Dry mechanism with multi-layer coating

Abstract

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

Description

Technical Field

[0001] The present disclosure relates to a mechanism comprising a plurality of components, wherein a first component comprises a first contact surface, and a second component comprises a second contact surface arranged to move relative to and in contact with the first contact surface, wherein at least one of the first and second contact surfaces is provided by a coating located directly on a surface of a metal substrate of the components to provide dry lubrication. Background Art

[0002] In typical electrical switchgear, the mechanical drive system relies on oil lubrication. Lubricants reduce friction in the mechanical system and minimize mechanical wear. However, these systems also have drawbacks such as limited temperature range, lubricant degradation due to particle contamination, and lubricant thickening due to aging or low temperatures, necessitating regular maintenance and re-lubrication. Furthermore, lubricant thickening can lead to increased static friction and potentially increased operating time, significantly impacting switching performance. In the worst case, lubrication failure can lead to complete functional failure of the switchgear, resulting in serious and costly consequences. Summary of the Invention

[0003] It is an object of the present invention to provide an improved, preferably dry (i.e. not using lubricating oil) metal mechanism, such as a drive and / or actuator, typically used in electrical equipment such as switchgear and / or controlgear, which has lower maintenance requirements compared to lubricated mechanisms.

[0004] According to one aspect of the present invention, a mechanism comprising a plurality of components is provided, wherein a first component comprises a first contact surface, and a second component comprises a second contact surface, the second contact surface being arranged to move relative to and in contact with 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 comprises a base layer structure disposed (preferably directly disposed) on the substrate surface. The ML coating further comprises a composite layer disposed (preferably directly disposed) on top of the base layer structure, the composite layer comprising material particles of graphene and related materials (GRMs) in a metal matrix. The ML coating further comprises a metal top layer disposed (preferably directly disposed) on top of the composite layer.

[0005] According to another aspect of the present invention, there is provided an electrical device comprising an electrical conductor and an embodiment of the mechanism according to the present disclosure.

[0006] According to another aspect of the present invention, a method for coating a metal substrate of a component of a mechanism is provided. The method comprises providing a metal electrolyte comprising metal ions, and depositing a base layer structure on the surface of the substrate by electrodeposition, thereby depositing the metal ions to form a metal base layer structure on the surface of the substrate (preferably directly on the surface of the substrate). The method further comprises providing a metal-GRM electrolyte comprising GRM particles and metal ions, and depositing a composite layer on the base layer structure by electrodeposition, thereby co-depositing the GRM particles and metal ions to form a metal-GRM composite layer on top of the base layer structure. The method further comprises providing a metal electrolyte comprising metal ions, and depositing a top layer on the composite layer by electrodeposition, thereby depositing metal ions to form a metal top layer on top of the composite layer (preferably directly on top of the composite layer).

[0007] By providing a metal-GRM composite layer within or at the first and / or second contact surfaces, dry lubrication is provided, thereby reducing or eliminating the need for lubrication maintenance over the life of the mechanism. Furthermore, by eliminating the need for lubricating oil, lubrication and lubrication effectiveness can be more stable over time and more resistant to, for example, high or low temperatures and dust or other contaminants. The metal-GRM composite layer can also improve the corrosion resistance of the metal component.

[0008] Further advantages are obtained by using a multilayer (ML) coating that includes, in addition to the metal-GRM (Me-GRRM) composite layer, a base layer structure and a top layer. The base layer structure can protect the substrate from corrosion, such as oxidation. For example, it has been shown that a base layer structure including or consisting of a nickel base layer can effectively avoid oxidation of a steel substrate, presumably through oxidation of the nickel (forming nickel oxide) rather than oxidation of the steel. A base layer structure consisting of, for example, nickel can also improve the adhesion of the composite layer to the substrate (e.g., a steel substrate). Similarly, the top layer can protect the composite layer from corrosion, such as oxidation. For example, a nickel top layer has been shown to effectively avoid oxidation of a copper metal substrate, presumably through oxidation of the nickel (forming nickel oxide) rather than oxidation of the copper. Preferably, the top layer is relatively thin, for example with an average thickness of less than 1 micrometer (μm), so that the top layer can break when in contact with another contact surface, thereby exposing the composite layer, so that the lubricating properties of the GRM particles can still be present on the contact surface provided by the ML coating, which is now in its initial use stage.

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

[0010] In general, unless otherwise expressly defined herein, all terms used in the claims are to be understood in accordance with their original meanings in the technical field. Unless otherwise expressly stated, all references to "one / an element, device, component, method, step, etc." are to be understood as referring to at least one instance of the element, device, component, method, step, etc. Unless expressly stated otherwise, the steps of any method disclosed herein do not have to be performed in the exact order disclosed. References to "first," "second," etc., for different features / components of the present disclosure are intended only to distinguish these features / components from other similar features / components, rather than to assign any order or hierarchy to these features / components. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following will describe the embodiments by way of example with reference to the accompanying drawings. In the accompanying drawings:

[0012] Figure 1 is a circuit schematic diagram of an electrical device according to some embodiments of the present invention.

[0013] Figure 2a is a schematic block diagram of an electrical device and a driving mechanism thereof according to some embodiments of the present invention.

[0014] Figure 2b is a schematic side view of a multilayer coating of a metal substrate according to some embodiments of the present invention.

[0015] Figure 3 is a schematic cross-sectional side view of an electrodeposition bath according to some embodiments of the present invention.

[0016] Figure 4 is a schematic flow chart of some embodiments of the method according to the present invention.

[0017] Figure 5 is an example graph of a standard reciprocating pin-on-disc friction and wear test at 3 Newtons (N) comparing the friction of an ML coating embodiment of the present invention to a standard lubricated oil solution against a spherical chrome-plated steel countertop. DETAILED DESCRIPTION

[0018] Embodiments will now be described more fully below with reference to the accompanying drawings that illustrate certain embodiments. However, many other embodiments are possible within the scope of the present disclosure. Rather, the following embodiments are provided by way of example only to make this disclosure thorough and complete and to fully convey the scope of this disclosure to those skilled in the art. Similar reference numerals are used throughout this specification to refer to similar elements.

[0019] According to the present invention, metal-GRM composite materials are used. Graphene and related materials (GRM) include graphene (G), graphene oxide (GO), reduced GO (rGO) and any combination thereof. Therefore, when referring to GRM in this article, the term encompasses any of these materials. In this article, the term graphene (G) is used as a general term for carbon atoms in a two-dimensional honeycomb lattice, which is a single-layer sheet, a double-layer sheet, a multilayer (3 to 5 layers) sheet or an average (e.g., number average) thickness of a nanosheet of up to 50 nm (e.g., in the range of 0.3 nm to 50 nm). In addition, when discussing graphene in this article, it should be understood that some graphene may exist in the form of graphene oxide (GO) or reduced GO (rGO). Therefore, graphene or GRM can be pure graphene, or a mixture of pure graphene and GO and / or rGO. Preferred GRM particles are graphene nanosheets (GnP), whose average (number average) thickness is, for example, in the range of 5 nm to 50 nm.

[0020] Figure 1 An electrical device 10, such as a switchgear and / or control device, is shown, including an electrical switch 11 for switching an electrical current I having a voltage U and conducted by an electrical conductor 12. The electrical device 10 includes an embodiment of a mechanism 1 according to the present disclosure, such as an actuator, a drive, or a mechanical joint such as a pin joint, as well as the switch 11 (and possibly other switches 11) and the conductor 12 (and possibly other conductors 12). The electrical device 10 can be any switchgear or control device configured to interrupt or switch an electrical current I via at least one switch 11 and / or to conduct an electrical current I via at least one electrical conductor 12. The electrical device 10 can, for example, be configured to interrupt or switch an electrical current I having a voltage in the low voltage range of up to 1 kV, such as in the range of 0.01 kV to 1 kV, or in the medium voltage range, such as in the range of 1 kV to 52 kV.

[0021] Figure 2aAn electrical device 10, such as the switchgear and / or control device described above, is shown, comprising a mechanical mechanism 1, such as a drive and / or actuator, or a connector, such as a pin connector, which may or may not be part of a drive or actuator. The mechanism 1 may, for example, be arranged to operate an electrical switch 11. While the mechanism 1 may be included in an electrical device, it should generally not be electrically conductive. Therefore, the mechanism 1 and any of its components 2 are generally not arranged to conduct an electrical current I. Instead, the current I is conducted by a conductor 12. The mechanism 1 may be actuated by any conventional means, such as spring, magnetic, or pneumatic actuation. The mechanism 1 includes a plurality of components 2 arranged to move relative to one another during operation of the mechanism. The mechanism 1 is typically a metallic mechanism, meaning that at least the substrate 3 of each component 2 is made of a metallic material. For two components 2 arranged to move relative to one another and to contact one another, each component includes 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 the mechanism 1 is provided with an ML coating according to the present disclosure, which is arranged to function as a dry lubricant, thereby reducing or eliminating the need for lubrication of the mechanism 1.

[0022] exist Figure 2a In the embodiment of FIG. 1 , first component 2a has a first contact surface 6a, and second component 2b has a second contact surface 6b, wherein first and second contact surfaces 6a and 6b are arranged to move relative to each other and to contact each other (as indicated by the downward arrows in the figure). First contact surface 6a is provided by an ML coating 4, which is disposed directly on surface 5 of a metal substrate 3 of first component 2a. Thus, coating 4 is disposed on substrate 3, typically on surface 5 of the substrate, such that coating 4 is in direct contact with the metallic material of substrate 3. The metallic material of substrate 3 may, for example, include or be comprised of steel (typically consisting of steel), such as a mild steel such as DCO1, a high-strength steel such as CrMo steel, or a stainless steel such as SS304. Steel can provide the strength and durability required of mechanism 1. In the case where component 2 is in the form of a spring or part of a spring, substrate 3 may be made of spring steel.

[0023] During sliding against the contact surface 6b of the second component 2b, the ML coating 4 may form a tribofilm on the contact surface 6a.The dry solution produces a friction coefficient comparable to the greased solution, for example in the range of 0.15 to 0.25.

[0024] The coating 4 is preferably produced by electrodeposition (also called electroplating), but other coating methods, such as cold spraying and laser sintering or oven sintering, are also possible.

[0025] Figure 2bAn embodiment of an ML coating 4 is shown. 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 μm to 50 μm, preferably 15 μm to 20 μm.

[0026] The GRM content in the composite layer 41 may be in the range of 0.1 wt% to 3 wt% or 2 wt%, preferably in the range of 0.3 wt% to 1.5 wt% or 1 wt%, thus having a concentration that provides self-lubricating properties and improved wear resistance and high temperature resistance, while not substantially changing the mechanical properties of the metal of the matrix 8. Preferably, the composite layer 41 may consist solely of GRM and Me, with the GRM particles 7 dispersed within the Me matrix 8.

[0027] The GRM 7 is preferably present in the form of a few-layer graphene sheets 7 (also referred to herein as graphene nanosheets GnP), preferably with a thickness in the range of 1 nm to 50 nm. The lateral dimension of each GRM sheet 7 (herein, the longest diameter) is several times the thickness, and thus is in the form of a small platelet (also referred to as a flake or plate). In some embodiments, the GRM sheets 7 each have a longest diameter in the range of 5 μm to 80 μm.

[0028] The metallic top layer 42 of the coating 4 is disposed directly on top of the composite layer 41 and protects the metal of the substrate 8 in the composite layer 41 from corrosion, particularly oxidation in the ambient air, but also from other corrosion, such as chemical corrosion (e.g., acid or salt corrosion). The top layer 42 typically consists of a metal, a pure metal, or a metal alloy, plus any metal oxides resulting from oxidation of the metal. The metal of the top layer may preferably be pure nickel or a nickel alloy. One advantage of nickel, particularly when the metal of the substrate 8 is copper, is that the top layer nickel oxidizes instead of the substrate copper, thereby preventing oxidation of the composite layer 41. Thus, the top layer 42 may consist of metallic nickel or a nickel alloy, and may also include nickel oxide if some of the nickel has already oxidized.

[0029] Top layer 42 is preferably much thinner than composite layer 41. Top layer 42 is preferably thin enough to avoid significantly reducing the lubricating effect of composite layer 41 on contact surface 6a. In some embodiments, top layer 42 has an average thickness of at most 1 μm, for example, in the range of 400 nm to 700 nm. Any thickness discussed herein can be measured, for example, by scanning electron microscopy (SEM), such as backscattered electron (BSE) SEM.

[0030] Similarly, the metallic base layer structure 43 of the coating 4 is disposed directly on the surface 5 of the substrate 3 and protects the metal of the substrate (e.g., steel) from corrosion, particularly oxidation in the ambient air, but also from other corrosion, such as chemical corrosion (e.g., acid or salt corrosion). The composite layer 41 is then disposed on top of the base layer structure 43, for example, directly on top of the base layer structure or via an intermediate transition layer or adhesive layer. The base layer structure 43 can be composed of a single base layer or multiple base layers, for example, two or three separate base layers, which are directly superimposed on each other on the surface 5 of the substrate 3. Each base layer of the base layer structure 43 typically consists of a pure metal or a metal alloy plus any metal oxides resulting from oxidation of the pure metal. The metal of the base layer can be pure copper or pure nickel, or an alloy of copper and / or nickel. Preferably, the metal of at least one base layer is pure nickel. One advantage of nickel is that the base layer nickel is oxidized instead of the substrate metal. One advantage of including copper in the base layer can be improved adhesion to the copper substrate 8 of the composite layer 41. The base layer structure 43 may conveniently have an average thickness of at least 1 μm, for example in the range of 5 to 20 μm. The base layer (eg nickel base layer) in the base layer structure 43 may have an average thickness in the range of 3 to 10 μm.

[0031] When the substrate 3 is a low-carbon steel (e.g., DCO1), the base layer structure can conveniently include a copper base layer between the substrate and the nickel base layer. An exemplary base layer structure 43 includes or consists of a (pure) copper base layer and a (pure) nickel base layer, the (pure) copper base layer preferably being directly disposed on the surface 5 of the substrate 3 and having an average thickness in the range of 5 μm to 10 μm, and the (pure) nickel base layer preferably being directly disposed on the copper base layer and having an average thickness in the range of 3 μm to 6 μm (e.g., about 5 μm). On the other hand, for example, when the substrate 3 is made of high-strength steel (CrMo) or stainless steel (e.g., SS304), the use of a copper base layer may not be necessary or may not be convenient at all. Therefore, another exemplary base layer structure 43 includes or consists of a (pure) nickel base layer, and preferably does not have a copper base layer, the (pure) nickel base layer preferably being directly disposed on the surface 5 of the substrate 3 and having an average thickness in the range of 5 μm to 10 μm.

[0032] Figure 3 An electrodeposition structure or bath 30 for electrodepositing the layers of coating 4 is shown.

[0033] For the layers in the base layer structure 43, an exemplary Me electrolyte 33 (typically an aqueous solution) includes Me ions 34 (but without GRM particles 7). The substrate 3 serves as a cathode and is also connected to a voltage source 31 as a corresponding anode 32. The anode 32 can be, for example, a copper (sacrificial) anode or an inert anode of a mixed oxide. By applying a voltage between the substrate 3 and the anode 32 by the voltage source 31, the Me ions 34 are deposited (and reduced) on the surface 5 of the substrate 3 to form a metal base layer 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 grams per liter to 250 grams per liter (g / L). Examples of electrolytes 33 for the base layer include 50 g / L to 300 g / L of CuSO4, 20 ppm to 250 ppm of CuCl2, and 10 g / L to 200 g / L of H2SO4.

[0034] For the composite layer 41, an exemplary Me-GRM electrolyte 33 (typically an aqueous solution) includes GRM particles 7 (typically in the form of GnP) and Me ions 34. The substrate 3 serves as a cathode and is similarly connected to a voltage source 31 as a corresponding anode 32. By applying a voltage between the substrate 3 and the anode 32 by the voltage source 31, the GRM particles 7 and the Me ions 34 are co-deposited on top of the base layer 43, forming the composite layer 41. The Me ions 34 are typically provided by dissolving a metal salt (e.g., 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 grams per liter to 250 grams per liter (g / L). Examples of electrolytes 33 for the composite layer 41 include 50 g / L to 300 g / L of CuSO4, 10 ppm to 400 ppm of CuCl2, 0.01 g / L to 10 g / L of graphene, and 0.01 g / L to 10 g / L of a dispersant. The GRM content in the solution 33 may preferably be in the range of 0.01 g / L to 1.5 g / L.

[0035] Similar to the base layer, for the top layer 42, an exemplary Me electrolyte 33 (typically an aqueous solution) includes Me ions 34 (but without GRM particles 7). The substrate 3 serves as a cathode and is also connected to a voltage source 31 as a corresponding anode 32. By applying a voltage between the substrate 3 and the anode 32 by the voltage source 31, the Me ions 34 are deposited (and reduced) on top of the composite layer 41, forming the metallic top layer 42. Again, the Me ions 34 are typically provided by dissolving a metal salt (e.g., a nickel salt) in the electrolyte 33. In some embodiments, the metal salt content in the solution 33 is in the range of 50 grams per liter to 250 grams per liter (g / L). Examples of electrolytes 33 for the top layer 42 include 50 g / L to 300 g / L of CuSO4, 20 ppm to 250 ppm of CuCl2, and 10 g / L to 200 g / L of H2SO4.

[0036] Figure 4 Some embodiments of a method for coating a metal substrate 3 of a component 2 of a mechanism 1 of an electrical device 10 are shown, for example.

[0037] The method includes: in order to arrange a base layer structure 43 on a substrate 3, providing S1 a metal electrolyte 33 containing metal ions 34 (preferably nickel ions or copper ions), and depositing S2 a base layer of the base layer structure 43 on the surface 5 of the substrate 3 (for example, directly on the surface 5 of the substrate 3) by electrodeposition, thereby depositing (and reducing) the metal ions 34 to form a metal base layer on the substrate surface.

[0038] Subsequently, the method includes: in order to arrange the composite layer 41 on the base layer structure 43, providing S3 a metal-GRM electrolyte 33 containing GRM particles 7 and metal ions 34 (preferably copper ions), and depositing S4 a composite layer 41 on the base layer structure 43 (for example, directly on the base layer structure 41) by electrodeposition, thereby co-depositing the GRM particles 7 and the metal ions 34 to form a metal-GRM composite layer on the base layer structure.

[0039] Subsequently, the method comprises providing S5 a metal electrolyte 33 comprising metal ions 34 (preferably nickel ions) in order to arrange a top layer 42 on top of the composite layer 41, and depositing S6 a top layer 42 on the composite layer 41 (preferably directly on the composite layer 41) by electrodeposition, thereby depositing (and reducing) the metal ions 34 to form a metal top layer on top of the composite layer.

[0040] Figure 5 An example graph of a standard reciprocating pin-on-disc friction and wear test at 3 Newtons (N) is shown, comparing the friction of an ML coating embodiment of the present invention with a standard lubricant solution. It can be seen that the ML coating 4 of the present invention is able to achieve low friction similar to that of conventional lubricants.

[0041] The present disclosure has been described above mainly with reference to several embodiments. However, as will be readily appreciated by those skilled in the art, other embodiments different from the above disclosed embodiments may also be made without departing from the scope of the present disclosure as defined in the appended claims.

Claims

1. A mechanism (1) comprising a plurality of components (2), wherein a first component (2a) comprises a first contact surface (6a), and a second component (2b) comprises a second contact surface (6b), the second contact surface (6b) being arranged to move relative to the first contact surface (6a) and to be in contact with the first contact surface (6a); in, The first contact surface (6a) is provided by a multi-layer coating (4) on a surface (5) of a metal substrate (3) of the first component (2a), wherein the multi-layer coating (4) comprises: a base layer structure (43) arranged on the surface (5) of the substrate (3); a composite layer (41) arranged on top of the base layer structure (43), the composite layer consisting of particles (7) of graphene and related materials (GRM) material in a metal matrix (8); and A metallic top layer (42) is arranged on top of the composite layer (41).

2. The mechanism according to claim 1, wherein: The top layer (42) is made of nickel or a nickel alloy, for example consisting of metallic nickel or a nickel alloy and optionally nickel oxide.

3. A mechanism according to any one of the preceding claims, wherein: The thickness of the top layer (42) is at most 1 μm, for example in the range of 400 nm to 700 nm.

4. A mechanism according to any one of the preceding claims, wherein: The base layer structure (43) comprises or consists of a base layer of nickel or a nickel alloy and / or a base layer of copper or a copper alloy, the base layer of nickel or a nickel alloy for example consisting of metallic nickel and optionally nickel oxide.

5. A mechanism according to any one of the preceding claims, wherein: The thickness of the base layer structure (43) is at least 1 μm, for example in the range of 5 μm to 20 μm.

6. A mechanism according to any one of the preceding claims, wherein: The metal matrix (8) comprises copper.

7. A mechanism according to any one of the preceding claims, wherein: The GRM content in the composite layer (41) is in the range of 0.1 wt% to 3 wt%, preferably 0.3 wt% to 1.5 wt%.

8. A mechanism according to any one of the preceding claims, wherein: The particles (7) are in the form of sheets with a thickness ranging from 0.3 nm to 50 nm, for example graphene nanosheets GnP with a thickness ranging from 5 nm to 50 nm.

9. A mechanism according to any one of the preceding claims, wherein: The thickness of the composite layer (41) is in the range of 10 μm to 50 μm, preferably 15 μm to 20 μm.

10. A mechanism according to any one of the preceding claims, wherein: The substrate (3) is made of steel, such as DC01.

11. A mechanism according to any one of the preceding claims, wherein: The mechanism (1) is an actuator, a drive or a mechanical joint, such as a pin joint, for example for a switchgear or a control device, and the components (2a, 2b) are not arranged to conduct electric current (I).

12. An electrical device (10), comprising: an electrical conductor (12), and A mechanism (1) according to any one of the preceding claims.

13. The electrical device according to claim 12, wherein: The electrical device (10) is a switching device and / or a 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) of a mechanism (1), the method comprising: For the base layer structure (43), providing (S1) a metal electrolyte (33) containing metal ions (34); depositing (S2) at least one layer of the base layer structure (43) on the surface (5) of the substrate (3) by electrodeposition, thereby depositing the metal ions (34) to form a metal base layer on the surface of the substrate; For the composite layer (41), providing (S3) a metal-GRM electrolyte (33) comprising GRM particles (7) and metal ions (34); depositing (S4) the composite layer (41) on the base layer structure (43) by electrodeposition, thereby co-depositing the GRM particles (7) and metal ions (34) to form a metal-GRM composite layer on top of the base layer structure; For the top layer (42), providing (S5) a metal electrolyte (33) containing metal ions (34); as well as The top layer (42) is deposited (S6) on the composite layer (41) by electrodeposition, thereby depositing the metal ions (34) to form a metal top layer on top of the composite layer.

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

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