Nickel-cadmium plating method for steel part for gas turbine

Abstract

The invention provides a nickel-cadmium plating method for a steel part for a gas turbine. The nickel-cadmium plating method comprises the steps of inspection before plating, clamping, chemical degreasing, flowing hot water cleaning, flowing cold water cleaning, drying, dismounting, isolation, flow mark cleaning, isolation inspection, clamping, electrochemical degreasing, flowing cold water cleaning, activation, flowing cold water cleaning, nickel chloride plating, non-flowing cold water cleaning and flowing cold water cleaning. The method comprises the steps of nickel plating, non-flowing cold water cleaning, flowing cold water cleaning, nickel plating layer inspection, cadmium plating, non-flowing cold water cleaning, flowing cold water cleaning, primary passivation, non-flowing cold water cleaning, flowing cold water cleaning, isolation removal, flowing hot water cleaning, flowing cold water cleaning, secondary passivation, non-flowing cold water cleaning, flowing cold water cleaning, non-flowing distilled water cleaning, drying and cadmium plating layer inspection. And dismounting, annealing and acceptance inspection are carried out. Damage to the surface of the titanium alloy blade can be reduced, the performance of the blade is protected, the pickling process is easy to control and implement, the production efficiency can be improved, and the cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal surface treatment, and particularly relates to a method for nickel-cadmium plating of steel parts for gas turbines. Background Art

[0002] In the field of gas turbines, steel parts are key components of gas turbines, and their performance and quality directly affect the reliability and service life of gas turbines. In order to improve the corrosion resistance, wear resistance and oxidation resistance of steel parts, surface treatment is usually required, and nickel-cadmium plating is a commonly used surface treatment method. The nickel-cadmium coating can effectively protect the surface of steel parts, prevent them from being corroded and worn, and thus extend the service life of gas turbines.

[0003] At present, the existing methods for nickel-cadmium plating of steel parts for gas turbines have many deficiencies. For example, the process flow design is unreasonable, and the coordination between various links is poor, thus affecting the production efficiency and quality; the pre-plating inspection is not comprehensive enough, and the inspection of surface defects of parts is not strict enough, affecting the coating quality; in the degreasing link, the effect of the solution is not good, and the control of temperature and time is not accurate enough to completely remove pollutants, resulting in reduced bonding strength; when nickel-cadmium plating, the control of solution components is not strict, and the stability of parameters is poor, resulting in unstable coating performance and poor quality. In addition, the requirements for equipment in the existing methods are not clear, and the material and structure are unreasonable, which will also affect the coating quality. At the same time, insufficient attention is paid to the cleaning link and the activation link. Incomplete cleaning affects the adhesion of the coating, and improper activation results in insufficient surface activity of parts and low bonding strength, reducing the service life and reliability of parts. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for nickel-cadmium plating of steel parts for gas turbines, which can solve the problems of unstable coating quality, poor bonding strength, and easy occurrence of defects such as bulging, blistering and delamination, can improve the surface quality and performance of steel parts, and extend the service life of gas turbines. Specifically, the present invention ensures higher coating quality, better process stability, wider adaptability, better environmental protection and stricter quality control through strict pre-plating treatment, optimized degreasing and plating processes, precise process parameter control and perfect quality inspection links.

[0005] A method for nickel-cadmium plating of steel parts for gas turbines includes the following steps:

[0006] S1, pre-plating inspection: Visually inspect the surface state of the parts on the inspection table before nickel-cadmium plating. The surface of the parts shall not have oxide film, scale, corrosion, indentation, burr, scratch, dent, burn, pore and abrasion;

[0007] S2, Clamping: Clamp the part onto the copper fixture. After clamping, ensure that the solution can enter all the holes and recesses of the part, and no bubbles should form on the surface and around the part.

[0008] S3, Chemical Degreasing: Conduct degreasing treatment in a degreasing tank with a solution composition of 30 - 50 grams per liter of trisodium phosphate and 3 - 5 grams per liter of OP-7 emulsifier. The treatment temperature is 60 - 80 degrees Celsius, and the time is 10 - 20 minutes.

[0009] S4, Flowing Hot Water Cleaning: Immerse the part in a flowing hot water tank at 60 - 90 degrees Celsius and clean it 3 - 5 times. The cleaning time for each time is 1 - 2 minutes.

[0010] S5, Flowing Cold Water Cleaning: Immerse the part in a flowing cold water tank and clean it 3 - 5 times. The cleaning time for each time is 1 - 2 minutes.

[0011] S6, Drying: Blow dry the moisture on the surface of the part with clean compressed air.

[0012] S7, Dismounting: Remove the part from the copper fixture on the dismounting table.

[0013] S8, Isolation: Apply an isolation glue with a composition and mass fraction of 20% - 30% white wax, 40% - 50% paraffin wax, and 20% - 40% turpentine to the surfaces that do not need to be cadmium-nickel plated for isolation treatment. The treatment temperature is 70 - 90 degrees Celsius.

[0014] S9, Use a scraper to remove the flow marks of the isolation glue on the surface of the part, and then wipe the surface to be plated with a cotton cloth dipped in heavy refined paraffin wax.

[0015] S10, Isolation Inspection: Check whether the isolation glue completely covers the surfaces of the parts that do not need to be plated, and there should be no residue of the isolation glue on the surfaces of the parts that need to be plated.

[0016] S11 Clamping: The same as S2.

[0017] S12, Electrochemical Degreasing: Conduct degreasing treatment in an electrochemical degreasing tank with a solution composition of 150 - 170 grams per liter of sodium hydroxide, 80 - 100 grams per liter of calcined sodium carbonate, and 10 - 30 grams per liter of water glass. The treatment temperature is 18 - 30 degrees Celsius, the current density is 3 - 10 amperes per square decimeter, the anode holding time is 2 - 3 minutes, the cathode holding time is 15 - 20 minutes, and Sa:Sk = 1:1, where Sa is the anode surface area and Sk is the cathode surface area.

[0018] S13 Flowing Cold Water Cleaning: The same as S5.

[0019] S14, Activation: Conduct activation treatment in an activation tank with a solution composition of 100 - 150 grams per liter of hydrochloric acid. The treatment temperature is 18 - 30 degrees Celsius, and the time is 1 - 2 minutes.

[0020] S15, Cold water rinsing in flow: The same as S5;

[0021] S16, Nickel chloride plating: When the steel part material is stainless steel or high carbon steel, nickel chloride plating is carried out in a nickel plating bath with an electrolyte composition of 200 - 250 g / L nickel chloride and 90 - 120 g / L pure salt. The treatment temperature is 18 - 30 °C, the current density is 5 - 10 A / dm², the non-current time is 2 minutes, the current-carrying time is 3 - 4 minutes, and Sa:Sk = 2:1;

[0022] S17, Cold water rinsing without flow after nickel chloride plating: Immerse the parts in a cold water bath without flow and rinse 3 - 5 times, with each rinsing time being 1 - 2 minutes;

[0023] S18, Cold water rinsing in flow after nickel chloride plating: The same as S5;

[0024] S19, Nickel plating: When the steel part material is carbon steel, low carbon steel, or stainless steel and high carbon steel that has undergone nickel chloride plating, nickel plating is carried out in a nickel plating bath with an electrolyte composition of 140 - 170 g / L nickel sulfate, 10 - 15 g / L nickel chloride hexahydrate, 130 - 170 g / L sodium sulfate, and 20 - 30 g / L boric acid. The nickel plating temperature is 28 - 35 °C, the current density is 0.4 - 0.6 A / dm², the time is 45 - 60 minutes, the pH value is 4 - 6, and Sa:Sk = 2:1;

[0025] S20, Cold water rinsing without flow: The same as S17;

[0026] S21, Cold water rinsing in flow: The same as S5;

[0027] S22, Inspection of nickel plating layer: Inspect the nickel plating layer of the parts on the inspection table. The appearance of the nickel plating layer should be smooth, without bulging, bubbles, and delamination, and non-plating is not allowed;

[0028] S23, Cadmium plating: Cadmium plating is carried out in a cadmium plating bath with an electrolyte composition of 40 - 500 g / L cadmium sulfate, 48 - 52 g / L sodium sulfate, 100 - 120 g / L sodium sulfate, and 3 - 5 g / L OP-7 emulsifier. The cadmium plating temperature is 18 - 30 °C, the current density is 1.5 - 2.5 A / dm², the time is 6 - 10 minutes, and Sa:Sk = 2:1;

[0029] S24, Cold water rinsing without flow: The same as S17;

[0030] S25, Cold water rinsing in flow: The same as S5;

[0031] S26, primary passivation: chemical passivation in a passivation tank containing 100-150 g / L potassium dichromate, 10-15 g / L sulfuric acid, and 10-15 g / L hydrochloric acid, at a passivation temperature of 18-30 degrees Celsius, for 3-5 times;

[0032] S27, still cold water cleaning: same as S17;

[0033] S28, flowing cold water cleaning: immerse the parts in a non-flowing distilled water tank for cleaning 3 to 5 times, each cleaning time is 0.5 to 1 minute;

[0034] S29, de-isolating: performing de-isolating treatment in a de-isolating tank containing 30 to 50 grams per liter of calcined sodium carbonate at a temperature of 80 to 100 degrees Celsius for a period of time until the isolating glue is completely removed;

[0035] S30, running hot water cleaning: same as S4;

[0036] S31, running cold water cleaning: same as S5;

[0037] S32, passivation again: same as S26;

[0038] S33, still cold water cleaning: same as S17;

[0039] S34, running cold water cleaning: same as S5;

[0040] S35, non-flowing distilled water cleaning: immerse the parts in a non-flowing distilled water tank for cleaning 3 to 5 times, each cleaning time is 0.5 to 1 minute;

[0041] S36, Drying: Same as S6;

[0042] S37, Check the cadmium plating layer: Check the cadmium plating layer on the inspection table. The nickel plating layer should be smooth, without bulging or delamination, and in the form of fine crystals;

[0043] S38, Disassembly: Remove the parts from the copper tooling on the disassembly table and store in a dry, clean environment;

[0044] S39, annealing: anneal the parts in a drying oven at a temperature of 350 to 370 degrees Celsius for 60 to 90 minutes, starting from the time the annealing temperature is reached;

[0045] S40, Acceptance inspection: Check the appearance of the nickel-cadmium coating, its adhesion strength to the base metal of the part, and its microhardness on the inspection table.

[0046] Furthermore, the inspection tables in S1, S22, S37, S40 and the disassembly tables in S7, S38 should be covered with polyvinyl chloride plastic.

[0047] Further, the degreasing tank in S3 and the flowing hot water tank in S4 are made of stainless steel, and are structurally provided with a side air extraction port, a serpentine steam pipe with a pressure resistance rating of 0.3 MPa, and a compressed air stirrer with an operating pressure greater than 0.2 MPa.

[0048] Further, the flowing cold water tank in S5 should be made of stainless steel, and is structurally provided with a cleaning tank made of polyvinyl chloride plastic and a compressed air stirrer with an operating pressure greater than 0.2 MPa.

[0049] Further, the compressed air in S6 should blow the mirror or filter paper for at least 3 - 4 minutes every month, and there should be no moisture and oil stain residues on the mirror or filter paper.

[0050] Further, the electro - chemical degreasing tank in S12 is made of stainless steel, and is structurally provided with a side air extraction port and a current commutation device.

[0051] Further, the activation tank in S14 and the passivation tank in S26 are made of stainless steel, and are structurally provided with a lining made of polyvinyl chloride plastic, a side air extraction port, and a compressed air stirrer with an operating pressure greater than 0.2 MPa.

[0052] Further, the nickel - plating tanks in S16 and S19 and the cadmium - plating tank in S23 are made of stainless steel, and are structurally provided with a lining made of polyvinyl chloride plastic and a side air extraction port.

[0053] Further, the non - flowing cold water tank in S17 and the non - flowing distilled water tank in S35 are made of stainless steel, and are structurally provided with a cleaning basket made of polyvinyl chloride plastic.

[0054] Further, the drying oven in S39 can automatically adjust the temperature, with a temperature difference within ±10 degrees Celsius, to ensure that the parts are evenly heated.

[0055] The beneficial effects of the present invention are as follows:

[0056] 1. Excellent coating quality: Through strict pre - plating inspection and treatment, it is ensured that the surface state of the parts is good, reducing the influence of surface defects on the coating quality. The optimized degreasing treatment and activation steps can more effectively remove oil stains and impurities, enhancing the bonding force between the coating and the base metal, and reducing the occurrence of defects such as bulging, bubbling, and delamination. Precise control of the process parameters for nickel - plating and cadmium - plating makes the coating more uniform, dense, with a smooth appearance and a fine crystal shape, improving the corrosion resistance and oxidation resistance of the coating.

[0057] 2. Stable and reliable process: Specific requirements for equipment and tools, such as the material and structural design of degreasing tanks, hot water tanks, cold water tanks, etc., ensure the stability and reliability of the equipment during use. Quality control of compressed air and drying ovens ensures the stability of process conditions, thereby improving the repeatability and stability of the entire nickel-cadmium plating process.

[0058] 3. Wide adaptability: Corresponding nickel plating processes are formulated according to different materials of steel parts, enabling the present invention to be applicable to various types of steel parts and having a wider adaptability.

[0059] 4. Good environmental performance: In the isolation and de-isolation steps, the isolation glue and de-isolation solution used are relatively environmentally friendly, reducing environmental pollution.

[0060] 5. Strict quality control: Multiple inspection and acceptance steps are added, including inspection of nickel plating layers and cadmium plating layers, acceptance inspection, etc., which can promptly detect problems and make adjustments to ensure that the product quality meets the requirements and improve the qualified rate of products. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a flowchart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0062] The present invention will be further described below with reference to the accompanying drawings.

[0063] As Figure 1 shown, a method for nickel-cadmium plating of steel parts for gas turbines includes the following steps:

[0064] S1. Pre-plating inspection: Visually inspect the surface condition of the parts on the inspection table before nickel-cadmium plating. The surface of the parts should be free of oxide films, scale, corrosion, indentations, burrs, scratches, dents, burns, pores and abrasions;

[0065] The desktop of the inspection table should be covered with polyvinyl chloride plastic;

[0066] S2. Clamping: Clamp the parts onto a copper fixture. After clamping, it should be ensured that the solution can enter all the holes and recesses of the parts, and no bubbles should form on the surface and around the parts;

[0067] The copper fixture can be replaced with copper wire;

[0068] S3. Chemical degreasing: Perform degreasing treatment in a degreasing tank with a solution composition of 30 - 50 grams per liter of trisodium phosphate and 3 - 5 grams per liter of OP-7 emulsifier, at a treatment temperature of 60 - 80 degrees Celsius for 10 - 20 minutes;

[0069] The degreasing tank is made of stainless steel and is structurally equipped with a side air extraction port, a serpentine steam pipe with a pressure resistance rating of 0.3 MPa, and a compressed air stirrer with an operating pressure greater than 0.2 MPa;

[0070] S4, Flow hot water cleaning: Immerse the parts in a flowing hot water tank at 60 - 90 °C and clean them 3 - 5 times, with each cleaning time being 1 - 2 minutes; After chemical degreasing, degreasing solution and related impurities may remain on the surface of the parts. Flow hot water cleaning can effectively remove these impurities. At the same time, the temperature of the hot water helps to further clean the surface of the parts, providing a cleaner surface condition for subsequent processing steps.

[0071] The flow hot water tank is made of stainless steel and is structurally equipped with a side air extraction port, a serpentine steam pipe with a pressure resistance rating of 0.3 MPa, and a compressed air stirrer with an operating pressure greater than 0.2 MPa;

[0072] S5, Flow cold water cleaning: Immerse the parts in a flowing cold water tank and clean them 3 - 5 times, with each cleaning time being 1 - 2 minutes; The purpose of this step is, firstly, to check the degreasing quality according to the wetness of the part surface. After the degreased surface is completely wetted, if water aggregates into drops, the degreasing quality is unqualified and the degreasing operation should be repeated. Secondly, it is to quickly and evenly cool the parts in preparation for subsequent drying.

[0073] The flow cold water tank is made of stainless steel and is structurally equipped with a cleaning tank made of polyvinyl chloride plastic and a compressed air stirrer with an operating pressure greater than 0.2 MPa;

[0074] S6, Drying: Blow dry the moisture on the surface of the parts with clean compressed air;

[0075] Compressed air should blow the mirror surface or filter paper for at least 3 - 4 minutes every month, and there should be no moisture and oil stain residues on the mirror surface or filter paper;

[0076] S7, Disassembly: Remove the parts from the copper fixture on the disassembly table;

[0077] The desktop of the disassembly table should be covered with polyvinyl chloride plastic;

[0078] S8, Isolation: Apply an isolation glue with a composition and mass fraction of 20% - 30% white paraffin wax, 40% - 50% paraffin wax, and 20% - 40% turpentine to the surfaces that do not need to be cadmium - nickel plated for isolation treatment, with the treatment temperature being 70 - 90 °C;

[0079] S9, Use a scraper to remove the flow marks of the isolation glue on the surface of the parts, and then wipe the surface that needs to be plated with a cotton cloth dipped in heavy refined paraffin wax;

[0080] S10, Isolation inspection: Check whether the isolation glue completely covers the surface of the parts that do not need to be plated, and at the same time, there should be no residue of the isolation glue on the surface of the parts that need to be plated;

[0081] S11 Clamping: The same as S2;

[0082] S12 Electrochemical degreasing: Perform degreasing treatment in an electrochemical degreasing tank with a solution composition of 150 - 170 g / L of sodium hydroxide, 80 - 100 g / L of calcined sodium carbonate, and 10 - 30 g / L of water glass. The treatment temperature is 18 - 30 °C, the current density is 3 - 10 A / dm², the anode holding time is 2 - 3 minutes, the cathode holding time is 15 - 20 minutes, and Sa:Sk = 1:1, where Sa is the anode surface area and Sk is the cathode surface area;

[0083] S13 Flowing cold water cleaning: The same as S5; The purpose of this step is to clean the degreasing residue adhering to the part surface after electrochemical degreasing and provide a clean surface for the activation process;

[0084] S14 Activation: Perform activation treatment in an activation tank with a solution composition of 100 - 150 g / L of hydrochloric acid. The treatment temperature is 18 - 30 °C and the time is 1 - 2 minutes;

[0085] S15 Flowing cold water cleaning: The same as S5; The purpose of this step is to clean the activation solution residue adhering to the part surface after activation and provide a clean surface for nickel chloride plating;

[0086] S16 Nickel chloride plating: When the steel part material is stainless steel or high carbon steel, perform nickel chloride plating in a nickel plating tank with an electrolyte composition of 200 - 250 g / L of nickel chloride and 90 - 120 g / L of pure salt. The treatment temperature is 18 - 30 °C, the current density is 5 - 10 A / dm², the non - current time is 2 minutes, the current - carrying time is 3 - 4 minutes, and Sa:Sk = 2:1;

[0087] S17 Still cold water cleaning after nickel chloride plating: Immerse the part in a still cold water tank and clean it 3 - 5 times, with each cleaning time being 1 - 2 minutes;

[0088] S18 Flowing cold water cleaning after nickel chloride plating: The same as S5; The purpose of this step is to clean the nickel chloride plating residue adhering to the part surface after nickel chloride plating and provide a clean surface for nickel plating;

[0089] S19 Nickel plating: When the steel part material is carbon steel, low - carbon steel, or stainless steel and high - carbon steel that has undergone nickel chloride plating, perform nickel plating in a nickel plating tank with an electrolyte composition of 140 - 170 g / L of nickel sulfate, 10 - 15 g / L of nickel chloride hexahydrate, 130 - 170 g / L of sodium sulfate, and 20 - 30 g / L of boric acid. The nickel plating temperature is 28 - 35 °C, the current density is 0.4 - 0.6 A / dm², the time is 45 - 60 minutes, the pH value is 4 - 6, and Sa:Sk = 2:1;

[0090] S20, Cleaning with non-flowing cold water: The same as S17; The purpose of this step is that the non-flowing water wash allows the solutes in the nickel plating solution to fully diffuse into the water in a relatively static environment, giving more time to mix and dissolve with the water, thus better removing the residual nickel plating solution on the part surface;

[0091] S21, Cleaning with flowing cold water: The same as S5; The purpose of this step is to further rinse off the residual nickel plating solution and impurities on the part surface using the fluidity of water, providing a clean surface for the inspection of the nickel plating layer and cadmium plating;

[0092] S22, Inspecting the nickel plating layer: Inspect the nickel plating layer of the part on the inspection table. The appearance of the nickel plating layer should be smooth, without bulging, bubbles, and delamination, and no missing plating is allowed;

[0093] The desktop of the inspection table should be covered with polyvinyl chloride plastic;

[0094] S23, Cadmium plating: Conduct cadmium plating in a cadmium plating bath with an electrolyte composition of 40 - 500 grams per liter of cadmium sulfate, 48 - 52 grams per liter of sodium sulfate, 100 - 120 grams per liter of sodium sulfate, and 3 - 5 grams per liter of OP-7 emulsifier. The cadmium plating temperature is 18 - 30 degrees Celsius, the current density is 1.5 - 2.5 amperes per square decimeter, the time is 6 - 10 minutes, and Sa:Sk = 2:1;

[0095] S24, Cleaning with non-flowing cold water: The same as S17; The purpose of this step is that the non-flowing water wash allows the solutes in the cadmium plating solution to fully diffuse into the water in a relatively static environment, giving more time to mix and dissolve with the water, thus better removing the residual cadmium plating solution on the part surface;

[0096] S25, Cleaning with flowing cold water: The same as S5; The purpose of this step is to further rinse off the residual cadmium plating solution and impurities on the part surface using the fluidity of water, providing a clean surface for passivation;

[0097] S26, Primary passivation: Conduct chemical passivation in a passivation bath with a solution composition of 100 - 150 grams per liter of potassium dichromate, 10 - 15 grams per liter of sulfuric acid, and 10 - 15 grams per liter of hydrochloric acid. The passivation temperature is 18 - 30 degrees Celsius, and the passivation is carried out 3 - 5 times;

[0098] S27, Cleaning with non-flowing cold water: The same as S17; The purpose of this step is that the non-flowing water wash allows the solutes in the passivation solution to fully diffuse into the water in a relatively static environment, giving more time to mix and dissolve with the water, thus better removing the residual passivation solution on the part surface;

[0099] S28, Flowing cold water cleaning: Immerse the parts in a non-flowing distilled water tank and clean them 3 - 5 times, with each cleaning time being 0.5 - 1 minute; The purpose of this step is to further rinse off the residual passivation solution and impurities on the surface of the parts by using the fluidity of water, providing a clean surface for isolation;

[0100] S29, De-isolation: Conduct de-isolation treatment in a de-isolation tank with a solution composition of 30 - 50 grams per liter of calcined sodium carbonate, at a treatment temperature of 80 - 100 degrees Celsius, for a time until the isolation glue is completely removed;

[0101] S30, Flowing hot water cleaning: The same as S4; The purpose of this step is to effectively dissolve the possible residual isolation solution on the surface of the parts by using flowing hot water;

[0102] S31, Flowing cold water cleaning: The same as S5; The purpose of this step is to further rinse off the residual isolation solution and impurities on the surface of the parts by using the fluidity of water, providing a clean surface for re-passivation

[0103] S32, Re-passivation: The same as S26;

[0104] S33, Non-flowing cold water cleaning: The same as S17;

[0105] S34, Flowing cold water cleaning: The same as S5;

[0106] S35, Non-flowing distilled water cleaning: Immerse the parts in a non-flowing distilled water tank and clean them 3 - 5 times, with each cleaning time being 0.5 - 1 minute; The purpose of this step is to further dissolve the possible residual impurities on the surface of the parts by using the high solubility of distilled water, and using distilled water can avoid the contamination of the surface of the parts by impurities in the water, ensuring the cleanliness of the surface of the parts, which is beneficial to the subsequent treatment steps

[0107] S36, Drying: The same as S6;

[0108] S37, Inspect the cadmium plating layer: Inspect the cadmium plating layer on the inspection table. The appearance of the nickel plating layer should be smooth, without bulging or delamination, and in a fine crystal shape;

[0109] The desktop of the inspection table should be covered with polyvinyl chloride plastic;

[0110] S38, Disassembly: Remove the parts from the copper fixture on the disassembly table and store them in a dry and clean environment;

[0111] The desktop of the disassembly table should be covered with polyvinyl chloride plastic;

[0112] S39, Annealing: Heat the parts in a drying oven for annealing. The annealing temperature is 350 - 370 degrees Celsius, and the annealing time is 60 - 90 minutes. The annealing time starts from the moment when the annealing temperature is reached;

[0113] S40, Acceptance inspection: Inspect the appearance of the nickel-cadmium coating, its adhesion strength to the base metal of the part, and its microhardness on the inspection table.

[0114] The desktop of the inspection table should be covered with polyvinyl chloride plastic.

[0115] The present invention can significantly improve the stability of the coating quality, ensuring that the coating can maintain good performance under various complex environments; can effectively enhance the bonding force between the coating and the base metal, making it not easy to peel off, thereby extending the service life of the part; can precisely control the process parameters to ensure that each production link can be carried out according to the preset standards, thus improving the consistency and reliability of the product; can improve production efficiency, reduce waste in the production process, and lower production costs; and should also have good environmental protection performance to reduce environmental pollution. By developing this new nickel-cadmium plating method, the surface quality and performance of steel parts used in gas turbines can be effectively improved. This not only helps to improve the operating efficiency and reliability of gas turbines, but also reduces maintenance costs and extends their service life.

[0116] The innovations of the present invention are reflected in the following aspects:

[0117] Strict pre-plating treatment: Through pre-plating inspection, it is ensured that the surface of the part is free of defects such as oxide films, scale, and corrosion, providing guarantee for the quality of the subsequent coating. When clamping, it is ensured that the solution can enter all the holes and recesses of the part without forming bubbles, which helps to improve the uniformity of the coating.

[0118] Optimization of degreasing treatment: By combining chemical degreasing and electro-chemical degreasing, the oil and impurities on the surface of the part can be removed more effectively. The solution with specific components and concentrations in chemical degreasing, as well as the appropriate treatment temperature and time, can improve the degreasing effect. The precise control of the solution components, treatment temperature, current density, and time in electro-chemical degreasing further ensures the thoroughness of degreasing, thereby improving the bonding force of the coating.

[0119] Precise control of nickel plating and cadmium plating processes: According to the different materials of steel parts, corresponding nickel plating process parameters are formulated respectively. For example, stainless steel or high carbon steel uses nickel chloride plating, and carbon steel, low carbon steel, etc. use another nickel plating method, and the current density, time, temperature, etc. are precisely controlled. In the cadmium plating process, the strict requirements for the electrolyte composition, cadmium plating temperature, current density, and time ensure the quality and performance of the cadmium plating layer.

[0120] Improvement of cleaning and passivation steps: Multiple times of flowing hot water cleaning, flowing cold water cleaning, non-flowing cold water cleaning, and distilled water cleaning ensure the cleanliness of the part surface and reduce the influence of impurities on the coating. The steps of primary passivation and re-passivation further improve the corrosion resistance and oxidation resistance of the coating.

[0121] Specific requirements for equipment and tools: Specific requirements are put forward for the materials and structures of equipment such as degreasing tanks, hot water tanks, cold water tanks, nickel plating tanks, cadmium plating tanks, etc., such as stainless steel materials, side air extraction ports, compressed air agitators, etc., which ensure the stability and reliability of the equipment and contribute to improving the stability of the nickel-cadmium plating process. The alternative choices for copper tooling and the requirements for compressed air and drying ovens also reflect the attention and optimization of process details.

[0122] Comprehensiveness of quality inspection: Inspection links are set in multiple steps, such as the inspection of nickel plating layer and cadmium plating layer, acceptance inspection, etc., which can timely detect problems and make adjustments to ensure that the product quality meets the requirements.

[0123] Improve the pickling step: Steps such as chemical degreasing, isolation, and de-isolation are added to make the pickling process more perfect and better meet the pickling requirements of titanium alloy blades for gas turbines.

[0124] Optimize the solution formula: The components of the pickling solution and degreasing solution are optimized to improve the pickling and degreasing effects.

[0125] Strictly control parameters: Parameters such as temperature and time in each step are strictly controlled to ensure the stability and reliability of the pickling process.

[0126] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for nickel-cadmium plating of steel parts for gas turbines, characterized in that: The following steps are involved: S1, inspection before plating: before nickel-cadmium plating, visually inspect the surface condition of the parts on the inspection table. The surface of the parts shall be free of oxide film, oxide scale, corrosion, indentation, burr, scratch, dent, burn, pore and abrasion; S2, clamping: clamp the parts onto the copper fixture. After clamping, ensure that the solution can enter all holes and recesses of the parts, and no bubbles should be formed on the surface and around the parts; S3, chemical degreasing: degreasing in a degreasing tank containing 30-50 g / L trisodium phosphate and 3-5 g / L OP-7 emulsifier, at a temperature of 60-80 degrees Celsius for 10-20 minutes; S4, running hot water cleaning: immerse the parts in a running hot water tank at 60 to 90 degrees Celsius for 3 to 5 times, each cleaning time is 1 to 2 minutes; S5, running cold water cleaning: immerse the parts in a running cold water tank for 3 to 5 times, each cleaning time is 1 to 2 minutes; S6, Drying: Use clean compressed air to dry the moisture on the surface of the parts; S7, disassembly: remove the parts from the copper tooling on the disassembly table; S8， Isolation: Apply an isolation glue with a composition and mass fraction of 20% to 30% ceresin, 40% to 50% paraffin and 20% to 40% turpentine to the surface that does not need cadmium nickel plating, and the treatment temperature is 70 to 90 degrees Celsius; S9, use a scraper to remove the isolation glue flow marks on the surface of the part, and then wipe the surface to be plated with cotton cloth dipped in heavy refined paraffin; S10, Isolation inspection: Check whether the isolation glue completely covers the surface of the parts that do not need to be plated, and there should be no isolation glue residue on the surface of the parts that need to be plated; S11 clamping: same as S2; S12, electrochemical degreasing: degreasing in an electrochemical degreasing tank with a solution composition of 150-170 g / L sodium hydroxide, 80-100 g / L calcined sodium carbonate and 10-30 g / L water glass, at a treatment temperature of 18-30 degrees Celsius, a current density of 3-10 amperes per square decimeter, an anode holding time of 2-3 minutes, a cathode holding time of 15-20 minutes, and Sa:Sk=1:1, wherein Sa is the anode surface area and Sk is the cathode surface area; S13 running cold water cleaning: same as S5; S14, activation: activation treatment is performed in an activation tank containing 100 to 150 g / L of hydrochloric acid at a temperature of 18 to 30 degrees Celsius for 1 to 2 minutes; S15, running cold water cleaning: same as S5; S16, nickel chloride plating: When the steel parts are made of stainless steel or high carbon steel, nickel chloride plating is carried out in a nickel plating tank with an electrolyte composition of 200-250 grams per liter of nickel chloride and 90-120 grams per liter of pure salt, with a processing temperature of 18-30 degrees Celsius, a current density of 5-10 amperes per square decimeter, a no-current time of 2 minutes, a current-carrying time of 3-4 minutes, and Sa:Sk=2:1; S17, non-flowing cold water cleaning after nickel chloride plating: immerse the parts in a non-flowing cold water tank for cleaning 3 to 5 times, each cleaning time is 1 to 2 minutes; S18, running cold water cleaning after nickel chloride plating: same as S5; S19, nickel plating: When the steel parts are made of carbon steel, low carbon steel, or stainless steel and high carbon steel that have been subjected to chloride nickel plating, nickel plating is performed in a nickel plating bath having an electrolyte composition of 140-170 g / L nickel sulfate, 10-15 g / L nickel chloride hexahydrate, 130-170 g / L sodium sulfate, and 20-30 g / L boric acid, with a nickel plating temperature of 28-35 degrees Celsius, a current density of 0.4-0.6 amperes per square decimeter, a time of 45-60 minutes, a pH value of 4-6, and Sa:Sk=2:1; S20, still water cleaning: same as S17; S21, running cold water cleaning: same as S5; S22, check the nickel plating: check the nickel plating of the parts on the inspection table. The nickel plating should be smooth, without bulging, bubbles and delamination, and no missing plating is allowed; S23, cadmium plating: cadmium plating is carried out in a cadmium plating bath having an electrolyte composition of 40-500 g / L cadmium sulfate, 48-52 g / L sodium sulfate, 100-120 g / L sodium sulfate, and 3-5 g / L OP-7 emulsifier, at a cadmium plating temperature of 18-30 degrees Celsius, a current density of 1.5-2.5 amperes per square decimeter, a time of 6-10 minutes, and Sa:Sk=2:1; S24, still cold water cleaning: same as S17; S25, running cold water cleaning: same as S5; S26, primary passivation: chemical passivation in a passivation tank containing 100-150 g / L potassium dichromate, 10-15 g / L sulfuric acid, and 10-15 g / L hydrochloric acid, at a passivation temperature of 18-30 degrees Celsius, for 3-5 times; S27, still cold water cleaning: same as S17; S28, flowing cold water cleaning: immerse the parts in a non-flowing distilled water tank for cleaning 3 to 5 times, each cleaning time is 0.5 to 1 minute; S29, de-isolating: performing de-isolating treatment in a de-isolating tank containing 30 to 50 grams per liter of calcined sodium carbonate at a temperature of 80 to 100 degrees Celsius for a period of time until the isolating glue is completely removed; S30, running hot water cleaning: same as S4; S31, running cold water cleaning: same as S5; S32, passivation again: same as S26; S33, still cold water cleaning: same as S17; S34, running cold water cleaning: same as S5; S35, non-flowing distilled water cleaning: immerse the parts in a non-flowing distilled water tank for cleaning 3 to 5 times, each cleaning time is 0.5 to 1 minute; S36, Drying: Same as S6; S37, Check the cadmium plating layer: Check the cadmium plating layer on the inspection table. The nickel plating layer should be smooth, without bulging or delamination, and in the form of fine crystals; S38, Disassembly: Remove the parts from the copper tooling on the disassembly table and store in a dry, clean environment; S39, annealing: anneal the parts in a drying oven at a temperature of 350 to 370 degrees Celsius for 60 to 90 minutes, starting from the time the annealing temperature is reached; S40, Acceptance inspection: Check the appearance of the nickel-cadmium coating, its adhesion strength to the base metal of the part, and its microhardness on the inspection table.

2. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The inspection tables in S1, S22, S37, S40 and the disassembly tables in S7, S38 should be covered with polyvinyl chloride plastic.

3. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The degreasing tank in S3 and the flowing hot water tank in S4 are made of stainless steel, and are structurally provided with side air extraction ports, serpentine steam pipes with a pressure resistance rating of 0.3 MPa, and compressed air agitators with a working pressure greater than 0.2 MPa.

4. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The flowing cold water tank in S5 should be made of stainless steel, and the structure should be equipped with a cleaning tank made of polyvinyl chloride plastic material and a compressed air agitator with a working pressure greater than 0.2 MPa.

5. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The compressed air in S6 should be blown on the mirror surface or filter paper for at least 3 to 4 minutes every month, and there should be no moisture or oil residue on the mirror surface or filter paper.

6. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The electrochemical degreasing tank in S12 is made of stainless steel and is structurally provided with a side air extraction port and a current reversing device.

7. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The activation tank in S14 and the passivation tank in S26 are made of stainless steel, and are structurally provided with a polyvinyl chloride plastic lining, a side air suction port, and a compressed air agitator with a working pressure greater than 0.2 MPa.

8. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The nickel plating tanks in S16 and S19 and the cadmium plating tank in S23 are made of stainless steel and have a polyvinyl chloride plastic lining and a side exhaust port.

9. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The non-flowing cold water tank in S17 and the non-flowing distilled water tank in S35 are made of stainless steel, and are structurally provided with a cleaning basket made of polyvinyl chloride plastic material.

10. The method for nickel-cadmium plating of steel parts for gas turbines according to claim 1, characterized in that: The drying oven in the S39 can automatically adjust the temperature within a temperature difference of ±10 degrees Celsius to ensure that the parts are heated evenly.

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