A method for repairing a protective layer of a slurry circulating pump impeller

Abstract

The application relates to a repair protective layer preparation method of a slurry circulating pump impeller, which comprises the following steps: a surface pretreatment step, a laser cladding additive manufacturing step, a finishing step, a surface treatment step and a corrosion and wear resistance treatment step, wherein the laser cladding additive manufacturing step comprises the following steps: automatically planning a route by using a laser cladding device, setting a repair transition layer, and setting at least one repair layer on the repair transition layer, wherein the scanning speed of the laser cladding device for setting the repair layer is greater than the scanning speed for setting the repair transition layer, the repair transition layer is made of an iron-based alloy material matched with the material of the impeller, and the repair layer is made of an iron-based alloy material with micro-nano particles added with WC and CeO2. The repair structure formed in this way has high bonding strength with the impeller base, and the impeller base and the repair layer are better integrated; the repair layer has the advantages of strength, toughness, wear resistance and corrosion resistance, the impeller as a whole is repaired to meet the use requirements, and the service life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of slurry circulation pump technology, and in particular to a method for preparing a repair and protective layer for a slurry circulation pump impeller. Background Technology

[0002] The slurry circulation pump is a crucial piece of equipment in the desulfurization system of a thermal power plant. Installed next to the desulfurization tower, it is used for the recirculation of gypsum slurry within the tower. As a pump with high flow rates and demanding operating conditions in the limestone (lime)-gypsum desulfurization process, its failure is often caused by corrosion and wear. When the impeller surface of the slurry circulation pump is damaged by wear, corrosion, and cavitation, the impeller gradually thins, develops pitting corrosion, and may even develop gaps. The existence and development of these defects can affect the safe and reliable operation of the entire desulfurization system.

[0003] Under normal circumstances, the service life of a slurry circulation pump is about 3 years, and the impeller needs to be replaced about once a year. Repairing and maintaining the impeller is an important technical measure to ensure the safe and economical operation of the desulfurization system. Traditional repair methods typically employ a combination of welding or manual welding repair with coating techniques. Welding, with its high heat transfer, can lead to further cracking of pits and deeper impeller cracks. Manual welding repair combined with coating, as described in Chinese invention patent CN106736232B, a method for repairing desulfurization slurry circulation pumps, involves repairing impeller blades by welding stainless steel mesh plates to the worn edges; applying a 3-10mm thick wear-resistant repair agent to the impeller surface; drying the agent; placing the impeller in an oven for heat treatment at 60°C for 2-6 hours; and then performing dimensional restoration and surface finishing. The wear-resistant repair agent is SIConit ceramic material. However, slurry circulation pump impellers are made of special materials, typically high-strength alloys A49 or Cr30A. The coating material differs from the substrate, resulting in low bonding strength. This method only provides some protection for the impeller and cannot repair damaged areas.

[0004] Therefore, it is necessary to design a method for preparing a repair and protective layer for the impeller of a slurry circulation pump to improve the impeller's anti-abrasion performance and extend its service life. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a method for preparing a repair and protective layer for a slurry circulation pump impeller.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a repair and protective layer for a slurry circulation pump impeller includes:

[0008] Surface pretreatment steps: The impeller part to be repaired is treated to meet the requirements of laser cladding additive manufacturing;

[0009] Laser cladding additive manufacturing steps:

[0010] The area to be clad is uniformly preheated to a temperature of 60-110℃. The purpose is to heat the substrate as a whole or on its surface to a certain temperature, reduce the temperature gradient between the cladding layer and the substrate material, and alleviate thermal stress. A preheating temperature of about 100℃ can reduce the cooling rate of the molten pool without generating excessive structural stress, thus significantly reducing the residual stress of the laser cladding layer.

[0011] Laser cladding equipment is used to automatically plan the route, set the repair transition layer, and control the thickness between 0.4mm and 0.6mm;

[0012] The laser cladding equipment automatically plans the route and sets at least one repair layer on the repair transition layer, with the thickness controlled between 0.8mm and 1.2mm. The interlayer temperature between the repair transition layer and the repair layer is between 140℃ and 160℃.

[0013] In this process, the scanning speed of the laser cladding equipment for setting the repair layer is greater than that for setting the repair transition layer. The repair transition layer is an iron-based alloy material that matches the impeller material, while the repair layer is an iron-based alloy material with micro-nano particles containing WC and CeO2.

[0014] Repair steps: Repair the impeller after cladding and restore it to its original size;

[0015] Surface treatment steps: The entire impeller of the repaired slurry circulation pump is sandblasted to make its surface roughness meet the requirements of the spraying process;

[0016] Corrosion protection steps: Use supersonic flame spraying equipment to spray anti-corrosion and anti-wear materials onto the entire surface of the impeller; then apply a sealing agent to the sprayed impeller.

[0017] Preferably, in the laser cladding additive manufacturing step:

[0018] The repair transition layer is made of iron-based alloy powder containing Fe, Cr, Ni, and Si, and the phases of the repair transition layer are FeCr solid solution strengthening phase and Cr. 23 C6 wear-resistant phase.

[0019] Preferably, the thickness of the repair transition layer is 0.5 mm.

[0020] Preferably, the thickness of the repair layer is 1 mm.

[0021] Preferably, in the laser cladding additive manufacturing step:

[0022] When setting the repair transition layer, the laser cladding equipment has a laser cladding power of 3000W, a scanning speed of 8mm / s, a spot diameter of 4mm, and a powder feeding speed of 4.2g / min.

[0023] When setting the repair layer, the laser cladding equipment has a laser cladding power of 3000W, a scanning speed of 16mm / s, a spot diameter of 4mm, and a powder feeding speed of 25g / min.

[0024] Preferably, in the laser cladding additive manufacturing step, when the repair layer is multi-layered, after each repair layer is clad, the repair layer is allowed to cool, the surface is cleaned, and PT flaw detection is performed to ensure that there are no defects before proceeding to the next repair layer cladding, until the cracks, pits and profiles of the impeller part to be repaired are restored.

[0025] After the cladding is completed, PT and hardness tests are conducted, and the results meet the testing standards.

[0026] Preferably, in the surface pretreatment step, the impeller part to be repaired is cleaned and the surface of the impeller part to be repaired is polished with an angle grinder until a continuous and complete smooth metal surface is formed; the polished impeller part to be repaired is subjected to PT flaw detection, and the requirement for laser cladding additive manufacturing is that there are no cracks and pore defects.

[0027] Preferably, in the trimming step, the original dimensions include the impeller profile and surface flatness;

[0028] The impeller profile is achieved by machining the impeller's precision mating surfaces on a lathe;

[0029] Surface flatness is achieved through surface polishing, specifically by polishing the surface of the cladding impeller area until it is on the same smooth plane as the unrepaired area.

[0030] Preferably, the specific steps for applying anti-corrosion material to the entire surface of the impeller using a supersonic flame spraying device are as follows: A mixed powder containing 80% Monel alloy powder and 20% nickel-plated WC powder is sprayed onto the entire surface of the impeller to form an anti-corrosion and anti-wear coating. The oxygen flow rate of the supersonic flame spraying device is 10 m³ / s. 3 •h -1 The propane flow rate is 1200 L•h -1 The nitrogen flow rate is 1300 L•h -1 The supersonic flame spraying equipment has a spraying distance of 180mm between itself and the impeller surface; the resulting anti-corrosion and anti-wear coating has a thickness of 0.3mm.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] The method for preparing a repair and protective layer for a slurry circulation pump impeller provided in the above technical solution applies laser cladding additive manufacturing technology to the repair of slurry circulation pump impellers, which not only accelerates the repair speed but also improves the repair quality. The method of this invention first pre-treats the impeller area to be repaired to meet the requirements of laser cladding additive manufacturing, avoiding further cracking of the impeller due to the heat of laser cladding. Then, the area to be clad is preheated to prevent impeller cracking due to sudden temperature changes. Finally, a repair transition layer with a matching material and appropriate thickness is set as a transition connection structure between the repair layer and the impeller substrate, enhancing the connection between the repair layer and the impeller. The strong bonding strength of the substrate improves the integration of the impeller substrate and the repair layer. A further repair layer of micro / nano-sized iron-based alloy material containing WC and CeO2 particles is added on top of the repair transition layer. Firstly, compared to the repair transition layer, the laser cladding equipment has a higher scanning speed for setting the repair layer, preventing the repair layer and the newly formed repair transition layer from absorbing excessive energy and experiencing large-area melting and remelting, which could lead to the failure of the repair transition layer and affect the cladding quality. Secondly, the addition of WC and CeO2 to the repair layer strengthens and toughens the iron-based alloy cladding repair layer, forming a solid solution strengthening phase FeCr, a stable rare earth compound CeNi3, and wear-resistant and corrosion-resistant phases WC and Cr. 23 C6 can improve the strength, toughness, wear resistance and corrosion resistance of the cladding repair layer; finally, the impeller is repaired, surface treated and anti-corrosion treated, and the impeller is repaired to meet the usage requirements and extend its service life. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a partial cross-sectional schematic diagram of an impeller repaired using the method of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Impeller substrate; 2. Repair transition layer; 3. Repair layer. Detailed Implementation

[0037] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] This invention provides a method for preparing a repair and protective layer for a slurry circulation pump impeller, comprising the following steps:

[0041] First, the surface pretreatment step: the impeller part to be repaired is treated to meet the requirements of laser cladding additive manufacturing;

[0042] Specifically, the impeller area to be repaired is cleaned and polished using an angle grinder until a continuous and smooth metal surface is formed. A smooth surface facilitates the tight bonding between the subsequent repair transition layer 2 and the impeller substrate 1, and improves the uniformity of the laser cladding powder on the surface of the impeller substrate 1, thereby making the formation of the repair transition layer 2 smoother and laying a good foundation for the subsequent repair layer 3. The polished impeller area to be repaired is then subjected to PT flaw detection. Laser cladding additive manufacturing requires the absence of cracks and pore defects, thereby avoiding further deepening of cracks or pores by the heat during subsequent laser cladding.

[0043] Then comes the laser cladding additive manufacturing step:

[0044] The area to be clad is uniformly preheated to a temperature of 60-110℃. The purpose of preheating is to heat the entire impeller substrate or its surface to a certain temperature. On the one hand, this can reduce the temperature gradient between the repair transition layer 2 and the impeller substrate, thus mitigating thermal stress. On the other hand, setting the repair transition layer on the preheated impeller substrate can reduce the cooling rate of the molten pool without generating excessive structural stress, significantly reducing the residual stress of the repair transition layer and improving the repair effect.

[0045] The laser cladding equipment automatically plans the cladding route, which is programmed by the equipment itself. Laser cladding is used to set the repair transition layer 2, and the thickness of the repair transition layer 2 is controlled between 0.4mm and 0.6mm, preferably 0.5mm. The impeller of the slurry circulation pump is generally made of high-strength alloy A49 or Cr30A. A49 is also known as white cast iron or high-chromium alloy cast iron, while Cr30A is also known as duplex stainless white cast iron, i.e., Cr30 + Ni, Cu, Mo. Its microstructure consists of austenite + ferrite + granular eutectic carbides + secondary carbides. Its duplex matrix contains a large amount of easily passivated and pitting corrosion resistant alloying elements such as chromium, molybdenum, and copper. Both A49 and Cr30A have good wear resistance and corrosion resistance. Therefore, the repair transition layer 2 is an iron-based alloy material that matches the impeller material, specifically an iron-based alloy powder containing Fe, Cr, Ni, and Si. The phases of the repair transition layer 2 are FeCr solid solution strengthening phase and wear-resistant Cr. 23 C6 exhibits better adhesion to the impeller substrate 1. The mass fraction (wt.%) of each component in the iron-based alloy powder is 71.35Fe, 17.45Cr, 3.87Ni, 3.43Mo, 2.53C, and 1.37Si. The composition and thermal expansion coefficient of the iron-based alloy repair transition layer 2 are similar to those of the substrate, thus playing a role in component transition and preventing the substrate from cracking during subsequent cladding. Controlling the thickness of the repair transition layer 2 to around 0.5mm has the advantage of low residual stress.

[0046] The laser cladding equipment automatically plans the cladding route, which is programmed by the equipment itself. At least one repair layer 3 is applied to the repair transition layer, with a thickness controlled between 0.8mm and 1.2mm, preferably 1mm. This thickness provides optimal corrosion resistance. The number of repair layers 3 is determined by the degree of damage to the impeller area to be repaired, with the depth matching the thickness of each repair layer 3. When multiple repair layers 3 are used, after each layer is clad, it is allowed to cool, its surface is cleaned, and PT (Potential Testing) is performed to ensure no defects before proceeding to the next layer. This process continues until the cracks, pits, and profiles of the impeller area to be repaired are restored.

[0047] The interlayer temperature between the repair transition layer 2 and the repair layer 3 is 140℃-160℃, preferably 150℃, which can produce a fine-grained structure and help improve the strength, toughness and plasticity of the transition layer and the repair layer.

[0048] Specifically, the laser cladding equipment uses a higher scanning speed for setting the repair layer 3 than for setting the repair transition layer 2. In particular, when setting the repair transition layer 2, the laser cladding equipment...

[0049] When setting the repair transition layer in the laser cladding equipment, the laser cladding power is 3000W, the scanning speed is 8mm / s, the spot diameter is 4mm, and the powder feeding speed is 4.2g / min. The scanning speed determines the amount of laser injected energy, i.e., the energy density. The scanning speed largely determines the size and homogeneity of the cladding layer's structure. If the scanning speed is too low, below 8mm / s, the interaction time between the laser beam and the cladding material increases, and the energy absorbed by the repair transition layer 2 increases. At this time, the substrate melts more severely, leading to a sharp increase in the dilution rate. The performance after cladding changes significantly and fails to meet the required wear and corrosion resistance. Therefore, the scanning speed of the repair transition layer is set to 8mm / s.

[0050] When the repair layer 3 is set, the laser cladding equipment has a laser cladding power of 3000W, a scanning speed of 16mm / s, a spot diameter of 4mm, and a powder feeding speed of 25g / min.

[0051] Compared to the repair transition layer 2, the laser cladding equipment has increased the scanning speed for the repair layer 3. This avoids excessive energy absorption by the repair layer 3 and the newly formed repair transition layer 2, preventing large-area melting and remelting, which could lead to the failure of the repair transition layer 2 and affect the cladding quality. Provided the energy density is sufficient to ensure the melting of the cladding layer, a higher scanning speed results in a finer cladding layer structure and a correspondingly smaller precipitate size, improving the toughness, strength, corrosion resistance, and wear resistance of the cladding layer. However, an excessively high scanning speed, greater than 16 mm / s, results in a short molten pool existence time during cladding, leading to reduced mechanical properties. Therefore, the scanning speed for the repair transition layer is set to 16 mm / s.

[0052] The repair layer 3 is a micro / nano-sized iron-based alloy material with added WC and CeO2, wherein the addition ratio of WC and CeO2 is 10% and 5%, respectively. The micro / nano-sized iron-based alloy material is a directly purchased finished powder, and the mass fraction (wt.%) of each component in the micro / nano-sized iron-based alloy powder is 71.35Fe, 17.45Cr, 3.87Ni, 3.43Mo, 2.53C, and 1.37Si; forming a solid solution strengthening phase FeCr, a stable rare earth compound CeNi3, and wear-resistant and corrosion-resistant phases WC and Cr. 23C6 can improve the strength, toughness, wear resistance and corrosion resistance of the cladding repair layer 3.

[0053] Furthermore, the repair process involves repairing the clad impeller to restore it to its original dimensions.

[0054] The original dimensions include the impeller profile and surface flatness. Specifically, the impeller profile is achieved by machining the impeller's precision mating surfaces on a lathe, restoring the impeller profile to its initial state. Then, the slurry circulation pump impeller undergoes PT (penetration test) and hardness testing. The PT test meets the Class I (qualified) standard of NB / T47013.5 Non-destructive Testing of Pressure Equipment, Part 5. Surface flatness is then achieved through surface grinding, polishing the surface of the clad impeller area until it is flush with the unrepaired area.

[0055] Next is the surface treatment step: the entire impeller of the repaired slurry circulation pump is sandblasted to make its surface roughness meet the spraying requirements, enhance the bonding strength between the subsequent anti-corrosion coating and the substrate, and eliminate stress effects. Specifically, quartz stone is used for sandblasting roughening.

[0056] Finally, the anti-corrosion treatment steps are as follows: anti-corrosion material is sprayed onto the entire surface of the impeller using supersonic flame spraying equipment; the sprayed impeller is then treated with an overall sealing agent.

[0057] Specifically, the steps for applying anti-corrosion material to the entire surface of the impeller using supersonic flame spraying equipment are as follows: A mixed powder containing 80% Monel alloy powder and 20% nickel-plated WC powder is sprayed onto the entire surface of the impeller to form an anti-corrosion and anti-wear coating. The oxygen flow rate of the supersonic flame spraying equipment is 10 m³ / s. 3 •h -1 The propane flow rate is 1200 L•h -1 The nitrogen flow rate is 1300 L•h -1 The supersonic flame spraying equipment maintains a spraying distance of 180mm between itself and the impeller surface; the resulting anti-corrosion and anti-wear coating has a thickness of 0.3mm. The composition (wt.%) of the Monel alloy powder is: 58.5Ni, 0.5Cr, 30.0Cu, 2.5Fe, 8.0Mo, 0.3C, and 0.2Si; the composition of the nickel-plated WC powder is: 65%Ni60A and 35%WC, where the composition (wt.%) of the Ni60A powder is: 8.0Fe, 0.8C, 16.5Cr, 4.25Si, 3.75B, and 66.7Ni.

[0058] A mixed powder spray coating of Monel alloy powder and nickel-coated WC powder forms (Ni, Cu) and (Ni, Mo) solid solutions and WC and Cr. 23The C6 phase, (Ni, Cu) and (Ni, Mo) solid solutions provide solid solution strengthening, while WC and Cr... 23 The C6 phase acts as a reinforcing agent, giving this coating excellent wear and corrosion resistance.

[0059] The impeller after spraying is treated with a sealing agent. Specifically, a sealing agent with good penetration, resistance to acidic chemical corrosion, and non-dissolving and non-deteriorating properties is used to treat the impeller after spraying. The sealing agent can enhance the coating performance, ensure the overall impeller can maintain stable performance in the working environment of the slurry circulation pump, and extend its service life. The sealing agent is a directly purchased product and will not be described in detail here.

[0060] The impeller structure of the slurry circulation pump repaired using the above method involves laser cladding with powder of similar material to the impeller substrate, and the addition of a repair transition layer and a repair layer with different compositions. The impeller profile is restored using a cladding path programmed by an automated system. A supersonic flame spraying anti-abrasion coating is then applied to improve wear, corrosion, and cavitation resistance, extending the impeller's service life. This supersonic flame spraying technology significantly reduces the coating's porosity (<0.5%), and the use of a corrosion-resistant and high-temperature-resistant sealing agent further enhances the anti-corrosion and anti-wear effect of the supersonic flame coating. Through this comprehensive approach, damaged slurry circulation pump impellers can be effectively repaired and protected, extending the pump's service life by more than 5 years, resulting in significant direct economic benefits. Simultaneously, it reduces labor costs associated with replacing old parts, leading to significant indirect economic benefits.

[0061] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a repair and protective layer for a slurry circulation pump impeller, characterized in that, The method comprises the following steps: a surface pretreatment step: processing the impeller part to be repaired to meet the requirements of laser cladding additive manufacturing; a laser cladding additive manufacturing step: uniformly preheat the area to be cladded, and control the temperature at 60-110℃; automatically plan the route by using a laser cladding device, set a repair transition layer, and control the thickness at 0.4mm-0.6mm; when setting the repair transition layer, the laser cladding power is 3000W, the scanning speed is 8mm / s, the diameter of the light spot is 4mm, and the powder feeding speed is 4.2g / min; automatically plan the route by using a laser cladding device, set at least one repair layer on the repair transition layer, and control the thickness at 0.8mm-1.2mm; when setting the repair layer, the laser cladding power is 3000W, the scanning speed is 16mm / s, the diameter of the light spot is 4mm, and the powder feeding speed is 25g / min; wherein the scanning speed of the laser cladding device when setting the repair layer is greater than the scanning speed when setting the repair transition layer, the repair transition layer is an iron-based alloy material matched with the material of the impeller, and the repair layer is a micro-nano particle iron-based alloy material added with WC and CeO2; the interlayer temperature of the repair transition layer and the repair layer is at 140℃-160℃; a trimming step: trimming the cladded impeller to restore to the original size; a surface treatment step: sandblasting the repaired slurry circulating pump impeller as a whole to make the surface roughness meet the requirements of spraying process; a corrosion and wear resistance treatment step: spraying a corrosion and wear resistance material on the surface of the impeller by using a supersonic flame spraying device; and performing overall sealing agent treatment on the sprayed impeller.

2. The method of claim 1, wherein: In the laser cladding additive manufacturing step: The material of the repair transition layer is an iron-based alloy powder containing Fe, Cr, Ni and Si, and the phase of the formed repair transition layer is FeCr solid solution strengthening phase and Cr 23 C6 wear-resistant phase.

3. The method of claim 1, wherein: the thickness of the repair transition layer is 0.5mm.

4. The method of claim 1, wherein: the thickness of the repair layer is 1mm.

5. The method of claim 1, wherein: In the laser cladding additive manufacturing step, when the repair layer is multi-layered, after completing the cladding of one repair layer, waiting for the repair layer to cool, performing surface cleaning, and performing PT detection to ensure no defects, cladding the next repair layer until the cracks, pits and profile of the impeller part to be repaired are restored; after completing the cladding as a whole, performing PT detection and hardness detection to meet the detection standards.

6. The method of claim 1, wherein, In the surface pretreatment step, cleaning the impeller part to be repaired, and polishing the surface of the impeller part to be repaired by using an angle grinder until a continuous and complete smooth metal surface is formed; performing PT detection on the polished impeller part to be repaired, and the laser cladding additive manufacturing requirements are no cracks and porosity defects.

7. The method of claim 1, wherein, In the trimming step, the original size includes the impeller profile and surface flatness; the impeller profile is achieved by machining the precision fitting surface of the impeller by using a lathe; the surface flatness is achieved by surface polishing, specifically: polishing the surface of the cladded impeller area to the same smooth plane as the un-repaired part.

8. The method of claim 1, wherein, The specific steps of spraying the anti-corrosion and anti-abrasion material on the whole surface of the impeller by using the supersonic flame spraying equipment are as follows: the whole surface of the impeller is sprayed by using the mixed powder containing 80% Monel alloy powder and 20% nickel-coated WC powder to form the anti-corrosion and anti-abrasion coating, the oxygen flow of the supersonic flame spraying equipment is 10 m 3 •h-1, the nitrogen flow is 1300 L•h-1, the spraying distance between the supersonic flame spraying equipment and the surface of the impeller is 180 mm, and the thickness of the formed anti-corrosion and anti-abrasion coating is 0.3 mm.

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