Special valve hard sealing element dissimilar material coating process

Abstract

The invention belongs to the technical field of valve sealing element coating and plating processes, and discloses a special valve hard sealing element dissimilar material coating and plating process which comprises the following steps: S1, surface pretreatment; s2, coating of a bottom layer coating; s3, coating of an intermediate coating; s4, coating of a top layer coating; s5, quality detection and control; the surface pretreatment comprises cleaning, mechanical treatment, acid pickling and passivation, the coating of the bottom coating comprises nickel plating treatment and chromium plating treatment, the coating of the middle coating comprises ceramic coating and coating curing, and the coating of the top coating comprises tungsten carbide coating and coating heat treatment. The quality detection and control comprises coating thickness testing, adhesive force testing, corrosion resistance testing and wear resistance testing. According to the method, a compact and hard ceramic coating is formed through curing treatment, so that the high temperature resistance of the sealing element is improved, and the wear resistance and corrosion resistance of the sealing element are further enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of valve seal coating and plating technology, in particular to a special valve hard seal heterogeneous material coating and plating technology. Background Art

[0002] The dissimilar material coating process for special valve hard seals is a surface treatment technology specifically used to improve the performance of valve seals. This process uses a series of steps to coat a layer of dissimilar materials on the hard seals of special valves to enhance their wear resistance, corrosion resistance and high temperature resistance, thereby extending the service life of the valve. This process not only broadens the application range of special materials on valves, but also improves the economy and durability of valves.

[0003] However, there are still some substantial problems in the coating process of heterogeneous materials for special valve hard seals, namely poor material compatibility. Hard seals are usually composed of two or more different materials, and the coating process involves covering a layer of external coating (such as metal plating or ceramic coating) on ​​the base material. If the physical and chemical properties of the coating material and the base material are incompatible (such as differences in expansion coefficients, hardness, etc.), the bonding force between the coating and the base will be insufficient. During long-term use, this poor compatibility may cause the coating to fall off, crack or peel off, thereby affecting the sealing performance and the service life of the valve. At the same time, there will be a series of problems such as difficulty in controlling the coating thickness, durability problems of the coating, compatibility of heat treatment and coating, high complexity of process control, and sealing surface matching problems, which urgently need to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide a special valve hard seal heterogeneous material coating process to solve the problems raised in the above background technology.

[0005] In order to achieve the above object, the present invention provides the following technical solution: a special valve hard seal heterogeneous material coating process, comprising the following steps:

[0006] S1: surface pretreatment;

[0007] S2: application of base coating;

[0008] S3: application of intermediate coating;

[0009] S4: application of top coating;

[0010] S5: Quality inspection and control;

[0011] The surface pretreatment includes cleaning, mechanical treatment, pickling and passivation, the coating of the base coating includes nickel plating and chrome plating, the coating of the intermediate coating includes ceramic coating and coating curing, the coating of the top coating includes tungsten carbide coating and coating heat treatment, and the quality inspection and control includes coating thickness test, adhesion test, corrosion resistance test and wear resistance test.

[0012] As a further technical solution of the present invention, the cleaning is used to remove grease, dust and other contaminants on the surface of the material to ensure the uniformity and adhesion of the coating. It uses an acidic cleaning solution, including a mixture of hydrochloric acid (HCl) and hydrofluoric acid (HF), with a hydrochloric acid concentration of 5% to 10% and a hydrofluoric acid concentration of 1% to 2%. The cleaning method adopts immersion cleaning or spray cleaning. Immersion cleaning is more suitable for workpieces with complex shapes, and spray cleaning is suitable for parts with less serious surface contamination. The cleaning temperature is 40°C to 50°C, and the cleaning time is 10 minutes. For some difficult-to-clean areas, ultrasonic cleaning can improve the cleaning effect. The ultrasonic frequency is selected to be 40kHz, and the cleaning time is 5 minutes.

[0013] As a further technical solution of the present invention, the mechanical treatment includes sandblasting, pickling, and passivation. The sandblasting is used to remove the oxide layer and attachments on the surface of the substrate and enhance the surface roughness to improve the adhesion of the coating. The sandblasting material is quartz sand with a particle size of 30 to 50 meshes. The sandblasting pressure is 0.3 to 0.5 MPa. The sandblasting time is 3 to 5 minutes. The sandblasting angle needs to keep the sandblasting gun at a 45° angle to the workpiece surface, and the sandblasting spacing is 20 to 30 cm.

[0014] As a further technical solution of the present invention, the pickling adopts a dilute nitric acid solution to remove the surface oxide film, the nitric acid concentration is 10%, the pickling temperature is 25°C to 30°C, and the pickling time is 5 minutes. The passivation adopts chromic acid passivation, which can further improve the surface corrosion resistance. The passivation solution concentration is 5% to 7% chromic acid, the passivation time is 5 to 10 minutes, and the passivation temperature is 25°C to 30°C.

[0015] As a further technical solution of the present invention, the nickel plating treatment is used to provide good corrosion resistance and improve the surface smoothness of the substrate. The nickel plating solution formula includes the following formula: nickel sulfuric acid (NiSO4): 250g / L, nickel chloride (NiCl2): 30g / L, boric acid (H3BO3): 30g / L, wherein the pH value is 4.5-5.0, the temperature is 50°C-55°C, and the current density is 2.5A / dm 2 The nickel plating time is 20 to 30 minutes, the nickel plating thickness is 20 to 40 μm, and the concentration of the nickel plating solution must be stable. The tank liquid should be replaced regularly to avoid the deposition of impurities.

[0016] As a further technical solution of the present invention, the chrome plating treatment is used to provide higher hardness, wear resistance and corrosion resistance, and is often used for valves under extreme working conditions. The chrome plating solution formula includes the following formula: chromic acid (CrO3): 250g / L, chromium chloride (CrCl3): 10g / L, wherein the pH value is 1.0-2.0, and the current density is 10A / dm 2 , temperature: 40℃~45℃, chrome plating time: 30~60 minutes, chrome plating thickness: 25~50μm.

[0017] As a further technical solution of the present invention, the ceramic coating is used to improve the high temperature resistance and wear resistance of the hard seal and avoid surface degradation in a high temperature environment. The coating material includes aluminum oxide (Al2O3): 90%, epoxy resin (curing agent): 10%, and the coating method is thermal spraying. The spraying temperature is 1200°C to 1500°C, the spraying thickness is 50 to 100 μm, the spraying atmosphere is argon, and the spraying time is 1 hour. The curing temperature of the coating is 150°C to 180°C, and the curing time is 30 to 60 minutes.

[0018] As a further technical solution of the present invention, the coating material of the tungsten carbide coating is WC 80%, Co20%, the coating method is laser cladding, the laser power is 800W-1200W, the laser beam diameter is 1.5mm, the scanning speed is 2-5mm / s, the coating thickness is 100-200μm, the powder spraying rate is 3-5g / min, and the coating density is above 90%.

[0019] As a further technical solution of the present invention, the heat treatment temperature of the coating heat treatment is 500° C. to 600° C., the heat treatment time is 1 hour to 2 hours, and the protective atmosphere is nitrogen.

[0020] As a further technical solution of the present invention, the coating thickness test includes using a coating thickness gauge to test each batch, and the qualified standard is that the coating thickness must be uniform and meet the design requirements, requiring a tolerance of ±5%, the adhesion test includes a pull-out test, and the qualified standard is that the coating must not peel off during the pull-out test, and the adhesion is ≥20Mpa, the corrosion resistance test includes a salt spray test, and the qualified standard is that after 1000 hours of testing, there is no obvious corrosion on the coating surface, and the corrosion resistance test includes a Taber wear test, and the qualified standard is that the wear amount is ≤10mg, meeting the standard wear resistance requirements.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The present invention ensures the cleanliness and roughness of the surface of the substrate material by adopting a comprehensive pretreatment method including an acid cleaning solution, mechanical treatment, pickling and passivation, laying a solid foundation for the subsequent coating. In particular, the selection of the acid cleaning solution not only effectively removes pollutants such as grease and dust, but also removes the surface oxide layer through chemical action, thereby improving the adhesion and uniformity of the coating. The sandblasting step in the mechanical treatment further enhances the surface roughness and optimizes the bonding interface between the coating and the substrate. In the coating stage of the bottom coating, the present invention selects two treatment methods, nickel plating and chrome plating. The nickel plating layer has good corrosion resistance and a certain hardness, can significantly improve the smoothness of the substrate surface, and provides a better coating for the subsequent coating. The chrome plating layer is known for its high hardness, wear resistance and corrosion resistance, and is particularly suitable for valve seals under extreme working conditions. By precisely controlling the plating solution formula, electroplating parameters and time, the present invention ensures that the thickness, hardness and adhesion of the underlying coating meet the design requirements. In the coating stage of the intermediate coating, the present invention adopts ceramic coating technology. The ceramic coating has the characteristics of high temperature resistance, wear resistance and oxidation resistance, and has become a key link in improving the performance of valve seals. Through thermal spraying technology, a mixture of aluminum oxide and epoxy resin is evenly sprayed on the underlying coating, and then cured to form a dense and hard ceramic coating. This step not only improves the high temperature resistance of the seal, but also further enhances its wear resistance and corrosion resistance.

[0023] 2. The present invention introduces tungsten carbide coating technology, which is another important means to improve the hardness and wear resistance of valve seals. Tungsten carbide is an ideal choice for valve seal coatings under extreme working conditions due to its high hardness, high wear resistance and good chemical stability. Through laser cladding technology, a mixture of tungsten carbide and cobalt is accurately coated on the intermediate coating to form a top coating with excellent performance. This step not only significantly improves the hardness and wear resistance of the seal, but also optimizes the microstructure of the coating and improves its ability to resist crack propagation through rapid cooling and solidification during the laser cladding process. By accurately controlling the heat treatment temperature and time and selecting nitrogen as the protective atmosphere, the residual stress inside the coating is effectively eliminated, and the stability and durability of the coating are improved. The quality inspection and control link ensures that the performance of each batch of coatings meets the design requirements through coating thickness testing, adhesion testing, corrosion resistance testing and wear resistance testing, especially corrosion resistance testing and wear resistance testing. By simulating the use conditions under extreme working conditions, the reliability and stability of the coating in practical applications are verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a block diagram of the overall system structure of the present invention;

[0025] Figure 2 This is a schematic diagram of the surface pretreatment process of the present invention;

[0026] Figure 3 Schematic diagram of the coating process of the bottom coating of the present invention;

[0027] Figure 4 Schematic diagram of the coating process of the intermediate coating of the present invention;

[0028] Figure 5 Schematic diagram of the coating process of the top coating of the present invention;

[0029] Figure 6 It is a schematic diagram of the quality detection and control process of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0031] like Figures 1 to 6 As shown, in the embodiment of the present invention, the special valve hard seal heterogeneous material coating process includes the following steps:

[0032] S1: surface pretreatment;

[0033] S2: application of base coating;

[0034] S3: application of intermediate coating;

[0035] S4: application of top coating;

[0036] S5: Quality inspection and control;

[0037] Surface pretreatment includes cleaning, mechanical treatment, pickling and passivation. The coating of the base coating includes nickel plating and chrome plating. The coating of the intermediate coating includes ceramic coating and coating curing. The coating of the top coating includes tungsten carbide coating and coating heat treatment. Quality inspection and control include coating thickness test, adhesion test, corrosion resistance test and wear resistance test.

[0038] Through systematic surface pretreatment, multi-level coating, and strict quality inspection and control, high-performance protection of the seal surface is achieved. This process not only improves the corrosion resistance and wear resistance of the seal, but also ensures good adhesion and appropriate thickness of the coating through fine coating design. This series of measures work together to significantly enhance the sealing performance and service life of special valves, providing a strong guarantee for the stable operation of valves under harsh working conditions. The application of this process is of great significance to improving the overall quality and market competitiveness of valve products.

[0039] Among them, cleaning is used to remove grease, dust and other contaminants on the surface of the material to ensure the uniformity and adhesion of the coating. It uses an acidic cleaning solution, including a mixture of hydrochloric acid (HCl) and hydrofluoric acid (HF). The concentration of hydrochloric acid is 5% to 10%, and the concentration of hydrofluoric acid is 1% to 2%. The cleaning method adopts immersion cleaning or spray cleaning. Immersion cleaning is more suitable for workpieces with complex shapes, and spray cleaning is suitable for parts with less serious surface contamination. The cleaning temperature is 40℃ to 50℃, and the cleaning time is 10 minutes. For some difficult-to-clean areas, ultrasonic cleaning can improve the cleaning effect. The ultrasonic frequency is selected to be 40kHz, and the cleaning time is 5 minutes.

[0040] The cleaning process using an acidic cleaning fluid (containing 5% to 10% hydrochloric acid and 1% to 2% hydrofluoric acid) can effectively remove pollutants such as grease and dust from the surface of special valve hard seals, laying a solid foundation for uniform coating and firm adhesion of the coating. Through immersion or spray cleaning, it is suitable for workpieces of different shapes and degrees of contamination to ensure cleaning efficiency and effect. In particular, cleaning at 40°C to 50°C for 10 minutes, or assisted by 40kHz ultrasonic cleaning for 5 minutes, can significantly improve the cleanliness of difficult-to-clean areas. This process not only optimizes the coating quality, but also improves the durability and reliability of valve seals.

[0041] Among them, mechanical treatment includes sandblasting, pickling and passivation. Sandblasting is used to remove the oxide layer and attachments on the surface of the substrate and enhance the surface roughness to improve the adhesion of the coating. The sandblasting material is quartz sand with a particle size of 30 to 50 meshes. The sandblasting pressure is 0.3 to 0.5 MPa and the sandblasting time is 3 to 5 minutes. The sandblasting angle needs to keep the sandblasting gun at a 45° angle to the workpiece surface, and the sandblasting spacing is 20 to 30 cm.

[0042] The sandblasting step in the mechanical treatment uses 30-50 mesh quartz sand, 0.3-0.5Mpa pressure, 45° angle and 20-30cm spacing to sandblast the surface of special valve hard seals for 3-5 minutes, effectively removing the oxide layer and attachments, and significantly enhancing the surface roughness. This treatment not only provides a good adhesion foundation for subsequent coatings, but also further improves the bonding strength and overall performance of the coating. By precisely controlling the sandblasting parameters, the stability and consistency of the treatment effect are ensured, laying a solid foundation for the long-term use of valve seals.

[0043] Among them, pickling uses a dilute nitric acid solution to remove the surface oxide film, the nitric acid concentration is 10%, the pickling temperature is 25°C to 30°C, and the pickling time is 5 minutes. Chromic acid passivation is used for passivation, which can further improve the surface corrosion resistance. The passivation solution concentration is 5% to 7% chromic acid, the passivation time is 5 to 10 minutes, and the passivation temperature is 25°C to 30°C.

[0044] Pickling and passivation treatment significantly improves the surface quality of special valve hard seals. A 10% dilute nitric acid solution was used for pickling at 25℃~30℃ for 5 minutes to effectively remove the surface oxide film. Subsequently, a 5%~7% chromic acid passivation treatment was performed for 5~10 minutes, also at 25℃~30℃, to further enhance the surface corrosion resistance. This series of treatments not only optimizes the combination of the coating and the substrate, but also significantly improves the durability and long-term stability of the seal, providing a strong guarantee for the reliable operation of the valve in various harsh environments.

[0045] Among them, nickel plating treatment is used to provide good corrosion resistance and improve the surface smoothness of the substrate. The nickel plating solution formula includes the following formula: nickel sulfuric acid (NiSO4): 250g / L, nickel chloride (NiCl2): 30g / L, boric acid (H3BO3): 30g / L, pH value: 4.5-5.0, temperature: 50℃-55℃, current density: 2.5A / dm 2 The nickel plating time is 20 to 30 minutes, the nickel plating thickness is 20 to 40 μm, and the concentration of the nickel plating solution must be stable. The tank liquid should be replaced regularly to avoid the deposition of impurities.

[0046] Nickel plating provides excellent corrosion resistance and smooth surface for special valve hard seals. The optimized nickel plating solution formula is used, including appropriate amounts of nickel sulfuric acid, nickel chloride and boric acid, at a pH value of 4.5 to 5.0, a temperature of 50°C to 55°C, and a current density of 2.5A / dm 2Under the condition of 20-30 minutes of nickel plating, a coating thickness of 20-40μm can be obtained. This treatment not only significantly enhances the corrosion resistance of the seal, but also improves its surface quality and reduces friction and wear. By regularly replacing the nickel plating solution, the stability and consistency of the coating quality are ensured, providing a solid guarantee for the long life and high performance of the valve.

[0047] Among them, chrome plating is used to provide higher hardness, wear resistance and corrosion resistance, and is often used for valves under extreme working conditions. The chrome plating solution formula includes the following formula: chromic acid (CrO3): 250g / L, chromium chloride (CrCl3): 10g / L, pH value: 1.0-2.0, current density: 10A / dm 2 , temperature: 40℃~45℃, chrome plating time: 30~60 minutes, chrome plating thickness: 25~50μm.

[0048] Chrome plating significantly improves the hardness, wear resistance and corrosion resistance of special valve hard seals, and is particularly suitable for extreme working conditions. The optimized chrome plating solution formula, including chromic acid and chromium chloride, is used at a pH value of 1.0 to 2.0 and a current density of 10A / dm 2 Under the condition of 40℃~45℃, chrome plating for 30~60 minutes can obtain a coating thickness of 25~50μm. This treatment not only greatly enhances the durability of the seal, but also significantly improves its corrosion resistance and wear resistance. The excellent performance of the chrome plating layer provides a reliable guarantee for the long-term stable operation of the valve in harsh environments.

[0049] Among them, the ceramic coating is used to improve the high temperature resistance and wear resistance of the hard seal and avoid surface degradation in high temperature environment. The coating material includes aluminum oxide (Al2O3): 90%, epoxy resin (curing agent): 10%, the coating method is thermal spraying, the spraying temperature is 1200℃~1500℃, the spraying thickness is 50~100μm, the spraying atmosphere is argon, the spraying time is 1 hour, the curing temperature of the coating is 150℃~180℃, and the curing time is 30~60 minutes.

[0050] Ceramic coating significantly enhances the high temperature resistance and wear resistance of special valve hard seals. Using a high proportion of aluminum oxide and epoxy resin, through thermal spraying technology, at a high temperature of 1200℃~1500℃, a 50~100μm coating is sprayed, which effectively avoids surface degradation in high temperature environment. Argon is used as the spraying atmosphere to ensure the purity and quality of the coating. The coating curing process is carried out at 150℃~180℃ for 30~60 minutes, which further enhances the stability and durability of the coating. This treatment provides a solid guarantee for the long-term stable operation of the valve in a high temperature and high wear environment.

[0051] Among them, the coating material of the tungsten carbide coating is WC 80%, Co 20%, the coating method is laser cladding, the laser power is 800W~1200W, the laser beam diameter is 1.5mm, the scanning speed is 2~5mm / s, the coating thickness is 100~200μm, the powder spraying rate is 3~5g / min, and the coating density is more than 90%.

[0052] Tungsten carbide coating significantly improves the hardness and wear resistance of special valve hard seals. Using high-quality coating materials of WC 80% and Co20%, through laser cladding technology, at a laser power of 800W to 1200W, with a laser beam diameter of 1.5mm and a scanning speed of 2 to 5mm / s, a 100 to 200μm coating is accurately applied. The powder spraying rate is 3 to 5g / min, ensuring the uniformity and high density of the coating (more than 90%). This treatment not only greatly enhances the durability of the seal, but also significantly improves its wear resistance, providing reliable guarantee for the long-term stable operation of the valve under extreme working conditions.

[0053] The heat treatment temperature of the coating is 500° C. to 600° C., the heat treatment time is 1 hour to 2 hours, and the protective atmosphere is nitrogen.

[0054] Coating heat treatment is a key step to improve the performance of special valve hard seal coatings. Heat treatment at 500℃ to 600℃ for 1 to 2 hours helps eliminate residual stress inside the coating and optimize its microstructure, thereby further improving the hardness and wear resistance of the coating. Nitrogen as a protective atmosphere effectively prevents oxidation and degradation of the coating at high temperatures. This treatment not only enhances the stability and durability of the coating, but also ensures the long-term reliable operation of the valve in harsh environments, significantly improving the service life and performance of the valve.

[0055] Among them, the coating thickness test includes using a coating thickness gauge to test each batch. The qualified standard is that the coating thickness must be uniform and meet the design requirements, requiring a tolerance of ±5%. The adhesion test includes a pull-out test. The qualified standard is that the coating must not peel off during the pull-out test, and the adhesion must be ≥20Mpa. The corrosion resistance test includes a salt spray test. The qualified standard is that there is no obvious corrosion on the coating surface after 1000 hours of testing. The corrosion resistance test includes a Taber wear test. The qualified standard is that the wear amount is ≤10mg, meeting the standard wear resistance requirements.

[0056] The coating quality test ensures that the performance of special valve hard seals meets the standards. The coating thickness test ensures that each batch of coating is uniform and meets the design requirements. The adhesion test verifies the strong bond between the coating and the substrate through the pull-out test. The corrosion resistance test verifies the stability of the coating under long-term use and harsh environments through the salt spray test and Taber wear test. This series of strict quality control measures ensures that the coating has excellent durability, adhesion and wear resistance, providing a solid guarantee for the long-term stable operation of the valve under various extreme working conditions.

[0057] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. The coating process of special valve hard seals with different materials includes the following steps: S1: surface pretreatment; S2: application of base coating; S3: application of intermediate coating; S4: application of top coating; S5: Quality inspection and control; The surface pretreatment includes cleaning, mechanical treatment, pickling and passivation, the coating of the base coating includes nickel plating and chrome plating, the coating of the intermediate coating includes ceramic coating and coating curing, the coating of the top coating includes tungsten carbide coating and coating heat treatment, and the quality inspection and control includes coating thickness test, adhesion test, corrosion resistance test and wear resistance test.

2. The special valve hard seal heterogeneous material coating process according to claim 1 is characterized by: The cleaning is used to remove grease, dust and other pollutants on the surface of the material to ensure the uniformity and adhesion of the coating. An acidic cleaning solution is used, including a mixture of hydrochloric acid (HCl) and hydrofluoric acid (HF). The concentration of hydrochloric acid is 5% to 10%, and the concentration of hydrofluoric acid is 1% to 2%. The cleaning method adopts immersion cleaning or spray cleaning. Immersion cleaning is more suitable for workpieces with complex shapes, and spray cleaning is suitable for parts with less surface pollution. The cleaning temperature is 40°C to 50°C, and the cleaning time is 10 minutes. For some difficult-to-clean areas, ultrasonic cleaning can improve the cleaning effect. The ultrasonic frequency is selected to be 40kHz, and the cleaning time is 5 minutes.

3. The special valve hard seal heterogeneous material coating process according to claim 1 is characterized by: The mechanical treatment includes sandblasting, pickling and passivation. The sandblasting is used to remove the oxide layer and attachments on the surface of the substrate and enhance the surface roughness to improve the adhesion of the coating. The sandblasting material is quartz sand with a particle size of 30 to 50 meshes. The sandblasting pressure is 0.3 to 0.5 MPa. The sandblasting time is 3 to 5 minutes. The sandblasting angle needs to keep the sandblasting gun at a 45° angle to the workpiece surface, and the sandblasting spacing is 20 to 30 cm.

4. The special valve hard seal heterogeneous material coating process according to claim 3 is characterized by: The pickling adopts a dilute nitric acid solution to remove the surface oxide film, the nitric acid concentration is 10%, the pickling temperature is 25°C to 30°C, and the pickling time is 5 minutes. The passivation adopts chromic acid passivation, which can further improve the surface corrosion resistance. The passivation solution concentration is 5% to 7% chromic acid, the passivation time is 5 to 10 minutes, and the passivation temperature is 25°C to 30°C.

5. The special valve hard seal heterogeneous material coating process according to claim 1 is characterized by: The nickel plating treatment is used to provide good corrosion resistance and improve the surface smoothness of the substrate. The nickel plating solution formula includes the following formula: nickel sulfuric acid (NiSO4): 250g / L, nickel chloride (NiCl2): 30g / L, boric acid (H3BO3): 30g / L, wherein the pH value is 4.5-5.0, the temperature is 50°C-55°C, and the current density is 2.5A / dm 2 The nickel plating time is 20 to 30 minutes, the nickel plating thickness is 20 to 40 μm, and the concentration of the nickel plating solution must be stable. The tank liquid should be replaced regularly to avoid the deposition of impurities.

6. The special valve hard seal heterogeneous material coating process according to claim 1 is characterized by: The chrome plating treatment is used to provide higher hardness, wear resistance and corrosion resistance, and is often used for valves under extreme working conditions. The chrome plating solution formula includes the following formula: chromic acid (CrO3): 250g / L, chromium chloride (CrCl3): 10g / L, wherein the pH value is 1.0-2.0, and the current density is 10A / dm 2 , temperature: 40℃~45℃, chrome plating time: 30~60 minutes, chrome plating thickness: 25~50μm.

7. The special valve hard seal heterogeneous material coating process according to claim 1 is characterized by: The ceramic coating is used to improve the high temperature resistance and wear resistance of the hard seal and avoid surface degradation in a high temperature environment. The coating material includes aluminum oxide (Al2O3): 90%, epoxy resin (curing agent): 10%, the coating method is thermal spraying, the spraying temperature is 1200°C to 1500°C, the spraying thickness is 50 to 100 μm, the spraying atmosphere is argon, the spraying time is 1 hour, the curing temperature of the coating is 150°C to 180°C, and the curing time is 30 to 60 minutes.

8. The special valve hard seal heterogeneous material coating process according to claim 1 is characterized by: The coating material of the tungsten carbide coating is WC 80%, Co 20%, the coating method is laser cladding, the laser power is 800W-1200W, the laser beam diameter is 1.5mm, the scanning speed is 2-5mm / s, the coating thickness is 100-200μm, the powder spraying rate is 3-5g / min, and the coating density is above 90%.

9. The special valve hard seal heterogeneous material coating process according to claim 1 is characterized by: The heat treatment temperature of the coating heat treatment is 500° C. to 600° C., the heat treatment time is 1 hour to 2 hours, and the protective atmosphere is nitrogen.

10. The special valve hard seal heterogeneous material coating process according to claim 1, characterized in that: The coating thickness test includes using a coating thickness gauge to test each batch. The qualified standard is that the coating thickness must be uniform and meet the design requirements, requiring a tolerance of ±5%. The adhesion test includes a pull-out test. The qualified standard is that the coating must not peel off during the pull-out test, and the adhesion is ≥20Mpa. The corrosion resistance test includes a salt spray test. The qualified standard is that there is no obvious corrosion on the coating surface after 1000 hours of testing. The corrosion resistance test includes a Taber wear test. The qualified standard is that the wear amount is ≤10mg, meeting the standard wear resistance requirements.

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