Nickel-chromium alloy clad aluminum-copper alloy composite grounding material and powder metallurgy preparation method

Abstract

The application relates to the technical field of grounding materials, and discloses a nickel-chromium alloy coated aluminum-copper alloy composite grounding material and a powder metallurgy preparation method, which comprises the following steps: uniformly mixing modified aluminum-copper alloy powder, nickel powder and chromium powder, vacuum drying, ball milling, and obtaining nickel-chromium powder coated aluminum-copper alloy powder; placing the nickel-chromium coated aluminum-copper alloy powder in a mold and cold pressing to form a grounding material blank; after sintering the grounding material blank, cooling to room temperature, and then machining and straightening, product inspection, a nickel-chromium alloy coated aluminum-copper alloy composite grounding material is formed. The nickel powder and the chromium powder are coated on the surface of the modified aluminum-copper alloy powder, the composite grounding material is formed through cold pressing, sintering and post-processing, a nickel-chromium corrosion-resistant layer can be formed on the surface of the aluminum-copper alloy base material, the mechanical strength and the corrosion resistance of the composite grounding material are improved, and the composite grounding material layer further contains nano zinc oxide and a carbon-metal layer, so that the mechanical strength and the corrosion resistance of the composite grounding material are enhanced.

Description

Technical Field

[0001] This invention relates to the field of grounding materials technology, specifically to nickel-chromium alloy-coated aluminum-copper alloy composite grounding materials and their powder metallurgy preparation method. Background Technology

[0002] As grounding device materials for power grid facilities, traditional grounding materials such as pure copper and pure aluminum are prone to corrosion in humid, saline-alkali, or acidic soil environments, leading to increased grounding resistance and affecting the safe operation of power equipment. Although copper has good corrosion resistance, it is expensive and heavy. Although aluminum is light and has good conductivity, its surface is easily oxidized and not corrosion resistant. The mainstream choice for high-conductivity deep-buried grounding device materials is conductive aluminum-copper alloy-based grounding materials, which have high conductivity and mechanical strength, and their conductivity far exceeds that of copper-clad steel and galvanized steel.

[0003] Aluminum-copper alloys not only possess high conductivity comparable to copper alloys, but also exhibit higher strength, hardness, and other mechanical properties than bronze alloys. Their low resistivity enables efficient current conduction, reducing the grounding resistance of the grounding electrode. Nickel-chromium alloys, with their excellent corrosion resistance, are widely used in various industries. The passivation film formed on their surface effectively slows down the oxidation process and extends the material's service life. By combining these two alloys, grounding device materials are expected to achieve a synergistic optimization of high conductivity and low corrosion resistance, breaking through the performance limitations of traditional grounding electrode materials.

[0004] Existing grounding materials prepared by coating or composite methods involve coating a nickel-chromium alloy onto an aluminum-copper alloy surface to form a grounding device material. The outer layer is nickel-chromium alloy, and the inner core is aluminum-copper alloy. This structure endows it with superior electrical performance, mechanical properties, and corrosion resistance. The material performs better than traditional power grounding materials in terms of soil corrosion resistance and fault current conduction, ensuring reliability and safety in long-term use. However, the nickel-chromium alloy and aluminum-copper alloy have poor interfacial bonding and are prone to delamination, which affects the mechanical strength and corrosion resistance of the composite grounding material. Summary of the Invention

[0005] This invention provides a nickel-chromium alloy-coated aluminum-copper alloy composite grounding material and a powder metallurgy preparation method, which solves the problems of poor interfacial bonding and easy delamination between nickel-chromium alloy and aluminum-copper alloy, which affect the mechanical strength and corrosion resistance of the composite grounding material.

[0006] The technical solution of the present invention: A powder metallurgical preparation method for nickel-chromium alloy-coated aluminum-copper alloy composite grounding materials includes the following steps: S1. Mix the modified aluminum-copper alloy powder, nickel powder and chromium powder evenly, dry under vacuum and ball mill to obtain nickel-chromium powder coated aluminum-copper alloy powder. S2. Place nickel-chromium coated aluminum-copper alloy powder in a mold and cold press it to form a grounding material blank; S3. After sintering the grounding material blank, cool it to room temperature and then perform post-processing to form a nickel-chromium alloy coated aluminum-copper alloy composite grounding material. The modified aluminum-copper alloy powder is obtained by mixing acidified nano zinc oxide with phenolic resin to form modified phenolic resin, and then coating the surface of the aluminum-copper alloy powder with the modified phenolic resin.

[0007] Further, in step S1, the mass ratio of the modified aluminum-copper alloy powder, nickel powder, and chromium powder is 100:(6-6.4):(1.4-1.6).

[0008] Furthermore, in step S1, the vacuum drying temperature is 100-110℃, the vacuum degree is 4-6Pa, and the vacuum drying time is 20-30min.

[0009] Further, in step S1, the ball milling is carried out in a ball mill, the ball material is zirconia grinding balls with a diameter of 10 mm, the ball-to-material ratio is (15-20):1, the rotation speed is 200-300 r / min, and the ball milling time is 10-15 h.

[0010] Furthermore, in step S2, the mold is made of high-strength steel; the cold pressing pressure is 300-350MPa, and the cold pressing time is 10-15min.

[0011] Further, in step S3, the sintering specifically includes: a first sintering temperature of 560-580℃, a first sintering time of 90-120 min, and a heating rate of 3℃ / min; a second sintering temperature of 600-620℃, a second sintering time of 120-130 min, a heating rate of 5℃ / min, and a sintering atmosphere of nitrogen.

[0012] Furthermore, the modified aluminum-copper alloy powder is specifically prepared by the following steps: A1. Add nano zinc oxide and deionized water to a sand grinding cylinder, stir evenly, add 0.1-0.3 mol / L dilute hydrochloric acid to adjust the pH to 4-5, grind, filter, wash, and dry to obtain acidified nano zinc oxide; A2. Place the acidified nano zinc oxide in a phenolic resin ethanol solution with a mass fraction of 14-16%, immerse it at 60-80℃ for 1-2 hours, take it out, and dry it at 80-100℃ for 1-2 hours to completely remove the ethanol solvent and obtain the modified phenolic resin. A3. Mix the modified phenolic resin and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 40-60℃ and 200-300r / min for 30-40min, dry to remove ethanol solvent, cool to room temperature, grind and disperse, and sieve to obtain modified aluminum-copper alloy powder.

[0013] Furthermore, in the A1 reaction process described above, dilute hydrochloric acid with a concentration of 0.1-0.3 mol / L is used as an acidifying agent, which causes a small amount of zinc ions to dissolve from the surface of the nano zinc oxide, exposing a large number of hydroxyl functional groups on the surface of the nano zinc oxide, thus obtaining acidified nano zinc oxide.

[0014] Furthermore, in the A2 reaction process described above, the acidified nano zinc oxide is placed in an ethanol solution containing phenolic resin at 60-80℃ for 1-2 hours and then dried at 80-100℃ for 1-3 hours, so that the phenolic resin coats the surface of the acidified nano zinc oxide to obtain modified phenolic resin.

[0015] Furthermore, during the A3 reaction process described above, the phenolic resin material in the modified phenolic resin has adhesive properties, which allows the modified phenolic resin to adhere to the surface of the aluminum-copper alloy powder, thereby obtaining modified aluminum-copper alloy powder.

[0016] Further, in step A1, the mass ratio of the nano zinc oxide to deionized water is 1:(4-5).

[0017] Further, in step A2, the mass ratio of the acidified nano zinc oxide and the phenolic resin ethanol solution is 1:(10-12).

[0018] Further, in step A3, the mass ratio of the modified phenolic resin, ethanol and aluminum-copper alloy powder is 1:(5-6):(100-110).

[0019] The present invention has the following beneficial effects: (1) In the technical solution of the present invention, the nano zinc oxide is acidified so that the surface of the nano zinc oxide is rich in a large number of hydroxyl groups, which can form hydrogen bonds with phenolic resin molecules, so that the phenolic resin tightly coats the surface of the nano zinc oxide, which is beneficial to coat the nano zinc oxide onto the surface of aluminum-copper alloy powder through phenolic resin; embedding a small amount of nano zinc oxide between the nickel-chromium alloy and the aluminum-copper alloy layers does not affect the conductivity of the composite grounding material, and can fill the gap between the nickel-chromium alloy and the aluminum-copper alloy layers with nano zinc oxide to form a continuous and dense inorganic barrier layer, reduce the rate at which the corrosive medium reaches the aluminum-copper substrate, and work with the nickel-chromium alloy layer to improve the corrosion resistance of the composite grounding material.

[0020] (2) In the technical solution of the present invention, phenolic resin is coated on the surface of acidified nano zinc oxide to obtain modified phenolic resin. On the one hand, phenolic resin has high adhesion performance, which enables acidified nano zinc oxide to be uniformly loaded onto the surface of aluminum-copper alloy powder through phenolic resin, so as to realize that nano zinc oxide fills the gap between nickel-chromium alloy and aluminum-copper alloy layer, exert the corrosion resistance of nano zinc oxide, and thus improve the corrosion resistance of composite grounding material. On the other hand, during the ball milling process in step A1, the excellent adhesion performance of phenolic resin can uniformly coat nickel powder and chromium powder on the surface of aluminum-copper alloy powder to form dense nickel-chromium powder coated aluminum-copper alloy powder, which is conducive to forming a composite grounding material with high strength and excellent corrosion resistance.

[0021] (3) In the technical solution of the present invention, the modified aluminum-copper alloy powder formed by the modified phenolic resin adhering to the surface of the aluminum-copper alloy powder is mixed with nickel powder and chromium powder to obtain nickel-chromium powder coated aluminum-copper alloy powder. On the one hand, during the two sintering processes at 560-580℃ and 600-620℃, the phenolic resin on the surface of the modified aluminum-copper alloy powder is thermally decomposed to form a large amount of active carbon elements. The active carbon elements can form a carbon-metal layer with nickel, chromium elements and aluminum and copper elements on the surface of the aluminum-copper alloy powder. The carbon-metal layer is distributed at the interface between the nickel-chromium alloy and the aluminum-copper alloy. This process improves the interfacial bonding strength, avoiding poor interfacial bonding and easy delamination between nickel-chromium alloy and aluminum-copper alloy, which affects the mechanical strength and corrosion resistance of the composite grounding material. On the other hand, the phenolic resin on the surface of the modified aluminum-copper alloy powder decomposes upon heating, releasing nano-zinc oxide, which can fill the gaps between the nickel-chromium alloy and aluminum-copper alloy layers. This solves the problem of phenolic resin easily forming gaps upon heating, increases the density between the nickel-chromium alloy and aluminum-copper alloy layers, and thus improves the mechanical strength and corrosion resistance of the composite grounding material.

[0022] (4) In the technical solution of the present invention, by coating nickel powder and chromium powder on the surface of modified aluminum-copper alloy powder, and forming a composite grounding material by cold pressing, sintering and post-treatment, a nickel-chromium anti-corrosion layer can be formed on the surface of the aluminum-copper alloy substrate, which improves the mechanical strength and anti-corrosion performance of the composite grounding material. In addition, the composite grounding material also contains nano zinc oxide and carbon-metal layer between the layers, which significantly enhances the mechanical strength and anti-corrosion performance of the composite grounding material. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] The raw materials used in the embodiments of this invention are shown below, and all reagents used are analytical grade.

[0025] Among them, the aluminum-copper alloy powder has a particle size of 200 mesh, the nickel powder has a particle size of 100 mesh, the chromium powder has a particle size of 100 mesh, and the nano zinc oxide has a particle size of 50 nm.

[0026] The phenolic resin, catalog number P832682, BR, was purchased from Maclean's Reagents.

[0027] Example 1

[0028] A powder metallurgical preparation method for nickel-chromium alloy-coated aluminum-copper alloy composite grounding materials includes the following steps: S1. The modified aluminum-copper alloy powder, nickel powder, and chromium powder are mixed evenly and vacuum dried at 100℃ and 4Pa for 20 min. The mixture is then ball-milled to obtain nickel-chromium powder-coated aluminum-copper alloy powder. The mass ratio of the modified aluminum-copper alloy powder, nickel powder, and chromium powder is 100:6:1.4. The ball milling is carried out in a ball mill with 10 mm diameter zirconia grinding balls. The ball-to-material ratio is 15:1, the rotation speed is 200 r / min, and the ball milling time is 10 h. S2. Place the nickel-chromium coated aluminum-copper alloy powder in a high-strength steel mold and cold press it at 300MPa for 10 minutes to obtain the grounding material blank. S3. After sintering the grounding material blank, cool it to room temperature, then straighten it by machining, and inspect the finished product to form a nickel-chromium alloy-coated aluminum-copper alloy composite grounding material. The sintering process is as follows: the first sintering temperature is 560℃, the first sintering time is 90min, and the heating rate is 3℃ / min; the second sintering temperature is 600℃, the second sintering time is 120min, the heating rate is 5℃ / min, and the sintering atmosphere is nitrogen.

[0029] Modified aluminum-copper alloy powder is prepared by the following steps: A1. Add nano zinc oxide and deionized water to a sand mill, stir evenly, add 0.1 mol / L dilute hydrochloric acid to adjust the pH to 4, grind at 4000 r / min for 1 h, filter, wash with deionized water until the pH of the washing solution is neutral, and dry in an oven at 80℃ for 20 min to obtain acidified nano zinc oxide; the mass ratio of nano zinc oxide to deionized water is 1:4. A2. Acidified nano zinc oxide was placed in a 14% (w / w) phenolic resin ethanol solution and immersed at 60°C for 1 hour. After immersion, it was removed and dried at 80°C for 1 hour to completely remove the ethanol solvent, thus obtaining modified phenolic resin. The mass ratio of acidified nano zinc oxide to phenolic resin ethanol solution was 1:10. A3. Mix the modified phenolic resin and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 40℃ and 200r / min for 30min, dry in an oven at 90℃ for 1.5h to remove ethanol solvent, cool to room temperature, grind and disperse, and pass through a 300-mesh sieve to obtain modified aluminum-copper alloy powder; the mass ratio of modified phenolic resin, ethanol and aluminum-copper alloy powder is 1:5:100.

[0030] Example 2

[0031] A powder metallurgical preparation method for nickel-chromium alloy-coated aluminum-copper alloy composite grounding materials includes the following steps: S1. The modified aluminum-copper alloy powder, nickel powder, and chromium powder are mixed evenly and vacuum dried at 105℃ and 5Pa for 25 min. The mixture is then ball-milled to obtain nickel-chromium powder-coated aluminum-copper alloy powder. The mass ratio of the modified aluminum-copper alloy powder, nickel powder, and chromium powder is 100:6.2:1.5. The ball milling is carried out in a ball mill, using 10 mm diameter zirconia grinding balls. The ball-to-material ratio is 18:1, the rotation speed is 250 r / min, and the ball milling time is 13 h. S2. Place the nickel-chromium coated aluminum-copper alloy powder in a high-strength steel mold and cold press it at 330MPa for 13 minutes to obtain the grounding material blank. S3. After sintering the grounding material blank, cool it to room temperature, then straighten it by machining, and inspect the finished product to form a nickel-chromium alloy coated aluminum-copper alloy composite grounding material. The sintering process is as follows: the first sintering temperature is 570℃, the first sintering time is 110min, and the heating rate is 3℃ / min; the second sintering temperature is 610℃, the second sintering time is 125min, the heating rate is 5℃ / min, and the sintering atmosphere is nitrogen.

[0032] Modified aluminum-copper alloy powder is prepared by the following steps: A1. Nano zinc oxide and deionized water were added to a sand mill and stirred evenly. 0.2 mol / L dilute hydrochloric acid was added to adjust the pH to 4.5. The mixture was ground at 4000 r / min for 1 h. After filtration, the mixture was washed with deionized water until the pH of the washing solution was neutral. The solution was then dried in an oven at 80℃ for 20 min to obtain acidified nano zinc oxide. The mass ratio of nano zinc oxide to deionized water was 1:4.5. A2. Acidified nano zinc oxide was placed in a 15% (w / w) phenolic resin ethanol solution and immersed at 70°C for 1.5 h. After immersion, it was removed and dried at 90°C for 1.5 h to completely remove the ethanol solvent, thus obtaining modified phenolic resin. The mass ratio of acidified nano zinc oxide to phenolic resin ethanol solution was 1:11. A3. Mix modified phenolic resin and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 50℃ and 250r / min for 35min, dry in an oven at 90℃ for 1.5h to remove ethanol solvent, cool to room temperature, grind and disperse, and pass through a 300-mesh sieve to obtain modified aluminum-copper alloy powder; the mass ratio of modified phenolic resin, ethanol and aluminum-copper alloy powder is 1:5.5:105.

[0033] Example 3

[0034] A powder metallurgical preparation method for nickel-chromium alloy-coated aluminum-copper alloy composite grounding materials includes the following steps: S1. The modified aluminum-copper alloy powder, nickel powder, and chromium powder are mixed evenly and vacuum dried at 110℃ and 6Pa for 30 min. The mixture is then ball-milled to obtain nickel-chromium powder-coated aluminum-copper alloy powder. The mass ratio of the modified aluminum-copper alloy powder, nickel powder, and chromium powder is 100:6.4:1.6. The ball milling is carried out in a ball mill with 10 mm diameter zirconia grinding balls. The ball-to-material ratio is 20:1, the rotation speed is 300 r / min, and the ball milling time is 15 h. S2. Place the nickel-chromium coated aluminum-copper alloy powder in a high-strength steel mold and cold press it at 350MPa for 15 minutes to obtain the grounding material blank. S3. After sintering the grounding material blank, cool it to room temperature, then straighten it by machining, and inspect the finished product to form a nickel-chromium alloy-coated aluminum-copper alloy composite grounding material. The sintering process is as follows: the first sintering temperature is 580℃, the first sintering time is 120min, and the heating rate is 3℃ / min; the second sintering temperature is 620℃, the second sintering time is 130min, the heating rate is 5℃ / min, and the sintering atmosphere is nitrogen.

[0035] Modified aluminum-copper alloy powder is prepared by the following steps: A1. Nano zinc oxide and deionized water were added to a sand mill and stirred evenly. 0.3 mol / L dilute hydrochloric acid was added to adjust the pH to 5. The mixture was ground at 4000 r / min for 1 h. After filtration, the mixture was washed with deionized water until the pH of the washing solution was neutral. The solution was then dried in an oven at 80℃ for 20 min to obtain acidified nano zinc oxide. The mass ratio of nano zinc oxide to deionized water was 1:5. A2. Acidified nano zinc oxide was placed in a 16% (w / w) phenolic resin ethanol solution and immersed at 80°C for 2 hours. After immersion, it was removed and dried at 100°C for 2 hours to completely remove the ethanol solvent, thus obtaining modified phenolic resin. The mass ratio of acidified nano zinc oxide to phenolic resin ethanol solution was 1:12. A3. Mix modified phenolic resin and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 60℃ and 300r / min for 40min, dry in an oven at 90℃ for 1.5h to remove ethanol solvent, cool to room temperature, grind and disperse, and pass through a 300-mesh sieve to obtain modified aluminum-copper alloy powder; the mass ratio of modified phenolic resin, ethanol and aluminum-copper alloy powder is 1:6:110.

[0036] Comparative Example 1 The only difference between this comparative example and Example 3 is the preparation of the modified aluminum-copper alloy powder, as detailed below: Modified aluminum-copper alloy powder is prepared by the following steps: A1. Nano zinc oxide was placed in a 16% (w / w) phenolic resin ethanol solution and immersed at 80°C for 2 hours. After immersion, it was removed and dried at 100°C for 2 hours to completely remove the ethanol solvent, thus obtaining modified phenolic resin. The mass ratio of nano zinc oxide to phenolic resin ethanol solution was 1:12. A2. Mix modified phenolic resin and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 60℃ and 300r / min for 40min, dry in an oven at 90℃ for 1.5h to remove ethanol solvent, cool to room temperature, grind and disperse, and pass through a 300-mesh sieve to obtain modified aluminum-copper alloy powder; the mass ratio of modified phenolic resin, ethanol and aluminum-copper alloy powder is 1:6:110.

[0037] Comparative Example 2 The only difference between this comparative example and Example 3 is the preparation of the modified aluminum-copper alloy powder, as detailed below: Modified aluminum-copper alloy powder is prepared by the following steps: A1. Nano zinc oxide and deionized water were added to a sand mill and stirred evenly. 0.3 mol / L dilute hydrochloric acid was added to adjust the pH to 5. The mixture was ground at 4000 r / min for 1 h. After filtration, the mixture was washed with deionized water until the pH of the washing solution was neutral. The solution was then dried in an oven at 80℃ for 20 min to obtain acidified nano zinc oxide. The mass ratio of nano zinc oxide to deionized water was 1:5. A2. Mix acidified nano zinc oxide and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 60℃ and 300r / min for 40min, dry in an oven at 90℃ for 1.5h to remove ethanol solvent, cool to room temperature, grind and disperse, and pass through a 300-mesh sieve to obtain modified aluminum-copper alloy powder; the mass ratio of acidified nano zinc oxide, ethanol and aluminum-copper alloy powder is 1:6:110.

[0038] Comparative Example 3 The only difference between this comparative example and Example 3 is the preparation of the modified aluminum-copper alloy powder, as detailed below: Modified aluminum-copper alloy powder is prepared by the following steps: Phenolic resin and ethanol were mixed and stirred evenly. Aluminum-copper alloy powder was added and stirred at 60℃ and 300r / min for 40min. The mixture was then dried in an oven at 90℃ for 1.5h to remove the ethanol solvent. After cooling to room temperature, the mixture was ground and dispersed, and then passed through a 300-mesh sieve to obtain modified aluminum-copper alloy powder. The mass ratio of phenolic resin, ethanol and aluminum-copper alloy powder was 1:6:110.

[0039] Comparative Example 4 The only difference between this comparative example and Example 3 is the preparation of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material, as detailed below: S1. The modified aluminum-copper alloy powder and chromium powder are mixed evenly and vacuum dried at 110℃ and 6Pa for 30 min. The mixture is then ball-milled to obtain chromium-coated aluminum-copper alloy powder. The mass ratio of the modified aluminum-copper alloy powder to the chromium powder is 100:8. The ball milling is carried out in a ball mill, using 10 mm diameter zirconia grinding balls. The ball-to-material ratio is 20:1, the rotation speed is 300 r / min, and the ball milling time is 15 h. S2. Place the chromium powder-coated aluminum-copper alloy powder in a high-strength steel mold and cold press it at 350MPa for 15 minutes to obtain the grounding material blank. S3. After sintering the grounding material blank, cool it to room temperature, then straighten it by machining, and inspect the finished product to form a nickel-chromium alloy-coated aluminum-copper alloy composite grounding material. The sintering process is as follows: the first sintering temperature is 580℃, the first sintering time is 120min, and the heating rate is 3℃ / min; the second sintering temperature is 620℃, the second sintering time is 130min, the heating rate is 5℃ / min, and the sintering atmosphere is nitrogen.

[0040] Modified aluminum-copper alloy powder is prepared by the following steps: A1. Nano zinc oxide and deionized water were added to a sand mill and stirred evenly. 0.3 mol / L dilute hydrochloric acid was added to adjust the pH to 5. The mixture was ground at 4000 r / min for 1 h. After filtration, the mixture was washed with deionized water until the pH of the washing solution was neutral. The solution was then dried in an oven at 80℃ for 20 min to obtain acidified nano zinc oxide. The mass ratio of nano zinc oxide to deionized water was 1:5. A2. Acidified nano zinc oxide was placed in a 16% (w / w) phenolic resin ethanol solution and immersed at 80°C for 2 hours. After immersion, it was removed and dried at 100°C for 2 hours to completely remove the ethanol solvent, thus obtaining modified phenolic resin. The mass ratio of acidified nano zinc oxide to phenolic resin ethanol solution was 1:12. A3. Mix modified phenolic resin and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 60℃ and 300r / min for 40min, dry in an oven at 90℃ for 1.5h to remove ethanol solvent, cool to room temperature, grind and disperse, and pass through a 300-mesh sieve to obtain modified aluminum-copper alloy powder; the mass ratio of modified phenolic resin, ethanol and aluminum-copper alloy powder is 1:6:110.

[0041] Comparative Example 5 The only difference between this comparative example and Example 3 is the preparation of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material, as detailed below: S1. The modified aluminum-copper alloy powder and nickel powder are mixed evenly and vacuum dried at 110℃ and 6Pa for 30 min. The mixture is then ball-milled to obtain nickel-coated aluminum-copper alloy powder. The mass ratio of modified aluminum-copper alloy powder to nickel powder is 100:8. The ball milling is carried out in a ball mill. The ball material is zirconia grinding balls with a diameter of 10 mm. The ball-to-material ratio is 20:1. The rotation speed is 300 r / min. The ball milling time is 15 h. S2. Place the nickel powder coated aluminum-copper alloy powder in a high-strength steel mold and cold press it at 350MPa for 15 minutes to obtain the grounding material blank. S3. After sintering the grounding material blank, cool it to room temperature, then straighten it by machining, and inspect the finished product to form a nickel-chromium alloy-coated aluminum-copper alloy composite grounding material. The sintering process is as follows: the first sintering temperature is 580℃, the first sintering time is 120min, and the heating rate is 3℃ / min; the second sintering temperature is 620℃, the second sintering time is 130min, the heating rate is 5℃ / min, and the sintering atmosphere is nitrogen.

[0042] Modified aluminum-copper alloy powder is prepared by the following steps: A1. Nano zinc oxide and deionized water were added to a sand mill and stirred evenly. 0.3 mol / L dilute hydrochloric acid was added to adjust the pH to 5. The mixture was ground at 4000 r / min for 1 h. After filtration, the mixture was washed with deionized water until the pH of the washing solution was neutral. The solution was then dried in an oven at 80℃ for 20 min to obtain acidified nano zinc oxide. The mass ratio of nano zinc oxide to deionized water was 1:5. A2. Acidified nano zinc oxide was placed in a 16% (w / w) phenolic resin ethanol solution and immersed at 80°C for 2 hours. After immersion, it was removed and dried at 100°C for 2 hours to completely remove the ethanol solvent, thus obtaining modified phenolic resin. The mass ratio of acidified nano zinc oxide to phenolic resin ethanol solution was 1:12. A3. Mix modified phenolic resin and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 60℃ and 300r / min for 40min, dry in an oven at 90℃ for 1.5h to remove ethanol solvent, cool to room temperature, grind and disperse, and pass through a 300-mesh sieve to obtain modified aluminum-copper alloy powder; the mass ratio of modified phenolic resin, ethanol and aluminum-copper alloy powder is 1:6:110.

[0043] The performance of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding materials prepared in Examples 1-3 and Comparative Examples 1-5 was tested.

[0044] The nickel-chromium alloy-coated aluminum-copper alloy composite grounding material prepared above has a diameter of 16 mm, a length of 50 mm, and a coating thickness of 0.6-1 mm.

[0045] Corrosion resistance: The experimental soil consisted of two actual soil types: acidic soil from Chizhou City, Anhui Province, and saline-alkali soil from the National Field Scientific Observation and Research Station for Atmospheric Environmental Material Corrosion in Weili County, Xinjiang Province; as shown in Table 1 below: Table 1

[0046] The indoor simulated soil corrosion accelerated test was conducted in accordance with the Zhongguancun Materials Testing Technology Alliance standard T / CSTM00046.4-2018 "Corrosion Test of Low Alloy Structural Steel Part 4: Corrosion Test in Simulated Soil Environment". The soil used was acidic soil from Chizhou and saline-alkali soil from Weili. The soil was naturally air-dried, crushed and ground, and then passed through a 20-mesh sieve. The sieved soil samples were placed in a clean container and dried at 105℃ for 6 hours. After cooling, the samples were weighed and distilled water was added to prepare a soil medium with a moisture content of 20%. The indoor soil corrosion test was then carried out at a temperature of 70℃ for 30 days. After the test, the samples were taken out, the loose soil was cleaned with a brush, and the corrosion morphology of the nickel-chromium alloy coated aluminum-copper alloy composite grounding material prepared above was observed.

[0047] Mechanical strength: Tensile strength is tested according to standard GB / T32498-2016, and interlaminar shear strength is tested according to standard GB / T21698-2022.

[0048] Electrical conductivity: Resistivity is tested according to standard IEC60468:1974.

[0049] The test results are shown in Table 2.

[0050] Table 2 Performance testing of composite grounding materials prepared in Examples 1-3 and Comparative Examples 1-5

[0051] As can be seen from the data in Table 2, the nickel-chromium alloy-coated aluminum-copper alloy composite grounding materials prepared using Examples 1-3 have high mechanical strength and corrosion resistance, and the nickel-chromium alloy and aluminum-copper alloy have high interfacial bonding strength.

[0052] Comparative Example 1 showed that replacing acidified nano-zinc oxide with modified aluminum-copper alloy powder prepared from nano-zinc oxide resulted in a decrease in the mechanical strength and corrosion resistance of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material. This demonstrates that acidification of nano-zinc oxide enriches its surface with numerous hydroxyl groups, enabling it to form hydrogen bonds with phenolic resin molecules. This allows the phenolic resin to tightly coat the surface of the nano-zinc oxide, facilitating the coating of nano-zinc oxide onto the aluminum-copper alloy powder surface via phenolic resin. Furthermore, embedding a small amount of nano-zinc oxide between the nickel-chromium alloy and aluminum-copper alloy layers does not affect the conductivity of the composite grounding material. The nano-zinc oxide also fills the gaps between the nickel-chromium alloy and aluminum-copper alloy layers, forming a continuous and dense inorganic barrier layer. This reduces the rate at which corrosive media reaches the aluminum-copper substrate and, in conjunction with the nickel-chromium alloy layer, improves the corrosion resistance of the composite grounding material.

[0053] Comparative Example 2 showed that when modified aluminum-copper alloy powder prepared by replacing modified phenolic resin with acidified nano zinc oxide was used to prepare nickel-chromium alloy-coated aluminum-copper alloy composite grounding material, its mechanical strength and corrosion resistance decreased. This demonstrates that the phenolic resin coating on the surface of acidified nano zinc oxide has high adhesion properties, allowing the acidified nano zinc oxide to be uniformly loaded onto the surface of the aluminum-copper alloy powder through the phenolic resin. This enables the nano zinc oxide to fill the gaps between the nickel-chromium alloy and the aluminum-copper alloy layers, thus leveraging the corrosion resistance of the nano zinc oxide and improving the corrosion resistance of the composite grounding material. Furthermore, the excellent adhesion properties of the phenolic resin can uniformly coat the nickel and chromium powders onto the surface of the aluminum-copper alloy powder, forming a dense nickel-chromium powder-coated aluminum-copper alloy powder, which is beneficial for forming a composite grounding material with high strength and excellent corrosion resistance.

[0054] Comparative Example 3 showed that the modified aluminum-copper alloy powder prepared by replacing the modified phenolic resin with phenolic resin was used to prepare nickel-chromium alloy-coated aluminum-copper alloy composite grounding material. Its mechanical strength and corrosion resistance decreased, which proved that the phenolic resin on the surface of the modified aluminum-copper alloy powder decomposed under heat, releasing nano-zinc oxide, which could fill the gaps between the nickel-chromium alloy and aluminum-copper alloy layers. This solved the problem of phenolic resin easily forming gaps when heated, improved the density between the nickel-chromium alloy and aluminum-copper alloy layers, and thus improved the mechanical strength and corrosion resistance of the composite grounding material.

[0055] Comparative Example 4, in which nickel powder was replaced by chromium powder, and Comparative Example 5, in which chromium powder was replaced by nickel powder, produced nickel-chromium alloy-coated aluminum-copper alloy composite grounding materials. The mechanical strength and corrosion resistance of these materials decreased. This demonstrates that by coating the surface of modified aluminum-copper alloy powder with nickel and chromium powder, followed by cold pressing, sintering, and post-treatment to form a composite grounding material, a nickel-chromium anti-corrosion layer can be formed on the surface of the aluminum-copper alloy substrate. This improves the mechanical strength and corrosion resistance of the composite grounding material. Furthermore, the composite grounding material contains nano-zinc oxide and carbon-metal layers between its layers, further enhancing its mechanical strength and corrosion resistance.

[0056] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0057] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A powder metallurgy preparation method for nickel-chromium alloy-coated aluminum-copper alloy composite grounding material, characterized in that, Includes the following steps: S1. Mix the modified aluminum-copper alloy powder, nickel powder and chromium powder evenly, dry under vacuum and ball mill to obtain nickel-chromium powder coated aluminum-copper alloy powder. S2. Place nickel-chromium coated aluminum-copper alloy powder in a mold and cold press it to form a grounding material blank; S3. After sintering the grounding material blank, cool it to room temperature, then straighten it by machining, and inspect the finished product to form a nickel-chromium alloy coated aluminum-copper alloy composite grounding material. The modified aluminum-copper alloy powder is obtained by mixing acidified nano zinc oxide with phenolic resin to form modified phenolic resin, and then coating the surface of the aluminum-copper alloy powder with the modified phenolic resin.

2. The powder metallurgy preparation method of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material according to claim 1, characterized in that, In step S1, the mass ratio of the modified aluminum-copper alloy powder, nickel powder, and chromium powder is 100:(6-6.4):(1.4-1.6). In step S1, the vacuum drying temperature is 100-110℃, the vacuum degree is 4-6Pa, and the vacuum drying time is 20-30min.

3. The powder metallurgy preparation method of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material according to claim 1, characterized in that, In step S1, the ball milling is carried out in a ball mill, the ball material is zirconia grinding balls with a diameter of 10 mm, the ball-to-material ratio is (15-20):1, the rotation speed is 200-300 r / min, and the ball milling time is 10-15 h.

4. The powder metallurgy preparation method of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material according to claim 1, characterized in that, In step S2, the mold is made of high-strength steel; the cold pressing pressure is 300-350MPa, and the cold pressing time is 10-15min.

5. The powder metallurgy preparation method of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material according to claim 1, characterized in that, In step S3, the sintering specifically involves: a first sintering temperature of 560-580℃, a first sintering time of 90-120 min, and a heating rate of 3℃ / min; a second sintering temperature of 600-620℃, a second sintering time of 120-130 min, a heating rate of 5℃ / min, and a sintering atmosphere of nitrogen.

6. The powder metallurgy preparation method of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material according to claim 1, characterized in that, The modified aluminum-copper alloy powder is prepared by the following steps: A1. Add nano zinc oxide and deionized water to a sand grinding cylinder, stir evenly, add 0.1-0.3 mol / L dilute hydrochloric acid to adjust the pH to 4-5, grind, filter, wash, and dry to obtain acidified nano zinc oxide; A2. Place the acidified nano zinc oxide in a phenolic resin ethanol solution with a mass fraction of 14-16%, immerse it at 60-80℃ for 1-2 hours, take it out, and dry it at 80-100℃ for 1-2 hours to completely remove the ethanol solvent and obtain the modified phenolic resin. A3. Mix the modified phenolic resin and ethanol, stir evenly, add aluminum-copper alloy powder, stir at 40-60℃ and 200-300r / min for 30-40min, dry to remove ethanol solvent, cool to room temperature, grind and disperse, and sieve to obtain modified aluminum-copper alloy powder.

7. The powder metallurgy preparation method of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material according to claim 6, characterized in that, In step A1, the mass ratio of nano zinc oxide to deionized water is 1:(4-5).

8. The powder metallurgy preparation method of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material according to claim 6, characterized in that, In step A2, the mass ratio of the acidified nano zinc oxide and the phenolic resin ethanol solution is 1:(10-12).

9. The powder metallurgy preparation method of the nickel-chromium alloy-coated aluminum-copper alloy composite grounding material according to claim 6, characterized in that, In step A3, the mass ratio of the modified phenolic resin, ethanol and aluminum-copper alloy powder is 1:(5-6):(100-110).

10. A nickel-chromium alloy-clad aluminum-copper alloy composite grounding material prepared by the powder metallurgy preparation method of the nickel-chromium alloy-clad aluminum-copper alloy composite grounding material according to any one of claims 1-9.

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