ALUMINUM ALLOY FOR HIGH STRENGTH BEARINGS

Abstract

An aluminum alloy for a high strength bearing, such as those used in an internal combustion engine, is provided. The aluminum alloy includes tin (Sn) in an amount of 5.00 to 8.00 wt. %, silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %. The aluminum alloy may also include vanadium (V) or manganese (Mn). The aluminum alloy may be roll cast and hot bonded to another layer of metal. The bearing can also include a coating, for example a polymer layer applied by thermal spraying. The coating could alternatively include a nickel layer electroplated onto the aluminum alloy followed by a tin layer electroplated onto the nickel layer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims priority to U.S. provisional application no. 63/757,953, filed Feb. 13, 2025, the entire contents of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to materials used to form high strength bearings for vehicles, including aluminum alloys, coated aluminum alloys, and methods of manufacturing the same.

2. Related Art

Bearings are used in a variety of vehicle applications, including internal combustion engines. Typically, bearings are designed to provide high strength, seizure resistance, and wear resistance. Bearing which include a bronze lining have been used to achieve the high fatigue strength, but require a coating for seizure and wear resistance. Bearings which are formed of an aluminum or aluminum alloy lining have also been used because they cost less to manufacture than the bronze linings. However, improvements to high strength bearings formed of an aluminum alloy, which also have acceptable seizure resistance and hardness, are desired.

SUMMARY

One aspect of the disclosure provides a bearing comprising an aluminum alloy. The aluminum alloy includes tin (Sn) in an amount of 5.00 to 8.00 weight percent (wt. %), silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %, based on the total weight of the aluminum alloy.

Another aspect of the disclosure provides method of manufacturing a bearing. The method comprises the step of roll casting an aluminum alloy. The aluminum alloy includes tin (Sn) in an amount of 5.00 to 8.00 wt. %, silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %, based on the total weight of the aluminum alloy. The method can also include hot bonding the cast aluminum alloy to a layer of metal.

Yet another aspect of the disclosure provides method of manufacturing a bearing by applying a coating to an aluminum alloy. The aluminum alloy includes tin (Sn) in an amount of 5.00 to 8.00 wt. %, silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %, based on the total weight of the aluminum alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 illustrates a cross section of a bearing including an aluminum alloy layer according to a first example embodiment;

FIG. 2 illustrates a cross section of a bearing according to a second example embodiment;

FIG. 3 illustrate a cross section of a bearing according to a third example embodiment; and

FIG. 4 includes property testing results for uncoated and coated aluminum alloy layers according to example embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

One aspect of the disclosure provides an aluminum alloy which is capable of providing a high strength bearing having acceptable fatigue strength, seizure resistance, and wear resistance, such a bearing for use in an internal combustion engine.

According to example embodiments, the aluminum alloy includes tin (Sn) in an amount of 5.00 to 8.00 weight percent (wt. %), silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %, and typically a balance of aluminum, based on the total weight of the aluminum alloy. The aluminum alloy also includes titanium (Ti) in an amount not greater than 0.30 wt. %, iron (Fe) in an amount not greater than 0.70 wt. %, lead (Pb) in an amount less than 0.10 wt. %, other elements each in an amount of not greater than 0.05 wt. %, and the other elements in a total amount of not greater than 0.15 wt. %, based on the total weight of the aluminum alloy.

According to a first example embodiment, the silicon (Si) of the aluminum alloy is present in an amount of 2.00 to 3.00 wt. %. The aluminum alloy of the first embodiment may consist of the tin (Sn) in an amount of 5.00 to 8.00 wt. %, the silicon (Si) in an amount of 2.00 to 3.00 wt. %, the copper (Cu) in an amount of 1.00 to 2.00 wt. %, the chromium (Cr) in an amount of 0.15 to 0.25 wt. %, the titanium (Ti) in an amount not greater than 0.30 wt. %, the iron (Fe) in an amount not greater than 0.70 wt. %, the lead (Pb) in an amount less than 0.10 wt. %, the other elements each in an amount of not greater than 0.05 wt. %, the other elements in a total amount of not greater than 0.15 wt. %, and a balance of aluminum, based on the total weight of the aluminum alloy.

According to a second example embodiment, the silicon (Si) of the aluminum alloy is present in an amount of 2.00 to 3.00 wt. %, and the aluminum alloy further includes vanadium (V) in an amount of 0.15 to 0.25 wt. %. The aluminum alloy of the second embodiment may consist of the tin (Sn) in an amount of 5.00 to 8.00 wt. %, the silicon (Si) in an amount of 2.00 to 3.00 wt. %, the copper (Cu) in an amount of 1.00 to 2.00 wt. %, the chromium (Cr) in an amount of 0.15 to 0.25 wt. %, the vanadium (V) in an amount of 0.15 to 0.25 wt. %, the titanium (Ti) in an amount not greater than 0.30 wt. %, the iron (Fe) in an amount not greater than 0.70 wt. %, the lead (Pb) in an amount less than 0.10 wt. %, the other elements each in an amount of not greater than 0.05 wt. %, the other elements in a total amount of not greater than 0.15 wt. %, and a balance of aluminum, based on the total weight of the aluminum alloy.

According to a third example embodiment, the silicon (Si) of the aluminum alloy is present in an amount of 3.25 to 4.75 wt. %, the titanium (Ti) is present in an amount not greater than 0.20 wt. %, the iron (Fe) is present in an amount not greater than 0.45 wt. %, and the aluminum alloy further includes manganese (Mn) in an amount of 0.15 to 0.25 wt. %. The aluminum alloy of the third embodiment may consist of the tin (Sn) in an amount of 5.00 to 8.00 wt. %, the silicon (Si) in an amount of 3.25 to 4.75 wt. %, the copper (Cu) in an amount of 1.00 to 2.00 wt. %, the chromium (Cr) in an amount of 0.15 to 0.25 wt. %, the manganese (Mn) in an amount of 0.15 to 0.25 wt. %, the titanium (Ti) in an amount not greater than 0.20 wt. %, the iron (Fe) in an amount not greater than 0.45 wt. %, the lead (Pb) in an amount less than 0.10 wt. %, the other elements each in an amount of not greater than 0.05 wt. %, the other elements in a total amount of not greater than 0.15 wt. %, and a balance of aluminum, based on the total weight of the aluminum alloy.

Another aspect of the disclosure provides a bearing which includes a layer formed of the aluminum alloy, referred to as an aluminum alloy layer 10. The bearing can also include a base layer 12 formed of metal other than the aluminum alloy, for example steel. The aluminum alloy layer 10 can be disposed directly on the base layer 12, or one or more additional layers can be disposed between the base layer 12 and the aluminum alloy layer 10. According to an example embodiment, the aluminum alloy can be cast to form the aluminum alloy layer 10, for example by a roll casting process. The cast aluminum alloy layer 10 can then be hot bonded to the base layer 12. The cast aluminum alloy typically has a tensile strength of at least 150 MPa and an elongation of at least 5% after the casting and hot bonding steps.

The bearing can also include a coating applied to the aluminum alloy layer 10. The coating may be applied before or after casting the aluminum alloy. The coating can include a single layer or multiple layers.

According to a first example embodiment, the coating is a single layer formed of a polymer-based material, referred to as a polymer layer 14. An example of the bearing according to this embodiment is shown in FIG. 1. According to example embodiments, the polymer layer 14 includes polyamide-imide (PAI). The polymer layer 14 can also include hexagonal boron nitride, molybdenum disulfide, and/or other additions. The other additions can include components which provide wear resistance or other desirable properties. According to one example embodiment, the polymer layer 14 includes the hexagonal boron nitride in an amount of 30.1 wt. % to 34.0 wt. %, the additions in an amount of 19.5 wt. % to 25.1 wt. %, and a balance of the polyamide-imide, based on the total weight of the polymer layer 14. According to another example embodiment, the polymer layer 14 includes the molybdenum disulfide in an amount of 58.0 wt. % to 63.3 wt. %, the additions in an amount of 7.8 wt. % to 9.1 wt. %, and a balance of the polyamide-imide, based on the total weight of the polymer layer 14. The polymer layer 14 can be applied by thermal spraying.

According to other example embodiments, the coating includes multiple layers formed of metal. An example of the bearing including the metal layers is shown in FIGS. 2 and 3. According to some example embodiments, the bearing includes a layer formed of nickel, referred to as a nickel layer 16, disposed directly on the aluminum alloy layer 10. The bearing also includes a layer formed of tin, referred to as a tin layer 18, disposed over the nickel layer 16. The nickel layer 16 and the tin layer 18 are typically applied by electroplating. According to the embodiment shown in FIG. 2, the tin layer 18 is disposed directly on the nickel layer 16. According to the embodiment shown in FIG. 3, a middle layer 20 formed of NiSn, or both nickel and tin, is disposed between the nickel layer 16 and the tin layer 18. The middle layer 20 can also be applied by electroplating. Alternatively, the middle layer 20 could also be formed of nickel but processed or otherwise formed to have properties different from the nickel layer 16. For example, the middle layer 20 could be formed of nickel but include a different crystal size and/or hardness relative to the nickel layer 16.

Other metal layers besides those shown in FIGS. 2 and 3 are also possible. For example, the coating could include layers of bronze, nickel, tin, and/or copper. According to yet another example embodiment, the coating could include a first layer of bronze and nickel having a hardness ranging from 400 to 500 HV disposed on the aluminum alloy layer 10, a second layer of SnNi having a hardness of approximately 700 HV disposed on the first layer, a third layer formed of SnCu having a hardness of 20 to 40 HV disposed on the second layer, and a Sn flash layer disposed on the third layer. According to another example embodiment, the coating includes a first layer of bronze disposed on the aluminum alloy layer 10, a second layer of nickel disposed on the first layer, a third layer of SnCu disposed on the second layer, and a Sn flash layer disposed on the third layer.

Another aspect of the disclosure provides a method of manufacturing a bearing. According to example embodiments, the method includes the step of roll casting the aluminum alloy disclosed above. The example method also includes hot bonding the cast aluminum alloy to a layer of metal. As stated above, the aluminum alloy includes tin (Sn) in an amount of 5.00 to 8.00 wt. %, silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %, based on the total weight of the aluminum alloy.

The method can also include applying a coating to the aluminum alloy layer 10. According to a first example embodiment, the method includes thermal spraying the polymer layer 14 onto the aluminum alloy layer 10. According to a second example embodiment, the method includes electroplating metal layers onto the aluminum alloy layer 10. For example, the method can include electroplating the nickel layer 16 on the aluminum alloy layer 10 and then electroplating the tin layer 18 on the nickel layer 16. The method can optionally include electroplating the SnNi layer 20 between the nickel layer 16 and tin layer 18.

Experiment

Property testing was conducted on an uncoated aluminum alloy layer and coated aluminum alloy layers according to example embodiments. The aluminum alloy layers were applied to a base layer formed of steel. In each case, the aluminum alloy layer included the following composition: Al–6Sn–2.5Si–1.5Cu–0.2Cr–0.2V. The first aluminum alloy layer tested was not coated. The second aluminum alloy layer tested included an electroplated coating. The composition of the electroplated coating included the nickel layer disposed directly on the aluminum alloy layer and the tin layer including tin (Sn) in an amount greater than 99 wt. % disposed directly on the nickel layer, as shown in FIG. 2. The third aluminum alloy tested included a polymer-based coating. The composition of the polymer-based coating tested included molybdenum disulfide in an amount of 58.0 wt. % to 63.3 wt. %, the additions in an amount of 7.8 wt. % to 9.1 wt. %, and a balance of polyamide-imide (PAI).

The property testing included an Underwood Test (UW). An accelerated rotating-shaft fatigue and wear test commonly used for engine bearings was performed on the uncoated and coated aluminum alloy layers. The test lasted for 250 hours and evaluated the following:

Fatigue limit (MPa): Maximum applied surface pressure the bearing can sustain;

Wear depth (µm): Material loss after the test run; and

Surface damage (%): Fraction of the surface showing wear or distress.

For each aluminum alloy layer variant, the highest fatigue load that produced acceptable results is the relevant value. Lower loads (e.g., 110MPa) were used first. If the lower load passed, the load was increased until the aluminum alloy layer reached its limit. The results of the Underwood Test (UW) are disclosed in FIG. 4. The test results illustrate exceptional performance is achieved by both the uncoated and coated aluminum alloy layer.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the following claims.

Claims

1. A bearing, comprising:

an aluminum alloy, the aluminum alloy including tin (Sn) in an amount of 5.00 to 8.00 weight percent (wt. %), silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %, based on the total weight of the aluminum alloy.

2. The bearing of claim 1, wherein the aluminum alloy includes titanium (Ti) in an amount not greater than 0.30 wt. %, iron (Fe) in an amount not greater than 0.70 wt. %, lead (Pb) in an amount less than 0.10 wt. %, other elements each in an amount of not greater than 0.05 wt. %, and the other elements in a total amount of not greater than 0.15 wt. %, based on the total weight of the aluminum alloy.

3. The bearing of claim 2 including the silicon (Si) in an amount of 2.00 to 3.00 wt. %.

4. The bearing of claim 3 consisting of the tin (Sn) in an amount of 5.00 to 8.00 wt. %, the silicon (Si) in an amount of 2.00 to 3.00 wt. %, the copper (Cu) in an amount of 1.00 to 2.00 wt. %, the chromium (Cr) in an amount of 0.15 to 0.25 wt. %, the titanium (Ti) in an amount not greater than 0.30 wt. %, the iron (Fe) in an amount not greater than 0.70 wt. %, the lead (Pb) in an amount less than 0.10 wt. %, the other elements each in an amount of not greater than 0.05 wt. %, the other elements in a total amount of not greater than 0.15 wt. %, and a balance of aluminum, based on the total weight of the aluminum alloy.

5. The bearing of claim 2 including the silicon (Si) in an amount of 2.00 to 3.00 wt. % and vanadium (V) in an amount of 0.15 to 0.25 wt. %.

6. The bearing of claim 5 consisting of the tin (Sn) in an amount of 5.00 to 8.00 wt. %, the silicon (Si) in an amount of 2.00 to 3.00 wt. %, the copper (Cu) in an amount of 1.00 to 2.00 wt. %, the chromium (Cr) in an amount of 0.15 to 0.25 wt. %, the vanadium (V) in an amount of 0.15 to 0.25 wt. %, the titanium (Ti) in an amount not greater than 0.30 wt. %, the iron (Fe) in an amount not greater than 0.70 wt. %, the lead (Pb) in an amount less than 0.10 wt. %, the other elements each in an amount of not greater than 0.05 wt. %, the other elements in a total amount of not greater than 0.15 wt. %, and a balance of aluminum, based on the total weight of the aluminum alloy.

7. The bearing of claim 2 including the silicon (Si) in an amount of 3.25 to 4.75 wt. %, manganese (Mn) in an amount of 0.15 to 0.25 wt. %, the titanium (Ti) in an amount not greater than 0.20 wt. %, and the iron (Fe) in an amount not greater than 0.45 wt. %.

8. The bearing of claim 7 consisting of the tin (Sn) in an amount of 5.00 to 8.00 wt. %, the silicon (Si) in an amount of 3.25 to 4.75 wt. %, the copper (Cu) in an amount of 1.00 to 2.00 wt. %, the chromium (Cr) in an amount of 0.15 to 0.25 wt. %, the manganese (Mn) in an amount of 0.15 to 0.25 wt. %, the titanium (Ti) in an amount not greater than 0.20 wt. %, the iron (Fe) in an amount not greater than 0.45 wt. %, the lead (Pb) in an amount less than 0.10 wt. %, the other elements each in an amount of not greater than 0.05 wt. %, the other elements in a total amount of not greater than 0.15 wt. %, and a balance of aluminum, based on the total weight of the aluminum alloy.

9. The bearing of claim 1 including a coating applied to the aluminum alloy, wherein coating is a polymer-based coating.

10. The bearing of claim 9, wherein the polymer is polyamide-imide.

11. The bearing of claim 1 including a coating applied to the aluminum alloy, wherein coating includes a layer of nickel disposed on the aluminum alloy, a layer of tin disposed over the layer of nickel, and optionally a layer including nickel and tin disposed therebetween.

12. The bearing of claim 1, wherein the aluminum alloy is cast and bonded to a layer formed of metal.

13. The bearing of claim 1, wherein the aluminum alloy has a tensile strength of at least 150 MPa and an elongation of at least 5%.

14. A method of manufacturing a bearing, comprising the steps of: roll casting an aluminum alloy, the aluminum alloy including tin (Sn) in an amount of 5.00 to 8.00 wt. %, silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %, based on the total weight of the aluminum alloy.

15. The method of claim 14 including hot bonding the cast aluminum alloy to a layer of metal.

16. The method of claim 15, wherein the aluminum alloy has a tensile strength of at least 150 MPa and an elongation of at least 5% after the hot bonding step.

17. A method of manufacturing a bearing, comprising the steps of:

applying a coating to an aluminum alloy, the aluminum alloy including tin (Sn) in an amount of 5.00 to 8.00 wt. %, silicon (Si) in an amount of 2.00 to 4.75 wt. %, copper (Cu) in an amount of 1.00 to 2.00 wt. %, chromium (Cr) in an amount of 0.15 to 0.25 wt. %, and aluminum (Al) in an amount of at least 80.00 wt. %, based on the total weight of the aluminum alloy.

18. The method of claim 17, wherein the step of applying the coating includes spraying a polymer-based material on the aluminum alloy.

19. The method of claim 17, wherein the step of applying the coating includes electroplating nickel on the aluminum alloy, electroplating tin over the nickel, and optionally electroplating a mixture of nickel and tin therebetween.

20. The method of claim 17 including casting the aluminum alloy before or after applying the coating.