Cold spraying powder for corrosion prevention and repair of steel structure surface as well as preparation method and application of cold spraying powder

Abstract

The invention discloses cold spraying powder for corrosion prevention and repair of the surface of a steel structure as well as a preparation method and application of the cold spraying powder. The cold spraying powder is prepared from the following components in percentage by weight: 65 to 75 percent of AlZn alloy, 15 to 20 percent of SiC and 10 to 15 percent of FeCoCrNiMo high-entropy alloy. The cold spraying powder is good in protection effect, small in environmental influence, wide in application range, simple in preparation process and convenient to implement, and can be used for on-site repair of power equipment.

Description

Technical Field

[0001] The invention relates to the technical field of steel structure surface treatment, and in particular to a cold spraying powder for anti-corrosion and repair of steel structure surfaces, a preparation method and application thereof. Background Art

[0002] With the rapid development of the national power grid, my country's power grid system is at the forefront of the world in terms of scale, lines and coverage. Among them, the transmission towers, substation structures and other equipment used for power transmission are exposed to various natural environments for a long time, and the steel components in the equipment will suffer from varying degrees of corrosion damage, and their performance will drop significantly, seriously affecting the efficiency and safety of the power grid.

[0003] As a new type of surface treatment technology, cold spraying technology is an important means of anti-corrosion and repair of power transmission and transformation steel structures with its advantages of low-temperature treatment, dense coating, environmental protection and high efficiency. However, traditional cold spraying powder materials are mostly single metals or alloys, and their corrosion resistance and mechanical properties are still insufficient under complex and changeable environmental conditions. For example, Chinese literature, DOI: 10.27206 / d.cnki.ggsgu.2021.001528, the theme is the study of the corrosion resistance of Zn-Al composite coatings with different Al contents sprayed by low pressure cold spraying. The electrochemical tests and hardness tests were carried out on Zn-Al composite coatings with different Al contents. The results showed that after immersion in 3.5wt.% NaCl solution for 1h, the self-corrosion potential of the Zn-Al composite coating was -1.3~-1.5V, and the self-corrosion current was 1.2~3.4×10 -4 A / cm 2 ; The hardness of Zn-Al composite coating is 66-76HV 0.25 For power equipment serving in coastal, hot and humid areas, heavy industrial pollution and other heavily corrosive environments, existing cold spray coatings cannot meet their protection needs, so it is necessary to further improve the corrosion resistance and mechanical properties of cold spray coatings. Summary of the invention

[0004] In order to overcome the technical problems of insufficient corrosion resistance and mechanical properties and poor protective effect of cold spray coatings in the prior art, the present invention provides a cold spray powder for anti-corrosion and repair of steel structure surfaces, a preparation method and application thereof, and adopts cold spray powder containing AlZn alloy (i.e., aluminum-zinc alloy), SiC and FeCoCrNiMo high entropy alloy to repair the corroded and damaged parts of the steel structure surface to form an anti-corrosion and anti-wear layer. The cold spray powder has good protective effect, is less affected by the environment and has a wide range of applications.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The invention provides a cold spraying powder for anticorrosion and repairing of steel structure surface, comprising the following components: 65-75wt.% of AlZn alloy, 15-20wt.% of SiC and 10-15wt.% of FeCoCrNiMo high entropy alloy.

[0006] The present invention prepares cold spray powder by mixing AlZn alloy, SiC and FeCoCrNiMo high entropy alloy in a specific proportion, while ensuring that its basic performance meets the normal use requirements, the corrosion and wear resistance of the coating is greatly improved. Specifically, aluminum has a strong passivation ability, and can form a dense oxide film on the surface of the steel structure. This oxide film has good barrier properties and can prevent external corrosive media such as oxygen, moisture and corrosive ions from directly contacting the steel structure, thereby playing an anti-corrosion role. When zinc contacts aluminum and is exposed to a corrosive environment, zinc will be corroded first, thereby forming a protective layer composed of zinc corrosion products on the contact surface. This protective layer can slow down or prevent the corrosive medium from eroding another metal, thereby playing a protective role. The synergistic effect of SiC and zinc in AlZn alloy can significantly improve the corrosion resistance of the coating; since the surface of steel structures in the natural environment is often subjected to friction and impact, the high hardness and high wear resistance of SiC significantly improve the hardness and scratch resistance of the coating. At the same time, SiC particles can fill the microscopic pores and defects in the coating, making the coating denser and further preventing the penetration of corrosive media; FeCoCrNiMo high entropy alloy has excellent corrosion resistance and high temperature stability. CrNiMo in the high entropy alloy will form a dense oxide layer, which hinders the penetration of corrosive media and enhances the corrosion resistance of the coating. In addition, each atom in the high entropy alloy occupies a different lattice to form a lattice distortion, thereby pinning the dislocation, hindering movement, and producing solid solution strengthening, thereby increasing the hardness and wear resistance of the coating.

[0007] AlZn alloy, SiC and FeCoCrNiMo high entropy alloy have different phase compositions: AlZn alloy is mostly α phase, and aluminum-based solid solution dissolves part of zinc; SiC has a variety of polymorphs, such as cubic 3C-SiC and hexagonal 4H-SiC and 6H-SiC; high entropy alloys are mostly FCC face-centered cubic structures. The three are mixed to form a multi-phase, which forms multiple protective barriers in the coating, increasing the difficulty of corrosive medium penetration. Even if a certain phase is corroded to a certain extent under specific corrosion conditions, other phases can continue to play a protective role, thereby improving the overall corrosion resistance of the coating. At the same time, there are a large number of phase interfaces in the coating composed of multi-phases. These phase interfaces have high interface energy, and the atomic arrangement at the phase interface is discontinuous. Dislocations need to consume more energy when crossing the phase interface, thereby increasing the difficulty of dislocation movement. The interface between different phases can also promote the interaction of dislocations, which can further increase the resistance to dislocation movement and improve the hardness and wear resistance of the coating.

[0008] In order to obtain the best coating performance, the content of each component needs to be precisely controlled. If the AlZn alloy content is too high, the brittleness will increase and the impact resistance of the coating will decrease; if the content is too low, the corrosion resistance of the coating will be significantly reduced. If the SiC content is too high, the coating will be too hard and brittle, reducing the toughness and impact resistance of the coating. At the same time, too much SiC will reduce the interface bonding strength with the metal matrix, forming defects such as pores and cracks; if the content is too low, the wear resistance of the coating will be significantly reduced, and it will not be able to effectively resist mechanical damage such as wear and scratches. The particle size of FeCoCrNiMo high entropy alloy is relatively large, and if the content is too high, the powder deposition rate will be reduced; if the content is too low, the mechanical and corrosion resistance of the coating will decrease.

[0009] Through the synergistic effect and content optimization of the above ingredients, the cold spray powder can form a coating on the surface of the steel structure that has corrosion resistance, wear resistance and good mechanical properties, providing effective protection for the steel structure and is suitable for a variety of harsh working environments.

[0010] Furthermore, the AlZn alloy includes 75-85 wt. % Al and 15-25 wt. % Zn.

[0011] In AlZn alloys, too high aluminum content will change the composition of the oxide film on the surface of the alloy, causing the oxide film to be less dense, thereby reducing the corrosion resistance of the alloy. At the same time, too high aluminum content will increase the brittleness of the alloy; if the zinc content is too high, the strength of the alloy will increase but the toughness will decrease. During the solidification process of the alloy, zinc will solidify and shrink first, causing thermal stress inside the alloy, which in turn increases the tendency to thermal cracking.

[0012] Furthermore, the FeCoCrNiMo high entropy alloy has an atomic ratio of Fe:Co:Cr:Ni:Mo of 1:1:1:1:0.2-1.

[0013] Molybdenum can play a role of solid solution strengthening in high-entropy alloys, that is, it increases the resistance to dislocation movement by integrating into the crystal lattice, thereby improving the strength of the alloy. When the molybdenum content is too low, this strengthening effect is weakened, resulting in a decrease in the strength of the alloy, and it also makes the alloy more susceptible to corrosion; when the molybdenum content is too high, it will lead to increased brittleness of the alloy. This is because too much molybdenum will form a brittle phase or cause the lattice distortion to increase, thereby reducing the toughness and plasticity of the alloy.

[0014] The present invention also provides a method for preparing cold spray powder for anti-corrosion and repair of steel structure surface, comprising the following steps: (1) preparing raw materials in proportion, mixing and drying; (2) grinding the dried raw material to obtain an intermediate powder; (3) screening the intermediate powder; (4) The sieved intermediate powder is classified to obtain cold spray powder.

[0015] The mixed raw materials are dried, and then the powder is refined by grinding and the raw materials are further mixed evenly. Powders with too large and too small particle sizes are removed by screening and grading to improve the coating quality.

[0016] Furthermore, in step (1), the drying temperature is 80-105° C. and the drying time is 2-4 h.

[0017] Furthermore, in step (2), grinding is performed using a ball mill, and the diameters of the balls in the ball mill are 10 mm and 5 mm, with a ratio of 1:4.

[0018] Furthermore, in step (2), the ball mill speed is 250-300 r / min, and after each ball milling for 20-40 minutes, it is paused for 10-15 minutes, and the total ball milling time is 2-4 hours.

[0019] Since SiC is a ceramic phase, its physical properties such as density and hardness are quite different from those of the metal matrix (AlZn and FeCoCrNiMo), and it is difficult to evenly disperse SiC in the metal matrix during the mixing process. The present invention adopts the ball milling process to break the agglomeration between powder particles through mechanical force, thereby achieving even dispersion of SiC in the metal matrix.

[0020] Furthermore, in step (2), the material of the ball milling jar used for ball milling is one of 304 stainless steel, 316L stainless steel, tungsten carbide, and zirconium oxide; the material of the ball milling ball is one of steel ball, ceramic, and high chromium cast iron.

[0021] Furthermore, in step (3), a vibrating screening machine is used for screening, the apertures of the screening mesh are set to 50 μm and 25 μm respectively, the vibration frequency is 65 Hz-70 Hz, and the screening time is 15-30 min.

[0022] The average particle size of the cold spray powder is controlled at 25-50μm to improve the spraying accuracy and enable the cold spray powder to be closely combined with the surface of the steel structure.

[0023] Furthermore, in step (4), the classification is performed using an airflow classifier, the airflow classifier has a rotation speed of 2000-3000 r / min, an airflow velocity of 10-20 m / s, and a feed rate of 5-15 kg / h.

[0024] Gradually remove powder with too small particle size. In the cold spray process, powder particles need to reach a certain critical speed to effectively deposit on the substrate and form a solid coating. Powder with too small particle size is difficult to reach this critical speed due to its small mass and inertia, thus reducing the deposition efficiency. Therefore, it is necessary to remove powder with too small particle size to improve the deposition efficiency.

[0025] The present invention also provides an application of cold spray powder for anti-corrosion repair of steel structure surface for on-site repair of power equipment, comprising the following steps: a) Determine the on-site operation area, set up warning signs, wear safety protection equipment, and find repair points; b) Determine the repair point and pre-treat the surface of the steel structure of the power equipment to be sprayed, including cleaning and preheating; c) A low-pressure cold spraying process is used to spray cold spray powder on the pretreated steel structure surface; in the low-pressure cold spraying process, the process gas is air, the gas pressure is 0.8-1.2Mpa, the gas temperature is 300-500°C, the spraying deposition angle is 70-90°, the spraying distance is 10-20mm, and the spraying forward speed is 2-6mm / s.

[0026] Due to natural factors such as wind encountered during on-site operations, especially equipment such as power transmission towers will be corroded at high altitudes, requiring personnel to work at high altitudes, which affects the spraying of powder. The present invention adopts the above-mentioned low-pressure cold spraying process to overcome environmental influences, so that the cold sprayed powder can be smoothly deposited on the substrate to obtain a high-quality coating; in addition, the on-site repair method is easy to operate, adopts a low-pressure cold spraying process, does not involve high-pressure dangerous gases, etc., has high safety, and the splashed powder generated during the spraying process can be recovered without causing environmental pollution.

[0027] Furthermore, in step b), the preheating temperature is 300-500° C. and the preheating time is 60-120 seconds.

[0028] Furthermore, in step c), the equipment used in the low-pressure cold spraying process includes an air compressor, a cold air dryer and a spraying device.

[0029] The beneficial effects of the present invention are: (1) Good protective effect: AlZn alloy can improve the corrosion resistance of the coating, silicon carbide can improve the mechanical properties of the coating, and FeCoCrNiMo high entropy alloy can improve the corrosion resistance and mechanical properties of the coating. These three components have different phase compositions and form a multi-phase after mixing. The multi-phase forms multiple protective barriers in the coating, which can effectively resist various corrosive media, including acids, alkalis, salts, etc. At the same time, there are a large number of phase interfaces in the coating composed of multi-phases, which increases the difficulty of dislocation movement. The interfaces between different phases can also promote the interaction of dislocations, which can further increase the resistance to dislocation movement and improve the hardness and wear resistance of the coating. The cold spray powder can form a coating with corrosion resistance, wear resistance and good mechanical properties on the surface of the steel structure, providing effective protection for the steel structure and extending its service life; (2) Small impact on the environment and wide application range: The cold spray powder has a complex phase structure, and the solid solution strengthening effect of the FeCoCrNiMo high entropy alloy component enables the coating to maintain good performance in harsh environments and is less affected by the environment, thus broadening the application range of the coating; (3) The preparation process is simple and easy to implement: The cold spray powder preparation process of the present invention has few steps, simple process steps, simple equipment, and the cold spray technology is used to prepare the anti-corrosion and anti-wear coating, which can be operated on-site to achieve in-situ repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a 200-fold BSE diagram of the cold spray powder prepared in Example 1 of the present invention; Figure 2 This is a 500-fold SE image of the cold spray powder prepared in Example 1 of the present invention; Figure 3 This is the elemental analysis diagram of the cold spray powder obtained in Example 1 of the present invention; Figure 4 This is a 500-fold SE image of the cold spray powder prepared in Example 2 of the present invention; Figure 5 This is the elemental analysis diagram of the cold spray powder prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0031] The present invention is described below by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0032] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0033] In the present invention, the proportions of each component not otherwise specified are all in mass percentage. The high entropy alloy described in the present invention is an alloy formed by mixing five or more main elements in an equiatomic ratio or a nearly equiatomic ratio. The AlZn alloy, SiC powder and FeCoCrNiMo high entropy alloy in the present invention were purchased from Tianjin Hi-Tech New Materials Technology Co., Ltd. In the preparation method described in the present invention, the equipment used is not limited to a drying oven, a ball mill, a vibrating screen and an airflow classifier, but also includes other equipment that can achieve drying, grinding, screening and grading effects. In the application described in the present invention, the equipment used is not limited to an air compressor, a cold air dryer and a spraying equipment, but also includes other equipment that can achieve gas compression, drying and spraying effects.

[0034] Example 1 A cold spray powder for anti-corrosion and repair of steel structure surface comprises the following components: 70wt% AlZn alloy powder, 15wt% SiC powder, and 15wt% FeCoCrNiMo high entropy alloy powder, wherein the AlZn alloy comprises 75wt.% Al and 25wt.% Zn, and the FeCoCrNiMo high entropy alloy has an atomic ratio of Fe:Co:Cr:Ni:Mo of 1:1:1:1:0.5.

[0035] The cold sprayed powder was subjected to electron microscope scanning to obtain Figure 1 and Figure 2 , Figure 1 It can be seen that the ingredients are mixed evenly. Figure 2 It can be seen that the components are mixed evenly and the powder particle size does not exceed 50 μm. The prepared cold spray powder is subjected to EDS analysis (i.e., energy dispersive X-ray spectroscopy analysis) to obtain Figure 3 , it can be seen that the peak value of each element is basically consistent with the proportion of raw material powder.

[0036] Example 2 A cold spray powder for anti-corrosion and repair of steel structure surface comprises the following components: 65wt% AlZn alloy powder, 20wt% SiC powder, and 15wt% FeCoCrNiMo high entropy alloy powder, wherein the AlZn alloy comprises 80wt.% Al and 20wt.% Zn, and the FeCoCrNiMo high entropy alloy has an atomic ratio of Fe:Co:Cr:Ni:Mo of 1:1:1:1:0.2.

[0037] The cold sprayed powder was subjected to electron microscope scanning to obtain Figure 4 It can be seen that the components are mixed evenly and the powder particle size does not exceed 50μm. The cold spray powder obtained was analyzed by EDS. Figure 5 , it can be seen that the peak value of each element is basically consistent with the proportion of raw material powder.

[0038] Example 3 A cold spray powder for anti-corrosion and repair of steel structure surface comprises the following components: 75wt% AlZn alloy powder, 15wt% SiC powder, and 10wt% FeCoCrNiMo high entropy alloy powder, wherein the AlZn alloy comprises 85wt.% Al and 15wt.% Zn, and the FeCoCrNiMo high entropy alloy has an atomic ratio of Fe:Co:Cr:Ni:Mo of 1:1:1:1:1.

[0039] Example 4 A method for preparing cold spray powder for anti-corrosion and repair of steel structure surface comprises the following steps: (1) The AlZn alloy and the FeCoCrNiMo high entropy alloy are ground into powders respectively, and the three raw materials in powder form are weighed and mixed according to proportion.

[0040] (2) Check the vacuum drying oven to ensure that it is clean, free of debris, and has normal sealing and vacuum. Spread the above raw material powder evenly on a stainless steel tray without piling it too thickly. Turn on the power of the vacuum drying oven and set the temperature to 90°C for 3 hours. After placing the sample, close the door and start the vacuum pump to extract air. After reaching the vacuum degree, turn on the heating device. After the drying is completed, wait for the temperature to drop to room temperature, turn off the vacuum pump and take out the powder.

[0041] (3) Check the status of the ball mill, select a 304 stainless steel ball mill jar, clean it, put the dried powder into the jar, and then add 10 mm and 5 mm steel balls in the jar at a ratio of 1:4. Set the ball mill speed to 280 r / min and the total ball milling time to 3 h. Continue ball milling for 30 min, then stop and cool for 12 min, start the ball mill, and remove the ball mill jar after completion.

[0042] (4) Start the vibration screening machine and preheat it for a period of time to ensure that the equipment is stable. Slowly and evenly pour the ball-milled powder into the feed port of the vibration screening machine to avoid clogging caused by pouring too much at one time. The vibration frequency is set to 65 Hz, and the sieve mesh aperture is set to 50 μm and 25 μm respectively. The 50 μm sieve removes powder with too large a particle size, and the 25 μm sieve removes powder with too small a particle size. The total screening time is set to 20 minutes. After the screening is completed, take out the powder in the 25 μm sieve.

[0043] (5) Start the airflow classifier and wait until it reaches a stable operating state. Feed the screened powder evenly into the airflow classifier through a feeding device. Set the rotation speed at 2500 r / min, the airflow velocity at 15 m / s, and the feeding rate at 10 kg / h to ensure the stability and accuracy of the classification process. Take the bottom powder to obtain the cold spray powder.

[0044] Example 5 A method for preparing cold spray powder for anti-corrosion and repair of steel structure surface comprises the following steps: (1) Grind the AlZn alloy and FeCoCrNiMo high entropy alloy into powders respectively, weigh the three raw materials in powder form according to the proportion and mix them.

[0045] (2) Check the vacuum drying oven to ensure that it is clean, free of debris, and has normal sealing and vacuum. Spread the above raw material powder evenly on the stainless steel tray without piling it too thickly. Turn on the power of the vacuum drying oven, set the temperature to 90°C and the drying time to 3 hours. After placing the sample, close the oven door and start the vacuum pump to extract air. After reaching the vacuum degree, turn on the heating device. After the drying is completed, wait for the temperature to drop to room temperature, turn off the vacuum pump and take out the powder.

[0046] (3) Check the status of the ball mill, select a 304 stainless steel ball mill jar, clean it, put the dried powder into the jar, and then add 10 mm and 5 mm steel balls in the jar at a ratio of 1:4. Set the ball mill speed to 280 r / min and the total ball milling time to 3 h. Continue ball milling for 30 min, then stop and cool for 12 min, start the ball mill, and remove the ball mill jar after completion.

[0047] (4) Start the vibration screening machine and preheat it for a period of time to ensure that the equipment is stable. Slowly and evenly pour the ball-milled powder into the feed port of the vibration screening machine to avoid clogging caused by pouring too much at one time. The vibration frequency is set to 65 Hz, and the sieve mesh aperture is set to 50 μm and 25 μm respectively. The 50 μm sieve removes powder with too large a particle size, and the 25 μm sieve removes powder with too small a particle size. The total screening time is set to 20 minutes. After the screening is completed, take out the powder in the 25 μm sieve.

[0048] (5) Start the airflow classifier and wait until it reaches a stable operating state. Feed the screened powder evenly into the airflow classifier through a feeding device. Set the rotation speed at 2500 r / min, the airflow velocity at 15 m / s, and the feeding rate at 10 kg / h to ensure the stability and accuracy of the classification process. Take the bottom powder to obtain the cold spray powder.

[0049] Example 6 A method for preparing cold spray powder for anti-corrosion and repair of steel structure surface comprises the following steps: (1) The AlZn alloy and the FeCoCrNiMo high entropy alloy are ground into powders respectively, and the three raw materials in powder form are weighed and mixed according to proportion. (2) Check the vacuum drying oven to ensure that it is clean, free of debris, and has normal sealing and vacuum. Spread the above raw material powder evenly on a stainless steel tray without piling it too thickly. Turn on the power of the vacuum drying oven and set the temperature to 90°C for 3 hours. After placing the sample, close the door and start the vacuum pump to extract air. After reaching the vacuum degree, turn on the heating device. After the drying is completed, wait for the temperature to drop to room temperature, turn off the vacuum pump and take out the powder.

[0050] (3) Check the status of the ball mill, select a 304 stainless steel ball mill jar, clean it, put the dried powder into the jar, and then add 10 mm and 5 mm steel balls in the jar at a ratio of 1:4. Set the ball mill speed to 280 r / min and the total ball milling time to 3 h. Continue ball milling for 30 min, then stop and cool for 12 min, start the ball mill, and remove the ball mill jar after completion.

[0051] (4) Start the vibration screening machine and preheat it for a period of time to ensure that the equipment is stable. Slowly and evenly pour the ball-milled powder into the feed port of the vibration screening machine to avoid clogging caused by pouring too much at one time. The vibration frequency is set to 65 Hz, and the sieve mesh aperture is set to 50 μm and 25 μm respectively. The 50 μm sieve removes powder with too large a particle size, and the 25 μm sieve removes powder with too small a particle size. The total screening time is set to 20 minutes. After the screening is completed, take out the powder in the 25 μm sieve.

[0052] (5) Start the airflow classifier and wait until it reaches a stable operating state. Feed the screened powder evenly into the airflow classifier through a feeding device. Set the rotation speed at 2500 r / min, the airflow velocity at 15 m / s, and the feeding rate at 10 kg / h to ensure the stability and accuracy of the classification process. Take the bottom powder to obtain the cold spray powder.

[0053] Example 7 A method for preparing cold spray powder for anti-corrosion and repair of steel structure surface comprises the following steps: (1) The AlZn alloy and the FeCoCrNiMo high entropy alloy are ground into powders respectively, and the three raw materials in powder form are weighed and mixed according to proportion. (2) Check the vacuum drying oven to ensure that it is clean, free of debris, and has normal sealing and vacuum. Spread the above raw material powder evenly on the stainless steel tray without piling it too thickly. Turn on the power of the vacuum drying oven, set the temperature to 105°C and the drying time to 2 hours. After placing the sample, close the door and start the vacuum pump to extract air. After reaching the vacuum degree, turn on the heating device. After the drying is completed, wait for the temperature to drop to room temperature, turn off the vacuum pump and take out the powder.

[0054] (3) Check the status of the ball mill, select a 304 stainless steel ball mill jar, clean it, put the dried powder into the jar, and then add 10 mm and 5 mm steel balls in the jar at a ratio of 1:4. Set the ball mill speed to 280 r / min and the total ball milling time to 3 h. Continue ball milling for 30 min, then stop and cool for 12 min, start the ball mill, and remove the ball mill jar after completion.

[0055] (4) Start the vibration screening machine and preheat it for a period of time to ensure that the equipment is stable. Slowly and evenly pour the ball-milled powder into the feed port of the vibration screening machine to avoid clogging caused by pouring too much at one time. The vibration frequency is set to 65 Hz, and the sieve mesh aperture is set to 50 μm and 25 μm respectively. The 50 μm sieve removes powder with too large a particle size, and the 25 μm sieve removes powder with too small a particle size. The total screening time is set to 20 minutes. After the screening is completed, take out the powder in the 25 μm sieve.

[0056] (5) Start the airflow classifier and wait until it reaches a stable operating state. Feed the screened powder evenly into the airflow classifier through a feeding device. Set the rotation speed at 2500 r / min, the airflow velocity at 15 m / s, and the feeding rate at 10 kg / h to ensure the stability and accuracy of the classification process. Take the bottom powder to obtain the cold spray powder.

[0057] Example 8 A method for preparing cold spray powder for anti-corrosion and repair of steel structure surface comprises the following steps: (1) The AlZn alloy and the FeCoCrNiMo high entropy alloy are ground into powders respectively, and the three raw materials in powder form are weighed and mixed according to proportion.

[0058] (2) Check the vacuum drying oven to ensure that it is clean, free of debris, and has normal sealing and vacuum. Spread the above raw material powder evenly on the stainless steel tray without piling it too thickly. Turn on the power of the vacuum drying oven, set the temperature to 90°C and the drying time to 3 hours. After placing the sample, close the oven door and start the vacuum pump to extract air. After reaching the vacuum degree, turn on the heating device. After the drying is completed, wait for the temperature to drop to room temperature, turn off the vacuum pump and take out the powder.

[0059] (3) Check the status of the ball mill, select a 304 stainless steel ball mill jar, clean it, put the dried powder into the jar, and then add 10 mm and 5 mm steel balls in the jar at a ratio of 1:4. Set the ball mill speed to 250 r / min and the total ball milling time to 4 h. Continue ball milling for 40 min, then stop and cool for 10 min, start the ball mill, and take out the ball mill jar after completion.

[0060] (4) Start the vibration screening machine and preheat it for a period of time to ensure that the equipment is stable. Slowly and evenly pour the ball-milled powder into the feed port of the vibration screening machine to avoid clogging caused by pouring too much at one time. The vibration frequency is set to 65 Hz, and the sieve mesh aperture is set to 50 μm and 25 μm respectively. The 50 μm sieve removes powder with too large a particle size, and the 25 μm sieve removes powder with too small a particle size. The total screening time is set to 20 minutes. After the screening is completed, take out the powder in the 25 μm sieve.

[0061] (5) Start the airflow classifier and wait until it reaches a stable operating state. Feed the screened powder evenly into the airflow classifier through a feeding device. Set the rotation speed at 2500 r / min, the airflow velocity at 15 m / s, and the feeding rate at 10 kg / h to ensure the stability and accuracy of the classification process. Take the bottom powder to obtain the cold spray powder.

[0062] Example 9 A method for preparing cold spray powder for anti-corrosion and repair of steel structure surface comprises the following steps: (1) The AlZn alloy and the FeCoCrNiMo high entropy alloy are ground into powders respectively, and the three raw materials in powder form are weighed and mixed according to proportion. (2) Check the vacuum drying oven to ensure that it is clean, free of debris, and has normal sealing and vacuum. Spread the above raw material powder evenly on the stainless steel tray without piling it too thickly. Turn on the power of the vacuum drying oven, set the temperature to 90°C and the drying time to 3 hours. After placing the sample, close the oven door and start the vacuum pump to extract air. After reaching the vacuum degree, turn on the heating device. After the drying is completed, wait for the temperature to drop to room temperature, turn off the vacuum pump and take out the powder.

[0063] (3) Check the status of the ball mill, select a 304 stainless steel ball mill jar, clean it, put the dried powder into the jar, and then add 10 mm and 5 mm steel balls in the jar at a ratio of 1:4. Set the ball mill speed to 300 r / min and the total ball milling time to 2 h. Continue ball milling for 20 min, then stop and cool for 15 min, start the ball mill, and remove the ball mill jar after completion.

[0064] (4) Start the vibration screening machine and preheat it for a period of time to ensure that the equipment is stable. Slowly and evenly pour the ball-milled powder into the feed port of the vibration screening machine to avoid clogging caused by pouring too much at one time. The vibration frequency is set to 65 Hz, and the sieve mesh aperture is set to 50 μm and 25 μm respectively. The 50 μm sieve removes powder with too large a particle size, and the 25 μm sieve removes powder with too small a particle size. The total screening time is set to 20 minutes. After the screening is completed, take out the powder in the 25 μm sieve.

[0065] (5) Start the airflow classifier and wait until it reaches a stable operating state. Feed the screened powder evenly into the airflow classifier through a feeding device. Set the rotation speed at 2500 r / min, the airflow velocity at 15 m / s, and the feeding rate at 10 kg / h to ensure the stability and accuracy of the classification process. Take the bottom powder to obtain the cold spray powder.

[0066] Example 10 A method for preparing cold spray powder for anti-corrosion and repair of steel structure surface comprises the following steps: (1) The AlZn alloy and the FeCoCrNiMo high entropy alloy are ground into powders respectively, and the three raw materials in powder form are weighed and mixed according to proportion.

[0067] (2) Check the vacuum drying oven to ensure that it is clean, free of debris, and has normal sealing and vacuum. Spread the above raw material powder evenly on a stainless steel tray without piling it too thickly. Turn on the power of the vacuum drying oven and set the temperature to 90°C for 3 hours. After placing the sample, close the door and start the vacuum pump to extract air. After reaching the vacuum degree, turn on the heating device. After the drying is completed, wait for the temperature to drop to room temperature, turn off the vacuum pump and take out the powder.

[0068] (3) Check the status of the ball mill, select a 304 stainless steel ball mill jar, clean it, put the dried powder into the jar, and then add 10 mm and 5 mm steel balls in the jar at a ratio of 1:4. Set the ball mill speed to 300 r / min and the total ball milling time to 2 h. Continue ball milling for 20 min, then stop and cool for 15 min, start the ball mill, and remove the ball mill jar after completion.

[0069] (4) Start the vibration screening machine and preheat it for a period of time to ensure that the equipment is stable. Slowly and evenly pour the ball-milled powder into the feed port of the vibration screening machine to avoid clogging caused by pouring too much at one time. The vibration frequency is set to 70 Hz, and the sieve mesh aperture is set to 50 μm and 25 μm respectively. The 50 μm sieve removes powder with too large a particle size, and the 25 μm sieve removes powder with too small a particle size. The total screening time is set to 15 minutes. After the screening is completed, take out the powder in the 25 μm sieve.

[0070] (5) Start the airflow classifier and wait until it reaches a stable operating state. Feed the screened powder evenly into the airflow classifier through a feeding device. Set the rotation speed at 3000 r / min, the airflow velocity at 20 m / s, and the feeding rate at 15 kg / h to ensure the stability and accuracy of the classification process. Take the bottom powder to obtain the cold spray powder.

[0071] Embodiment 11 A method for preparing cold spray powder for anti-corrosion and repair of steel structure surface comprises the following steps: (1) The AlZn alloy and the FeCoCrNiMo high entropy alloy are ground into powders respectively, and the three raw materials in powder form are weighed and mixed according to proportion. (2) Check the vacuum drying oven to ensure that it is clean, free of debris, and has normal sealing and vacuum. Spread the above raw material powder evenly on the stainless steel tray without piling it too thickly. Turn on the power of the vacuum drying oven, set the temperature to 80°C and the drying time to 4 hours. After placing the sample, close the door and start the vacuum pump to extract air. After reaching the vacuum degree, turn on the heating device. After the drying is completed, wait for the temperature to drop to room temperature, turn off the vacuum pump and take out the powder.

[0072] (3) Check the status of the ball mill, select a 304 stainless steel ball mill jar, clean it, put the dried powder into the jar, and then add 10 mm and 5 mm steel balls in the jar at a ratio of 1:4. Set the ball mill speed to 300 r / min and the total ball milling time to 2 h. Continue ball milling for 20 min, then stop and cool for 15 min, start the ball mill, and remove the ball mill jar after completion.

[0073] (4) Start the vibration screening machine and preheat it for a period of time to ensure that the equipment is stable. Slowly and evenly pour the ball-milled powder into the feed port of the vibration screening machine to avoid clogging caused by pouring too much at one time. The vibration frequency is set to 70 Hz, and the sieve mesh aperture is set to 50 μm and 25 μm respectively. The 50 μm sieve removes powder with too large a particle size, and the 25 μm sieve removes powder with too small a particle size. The total screening time is set to 30 minutes. After the screening is completed, take out the powder in the 25 μm sieve.

[0074] (5) Start the airflow classifier and wait until it reaches a stable operating state. Feed the screened powder evenly into the airflow classifier through a feeding device. Set the rotation speed at 2000 r / min, the airflow velocity at 10 m / s, and the feeding rate at 5 kg / h to ensure the stability and accuracy of the classification process. Take the bottom powder to obtain the cold spray powder.

[0075] Example 12 An application of cold spray powder for anti-corrosion repair of steel structure surface for on-site repair of power equipment includes the following steps: (1) Identify the electrical equipment that needs to be repaired, set up warning signs, wear safety protection equipment, find the repair point, thoroughly clean the surface of the substrate to be sprayed, use mechanical grinding combined with laser cleaning to remove the zinc coating, rust and other contaminants on the surface of the substrate to be sprayed, and place baffles around the area to be sprayed to avoid overspray.

[0076] (2) Use a drying oven to preheat the cleaned surface of the substrate to be sprayed. The preheating temperature is set to 300°C and the preheating time is set to 120s. During the preheating process, the temperature of the substrate should be controlled and monitored to avoid overheating of the substrate and to prevent oxidation and deformation of the surface to be sprayed.

[0077] (3) A low-pressure cold spraying process is used, including an air compressor, a cold air dryer and a spraying equipment. The switches and valves of the air compressor and the cold air dryer are turned on in sequence. The control system switch is turned on. The system parameters are set to a gas pressure of 0.8 MPa, a gas temperature of 300 °C, and a spraying forward speed of 2 mm / s. The cold spraying powder is accurately added to the powder feeder of the spraying equipment.

[0078] (4) After the preheating of the area to be sprayed on the substrate surface is completed, turn on the powder feeder switch and start spraying. The deposition angle of the spraying is 70° and the spraying distance is 10 mm. During the spraying process, spraying should be carried out at a stable speed and uniform path, and the coating quality should be closely observed and the spraying parameters should be adjusted in time. If problems such as sagging and bubbling are found in the coating, spraying should be stopped immediately and the parameters should be adjusted before continuing. After the spraying is completed, the low-pressure cold spray system should be turned off.

[0079] Embodiment 13 An application of cold spray powder for anti-corrosion repair of steel structure surface for on-site repair includes the following steps: (1) Identify the electrical equipment that needs to be repaired, set up warning signs, wear safety protection equipment, find the repair point, thoroughly clean the surface of the substrate to be sprayed, use mechanical grinding combined with laser cleaning to remove the zinc coating, rust and other contaminants on the surface of the substrate to be sprayed, and place baffles around the area to be sprayed to avoid overspray.

[0080] (2) Use a drying oven to preheat the cleaned surface of the substrate to be sprayed. The preheating temperature is set to 500°C and the preheating time is set to 60s. During the preheating process, the temperature of the substrate should be controlled and monitored to avoid overheating of the substrate and to prevent oxidation and deformation of the surface to be sprayed.

[0081] (3) A low-pressure cold spraying process is used, including an air compressor, a cold air dryer and a spraying equipment. The switches and valves of the air compressor and the cold air dryer are turned on in sequence. The control system switch is turned on. The system parameters are set to a gas pressure of 1.2 MPa, a gas temperature of 600 °C, and a spraying forward speed of 6 mm / s. The cold spraying powder is accurately added to the powder feeder of the spraying equipment.

[0082] (4) After the preheating of the area to be sprayed on the substrate surface is completed, turn on the powder feeder switch and start spraying. The deposition angle of the spraying is 90° and the spraying distance is 20 mm. During the spraying process, spraying should be carried out at a stable speed and uniform path, and the coating quality should be closely observed and the spraying parameters should be adjusted in time. If problems such as sagging and bubbling are found in the coating, spraying should be stopped immediately and the parameters should be adjusted before continuing. After the spraying is completed, the low-pressure cold spray system should be turned off.

[0083] Comparative Example 1 A cold spray powder for anti-corrosion and repair of steel structure surface comprises the following components: 75wt% AlZn alloy powder and 25wt% SiC powder, wherein the AlZn alloy comprises 85wt.% Al and 15wt.% Zn.

[0084] Comparative Example 2 A cold spray powder for anti-corrosion and repair of steel structure surface comprises the following components: 75wt% AlZn alloy powder and 25wt% FeCoCrNiMo high entropy alloy powder, wherein the AlZn alloy comprises 85wt.% Al and 15wt.% Zn, and the FeCoCrNiMo high entropy alloy has an atomic ratio of Fe:Co:Cr:Ni:Mo of 1:1:1:1:1.

[0085] Comparative Example 3 A cold spray powder for anti-corrosion and repair of steel structure surface comprises the following components: 55wt% AlZn alloy powder, 30wt% SiC powder, and 15wt% FeCoCrNiMo high entropy alloy powder, wherein the AlZn alloy comprises 85wt.% Al and 15wt.% Zn, and the FeCoCrNiMo high entropy alloy has an atomic ratio of Fe:Co:Cr:Ni:Mo of 1:1:1:1:1.

[0086] The corrosion resistance of the coatings formed by the cold spray powders prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the following experiments were conducted: (1) According to DL / 1453-2015 "Anti-corrosion Protection Coating for Transmission Line Towers", each coating was subjected to a neutral salt spray test to observe the corrosion onset time and measure the weight loss and corrosion rate after 720 hours. The test results are shown in Table 1. (2) According to ISO 17475:2005 “Electrochemical test methods for corrosion of metals and alloys – Guide for potentiostatic and potentiodynamic polarization measurements”, the coatings were electrochemically tested. The test results are shown in Table 2.

[0087] Table 1 Neutral salt spray test data From the table we can see that: (1) The corrosion time of the coatings prepared in Examples 1-3 is 720h. According to the relevant provisions of GB / T 26110-2010 "Technical Conditions for Aluminum-Zinc Coatings" and DL / 1453-2015 "Anti-Corrosion Protection Coatings for Transmission Line Towers", the corrosion time of the coatings should be greater than 480h. It can be seen that the coatings prepared in Examples 1-3 meet the requirements, while the coatings prepared in Comparative Examples 1 and 3 do not meet the requirements. (2) By comparing the experimental data of Examples 1-3 and Comparative Examples 1 and 3, it can be seen that after 720h, the coatings prepared in Examples 1-3 have less weight loss and a slow corrosion rate. The reason is that FeCoCrNiMo high entropy alloy is not added in Comparative Example 1, resulting in a decrease in corrosion resistance. The AlZn alloy content in Comparative Example 3 is too low, resulting in a decrease in corrosion resistance. It is proved that FeCoCrNiMo high entropy alloy and AlZn alloy can improve the corrosion resistance of the coating.

[0088] Table 2 Electrochemical test data Sample E(V) <![CDATA[I(A / cm 2 )]]> Example 1 -0.917 <![CDATA[7.579×10 -6 ]]> Example 2 -0.929 <![CDATA[7.889×10 -6 ]]> Example 3 -1.014 <![CDATA[8.097×10 -6 ]]> Comparative Example 1 -1.657 <![CDATA[3.579×10 -4 ]]> Comparative Example 2 -0.998 <![CDATA[7.932×10 -6 ]]> Comparative Example 3 -1.697 <![CDATA[8.697×10 -5 ]]> From the table we can see that: (1) The self-corrosion potentials of the coatings prepared in Examples 1-3 were all greater than -1.1 V, and the self-corrosion currents were all less than 8.1×10 -6 A / cm 2 The coating prepared by the cold spraying powder of the present invention has good corrosion resistance. Compared with the coating of the prior art, the self-corrosion potential is -1.3 to -1.5 V, and the self-corrosion current is 1.2 to 3.4×10 -4 A / cm 2 There has been a significant improvement. (2) By comparing the data of Examples 1-3 and Comparative Examples 1 and 2, it can be seen that FeCoCrNiMo high entropy alloy is one of the main components for improving the corrosion resistance of the coating. (3) By comparing the data of Examples 1-3 and Comparative Example 3, it can be seen that the coatings prepared in Examples 1-3 have better corrosion resistance, indicating that AlZn alloy is one of the main components for improving the corrosion resistance of the coating.

[0089] According to ISO 4516:2002 “Metallic and other inorganic coatings. Vickers and Knoop microhardness test”, the mechanical properties of the coatings formed by the cold spray powders prepared in Examples 1-3 and Comparative Examples 1-3 were tested. The results are shown in Tables 3 and 4.

[0090] Table 3 Coating surface hardness values Table 4 Coating friction coefficient Sample Maximum friction coefficient Average friction coefficient Example 1 0.388 0.317 Example 2 0.375 0.315 Example 3 0.391 0.374 Comparative Example 1 0.365 0.294 Comparative Example 2 0.426 0.396 Comparative Example 3 0.324 0.252 From the table we can see that: (1) The surface hardness values ​​of the coatings obtained in Examples 1-3 are all greater than 100 HV 0.5 The average friction coefficient is less than 0.4, indicating that the coating surface prepared by the cold spraying powder of the present invention is smooth and has good mechanical properties. The hardness of the coating is 66-76HV compared with the prior art. 0.25 The reason for the significant improvement is that silicon carbide (SiC) is the main hard phase in the formula, and high entropy alloy can also increase the hardness of the coating; (2) By comparing the data of Examples 1-3 and Comparative Examples 1-3, it can be seen that the mechanical properties of the coatings prepared in Examples 1-3 are better than those in Comparative Example 2, and slightly lower than those in Comparative Examples 1 and 3. The reason is that there is no silicon carbide in Comparative Example 2, so the hardness value is smaller and the friction coefficient is higher. Comparative Examples 1 and 3 have a higher proportion of silicon carbide, so the hardness value is higher and the friction coefficient is smaller, which proves that silicon carbide can significantly improve the mechanical properties of the coating.

[0091] In summary, the coating made from the cold spray powder of the present invention has good corrosion resistance and mechanical properties, which is greatly improved compared with the prior art. The above experimental data can prove that AlZn alloy can improve the corrosion resistance of the coating, silicon carbide can improve the mechanical properties of the coating, and FeCoCrNiMo high entropy alloy can improve the corrosion resistance and mechanical properties of the coating. The content of each component has an effect on the comprehensive performance of the coating. For example, too little AlZn alloy will reduce the corrosion resistance of the coating, and too much will cause other components to be reduced, resulting in loss of mechanical properties of the coating. The coating obtained by the ratio described in the present invention has the best comprehensive performance.

[0092] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A cold spray powder for anti-corrosion and repair of steel structure surface, characterized in that: The invention comprises the following components: 65-75wt.% of AlZn alloy, 15-20wt.% of SiC and 10-15wt.% of FeCoCrNiMo high entropy alloy.

2. The cold spray powder for anti-corrosion and repair of steel structure surface according to claim 1, characterized in that: The AlZn alloy includes 75-85 wt. % Al and 15-25 wt. % Zn.

3. The cold spray powder for anticorrosion and repair of steel structure surface according to claim 1, characterized in that: The FeCoCrNiMo high entropy alloy has an atomic ratio of Fe:Co:Cr:Ni:Mo of 1:1:1:1:0.2-1.

4. A method for preparing a cold spray powder for anti-corrosion and repair of a steel structure surface, wherein the cold spray powder for anti-corrosion and repair of a steel structure surface is the cold spray powder according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) preparing raw materials in proportion, mixing and drying; (2) grinding the dried raw material to obtain an intermediate powder; (3) screening the intermediate powder; (4) The sieved intermediate powder is classified to obtain cold spray powder.

5. The method for preparing a cold spray powder for anticorrosion and repair of a steel structure surface according to claim 4, characterized in that: In step (2), a ball mill is used for grinding, and the diameters of the balls in the ball mill are 10 mm and 5 mm, with a ratio of 1:

4.

6. The method for preparing a cold spray powder for anticorrosion and repair of a steel structure surface according to claim 4, characterized in that: In step (2), the ball mill speed is 250-300 r / min, and the ball milling is continued for 20-40 minutes, and then paused for 10-15 minutes. The total ball milling time is 2-4 hours.

7. The method for preparing cold spray powder for anticorrosion and repair of steel structure surface according to claim 4, characterized in that: In step (3), a vibrating screening machine is used for screening, the apertures of the screening meshes are set to 50 μm and 25 μm respectively, the vibration frequency is 65 Hz-70 Hz, and the total screening time is 15-30 min.

8. The method for preparing cold spray powder for anticorrosion and repair of steel structure surface according to claim 4, characterized in that: In step (4), an air flow classifier is used for classification, the speed of the air flow classifier is 2000-3000 r / min, the air flow velocity is 10-20 m / s, and the feeding rate is 5-15 kg / h.

9. Application of a cold spray powder for anti-corrosion repair of steel structure surface for on-site repair of power equipment, the cold spray powder for anti-corrosion repair of steel structure surface is the cold spray powder according to any one of claims 1 to 3, characterized in that: The following steps are involved: a) Determine the on-site operation area, set up warning signs, wear safety protection equipment, and find repair points; b) Determine the repair point and pre-treat the surface of the steel structure of the power equipment to be sprayed, including cleaning and preheating; c) A low-pressure cold spraying process is used to spray cold spray powder on the pretreated steel structure surface; in the low-pressure cold spraying process, the process gas is air, the gas pressure is 0.8-1.2Mpa, the gas temperature is 300-500°C, the spraying deposition angle is 70-90°, the spraying distance is 10-20mm, and the spraying forward speed is 2-6mm / s.

10. The application of the cold spray powder for anti-corrosion repair of steel structure surface according to claim 9 for on-site repair of power equipment, characterized in that: In step b), the preheating temperature is 300-500° C. and the preheating time is 60-120 seconds.

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