JP2019502820A - Metal coating method for steel plate and metal coated steel plate manufactured using the same - Google Patents

Abstract

  The present invention relates to a metal coating method for a steel plate and a metal coated steel plate produced using the same, a step of heating the first metal powder below the softening point, a step of heating the gas at a temperature of 200 to 600 ° C., A metal coating of a steel sheet, comprising: forming a metal coating layer by vacuum spraying a heated metal powder together with a heated gas; and forming a second metal plating layer on the metal coating layer Methods and metal coated steel plates produced by such methods are provided.

Description

  The present invention relates to a metal coating method for a steel sheet and a metal coated steel sheet manufactured using the same, and more specifically, after forming a porous coating layer by vacuum spray coating, forming a plating layer, thereby forming voids. The present invention relates to a method for forming a non-coating layer and a steel sheet on which such a coating layer is formed.

  The particle coating method is used as a surface treatment method for coating various powder materials on the surface of various materials. Usually, the injection speed is realized by the gas pressure difference between the coating section bordering the nozzle and the powder transfer gas. . The particle coating means that the material to be coated is in a particle state, and particles having a size of several hundred to several tens of nanometers (nm) collide with the material at a high speed and are coated. It is characterized in that it is very fast compared with PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), etc., which are coated in atomic and molecular units, and the chemical composition of the raw material powder does not change.

  Examples of the particle coating method include a thermal spray method (Thermal spray, Cold spray, etc.), a vacuum spray method, and the like. These are usually useful methods for coating solid powders such as metals, alloys, ceramics, cermets, etc., where temperature and spray rate are very important factors.

  The vacuum injection method employs a method of maintaining the pressure of the coating part in a vacuum (low pressure) in order to realize a pressure difference. That is, coating is performed by providing a member to be coated inside the vacuum body, and spraying the powder onto the member to be coated on the flow of the transfer gas. Since this method does not require a high pressure of the transfer gas, the amount of gas consumed is very small compared to the thermal spray method, and it is not necessary to heat the gas to form a high-pressure gas. There is an advantage that is possible.

  In order to apply this particle coating method to the steel industry such as surface treatment of steel sheets, mass production (coating efficiency) and economy (gas consumption) should be considered. From this point of view, the vacuum injection method is economical because it consumes less gas, but the coating temperature is close to room temperature, and the powder particle injection speed is slower than the thermal spray method. Coating efficiency (lamination amount / total injection amount) is low, and there is a limit in coating materials.

  As disclosed in Korean Patent Application No. 2008-0076019, the vacuum injection method is generally used for a brittle material such as ceramic, in which the powder particles are crushed during the coating process, and then the coating is performed by recombination of the crushed particles. It is generally used for coating, and is not suitable for coating of a soft material that requires high energy for plastic deformation, such as metal.

On the other hand, the particle coating method by the thermal spraying method has high coating efficiency of metal powder, but the main body provided with the member to be coated is under normal pressure conditions, and in order to increase the pressure difference from normal pressure, the powder transfer gas As a high pressure gas of several MPa level is used. Therefore, there is a drawback that the gas consumption is very large. In addition, there is a problem that an expensive gas such as He or N ₂ having a low density must be used in order for the member to be coated to realize a particle velocity for high-speed collision under normal pressure conditions. That is, such a thermal spraying method is generally used for coating of a small area, and due to the problem of air resistance under normal pressure conditions, a particle size of several tens of μm level is necessary for high-speed spraying. However, due to problems such as coating layer defects and residual stress, it is necessary to form a thick film coating with a thickness of several tens to several hundreds of μm. There is a problem that it is difficult. In general, in such a particle coating method for coating a metal powder, voids are formed in the coating layer. Especially, when coating a thin film of several to several tens of μm, the voids serve as a penetration path for corrosion factors. It acts and causes the corrosion resistance of the steel sheet material to decrease.

  Therefore, when forming a metal film on the surface of a steel plate to maximize the functionality of a metal coating layer such as corrosion resistance, a coating method is provided in which the problems of the above-described spraying method and vacuum spraying method are eliminated. If so, it is expected to be widely applicable in related fields.

  The objective of this invention is providing the metal coating method of the steel plate which can form the coating layer without a space | gap.

  Another object of the present invention is to provide a metal-coated steel sheet comprising a coating layer formed so as not to have voids by the metal coating method of the present invention.

  According to the knowledge of the present invention, the step of heating the first metal powder at a temperature not lower than the normal temperature and lower than the softening point, the step of heating the gas at a temperature of 200 to 600 ° C., and the heated metal powder together with the heated gas Forming a porous first metal coating layer by vacuum spraying; and forming a second metal plating layer in a gap between powders forming the first metal coating layer. A method is provided.

  The first metal is copper (Cu), aluminum (Al), zinc (Zn), iron (Fe), nickel (Ni), chromium (Cr), molybdenum (Mo), titanium (Ti), cobalt (Co). It is preferable that at least one metal selected from the group consisting of manganese (Mn), tungsten (W), zirconium (Zr), and tin (Sn) is included.

  The first metal powder preferably has an average particle size of 1 to 20 μm.

The gas is preferably at least one gas selected from the group consisting of nitrogen (N ₂ ), helium (He), and air having a density equal to or lower than air.

  The vacuum injection is preferably performed at a pressure of 0.01 to 20 Torr.

  The vacuum injection is preferably performed in a temperature range of 10 to 200 ° C. in a vacuum chamber.

  The second metal preferably includes at least one metal selected from the group consisting of zinc (Zn), nickel (Ni), tin (Sn), copper (Cu), and chromium (Cr).

  The step of forming the second metal plating layer is preferably performed by an electroplating method or an electroless plating method.

  Preferably, the metal coating method for the steel sheet further includes a step of polishing the second metal plating layer.

  The metal coating method for the steel sheet preferably further includes a step of heat-treating at a temperature of 200 to 1000 ° C. after the step of forming the second metal plating layer.

  According to another finding of the present invention, there is provided a metal coated steel sheet manufactured by the above-described metal coating method for a steel sheet according to the present invention.

  According to still another aspect of the present invention, a steel plate, a porous first metal coating layer formed on at least one surface of the steel plate using the first metal powder, and a metal powder forming the first metal coating layer are provided. There is provided a metal-coated steel sheet including a second metal plating layer formed in the gap.

  The second metal plating layer is preferably formed between a surface layer portion of the first metal coating layer and pores of the first metal coating layer.

  It is preferable that an uneven structure portion is formed at the interface between the steel plate and the first metal coating layer.

  The first metal is copper (Cu), aluminum (Al), zinc (Zn), iron (Fe), nickel (Ni), chromium (Cr), molybdenum (Mo), titanium (Ti), cobalt (Co). It is preferable that at least one metal selected from the group consisting of manganese (Mn), tungsten (W), zirconium (Zr), and tin (Sn) is included.

  The first metal powder preferably has an average particle size of 1 to 20 μm.

  The second metal preferably includes at least one metal selected from the group consisting of zinc (Zn), nickel (Ni), tin (Sn), copper (Cu), and chromium (Cr).

  According to the present invention, by using the heated gas, the metal powder can be injected by forming a high-pressure gas without increasing the gas consumption, and heated to a temperature below the softening point. Coating efficiency can be improved by plastic deformation. In the metal-coated steel sheet of the present invention, since a plating layer is formed between metal powder particles and a coating layer without voids can be provided, the corrosion resistance is improved and the functionality of the coating powder itself is ensured. Can do.

FIG. 3 schematically illustrates an exemplary structure of a coating layer formed in accordance with the present invention. It is the figure which showed typically an example of the injection device formed so that the coating method of this invention might be implement | achieved. It is the figure which showed typically the other example of the injection device formed so that the coating method of this invention might be implement | achieved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

  According to the present invention, the function of the metal coating layer is provided by providing on the steel plate a metal coating layer without voids, in which a metal plating layer is formed inside and / or between the metal powder particles in the surface layer portion of the metal coating layer. A coating technique that maximizes the properties and a surface-treated steel sheet using the same are provided.

  The steel plate to which the metal coating method of the steel plate according to the present invention is applicable is not particularly limited, but is hot-rolled steel plate, cold-rolled steel plate, cold-rolled annealed steel plate, galvanized steel plate, zinc-based alloy plated steel plate, and aluminum-based steel It can be a steel plate selected from the group consisting of plated steel plates.

  The metal coating method for a steel sheet according to the present invention includes a step of heating the first metal powder at a temperature not lower than a normal temperature and lower than a softening point, a step of heating a gas at a temperature of 200 to 600 ° C., and heating the heated metal powder. A step of forming a porous first metal coating layer by spraying with a vacuum gas, and a step of forming a second metal plating layer in a gap between powders forming the first metal coating layer.

  That is, the metal coating method of the present invention is a method of forming a coating structure by mixing a metal powder heated to an appropriate temperature and a gas and injecting the powder placed on the gas flow in a low-temperature and low-pressure atmosphere. It is. According to the present invention, as a result of vacuum injection of the first metal powder onto the steel plate in this way, as shown in FIG. 1, the concavo-convex structure portion 8 can be formed at the interface with the steel plate.

  At this time, the “normal temperature” means a temperature of about 15 to 25 ° C.

  In addition, according to the present invention, since the inside of the vacuum body 100 to which the powder on the gas flow is injected is maintained in a low temperature and low pressure state, the nozzle injection port is used as a boundary without increasing the gas consumption. Gas can be injected by a high pressure difference between the coating portion and the transfer gas. Furthermore, since the vacuum main body 100 is maintained at a low temperature, an increase in pressure inside the vacuum main body 100 is prevented even when the powder riding on the gas flow is injected, and the powder is stably injected. Can do.

  In the step of heating the first metal powder at a temperature not lower than the normal temperature and lower than the softening point, the first metal may be copper (Cu), aluminum (Al), zinc (Zn), iron (Fe), nickel (Ni), At least one selected from the group consisting of chromium (Cr), molybdenum (Mo), titanium (Ti), cobalt (Co), manganese (Mn), tungsten (W), zirconium (Zr), and tin (Sn) Including, but not limited to, a metal, any one of these metals, two or more alloys thereof, or an alloy containing at least one of them. For example, stainless steel powder can be used, and high-strength alloy powders can be used, not to mention Fe-based metals such as stainless steel powders such as 200 series, 300 series, and 400 series. Accordingly, the softening point can vary depending on the first metal.

  On the other hand, in the present invention, the aspect ratio (long axis length / shortened length) of the cross section of the first metal powder is preferably less than 2.

  For example, the step of heating the first metal powder can be performed at a temperature of room temperature to 900 ° C. when a stainless steel powder is used.

  If the temperature at the stage of heating the first metal powder is as low as room temperature, there is a problem that plastic deformation and coating are not smooth, but this can be overcome by further heating the transfer gas. When the melting point is higher than the softening point, there is a risk that the steel sheet material may be damaged in the case of the high melting point powder, and the production cost is increased.

  The first metal powder preferably has an average particle size of 1 to 20 μm, more preferably an average particle size of 1 to 10 μm. When the average particle size of the first metal powder is less than 1 μm, there is a problem that the cost of the powder increases, resulting in an increase in manufacturing cost. When the average particle size exceeds 20 μm, there is a problem between the particles of the powder coating layer. The gap size is large and it is difficult to form a dense coating layer. Also, the impact energy required when coating steel sheets increases, and this requires a higher pressure gas. There is a problem of increasing.

  Meanwhile, a step of heating the gas is performed separately from the step of heating the first metal powder. More specifically, the gas is preferably heated at a temperature of 200 to 600 ° C., more preferably 200 to 500 ° C. When the temperature is less than 200 ° C., there is a problem that sufficient gas pressure cannot be secured. When the temperature exceeds 600 ° C., the problem is that the powder injection speed increases and the steel plate material is damaged, There is a problem that the material is bent due to the above, and a manufacturing cost is increased.

At this time, the usable gas preferably has a density equal to or lower than air, and includes at least one gas selected from the group consisting of nitrogen (N ₂ ), helium (He), and air, This is not a limitation. That is, as the gas, nitrogen (N ₂ ), helium (He), or the like having a low density can be used, but dry air having a higher density than these is used in consideration of the amount used, the price, and the like. You can also.

  On the other hand, the higher the temperature of the powder, the better for improving the coating efficiency of the metal powder by plastic deformation. However, according to the present invention, the metal powder is heated at the above-mentioned temperature and heated at a lower temperature. By mixing and injecting with a large number of flowed gases, the plastic deformation rate of the powder can be maximized and injected at an appropriate speed.

  Then, the stage which forms a porous 1st metal coating layer is performed by vacuum-jetting the metal powder heated in this way with the heated gas.

  With reference to FIG. 2 and FIG. 3, the metal coating method of the present invention will be described in more detail with an apparatus capable of performing it.

  The present invention can be realized by using, for example, the powder injection device 1, and provides a steel sheet as the member to be coated 3 to the vacuum body 100, and the powder is laminated on the member to be coated 3 while being plastically deformed. As described above, the powder can be put on the flow of the high-pressure gas heated by the heating and spraying unit 200 and sprayed onto the coated member 3.

  In order to provide the coated member 3 to be coated inside the vacuum body 100, the coated member 3 is mounted on the member transporter 3a. Thereafter, when the gas heating unit 230 heats the gas provided from the gas supply unit 220 and the powder heating unit 240 heats the powder provided from the powder supply unit 210, the heated high-pressure gas and powder are converted into the nozzle unit 250. The coating layer is formed by being sprayed at a high speed on the vacuum body 100 in a vacuum state and laminated on the steel plate 3 of the member to be coated inside the vacuum body 100 by plastic deformation.

  That is, according to the present invention, the gas and powder to be injected are heated before being injected, and the high-pressure gas is formed by increasing the gas flow rate by the existing vacuum injection method and then injecting at high speed. In this way, the high pressure gas can be formed without increasing the gas consumption, and the powder can be injected at high speed. Further, by heating the metal powder to be coated to a specific temperature or higher according to the material, it is possible to increase the plastic deformation rate of the metal material so that lamination can be performed smoothly at the time of collision with the steel plate.

  For example, the powder heating unit 240 may be provided to the powder supply unit 210 and may serve to heat the powder. The reason for heating the powder is to facilitate plastic deformation of the powder, and the temperature can be controlled to be higher than that of the gas heating portion, which contributes to the improvement of the coating efficiency. That is, the powder heating unit 240 is provided separately from the gas heating unit 230, and by separating and heating the gas and the powder, a powder temperature higher than the gas temperature can be realized. Also, the powder heating unit 240 may be provided with a sensor S for temperature measurement, and connected to the control unit C to control the heating temperature.

  The vacuum body 100 may include a chamber part 110 in which the steel plate 3 is provided and a vacuum part 130 provided in the chamber part 110 in order to form a vacuum.

  Meanwhile, it is preferable that the chamber part 110 is provided to be sealed so that the vacuum formation by the vacuum part 130 is maintained. The transfer device 3 a provided to the steel plate 3 may also be provided inside the chamber part 110.

  On the other hand, in the present invention, the vacuum injection is preferably performed at a pressure of 0.01 to 20 Torr, and more preferably at a pressure of 0.1 to 15 Torr.

  When the vacuum injection is performed at a pressure of less than 0.01 Torr, there is a problem that the manufacturing cost for forming a vacuum as a high vacuum region increases. When the vacuum injection is performed at a pressure exceeding 20 Torr, a vacuum chamber is used. In some cases, a sufficient powder injection speed cannot be obtained.

  For example, referring to FIGS. 2 and 3, the vacuum unit 130 may serve to create a vacuum inside the chamber unit 110. For this purpose, the vacuum unit 130 may include a vacuum pump 131, a powder filter 132, and a cooler 133. That is, the vacuum part 130 can play a role of maintaining the inside of the chamber part 110 in a low vacuum state of 0.01 to 20 Torr.

  The vacuum body 100 may further include a cooling unit 120 so that the temperature difference with the heating and spraying unit 200 is further increased, so that powder can be sprayed at a high speed with a larger pressure difference.

  That is, the vacuum injection is preferably performed at a temperature of 10 to 200 ° C, and more preferably at a temperature of 25 to 100 ° C. When the temperature of the vacuum jet is less than 10 ° C., there is a problem that the cost for maintaining the temperature increases. When the temperature exceeds 200 ° C., the pressure in the vacuum chamber increases, and there is a sufficient pressure difference. There is a problem that it cannot be obtained.

  That is, the cooling unit 120 may serve to maintain the temperature of the entire interior of the chamber unit 110 at a low temperature. Thus, it goes without saying that the pressure difference between the inside of the chamber part 110 and the supplied gas can be further increased, and powder can be injected at a higher speed. Even when gas and powder are injected from the heating and injection unit 200 described later, there is an advantage that the pressure inside the chamber part 110 is prevented from being increased and the powder can be stably injected. .

  Therefore, the vacuum body 100 of the exemplary powder injection apparatus 1 to which the present invention is applicable may include the chamber unit 110 and the cooling unit 120 provided to the chamber unit 110 so as to maintain the inside at a low temperature. it can. The cooling unit 120 may be a powder injection device of FIG. 2 provided in a double structure so as to surround the outer surface of the chamber unit 110 so that cooling is performed on the entire surface of the chamber unit 110, or a cooling coil or a cooling pin. Can be realized like the injection device of FIG.

  The powder and the first metal powder are heated and sprayed into the vacuum body 100 at a high speed, whereby the powder is coated on the steel plate 3 which is a member to be coated provided in the vacuum body 100 by plastic deformation. can do. Therefore, the heating and spraying unit 200 may include a powder supply unit 210, a gas supply unit 220, a gas heating unit 230, a powder heating unit 240, a nozzle unit 250, and the like.

  The powder supply unit 210 may serve to provide powder to be sprayed for coating the steel plate 3, and the powder may be heated and supplied by the powder heating unit 240. In addition, the powder supply unit 210 can adjust the supply amount of the powder, and receives a part of the gas supplied from the connection pipe 223 a connected to the gas distributor 223 of the gas supply unit 220. The supplied gas can act as a driving force for floating the powder stored in the powder supply unit 210 and transferring the suspended powder.

  Meanwhile, the gas supply unit 220 may serve to supply a high-pressure gas for injecting the powder at a high speed. That is, when the powder is injected into the vacuum main body 100, the powder is injected along the flow of the high-pressure gas when the high-pressure gas is injected. Therefore, when the high-pressure gas is injected at a high speed, the powder can also be injected at a high speed. In addition, the gas supply unit 220 is maintained in a high pressure state in order to inject gas at a high speed, and can be heated by the gas heating unit 230 to provide a high-temperature and high-pressure gas. Therefore, the gas supply unit can include a gas storage chamber 221, a gas transfer pipe 222, a gas distributor 223, a dehumidifier 224, and the like. Moreover, the sensor S for measuring temperature can be provided, and it can be connected with the control part C and can control the heating temperature by the said gas heating part 230. FIG.

  The temperature and speed of the gas and powder are important factors that determine the injection speed, and must be set appropriately according to the metal powder material. If the gas temperature or velocity is too low, the metal powder will not get enough impact energy for coating when it collides with the steel plate material, and if it is too high, the material will not be coated. This causes a problem of etching out or jumping out without being laminated after the collision.

  That is, in order to coat a metal powder on the surface of a steel plate material, an appropriate impact energy is necessary, and for that purpose, the temperature and speed conditions of the gas and powder are important. Under optimized conditions, strong impact energy causes metal bonding at the interface between the steel plate material and the metal coating layer, or the formation of an intermetallic diffusion layer between the steel plate component and the coating powder material component, or is strong The impact energy can form an uneven layer where the initial collision particles enter the steel plate material side, or two or more of these structures or all of these layers can be formed. More specifically, when the impact energy is low, even if there is no metal bond or intermetallic diffusion layer, the concavo-convex structure is formed and laminated, and as the impact energy increases, the metal bond is formed along with the formation of the concavo-convex structure. When the steel plate material and the powder are components different from each other, an intermetallic diffusion layer can be formed. On the other hand, when the impact energy is low, the adhesion can be somewhat low, but the adhesion can be ensured by forming a metal bond by heat treatment described below.

  Thus, due to the formation of the metal bond at the interface between the steel plate material and the first metal coating layer, the intermetallic diffusion layer and the uneven structure portion, the material steel plate and the first metal coating layer have a strong adhesion, The metal bonds and intermetallic diffusion layers accompanied by plastic deformation can be formed between the particles.

  Through such steps, the metal powder can be sprayed onto the steel plate material to form the metal coating layer with high coating efficiency. However, in such a case, although the coating efficiency is high, most of the particles are coated at the time of collision with the steel plate material, and the shape of the powder particles is maintained, but the coating is performed in a slightly deformed state. As a result of coating while maintaining the morphology of the particles, voids are formed inside the coating layer, which may cause problems such as corrosion resistance.

  In the present invention, the cross-sectional aspect ratio (long axis length / shortening length) of the metal powder in the first metal coating layer is preferably less than 2.

  Therefore, in the present invention, the step of forming the second metal plating layer is further performed.

  That is, in this invention, the coating layer without a space | gap is finally provided by forming another metal layer by plating between the surface layer part of a metal coating layer, the inside, or both these metal powder particles. Thereby, the penetration | invasion of a corrosion factor can be prevented and the functionality of coating material can be maximized.

  At this time, the second metal that can be used includes at least one metal selected from the group consisting of zinc (Zn), nickel (Ni), tin (Sn), copper (Cu), and chromium (Cr). However, it is not limited thereto, and any one of these metals, two or more alloys thereof, or an alloy including at least one of them can be used.

  On the other hand, the step of forming the plating layer can be performed by an electroplating method or an electroless plating method.

  That is, by forming another plating layer on the steel plate material on which the metal coating layer is formed using a normal electroplating method or electroless plating method, voids between the powder particles in the metal coating layer are formed. By filling in, a metal coating layer without voids can be formed.

  FIG. 1 schematically shows a structure in which another metal layer is formed by plating between the metal powder particles inside the metal coating layer and on the surface layer portion. It may be realized so that a plating layer is formed only in the space between the metal powder particles inside the layer and plating on other surface layer portions is suppressed. In the latter case, an inhibitor can be included in the plating solution, and as a result, another metal layer can be mainly formed only in the voids in the metal coating layer.

  In this case, the inhibitor that can be used is not particularly limited, but an inhibitor usually used in electroplating or electroless plating can be used, and the metal type and powder of the metal coating layer proposed in the present invention can be used. Any inhibitor that is optimal for the properties of the metal coating layer determined by the size or the like may be used. For example, surfactants such as polyol-based and amine-based organic compounds can be used.

  In the present invention, the method may further include polishing the second metal plating layer.

  When performing the polishing step, the voids in the surface layer portion can be further minimized, and the appearance can be improved by imparting a hairline or metal texture to the surface of the metal coating layer. This is due to the phenomenon that the voids in the surface layer are blocked by the frictional force generated during the polishing process, and the value of the product is improved by adding a metal texture such as a hairline to the surface by the polishing process. An effect can be obtained.

  Furthermore, according to the coating method of the present invention, it may further include a step of heat treatment at a temperature of 200 to 1000 ° C., and the heat treatment temperature is more preferably 300 to 850 ° C.

  The temperature during the additional heat treatment is preferably less than the melting point of the metal or alloy constituting the metal coating layer. When the steel plate material is a plated steel plate, the melting point of the plating layer and the alloying temperature of the plating layer are taken into consideration. Thus, it is preferable to perform heat treatment at a low temperature for a long time if necessary.

  Further, by applying a laser or plasma heating method as a heat treatment method, it is possible to apply a method of minimizing the influence of heat on the steel sheet material and imparting the effect of the heat treatment only to the coating layer.

  This additional heat treatment step further minimizes voids in the metal coating layer, between the steel plate material and the metal coating layer, between the powder particles in the metal coating layer, and even with the metal powder particles. By providing adhesion between the plated layer formed by plating, workability can be improved along with corrosion resistance.

  This is due to a phenomenon in which sintering occurs at each interface by an additional heat treatment. On the other hand, dislocation occurs in the crystal grains due to plastic deformation of the powder particles during coating, but the dislocation is eliminated by such heat treatment, and the size of the crystal grains in the powder particles is less than the average particle size (D50) of the original powder particles. Is recrystallized. This increases the workability in preparation for a metal coating layer that has not been heat-treated.

  At this time, a dissimilar intermetallic diffusion layer can be formed at the interface between the metal powder particles and the plating layer and at the interface between the steel plate material and the metal coating layer.

  The additional heat treatment step can be performed before or after the polishing step, and the processing order is not limited.

  According to the present invention, there is provided a metal-coated steel sheet produced by the above-described metal coating method for a steel sheet of the present invention.

  More specifically, the metal-coated steel sheet of the present invention comprises a steel sheet, a porous first metal coating layer formed using a first metal powder on at least one surface of the steel sheet, and the first metal coating layer. And a second metal plating layer formed in the gap between the metal powders.

  Referring to FIG. 1, in a gap between a porous first metal coating layer 4 formed by spraying a first metal powder on a steel plate or a plated steel plate 3, and metal powder particles 5 constituting the first metal coating layer. A metal-coated steel sheet 2 is provided which includes the formed second metal plating layer 6 and has a coating layer 4a without voids 7 formed therein.

  At this time, the second metal plating layer may be formed between pores inside the first metal coating layer and / or in a surface layer portion. Therefore, by finally providing a coating layer without voids, it is possible to ensure corrosion resistance by preventing the corrosion factor from reaching the steel sheet, and maximize the functionality of the coated metal. It can be made.

  On the other hand, in the present invention, the porous first metal coating layer is formed by a vacuum injection process, and the size of the crystal grains of the first metal powder in the metal coating layer is the average particle size (D50) of the originally used powder particles. ).

  Meanwhile, an intermetallic diffusion layer exists at the interface between the second metal plating layer and the first metal powder particles formed between the first metal powder particles, and the interface between the steel plate and the first metal coating layer. A metal bond, the concavo-convex structure portion 8, and an intermetallic diffusion layer can be formed.

  The first metal is copper (Cu), aluminum (Al), zinc (Zn), iron (Fe), nickel (Ni), chromium (Cr), molybdenum (Mo), titanium (Ti), cobalt (Co). , At least one metal selected from the group consisting of manganese (Mn), tungsten (W), zirconium (Zr), and tin (Sn), but is not limited thereto, any of these It can be a metal, two or more of these alloys, or an alloy comprising at least one of these. For example, stainless steel powder can be used, and high-strength alloy powders can be used, not to mention Fe-based metals such as stainless steel powders such as 200 series, 300 series, and 400 series. Accordingly, the softening point can vary depending on the first metal.

  The first metal powder is preferably a single type of metal powder having an average particle size of any one of 1 to 20 μm, more preferably an average particle size of 3 to 10 μm, and even more preferably 5 to 10 μm. . When the average particle size of the first metal powder is less than 1 μm, there is a problem that the cost of the powder increases, resulting in an increase in manufacturing cost. When the average particle size exceeds 20 μm, there is a problem between the particles of the powder coating layer. The gap size is large and it is difficult to form a dense coating layer, and the impact energy required when coating on steel sheets increases, and this requires a higher pressure gas, so gas consumption There is a problem that increases.

  At this time, the second metal that can be used includes at least one metal selected from the group consisting of zinc (Zn), nickel (Ni), tin (Sn), copper (Cu), and chromium (Cr). However, it is not limited thereto, and any one of these metals, two or more alloys thereof, or an alloy including at least one of them can be used.

  Hereinafter, the present invention will be described more specifically with reference to specific examples. The following examples are merely illustrative for understanding of the present invention, and the scope of the present invention is not limited thereby.

"1. Experiment for confirming changes in coating layer depending on temperature conditions during coating"
Cold rolled steel sheet was used as the material to be coated, and stainless steel powder was used as the coating material. The average particle size (D50) of the powder was 5 μm, and the particle size had a normal distribution in the range of 1 to 10 μm.

  The coating apparatus shown in FIG. 2 is used, and the initial vacuum main body 100 pressure is set to 5 × 0.01 Torr and the gas pressure before nozzle injection is set to 800 Torr as the coating conditions. The coating experiment was carried out. At this time, dry air was used as the gas, and the flow rate was set to 30 L / min for the powder transfer pipe 211 and 200 L / min for the gas transfer pipe 222. Further, the nozzle portion 250 is separated from the coating material by 10 mm using a cylinder type nozzle having a throat size of 0.8 mm × 100 mm, and the material is 10 mm / sec with one nozzle portion 250 fixed. The coating was carried out while moving left and right twice at a speed.

  The powder heating unit 240 and the gas heating unit 230 were driven, and the coating experiment was performed by controlling the temperatures of the powder transfer pipe 211 and the gas transfer pipe 222 to the values shown in Table 1 below.

  The thickness of the coating layer was measured by the elemental analysis of the Cr component in the cross section by a scanning electron microscope (SEM) for the cold-rolled steel sheet as the coated member. It was.

  As can be seen from Table 1 above, almost no coating was performed in Comparative Example 1 performed under normal temperature conditions, whereas Comparative Example 2 (having a normal distribution in a particle size range of 1 to 10 μm), Example From the results of 1 and Example 2, it was found that the thickness of the coating layer increased as the gas temperature increased. However, in Comparative Example 2, although a structure without voids was obtained, it was not possible to utilize because the coating efficiency was low, and it was confirmed from the results of Examples 1 to 5 that voids were formed. .

  Such a result is attributed to the fact that as the gas temperature rises, the pressure of the gas increases, and the pressure difference between the high-pressure gas and the inside of the vacuum body 100 increases, thereby increasing the powder injection speed.

  Moreover, it turned out that the thickness of a coating increases further by heating a powder from the result of Example 3, Example 4, and Example 5. FIG. Therefore, the plastic deformation rate can be maximized by heating the metal powder in this way, and as a result, the coating efficiency can be dramatically increased as compared with Comparative Example 1 under normal temperature conditions.

"2. Physical property confirmation experiment of coating layer by coating process"
The material and coating conditions of the steel sheet are as described in 1. above. The same temperature conditions as those in Example 4 in Table 1 were set. However, the test piece was manufactured so that the average particle size of the powder was 5 μm and the coating thickness was about 25 μm.

  The same test piece thus obtained was further subjected to electroplating, heat treatment, polishing treatment, etc. to produce each test piece as shown in Table 2 below. In the case of performing a plurality of subsequent processes, the process order was electroplating, heat treatment, and then polishing process.

Electroplating, plated with more Ni in the metal powder coating layer, the plating solution is very adding a small amount of inhibitor in the current density 20A / dm ^2, about 2g adhesion amount under the conditions of the plating solution temperature 50 ° C. / M ² .

  The heat treatment was performed in a reducing atmosphere at a temperature condition of 850 ° C. for 5 minutes. The polishing process was performed using normal sandpaper so that about 2 to 5 μm of the surface layer portion was consumed.

  The test pieces thus produced were evaluated for corrosion resistance and workability, and the results are shown in Table 2 below.

  Corrosion resistance was measured by a salt spray test until the area where red rust was generated reached 5% of the total area of the test piece 75 mm × 150 mm.

  The workability was evaluated by the presence or absence of cracks in the bending portion under the conditions of an angle of 90 ° and a curvature radius of 3 mm by a bending experiment. Table 2 below shows “X” when a crack is generated and “◯” when no crack is generated by observation with an optical microscope.

  In the case of Comparative Examples 3 to 6 in which voids exist in the metal coating layer, the corrosion resistance is increased to some extent by heat treatment or polishing treatment even if another metal is not present in the coating layer in addition to the metal powder. However, it was confirmed that the corrosion resistance and functionality of the STS powder coating layer itself could not be fully exhibited.

  On the other hand, as can be confirmed from Example 6 above, by forming another metal between the coated powder particles, the functionality of the coating layer can be more effectively exhibited. As can be confirmed from Example 9, it was confirmed that the characteristics could be further improved by further heat treatment or polishing treatment.

  Although the embodiments of the present invention have been described in detail above, the scope of rights of the present invention is not limited thereby and within the scope without departing from the technical idea of the present invention described in the claims. It will be apparent to those skilled in the art that various modifications and variations are possible.

DESCRIPTION OF SYMBOLS 1 Powder injection apparatus 2 Metal coated steel plate 3 Coating material (steel plate or plated steel plate)
DESCRIPTION OF SYMBOLS 4 Metal coating layer 4a Coating layer without space | gap 5 1st metal powder particle 6 2nd metal 7 Space | gap 8 Uneven structure part 100 Vacuum body 110 Chamber part 120 Cooling part 130 Vacuum part 131 Vacuum pump 131 Powder filter 133 Cooler 200 Heat injection Unit 210 Powder supply section 211 Powder transfer pipe 220 Gas supply section 221 Gas storage chamber 222 Gas transfer pipe 223 Gas distributor 223a Connection pipe 224 Dehumidifier 230 Gas heating section 240 Powder heating section 250 Nozzle section

Claims (17)

Heating the first metal powder at a temperature not lower than the normal temperature and lower than the softening point;
Heating the gas at a temperature of 200-600 ° C .;
Forming a porous first metal coating layer by vacuum jetting the heated metal powder together with the heated gas;
Forming a second metal plating layer in a gap between powders forming the first metal coating layer.   The first metal is copper (Cu), aluminum (Al), zinc (Zn), iron (Fe), nickel (Ni), chromium (Cr), molybdenum (Mo), titanium (Ti), cobalt (Co). The metal coating method of the steel plate of Claim 1 containing the at least 1 or more metal selected from the group which consists of manganese (Mn), tungsten (W), zirconium (Zr), and tin (Sn).   The metal coating method for a steel sheet according to claim 1, wherein the first metal powder has an average particle size of 1 to 20 μm. The metal coating of a steel sheet according to claim 1, wherein the gas is at least one gas selected from the group consisting of nitrogen (N ₂ ), helium (He), and air having a density equal to or lower than air. Method.   The metal coating method for a steel sheet according to claim 1, wherein the vacuum injection is performed at a pressure of 0.01 to 20 Torr.   The metal coating method for a steel sheet according to claim 1, wherein the vacuum spraying is performed at a temperature of 10 to 200 ° C.   The second metal includes at least one metal selected from the group consisting of zinc (Zn), nickel (Ni), tin (Sn), copper (Cu), and chromium (Cr). The metal coating method of the steel plate as described in 2.   The method for coating a steel sheet according to claim 1, wherein the step of forming the second metal plating layer is performed by an electroplating method or an electroless plating method.   The metal coating method for a steel sheet according to claim 1, further comprising a step of polishing the second metal plating layer.   The metal coating method for a steel sheet according to claim 1, further comprising a step of performing a heat treatment at a temperature of 200 to 1000 ° C. after the step of forming the second metal plating layer.   A metal-coated steel sheet produced according to any one of claims 1 to 10. Steel sheet,
A porous first metal coating layer formed on at least one surface of the steel plate using a first metal powder;
A metal-coated steel sheet, comprising: a second metal plating layer formed in a gap between metal powders forming the first metal coating layer.   The metal-coated steel sheet according to claim 12, wherein the second metal plating layer is formed in a surface layer portion of the first metal coating layer and pores of the first metal coating layer.   The metal-coated steel plate according to claim 12, wherein an uneven structure portion is formed at an interface between the steel plate and the first metal coating layer.   The first metal is copper (Cu), aluminum (Al), zinc (Zn), iron (Fe), nickel (Ni), chromium (Cr), molybdenum (Mo), titanium (Ti), cobalt (Co). The metal-coated steel sheet according to claim 12, comprising at least one metal selected from the group consisting of manganese, Mn, tungsten (W), zirconium (Zr), and tin (Sn).   The metal-coated steel sheet according to claim 12, wherein the first metal powder has an average particle size of 1 to 20 μm.   The said second metal includes at least one metal selected from the group consisting of zinc (Zn), nickel (Ni), tin (Sn), copper (Cu), and chromium (Cr). Metal coated steel sheet.

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