Electrolytic stripping solution for stripping nitride coating, electrolytic stripping method and application

Abstract

The application relates to an electrolytic stripping solution for stripping nitride coating, an electrolytic stripping method and application, wherein the electrolytic stripping solution comprises water-soluble hydroxide, a complexing agent, nanometer carbon balls, an anionic surfactant and water. The electrolytic stripping solution can be used for electrochemical stripping, can effectively improve the stripping efficiency, can make the current as evenly distributed as possible, can effectively reduce the defect generation rate of the workpiece surface, and can obtain a high-quality surface.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrolytic stripping solution for stripping nitride coating, an electrolytic stripping method and application, and belongs to the field of surface treatment. BACKGROUND

[0002] Coating a layer of nitride coating on the surface of metal cutting tools can prolong the service life. After a period of use, the cutting edge and the surface coating of the cutting edge will be worn out, and the tool needs to be re-coated after grinding and stripping.

[0003] In the case of as little damage to the substrate body as possible, how to efficiently and stably strip the hard film from the substrate is a problem that must be faced in industrial mass production.

[0004] The existing large-scale stripping methods include chemical stripping and electrochemical stripping.

[0005] Chemical stripping has good consistency in removing the coating on the shaped surface of the tool, and the stripping strength is easy to control. Chemical stripping refers to the dissolution reaction of the tool coating by using a specific chemical solution. Since pure immersion is used, the whole stripping process takes a long time, and has high requirements for reaction temperature.

[0006] Electrochemical stripping: by applying a suitable polarization potential in the electrolytic circuit, the coating metal elements and the substrate have different electrochemical characteristics, and the coating on the surface of the substrate is selectively dissolved (the coating is in the active dissolution zone, and the substrate is in the stable passivation zone), which is the main technical feature of electrochemical stripping.

[0007] In the previous electrolytic stripping formula, in order to ensure the stripping efficiency, a large proportion of electrolyte is often added to the formula, and a higher electrolytic voltage and a larger current density are applied. In this way, while the film is stripped, the local excessive current produces irregularly distributed large-size depressions on the substrate surface, causing damage to the substrate.

[0008] The multi-layer structure design of the nano multi-layer nitride hard film is formed by the alternation of multiple different nitride monolayers, which makes it more likely to cause substrate damage or low stripping efficiency due to unreasonable stripping process parameters.

[0009] Chinese invention patent application CN201010150010 discloses a stripping solution containing acid, accelerator, promoter and corrosion inhibitor, which is stripped by chemical method. The workpiece and the stripping solution are contacted by spraying and soaking to dissolve the titanium nitride film. This method takes 0.5-2h, which is time-consuming and inefficient.

[0010] Chinese patent application CN102234835A discloses an electrochemical stripping method for stripping titanium carbide coating by using two different stripping solutions with different formulations, which controls the electrolysis intensity and realizes the lossless removal of the substrate coating by preparing the stripping solutions with different concentrations of hydroxide, the first stripping solution containing 5-100 g / L of sodium hydroxide and the second stripping solution containing 50-300 g / L of sodium hydroxide. However, the method needs two times of electrolysis, which is time-consuming. SUMMARY

[0011] In view of the above problems, one of the purposes of the present application is to provide an electrolytic stripping solution for stripping nitride coating, which can efficiently strip the nitride coating and avoid the generation of surface defects of the substrate as much as possible. Another purpose of the present application is to provide an electrolytic stripping method for stripping nitride coating. The third purpose of the present application is to provide the application of nanometer carbon spheres in the electrochemical stripping method for stripping nitride coating, which disperses the nanometer carbon spheres in the electrolyte.

[0012] To solve the above technical problems, the technical scheme of the present application is as follows:

[0013] The electrolytic stripping solution for stripping nitride coating comprises water-soluble hydroxide, complexing agent, nanometer carbon spheres (CNBS), anionic surfactant and water.

[0014] The present application introduces nanometer carbon spheres into the electrolytic stripping solution and adds anionic surfactant, which can uniformly and stably disperse the nanometer carbon spheres in the electrolytic stripping solution. Specifically, under the action of the anionic surfactant, a polar adsorption film completely wrapping the spheres is formed on the surface of the CNBS, which increases the polarity of the CNBS surface, and the nanometer carbon spheres are far away from each other due to the electrostatic repulsion, forming a uniform and stable suspension system. In this way, on the one hand, the conductivity of the electrolytic stripping solution can be effectively improved, and the resistance of the electrolytic stripping solution is reduced, so that the current distribution in the electrolytic stripping solution is more uniform during the electrolytic stripping process, and the CNBS with negative charge can be enriched in the anode reaction zone under the driving of the electric field; on the other hand, during the electrolytic stripping process, the hard metal cations peeled off from the surface of the workpiece will react with the anions in the electrolytic stripping solution to form flocculent complexes, which affects the electrolysis efficiency of the region. The electrolytic stripping solution of the present application contains CNBS, which can continuously flush the surface of the workpiece with nitride coating to be stripped at the anode position and carry away the flocculent complexes generated by the reaction, so that the diffusion reaction between the surface of the nitride coating and the electrolytic stripping solution can continue stably until the electrochemical stripping of the nitride coating is completed. The above two aspects not only improve the stripping efficiency, but also make the current as uniform as possible, effectively reducing the defect generation rate of the surface of the workpiece and obtaining a high-quality surface.

[0015] Further, the concentration of the nanocarbon spheres is 1-25 g / L, preferably 2-15 g / L, and more preferably 2-8 g / L.

[0016] Further, the concentration of the anionic surfactant is 1-50 g / L, preferably 4-30 g / L, and more preferably 4-16 g / L.

[0017] Further, the particle size of the nanocarbon spheres is 20-800 nm, preferably 50-700 nm, and more preferably 100-600 nm.

[0018] Further, the nanocarbon spheres are modified nanocarbon spheres, and the surface of the modified nanocarbon spheres contains hydroxyl functional groups, preferably the content of the hydroxyl functional groups is ≥ 4 wt%.

[0019] Further, the anionic surfactant is sodium dodecyl benzene sulfonate, sodium hexadecyl sulfonate, or fatty alcohol polyether-n carboxylate, preferably sodium dodecyl benzene sulfonate.

[0020] Further, the concentration of the water-soluble hydroxide is 10-200 g / L, preferably 50-200 g / L.

[0021] Further, the concentration of the complexing agent is 10-100 g / L, preferably 50-80 g / L.

[0022] Preferably, the water-soluble hydroxide is a water-soluble alkali metal hydroxide, and the water-soluble alkali metal hydroxide includes one or more of sodium hydroxide and potassium hydroxide.

[0023] Preferably, the complexing agent includes one or more of monoethanolamine, sodium ethylenediaminetetraacetate (ETDDA-4Na), and tartaric acid, and more preferably the complexing agent is one of sodium ethylenediaminetetraacetate and tartaric acid.

[0024] Optionally, the nitride coating is a nitride coating on a tool (such as a milling cutter, a band saw blade, etc.). Optionally, the base body of the tool is one or more of high-speed steel, stainless steel, and alloy steel.

[0025] Optionally, the coating is a single-layer nitride coating or a nano-multilayer nitride coating.

[0026] Optionally, the preparation method of the electrolytic stripping solution includes the following steps:

[0027] (1) According to the need, a certain amount of deionized water is weighed, and then the required CNBS and anionic surfactant are sequentially added to the deionized water, the heating temperature is 25-45℃, the ultrasonic vibration time is 15-45 minutes, and manual auxiliary stirring is performed 2-5 times, each time for 0.5-3 minutes, to obtain a uniformly and stably dispersed CNBS dispersion liquid;

[0028] (2) A small amount of water-soluble hydroxide is added to the CNBS dispersion liquid in multiple times, and stirring is performed until complete dissolution to obtain a mixed liquid;

[0029] (3) When the temperature of the mixed liquid cools to below 60℃, a certain amount of complexing agent is weighed and stirred until dissolved;

[0030] (4) The deionized water is used to dilute to the target amount to obtain an electrolytic stripping solution.

[0031] The electrolytic stripping method for removing nitride coating uses the electrolytic stripping solution as described above as an electrolyte to perform electrochemical stripping treatment on a workpiece to be stripped of nitride coating; preferably, the electrochemical stripping treatment time is 1-15 minutes.

[0032] Optionally, the electrolytic stripping solution is stirred to enhance the flushing effect when the electrochemical stripping treatment is performed.

[0033] Optionally, the electrolytic stripping solution is stirred clockwise; the workpiece is fixed on the anode, and the anode is controlled to rotate counterclockwise; to further enhance the flushing effect.

[0034] Optionally, the stirring rate of the electrolytic stripping solution is 80-220 r / min, and further 100-200 r / min; the rotation speed of the workpiece is 20-55 r / min, and further 20-30 r / min.

[0035] Optionally, the temperature of the electrolytic stripping solution is controlled to be 45-60℃ when the electrochemical stripping treatment is performed; preferably, the direct current voltage is controlled to be 4-12V.

[0036] Optionally, the material of the cathode plate is one of graphite and red copper; the material of the anode is brass, and the surface of the anode is plated with a nickel layer with a thickness of 4-8 microns. Optionally, the inter-electrode distance of the anode and the cathode is 10-30 mm.

[0037] Application of nanometer carbon spheres in removing nitride coating by electrochemical stripping method, the nanometer carbon spheres are dispersed in the electrolyte. In this way, the nitride coating can be uniformly and quickly removed in the electrochemical stripping process, and the substrate damage is avoided.

[0038] Optionally, the particle size of the nanocarbon sphere is 20-800 nm, preferably 50-700 nm, and more preferably 100-600 nm.

[0039] The electrolytic stripping solution of the present application is used for electrochemical stripping, which can effectively improve the stripping efficiency, and also make the current as evenly distributed as possible, effectively reduce the defect generation rate of the workpiece surface, and obtain a high-quality surface. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a SEM (a) and TEM (b) of a nanocarbon sphere of the present application. DETAILED DESCRIPTION

[0041] The present application will be described in detail below with reference to examples. It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict. In each example and comparative example, the nanocarbon sphere (CNBS) used is purchased from Nanjing Jicang Nanotechnology Co., Ltd., product model: solid carbon sphere JCSC-99-550-COOH.

[0042] Example 1

[0043] A. Provide a sample coated with nitride coating

[0044] An arc ion plating device (Shenyang Willy Del Vacuum Technology Co., Ltd.) was used to coat a polished surface of a high-speed steel (W2Mo9Cr4VCo8, Dongguan Chang'an You Titanium Metal Material Co., Ltd.) sample (size 35 mm x 10 mm x 10 mm) with a thickness of 4.7 microns of nitride coating, the binding layer of which is CrN, and the functional layer is TiAlN, as a sample.

[0045] B. Provide an electrolytic stripping solution

[0046] The preparation method of the electrolytic stripping solution is shown in Table 1.

[0047] Table 1

[0048]

[0049] According to Table 2, the electrolytic stripping solution 10L was prepared according to Table 1, and was ready for use.

[0050] Table 2

[0051] Name NaOH ETDDA-4Na DBS CNBS Deionized water Concentration 115 g / L 60 g / L 8 g / L 4.0 g / L Balance

[0052] C. Nitride coating stripping

[0053] The electrolytic stripping solution is put into an electrolytic tank and heated and kept at 45-60°C; the sample is fixed on the anode (the anode is equipped with a motor for driving the anode to rotate); the electrolytic stirring pump and the motor are started, and the stirring rate of the electrolytic stripping solution is 100 r / min; the rotation speed of the anode is 20 r / min. The inter-electrode potential is kept at 4.5 V / cm.

[0054] The tank body of the electrolytic tank is made of PP material, and a quartz heating tube is arranged on the side wall of the tank body for heating the electrolyte; a cathode and an anode are arranged in the tank body, and the inter-electrode distance of the cathode and the anode is 15 mm. Surface observation is performed every 80 s.

[0055] After observation, the TiAlN and CrN coatings on the sample block are completely removed clean after 400 s, and the high-speed steel substrate body is exposed; no corrosion pits are observed on the surface of the substrate.

[0056] Comparative Example 1

[0057] Example 1 is repeated, except that the concentration of DBS in the electrolytic stripping solution is 0, i.e. no DBS is added.

[0058] After electrolytic stripping treatment for 400 s, visual sampling observation shows that the TiAlN and CrN coatings on the sample block are not completely removed clean, and the high-speed steel sample substrate is partially black and gray; no corrosion pits are observed on the surface of the substrate; further additional electrolytic stripping treatment for 160 s, and then sampling observation shows that the black and gray color of the high-speed steel sample substrate disappears, but corrosion pits appear on the surface of the substrate.

[0059] Comparative Example 2

[0060] Example 1 is repeated, except that the concentration of CNBS in the electrolytic stripping solution is 0, i.e. no CNBS is added.

[0061] After electrolytic stripping treatment for 400 s, visual sampling observation shows that the TiAlN and CrN coatings on the sample block are not completely removed clean, and the high-speed steel sample substrate is partially black and gray; no corrosion pits are observed on the surface of the substrate; further additional electrolytic stripping treatment for 320 s, and then sampling observation shows that the black and gray color of the high-speed steel sample substrate disappears, but corrosion pits appear on the surface of the substrate.

[0062] Comparative Example 3

[0063] Example 1 is repeated, except that the stirring rate of the electrolytic stripping solution is 0 r / min; and the rotation speed of the workpiece is 0 r / min, i.e. the workpiece does not move relative to the electrolyte.

[0064] After the electrolytic stripping treatment 420s, the TiAlN and CrN coatings on the sample block were not completely stripped, and the high-speed steel sample substrate was partially black and gray. No corrosion pits were observed on the surface of the substrate. After an additional electrolytic stripping treatment for 160s, the black and gray color of the high-speed steel sample substrate disappeared, but fine corrosion pits appeared on the surface of the substrate.

[0065] Example 2

[0066] A. Provide a sample coated with a nitride coating

[0067] A nitride coating with a thickness of 3.8 microns was deposited on the polished surface of a high-speed steel (W2Mo9Cr4VCo8, Dongguan Chang'an Youtitan Metal Material Co., Ltd.) sample (size 35mm x 10mm x 10mm) using an arc ion plating device (Shenyang Willyde Vacuum Technology Co., Ltd.). The binding layer of the nitride coating was TiAlN, and the functional layer was deposited by alternating stacking of TiAlN and CrAlN with a modulation ratio of 1:2 and a modulation period of 9.6nm.

[0068] B. Provide an electrolytic stripping solution

[0069] According to Table 3, an electrolytic stripping solution of 10L was prepared according to Table 1 for standby.

[0070] Table 3

[0071] Name NaOH ETDDA-4Na DBS CNBS Deionized water Concentration 130 g / L 48 g / L 6 g / L 3.0 g / L Balance

[0072] C. Nitride coating removal

[0073] The above electrolytic stripping solution was placed in an electrolytic cell and heated to 45-60°C; the sample was fixed on the anode (the anode was equipped with a motor for driving the anode to rotate); the electrolytic stirring pump and motor were started, the stirring rate of the electrolytic stripping solution was 100r / min, and the rotation speed of the anode was 20r / min. The inter-electrode potential was maintained at 5.4V / cm, and the reaction time was 280s.

[0074] The electrolytic cell was made of PP material, and a quartz heating tube was provided on the side wall of the cell body for heating the electrolyte. The cathode and anode were arranged in the cell, and the inter-electrode distance was 15mm.

[0075] After observation, the TiAlN and CrAlN coatings on the sample block were completely stripped, exposing the high-speed steel substrate; no corrosion pits were observed on the surface of the substrate.

[0076] Example 3

[0077] A. Provide a sample coated with a nitride coating

[0078] A nitride coating with a thickness of 5.2 microns was deposited on a polished surface of a high-speed steel (W2Mo9Cr4VCo8, Dongguan Chang'an Youtitan Metal Material Co., Ltd.) sample (size 35 mm x 10 mm x 10 mm) using an arc ion plating device (Shenyang Williden Vacuum Technology Co., Ltd.), the nitride coating having a bonding layer of CrAlN and a functional layer of AlCrBN and CrAlN deposited in an alternating stack, a modulation ratio of 1:1, and a modulation period of 12.1 nm.

[0079] B. Providing an electrolytic stripping solution

[0080] According to Table 4, an electrolytic stripping solution 10L was prepared according to Table 1, and was ready for use.

[0081] Table 4

[0082] Name NaOH ETDDA-4Na DBS CNBS Deionized water Concentration 170 g / L 48 g / L 5 g / L 2.5 g / L Balance

[0083] C. Stripping of the nitride coating

[0084] The electrolytic stripping solution was placed in an electrolytic cell and heated and kept at a temperature of 45-60°C; the sample was fixed on the anode (the anode was equipped with a motor for driving the anode to rotate); the electrolytic stirring pump and the motor were started, the stirring rate of the electrolytic stripping solution was 100 r / min; the rotation speed of the anode was 20 r / min. The inter-electrode potential was kept at 6 V / cm, and the reaction time was 380 s.

[0085] The cell body was made of PP material, a quartz heating tube was arranged on the sidewall of the cell body for heating the electrolyte; a cathode and an anode were arranged in the cell body, and the inter-electrode distance of the cathode and the anode was 25 mm.

[0086] After observation, the AlCrBN and CrAlN coatings on the sample block were completely stripped clean, exposing the high-speed steel substrate body; no corrosion pits were observed on the surface of the substrate.

[0087] Example 4

[0088] A. Providing a sample coated with a nitride coating

[0089] A nitride coating with a thickness of 3.4 microns was deposited on a polished surface of a high-speed steel (W2Mo9Cr4VCo8, Dongguan Chang'an Youtitan Metal Material Co., Ltd.) sample (size 35 mm x 10 mm x 10 mm) using an arc ion plating device (Shenyang Williden Vacuum Technology Co., Ltd.), the nitride coating having a bonding layer of AlTiN and a functional layer of AlTiN and AlCrSiN deposited in an alternating stack, a modulation ratio of 3:1, and a modulation period of 11.6 nm.

[0090] B. Providing an electrolytic stripping solution

[0091] According to Table 5, the electrolytic stripping solution 10L is prepared according to Table 1, and is standby.

[0092] Table 5

[0093] Name NaOH ETDDA-4Na DBS CNBS Deionized water Concentration 170 g / L 48 g / L 4 g / L 2 g / L Balance

[0094] C. Nitride coating stripping

[0095] The above electrolytic stripping solution is put into an electrolytic tank and heated and kept at 45-60 DEG C; the sample is fixed on the anode (the anode is equipped with a motor for driving the anode to rotate); the electrolytic stirring pump and the motor are started, the stirring rate of the electrolytic stripping solution is 100 r / min; the rotation speed of the anode is 20 r / min, the inter-electrode potential is kept at 6V / cm, and the reaction time is 440s.

[0096] The tank body is made of PP material, the sidewall of the tank body is provided with a quartz heating tube for heating the electrolyte; the tank body is provided with a cathode and an anode, and the inter-electrode distance of the cathode and the anode is 20mm.

[0097] After observation, the AlTiN and AlCrSiN coatings on the sample block are completely stripped clean, and the high-speed steel substrate body is exposed; no corrosion pits are found on the surface of the substrate.

[0098] As can be seen from the above, the electrolytic stripping solution can be used for efficiently removing the multi-element (Al, Cr, Si, Ti, B, etc.) nitride hard film on the surface of a high-speed steel workpiece, and the removal process is relatively uniform and stable, and no corrosion pits are generated.

[0099] The content illustrated in the above examples should be understood as that the examples are only used for more clearly illustrating the present application, and are not used for limiting the scope of the present application, and after reading the present application, the modification of various equivalent forms of the present application by those skilled in the art falls within the scope defined by the appended claims of the present application.

Claims

1. An electrolytic stripping solution for stripping nitride coatings, characterized in that The electrolytic liquid comprises a water-soluble hydroxide, a complexing agent, nanometer carbon balls, an anionic surfactant and water; wherein the concentration of the nanometer carbon balls is 1-25 g / L, and the concentration of the anionic surfactant is 1-50 g / L.

2. The electrolytic de-coating solution according to claim 1, wherein The concentration of the nanometer carbon balls is 2-15 g / L.

3. The electrolytic de-coating solution of claim 2, wherein, The concentration of the nanometer carbon balls is 2-8 g / L.

4. The electrolytic strip solution of claim 1, wherein The concentration of the anionic surfactant is 4-30 g / L.

5. The electrolytic de-coating solution of claim 4, wherein, The concentration of the anionic surfactant is 4-16 g / L.

6. The electrolytic de-coating liquid according to any one of claims 1 to 5, characterized in that, The particle size of the nanometer carbon balls is 20-800 nm.

7. The electrolytic de-coating solution of claim 6, wherein The particle size of the nanometer carbon balls is 50-700 nm.

8. The electrolytic de-coating solution of claim 7, wherein, The particle size of the nanometer carbon balls is 100-600 nm.

9. The electrolytic de-coating solution according to any one of claims 1 to 5, wherein The nanometer carbon balls are modified nanometer carbon balls, the surface of the modified nanometer carbon balls contains hydroxyl functional groups, and the content of the hydroxyl functional groups is ≥ 4 wt%.

10. The electrolytic de-coating solution according to any one of claims 1 to 5, characterized in that, The anionic surfactant is sodium dodecyl benzene sulfonate, sodium hexadecyl sulfonate or fatty alcohol polyether-n carboxylate.

11. The electrolytic de-coating solution according to any one of claims 1 to 5, wherein The anionic surfactant is sodium dodecyl benzene sulfonate.

12. The electrolytic de-coating solution according to any one of claims 1 to 5, wherein The concentration of the water-soluble hydroxide is 10-200 g / L; and the concentration of the complexing agent is 10-100 g / L.

13. The electrolytic de-coating solution of claim 12, wherein, The concentration of the water-soluble hydroxide is 50-200 g / L; and the concentration of the complexing agent is 50-80 g / L.

14. The electrolytic strip solution of claim 12, wherein, The water-soluble hydroxide is a water-soluble alkali metal hydroxide, and the water-soluble alkali metal hydroxide comprises one or more of sodium hydroxide and potassium hydroxide; and the complexing agent comprises one or more of monoethanolamine, ethylenediamine tetraacetic acid sodium and tartaric acid.

15. An electrolytic stripping method for stripping off a nitride coating, characterized by, The workpiece to be removed is subjected to electrochemical removal treatment by using the electrolytic liquid as claimed in any one of claims 1-14 as an electrolyte.

16. The electrolytic de-coating method of claim 15, wherein, The electrochemical removal treatment time is 1-15 min; and the electrolyte is stirred during the electrochemical removal treatment.

17. Use of nanocarbon spheres in the removal of nitride coatings by electrochemical de-coating, characterized in that, The nanometer carbon balls are dispersed in the electrolyte.

18. The use according to claim 17, characterized in that, The particle size of the nanometer carbon balls is 20-800 nm.

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