A method for preparing a wear-resistant composite coating of Ni / WC

Abstract

This invention discloses a method for preparing a Ni / WC wear-resistant composite coating. The specific steps include: roughening a substrate; electro-cleaning the roughened substrate; activating the electro-cleaned substrate; pre-depositing the activated substrate; and subsequent brush-plating nickel onto the pre-deposited substrate. This wear-resistant coating preparation method is simple, process-controllable, has low equipment cost, and produces a tight bond between the composite coating and the substrate. Through the roughening and pre-depositing treatment methods employed in this invention, a uniform Ni / WC composite coating with excellent wear resistance can be successfully obtained.

Description

Technical Field

[0001] This invention belongs to the field of composite coating preparation technology, specifically relating to a method for preparing a Ni / WC wear-resistant composite coating. Background Technology

[0002] With the advancement of technology and industrial development, mechanical parts often need to operate in harsh environments, thus placing higher demands on their surface properties. Traditional single-coating methods for surface modification often only improve a specific surface property. Composite coatings, however, retain the properties of a single coating while also enhancing the workpiece's hardness, wear resistance, and corrosion resistance. Therefore, applying composite coatings to improve surface properties is considered an effective method for addressing corrosion and wear problems in challenging environments.

[0003] Tungsten carbide is widely used in the preparation of wear-resistant composite coatings due to its excellent high-temperature resistance, corrosion resistance, and wear resistance. However, existing preparation methods suffer from defects such as uneven WC distribution, uneven coating, and unstable performance. Summary of the Invention

[0004] To address the aforementioned problems, this invention overcomes the shortcomings of existing Ni / WC wear-resistant composite coating preparation methods and provides a novel method for preparing Ni / WC wear-resistant composite coatings. This method involves pre-depositing tungsten carbide into the sandblasted grooves of the substrate after sandblasting, followed by electrobrush plating to obtain a smooth, dense, and uniformly performing Ni / WC wear-resistant composite coating. The specific technical solution is as follows:

[0005] A method for preparing a Ni / WC wear-resistant composite coating includes the following steps:

[0006] (1) The substrate is roughened by sandblasting and then cleaned after sandblasting.

[0007] (2) Connect the cleaned substrate to the power supply in the forward direction for electrical cleaning.

[0008] (3) Connect the substrate after the electro-cleaning process to the power supply in reverse for activation;

[0009] (4) Place the activated substrate horizontally in the pre-deposition solution for pre-deposition WC treatment;

[0010] (5) Connect the substrate after pre-depositing WC to the power supply for brush nickel plating; after cleaning and drying, a Ni / WC composite coating with tight bonding and good wear resistance can be obtained.

[0011] Specifically, the quartz sand used in the sandblasting process described in this invention has a particle size of 800 mesh, and the compressed air pressure in the spray gun is 0.3 to 0.7 MPa.

[0012] Preferably, the cleaning process in step (1) is ultrasonic-assisted cleaning.

[0013] Preferably, the electro-cleaning solution in step (2) consists of 25 g / L sodium hydroxide, 20 g / L sodium carbonate, 50 g / L sodium phosphate, 3 g / L sodium chloride, and 0.1 mL / L OP emulsifier. The electro-cleaning voltage is 2–12 V, the speed of the plating pen relative to the substrate is 50–200 mm / s, and the electro-cleaning time is 15–180 s.

[0014] Preferably, the activation solution in step (3) consists of 40 g / L hydrochloric acid with a mass fraction of 37%, 150 g / L sodium chloride, and 0.5 mL / L 0.1% methyl red ethanol solution. The activation voltage is 4–10 V, the speed of the plating pen relative to the substrate is 50–300 mm / s, the activation time is 10–60 s, and the activation temperature is 40–60 °C.

[0015] Preferably, the pre-deposition treatment liquid in step (4) needs to be magnetically stirred during use, and the rotor speed is 10-30 r / min.

[0016] Preferably, the pre-deposition treatment solution in step (4) consists of 5-50 g / L WC, 0.5-5 g / L polyethylene glycol and the remainder deionized water, and the pre-deposition time is 60-600 s.

[0017] Preferably, the nickel plating solution in step (5) consists of 400 g / L nickel sulfate, 30 g / L nickel chloride, 30 g / L hydrochloric acid with a mass fraction of 37%, 70 mL / L acetic acid, and 5–15 g / L WC. The brush plating voltage is 4–12 V, the speed of the plating pen relative to the substrate is 50–500 mm / s, the brush plating time is 3–20 min, and the brush plating temperature is 60–80 °C.

[0018] The method for preparing the Ni / WC wear-resistant composite coating provided by this invention employs a combination of sandblasting and pre-deposition in the pretreatment process. This ensures that WC powder is uniformly deposited in the grooves formed by sandblasting before brush coating, guaranteeing the WC content in the composite coating and avoiding the problem of uneven WC distribution caused by manual operation. Simultaneously, the pre-deposition treatment allows for complete coating of the WC powder in the grooves with a thinner Ni layer during subsequent brushing, effectively improving efficiency and solving the problem of coating failure caused by WC powder detachment due to incomplete coating. Compared to traditional composite coating preparation methods, the wear-resistant coating obtained by this invention exhibits uniform performance, effectively avoiding localized failure during subsequent use of the processed workpiece and significantly extending the service life of the wear-resistant coating. Attached Figure Description

[0019] Figure 1 The image shows the EDS energy spectrum of the Ni / WC wear-resistant composite coating obtained in Example 1.

[0020] Figure 2 Here is a SEM image of the Ni / WC wear-resistant composite coating obtained in Example 2;

[0021] Figure 3 This is a SEM image of the Ni / WC wear-resistant composite coating obtained in Example 3. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0023] Example 1:

[0024] (1) Place the substrate in a sandblasting machine for sandblasting treatment. The compressed air pressure in the spray gun is 0.6 MPa.

[0025] (2) Place the substrate after sandblasting in deionized water for ultrasonic cleaning for 10 minutes.

[0026] (3) Connect the substrate after ultrasonic cleaning to the power supply of the brush plating machine for electro-cleaning. The electro-cleaning voltage is 6V, the relative movement speed of the plating pen is 100mm / s, and the electro-cleaning time is 60s.

[0027] (4) Connect the substrate after electro-cleaning to the power supply of the brush plating machine in reverse for activation. The activation voltage is 4V, the relative movement speed of the plating pen is 100mm / s, and the activation time is 30s.

[0028] (5) The activated substrate is placed horizontally in a magnetically stirred pre-deposited WC solution, where the rotor speed is 10 r / min and the pre-deposit time is 180 s. The pre-deposit solution consists of 15 g / L WC and 2 g / L polyethylene glycol.

[0029] (6) Connect the substrate with pre-deposited WC to the power supply of the brush plating machine for brush plating nickel, wherein the WC content in the nickel plating solution is 10g / L. The brush plating working voltage is 4V, the relative movement speed of the plating pen is 50mm / s, and the brush plating time is 10min.

[0030] (7) After cleaning and drying the substrate after nickel plating by brush, a wear-resistant coating with uniform WC distribution can be obtained. The WC content in the coating is 17.0% and the coating hardness is 579.5HV.

[0031] Example 2:

[0032] (1) Place the substrate in a sandblasting machine for sandblasting treatment. The compressed air pressure in the spray gun is 0.5 MPa.

[0033] (2) Place the substrate after sandblasting in deionized water for ultrasonic cleaning for 10 minutes.

[0034] (3) Connect the substrate after ultrasonic cleaning to the power supply of the brush plating machine for electro-cleaning. The electro-cleaning voltage is 4V, the relative movement speed of the plating brush is 150mm / s, and the electro-cleaning time is 60s.

[0035] (4) Connect the substrate after electro-cleaning to the power supply of the brush plating machine in reverse for activation. The activation voltage is 4V, the relative movement speed of the plating pen is 100mm / s, and the activation time is 30s.

[0036] (5) The activated substrate is placed horizontally in a magnetically stirred pre-deposited WC solution, with a rotor speed of 20 r / min and a pre-deposit time of 300 s. The pre-deposit solution consists of 20 g / L WC and 2 g / L polyethylene glycol.

[0037] (6) Connect the substrate with pre-deposited WC to the power supply of the brush plating machine for brush plating of nickel. The WC content in the nickel plating solution is 10 g / L. The brush plating working voltage is 6V, the relative movement speed of the plating pen is 100 mm / s, and the brush plating time is 10 min.

[0038] (7) After cleaning and drying the substrate after nickel plating by brush, a wear-resistant coating with uniform WC distribution can be obtained. The WC content in the coating is 21.2%, and the coating hardness is 586.3HV.

[0039] Example 3:

[0040] (1) Place the substrate in a sandblasting machine for sandblasting treatment. The compressed air pressure in the spray gun is 0.7 MPa.

[0041] (2) Place the substrate after sandblasting in deionized water for ultrasonic cleaning for 10 minutes.

[0042] (3) Connect the substrate after ultrasonic cleaning to the power supply of the brush plating machine for electro-cleaning. The electro-cleaning voltage is 6V, the relative movement speed of the plating pen is 100mm / s, and the electro-cleaning time is 60s.

[0043] (4) Connect the substrate after electro-cleaning to the power supply of the brush plating machine in reverse for activation. The activation voltage is 2V, the relative movement speed of the plating pen is 100mm / s, and the activation time is 180s.

[0044] (5) The activated substrate is placed horizontally in a magnetically stirred pre-deposited WC solution, with a rotor speed of 10 r / min and a pre-deposit time of 300 s. The pre-deposit solution consists of 35 g / L WC and 4 g / L polyethylene glycol.

[0045] (6) Connect the substrate with pre-deposited WC to the power supply of the brush plating machine for brush plating nickel, wherein the WC content in the nickel plating solution is 15g / L. The brush plating working voltage is 4V, the relative movement speed of the plating pen is 50mm / s, and the brush plating time is 10min.

[0046] (7) After cleaning and drying the substrate after nickel plating by brush, a wear-resistant coating with uniform WC distribution can be obtained. The WC content in the coating is 27.8%, and the coating hardness is 599.0 HV.

[0047] Comparative Example 1: This comparative example does not undergo WC pre-deposition treatment.

[0048] (1) Place the substrate in a sandblasting machine for sandblasting treatment. The compressed air pressure in the spray gun is 0.7 MPa.

[0049] (2) Place the substrate after sandblasting in deionized water for ultrasonic cleaning for 10 minutes.

[0050] (3) Connect the substrate after ultrasonic cleaning to the power supply of the brush plating machine for electro-cleaning. The electro-cleaning voltage is 6V, the relative movement speed of the plating pen is 100mm / s, and the electro-cleaning time is 60s.

[0051] (4) Connect the substrate after electro-cleaning to the power supply of the brush plating machine in reverse for activation. The activation voltage is 2V, the relative movement speed of the plating pen is 100mm / s, and the activation time is 180s.

[0052] (5) Connect the activated substrate to the power supply of the brush plating machine for electroplating nickel, wherein the WC content in the nickel plating solution is 15g / L. The brush plating working voltage is 4V, the relative movement speed of the plating pen is 50mm / s, and the brush plating time is 20min.

[0053] (6) After cleaning and drying the substrate after brush-plating nickel, a Ni / WC composite coating can be obtained. The WC content in the obtained coating is only 9.8% and is unevenly distributed. The WC content in the coating gradually increases along the brush plating direction. When used as a wear-resistant coating, it has poor uniformity and is prone to local failure.

[0054] Comparative Example 2: No WC was added to the nickel plating solution in this comparative example.

[0055] (1) Place the substrate in a sandblasting machine for sandblasting treatment. The compressed air pressure in the spray gun is 0.5 MPa.

[0056] (2) Place the substrate after sandblasting in deionized water for ultrasonic cleaning for 10 minutes.

[0057] (3) Connect the substrate after ultrasonic cleaning to the power supply of the brush plating machine for electro-cleaning. The electro-cleaning voltage is 6V, the relative movement speed of the plating pen is 100mm / s, and the electro-cleaning time is 60s.

[0058] (4) Connect the substrate after electro-cleaning to the power supply of the brush plating machine in reverse for activation. The activation voltage is 4V, the relative movement speed of the plating pen is 100mm / s, and the activation time is 30s.

[0059] (5) The activated substrate was placed horizontally in a magnetically stirred pre-deposited WC solution, with a rotor speed of 10 r / min and a pre-deposit time of 180 s. The pre-deposit solution consisted of 15 g / L WC and 2 g / L polyethylene glycol.

[0060] (6) Connect the substrate with pre-deposited WC to the power supply of the brush plating machine for brush nickel plating. No additional WC is added during the brush nickel plating process. The brush plating working voltage is 4V, the relative movement speed of the plating pen is 50mm / s, and the brush plating time is 10min.

[0061] (7) After cleaning and drying the substrate after electroplating nickel, a wear-resistant coating with uniform WC distribution can be obtained. The WC in the coating is mainly concentrated in the groove after sandblasting, but the WC content is only 12.7% and the coating hardness is 373.4 HV.

[0062] The composite coatings obtained in the above embodiments and comparative examples are listed in Table 1:

[0063] Table 1 Comparison of Examples and Comparative Examples

[0064] Examples and Comparative Examples The effect of the resulting composite coating Example 1 The coating has a high and uniform WC content, resulting in high coating hardness. Example 2 The coating has a high and uniform WC content, resulting in high coating hardness. Example 3 The coating has a high and uniform WC content, resulting in high coating hardness. Comparative Example 1 The coating has low WC content and uneven distribution. Comparative Example 2 The coating has a low WC content and a relatively uniform distribution.

Claims

1. A method for preparing a Ni / WC wear-resistant composite coating, characterized in that: Includes the following steps: a) The substrate is roughened and then ultrasonically cleaned. The substrate is a 304 stainless steel strip with a thickness of 0.3 mm. b) Perform an electro-cleaning treatment on the substrate obtained in step a); c) Activate the substrate obtained in step b); d) Perform WC pre-deposition treatment on the substrate obtained in step c); e) Perform electroplating on the substrate obtained in step d), wherein WC is added to the nickel solution during the electroplating process; after cleaning and drying, a Ni / WC composite coating with excellent wear resistance can be obtained.

2. The method for preparing a Ni / WC wear-resistant composite coating according to claim 1, characterized in that: The roughening treatment is a sandblasting treatment, with the compressed air pressure in the spray gun being 0.3 to 0.7 MPa, and the sand used being 800-mesh quartz sand.

3. The method for preparing a Ni / WC wear-resistant composite coating according to claim 1, characterized in that: The electro-cleaning solution consists of 25 g / L sodium hydroxide, 20 g / L sodium carbonate, 50 g / L sodium phosphate, 3 g / L sodium chloride, and 0.1 mL / L OP emulsifier. During the electro-cleaning process, the substrate is connected to the power supply in the forward direction, the operating voltage is 2–12 V, the speed of the plating pen relative to the substrate is 50–200 mm / s, and the electro-cleaning time is 15–180 s.

4. The method for preparing a Ni / WC wear-resistant composite coating according to claim 1, characterized in that: The activation solution consists of 40 g / L hydrochloric acid (37% by mass), 150 g / L sodium chloride, and 0.5 mL / L 0.1% methyl red ethanol solution. During activation, the substrate is connected to a power supply in reverse, the operating voltage is 4–10 V, the speed of the plating pen relative to the substrate is 50–300 mm / s, the activation time is 10–60 s, and the temperature is 40–60 °C.

5. The method for preparing a Ni / WC wear-resistant composite coating according to claim 1, characterized in that: The treatment solution in the pre-deposition WC treatment consists of 5-50 g / L WC and 0.5-5 g / L polyethylene glycol.

6. The method for preparing a Ni / WC wear-resistant composite coating according to claim 5, characterized in that: The pre-deposition WC treatment involves immersing the substrate horizontally in the treatment solution for 60–600 seconds. During the pre-deposition treatment, the treatment solution is always stirred in a magnetic stirrer with a rotor speed of 10–30 r / min.

7. The method for preparing a Ni / WC wear-resistant composite coating according to claim 1, characterized in that: The nickel solution used in the electroplating process consists of 400 g / L nickel sulfate, 30 g / L nickel chloride, 30 g / L hydrochloric acid (37% by mass), 70 mL / L acetic acid, and 5–15 g / L WC. During electroplating, the substrate is connected to the power supply in the forward direction, and the plating is performed at a working voltage of 4–12 V, a plating pen speed relative to the substrate of 50–500 mm / s, a plating time of 3–20 min, and a temperature of 60–80 °C.

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