Corrosion-resistant aluminum alloy grounding body material and preparation process thereof

Abstract

The invention belongs to the technical field of aluminum alloy, and particularly relates to a corrosion-resistant aluminum alloy grounding body material and a preparation process thereof. The preparation process comprises the following steps: (1) weighing components of an aluminum alloy, wherein the aluminum alloy comprises the following components in percentage by weight: 0.01%-0.5% of Re, 0.05%-0.27% of Ce, 0.5%-1.72% of Mg, 0.01%-5% of Cu, 0.05%-3% of Si, 0.01%-1% of Zr, 0.01%-0.5% of Ti, 0.01%-1.5% of Mn and the balance of Al; (2) preparing a hot extrusion part; (3) carrying out high-pressure sand blasting surface treatment on the surface of the extruded part; (4) the aluminum alloy subjected to sand blasting is subjected to destressing annealing heat treatment; and (5) surface anodic oxidation. The corrosion-resistant aluminum alloy grounding body material prepared by the invention is high in corrosion resistance in high-saline-alkali soil in a yellow irrigation area, and is excellent in grounding performance and mechanical performance at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloys, and in particular relates to a corrosion-resistant aluminum alloy grounding body material and a preparation process thereof. Background Art

[0002] As the power grid has increased its requirements for the safety of transmission lines, safe and strong power transmission and transformation technology is an important development direction in the future, and higher requirements are placed on the corrosion resistance of grounding materials and the safety performance of grounding networks. The damage or failure of this type of buried equipment is mainly due to electrochemical corrosion in corrosive soil environments and corrosion caused by leakage current during the operation of power grid equipment. Soil corrosion causes oxides to form on the surface of buried materials, reducing or even breaking the cross-sectional area, resulting in poor grounding performance, which may lead to accidents, endangering equipment and personal safety, and causing significant economic losses.

[0003] At present, the commonly used grounding materials mainly include galvanized steel and pure copper. Galvanized steel as a grounding material will generally have serious corrosion problems after 8 to 10 years of operation. Especially in the high-salinity soil in the Huangguan area, the corrosion rate of galvanized steel is very fast. It needs to be excavated and inspected regularly and modified according to the degree of corrosion. It cannot meet the requirements for safe operation of the power system. In addition, the excavation, inspection and maintenance of the grounding grid require earthwork construction, which is costly and affects the normal operation of the equipment, making it difficult to implement. Pure copper has good electrical conductivity and corrosion resistance. As a grounding material, it has the characteristics of long life and high reliability, but copper is a heavy metal that pollutes the environment and is also expensive.

[0004] Therefore, the research and development of key technologies to improve the corrosion resistance of grounding materials is of great significance to improving the anti-corrosion performance of the grounding grid of transmission towers and ensuring the stability of the grounding performance of the grounding grid. It is also a key problem that needs to be solved in the safe production of the transmission system. As the most widely used lightweight metal, aluminum alloy has low production and processing costs, and aluminum alloy itself has good corrosion resistance and electrical conductivity. In addition, compared with traditional galvanized grounding flat steel and copper grounding bodies, aluminum alloy gold grounding materials are prepared by plastic processing methods, without the need for surface treatment processes such as hot-dip galvanizing, which can effectively avoid heavy metal pollution of the soil and the discharge of wastewater and exhaust gas, and have a good environmental protection effect.

[0005] The Chinese patent with publication number CN111424198A discloses a corrosion-resistant aluminum alloy grounding material and a method for making the same, which includes the following steps: batching, preparing raw materials of each component; smelting, adding each raw material in turn to form a molten liquid; casting the molten liquid to form a cast rod; hot extrusion, hot extruding the cast rod in an extruder to form a hot extrusion part with a desired cross section; shot peening, shot peening the hot extrusion part; oxidation, placing the shot peened hot extrusion part in a warm box for oxidation. The beneficial effect is that the generation of aluminum-copper θ phase can be suppressed, the cost can be reduced, and the problem of heavy metal ion pollution caused by copper to the environment can be avoided.

[0006] The Chinese patent with publication number CN117613576A discloses a novel anti-oxidation aluminum alloy rare earth grounding material. The novel aluminum silicon manganese alloy material is obtained mainly by adding Si and Mn, and the aluminum silicon manganese alloy material is modified by adding Cu, Fe, Mg, Ni, Zn, Ti and a small amount of Sn, Pb, Cr, Ca, V, rare earth elements, etc., so as to obtain a novel aluminum alloy rare earth grounding material with excellent conductivity, good tensile strength and elongation, excellent oxidation resistance, low manufacturing cost and environmental friendliness. The material can well meet the use in the complex and changeable environment of the grounding project, and is of great significance to ensuring the stable operation of the power system and the personal safety of personnel.

[0007] The corrosion resistance of the aluminum alloy grounding material in the prior art cannot meet the use requirements in the high-salinity and alkaline soil of the Huang irrigation area, and the mechanical properties and conductivity also need to be improved. Summary of the invention

[0008] The purpose of the present invention is to provide a corrosion-resistant aluminum alloy grounding body material and a preparation process thereof.

[0009] In order to achieve the above object, the present invention provides the following technical solutions: A preparation process of a corrosion-resistant aluminum alloy grounding material comprises the following steps: (1) Weigh the components of aluminum alloy, which include the following components in weight percentage: Re 0.01-0.5%, Ce 0.05-0.27%, Mg 0.5-1.72%, Cu 0.01-5%, Si 0.05-3%, Zr 0.01-1%, Ti 0.01-0.5%, Mn 0.01-1.5%, and the balance is Al; (2) In an argon atmosphere, the components of the aluminum alloy are mixed and then melted to form a molten liquid, which is refined by argon. After the refining, the molten liquid is cast to obtain a drawn cast rod, which is preheated and extruded in an extruder. After the extrusion is completed, the rod is cooled to form an extruded part; (3) Perform high-pressure sandblasting on the surface of the extruded part, and then clean it after the sandblasting is completed; (4) performing stress relief annealing heat treatment on the aluminum alloy after sandblasting, and air cooling to room temperature to obtain an annealed aluminum alloy part; (5) Surface anodizing: The annealed aluminum alloy parts are subjected to alkali washing and acid washing in sequence to obtain pretreated aluminum alloy parts; the pretreated aluminum alloy parts are subjected to anodizing to obtain corrosion-resistant aluminum alloy grounding body materials.

[0010] Furthermore, the aluminum alloy includes the following components in weight percentage: Re 0.33-0.42%, Ce 0.15-0.27%, Mg 1.21-1.72%, Cu 2.12-4.05%, Si 1.01-2.08%, Zr 0.14-0.23%, Ti 0.10-0.17%, Mn 0.23-0.87%, and the balance is Al.

[0011] Furthermore, the sum of the weight percentages of Re and Ce is less than the weight percentage of Mn.

[0012] Furthermore, the weight percentage ratio of Cu to Mg is (1.5~2.0):1.

[0013] Furthermore, the extrusion conditions in step (2) are: the mold is preheated to 400-420°C, the extrusion temperature is 430-460°C, the extrusion ratio is 20-30:1, and the extrusion speed is 5-10 mm / s.

[0014] Furthermore, the conditions for sandblasting are as follows: the sandblasting medium is white corundum, the particle size is 80-120 mesh, the sandblasting pressure is 0.5-0.8 MPa, the angle is 60-75°, the distance is 150-200 mm, the sandblasting time is 3-5 min, and the surface roughness Ra is controlled at 2.5-4.0 μm.

[0015] Furthermore, the conditions for the annealing heat treatment are: firstly heating to 280-290°C, keeping the temperature for 1-2 hours, and then continuing to heating to 320-330°C, keeping the temperature for 1-2 hours.

[0016] Furthermore, the specific conditions of anodization are: the electrolyte is sulfuric acid 180~200g / L, the temperature is 18~22℃, the current density is 1.5~2.0A / dm², the oxidation time is 30~50min, and the voltage is 15~20V.

[0017] Furthermore, the thickness of the anodized film is 5-10 μm.

[0018] The invention also provides a corrosion-resistant aluminum alloy grounding body material obtained by the preparation process.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention improves the corrosion resistance of the aluminum alloy by selecting the components of the aluminum alloy and satisfying that the sum of the weight percentages of Re and Ce is less than the weight percentage of Mn, and at the same time satisfies the weight percentage ratio of Cu and Mg is (1.5-2.0):1, so that the mechanical properties and electrical conductivity of the material can be improved.

[0020] 2. The stress relief annealing heat treatment method of the present invention uses a gradient heat treatment method to improve the corrosion resistance, mechanical properties and electrical conductivity of the aluminum alloy grounding material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Metallographic pictures of the aluminum alloy grounding electrode of the aluminum alloy grounding material prepared in Example 4, (a) edge, (b) core.

[0022] Figure 2 Schematic diagram of the geometric model of micro grounding grid with different grounding materials.

[0023] Figure 3 Schematic diagram of the on-site situation of micro grounding grids with different grounding materials.

[0024] Figure 4 These are pictures of the aluminum alloy grounding material before the corrosion experiment. From left to right: 1. Example 1; 2. Example 2; 3. Example 3; 4. Example 5; 5. Comparative Example 1; 6. Example 7; 7. Example 6; 8. Example 4; 9. Comparative Example 2.

[0025] Figure 5 These are pictures of aluminum alloy grounding material after corrosion experiment, from left to right: 1, Example 1; 2, Example 2; 3, Example 3; 4, Example 5; 5, Comparative Example 1; 6, Example 7; 7, Example 6; 8, Example 4; 9, Comparative Example 2.

[0026] Figure 6 Metallographic pictures of the aluminum alloy grounding electrode of the aluminum alloy grounding material prepared in Example 1, (a) edge, (b) core.

[0027] Figure 7 Metallographic pictures of the aluminum alloy grounding electrode of the aluminum alloy grounding material prepared in Example 2, (a) edge, (b) core.

[0028] Figure 8 Metallographic pictures of the aluminum alloy grounding electrode of the aluminum alloy grounding material prepared in Example 3, (a) edge, (b) core.

[0029] Fig. 9 Metallographic pictures of the aluminum alloy grounding electrode of the aluminum alloy grounding material prepared in Example 5, (a) edge, (b) core.

[0030] Fig.10 Metallographic pictures of the aluminum alloy grounding electrode of the aluminum alloy grounding material prepared in Example 6, (a) edge, (b) core.

[0031] Fig.11 Metallographic pictures of the aluminum alloy grounding electrode of the aluminum alloy grounding material prepared in Example 7, (a) edge, (b) core.

[0032] Fig.12 The following are comparison diagrams of different grounding materials before and after rust removal after accelerated corrosion test. (a) is sample 1 before rust removal; (b) is sample 1 after rust removal; (c) is sample 2 before rust removal; (d) is sample 2 after rust removal; (e) is sample 3 before rust removal; (f) is sample 3 after rust removal; (g) is sample 4 before rust removal; (h) is sample 4 after rust removal; (i) is sample 5 before rust removal; (j) is sample 5 after rust removal; (k) is sample 6 before rust removal; (l) is sample 6 after rust removal; (m) is sample 7 before rust removal; (n) is sample 7 after rust removal; (o) is sample 8 before rust removal; (p) is sample 8 after rust removal; (q) is sample 9 before rust removal; (r) is sample 9 after rust removal; (s) is sample 10 before rust removal; (t) is sample 10 after rust removal; (u) is sample 11 before rust removal; (v) is sample 11 after rust removal. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1 This embodiment provides a preparation process of a corrosion-resistant aluminum alloy grounding body material, comprising the following steps: (1) Weigh the components of an aluminum alloy, which includes the following components in weight percentage: The aluminum alloy includes the following components in weight percentage: Re 0.38%, Ce 0.20%, Mg 1.25%, Cu 2.12%, Si 1.2%, Zr 0.19%, Ti 0.12%, Mn 0.65%, and the balance is Al; (2) In an argon atmosphere, the components of the aluminum alloy were mixed and melted at 730°C to form a molten liquid, which was then refined by argon at a flow rate of 0.4 L / min for 12 min. After refining, the molten liquid was cast at a cooling water flow rate of 25 L / min and an ingot casting speed of 70 mm / min to obtain a drawn cast rod. The drawn cast rod was preheated at 460°C for 5 h and extruded in an extruder. The mold was preheated to 410°C, the extrusion temperature was 450°C, the extrusion ratio was 25:1, and the extrusion speed was 8 mm / s. After extrusion, it was water-cooled online at a water temperature of 25°C to form an extruded part. (3) Perform high-pressure sandblasting on the surface of the extruded part for surface treatment. The sandblasting medium is white corundum, the particle size is 80-120 mesh, the sandblasting pressure is 0.6 MPa, the angle is 60-75°, the distance is 170 mm, the sandblasting time is 4 min, and the surface roughness Ra is controlled at 3.0 μm. After the sandblasting is completed, the part is placed in a mixture of acetone and ethanol in a volume ratio of 1:1 for ultrasonic cleaning. (4) The aluminum alloy after sandblasting is subjected to stress relief annealing heat treatment, firstly heated to 285°C, kept at this temperature for 1.5 hours, then further heated to 325°C, kept at this temperature for 1.5 hours, furnace cooled to 200°C, and then air cooled to room temperature to obtain annealed aluminum alloy parts; (5) Surface anodization: The annealed aluminum alloy parts were immersed in 60℃, 50g / L NaOH for 3min, washed with water, and then immersed in 150mL / L HNO 3 The pretreated aluminum alloy parts were anodized for 1 minute, and the specific conditions were as follows: the electrolyte was 190 g / L sulfuric acid, the temperature was 20°C, the current density was 1.8 A / dm², the oxidation time was 40 min, the voltage was 18 V, and the film thickness was 8 μm to obtain a corrosion-resistant aluminum alloy grounding material.

[0035] Example 2 This embodiment provides a preparation process of a corrosion-resistant aluminum alloy grounding body material, comprising the following steps: (1) Weigh the components of an aluminum alloy. The aluminum alloy includes the following components in weight percentage: The aluminum alloy includes the following components in weight percentage: Re 0.33%, Ce 0.27%, Mg 1.3%, Cu 2.5%, Si 1.01%, Zr 0.14%, Ti 0.17%, Mn 0.87%, and the balance is Al.

[0036] (2) In an argon atmosphere, the components of the aluminum alloy were mixed and melted at 720°C to form a molten liquid, which was then refined by argon at a flow rate of 0.5 L / min for 10 min. After the refining, the molten liquid was cast at a cooling water flow rate of 30 L / min and an ingot casting speed of 60 mm / min to obtain a drawn cast rod. The drawn cast rod was preheated at 480°C for 4 h and extruded in an extruder. The mold was preheated to 420°C, the extrusion temperature was 430°C, the extrusion ratio was 30:1, and the extrusion speed was 7 mm / s. After the extrusion was completed, it was water-cooled online at a water temperature of 30°C to form an extruded part. (3) The surface of the extruded part is treated by high-pressure sandblasting. The sandblasting medium is white corundum, the particle size is 80-120 mesh, the sandblasting pressure is 0.5 MPa, the angle is 75°, the distance is 150 mm, the sandblasting time is 5 min, and the surface roughness Ra is controlled at 2.5 μm. After the sandblasting, the part is placed in a mixture of acetone and ethanol in a volume ratio of 1:1 for ultrasonic cleaning. (4) The aluminum alloy after sandblasting is subjected to stress relief annealing heat treatment, firstly heated to 290°C, kept at this temperature for 1 hour, then further heated to 330°C, kept at this temperature for 1 hour, furnace cooled to 200°C, and then air cooled to room temperature to obtain annealed aluminum alloy parts; (5) Surface anodization: The annealed aluminum alloy parts were immersed in 60℃, 50g / L NaOH for 3min, washed with water, and then immersed in 150mL / L HNO 3 The pretreated aluminum alloy parts were anodized for 1 minute, and the specific conditions were as follows: the electrolyte was 190 g / L sulfuric acid, the temperature was 20°C, the current density was 1.8 A / dm², the oxidation time was 40 min, the voltage was 18 V, and the film thickness was 8 μm to obtain a corrosion-resistant aluminum alloy grounding material.

[0037] Example 3 This embodiment provides a preparation process of a corrosion-resistant aluminum alloy grounding body material, comprising the following steps: (1) Weigh the components of an aluminum alloy. The aluminum alloy includes the following components in weight percentage: The aluminum alloy includes the following components in weight percentage: Re 0.42%, Ce 0.15%, Mg 1.32%, Cu 2.64%, Si 1.52%, Zr 0.17%, Ti 0.14%, Mn 0.67%, and the balance is Al.

[0038] (2) In an argon atmosphere, the components of the aluminum alloy were mixed and melted at 760°C to form a molten liquid, which was then refined by argon at a flow rate of 0.3 L / min for 15 min. After the refining, the molten liquid was cast with a cooling water flow rate of 20 L / min and an ingot casting speed of 80 mm / min to obtain a drawn cast rod. The drawn cast rod was preheated at 450°C for 6 h and extruded in an extruder. The mold was preheated to 400°C, the extrusion temperature was 460°C, the extrusion ratio was 20:1, and the extrusion speed was 10 mm / s. After the extrusion was completed, it was water-cooled online at a water temperature of 20°C to form an extruded part. (3) The surface of the extruded part is treated by high-pressure sandblasting. The sandblasting medium is white corundum, the particle size is 80-120 mesh, the sandblasting pressure is 0.8 MPa, the angle is 60°, the distance is 200 mm, the sandblasting time is 3 min, and the surface roughness Ra is controlled at 4.0 μm. After the sandblasting, the part is placed in a mixture of acetone and ethanol in a volume ratio of 1:1 for ultrasonic cleaning. (4) The aluminum alloy after sandblasting is subjected to stress relief annealing heat treatment, firstly heated to 280°C, kept at this temperature for 2 hours, then further heated to 320°C, kept at this temperature for 2 hours, furnace cooled to 200°C, and then air cooled to room temperature to obtain annealed aluminum alloy parts; (5) Surface anodization: The annealed aluminum alloy parts were immersed in 60℃, 50g / L NaOH for 3min, washed with water, and then immersed in 150mL / L HNO 3 The pretreated aluminum alloy parts were anodized for 1 minute, and the specific conditions were as follows: the electrolyte was 190 g / L sulfuric acid, the temperature was 20°C, the current density was 1.8 A / dm², the oxidation time was 40 min, the voltage was 18 V, and the film thickness was 8 μm to obtain a corrosion-resistant aluminum alloy grounding material.

[0039] Example 4 This embodiment provides a preparation process of a corrosion-resistant aluminum alloy grounding body material, comprising the following steps: (1) Weigh the components of an aluminum alloy. The aluminum alloy includes the following components in weight percentage: The aluminum alloy includes the following components in weight percentage: Re 0.42%, Ce 0.15%, Mg 1.72%, Cu 2.58%, Si 2.08%, Zr 0.14%, Ti 0.17%, Mn 0.77%, and the balance is Al.

[0040] (2) In an argon atmosphere, the components of the aluminum alloy were mixed and melted at 720°C to form a molten liquid, which was then refined by argon at a flow rate of 0.3 L / min for 10 min. After the refining, the molten liquid was cast with a cooling water flow rate of 20 L / min and an ingot casting speed of 60 mm / min to obtain a drawn cast rod. The drawn cast rod was preheated at 450°C for 4 h and extruded in an extruder. The mold was preheated to 400°C, the extrusion temperature was 430°C, the extrusion ratio was 20:1, and the extrusion speed was 5 mm / s. After the extrusion was completed, it was water-cooled online at a water temperature of 20°C to form an extruded part. (3) The surface of the extruded part is treated by high-pressure sandblasting. The sandblasting medium is white corundum, the particle size is 80-120 mesh, the sandblasting pressure is 0.8 MPa, the angle is 75°, the distance is 200 mm, the sandblasting time is 5 min, and the surface roughness Ra is controlled at 3.5 μm. After the sandblasting, it is placed in a mixture of acetone and ethanol with a volume ratio of 1:1 for ultrasonic cleaning; (4) The aluminum alloy after sandblasting is subjected to stress relief annealing heat treatment, firstly heated to 290°C, kept at this temperature for 2 hours, then further heated to 320°C, kept at this temperature for 1 hour, furnace cooled to 200°C, and then air cooled to room temperature to obtain annealed aluminum alloy parts; (5) Surface anodization: The annealed aluminum alloy parts were immersed in 60℃, 50g / L NaOH for 3min, washed with water, and then immersed in 150mL / L HNO 3 The pretreated aluminum alloy parts were anodized for 1 minute, and the specific conditions were as follows: the electrolyte was 190 g / L sulfuric acid, the temperature was 20°C, the current density was 1.8 A / dm², the oxidation time was 40 min, the voltage was 18 V, and the film thickness was 8 μm to obtain a corrosion-resistant aluminum alloy grounding material.

[0041] Example 5 The difference between this embodiment and embodiment 1 is that the aluminum alloy includes the following components in weight percentage: Re 0.2%, Ce 0.1%, Mg 1.0%, Cu 0.2%, Si 2.5%, Zr 0.5%, Ti 0.4%, Mn 0.7%, and the balance is Al.

[0042] Example 6 The difference between this embodiment and embodiment 4 is that the aluminum alloy includes the following components in weight percentage: Re 0.42%, Ce 0.15%, Mg 1.22%, Cu 3.08%, Si 2.08%, Zr 0.14%, Ti 0.17%, Mn 0.77%, and the balance is Al.

[0043] Example 7 The difference between this embodiment and embodiment 4 is that the aluminum alloy includes the following components in weight percentage: Re 0.47%, Ce 0.25%, Mg 1.72%, Cu 2.58%, Si 2.08%, Zr 0.14%, Ti 0.17%, Mn 0.52%, and the balance is Al.

[0044] Comparative Example 1 The difference between this comparative example and Example 1 is that the aluminum alloy includes the following components in weight percentage: Re 0.77%, Ce 1.55%, Mg 2.72%, Cu 1.58%, Si 1.08%, Zr 1.14%, Ti 0.67%, Mn 0.72%, and the balance is Al.

[0045] Comparative Example 2 The difference between this comparative example and Example 1 is that the aluminum alloy after sandblasting is subjected to stress relief annealing heat treatment, the temperature is raised to 300° C., kept warm for 3 hours, furnace cooled to 200° C. and then air cooled to room temperature to obtain an annealed aluminum alloy part.

[0046] Performance Testing 1. According to the requirements of GB / T 228.1-2021 “Tensile test of metallic materials - Part 1: Room temperature test method”, samples of the aluminum alloy grounding materials prepared in Examples 1-7 and Comparative Examples 1-2 were subjected to room temperature tensile tests on a CMT5305 electronic universal testing machine.

[0047] 2. According to the requirements of GB / T 3048.4-2007 "Electrical Performance Test Methods for Wires and Cables Part 4: DC Resistance Test for Conductors", a DC resistance test was performed on the aluminum alloy grounding bodies of Examples 1-7 and Comparative Examples 1-2 on a QJ36B-2 digital bridge. The length of the grounding bodies used in the test was 1 m, and the experimental temperature was 20°C.

[0048] 3. Corrosion resistance experiment: For the soil corrosion simulation solution test, 600g of analytically pure sodium chloride, 400g of sodium sulfate, 400g of sodium bicarbonate, 400g of calcium chloride, 120g of magnesium chloride and deionized distilled water were used to prepare 40L of soil corrosion simulation solution, in which sodium chloride, calcium chloride and magnesium chloride were used to control the content of chloride ions, sodium sulfate was used to control the content of sulfate ions, and sodium bicarbonate was used to control the content of carbonate ions. At the same time, the pH value of the solution was adjusted to about 8.5 by sodium hydroxide, so as to obtain a simulated solution close to the soil corrosion characteristics of the Huang irrigation area. During the entire test, a heating rod was used to heat the solution, and the temperature was controlled at 50±5℃, and an oxygen pump was used to oxygenate the solution to intensify the corrosion process of the grounding material. At the same time, in order to avoid changes in the concentration of the corrosive solution caused by water evaporation, distilled water was regularly added to the solution during the test to maintain the volume of the soil corrosion simulation solution at about 40L. The cross-sectional dimensions of the samples were all 50 mm×5 mm, the test period was 100 days, and the corrosion conditions of the aluminum alloy grounding materials of Examples 1-7 and Comparative Examples 1-2 were recorded.

[0049] All the pictures of the samples before and after corrosion are shown in Figure 4-5 , the results are shown in Table 1.

[0050] Table 1 Performance test results

[0051] It can be seen from Table 1 that the corrosion-resistant aluminum alloy grounding body materials of Examples 1-7 have high mechanical properties and electrical conductivity, especially Example 4 has better comprehensive performance and its corrosion resistance is the best.

[0052] It can be found from Examples 5-7 that there is a synergistic effect between the components of the aluminum alloy. When the sum of the weight percentages of Re and Ce is less than the weight percentage of Mn, the corrosion resistance of the aluminum alloy can be improved. At the same time, when the weight percentage ratio of Cu and Mg is (1.5~2.0):1, the mechanical properties and conductivity of the material can be improved.

[0053] In comparative example 1, the composition ratio of the aluminum alloy grounding material is changed, the mechanical properties are reduced, and the resistance value is increased. In comparative example 2, the stress relief annealing heat treatment method does not perform gradient heat treatment, and the mechanical properties and conductivity of the aluminum alloy grounding material are deteriorated.

[0054] 2. Accelerated soil corrosion test: Taking into account the physical and chemical properties of the soil in the Huang irrigation area, 230 kg of the original soil in the Huang irrigation area (pH = 8.89, weak alkalinity) was taken, crushed (200 mesh), dried, and evenly stirred with 400 g of sodium chloride, 300 g of sodium sulfate, 300 g of sodium bicarbonate, 100 g of magnesium chloride, 100 g of calcium chloride and 5 L of distilled water to make accelerated corrosion soil, placed in a plastic box, and the soil pH was adjusted to about 9.0 using sodium hydroxide. Keep the soil temperature: 20 ± 5 ° C, air temperature: 20 ± 5 ° C. The grounding material of Example 4 and the currently commercially available grounding material are placed horizontally in the soil accelerated corrosion box, and 2 L of distilled water is added to the box every 15 days to ensure the relative stability of the soil water content. The size of all grounding material samples for the soil accelerated corrosion test is 50 mm × 50 mm × 5 mm. In order to ensure the accuracy and stability of the accelerated corrosion test and reduce the test error, 3 parallel samples are taken for each grounding material accelerated test, and parallel sample tests are carried out.

[0055] In order to more realistically reflect the corrosion of grounding materials, the samples were buried 15 cm away from the soil surface, and the spacing between the samples was not less than 10 cm. The soil accelerated corrosion test cycle was 65 days. After 65 days, the grounding material corrosion samples were taken out, and the grounding materials with corrosion products were derusted according to GB / T 16545-2015 "Removal of Corrosion Products on Corrosion Test Specimens of Metals and Alloys". After derusting, the samples were placed in an oven for 24 hours and weighed using an electronic balance with an accuracy of one ten-thousandth. The corrosion rates of different grounding materials in the soil accelerated corrosion box were calculated based on the initial weight before sampling and the surface area of ​​the samples.

[0056] The results are shown in Table 2 and Fig.12 .

[0057] Table 2 Results of soil accelerated corrosion tests on different grounding materials

[0058] Specific test data are shown in Table 2 and Fig.12. The results show that the grounding materials used in the test have different degrees of corrosion. The carbon steel and galvanized steel samples are corroded more seriously, the surface is dark brown, and a layer of sand with uneven thickness is attached to the local area. The galvanized layer on the surface of the galvanized steel has completely disappeared, and the protective effect on the substrate has been lost. Therefore, the corrosion rate of galvanized steel and carbon steel is not much different. Most areas of the pure copper sample are brown after corrosion, and spotty green corrosion products can be seen in local areas. There are a large number of tiny pitting corrosion pits on the surface, and the overall corrosion degree is relatively light. The aluminum-copper-titanium sample without surface treatment has a small number of corrosion pits due to stress corrosion, and the material in the pit has a slight peeling phenomenon. The diameter of some corrosion pits can reach 2mm, and the corrosion product is white powder. The aluminum alloy sample with only sandblasting and heat treatment on the surface has a corrosion rate similar to that of the sample without surface treatment, but there is no obvious pitting corrosion pit and material peeling phenomenon on the surface. The overall corrosion is relatively uniform, indicating that the sandblasting and heat treatment process can effectively improve the stress state inside the aluminum alloy material, greatly reduce the tendency of stress corrosion, and avoid the occurrence of large pitting corrosion pits. The aluminum-copper-titanium sample with only anodized surface has a lighter degree of corrosion, no obvious pitting corrosion pits are found, and the corrosion rate is only half of that of the sample without anodizing treatment, and is close to the corrosion rate of pure copper, indicating that the anodized film can effectively isolate the contact of external air, moisture and corrosive media, greatly improving the corrosion resistance of aluminum alloy. The corrosion resistance of the aluminum alloy grounding body material prepared by Example 4, which is sandblasted, heat treated and anodized at the same time, is the best among all aluminum alloy grounding materials. Its corrosion rate is 1 / 85 and 1 / 20 of the commonly used grounding materials galvanized steel and pure copper, respectively, and is close to the corrosion resistance of stainless steel, which can effectively avoid the problem of premature failure of the grounding body due to corrosion.

[0059] 3. On-site grounding resistance test of high-performance corrosion-resistant aluminum alloy micro grounding grid In order to study the corrosion resistance and grounding performance of grounding materials with different materials and surface treatment states in a real service environment, the present invention uses a welding method to process Example 4 with a specification of 50mm×5mm and commercially available grounding materials into a 1.5m×1.5m micro grounding grid, and at the same time ensures that the vertical down conductor length of the grounding grid is 1m. Figure 2 and 3 To avoid mutual influence between micro grounding grids made of different grounding materials, the spacing between different grounding grids is not less than 15m. At the same time, the grounding grid is 0.8m away from the ground, and the grounding resistance is regularly tested using the three-electrode method. The test data are shown in Table 3.

[0060] Table 3 Field test results of micro grounding grids with different grounding materials

[0061] The test results show that the grounding resistance values ​​of micro grounding grids made of different grounding materials are all less than 2Ω, and the values ​​are not much different. The fluctuation of grounding resistance values ​​of different grounding materials should be caused by the instrument's own error and test error. In addition, sandblasting effectively improves the surface roughness of the grounding body and increases the contact area between the grounding body and the soil to a certain extent, thus promoting the grounding performance of the grounding grid.

[0062] The soil in the Huang irrigation area contains a large amount of chloride and sulfate, which will produce a large number of ions after dissolution, which can serve as the main carrier of current conduction in the soil. The higher the salt content, the lower the soil resistivity. At the same time, the soil has a high water content. As a good conductive medium, water can provide a continuous conductive path for the migration of ions, improve soil conductivity, and cause the soil resistivity to decrease. Therefore, in the Huang irrigation area where the soil resistivity is low, the corrosion resistance should be given priority when selecting the grounding material for power transmission and transformation equipment.

[0063] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A preparation process of a corrosion-resistant aluminum alloy grounding material, characterized in that: The following steps are involved: (1) Weigh the components of aluminum alloy, which include the following components in weight percentage: Re 0.01-0.5%, Ce 0.05-0.27%, Mg 0.5-1.72%, Cu 0.01-5%, Si 0.05-3%, Zr 0.01-1%, Ti 0.01-0.5%, Mn 0.01-1.5%, and the balance is Al; (2) In an argon atmosphere, the components of the aluminum alloy are mixed and then melted to form a molten liquid, which is refined by argon gas. After the refining is completed, the aluminum alloy is cast to obtain a drawn cast rod, and the drawn cast rod is extruded in an extruder to form an extruded part; (3) Perform high-pressure sandblasting surface treatment on the surface of the extruded part; (4) performing stress relief annealing heat treatment on the aluminum alloy after sandblasting, and air cooling to room temperature to obtain an annealed aluminum alloy part; (5) Surface anodizing: The annealed aluminum alloy parts are anodized to obtain corrosion-resistant aluminum alloy grounding material.

2. The preparation process of the corrosion-resistant aluminum alloy grounding material according to claim 1 is characterized in that: The aluminum alloy includes the following components in weight percentage: Re 0.33-0.42%, Ce 0.15-0.27%, Mg 1.21-1.72%, Cu 2.12-4.05%, Si 1.01-2.08%, Zr 0.14-0.23%, Ti 0.10-0.17%, Mn 0.23-0.87%, and the balance is Al.

3. The preparation process of the corrosion-resistant aluminum alloy grounding material according to claim 2 is characterized in that: The sum of the weight percentages of Re and Ce is less than the weight percentage of Mn.

4. The preparation process of the corrosion-resistant aluminum alloy grounding material according to claim 3 is characterized in that: The weight percentage ratio of Cu and Mg is (1.5~2.0):

1.

5. The preparation process of the corrosion-resistant aluminum alloy grounding material according to claim 1, characterized in that: The extrusion conditions in step (2) are as follows: the mold is preheated to 400-420° C., the extrusion temperature is 430-460° C., the extrusion ratio is 20-30:1, and the extrusion speed is 5-10 mm / s.

6. The preparation process of the corrosion-resistant aluminum alloy grounding material according to claim 1, characterized in that: The conditions for sandblasting are as follows: the sandblasting medium is white corundum, the particle size is 80~120 mesh, the sandblasting pressure is 0.5~0.8MPa, the angle is 60~75°, the distance is 150~200mm, the sandblasting time is 3~5min, and the surface roughness Ra is controlled at 2.5~4.0μm.

7. The preparation process of the corrosion-resistant aluminum alloy grounding material according to claim 1, characterized in that: The conditions for annealing heat treatment are: first raise the temperature to 280~290℃, keep it warm for 1~2h, then continue to raise the temperature to 320~330℃, keep it warm for 1~2h.

8. The preparation process of the corrosion-resistant aluminum alloy grounding material according to claim 1, characterized in that: The specific conditions of anodization are: the electrolyte is sulfuric acid 180~200g / L, the temperature is 18~22℃, the current density is 1.5~2.0A / dm², the oxidation time is 30~50min, and the voltage is 15~20V.

9. The preparation process of the corrosion-resistant aluminum alloy grounding material according to claim 8, characterized in that: The thickness of the anodized film is 5~10μm.

10. A corrosion-resistant aluminum alloy grounding material obtained by the preparation process described in any one of claims 1 to 9.

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