Pulse plating method for high wear-resistant spherical chromium plating layer of crystallizer copper tube

Abstract

This invention provides a pulse electroplating method for a high-wear-resistant spherical chromium plating layer on a crystallizer copper tube, relating to the field of electroplating technology. The method includes the following steps: placing the crystallizer copper tube in an electroplating solution containing hexavalent chromium; sequentially electroplating an underlayer, a spherical chromium wear-resistant layer, and a thickening layer on the inner wall surface of the copper tube; the underlayer and thickening layer are electroplated using direct current (DC) electroplating, while the spherical chromium wear-resistant layer is electroplated using single-pulse electroplating. The underlayer electroplating temperature is 50-70℃, and the current density is 30-45 A / dm²; the spherical chromium wear-resistant layer electroplating temperature is 30-40℃, the current density is 35-70 A / dm², the pulse width is 10-20 ms, the on-time is 5-10 ms, the off-time is 2-5 ms, and the time is 0.5-1 h; the thickening layer electroplating temperature is 53-57℃, and the current density is 33-37 A / dm². This invention employs a three-layer structure and pulse electroplating to form a three-dimensional spherical micro chromium layer with a hardness of up to 1000 HV and excellent adhesion (no chromium chipping after 20 thermal shocks). It can also solve the problem of scorching and whitening of the copper tube R-angle through flow plating, significantly improving the service life of the crystallizer.

Description

Technical Field

[0001] This invention mainly relates to the field of electroplating technology, specifically to a pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube. Background Technology

[0002] The crystallizer is a key component of continuous casting equipment. Its inner wall comes into direct contact with the high-temperature steel billet, enduring intense friction, thermal shock, and corrosion. To improve the service life of the crystallizer, a hard chrome plating layer is typically applied to the inner wall of its copper tubes to enhance wear resistance and thermal fatigue resistance. Traditional hard chrome plating processes mainly use DC power and are carried out at relatively high temperatures (55~70℃) and high current densities. The resulting plating layer often has a layered microstructure or contains microcracks. Although this type of plating has a certain degree of hardness, in practical use, it suffers from uneven wear resistance, insufficient surface smoothness, and easy local peeling, making it difficult to meet the requirements of high-end continuous casting processes for long crystallizer life and high stability.

[0003] In recent years, pulse electroplating technology has attracted attention due to its ability to significantly improve the microstructure and performance of coatings. Studies have shown that by controlling the on / off time and pulse width of the pulsed power supply, special chromium coatings with three-dimensional spherical or uneven morphologies can be prepared under low-temperature conditions. These coatings (often called spherical chromium or high-wear-resistant chromium) effectively disperse contact stress and reduce the coefficient of friction due to the formation of a dense, uniform spherical or nodular structure on the surface, thus significantly improving the wear resistance and adhesion of the coating. However, existing research on spherical chromium coatings is mostly focused on small laboratory samples or simple-shaped workpieces. Industrial electroplating processes for slender, irregularly shaped internal structures such as copper tubes used in crystallizers are still immature. In actual production, problems such as scorching, whitening, and uneven coating are prone to occur at the radius (R) corners of copper tubes, and single DC or single pulse processes cannot simultaneously meet the different performance requirements of the underlayer, wear-resistant layer, and thickening layer. Summary of the Invention

[0004] 1. The technical problem that the invention aims to solve: This invention provides a pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube, in order to solve the technical problems existing in the background art.

[0005] 2. Technical Solution: To achieve the above objectives, the technical solution provided by this invention is: a pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube, comprising the following steps: The copper tube of the crystallizer is placed in an electroplating solution containing hexavalent chromium; An underlayer is electroplated onto the inner wall surface of the copper tube in the crystallizer, and the underlayer is electroplated using DC electroplating. A spherical chromium wear-resistant layer is electroplated on the substrate, and the spherical chromium wear-resistant layer is electroplated using a single-pulse electroplating method; A thickening layer is electroplated onto the spherical chromium wear-resistant layer, and the thickening layer is electroplated using DC electroplating.

[0006] Furthermore, the electroplating temperature of the underlayer is 50-70℃, and the current density is 30-45A / dm². 2 The electroplating time is 0.5-1 hour.

[0007] Furthermore, the electroplating temperature of the thickened layer is 53-57℃, and the current density is 33-37 A / dm². 2 The electroplating time is 1-2 hours.

[0008] Furthermore, the electroplating temperature of the spherical chromium wear-resistant layer is 30-40℃, and the current density is 35-70A / dm². 2 The pulse width is 10-20ms, and the electroplating time is 0.5-1 hour.

[0009] Furthermore, the pulse on-time of the single-pulse electroplating is 5-10ms, and the pulse off-time is 2-5ms.

[0010] Furthermore, the electroplating temperature of the spherical chromium wear-resistant layer is 35-38℃, and the current density is 35-40A / dm². 2 The pulse width is 10ms, the on-time is 5ms, the off-time is 2ms, and the electroplating time is 0.5 hours. Furthermore, the current density of the spherical chromium wear-resistant layer is 50-70 A / dm². 2 .

[0011] Furthermore, the electroplating time for the underlayer is 1 hour, and the current density is 33 A / dm². 2 The temperature was 55℃; the electroplating time for the thickened layer was 1 hour, and the current density was 33A / dm³. 2 The temperature is 55℃ Furthermore, the electroplating solution containing hexavalent chromium has a hexavalent chromium content of 230-270 g / L, a sulfate content of 2.2-2.7 g / L, and a trivalent chromium content of 3-10 g / L.

[0012] Furthermore, a flow plating method is adopted in the electroplating process, so that the electroplating solution circulates within the copper tube of the crystallizer.

[0013] 3. Beneficial effects: Compared with the prior art, the technical solution provided by this invention has the following advantages: This invention features a rational design. Through the synergistic optimization of a three-layer structure and pulse electroplating process, a highly wear-resistant chromium plating layer with a three-dimensional spherical microstructure is formed on the inner wall of the copper tube in the crystallizer. Compared with the layered structure of traditional DC chromium plating, the spherical chromium plating layer can achieve a hardness of 1000 HV, and the plating layer is dense without penetrating cracks, resulting in significantly improved wear resistance.

[0014] The combination of a soft chromium underlayer and a single-pulse spherical chromium wear-resistant layer effectively reduces the internal stress of the plating. Thermal shock tests show that the plating under the optimized process does not chip after 20 thermal shocks, while ordinary chromium plating peels off after only 10 shocks, significantly enhancing the adhesion. Simultaneously, the introduction of a flow plating method solves the problem of scorching and whitening at the copper tube's R-corners, ensuring consistent color between the surface and corners, and excellent plating uniformity.

[0015] This solution offers a wide range of process parameters, allowing for the achievement of qualified plating within a range of conditions including a base coat temperature of 50-70℃, a spherical chromium wear-resistant layer temperature of 30-40℃, and a current density of 35-70 A / dm². This facilitates adjustments for industrial production. This technology provides a reliable guarantee for the long-life application of crystallizer copper tubes. Attached Figure Description

[0016] Figure 1 This is a partial cross-sectional schematic diagram of the coating structure on the inner wall of the copper tube of the crystallizer of the present invention; Figure 2 These are comparison images of the microstructure of the spherical chromium wear-resistant layer under different electroplating times according to the present invention. Figure 3 The figure shows the thermal shock test results of the spherical chromium wear-resistant layer under different electroplating times according to the present invention; Figure 4 These are comparative images of the microstructure of the spherical chromium wear-resistant layer under different current densities according to the present invention. Figure 5 The figure shows the thermal shock test results of the spherical chromium wear-resistant layer under different current densities according to the present invention. Figure 6 These are comparison images of the microstructure of the spherical chromium wear-resistant layer under different pulse widths according to the present invention. Figure 7 The figure shows the thermal shock test results of the spherical chromium wear-resistant layer under different pulse widths according to the present invention. Detailed Implementation

[0017] To facilitate understanding of the present invention, a more complete description of the invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the invention will be more thorough and complete.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] In this invention, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," "fixed," "provided with," and "located in" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] It should be noted that structures not described in this invention do not involve the design points and improvement directions of this invention, and can all be achieved using existing technologies known to those skilled in the art.

[0022] See attached document Figure 1-7 The present invention will be further described in detail below with reference to specific embodiments. The present invention provides a pulse electroplating method for a high-wear-resistant spherical chromium plating layer on a crystallizer copper tube. This method employs a three-layer structure design, sequentially forming an underlayer, a spherical chromium wear-resistant layer, and a thickening layer on the inner wall surface of the crystallizer copper tube. The underlayer and thickening layer are plated using direct current electroplating, while the spherical chromium wear-resistant layer is plated using single-pulse electroplating. By optimizing the electroplating parameters of each layer, a high-wear-resistant chromium plating layer with a three-dimensional spherical microstructure can be obtained, effectively solving the problem of scorching and whitening at the R-corner of the copper tube, and improving the adhesion and wear resistance of the plating layer.

[0023] In this invention, the underlay layer serves to form a relatively soft ordinary chromium layer on the surface of the copper substrate, acting as a transition and bonding agent, and reducing the internal stress of the plating layer. The underlay layer is applied using direct current electroplating, with the preferred plating temperature being 50-70℃ and the preferred current density being 30-45 A / dm².2 The electroplating time is preferably 0.5-1 hour. More preferably, the electroplating temperature for the underlayer is 55°C, and the current density is 33 A / dm³. 2 The electroplating time is 1 hour. Under these conditions, the formed soft chromium layer has a slightly white hue and bonds well to the copper substrate. If the electroplating temperature is too low, the internal stress of the plating layer increases; if the temperature is too high, the plating layer hardness is too high, and the buffering effect of the soft chromium layer is lost. The current density is below 30 A / dm³. 2 The deposition rate is too slow, exceeding 45 A / dm. 2 The coating is prone to roughness.

[0024] The spherical chromium wear-resistant layer is the key layer for achieving high wear resistance. Single-pulse electroplating is employed, utilizing the periodic on / off switching of the pulsed current to control the deposition rate of chromium ions, forming a three-dimensional spherical or uneven microstructure under low-temperature conditions. The parameters for pulse electroplating include plating temperature, current density, pulse width, on-time, off-time, and plating time. This invention, through extensive experimentation, has determined the preferred process range for the spherical chromium wear-resistant layer: an electroplating temperature of 30-40℃ and a current density of 35-70 A / dm³. 2 The pulse width is 10-20 ms, and the electroplating time is 0.5-1 hour. Further, the pulse on-time is preferably 5-10 ms, and the pulse off-time is preferably 2-5 ms.

[0025] To verify the effect of electroplating time on the spherical chromium wear-resistant layer, this invention uses a temperature of 30-40℃ and a current density of 60-70 A / dm². 2 Experiments were conducted for different durations with a pulse width of 10ms, and the results are as follows.

[0026]

[0027] Please refer to the attached image for a comparison of the microstructures of different wear-resistant layers after electroplating time. Figure 2 .

[0028] Meanwhile, thermal shock tests were conducted on the coatings prepared at different electroplating times. Data on the effect of electroplating time on thermal shock performance can be found in the appendix. Figure 3 .

[0029] The results showed that when the electroplating time was 5-20 minutes, the microscopic three-dimensionality was poor, and although the high wear-resistant points were uniform and dense, the three-dimensionality was insufficient; when the electroplating time was 30 minutes, the microscopic three-dimensionality was strong, the high wear-resistant points were dense and of moderate size, and the hardness reached 930HV; when the electroplating time was 40 minutes, the spheres were larger and the hardness was 941HV; when the electroplating time was 50-60 minutes, the high wear-resistant points showed unevenness and a tendency to form patches, and the hardness decreased.

[0030] Experiment No. 9 was a comparative experiment. Under DC conditions, normal electroplating was performed. There were no high wear-resistant spots, the plating layer had micro-cracks, and after 10 thermal shocks, the chromium had already chipped off.

[0031] Therefore, the electroplating time for the spherical chromium wear-resistant layer is preferably 30-60 minutes, more preferably 30 minutes.

[0032] Meanwhile, current density has a significant impact on the three-dimensional morphology of spherical chromium. This invention investigated the spherical formation effect of different current densities under conditions of 30-40℃, 10ms pulse width, and 30 minutes of electroplating. The experimental results are as follows.

[0033]

[0034] Please refer to the attached diagram for a comparison of the experimental microstructures under different current densities. Figure 4 ; Meanwhile, thermal shock tests were conducted on the coatings prepared under different current densities. Data on the effect of current density on thermal shock performance can be found in the appendix. Figure 5 .

[0035] The results showed that when the current density was 20-25 A / dm 2 At that time, it can only form flat spheres with extremely poor three-dimensionality and a hardness below 650 HV; the current density is 30 A / dm. 2 At that time, the three-dimensional effect was slightly stronger, the hardness was 725HV, and the current density was 35-40A / dm. 2 At that time, the three-dimensional effect is enhanced, but the uniformity of high wear-resistant points is slightly poor; the current density reaches 50-70A / dm. 2 At that time, it can form a three-dimensional, continuous, and uniform highly wear-resistant micro-coating, of which 50A / dm 2 Hardness reaches up to 1000 HV, 55-70 A / dm 2 The hardness is between 856-900 HV. When the current density exceeds 70 A / dm²... 2 Afterwards, the coating is prone to cracking, and the bath temperature becomes uncontrollable.

[0036] Therefore, the preferred current density for the spherical chromium wear-resistant layer is 35-70 A / dm². 2 More preferably 50-70 A / dm 2 While balancing pelletizing effect and production economy, 35-40A / dm can also be selected. 2 .

[0037] Finally, pulse width is another important parameter in pulse electroplating. This invention operates at a temperature of 30-40℃ and a current density of 50 A / dm². 2 Under the condition of electroplating for 30 minutes, the spherical formation effect of different pulse widths was compared, and the experimental results are as follows.

[0038]

[0039] Please refer to the attached image for a comparison of the experimental microstructures under different pulse widths. Figure 6 .

[0040] Meanwhile, thermal shock experiments were conducted on coatings prepared under different pulse widths. Data on the influence of pulse width on thermal shock performance can be found in the appendix. Figure 7 .

[0041] As can be seen, when the pulse width is 5ms, there are basically no high-wear-resistant spots at the microscopic level, and the coating is similar to DC electroplating; when the pulse width is 10ms, the high-wear-resistant spots are uniform and continuous, and the hardness reaches 1000HV; when the pulse width is 20ms, the high-wear-resistant spots are uniform and continuous, but the hardness drops to 835HV; when the pulse width is 50ms, the high-wear-resistant spots are uneven in size, the three-dimensionality deteriorates, and the coating is not smooth enough. Therefore, the pulse width is preferably 10-20ms, more preferably 10ms, and the conduction time is preferably 5ms and the disconnection time is preferably 2ms. Under these conditions, the spheres are uniformly dispersed and there is no local burning phenomenon.

[0042] After the spherical chromium wear-resistant layer is electroplated, a thickening layer needs to be electroplated on top. The thickening layer is electroplated using direct current (DC) to allow the spherical chromium layer to continue growing, forming larger, more uniform, and denser spheres, further improving the coating thickness and stability. The preferred electroplating temperature for the thickening layer is 53-57℃, and the preferred current density is 33-37 A / dm³. 2 The electroplating time is preferably 1-2 hours. More preferably, the electroplating temperature for the thickened layer is 55°C, and the current density is 33 A / dm³. 2 The electroplating time is 1 hour. Under these conditions, the thickened layer can bond well with the spherical chromium wear-resistant layer without damaging the spherical structure, and the coating hardness is between 715-920 HV, which meets the requirements for crystallizer use.

[0043] To address the problem of easily scorched and whitened corners on the R-angle of copper tubes in crystallizers during field applications, this invention further optimizes the use of a flow plating method, in which the plating solution circulates within the inner cavity of the copper tube during the electroplating process. Flow plating improves the current distribution and mass transfer conditions at the surface and corners of the copper tube, resulting in a uniform plating color and effectively solving the corner whitening defect. Experiments show that using 38℃ and 35A / dm²... 2 Single-pulse electroplating for 1.5 hours, followed by electroplating at 55℃ and 33A / dm. 2 The DC electroplating process, which takes 2 hours, produces a copper tube with consistent color across its surface and corners, and the coating hardness meets the requirements.

[0044] The electroplating solution used in this invention is a hexavalent chromium plating solution, preferably composed of: 230-270 g / L hexavalent chromium, 2.2-2.7 g / L sulfate, and 3-10 g / L trivalent chromium. More preferably, it contains 250 g / L hexavalent chromium, 2.5 g / L sulfate, and 5 g / L trivalent chromium.

[0045] The technical solution and effects of the present invention are further illustrated below through specific embodiments.

[0046] Example 1

[0047] A pulse electroplating method for a high-wear-resistant spherical chromium plating layer on a crystallizer copper tube includes the following steps: The crystallizer copper tube is placed in an electroplating solution containing hexavalent chromium (230 g / L), sulfate (2.3 g / L), and trivalent chromium (3 g / L). A base layer is electroplated onto the inner wall surface of the crystallizer copper tube using direct current electroplating at a temperature of 70°C and a current density of 40 A / dm³. 2 The electroplating time was 0.5 hours. A spherical chromium wear-resistant layer was electroplated onto the base layer using single-pulse electroplating at a temperature of 30℃ and a current density of 50A / dm³. 2 The pulse width was 10ms, the on-time was 5ms, the off-time was 2ms, and the electroplating time was 0.5 hours. A thicker layer was electroplated onto the spherical chromium wear-resistant layer using direct current electroplating at a temperature of 53℃ and a current density of 33A / dm³. 2 The electroplating time was 1.5 hours. The resulting spherical chromium plating layer had a hardness of 850 HV and good adhesion.

[0048] Example 2

[0049] A pulse electroplating method for a high-wear-resistant spherical chromium plating layer on a crystallizer copper tube includes the following steps: the electroplating solution contains 270 g / L hexavalent chromium, 2.7 g / L sulfate, and 10 g / L trivalent chromium. The underlayer is deposited using direct current electroplating at a temperature of 50°C and a current density of 30 A / dm³. 2 The electroplating time is 1 hour. The spherical chromium wear-resistant layer is plated using single-pulse electroplating at a temperature of 40℃ and a current density of 70A / dm³. 2 The pulse width is 20ms, the on-time is 10ms, the off-time is 5ms, and the electroplating time is 1 hour. The thickened layer is plated using DC electroplating at a temperature of 57℃ and a current density of 37A / dm³. 2 The electroplating time was 2 hours. A continuous plating method was used during the electroplating process. The resulting coating had a uniform color, no scorching or whitening at the rounded corners, a hardness of 900 HV, and excellent adhesion in thermal shock tests.

[0050] Example 3 (Preferred Example) A pulse electroplating method for a high-wear-resistant spherical chromium plating layer on a crystallizer copper tube includes the following steps: the electroplating solution contains 250 g / L hexavalent chromium, 2.5 g / L sulfate, and 5 g / L trivalent chromium. The underlayer is deposited using direct current electroplating at a temperature of 55°C and a current density of 33 A / dm³. 2 The electroplating time is 1 hour. The spherical chromium wear-resistant layer is plated using single-pulse electroplating at a temperature of 38℃ and a current density of 35A / dm³. 2The pulse width is 10ms, the on-time is 5ms, the off-time is 2ms, and the electroplating time is 0.5 hours. The thickened layer is applied using DC electroplating at a temperature of 55℃ and a current density of 33A / dm³. 2 The electroplating time was 1 hour. A flow plating method was used during the electroplating process. The coating prepared in this embodiment has a uniform and dense three-dimensional sphere microstructure, is of moderate size without any continuous patches, has a hardness of 1000 HV, and did not exhibit chromium chipping after 20 thermal shocks. The color of the copper tube's surface and corners is consistent.

[0051] Example 4 A pulse electroplating method for a high-wear-resistant spherical chromium plating layer on a crystallizer copper tube includes the following steps: the electroplating solution contains 260 g / L hexavalent chromium, 2.6 g / L sulfate, and 8 g / L trivalent chromium. The underlayer is deposited using direct current electroplating at a temperature of 65°C and a current density of 35 A / dm³. 2 The electroplating time was 0.8 hours. The spherical chromium wear-resistant layer was applied using single-pulse electroplating at a temperature of 35℃ and a current density of 60A / dm³. 2 The pulse width is 15ms, the on-time is 8ms, the off-time is 3ms, and the electroplating time is 0.8 hours. The thickened layer is applied using DC electroplating at a temperature of 55℃ and a current density of 35A / dm³. 2 The electroplating time was 1.8 hours. The resulting coating had a hardness of 920 HV, strong spherical three-dimensionality, and good adhesion.

[0052] Example 5

[0053] A pulse electroplating method for a high-wear-resistant spherical chromium plating layer on a crystallizer copper tube includes the following steps: the electroplating solution contains 240 g / L hexavalent chromium, 2.4 g / L sulfate, and 6 g / L trivalent chromium. The underlayer is deposited using direct current electroplating at a temperature of 70°C and a current density of 40 A / dm³. 2 The electroplating time is 0.5 hours. The spherical chromium wear-resistant layer is applied using single-pulse electroplating at a temperature of 30℃ and a current density of 50A / dm³. 2 The pulse width is 10ms, the on-time is 5ms, the off-time is 2ms, and the electroplating time is 0.5 hours. The thickened layer is applied using DC electroplating at a temperature of 57℃ and a current density of 37A / dm³. 2 The electroplating time was 1.5 hours. A continuous plating method was used during the electroplating process. The resulting coating had a hardness of 860 HV, with no whitening at the corners of the copper tube, and good coating uniformity.

[0054] Based on Examples 1-5, the present invention is further summarized and explained as follows: Examples 1-5 demonstrate the feasibility and effectiveness of preparing a high-wear-resistant spherical chromium plating layer for crystallizer copper tubes under different combinations of process parameters. Specifically, the process parameters used in Example 3 (underlay: 55℃, 33A / dm)2 1h; Spherical chromium wear-resistant layer: 38℃, 35A / dm 2 Pulse width 10ms, conduction time 5ms, disconnection time 2ms, duration 0.5h; Thickened layer: 55℃, 33A / dm 2 The optimal solution is to use a flow plating method (1 hour; and using 1 hour of flow plating). The resulting coating has a hardness of up to 1000 HV, with uniform and dense spheres without any patches. It does not chip chromium after 20 thermal shocks, and the copper tube surface and corners have the same color, effectively solving the problem of scorching and whitening at the R-corners. Examples 2 and 5 show that the flow plating method can significantly improve the coating uniformity of irregularly shaped parts; Examples 1 and 4 verify that within a wide range of parameters (underlay temperature 50-70℃, current density 30-45A / dm³), the coating uniformity is achieved. 2 Wear-resistant layer temperature 30-40℃, current density 50-70A / dm 2 Pulse width 10-20ms; Thickened layer temperature 53-57℃; Current density 33-37A / dm² 2 All methods can produce spherical chromium plating layers that meet usage requirements, with a hardness between 850-920 HV and good adhesion. Therefore, the three-layer pulse electroplating method and its preferred process range established in this invention are repeatable and industrially applicable. Those skilled in the art can adjust the parameters within the above range according to actual production needs to achieve the preparation of highly wear-resistant spherical chromium plating layers.

[0055] The above-described embodiments are merely illustrative of certain implementations of the present invention, and are described in a relatively specific and detailed manner. However, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These modifications and improvements, and their application in copper tubes of continuous casting crystallizers, all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims

1. A pulse electroplating method for a high-wear-resistant spherical chromium plating layer on a crystallizer copper tube, characterized in that: Includes the following steps: The copper tube of the crystallizer is placed in an electroplating solution containing hexavalent chromium; An underlayer is electroplated onto the inner wall surface of the copper tube in the crystallizer, and the underlayer is electroplated using DC electroplating. A spherical chromium wear-resistant layer is electroplated on the substrate, and the spherical chromium wear-resistant layer is electroplated using a single-pulse electroplating method; A thickening layer is electroplated onto the spherical chromium wear-resistant layer, and the thickening layer is electroplated using DC electroplating.

2. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The electroplating temperature of the underlayer is 50-70℃, and the current density is 30-45A / dm². 2 The electroplating time is 0.5-1 hour.

3. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The electroplating temperature of the thickened layer is 53-57℃, and the current density is 33-37A / dm. 2 The electroplating time is 1-2 hours.

4. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The electroplating temperature of the spherical chromium wear-resistant layer is 30-40℃, and the current density is 35-70A / dm. 2 The pulse width is 10-20ms, and the electroplating time is 0.5-1 hour.

5. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The pulse on-time of the single-pulse electroplating is 5-10ms, and the pulse off-time is 2-5ms.

6. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The electroplating temperature of the spherical chromium wear-resistant layer is 35-38℃, and the current density is 35-40A / dm². 2 The pulse width is 10ms, the conduction time is 5ms, the disconnection time is 2ms, and the electroplating time is 0.5 hours.

7. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The current density of the spherical chromium wear-resistant layer is 50-70 A / dm. 2 .

8. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The electroplating time for the underlayer is 1 hour, and the current density is 33 A / dm². 2 The temperature was 55℃; the electroplating time for the thickened layer was 1 hour, and the current density was 33A / dm³. 2 The temperature is 55℃.

9. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The electroplating solution containing hexavalent chromium has a hexavalent chromium content of 230-270 g / L, a sulfate content of 2.2-2.7 g / L, and a trivalent chromium content of 3-10 g / L.

10. The pulse electroplating method for a high wear-resistant spherical chromium plating layer on a crystallizer copper tube according to claim 1, characterized in that: The electroplating process employs a flow plating method, allowing the electroplating solution to circulate within the copper tube of the crystallizer.

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