A method for preparing a gold-plated layer with a long current-carrying wear life in a space environment

Abstract

The present invention provides a method for preparing a gold-plated layer with a long current-carrying wear life in a space environment, comprising the following steps: step 1, degreasing with an organic solvent; step 2, applying tooling; step 3, chemical degreasing; step 4; step 5, nickel electroplating; step 6, gold electroplating; step 7, hot pure water washing; step 8, drying. The present invention provides a method for preparing a gold-plated layer with a long current-carrying wear life in a space environment, which solves the problem that the existing conductive slip ring plating cannot meet the high load, large load and long life requirements of the gold-plated layer on the surface of the conductive slip ring busbar in space. The present invention utilizes a high-uniformity busbar electroplating gold device and a double-pulse electroplating gold technology to prepare a gold-plated layer with good bonding force, uniformity, conductivity, high hardness and low wear rate.

Description

Technical Field

[0001] The present invention relates to four fields, namely, materials science, electricity, physics and space environment science, and belongs to the category of interdisciplinary subjects. Specifically, the present invention relates to a method for preparing a gold-plated layer with a long current-carrying wear life in a space environment. The method uses electrochemical means to prepare a gold-plated layer with high hardness, fine grains and excellent current-carrying friction and wear performance in a space environment on the surface of a space conductive slip ring busbar. Background Art

[0002] As the core component of the satellite solar array drive mechanism (SADA) product, the conductive slip ring is mainly used to transmit electrical power and signals between the relatively rotating solar panels and the satellite body. The reliability of its operation is directly related to the energy supply of the entire satellite and the success or failure of the mission. It is the veritable "lifeline" of the spacecraft. In recent years, accidents of satellite failures caused by conductive slip ring failures have occurred frequently, causing huge losses to my country's aerospace and national defense forces. The most common cause of accidents is that the conductive slip ring busbar has a large amount of wear debris on the surface of the coating, which floats in the space environment, causing short circuits between different lines of the busbar, resulting in conductive slip ring failures.

[0003] In order to ensure stable electrical performance, the surface of the conductive slip ring busbar is generally plated with gold. Therefore, the wear resistance of the electroplated gold layer in the space environment determines the life of the conductive slip ring. Therefore, the gold plating process is an important process in the slip ring manufacturing process and is the core technology to ensure the reliable service of the slip ring. Therefore, it is very important to prepare a gold plating layer on the surface of the space conductive slip ring busbar that can meet the requirements of the stability of the current and signal input under vacuum conditions of the model product and the long service life of the conductive slip ring.

[0004] At present, there are two types of plating used in space conductive slip ring busbars. One is the surface electroplated palladium-nickel-gold plating, in which the gold layer is generally made of pure gold, which aims to improve the conductivity of the friction pair, and its wear resistance mainly depends on the high hardness of the underlying palladium-nickel plating; the other is the surface nickel-gold plating, in which the gold layer is hard gold, which improves the wear resistance to a certain extent while ensuring conductivity. The hardness of the plating is generally controlled at HV170~HV190, and the generated wear debris is restrained through structural design to prevent the wear debris from affecting the overall performance of the conductive slip ring.

[0005] The conductive slip ring is the lifeline of the satellite power subsystem. The surface gold plating layer must have good bonding force, uniformity, conductivity, high hardness and low wear rate. At the same time, with the continuous improvement of the use requirements of satellite model products, conventional electroplating hard gold can no longer meet the use requirements of high load, large load and long life. In order to ensure that the product meets the technical requirements mentioned above, the traditional practice is to use a DC gold-plated base alloy, add trace cobalt elements and complexing agents to the electroplating gold solution, realize the co-deposition of gold and trace elements, and improve the surface hardness and wear resistance of the gold plating layer. In order to ensure the consistency of the plating quality, the plating tank adopts a uniform electric field design and a design to enhance the fluidity of the plating solution.

[0006] With the development of double pulse electroplating technology, double pulse wear-resistant gold plating is increasingly widely used due to its excellent performance. As a new technology for controlling the performance of the coating outside the tank, double pulse electroplating mainly uses positive and negative current pulses to increase the activation polarization of the cathode and reduce the concentration polarization of the cathode. Therefore, the peak current of double pulse electroplating can be much higher than the average current, which makes the formation rate of crystal nuclei higher than the growth rate of crystals, making the coating crystallization refined, tightly arranged, with fewer pores and increased hardness, thereby greatly improving the physical and chemical properties of the deposited layer.

[0007] The hardness of the DC electroplated gold layer is about HV190, the roughness is Ra<0.4, and the unit cell size is about 6μm. -4 Under the conditions of Pa, temperature 80℃, and load 0.5N, the average friction coefficient of the DC electroplated gold layer is about 0.30, and the wear rate is 4.84×10 -6 mg / min.

[0008] The double pulse electroplated gold layer has a hardness of about HV210, a roughness of Ra<0.4, and a cell size of about 3μm. -4 Under the conditions of Pa, temperature 80℃, and load 0.5N, the average friction coefficient of the double-pulse electroplated gold layer is about 0.28, the wear scar is narrow and shallow, and the wear rate is 1.21×10 -6 The reason is that the electrochemical polarization is increased and the concentration polarization is reduced in the double-pulse gold electroplating process, which makes the coating crystals more refined, the roughness is reduced, and the unit cell size is reduced. Under the same friction pair and working conditions, as the coating roughness decreases, the unit cell size decreases, and the wear resistance of the coating is improved.

[0009] This technology solves the problem of poor wear resistance of the friction pair system in the conductive slip ring assembly. The conductive slip ring assembly manufactured using this technology has passed the electrical performance test and life test verification, and meets the application needs of satellite model products for long-term reliable operation in orbit. The conductive slip ring system with the conductive slip ring assembly as the core has been successfully used in the production of model products. Summary of the invention

[0010] The present invention provides a method for preparing a gold-plated layer with a long current-carrying wear life in a space environment, which solves the problem that the existing conductive slip ring plating cannot meet the use requirements of high load, large load and long life of the gold-plated layer on the surface of the space conductive slip ring busbar. The present invention uses a high-uniformity busbar electroplating gold device and a double-pulse electroplating gold technology to prepare a gold-plated layer with good bonding force, uniformity, conductivity, high hardness and low wear rate.

[0011] The technical solution provided by the present invention is as follows:

[0012] A method for preparing a gold-plated layer with a long current-carrying wear life in a space environment comprises the following steps:

[0013] Step 1, degreasing with organic solvent: degreasing the parts with organic solvent;

[0014] Step 2, tooling: clamp the parts processed in step 1 to the parts installation position in the high uniformity busbar electroplating device, and use wires to connect the parts to the cathode conductive rod. After connection, use a milliohmmeter to test the conductivity of each position of the part and the wire, and record it. The resistance is less than 0.3Ω;

[0015] Step 3, chemical degreasing: immerse the parts in chemical degreasing solution for chemical degreasing, the temperature is 10-50℃, the time is 10-30min; after degreasing, visually check the water wetting condition of the metal ring surface of the power disk, the water film on the surface of the parts should not be broken within 5s. Otherwise, the degreasing time should be extended, and wash with water for 10-15 seconds after degreasing;

[0016] Step 4, pickling: Use acid solution to remove the oxide film on the surface of parts and wires to be mounted, the temperature is ambient temperature, the time is 5 to 10 seconds; then wash with water for 10 to 15 seconds; and transfer to the nickel plating tank within 5-6 seconds;

[0017] Step 5: Electroplating nickel: Use nickel plating solution for electroplating nickel at a temperature of 39-41°C and a current density of 2-4A / dm 2 , time 16 to 25 minutes; after nickel electroplating, put it in the water recovery tank for recovery and cleaning, the cleaning time is 10 to 15 seconds;

[0018] Step 6: Electroplating: Use gold plating solution for multi-mode double pulse electroplating; temperature 44-46°C, forward current density 0.3-0.8A / dm 2 , negative current density 0.3~0.8A / dm 2, positive time 15 ~ 25s, negative time 8 ~ 12s, positive duty cycle 15% ~ 25%, negative duty cycle 3% ~ 7%, positive frequency 600 ~ 900Hz, negative frequency 600 ~ 900Hz; after electroplating gold, put it in the deionized water recovery tank for recycling and cleaning, the cleaning time is 10 ~ 15 seconds;

[0019] Step 7, hot pure water washing: Soak the parts in hot deionized water for washing at a temperature of 80-90°C for 30-60 seconds; after washing, use water-free and oil-free compressed air to blow dry the parts;

[0020] Step 8: Drying: Place the parts in an oven for drying at a temperature of 60-65°C for 15-25 minutes.

[0021] Step 1 is as follows: clean the surface of the part with a clean soft brush in acetone, and then dry it naturally or blow it dry with water-free and oil-free compressed air;

[0022] In step 3, the chemical degreasing solution includes KF-60 copper alloy chemical degreasing agent.

[0023] In step 4, the acid solution refers to sulfuric acid (mass concentration 98%).

[0024] In step 5, the nickel plating solution includes 200-300 g / L nickel sulfamate, 3-9 g / L nickel chloride, 30-40 g / L boric acid, 3-5 ml / L additive A, 1-2 g / L additive B, and a pH value of 3.6-4.4.

[0025] The additive A includes sodium octyl sulfate and the like as a low-foam wetting agent.

[0026] The additive B includes at least one of saccharin and sodium benzenesulfinate; the additive B is used as a brightener.

[0027] In step 6, the gold plating solution includes 2-5 g / L potassium gold cyanide, 1-2 g / L cobalt acetate, 60-90 g / L citric acid, 5-10 ml / L additive C, and a pH value of 4.1-4.3.

[0028] The additive C includes at least one of potassium D-gluconate and citrate.

[0029] Preferably, the additive C comprises potassium D-gluconate and citrate as a composite complexing agent.

[0030] In step 6, the step of electroplating gold adopts a high uniformity busbar electroplating gold device, which includes: a special hanger consisting of two pictographic anodes, two power line restraint plates, a part clamping positioner, and a plating solution forced jet device consisting of a jet pipeline and a jet pump. During production, the special hanger and the solution forced jet device work together to ensure a consistent deposition speed on the part surface.

[0031] The special hanger includes two pictographic anodes, two power line restraint plates, and a part clamping locator, wherein the material of the pictographic anode is a titanium alloy mesh with ruthenium plated on the surface, the titanium alloy mesh is woven from titanium alloy wire with a diameter of 0.8 to 1.2 mm, and the titanium mesh size is 15 to 20 meshes. The size of the power line restraint plate is 190mm×250mm×1mm, wherein the restraint hole size of the power line restraint plate is Φ140mm~Φ160mm, and the material is PTFE. The size of the clamping locator is 190mm×500mm×3mm, and the parts are positioned and fixed using a hanging positioning groove, and the material is PTFE.

[0032] The forced jet device includes a jet conduit and a jet pump, wherein the jet conduit is divided into a main pipe, a branch pipe and an injection pipe, the main pipe has a diameter of 13 to 18 mm, the branch pipe has a diameter of 7 to 9 mm, the injection pipe has a diameter of 4 to 6 mm, the injection pipe is at an angle of 40° to 50° to the vertical direction, and there are 4 injection pipes; the jet pump is a jet vacuum pump, and the flow rate of the jet pump is not less than 40 to 60 L / min.

[0033] The present invention provides a method for preparing a gold-plated layer with a long current-carrying wear life in a space environment, comprising the following steps: fixing a space busbar with a high-uniform gold-plating tool; pre-treating the parts with chemical degreasing, pickling, etc. to ensure that the parts are free of oil and oxidation; electroplating nickel with an aminosulfonate nickel plating solution; and double-pulse electroplating gold with an electroplating gold solution; after the electroplating is completed, testing the appearance, thickness and uniformity, hardness, unit cell size, and vacuum current-carrying friction and wear performance of the parts. At the same time, the thickness of the gold-plated layer of each loop is measured and statistically analyzed.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. The key point of the present invention is that a high-uniformity busbar electroplating gold device is used in the electroplating process. The device includes a special hanger composed of two pictographic anodes, two power line constraint plates, a part clamping locator, and a forced jet device of the electroplating solution composed of a jet pipeline and a jet pump. The present invention adopts digital simulation technology to optimize the shape and position of the pictographic anode, the shape and position of the power line constraint plate, so as to achieve uniform power lines on the busbar surface during electroplating and eliminate the edge effect during the electroplating process, instead of simply using pictographic anodes in the prior art to improve the distribution of power lines. The key point of the present invention is the use of a jet device, which is different from the existing mechanical stirring and cathode movement methods. The device can continuously spray high-concentration electroplating solution onto the surface of the part, so that the solution on the surface of the part is forced to exchange, which improves the efficiency of solution exchange, reduces the concentration difference plan, and can promote the formation of grains in the electroplating process, refine the coating grains, and improve the hardness and wear resistance of the coating.

[0036] 2. The key point of the present invention is that the double-pulse gold electroplating technology is used in the electroplating process. By periodically applying positive pulse current and negative pulse current to the parts, a gold deposition layer can be formed on the surface of the parts during the positive pulse process, wherein the pulse current can improve the concentration polarization during the electroplating process, and ensure that when the peak current of the pulse electroplating is much higher than the average current, the formation rate of the seed is higher than the growth rate of the crystal, so that the coating crystal is refined, arranged tightly, the pores are reduced, and the hardness is increased. At the same time, the periodic negative pulse can further reduce the concentration plan, and the negative pulse can dissolve the coating metal, further promote grain refinement, and also eliminate the original electroplating edge effect, and improve the uniformity of the coating. The double pulse of this project is a periodic double pulse mode of a group of positive pulses plus a group of negative pulses. Different from the existing mode of one positive pulse plus one negative pulse, it can effectively reduce the capacitance effect during the pulse process and improve the electroplating efficiency. At the same time, the use of high-frequency pulses above 600Hz, rather than the conventional low-frequency pulses below 400Hz, can promote the formation of crystal nuclei and inhibit grain growth.

[0037] 3. The present invention adopts double-pulse gold electroplating technology and a jet device, which work together to reduce the concentration polarization on the surface of the parts. At the same time, since the peak value of the pulse electroplating current is large and the duration is short, the formation of crystals can be promoted, so that the formation rate of the crystals is greater than the growth rate, the coating crystals are refined, the arrangement is tight, the pores are reduced, the hardness is increased, and the wear resistance of the coating is improved.

[0038] 4. The present invention can reduce the friction coefficient of the coating, improve wear resistance, and reduce mechanical wear due to the high uniformity of the coating, fine grains, high hardness, and low porosity. At the same time, the high uniformity of the coating, fine grains, and low porosity can also reduce abnormal discharge during current-carrying friction, avoid discharge ablation, and further improve the wear resistance of the coating.

[0039] 5. Measure and count the thickness of the gold-plated layer in each loop, and test at least 4 points in each loop. Then, perform statistical analysis on the product limit thickness, average thickness, and variance according to the statistical 3σ principle, and evaluate the uniformity of the coating thickness based on the analysis results. This is different from the common coating that only uses the thickness range as the uniformity evaluation standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0041] Figure 1 A schematic diagram of a gold electroplating device for a high uniformity busbar with a long current-carrying wear life used in a space environment;

[0042] Figure 2 A schematic diagram of a special hanger for gold plating with long current-carrying wear life in a space environment;

[0043] Figure 3 Schematic diagram of a gold-plated forced jet pipeline with long current-carrying wear life for use in space environments. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0045] Example 1

[0046] The technical solution provided by the present invention is as follows:

[0047] A method for preparing a gold-plated layer with a long current-carrying wear life in a space environment comprises the following steps:

[0048] Step 1, degreasing with organic solvents: clean the surface of the parts with a clean soft brush in acetone, and then dry them naturally or blow dry them with water-free and oil-free compressed air;

[0049] Step 2, tooling: clamp the parts processed in step 1 to the parts installation position in the high uniformity busbar electroplating device, and use wires to connect the parts to the cathode conductive rod. After connection, use a milliohmmeter to test the conductivity of each position of the part and the wire, and record it. The resistance is less than 0.3Ω;

[0050] Step 3, chemical degreasing: immerse the parts in chemical degreasing solution for chemical degreasing, temperature 50℃, time 10min; after degreasing, visually check the water wetting condition of the metal ring surface of the power disk, the water film on the surface of the parts should not be broken within 5s. Otherwise, the degreasing time should be extended, and water should be used for washing for 15 seconds after degreasing;

[0051] The chemical degreasing solution is KF-60 copper alloy chemical degreasing agent 120g / L.

[0052] Step 4, pickling: Use acid solution to remove the oxide film on the surface of the parts and the wires to be mounted, at ambient temperature for 10 seconds; then rinse with deionized water for 15 seconds; and transfer to the nickel plating tank within 5-6 seconds; the acid solution refers to 200g / L sulfuric acid (mass concentration 98%).

[0053] Step 5: Nickel electroplating: nickel electroplating is performed using a nickel plating solution at a temperature of 41°C and a current density of 3A / dm 2 , time 20min; after nickel electroplating, put it in the deionized water recovery tank for recovery and cleaning, the cleaning time is 15 seconds;

[0054] The nickel plating solution includes 300 g / L nickel sulfamate, 9 g / L nickel chloride, 40 g / L boric acid, 5 ml / L additive A, 2 g / L additive B, and a pH value of 4.4.

[0055] The additive A is sodium octyl sulfate, which serves as a low-foaming wetting agent.

[0056] The additive B is sodium sulfite, which is used as a brightener.

[0057] Step 6: Electroplating: Use gold plating solution for multi-mode double pulse electroplating; temperature 46°C, forward current density 0.5A / dm 2 , negative current density 0.5A / dm 2 , positive time 20s, negative time 10s, positive duty cycle 20%, negative duty cycle 5%, positive frequency 800Hz, negative frequency 800Hz; after electroplating, put it in the deionized water recovery tank for recycling and cleaning, the cleaning time is 15 seconds;

[0058] The gold plating solution includes 5g / L potassium gold cyanide, 2g / L cobalt acetate, 90g / L citric acid, 10ml / L additive C, and a pH value of 4.1-4.3;

[0059] The additive C includes potassium D-gluconate and citrate as a complex complexing agent.

[0060] The gold electroplating step uses a high uniformity busbar gold electroplating device, such as Figure 1As shown, it includes: a special hanger composed of two pictographic anodes, two power line restraint plates, and a part clamping locator (the device is as shown in Figure 2 As shown), a jet pipeline (the device is as shown Figure 3 During production, the special hanger and the solution forced jet device work together to ensure that the deposition speed on the surface of the parts is consistent.

[0061] The special hanger includes two pictographic anodes, two power line restraint plates, and a part clamping locator, wherein the material of the pictographic anode is a titanium alloy mesh with ruthenium plated on the surface, the titanium alloy mesh is woven from titanium alloy wire with a diameter of 0.8 to 1.2 mm, and the titanium mesh size is 15 to 20 meshes. The size of the power line restraint plate is 190mm×250mm×1mm, wherein the restraint hole size of the power line restraint plate is Φ140mm~Φ160mm, and the material is PTFE. The size of the clamping locator is 190mm×500mm×3mm, and the parts are positioned and fixed using a hanging positioning groove, and the material is PTFE.

[0062] The forced jet device includes a jet pipeline and a jet pump, wherein the jet pipeline is divided into a main pipe, a branch pipe and an injection pipe, the main pipe has a diameter of 13 to 18 mm, the branch pipe has a diameter of 7 to 9 mm, the injection pipe has a diameter of 4 to 6 mm, the injection pipe is at an angle of 40° to 50° to the vertical direction, and there are 4 injection pipes; the jet pump is a jet vacuum pump, and the flow rate of the jet pump is not less than 40 to 60 L / min.

[0063] Step 7, hot pure water washing: Soak the parts in hot deionized water for washing at a temperature of 80-90°C for 30-60 seconds; after washing, use water-free and oil-free compressed air to blow dry the parts;

[0064] Step 8: Drying: Place the parts in an oven for drying at a temperature of 60-65°C for 15-25 minutes.

[0065] The double pulse electroplated gold layer has a uniform golden appearance, a maximum thickness of 5 to 7 μm, an average thickness of 5.7 to 6.3 μm, and a standard deviation of less than 0.4. The hardness is about HV210, the roughness is Ra<0.4, and the unit cell size is about 3 μm. -4 Under the conditions of Pa, temperature 80℃, and load 0.5N, the average friction coefficient of the double-pulse electroplated gold layer is about 0.28, the wear scar is narrow and shallow, and the wear rate is 1.21×10 -6 mg / min.

[0066] Comparative Example 1: DC Gold Plating

[0067] Step 1, degreasing with organic solvents: clean the surface of the parts with a clean soft brush in acetone, and then dry them naturally or blow dry them with water-free and oil-free compressed air;

[0068] Step 2, tooling: Clamp the parts processed in step 1 to the parts installation position of the hanger of the high uniformity busbar electroplating device, and use wires to connect the parts to the cathode conductive rod. After connection, use a milliohmmeter to test the conductivity of each position of the part and the wire, and record it. The resistance is less than 0.3Ω;

[0069] Step 3, chemical degreasing: immerse the parts in chemical degreasing solution for chemical degreasing, temperature 50℃, time 10min; after degreasing, visually check the water wetting condition of the metal ring surface of the power disk, the water film on the surface of the parts should not be broken within 5s. Otherwise, the degreasing time should be extended, and water should be used for washing for 15 seconds after degreasing;

[0070] The chemical degreasing solution refers to KF-60 copper alloy chemical degreasing agent 120g / L.

[0071] Step 4, pickling: Use acid solution to remove the oxide film on the surface of parts and wires to be mounted, at ambient temperature, for 5 to 10 seconds; then rinse with deionized water for 15 seconds; and transfer to the nickel plating tank within 5 to 6 seconds; the acid solution refers to 200 g / L sulfuric acid (98%).

[0072] Step 5: Nickel electroplating: nickel electroplating is performed using a nickel plating solution at a temperature of 41°C and a current density of 3A / dm 2 , time 20min; after nickel electroplating, put it in the deionized water recovery tank for recovery and cleaning, the cleaning time is 15 seconds;

[0073] The nickel plating solution includes 300 g / L nickel sulfamate, 9 g / L nickel chloride, 40 g / L boric acid, 5 ml / L additive A, 2 g / L additive B, and a pH value of 4.4.

[0074] The additive A is sodium octyl sulfate, which serves as a low-foaming wetting agent.

[0075] The additive B is sodium sulfite, which is used as a brightener.

[0076] Step 6: Electroplating: Use gold plating solution for direct current gold plating; temperature 46°C, current density 1A / dm 2 , time 20min; after electroplating, put it in the deionized water recovery tank for recovery and cleaning, the cleaning time is 10 to 15 seconds;

[0077] The gold plating solution includes 2-5 g / L potassium gold cyanide, 1-2 g / L cobalt acetate, 60-90 g / L citric acid, 5-10 ml / L additive C, and a pH value of 4.1-4.3;

[0078] The additive C includes potassium D-gluconate, citrate, etc. as a complexing agent.

[0079] The gold electroplating step uses a high uniformity busbar gold electroplating device, such as Figure 1 As shown, it includes: a special hanger composed of two pictographic anodes, two power line restraint plates, and a part clamping locator (the device is as shown in Figure 2 As shown), a jet pipeline (the device is as shown Figure 3 During production, the special hanger and the solution forced jet device work together to ensure that the deposition speed on the surface of the parts is consistent.

[0080] The special hanger includes two pictographic anodes, two power line restraint plates, and a part clamping locator, wherein the material of the pictographic anode is a titanium alloy mesh with ruthenium plated on the surface, the titanium alloy mesh is woven from titanium alloy wire with a diameter of 0.8 to 1.2 mm, and the titanium mesh size is 15 to 20 meshes. The size of the power line restraint plate is 190mm×250mm×1mm, wherein the restraint hole size of the power line restraint plate is Φ140mm~Φ160mm, and the material is PTFE. The size of the clamping locator is 190mm×500mm×3mm, and the parts are positioned and fixed using a hanging positioning groove, and the material is PTFE.

[0081] The forced jet device includes a jet pipeline and a jet pump, wherein the jet pipeline is divided into a main pipe, a branch pipe and an injection pipe, the main pipe has a diameter of 13 to 18 mm, the branch pipe has a diameter of 7 to 9 mm, the injection pipe has a diameter of 4 to 6 mm, the injection pipe is at an angle of 40° to 50° to the vertical direction, and there are 4 injection pipes; the jet pump is a jet vacuum pump, and the flow rate of the jet pump is not less than 40 to 60 L / min.

[0082] Step 7, hot pure water washing: Soak the parts in hot deionized water for washing at a temperature of 80-90°C for 30-60 seconds; after washing, use water-free and oil-free compressed air to blow dry the parts;

[0083] The appearance of the DC gold plating layer is golden yellow, with a darker edge color. The maximum thickness of the plating layer is 5-7μm, the average thickness is 5.6-6.5μm, the thickness range is 0.9μm and the standard deviation is less than 0.6. The hardness is about HV190, the roughness is Ra<0.4, and the unit cell size is about 6μm. -4 Under the conditions of Pa, temperature 80℃, and load 0.5N, the average friction coefficient of the DC electroplated gold layer is about 0.30, and the wear rate is 1.73×10 -5 mg / min.

[0084] Comparative Example 2: Original mounting method

[0085] Step 1, degreasing with organic solvents: clean the surface of the parts with a clean soft brush in acetone, and then dry them naturally or blow dry them with water-free and oil-free compressed air;

[0086] Step 2, tooling: Clamp the parts processed in step 1 onto the cathode conductive rod. After connection, use a milliohmmeter to test the conductivity of each position of the parts and the wire, and record it. The resistance is less than 0.3Ω;

[0087] Step 3, chemical degreasing: immerse the parts in chemical degreasing solution for chemical degreasing, temperature 50℃, time 10min; after degreasing, visually check the water wetting condition of the metal ring surface of the power disk, the water film on the surface of the parts should not be broken within 5s. Otherwise, the degreasing time should be extended, and water should be used for washing for 15 seconds after degreasing;

[0088] The chemical degreasing solution refers to KF-60 copper alloy chemical degreasing agent 120g / L.

[0089] Step 4, pickling: Use acid solution to remove the oxide film on the surface of parts and wires to be mounted, at ambient temperature, for 5 to 10 seconds; then rinse with deionized water for 15 seconds; and transfer to the nickel plating tank within 5 to 6 seconds; the acid solution refers to 200 g / L sulfuric acid (98%).

[0090] Step 5: Nickel electroplating: nickel electroplating is performed using a nickel plating solution at a temperature of 41°C and a current density of 3A / dm 2 , time 20min; after nickel electroplating, put it in the deionized water recovery tank for recovery and cleaning, the cleaning time is 15 seconds;

[0091] The nickel plating solution includes 300 g / L nickel sulfamate, 9 g / L nickel chloride, 40 g / L boric acid, 5 ml / L additive A, 2 g / L additive B, and a pH value of 4.4.

[0092] The additive A is sodium octyl sulfate, which serves as a low-foaming wetting agent.

[0093] The additive B is sodium sulfite, which is used as a brightener.

[0094] Step 6, electroplating gold: double pulse electroplating gold is performed using a gold plating solution; the anode is a pictographic anode, the moving method is cathode moving, the temperature is 46°C, and the current density is 1A / dm 2 , time 20min; after electroplating, put it in the deionized water recovery tank for recovery and cleaning, the cleaning time is 10 to 15 seconds;

[0095] The gold plating solution includes 2-5 g / L potassium gold cyanide, 1-2 g / L cobalt acetate, 60-90 g / L citric acid, 5-10 ml / L additive C, and a pH value of 4.1-4.3;

[0096] The additive C includes potassium D-gluconate, citrate, etc. as a complexing agent.

[0097] The material of the pictographic anode is a titanium alloy mesh with ruthenium plated on the surface. The titanium alloy mesh is woven from titanium alloy wires with a diameter of 0.8 to 1.2 mm, and the size of the titanium mesh holes is 15 to 20 meshes.

[0098] The cathode moving distance is 10 cm, and the frequency is 20 times / min.

[0099] Step 7, hot pure water washing: Soak the parts in hot deionized water for washing at a temperature of 80-90°C for 30-60 seconds; after washing, use water-free and oil-free compressed air to blow dry the parts;

[0100] The appearance of the DC gold plating layer is golden yellow, with a darker edge color. The maximum thickness of the plating layer is 4 to 8 μm, the average thickness is 5.3 to 6.9 μm, the thickness range is 1.6 μm and the standard deviation is less than 1.1. The hardness is about HV210, the roughness is Ra < 0.4, and the unit cell size is about 6 μm. -4 Under the conditions of Pa, temperature 80℃, and load 0.5N, the average friction coefficient of the DC electroplated gold layer is about 0.30, and the wear rate is 4.84×10 -6 mg / min.

[0101] The present invention relates to the four fields of materials science, electricity, physics and space environment science, and belongs to the category of interdisciplinary subjects. Specifically, it is a method for preparing a gold-plated layer with a long current-carrying wear life in a space environment. It is a method for preparing a gold-plated layer with high hardness, fine grains and excellent current-carrying friction and wear performance in a space environment on the surface of a space conductive slip ring busbar by electrochemical means. The characteristics of the device of the present invention are: (1) On the basis of the existing electroplating tank and hanger, two pictographic anodes and two power line constraint plates are added to achieve uniform power lines on the surface of the product. (2) A forced jet device is added to enhance the speed of solution exchange and optimize the flow direction of the solution, so as to achieve uniform solution concentration on the surface of the product. The characteristics of the method are: (1) By using a double pulse current mode, the activation polarization of the cathode is increased and the concentration polarization of the cathode is reduced, so that the formation speed of the crystal nucleus is higher than the growth speed of the crystal, so that the coating crystal is refined, the pores are reduced, and the hardness is increased. (2) The thickness of the gold-plated layer of each loop is measured and counted, and at least 4 points are detected in each loop. Then, the average thickness and variance of the product are statistically analyzed according to the statistical 3σ principle, and the uniformity of the coating thickness is evaluated according to the analysis results. The present invention solves the problem that the existing conductive slip ring coating cannot meet the use requirements of high load, large load and long life of the gold-plated layer on the surface of the space conductive slip ring busbar.

[0102] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a gold-plated layer with a long current-carrying wear life in a space environment, characterized in that: The steps include: Step 1, degreasing with organic solvent: degreasing the parts with organic solvent; Step 2, tooling: clamp the parts processed in step 1 to the parts installation position in the high uniformity busbar electroplating device, and use wires to connect the parts to the cathode conductive rod. After connection, use a milliohmmeter to test the conductivity of each position of the part and the wire, and record it. The resistance is less than 0.3Ω; Step 3, chemical degreasing: immerse the parts in a chemical degreasing solution for chemical degreasing at a temperature of 10 to 50°C for 10 to 30 minutes; Step 4, pickling: Use acid solution to remove the oxide film on the surface of parts and wires to be mounted, the temperature is ambient temperature, the time is 5 to 10 seconds; then wash with water for 10 to 15 seconds; and transfer to the nickel plating tank within 5-6 seconds; Step 5: Electroplating nickel: Use nickel plating solution for electroplating nickel at a temperature of 39-41°C and a current density of 2-4A / dm 2 , time 16 to 25 minutes; after nickel electroplating, put it in the water recovery tank for recovery and cleaning, the cleaning time is 10 to 15 seconds; Step 6, electroplating gold: using a gold plating solution to perform multi-mode double-pulse electroplating gold; Step 7, hot pure water washing: Soak the parts in hot deionized water for cleaning at a temperature of 80-90°C for 30-60 seconds; After cleaning, use water-free and oil-free compressed air to dry the parts; Step 8: Drying: Place the parts in an oven for drying at a temperature of 60-65°C for 15-25 minutes.

2. The preparation method according to claim 1, characterized in that: In step 6, the parameters of electroplating gold are: temperature 44-46°C, forward current density 0.3-0.8A / dm 2 , negative current density 0.3~0.8A / dm 2 , positive time 15~25s, negative time 8~12s, positive duty cycle 15%~25%, negative duty cycle 3%~7%, positive frequency 600~900Hz, negative frequency 600~900Hz; after electroplating gold, place it in a deionized water recovery tank for recovery and cleaning, the cleaning time is 10~15 seconds.

3. The preparation method according to claim 1, characterized in that: In step 6, the gold plating solution includes 2-5 g / L potassium gold cyanide, 1-2 g / L cobalt acetate, 60-90 g / L citric acid, 5-10 ml / L additive C, and a pH value of 4.1-4.

3.

4. The preparation method according to claim 1, characterized in that: In step 5, the nickel plating solution includes 200-300 g / L nickel sulfamate, 3-9 g / L nickel chloride, 30-40 g / L boric acid, 3-5 ml / L additive A, 1-2 g / L additive B, and a pH value of 3.6-4.

4.

5. The preparation method according to claim 4, characterized in that: The additive A includes sodium octyl sulfate; the additive B includes at least one of saccharin and sodium benzenesulfinate; and the additive C includes at least one of potassium D-gluconate and citrate.

6. The preparation method according to claim 1, characterized in that: In step 3, the chemical degreasing solution includes KF-60 copper alloy chemical degreasing agent; in step 4, the acid solution includes sulfuric acid.

7. The preparation method according to claim 1, characterized in that: In step 6, the gold electroplating step uses a busbar gold electroplating device; The busbar electroplating gold device comprises: a special hanger consisting of two pictographic anodes, two power line restraint plates, a parts clamping positioner, and a plating solution forced jet device consisting of a jet pipeline and a jet pump; during production, the special hanger and the solution forced jet device work together.

8. The preparation method according to claim 7, characterized in that: The special hanger is composed of two pictographic anodes, two power line restraint plates and a parts clamping locator.

9. The preparation method according to claim 8, characterized in that: The size of the pictographic anode is Φ150mm×1mm; the material of the pictographic anode is a titanium alloy mesh with ruthenium plated on the surface, the titanium alloy mesh is woven from titanium alloy wire with a diameter of 0.8-1.2mm, and the titanium mesh size is 15-20 meshes; And / or, the size of the power line restraint plate is 190 mm×250 mm×1 mm, wherein the restraint hole size of the power line restraint plate is Φ140 mm to Φ160 mm, and the material of the power line restraint plate is PTFE; And / or, the size of the clamping locator is 190mm×500mm×3mm, and the parts are positioned and fixed using a hanging locating groove, and the material is PTFE.

10. The preparation method according to claim 7, characterized in that: The electroplating solution forced jet device includes a jet pipeline and a jet pump, wherein the jet pipeline is divided into a main pipe, a branch pipe and an injection pipe; the main pipe has a diameter of 13 to 18 mm, the branch pipe has a diameter of 7 to 9 mm, the injection pipe has a diameter of 4 to 6 mm, the injection pipe is at an angle of 40° to 50° to the vertical direction, and the number of injection pipes is 4; the jet pump is a jet vacuum pump, and the flow rate of the jet pump is not less than 40 to 60 L / min.

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