Dry mechanism with multi-layer coating

Abstract

The present disclosure relates to a mechanism comprising a plurality of components, a first of which comprises a first contact surface and a second of which comprises a second contact surface arranged to contact and move relative to the first contact surface. The first contact surface is provided by a multilayer coating (4) directly on a surface (5) of a metal substrate of the first component. The multilayer coating comprises a base layer arrangement (43) arranged directly on the surface of the substrate, a composite layer (41) arranged on top of the base layer arrangement, and a metal top layer (42) arranged directly on top of the composite layer, the composite layer being comprised of particles (7) of graphene and related materials, GRM materials, in a metal matrix (8).

Description

[Technical Field]

[0001]

[0001] The present disclosure relates to a mechanism comprising a plurality of parts, a first part of the plurality of parts comprising a first contact surface, a second part of the plurality of parts comprising a second contact surface arranged to contact the first contact surface and move relative to the first contact surface, and at least one of the first contact surface and the second contact surface being provided by a coating directly on a surface of a metal substrate of the part to provide dry lubrication. [Background technology]

[0002]

[0002] For typical electrical switching devices, the mechanical drive system relies on lubrication by grease. Grease reduces friction in the mechanical system and minimizes mechanical wear. However, drawbacks include a limited temperature range, grease degradation due to particulate contamination, and grease thickening due to aging or low temperatures, resulting in the need for periodic maintenance and re-greasing. Grease thickening can also result in increased static friction and potentially increased operating times, which can significantly impact switching performance. In the worst case, lubrication failure can result in a complete shutdown of the switching device, which can have very serious and costly consequences. Summary of the Invention

[0003]

[0003] It is an object of the present invention to provide improved, preferably dry (i.e., without the use of grease), metal mechanisms, e.g., drives and / or actuators, typically for electrical devices such as switchgear and / or control gear, which have reduced maintenance requirements compared to greased mechanisms.

[0004] According to one aspect of the present invention, a mechanism is provided that includes a plurality of components, a first component of the plurality of components having a first contact surface and a second component having a second contact surface arranged to contact the first contact surface and move relative to the first contact surface. The first contact surface is provided by a multilayer (ML) coating on a surface of a metal substrate of the first component. The ML coating includes a base layer arrangement disposed on, preferably directly on, the surface of the substrate. The ML coating also includes a composite layer disposed on, preferably directly on, the base layer arrangement, where the composite layer is composed of particles of a Graphene and Related Materials (GRM) material in a metal matrix. The ML coating also includes a metal top layer disposed on, preferably directly on, the composite layer.

[0005]

[0005] In accordance with another aspect of the present invention, an electrical device comprising an electrical conductor and an embodiment of the mechanism of the present disclosure is provided.

[0006] According to another aspect of the present invention, there is provided a method for coating a metal substrate of a component for a mechanism. The method comprises providing a metal electrolyte containing metal ions and depositing a base layer arrangement on a surface of the substrate by electrodeposition, whereby the metal ions are deposited to form a metal base layer arrangement on, and preferably directly on, the surface of the substrate. The method also comprises providing a metal-GRM electrolyte containing GRM particles and the metal ions and depositing a composite layer on the base layer arrangement by electrodeposition, whereby the GRM particles and the metal ions are co-deposited to form a metal-GRM composite layer on top of the base layer arrangement. The method also comprises providing a metal electrolyte containing metal ions and depositing a top layer on the composite layer by electrodeposition, whereby the metal ions are deposited to form a metal top layer on top of, and preferably directly on top of, the composite layer.

[0007]

[0007] The metal-GRM composite layer within or at the first and / or second contact surface(s) provides dry lubrication, reducing or eliminating the need for lubrication maintenance over the life of the mechanism. Also, by eliminating the need for grease, the lubrication and lubrication effect may be more stable over time and more resistant to, for example, high or low temperatures, and dust or other contaminants. The corrosion resistance of metal parts may also be improved by the metal-GRM composite layer.

[0008]

[0008] Further advantages can be achieved by using a multilayer (ML) coating that includes a base layer arrangement and a top layer in addition to a metal-GRM (Me-GRRM) composite layer. The base layer arrangement can protect the substrate from corrosion, e.g., oxidation. For example, a base layer arrangement comprising or consisting of a nickel base layer has been shown to effectively protect a steel substrate from oxidation, presumably by oxidizing the nickel (forming nickel oxide) instead of the steel. For example, a nickel base layer arrangement can also improve adhesion of the composite layer to the substrate (e.g., a steel substrate). Similarly, the top layer can protect the composite layer from corrosion, e.g., oxidation. For example, a nickel top layer has been shown to effectively protect a copper metal matrix from oxidation, presumably by oxidizing the nickel (forming nickel oxide) instead of the copper. Preferably, the top layer is relatively thin, e.g., has an average thickness of less than 1 micrometer (μm), so that the top layer cracks upon contact with another contact surface, exposing the composite layer, so that the lubricating properties of the GRM particles can still be exhibited on the contact surface provided by the ML coating, even in the early stages of use.

[0009]

[0009] It should be noted that any feature of any of the aspects may be applied to any of the other aspects, where appropriate. Similarly, any advantage of any of the aspects may be applied to any of the other aspects. Other objects, features, and advantages of the enclosed embodiments will become apparent from the following detailed disclosure, from the attached dependent claims, and from the drawings.

[0010] In general, all terms used in the claims should be interpreted according to their ordinary meaning in the art unless expressly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, step, etc." should be openly interpreted as referring to at least one instance of the element, apparatus, component, means, step, etc., unless expressly stated otherwise. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless explicitly stated otherwise. The use of "first," "second," etc. for different features / components of the present disclosure is intended only to distinguish the feature / component from other similar features / components, and is not intended to impose any order or hierarchy on the features / components.

[0011]

[0011] Embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic circuit diagram of an electrical device according to some embodiments of the present invention. [Figure 2a] FIG. 2a is a schematic block diagram of an electric device and its driving mechanism according to some embodiments of the present invention. [Figure 2b] FIG. 2b is a schematic side view of a multilayer coating on a metal substrate, according to some embodiments of the present invention. [Figure 3] FIG. 3 is a schematic, partial cross-sectional side view of an electrodeposition bath according to some embodiments of the present invention. [Figure 4] FIG. 4 is a schematic flow diagram of some embodiments of the method of the present invention. [Figure 5] FIG. 5 is an exemplary graph of a standard pin-on-disk reciprocating test at 3 Newtons (N) comparing the friction of an embodiment of the ML coating of the present invention with a standard grease solution against a spherical chrome-plated steel counterface. DETAILED DESCRIPTION OF THE INVENTION

[0013]

[0012] Embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which certain specific embodiments are shown. However, other embodiments in many different forms are possible within the scope of this disclosure. Rather, the following embodiments are provided as examples so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0014]

[0013] In accordance with the present invention, a metal-GRM composite is used. Graphene and related materials (GRMs) include graphene (G), graphene oxide (GO), reduced GO (rGO), and any combination thereof. Thus, when GRMs are referred to herein, any such material is encompassed by this term. As used herein, the term graphene (G) is used generically for a 2D honeycomb lattice of carbon atoms in the form of single-layer sheets, double-layer sheets, few-layer (3-5) sheets, or nanoplatelets having an average (e.g., number-average) thickness of up to 50 nm, e.g., in the range of 0.3 to 50 nm. Also, when graphene is described herein, it should be understood that some of the graphene may be in the form of graphene oxide (GO) or reduced GO (rGO). Thus, graphene or GRMs may be pure graphene or may comprise a mixture of pure graphene with GO and / or rGO. Preferred GRM particles are, for example, graphene nanoplatelets (GnPs) having an average (eg, number average) thickness in the range of 5 to 50 nm.

[0015] 1 illustrates an electric device 10, such as, for example, a switching device and / or a control device, comprising an electric switch 11 for switching a current I having a voltage U and being conducted by an electric conductor 12. The electric device 10 comprises an embodiment of a mechanism 1 of the present disclosure, such as an actuator, a drive or a mechanical joint, such as a pin joint, as well as a switch 11 (and possibly further switches 11) and an electric conductor 12 (and possibly further conductors 12). The electric device 10 may be any switching device or control device configured to interrupt or switch the current I by means of at least one switch 11 and / or to conduct the current I by means of at least one electric conductor 12. The electric device 10 may be configured to interrupt or switch the current I, for example, having a voltage in the low voltage range up to 1 kV, for example, in the range of 0.01 to 1 kV, or in the medium voltage range, for example, in the range of 1 to 52 kV.

[0016]

[0015] Figure 2a illustrates an electrical device 10, such as a switchgear and / or control device as described above, that includes a mechanical mechanism 1, e.g., a drive and / or actuator, or a joint, e.g., a pin joint, which may or may not be part of the drive or actuator. The mechanism 1 may be arranged to operate, for example, an electrical switch 11. While the mechanism 1 may be included in an electrical device, it is typically not intended to conduct electricity. Thus, the mechanism 1 and any of its components 2 are typically not arranged to conduct electric current I; current is instead conducted by a conductor 12. The mechanism 1 may be actuated in any conventional manner, such as by a magnetically or pneumatically actuated spring. The mechanism 1 includes multiple components 2 that are arranged to move relative to one another during operation of the mechanism. The mechanism 1 is typically a metallic mechanism, which implies that at least the substrate 3 of each of the components 2 is made of a metallic material. Two components 2 that are arranged to contact and move relative to one another each include a contact surface 6 for contacting a corresponding contact surface 6 of the other component 2. At least one contact surface 6 of at least one component 2 of mechanism 1 is provided with an ML coating of the present disclosure arranged to act as a dry lubricant, reducing or eliminating the need to grease mechanism 1.

[0017] In the embodiment of FIG. 2a, the first component 2a has a first contact surface 6a, and the second component 2b has a second contact surface 6b, where the first and second contact surfaces 6a and 6b are arranged to contact each other and move relative to each other (as indicated by the downward arrows in the figure). The first contact surface 6a is provided by a multilayer coating 4 disposed directly on the surface 5 of the metal substrate 3 of the first component 2a. The coating 4 is thus disposed on the substrate 3, typically on the surface 5 of the substrate, so that the coating 4 is in direct contact with the metallic material of the substrate 3. The metallic material of the substrate 3 may comprise or consist of (typically consist of) steel, e.g., low-carbon steel such as DC01, high-strength steel such as CrMo steel, or stainless steel such as SS304. The steel may provide the desired strength and durability for the mechanism 1. If the component 2 is in the form of a spring or is part of a spring, the substrate 3 may be made of spring steel.

[0018] The ML coating 4 can form a tribofilm on the contact surface 6a while sliding against the contact surface 6b of the second component 2b. This dry solution provides a coefficient of friction comparable to that of a grease solution, for example in the range of 0.15 to 0.25.

[0019]

[0018] The coating 4 is preferably produced by electrodeposition (also called electroplating), although other coating methods such as cold spraying and laser or oven sintering are also possible.

[0020]

[0019] Figure 2b illustrates an embodiment of the ML coating 4. The ML coating 4 comprises a composite layer 41 of GRM particles 7 in a metal matrix 8. The metal of the matrix may conveniently be or comprise (preferably consist of) copper (Cu). The composite layer 41 may have an average thickness of up to 100 µm, for example in the range of 10 to 50 µm, preferably 15 to 20 µm.

[0021] The GRM content in composite layer 41 can be in the range of 0.1 to 3 or 2 wt. %, preferably in the range of 0.3 to 1.5 or 1 wt. %, thus a concentration that provides self-lubricating properties and improved wear resistance and high temperature resistance without substantially changing the mechanical properties of the matrix metal 8. Preferably, composite layer 41 can be composed solely of GRM and Me, with GRM particles 7 dispersed within the Me matrix 8.

[0022] The GRMs 7 are preferably present as few-layer graphene sheets 7 (also referred to herein as graphene nanoplatelets, GnPs), with a preferred thickness in the range of 1-50 nm. The GRM sheets 7 each have a lateral size, described herein as the longest diameter, which is several times greater than the thickness, resulting in a platelet morphology (also referred to as a flake or sheet morphology). In some embodiments, the GRM sheets 7 each have a longest diameter in the range of 5-80 μm.

[0023] The metallic top layer 42 of the coating 4 is disposed directly on top of the composite layer 41 and may protect the metal of the matrix 8 in the composite layer 41 from corrosion, specifically oxidation in ambient air, and possibly from other corrosion, such as chemical (e.g., acid or salt) corrosion. Typically, the top layer 42 is composed of a metal, a pure metal, or a metal alloy, as well as any metal oxide resulting from oxidation of the metal. The metal of the top layer may preferably be pure nickel or a nickel alloy. The advantage of using nickel is that, particularly when the metal of the matrix 8 is copper, the nickel in the top layer oxidizes instead of the matrix copper, protecting the composite layer 41 from oxidation. Thus, the top layer 42 may be composed of metallic nickel or a nickel alloy, and, if part of the nickel oxidizes, nickel oxide.

[0024]

[0023] The top layer 42 is preferably substantially thinner than the composite layer 41. The top layer 42 is preferably thin enough not to significantly reduce the lubricating effect of the composite layer 41 on the contact surface 6a. In some embodiments, the top layer 42 has an average thickness of at most 1 μm, e.g., in the range of 400-700 nm. Any thickness described herein may be determined by scanning electron microscopy (SEM), such as, for example, a backscattered electron (BSE) SEM.

[0025] Similarly, the metal substrate arrangement 43 of the coating 4 is disposed directly on the surface 5 of the substrate 3 and can protect the substrate's metal (e.g., steel) from corrosion, specifically oxidation in ambient air, and possibly from other corrosion, such as chemical (e.g., acid or salt) corrosion. The composite layer 41 is then disposed on top of the substrate arrangement 43, for example, directly on top of the substrate arrangement 43 or via an intermediate transition or adhesive layer. The substrate arrangement 43 can consist of a single substrate, or it can consist of multiple substrates, for example, two or three separate substrates, disposed directly on top of each other on the surface 5 of the substrate 3. Typically, each substrate of the substrate arrangement 43 is composed of a pure metal or metal alloy, as well as any metal oxide resulting from the oxidation of the pure metal. The substrate metal can be pure copper or pure nickel, or an alloy of copper and / or nickel. Preferably, the metal of at least one substrate is pure nickel. The advantage of using nickel is that the nickel substrate is oxidized instead of the substrate metal. An advantage of using copper in the base layer may be improved adhesion of the composite layer 41 to the copper matrix 8. The base layer arrangement 43 may conveniently have an average thickness of at least 1 μm, for example in the range of 5 to 20 μm. The base layers within the base layer arrangement 43, for example nickel base layers, may have an average thickness in the range of 3 to 10 μm.

[0026]

[0025] When the substrate 3 is low-carbon steel, e.g., DC01, the substrate arrangement may advantageously comprise a copper substrate between the substrate and the nickel substrate. An exemplary substrate arrangement 43 comprises or consists of a (pure) copper substrate having an average thickness in the range of 5-10 μm, preferably disposed directly on the surface 5 of the substrate 3, and a (pure) nickel substrate having an average thickness in the range of 3-6 μm (e.g., about 5 μm), preferably disposed directly on the copper substrate. On the other hand, for example, when the substrate 3 is comprised of high-strength steel (CrMo) or stainless steel (e.g., SS304), the copper substrate may not be required or may not be convenient at all. Therefore, another exemplary substrate arrangement 43 comprises or consists of a (pure) nickel substrate having an average thickness in the range of 5-10 μm, preferably disposed directly on the surface 5 of the substrate 3, and preferably no copper substrate.

[0027] FIG. 3 illustrates an electrodeposition arrangement or electrodeposition bath 30 for the electrodeposition of the layers of coating 4.

[0028] For the layer of underlayer arrangement 43, an exemplary Me electrolyte 33, typically aqueous, comprises Me ions 34 (but not GRM particles 7). The substrate 3 functions as a cathode and is connected to a voltage source 31, as is a corresponding anode 32. The anode 32 can be, for example, a copper (sacrificial) anode or a mixed-oxide inert anode. By applying a voltage between the substrate 3 and the anode 32 by the voltage source 31, Me ions 34 are deposited (and reduced) on top of the surface 5 of the substrate 3 to form the metal underlayer arrangement 43. The Me ions 34 are typically provided by dissolving a metal salt, e.g., a nickel salt or a copper salt such as CuSO4 and / or CuCl2, in the electrolyte 33. In some embodiments, the metal salt content in the solution 33 is in the range of 50 to 250 grams per liter (g / L). An exemplary electrolyte 33 for the substrate comprises 50-300 g / L CuSO4, 20-250 ppm CuCl2, and 10-200 g / L H2SO4.

[0029] For composite layer 41, an exemplary Me-GRM electrolyte solution 33, typically aqueous, comprises GRM particles 7, typically in the form of GnP, and Me ions 34. Substrate 3 functions as a cathode and is connected to voltage source 31, as is corresponding anode 32. By applying a voltage between substrate 3 and anode 32 by voltage source 31, GRM particles 7 and Me ions 34 are co-deposited on top of base layer 43 to form composite layer 41. Me ions 34 are typically provided by dissolving a metal salt, e.g., a copper salt such as CuSO4 and / or CuCl2, in electrolyte solution 33. In some embodiments, the metal salt content in solution 33 is in the range of 50 to 250 grams per liter (g / L). An example electrolyte solution 33 for composite layer 41 comprises 50-300 g / L of CuSO, 10-400 ppm of CuCl, 0.01-10 g / L of graphene, and 0.01-10 g / L of dispersing agent. The content of GRM in solution 33 may preferably be in the range of 0.01-1.5 g / L.

[0030] As with the base layer, for the top layer 42, an exemplary Me electrolyte 33, typically aqueous, comprises Me ions 34 (but does not comprise GRM particles 7). The substrate 3 functions as a cathode and is connected to a voltage source 31, as is the corresponding anode 32. By applying a voltage between the substrate 3 and the anode 32 via the voltage source 31, the Me ions 34 are deposited (and reduced) on top of the composite layer 41 to form a metallic top layer 42. Again, the Me ions 34 are typically provided by dissolving a metal salt, such as a nickel salt, in the electrolyte 33. In some embodiments, the metal salt content in the solution 33 is in the range of 50 to 250 grams per liter (g / L). An exemplary electrolyte 33 for the top layer 42 comprises 50 to 300 g / L of CuSO, 20 to 250 ppm of CuCl, and 10 to 200 g / L of HSO.

[0031] FIG. 4 illustrates some embodiments of a method for coating a metal substrate 3 of a part 2 of a mechanism 1 for, for example, an electrical device 10.

[0032]

[0031] This method comprises providing a metal electrolyte 33 comprising metal ions 34, preferably nickel ions or copper ions, S1 to arrange a base layer arrangement 43 on a substrate 3, and depositing a base layer of the base layer arrangement 43 on the surface 5 of the substrate 3, for example directly thereon, by electrodeposition S2, whereby the metal ions 34 are deposited (and reduced) to form a metal base layer on the surface of the substrate.

[0033]

[0032] The method then includes providing a metal-GRM electrolyte 33 comprising GRM particles 7 and metal ions 34, preferably copper ions, S3 to dispose a composite layer 41 on top of the substrate arrangement 43, and depositing the composite layer 41 by electrodeposition S4 on the substrate arrangement 43, for example directly thereon, whereby the GRM particles 7 and metal ions 34 are co-deposited to form a metal-GRM composite layer on top of the substrate arrangement.

[0034]

[0033] The method then comprises providing a metal electrolyte 33 comprising metal ions 34, preferably nickel ions, S5 to place a top layer 42 on top of the composite layer 41, and depositing the top layer 42 by electrodeposition S6 on the composite layer 41, preferably directly thereon, whereby the metal ions 34 are deposited (and reduced) to form a metal top layer on top of the composite layer.

[0035] 5 shows an exemplary graph of a standard pin-on-disk reciprocating test at 3 Newtons (N) comparing the friction of an embodiment of the ML coating of the present invention with a standard grease solution. As can be seen, the ML coating 4 of the present invention provides low friction similar to that of conventional grease.

[0036]

[0035] The present disclosure has been described above primarily with reference to certain embodiments. However, as will be readily recognized by those skilled in the art, embodiments other than those disclosed above are equally possible within the scope of the present disclosure as defined by the appended claims.

Claims

1. A mechanism (1) comprising a plurality of parts (2), wherein a first part (2a) of the plurality of parts (2) comprises a first contact surface (6a) and a second part (2b) comprises a second contact surface (6b) arranged in contact with and movable relative to the first contact surface (6a); The first contact surface (6a) is provided by a multilayer coating (4) on the surface (5) of the metal substrate (3) of the first part (2a), the multilayer coating (4) comprising: a base layer arrangement (43) disposed on the surface (5) of the substrate (3); a composite layer (41) disposed on top of the base layer arrangement (43), wherein the composite layer is composed of particles (7) of graphene and related materials, GRM materials, in a metal matrix (8); a metal top layer (42) disposed on top of the composite layer (41); A mechanism (1) comprising:

2. The arrangement of claim 1 , wherein the top layer (42) is of nickel or a nickel alloy, for example, comprised of metallic nickel or a nickel alloy, and optionally nickel oxide.

3. The arrangement according to claim 1 or claim 2, wherein the top layer (42) has a thickness of at most 1 μm, for example in the range of 400 to 700 nm.

4. 4. The arrangement according to claim 1, wherein the substrate arrangement (43) comprises or consists of a substrate of nickel or a nickel alloy, for example made of metallic nickel and, optionally, nickel oxide, and / or a substrate of copper or a copper alloy.

5. An arrangement according to any one of claims 1 to 4, wherein the substrate arrangement (43) has a thickness of at least 1 μm, for example in the range of 5 to 20 μm.

6. A mechanism according to any one of claims 1 to 5, wherein said metal matrix (8) is of copper.

7. The arrangement according to any one of claims 1 to 6, wherein the content of said GRM in said composite layer (41) is in the range of 0.1 to 3 wt%, preferably 0.3 to 1.5 wt%.

8. The mechanism according to any one of claims 1 to 7, wherein the particles (7) are in the form of sheets having a thickness in the range of 0.3 to 50 nm, for example graphene nanoplatelets, GnPs, having a thickness in the range of 5 to 50 nm.

9. Arrangement according to any one of the preceding claims, wherein said composite layer (41) has a thickness in the range of 10 to 50 μm, preferably 15 to 20 μm.

10. Arrangement according to any one of the preceding claims, wherein the substrate (3) is of steel, for example DC01.

11. 11. The mechanism (1) according to any one of claims 1 to 10, wherein the mechanism (1) is an actuator, a drive or a mechanical joint, e.g. a pin joint, for example for a switching device or a control device, and wherein the parts (2a, 2b) are not arranged to conduct an electric current (I).

12. A conductor (12); A mechanism (1) according to any one of claims 1 to 11, An electrical device (10) comprising:

13. 13. The electrical device of claim 12, wherein the electrical device (10) is a switchgear and / or control device, for example comprising an electrical switch (11) such as a circuit breaker or a contactor.

14. A method for coating a metal substrate (3) of a component (2) for a mechanism (1), said method comprising the steps of: providing (S1) a metal electrolyte (33) containing metal ions (34) for a substrate arrangement (43); depositing (S2) by electrodeposition at least one layer of the base layer arrangement (43) on the surface (5) of the substrate (3), whereby the metal ions (34) are deposited to form a metal base layer on the surface of the substrate; providing (S3) a metal-GRM electrolyte (33) comprising GRM particles (7) and metal ions (34) for a composite layer (41); depositing (S4) the composite layer (41) on the substrate arrangement (43) by electrodeposition, whereby the GRM particles (7) and metal ions (34) are co-deposited to form a metal-GRM composite layer on top of the substrate arrangement; providing (S5) a metal electrolyte (33) comprising metal ions (34) for the top layer (42); depositing (S6) the top layer (42) on the composite layer (41) by electrodeposition, whereby the metal ions (34) are deposited to form a metal top layer on top of the composite layer; A method comprising:

15. 15. The method of claim 14, wherein the metal ions (34) of the metal electrolyte (33) of the top layer (42) are nickel ions.

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