Forward and reverse pulse electrolytic nickel-tungsten alloy solution, preparation method, electroplating method and nickel-tungsten alloy coating

Abstract

The present invention belongs to the technical field of electroplating nickel-tungsten alloy, and in particular, relates to a forward and reverse pulse electrolytic nickel-tungsten alloy solution, a preparation method, an electroplating method and a nickel-tungsten alloy coating. The nickel-tungsten alloy solution comprises: 20-150 g / L of nickel salt, 30-300 g / L of tungstate, 5-500 g / L of organic acid salt, 3-300 g / L of organic acid and 0.02-15 g / L of nitrogen-containing heterocyclic compound. The nickel-tungsten alloy coating electrolytically precipitated by the present invention is uniform and smooth, presents a submicron structure amorphous alloy surface morphology, has very high purity and excellent compactness, can provide a nickel-tungsten alloy electroplating product with uniform coating distribution, saves the amount of nickel-tungsten alloy used in plated parts, greatly reduces production costs, improves product quality, and can meet the development trend of the demand for high-end nickel-tungsten amorphous alloy materials in the field of high-tech electronic products and high-quality and high-precision mold products.

Description

Technical Field

[0001] The invention belongs to the technical field of nickel-tungsten alloy electroplating, and in particular relates to a forward and reverse pulse electrolytic nickel-tungsten alloy solution, a preparation method, an electroplating method and a nickel-tungsten alloy coating. Background Art

[0002] Nickel-tungsten alloy plating has the characteristics of dense and bright surface, high hardness, good wear resistance and strong corrosion resistance, and is widely used in new energy vehicles, aerospace, communications and other electronic products as well as high-precision mold products. However, non-patent literature (Electroplating and Finishing, 1998, 17 (3): pp22) points out that the nickel-tungsten alloy electroplating process generally has defects such as rough, uneven, and pitting coatings, which seriously restricts its application development.

[0003] The following patents also propose various methods for preparing nickel-tungsten amorphous alloy coatings.

[0004] Patent CN 115323448 A provides a nickel-tungsten alloy electrodeposition solution and an electrodeposition process. The nickel-tungsten alloy electrodeposition solution is made of nickel sulfate, sodium tungstate, sodium pyrophosphate, brightener, and stabilizer dissolved in deionized water. The nickel-tungsten alloy electrodeposition solution has excellent corrosion resistance and wear resistance, and the service life of the electrodeposition solution is long, which reduces the production cost, and the electrodeposited nickel-tungsten alloy coating is bright and dense.

[0005] The nickel-tungsten alloy coating provided by patent CN 115182009 A is dense, bright and highly corrosion-resistant. It can improve the electrochemical polarization in the coating process, refine the grains, optimize the leveling ability of the plating solution, and improve the brightness of the coating. At the same time, it provides a corrosion-resistant multilayer coating preparation process for situations where corrosion resistance requirements are more stringent.

[0006] The nickel-tungsten alloy electroplating solution and insoluble anode system provided by patent CN 114959812 A improve the current efficiency of the coating and reduce the hydrogen evolution process; they can effectively reduce the stress in the coating and reduce the generation of cracks after heat treatment. The filter membrane limits the organic matter in the plating solution from entering the anode chamber, preventing the decomposition of the organic matter, reducing the consumption of organic matter and the aging of the plating solution.

[0007] Patent CN 112111765 B provides a method for forming a nickel-tungsten alloy coating that can not only extend the service life of the electroplating solution, but also form a dense and bright coating on the workpiece.

[0008] Patent CN 105543910 B provides a method of using β-cyclodextrin as a grain refiner for electroplating nickel-tungsten alloy. The grain size of the nickel-tungsten alloy is significantly reduced during the deposition process. Moreover, the substance is very stable during the preparation process and will not affect the performance of the product. At the same time, it makes the coating more corrosion-resistant.

[0009] Patent CN 104032339 A The present invention relates to a method for controlling the structure of an electrodeposited nickel-tungsten alloy coating, which combines ultrasound, mechanical stirring and direct current, and uses the synergistic effect of the three to control the structure of the electrodeposited nickel-tungsten alloy coating by adjusting and controlling the temperature and current density of the electroplating. Compared with the prior art, the present invention is simple and easy to operate, the structure of the required device is simple, the structure of the nickel-tungsten alloy coating can be effectively controlled, and it is conducive to improving the production efficiency of the nickel-tungsten alloy coating, and has good application prospects.

[0010] However, the above existing electrolytic nickel-tungsten technologies do not solve the defects of rough, uneven, and pitted nickel-tungsten alloy coatings. Moreover, when using high-frequency DC power supplies and pulse power supplies, depending on the shape of the electrolytic product, the current distribution in the edge area of ​​the product is large, and the edge of the electrolytically deposited nickel-tungsten alloy coating is too thick; while the flat area in the middle of the product accounts for a large proportion of the surface and the current distribution is small, resulting in the nickel-tungsten alloy coating in the middle area being too thin. As a result, when the nickel-tungsten alloy coating in the middle area of ​​the product meets the requirements of the product technical standards, the nickel-tungsten alloy coating in the edge area of ​​the product has far exceeded the standard value, resulting in unnecessary waste, which not only increases production costs, but also causes friction damage to the subsequent product assembly, affecting the quality of high-end electronic products.

[0011] In view of this, the present invention is proposed. Summary of the invention

[0012] In order to solve the problems existing in the production and processing caused by the uneven coating of the nickel-tungsten alloy electroplating in the prior art, the present invention provides a forward and reverse pulse electrolytic nickel-tungsten alloy solution, a preparation method, an electroplating method and a nickel-tungsten alloy coating. The forward and reverse pulse electrolytic nickel-tungsten alloy solution of the present invention has the stable characteristics of withstanding the impact of forward and reverse pulse signals by adding organic acids and nitrogen-containing heterocyclic compounds, and has good stability under the condition of high-speed conversion of forward and reverse pulse power supply signals. The nickel-tungsten alloy coating prepared by the present invention through the optimized nickel-tungsten alloy solution and the forward and reverse pulse electroplating process is uniform and smooth, presents a submicron structure amorphous alloy morphology, has very high purity and density, and its quality is better than the submicron structure amorphous alloy prepared by the traditional chemical plating method and the electrolysis method usually using a high-frequency power supply and a pulse power supply. In addition, the present invention can obtain nickel-tungsten alloy electroplating products with uniform coating distribution, which saves the amount of nickel-tungsten alloy used for each plated part, greatly reduces production costs, improves product quality, and can meet the development trend of the demand for high-end nickel-tungsten amorphous alloy materials in the field of high-tech electronic products and high-quality and high-precision mold products.

[0013] The present invention is achieved through the following technical solutions:

[0014] The present invention provides a forward and reverse pulse electrolytic nickel-tungsten alloy solution, comprising the following components:

[0015] Nickel salts 20-150g / L, tungstates 30-300g / L, organic acid salts 5-500g / L, organic acids 3-300g / L and nitrogen-containing heterocyclic compounds 0.02-15g / L.

[0016] Preferably, the components used in the present invention are of high purity, which is beneficial to improving the purity of the electrolytic nickel-tungsten alloy solution and the performance of the coating.

[0017] Preferably, the nickel salt is one or more of nickel sulfate, nickel chloride, nickel nitrate, nickel sulfamate, nickel citrate, nickel carbonate, nickel bromide, nickel phosphate, nickel borate, nickel benzenesulfonate, nickel hypophosphite, and nickel 4-toluenesulfonate; the tungstate salt is one or more of sodium tungstate, potassium tungstate, ammonium tungstate, ammonium metatungstate, and ammonium metatungstate; the organic acid salt is one or more of salts of monocarboxylic acid to hexacarboxylic acid; the organic acid is one or more of monocarboxylic acid to hexacarboxylic acid; the nitrogen-containing heterocyclic compound is one or more of pyrrole, pyrazole, oxazole, thiazole, imidazole, pyridine, pyrimidine, azaindole, and pyrazine.

[0018] Preferably, the nickel salt is one or more of nickel sulfate, nickel chloride, nickel nitrate, nickel sulfamate, nickel citrate, nickel carbonate, nickel bromide, nickel phosphate, nickel borate, nickel benzenesulfonate, nickel hypophosphite, and nickel 4-toluenesulfonate; the tungstate salt is one or more of sodium tungstate, potassium tungstate, ammonium tungstate, ammonium metatungstate, and ammonium metatungstate; the organic acid salt is one or more of salts of monocarboxylic acid to hexacarboxylic acid; the organic acid is one or more of monocarboxylic acid to hexacarboxylic acid; the nitrogen-containing heterocyclic compound is one or more of pyrrole, pyrazole, oxazole, thiazole, imidazole, pyridine, pyrimidine, azaindole, and pyrazine.

[0019] Preferably, the organic acid salt is specifically sodium formate, ammonium formate, sodium acetate, ammonium acetate, sodium propionate, ammonium ethylenediaminetetraacetate, diammonium ethylenediaminetetraacetate monohydrate, tetrasodium ethylenediaminetetraacetate dihydrate, triammonium ethylenediaminetetraacetate, potassium ethylenediaminetetraacetate, tripotassium ethylenediaminetetraacetate, dipotassium ethylenediaminetetraacetate, ammonium hydroxyethyl sulfonate, dimethylamine 2-hydroxyethyl sulfonate, ammonium dihydrogen citrate, potassium dihydrogen citrate, diammonium hydrogen citrate, disodium citrate, trisodium citrate hydrate, trisodium citrate One or more of ammonium, choline dihydrogen citrate, choline citrate, ammonium oxalate, ammonium succinate, diethylenetriamine pentaacetic acid pentasodium, and phosphonic acid alkyl polycarboxylates; wherein the phosphonic acid alkyl polycarboxylates are one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid sodium salt, 2-phosphonobutane-1,2,4-tricarboxylic acid tetrasodium, 2-phosphonobutane-1,2,4-tricarboxylic acid potassium salt, diethylenetriamine penta methylenephosphonic acid heptasodium salt, and diethylenetriamine penta methylenephosphonic acid sodium salt;

[0020] The organic acids are specifically formic acid, acetic acid, malonic acid, ethylenediaminetetraacetic acid, 3-hydroxy-3-carboxyglutaric acid, propanetricarboxylic acid, propanetricarboxylic acid, 3-amino-1,1,3-propanetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, hydrolyzed ophiopogon acid, butanetetracarboxylic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, and one or more of phosphonic acid alkyl polycarboxylic acids; wherein the phosphonic acid alkyl polycarboxylic acids are one or more of diethylenetriaminepenta(methylenephosphonic acid) and triethylenetetraaminehexa(methylphosphonic acid).

[0021] Preferably, the pyrrole is one or more of 5-(pyrrolidin-3-yl)-2H-1,2,3,4-tetrazole hydrochloride, 3-methyl-5-pyrrole-1,2,4-oxadiazole, 2-(pyrrolidin-3-yl)ethane-1-ol hydrochloride, 4-pyrrolidin-1-pyridine-2-carboxylic acid hydrochloride, 4-(pyrrolidin-3-yl)pyridine hydrochloride, 1-(2-chlorobenzyl)-pyrrolidin-3-amine dihydrochloride, and 1-(4-chlorobenzyl)-pyrrolidin-3-amine dihydrochloride;

[0022] The pyrazoles are one or more of 5-amino-1-(2-hydroxyethyl)pyrazole, 5-amino-1-ethylpyrazole, 2-(4-bromo-1H-pyrazol-1-yl)ethanol, 2-(4-bromo-1H-pyrazol-1-yl)acetamide, 2-(4-bromo-1H-pyrazol-1-yl)propionamide, 4-amino-1-methyl-3-propylpyrazole-5-carboxamide hydrochloride, 5-amino-1-ethylpyrazole-4-carboxylic acid, and 5-amino-(2-hydroxyethyl)-4-pyrazolecarboxylic acid;

[0023] The oxazoles are one or more of 5-nitro-1,2-benzisoxazole, 3-amino-5-nitro-1,2-benzisoxazole, 3-chloro-7-nitro-1,2-benzisoxazole, 3-methyl-5-nitro-1,2-benzisoxazole, 5-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole, 6-nitro-1,2-benzisoxazole, 6-nitro-1,2-benzisoxazole-3-methanol, and 6-nitro-1,2-benzisoxazole-3-carboxylic acid;

[0024] The thiazole is one or more of 2-methyl 5-nitrothiazole, 3-amino-5-nitrobenzisothiazole, 2-methyl-5-nitrobenzisothiazole, 2-methyl-5-nitrobenzisothiazole, 2-methyl-5-phenyl-thiazole-4-carboxylic acid, 4-methyl-5-nitrothiazole, 2-amino-5-nitrothiazole, and 2-methyl-5-thiazolamine;

[0025] The imidazoles are one or more of 2-(difluoromethyl)-1-phenyl-4,5-dihydro-1H-imidazole, 2-methyl-5-nitroimidazole, 1-(2,3-dihydroxypropyl)-2-methyl-5-nitroimidazole, 1-propyl-2,3-methylimidazole tetrafluoroborate, 1-(2-iodoethyl)-2-methyl-5-nitro-1H-imidazole, 2-methyl-5-nitrobenzimidazole, 1-benzyl-2-methyl-5-nitro-1H-1,3-benzimidazole, and 2-mercapto-5-nitrobenzimidazole;

[0026] The pyridine is one or more of 2-(4-bromo-1H-pyrazol-1-yl)-5-fluoropyridine, 2-bromo-6-(1H-pyrazol-1-yl)pyridine, 2-(pyrrolidin-1-yl)pyridine-3-boric acid, 2-(4-bromopyrazol-1-yl)pyridine, 2-((4-iodo-1H-pyrazol-1-yl)methyl)pyridine, 2-(4-bromo-3-methyl-5-(trifluoromethyl)pyrazol-1-yl)-6-chloropyridine, 5-(chloromethyl)-2-(1H-pyrazol-1-yl)pyridine, 2-(4-bromo-1H-imidazol-1-yl)pyridine, and 1-benzenesulfonyl-3-iodo-1H-pyrrolo[2,3-B]pyridine;

[0027] The pyrimidines are one or more of 2-(4-bromo-1H-pyrazol-1-yl)pyrimidine, 2-(1H-pyrazol-1-yl)-5-(trifluoromethyl)pyrimidine, 2-(4-fluoro-1H-pyrazol-1-yl)pyrimidine-5-carboxylic acid, (9CI)-4-(1H-pyrazol-1-yl)-pyrimidine, 2,4-dichloro-5-(1H-pyrazol-1-yl)pyrimidine, 2-(1H-pyrazol-1-yl)-5-(trifluoromethyl)pyrimidine, 4-(4-bromo-1H-pyrazol-1-yl)-6-chloropyrimidine, and 4-chloro-6-(1H-pyrazol-1-yl)pyrimidine;

[0028] The azaindole is one or more of 4-bromo-2-iodo-N-toluenesulfonyl-7-azaindole, 4-bromo-1-toluenesulfonyl-7-azaindole, 2-difluoromethyl-1-benzenesulfonyl-7-azaindole, 4-bromo-2-iodo-7-azaindole, N-toluenesulfonyl-5-bromo-4,7-diazaindole, 1-benzenesulfonyl-4-chloro-2-iodo-7-azaindole, 2-iodo-1-benzenesulfonyl-7-azaindole, 2-methyl-1-(benzenesulfonyl)-7-azaindole, 2-difluoromethyl-1-benzenesulfonyl-7-azaindole, and 4-bromo-pyrrolo[2,3-F]-7-azaindole;

[0029] The pyrazines are one or more of 2-(4-bromo-1H-pyrazol-1-yl)pyrazine, pyrazine-2-boric acid, 2-(4-bromo-1H-pyrazol-1-yl)pyrazine, 3-(4-bromo-1H-pyrazol-1-yl)-6-chloropyrazine, 3-chloro-6-(4-iodo-1H-pyrazol-1-yl)pyrazine, 5-(1H-pyrazol-1-yl)pyrazine-2-carboxylic acid, and 2-bromo-5-(1H-pyrrol-1-yl)pyrazine.

[0030] The nickel-tungsten electrolyte in the prior art has the following problems when using the forward and reverse pulse method to electroplate the nickel-tungsten coating: (1) Although the nickel-tungsten alloy product can be obtained by electrolysis, the nickel-tungsten alloy solution will become turbid and unstable, and cannot be used in continuous electrolytic production; (2) During the electrolysis process, the nickel-tungsten alloy solution produces suspended particles, which co-precipitate with nickel tungsten, resulting in the nickel-tungsten alloy coating containing impurities; (3) No nickel-tungsten alloy coating can be obtained after electrolysis.

[0031] In view of the above problems, the present invention adds a carboxylic acid to the hexacarboxylic acid compound. The p-π conjugation effect in the carboxyl group is conducive to reducing the electron cloud density on the hydroxyl oxygen atom and enhancing the stability of the compound. The more carboxyl groups there are, the stronger the p-π conjugation effect is, and the better the thermal stability is. At the same time, the forward and reverse pulse electrolytic nickel-tungsten alloy solution has the properties of acid resistance, alkali resistance, and oxidant resistance, and can meet the strong impact of the instantaneous pulse of the reverse pulse power supply. In particular, the phosphonic acid alkyl polycarboxylic acid, in addition to having the characteristics of polycarboxylic acids, further enhances the stability through the support of the phosphonic acid alkyl, which is more conducive to improving the stability of the nickel-tungsten alloy solution.

[0032] The present invention adds monocarboxylic acid to hexacarboxylate compounds, which, in addition to having the characteristics of polycarboxylic acids, can also form a very stable buffer solution system with carboxylic acid compounds, maintaining the pH value of the solution between 7 and 8, which is very beneficial to the stability of the nickel-tungsten alloy solution. In particular, phosphonic acid alkyl polycarboxylates are more conducive to forming a very stable buffer solution system, improving the stability of the nickel-tungsten alloy during electrolysis.

[0033] The nitrogen on the five-membered ring and the six-membered ring of the nitrogen-containing heterocyclic compound of the present invention forms a composite salt with an acid, which reduces the electron cloud density of the heterocyclic ring, strengthens the electron-withdrawing inductive effect, has the characteristics of being not easily oxidized and resistant to strong electromagnetic fields, and thus improves the effect of forward and reverse pulse electroplating of nickel-tungsten alloy.

[0034] The present invention also provides a method for preparing the forward and reverse pulse electrolytic nickel-tungsten alloy solution, comprising the following steps:

[0035] S1. Add nickel sulfate in small amounts and multiple times to a portion of pure water under heating and stirring conditions;

[0036] S2. After all the nickel sulfate is dissolved, add organic acid in small amounts several times;

[0037] S3, after the organic acid is completely dissolved, add the organic acid salt in small amounts and multiple times;

[0038] S4. After all the organic acid salts are dissolved, the pH value of the solution is tested and the pH value is controlled within the range of 7.0-8.0;

[0039] S5, add tungstate in small amounts and multiple times, and after the tungstate is completely dissolved, add nitrogen-containing heterocyclic compounds in small amounts and multiple times;

[0040] S6. After all the nitrogen-containing heterocyclic compounds are dissolved, stir evenly and add some pure water to obtain the forward and reverse pulse electrolytic nickel-tungsten alloy solution.

[0041] The heating temperature is 40-60°C. In S4, if the pH is lower than 7.0, an organic acid salt is added for adjustment. If the pH is higher than 8.0, an organic acid is added for adjustment.

[0042] The present invention also provides a method for electroplating nickel-tungsten alloy using forward and reverse pulses, comprising the following steps:

[0043] (1) Place the nickel-tungsten alloy electrolyte into the electrolytic cell and heat it to 40-60°C;

[0044] (2) Connect the nickel plate to the positive electrode of the pulse reverse power supply through the positive conductive connecting rod, and connect the plated part to the negative electrode of the pulse reverse power supply through the negative conductive connecting rod;

[0045] (3) Electroplating with forward and reverse pulses: applying a forward pulse current I1 for a forward pulse time of t1, then applying a reverse pulse current I2 for a reverse pulse time of t2, to complete a cycle of forward and reverse pulse electroplating;

[0046] (4) Repeat the forward and reverse pulse cycle of step (3) until the set electroplating time is over.

[0047] It should be noted that when the forward and reverse pulse cycles of the present invention are used to electroplate the nickel-tungsten alloy coating, within one cycle, when the forward pulse is first applied, the edge coating is thicker due to the high current distribution in the edge area of ​​the plated piece, and when the reverse pulse is applied, the plated piece will undergo anodization dissolution. Similarly, due to the high current distribution in the edge area of ​​the plated piece, the edge coating dissolves faster than the middle area, ultimately making the thickness of the entire coating product uniform. In addition, due to the anodic dissolution during the reverse pulse, the inclusion of impurities in the coating is greatly reduced, thereby improving the purity and density of the coating.

[0048] Furthermore, the current density of the forward pulse current in step (3) is in the range of 0.5-30.0A / dm 2 , the current density range of the reverse pulse current is 5.0-100.0A / dm 2 .

[0049] From the above, it can be seen that in each forward and reverse pulse cycle, the setting of the pulse current and pulse time will affect the quality of the entire coating. As a priority solution, the ratio of t1 to t2 is in the range of (10-100):1; the ratio of I1 to I2 is in the range of 1:(2-5). By setting the forward pulse current and reverse pulse current size and pulse time, the deposition rate and dissolution rate of the edge and middle areas of the nickel-tungsten coating can be effectively controlled, so that the thickness of the edge and middle areas of the nickel-tungsten alloy coating obtained by electroplating is uniform.

[0050] Preferably, the electroplating time is 1-100 min, and the thickness of the nickel-tungsten alloy coating obtained by electroplating is 0.5-100 μm.

[0051] Preferably, the method is used for roll plating, rack plating and continuous production lines of nickel-tungsten amorphous alloy materials. More preferably, the method is used for surface electrolytic machining of through holes, blind hole inner walls and inner walls of tiny precision products.

[0052] The present invention also provides a nickel-tungsten alloy coating obtained by electroplating according to the method, wherein the composition of the nickel-tungsten alloy coating is Ni 100-m W m , m is the percentage of tungsten atoms, and 43.43%≤m≤53.52%.

[0053] Compared with the prior art, the beneficial effects of the present invention are:

[0054] (1) The present invention adds organic acids, organic acid salts and nitrogen-containing heterocyclic compounds to the forward and reverse pulse electrolytic nickel-tungsten alloy solution, so that the nickel-tungsten alloy solution has stable characteristics of withstanding the impact of forward and reverse pulse signals. Under the condition of high-speed conversion of forward and reverse pulse power supply signals, the nickel-tungsten alloy solution has good stability, avoiding turbidity of the nickel-tungsten alloy solution and the problem of suspended particles in the nickel-tungsten alloy solution co-precipitating with the nickel-tungsten alloy, resulting in the nickel-tungsten alloy coating containing impurities, thereby ensuring that the subsequent electroplating products have good quality.

[0055] (2) In the process of forward and reverse pulse electroplating of nickel-tungsten alloy coating, a nickel-tungsten alloy coating with uniform thickness is obtained by cyclically applying forward pulses and reverse pulses. Compared with the existing electroplating technology, when electroplating nickel-tungsten alloy coating, the coating formed by the electroplating method of the present invention has good uniformity and can save the amount of nickel-tungsten alloy used. Moreover, the thicker the coating of the nickel-tungsten alloy-plated part, the more nickel-tungsten alloy can be saved by the electroplating method of the present invention.

[0056] (3) The present invention uses an optimized nickel-tungsten alloy solution and forward and reverse pulse parameters to form the electroplating process of the present invention. The nickel-tungsten alloy coating prepared is uniform and smooth, presents a submicron structure amorphous alloy morphology, has very high purity and density, and its quality is superior to the submicron structure amorphous alloy prepared by the traditional chemical plating method and the electrolysis method usually using high-frequency power supply and pulse power supply. In particular, it provides a very effective preparation method for the surface electrolytic processing of products with through holes, blind hole inner walls and small and precise inner walls of various shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0058] Figure 1 Schematic diagram of the forward and reverse pulse electroplating nickel-tungsten alloy device of the present invention, wherein (a) is a schematic diagram of applying a forward pulse current, and (b) is a schematic diagram of applying a reverse pulse current;

[0059] Figure 2 This is a schematic diagram of the pulse reverse power supply electrolysis of the present invention;

[0060] Figure 3 This is a schematic diagram of the test point distribution;

[0061] Figure 4 is an enlarged schematic diagram of test point A;

[0062] Figure 5 This is the appearance diagram of Example 3;

[0063] Figure 6 This is an appearance diagram of Example 9;

[0064] Figure 7This is the rough appearance picture of Comparative Example 3;

[0065] Figure 8 This is a rough appearance diagram of Comparative Example 9;

[0066] Fig. 9 This is the pitted outer tube diagram of Comparative Example 6;

[0067] Fig.10 This is the appearance diagram of pitting of Comparative Example 7;

[0068] Fig.11 This is a graph showing the nitric acid vapor test results of Example 3;

[0069] Fig.12 This is a graph showing the nitric acid vapor test results of Example 9;

[0070] Fig.13 The friction and wear test result spectrum of Example 3;

[0071] Fig.14 This is a graph showing the test results of the friction and wear test of Comparative Example 9;

[0072] Fig.15 This is a graph showing the surface roughness test results of Example 3;

[0073] Fig.16 This is a graph showing the surface roughness test results of Comparative Example 9;

[0074] Fig.17 This is a nitric acid vapor test diagram of the copper sheet sample of Example 11;

[0075] Fig.18 This is a nitric acid vapor test diagram of the copper sheet sample of Example 13;

[0076] Fig.19 This is a nitric acid vapor test diagram of the terminal sample of Example 11;

[0077] Fig. 20 This is a nitric acid vapor test diagram of the terminal sample of Example 13;

[0078] Fig.21 This is the X-ray diffraction pattern of Example 3. DETAILED DESCRIPTION

[0079] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] Example 1

[0081] The present embodiment provides a forward and reverse pulse electrolytic nickel-tungsten alloy solution, including: 28 g / L nickel sulfate, 165 g / L sodium tungstate, 83 g / L 1,2,4-butanetricarboxylic acid, 320 g / L 2-phosphonobutane-1,2,4-tricarboxylic acid sodium salt, and 0.7 g / L 2-(pyrrolidin-3-yl)ethane-1-ol hydrochloride.

[0082] The preparation method of the nickel-tungsten alloy electrolyte comprises the following steps:

[0083] S0, add 10 liters of pure water to the clean 20-liter electrolytic cell 50, turn on the internal circulation pump power supply, and turn on the heating system to heat up while the pure water circulates and stirs;

[0084] S1. When the pure water temperature in the electrolytic cell reaches 50°C, 420 g of nickel sulfate is added to the electrolytic cell 50 in small amounts and multiple times;

[0085] S2. After all the nickel sulfate in the electrolytic cell 50 is dissolved, 1245 g of 1,2,4-butanetricarboxylic acid is added to the electrolytic cell 50 in multiple portions;

[0086] S3. After all the 1,2,4-butanetricarboxylic acid in the electrolytic cell 50 is dissolved, 4800 g of 2-phosphonobutane-1,2,4-tricarboxylic acid sodium salt is added to the electrolytic cell 50 in multiple portions;

[0087] S4. After the sodium salt of 2-phosphonobutane-1,2,4-tricarboxylate in the electrolytic cell 50 is stirred evenly, the solution prepared in the electrolytic cell 50 is tested with a pH meter to control the pH value in the range of 7.0-8.0; if the pH value is lower than 7.0, an organic acid salt is added; if the pH value is higher than 8.0, an organic acid is added for adjustment;

[0088] S5, adding 2475 g of sodium tungstate into the electrolytic cell 50 in small amounts and multiple times;

[0089] S6. After the sodium tungstate in the electrolytic cell 50 is stirred evenly, 10.5 g of 2-(pyrrolidin-3-yl)ethane-1-ol hydrochloride is added to the electrolytic cell 50 in small amounts and in multiple times;

[0090] S7. When the 2-(pyrrolidin-3-yl)ethane-1-ol hydrochloride is completely dissolved, pure water is added to make the volume of the solution in the electrolytic cell 50 reach 15 liters to obtain a nickel-tungsten alloy electrolyte 10 for standby use.

[0091] In this embodiment, the plated material selected is copper alloy, with a size of 100×70 mm and a thickness of 0.3 mm. After degreasing, acid activation and drying, it is precisely weighed with an HR-120 electronic balance. The sample weight is 18.7263 grams and electrolytic treatment is carried out according to the following steps.

[0092] like Figure 1 As shown, the method of electroplating nickel-tungsten alloy by forward and reverse pulses is used. When the forward pulse is running, the nickel plate 20 is printed with the positive electrode and the plated part 30 is printed with the negative electrode ( Figure 1 As shown in (a), when the reverse pulse is running, the nickel plate 20 is printed with the negative electrode and the plated part 30 is printed with the positive electrode ( Figure 1 As shown in (b), electroplating of nickel-tungsten alloy is performed, and the coating thickness is required to be 1 μm, which specifically includes the following steps:

[0093] (1) directly using the prepared nickel-tungsten alloy electrolyte 10 in the electrolytic cell 50 and heating it to 55° C.;

[0094] (2) A copper plate with a size of 100×70 mm and a thickness of 0.3 mm is used as the plated component 30. One side of the plated component 30 is bonded and masked with a special protective film, and only the other side is exposed and placed opposite to the nickel plate 20.

[0095] (3) The plated part 30 after the shielding treatment is subjected to ultrasonic degreasing treatment for 15 seconds, and then cleaned with pure water; the cleaned plated part 30 is subjected to cathode electrolysis treatment for 10 seconds, and then cleaned with pure water; then it is subjected to acid activation treatment for 20 seconds, and then treated with pure water;

[0096] (4) Connect the nickel plate 20 to the positive electrode of the pulse reverse power supply 100 through the positive conductive connecting rod 21, and connect the plated component 30 to the negative electrode of the pulse reverse power supply 100 through the negative conductive connecting rod 31;

[0097] (5) Use forward and reverse pulses for electroplating, such as Figure 2 As shown, the forward pulse current I1 is 5A, the forward pulse time t1 is 20 milliseconds, and the pause is 1 millisecond. Then the reverse pulse current I2 is 15A, and the reverse pulse time t2 is 2 milliseconds, completing a cycle of forward and reverse pulse electroplating.

[0098] (6) Repeat the forward and reverse pulse cycles of step (5) until the total electroplating time ends after 1-3 minutes. Remove the special protective film to obtain a nickel-tungsten alloy coating.

[0099] Example 1 was carried out according to Figure 3Test at five test points A, B, C, D, and E. Figure 4 1-5 data in ( Figure 4 Taking the upper left corner as the zero point, the coordinates of No. 1 are (2, 2), No. 2 are (2, 6), No. 3 are (6, 6), No. 4 are (6, 2), and No. 5 are (4, 4). The test results are shown in Table 1:

[0100] Table 1 Test results of nickel-tungsten alloy coating in Example 1 (μm)

[0101] 1 2 3 4 5 Ave. A 1.213 1.196 1.165 1.184 1.174 1.186 B 1.193 1.186 1.156 1.195 1.165 1.179 C 1.202 1.194 1.167 1.186 1.173 1.184 D 1.211 1.195 1.163 1.183 1.166 1.183 E 1.154 1.166 1.145 1.154 1.136 1.151 Ave. 1.194 1.187 1.159 1.180 1.163 1.177

[0102] This embodiment requires the coating thickness to be 1μm, the standard test point is the center E5, and the high-precision XRF analyzer FISCHERSCOPE X-RAY XDV-SDD is used to detect the nickel-tungsten thickness to be 1.136μm. The S-4800 scanning electron microscope / X-ray spectrometer test results show that the tungsten content is 53.52%. The electronic balance is used for precise weighing, and the weight of the nickel-tungsten alloy product is 18.9676 grams; that is, the weight of the nickel-tungsten alloy coating = 18.9676-18.7263 = 0.2413 grams.

[0103] It can be seen from Table 1 that the average coating thickness of the five test points A to E in Example 1 is 1.177 μm.

[0104] According to the above results, under the condition that the tungsten content of Example 1 is 53.52%, the theoretically calculated coating weight is 0.2040 g when the product specification coating is 1 μm;

[0105] Example 1 Nickel tungsten 0.2413 - Standard nickel tungsten 0.2040 = 0.0373 g;

[0106] That is, the coating weight of Example 1 is 0.0373 grams more than the coating weight of the product specification, accounting for 18.3%.

[0107] The nickel-tungsten alloy coating of Example 3 was tested using a Rigaku X-ray diffractometer Ultima IV. The results are as follows: Fig.21 shown.

[0108] from Fig.21 The 2θ-θX-ray diffraction method shows that when the X-ray incident angle is 15°, in addition to the wide and short diffraction peak of nickel-tungsten, the diffraction peak of the plated material copper is still relatively obvious; when the X-ray incident angle is reduced to 5°, the diffraction peak of the plated material copper has almost disappeared; when the X-ray incident angle is reduced to 2°, only a wide and short diffraction peak is presented, indicating that the nickel-tungsten alloy coating is an amorphous structure.

[0109] Embodiment 2-10

[0110] The composition of the forward and reverse pulse electrolytic nickel-tungsten alloy solution provided in Example 2-10 is shown in Table 2. The preparation method of the nickel-tungsten alloy electrolyte in Example 2-10 is the same as that in Example 1. The nickel-tungsten alloy coating test in Example 2-10 is the same as that in Example 1, and the test data are listed in Table 5. The method of electroplating the nickel-tungsten alloy coating in Examples 2 to 10 is basically the same as that in Example 1, except that:

[0111] The total electroplating time of Example 2 is 3 to 9 minutes, the coating thickness is 3.0 μm, and the tungsten content is 45.72%;

[0112] The total electroplating time of Example 3 is 5 to 11 minutes, the coating thickness is 5.0 μm, and the tungsten content is 48.63%;

[0113] The total electroplating time of Example 4 is 13 to 21 minutes, the coating thickness is 10.0 μm, and the tungsten content is 49.18%;

[0114] The total electroplating time of Example 5 is 30 to 45 minutes, the coating thickness is 30.0 μm, and the tungsten content is 43.52%;

[0115] The total electroplating time of Example 6 is 50 to 65 minutes, the coating thickness is 50.0 μm, and the tungsten content is 47.91%;

[0116] The total electroplating time of Example 7 is 5 to 11 minutes, the coating thickness is 5.0 μm, and the tungsten content is 45.75%;

[0117] The total electroplating time of Example 8 was 13 to 21 minutes, the coating thickness was 10.0 μm, and the tungsten content was 48.47%;

[0118] The total electroplating time of Example 9 is 30 to 45 minutes, the coating thickness is 30.0 μm, and the tungsten content is 46.25%;

[0119] The total electroplating time of Example 10 is 50-65 minutes, the coating thickness is 50.0 μm, and the tungsten content is 43.43%.

[0120] Table 2 Composition of nickel-tungsten alloy solutions of Examples 1 to 10 (g / L)

[0121]

[0122]

[0123] Comparative Examples 1-12

[0124] The composition of the forward and reverse pulse electrolytic nickel-tungsten alloy solution provided in Comparative Examples 1-12 is shown in Table 3. The preparation method of the nickel-tungsten alloy electrolyte in Comparative Examples 1-12 is the same as that in Example 1. The nickel-tungsten alloy coating test in Comparative Examples 1-12 is the same as that in Example 1, and the test data are listed in Table 5. The method of electroplating the nickel-tungsten alloy coating in Comparative Examples 1 to 12 is basically the same as that in Example 1, except that:

[0125] Comparative Examples 1-4 and Comparative Examples 9-12 use a high frequency power supply, and Comparative Examples 5-8 use a reverse pulse power supply;

[0126] The total electroplating time of Comparative Example 2 was 2 to 6 minutes, the coating thickness was 5.0 μm, and the tungsten content was 37.27%;

[0127] The total electroplating time of Comparative Example 3 was 3 to 9 minutes, the coating thickness was 10.0 μm, and the tungsten content was 35.56%;

[0128] The total electroplating time of Comparative Example 4 was 37 to 48 minutes, the coating thickness was 50.0 μm, and the tungsten content was 38.73%;

[0129] The total electroplating time of Comparative Example 6 was 3 to 9 minutes, the coating thickness was 3.0 μm, and the tungsten content was 37.61%;

[0130] The total electroplating time of Comparative Example 9 was 1 to 3 minutes, the coating thickness was 1.0 μm, and the tungsten content was 35.32%;

[0131] The total electroplating time of Comparative Example 10 is 2 to 6 minutes, the coating thickness is 5.0 μm, and the tungsten content is 37.65%;

[0132] The total electroplating time of Comparative Example 11 was 3 to 9 minutes, the coating thickness was 10.0 μm, and the tungsten content was 36.27%;

[0133] The total electroplating time of Comparative Example 12 was 37 to 48 minutes, the coating thickness was 50.0 μm, and the tungsten content was 39.71%;

[0134] Table 3 Composition of nickel-tungsten alloy solutions of Comparative Examples 1 to 12 (g / L)

[0135]

[0136]

[0137]

[0138] Table 4 Test results of nickel-tungsten alloy coating of comparative example 1 (μm)

[0139] 1 2 3 4 5 Ave. A 1.935 1.935 1.874 1.815 1.154 1.743 B 1.917 1.914 1.853 1.794 1.146 1.725 C 2.014 1.954 1.892 1.888 1.162 1.782 D 1.975 1.976 1.865 1.876 1.153 1.769 E 1.193 1.202 1.194 1.190 1.194 1.194 Ave. 1.807 1.796 1.735 1.712 1.162 1.642

[0140] Comparative Example 1 requires a coating thickness of 1 μm, a standard test point is the center E5, and the weight of the sample before plating is 18.4713 grams; the nickel-tungsten thickness at the center E5 of Comparative Example 1 is 1.194 μm.

[0141] The results of testing using S-4800 scanning electron microscope / X-ray spectrometer showed that the tungsten content was 36.41%.

[0142] The weight of the nickel-tungsten alloy product is 18.7642 grams when accurately weighed using an electronic balance; that is, the weight of the nickel-tungsten alloy coating = 18.7642-18.4713 = 0.2929 grams;

[0143] It can be seen from Table 4 that the average coating thickness of the five test points A to E in Comparative Example 1 is 1.642 μm.

[0144] According to the above results, under the condition that the tungsten content of comparative example 1 is 36.41%, the theoretically calculated coating weight is 0.1789 g when the product specification coating is 1.0 μm;

[0145] Comparative Example 1 Nickel Tungsten 0.2929 - Standard Nickel Tungsten 0.1789 = 0.1140 g;

[0146] That is, the coating weight of Comparative Example 1 is 0.1140 g more than the coating weight of the product specification, accounting for 63.7%.

[0147] By comparing the results of Example 1 in Table 1 with the results of Comparative Example 1 in Table 3, it can be seen that when the power supply used is replaced by the high-frequency power supply of Comparative Example 1 instead of the reverse pulse power supply of Example 1, the nickel-tungsten alloy coating of Comparative Example 1 has a very different thickness depending on the position, and the edge of the product is much higher than the middle. The coating test results and the weight difference data before and after plating confirm that the reverse pulse electroplating method of the present invention is beneficial to improving the uniformity of the nickel-tungsten alloy coating. At the same time, it can greatly save the amount of nickel-tungsten alloy used in the plated parts, thereby reducing production costs.

[0148] Table 5 Test results of the nickel-phosphorus alloy coatings obtained in Examples 1-10 and Comparative Examples 1-12

[0149]

[0150]

[0151] It can be seen from the results in Table 5 that the nickel-tungsten alloy solutions of the present invention in Examples 1 to 10 adopt reverse pulse electrolysis technology to obtain nickel-tungsten alloy coating products with a tungsten content of 43.43% to 53.52%. The product specification requires a coating range of 1.0 μm to 50.0 μm, and the actual tested coating range is 1.183 μm to 59.656 μm; the weight range of the nickel-tungsten alloy increased before and after the electrolysis is 0.2413 g to 11.5995 g.

[0152] The nickel-tungsten alloy solutions of the present invention in Examples 1 to 4 and the nickel-tungsten alloy solutions of the prior art in Examples 9 to 12 are electrolyzed using a high-frequency power supply to obtain nickel-tungsten alloy coating products with a tungsten content of 35.56% to 38.73%. The product specifications also require a coating range of 1.0 μm to 50.0 μm, and the actual tested coating range is 1.586 μm to 83.051 μm; the weight of the nickel-tungsten alloy increased before and after the electrolysis is 0.2812 g to 15.2602 g.

[0153] When the prior art nickel-tungsten alloy solutions of Comparative Examples 5 to 8 are electrolyzed using a reverse pulse power supply, only Comparative Example 6 can obtain test data, and there are the following problems: (1) nickel-tungsten alloy cannot be obtained by electrolysis; (2) during the electrolysis process, the nickel-tungsten alloy solution becomes turbid and the nickel-tungsten coating has pitting; (3) the nickel-tungsten alloy coating obtained by electrolysis is rough and dull; (4) a nickel-tungsten alloy product can be obtained in the early stage of electrolysis, but after several hours of use, the solution becomes turbid and foreign matter adheres to the surface of the nickel-tungsten coating.

[0154] Furthermore, the measured nickel-tungsten alloy coating weights of Examples 1 to 10 are compared with the standard nickel-tungsten nickel-tungsten alloy coating weights required by product specifications, and the increased weight percentages range from 17.2% to 19.5%; while the increased weight percentages of Comparative Examples 1 to 12 range from 58.6% to 66.1%.

[0155] It can be seen from the above data that no matter whether it is the nickel-tungsten alloy solution examples 9 to 12 of the prior art or the nickel-tungsten alloy solution examples 1 to 4 of the present invention, no matter whether a conventional high-frequency power supply or a single-pulse power supply is used, the obtained nickel-tungsten alloy coating has the problem of uneven distribution; all the problems existing in the above-mentioned prior art can be completely solved by the nickel-tungsten alloy solution and reverse pulse electrolysis process technology of the present invention.

[0156] Furthermore, the appearance of the coatings of Examples 1 to 10 and Comparative Examples 1 to 12 was examined by optical microscopy, and the results are listed in Table 6.

[0157] The porosity of the nickel-tungsten alloy coating was determined by the nitric acid vapor test according to the national standard GB / T 19351-2003 / ISO14647:2000. The sample was cut into 3mm×3mm pieces, and the four sides and the back were bonded with 3M electroplating protection tape, leaving a single side of 2mm×2mm for the test. The test time was 2 hours. The test results are listed in Table 6.

[0158] The high temperature life test of nickel-tungsten alloy coating was carried out according to the national standard GJB360A-96, with a high temperature of 300° and a test time of 2 hours. The test results are listed in Table 6.

[0159] The sliding friction and wear test of the nickel-tungsten alloy coating was carried out according to the national standard GB-T 12444-2006 and tested by CSM ball friction and wear testing equipment; the larger the friction and wear value, the greater the surface roughness of the nickel-tungsten alloy, or the lower the hardness of the nickel-tungsten alloy coating. The experimental results are listed in Table 6.

[0160] The surface roughness of the nickel-tungsten alloy coating was implemented according to the national standard GB3505-83. The surface roughness was tested using a 3D profile measuring instrument VR-5000 manufactured by Keyence. The experimental results are listed in Table 6.

[0161] Table 6 Test results of the nickel-phosphorus alloy coatings obtained in Examples 1 to 10 and Comparative Examples 1 to 12

[0162]

[0163]

[0164] * Excellent: no corrosion spots; Good: one small spot; Slightly corroded: two small spots; Corroded: 3 spots or more.

[0165] From Table 6, the coating appearances of Examples 1 to 10 are semi-bright, bright, and smooth and bright, and the coating appearances of Comparative Examples 1 to 12 are semi-bright, bright, and smooth and bright;

[0166] From the nitric acid vapor test results of the nickel-tungsten alloy coating porosity determination, Examples 1 to 10 were excellent and good, and Comparative Examples 1 to 12 were good, slightly corrosive, and corrosive;

[0167] From the high temperature test results of the nickel-tungsten alloy coating, Examples 1 to 10 were excellent and good, while Comparative Examples 1 to 12 were good, peeling, and pitting;

[0168] From the results of the sliding friction and wear test of the nickel-tungsten alloy plated ball, the friction and wear amount of Examples 1 to 10 is 0.7mg to 1.7mg, and after removing 1.7mg of Example 1, the range is 0.7mg to 1.1mg; while the friction and wear amount of Comparative Examples 1 to 12 is 2.1mg to 2.9mg;

[0169] From the test results of the surface roughness of the plated copper alloy material, the average arithmetic roughness of Examples 1 to 10 is 0.431 μm to 0.438 μm; the average arithmetic roughness of Comparative Examples 1 to 12 is 0.432 μm to 0.439 μm;

[0170] From the test results of the surface roughness of the nickel-tungsten alloy coating, the roughness of Examples 1 to 10 is 0.443 μm to 0.449 μm; the average arithmetic roughness of Comparative Examples 1 to 12 is 0.631 μm to 0.647 μm;

[0171] From the results of Table 5 and Table 6, the experimental result of Example 1 in which the tungsten content of the nickel-tungsten alloy coating is ≥50% is not ideal. The tungsten contents of Examples 2 to 10 are 43.43% to 49.18%, and all the experimental results are excellent. However, the tungsten contents of Comparative Examples 1 to 12 are 35.56% to 39.71%, and their comprehensive experimental results are not ideal, and defects such as roughness, unevenness, and pitting of the nickel-tungsten alloy coating still exist.

[0172] In summary, the process technology provided by the present invention solves the defects of the nickel-tungsten alloy coating in the prior art, such as roughness, unevenness, pitting, etc.

[0173] Embodiment 11

[0174] The formula of the nickel-tungsten alloy solution is the same as that of Example 3. The material is a copper alloy terminal composed of 5 metal needles and a copper sheet of 30mm×30mm and 0.2mm thickness. The nickel-tungsten alloy coating is 1.5μm and then gold-plated 0.1μm.

[0175] Comparative Example 13

[0176] The formula of the nickel-tungsten alloy solution is the same as that of comparative example 9. The material is a copper alloy terminal composed of 5 metal needles and a copper sheet of 30mm×30mm and 0.2mm thickness, with a nickel-tungsten alloy coating of 1.5μm and then gold plating of 0.1μm.

[0177] The porosity of the nickel-tungsten alloy coating was determined by the nitric acid vapor test according to the national standard GB / T19351-2003 / ISO14647:2000. The copper sheet sample was bonded with 3M electroplating protection tape on all sides and the back, exposing a single side of 20mm×20mm for the test. Similarly, the terminal sample was also bonded with 3M electroplating protection tape on all sides and the back, exposing a single side of 20mm×20mm for 7 hours. The results are listed in Table 7.

[0178] Table 7 Nitric acid vapor test results of Example 11 and Comparative Example 13

[0179]

[0180] From the nitric acid vapor test results of the connector terminal gold-plated material shown in Table 7, the nickel-tungsten alloy coating / gold-plated composite material of the present invention does not corrode under long-term strong nitric acid vapor test conditions compared with the composite material of the prior art, and has very excellent corrosion resistance.

[0181] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A forward and reverse pulse electroplating nickel-tungsten alloy solution, characterized in that: It is composed of the following components: Nickel salts 28-150g / L, tungstates 165-300g / L, organic acid salts 100-500g / L, organic acids 70-300g / L and nitrogen-containing heterocyclic compounds 0.02-15g / L; The nickel salt is one or more of nickel sulfate, nickel chloride, nickel nitrate, nickel sulfamate, nickel citrate, nickel carbonate, nickel bromide, nickel benzenesulfonate, and nickel 4-toluenesulfonate; The tungstate salt is one or more of sodium tungstate, potassium tungstate, ammonium tungstate, and ammonium metatungstate; The nitrogen-containing heterocyclic compound is one or more of pyrrole, pyrazole, oxazole, thiazole, imidazole, pyridine, pyrimidine, azaindole, and pyrazine; The organic acid salts are specifically one or more of sodium formate, ammonium formate, sodium acetate, ammonium acetate, sodium propionate, ethylenediaminetetraacetic acid diammonium monohydrate, ethylenediaminetetraacetic acid tetrasodium salt dihydrate, ethylenediaminetetraacetic acid triammonium salt, ethylenediaminetetraacetic acid tripotassium salt, ethylenediaminetetraacetic acid dipotassium salt, hydroxyethyl sulfonic acid ammonium salt, 2-hydroxyethyl sulfonic acid dimethylamine, oxalic acid ammonium salt, succinic acid ammonium salt, 2-phosphonobutane-1,2,4-tricarboxylic acid tetrasodium, 2-phosphonobutane-1,2,4-tricarboxylic acid potassium salt, diethylenetriaminepentaacetic acid pentasodium salt, diethylenetriaminepentamethylenephosphonic acid heptasodium salt, and diethylenetriaminepentamethylenephosphonic acid sodium salt; The organic acid is specifically one or more of formic acid, acetic acid, malonic acid, ethylenediaminetetraacetic acid, 3-hydroxy-3-carboxyglutaric acid, propanetricarboxylic acid, 3-amino-1,1,3-propanetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, hydrolyzed ophiopogon acid, butanetetracarboxylic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, diethylenetriaminepentamethylenephosphonic acid, and triethylenetetraaminehexa(methylphosphonic acid); The pyrrole is one or more of 2-(pyrrolidin-3-yl)ethane-1-ol hydrochloride, 1-(2-chlorobenzyl)-pyrrolidin-3-amine dihydrochloride, and 1-(4-chlorobenzyl)-pyrrolidin-3-amine dihydrochloride; The pyrazoles are 2-(4-bromo-1H-pyrazol-1-yl)acetamide and 2-(4-bromo-1H-pyrazol-1-yl)propionamide; The oxazole is one or more of 5-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole, 6-nitro-1,2-benzisoxazole-3-methanol, and 6-nitro-1,2-benzisoxazole-3-carboxylic acid; The thiazoles are one or more of 2-methyl-5-nitrothiazole, 2-methyl-5-nitrobenzothiazole, 2-methyl-5-phenyl-thiazole-4-carboxylic acid, and 4-methyl-5-nitrothiazole; The imidazole is 2-(difluoromethyl)-1-phenyl-4,5-dihydro-1H-imidazole; The pyridine is one or more of 2-(4-bromo-1H-pyrazol-1-yl)-5-fluoropyridine, 2-bromo-6-(1H-pyrazol-1-yl)pyridine, 2-(4-bromopyrazol-1-yl)pyridine, 2-((4-iodo-1H-pyrazol-1-yl)methyl)pyridine, 2-(4-bromo-3-methyl-5-(trifluoromethyl)pyrazol-1-yl)-6-chloropyridine, and 5-(chloromethyl)-2-(1H-pyrazol-1-yl)pyridine; The pyrimidines are one or more of 2-(4-bromo-1H-pyrazol-1-yl)pyrimidine, 2-(1H-pyrazol-1-yl)-5-(trifluoromethyl)pyrimidine, 2,4-dichloro-5-(1H-pyrazol-1-yl)pyrimidine, 2-(1H-pyrazol-1-yl)-5-(trifluoromethyl)pyrimidine, 4-(4-bromo-1H-pyrazol-1-yl)-6-chloropyrimidine, and 4-chloro-6-(1H-pyrazol-1-yl)pyrimidine; The azaindole is one or more of 4-bromo-2-iodo-N-toluenesulfonyl-7-azaindole, 4-bromo-1-toluenesulfonyl-7-azaindole, 2-difluoromethyl-1-benzenesulfonyl-7-azaindole, N-toluenesulfonyl-5-bromo-4,7-diazaindole, 1-benzenesulfonyl-4-chloro-2-iodo-7-azaindole, 2-iodo-1-benzenesulfonyl-7-azaindole, 2-methyl-1-(benzenesulfonyl)-7-azaindole, and 2-difluoromethyl-1-benzenesulfonyl-7-azaindole; The pyrazines are one or more of 2-(4-bromo-1H-pyrazol-1-yl)pyrazine, 2-(4-bromo-1h-pyrazol-1-yl)pyrazine, 3-(4-bromo-1H-pyrazol-1-yl)-6-chloropyrazine, and 3-chloro-6-(4-iodo-1H-pyrazol-1-yl)pyrazine.

2. A method for preparing the forward and reverse pulse electroplating nickel-tungsten alloy solution according to claim 1, characterized in that: The steps include: S1. Add nickel sulfate in small amounts and multiple times to a portion of pure water under heating and stirring conditions; S2. After all the nickel sulfate is dissolved, add organic acid in small amounts several times; S3, after the organic acid is completely dissolved, add the organic acid salt in small amounts and multiple times; S4. After all the organic acid salts are dissolved, the pH value of the solution is tested and the pH value is controlled within the range of 7.0-8.0; S5, add tungstate in small amounts and multiple times, and after the tungstate is completely dissolved, add nitrogen-containing heterocyclic compounds in small amounts and multiple times; S6. After all the nitrogen-containing heterocyclic compounds are dissolved, stir evenly and add some pure water to obtain the forward and reverse pulse electroplating nickel-tungsten alloy solution.

3. The preparation method according to claim 2, characterized in that: The heating temperature is 40-60° C. In S4, if the pH is lower than 7.0, an organic acid salt is added for adjustment, and if the pH is higher than 8.0, an organic acid is added for adjustment.

4. A method for forward and reverse pulse electroplating of nickel-tungsten alloy, characterized in that: The method uses the nickel-tungsten alloy solution of claim 1 or the nickel-tungsten alloy solution prepared by the preparation method of claim 2, and comprises the following steps: (1) placing a nickel-tungsten alloy electrolyte (10) into an electrolytic cell (50) and heating the electrolyte to 40-60° C.; (2) connecting the nickel plate (20) to the positive electrode of the pulse reverse power supply (100) through the positive electrode conductive connecting rod (21), and connecting the plated part (30) to the negative electrode of the pulse reverse power supply (100) through the negative electrode conductive connecting rod (31); (3) Electroplating with forward and reverse pulses: applying a forward pulse current I1, the forward pulse time t1, and then applying a reverse pulse current I2, the reverse pulse time t2, to complete a cycle of forward and reverse pulse electroplating; the ratio range of t1 to t2 is (10-100):1; the ratio range of I1 to I2 is 1:(2-5); (4) Repeat the forward and reverse pulse cycle of step (3) until the set electroplating time is completed.

5. The method for forward and reverse pulse electroplating of nickel-tungsten alloy according to claim 4, characterized in that: The current density of the forward pulse current in step (3) is in the range of 0.5-30.0A / dm 2 , the current density range of the reverse pulse current is 5.0-100.0A / dm 2 .

6. The method for forward and reverse pulse electroplating of nickel-tungsten alloy according to claim 4, characterized in that: The electroplating time is 1-100 minutes, and the thickness of the nickel-tungsten alloy coating obtained by electroplating is 0.5-100 μm.

7. The method for forward and reverse pulse electroplating of nickel-tungsten alloy according to claim 4, characterized in that: The method is used for barrel plating and rack plating.

8. The method for forward and reverse pulse electroplating of nickel-tungsten alloy according to claim 4, characterized in that: The method is used for a continuous production line of nickel-tungsten amorphous alloy materials.

9. The method for forward and reverse pulse electroplating of nickel-tungsten alloy according to claim 4, characterized in that: The method is used for the inner walls of through holes and blind holes.

10. The method for forward and reverse pulse electroplating of nickel-tungsten alloy according to claim 4, characterized in that: The method is used for surface electrolytic machining of the inner wall of tiny precision products.

11. A nickel-tungsten alloy coating obtained by electroplating according to any one of claims 4 to 10, characterized in that: The composition of the nickel-tungsten alloy coating is Ni 1-m W m , m is the percentage of tungsten atoms, and 43.43%≤m≤53.52%.

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