System and method for performing vacuum plating on strip steel

Abstract

Disclosed in the present invention is a system for performing vacuum plating on strip steel. The system is arranged in a vacuum cavity, and comprises a first jet deposition section, a first cooling section, a second jet deposition section and a second cooling section, which are sequentially arranged in the movement direction of strip steel, wherein the first jet deposition section and the second jet deposition section are respectively arranged on a first surface side of the strip steel and a second surface side of the strip steel that is opposite the first surface side; the first jet deposition section is configured to spray plating solution steam onto a first surface of the strip steel; and the second jet deposition section is configured to spray the plating solution steam onto a second surface of the strip steel that is opposite the first surface. Correspondingly, further disclosed in the present invention is a method for performing vacuum plating on strip steel. The present application can avoid the problem of zinc re-evaporation caused by the fact that an excessive temperature rise may occur during the production of a thick coating.

Description

A system and method for vacuum plating of steel strip Technical Field

[0001] This invention relates to a system and method for processing steel strip, and more particularly to a system and method for applying a coating to steel strip. Background Technology

[0002] Currently, vacuum plating processes for steel strips only support coating thicknesses between 0.5 and 10 μm. Since the production speed of steel strips is limited by the evaporation rate, producing steel strips with thicker coatings requires reducing the production speed, which leads to decreased production efficiency.

[0003] In the existing technology, some technical solutions have attempted to perform continuous vacuum plating on steel strips with thick coatings, for example:

[0004] Chinese patent document CN112262226A, published on January 22, 2021, entitled "Vacuum Deposition Equipment and Method for Coating Substrate", discloses a continuous vacuum deposition method in which the coating nozzles are arranged face-to-face on both sides of a strip steel.

[0005] Spraying both sides of the strip steel with zinc can improve production efficiency and make the production unit layout more compact. However, when producing a thick zinc layer, the coatings on both sides will release condensation heat at the same time, which will cause the temperature of the strip steel and the coating to rise significantly, thus bringing the risk of coating re-evaporation and affecting product quality. Summary of the Invention

[0006] One of the objectives of this invention is to provide a system for vacuum plating strip steel that can avoid excessive temperature rise during the production of thick plating layers, which could cause zinc to re-evaporate, reduce yield, and contaminate the chamber.

[0007] To achieve the above objectives, the present invention provides a system for vacuum plating strip steel, which is disposed within a vacuum chamber, the system comprising the following components arranged sequentially along the travel direction of the strip steel:

[0008] The strip comprises a first jet deposition section, a first cooling section, a second jet deposition section, and a second cooling section; wherein the first jet deposition section and the second jet deposition section are respectively located on the first surface side of the strip and the second surface side opposite to the first surface side, the first jet deposition section being used to spray plating solution vapor onto the first surface of the strip, and the jet deposition section being used to spray plating solution vapor onto the second surface of the strip opposite to the first surface.

[0009] When vacuum-coating strip steel using PVD (physical vapor deposition), heat is released when the plating solution vapor condenses (sublimates). This heat is absorbed by the strip steel, resulting in an increase in the strip steel temperature and consequently, an increase in the temperature of the coating.

[0010] Because the saturated vapor pressure of the plating solution is very high, the temperature of the plating solution must be controlled to not exceed 450°F in a vacuum environment. Otherwise, the plating solution on the substrate surface will re-evaporate, which not only reduces the yield of the plating material but also causes problems with the stable operation of the equipment. Therefore, the coating thickness is limited by the large amount of condensation heat released onto the steel plate during vapor deposition. If a thicker coating needs to be deposited, the heat released during condensation is greater, which may lead to excessively high coating temperatures and subsequent re-evaporation of the coating.

[0011] Therefore, to solve the above problems, this invention, based on the aforementioned system, employs a method of alternating single-sided deposition and cooling to vacuum plate the strip steel. Specifically, after deposition on one side of the strip steel, cooling is performed from the opposite side of the deposition surface; then, deposition is performed on the other side of the strip steel, and cooling is performed from the opposite side. This method avoids the heat generated by the thick coating causing the temperature to rise sufficiently to lead to the re-evaporation of the zinc layer, and also avoids damage to the coating on the strip steel surface during cooling.

[0012] Furthermore, the system of the present invention also includes a surface pretreatment device disposed upstream of the first jet deposition section along the travel direction of the strip. In some embodiments, the surface pretreatment device is used to clean the surface of the strip. In some embodiments, the surface pretreatment device is a plasma etching device. In some embodiments, the system of the present invention also includes a pre-plating device for pre-plating the strip.

[0013] Furthermore, the system described in this invention also includes a heating device disposed upstream of the pretreatment device along the walking direction of the strip.

[0014] In this paper, the first jet deposition section and the second jet deposition section respectively include a crucible, a plating solution vapor nozzle, and a pipe for conveying plating solution vapor to the plating solution vapor nozzle.

[0015] In this document, the first cooling section and the second cooling section can be cooled using cooling devices well-known in the art. These cooling devices include, but are not limited to, cooling rollers, radiation cooling devices, etc. The cooling devices for the first cooling section and the second cooling section can be the same or different.

[0016] Furthermore, in the system described in this invention, the first cooling section includes a cooling roller that is in direct contact with the strip; and / or the second cooling section includes a cooling roller that is in direct contact with the strip.

[0017] Furthermore, in the system described in this invention, the first cooling roller contacts the second surface of the strip; the second cooling roller contacts the first surface of the strip.

[0018] Furthermore, in the system described in this invention, the first cooling section includes a radiative cooling device; and / or the second cooling section includes a radiative cooling device.

[0019] Another objective of this invention is to provide a method for vacuum plating strip steel. This method reduces the heat release of zinc deposition by depositing and cooling both sides of the strip steel, thereby reducing the temperature rise of the strip steel and preventing the thick coating from re-evaporating due to excessive temperature.

[0020] To achieve the above objectives, the present invention provides a method for vacuum plating strip steel, based on the above-described system implementation, the method comprising the steps of: during the movement of the strip steel:

[0021] In the first jet deposition section, the nozzles spray plating vapor onto the first surface of the strip steel so that the vapor is deposited on the first surface.

[0022] The first cooling section cools the strip steel;

[0023] The nozzles of the second jet deposition section spray plating vapor onto the second surface of the strip steel so that the vapor is deposited on the second surface.

[0024] The second cooling section cools the strip steel.

[0025] This invention employs a method of alternating single-sided deposition and cooling to perform vacuum plating on strip steel. Specifically, after deposition on one side of the strip steel, the strip steel is cooled from the opposite side of the deposition surface. Then, deposition is performed on the other side of the strip steel and cooled from the opposite side. This method avoids the heat generated by the thick plating layer causing the temperature to rise to a level sufficient to cause the zinc layer to re-evaporate, and also avoids damage to the plating layer on the strip steel surface caused by cooling.

[0026] Furthermore, in the method described in this invention, before the step of spraying plating solution vapor onto the first surface of the strip steel by the nozzle of the first jet deposition section, the method further includes pretreatment of the strip steel surface.

[0027] Furthermore, in the method described in this invention, the strip steel is preheated before pretreatment of the strip steel surface.

[0028] Furthermore, in the method described in this invention, in the step of preheating the strip steel, the strip steel is preheated to 120-180°C.

[0029] Controlling the preheating temperature of the strip steel between 120-180℃ can ensure that the coating has good density and adhesion.

[0030] Furthermore, in the method described in this invention, the plating solution vapor is zinc vapor.

[0031] Another object of the present invention is to provide a coated steel strip that produces no emissions during production, offering significant environmental advantages. Furthermore, it reduces the entry of hydrogen, lowering the risk of hydrogen embrittlement, and the coated surface exhibits excellent morphology and good plating properties.

[0032] To achieve the above objectives, the present invention provides a coated steel strip, wherein the coating is obtained by the method described above.

[0033] Furthermore, in the coated steel strip described in this invention, the coating thickness is >10μm.

[0034] Compared with the prior art, the system and method for vacuuming strip steel and the coated strip steel described in this invention have the following advantages and beneficial effects:

[0035] The vacuum system for strip steel described in this invention can avoid excessive temperature rise during the production of thick coatings, which could cause zinc to re-evaporate, reduce yield, and contaminate the chamber.

[0036] The vacuum coating method for strip steel described in this invention employs a single-sided deposition and alternating cooling process to perform vacuum plating on the strip steel. This avoids the heat generated by the thick coating layer, which could cause the temperature to rise to a level sufficient to cause the zinc layer to re-evaporate, and also avoids damage to the coating layer on the strip steel surface during cooling. This method is suitable not only for the production of thick coatings but also for the production of thin coatings.

[0037] The production process of the coated steel strip described in this invention is emission-free, offering significant environmental advantages. Furthermore, it reduces the entry of hydrogen, lowering the risk of hydrogen embrittlement, and the coated surface exhibits excellent morphology and good plating properties. Attached Figure Description

[0038] Figure 1 shows a schematic diagram of the system for vacuum plating strip steel according to the present invention.

[0039] Figure 2 shows a schematic diagram of another embodiment of the vacuum plating system for strip steel described in this invention. Detailed Implementation

[0040] The system for vacuum plating strip steel will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, this explanation and description do not constitute an undue limitation on the technical solution of the present invention.

[0041] Figure 1 shows a schematic diagram of the structure of the vacuum plating system for strip steel according to one embodiment of the present invention.

[0042] It should be noted that the system described in this invention is used for vacuum plating, and therefore it is located inside the vacuum chamber of the vacuum plating process.

[0043] As shown in Figure 1, in some embodiments of the present invention, the system for vacuum coating of strip steel includes: a first jet deposition section 2, a first cooling section 3, a second jet deposition section 4, and a second cooling section 5 arranged along the length direction of the strip steel 1. The first jet deposition section 2 and the second jet deposition section 4 are respectively located on a first surface side and a second surface side opposite to the first surface side of the strip steel.

[0044] In this manner, the first jet deposition section 2 is used to spray plating solution vapor onto the first surface of the strip; the second jet deposition section 4 is used to spray plating solution vapor onto the second surface of the strip opposite to the first surface.

[0045] More specifically, in some embodiments, the first cooling section 3 may include a radiative cooling device 6, and the second cooling section 5 may also include a radiative cooling device 7. In this way, the first cooling section 3 and the second cooling section 5 can cool the two surfaces of the strip without contacting it.

[0046] In some more specific embodiments, crucibles 8 and 10 may be arranged on the first jet deposition section 2 and the second jet deposition section 4, respectively, and the plating solution vapor is delivered to the plating solution vapor nozzles 9 and 11 by pipes. The plating solution vapor is sprayed onto one side of the strip steel through the nozzles and deposited on its surface.

[0047] In some embodiments, a surface pretreatment device may be installed upstream of the first jet deposition section along the strip's travel direction. This device may include a plasma etching device and a pre-plating device. The plasma etching device is used for plasma cleaning of the strip, and the pre-plating device is used for pre-plating the strip.

[0048] In some embodiments, a heating device may be installed upstream of the pretreatment device along the walking direction of the strip to preheat the strip.

[0049] Figure 2 shows a schematic diagram of another embodiment of the vacuum plating system for strip steel described in this invention.

[0050] As shown in Figure 2, this embodiment adopts the same configuration as the embodiment shown in Figure 1, except that the first cooling section 3 may include a first cooling roller 12 that directly contacts the second surface of the strip, and the second cooling section 5 includes a second cooling roller 13 that directly contacts the first surface of the strip. In this way, the first cooling section 3 and the second cooling section 5 can cool the two surfaces of the strip by directly contacting the strip.

[0051] In another embodiment of the present invention, the present invention also proposes a method for vacuum plating strip steel based on the above system, which includes the steps of: during the movement of the strip steel:

[0052] (1) The nozzle of the first jet deposition section sprays plating liquid vapor onto the first surface of the strip steel so that the vapor is deposited on the first surface;

[0053] (2) The first cooling section cools the strip steel;

[0054] (3) The nozzle of the second jet deposition section sprays plating vapor onto the second surface of the strip steel so that the vapor is deposited on the second surface;

[0055] (4) The second cooling section cools the strip steel.

[0056] In some embodiments, the strip surface may preferably be pretreated before the step of spraying plating solution vapor onto the first surface of the strip through the nozzle of the first jet deposition section.

[0057] In some more specific embodiments, pretreatment may include plasma cleaning and pre-plating.

[0058] In some embodiments, preheating of the strip may be included before pretreatment of the strip surface. In some more specific embodiments, the strip may be preheated to 120-180°C. Controlling the strip preheating temperature between 120-180°C ensures that the coating has good density and adhesion.

[0059] In some more specific embodiments, the plating solution vapor can be zinc vapor. When galvanizing strip steel, since the saturated vapor pressure of zinc at 250°C is approximately 0.01 Pa, while the gas pressure in the vacuum deposition chamber is generally greater than or equal to 0.01 Pa, the temperature of the strip steel should not exceed 250°C to ensure long-term stable operation.

[0060] In some embodiments, the strip can be cooled through direct contact. In other embodiments, the strip can be cooled using non-contact radiative cooling.

[0061] Because this invention can avoid excessive temperature rise that may occur during the production of thick coatings, which could cause zinc to re-evaporate, it is suitable for steel strips with thick coatings, for example, it can be used to manufacture steel strips with a coating thickness greater than 10 μm.

[0062] Of course, in other embodiments, it can also be used to obtain strip steel with a coating thickness of less than or equal to 10 μm.

[0063] The following specific example verifies the system and method for vacuum plating of steel strips described in this invention:

[0064] Vacuum galvanizing is performed on 3mm thick steel strip, with a total zinc coating weight of 720g / m² on both sides. 2 (360g / m² on each side) 2The thickness of the coating on each side is 50 μm.

[0065] Before galvanizing, the strip steel is preheated to 150°C in a vacuum, and 360g / m² of galvanizing is deposited on one side. 2 Zinc is deposited on one side, then the other side is cooled; then 360 g / m² is deposited on the other side. 2 The zinc is applied, and then the side that was first zinc-sprayed is cooled. Specifically:

[0066] After the first deposition, the heat release per unit area q of the strip is:

[0067] Where q represents the heat released per unit area, and its unit is kJ / m². 2 δ represents the amount of sediment, with units of g / m³. 2 Q represents the heat of condensation, with a heat release per unit area of ​​kJ / mol; M represents the molar mass of the coating material, with units of g / mol.

[0068] The temperature rise per unit area ΔT is:

[0069] Where ΔT represents the temperature rise per unit area, and its unit is °C; h represents the strip thickness, and its unit is mm; ρ s This indicates the density of the strip steel, and its unit is kg / m³. 3 ;Cp s It represents the heat released during condensation, and its unit is J / (g·K).

[0070] Therefore, after the first galvanizing, the strip temperature reaches 150 + 61.06 = 211.06℃ < 250℃, which will not cause the coating to evaporate again.

[0071] Then, the strip steel is cooled to 180°C by the first cooling roller of the first cooling section arranged on the opposite side of the deposition surface (i.e. the first surface).

[0072] Subsequently, zinc plating is also deposited on the other side of the strip (i.e. the second surface), which will also cause the temperature to rise by 61.06℃, reaching 180+61.06=241.06℃<250℃, so the coating will not evaporate again.

[0073] Then, a second cooling roller, positioned on the opposite side of the second jet deposition section, cools the strip.

[0074] Therefore, this invention employs a method of alternating single-sided deposition and cooling for vacuum plating of strip steel. For the same plating thickness, the temperature rise of the strip steel is only half that of simultaneous double-sided deposition. This avoids the problem of zinc layer re-evaporation caused by the exothermic reaction of a thick plating layer. Furthermore, in existing production processes, for 3mm thick strip steel, to ensure the temperature rise does not exceed 100℃, the total weight of the double-sided plating is 572g / m². 2 When the single-sided coating thickness is 40μm, the unit speed is only 21mpm, while using the method of this invention, the total weight of the 3mm thick strip steel with double-sided coating is 572g / m. 2 (With a single-sided coating thickness of 40μm), the unit can reach a speed of 25mpm while ensuring that the temperature rise of the strip does not exceed 100℃. Compared with the existing 21mpm, the production efficiency is increased by 19%.

[0075] Furthermore, using the method of this invention, with a zinc evaporation rate of 519 kg / hr for a single crucible (one crucible on each side of the strip), the total weight of the double-sided coating is 40 g / m². 2 When the coating thickness on one side is 2.8μm, the unit speed can reach 360mpm.

[0076] It should be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A system for vacuum plating steel strip, disposed within a vacuum chamber, characterized in that, The system includes, in sequence along the travel direction of the strip: a first jet deposition section, a first cooling section, a second jet deposition section, and a second cooling section; The first jet deposition section and the second jet deposition section are respectively located on the first surface side of the strip and the second surface side opposite to the first surface side. The first jet deposition section is used to spray plating solution vapor onto the first surface of the strip, and the second jet deposition section is used to spray plating solution vapor onto the second surface of the strip opposite to the first surface.

2. The system as described in claim 1, characterized in that, It also includes a surface pretreatment device located upstream of the first jet deposition section along the walking direction of the strip; preferably, the surface pretreatment device is a plasma etching device.

3. The system as described in claim 2, characterized in that, It also includes a heating device located upstream of the pretreatment unit along the direction of the strip's travel.

4. The system as described in claim 1, characterized in that, The first jet deposition section and the second jet deposition section each include a crucible, a plating solution vapor nozzle, and a pipe for conveying plating solution vapor to the plating solution vapor nozzle.

5. The system as described in claim 1, characterized in that, The first cooling section and the second cooling section are equipped with cooling devices, which are selected from cooling rollers and radiation cooling devices; the cooling devices of the first cooling section and the second cooling section may be the same or different.

6. The system as described in claim 1, characterized in that, The first cooling section includes a first cooling roller that is in direct contact with the strip; and / or the second cooling section includes a second cooling roller that is in direct contact with the strip.

7. The system as described in claim 6, characterized in that, The first cooling roller is in contact with the second surface of the strip; the second cooling roller is in contact with the first surface of the strip.

8. The system as described in claim 1, characterized in that, The first cooling section includes a radiative cooling device; and / or the second cooling section includes a radiative cooling device.

9. A method for vacuum plating strip steel, characterized in that, It is implemented based on the system as described in any one of claims 1 to 6, and the method includes the step of: during the movement of the strip steel: In the first jet deposition section, the nozzles spray plating vapor onto the first surface of the strip steel so that the vapor is deposited on the first surface. The first cooling section cools the strip steel; The nozzles of the second jet deposition section spray plating vapor onto the second surface of the strip steel so that the vapor is deposited on the second surface. The second cooling section cools the strip steel.

10. The method as described in claim 9, characterized in that, Before the step of spraying plating solution vapor onto the first surface of the strip through the nozzle of the first jet deposition section, the strip surface is pretreated.

11. The method as described in claim 10, characterized in that, The process of pre-treating the strip surface also includes preheating the strip.

12. The method as described in claim 11, characterized in that, In the step of preheating the strip steel, the strip steel is preheated to 120-180℃.

13. The method as described in claim 9, characterized in that, The plating solution vapor is zinc vapor.

14. A coated steel strip, characterized in that, The coating is obtained by the method described in any one of claims 9-13.

15. The coated steel strip as described in claim 14, characterized in that, Its coating thickness is >10μm.

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