-ring wear tests according to Active Standard ASTM G 77-05 (2010)Standard Test Method for Ranking Resistance of Materials to Sliding Wear Using Block-on-Ring Wear Test. The test conditions include: 0W30 oil; 120 C. test temperature; 5000 cycles; 200 rpm; and 267N load. The wear loss volume was determined by weighing the parts before and after the tests and converting the mass loss with the material density into a volume loss denoted as the mass loss. Furthermore, the wear loss volume was also determined by measuring the wear scar width and calculating the wear volume according to the formula provided in ASTM G77-05 (2010) denoted as the scar area.

(20) The wear results show an improvement over the known bearing elements, Baseline 1 and Baseline 2. The results show that Baseline 2, although exhibiting higher wear in the form of a greater volume loss and scar area than Baseline 1, was a further development from Baseline 1 in exhibiting greater fatigue resistance with about 55 MPa application load for Baseline 2 compared to about 45 MPa application load for Baseline 1.

(21) As discussed above, the inventors have been seeking to provide an improved sliding element (e.g. bi-metal plain bearing) having great wear resistance for start-stop applications than the known bearing elements, Baseline 1 and Baseline 2, which operates for a extended time in mixed and boundary lubrication regimes. Until now, this has required the use of a bearing element having a polymeric overlay on top of a bimetallic bearing. However, this has kept the cost of such bearings high and the inventors have been seeking to provide a more cost effective alternative. The test results demonstrate that the Aluminium alloy composition of variants 2 and 3 exhibit improved wear resistance when compared to the Baseline variants (Baseline 1 and 2) while maintaining a high fatigue resistance of about 55 MPa application load. It can be seen from these initial test results that the Aluminium alloy composition of variant 2 exhibits higher resistance to wear than the Aluminium alloy composition of variant 3 with comparable fatigue resistance of about 55 MPa application load. This would appear to make the Aluminium alloy composition of variant 2 a good prospect for use in sliding elements for engines, particularly those operating start-stop engine regimes.