KR20180061385A - Highly homogeneous thermal spray powder and method for manufacturing the same - Google Patents

Abstract

Disclosed is a high fluidity powder and a coating method using the same that improve the flow characteristics of sprayed powder introduced into a spray gun to improve the quality of the spray coating film. The flow characteristics of the sprayed powder can be greatly improved by coating an organic monomer on the surface of the granular sprayed powder, the heat treated sprayed powder or the plasma sprayed sprayed powder. Further, the improved flow characteristics of the sprayed powder coated with the organic monomer can increase the cost competitiveness of the sprayed powder by extending the duration of use of the spray gun in coating yield and coating layer quality.

Description

Highly homogeneous thermal spray powder and method for manufacturing the same

The present invention relates to a high-velocity thermal sprayed powder and a method of manufacturing the same. More particularly, the present invention relates to a high-velocity thermal sprayed powder whose surface is coated with an organic monomer and a method for producing the same.

Ceramic spray coating technology using sprayed powder is applied to various fields. By industry, it is most actively applied to general machinery, semiconductor, liquid crystal, steel and printing industries. The market size of China, Korea and Singapore is expanding, and the market size of Asia as a whole is very promising technology which is growing to the same level as US and EU.

The spray coating method using sprayed powder includes arc spraying method, flame spraying method, high-speed flame spraying method, plasma spraying method, cold spray (CS) method, SPS method (Suspension plasma spraying), SPPS .

From the viewpoint of thermal spraying materials, stabilized zirconia (YSZ) used for thermal barrier coating, Al ₂ O ₃ for insulating material, and TiO ₂ for photocatalyst are being actively developed and sold. In Japan, Abatite is also under development for application as a spray coating material with high added value. Tungsten (W) is also an important material as a high-temperature material for plasma shielding of nuclear fusion shields or plasma fusion barriers in the nuclear field, and development of a thermal spray coating for this application is proceeding.

Ceramic spray coating technology has been widely applied to wear resistant material coatings for improving wear resistance, and wear resistant coatings by spray coating have sufficient mechanical strength. The thermal spray coating has a considerable level of thermal spraying material as the thermal spray coating material to enable control of friction and wear to withstand contact with the surface of the mating structure that comes into contact in the form of sliding, . These ceramic coatings can effectively control wear and friction, and applications in industrial fields are continuously expanding.

In the spray coating method, the largest influence on the quality of the spray coating film is to maintain the discharge speed of the sprayed powder discharged from the sprayed powder supply portion. If the speed of the sprayed powder is not kept constant during the spray coating, the uniformity of the sprayed coating film and the rate of occurrence of pores are deviated from the designed value, or the strength of the sprayed coating is adversely affected.

In addition, clogging phenomenon occurs when the spraying powder is discharged from the nozzle to the plasma or flame of the spray gun at the supply part of the spray gun of the spray gun. Like the phenomenon that occurs in an hourglass, it is a common problem that a powder at a limited inlet is generated in the dust release.

When the powder used for the spray coating is made into a slurry and the slurry is discharged and used, the clogging phenomenon can be suppressed and a discharge amount can be generated at a certain pressure.

However, the powder discharge using the slurry causes deterioration of the thermal sprayed coating due to the organic impurities contained in the slurry preparation.

In addition, the sprayed powder produced through spray drying causes deterioration of the sprayed coating due to the shape of the granules and the roughness of the granular surface.

Most of the sprayed powders currently applied are applied to spray coating by reducing the friction between the powders by controlling the center of gravity of the powder to the center of the spherical shape by sphering by spray drying method and reducing the clogging phenomenon.

However, there is a problem in that the cost of manufacturing the powder by adjusting the center of gravity of the powder to the center of the spherical shape is difficult.

In addition, the flow characteristics of the powder are low, leading to a deterioration of spray coating quality.

In Korean Patent No. 10-0669819 (filed on Aug. 19, 2003), powders were dispersed using a non-aqueous solvent at the time of slurry preparation, and the slurry was spray-dried using Y ₂ O ₃ , Al ₂ O ₃ , TiO ₂ -based, AlN-based, and nitride-based granular powders are produced. Then, the granulated powder is subjected to a sintering heat treatment to complete the production of the ceramic powder. In particular, it has been reported that the flowability of the conventional Y ₂ O ₃ raw material powder can not be measured and has a flow characteristic of 0.19 g / sec when the powder is produced by the spray drying method.

However, there is a limit to improve the flowability of the powder through the change of the powder production method, and the quality of the spray coating film is still not greatly improved.

Korean Patent Registration No. 10-0863697 (filed December 31, 2007) discloses that a spray coating film is formed by spraying a spray coating powder and a sealing organic material powder together to seal the spray coating film without any additional process.

The powder for spray coating is obtained by forming a sealing film on the outer surface of the ceramic powder and surrounding it, and heat-treating the sealing organic material powder in a state surrounding the outer surface. Wherein the ratio of the ceramic powder to the organic powder is 1: 0.1 to 0.3, further narrowing the range, and the content ratio of the ceramic powder and the organic powder is adjusted to 1: 0.2 to 0.5.

However, the prior art is for forming a sealing film of a thermal sprayed coating at the time of forming a thermal sprayed coating, and since a considerable amount of organic material is coated on the ceramic powder, the quality such as uniformity of the sprayed coating film is deteriorated due to occurrence of cohesion between the thermal sprayed powder .

In addition, there is a problem that the discharge of powder due to the clogging phenomenon occurring in the release of the sprayed powder is delayed, and the quality of the sprayed coating is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a high flowability powder having improved flow characteristics in the powdery state.

According to a second aspect of the present invention, there is provided a method of manufacturing a high-velocity thermal spray powder for achieving the first technical object.

According to an aspect of the present invention, there is provided a high-velocity thermal sprayed powder comprising granular powder and an organic monomer attached to a surface of the granular powder.

The granular powder may have any one selected from the group consisting of ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , AlN, HfO ₂ , TiO ₂ and stabilized zirconia.

The granular powder is a powder produced through a granulation process and is a high-velocity sprayed powder.

The granular powder is a high-velocity sprayed powder which is a powder surface-treated by plasma.

And the surface roughness of the granular powder surface-treated by the plasma is decreased.

And the surface of the granular powder is melted by the plasma to increase the surface density of the granular powder.

Wherein the granular powder is a high-velocity homogeneous sprayed powder which is stabilized zirconia.

And the content of the organic monomer is in the range of 0.05 wt% to 5.0 wt% with respect to the weight of the granular powder.

And the organic monomer is a high-velocity sprayed powder which occupies 5% to 100% of the surface area of the granule powder.

The organic monomer may have any one selected from the group consisting of an anionic surfactant, a cationic surfactant, a positive surfactant, and a nonionic surfactant.

The organic monomers include palmitic acid, tetraethyl orthosilicate, hexamethyldsiloxane, acrylic, styrene, ethylene, acrylamide, methacrylic acid, acrylates, vinyl carboxylic acid, acrylonitrile, propylene oxide, butyl _{acrylate, stearic acid (C 17 H 35} COOH), oleic acid (CH ₃ (CH ₂ ) ₇ CH═CH (CH ₂ ) ₇ COOH), eicosanic acid (C ₁₉ H ₃₉ COOH) and docosanoic acid (C ₂₁ H ₄₃ COOH) have.

According to another aspect of the present invention, there is provided a method for preparing a granule, comprising the steps of: preparing a granulated powder prepared by a granulation process; adding an organic monomer to a solvent to prepare an organic monomer solution; Mixing and mixing the powders, and coating the organic monomers on the surface of the granular powder while evaporating the solvent.

Wherein the granular powder is any one selected from the group consisting of ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , AlN, HfO ₂ , TiO ₂ and stabilized zirconia.

Further comprising a step of plasma-treating the sprayed powder after preparing the sprayed powder prepared through the granulation process.

Wherein the surface of the granular powder is melted by the plasma surface treatment to increase the surface density of the granular powder and reduce the surface roughness.

Wherein the granular powder is stabilized zirconia.

According to the present invention, there is an effect that an organic coating layer is formed on the surface of the sprayed powder to induce generation of a certain amount of static electricity (repulsive force) on the surface of the sprayed powder to prevent aggregation between powders.

Further, the flow characteristics of the powder are improved during the spray coating of the organic coated powder, and the clogging phenomenon is suppressed in the spray nozzle.

Further, the flow properties of the powder during spray coating are improved, thereby increasing the thickness uniformity of the spray coating film and reducing the surface roughness.

Further, by using the powder with improved flow characteristics, there is an effect that the continuous use time of the plasma spray gun for spray coating is prolonged.

Further, by using the powder having improved flow characteristics, there is an effect of eliminating the nozzle clogging phenomenon of the powder injector portion of the spray gun.

1 is a flowchart illustrating a process of coating an organic monomer on a sprayed powder according to an embodiment of the present invention.
2 is an electron microscope image of 300 times the granular powder in the range of 5 탆 to 25 탆 according to a preferred embodiment of the present invention.
Figure 3 is an electron micrograph of a 1000 times magnification of a granular powder in the range of 5 [mu] m to 25 [mu] m according to a preferred embodiment of the present invention.
Figure 4 is an electron micrograph of a 300 times magnification of the granular powder in the range of 15 [mu] m to 45 [mu] m according to a preferred embodiment of the present invention.
5 is an electron micrograph of a 1000 times magnification of a granular powder in the range of 5 [mu] m to 25 [mu] m according to a preferred embodiment of the present invention.
6 is an electron microscope image of a 300 times magnification of a powder surface-treated with a granular powder in the range of 15 to 45 mu m according to a preferred embodiment of the present invention.
7 is an electron microscope image at 1000 times of a powder surface-treated with a granular powder in the range of 15 탆 to 45 탆 according to a preferred embodiment of the present invention.
8 is a schematic view of a cross-section of an organic monomer-coated granule powder according to a preferred embodiment of the present invention.
9 is a schematic view of a section of a plasma-treated granular powder coated with an organic monomer according to a preferred embodiment of the present invention.
10 is a schematic view of an experimental apparatus for measuring the flow rate of a sprayed powder according to a preferred embodiment of the present invention.
11 is a cross-sectional view of a coating layer formed by spray coating using a sprayed powder according to a preferred embodiment of the present invention.
FIG. 12 is a cross-sectional image of a coating layer obtained by enlarging and measuring a dash circle region of FIG. 11 according to a preferred embodiment of the present invention.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating a process of coating an organic monomer on a sprayed powder according to an embodiment of the present invention.

Referring to FIG. 1, the sprayed powder is manufactured by a spray drying method which is a conventional method. Powder prepared by spray drying is powder in granular state and powder in the form of aggregate of fine powder.

Usually, the granular powder is calcined or calcined to be used as a spraying powder. The calcination process is performed at 1200 ° C. for 4 hours or less, and the calcination process is performed at 1600 ° C. for 4 hours or less, but the heat treatment process is performed in accordance with the required characteristics of the sprayed powder. Through such a process, a sprayed powder can be prepared.

In the present invention, the granular powder prepared through the calcination process or the baking process is prepared, and then the granular powder is put into the solution in which the organic monomer is dissolved. After the granular powder is introduced, the solution is stirred so that the granular powder is sufficiently dispersed in the solution.

When the granular powder is sufficiently dispersed in the solution, the solution is heated to evaporate the solvent. Subsequently, the coating of the organic monomer is completed on the surface of the sprayed powder so that the organic monomer is coated on the surface of the sprayed powder. Evaporation of solvent does not occur at a rapid rate, and heating is carried out in a hot water bath to uniformly heat the entire solution. The evaporation rate of solvent varies according to the total amount, but it is controlled by process optimization.

Once all of the solvent has evaporated, the sprayed powder becomes an apparent cohesive state. This can solve the coagulation state through a sieving process or a simple crushing process.

The coating amount of the organic monomer on the surface of the granular powder can be determined by controlling the amount of the organic monomer added during the preparation of the initial solution or the amount of the sprayed powder injected into the solution.

When the spray coating process using the granular powder is carried out, the granular powder is not discharged. Therefore, the density of the powder is increased through the calcining process or the baking process of the granular powder, and the roughness of the surface is reduced, so that the powder is used as a spraying powder which can cope with the spraying process. However, there is still a problem of powder discharge for the spray coating, which has a great influence on the quality of the spray coating film. Spray coating companies have know-how to process powder and determine the specification of sprayed powder for spray coating. However, problems such as discharge delay of powder during spray coating are always present.

2 is an electron microscope image of 300 times the granular powder in the range of 5 탆 to 25 탆 according to a preferred embodiment of the present invention.

FIG. 2 is an electron microscope image of granular powder prepared by a spray drying method, and granular powder having a size distribution ranging from 5 μm to 25 μm.

Figure 3 is an electron micrograph of a 1000 times magnification of a granular powder in the range of 5 [mu] m to 25 [mu] m according to a preferred embodiment of the present invention.

Referring to FIG. 3, the surface roughness of the granular powder is indirectly predicted to have a large surface roughness, and the granular powder is produced by calcining and firing.

In addition, the image of the electron microscope shows that the internal pores are at a considerable level, and the surface area of the powder is large, so that the generation of the static electricity due to the friction between the powders can be expected to be large. An excessive charge is generated on the surface of the granular powder, and the generation of contact between the powders occurs in a certain space, so that the granular powder easily aggregates.

As a result, if the sprayed granulated powder is injected into the spray gun for spray coating, the aggregated powder easily clogs. Therefore, since the discharge of the granular powder does not normally occur in the limited discharge hole, normal spray coating does not occur.

Usually, the granular powder is made suitable for spray coating by using a powder whose surface state is changed or the powder distribution is optimized by the firing process, but the quality of the spray coating or the coating efficiency is not improved.

Figure 4 is an electron micrograph of a 300 times magnification of the granular powder in the range of 15 [mu] m to 45 [mu] m according to a preferred embodiment of the present invention.

Referring to FIG. 4, an electron microscope image of the granular powder prepared by the spray drying method, and a granular powder having a size distribution ranging from 15 μm to 45 μm.

5 is an electron micrograph of a 1000 times magnification of the granular powder in the range of 15 to 45 mu m according to a preferred embodiment of the present invention.

Referring to FIG. 5, the size distribution of the granular powder is rightwardly upward, but the surface roughness of the granular powder is not reduced, and pores are present in the granular powder.

The size distribution of the granular powder is increased, and even if the spray coating is proceeded, the granular powder is hardly discharged. That is, even when the spraying powder size distribution is increased, the charge state occurring on the surface of the powder is caused by the tendency of the powder to aggregate.

6 is an electron microscope image of a 300 times magnification of a powder surface-treated with a granular powder in the range of 15 to 45 mu m according to a preferred embodiment of the present invention.

Referring to FIG. 6, an electron microscope image of a powder subjected to a plasma surface treatment of granular powder produced by a spray drying method, and a size distribution of a sprayed plasma sprayed powder is in the range of 15 to 45 μm.

7 is an electron microscope image at 1000 times of a powder surface-treated with a granular powder in the range of 15 탆 to 45 탆 according to a preferred embodiment of the present invention.

Referring to FIG. 7, it can be predicted that the surface of the plasma-treated granular powder is considerably smoothed and the surface density is improved, and the pores on the image are hardly visible.

8 is a schematic view of a cross-section of an organic monomer-coated granule powder according to a preferred embodiment of the present invention.

9 is a schematic view of a section of a plasma-treated granular powder coated with an organic monomer according to a preferred embodiment of the present invention.

8 to 9, this structure is a form in which the surfactant is adsorbed on the surface of the granular powder in a micelle structure. The micelle structure is a structure of an organic monomer in which a portion bonded to a powder surface is a hydrophobic portion and a portion in contact with air is adsorbed on a powder surface which is a hydrophilic portion. The organic monomer is dissolved by using water as a solvent, and when the spraying powder is added, the organic monomer is attached to the surface of the spraying powder. At this time, a portion of the organic monomer in contact with water is negatively charged, and a hydrophobic substance such as oil is in contact with the powder surface to form a micellar structure.

When the granular powder is put into the solution in which the organic monomer is dissolved, the organic monomers are bonded to the surface of the granular powder. When the solvent is water, the organic monomer of the lipophilic portion adheres to the surface of the granular powder, and the hydrophilic portion is located toward the solvent. In this state, the granular powder is dispersed in the solvent.

The sprayed powder is dispersed in a solution containing the organic monomer, and the solvent is slowly evaporated to obtain a sprayed powder coated with the organic monomer, whereby a sprayed powder coated with the organic monomer can be obtained.

The surface roughness of the granular powder coated with the organic monomer is not greatly decreased but the generation of frictional force between the granular powders is reduced due to the coating formed of the organic monomer and the amount of static electricity generated in the coating formed of the organic monomer The coagulation state is controlled.

Even in the case of plasma-treated granular powder, when a coating is formed with an organic monomer, agglomeration between the powders is controlled by reducing the frictional force between the granular powders.

10 is a schematic view of an experimental apparatus for measuring the flow rate of a sprayed powder according to a preferred embodiment of the present invention.

Referring to Fig. 10, there is shown a schematic view of a powder flow rate measurement apparatus comprising a sample cup 70 including a measuring funnel 100 into which a powder is loaded, and a specific gravity cup 60 containing free falling powder. The sample cup 70 and the specific weight cup 60 are spaced apart by a distance of 80 mm between the cups and the specific volume cup 60 has an inner volume of about 100 cc.

Standard measurement methods for fluidity characterization are specified in KS L 1618-4. This standard is the result of the task of "Establishment of KS Standard for Abrasive and Special Ceramic Products", which is part of the standardized academic research service project implemented by the Korea Standards Institution in 2002.

Most of the ceramic granules are made into granules due to handling problems. They are prepared by spray drying and granulation method, and the characteristics such as granule diameter, bulk density, drying loss and flowability of the granules are confirmed by standard methods.

Since the range of the diameter of the granular powder of ceramics mostly ranges from 20 탆 to 500 탆, this range is limited to several tens to several hundreds of micrometers, and most of the ceramic granules will be included in the diameter range of the granular powder.

The measurement procedure for measuring the flow of the powder is as follows. After the measurement sample for spraying is filled in the funnel for measurement 100, the sample is freely dropped through the powder discharge port 90 into the specific gravity cup 60. The time when the powder falls freely is measured, and a total of three measurements are averaged and calculated.

The flow rate F is calculated to three digits to the right of the decimal place according to the following formula, and after three measurements, three measurements are arithmetically averaged.

Here, F is the mass (g) Fluidity (g / s), w ₁ is a weight (g), w ₂ of the specific gravity cup (60) is the sum of the distance the sample on the specific gravity cup (60) and a specific gravity cup (60) , and t is the time (s, second) required for the sample to fall. That is, w ₂ -w ₁ is the mass of the sample freely falling in the specific gravity cup 60.

Example 1

A solution is prepared by using palmitic acid as an organic monomer material. 0.2 g of palmitic acid is prepared, and the solution is put into a beaker containing 200 ml of ethanol. The mixture is stirred for a sufficient time of about 0.5 hr to dissolve. Care should be taken not to excessively reduce the amount of ethanol in the process of dissolving palmitic acid.

10 g of stabilized zirconia granule powder is put into the ethanol solution in which palmitic acid is dissolved, and the mixture is stirred until the total amount of granular powder reaches 100 g. The size of the granular powder was in the range of 5 탆 to 25 탆, and the palmitic acid coating was carried out. Stirring was continued for more than one hour, until the granular powder could be dispersed in solution.

Subsequently, while the solution containing the granular powder was stirred and heated, the ethanol used as the solvent was evaporated to leave only the palmitic acid-coated granular powder. The granular powder coated with palmitic acid remained in a weakly coagulated state. To break it, the granulation was carried out using a sieving process.

The size distribution of the powder prepared by the above method was almost the same as the size distribution of the initial granule powder. Since the weight content of palmitic acid (CH ₃ (CH ₂ ) ₁₄ COOH) is 0.2 wt% with respect to the granulated powder, it does not substantially increase the size of the granulated powder.

The flow characteristics of the granular powder coated with palmitic acid prepared as described above were measured. In the case of stabilized zirconia granule powder before coating with palmitic acid, the flow characteristics are very low and the measured value is almost zero. On the other hand, the flow characteristics of the granular powders coated with palmitic acid were remarkably increased and the flow characteristics were measured at 1.0912 g / sec.

An electron microscope image of the granular powder coated with palmitic acid shows an image similar to the image of FIG. 2 to FIG. This is due to the fact that 0.2 wt% of palmitic acid has a very small coating thickness and is difficult to see by electron microscopy.

The surface roughness of the granular powder was measured to be 20 nm or more when the surface of the granular powder was microscopically measured using AFM and the surface roughness of the granular powder coated with palmitic acid was measured to be less than 20 nm As a result, the coating of palmitic acid on the granular powder surface can be confirmed indirectly.

The coating amount of palmitic acid is preferably 0.01 wt% to 5.0 wt% with respect to the isolated powder, but is not limited thereto.

Comparative Example 1

0.2 g of polystyrene as a polymer is prepared, and the mixture is poured into a beaker containing 200 ml of ethanol. Polystyrene is dissolved by stirring for 0.5 hour.

100 g of the stabilized zirconia granule powder was subjected to polystyrene coating in the same manner as in Example 1. The flow properties of the prepared polystyrene-coated stabilized zirconia granules were measured. The flow property value of the polystyrene-coated stabilized zirconia granule powder was measured to be 0.4453 g / sec.

The sprayed powder prepared as described above was loaded on a plasma gun, and sprayed with a sprayed powder to prepare a sprayed coating film. The surface of the sprayed coating was not uniform, and the part where the coating rapidly protruded was observed. It is presumed that the thermal spraying quality deteriorated due to clogging phenomenon or coalescence of the partial spraying powder during spraying of the sprayed powder. In order to improve the quality of the sprayed coating, it is necessary to improve the flow characteristics of the sprayed powder.

In addition, when the thermal sprayed coating is formed using the polymer-coated granular powder, the residual amount of carbon in the thermal sprayed coating may be increased, thereby deteriorating the quality of the thermal sprayed coating.

Comparative Example 2

0.2 g of the glycolic acid of a trimeric oligomer polymerized with a small number of molecules is prepared, and the mixture is poured into a beaker containing 200 ml of ethanol. The mixture is stirred and dissolved for a sufficient time of about 0.5 hr.

As in Example 1, the glycolic acid coating of the trimer was performed on 100 g of the stabilized zirconia granule powder. The flow characteristics of stabilized zirconia granules were investigated. The flow property value of the polystyrene-coated stabilized zirconia granule powder was measured to be 0.6521 g / sec.

The flow characteristics were improved to a small level compared to the polymer coated granules and the spraying powders applied to the spray coating showed good results.

Example 2

 0.2 g of palmitic acid is added to the beaker containing 200 ml of ethanol. The mixture is stirred for 0.5 hour to dissolve. Be careful to keep the amount of ethanol in the process of dissolving palmitic acid.

10 g of stabilized zirconia granule powder is put into the ethanol solution in which palmitic acid is dissolved, and the mixture is stirred until the total amount of granular powder reaches 100 g. The size of the granular powder was in the range of 15 탆 to 45 탆, and the palmitic acid coating was carried out. Stirring was continued for more than one hour, until the granular powder could be dispersed in solution.

The flow characteristics of the granular powder coated with palmitic acid prepared as described above were measured. In the case of stabilized zirconia granule powder before coating with palmitic acid, the flow characteristics are very low and the measured value is almost zero. On the other hand, the flow properties of the granular powders coated with palmitic acid were remarkably increased and the flow property value was measured to be 1.9084 g / sec.

The size distribution of the granule powder was increased, and it was confirmed that the granule powder coated with palmitic acid showed a considerable improvement in flow characteristics. This is presumed to be due to the fact that the electrostatic charge on the surface of the coated powder is smaller than the volume of the powder, which makes it easier to maintain the state of separation between the powders.

The spray coating process was performed using the granular powder coated with palmitic acid prepared as described above.

The coating amount of palmitic acid is preferably 0.01 wt% to 2.0 wt% with respect to the isolated powder, but is not limited thereto.

11 is a cross-sectional view of a coating layer formed by spray coating using a sprayed powder according to a preferred embodiment of the present invention.

FIG. 12 is a cross-sectional image of a coating layer obtained by enlarging and measuring a dash circle region of FIG. 11 according to a preferred embodiment of the present invention.

FIG. 12 is an enlarged image of the coating region 110, and shows a pore (or pore) inside the spray coating layer. FIG. 12 is a view showing a sample of the sprayed coating formed using the sprayed powder prepared in Example 2, ) Is very small. When the pore content of the spray coating layer was measured using the image analysis system of the spray coating layer using the granular powder in Example 2, the pore content of about 5% was measured.

A sprayed coating was prepared using the sprayed powder prepared in Example 1, and the pore content of the sprayed coating was measured at 6% or more. This shows that the properties of the sprayed coating can be controlled by controlling the flow characteristics of the sprayed powder.

Example 3

0.2 g of palmitic acid is added to the beaker containing 200 ml of ethanol. The mixture is stirred for 0.5 hour to dissolve. Be careful to keep the amount of ethanol in the process of dissolving palmitic acid.

10 g of stabilized stabilized zirconia granule powder treated with plasma is put into the ethanol solution in which palmitic acid is dissolved and the mixture is stirred until the total amount of powder reaches 100 g. The plasma-treated stabilized zirconia granule powder having a size ranging from 15 탆 to 45 탆 was subjected to a palmitic acid coating. Stirring was continued for more than one hour, until the powder could be dispersed in solution.

The flow characteristics of the granular powder coated with palmitic acid prepared as described above were measured. Plasma surface treated zirconia granulated powders before coating with palmitic acid have very low flow characteristics and the measured values are almost zero. On the other hand, the flow properties of stabilized zirconia granule powders treated with palmitic acid coated plasma were significantly increased and the flow characteristics were measured at 2.0152 g / sec.

The spray coating process was performed using the granular powder coated with palmitic acid prepared as described above. When the spray coating was performed using the powder prepared as described above and the spray coating film was evaluated, the internal content of the pore, which was the same level as that of the thermal spray coating film prepared in Example 2, was measured to be within 5%.

It can be seen that the organic monomer is coated on the surface of the plasma-treated granular powder and its flow characteristics are improved. This is due to the improved uniformity of the organic monomers coated on the powder surface.

The use time of the spray gun can be prolonged and the quality of the spray coating can be improved in the case of using the sprayed powder having improved flow characteristics. It is also easier to control the properties of the thermal spray coating.

Comparative Example 3

0.2 g of polystyrene is prepared, and the mixture is poured into a beaker containing 200 ml of ethanol, followed by stirring for a sufficient time of about 0.5 hr to dissolve.

Polystyrene coating was performed on 100 g of stabilized zirconia granulated powder subjected to plasma surface treatment in the same manner as in Example 1. The flow characteristics of the polystyrene - coated stabilized zirconia granules were also investigated. The flow property value of the polystyrene-coated stabilized zirconia granule powder was measured to be 0.4128 g / sec.

It can be confirmed that the selection of the coating material greatly influences the flow characteristics of the sprayed powder.

In addition to the organic monomer materials described above, the surface of the granular powder can be coated with tetraethyl orthosilicate (TEOS) or hexamethyldisiloxane. This also shows improved flow characteristics.

It is also possible to use at least one selected from the group consisting of styrene, acrylic, ethylene, acrylamide, methacrylic acid, acrylate, vinylcarboxylic acid, AN, PROPYLENE OXIDE, silicone macro, and butyl acrylate as an organic monomer, The surface of the powder can be coated.

In addition, stearic acid (C ₁₇ H ₃₅ COOH), oleic acid (CH ₃ (CH ₂ ) ₇ CH═CH (CH ₂ ) ₇ COOH), eicosanic acid (C ₁₉ H ₃₉ COOH) and docosanoic acid (C ₂₁ H ₄₃ COOH) may be selected to coat the surface of the granular powder.

The granular powder coated with the organic monomer is loaded on the spray gun, and the spray coating process is performed by discharging the powder from the spray gun with the flame. That is, the powder for spray coating may be a sprayed powder, and the sprayed powder may be a granulated powder coated with an organic monomer or a plasma treated granulated powder.

10: organic monomer 20: surface of granular powder
30: Granular powder 40: Plasma treated granular powder surface
50: Plasma treated granular powder
60: specific gravity cup 70: sample cup
80: distance between cups 90: powder outlet
100: measuring funnel 110: coating area

Claims (16)

Granule powder; And
And an organic monomer adhered to the surface of the granular powder. The method according to claim 1,
Wherein the granular powder is any one selected from the group consisting of ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , AlN, HfO ₂ , TiO ₂ and stabilized zirconia. 3. The method of claim 2,
Wherein the granular powder is a powder produced through a granulation process. The method of claim 3,
Wherein the granular powder is a powder surface-treated with plasma. 5. The method of claim 4,
Wherein the surface roughness of the granular powder surface-treated by the plasma is reduced. 5. The method of claim 4,
Wherein the surface of the granular powder is melted by the plasma to increase the surface density of the granular powder. The method according to claim 6,
Wherein the granular powder is stabilized zirconia. The method according to claim 1,
Wherein the content of the organic monomer is in the range of 0.05 wt% to 5.0 wt% with respect to the weight of the granular powder. The method according to claim 1,
Wherein the organic monomer occupies 5% to 100% of the surface area of the granular powder. The method according to claim 1,
Wherein the organic monomer is any one selected from the group consisting of an anionic surface active agent, a cationic surface active agent, a positive surface active agent, and a nonionic surface active agent. The method according to claim 1,
The organic monomers include palmitic acid, tetraethyl orthosilicate, hexamethyldsiloxane, acrylic, styrene, ethylene, acrylamide, methacrylic acid, acrylates, vinyl carboxylic acid, acrylonitrile, propylene oxide, butyl _{acrylate, stearic acid (C 17 H 35} COOH), oleic acid (CH ₃ (CH ₂ ) ₇ CH═CH (CH ₂ ) ₇ COOH), eicosanic acid (C ₁₉ H ₃₉ COOH) and docosanoic acid (C ₂₁ H ₄₃ COOH) High-velocity spraying powder. Preparing granular powder prepared through a granulation process;
Adding an organic monomer to a solvent to prepare an organic monomer solution;
Introducing and mixing the granular powder into the organic monomer solution; And
And coating the organic monomer on the surface of the granular powder while evaporating the solvent. 13. The method of claim 12,
Wherein the granular powder comprises any one selected from the group consisting of ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , AlN, HfO ₂ , TiO ₂ and stabilized zirconia. 13. The method of claim 12,
After the step of preparing the sprayed powder prepared through the granulation process,
Further comprising a plasma surface treatment of the sprayed powder. 15. The method of claim 14,
Wherein the surface of the granular powder is melted by the plasma surface treatment to increase the surface density of the granular powder and reduce the surface roughness. 16. The method of claim 15,
Wherein the granular powder is stabilized zirconia.

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