KR20090052698A - Method for manufacturing thin plate using spray coating - Google Patents

Abstract

The present invention relates to a method for manufacturing a thin plate using the spray coating method, and more particularly, in the conventional rolling method, in contrast to exposing the limits for ultra-thin materials, the thin plate in a desired form using a spray coating It relates to a method for producing a thin plate can be easily produced by forming an ultra-thin.

The production method of the present invention comprises the steps of preparing a support; Applying an intermediate layer to the support surface; Spray coating the support on which the intermediate layer is applied to obtain a support on which a thin plate is laminated; And separating the thin plate by removing some or all of the intermediate layer from the thin plate coated support.

Spray Coating, Thermal Spray, Low Temperature Spray, Interlayer, Thin Plate

Description

Manufacturing method of thin plate using spray coating method {METHOD FOR MANUFACTURING THIN PLATE USING SPRAY COATING}

The present invention relates to a method for manufacturing a thin plate using the spray coating method, and more particularly, in the conventional rolling method, in contrast to exposing the limits for ultra-thin materials, the thin plate in a desired form using a spray coating It relates to a method for producing a thin plate can be easily produced by forming an ultra-thin.

The thin plate means a thin plate, and it is difficult to uniformly determine the thickness of the plate in accordance with the term 'thin plate', but it may be considered to mean a plate having a thickness of about several tens of mm or less.

Such a thin plate, in particular, a technique for manufacturing a metal thin plate can be divided into two largely depending on the thickness of the thin plate.

First, as a technique for manufacturing a thin film plate having a thickness of several micrometers or less, a technique using a deposition method such as CVD, PVD, and sol-gel method is mainly used. The above technique is capable of producing very thin sheets having a thickness of several micrometers or less, and is advantageous in that the thickness control is precise, but the prepared sheets are difficult to separate from the support, and even if separated, they are very fragile. Since it cannot be used alone for the purpose of a structure, etc., it is excluded from the scope of the technique for manufacturing the thin plate targeted by this invention.

Secondly, as a technique for manufacturing a thin plate having a thickness of about several mm or more, a metal ingot (which means all slabs, blooms, billets, etc.) is rolled to the thin plate having a desired thickness. The manufacturing method is mentioned. In the method, the metal ingot may be heated to a temperature at which the metal softens, if necessary, and may also be manufactured to a desired thickness by repeating hot rolling and cold rolling several times. Rolling is done in such a way that the thickness of the roll is reduced by the compression force acting between the two rolls by passing the metal ingot between one or more pairs of up and down facing rolls. However, in the case of the rolling method as described above, the thickness of the metal sheet to be manufactured is usually only 3 mm or more, but when manufacturing the metal sheet with a smaller thickness, the reduction force applied to the roll is increased. There is a fear that facilities will be enlarged and complicated. In addition, in order to process a metal with low formability, the metal ingot has to be heated to a high temperature, which causes a high energy cost. In addition, when the formability of the metal is very low, cracks may occur during rolling or installation. There may be various problems such as excessive load.

The present invention is to solve the problems of the prior art, according to one aspect of the present invention, not only can be easily manufactured thin plate thickness of 3mm or less, but also the prepared thin plate is easily separated from the support to recover the thin plate There is provided a method for producing a thin plate which is easy.

The manufacturing method for solving the problem of the present invention comprises the steps of preparing a support; Applying an intermediate layer to the support surface; Spray coating the support on which the intermediate layer is applied to obtain a support on which a thin plate is laminated; And separating the thin plate by removing some or all of the intermediate layer from the thin plate coated support.

At this time, the spray coating method is preferably a thermal spray coating method or low temperature spray coating method.

In addition, when the spray coating method is a thermal spray coating method, the intermediate layer is preferably made of a water-soluble ceramic.

In addition, it is effective to remove the intermediate layer made of the water-soluble ceramic by adding moisture.

In addition, when the spray coating method is a low temperature spray coating method, the intermediate layer is preferably made of a low melting point metal.

In addition, the intermediate layer made of the low melting point metal is preferably removed by melting.

In order to further improve the physical properties of the thin plate manufactured by the above process, it is preferable to further temper the thin plate obtained after the step of separating the thin plate.

According to the present invention, even when the thickness of the thin plate is not only easier to manufacture the thin plate compared to the conventional rolling method, but also the thin plate can be easily separated from the support can be used as a thin plate alone, its use is Wide is effective.

Hereinafter, the present invention will be described in detail.

First, the meaning of the term 'thin plate' referred to in the present invention is elaborated. The thin plate generally refers to a plate-shaped object that is thinner than the total width. However, the thin plate of the present invention does not necessarily have a flat plate shape as long as its thickness is thin. Or, if it has another special form, but the thickness is thin, it should be noted that all corresponds to the 'thin plate' means in the present invention. In addition, the thin plate means in the present invention is not necessarily limited to a metal material, it is meant to include a thin plate manufactured by a material that can be coated by spray coating, such as cermet. Although not necessarily limited to this, examples of materials that can be used to manufacture the thin plate of the present invention include pure metals Fe, Al, Ni, Ti, Cu and Fe-based, Al-based, Ni-based, Ti-based, Cu-based alloys, and the like. .

The inventors of the present invention have studied in depth to produce a thin plate in a simpler way, and found that when the thin plate is manufactured by spray coating the thin plate on a support, a thin plate having a very thin thickness can be produced. And the present invention.

That is, the thin plate manufacturing method of the present invention can be implemented by spray coating a material forming a thin plate on a support having a desired shape. However, this may cause one big problem. In other words, the spray coating means a method in which the sprayed materials at high speed are coated on the surface of the support by bonding to each other or strongly bonded to the support, in which case the bonding strength of the support and the coating layer is high so that the coated thin plate is difficult to be separated from the support. Can be. In this case, the problem of the present invention of easily manufacturing a thin plate of thin thickness is not easily achieved.

In the present invention, in order to solve this problem, after coating the intermediate layer on the surface of the support, spray coating is performed. That is, since the intermediate layer is first coated on the support and then spray-coated a coating material for forming a thin plate thereon, the stack is formed in the form of a support / intermediate layer / coating material (thin plate), and then some or all of the intermediate layer of the laminate is subsequently removed. This is because the coated thin plate can be easily separated from the support when removed.

Therefore, it is preferable that the intermediate layer can be easily removed by simple operation. Here, the simple operation means a case of supplying heat or moisture, and the kind of the intermediate layer is changed according to the conditions of the spray coating.

That is, the spray coating may be divided into a thermal spray coating and a low temperature spray coating according to the degree to which the powder to be coated is heated and melted. First, all or a part of the coating material to be sprayed is exposed to a high temperature and sprayed in a molten state. In the case of a thermal spray coating, the intermediate layer is preferably a water soluble ceramic. In the case of the thermal spray coating, it is preferable that the intermediate layer is not damaged by heat as much as possible so that the surface shape of the coated thin plate can be maintained in a desired shape, so that the ceramic is coated at a stable temperature at a relatively high temperature and the thin coating material is coated on the ceramic. It is desirable to.

Then, it is preferable to remove the ceramic by a simple method so that the prepared thin plate can be easily separated from the support. According to the results of the inventors of the present invention, the ceramic is preferably a water-soluble ceramic. The ceramic is not particularly limited as long as it is water-soluble, and examples thereof include NaCl.

In this case, in order to sufficiently accommodate the role of the intermediate layer in which the water-soluble ceramic is not in direct contact with the thin coating layer and the support, the thickness of the water-soluble ceramic is different depending on the particle diameter per powder sphere commonly used in the spraying process. It is preferable that it is micrometer or more. When the thickness of the water-soluble ceramic is too thin, there is a possibility that the thin plate is difficult to separate by the direct contact between the thin coating layer and the support, on the contrary, if too thick (ie, 10 mm or more), it is difficult to expect further effects. However, it may be difficult to form a thick and uniform coating layer.

In this case, the water-soluble ceramic may be coated on the surface of the support using a thermal spraying process capable of melting the particles. In addition, in order to remove the ceramic coating layer, the thin plate can be obtained very simply because water is supplied to the laminate coated with the thin plate.

Unlike the thermal spray coating, in the cold spray coating, the intermediate layer is preferably a low melting point metal having a low melting point. More specifically, it is preferable that melting | fusing point of the said low melting metal is 350 degrees C or less, Although it is not limited to this, Tin (melting point: 232 degreeC), lead (melting point: 327 degreeC) etc. are mentioned as an example. The low melting point metal may be applied to the surface of the support using conventional plating methods such as hot dip plating, vapor deposition, or common spraying processes of thermal spraying and low temperature spraying. The reason why the low melting point coating layer is applied to the surface of the support during low temperature spraying is that unlike the thermal spraying, the coating powder that is sprayed at low temperature is not molten. Since it is not easy, the intermediate layer can serve as a metal bond to provide a bonding force between the powders. In addition, as described above, the intermediate layer should be easily removed from the support / intermediate layer / thin plate coating layer. When using a low melting point metal, the intermediate layer may be melted at a very low temperature and removed from the laminate, so that a thin plate may be easily obtained. have.

At this time, the thickness of the low melting point metal layer is different depending on the particle diameter per powder spherical commonly used in the spraying process, but preferably 100 μm or more. If the thickness of the low melting point metal layer is too thin, the thin plate coating layer and the support may be in direct contact with each other, making the separation of the thin plate difficult. On the contrary, if the thickness is too thick (ie, 10 mm or more), further effects are expected. In addition to being difficult to do, it may be difficult to form a thick and uniform coating layer.

In addition, in order to remove the low melting point metal layer, as described above, it is preferable to heat the laminate to a temperature higher than the temperature of the low melting point metal so that the low melting point metal flows out of the laminate. However, if the temperature is too high, the thin plate or the support may be damaged, so the temperature for heating the laminate is preferably lower than the temperature at which the thin plate or the support is thermally damaged (that is, at least the thin plate is thermally It is desirable not to damage, most preferably not to damage either).

Here, the term 'thermally damaged temperature' is difficult to define collectively because it depends on the type or use of the thin plate to be manufactured, and the type of the support. That is, the internal structure of the manufactured thin plate is not a big problem, but if only its shape is kept thin, the melting temperature of the thin plate may be set as the 'thermally damaged temperature', and the thin plate may have various compositions. In the case of an element, for example, cermet, the temperature at which one element is chemically reacted may be defined as the 'thermally damaged temperature', and the temperature at which the internal microstructure is recrystallized is also described above. It can be defined as 'thermally damaged temperature'. In addition, since the support may also be defined as the 'thermally damaged temperature' as the temperature defined by one of these cases, the temperature cannot be defined uniformly. However, the melting temperature is generally defined herein as the 'thermally damaged temperature'.

Therefore, the method of manufacturing a thin plate of the present invention comprises the steps of preparing a support; Applying an intermediate layer to the support surface; Spray coating the support on which the intermediate layer is applied to obtain a support on which a thin plate is laminated; And separating the thin plate by removing some or all of the intermediate layer from the thin plate coated support.

At this time, as described above, the method of applying and removing the intermediate layer is different depending on whether the spray coating is performed by a thermal spraying method or a low temperature spraying method. Will be described below. As described below, the thermal spray coating or the low-temperature spray coating itself is a technology that has already been developed and implemented, and can be easily carried out by applying the conditions necessary for the present invention from the coating conditions already in common even if the conditions are not specifically described.

However, hereinafter will be briefly described the more preferable process parameters affecting the effect of the present invention divided into thermal spray coating method and low temperature spray coating method.

(Thermal spray coating conditions)

Thermal spray coating is a method of melting part or all of the powder to be coated using heat generated by a combustion reaction between fuel gas and oxygen, and then spraying the molten powder onto the subject surface to coat the coating. In this method, since the coating powder is melted and then coated, the coating powder may be combined with a sufficiently strong bonding force even if the spraying speed is not high.

Figure 1 shows the equipment for carrying out the thermal spray coating. As can be seen from the figure, the thermal spraying apparatus includes a gas supply device 1, a control panel 2, a gas heating device 3, a powder supply device 4 and a nozzle (5). Gas supplied from the gas supply device 1 is controlled by the gas amount control panel 2 is divided into a gas heating device 3 and the powder supply device (4) is supplied. The gas heating device 3 heats the gas to a high temperature to induce a speed increase due to the expansion of the gas, and the powder supply device 4 supplies the powder to the gas supplied from the control panel 2 to supply powder by gas. It serves to be supplied to the nozzle (5). As the gas is injected from the nozzle outlet 6 and as shown in FIG. 2, a hot gas flow field 7 is formed by arc ignition or direct ignition, and the powder is loaded in the flow field to impart a flying state in a molten state. After hitting the subject 8, a powder-coated subject may be obtained.

Immediately before the nozzle 5, the mixture of the powder and gas supplied from the powder feeder 4 and the high-speed gas heated and supplied from the gas heater 3 meet to form a gas / powder mixture to form the nozzle 5 Through a high velocity gas / powder jet. This high speed gas formation is possible by the structural characteristics of the nozzle as shown in FIG. The powder transported by the gas injected through the nozzle 5 collides with the subject at a high speed close to the velocity of the gas, and the thermal or kinetic energy of the powder is converted into the energy necessary for the coupling between the subject / powder. Thus, a powder-coated subject can be obtained.

At this time, the general conditions for the thermal spray coating may be carried out in accordance with a known thermal spray coating method, but as the conditions of the thermal spray coating which is particularly advantageous for thin plate manufacturing as in the present invention, the temperature of the gas, the gas It is more preferable to control the pressure, the diameter of the powder particles, and the like. Hereinafter, the above conditions will be described in detail.

Temperature of gas

When coating using thermal spraying, the gas and powder and the intermediate layer may be slightly different depending on the type of injection gas is preferably used preheated to a temperature of 500 ~ 15000 ℃. This indicates the temperature range of the heat source that may occur in the thermal spraying process, and when the temperature of the injection gas is too low, it is difficult to form a coating layer because the powder is difficult to melt sufficiently, whereas when too high, the powder may be lost by heat. In addition, since the degree of oxidation is so severe that the mechanical properties of the coating layer is reduced, the heating temperature of the injection gas is preferably 500 to 15000 ° C.

Gas flow rate

In thermal spraying, hydrogen, argon, or a mixture thereof may be used as a gas for accelerating the powder. When using a conventional injection nozzle, the pressure of the injection gas immediately before the nozzle may be described as the flow rate per unit time of the gas. have. The flow rate is a factor that determines the proper flight speed and flight time for the injector to fly, and in order to maintain the molten state for the time until the injector is stacked, argon (Ar) is preferably in the range of 0 to 125 SCFH. Since hydrogen acts as a heat source, it is only necessary to use an appropriate amount depending on the heating temperature of the powder, and there is no need to specifically limit the flow rate. If the flow rate range of the argon gas is less than the reference, the flight speed of the powder is significantly low, so that it stays in the hot gas flow field for a long time. Therefore, a phenomenon such as phase change of powder particles due to thermal damage occurs. On the contrary, if the pressure range is higher than the standard, sufficient residence time in the gas flow field may not be secured, resulting in a collision with the base metal before melting, and thus the coating layer may not be efficiently laminated.

Diameter of powder particles

The diameter of the powder is an important factor in determining the coatability. In the case of thermal spraying, if the diameter of the particle is too small, the damage of the particle due to heat damage in the gas flow field, which is a high temperature environment, can be serious, and if the particle diameter is too large, It does not melt enough and the lamination is not good. Therefore, although the diameter of particle | grains is preferable to use the thing of a fixed range, it is preferable that the range of the diameter per effective particle spherical form is 5-200 micrometers.

(Low Temperature Spray Coating Conditions)

Low-temperature spray coating is a method of coating the powder on the subject by using the kinetic energy of the powder accelerated to a high speed instead of melting the powder to be sprayed, unlike the thermal spray coating. 4 shows a schematic form of a low temperature spray coating apparatus which is generally used to explain the low temperature spray coating method in more detail.

As shown in FIG. 4, the low temperature spray coater includes a gas supply device, a control panel, a gas heating device, a powder supply device, and a de Laval nozzle. The gas supplied from the gas supply device is controlled by the amount of gas in the control panel, and divided into a gas heating device and a powder supply device. The gas heating device heats the gas to a high temperature to induce a speed increase due to the expansion of the gas, and the powder feeding device supplies the powder to the gas supplied from the control panel so that the powder can be supplied to the DeLaval nozzle by the gas. Play a role. Immediately after the powder feeding device, a powder heating device for heating the powder may be provided. The powder heating device is a device for heating the powder by mounting a heating element on the outside of the tube through which the powder passes, and serves to increase the temperature of the powder to increase the deformation and toughness of the powder when the powder collides with the subject. Immediately before the de Laval nozzle, a mixture of the powder and gas supplied from the powder feeder and the heated high-speed gas supplied from the gas heater meet to form a high-speed gas / powder mixture to form a high-speed gas through the DeLaval nozzle. Sprayed by powder jets. DeLaval nozzle is a nozzle that is used to increase the speed of the gas to the supersonic speed above the speed of sound as it has a form that the inner diameter of the nozzle is reduced (converge) and then diverged again when viewed in the nozzle length direction. The powder transported by the gas injected at supersonic speed through the de Laval nozzle collides with the subject at a high speed close to the velocity of the gas, and the kinetic energy of the powder is converted into the energy required for the coupling between the subject / powder. Thus, a powder-coated subject can be obtained.

In this case, the conditions for the low temperature spray coating may be carried out according to a known low temperature spray coating method, but the conditions of the low temperature spray coating, which are particularly advantageous for thin plate production as in the present invention, are as follows. It is more preferable to control the pressure, the diameter of the powder particles, and the like. Hereinafter, the above conditions will be described in detail.

Temperature of gas

Although it may vary slightly depending on the type of injector and the kind of intermediate, in general, the injection gas is preferably heated in a gas preheater at a temperature of 200 to 850 ° C. during low temperature spray coating. Since the injection gas serves to adiabaticly expand at the nozzle outlet to impart kinetic energy to the powder particles, when the temperature of the injection gas is too low, it is difficult to obtain a sufficient acceleration effect of the powder. If the temperature is too high, the powder to be sprayed melts or is damaged, which is undesirable.

Gas pressure

In the low temperature spray coating, hydrogen, helium, argon, or a mixed gas thereof may be used. In this case, the pressure of the gas is preferably adjusted to 10 to 30 bar. The gas pressure is an important factor that allows the sprayed particles to have a sufficient energy to form a coating layer and at the same time to maintain the adhesion state even after being attached. When the pressure of the gas is less than 10bar, the particles to be sprayed do not have a critical velocity enough to stack, and thus do not adhere to the base material. On the contrary, when the pressure of the gas exceeds 30bar, it adheres to the base material. When it can be attached easily, but may not be able to withstand the repulsion energy due to the impact transmitted from the particles may be a phenomenon that peels off.

Diameter of injector particles

The diameter of the spray is an important factor in determining the coatability. In the case of low temperature spraying, if the diameter of the particle is too small, the kinetic energy of the particle is insufficient, so that the lamination rate during coating decreases. On the contrary, when the particle diameter is too large, the gas does not accelerate the particle sufficiently and the particle becomes difficult. It becomes difficult to coat. Therefore, although the diameter of particle | grains is preferable to use the thing of a fixed range, it is preferable that the range of the diameter per effective particle spherical form is 5-200 micrometers.

When selecting an appropriate coating method as described above, and employing the appropriate process parameters it can easily form a coating layer for producing a thin plate to be prepared in the present invention.

The metal sheet produced by the above process can be used as such, but may be contracted while being cooled after the powder is coated to manufacture the sheet, since the thermal expansion rate with the intermediate layer present at the bottom during cooling is different. Stress may be generated during shrinkage. Therefore, in some cases, there is a possibility that the thin plate is weak enough to be unsuitable for use in a predetermined use, and therefore, it is more preferable to perform a heat treatment to remove the residual stress applied to the thin plate.

Since the heat treatment conditions vary depending on the type of material used, it is difficult to uniformly specify the temperature, treatment time and atmosphere. However, it is preferable to carry out according to the tempering conditions set for each material. The term "tempering" means that a person having ordinary knowledge in the technical field to which the present invention belongs can easily change the temperature and the holding time, etc. according to each type of material, and specifically define the conditions in the present specification. There is no need to do it.

However, in the case of the material usable in the present invention, the tempering heat treatment may vary slightly depending on the physical properties of the material, but is preferably performed at a temperature of 200 to 1500 ° C. for 1 to 24 hours. If the tempering heat treatment temperature is too high, there is a possibility that deformation may occur in the material by a process such as phase transformation of the material, which is not preferable. On the contrary, when the temperature is too low, it is difficult to obtain a residual stress removing effect. In addition, when the tempering heat treatment time is too short, it is not possible to obtain a sufficient residual stress removal effect, on the contrary, if the heat treatment time is too long, even if longer effects can be obtained because the maintenance time is long, it may cause an increase in manufacturing cost.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, it is necessary to note that the following examples are intended to illustrate and illustrate the present invention, but not to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the claims and the matters reasonably inferred therefrom.

(Example)

Thermal spray coating

A cylindrical thin plate was manufactured by using a thermal spray coating method through the following process.

As a support for the thin plate manufacturing, a stainless steel sheet made of STS 430 having a thickness of 1 cm was used. NaCl powder was coated on the surface of the support to a thickness of about 100 μm by a thermal spraying method to prepare a subject required for thermal spraying coating.

Thereafter, aluminum powder having a particle size distribution in the range of 50-80 μm in diameter was sprayed. The coating equipment was a type of equipment similar to that shown in FIG. 1, using an APS (Arc Plasma Spray) equipment manufactured by Sultz-Meco, USA, and hydrogen and argon were used as injection gases. The temperature of the used gas was controlled in the range of 12000 ~ 15000 ℃, the gas flow rate was 100 SCFH for argon, hydrogen was 5 SCFH.

 In addition, the distance between the nozzle and the substrate was set to about 100 mm, and the front coating was performed while moving the nozzle at a speed of 200 mm / s so that aluminum particles could be coated without gaps.

 A photograph of the support / NaCl / thin coating layer laminate prepared by the above method is shown in FIG. 5. As shown in FIG. 5, NaCl, which is an intermediate layer, is linearly stacked on a support, and aluminum is coated thereon to form a round cylindrical thin plate. And Figure 6 is a photograph after separating the thin aluminum plate after dissolving by adding water to the NaCl layer.

As can be seen in the drawings, it can be seen that a cylindrical thin plate having a form similar to that of the support can be easily produced by the present invention.

(Low temperature spray coating)

A cylindrical thin plate was manufactured by using a low temperature spray coating method through the following procedure.

As a support for the thin plate manufacturing, a stainless steel plate made of 1 cm thick STS 430 material was used. Lead, which is a low melting point metal, was coated on the surface of the support to a thickness of about 100 μm by a thermal spraying method to prepare a subject for thermal spraying coating.

Thereafter, a copper powder with a particle size distribution in the range of 50-80 μm in diameter was sprayed. The coating equipment used was a CGT 3000 low temperature spraying equipment of CGT, Germany, as a type of equipment similar to that shown in FIG. 4, and nitrogen and helium were used as injection gases. The temperature of the gas used was controlled in the range of 200 ~ 500 ℃, the pressure of the gas was controlled in the range of 10 ~ 25bar.

As can be seen in Figure 7, it can be seen that a flat sheet having a form similar to that of the support can be easily produced by the present invention.

Although shown in the present embodiment relates to a thin plate formed on a somewhat smaller cylindrical support or plate-shaped support in the experimental range, it is to be noted that the shape of the thin plate can be freely changed as the size and shape of the support is changed. Therefore, large flat sheets of large flat shape or thin plates of more complicated shapes can also be produced by the method of the present invention.

1 is a layout view showing the configuration of a thermal spray coating apparatus,

Figure 2 is a schematic diagram showing a process of heating the powder is sprayed during thermal spraying,

3 is a schematic diagram schematically showing an example of a nozzle used in a thermal spray coating;

4 is a layout view showing the configuration of a low temperature spray coating apparatus;

5 is a photograph of a laminate in which the tubular thin plates manufactured according to one embodiment of the present invention are stacked;

6 is a photograph of the result of removing the thin plate from the laminate of FIG. 5, and

FIG. 7 is a photograph of a laminate in which plate-shaped thin plates manufactured according to another embodiment of the present invention are stacked. FIG.

Claims (7)

Preparing a support; Applying an intermediate layer to the support surface; Spray coating the support on which the intermediate layer is applied to obtain a support on which a thin plate is laminated; Separating the thin plate by removing some or all of the intermediate layer from the thin plate coated support; Method for producing a thin plate comprising a. The method of claim 1, wherein the spray coating method is a thermal spray coating method or a low temperature spray coating method. The method of claim 2, wherein the intermediate layer is made of a water-soluble ceramic when the spray coating method is a thermal spray coating method. 4. The method of claim 3, wherein the intermediate layer made of the water-soluble ceramic is removed by adding water. The method of claim 2, wherein the intermediate layer is made of a low melting point metal when the spray coating method is a low temperature spray coating method. The method of manufacturing a thin plate according to claim 5, wherein the intermediate layer made of the low melting point metal is melted and removed. The method for manufacturing a thin plate according to any one of claims 1 to 6, further comprising a tempering treatment on the thin plate obtained after the separating of the thin plate.

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