Electrochemical deposition chromium surface strengthening method for aviation plunger seat

Abstract

The invention belongs to the technical field of electroplating alloy processes, and relates to an aviation plunger seat electrochemical deposition chromium surface strengthening method which comprises the following steps: step 1, organic solvent oil removal: performing oil removal treatment on an aviation plunger seat in an organic solvent, and cleaning for a period of time; 2, weak corrosion is conducted, specifically, the aviation plunger seat is subjected to weak corrosion treatment in an acid solution; 3, nickel pre-plating is conducted, specifically, nickel plating is conducted on the surface of the aviation plunger seat for a period of time; 4, hard chromium plating is conducted, specifically, hard chromium plating is conducted on the aviation plunger seat in a chromic anhydride and sulfuric acid mixed solution; 5, hydrogen removal treatment is conducted, specifically, hydrogen removal treatment is conducted on the aviation plunger seat in a high-temperature environment; according to the method, the qualification rate of the chromium plating layer is increased by 90%, and the strengthening hardness can reach HRC 55-60.

Description

Technical Field

[0001] The invention belongs to the technical field of electroplating alloy process, and in particular relates to a method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium. Background Art

[0002] A certain type of engine driven pump assembly is a newly developed airborne equipment to meet the needs of early warning patrols and long-distance / transfer missions on aircraft, taking into account the use environment on land and on ships, and meeting the pressure and flow requirements of aircraft hydraulic system users. The product directly extracts mechanical energy from the engine transmission casing to provide hydraulic energy of a certain pressure and flow to the No. 1 hydraulic system user in the engine driven pump assembly. The oil distribution plate and plunger are mostly strengthened with bearing steel as a whole, which improves the tensile strength on the one hand and the wear resistance on the other. The inner ring and outer ring of the bearing serve as rolling runways, and there is a problem of matching the hardness of the rollers.

[0003] Parts such as the spindle and the swash plate require good local wear resistance while maintaining good toughness in the core, so local carburizing and nitriding treatments are often used. Carburizing and nitriding require protective measures, so the process is complicated and the cycle is long. Therefore, if chrome plating can be used instead of carburizing and nitriding, the processing cycle can be greatly saved. However, due to the surface shape of the involute spline, it is difficult to ensure the thickness and uniformity of the coating on the spline that needs to be strengthened on the spindle. Since the swash plate and the plunger seat will be subjected to a large impact force during the dynamic switching process, according to historical experience and reference to similar foreign products, high-frequency quenching is generally used to ensure that the carburized layer is thick enough, and the thickness of the coating will not exceed 0.2mm. It may peel off under the impact force, so the surface of the plunger seat that is subjected to impact needs to be strengthened with chrome plating.

[0004] Currently, there are very few methods suitable for strengthening the surface of the plunger seat. The main electroplating process for the common chrome plating protective layer is the direct current chrome plating process, which has excellent plating adhesion and high pass rate and can be used in industry. Summary of the invention

[0005] In order to solve the problem that there are very few methods suitable for strengthening the surface of the plunger seat in the prior art, the thickness of the common carburizing and nitriding protective layer coating will not exceed 0.2mm, and there are technical problems such as thin carburizing layer and easy wear and failure, the present invention provides a method for strengthening the surface of the aviation plunger seat by electrochemical deposition of chromium. The plunger seat strengthening layer prepared by this process has a bright surface, a compact structure, fine and uniform crystals, and has good wear resistance and corrosion resistance after dehydrogenation treatment.

[0006] The technical solution is as follows:

[0007] A method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium comprises the following steps:

[0008] Step 1, degreasing with organic solvent: the aviation plunger seat is degreased in an organic solvent and cleaned for a period of time;

[0009] Step 2, weak corrosion: the aviation plunger seat is subjected to weak corrosion treatment in an acid solution;

[0010] Step 3, pre-nickel plating: nickel plating is performed on the surface of the aviation plunger seat for a period of time;

[0011] Step 4, hard chrome plating: hard chrome plating is performed on the aviation plunger seat in a mixed solution of chromic anhydride and sulfuric acid;

[0012] Step 5, dehydrogenation treatment: dehydrogenation treatment is performed on the aviation plunger seat in a high temperature environment.

[0013] Furthermore, in step 1, the aviation plunger seat is degreased in gasoline, and the cleaning time is 2-3 minutes.

[0014] Further, in step 2, the aviation plunger seat is weakly corroded in H2SO4 or HCl solution. When H2SO4 solution is used for weak corrosion, the density of H2SO4 is ρ=1.84g / mL, and the volume is 100-150ml. When HCl solution is used for weak corrosion, the density of HCl is ρ=1.19g / ml, and the volume is 100-150ml. The working temperature for weak corrosion using H2SO4 solution or HCl solution is 18-25°C, and the working time is 30-120s.

[0015] Furthermore, in step 2, the working temperature for weak corrosion using H2SO4 solution or HCl solution is 18-25°C, and the working time is 60-120s.

[0016] Further, step 3, the pre-nickel plating is specifically carried out in a mixed solution of NiCl26H2O and HCl, the concentration of NiCl26H2O is 250-350g / L, the density of HCl is ρ=1.19g / cm3, the concentration is 120-180g / L, the pre-nickel plating working temperature is 18-25°C, the working time is 2-3min after the part is put into the tank, the cathode plating is 2-3min, and the current density is 4-8A / dm 2 , the anode material is pure nickel plate.

[0017] Further, in step 3, the pre-nickel plating working temperature is 18-25°C, the working time is 3-5 minutes after the parts are put into the tank, the cathode plating is 3-5 minutes, and the current density is 4-8A / dm 2 , the anode material is pure nickel plate.

[0018] Further, in step 4, hard chrome plating is specifically carried out in a mixed solution of CrO3, H2SO4, and Cr2O3, the CrO3 concentration is 200-250g / L, the H2SO4 concentration is 2.0-2.5g / L, the Cr2O3 concentration is 3-5g / L, the hard chrome plating working temperature is 50-60°C, and the current density is 25-35A / dm 2 The anode is made of titanium-platinum rod; the titanium-platinum rod is made by platinum-plating 1-2μm on the surface of the titanium alloy anode.

[0019] Furthermore, in step 4, the anode is a lead rod.

[0020] Further, step 5, dehydrogenation treatment: carried out in a box-type resistance furnace, with an operating temperature of 190±10°C and a working time of 1h30min.

[0021] Further, step 5, dehydrogenation treatment: carried out in a box-type resistance furnace, with an operating temperature of 190±10°C and a working time of 2h.

[0022] Beneficial effects of the present invention:

[0023] 1. The present invention adopts a method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium based on an electroplating chromium system, the qualified rate of the chromium plating layer is increased by 90%, and the hardness can reach HRC 55-60;

[0024] 2. The electrochemical deposition chromium plating process provided by the present invention removes the oxide film formed on the surface of the plunger seat through weak corrosion, hot water / cold water washing, pre-nickel plating, and pre-sets the intermediate layer to achieve the plunger seat chromium plating process, which significantly improves the problems of insufficient bonding strength of the chrome plating layer of the plunger seat and coating peeling; the risk of hydrogen embrittlement caused by weak corrosion after dehydrogenation treatment is tested for the bonding strength of the coating. The process conditions are 190±10℃, heat preservation for 2h, and air cooling with the furnace. The wear resistance and hardness of the plunger seat are significantly improved after chrome plating. The strengthening layer prepared by the invention is suitable for anti-corrosion protection layer and can also be used as a wear-resistant protective layer;

[0025] 3. The electrochemical deposition chromium plating process adopted by the present invention has a wide range of process parameters, is simple to operate, and has conditions for batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] According to the demand of applying the chrome plating strengthening process of the plunger seat to actual production, the present invention controls a single electroplating parameter to efficiently and stably obtain a plunger seat strengthening layer whose comprehensive properties such as hardness and bonding strength meet the standard requirements. The hardness after strengthening can reach HRC 55-60. The plunger seat strengthening process is applied to the aviation and aerospace industry systems, which meets the quality control requirements and plays an important role in the electroplating industry and the aviation plunger seat industry.

[0028] An embodiment of the present invention is:

[0029] Step 1, degreasing with organic solvents: Degreasing the aviation plunger seat in gasoline, the cleaning time is 2-3 minutes.

[0030] Step 2, weak corrosion: the aviation plunger seat is weakly corroded in an acidic solution; the aviation plunger seat is weakly corroded in a H2SO4 or HCl solution. When the H2SO4 solution is used for weak corrosion, the density of H2SO4 is ρ=1.84g / mL, and the volume is 100-150ml. When the HCl solution is used for weak corrosion, the density of HCl is ρ=1.19g / ml, and the volume is 100-150ml. The working temperature for weak corrosion using H2SO4 solution or HCl solution is 18-25°C, and the working time is 30-120s or 60-120s.

[0031] Step 3, pre-nickel plating: nickel plating is performed on the surface of the aviation plunger seat for a period of time; specifically, it is performed in a mixed solution of NiCl26H2O and HCl, the concentration of NiCl26H2O is 250-350g / L, the density of HCl is ρ=1.19g / cm3, the concentration is 120-180g / L, the pre-nickel plating working temperature is 18-25°C, the working time is 2-3min after the part is put into the tank, the cathode plating is 2-3min, and the current density is 4-8A / dm 2 , the anode material is pure nickel plate.

[0032] Or the pre-nickel plating working temperature is 18-25℃, the working time is 3-5min after the parts are put into the tank, the cathode plating is 3-5min, and the current density is 4-8A / dm 2 , the anode material is pure nickel plate.

[0033] Step 4, hard chrome plating: hard chrome plating is performed on the aviation plunger seat in a mixed solution of chromic anhydride and sulfuric acid; specifically, it is performed in a mixed solution of CrO3, H2SO4, and Cr2O3, the CrO3 concentration is 200-250g / L, the H2SO4 concentration is 2.0-2.5g / L, the Cr2O3 concentration is 3-5g / L, the hard chrome plating working temperature is 50-60℃, and the current density is 25-35A / dm 2 The anode is made of titanium-platinum rod or lead rod; the titanium-platinum rod is a titanium alloy anode with platinum plated on the surface with 1-2μm.

[0034] Step 5, dehydrogenation treatment: Dehydrogenation treatment is performed on the aviation plunger seat in a high temperature environment, specifically in a box-type resistance furnace, with an operating temperature of 190±10°C and a working time of 1h30min or 2h.

[0035] A second embodiment of the present invention is:

[0036] A method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium comprises the following steps:

[0037] Step 1: Check and accept the produced aviation plungers, and proceed to the next step if they meet the quality requirements;

[0038] Step 2, degreasing with organic solvents: The aviation plunger seat is degreased in gasoline, and the cleaning time is 2-3 minutes.

[0039] Step 3: After the organic solvent is removed from the oil, use hot water and cold water to remove the organic solvent on the surface of the aviation plunger seat. Check the water film continuity on the surface of the parts after hot water and cold water washing. If the requirements are met, proceed to the next step;

[0040] Step 4, weak corrosion: the aviation plunger seat is weakly corroded in an acidic solution; the aviation plunger seat is weakly corroded in a H2SO4 or HCl solution. When the H2SO4 solution is used for weak corrosion, the density of H2SO4 is ρ=1.84g / mL, and the volume is 100-150ml. When the HCl solution is used for weak corrosion, the density of HCl is ρ=1.19g / ml, and the volume is 100-150ml. The working temperature for weak corrosion using H2SO4 solution or HCl solution is 18-25°C, and the working time is 30-120s or 60-120s.

[0041] Step 5: After the weak corrosion is completed, use hot water washing and cold water washing to remove the acidic solution on the surface of the aviation plunger seat;

[0042] Step 6, pre-nickel plating: nickel plating is performed on the surface of the aviation plunger seat for a period of time; specifically, it is performed in a mixed solution of NiCl26H2O and HCl, the concentration of NiCl26H2O is 250-350g / L, the density of HCl is ρ=1.19g / cm3, the concentration is 120-180g / L, the pre-nickel plating working temperature is 18-25°C, the working time is 2-3min after the part is put into the tank, the cathode plating is 2-3min, and the current density is 4-8A / dm 2 , the anode material is pure nickel plate.

[0043] Or the pre-nickel plating working temperature is 18-25℃, the working time is 3-5min after the parts are put into the tank, the cathode plating is 3-5min, and the current density is 4-8A / dm2 , the anode material is pure nickel plate.

[0044] Step 7: After the pre-nickel plating is completed, the mixed solution of NiCl26H2O and HCl on the surface of the aviation plunger seat is removed by cold water washing;

[0045] Step 8, hard chrome plating: hard chrome plating is performed on the aviation plunger seat in a mixed solution of chromic anhydride and sulfuric acid; specifically, it is performed in a mixed solution of CrO3, H2SO4, and Cr2O3, the concentration of CrO3 is 200-250g / L, the concentration of H2SO4 is 2.0-2.5g / L, the concentration of Cr2O3 is 3-5g / L, the working temperature of hard chrome plating is 50-60℃, and the current density is 25-35A / dm 2 The anode is made of titanium-platinum rod or lead rod; the titanium-platinum rod is a titanium alloy anode with platinum plated on the surface with 1-2μm.

[0046] Step 9: recovering the mixed solution of CrO3, H2SO4, and Cr2O3, and then removing the mixed solution of CrO3, H2SO4, and Cr2O3 on the surface of the aviation plunger seat by washing, and performing drying treatment;

[0047] Step 10, dehydrogenation treatment: Dehydrogenation treatment is performed on the aviation plunger seat in a high temperature environment, specifically in a box-type resistance furnace, with an operating temperature of 190±10°C and a working time of 1h30min or 2h.

[0048] Step 11, inspect the surface of the aviation plunger seat.

[0049] The present invention adopts a method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium based on an electrochromium plating system, and the qualified rate of the chromium plating layer is increased by 90%, and the hardness can reach HRC 55-60; the electrochemical deposition chromium plating process provided by the present invention removes the oxide film formed on the surface of the plunger seat by weak corrosion, hot water / cold water washing, and pre-nickel plating, and realizes the plunger seat chromium plating process by pre-setting an intermediate layer, which significantly improves the problems of insufficient bonding force and peeling of the chromium plating layer of the plunger seat; the risk of hydrogen embrittlement caused by weak corrosion after dehydrogenation treatment is tested for the bonding force of the plating layer. The process conditions are 190±10℃, heat preservation for 2h, and air cooling with the furnace. The wear resistance and hardness of the plunger seat are significantly improved after chromium plating strengthening. The strengthening layer prepared by the invention is suitable for an anti-corrosion protective layer, and can also be used as a wear-resistant protective layer; the electrochemical deposition chromium plating process adopted by the present invention has a wide range of parameters, simple operation, and batch production conditions.

Claims

1. A method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium, characterized in that: The following steps are involved: Step 1, degreasing with organic solvent: the aviation plunger seat is degreased in an organic solvent and cleaned for a period of time; Step 2, weak corrosion: the aviation plunger seat is subjected to weak corrosion treatment in an acid solution; Step 3, pre-nickel plating: nickel plating is performed on the surface of the aviation plunger seat for a period of time; Step 4, hard chrome plating: hard chrome plating is performed on the aviation plunger seat in a mixed solution of chromic anhydride and sulfuric acid; Step 5, dehydrogenation treatment: dehydrogenation treatment is performed on the aviation plunger seat in a high temperature environment.

2. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 1, characterized in that: In step 1, the aviation plunger seat is degreased in gasoline, and the cleaning time is 2-3 minutes.

3. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 2, characterized in that: In step 2, the aviation plunger seat is weakly corroded in H2SO4 or HCl solution. When H2SO4 solution is used for weak corrosion, the density of H2SO4 is ρ=1.84g / mL, and the volume is 100-150ml. When HCl solution is used for weak corrosion, the density of HCl is ρ=1.19g / ml, and the volume is 100-150ml. The working temperature for weak corrosion using H2SO4 solution or HCl solution is 18-25°C, and the working time is 30-120s.

4. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 3, characterized in that: In step 2, the working temperature for weak corrosion using H2SO4 solution or HCl solution is 18-25°C, and the working time is 60-120s.

5. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 4, characterized in that: Step 3, the pre-nickel plating is specifically carried out in a mixed solution of NiCl26H2O and HCl, the concentration of NiCl26H2O is 250-350g / L, the density of HCl is ρ=1.19g / cm3, the concentration is 120-180g / L, the pre-nickel plating working temperature is 18-25°C, the working time is 2-3min after the part is put into the tank, the cathode plating is 2-3min, and the current density is 4-8A / dm 2 , the anode material is pure nickel plate.

6. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 5, characterized in that: Step 3: The working temperature of pre-nickel plating is 18-25℃, the working time is 3-5min after the parts are put into the tank, and the cathode plating time is 3-5min. The current density is 4-8A / dm 2 , the anode material is pure nickel plate.

7. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 6, characterized in that: Step 4, hard chrome plating is specifically carried out in a mixed solution of CrO3, H2SO4, and Cr2O3, with a CrO3 concentration of 200-250g / L, a H2SO4 concentration of 2.0-2.5g / L, a Cr2O3 concentration of 3-5g / L, a hard chrome plating working temperature of 50-60°C, and a current density of 25-35A / dm 2 The anode is made of titanium-platinum rod; the titanium-platinum rod is made by platinum-plating 1-2μm on the surface of the titanium alloy anode.

8. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 7, characterized in that: In step 4, a lead rod is used as the anode.

9. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 7, characterized in that: Step 5, dehydrogenation treatment: carried out in a box-type resistance furnace, with an operating temperature of 190±10°C and a working time of 1h30min.

10. The method for strengthening the surface of an aviation plunger seat by electrochemical deposition of chromium according to claim 9, characterized in that: Step 5, dehydrogenation treatment: carried out in a box-type resistance furnace with an operating temperature of 190±10°C and a working time of 2h.

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