A gallium-based liquid metal electrocontact composite material with high conductivity and low abrasion and its preparation method

Abstract

The present invention relates to a high-conductivity and low-abrasion gallium-based liquid metal electrical contact composite material and a preparation method thereof. The electrical contact composite material of the present invention comprises a conductive ceramic as a matrix material and a gallium-based liquid metal as a conductive additive phase, and optionally further comprises a conductive lubricating phase. The electrical contact composite material of the present invention achieves both high conductivity and low wear performance, improves the ultimate current-carrying density of the electrical contact material, and is of great significance for improving the performance of electrical contact devices.

Description

Technical Field

[0001] The present invention belongs to the field of electrical contact composite materials, and relates to an electrical contact composite material and a preparation method thereof. Specifically, the present invention relates to a conductive ceramic-based composite material having both high conductivity and wear resistance, using gallium-based liquid metal as a conductive additive phase to increase the actual current-carrying area of ​​the interface, and a preparation method thereof. Background Art

[0002] Current-carrying friction refers to the friction generated between interfaces in relative motion while current is being transmitted. It is widely used in high-end equipment in the fields of aerospace, advanced weapons, transportation, new energy, etc., including conductive rings in spacecraft and floating wind turbines, electromagnetic railgun armatures / rails, electric locomotive pantographs / contact networks, etc. The above application fields urgently need to solve the problem of high conductivity and low wear of key moving pairs under extremely harsh working conditions (high current / high vacuum, etc.), which is difficult to meet with the existing current-carrying friction system. For example, the contact resistivity of metal-based materials is as low as ~10 -12 Ωm 2 , but the wear rate is as high as ~10 -3 mm 3 N -1 m -1 ; Other new materials such as diamond-like carbon-based coatings and conductive two-dimensional materials can have wear rates as low as ~10 -7 mm 3 N -1 m -1 , but the contact resistivity is as high as ~10 -10 Ωm 2 The interface current density of the macroscopic current-carrying friction system is generally <300MA / m 2 .

[0003] Although metal materials with good electrical conductivity and anti-friction and anti-wear materials can be combined together through material composites to regulate the electrical conductivity and wear resistance of the materials, it is still difficult to develop electrical contact materials with both high conductivity and low wear properties.

[0004] In addition, when the current-carrying friction interface carries a large current, the interface will also undergo severe wear and deterioration due to factors such as Joule temperature rise and arc erosion, resulting in further degradation of interface performance. This greatly restricts the improvement of the life and reliability of future high-power equipment.

[0005] Existing current-carrying friction materials focus on improving the conductivity or wear resistance of the material itself, but pay insufficient attention to the physical and chemical state of the material's current-carrying friction interface. They all require sacrificing one aspect of the material's mechanical / electrical properties in exchange for an improvement in another aspect of the performance, and are unable to fundamentally solve the problem of balancing conductivity and wear resistance.

[0006] Microscopically, the surface of the electrical contact material consists of many rough peaks, and the actual contact area only accounts for a very small part of the macroscopic contact area, which introduces a relatively high contact resistance at the contact interface. Moreover, during the current-carrying friction process, changes in the interface contact state will also cause problems such as separation of rough peaks and arc ablation, resulting in fluctuations in contact resistance and even current transmission failure. Limited by the deterioration of the interface state under high current-carrying conditions, the ultimate current-carrying density of the electrical contact material cannot be further increased, and these problems cannot be solved by the existing technologies. Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The purpose of the present invention is to provide an electrical contact composite material and a preparation method thereof that can solve the problem that it has been difficult to balance high electrical conductivity and low wear performance of electrical contact materials.

[0009] Solutions for solving the problems

[0010] In the electrical contact composite material of the present invention, a gallium-based liquid metal is used as a conductive additive phase to fill the gaps between the rough peaks of the current-carrying friction interface, so as to greatly increase the actual current-carrying area. And this material uses a conductive ceramic with good wear resistance as the matrix, thereby solving the above technical problems.

[0011] Specifically, the present invention provides an electrical contact composite material, which comprises: 85% to 98% by mass of a matrix material; and 1% to 5% by mass of a conductive additive phase, wherein the matrix material is a conductive ceramic and the conductive additive phase is a gallium-based liquid metal.

[0012] According to the electrical contact composite material of the present invention, the conductive ceramic is selected from at least one of tungsten carbide, titanium carbide, titanium nitride, and titanium aluminum carbide.

[0013] According to the electrical contact composite material of the present invention, the gallium-based liquid metal is selected from at least one of pure metal gallium, gallium indium alloy, gallium indium tin alloy, and gallium indium tin zinc alloy.

[0014] According to the electrical contact composite material of the present invention, the gallium-based liquid metal is a gallium indium alloy, and the mass ratio of gallium to indium is Ga:In = 70:30 to 80:20.

[0015] According to the electrical contact composite material of the present invention, the electrical contact composite material further comprises 1% to 10% by mass of a conductive lubricating phase, and the conductive lubricating phase is selected from at least one of graphite, niobium diselenide, and nickel ditelluride.

[0016] According to the electrical contact composite material of the present invention, its wear rate is 1×10 -6 mm 3 N-1 m -1 Hereinafter, the contact resistivity is 1×10 -11 Ωm 2 Hereinafter, the interfacial current density is 500 MA / m 2 or more.

[0017] For the electro - contact composite material according to the present invention, its wear rate is 1×10 -6 mm 3 N -1 m -1 Hereinafter, the contact resistivity is 6×10 -11 Ωm 2 Hereinafter, the interfacial current density is 500 MA / m 2 or more.

[0018] The present invention also provides a preparation method of the electro - contact composite material according to the present invention, and the preparation method includes the following steps:

[0019] (1) Mixing: Mixing the conductive ceramic powder and the gallium - based liquid metal raw material to obtain a composite powder;

[0020] (2) Hot - press sintering: Placing the composite powder obtained in step (1) in a mold for hot - press sintering, and obtaining a sintered blank after cooling;

[0021] (3) Grinding and polishing: Grinding and polishing the sintered blank obtained in step (2) to obtain the electro - contact composite material.

[0022] According to the preparation method of the present invention, a conductive lubricating phase powder is further added in step (1).

[0023] According to the preparation method of the present invention, the atmosphere of the hot - press sintering is an argon atmosphere, the sintering pressure of the hot - press sintering is 40 - 200 MPa, the sintering temperature is 1000 - 1800 °C, the heat - preservation time is 10 - 30 min, and the particle size of the conductive ceramic powder is 50 - 400 nm.

[0024] Effects of the invention

[0025] The technical solution of the present invention has the following beneficial effects:

[0026] The electro - contact composite material of the present invention achieves both high conductivity and low wear performance, improves the ultimate current - carrying density of the electro - contact material, and is of great significance for improving the performance of electro - contact devices; the present invention first proposes a material design for improving the current - carrying friction performance of electro - contact materials by compounding gallium - based liquid metal into electro - contact materials and increasing the actual current - carrying area at the interface through the small amount of precipitation of liquid metal during the current - carrying friction process, as well as a preparation method for related materials. Brief Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the current-carrying friction interface of the electro-contact composite material of the present invention.

[0028] Figure 2 It is a scanning electron microscope (SEM) image of the surface of electro-contact composite material-I.

[0029] Figure 3 It is a curve of the change of the friction coefficient and contact resistance during the current-carrying friction test of electro-contact composite material-I. Detailed implementation manners

[0030] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The special term "exemplary" used here means "serving as an example, embodiment or illustration". Any embodiment described as "exemplary" here does not have to be construed as superior to or better than other embodiments.

[0031] In addition, in order to better illustrate the present invention, numerous specific details are given in the following detailed implementation manners. Those skilled in the art should understand that the present invention can also be implemented without some specific details. In other instances, methods, means, equipment and steps well-known to those skilled in the art are not described in detail in order to highlight the gist of the present invention.

[0032] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values and numerical ranges appearing in the present invention should be understood as including the inevitable systematic errors in industrial production.

[0033] In this specification, the meaning expressed by using "can" includes the meanings of both performing a certain process and not performing a certain process.

[0034] In this specification, the so-called "some specific / preferred implementation manners", "other specific / preferred implementation manners", "implementation manners", etc. refer to the specific elements (for example, features, structures, properties and / or characteristics) related to the implementation manner described herein, which are included in at least one of the implementation manners described herein, and may or may not exist in other implementation manners. In addition, it should be understood that the elements can be combined in various implementation manners in any suitable manner.

[0035] In this specification, the numerical range expressed by using "numerical value A~numerical value B" refers to the range including the endpoint numerical values A and B.

[0036] In this specification, the meaning of "room temperature" is "20~40°C".

[0037] Electric contact composite material

[0038] The present invention provides an electric contact composite material including a conductive ceramic as a matrix material and a gallium-based liquid metal as a conductive additive phase. This electric contact composite material has both high conductivity and wear resistance, and will not undergo arc ablation and severe wear during high-current operation.

[0039] During the current-carrying friction process of the electric contact composite material of the present invention, as the matrix material wears, a small amount of gallium-based liquid metal precipitates and fills the gaps between the rough peaks in the worn groove area, thereby greatly increasing the actual current-carrying area of the interface, reducing the contact resistance and its fluctuations, and alleviating the problem of aggravated material wear caused by Joule heat temperature rise.

[0040] Gallium-based liquid metal will react with most metal materials such as copper and silver to form intermetallic compounds or dissolve with each other, and the high-temperature environment during hot press sintering will exacerbate this process, which makes it difficult to compound gallium-based liquid metal into the interior of the metal matrix. Therefore, the present invention uses a conductive ceramic that does not react or dissolve with gallium-based liquid metal as the matrix, and at the same time, by using a high-strength ceramic material, the obtained composite material has excellent wear resistance.

[0041] In some preferred embodiments, the electric contact composite material of the present invention further includes a conductive lubricating phase. The conductive lubricating phase can reduce the friction coefficient of the current-carrying friction interface and further reduce the wear rate of the material.

[0042] Figure 1 It is a schematic diagram of the mechanism where gallium-based liquid metal at the current-carrying friction interface fills the gaps between the rough peaks in the worn groove area to increase the actual current-carrying area and the conductive lubricating phase plays a lubricating role. During the friction process, the gallium-based liquid metal inside the composite material is slowly and slightly released at the interface and fills the gaps between the rough peaks in the worn groove area to promote the formation of conformal contact, greatly increasing the actual current-carrying area; the conductive lubricating phase forms a heterogeneous weak shear slip plane to reduce friction.

[0043] Hereinafter, the electric contact composite material of the present invention will be described in detail.

[0044] Matrix material

[0045] The electric contact composite material of the present invention includes a matrix material, and the matrix material is a conductive ceramic with good wear resistance.

[0046] The conductive ceramic has high strength, so that the finally obtained electric contact composite material has excellent wear resistance. The conductive ceramic can be at least one selected from tungsten carbide, titanium carbide, titanium nitride, and titanium aluminum carbide. In some embodiments, the conductive ceramic is preferably tungsten carbide, which has high hardness, wear resistance, and high melting point, and can effectively improve the wear and arc ablation problems during the current-carrying friction process of the electric contact material.

[0047] Due to the high hardness and low deformation ability of tungsten carbide materials, the surface rough peaks are prone to separation during the current-carrying friction process, resulting in large fluctuations in the dynamic contact resistance. Therefore, tungsten carbide is rarely used as the matrix of electrical contact materials in the prior art. In the present invention, tungsten carbide is preferably used as the matrix material and gallium-based liquid metal is added as the conductive additive phase. The good deformation ability of gallium-based liquid metal is utilized to fill the gaps of the rough peaks at the tungsten carbide interface, which can effectively increase the actual current-carrying area of the interface and the ultimate current-carrying density of tungsten carbide materials, achieving both good electrical conductivity and wear resistance of the electrical contact composite material.

[0048] In some embodiments, the content of the matrix material in the electrical contact composite material is 85% to 98% by mass, for example, it can be 88% by mass, 91% by mass, 94% by mass.

[0049] Conductive additive phase

[0050] The electrical contact composite material of the present invention contains a conductive additive phase, and the conductive additive phase is gallium-based liquid metal. Gallium-based liquid metal is a type of metal material with a melting point at or below room temperature, and has characteristics such as low toxicity, high fluidity, and low saturated vapor pressure.

[0051] Gallium-based liquid metal does not react or dissolve with conductive ceramics. Therefore, in the electrical contact composite material of the present invention, the gallium-based liquid metal as the conductive additive phase is stored in the conductive ceramic as the matrix material. During the current-carrying friction process, according to the interface state, the gallium-based liquid metal can precipitate adaptively and fill the gaps of the rough peaks at the current-carrying friction interface, thereby greatly increasing the actual current-carrying area at the interface, avoiding problems such as arc ablation and increased wear caused by the separation of rough peaks, reducing the fluctuation of the contact resistance during the current-carrying friction process, and thus prolonging the reliable service life of the electrical contact composite material.

[0052] In some embodiments, the gallium-based liquid metal is preferably selected from at least one of pure metal gallium, gallium-indium alloy, gallium-indium-tin alloy, and gallium-indium-tin-zinc alloy, more preferably gallium-indium alloy, in which the mass ratio of gallium to indium is Ga:In = 70:30 to 80:20, for example, 72:28, 74.5:25.5, 75.5:24.5, 78:22, and further more preferably eutectic gallium-indium alloy, in which the mass ratio of gallium to indium is Ga:In = 75.5:24.5.

[0053] In some embodiments, the content of the conductive additive phase in the electrical contact composite material is 1% to 5% by mass, for example, it can be 2% by mass, 3% by mass, 4% by mass.

[0054] Conductive lubricating phase

[0055] The electro - contact composite material of the present invention may further comprise a conductive lubricating phase. The conductive lubricating phase can reduce the friction coefficient of the current - carrying friction interface at the low - shear interface formed at the electro - contact interface and further reduce the wear rate of the material, alleviating the problem of the increase in contact resistance caused by wear. The conductive lubricating phase can be at least one selected from graphite, niobium diselenide, and nickel ditelluride.

[0056] In some embodiments, the conductive lubricating phase is preferably graphite.

[0057] In some embodiments, the content of the conductive lubricating phase in the electro - contact composite material is 1% to 10% by mass, for example, it can be 4% by mass or 7% by mass.

[0058] The hardness of the electro - contact composite material of the present invention is above 800 HV, and the material wear rate during use is 1×10 -6 mm 3 N -1 m -1 Hereinafter, the contact resistivity is 6×10 -11 Ωm 2 Hereinafter, for example, it is 1×10 -11 Ωm 2 Hereinafter, the interfacial current - carrying density is 500 MA / m 2 Above. The above results show that the electro - contact composite material of the present invention can achieve both high conductivity and low wear performance.

[0059] The test method for hardness is as follows: Use a Vickers hardness tester for testing. The test force is 0.3 kgf, the holding time is 15 s, and measure at least at 3 different positions and take the average value as the final hardness value.

[0060] The test methods for material wear rate and contact resistivity are as follows: The electro - contact composite material of the present invention uses a tungsten carbide ball as the counter - grinding pair and conducts current - carrying friction testing in a vacuum environment. The test parameters are: the temperature is 27 °C, the vacuum degree is <1×10 -3 Pa, the motion mode is continuous rotation, the load is 1.5 N, the current is 2 A, and the rotation speed is 24 rpm.

[0061] Preparation method of electric contact composite material

[0062] The present invention also provides a preparation method of an electro - contact composite material, which comprises the following steps:

[0063] (1) Mixing: Mix the conductive ceramic powder and the gallium - based liquid metal raw material to obtain a composite powder;

[0064] (2) Hot - press sintering: Place the composite powder obtained in step (1) in a mold for hot - press sintering, and obtain a sintered blank after cooling;

[0065] (3) Grinding and polishing: The sintered blank obtained in step (2) is ground and polished to obtain an electro - contact composite material.

[0066] The following is a detailed description of each step.

[0067] (1) Mixing materials

[0068] In this step, according to the proportion of each component in the finished product, the required mass of conductive ceramic powder and gallium - based liquid metal raw material are mixed evenly by mechanical stirring to prepare a composite powder to be hot - pressed and sintered. In this step, the conductive ceramic powder can separate the droplets of the gallium - based liquid metal raw material, making it evenly dispersed in the mixing system.

[0069] In some embodiments, the conductive ceramic powder is preferably tungsten carbide powder. In some embodiments, the particle size of the conductive ceramic powder is preferably 50 - 400 nm, such as 60 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm. The nano - scale powder can reduce the temperature required for sintering, reduce the vaporization of the liquid metal during the sintering process, and avoid defects such as pores formed inside the material.

[0070] In some embodiments, the gallium - based liquid metal raw material is preferably selected from at least one of pure metal gallium, gallium - indium alloy, gallium - indium - tin alloy, and gallium - indium - tin - zinc alloy. In some embodiments, the gallium - based liquid metal raw material is more preferably a gallium - indium alloy, in which the mass ratio of gallium to indium is Ga:In = 70:30 - 80:20, such as 72:28, 74.5:25.5, 75.5:24.5, 78:22. In some embodiments, the gallium - based liquid metal is further more preferably a eutectic gallium - indium alloy, in which the mass ratio of gallium to indium is Ga:In = 75.5:24.5, and the melting point of this alloy is 15.7 °C, which is convenient for the mixing step at room temperature.

[0071] In some embodiments, a conductive lubricating phase powder is further added in the mixing step, thereby further reducing the friction coefficient and wear rate of the composite material. In some embodiments, the conductive lubricating phase powder is preferably graphite powder. In some embodiments, the particle size of the conductive lubricating phase powder is preferably 1 - 10 μm, such as 1.6 μm, 2 μm, 4 μm, 6 μm, 8 μm.

[0072] (2) Hot press sintering

[0073] In this step, the composite powder obtained in step (1) is placed in a mold for hot - pressing sintering and heat preservation, and a sintered blank is obtained after cooling;

[0074] In some embodiments, the atmosphere for hot-press sintering is an inert gas atmosphere, preferably an argon atmosphere. Using an argon atmosphere can reduce the vaporization of the gallium-based liquid metal raw material during high-temperature sintering, and at the same time play a protective role to avoid the oxidation problem of the gallium-based liquid metal.

[0075] In some embodiments, the sintering pressure is preferably 40 - 200 MPa, the sintering temperature is preferably 1000 - 1800 °C, and the heat preservation time for sintering is preferably 10 - 30 min.

[0076] In some embodiments, the cooling process is preferably furnace cooling.

[0077] (3) Grinding and polishing

[0078] The sintered compact obtained in step (2) is ground and polished to obtain an electrical contact composite material.

[0079] In some embodiments, in the grinding and polishing step, it is preferable to use a polishing machine, sandpaper, polishing cloth, and polishing liquid to grind and polish the sintered compact.

[0080] In some embodiments, after the grinding and polishing step, the surface roughness of the sintered compact can be reduced to below Ra 0.2 μm and the defects on the surface layer of the sintered compact can be removed.

[0081] The electrical contact composite material prepared by the present invention has very low contact resistivity and wear rate in a vacuum environment. A small amount of gallium-based liquid metal is released at the contact interface during the current-carrying friction process, effectively filling the gaps between the rough peaks in the wear scar area, and greatly improving the electrical contact performance of the system. Examples

[0082] The following will describe the embodiments of the present invention in detail in conjunction with examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase. The test methods not described in detail in the examples are all conventional test methods in the art.

[0083] Example 1

[0084] Prepare the electrical contact composite material-I of Preparation Example 1 below, and the equipment such as the mixer and hot press furnace used are those well-known to those skilled in the art.

[0085] (1)Mixing: In the prepared electro - contact composite material, tungsten carbide is 95% by mass, and the balance is eutectic gallium - indium alloy. The mass ratio of gallium to indium in this alloy is Ga:In = 75.5:24.5. Weigh the required tungsten carbide and gallium - indium alloy raw materials according to the above ratio and add them to a mixer. The particle size of the selected tungsten carbide powder is 50 nm. In the mixer, the tungsten carbide powder and gallium - indium alloy are mixed evenly by mechanical stirring until the mixed system is in a powder state and there are no aggregated eutectic gallium - indium alloy droplets macroscopically, so as to facilitate subsequent hot - pressing sintering. The tungsten carbide powder can effectively separate the gallium - indium alloy droplets, making the mixed system in a solid powder state.

[0086] (2)Hot - pressing sintering: Select a hot - pressing die of appropriate size according to the finished product size, and weigh the mixed powder prepared in the above step according to the finished product mass. Add the mixed powder into the die and put it into a hot - pressing furnace. Sinter and keep it warm for 15 min under an argon atmosphere, a sintering pressure of 50 MPa and a sintering temperature of 1400 °C. After sintering, cool the die and the sample in it to below 40 °C with the furnace and then take them out.

[0087] (3)Use a polishing machine, sandpaper, polishing cloth and polishing fluid to polish the surface of the sample, reduce the surface roughness of the sintered blank to below Ra 0.2 μm and remove the defects on the surface layer of the sintered blank. The obtained sample is denoted as electro - contact composite material - I.

[0088] Example 2

[0089] Prepare electro - contact composite material - II according to the method of Example 1, except that: in the prepared electro - contact composite material, tungsten carbide is 85% by mass, graphite is 10% by mass, and the balance is eutectic gallium - indium alloy. The particle size of the selected graphite powder is 1.6 μm during preparation. The obtained sample is denoted as electro - contact composite material - II.

[0090] Performance test

[0091] SEM and energy spectrum analysis (EDS)

[0092] For SEM testing, the instrument model is Gemini 300, ZEISS (Germany); the acceleration voltage is 3 kV; the testing method is to stick the electro - contact composite material sample to the conductive adhesive on the sample stage and take pictures of the sample morphology.

[0093] For EDS testing, the instrument model is XPLORE30, OXFORD (UK); the acceleration voltage is 15 kV; the testing method is to stick the electro - contact composite material sample to the conductive adhesive on the sample stage and perform energy - spectrum testing to measure the elemental composition and relative content of the sample.

[0094] The SEM image of the surface of electro - contact composite material - I is asFigure 2 As shown in the figure. Among them, tungsten carbide (WC) is the matrix material, and eutectic gallium-indium alloy (EGaIn) is used as the conductive additive phase and is dispersed in the micropores of the tungsten carbide matrix.

[0095] The microstructure and elemental composition of the wear scar were characterized by SEM and EDS techniques. It was found that the contents of gallium and indium elements inside the wear scar were significantly higher than those outside the wear scar, indicating that during the current-carrying friction process, the gallium-based liquid metal effectively filled the gaps between the asperities in the wear scar region, and only a small amount of it precipitated in the wear scar region.

[0096] Friction and conductivity performance test

[0097] A tungsten carbide (grade YG6) ball with a diameter of 8 mm was used as the current-carrying friction pair to test the current-carrying friction performance of the prepared electrical contact composite material-I and electrical contact composite material-II. The test parameters were a vacuum degree <1×10 -3 Pa, the movement mode was continuous rotation, the load was 1.5 N, the current was 2 A, and the rotation speed was 24 rpm.

[0098] Figure 3 It is the curve of the friction coefficient and contact resistance changing with time during the current-carrying friction test of the electrical contact composite material-I. Combining the data of the contact resistance changing with time, it can be seen that after adding the gallium-based liquid metal, the actual current-carrying area of the interface has been greatly improved, effectively reducing the contact resistance of the composite material and alleviating the aggravating effect of Joule heat temperature rise on wear.

[0099] Material wear rate and contact resistivity

[0100] After the friction and conductivity performance test, the samples were taken out of the vacuum chamber. The three-dimensional topography of the wear scars on the surfaces of the electrical contact composite material-I and the electrical contact composite material-II was measured by a white light interferometer and the wear rate was calculated. At the same time, the width of the wear scar was determined to calculate the magnitude of the contact resistivity.

[0101] Regarding the measurement of the three-dimensional topography of the wear scars on the surface of the composite material by a white light interferometer, the model of the instrument used was NexView, ZYGO Corporation (USA); the vertical resolution was 0.1 nm, and the relevant test method was to place the electrical contact composite material sample on the instrument sample stage and level it, and measure the three-dimensional topography near the wear scar area on the sample surface to obtain the wear volume.

[0102] The calculation method of the contact resistivity is: contact resistance × π × (width of the wear scar) 2 / 4.

[0103] The calculation method of the interface current density is: current / (π × (width of the wear scar) 2 / 4)

[0104] The test results are as follows: the wear rate of the electrical contact composite material-I is 7×10 -7 mm 3 N -1 m -1 , the contact resistivity is 9×10 -12 Ωm 2 , the average friction coefficient is 0.28, and the interface current-carrying density is 520 MA / m 2 ; the wear rate of the electrical contact composite material-II is 5×10 -7 mm 3 N -1 m -1 , the contact resistivity is 6×10 -11 Ωm 2 , the average friction coefficient is 0.22, and the interface current-carrying density is 707 MA / m 2 .

[0105] It should be noted that although the technical solutions of the present invention are introduced by specific examples, those skilled in the art can understand that the present invention should not be limited thereto.

[0106] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, the practical application, or the improvement of the technology in the market, or to enable other ordinary skilled in the art of this technology to understand the disclosed embodiments.

Claims

1. An electrical contact composite material, characterized in that: The electrical contact composite material comprises: 85% to 98% by mass of a matrix material; and 2% to 5% by mass of conductive additive phase, Wherein, the matrix material is a conductive ceramic, and the conductive ceramic is selected from at least one of tungsten carbide, titanium carbide, titanium nitride and titanium aluminum carbide. The conductive additive phase is gallium-based liquid metal, The gallium-based liquid metal is selected from at least one of pure metallic gallium, gallium-indium alloy, gallium-indium-tin alloy and gallium-indium-tin-zinc alloy.

2. The electrical contact composite material according to claim 1, characterized in that: The gallium-based liquid metal is a gallium-indium alloy, wherein the mass ratio of gallium to indium is Ga:In=70:30-80:

20.

3. The electrical contact composite material according to claim 1 or 2, characterized in that: The electrical contact composite material further comprises 1 mass % to 10 mass % of a conductive lubricating phase, wherein the conductive lubricating phase is at least one selected from graphite, niobium diselenide and nickel ditelluride.

4. The electrical contact composite material according to claim 1 or 2, characterized in that: The wear rate of the electrical contact composite material is 1×10 -6 mm 3 N -1 m -1 Below, the contact resistance is 1×10 -11 Ωm 2 Below, the interface current density is 500MA / m 2 above.

5. The electrical contact composite material according to claim 3, characterized in that: The wear rate of the electrical contact composite material is 1×10 -6 mm 3 N -1 m -1 Below, the contact resistance is 6×10 -11 Ωm 2 Below, the interface current density is 500MA / m 2 above.

6. A method for preparing the electrical contact composite material according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Mixing: mixing the conductive ceramic powder and the gallium-based liquid metal raw material to obtain a composite powder; (2) hot pressing and sintering: placing the composite powder obtained in step (1) in a mold for hot pressing and sintering, and obtaining a sintered blank after cooling; (3) Grinding and polishing: Grinding and polishing the sintered blank obtained in step (2) to obtain the electrical contact composite material.

7. The method for preparing the electrical contact composite material according to claim 6, characterized in that: In the step (1), conductive lubricating phase powder is further added.

8. The method for preparing the electrical contact composite material according to claim 6 or 7, characterized in that: The atmosphere of the hot pressing sintering is an argon atmosphere, the sintering pressure of the hot pressing sintering is 40-200 MPa, the sintering temperature is 1000-1800° C., the holding time is 10-30 min, and the particle size of the conductive ceramic powder is 50-400 nm.

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