A zinc-aluminum-magnesium alloy coated steel plate for photovoltaics and its preparation method

Abstract

The present invention discloses a zinc-aluminum-magnesium alloy coated steel plate for photovoltaic use and a preparation method, which belongs to the technical field of hot-dip coating of photovoltaic steel plates. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium coated steel plate are: Al 5-9%, Mg 2.5-4.5%, Ni 0-0.15%, Ti 0-0.2%, and the rest are Zn and inevitable impurities. The process route of the preparation method is: hot-rolled or cold-rolled raw material plate - electrolytic cleaning section cleaning - non-oxidation horizontal modified Sendkimir process heating furnace annealing - electromagnetic induction alloy zinc pot coating - pure nitrogen air knife scraping excess steel liquid on the surface - post-plating cooling - smoothing - straightening - passivation - drying - electrostatic oiling - inspection, packaging and warehousing. The present invention makes full use of the technical means such as the role played by each alloy element in the new alloy system in the hot-dip coating process and the corrosion process, the reactions occurring, and the products obtained by the reactions to further improve the coating quality, wear resistance, corrosion resistance and other properties.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-dip plating of photovoltaic steel plates and relates to a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics and a preparation method thereof. Background Art

[0002] Photovoltaic power generation has become a green, low-carbon, and sustainable thermal power project. Since photovoltaic power stations are often built in complex environments such as deserts, mudflats, and sea surfaces, a highly corrosion-resistant and wear-resistant material with controllable environmental management is required as the structural support for photovoltaic power stations.

[0003] Zinc-aluminum-magnesium alloy coatings offer excellent protection for steel products, enhancing the corrosion resistance of steel components compared to pure zinc or zinc-aluminum alloy coatings. Furthermore, when zinc-aluminum-magnesium alloy-coated steel plates are used as structural supports for photovoltaic power stations, they are not only corrosion-resistant and wear-resistant but also possess exceptionally high self-healing capabilities, making them suitable for use in a variety of complex environments.

[0004] Although there are many existing methods for preparing zinc-aluminum-magnesium, these methods mainly achieve corresponding performance improvements by controlling the addition of alloying elements to optimize the element distribution, grain size and phase structure of the coating.

[0005] Chinese patent CN111534777A discloses a hot-dip galvanized aluminum-magnesium coated steel plate with notch corrosion resistance and a preparation method thereof, wherein the chemical composition mass fraction of the coating is: Al: 2-12wt.%, Mg: 1-4%wt.%, and the rest is Zn and unavoidable impurities; but its technical content only focuses on the corrosion resistance of the notch position, and does not involve further improvement of its wear resistance and corrosion resistance.

[0006] Chinese patent CN112575273A discloses a medium-aluminum zinc-aluminum-magnesium coated steel sheet with excellent coating plasticity and a production method. By adding Nb: 0.01-0.05wt.%, Cr: 0.01-0.05%wt.% and / or Cu: 0.01-0.05wt.% to the medium-aluminum zinc-aluminum-magnesium coating, a medium-aluminum zinc-aluminum-magnesium coated steel sheet with excellent coating plasticity is obtained; therefore, its production process adopts chemical + electrolytic degreasing to pretreat the cold-rolled steel sheet, its production process is long, the efficiency is low, and the impact on the environment is large, and the composition selection of the steel sheet substrate is not given. If the steel sheet has a high silicon content, there will be the generation of the Sandelin effect during the immersion plating of the silicon-containing steel, and further improvement of hardness, wear resistance and corrosion resistance is not considered.

[0007] Chinese patent CN106222593A improves the corrosion resistance of a zinc-aluminum-magnesium coating by adding Si, Ni, and Ce. However, the results show that the improvement in corrosion resistance is primarily due to the addition of Si and an increase in Al content. However, increasing Si and Al content also increases the brittleness of the coating. Furthermore, while the rare earth elements Ce and Ni can improve corrosion resistance to a certain extent, they are expensive. Similarly, Chinese patent CN113737117A discloses a hot-dip zinc-aluminum-magnesium alloy coated steel sheet and preparation method. Similar to the aforementioned patent, increasing Si content in the aforementioned patent increases the likelihood of the Sandelin effect occurring during the immersion plating of silicon-containing steel.

[0008] Chinese patent CN110358998A discloses an aluminum-zinc-magnesium coated steel plate and a preparation method thereof, wherein the cost of adding alloy elements is high, and the Sr content in the inhibition layer is lower than the Sr content in the parent layer, which has little effect on further improving the hardness, wear resistance and corrosion resistance of the coating.

[0009] Chinese patent CN111850447A discloses a high-performance zinc-aluminum-magnesium coated steel sheet and a preparation method thereof. By utilizing the modification effect of metal oxides on the alloy coating, a zinc-aluminum-magnesium alloy coating with good wear resistance is obtained. However, since the distribution of nano-scale oxides in the coating is difficult to control, this method is very difficult to implement.

[0010] Chinese patents CN114107868A and CN111270184A disclose a zinc-aluminum-magnesium alloy coated steel and a preparation method thereof. Obviously, the content of aluminum alloy elements is selected to be quite high, and the addition of trace alloying elements and rare earth elements increases the cost. The phase structure and performance of the prepared coating are difficult to achieve further improvement in hardness, wear resistance and corrosion resistance. Summary of the Invention

[0011] The technical problem to be solved by the present invention is how to overcome the technical defects in the prior art, such as the relatively low hardness of the hot-dip galvanized aluminum-magnesium coating, the fluidity and corrosion resistance of the plating solution, the high cost of the added alloying elements, the increased Si content which increases the probability of the Sandelin effect during the immersion plating of silicon-containing steel, the relatively low improvement in the hardness, wear resistance and corrosion resistance of the coating caused by the addition of alloying elements, and the poor control of the phase structure and grain size.

[0012] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0013] A zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics, wherein the chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 5-9%, Mg 2.5-4.5%, Ni 0-0.15%, Ti 0-0.2%, and the remainder is Zn and unavoidable impurities; the mass percentage of Ni and the mass percentage of Ti cannot be zero.

[0014] Preferably, the thickness of the steel plate is 0.75-4 mm, the thickness of the coating is 10-60 μm, and the density of the coating is 5.6-6.2 g / cm 3 The hardness of the coating is 130-180HV, and the time for 5% red rust to appear on the steel plate is 2830-3880h.

[0015] Preferably, the quality control of the coating on one side is 40-300g / m 2 The phase structure of the coating is composed of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0016] Preferably, the steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a hot-rolled or cold-rolled raw material plate; wherein: the chemical composition and mass percentage content of the hot-rolled substrate are: C 0.07-0.09%, Si 0.05-0.15%, Mn 0.9-1.5%, and the rest are Fe and inevitable impurities; the chemical composition and mass percentage content of the cold-rolled substrate are: C 0.07-0.18%, Si 0.05-0.08%, Mn 0.8-1.1%, and the rest are Fe and inevitable impurities.

[0017] A preparation method for the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is disclosed. The preparation method adopts a modified Sendzimir process for hot-dip plating production, and the process route is: hot-rolling or cold-rolling raw material plate - electrolytic cleaning section cleaning - non-oxidation horizontal modified Sendzimir heating furnace annealing - electromagnetic induction alloy zinc pot coating - pure nitrogen air knife scraping excess steel liquid on the surface - post-plating cooling - skin finishing - straightening - passivation - drying - electrostatic oiling - inspection, packaging and warehousing.

[0018] Preferably, the annealing in the non-oxidizing horizontal modified Sendkimier process heating furnace is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section and a jet cooling section, and the total annealing time is 50-180s; wherein: the temperature of the direct flame section is 1100-1260°C, and the time is 12-55s; the temperature of the radiant tube heating section is 950-1150°C, and the time is 15-50s; the temperature of the radiant tube soaking section is 900-920°C, and the time is 12-55s; the temperature of the jet cooling section is 480-520°C, and the cooling rate of the strip during the jet process is 22-35°C / s, and the time is 11-20s.

[0019] Preferably, the protective atmosphere in the non-oxidizing horizontal modified Sendkimier process heating furnace for annealing is N2+H2, and the volume fraction of H2 is controlled to be 7-15%; the oxygen content is lower than 5ppm, and the dew point is -60°C.

[0020] Preferably, the temperature of the alloy zinc pot in the electromagnetic induction alloy zinc pot coating is 500±20°C, the temperature of the strip when entering the alloy zinc pot should be consistent with the temperature of the alloy zinc pot, and the immersion plating time is 2-8s.

[0021] Preferably, the cooling rate of the steel plate after plating is 10-30°C / s.

[0022] Preferably, skin-passing-stretching-passivation-drying-electrostatic oiling refers to using a skin-passing machine to skin-pass the cooled alloy-coated steel plate; using a straightening machine to straighten the alloy-coated steel plate after skin-passing; using a passivation coating machine to passivate the alloy-coated steel plate after straightening; drying the alloy-coated steel plate after passivation; and electrostatic oiling the alloy-coated steel plate after drying.

[0023] The functions of the chemical elements in the zinc-aluminum-magnesium alloy coated steel plate coating of the present invention are as follows:

[0024] The present invention controls the aluminum element to be between 5-9wt.%, and Al has good corrosion resistance. When added to the coating, this element can form protective corrosion products Zn2Al(OH)6(CO3) during the corrosion process of the coating. 1 / 2 xH2O. By controlling the Al content to no more than 10 wt.%, the formation of the Fe-Al alloy layer is suppressed, thereby increasing the adhesion between the coating and the steel sheet.

[0025] The addition of alloying element Mg causes the appearance of intermetallic compound MgZn2 and Zn / Al / MgZn2 ternary eutectic phase in the solidified structure of the coating, and forms protective corrosion product Mg6Al2(OH) in the subsequent corrosion process. 16 CO3·4H2O, and the Mg element also helps increase the hardness and wear resistance of the coating. By controlling the Mg content between 2.5-4.5wt.%, not only can the coating solidification structure have the best density, thus achieving the best corrosion resistance, but it can also prevent surface quality defects such as plating leakage caused by excessive Mg content.

[0026] The addition of Ni element can effectively inhibit the formation of brittle alloy layer on the surface of steel plate during immersion plating, thereby increasing the corrosion resistance of alloy-coated steel plate. It can also increase the fluidity of the plating solution and inhibit the generation of Sandelin effect during immersion plating of silicon-containing steel, thereby improving the surface quality of alloy-coated steel plate.

[0027] The addition of Ti not only increases the hardness of the coating but also provides heterogeneous nucleation sites during the solidification process of the alloy coating, thereby refining the grain size of the coating and improving the corrosion resistance of the alloy coating. Since zinc-aluminum-magnesium alloy-coated steel sheets for photovoltaic applications are often subject to erosion and wear from wind, sand, and water flow during service, the increased number of grain boundaries inhibits crack propagation, thereby improving the wear resistance of the alloy coating.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] In the above scheme, the present invention controls the element selection and content of Al, Mg, Ni, and Ti, and improves the preparation method, so that the zinc-aluminum-magnesium alloy coated steel plate for photovoltaic use is uniformly coated, and the adhesion of the steel plate and the erosion and wear resistance in the service environment are significantly improved, thereby avoiding possible technical shortcomings.

[0030] Trace amounts of Ni and Ti elements are added to the medium-aluminum zinc-aluminum-magnesium coating of the present invention, and the coated steel plate has high corrosion resistance and hardness. The grain refinement also enhances the ability to resist erosion and wear when encountering wind, sand, and water flow, which helps to solve the problems of short service life and rapid failure of zinc-aluminum-magnesium coated steel plates for photovoltaics in harsh service environments.

[0031] The thickness of the steel plate of the present invention is 0.75-4 mm, the thickness of the coating is 10-60 μm, and the density of the coating is 5.6-6.2 g / cm 3 The hardness of the coating is 130-180HV, and the time for 5% red rust to appear on the steel plate is 2830-3880h.

[0032] The quality control of the coating on one side of the present invention is 40-300g / m 2 The phase structure of the coating is composed of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0033] In summary, the coating performance of the present invention is excellent. By adding low-cost alloying elements and coordinating with the hot-dip plating process on the basis of the original medium-aluminum zinc-aluminum-magnesium coating, the role and reaction of each alloying element in the new alloy system during the hot-dip plating process and the corrosion process, the products obtained by the reaction and other technical means are fully utilized to further improve the coating quality, wear resistance and corrosion resistance. The process is conducive to large-scale industrial production and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 This is a metallographic diagram of a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to Example 1 of the present invention;

[0036] Figure 2 This is a metallographic image of a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to Example 2 of the present invention;

[0037] Figure 3 This is a metallographic diagram of a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to Example 3 of the present invention;

[0038] Figure 4 This is a metallographic diagram of a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to Example 4 of the present invention;

[0039] Figure 5 This is a metallographic diagram of a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to Example 5 of the present invention;

[0040] Figure 6 This is a metallographic diagram of a zinc-aluminum-magnesium alloy-coated steel sheet for photovoltaic use according to Example 6 of the present invention;

[0041] Figure 7 This is a metallographic diagram of a zinc-aluminum-magnesium alloy-coated steel sheet for photovoltaic use according to Example 7 of the present invention;

[0042] Figure 8 This is a metallographic image of a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to Example 8 of the present invention;

[0043] Figure 9 This is a metallographic image of a zinc-aluminum-magnesium alloy-coated steel sheet for photovoltaic use according to Example 9 of the present invention;

[0044] Figure 10 This is a metallographic diagram of a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to Example 10 of the present invention. DETAILED DESCRIPTION

[0045] The following will describe the technical solutions and technical problems solved in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them.

[0046] Example 1

[0047] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 6.0%, Mg 3.0%, Ni 0.01%, Ti 0.01%, and the rest are Zn and unavoidable impurities.

[0048] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a hot-rolled raw material plate; wherein: the chemical composition and mass percentage content of the hot-rolled substrate are: C 0.08%, Si 0.13%, Mn 1.2%, and the rest are Fe and unavoidable impurities.

[0049] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0050] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0051] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 69 seconds; wherein: the temperature of the direct flame section is 1150°C, and the annealing time is 12.5 seconds; the temperature of the radiant tube heating section is 1000°C, and the annealing time is 24 seconds; the temperature of the radiant tube soaking section is 920°C, and the annealing time is 20 seconds; the temperature of the air jet cooling section is 482.5°C, and the strip cooling rate during the air jet process is 35°C / s, and the annealing time is 12.5 seconds;

[0052] S3: The annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 80g / m 2 , obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, with the volume fraction of H2 controlled to be 11%; the oxygen content is less than 5ppm, and the dew point is -60°C; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 480°C, and the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature; the immersion time is 4.2s;

[0053] S4, scraping excess molten steel from the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 12°C / s to obtain a cooled coated steel plate;

[0054] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0055] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0056] The thickness of the steel plate entering the warehouse is 0.75mm, the thickness of the coating on one side is 11μm, and the density of the coating is 5.99g / cm 3 The hardness of the coating is 146HV, and the time for 5% red rust to appear on the steel plate is 2844h.

[0057] like Figure 1 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0058] Example 2

[0059] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 6.0%, Mg 3.0%, Ni 0.01%, Ti 0.05%, and the rest are Zn and unavoidable impurities.

[0060] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a hot-rolled raw material plate; wherein: the chemical composition and mass percentage content of the hot-rolled substrate are: C 0.08%, Si 0.09%, Mn 1.0%, and the rest are Fe and unavoidable impurities.

[0061] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0062] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0063] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 135 seconds; wherein: the temperature of the direct flame section is 1150°C, and the annealing time is 40 seconds; the temperature of the radiant tube heating section is 1000°C, and the annealing time is 38 seconds; the temperature of the radiant tube soaking section is 920°C, and the annealing time is 42 seconds; the temperature of the air jet cooling section is 500°C, and the strip cooling rate during the air jet process is 28°C / s, and the annealing time is 15 seconds;

[0064] S3, the annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 200g / m 2, obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, the volume fraction of H2 is controlled to be 12%; the oxygen content is less than 5ppm, and the dew point is -60℃; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 500℃, the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature, and the immersion time is 5s;

[0065] S4, scraping excess molten steel from the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 20°C / s to obtain a cooled coated steel plate;

[0066] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0067] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0068] The thickness of the steel plate entering the warehouse is 2.8mm, the thickness of the coating on one side is 33μm, and the density of the coating is 5.98g / cm 3 The hardness of the coating is 151HV, and the time for 5% red rust to appear on the steel plate is 3753h.

[0069] like Figure 2 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0070] Example 3

[0071] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 6.0%, Mg 3.0%, Ni 0.05%, Ti 0.01%, and the rest are Zn and unavoidable impurities.

[0072] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a cold-rolled raw material plate; wherein: the chemical composition and mass percentage content of the cold-rolled substrate are: C 0.12%, Si 0.06%, Mn 0.8%, and the rest are Fe and unavoidable impurities.

[0073] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0074] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0075] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 154 seconds; wherein: the direct flame section temperature is 1200°C, the annealing time is 48 seconds; the radiant tube heating section temperature is 1100°C, the annealing time is 42 seconds; the radiant tube soaking section temperature is 920°C, the annealing time is 50 seconds; the air jet cooling section temperature is 500°C, the strip cooling rate during the air jet process is 30°C / s, and the annealing time is 14 seconds;

[0076] S3: The annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 180g / m 2 , obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, with the volume fraction of H2 controlled to be 9%; the oxygen content is less than 5ppm, and the dew point is -60°C; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 510°C, and the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature; the immersion time is 7.4s;

[0077] S4, scraping excess molten steel from the surface of the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 16°C / s to obtain a cooled coated steel plate;

[0078] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0079] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0080] The thickness of the steel plate entering the warehouse is 3.25mm, the thickness of the coating on one side is 30μm, and the density of the coating is 5.99g / cm 3 The hardness of the coating is 144HV, and the time for 5% red rust to appear on the steel plate is 3861h.

[0081] like Figure 3As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0082] Example 4

[0083] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 6.0%, Mg 3.0%, Ni 0.05%, Ti 0.05%, and the rest are Zn and unavoidable impurities.

[0084] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a cold-rolled raw material plate; wherein: the chemical composition and mass percentage content of the cold-rolled substrate are: C 0.18%, Si 0.08%, Mn 0.8%, and the rest are Fe and unavoidable impurities.

[0085] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0086] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0087] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 84 seconds; wherein: the temperature of the direct flame section is 1180°C, and the annealing time is 18 seconds; the temperature of the radiant tube heating section is 1100°C, and the annealing time is 26 seconds; the temperature of the radiant tube soaking section is 920°C, and the annealing time is 26 seconds; the temperature of the air jet cooling section is 500°C, and the strip cooling rate during the air jet process is 30°C / s, and the annealing time is 14 seconds;

[0088] S3: The annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 142g / m 2 , obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, with the volume fraction of H2 controlled at 15%; the oxygen content is less than 5ppm, and the dew point is -60°C; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 510°C, and the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature; the immersion time is 8s;

[0089] S4, scraping excess molten steel from the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 25°C / s to obtain a cooled coated steel plate;

[0090] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0091] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0092] The thickness of the steel plate entering the warehouse is 1.40mm, the thickness of the coating on one side is 23.7μm, and the density of the coating is 5.99g / cm 3 The hardness of the coating is 158HV, and the time for 5% red rust to appear on the steel plate is 3580h.

[0093] like Figure 4 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0094] Example 5

[0095] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 6.0%, Mg 3.0%, Ni 0.10%, Ti 0.10%, and the rest are Zn and unavoidable impurities.

[0096] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a cold-rolled raw material plate; wherein: the chemical composition and mass percentage content of the cold-rolled substrate are: C 0.16%, Si 0.06%, Mn 1.1%, and the rest are Fe and unavoidable impurities.

[0097] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0098] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0099] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 180 seconds; wherein: the temperature of the direct flame section is 1260°C, and the annealing time is 55 seconds; the temperature of the radiant tube heating section is 1150°C, and the annealing time is 50 seconds; the temperature of the radiant tube soaking section is 920°C, and the annealing time is 55 seconds; the temperature of the air jet cooling section is 480°C, and the cooling rate of the strip during the air jet process is 22°C / s, and the annealing time is 20 seconds;

[0100] S3, the annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 300g / m 2 , obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, with the volume fraction of H2 controlled to be 8%; the oxygen content is less than 5ppm, and the dew point is -60°C; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 520°C, and the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature; the immersion time is 8s;

[0101] S4, scraping excess molten steel from the surface of the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 13°C / s to obtain a cooled coated steel plate;

[0102] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0103] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0104] The thickness of the steel plate entering the warehouse is 4.0mm, the thickness of the coating on one side is 48.9μm, and the density of the coating is 5.98g / cm 3 The hardness of the coating is 160HV, and the time for 5% red rust to appear on the steel plate is 4233h.

[0105] like Figure 5 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0106] Example 6

[0107] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 5.0%, Mg 2.5%, Ni 0.05%, Ti 0.01%, and the rest are Zn and unavoidable impurities.

[0108] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a hot-rolled raw material plate; wherein: the chemical composition and mass percentage content of the hot-rolled substrate are: C 0.07%, Si 0.08%, Mn 0.9%, and the rest are Fe and unavoidable impurities.

[0109] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0110] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0111] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 86 seconds; wherein: the temperature of the direct flame section is 1100° C., and the annealing time is 25 seconds; the temperature of the radiant tube heating section is 980° C., and the annealing time is 22 seconds; the temperature of the radiant tube soaking section is 910° C., and the annealing time is 25 seconds; the temperature of the air jet cooling section is 490° C., and the strip cooling rate during the air jet process is 30° C. / s, and the annealing time is 14 seconds;

[0112] S3, the annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 100g / m 2 , obtaining a coated steel plate; wherein: the protective atmosphere in the furnace is N2+H2, with the H2 volume fraction controlled at 13%; the oxygen content is less than 5ppm, and the dew point is -60°C; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 490°C, and the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature; the immersion time is 3.6s;

[0113] S4, scraping excess molten steel from the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 23°C / s to obtain a cooled coated steel plate;

[0114] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0115] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0116] The thickness of the steel plate entering the warehouse is 1.0mm, the thickness of the coating on one side is 16.3μm, and the density of the coating is 6.15g / cm 3 The hardness of the coating is 143HV, and the time for 5% red rust to appear on the steel plate is 2861h.

[0117] like Figure 6 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0118] Example 7

[0119] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 5.0%, Mg 2.5%, Ni 0.15%, Ti 0.20%, and the rest are Zn and unavoidable impurities.

[0120] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a cold-rolled raw material plate; wherein: the chemical composition and mass percentage content of the cold-rolled substrate are: C 0.12%, Si 0.06%, Mn 1.0%, and the rest are Fe and unavoidable impurities.

[0121] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0122] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0123] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 150 seconds; wherein: the temperature of the direct flame section is 1250°C, and the annealing time is 48 seconds; the temperature of the radiant tube heating section is 1080°C, and the annealing time is 37 seconds; the temperature of the radiant tube soaking section is 920°C, and the annealing time is 45 seconds; the temperature of the air jet cooling section is 480°C, and the cooling rate of the strip during the air jet process is 22°C / s, and the annealing time is 20 seconds;

[0124] S3: The annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 160g / m 2 , obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, with the volume fraction of H2 controlled to be 12%; the oxygen content is less than 5ppm, and the dew point is -60°C; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 500°C, and the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature; the immersion time is 6s;

[0125] S4, scraping excess molten steel from the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 20°C / s to obtain a cooled coated steel plate;

[0126] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0127] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0128] The thickness of the steel plate entering the warehouse is 2.85mm, the thickness of the coating on one side is 26.3μm, and the density of the coating is 6.15g / cm 3 The hardness of the coating is 157HV, and the time for 5% red rust to appear on the steel plate is 3617h.

[0129] like Figure 7 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0130] Example 8

[0131] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 7.0%, Mg 3.0%, Ni 0.05%, Ti 0.101%, and the rest are Zn and unavoidable impurities.

[0132] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a hot-rolled raw material plate; wherein: the chemical composition and mass percentage content of the hot-rolled substrate are: C 0.09%, Si 0.14%, Mn 0.9%, and the rest are Fe and unavoidable impurities.

[0133] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0134] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0135] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 158 seconds; wherein: the direct flame section is at a temperature of 1120°C for 50 seconds; the radiant tube heating section is at a temperature of 850°C for 50 seconds; the radiant tube soaking section is at a temperature of 910°C for 46 seconds; the air jet cooling section is at a temperature of 520°C, the strip cooling rate during the air jet process is 32°C / s, and the time is 12 seconds;

[0136] S3, the annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 200g / m 2 , obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, with the volume fraction of H2 controlled to be 7%; the oxygen content is less than 5ppm, and the dew point is -60°C; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 480°C, and the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature; the immersion time is 2s;

[0137] S4, scraping excess molten steel from the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 10°C / s to obtain a cooled coated steel plate;

[0138] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0139] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0140] The thickness of the steel plate entering the warehouse is 3.25mm, the thickness of the coating on one side is 28.1μm, and the density of the coating is 5.91g / cm 3 The hardness of the coating is 162HV, and the time for 5% red rust to appear on the steel plate is 3492h.

[0141] like Figure 8 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0142] Example 9

[0143] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 8.0%, Mg 4.0%, Ni 0.01%, Ti 0.05%, and the rest are Zn and unavoidable impurities.

[0144] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a hot-rolled raw material plate; wherein: the chemical composition and mass percentage content of the hot-rolled substrate are: C 0.08%, Si 0.08%, Mn 1.2%, and the rest are Fe and unavoidable impurities.

[0145] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0146] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0147] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 150 seconds; wherein: the temperature of the direct flame section is 1160°C, and the annealing time is 52 seconds; the temperature of the radiant tube heating section is 1000°C, and the annealing time is 46 seconds; the temperature of the radiant tube soaking section is 920°C, and the annealing time is 38 seconds; the temperature of the air jet cooling section is 510°C, and the strip cooling rate during the air jet process is 29°C / s, and the annealing time is 14 seconds;

[0148] S3, the annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 200g / m 2 , obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, with the volume fraction of H2 controlled at 15%; the oxygen content is less than 5ppm, and the dew point is -60°C; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 490°C, and the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature; the immersion time is 4s;

[0149] S4, scraping excess molten steel from the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 30°C / s to obtain a cooled coated steel plate;

[0150] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0151] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0152] The thickness of the steel plate entering the warehouse is 3.27mm, the thickness of the coating on one side is 35.1μm, and the density of the coating is 5.68g / cm 3 The hardness of the coating is 168HV, and the time for 5% red rust to appear on the steel plate is 3540h.

[0153] like Figure 9 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0154] Example 10

[0155] This example is a zinc-aluminum-magnesium alloy-coated steel plate for photovoltaics. The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium alloy-coated steel plate are: Al 9.0%, Mg 3.0%, Ni 0.05%, Ti 0.10%, and the rest are Zn and unavoidable impurities.

[0156] The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a hot-rolled raw material plate; wherein: the chemical composition and mass percentage content of the hot-rolled substrate are: C 0.09%, Si 0.05%, Mn 1.4%, and the rest are Fe and unavoidable impurities.

[0157] A preparation method of the photovoltaic zinc-aluminum-magnesium alloy coated steel sheet is provided, wherein the preparation method adopts the modified Sendzimir process for hot-dip coating production, and the process steps are as follows:

[0158] S1. The hot-rolled or cold-rolled raw material plate is cleaned in an electrolytic cleaning section to obtain a steel plate with a clean surface;

[0159] S2. Annealing the steel plate obtained in step S1 in a non-oxidizing horizontal modified Sendkimer process heating furnace to obtain an annealed steel plate; wherein the non-oxidizing horizontal modified Sendkimer process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section, and an air jet cooling section, and the total annealing time is 50 seconds; wherein: the temperature of the direct flame section is 1150° C., the time is 12 seconds; the temperature of the radiant tube heating section is 1020° C., the time is 15 seconds; the temperature of the radiant tube soaking section is 900° C., the time is 12 seconds; the temperature of the air jet cooling section is 480° C., the cooling rate of the strip during the air jet process is 35° C. / s, and the time is 12 seconds;

[0160] S3, the annealed steel sheet in step S2 is plated in an electromagnetic induction alloy zinc pot, and the quality of the coating on one side is controlled to be 100g / m 2 , obtaining a steel plate with a coating; wherein: the protective atmosphere in the furnace is N2+H2, the volume fraction of H2 is controlled to be 9%; the oxygen content is less than 5ppm, and the dew point is -60℃; the alloy zinc pot temperature in the electromagnetic induction alloy zinc pot coating is 500℃, the temperature of the steel strip entering the alloy zinc pot should be consistent with the alloy zinc pot temperature, and the immersion time is 5s;

[0161] S4, scraping excess molten steel from the steel plate with the coating in step S3 with a pure nitrogen air knife, and then performing post-coating cooling at a cooling rate of 14°C / s to obtain a cooled coated steel plate;

[0162] S5, sequentially performing skin pass-through, straightening, passivation, drying, and electrostatic oiling on the cooled coated steel plate in step S4 to obtain a treated steel plate; wherein the cooled alloy coated steel plate is skin pass-through treated by a skin pass-through mill; the skin pass-through treated alloy coated steel plate is straightened by a straightening mill; the straightening treated alloy coated steel plate is passivated by a passivation coating machine; the passivated alloy coated steel plate is dried; and the dried alloy coated steel plate is electrostatically oiled for protection;

[0163] S6. The steel plates processed in step S5 are inspected, packaged and then put into storage.

[0164] The thickness of the steel plate entering the warehouse is 1.2mm, the thickness of the coating on one side is 23.8μm, and the density of the coating is 5.75g / cm 3 The hardness of the coating is 174HV, and the time for 5% red rust to appear on the steel plate is 3392h.

[0165] like Figure 10 As shown, the phase structure of the coating consists of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0166] In the above scheme, the present invention controls the element selection and content of Al, Mg, Ni, and Ti, and improves the preparation method, so that the zinc-aluminum-magnesium alloy coated steel plate for photovoltaic use is uniformly coated, and the adhesion of the steel plate and the erosion and wear resistance in the service environment are significantly improved, thereby avoiding possible technical shortcomings.

[0167] Trace amounts of Ni and Ti elements are added to the medium-aluminum zinc-aluminum-magnesium coating of the present invention, and the coated steel plate has high corrosion resistance and hardness. The grain refinement also enhances the ability to resist erosion and wear when encountering wind, sand, and water flow, which helps to solve the problems of short service life and rapid failure of zinc-aluminum-magnesium coated steel plates for photovoltaics in harsh service environments.

[0168] The thickness of the steel plate of the present invention is 0.75-4 mm, the thickness of the coating is 10-60 μm, and the density of the coating is 5.6-6.2 g / cm 3 The hardness of the coating is 130-180HV, and the time for 5% red rust to appear on the steel plate is 2830-3880h.

[0169] The quality control of the coating on one side of the present invention is 40-300g / m 2 The phase structure of the coating is composed of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

[0170] In summary, the coating performance of the present invention is excellent. By adding low-cost alloying elements and coordinating with the hot-dip plating process on the basis of the original medium-aluminum zinc-aluminum-magnesium coating, the role and reaction of each alloying element in the new alloy system during the hot-dip plating process and the corrosion process, the products obtained by the reaction and other technical means are fully utilized to further improve the coating quality, wear resistance and corrosion resistance. The process is conducive to large-scale industrial production and promotion.

[0171] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use, characterized in that: The chemical composition and mass percentage of the zinc-aluminum-magnesium alloy coating of the zinc-aluminum-magnesium coated steel plate are: Al 5-9%, Mg 2.5-4.5%, Ni 0-0.15%, Ti 0-0.2%, and the remainder is Zn and unavoidable impurities; the mass percentage of Ni and the mass percentage of Ti cannot be zero; The thickness of the steel plate is 0.75-4 mm, the thickness of the coating is 10-60 μm, and the density of the coating is 5.6-6.2 g / cm 3 The hardness of the coating is 130-180HV, and the time for 5% red rust to appear on the steel plate is 2830-3880h; The quality control of the coating on one side is 40-300g / m 2 The phase structure of the coating is composed of pure zinc + MgZn2 + Zn / MgZn2 binary eutectic + Zn / MgZn2 / Al ternary eutectic.

2. The zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to claim 1, characterized in that: The steel plate substrate in the zinc-aluminum-magnesium coated steel plate is a hot-rolled or cold-rolled raw material plate; the chemical composition and mass percentage content of the hot-rolled substrate are: C 0.07-0.09%, Si 0.05-0.15%, Mn 0.9-1.5%, and the remainder is Fe and inevitable impurities; the chemical composition and mass percentage content of the cold-rolled substrate are: C 0.07-0.18%, Si 0.05-0.08%, Mn 0.8-1.1%, and the remainder is Fe and inevitable impurities.

3. A method for preparing a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to any one of claims 1-2, characterized in that: The preparation method adopts the modified Sendzimir process for hot-dip plating production, and its process route is: hot rolling or cold rolling raw material plate - cleaning in an electrolytic cleaning section - annealing in a non-oxidizing horizontal modified Sendzimir process heating furnace - electromagnetic induction alloy zinc pot coating - scraping excess steel liquid on the surface with a pure nitrogen air knife - post-plating cooling - skin finishing - straightening - passivation - drying - electrostatic oiling - inspection, packaging and warehousing.

4. The method for preparing a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to claim 3, characterized in that: The non-oxidizing horizontal improved Sendkimir process heating furnace annealing is divided into a preheating section, a direct flame section, a radiant tube heating section, a radiant tube soaking section and an air jet cooling section, and the total annealing time is 50-180s; wherein: the temperature of the direct flame section is 1100-1260°C, and the time is 12-55s; the temperature of the radiant tube heating section is 950-1150°C, and the time is 15-50s; the temperature of the radiant tube soaking section is 900-920°C, and the time is 12-55s; the temperature of the air jet cooling section is 480-520°C, and the cooling rate of the strip during the air jet process is 22-35°C / s, and the time is 11-20s.

5. The method for preparing a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to claim 3, characterized in that: The protective atmosphere in the non-oxidizing horizontal modified Sendkimier process heating furnace for annealing is N2+H2, with the volume fraction of H2 controlled to be 7-15%; the oxygen content is lower than 5ppm, and the dew point is -60°C.

6. The method for preparing a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to claim 3, characterized in that: The temperature of the alloy zinc pot in electromagnetic induction alloy zinc pot coating is 500±20℃. The temperature of the strip when entering the alloy zinc pot should be consistent with the temperature of the alloy zinc pot. The immersion time is 2-8s.

7. The method for preparing a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to claim 3, characterized in that: The cooling rate of the steel plate after plating is 10-30℃ / s.

8. The method for preparing a zinc-aluminum-magnesium alloy coated steel sheet for photovoltaic use according to claim 3, characterized in that: Skin finishing - straightening - passivation - drying - electrostatic oiling refers to the use of a skin finishing machine to skin finish the cooled alloy-coated steel plate; the use of a straightening machine to straighten the alloy-coated steel plate after skin finishing; the use of a passivation coating machine to passivate the alloy-coated steel plate after straightening; the drying of the passivated alloy-coated steel plate; and the electrostatic oiling of the dried alloy-coated steel plate.

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