阅读说明：本技术 化学镀镍钨磷镀液及采用该镀液的化学镀方法 (Chemical nickel-tungsten-phosphorus plating solution and chemical plating method using same ) 是由 孙华敏 赵东军 张翼 于 2021-08-12 设计创作，主要内容包括：本发明公开了一种化学镀镍钨磷镀液及采用该镀液的化学镀方法,该镍钨磷镀液采用二氧化碲、酒石酸锑钾与糖精钠作为复合光亮剂,多硫化物、碘酸钾和硫氰酸钠作为复合稳定剂,柠檬酸钠、乳酸和三乙醇胺作为复合络合剂,壬基酚聚氧乙烯醚与十二烷基硫酸钠作为复合防针孔剂,还包含所必须的主盐和还原剂。本发明提供的镍钨磷镀液和化学镀方法解决了镀液稳定性差、镀层有缺陷以及镀层硬度低和耐腐蚀性差的问题。(The invention discloses a chemical nickel-tungsten-phosphorus plating solution and a chemical plating method adopting the plating solution, wherein the nickel-tungsten-phosphorus plating solution adopts tellurium dioxide, antimony potassium tartrate and sodium saccharin as composite brightening agents, polysulfide, potassium iodate and sodium thiocyanate as composite stabilizing agents, sodium citrate, lactic acid and triethanolamine as composite complexing agents, nonylphenol polyoxyethylene ether and sodium dodecyl sulfate as composite anti-pinhole agents, and also contains necessary main salt and reducing agents. The nickel-tungsten-phosphorus plating solution and the chemical plating method provided by the invention solve the problems of poor stability of the plating solution, defective plating layer, low hardness of the plating layer and poor corrosion resistance.)

1. The chemical nickel-tungsten-phosphorus plating solution is characterized by comprising the following components:

at least one soluble nickel salt with the concentration of 10-25 g/L;

at least one soluble tungstate with a concentration of 20-42 g/L;

hypophosphite with the concentration of 25-40 g/L;

the composite brightener consists of 1-9mg/L tellurium dioxide, 5-12mg/L antimony potassium tartrate and 10-50mg/L saccharin sodium;

the compound pinhole preventing agent consists of 3-10mg/L nonylphenol polyoxyethylene ether and 15-30mg/L lauryl sodium sulfate;

the composite stabilizer consists of polysulfide 1-5mg/L, potassium iodate 6-12mg/L and sodium thiocyanate 3.5-7 mg/L;

the complex complexing agent consists of 15-40g/L sodium citrate, 12-20g/L lactic acid and 0.1-0.5g/L triethanolamine.

2. An electroless nickel, tungsten and phosphorus plating solution according to claim 1 wherein said polysulfide is isothiourea propane sulfonate inner salt.

3. An electroless nickel, tungsten and phosphorus plating solution according to claim 1 wherein said soluble nickel salt is selected from nickel sulfate and/or nickel chloride.

4. An electroless nickel tungsten phosphorus plating solution according to claim 1 wherein said soluble tungstate is sodium tungstate.

5. An electroless nickel, tungsten and phosphorus plating solution according to claim 1 wherein said hypophosphite is sodium hypophosphite.

6. An electroless nickel, tungsten and phosphorus plating solution according to claim 1 further comprising a buffering agent.

7. The electroless nickel, tungsten and phosphorus plating solution as recited in claim 6, wherein said buffer is ammonium acetate.

8. The electroless nickel, tungsten and phosphorus plating solution as recited in claim 7, wherein the concentration of ammonium acetate is 12-30 g/L.

9. An electroless plating process using the nickel tungsten phosphorous plating solution of any of claims 1 to 8 comprising the steps of:

providing a substrate to be plated;

formulating the nickel tungsten phosphorous plating solution of any one of claims 1 to 8;

adjusting the pH value of the nickel-tungsten-phosphorus plating solution to 8-10;

immersing a substrate into the nickel-tungsten-phosphorus plating solution, and heating the nickel-tungsten-phosphorus plating solution to 85-90 ℃;

and plating the nickel-tungsten-phosphorus plating solution on the surface of the substrate at a plating speed of 18-20 mu m/H to form a plated layer.

10. The electroless plating method according to claim 9, wherein the substrate is a steel material.

11. The electroless plating method according to claim 9, wherein the tungsten content in the plating layer is 5 to 15%.

12. The electroless plating method according to claim 9, further comprising the step of heat-treating the plated layer.

Technical Field

The invention relates to the field of chemical plating, in particular to a chemical nickel-tungsten-phosphorus plating solution and a chemical plating method adopting the plating solution.

Background

The chemical nickel, tungsten and phosphorus plating technology is developed on the basis of the nickel and phosphorus chemical plating technology, and the addition of tungsten can improve the coating defects generated in the plating process, so that the protection effect on a matrix is enhanced. In the chemical nickel-tungsten-phosphorus plating formula, the selection of a complexing agent, a stabilizing agent, a brightening agent and a pinhole preventing agent is very important, and the physical properties and the chemical properties of a plating solution and a plating layer can be directly influenced.

The complexing agent added into the chemical nickel, tungsten and phosphorus plating solution not only can play a role in controlling the concentration of free ions, but also can effectively influence the phosphorus content in the plating layer and the stability of the plating layer. In the chemical nickel, tungsten and phosphorus plating solution disclosed at present, the complexing agent generally adopts sodium citrate, and some of the complexing agents are added with sodium gluconate, sodium lactate and the like as auxiliary complexing agents. However, the stability of the plating solution is still to be improved. For example, the invention patent (application No. CN200810064719.6) adopts sodium citrate as a single complexing agent, and the stability of the plating solution is poor. In addition, a fluoride protective film is formed on the surface of a substrate by adding ammonium bifluoride to improve the stability of a plating layer, but fluorine-containing substances pollute the environment and are not an optimal solution.

In addition, the stability of the bath is also related to the stabilizer component added. In the prior art, thiourea, iodate or both are commonly used as the stabilizer. Or additionally adding a strong reducing agent to increase the service life of the plating solution. The invention patent (application No. CN 201710261744.2) discloses a method for adding dimethylamine borane into chemical nickel-tungsten-phosphorus plating solution to reduce the accumulation speed of phosphite ions and prolong the service life of the plating solution. However, dimethylamine borane is high in toxicity, is not environment-friendly, is violent in reaction process, is difficult to control, and has potential harm.

The traditional inorganic brightener contains toxic metal elements such as cadmium, lead and the like, and is eliminated by the market. Therefore, the development of novel inorganic brightener with high efficiency and environmental protection is a research hotspot. In addition, the composite brightener is more conducive to increasing the fineness and gloss uniformity of the plating layer than a single brightener. However, the coordination of the composition proportion of the composite brightener and the economic problem is also a big difficulty in the current practical application. In addition, the hardness and the corrosion resistance of the plating layer are directly related to the porosity of the plating layer, and the porosity of the plating layer can be effectively reduced by adding the pinhole preventing agent into the plating solution. The invention patent (application number: CN200810059696. X) discloses a technical scheme for reducing porosity and improving smoothness and compactness of a coating by adding sodium dodecyl sulfate into a plating solution, but the microscopic characterization of apparent crack condition of the coating is not carried out, and the corrosion resistance of the coating still needs to be improved.

Therefore, the existing electroless nickel-tungsten-phosphorus plating solution still has the problem of poor stability, and the formed plating layer has the defects of low hardness and poor corrosion resistance. In addition, the environmental friendliness of the chemical nickel, tungsten and phosphorus plating technology and the excellent performance of the plating layer are both problems which are urgently needed to be solved at present.

Disclosure of Invention

In view of the above-mentioned deficiencies of the prior art, the present invention aims to provide an electroless nickel-tungsten-phosphorus plating solution and an electroless plating method using the same, wherein the plating layer obtained by using the plating solution and the electroless plating method has the advantages of no crack, high hardness, excellent corrosion resistance and higher deposition rate.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides a chemical nickel-tungsten-phosphorus plating solution, which comprises at least one soluble nickel salt, wherein the concentration range of the soluble nickel salt is 10-25 g/L; at least one soluble tungstate, the concentration of which ranges from 20 to 42 g/L; hypophosphite as a reducing agent and providing a phosphorus source in a concentration range of 25-40 g/L; the composite brightener consists of 1-9mg/L tellurium dioxide, 5-12mg/L antimony potassium tartrate and 10-50mg/L saccharin sodium; the compound pinhole preventing agent consists of 3-10mg/L nonylphenol polyoxyethylene ether and 15-30mg/L lauryl sodium sulfate; the composite stabilizer consists of polysulfide 1-5mg/L, potassium iodate 6-12mg/L and sodium thiocyanate 3.5-7 mg/L; the complex complexing agent consists of 15-40g/L sodium citrate, 12-20g/L lactic acid and 0.1-0.5g/L triethanolamine.

In order to keep the plating solution in a stable state, a composite complexing agent consisting of sodium citrate, lactic acid and triethanolamine is used to control the concentration of free metal particles in the plating solution within an ideal range. The preferable concentration of the composite complexing agent is 17-29g/L of sodium citrate, 14-18g/L of lactic acid and 0.1-0.4g/L of triethanolamine. Meanwhile, in order to eliminate the spontaneous decomposition of the plating solution caused by some operation factors in the plating process, a composite stabilizer consisting of polysulfide, potassium iodate and sodium thiocyanate is adopted to further maintain the stability of the plating solution. Polysulfide, preferably isothiourea propane sulfonate inner salt, can be adsorbed to particles in the plating solution to inhibit nickel-tungsten-phosphorus codeposition reaction from occurring on these particles with strong surface activity, thereby inhibiting spontaneous decomposition of the plating solution. The preferable concentration of the composite stabilizer is 1.5-4mg/L of polysulfide, 6.5-11mg/L of potassium iodate and 3.6-5.5mg/L of sodium thiocyanate. The synergistic use of the complex complexing agent and the complex stabilizer can keep the deposition rate of the plating solution at 18-20 mu m/H, and meanwhile, the plating solution is stabilized for more than 8 periods.

The addition of the composite pinhole preventing agent can effectively reduce the porosity of the plating layer so as to obtain the microscopic crack-free plating layer. The preferable concentration of the composite pinhole preventing agent is 3.5-8mg/L of nonylphenol polyoxyethylene ether and 15.5-17mg/L of sodium dodecyl sulfate. Meanwhile, the composite brightener is added to improve the uniform glossiness and fineness of the coating. The preferable concentration of the composite brightener is 1-6 mg/L of tellurium dioxide, 5.5-8.5mg/L of antimony potassium tartrate and 12-18mg/L of saccharin sodium. The synergistic use of the composite pinhole preventing agent and the composite brightener can obviously improve the surface state of a plating layer, has no obvious cracks under microscopic detection, and has good glossiness. Meanwhile, the hardness of the plating layer is as high as 750HV0.1, and after heat treatment, the hardness is further increased to more than 1000HV 0.1. And the coating shows good corrosion resistance, and after 100 hours of CASS (copper salt accelerated acetate spray test), the coating is not corroded.

Wherein, the soluble nickel salt is used for providing nickel ions, and can be selected from one or more of nickel chloride, nickel sulfate, nickel formate and nickel acetate. One or two of nickel sulfate and nickel chloride are preferably used simultaneously. The tungstate is used to provide tungstate ions and may be selected from soluble tungstates, preferably sodium tungstate. Sodium hypophosphite is preferred as the reducing agent and as the hypophosphite that provides the phosphorus source.

Since hydrogen ions generated during plating may lower the pH of the plating solution, a buffer may be included in the plating solution as necessary to maintain the pH of the plating solution within a certain range. The buffer may be selected from weak acids and weak acid salts or polybasic weak acids, and one or more of them may be used together to construct a suitable and stable buffer system, including but not limited to ammonium acetate, boric acid, sodium carbonate or sodium bicarbonate, etc. Ammonium acetate in the range of 12 to 30g/L is preferred in the present invention.

The invention also provides a chemical plating method adopting the nickel-tungsten-phosphorus plating solution, which comprises the following steps: providing a substrate to be plated; preparing nickel-tungsten-phosphorus plating solution; adjusting the pH range of the plating solution to 8-10, preferably 8-8.5; immersing a substrate into the nickel-tungsten-phosphorus plating solution, and heating the nickel-tungsten-phosphorus plating solution to 85-90 ℃; and plating the nickel-tungsten-phosphorus plating solution on the substrate at a plating speed of 18-20 mu m/H.

The substrate to be plated is preferably a steel material, but the nickel-tungsten-phosphorus plating solution and the electroless plating method using the same are not limited to steel materials, and other metal or nonmetal material substrates, such as aluminum and aluminum alloys, zinc and zinc alloys, magnesium and magnesium alloys, glass, and the like, may be selected.

The preparation method of the nickel-tungsten-phosphorus plating solution adopts a general method to fully and uniformly mix the components with the above concentrations. The pH regulator is alkaline, and can be strong base or strong base weak acid salt, including but not limited to sodium hydroxide, ammonia water or sodium carbonate with appropriate concentration. In addition, the alkaline agent may be added multiple times to control the pH range, if necessary, based on the fact that the hydrogen ion concentration continues to increase during plating. The nickel-tungsten-phosphorus plating solution can be supplemented more than once in the plating process so as to maintain the concentration of each component in a proper range.

The electroless plating method described above may also include the use of particles that pretreat the substrate prior to plating using methods common in the electroless plating art to provide the substrate surface with a significant catalytically active effect. The pretreatment process includes, but is not limited to, grinding, degreasing, roughening, activating, washing, and the like.

The tungsten content in the plating layer formed by the plating solution and the chemical plating method is 5-15% (mass percent), and the preferable range is 5-8.1%.

The electroless plating method may further comprise a step of heat-treating the plated substrate at a temperature suitable for promoting the transformation of the plated layer from the amorphous state to the crystalline state, specifically, the second phase Ni₃The precipitation of P makes the P keep coherent relation with the mother phase Ni, thereby causing lattice distortion and hindering dislocation motionTherefore, a plated layer having a higher hardness can be obtained. The temperature of the heat treatment in the above-mentioned electroless plating method is preferably in the range of 300-400 ℃ and the time is preferably 1-2H, wherein as a further preferable aspect, the heat treatment temperature is 300 ℃ and the time is 2H. It should be appreciated that the selection of the heat treatment temperature and time will depend on the substrate material, the quality of the workpiece, etc., and thus the above-listed temperatures and times are not intended to limit the present invention.

Compared with the prior art, the invention has the beneficial effects that: the invention adds the compound complexing agent and the compound stabilizer to improve the deposition speed and the stability of the plating solution, the deposition rate reaches 18 to 20 mu m/H, and the plating solution is stable for more than 8 periods; the performance of the plating layer is improved by adopting the composite brightener and the composite pinhole preventing agent, the formed plating layer has continuous crystalline phase and no micro cracks, the plating state hardness of the plating layer is as high as 750HV0.1, and the hardness can reach more than 1100HV0.1 after heat treatment; the corrosion resistance of the plating layer is strong, and the corrosion phenomenon does not appear after 100 hours of CASS experiment.

Drawings

In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive efforts.

FIG. 1 is an SEM examination of the nickel tungsten phosphorous plating of example 1.

FIG. 2 is an EDS energy spectrum of the nickel tungsten phosphorous coating of example 1.

FIG. 3 is an SEM examination of the nickel tungsten phosphorous plating of example 3.

FIG. 4 is an EDS energy spectrum of the nickel tungsten phosphorous plating of example 3.

Detailed Description

The technical solutions in the specific embodiments of the present invention will be clearly and completely described below, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The first embodiment is as follows:

the chemical nickel-tungsten-phosphorus plating solution comprises the following components in concentration:

components	Concentration of	Components	Concentration of
				Nickel sulfate hexahydrate	15g/L	Sodium tungstate dihydrate	25g/L
Citric acid sodium salt dihydrate	20g/L	Triethanolamine	0.1g/L
				Lactic acid	14g/L	Ammonium acetate	12g/L
Sodium hypophosphite	25g/L	Isothiourea propanesulfonic acid inner salt	1.5 mg/L
				Potassium iodate	6.5 mg/L	Sodium thiocyanate	3.6 mg/L
Polyoxyethylene nonyl phenyl ether	3.5 mg/L	Sodium dodecyl sulfate	16 mg/L
				Tellurium dioxide	1mg/L	Antimony potassium tartrate	5.5mg/L
Saccharin sodium salt	15mg/L

The preparation method of the nickel-tungsten-phosphorus plating solution comprises the following steps: weighing a certain amount of the components by taking deionized water as a solvent, sequentially adding the weighed components into the deionized water to enable the concentration of each component to be as above, and mixing and stirring until each component is fully dissolved.

The pH value of the prepared plating solution is adjusted to 8.2 by a pH regulator and heated to 85-90 ℃. The substrate is made of pretreated 110s steel, and the temperature of the plating solution is kept stable in the immersion plating process.

After the 2H deposition of the coating, the coating deposition rate is measured to be 18-20 mu m/H by using a thickness gauge. And detecting the surface appearance of the coating by using a Scanning Electron Microscope (SEM). As shown in FIG. 1, the results of the tests show that the coating formed on the surface of the steel material by the nickel-tungsten-phosphorus plating solution and the electroless plating method has compact crystals and no cracks on the surface. The element content of the surface of the plating layer was measured by an X-ray energy spectrometer (EDS), and as shown in fig. 2, the Ni content was 76.8%, the W content was 8.1%, and the P content was 7.1% by mass.

Example two:

the chemical nickel-tungsten-phosphorus plating solution comprises the following components in concentration:

components	Concentration of	Components	Concentration of
				Nickel sulfate hexahydrate	14 g/L	Sodium tungstate dihydrate	25g/L
Citric acid sodium salt dihydrate	23 g/L	Triethanolamine	0.12 g/L
				Lactic acid	16.5 g/L	Ammonium acetate	13 g/L
Sodium hypophosphite	26.7 g/L	Isothiourea propanesulfonic acid inner salt	1.6 mg/L
				Potassium iodate	7.5 mg/L	Sodium thiocyanate	3.8 mg/L
Polyoxyethylene nonyl phenyl ether	5 mg/L	Sodium dodecyl sulfate	15.5 mg/L
				Tellurium dioxide	1.8 mg/L	Antimony potassium tartrate	6.5mg/L
Saccharin sodium salt	12 mg/L

The preparation method of the nickel-tungsten-phosphorus plating solution comprises the following steps: weighing a certain amount of the components by taking deionized water as a solvent, sequentially adding the weighed components into the deionized water to enable the concentration of each component to be as above, and mixing and stirring until each component is fully dissolved.

The pH value of the prepared plating solution is adjusted to 8.0 by a pH regulator and heated to 85-90 ℃. The substrate is made of pretreated 110s steel, and the temperature of the plating solution is kept stable in the immersion plating process.

After 2H deposition of the coating, the coating thickness was measured to be 39 μm using a thickness gauge. The coating state hardness is 560HV0.1, and the coating hardness is further increased by heat treatment at 300 ℃ for 2H, and can reach 1151HV 0.1. The coating obtained by the nickel-tungsten-phosphorus plating solution and the chemical plating method has higher hardness.

Example three:

the chemical nickel-tungsten-phosphorus plating solution comprises the following components in concentration:

components	Concentration of	Components	Concentration of
				Nickel sulfate hexahydrate	16 g/L	Sodium tungstate dihydrate	28 g/L
Citric acid sodium salt dihydrate	17 g/L	Triethanolamine	0.23 g/L
				Lactic acid	18 g/L	Ammonium acetate	14.2 g/L
Sodium hypophosphite	31 g/L	Isothiourea propanesulfonic acid inner salt	2.2 mg/L
				Potassium iodate	7.7 mg/L	Sodium thiocyanate	4 mg/L
Polyoxyethylene nonyl phenyl ether	5.3 mg/L	Sodium dodecyl sulfate	16.2 mg/L
				Tellurium dioxide	3.6 mg/L	Antimony potassium tartrate	7.5mg/L
Saccharin sodium salt	15 mg/L

The preparation method of the nickel-tungsten-phosphorus plating solution comprises the following steps: weighing a certain amount of the components by taking deionized water as a solvent, sequentially adding the weighed components into the deionized water to enable the concentration of each component to be as above, and mixing and stirring until each component is fully dissolved.

The pH value of the prepared plating solution is adjusted to 8.5 by a pH regulator and heated to 85-90 ℃. The substrate is made of pretreated 110s steel, and the temperature of the plating solution is kept stable in the immersion plating process.

The plating solution is enabled to work for 8.4 periods continuously, the surface morphology of the plating layer is detected by using an SEM after the plating solution works for 8.4 periods, the detection result is shown in figure 3, the plating layer is compact in crystallization, and the surface is obviously free of cracks. Similarly, the element content of the surface of the plating layer was measured by EDS, and as shown in fig. 4, the Ni content was 76.1%, the W content was 5.0%, and the P content was 9.5% by mass.

Example four:

the chemical nickel-tungsten-phosphorus plating solution comprises the following components in concentration:

components	Concentration of	Components	Concentration of
				Nickel sulfate hexahydrate	22 g/L	Sodium tungstate dihydrate	35 g/L
Citric acid sodium salt dihydrate	29 g/L	Triethanolamine	0.4 g/L
				Lactic acid	15.5 g/L	Ammonium acetate	20 g/L
Sodium hypophosphite	38 g/L	Isothiourea propanesulfonic acid inner salt	4 mg/L
				Potassium iodate	11 mg/L	Sodium thiocyanate	5.5 mg/L
Polyoxyethylene nonyl phenyl ether	8 mg/L	Sodium dodecyl sulfate	17 mg/L
				Tellurium dioxide	6 mg/L	Antimony potassium tartrate	8.5mg/L
Saccharin sodium salt	18 mg/L

The preparation method of the nickel-tungsten-phosphorus plating solution comprises the following steps: weighing a certain amount of the components by taking deionized water as a solvent, sequentially adding the weighed components into the deionized water to enable the concentration of each component to be as above, and mixing and stirring until each component is fully dissolved.

The pH value of the prepared plating solution is adjusted to 8.5 by a pH regulator and heated to 85-90 ℃. The substrate is made of pretreated 110s steel, and the temperature of the plating solution is kept stable in the immersion plating process.

After 2H deposition of the coating, the thickness of the coating was measured to be 40 μm using a thickness gauge. The corrosion resistance of the nickel-tungsten-phosphorus plating solution is tested, and the test result shows that the plating layer is not obviously corroded within 100 hours of the CASS test, which shows that the plating layer obtained by the nickel-tungsten-phosphorus plating solution and the chemical plating method has good corrosion resistance.

The chemical nickel-tungsten-phosphorus plating solution provided by the invention adopts a composite pinhole preventing agent, a composite brightening agent, a composite complexing agent and a composite stabilizer. The synergistic use of the composite pinhole preventing agent and the composite brightener can reduce the porosity of the plating, basically eliminate pinholes of the plating, effectively improve the corrosion resistance of the plating and ensure that the surface of the plating has good glossiness. The synergistic use of the composite complexing agent and the composite stabilizer can ensure that the plating solution has higher deposition speed and keeps good stability, and effectively prevents the spontaneous decomposition of the plating solution.

In addition, it should be understood that this specification uses specific examples to illustrate the invention, and the above description of the embodiments is only for the purpose of helping to understand the contents and core ideas of the invention. It should be noted that, for those skilled in the art, the description as a whole should be taken as an example, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art, and these embodiments also fall within the scope of the claims of the present invention.