Electroplated diamond wire and method for manufacturing the same

Abstract

The application discloses a kind of electroplated diamond wire and its preparation method, the diamond wire is coated with diamond, nickel layer, nickel-iron alloy layer and nickel layer in turn from inside to outside;Its preparation method is by sequentially passing through alkali washing, pre-plating sand, activation treatment, plating nickel, drying and discharging to obtain the diamond wire;After pre-plating sand, plating nickel-iron alloy is carried out before activation treatment;In the activation treatment step, the composition of activation solution includes: ammonium hydrogen fluoride and hydrogen peroxide;Iron is used to replace part of nickel in coating, which can save nickel cost;The hardness of nickel-iron alloy is higher than that of pure nickel layer, which increases the wear resistance of diamond wire, and the toughness and ductility are improved;Activation treatment liquid makes nickel-iron alloy coating and substrate firmly combined;The leveling ability of plating solution is better than that of pure nickel;Divalent iron ion impurities are activated into coating, which makes the plating solution easier to manage.

Description

Technical Field

[0001] This invention relates to a diamond wire for cutting and its preparation method, and more particularly to an electroplated diamond wire and its preparation method. Background Technology

[0002] In the production of electroplated diamond wire, a layer of metallic nickel is typically plated onto the surface of the metal wire, with diamond abrasive coated onto the wire to increase the adhesion between the abrasive and the metal substrate. After the abrasive treatment, a second nickel plating is performed to improve the wear resistance and strength of the diamond wire. Such diamond wire is used for cutting hard materials, such as sapphire, magnetic materials, and silicon wafers. However, the current surge in the price of metallic nickel has increased the production cost of diamond wire. Therefore, reducing the nickel content of the plating while maintaining the performance of the diamond wire is an urgent problem to be solved. In existing processes, the pre-plated wire is activated before the second nickel plating, but the activation solution has a single component and is not suitable for other metal platings. Therefore, how to ensure the adhesion between plating layers after reducing the nickel content is another major problem that needs to be solved.

[0003] Patent application number 2018107530647 discloses a method to improve the adhesion of diamond wire coating. The method involves plating a nickel layer onto the diamond wire by passing it through the wire feeding end in sequence through alkaline washing, hot water washing, cold water washing, acid washing, cold water washing, and pre-plating reinforcement processes. Throughout the process, alkaline washing removes grease from the surface of the diamond wire, while acid washing removes oxides. After pre-plating and reinforcement to coat the steel wire with a nickel layer, a relatively strong coating can be obtained. However, the diamond wire prepared by this method is not further treated after pre-plating, so the adhesion between the coatings in the second electroplating is not improved. Therefore, it is necessary to improve the adhesion between the multiple coatings of the diamond wire. In the lecture on electroplating fundamentals in the September 2009 issue of "Electroplating and Finishing" (Vol. 28, No. 9), it was mentioned that without special pretreatment, the adhesion of difficult-to-plat metals is poor, and peeling and blistering will occur. The reason for this phenomenon is that metals such as nickel, nickel alloys, stainless steel, aluminum, and aluminum alloys are easily passivated. The more easily a metal is passivated, the worse the adhesion of the coating. It is very difficult to stack other metal layers on a nickel layer to ensure the adhesion between the coatings. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide an electroplated diamond wire with low cost and strong coating adhesion. Another purpose of this invention is to provide a method for preparing the above-mentioned electroplated diamond wire.

[0005] Technical solution: The present invention provides an electroplated diamond wire, wherein the diamond wire is coated from the inside out with diamond grit, a nickel layer, a nickel-iron alloy layer and a nickel layer in sequence.

[0006] The present invention discloses a method for preparing electroplated diamond wire, which involves sequentially subjecting a mother wire to alkaline washing, pre-plating with sand, activation treatment, nickel plating, and drying to obtain the diamond wire; nickel-iron alloy plating is performed after pre-plating with sand and before activation treatment; the activation treatment step includes ammonium hydrogen fluoride and hydrogen peroxide.

[0007] Furthermore, the concentration of ammonium bifluoride in the activation solution is 30-40 g / L, the concentration of hydrogen peroxide is 5-10 ml / L, and the hydrogen peroxide is a 35% hydrogen peroxide solution by mass.

[0008] Furthermore, in the nickel-iron alloy plating step, the Ni in the nickel-iron alloy plating solution... 2+ The concentration is 40-50 g / L, Fe 2+ The concentration is 4-8 g / L.

[0009] Furthermore, in the nickel-iron alloy plating step, the electroplating solution contains: nickel aminosulfonate at a concentration of 170-210 g / L and ferrous sulfate at a concentration of 20-40 g / L.

[0010] Furthermore, in the nickel-iron alloy plating step, the preparation temperature is 60-65℃, the pH is 3.0-4.0, and the cathode current density is 2-10 A / dm³. 2 The anode Ni:Fe area ratio is (6-8):1.

[0011] Furthermore, in the activation treatment step, the preparation temperature is 20-30℃.

[0012] Furthermore, the activation time in the activation treatment step is 1-2 minutes, until the ferrous ions are fully converted into ferric ions.

[0013] Furthermore, in the nickel plating step, the Ni in the nickel plating solution... 2+ The concentration is 70-110 g / L.

[0014] Mechanism of action: Hydrogen peroxide acidified with ammonium bifluoride has a significantly increased oxidizing power, with a standard electrode potential reaching 1.766V (the higher the electrode potential, the stronger the oxidizing power, and vice versa); the hydrogen peroxide oxidizes divalent ferrous ions, generating hydroxyl radicals: Fe 2+ +H₂O₂=Fe 3+ +OH-+HO·;The mixed use of ammonium bifluoride and hydrogen peroxide in Fe 2+The presence of ions generates hydroxyl radicals, HO· (hydroxyl radicals), which are highly reactive and can steal electrons from other substances, resulting in strong etching ability. This greatly promotes the corrosion of nickel-iron alloys, making the adhesion between coatings stronger. The etching effect and rate are not obvious when the hydrogen peroxide concentration is below 5 ml / L, and the corrosion efficiency is not significantly improved when the concentration is above 10 ml / L. Therefore, a hydrogen peroxide concentration of 5-10 ml / L is preferred.

[0015] In nickel-iron co-deposition, iron metal is preferentially deposited. When the nickel concentration in the plating bath remains constant, increasing the iron ion concentration linearly increases the iron content in the coating: for every 1 g / L increase in iron ions, the iron content in the coating increases by 10%. Therefore, the composition of the alloy layer is mainly controlled by adjusting the ratio of nickel ion to iron ion concentrations in the plating bath during preparation. Excessive iron content, due to its lower corrosion resistance compared to nickel, negatively impacts the corrosion resistance of the diamond wire. Therefore, it is necessary to control the iron content in the nickel-iron alloy, and the Ni:Fe anode area ratio is adjusted based on the nickel-iron ion content in the plating bath to ensure that the final coating contains approximately 50%-60% iron. Within this range, the mechanical and corrosion resistance properties of the diamond wire are stable, and the cost is relatively low.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. Iron is used to replace part of the nickel in the coating, which can save nickel costs; 2. The nickel-iron alloy has a higher hardness than the pure nickel layer, which increases the wear resistance of the diamond wire and improves its toughness and ductility; 3. The activation treatment solution makes the nickel-iron alloy coating firmly bonded to the substrate; the leveling ability of the plating solution is better than that of pure nickel; 4. The divalent iron ion impurities are activated into the coating, making the plating solution easier to manage. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the preparation process of the present invention;

[0018] Figure 2 This is a scanning electron microscope image of diamond wire in Embodiment 1 of the present invention;

[0019] Figure 3 This is a scanning electron microscope image of diamond wire in Embodiment 2 of the present invention;

[0020] Figure 4 This is a scanning electron microscope image of diamond wire in Embodiment 3 of the present invention;

[0021] Figure 5 This is a scanning electron microscope image of diamond wire in Comparative Example 1 of the present invention;

[0022] Figure 6 This is a scanning electron microscope image of diamond wire, which is a comparative example 2 of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0024] Example 1, the preparation process is as follows Figure 1 As shown, the specific preparation steps are as follows:

[0025] (1) Alkali washing

[0026] The busbar is alkali-washed in an alkaline solution for 5 minutes at a temperature controlled at 50°C. The alkaline solution consists of sodium hydroxide at a concentration of 50 g / L, sodium carbonate at a concentration of 40 g / L, and sodium metasilicate at a concentration of 15 g / L. After alkali washing, the busbar is rinsed with three deionized water cycles.

[0027] (2) Pre-plating sandblasting

[0028] After alkaline washing, the busbar is pre-plated with sandblasting solution. The solution consists of 400 g / L nickel sulfamate, 35 g / L boric acid, and 10 g / L nickel chloride, with a pH of 3.5-4.5. The plating temperature is 55℃, and the cathode current density is 5 A / dm³. 2 .

[0029] (3) Nickel-iron alloy

[0030] The busbars treated in the above steps are then subjected to nickel-iron alloy plating. The plating solution is prepared as follows: 190 g / L nickel sulfamate, 25 g / L sodium chloride, 40 g / L boric acid, 30 g / L ferrous sulfate, 20 g / L citric acid, 3 g / L saccharin, pH 3.5, and cathode current density of 5 A / dm³. 2 The anode Ni:Fe area ratio is 6:1, the electroplating time is 3 minutes, and the coating thickness is 4 micrometers; after plating the nickel-iron alloy, it undergoes 3 deionized water washes.

[0031] (4) Activation treatment

[0032] First, prepare an activation treatment solution containing 30 g / L ammonium hydrogen fluoride and 5 ml / L hydrogen peroxide. The hydrogen peroxide is a 35% industrial hydrogen peroxide solution. Place the above-mentioned busbar in the activation treatment solution at 25°C for 2 minutes. After the activation treatment is completed, perform three deionized water washes.

[0033] (5) Nickel plating

[0034] First, prepare the nickel plating solution, comprising 300 g / L nickel sulfamate, 25 g / L boric acid, and 15 g / L nickel chloride, with a pH of 3.5. Control the plating temperature at 62℃ and the cathode current density at 20 A / dm³. 2 The electroplating time is 0.5 min and the thickness is 1.5 micrometers; after the nickel plating layer is completed, it is washed with deionized water twice.

[0035] (6) The finished diamond wire was obtained after drying in an oven; the electron microscope image after bending experiment is shown below. Figure 2 It can be seen that the coating layers are firmly bonded after the diamond wire is bent, and there are no coating bubbles or peeling.

[0036] Example 2 follows the same implementation steps as Example 1, with the following differences:

[0037] In step (3), the concentration conditions of the prepared solution are as follows: 190 g / L nickel sulfamate, 27 g / L sodium chloride, 45 g / L boric acid, 25 g / L ferrous sulfate, 25 g / L citric acid, 4 g / L saccharin, pH value 3.5, and cathode current density 6 A / dm³. 2 The anode Ni:Fe area ratio is 7:1;

[0038] In step (4), the activation solution was 35 g / L ammonium bifluoride and 7 ml / L hydrogen peroxide. The above-mentioned wire was placed in the activation solution at 30°C for 2 min. The electron microscope image of the final diamond wire after bending experiment is shown below. Figure 3 It can be seen that the bonding force between the coatings remains strong after bending, and there are no bubbles or peeling phenomena.

[0039] Example 3 follows the same implementation steps as Example 1, with the following differences:

[0040] In step (3), the concentration conditions of the prepared solution are as follows: 210 g / L nickel sulfamate, 30 g / L sodium chloride, 50 g / L boric acid, 40 g / L ferrous sulfate, 30 g / L citric acid, 5 g / L saccharin, pH value of 3.5, and cathode current density of 2 A / dm³. 2 The anode Ni:Fe area ratio is 6:1;

[0041] In step (4), the activation solution was 40 g / L ammonium bifluoride and 10 ml / L hydrogen peroxide. The above-mentioned wire was placed in the activation solution at 30°C for 1 min. The electron microscope image of the final diamond wire after bending experiment is shown below. Figure 4 It can be seen that the bonding force between the coatings remains strong after bending, and there are no bubbles or peeling phenomena.

[0042] Comparative Example 1

[0043] The basic steps are the same as in Example 1, the difference being that a conventional activating solution is used for the activation treatment, and only ammonium bifluoride is added in step (4) to finally prepare diamond wire; the diamond wire prepared has poor adhesion between the coating layers and is easy to peel off between the coating layers; its electron microscope image after bending is as follows. Figure 5 As shown, the coating in the middle has peeled off, and wrinkles have formed at the bend.

[0044] Comparative Example 2

[0045] The basic steps are the same as in Example 1, except that only hydrogen peroxide is added in step (4) to finally prepare diamond wire; the bonding force between the coatings of the prepared diamond wire is poor, and the coatings are easy to peel off. The electron microscope image after bending is as follows. Figure 6 As shown, it can be seen that obvious peeling occurs at the bend and the middle part, exposing the smooth busbar.

[0046] from Figures 2-4 It can be seen that the diamond wire pre-plated with abrasive first undergoes a nickel-iron alloy plating layer, followed by activation treatment, and then a second nickel plating to form a nickel layer. The resulting diamond wire shows no obvious breakage between plating layers during bending tests. However, in the case of a conventional activation solution used for activation treatment, followed by a second plating, the adhesion between the resulting nickel layer and the nickel-iron alloy layer is poor. Figure 5 It can be seen that cracking and peeling occur; similarly, if only hydrogen peroxide is added for activation treatment, such as Figure 6 As shown, the final diamond wire also exhibits breakage and peeling when bent.

Claims

1. A preparation method of electroplated diamond wire, by sequentially passing a mother wire through alkali washing, pre-plating sand, activation treatment, nickel plating, and drying to obtain the diamond wire; characterized in that, Nickel-iron alloy plating is carried out after pre-plating sand and before activation treatment; the activation liquid composition comprises ammonium hydrogen fluoride and hydrogen peroxide in the activation treatment step; The ammonium hydrogen fluoride concentration in the activation liquid is 30-40 g / L, and the hydrogen peroxide concentration is 5-10 ml / L, and the hydrogen peroxide is a 35% mass concentration hydrogen peroxide solution; The iron content in the nickel-iron alloy is 50%-60%.

2. The method of claim 1, wherein the gold-plated diamond wire is prepared by the steps of: In the nickel-iron alloy plating step, the electroplating liquid composition comprises nickel sulfamate and ferrous sulfate; and the nickel sulfamate concentration in the electroplating liquid is 170-210 g / L, and the ferrous sulfate concentration in the electroplating liquid is 20-40 g / L. ​ 3. The method of claim 1 or 2, wherein the gold-plated diamond wire is prepared by the steps of: The temperature of the step of plating the nickel-iron alloy is 60-65°C, the pH is 3.0-4.0, the cathode current density is 2-10 A / dm 2 , and the anode Ni:Fe area ratio is (6-8):

1. ​ 4. The method of claim 1, wherein the gold-plated diamond wire is prepared by the steps of: The preparation temperature in the activation treatment step is 20-30°C. ​ 5. The method of claim 3, wherein the gold-plated diamond wire is prepared by the steps of: The activation time in the activation treatment step is 1-2 min. ​ 6. The method of claim 1, wherein the gold electroplated diamond wire is prepared by the steps of: In the nickel plating step, the nickel in the nickel plating solution... 2+ The concentration is 70-110 g / L.

7. The electroplated diamond wire prepared by the method according to any one of claims 1-6.

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