A tungsten-coated copper antioxidant material and its preparation method

Abstract

This invention discloses a tungsten-coated copper antioxidant material and its preparation method, relating to the field of coating materials technology. The preparation method of the tungsten-coated copper antioxidant material disclosed in this invention includes the following steps: S1, washing and first drying copper powder to obtain clean copper powder; S2, mixing tungsten salt, surfactant, clean copper powder, and water, and stirring to obtain a mixture; S3, filtering and second drying the mixture to obtain copper powder with tungsten salt adsorbed on its surface; S4, calcining the copper powder with tungsten salt adsorbed on its surface under a reducing atmosphere to obtain the tungsten-coated copper antioxidant material. The tungsten-coated copper antioxidant material prepared by the above method has good antioxidant properties and electrical conductivity, and is suitable for application in multiple fields.

Description

Technical Field

[0001] This invention relates to the field of coating materials technology, and more specifically, to a tungsten-coated copper antioxidant material and its preparation method. Background Technology

[0002] Copper powder possesses excellent electrical and thermal conductivity, making it widely used in catalysts, metal coatings, and other fields. It is a key raw material for advanced circuit integration in high-density printed circuit boards (PCBs) and also plays an important role in high-performance lubricating greases for low-speed, heavy-duty bearings and gears in wind power and metallurgical industries. However, copper powder is prone to oxidation in air. This oxidation problem severely affects the performance of copper powder in products. For example, in the field of conductive pastes, the high conductivity of the product depends on the conductive network formed after the copper powder is sintered; if the copper powder oxidizes, an effective sintering neck cannot be formed at the same temperature, resulting in a significant decrease in conductivity.

[0003] Generally, a dense passivation layer is coated onto the surface of copper powder to prevent direct contact between the copper powder and oxygen. This passivation layer can be an organic layer; for example, CN114453578B discloses a method for modifying copper powder, utilizing the coordination of 2-mercaptobenzothiazole or methylbenzyltriazole with copper to form a hydrophobic and dense coating layer, improving the oxidation and corrosion resistance of the copper powder. The passivation layer can also be an inorganic material; for example, CN117548669A discloses a method for preparing silver-coated copper powder, which obtains silver-coated copper powder with excellent conductivity and oxidation resistance by coating the surface of copper powder with a dense silver layer.

[0004] While the above methods can improve the oxidation resistance of copper powder at room temperature, organic coating cannot improve the oxidation resistance of copper powder at high temperature. Silver coating of copper is costly. In addition, most existing coating methods have complex processes, which are not conducive to large-scale application. Summary of the Invention

[0005] The main objective of this invention is to provide a tungsten-coated copper antioxidant material and its preparation method, so as to solve the problems of poor high-temperature antioxidant properties of copper powder, high preparation cost of antioxidant copper powder, and complex preparation process in the prior art.

[0006] To achieve the above objectives, according to a first aspect of the present invention, a method for preparing a tungsten-coated copper antioxidant material is provided, comprising the following steps:

[0007] S1, the copper powder is cleaned and first dried to obtain clean copper powder;

[0008] S2, mix tungsten salt, surfactant, cleaning copper powder and water, stir to obtain a mixture;

[0009] S3, the mixture is filtered and then dried to obtain copper powder with tungsten salt adsorbed on its surface;

[0010] S4. Copper powder with tungsten salt adsorbed on its surface is calcined under a reducing atmosphere to obtain tungsten-coated copper antioxidant material.

[0011] Further, in S1, the copper powder is cleaned sequentially using an alkaline solution, an acidic solution, and water. The alkaline solution is at least one of sodium hydroxide solution, potassium hydroxide solution, and ammonia water; the acidic solution is at least one of sulfuric acid solution, hydrochloric acid, and nitric acid solution.

[0012] Furthermore, in S1, the temperature for cleaning with alkaline solution is 60℃~80℃, and the time is 0.5h~2h.

[0013] Furthermore, in S1, ultrasonic assistance is used when cleaning with acid solution, and the cleaning time with acid solution is 3 min to 10 min.

[0014] Further, in S1, the solution is washed with water until neutral.

[0015] Furthermore, in S1, the temperature of the first drying is 25℃~80℃, and the drying time is 2h~5h.

[0016] Further, in S2, tungsten salt is first dissolved in water to obtain a tungsten salt solution, then clean copper powder is added to the tungsten salt solution to form a dispersion; then a surfactant is added to the dispersion and stirred to obtain a mixture.

[0017] Furthermore, in S2, the mass ratio of tungsten salt to clean copper powder is 1:100 to 1:10.

[0018] Furthermore, in S2, the mass ratio of surfactant to cleaning copper powder is 1:50 to 1:5.

[0019] Furthermore, in S2, the concentration of tungsten salt in the tungsten salt solution is 1 mM to 10 mM.

[0020] Furthermore, in S2, the stirring time is 0.5h to 3h.

[0021] Furthermore, in S2, the tungsten salt is at least one of ammonium metatungstate, sodium tungstate, phosphotungstic acid, and ammonium paratungstate.

[0022] Furthermore, in S2, the surfactant is at least one of mercaptoethylamine, 3-(trimethoxysilyl)propylamine (APTMS), and cysteine.

[0023] Furthermore, in S3, the temperature for the second drying is 25℃~60℃, and the drying time is 1h~5h.

[0024] Furthermore, in S4, the calcination temperature is 300℃~500℃, and the calcination time is 1h~3h.

[0025] Furthermore, in S4, the reducing atmosphere is a mixture of hydrogen and an inert gas; the inert gas is at least one of nitrogen, argon, and helium.

[0026] According to a second aspect of the present invention, a tungsten-coated copper antioxidant material is provided, wherein the tungsten-coated copper antioxidant material is prepared by the preparation method of the first aspect of the present invention.

[0027] By applying the technical solution of this invention, contaminants on the surface of copper powder can be removed by cleaning, thus improving the uniformity of coating. In addition, by mixing tungsten salt, surfactant and clean copper powder, copper powder with tungstate adsorbed uniformly on the surface can be formed. Finally, by reducing and calcining in a reducing atmosphere, tungsten-coated copper antioxidant material with good oxidation resistance and conductivity can be obtained. Its oxidation resistance at high temperature is also significantly higher than that of uncoated copper powder. The preparation process is simple, low-cost and easy to industrialize, and can be applied in the fields of electronics, aerospace, high-temperature alloys and other fields. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the preparation method of tungsten-coated copper antioxidant material in this embodiment of the invention;

[0029] Figure 2 The images shown are scanning electron microscope (SEM) images and EDX spectra of the tungsten-coated copper antioxidant material in Example 1 of this invention.

[0030] Figure 3 The images shown are scanning electron microscope (SEM) images and EDX spectra of the tungsten-coated copper antioxidant material in Example 2 of this invention.

[0031] Figure 4 Here is a scanning electron microscope image of the copper powder in Comparative Example 1;

[0032] Figure 5 The images are scanning electron microscope (SEM) images of the tungsten-coated copper antioxidant materials in (a) Example 1, (b) Example 2 and (c) Comparative Example 2 after aging at 85°C for 10 hours. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0034] As described in the background section of this invention, existing technologies suffer from poor oxidation resistance of copper powder. Even after coating, the high-temperature oxidation resistance of copper powder remains poor, and the coating cost is relatively high and the process is complex. To address these technical problems, in a typical embodiment of this invention, a method for preparing tungsten-coated copper anti-oxidation material is provided, the process flow chart of which is shown below. Figure 1 As shown, it includes the following steps:

[0035] S1, the copper powder is cleaned and first dried to obtain clean copper powder;

[0036] S2, mix tungsten salt, surfactant, cleaning copper powder and water, stir to obtain a mixture;

[0037] S3, the mixture is filtered and then dried to obtain copper powder with tungsten salt adsorbed on its surface;

[0038] S4. Copper powder with tungsten salt adsorbed on its surface is calcined under a reducing atmosphere to obtain tungsten-coated copper antioxidant material.

[0039] In step S1, cleaning the copper powder removes organic matter, oxides, and other contaminants from its surface, facilitating the formation of copper powder with a uniformly adsorbed tungstate layer. This is beneficial for preparing tungsten-coated copper antioxidant materials with good antioxidant properties. In step S2, water is used as the solvent, avoiding the environmental pollution problems that may arise from the use of organic solvents in traditional coating processes. Furthermore, the processes of mixing, stirring, filtering, and drying using tungsten salts and surfactants in steps S2 and S3 are relatively simple, easy to industrialize, and do not require complex secondary coating, thus reducing production costs. In step S4, calcining the copper powder with adsorbed tungstate in a reducing atmosphere forms a tungsten-coated copper antioxidant material with a uniformly tungsten coating. The tungsten coating layer has good stability and a stronger bond with the copper powder, effectively isolating the copper powder from air and improving the high-temperature antioxidant properties of the copper powder.

[0040] In some embodiments, in step S1, the copper powder is cleaned sequentially using an alkaline solution, an acidic solution, and water. The alkaline solution is at least one of sodium hydroxide solution, potassium hydroxide solution, and ammonia water; the acidic solution is at least one of sulfuric acid solution, hydrochloric acid, and nitric acid solution. After cleaning with the alkaline and acidic solutions, the powder is then rinsed with water until neutral.

[0041] Cleaning with alkaline solutions, such as sodium hydroxide, potassium hydroxide, or ammonia, can effectively remove organic residues or oil from the surface of copper powder. These organic substances may originate from the production or storage process of the copper powder. Cleaning allows tungsten salts to be uniformly adsorbed on the copper powder surface, promoting the formation of a tungsten coating. Cleaning with acidic solutions, such as sulfuric acid, hydrochloric acid, or nitric acid, can remove the copper oxide layer formed on the surface of the copper powder and promote the adsorption of tungstates on the copper powder surface. Acid washing ensures the cleanliness of the copper powder surface, providing a good substrate for tungsten coating. After sequential cleaning with alkaline and acidic solutions, the number of active sites on the copper powder surface increases, which is beneficial to the subsequent adsorption and coating process of tungsten salts, resulting in a more uniform and dense tungsten coating. Cleaning with water to neutrality can maintain the good chemical stability of the copper powder and improve reaction efficiency. The tungsten-coated copper antioxidant material formed after cleaning using the above methods has good electrical and thermal conductivity, and its resistivity increases slowly during the aging process.

[0042] In some embodiments, the concentration of alkali in the alkaline solution is 2M to 5M, which is sufficient to remove organic contaminants from the surface of copper powder without damaging the copper powder itself.

[0043] In some embodiments, the concentration of acid in the acid solution is 1 wt% to 10 wt%, which is within the range that oxides on the surface of copper powder can be removed without damaging the copper powder itself.

[0044] In some embodiments, in step S1, the temperature for cleaning with the alkaline solution is 60°C to 80°C, and the time is 0.5 h to 2 h. Cleaning under these conditions can accelerate the reaction rate and enhance the cleaning effect.

[0045] In some embodiments, during S1, ultrasonic assistance is used when cleaning with acid solution, and the cleaning time is 3 to 10 minutes. Compared with traditional soaking, ultrasonic assistance can achieve the cleaning effect in a shorter time, reducing time costs.

[0046] In some embodiments, in step S1, the temperature for the first drying is 25°C to 80°C, and the drying time is 2 hours to 5 hours. Under these conditions, drying can be carried out quickly without causing the copper powder to age, resulting in good drying effect.

[0047] Typically, and not limitingly, the copper powder has a D50 particle size of 0.1 μm to 40 μm and is spherical or irregular in shape.

[0048] The copper powder mentioned above has a good adsorption effect on tungsten salt under the action of surfactant, which is conducive to the formation of a uniform tungsten coating layer.

[0049] In some embodiments, in step S2, tungsten salt is first dissolved in water to obtain a tungsten salt solution, and then clean copper powder is added to the tungsten salt solution to form a dispersion; then a surfactant is added to the dispersion and stirred to obtain a mixture.

[0050] Dissolving the tungsten salt first ensures complete dispersion in water, forming a homogeneous tungsten salt solution. Adding clean copper powder to this solution further improves the dispersion of the components. Introducing a surfactant into the dispersion helps the tungsten salt adsorb evenly onto the copper powder surface, enhancing chemical reaction efficiency, increasing the adsorption rate of tungsten salt on the copper powder surface, reducing coating defects, and ultimately improving the antioxidant properties of tungsten-coated copper antioxidant materials.

[0051] In some embodiments, in S2, the mass ratio of tungsten salt to clean copper powder is 1:100 to 1:10.

[0052] By limiting the mass ratio of tungsten salt and clean copper powder as described above, a uniform and continuous tungsten coating layer can be formed, which helps to improve the oxidation resistance of the tungsten-coated copper anti-oxidation material. The copper-coated tungsten anti-oxidation material also has good electrical conductivity.

[0053] In some embodiments, in S2, the mass ratio of surfactant to cleaning copper powder is 1:50 to 1:5.

[0054] Surfactants can improve the wettability and dispersibility of copper powder, ensuring good suspension of copper powder in solution. In addition, surfactants can lower the energy barrier of copper powder surface. The active groups in surfactants can electrostatically adsorb tungstate ions in tungstate salts, promoting the adsorption of tungstate salts on the copper powder surface. An appropriate surfactant-to-copper powder mass ratio can significantly improve the adsorption efficiency of tungstate salts on the copper powder surface, forming a dense coating layer, thereby enhancing the antioxidant properties of the material.

[0055] In some embodiments, in S2, the concentration of tungsten salt in the tungsten salt solution is 1 mM to 10 mM.

[0056] By setting the tungsten salt concentration appropriately, a stable and uniform tungsten salt solution can be prepared, ensuring that the tungsten salt can uniformly cover the copper powder surface during subsequent coating processes. Furthermore, a suitable concentration can improve coating efficiency.

[0057] Limiting the mass fraction of surfactants can improve the wettability and dispersibility of copper powder, and enhance the uniformity and density of the coating layer.

[0058] In some embodiments, the stirring time in step S2 is 0.5 h to 3 h. Under these conditions, tungsten salt can be uniformly adsorbed onto the surface of copper powder, which is beneficial for forming a tungsten-coated copper antioxidant material with good antioxidant properties.

[0059] In some embodiments, in S2, the tungsten salt is at least one of ammonium metatungstate, sodium tungstate, phosphotungstic acid, and ammonium paratungstate; the surfactant is at least one of mercaptoethylamine, 3-(trimethoxysilyl)propylamine, and cysteine.

[0060] Ammonium metatungstate, sodium tungstate, phosphotungstic acid, and ammonium paratungstate all possess excellent water solubility, enabling them to disperse rapidly in aqueous solutions and form a homogeneous and stable solution. This facilitates a uniform coating reaction with the copper powder surface, and their high reactivity ensures rapid formation of the tungsten coating layer, improving production efficiency. Surfactants such as mercaptoethylamine, APTMS, and cysteine ​​have surface tension-reducing properties, significantly improving the wettability of copper powder in tungsten salt solutions. This ensures the coating reaction proceeds uniformly on the copper powder surface, forming a dense coating layer. Furthermore, they help reduce the sensitivity of the tungsten-coated copper antioxidant to oxygen, enhancing the protective performance of the coating layer without affecting the conductivity of the copper powder.

[0061] In some embodiments, in S3, the temperature of the second drying is 25°C to 60°C, and the time of the second drying is 1 hour to 5 hours.

[0062] Drying under the above conditions can significantly accelerate solvent evaporation and shorten the overall drying time. This is particularly important for improving production efficiency and realizing industrial production. Furthermore, drying under these conditions maintains the stable adsorption of tungstate on the copper powder surface, preserving the stability and density of the coating layer.

[0063] In some embodiments, in step S4, the calcination temperature is 300°C to 500°C, and the calcination time is 1 hour to 5 hours.

[0064] Calcination of copper powder with tungstate adsorbed on its surface will cause further chemical reactions, forming a denser and more stable tungsten-coated copper antioxidant material. Under the above calcination conditions, the tungsten-coated copper antioxidant material also has good electrical conductivity. In addition to ensuring coating quality, it can also improve production efficiency and reduce energy consumption.

[0065] In some embodiments, in S4, the reducing atmosphere is a mixture of hydrogen and an inert gas; the inert gas is at least one of nitrogen, argon, and helium.

[0066] Hydrogen, as a reducing agent, can reduce tungsten oxide and tungstate to metallic tungsten at high temperatures, forming a coating layer with better conductivity. This process not only improves the oxidation resistance of the coating layer but also gives it good conductivity and corrosion resistance. In addition, in the mixed gas, inert gases (such as nitrogen, argon, and helium) can provide an air-isolated environment, effectively preventing copper powder from oxidizing due to contact with oxygen during high-temperature processing. This helps maintain the original properties of the copper powder and ensures the performance of the final product.

[0067] In some embodiments, in S4, the volume ratio of hydrogen to inert gas in the reducing atmosphere is 1:99 to 5:95.

[0068] Controlling the volume ratio of hydrogen and inert gas within the above range is to ensure that tungsten oxide or tungstate can be reduced to tungsten, and also to ensure the safety of the operation process.

[0069] In another typical embodiment of the present invention, a tungsten-coated copper antioxidant material is also provided, which is prepared by the preparation method described in the above embodiments of the present invention. This tungsten-coated copper antioxidant material has good antioxidant properties and electrical conductivity, and exhibits good antioxidant properties at high temperatures, making it suitable for a wide range of applications.

[0070] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0071] Example 1

[0072] One embodiment of the tungsten-coated copper antioxidant material of the present invention is described below:

[0073] S1. Take 5g of copper powder (D50 particle size of 40μm), add it to 50mL of sodium hydroxide aqueous solution with a concentration of 2.5M, and stir at 75℃ for 1h; after filtration, disperse it in 50mL of sulfuric acid aqueous solution with a concentration of 5wt% H2SO4, and sonicate for 3min; after filtration, wash the copper powder with water until neutral, and dry it in a vacuum drying oven at 25℃ for 3h to obtain 5g of clean copper powder;

[0074] S2, ammonium metatungstate is added to water to form 15 mL of ammonium metatungstate solution with a concentration of 10 mM (ammonium metatungstate mass is 0.446 g), and then the above-mentioned cleaned copper powder is added to the ammonium metatungstate solution to obtain a dispersion; then 0.5 mL of 99% APTMS solution (APTMS mass is 0.51 g) is added dropwise to the dispersion, and the mixture is stirred for 1 h to obtain a mixture;

[0075] S3, the mixture is filtered and then placed in a vacuum drying oven and dried at 25°C for 3 hours to obtain copper powder with tungsten salt adsorbed on the surface;

[0076] S4. Copper powder with tungstate adsorbed on its surface is placed in a tube furnace and calcined under the condition of hydrogen and argon volume ratio of 5:95. The temperature is increased to 300℃ at a rate of 2℃ / min and held for 3h to obtain tungsten-coated copper antioxidant material.

[0077] Example 2

[0078] One embodiment of the tungsten-coated copper antioxidant material of the present invention is described below:

[0079] S1. Take 5g of copper powder (D50 particle size is 0.4μm), add it to 50mL of sodium hydroxide aqueous solution with a concentration of 2.5M, and stir at 60℃ for 1h; after filtration, disperse it in 50mL of sulfuric acid aqueous solution with a concentration of 5wt% H2SO4, and sonicate for 3min; after filtration, wash the copper powder with water until neutral, and dry it in a vacuum drying oven at 40℃ for 3h to obtain 5g of clean copper powder;

[0080] S2, ammonium metatungstate is added to water to form 25 mL of ammonium metatungstate solution with a concentration of 10 mM (ammonium metatungstate mass is 0.743 g). The cleaned copper powder mentioned above is then added to the ammonium metatungstate solution to obtain a dispersion. Then, 1 mL of APTMS solution with a mass fraction of 99% (APTMS mass is 1.03 g) is added dropwise to the dispersion, and the mixture is stirred for 0.5 h to obtain a mixture.

[0081] S3. Filter the mixture and then put it into a vacuum drying oven and dry it at 60°C for 1 hour to obtain copper powder with tungsten salt adsorbed on the surface.

[0082] S4. Copper powder with tungstate adsorbed on its surface is placed in a tube furnace and calcined under the condition of hydrogen and argon volume ratio of 5:95. The temperature is increased to 300℃ at a rate of 2℃ / min and held for 3h to obtain tungsten-coated copper antioxidant material.

[0083] Example 3

[0084] One embodiment of the tungsten-coated copper antioxidant material of the present invention is described below:

[0085] S1, take 5g of copper powder (D50 particle size is 0.4μm), add it to 50mL of sodium hydroxide aqueous solution with a concentration of 2.5M, and stir at 60℃ for 1h; after filtration, disperse it in 50mL of sulfuric acid aqueous solution with a concentration of 5wt% H2SO4, and sonicate for 3min; after filtration, wash the copper powder with water until neutral, and dry it in a vacuum drying oven at 25℃ for 3h to obtain 5g of clean copper powder;

[0086] S2, ammonium metatungstate is added to water to form 15 mL of ammonium metatungstate solution with a concentration of 5 mM (ammonium metatungstate mass is 0.22 g), and then the above-mentioned cleaned copper powder is added to the ammonium metatungstate solution to obtain a dispersion; then 0.2 mL of APTMS solution with a mass fraction of 98% (APTMS mass is 0.204 g) is added dropwise to the dispersion, and the mixture is stirred for 0.5 h to obtain a mixture;

[0087] S3. Filter the mixture and then put it into a vacuum drying oven and dry it at 40°C for 1 hour to obtain copper powder with tungsten salt adsorbed on the surface.

[0088] S4. Copper powder with tungstate adsorbed on its surface is placed in a tube furnace and calcined under the condition of hydrogen and argon volume ratio of 5:95. The temperature is increased to 370℃ at a rate of 2℃ / min and held for 1h to obtain tungsten-coated copper antioxidant material.

[0089] Example 4

[0090] One embodiment of the tungsten-coated copper antioxidant material of the present invention is described below:

[0091] S1. Take 5g of copper powder (D50 particle size is 0.4μm), add it to 50mL of sodium hydroxide aqueous solution with a concentration of 2.5M, and stir at 60℃ for 1h; after filtration, disperse it in 50mL of sulfuric acid aqueous solution with a concentration of 5wt% H2SO4, and sonicate for 3min; after filtration, wash the copper powder with water until neutral, and dry it in a vacuum drying oven at 30℃ for 3h to obtain 5g of clean copper powder;

[0092] S2, ammonium metatungstate is added to water to form 15 mL of ammonium metatungstate solution with a concentration of 30 mM (ammonium metatungstate mass is 1.338 g), and then the above-mentioned cleaned copper powder is added to the ammonium metatungstate solution to obtain a dispersion; then 1 mL of APTMS solution with a mass fraction of 99% (APTMS mass is 1.03 g) is added dropwise to the dispersion, and the mixture is stirred for 0.5 h to obtain a mixture;

[0093] S3. Filter the mixture and then put it into a vacuum drying oven and dry it at 25°C for 1 hour to obtain copper powder with tungsten salt adsorbed on the surface.

[0094] S4. Copper powder with tungstate adsorbed on its surface is placed in a tube furnace and calcined under the condition of hydrogen and argon volume ratio of 5:95. The temperature is increased to 300℃ at a rate of 2℃ / min and held for 3h to obtain tungsten-coated copper antioxidant material.

[0095] Example 5

[0096] One embodiment of the tungsten-coated copper antioxidant material of the present invention is described below:

[0097] S1, take 5g of copper powder (D50 particle size is 0.4μm), add it to 50mL of sodium hydroxide aqueous solution with a concentration of 2.5M, and stir at 60℃ for 1h; after filtration, disperse it in 50mL of sulfuric acid aqueous solution with a concentration of 5wt% H2SO4, and sonicate for 3min; after filtration, wash the copper powder with water until neutral, and dry it in a vacuum drying oven at 60℃ for 2h to obtain 5g of clean copper powder;

[0098] S2, ammonium metatungstate is added to water to form 15 mL of ammonium metatungstate solution with a concentration of 10 mM (ammonium metatungstate mass is 0.743 g), and then the above-mentioned cleaned copper powder is added to the ammonium metatungstate solution to obtain a dispersion; then 2 mL of APTMS solution with a mass fraction of 99% (APTMS mass is 2.06 g) is added dropwise to the dispersion, and the mixture is stirred for 0.5 h to obtain a mixture;

[0099] S3. Filter the mixture and then put it into a vacuum drying oven and dry it at 25°C for 1 hour to obtain copper powder with tungsten salt adsorbed on the surface.

[0100] S4. Copper powder with tungstate adsorbed on its surface is placed in a tube furnace and calcined under the condition of hydrogen and argon volume ratio of 5:95. The temperature is increased to 300℃ at a rate of 2℃ / min and held for 3h to obtain tungsten-coated copper antioxidant material.

[0101] Example 6

[0102] One embodiment of the tungsten-coated copper antioxidant material of the present invention is described below:

[0103] S1. Take 5g of copper powder (D50 particle size of 0.4μm), add it to 50mL of sodium hydroxide aqueous solution with a concentration of 2.5M, and stir at 60℃ for 1h; after filtration, disperse it in 50mL of sulfuric acid aqueous solution with a concentration of 5wt% H2SO4, and sonicate for 3min; after filtration, wash the copper powder with water until neutral, and dry it in a vacuum drying oven at 80℃ for 2h to obtain 5g of clean copper powder;

[0104] S2, ammonium metatungstate is added to water to form 25 mL of ammonium metatungstate solution with a concentration of 10 mM (ammonium metatungstate mass is 0.743 g). The cleaned copper powder mentioned above is then added to the ammonium metatungstate solution to obtain a dispersion. Then, 0.5 mL of APTMS solution with a mass fraction of 99% (APTMS mass is 0.51 g) is added dropwise to the dispersion, and the mixture is stirred for 0.5 h to obtain a mixture.

[0105] S3. Filter the mixture and then put it into a vacuum drying oven and dry it at 40°C for 1 hour to obtain copper powder with tungsten salt adsorbed on the surface.

[0106] S4. Copper powder with tungstate adsorbed on its surface is placed in a tube furnace and calcined under the condition of hydrogen and argon volume ratio of 5:95. The temperature is increased to 650℃ at a rate of 2℃ / min and held for 1h to obtain tungsten-coated copper antioxidant material.

[0107] Comparative Example 1

[0108] A copper material, the preparation method of which differs from that of Example 1 only in that it omits steps S2 to S3, specifically including the following steps:

[0109] Take 5g of copper powder (D50 particle size of 0.4μm), add it to 50mL of 2.5M sodium hydroxide aqueous solution, and stir at 60℃ for 1h; after filtration, disperse it in 50mL of 5wt% sulfuric acid aqueous solution of H2SO4, and sonicate for 3min; after filtration, wash the copper powder with water until neutral, and dry it in a vacuum drying oven at 30℃ for 3h to obtain 5g of clean copper powder;

[0110] Clean copper powder is placed in a tube furnace and calcined under conditions of hydrogen and argon volume ratio of 5:95. The temperature is increased to 300°C at a rate of 2°C / min and held for 3 hours to obtain the copper material.

[0111] Comparative Example 2

[0112] A copper-coated tungsten antioxidant material is prepared in a method that differs from that in Example 2 only in that, in step S2, ammonium metatungstate is added to water to form 15 mL of ammonium metatungstate solution with a concentration of 0.1 mM (the mass of ammonium metatungstate is 0.045 g).

[0113] Comparative Example 3

[0114] A copper-coated tungsten antioxidant material is prepared in a method that differs from that in Example 2 only in that no surfactant is added to the dispersion.

[0115] Performance testing

[0116] 1) Morphology and elemental distribution: The surface morphology and surface elemental distribution of tungsten-coated copper antioxidant materials and copper powder in the examples and comparative examples were observed using scanning electron microscopy;

[0117] 2) Conductivity: The resistivity of copper powder was tested using a powder resistivity tester;

[0118] 3) High-temperature oxidation resistance: The high-temperature oxidation resistance of tungsten-coated copper antioxidant material and copper powder before and after accelerated aging in an 85°C oven for 10 hours was characterized by the change in resistivity.

[0119] Table 1 shows the performance test results.

[0120] Table 1

[0121]

[0122]

[0123] The test results above show that Examples 1 to 6 have better antioxidant properties than Comparative Example 1. At high temperatures, their resistivity growth rate is less than 2000%, indicating good high-temperature antioxidant properties.

[0124] Furthermore, comparing the test results of Examples 1-3 and Example 4, it can be found that an excessively high concentration of ammonium metatungstate in the ammonium metatungstate solution can also affect the adsorption effect of tungsten salt, possibly due to uneven adsorption of tungsten salt on the surface of copper powder.

[0125] Comparing the test results of Examples 1-3 and Example 5, it can be found that, similarly, excessive amounts of surfactant can also affect the adsorption effect. Only when the mass ratio of surfactant to clean copper powder is 1:50 to 1:5 can tungsten salt be uniformly adsorbed on the surface of copper powder, thereby improving the high-temperature oxidation resistance of tungsten-coated copper antioxidant material.

[0126] Comparing the test results of Examples 1-3 and Example 6, it can be found that the tungsten-coated copper antioxidant material prepared at a calcination temperature in the range of 300-500℃ has better high-temperature oxidation resistance.

[0127] Figure 2 The images show scanning electron microscope (SEM) and EDX spectra of the tungsten-coated copper antioxidant material in Example 1 of this invention. As can be seen from the images, the surface of the tungsten-coated copper antioxidant material is smooth and the uniformity of the tungsten coating layer is good. Figure 3 The images shown are scanning electron microscope (SEM) images and EDX spectra of the tungsten-coated copper antioxidant material in Example 2 of this invention. Similarly, its surface is smooth and the tungsten coating layer is uniform. Figure 4 The image shows a scanning electron microscope (SEM) image of the copper material in Comparative Example 1. As can be seen from the image, the copper powder without coating treatment will form sintering necks between the copper powder particles when calcined at the same temperature because there is no tungsten protection on the surface, resulting in fusion and destruction of the original morphology of the copper. Figure 5 The images are scanning electron microscope (SEM) images of the tungsten-coated copper antioxidant materials in (a) Example 1, (b) Example 2 and (c) Comparative Example 2 after aging at 85°C for 10 hours. As can be seen from the images, the tungsten-coated copper antioxidant materials in Examples 1 and 2 still have a smooth surface after high-temperature aging, while the tungsten-coated copper antioxidant material in Comparative Example 2 has more burrs on its surface and poor high-temperature oxidation resistance.

[0128] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing a tungsten-coated copper oxidation resistant material, characterized by, The method comprises the following steps: S1, cleaning and first drying copper powder to obtain clean copper powder; S2, mixing tungsten salt, a surfactant, the clean copper powder and water, and stirring to obtain a mixture; S3, filtering and second drying the mixture to obtain copper powder with tungsten salt adsorbed on the surface; S4, calcining the copper powder with tungsten salt adsorbed on the surface in a reducing atmosphere to obtain the tungsten-coated copper oxidation-resistant material; In the S2, the tungsten salt is dissolved in the water to obtain a tungsten salt solution, then the clean copper powder is added to the tungsten salt solution to form a dispersion liquid, and then the surfactant is added to the dispersion liquid and stirred to obtain the mixture; In the S2, the mass ratio of the tungsten salt to the clean copper powder in the mixture is 1:100-1:10, the mass ratio of the surfactant to the clean copper powder is 1:50-1:5, and the concentration of the tungsten salt in the tungsten salt solution is 1mM-10mM; In the S2, the tungsten salt is at least one of ammonium metatungstate, sodium tungstate, phosphotungstic acid and ammonium paratungstate, and the surfactant is at least one of mercaptoethylamine, 3-(trimethoxysilyl)propylamine and cysteine; In the S4, the calcination temperature is 300-500℃, and the calcination time is 1-3h.

2. The method of claim 1, wherein the tungsten-coated copper oxidation resistant material is prepared by the steps of: In the S1, the copper powder is sequentially cleaned with an alkali solution, an acid solution and water, the alkali solution is at least one of sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the acid solution is at least one of sulfuric acid solution, hydrochloric acid and nitric acid solution.

3. The method of claim 2, wherein the tungsten-coated copper oxidation resistant material is prepared by the steps of: In the S1, the temperature for cleaning with the alkali solution is 60-80℃, and the time is 0.5-2h; and / or, the cleaning with the acid solution is assisted by ultrasonic, the cleaning time with the acid solution is 3-10min; and / or, the cleaning with water is to neutralization; And / or, the temperature for the first drying is 25-80℃, and the time for the first drying is 2-5h.

4. The method of claim 1, wherein the tungsten-coated copper oxidation resistant material is prepared by the steps of: In the S2, the stirring time is 0.5-3h.

5. The method of producing a tungsten-coated copper oxidation resistant material according to any one of claims 1 to 3, characterized in that, In the S3, the temperature for the second drying is 25-60℃, and the time for the second drying is 1-5h.

6. The method of claim 1, wherein the tungsten-coated copper oxidation resistant material is prepared by the steps of: In the S4, the reducing atmosphere is a mixture of hydrogen and an inert gas, and the inert gas is at least one of nitrogen, argon and helium.

7. A tungsten-coated copper oxidation resistant material, characterized by, Prepared by the method of any one of claims 1-6.

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