阅读说明：本技术 一种钼铜合金表面电镀金新方法 (Novel method for electroplating gold on molybdenum-copper alloy surface ) 是由 侯文斌 李晓刚 舒建文 冯迎雪 于 2021-07-14 设计创作，主要内容包括：本发明涉及一种钼铜合金表面电镀金新方法,属金属表面处理技术领域。包括七个步骤,经体积分数为390～410ml/L的硝酸、390～410ml/L的硫酸、180～220ml/L的水组成的酸洗液酸洗及体积分数为45～55%盐酸活化、经体积分数为650～750ml/L的硫酸的阳极浸蚀粗化液作化学粗化,以直接在化学镍溶液中作闪镀镍再进行化学镀镍形成镀镍层为基础,实现镀层与基材的良好结合力,增强镀金层与基材的结合力及金锡焊料对镀金层的焊接性能,350℃高温下烘烤10min金锡焊料在镀金层表面润湿性好,镀金层不起泡不变色厚薄均匀颜色一致,不污染环境,成本低,适合加工含精密、形状复杂工件在内的所有工件。(The invention relates to a new method for electroplating metal on the surface of molybdenum-copper alloy, belonging to the technical field of metal surface treatment. The method comprises seven steps of pickling with pickling solution consisting of 390-410 ml/L nitric acid, 390-410 ml/L sulfuric acid and 180-220 ml/L water, activating with 45-55% hydrochloric acid, chemically roughening with anode etching roughening solution of 650-750 ml/L sulfuric acid, and directly performing flash nickel plating in chemical nickel solution and then chemical nickel plating to form a nickel plating layer, so that good bonding force between a plating layer and a base material is realized, the bonding force between the gold plating layer and the base material and the welding performance of gold-tin solder to the gold plating layer are enhanced, the gold-tin solder is baked at the high temperature of 350 ℃ for 10min and has good wettability on the surface of the gold plating layer, the gold plating layer does not blister, does not change color, is uniform in thickness and color, does not pollute the environment, is low in cost, and is suitable for processing all workpieces containing precise and workpieces with complex shapes.)

1. A new method for electroplating gold on the surface of molybdenum-copper alloy is characterized in that: the method is realized by the following steps:

step 1), ultrasonic degreasing

Placing the molybdenum-copper alloy workpiece in a low-frequency ultrasonic cleaning machine for treatment for 1-3 min, wherein the solution used for oil removal is a DS-1152 cleaning agent with the volume fraction of 90-110 ml/L, the ultrasonic cleaning frequency is 40KHz, the temperature of the ultrasonic cleaning solution is 45-55 ℃, and oil stains and other foreign matters on the surface of the molybdenum-copper alloy workpiece are removed;

step 2), chemical acid cleaning

The pickling solution used for the chemical pickling comprises the following components: the method comprises the following steps of (1) immersing a molybdenum-copper alloy workpiece treated in the step 1) into a pickling solution at an operating temperature of 15-25 ℃, shaking for 10-15 s, removing an oxidation film on the surface of the molybdenum-copper alloy workpiece to obtain the molybdenum-copper alloy workpiece with a uniform and clean metal surface, and immediately putting the molybdenum-copper alloy workpiece into flowing water to be washed clean after chemical pickling is finished, wherein the nitric acid with a volume fraction of 380-420 ml/L, the sulfuric acid with a volume fraction of 380-420 ml/L and the water with a volume fraction of 160-240 ml/L are used;

step 3), activation

The solution used for activation is hydrochloric acid with the volume fraction of 45-55%, the operation temperature is 45-55 ℃, the molybdenum-copper alloy workpiece treated in the step 2) is immersed in the activation solution, the activation time is 1-3 min, and the workpiece is quickly washed clean by running water after activation;

step 4), chemical roughening

The anode etching coarsening liquid used for chemical coarsening is prepared from the following components: the volume fraction of sulfuric acid is 650-750 ml/L, the volume fraction of water is 250-350 ml/L, stainless steel is used as a cathode, and the molybdenum-copper alloy workpiece treated in the step 3) is immersed into an anode to be etched and coarsenedIn the liquid, the current density is controlled to be 4-6A/dm²The coarsening time is 10-15 min; removing oxide skin and bad tissues on the surface of the molybdenum-copper alloy workpiece, and increasing the specific surface area, thereby increasing the binding force between the plating layer and the molybdenum-copper alloy workpiece substrate; placing the molybdenum-copper alloy workpiece subjected to chemical roughening treatment in an ultrasonic cleaning machine filled with clear water for ultrasonic cleaning for 1-3 min to thoroughly remove foreign matters generated in the anode etching process of the molybdenum-copper alloy workpiece, wherein the metal surface of the molybdenum-copper alloy workpiece is in a uniform purple copper color after the treatment is finished;

step 5), flash nickel plating and chemical nickel plating

Flash nickel plating is carried out in a chemical nickel tank, and the solution used for flash nickel plating adopts a commercial DS-1101 environment-friendly medium-phosphorus chemical nickel solution; the anode plate used for flash nickel plating is a 99.99 percent electrolytic nickel plate, and the flash plating current is 5-8A/dm²Connecting the molybdenum-copper alloy workpiece treated in the step 4) with a power supply cathode after the chemical nickel solution is heated to a set working temperature of 85-91 ℃, connecting the electrolytic nickel plate with a power supply anode, carrying out flash nickel plating in the chemical nickel solution after electrification, closing the power supply after the flash nickel plating is finished, and quickly taking out the electrolytic nickel anode plate to ensure that the molybdenum-copper alloy workpiece is continuously subjected to chemical nickel plating in the chemical nickel solution, wherein the nickel plating time of the chemical nickel solution is 20-30 min, the pH value is 4.8-5.2, and ensuring good bonding force between the nickel layer and the molybdenum-copper alloy workpiece by directly carrying out impact current flash nickel plating treatment on the copper-copper alloy workpiece in the chemical nickel solution, so that the uniform nickel layer with good bonding force can be obtained by continuously carrying out chemical nickel plating on the basis;

step 6), pre-plating gold

Pre-gold plating adopts a commercial DS-1301 pre-gold plating liquid medicine, the molybdenum-copper alloy workpiece treated in the step 5) is placed into the pre-gold plating liquid medicine, the pH value of the pre-gold plating liquid medicine is controlled to be 3.8-4.2, the gold ion concentration is 0.8-1.2 g/L, the specific gravity is 1.03-1.05, the pre-gold plating time is 45-55 s, after the pre-gold plating is finished, the molybdenum-copper alloy workpiece is washed clean by deionized water and then is continuously washed in hot pure water, the washing time is 5-10 s, and the temperature of the hot pure water is 50-60 ℃;

step 7), gold plating

And (3) gold plating adopts a commercially available DS-2301 gold plating liquid medicine, the molybdenum-copper alloy workpiece treated in the step 6) is placed into the gold plating liquid medicine, the pH value of the gold plating liquid medicine is controlled to be 5.8-6.2, the concentration of gold ions is 7.8-8.2 g/L, the specific gravity is 1.16-1.19, the gold plating time is 4-6 min, the thickness of the obtained gold layer is 0.45-0.71 um, and after the gold plating is finished, the molybdenum-copper alloy workpiece is washed clean by running water, so that a qualified product of the electroplated gold-molybdenum-copper alloy workpiece is obtained.

Technical Field

The invention relates to a new method for electroplating metal on the surface of molybdenum-copper alloy, belonging to the technical field of metal surface treatment.

Background

The molybdenum-copper alloy has the excellent characteristics of high electrical conductivity, high thermal conductivity and small expansion coefficient, and is widely applied to various fields of national defense, aerospace, electronics, metallurgy, chemical engineering and the like; however, the surface of the molybdenum-copper alloy is very easy to oxidize, and the chemical property of the oxidation film layer is stable, so that the surface of the molybdenum-copper alloy has poor wettability and is difficult to process, and cannot meet the application requirements of national defense and aerospace products, therefore, the molybdenum-copper alloy is usually subjected to gold plating treatment to greatly improve the conductivity and welding performance of the molybdenum-copper alloy, so that the molybdenum-copper alloy finally reaches the use standards of national defense and aerospace products, and based on the characteristics, the plating layer bonding force and the welding performance of the molybdenum-copper alloy gold plating process are very important, but the three gold electroplating processes of the existing molybdenum-copper alloy have the following defects:

first, a gold plating process using a sand blasting pretreatment mode and then performing pre-chrome plating and pre-nickel plating as a pre-plating layer can improve the bonding force and the welding performance of the plating layer to a certain extent, but the plating solution used for chrome plating generally contains Cr⁶⁺Not only seriously pollutes the environment, but also has great harm to human bodies, and in addition, the sand blasting pretreatment method of the process cannot be suitable for the treatment of precision parts and workpieces with complicated shapes.

And secondly, the binding force of the nickel layer and the substrate is improved by heat treatment of the nickel layer through the vacuum furnace, so that the binding force of a plating layer is improved, and the solderability of gold-tin solder to a gold layer is ensured.

And thirdly, a palladium chloride replacement plating process is adopted, although the problems of the bonding force and the weldability of the gold-tin solder can be effectively solved, the process directly adopts anode etching after the workpiece is degreased, the local over-corrosion of the molybdenum-copper alloy base material is easily caused by the inconsistent surface state of the workpiece, the surface state of the molybdenum-copper alloy base material after treatment is seriously influenced, and in addition, palladium salt is adopted for activation treatment, so the price is high, and the processing cost is high.

Disclosure of Invention

The invention aims to provide a new method for plating gold on the surface of a molybdenum-copper alloy, aiming at the defects of the prior art, and realizing an intermediate pre-plating layer with good bonding force with a molybdenum-copper alloy substrate, ensuring the bonding force between a subsequent gold-plating layer and the molybdenum-copper alloy substrate and the welding performance of gold-tin solder to the gold-plating layer, ensuring that the gold-tin solder baked at high temperature has good wettability on the surface of the gold-plating layer, and the gold-plating layer does not blister, does not change color, has uniform thickness and color, avoids pollution to the environment, effectively reduces the processing cost, and is suitable for processing all workpieces including precise parts and workpieces with complex shapes. The method solves the problems that the prior art improves the binding force of a plating layer through chromium plating, improves the binding force of the plating layer through heat treatment of a nickel layer and improves the binding force of the plating layer through palladium chloride replacement, easily causes environmental pollution, cannot process precise parts and workpieces with complex shapes, and has limited application range; poor heat treatment effect, low benign rate of plating layer treatment, serious influence on the surface roughness of the molybdenum-copper alloy base material after treatment, expensive activation price of palladium salt and high processing cost.

The invention realizes the purpose through the following technical scheme:

a new method for electroplating gold on the surface of molybdenum-copper alloy is characterized in that: the method is realized by the following steps:

step 1), ultrasonic degreasing

Placing the molybdenum-copper alloy workpiece in an ultrasonic cleaning machine for treatment for 1-3 min, wherein the solution used for oil removal is a DS-1152 cleaning agent with the volume fraction of 90-110 ml/L, the ultrasonic cleaning frequency is 40KHz, the temperature of the ultrasonic cleaning solution is 45-55 ℃, and oil stains and other foreign matters on the surface of the molybdenum-copper alloy workpiece are removed;

step 2), chemical acid cleaning

The pickling solution used for the chemical pickling comprises the following components: the method comprises the following steps of 1, immersing a molybdenum-copper alloy workpiece treated in the step 1 into a pickling solution at an operating temperature of 15-25 ℃, shaking for 10-15 s, removing an oxidation film on the surface of the molybdenum-copper alloy workpiece to obtain the molybdenum-copper alloy workpiece with a uniform and clean metal surface, and immediately putting the molybdenum-copper alloy workpiece into flowing water to be washed clean after chemical pickling is finished, wherein the nitric acid with a volume fraction of 380-420 ml/L, the sulfuric acid with a volume fraction of 380-420 ml/L and the water with a volume fraction of 160-240 ml/L are adopted;

step 3), activation

The solution used for activation is hydrochloric acid with the volume fraction of 45-55%, the operation temperature is 45-55 ℃, the molybdenum-copper alloy workpiece treated in the step 2 is immersed in the activation solution, the activation time is 1-3 min, and the workpiece is quickly washed clean by running water after activation;

step 4), chemical roughening

The chemical coarsening adopts an anode etching method, and the used anode etching coarsening liquid comprises the following components: the molybdenum-copper alloy workpiece treated in the step 3 is immersed in an anode etching roughening solution by taking stainless steel as a cathode, and the current density is controlled to be 4-6A/dm²The coarsening time is 10-15 min; removing oxide skin and bad tissues on the surface of the molybdenum-copper alloy workpiece, and increasing the specific surface area, thereby increasing the binding force between the plating layer and the molybdenum-copper alloy workpiece substrate; placing the molybdenum-copper alloy workpiece subjected to chemical roughening treatment in an ultrasonic cleaning machine filled with clear water for ultrasonic cleaning for 1-3 min to thoroughly remove foreign matters generated in the anode etching process of the molybdenum-copper alloy workpiece, wherein the metal surface of the molybdenum-copper alloy workpiece is in a uniform purple copper color after the treatment is finished;

step 5), flash nickel plating and chemical nickel plating

Flash nickel plating is carried out in a chemical nickel tank, and the solution used for flash nickel plating adopts a commercial DS-1101 environment-friendly medium-phosphorus chemical nickel solution; the anode plate used for flash nickel plating is a 99.99 percent electrolytic nickel plate, and the flash plating current is 5-8A/dm²And (4) flash plating for 40-50 s, when the chemical nickel solution is heated to the set working temperature of 85-91 ℃, connecting the molybdenum-copper alloy workpiece treated in the step (4) with a power supply cathode, and connecting the electrolytic nickel plate with the electrolytic nickel plateConnecting a power supply anode, carrying out flash nickel plating in the chemical nickel solution after electrifying, closing the power supply after the flash nickel plating is finished, quickly taking out the electrolytic nickel anode plate, ensuring that the molybdenum-copper alloy workpiece is continuously subjected to chemical nickel plating in the chemical nickel solution, wherein the nickel plating time of the chemical nickel solution is 20-30 min, the pH value is 4.8-5.2, directly carrying out impact current flash nickel plating activation treatment on the 'purple copper' molybdenum-copper alloy workpiece in the chemical nickel solution, ensuring the good bonding force between the nickel layer and the molybdenum-copper alloy workpiece, and continuously carrying out chemical nickel plating on the basis to obtain the nickel layer with uniform thickness and good bonding force;

step 6), pre-plating gold

Pre-gold plating adopts a commercial DS-1301 pre-gold plating liquid medicine, the molybdenum-copper alloy workpiece treated in the step 5 is placed into the pre-gold plating liquid medicine, the pH value of the pre-gold plating liquid medicine is controlled to be 3.8-4.2, the gold ion concentration is 0.8-1.2 g/L, the specific gravity is 1.03-1.05, the pre-gold plating time is 45-55 s, after the pre-gold plating is finished, the molybdenum-copper alloy workpiece is washed clean by deionized water and then is continuously washed in hot pure water, the washing time is 5-10 s, and the temperature of the hot pure water is 50-60 ℃;

step 7), gold plating

And (3) gold plating adopts a commercially available DS-2301 gold plating liquid medicine, the molybdenum-copper alloy workpiece treated in the step (6) is placed into the gold plating liquid medicine, the pH value of the gold plating liquid medicine is controlled to be 5.8-6.2, the concentration of gold ions is 7.8-8.2 g/L, the specific gravity is 1.16-1.19, the gold plating time is 4-6 min, the thickness of the obtained gold layer is 0.45-0.71 um, and after the gold plating is finished, the molybdenum-copper alloy workpiece is washed clean by running water, so that a qualified product of the electroplated gold-molybdenum-copper alloy workpiece is obtained.

Compared with the prior art, the invention has the beneficial effects that:

the novel method for electrogilding on the surface of the molybdenum-copper alloy comprises the steps of carrying out chemical pickling on a pickling solution consisting of nitric acid with the volume fraction of 380-420 ml/L, sulfuric acid with the volume fraction of 380-420 ml/L and water with the volume fraction of 160-240 ml/L through the components of the pickling solution, carrying out activation treatment on hydrochloric acid with the volume fraction of 45-55%, preliminarily removing metal oxides which are difficult to be plated on the surface of a molybdenum-copper alloy workpiece to obtain a metal layer with a clean and uniform surface, further carrying out chemical roughening on the metal layer by using a sulfuric acid solution with the volume fraction of 650-750 ml/L as an anode roughening solution, further removing the bad tissues on the surface of the metal layer, forming proper roughness on the surface of the metal layer, activating the metal layer and increasing the specific surface area of the metal, and being beneficial to obtaining good binding force between a molybdenum-copper alloy substrate and a plating layer, and carrying out high-current impact flash plating in a chemical nickel solution, under the dual action of high-density current polarization and chemical nickel solution reduction deposition, a transition layer with better bonding force is formed between the plating layer and the molybdenum-copper alloy workpiece substrate, chemical nickel deposition is continuously carried out on the basis to obtain a uniform, compact and high-temperature-resistant nickel plating layer, and finally pre-gold plating and gold electroplating are carried out on the basis of the intermediate nickel plating layer, namely, a gold plating layer with consistent appearance color, no bubbles and no discoloration of the molybdenum-copper alloy workpiece is finally obtained under the conditions of 350 ℃ temperature and 10min tolerance test, and meanwhile, the effect of good wettability of gold-tin solder on the surface of the gold plating layer is obtained. The intermediate pre-plating layer with good bonding force with the molybdenum-copper alloy substrate is realized, the bonding force between the subsequent gold-plating layer and the molybdenum-copper alloy substrate and the welding performance of the gold-tin solder to the gold-plating layer are ensured, the environmental pollution is avoided, the processing cost is effectively reduced, and all workpieces including precision parts and workpieces with complex shapes are adaptively treated. The method solves the problems that the prior art improves the binding force and welding performance of a plating layer through chromium plating, improves the binding force of the plating layer through heat treatment of a nickel layer and palladium chloride displacement plating, easily causes environmental pollution, cannot treat precision parts and workpieces with complex shapes, and has limited application range; poor heat treatment effect, low benign rate of plating layer treatment, serious influence on the surface roughness of the molybdenum-copper alloy base material after treatment, activation of palladium salt, high price and high processing cost.

The following is a detailed description of the new method for electroplating gold on the surface of molybdenum-copper alloy:

a new method for electroplating gold on the surface of molybdenum-copper alloy is characterized by comprising the following seven steps: step 1), ultrasonic oil removal; step 2), chemical acid washing; step 3), activating; step 4), chemical coarsening; step 5), flash nickel plating and chemical nickel plating; step 6), pre-plating gold; step 7), gold plating;

and in the step 1), an ultrasonic cleaning machine is used for removing oil, the solution used for removing the oil is a DS-1152 cleaning agent with the volume fraction of 90-110 ml/L, the ultrasonic cleaning frequency is 40KHz, the temperature of the ultrasonic cleaning liquid is 45-55 ℃, and oil stains and other foreign matters on the surface of the molybdenum-copper alloy workpiece are removed.

The pickling solution adopted in the step 2) comprises the following components: the method comprises the following steps of preparing nitric acid with the volume fraction of 380-420 ml/L, sulfuric acid with the volume fraction of 380-420 ml/L and water with the volume fraction of 160-240 ml/L, soaking a cleaned molybdenum-copper alloy workpiece into an acid washing solution at the actual operation temperature of 15-25 ℃ for 10-15 s, shaking for 10-15 s, removing an oxidation film on the surface of the molybdenum-copper alloy workpiece, and obtaining a uniform and clean metal surface; after the chemical pickling is finished, the molybdenum-copper alloy workpiece needs to be immediately put into running water to be washed clean; the step 2) of the invention can rapidly remove the oxide film on the surface of the molybdenum-copper alloy workpiece to obtain a uniform metal surface.

The solution adopted in the activation in the step 3) is hydrochloric acid (analytically pure) with the volume fraction of 45-55%, the operation temperature is 45-55 ℃, the activation time is 1-3 min, and after the activation is completed, the workpiece is quickly washed clean by running water.

The roughening solution for the chemical roughening of the anode etching in the step 4) consists of sulfuric acid solution with volume concentration of 650-750 ml/L, stainless steel is used as a cathode, and the current density is 4-6A/dm²The coarsening time is 10-15 min; roughening the uniform metal surface after pickling in an anode etching mode, and chemically roughening the molybdenum-copper alloy workpiece surface by anode etching, so that on one hand, oxide skin and poor tissues on the molybdenum-copper alloy workpiece surface are removed, and on the other hand, the bonding force between a plating layer and a molybdenum-copper alloy workpiece substrate is increased by improving the metal specific surface area; and 4, after the step 4 is finished, the molybdenum-copper alloy workpiece is placed in an ultrasonic cleaning machine filled with clear water to be subjected to ultrasonic cleaning for 1-3 min so as to ensure that a black film generated in the anode etching process of the molybdenum-copper alloy workpiece is completely removed, and the roughened metal surface is in a uniform red copper color.

And 5) flash nickel plating and chemical nickel plating, wherein the flash nickel plating is carried out on the chemical nickelThe chemical nickel solution is a DS-1101 environment-friendly medium phosphorus chemical nickel solution; the polar plate used for flash nickel plating is a 99.99 percent electrolytic nickel plate, and the flash plating current is 5-8A/dm²The flash plating time is 40-50 s, and the specific operation is as follows: after the chemical nickel solution is heated to the set working temperature of 85-91 ℃, connecting the molybdenum-copper alloy workpiece with a power supply cathode, connecting an electrolytic nickel plate with a power supply anode, carrying out flash nickel plating in the chemical nickel solution after electrifying, turning off the power supply and rapidly taking out a nickel anode plate after the flash nickel plating is finished, ensuring that the molybdenum-copper alloy workpiece continues to carry out chemical nickel plating in the chemical nickel solution, wherein the chemical nickel plating time is 20-30 min, and the pH value of the chemical nickel solution is 4.8-5.2; the method is characterized in that the method comprises the steps of directly carrying out impulse current flash nickel plating activation treatment on a 'purple copper' molybdenum-copper alloy workpiece in a chemical nickel solution to ensure good bonding force between a nickel layer and a molybdenum-copper alloy workpiece substrate, and continuously carrying out chemical nickel plating on the basis to obtain a uniform nickel layer with good bonding force.

Pre-gold plating is carried out in the step 6), and a pre-gold plating liquid medicine of DS-1301 is adopted, the pH value is controlled to be 3.8-4.2, the concentration of gold ions is 0.8-1.2 g/L, the specific gravity is 1.03-1.05, and the pre-gold plating time is 45-55 s; and after the pre-gold plating is finished, washing the molybdenum-copper alloy workpiece with deionized water, and then washing the workpiece in hot pure water for 5-10 s at the temperature of 50-60 ℃.

And 7) gold plating, namely adopting a DS-2301 gold plating solution, controlling the pH value to be 5.8-6.2, controlling the concentration of gold ions to be 7.8-8.2 g/L, controlling the specific gravity to be 1.16-1.19, carrying out gold plating for 4-6 min, wherein the thickness of an obtained gold layer is 0.45-0.71 um, and washing the molybdenum-copper alloy workpiece with running water after the gold plating is finished to obtain a qualified gold-molybdenum-copper alloy electroplated workpiece product.

The novel method for electrogilding the surface of the molybdenum-copper alloy preliminarily removes metal oxides which are difficult to be plated on the surface of a molybdenum-copper alloy workpiece through chemical pickling and activation to obtain a metal layer with a uniform surface, further chemically coarsens the metal surface through an anode etching method, further removes bad structures on the metal surface, activates the metal surface and increases the specific surface area of the metal, so that a good binding force is obtained between a substrate and a plating layer of the molybdenum-copper alloy workpiece; after chemical coarsening is finished, high-current impact flash nickel plating is carried out in a chemical nickel solution, a transition layer with better bonding force with a molybdenum-copper alloy workpiece substrate is obtained under the double actions of high-density current and chemical nickel solution reduction deposition, then chemical nickel deposition is carried out, an intermediate nickel plating layer with good uniform, compact and high-temperature resistant performance is obtained, and finally pre-gold plating and gold plating are carried out on the basis of the intermediate nickel plating layer, so that a gold plating layer with consistent appearance color, no bubbling and no discoloration can be obtained under the baking condition of high temperature of 350 ℃ and long time of 10min, and meanwhile, the wettability of gold-tin solder on the surface of the gold plating layer is good.

Example 1

1) Ultrasonic oil removal

Ultrasonic cleaning and deoiling the molybdenum-copper alloy workpiece in a soaking mode, wherein solution used for deoiling is DS-1152 cleaning agent with volume fraction of 90ml/L, the balance is tap water, the frequency of the ultrasonic cleaning machine is 40KHz, the ultrasonic cleaning temperature is 45 ℃, the time is 3min, and the molybdenum-copper alloy workpiece is washed clean by running water after the ultrasonic cleaning machine is cleaned;

2) chemical pickling

The pickling solution selected for chemical pickling consists of nitric acid with the volume fraction of 380ml/L, sulfuric acid with the volume fraction of 380ml/L and water with the volume fraction of 240ml/L, the actual operation temperature is 15 ℃, the molybdenum-copper alloy workpiece cleaned in the step 1 is immersed in the pickling solution, shaken for 15s and then immediately taken out and washed clean by running water, and the surface of the molybdenum-copper alloy workpiece is ensured not to have oxide residues;

3) activation of

The solution used for activation is hydrochloric acid with the volume fraction of 50 percent, (analytically pure), the operation temperature is 45 ℃, the activation time is 1min, the molybdenum-copper alloy workpiece which is subjected to acid washing in the step 2 is immersed in the hydrochloric acid solution, and the workpiece is quickly washed clean by running water after activation;

4) chemical roughening

The roughening solution for anodic etching consists of sulfuric acid solution with volume fraction of 650ml/L, stainless steel as cathode and current density of 4A/dm²The coarsening time is 15min, the molybdenum-copper alloy workpiece activated in the step 3 is immersed into the coarsening liquid etched by the anode for chemical coarseningThen cleaning the mixture in clear water by using an ultrasonic cleaning machine;

5) flash nickel plating and electroless nickel plating

Flash nickel plating is carried out in a chemical nickel tank, and a DS-1101 environment-friendly medium-phosphorus chemical nickel solution is adopted as a chemical nickel solution; the polar plate used for flash nickel plating is a 99.99 percent electrolytic nickel plate, the molybdenum-copper alloy workpiece is connected with a power supply cathode, the 99.99 percent electrolytic nickel plate is connected with a power supply anode, flash nickel plating is carried out in chemical nickel solution after electrification, and the flash plating current is 5A/dm²The flash plating time is 50s, and the temperature of the chemical nickel solution is 85 ℃; after the flash nickel plating is finished, the power supply is turned off, the nickel anode plate is quickly taken out, the molybdenum-copper alloy workpiece continues to carry out chemical nickel plating in a chemical nickel solution, the pH value of the chemical nickel solution is 5.15, the working temperature is 85 ℃, the chemical nickel plating time is 30min, and the workpiece is washed clean by running water after the chemical nickel plating is finished;

6) pre-gold plating

Pre-gold plating adopts pre-gold plating liquid medicine of DS-1301, the pH value is controlled to be 4.1, the concentration of gold ions is 0.875g/L, the specific gravity is 1.05, and the pre-gold plating time is 45 s; after pre-plating gold, washing the molybdenum-copper alloy workpiece with deionized water, and then washing in hot pure water, wherein the washing time is 10s, and the temperature of the hot pure water is 50 ℃;

7) gold plating

The electrogilding liquid medicine is DS-2301 gold-plating liquid medicine, the pH value is controlled at 5.9, the concentration of gold ions is 7.8g/L, the specific gravity is 1.17, the gold-plating time is 4min, and the workpiece is washed clean by running water after the gold-plating is finished.

Example 2

1) Ultrasonic oil removal

Ultrasonic cleaning and deoiling a molybdenum-copper alloy workpiece in a soaking mode, wherein a solution used for deoiling is a DS-1152 cleaning agent with the volume fraction of 100ml/L, the balance is tap water, the frequency of an ultrasonic cleaning machine is 40KHz, the ultrasonic cleaning temperature is 50 ℃, the time is 2min, and the molybdenum-copper alloy workpiece is cleaned by running water after the ultrasonic cleaning is finished;

2) chemical pickling

The pickling solution selected by the chemical pickling solution is prepared from 400ml/L nitric acid, 400ml/L sulfuric acid and 200ml/L water in volume fraction, the actual operation temperature is 20 ℃, a molybdenum-copper alloy workpiece is immersed in the solution and shaken for 13s, then immediately taken out and washed clean by running water, and the surface of the workpiece is ensured not to have oxide residues;

3) activation of

The solution used for activation is hydrochloric acid (analytically pure) with the volume fraction of 50%, the operation temperature is 50 ℃, the activation time is 2min, and the solution is quickly washed clean by running water after activation;

4) chemical roughening

The roughening solution for anode etching consists of sulfuric acid solution with volume fraction of 700ml/L, stainless steel as cathode and current density of 5A/dm²Coarsening for 13min, and then carrying out ultrasonic cleaning in clear water;

5) flash nickel plating and electroless nickel plating

Flash nickel plating is carried out in a chemical nickel tank, and a DS-1101 environment-friendly medium-phosphorus chemical nickel solution is adopted as a chemical nickel solution; the polar plate used for flash nickel plating is a 99.99 percent electrolytic nickel plate, the molybdenum-copper alloy workpiece is connected with a power supply cathode, the 99.99 percent electrolytic nickel plate is connected with a power supply anode, flash nickel plating is carried out in chemical nickel solution after electrification, and the flash plating current is 6.5A/dm²The flash plating time is 45s, and the temperature of the chemical nickel solution is 88 ℃; after the flash nickel plating is finished, the power supply is turned off, the nickel anode plate is quickly taken out, the molybdenum-copper alloy workpiece continues to carry out chemical nickel plating in a chemical nickel solution, the pH value of the chemical nickel solution is 5.17, the working temperature is 88 ℃, the chemical nickel plating time is 25min, and the workpiece is washed clean by running water after the chemical nickel plating is finished;

6) pre-gold plating

Pre-gold plating adopts DS-1301 pre-gold plating liquid medicine, the pH value is controlled to be 4.13, the concentration of gold ions is 0.981g/L, the specific gravity is 1.05, and the pre-gold plating time is 50 s; after pre-plating gold, washing the molybdenum-copper alloy workpiece with deionized water, and then washing in hot pure water for 8s at the temperature of 55 ℃;

7) gold plating

The gold plating liquid medicine is DS-2301, the pH value is controlled to be 5.9, the concentration of gold ions is 8.0g/L, the specific gravity is 1.17, the gold electroplating time is 5min, and the molybdenum-copper alloy workpiece is washed clean by running water after the gold electroplating is finished.

Example 3

1) Ultrasonic oil removal

Ultrasonic cleaning and deoiling a molybdenum-copper alloy workpiece in a soaking mode, wherein a solution used for deoiling is a DS-1152 cleaning agent with the volume fraction of 110ml/L, and the balance is tap water; the frequency of the ultrasonic cleaning machine is 40KHz, the ultrasonic cleaning temperature is 55 ℃, the time is 1min, and the ultrasonic cleaning machine is washed clean by running water after the ultrasonic cleaning is finished;

2) chemical pickling

The pickling solution selected by the chemical pickling solution comprises 420ml/L nitric acid, 420ml/L sulfuric acid and 160ml/L water in volume fraction, the actual operation temperature is 25 ℃, the molybdenum-copper alloy part is immersed in the solution, shaken for 10s and then immediately taken out and washed clean by running water, and the surface of a workpiece is ensured not to have oxide residues;

3) activation of

The solution used for activation is hydrochloric acid (analytically pure) with the volume concentration of 50%, the operation temperature is 50 ℃, the activation time is 3min, and the solution is quickly washed clean by running water after the activation is finished;

4) chemical roughening

The roughening solution for anodic etching is a solution consisting of 750ml/L sulfuric acid and 250ml/L water, stainless steel is used as cathode, and the current density is 5A/dm²Coarsening for 10min, and then carrying out ultrasonic cleaning in clear water;

5) flash nickel plating and electroless nickel plating

Flash nickel plating is carried out in a chemical nickel tank, and a DS-1101 environment-friendly medium-phosphorus chemical nickel solution is adopted as a chemical nickel solution; the electrode plate for flash nickel plating is 99.99% electrolytic nickel plate, the workpiece is connected with the cathode of a power supply, the 99.99% electrolytic nickel plate is connected with the anode of the power supply, flash nickel plating is carried out in chemical nickel solution after electrification, and the flash plating current is 8A/dm²The flash plating time is 40s, and the temperature of the chemical nickel solution is 91 ℃. After the flash nickel plating is finished, the power supply is turned off, the nickel anode plate is quickly taken out, the molybdenum-copper alloy workpiece continues to carry out chemical nickel plating in a chemical nickel solution, the pH value of the chemical nickel solution is 5.17, the working temperature is 91 ℃, the chemical nickel plating time is 20min, and the workpiece is washed clean by running water after the chemical nickel plating is finished;

6) pre-gold plating

Pre-gold plating adopts pre-gold plating liquid medicine of DS-1301, the pH value is controlled to be 4.13, the concentration of gold ions is 1.21g/L, the specific gravity is 1.05, and the pre-gold plating time is 55 s; after pre-plating gold, washing the molybdenum-copper alloy workpiece with deionized water, and then washing in hot pure water, wherein the washing time is 5s, and the temperature of the hot pure water is 60 ℃;

7) gold plating

The gold plating liquid medicine is DS-2301, the pH value is controlled at 5.9, the gold ion concentration is 8.13g/L, the specific gravity is 1.17, the gold plating time is 6min, and the molybdenum-copper alloy workpiece is washed clean by running water after the gold plating is finished.

The molybdenum-copper alloy comprises two types of Mo50Cu50 and Mo70Cu30, and a molybdenum-copper alloy workpiece needs to be polished by sand paper before electroplating.

The invention relates to a new method for plating gold on the surface of a molybdenum-copper alloy, which is realized by seven steps of ultrasonic oil removal, chemical acid cleaning, activation, chemical coarsening, nickel flash plating and chemical nickel plating, pre-gold plating and gold plating; primarily removing metal oxides on the surface of the substrate of the molybdenum-copper alloy workpiece through chemical pickling and activation treatment to obtain a metal layer with a substantially uniform surface; the method comprises the steps of completely removing oxides difficult to plate on the metal surface through chemical roughening, increasing the specific surface area, carrying out chemical nickel plating after carrying out flash nickel plating in a chemical nickel solution, determining the technological method and technological parameters of the chemical roughening and the flash nickel plating, obtaining an intermediate nickel plating layer with good binding force under the combined action of high-density current impact activation and chemical reduction deposition, then carrying out pre-gold plating and gold plating on the basis, enhancing the binding force and the weldability between the plating layer and a base material, ensuring that gold-tin solder baked at the high temperature of 350 ℃ for 10min has good wettability on the surface of the gold plating layer, the gold plating layer does not blister, does not change color, is uniform in thickness and color, avoids polluting the environment, effectively reduces the processing cost, is suitable for all molybdenum-copper alloy workpieces including precise parts and workpieces with complex shapes to carry out electroplating treatment, and has simple operation, has good application prospect.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.