A method of electrochemically plating a superhard abrasive with a brittle nickel

Abstract

The present application belongs to the technical field of superhard abrasive surface processing, and particularly relates to a method for electrochemically plating brittle nickel on superhard abrasive. The present application utilizes the different solubilities of sodium carbonate and sodium bicarbonate and the different pH values in aqueous solution, adjusts the pH values of hydrochloric acid and plating solution and other related parameters, forms an online foaming process, and electrochemically plates honeycomb-shaped brittle nickel on the surface of superhard abrasive. The superhard material surface nickel-plated product prepared by the method of the present application has a plating layer with both toughness and brittleness, and the protective film of pure electroplated nickel is sufficient to protect the superhard material from damage during tool processing, has good performance, and the foaming agent solution used in the nickel plating process can be used as an electrolyte in the plating solution. The entire process is safe and environmentally friendly, in line with existing environmental protection concepts. The nickel-plated diamond of the present application can be applied to the production of elastic modules, ceramic grinding wheels, wire saws and other diamond tools, which can significantly improve the grinding performance and service life of the tools.

Description

Technical Field

[0001] This invention belongs to the field of surface processing technology for superhard abrasives, and specifically relates to a method for electrochemically plating brittle nickel onto superhard abrasives. Background Technology

[0002] Metallization of superhard abrasive surfaces is widely used in sawing, drilling, and other fields due to its excellent performance. Traditional methods for metallizing superhard materials include vapor deposition, electroplating, and electroless plating. In addition, in recent years, magnetron sputtering has also been applied as a novel coating technology for metallizing superhard materials.

[0003] In traditional metallization processes for superhard materials, nickel plating is a common method. The traditional electroplating process typically involves first vapor-depositing a layer of titanium onto the superhard material surface to make it conductive. Then, after a series of sensitization and activation steps, a nickel-phosphorus alloy layer is deposited on the surface using chemical deposition. The material is then placed on a barrel plating machine for further weight gain. Finally, after washing, drying, and sieving, qualified products are produced according to standards. Traditional electroplating of superhard materials using nickel is a low-temperature process, which is relatively less environmentally damaging and uses recyclable or easily recoverable materials. Furthermore, the dense plating layer minimizes the risk of damage to the superhard material during processing. However, its high density results in tools that are slow to sharpen, sticky, and have poor sharpness.

[0004] Traditional electroless nickel plating typically involves pre-treating superhard materials, placing them in a reaction vessel, adding various chemicals according to a specific process, controlling the pH within a certain range, and undergoing a series of chemical reactions to obtain a semi-finished product. The main component of the plating layer is a nickel-phosphorus alloy. After washing, drying, and sieving, a qualified product is produced according to standards. Traditional electroless nickel plating offers a good balance of brittleness and toughness; however, its density is relatively poor, providing less protection for superhard materials during tooling compared to electroplating. Furthermore, the electroless nickel plating reaction process requires precise control; slight errors can easily result in substandard products. Additionally, the chemicals used in electroless nickel plating are all single-use, and the phosphorus-containing wastewater poses a significant environmental hazard, contradicting current environmental protection principles.

[0005] Therefore, it is necessary to find new coating processes for superhard materials in order to improve the brittleness, toughness, strength and other properties of the coating layer while ensuring its density. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing nickel plating processes by providing a green and environmentally friendly method for electrochemical plating of brittle nickel with superhard abrasives. This method ensures that the prepared nickel plating layer has good density while also improving the brittleness, toughness, strength, and other properties of the plating layer.

[0007] The present invention also provides a nickel-plated superhard material prepared by the method described above.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for electrochemically plating brittle nickel onto superhard abrasives includes the following steps: (1) Preparation of foaming agent solution: Dissolve sodium carbonate in water to prepare foaming agent solution (specifically, place sodium carbonate in deionized water and stir to dissolve it under water bath conditions of 20~25℃, which is the foaming agent solution). (2) Vacuum pre-plating of chromium: Before electrochemical nickel plating, a conductive chromium layer is first plated on the surface of the superhard abrasive. (3) Electrochemical nickel plating: After pre-plating with chromium, the superhard material is placed on a barrel plating machine for electrochemical nickel plating. The specific steps are as follows: Wash the superhard abrasive with deionized water at 30-50℃ 4-6 times, then dry it in an oven and let it cool to room temperature. Add the dried material to the foaming agent solution and stir. After the superhard abrasive and the foaming agent solution are evenly stirred, start adding hydrochloric acid dropwise until tiny bubbles are produced. Remove the superhard abrasive from the foaming agent solution and add it to the barrel plating tank as soon as possible. Add the electroplating solution, adjust the pH to between 3.8 and 4.1, adjust the current to 20-30A and the voltage to 10-15V, and perform electrochemical nickel plating. At this time, the anode and cathode are placed in the electroplating solution together; the anode is a nickel plate and the cathode is a copper strip. When the pH value of the solution exceeds 5.0, turn off the electroplating power supply, remove the superhard abrasive, and that is one nickel plating process. Repeat the aforementioned cleaning, drying, bubbling, and electrochemical plating processes several times to obtain a honeycomb-shaped brittle nickel plating layer, which is the final nickel-plated superhard abrasive.

[0009] Specifically, in step (1), the amount of sodium carbonate used is 60~80g, and the amount of deionized water used is 300~400mL.

[0010] Specifically, the superhard abrasive in step (2) is diamond of the ZND2010 series with a particle size of 200 / 230.

[0011] Specifically, in step (2), chromium plating on the surface of the superhard abrasive is performed using a vacuum micro-evaporation plating process, which allows metallic chromium to form chromium carbide chemical bonds with diamond, facilitating the subsequent formation of metallic bonds between chromium and nickel layers. This increases the conductivity of diamond while simultaneously enhancing the strength of the brittle nickel plating layer, thereby increasing the holding force of the diamond tool working layer on it. The chromium plating temperature is 850~900℃, and the plating time is 8~10 hours. When the vacuum degree reaches 6.5*10 -3When PA starts operating the process, the weight ratio of chromium powder to superhard abrasive is (0.5~0.9):1.

[0012] Specifically, in step (3), the amount of nickel used is designed and calculated before nickel plating. The nickel plating layer to be added is N50, where N50 means that the weight of the nickel plating layer / [the weight of the nickel plating layer + the weight of the diamond] = 50%. According to the calculation, the amount of electricity required when the weight of N50 is to be added is 700~750A∙h. The designed current is 20~30A and the voltage is 10~15V. When electrochemically plating nickel, a barrel plating drum is used. The rotation speed of the barrel plating drum is 20~40r / min. The anode used is a nickel plate with a purity ≥99% and a length * width * thickness = (350~400) * (60~80) * (8~12) mm. The cathode is a copper strip with a purity ≥99% and a length * width * thickness = (550~600) * (8~12) * (3~6) mm.

[0013] Specifically, in step (3), the ratio of the dried superhard abrasive to the foaming agent solution is: 300~4000 carats of superhard abrasive are added for every 2.5 liters of foaming agent solution.

[0014] Specifically, in step (3), after the dried superhard abrasive is mixed with the foaming agent solution, it is stirred using an automatic stirrer at a speed of 20~40 r / min.

[0015] Specifically, in step (3), hydrochloric acid is added drop by drop. When tiny bubbles appear, the amount of hydrochloric acid added is about 500 ml; the concentration of the added hydrochloric acid is 6-8%.

[0016] Specifically, in step (3), the amount of electroplating solution used is 5-6 liters; the components of the electroplating solution are: nickel sulfate 80-130g / L, sodium chloride 100-180g / L, boric acid 20-40g / L, preferably, the weight ratio of the three is 3:3.5:1; the weight ratio of electroplating solution to superhard abrasive is 1-1.5 liters / kcal.

[0017] Specifically, in step (3), when electrochemically plating nickel, the rotation speed of the barrel is adjusted to 20~40 r / min.

[0018] Furthermore, the present invention also provides a nickel-plated superhard abrasive prepared by the above method, specifically nickel-plated diamond.

[0019] Furthermore, based on a general inventive concept, the present invention also provides the application of the nickel-plated superhard abrasive in the manufacture of diamond tools such as elastic modules, ceramic grinding wheels, and wire saws.

[0020] Compared with the prior art, the beneficial effects of the present invention are: The method for electrochemically plating brittle nickel with superhard abrasives of the present invention employs an acidic electrochemical plating process, which causes the nickel to form a honeycomb structure during the electroplating process, possessing both brittleness and toughness. During the electroplating process, hydrochloric acid is added to the remaining sodium bicarbonate to replenish the electrolyte of the plating solution.

[0021] The nickel-plated products on the surface of superhard materials prepared by the method of the present invention have a coating that balances toughness and brittleness. The protective film of pure electroplated nickel is sufficient to protect the superhard materials from damage during tooling and has good performance. The foaming agent solution used in the nickel plating process can be used as an electrolyte in the plating solution. The entire process is safe and environmentally friendly, in line with the existing environmental protection concept. Attached Figure Description

[0022] Figure 1 This is a photograph of the actual diamond after nickel plating in Example 1. Detailed Implementation

[0023] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0025] The chemicals used in the following examples are of analytical grade.

[0026] Example 1 A method for electrochemically plating brittle nickel onto superhard abrasives utilizes the different solubilities of sodium carbonate and sodium bicarbonate (sodium bicarbonate is obtained by reacting sodium carbonate with hydrochloric acid to form sodium bicarbonate, which has a lower solubility than sodium carbonate and precipitates from the solution), as well as their different pH values ​​in aqueous solutions. By adjusting the pH of the hydrochloric acid and the plating solution, along with other relevant parameters, an online foaming process is formed to electrochemically plate a honeycomb-shaped brittle nickel onto the surface of the superhard abrasive. In this embodiment, the abrasive is 200 / 230 grit diamond from the ZND2010 series from Zhongnan. The specific steps are as follows: (1) Preparation of foaming agent solution: Place the water bath in the exhaust fan and set the water bath temperature to 20°C; place a 5L beaker in the water bath and add 400ml of deionized water; Weigh 60g of sodium carbonate and add it to a beaker. Stir continuously with an automatic stirrer until the sodium carbonate is completely dissolved. Then add water to make the total volume of the solution 500ml. Store the solution in a water bath. This is the foaming agent solution. (2) Vacuum pre-plating of chromium: Before electrochemical nickel plating, a conductive chromium layer is first plated on the surface of the superhard abrasive (diamond of grade ZND2010 from Zhongnan with a particle size of 200 / 230). Vacuum micro-evaporation plating is used for chromium plating to form chromium carbide chemical bonds between the metallic chromium and the diamond, so as to facilitate the formation of metallic bonds between the chromium and nickel layers in the subsequent process. This increases the conductivity of the diamond and improves the strength of the brittle nickel plating layer, thereby increasing the holding force of the diamond tool working layer on it. The chromium plating temperature is 900℃ and the chromium plating time is 8 hours. When the vacuum degree reaches 6.5*10 -3 PA started the plating process with a weight ratio of chromium powder to superhard abrasive of 0.7:1. (3) Electrochemical nickel plating: After pre-plating chromium, the superhard material is placed on a barrel plating equipment for electrochemical nickel plating. Before electroplating, the amount of material to be used is designed and calculated. The nickel plating layer to be added is N50, where N50 means that the weight of the plating layer (nickel) / [the weight of the plating layer (nickel) + the weight of diamond] = 50%. According to the calculation, when the weight is to be added by N50, the amount of electricity required is 700~750A∙h. The current to be used is 20~30A and the voltage is 10~15V. When electrochemically plating nickel, a barrel plating cylinder is used. The rotation speed of the barrel plating cylinder is 20~40r / min. The anode used is a nickel plate with a purity ≥99% and a length * width * thickness = (350~400) * (60~80) * (8~12) mm. The cathode is a copper strip with a purity ≥99% and a length * width * thickness = (550~600) * (8~12) * (3~6) mm. The specific steps are as follows: Wash the superhard abrasive with 50℃ deionized water 4-6 times, then dry it in an oven and let it cool to room temperature. Add the dried material to the foaming agent solution at a ratio of 2.5 liters of foaming agent solution to 4000 carats of superhard abrasive. Use an automatic stirrer with the speed adjusted to 30 rpm to stir. After the superhard abrasive and foaming agent solution are evenly mixed, start adding hydrochloric acid (8% concentration) dropwise with a pipette until tiny bubbles are produced. At this point, the amount of hydrochloric acid added is about 500 ml. Remove the superhard abrasive from the foaming agent solution and add it to the barrel plating tank as soon as possible. Add 6 liters of conventional electroplating solution, which consists of nickel sulfate, sodium chloride, and boric acid in a weight ratio of 3:3.5:1 (specific dosages: 120 g / L nickel sulfate, 140 g / L sodium chloride, and 40 g / L boric acid). The weight ratio of the electroplating solution to the superhard abrasive is 1.5 liters / kcal. Adjust the pH to between 3.8 and 4.1, adjust the current to 20 A and the voltage to 10 V, and adjust the barrel speed to 20 r / min to perform electrochemical nickel plating. At this time, immerse both the anode and cathode in the electroplating solution. When the solution pH exceeds 5.0, turn off the electroplating power supply and remove the superhard abrasive. This completes one nickel plating process. Repeat the aforementioned cleaning, drying, bubbling, and electrochemical plating processes several times until the nickel plating layer reaches the preset weight. This yields a honeycomb-like brittle nickel plating layer, which is the final nickel-plated superhard abrasive. The nickel-plated diamond obtained in Example 1 is as follows: Figure 1 As shown.

[0027] Testing revealed that the nickel-plated superhard abrasive prepared in Example 1 had a nickel plating layer weight gain of N50~N60; the nickel-plated diamond, according to the bulk density test, had a maximum value of 2.2 g / mL for the finer particles in a 200 / 230 ratio (bulk density measures the weight of particles within a certain volume, primarily determining the length of the nickel spikes; longer spikes provide better holding force from the substrate, and vice versa); and the plating layer's impact breakage rate percentage was ≥30% under 1500 steel ball impacts (the nickel-plated superhard abrasive is intended for use in subsequent processing as a grinding tool, indicating that it is easy to sharpen and has high cutting efficiency).

[0028] Example 2 Example 2 provides a method for electrochemical plating of brittle nickel with superhard abrasive. The difference between Example 2 and Example 1 is that the amount of sodium carbonate used in step (1) is 70g; and in step (3), after adding conventional electroplating solution, the current is adjusted to 24A and the voltage is adjusted to 12V.

[0029] Testing revealed that the nickel-plated superhard abrasive prepared in Example 2 had a nickel plating layer weight gain of N50~N60. The nickel-plated diamond, tested for bulk density, showed a maximum value of 2.2 g / mL for the finer particles (bulk density measures the weight of particles within a given volume, primarily determining the length of the nickel spikes; longer spikes provide better holding force from the substrate, and vice versa). Using the impact breakage rate percentage as an indicator, the breakage rate was ≥40% after 1500 steel ball impacts (this nickel-plated superhard abrasive is intended for use in subsequent grinding tools, indicating that it is easy to sharpen and has high cutting efficiency).

[0030] Example 3 Example 3 provides a method for electrochemical plating of brittle nickel with superhard abrasive. The difference between Example 2 and Example 1 is that the amount of sodium carbonate used in step (1) is 80g; and in step (3), after adding conventional electroplating solution, the current is adjusted to 26A and the voltage is adjusted to 13V.

[0031] Testing revealed that the nickel-plated superhard abrasive prepared in Example 2 had a nickel plating layer weight gain of N50~N60. The nickel-plated diamond, tested for bulk density, showed a maximum value of 2.2 g / mL for the finer particles in a 200 / 230 ratio (bulk density measures the weight of particles within a given volume, primarily determining the length of the nickel spikes; longer spikes provide better holding force from the substrate, and vice versa). Using the impact breakage rate percentage as an indicator, the breakage rate was ≥50% after 1500 steel ball impacts (this nickel-plated superhard abrasive is intended for use in subsequent grinding tools, indicating that it is easy to sharpen and has high cutting efficiency).

[0032] As can be seen from Examples 1-3, the method for plating brittle nickel described in this invention can achieve the effect of controlling the degree of sharpness and cutting efficiency according to different working conditions when used for cutting.

[0033] Application Examples The nickel-plated diamonds prepared in Examples 1, 2, and 3 were used to manufacture diamond tools such as elastic modules, ceramic grinding wheels, and wire saws. Specific examples are as follows: When the nickel-plated diamond prepared in Examples 1, 2, and 3 is applied to the preparation of elastic modules, the diamond concentration is reduced by 20% compared to before application (generally, a lower diamond concentration means fewer diamond particles per unit working layer area, resulting in greater force on each abrasive grain, greater cutting pressure, and deeper cutting depth per abrasive grain), and the number of square meters of ceramics that can be ground using the elastic modules (i.e., how many square meters of product are processed) is increased by 260%.

[0034] When the nickel-plated diamond prepared in Examples 1, 2, and 3 is applied to the preparation of ceramic grinding wheels, the grinding wheel sharpening time is reduced by 90% and the service life is increased by 2 times.

[0035] When the nickel-plated diamond prepared in Examples 1, 2, and 3 is applied to the manufacture of wire saws, the wire breakage rate of the wire saw can be reduced, the cutting efficiency can be increased by 3 times, and the precision of the finished product can also be improved by one level.

[0036] The results above show that applying the nickel-plated diamond of the present invention to diamond tools such as elastic modules, ceramic grinding wheels, and wire saws can significantly improve the grinding performance and service life of these tools, and has good application prospects.

[0037] The above embodiments are illustrative examples of the implementation of the present invention. The implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A method for electrochemically plating brittle nickel onto superhard abrasives, characterized in that, Includes the following steps; (1) Preparation of foaming agent solution: Dissolve sodium carbonate in water to prepare foaming agent solution; (2) Vacuum pre-plating of chromium: Before electrochemical nickel plating, a conductive chromium layer is first plated on the surface of the superhard abrasive. (3) Electrochemical nickel plating: After pre-plating with chromium, the superhard material is then electrochemically plated with nickel. The specific steps are as follows: The superhard abrasive is cleaned with water at 30-50°C, then dried to room temperature and added to a foaming agent solution. After the superhard abrasive and foaming agent solution are stirred evenly, hydrochloric acid is added drop by drop until bubbles are produced. The superhard abrasive is removed from the foaming agent solution and added to the barrel plating tank. Electroplating solution is added, and the pH is adjusted to between 3.8 and 4.

1. The current is adjusted to 20-30A and the voltage to 10-15V for electrochemical nickel plating. At this time, the anode and cathode are placed in the electroplating solution together. The anode is a nickel plate and the cathode is a copper strip. When the pH value of the solution exceeds 5.0, the electroplating is stopped, and the superhard abrasive is removed. This completes one nickel plating process. Repeat the aforementioned cleaning, drying, bubbling, and electrochemical plating processes several times to obtain a honeycomb-shaped brittle nickel plating layer, which is the final nickel-plated superhard abrasive.

2. The method as described in claim 1, characterized in that, In step (1), the amount of sodium carbonate used is 60~80g and the amount of deionized water used is 300~400mL.

3. The method as described in claim 1, characterized in that, The superhard abrasive in step (2) is diamond with a particle size of 200 / 230.

4. The method as described in claim 1, characterized in that, In step (2), chromium plating on the surface of the superhard abrasive is performed using a vacuum micro-evaporation plating process; the plating temperature is 850~900℃, the plating time is 8~10 hours, and the vacuum degree reaches 6.5*10 -3 When PA starts operating the process, the weight ratio of chromium powder to superhard abrasive is (0.5~0.9):

1.

5. The method as described in claim 1, characterized in that, In step (3), the ratio of dried superhard abrasive to foaming agent solution is: 300-4000 carats of superhard abrasive are added for every 2.5 liters of foaming agent solution.

6. The method as described in claim 1, characterized in that, In step (3), the amount of electroplating solution used is 5-6 liters; the composition of the electroplating solution is: nickel sulfate 80-130 g / L, sodium chloride 100-180 g / L, boric acid 20-40 g / L; the weight ratio of electroplating solution to superhard abrasive is 1-1.5 liters / kcal.

7. Nickel-plated superhard abrasive prepared by any one of the methods described in claims 1-6.

8. The application of the nickel-plated superhard abrasive of claim 7 in the manufacture of elastic modules, ceramic grinding wheels or wire saws.

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