Composite electric contact material, preparation method and electric contact element

Abstract

The invention relates to the technical field of electric contact materials, and particularly provides a composite electric contact material, a preparation method and an electric contact element. The composite electric contact material comprises a foam metal framework and functional powder, the foam metal framework is of a porous three-dimensional network structure, pores of the foam metal framework are filled with the functional powder, and the functional powder and the foam metal framework form a three-dimensional interpenetrating network structure. The preparation method is used for preparing the composite electric contact material, and the electric contact element comprises the composite electric contact material. The composite electric contact material, the preparation method and the electric contact element provided by the invention have excellent arc erosion resistance and fusion welding resistance while realizing relatively good mechanical strength.

Description

Technical Field

[0001] This disclosure relates to the field of electrical contact materials technology, and in particular to a composite electrical contact material, its preparation method, and an electrical contact element. Background Technology

[0002] Electrical contact elements, as current-carrying components in electrical equipment that enable circuit switching and current transmission, directly affect the switching capacity, electrical life, and reliability of electrical appliances. Traditional electrical contact materials are mainly prepared by powder metallurgy or internal oxidation methods. Their typical structure consists of a conductive silver (or copper) matrix with dispersed reinforcing phase particles (such as Ni, C, SnO2, etc.).

[0003] Under the repeated action of electric arc high temperature, electromagnetic force and mechanical collision, the dispersed reinforcing phase particles of the above-mentioned traditional materials are prone to segregation, shedding or forming diffusion layers at the interface, which leads to the deterioration of the material's conductive path, unstable and increased contact resistance, and intensified material transfer, ultimately causing premature failure of the contacts. Summary of the Invention

[0004] This disclosure is made in view of the above-mentioned problems. This disclosure provides a composite electrical contact material, a method for preparing it, and an electrical contact element that achieves good mechanical strength while exhibiting excellent resistance to arc erosion and weldability.

[0005] According to a first aspect of this disclosure, a composite electrical contact material is provided, comprising: a foamed metal skeleton and functional powder, wherein the foamed metal skeleton is a porous three-dimensional network structure, and the functional powder fills the pores of the foamed metal skeleton and forms a three-dimensional interpenetrating network structure with the foamed metal skeleton.

[0006] According to a second aspect of this disclosure, a method for preparing a composite electrical contact material is provided, comprising: A foam metal skeleton with a porous three-dimensional network structure is provided; Functional powders are mixed with a liquid carrier to form a slurry, and the slurry is filled into the pores of the foam metal skeleton to obtain a preform. The preform is dried to remove the liquid carrier inside the preform; The dried preform is sintered in a protective atmosphere or vacuum environment to form a three-dimensional interpenetrating network structure between the functional powders and between the functional powders and the metal skeleton. The sintered preform is processed to produce the composite electrical contact material.

[0007] According to a third aspect of this disclosure, an electrical contact device is provided, which is made of the composite electrical contact material described in the first aspect.

[0008] In one or more technical solutions provided in this disclosure, firstly, the composite electrical contact material includes a foamed metal skeleton and functional powder. The foamed metal skeleton is a porous three-dimensional network structure, which not only serves as a continuous conductive and mechanical support matrix but also provides uniform and firm adhesion sites for the functional powder. The functional powder, which fills the pores and sintersects with the skeleton to form an interpenetrating structure, is no longer an isolated and dispersed phase but forms an integrated continuous network structure interlocked with the skeleton. Therefore, even under repeated action of high-temperature electric arc, electromagnetic force impact, and mechanical collision, this structure can effectively resist interface separation and particle shedding, significantly improving the structural stability of the material and thus extending the service life of the electrical contact element. Secondly, the continuous foamed metal skeleton provides a stable and efficient conductive path, fundamentally avoiding problems such as interruption of conductive path or unstable contact resistance caused by the segregation of reinforcing phase in traditional materials. At the same time, the functional powder uniformly distributed in the pores of the skeleton, especially the reinforcing components, can effectively absorb arc energy and inhibit fusion welding during the switching process, thereby synergistically improving the material's resistance to arc erosion and fusion welding.

[0009] As can be seen from the above, the composite electrical contact material of this disclosure can effectively reduce the premature failure caused by increased contact resistance and intensified material transfer, significantly improve the switching capability, operational reliability and service life of electrical equipment, and is suitable for various scenarios with stringent requirements for electrical contact performance, such as high and low voltage switches, relays, and contactors, and has broad application value and market prospects.

[0010] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description

[0011] The above and other objects, features, and advantages of this disclosure will become more apparent from the more detailed description of the embodiments thereof in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the disclosure and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0012] Figure 1 This is a flowchart illustrating the preparation process of the composite electrical contact material according to an embodiment of this disclosure; Figure 2 This is a metallographic micrograph of the electrical contact material of Embodiment 1 of this disclosure. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this disclosure more apparent, exemplary embodiments according to this disclosure will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this disclosure, and not all embodiments of this disclosure. It should be understood that this disclosure is not limited to the exemplary embodiments described herein.

[0014] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0015] In the description of this disclosure, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure.

[0016] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this disclosure should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0017] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0018] Those skilled in the art employ sintered metal fiber skeletons or composite electroplating layers to improve the structural stability and functionality of electrical contact elements. However, the fabrication process of metal fiber skeletons is complex and costly, and the connections between fibers are mostly point contacts, resulting in limited overall mechanical strength and the stability of the conductive network. Although composite electroplating technology can form a functional layer on the substrate surface, the adhesion between the plating layer and the substrate is generally weak.

[0019] To address the aforementioned issues, this disclosure provides a composite electrical contact material, its preparation method, and an electrical contact element. A three-dimensional interpenetrating network structure is constructed using a foamed metal skeleton and functional powders filling its pores, achieving good mechanical strength while exhibiting excellent resistance to arc erosion and welding.

[0020] In one feasible embodiment, this disclosure provides a composite electrical contact material comprising a foamed metal skeleton and functional powder, wherein the foamed metal skeleton is a porous three-dimensional network structure, and the functional powder fills the pores of the foamed metal skeleton and forms a three-dimensional interpenetrating network with the foamed metal skeleton.

[0021] The composite electrical contact material of this disclosure includes a foamed metal skeleton and functional powder. The foamed metal skeleton is a porous three-dimensional network structure. This structure not only serves as a continuous conductive and mechanical support matrix, but also provides uniform and firm adhesion sites for the functional powder through the mechanical support of the skeleton itself. The three-dimensional connectivity of the pores allows the functional powder to form a multi-point, all-round tight contact with the skeleton after filling. After sintering, the interfacial bonding strength is improved, thereby solving the problems of easy detachment and agglomeration caused by point contact bonding between particles and the matrix in traditional dispersion-reinforced materials. Even under the high temperature of electric arcs reaching thousands of degrees Celsius and cyclic loading of frequent mechanical impacts, this structure can still maintain structural integrity, significantly improving arc fatigue resistance and extending the service life of electrical contact elements. Secondly, the continuous foamed metal skeleton provides a stable and efficient conductive path, fundamentally avoiding problems such as interruption of conductive path or unstable contact resistance caused by the agglomeration of reinforcing phase in traditional materials. Meanwhile, the functional powders evenly distributed in the skeleton pores, especially the reinforcing components, can effectively absorb arc energy and inhibit the formation of fusion welds during the switching process, thereby synergistically improving the material's resistance to arc erosion and fusion welds.

[0022] In some examples, the material of the aforementioned foam metal skeleton is selected from one or more of silver, copper, nickel, cobalt, iron, and chromium. It should be noted that the selection here is not limited to pure metallic forms, but also includes alloy systems formed by metallurgically bonding any two or more of these elements, such as Ag-Cu alloy foam or Ni-Cr-Fe alloy foam.

[0023] The aforementioned foam metal skeleton materials achieve good conductivity, mechanical strength, and high-temperature stability. Among them, the silver and copper-based skeleton can construct a continuous path with low resistance and high thermal conductivity, ensuring the immediacy and stability of electrical contact. The nickel, cobalt, and iron-based system endows the skeleton with higher structural strength and resistance to deformation, supporting the material to maintain its morphological integrity during frequent switching. The introduction of chromium significantly improves oxidation resistance and arc erosion resistance. This material system not only provides a stable and reliable supporting matrix for three-dimensional interpenetrating networks but also achieves a wide range of electrical contact materials from highly conductive to highly corrosion-resistant, thus broadly adapting to diverse application scenarios ranging from precision signal relays to high-load circuit breakers.

[0024] In some examples, the aforementioned functional powder includes conductive components and reinforcing components. The conductive components include one or more of Ag, Cu, and Au, and the reinforcing components include one or more of W, WC, Mo, Ni, C, ZrB2, TiC, SnO2, CuO, ZnO, and In2O3.

[0025] It should be noted that the aforementioned reinforcing components can be single substances or composites of multiple substances, and their selection depends on the specific application requirements for resistance to arc erosion, weldability, wear resistance, and thermal stability. For example, in applications requiring high resistance to arc erosion and high hardness, W, WC, Mo, or ZrB2 are preferred. When good weldability and environmental friendliness are desired, SnO2, CuO, ZnO, and In2O3 are preferred. When improving the material's self-lubricating properties and current-carrying stability is required, components such as C (graphite) or Ni can be introduced.

[0026] In some examples, the mass ratio of the conductive component to the reinforcing component is (60~98):(2~40). Preferably, the mass ratio of the conductive component to the reinforcing component is (70~95):(5~35), and more preferably, the mass ratio of the conductive component to the reinforcing component is (75~95):(5~30). The specific ratio can be adjusted according to the application scenario of the electrical contact element, such as current level, switching frequency, and arc resistance requirements. Within this mass ratio range, the proportion of the conductive component is not less than 60%, ensuring that even when the reinforcing phase content is high, the material can still form a continuous or near-continuous conductive network, avoiding a sharp increase in contact resistance caused by excessive reinforcing phase blocking the current path. Within this proportion range, the reinforcing component can achieve uniform distribution and strong interfacial bonding through the three-dimensional interpenetrating network structure, and can also avoid excessive slurry viscosity, filling difficulties, or microcracks caused by excessive differences in expansion coefficients during sintering due to excessive addition. Therefore, the conductive components form an efficient and stable current-carrying channel, while the uniformly distributed reinforcing components act as a strengthening phase to effectively suppress arc erosion and material transfer. Together, they ensure the long-term reliable service of the material under high electrical loads and mechanical stresses.

[0027] In some alternative approaches, the porosity of the aforementioned foamed metal skeleton is 80%–98%. Controlling the porosity of the foamed metal skeleton within this range ensures, on the one hand, that the skeleton itself maintains sufficient metallic ligament continuity, providing the necessary mechanical support strength and a stable three-dimensional conductive network for the material. On the other hand, the high-porosity structure provides ample space and uniformly distributed filling sites for the functional powder, allowing the functional powder to fully fill and form a large-area, tightly bonded interface with the metal skeleton. After sintering, the interpenetrating network structure formed between the high-porosity metal skeleton and the functional powder exhibits extremely high interfacial bonding strength and structural stability. This effectively suppresses the shedding and agglomeration of the functional phase under arc impact, and also efficiently absorbs and dissipates arc energy through the functional phase in the pores. Thus, the material synergistically achieves excellent resistance to arc erosion, weldability, and mechanical durability while maintaining high conductivity.

[0028] In some examples, at least one surface of the aforementioned composite electrical contact material is further laminated with a silver-based material layer, which accounts for 5% to 15% of the total thickness of the composite electrical contact material. It should be understood that the silver-based material layer can be made of silver or a silver alloy, such as pure silver, a silver-copper alloy, or a silver-nickel alloy. This silver-based material layer can serve as a functional transition layer, forming a good metallurgical bond with the internal three-dimensional interpenetrating network structure, while providing an optimized contact interface for external connections. Its high conductivity and excellent plastic deformation capability can effectively reduce contact resistance and improve electrical contact stability.

[0029] In some examples, the mass ratio of the functional powder to the foamed metal skeleton is 1:0.5 to 1:5. The specific ratio can be calculated and adjusted based on the porosity of the foamed metal skeleton, the theoretical density of the functional powder, and the target composition of the final composite material. Preferably, the mass ratio of the functional powder to the foamed metal skeleton is 1:1 to 1:3 to ensure that the functional powder can fully fill the pores of the skeleton while avoiding slurry overflow or composition deviation caused by overfilling.

[0030] This disclosure also provides a method for preparing a composite electrical contact material, which can be used to prepare the composite electrical contact material of the present invention. Figure 1 A flowchart illustrating the preparation process of the composite electrical contact material according to an embodiment of this disclosure is shown, as follows: Figure 1 As shown, the method for preparing the composite electrical contact material according to an embodiment of this disclosure includes: Step 101: Provide a foam metal skeleton with a porous three-dimensional network structure.

[0031] For example, depending on the final product form and performance requirements, a porous three-dimensional network structure of foam metal skeleton with a porosity of 80% to 98%, suitable pore size distribution, and material composition (such as foam Ag, foam Cu, foam Ni, or their alloys) is selected. For sheet or strip products, sheet-shaped foam metal can be used, while for riveted products, cylindrical foam metal can be used. This structure not only serves as a continuous conductive and mechanical support matrix but also provides uniform and firm adhesion sites for functional powders.

[0032] Step 102: Mix the functional powder with the liquid carrier to form a slurry, and fill the slurry into the pores of the foam metal skeleton to obtain a preform.

[0033] It should be noted that the liquid carrier mentioned above can be selected from one or more of organic solvents, water, or polymer solutions. Specifically, the organic solvent can be selected from one or more of ethanol, isopropanol, acetone, or toluene; the water can be deionized water; and the polymer solution can be selected from polyvinyl alcohol or polyethylene glycol.

[0034] For example, the above-mentioned method of mixing functional powder with liquid carrier to form a slurry and filling the slurry into the pores of the foam metal skeleton to obtain a preform includes: First, cutting the foam metal skeleton (such as foam silver, foam copper, or foam nickel) to a preset size and placing it in a mold to ensure that the skeleton maintains structural stability and accurate shape during subsequent filling. Then, mixing the functional powder with liquid carrier and dispersing it in a ball mill or high-speed mixer to form a slurry. Subsequently, the prepared slurry is injected into the mold and filled using slurrying or scraping methods at a vacuum degree ≤0.1MPa, vibration frequency 20Hz~100Hz, or centrifugal speed 500rpm~2000rpm, so that the slurry covers the foam metal skeleton and ensures that the slurry fully penetrates and completely fills all the interconnected pores of the skeleton. Finally, the filled mold is left to stand at room temperature for preliminary defoaming and leveling to obtain a preform with a complete structure.

[0035] The above-mentioned use of slurry filling supplemented by physical aids such as vibration, vacuum or centrifugation can ensure that functional powders can fill complex three-dimensional pores without dead corners and with high homogeneity, which greatly improves the uniformity of functional powder distribution and overcomes the problems of agglomeration and bridging that are easy to occur in traditional dry filling. Thus, a uniform, dense, and firmly bonded interpenetrating network structure can be obtained.

[0036] It should be understood that the above molds are graphite molds, stainless steel molds, or high-temperature resistant polymer molds.

[0037] Specifically, the above-mentioned method of mixing functional powder with liquid carrier to form a slurry and filling the slurry into the pores of the foam metal skeleton includes: placing conductive components and reinforcing components in a mixer and mixing them under an inert atmosphere to obtain a uniformly mixed powder.

[0038] In some examples, the functional powders (especially reinforcing components) may be surface-treated as needed, such as by coating the surface with silane coupling agents, titanate coupling agents, etc., to improve the dispersibility of the functional powders in the liquid carrier and their interfacial compatibility with the metal skeleton.

[0039] Step 103: Dry the preform to remove the liquid carrier inside the preform.

[0040] For example, the filled preform can be placed in an oven or vacuum drying equipment and dried at a suitable temperature (e.g., 60°C to 120°C) for several hours to remove the liquid carrier within the preform, forming a green body with a certain strength. This disclosure, through a vacuum drying process, completely removes the liquid carrier while avoiding cracking or deformation of the green body caused by drying stress concentration, ensuring the structural integrity and compositional stability of the green body before high-temperature sintering.

[0041] Step 104: Sinter the dried preform in a protective atmosphere or vacuum environment to form a sintered preform with a three-dimensional interpenetrating network structure between functional powders and between functional powders and metal skeleton.

[0042] For example, the dried green body can be placed in a sintering furnace and heated to a sintering temperature of 700°C to 950°C at a heating rate of 5°C / min to 10°C / min under a protective atmosphere such as hydrogen or argon, or under vacuum conditions, and held at that temperature for 1 hour to 4 hours. This achieves metallurgical bonding between functional powder particles and interfacial diffusion connection between functional powder and the framework. Sintering under a protective atmosphere or vacuum effectively inhibits the oxidation of metals and functional powders, promotes atomic diffusion and metallurgical bonding between powder particles and between powder and the framework, transforming the originally physically filled composite structure into an integrated interpenetrating network with strong interfacial bonding, significantly improving the overall strength, conductivity, and high-temperature stability of the material.

[0043] Step 105: Process the sintered blank to produce a composite electrical contact material.

[0044] For example, the above-mentioned processing of sintered blanks to produce composite electrical contact materials specifically includes: pressing, rolling or extruding the sintered blanks to obtain composite electrical contact materials.

[0045] In some examples, when pressing the sintered preform, it can be punched into small blocks and then repressed under a pressure of 600 MPa to 1400 MPa to obtain a composite electrical contact material. It should be understood that the repressing can be performed on a hydraulic press or a mechanical press, and lubricants (such as zinc stearate) or release agents can be used during the pressing process to ensure a smooth product surface and reduce mold wear.

[0046] In some examples, when rolling a sintered billet, the billet is hot-rolled at 300°C to 600°C to obtain a strip, which is then stamped to obtain a composite electrical contact material. Specifically, when rolling a sintered billet, the billet is hot-rolled multiple times at 300°C to 600°C, with a total deformation of 40% to 80%, to obtain a dense strip, which is then stamped to obtain a composite electrical contact material.

[0047] In some examples, when extruding sintered blanks, the blanks are heated to 500℃~850℃ and hot-extruded to form sheets or wires, resulting in composite electrical contact materials. Sheet extrusion specifically involves loading a cylindrical sintered blank into an extrusion cylinder, preheating it, and then extruding it through a flat-hole die to form a sheet. Wire extrusion specifically involves extruding the blank into wires with a diameter of 2mm~10mm through a round-hole die. The wires are then drawn multiple times to the target diameter (e.g., 0.5mm~2mm), and then cold-headed, cut, or forged to form riveted electrical contact elements.

[0048] The above three processing paths can be flexibly selected according to the product shape, performance requirements and production scale. All of them can maintain the integrity of the three-dimensional interpenetrating network structure while further densifying the material, thereby producing composite electrical contact materials with different shapes and excellent performance.

[0049] In one feasible manner, after filling the pores of a metal skeleton with slurry to obtain a preform and before drying the preform, the preparation method further includes: laying a silver-based material on at least one surface of the preform to form a silver-based material layer.

[0050] Specifically, silver powder or silver alloy powder can be mixed with organic solvents (such as ethanol and acetone) and an appropriate amount of binder to prepare a uniform silver-based slurry with a solid content of 60% to 80%. The slurry is applied to the surface of the preform by scraping, screen printing or spraying. By controlling the coating thickness, the thickness of the dried silver-based material layer accounts for 5% to 15% of the total thickness of the preform. This allows the silver-based material layer to form a strong metallurgical bond with the foam metal skeleton filled with functional powder during subsequent drying and co-sintering. As a result, a surface functional layer with low contact resistance, excellent weldability and good resistance to arc impact is constructed on the surface of the final composite material, achieving synergistic optimization of the material's surface properties and bulk structure.

[0051] In one feasible embodiment, after drying the preform and before sintering in a protective atmosphere or vacuum environment, the preparation method further includes: subjecting the dried preform to cold isostatic pressing. Specifically, the dried preform is sealed in a flexible sleeve and placed in the chamber of a cold isostatic press. It is then held at a liquid medium pressure of 100 MPa to 300 MPa for 1 to 10 minutes. This isotropic pressure further densifies the powder particles within the preform, reduces porosity, and enhances interfacial contact, thereby increasing the preform's density and strength, improving compositional uniformity, and providing a structurally stable preform with reduced defects for subsequent sintering and possible plastic processing such as extrusion and forging. This ensures the final acquisition of a highly dense, high-performance composite electrical contact material.

[0052] This disclosure also discloses an electrical contact element made of the composite electrical contact material of this disclosure, which includes a high-voltage switch, a relay, a circuit breaker, or a contactor.

[0053] In summary, the composite electrical contact material, preparation method, and electrical contact element of this disclosure solve the problems of easy detachment of the reinforcing phase and unstable conductive path in traditional dispersion-reinforced materials by filling the pores of the foam metal skeleton with functional powder and forming a three-dimensional interpenetrating network structure with the foam metal skeleton. The final electrical contact element has the characteristics of high strength arc resistance of solid phase and low surface resistance solderability, which significantly improves the reliability and service life of electrical equipment under frequent switching, high load and harsh environment.

[0054] To verify the effectiveness of the composite electrical contact material provided in the embodiments of the present invention, the embodiments of the present invention are demonstrated by comparing the embodiments with comparative examples.

[0055] Example 1 This embodiment uses a pressing method to prepare AgNiC sheet-like electrical contact material, including the following steps: The first step is to provide a foam metal skeleton: take a piece of foam Ni with a porosity of 90% and a thickness of 3mm, cut it into 100mm×100mm size, and lay it flat in the graphite mold.

[0056] The second step is to prepare the preform: Mix 960g of Ag powder (particle size about 5μm) and 40g of C powder (particle size about 1μm) with 500ml of anhydrous ethanol, and wet grind in a planetary ball mill for 6 hours to form a uniform slurry. Pour the slurry into the mold and place it on a vibrating table to vibrate for 2 minutes to ensure complete filling.

[0057] The third step is to form a silver-based material layer: pure Ag powder is mixed with anhydrous ethanol to make a silver-based slurry, which is then uniformly covered on the surface of the blank. The thickness of the pure Ag layer after drying is controlled to be about 0.30 mm.

[0058] Step 4: Remove the liquid carrier: Transfer the mold to an 80℃ vacuum oven and dry for 8 hours.

[0059] The fifth step is to prepare the sintered green body: After demolding, the green body is transferred into a sintering furnace with hydrogen gas, heated to 850°C at 5°C / min, held for 4 hours, and then cooled with the furnace.

[0060] Step 6: Preparation of composite electrical contact material: The sintered blank is cut into small pieces of 10mm×8mm using a mold, and then re-pressed under a pressure of 1000MPa to obtain the final dense sheet-like electrical contact material. Figure 2 Metallographic micrographs of the electrical contact material of Embodiment 1 of this disclosure are shown. Tests showed that the material of Embodiment 1 has a density of 98.5% of the theoretical density, a conductivity of 63% IACS, and an electrical life of over 15,000 cycles when tested in a circuit breaker with a rated current of 125A and a rated voltage of AC415V.

[0061] Example 2 The first step is to provide a foam metal skeleton: take a piece of foam silver with a porosity of 92% and a thickness of 2.5mm, cut it into a size of 100mm×100mm, and lay it flat in a graphite mold.

[0062] The second step is to prepare the preform: Mix 850g of Ag powder (particle size about 5μm), 120g of WC powder (particle size about 3μm) and 30g of C powder (particle size about 1μm) with 500ml of anhydrous ethanol, wet grind in a planetary ball mill for 6 hours to form a uniform slurry, pour the slurry into the mold, place it on a vibrating table and vibrate for 1 minute to ensure complete filling.

[0063] The third step is to form a silver-based material layer: pure Ag powder is mixed with anhydrous ethanol to make a silver-based slurry, which is then evenly applied to the upper surface of the blank. The thickness of the pure Ag layer after drying is controlled to be approximately 0.25 mm.

[0064] Step 4: Remove the liquid carrier: Transfer the mold to an 80℃ vacuum oven and dry for 8 hours.

[0065] The fifth step is to prepare the sintered green body: After demolding, the green body is transferred into a sintering furnace with hydrogen gas, heated to 880°C at 5°C / min, held for 4 hours, and then cooled with the furnace.

[0066] Step 6: Preparation of composite electrical contact material: The sintered blank is punched into 6mm×6mm pieces using a mold, and then re-pressed under 1200MPa pressure to obtain the final dense sheet-like electrical contact material. Testing showed that the material density reached 98.5% of the theoretical density, the conductivity was 65% IACS, and the electrical life exceeded 20,000 cycles when tested in a circuit breaker with a rated current of 125A and a rated voltage of AC415V.

[0067] Example 3 This embodiment three uses a rolling method to prepare AgNiC sheet-like electrical contact material, including the following steps: The first step is to provide a foam metal skeleton: take a piece of foam nickel with a porosity of 88% and a thickness of 10mm, cut it into a size of 1000mm×100mm, and lay it flat in the mold.

[0068] The second step is to prepare the preform: mix 7700g of Ag powder, 2000g of Ni powder and 300g of C powder with 5000ml of anhydrous ethanol, and wet grind for 4 hours to form a uniform slurry; pour the slurry into the mold, vibrate to ensure full filling, and then dry.

[0069] The third step is to form a silver-based material layer: a layer of pure Ag powder slurry is laid on the surface of the blank, and the thickness of the Ag layer formed after drying is about 1 mm.

[0070] The fourth step is to prepare the sintered green body: sinter at 850°C for 3 hours in a hydrogen atmosphere.

[0071] The fifth step is rolling: the sintered billet is hot rolled at 450°C. After multiple rolling passes, the total deformation reaches 80%, resulting in a dense strip with a thickness of 2mm.

[0072] Step 6: Preparation of composite electrical contact material: The strip is punched into 60mm×10mm sheet contacts. Testing shows that the resulting material has a density of 99.5% of the theoretical density, a conductivity of 60% IACS, and an electrical life of over 23,000 cycles when tested in a circuit breaker with a rated current of 125A and a rated voltage of AC415V. It exhibits uniform structure and good consistency in longitudinal and transverse properties, making it suitable for automated production lines.

[0073] Example 4 This fourth embodiment uses an extrusion method to prepare AgSnO2 rivet-type electrical contact material, including the following steps: The first step is to provide a foam metal skeleton: take a cylindrical foam silver with a porosity of 90% and a diameter of 90mm and put it into a rubber sleeve.

[0074] The second step is to prepare the preform: 8800g of Ag powder and 1200g of SnO2 powder are mixed with 4000ml of anhydrous ethanol to make a slurry, which is then poured into and filled into the pores of the foamed silver, and then dried.

[0075] The third step is cold isostatic pressing: the dried billet is subjected to cold isostatic pressing at 200 MPa.

[0076] The fourth step is to prepare the sintered green body: sinter at 780°C for 2.5 hours in an air atmosphere.

[0077] Step 5, extrusion and forming: The sintered billet is heated to 750°C and hot-extruded into a rod with a diameter of 8mm through a die; then the rod is drawn in multiple passes to finally obtain a wire with a diameter of 2mm.

[0078] Step 6: Preparation of composite electrical contact material: The wire is cold-forged into a standard rivet-type electrical contact element. Testing showed that the rivet-type electrical contact element prepared in Example 4 has a material density of 99.8% of the theoretical density, a conductivity of 86% IACS, and an electrical performance simulation test conducted with a rated current of 25A, a rated voltage of DC14V, and a 1-second on / off cycle. The electrical life can reach over 100,000 cycles.

[0079] Comparative Example 1 Comparative Example 1 uses conventional powder metallurgy to prepare AgNiC material. Ag powder, Ni powder, and C powder of the same specifications are directly mixed, pressed into shape at 600 MPa, and then sintered under the same conditions as in Example 1 (hydrogen atmosphere, 850℃ / 4h) to obtain the electrical contact material. Testing showed that the material density of Comparative Example 1 reached 98.5% of the theoretical density, the conductivity was 56% IACS, and the electrical life was 8,000 cycles.

[0080] Comparative Example 2 Comparative Example 2 uses a simple mixing and sintering process without forming a three-dimensional interpenetrating network to prepare the composite material. Ag powder and C powder of the same mass and particle size are directly physically mixed with small pieces of nickel foam, and then pressed and sintered under the same pressure and temperature conditions as in Example 1 to obtain the electrical contact material. Testing showed that the composite material of Comparative Example 2 has a density of only 93.5% of the theoretical density, a conductivity of 45% IACS, and an electrical life of 5,000 cycles.

[0081] Comparative Example 3 Comparative Example 3 uses a low-porosity foam metal skeleton to prepare a composite electrical contact material. A 50% porosity nickel foam skeleton was used, and the material dimensions, functional powder formulation (Ag powder and C powder), subsequent slurry filling, surface silver layer laying, drying, sintering, and pressing process parameters were all the same as in Example 1. Testing showed that the material density of Comparative Example 3 reached 96.0% of the theoretical density, the conductivity was 54% IACS, and the electrical life was 11,000 cycles.

[0082] As can be seen from the above embodiments and comparative examples, compared with traditional powder metallurgy processes (Comparative Example 1) and simple hybrid structures (Comparative Example 2), the three-dimensional interpenetrating network structure formed by the foamed metal skeleton and functional powders in this disclosure (Examples 1 to 4) exhibits significant advantages in comprehensive performance such as conductivity and arc life, proving that this structure can effectively stabilize conductive pathways, enhance interfacial bonding, and inhibit functional phase shedding. Comparative Example 3, which uses low-porosity (50%) foamed nickel, results in insufficient functional phase filling. Although the strength is high, the conductivity and arc life are significantly lower than those of the embodiments using high-porosity (80%~98%) skeletons, verifying the necessity of setting the porosity range in this invention.

[0083] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0084] The block diagrams of devices, apparatuses, devices, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0085] Additionally, as used herein, the "or" used in a list of items beginning with "at least one" indicates a separate list, such that a list of, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not imply that the described example is preferred or better than other examples.

[0086] It should also be noted that in the systems and methods of this disclosure, the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions to this disclosure.

[0087] Various changes, substitutions, and modifications can be made to the technology described herein without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, events, means, methods, and actions described above. Currently existing or later-developed processes, machines, manufactures, events, means, methods, or actions that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Therefore, the appended claims include such processes, machines, manufactures, events, means, methods, or actions within their scope.

[0088] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0089] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A composite electrical contact material, characterized by, The composite electric contact material comprises: a foamed metal skeleton having a porous three-dimensional network structure, and functional powders filled in pores of the foamed metal skeleton and forming a three-dimensional interpenetrating network structure with the foamed metal skeleton.

2. The composite electrical contact material of claim 1, wherein The foamed metal skeleton is made of one or more of silver, copper, nickel, cobalt, iron and chromium.

3. The composite electrical contact material of claim 1, wherein, The functional powders comprise conductive components and reinforcing components, the conductive components comprising one or more of Ag, Cu and Au; The reinforcing components comprising one or more of W, WC, Mo, Ni, C, ZrB2, TiC, SnO2, CuO, ZnO and In2O3.

4. The composite electrical contact material of claim 1, wherein The foamed metal skeleton has a porosity of 80% to 98%.

5. The composite electrical contact material of any of claims 1-4, wherein the silver- based alloy comprises silver, copper, and at least one of cobalt, nickel, and iron. The composite electric contact material further comprises a silver-based material layer on at least one surface of the composite electric contact material, the silver-based material layer accounting for 5% to 15% of the total thickness of the composite electric contact material.

6. A method of producing the composite electrical contact material according to any one of claims 1 to 5, characterized by, The method comprises: providing a foamed metal skeleton having a porous three-dimensional network structure; mixing functional powders with a liquid carrier to form a slurry, and filling the slurry into pores of the foamed metal skeleton to obtain a preform; drying the preform to remove the liquid carrier in the preform; sintering the dried preform in a protective atmosphere or a vacuum environment to form a sintered preform having a three-dimensional interpenetrating network structure between the functional powders and between the functional powders and the metal skeleton; processing the sintered preform to obtain the composite electric contact material.

7. The method of claim 6, wherein the step of mixing is performed at a temperature of 20°C to 100°C. The processing of the sintered preform to obtain the composite electric contact material comprises: pressing, rolling or extruding the sintered preform to obtain the composite electric contact material; wherein the pressing comprises: punching the sintered preform into small pieces, and then re-pressing under a pressure of 600 MPa to 1400 MPa to obtain the composite electric contact material; the rolling comprises: hot rolling the sintered preform at 300°C to 600°C to obtain a strip, and then punching the strip into a desired shape to obtain the composite electric contact material; the extruding comprises: heating the sintered preform to 500°C to 850°C and then hot extruding to obtain the composite electric contact material.

8. The method of claim 6, wherein the composite electrical contact material is prepared by a process comprising: After the filling of the slurry into the pores of the foamed metal skeleton to obtain the preform, before the drying of the preform, the method further comprises: laying a silver-based material on at least one surface of the preform to form a silver-based material layer.

9. The method of claim 6, wherein the composite electrical contact material is prepared by a process comprising: After the drying of the preform, before the sintering of the dried preform in a protective atmosphere or a vacuum environment, the method further comprises: cold isostatic pressing the dried preform.

10. An electrical contact element, characterized by The electric contact element is made of the composite electric contact material according to any one of claims 1 to 5.

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