KR20200036213A - Method of fabricating crystalline coating using suspension plasma spray and crystalline coating fabricated thereof - Google Patents

Abstract

The present invention relates to a method for manufacturing crystalline coating using a suspension plasma spray method, and the crystalline coating manufactured thereby. Such coating is used as environmental shielding coating by having chemical resistance and phase stability at a high temperature as crystallinity increases. In the present invention, a coating layer having high crystallinity is provided by controlling the content of H2 and the content of distilled water in a solvent when using the suspension plasma spray method. By using the coating layer having high crystallinity, high temperature chemical stability, which is a conventional problem, is improved in the environmental shielding coating.

Description

Method for producing crystalline coating using suspension plasma spray method and crystalline coating produced thereby {METHOD OF FABRICATING CRYSTALLINE COATING USING SUSPENSION PLASMA SPRAY AND CRYSTALLINE COATING FABRICATED THEREOF}

The present invention relates to a method for producing a crystalline coating using a suspension plasma spray method and a crystalline coating produced thereby. Such a coating is used as a high temperature environmental shielding coating by having chemical resistance as crystallinity increases.

Materials applied to the defense industry, aerospace and high-tech industries are representative materials exposed to extreme use environments such as ultra-high temperature, high pressure, and chemical degradation. Therefore, the development of composite materials with heat resistance, light weight, and corrosion resistance for core component materials such as turbine engines and peripheral devices, and the technology to maintain and protect the materials are required. Among these composite materials, ceramic matrix composites (CMC) based on silicon carbide (SiC), which is durable and has high temperature stability, is an extremely high-temperature environment and can be used in various fields such as gas turbine engines and peripheral parts. It is attracting attention as a material. However, in the case of SiC, it is known that chemical deterioration such as erosion and oxidation may be accelerated in an environment repeatedly exposed to CMAS (calcium-magnesium aluminosilicate) or moisture in a high temperature environment of 1300 ° C or higher. Therefore, research on environmental shielding coating technology (EBC) is being conducted to suppress chemical deterioration at high temperatures and to protect Si-based CMC substrates from high temperature, moisture, high pressure fuel, and other oxidation and erosion environments.

The condition of the environmental shielding coating should sufficiently protect the substrate in an oxidizing atmosphere such as high temperature, high pressure moisture or CMAS. Therefore, it has excellent high-temperature corrosion resistance and heat resistance among the materials, and the coefficient of thermal expansion should be similar to that of the substrate material SiC.

Materials such as SiC and Si ₃ N ₄ are used as materials for aircraft turbine engines and generator turbines, and these materials are very vulnerable to moisture or oxygen and require chemical resistance at high temperatures. Since the use temperature is 1200 to 1800 ℃, chemical resistance (preventing chemical deterioration) at high temperature is necessary.

In the present invention, to solve the problems mentioned in the prior art, and to provide a coating layer with improved crystallinity.

In order to increase the crystallinity of the coating layer, it is intended to control the content of H _{2 and} the content of distilled water when using the suspension plasma spray method.

A method of manufacturing a crystalline coating using a suspension plasma spray method according to an embodiment of the present invention includes: preparing a suspension in which calcined yttrium silicate or calcined lanthanum rare earth silicate raw material powder is dispersed; Coating the suspension by spraying the suspension onto a base material using a Suspension Plasma Spray (SPS) method; And heat-treating the coated coating film.

The lanthanide rare earth elements are preferably La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

In the step of coating the suspension by spraying the suspension onto the base material using the suspension plasma spray method, Ar, N ₂ , H ₂ is used as the plasma forming gas, and in this case, H ₂ is preferably controlled to 10 wt% or less.

It is preferable that the H ₂ is controlled to 5 wt% or less.

In the step of coating the suspension by spraying the suspension onto the base material using the suspension plasma spray method, it is preferable to be controlled by using Ar and N ₂ as a plasma forming gas.

In the step of preparing the suspension, it is preferred that ethanol and distilled water are used as the solvent. The distilled water is preferably controlled to more than 0 and less than 20 wt%.

The distilled water is preferably controlled to 10 to 20 wt%.

The crystalline coating film according to an embodiment of the present invention is made of crystalline, and the coating film inhibits moisture or oxygen from penetrating into the base material. The base material is SiC or Si ₃ N ₄ .

The present invention provides a coating layer with high crystallinity by controlling the content of H _{2 and} the content of distilled water when using the suspension plasma spray method.

By using the coating layer having high crystallinity, an environmental shielding coating having improved high temperature and chemical stability, which is an existing problem, is provided.

Figure 1 shows a flow chart of a method for producing a crystalline coating using a suspension plasma spray method according to an embodiment of the present invention.
2 is a result of XRD analysis of the coating layer prepared under the spray condition of Condition 1 in Table 1.
Figure 3 shows the XRD analysis results of the coating layer produced according to an embodiment of the present invention.
Figure 4 shows the XRD diffraction analysis results of the coating layer of the coating layer prepared according to an embodiment of the present invention.
5 is a result of TEM analysis of the coating layer of process condition 1.
6 is a result of TEM analysis of the coating layer of process condition 4.
7 is a result of TEM analysis of the coating layer of process condition 7.
Various embodiments are now described with reference to the drawings, and like reference numbers throughout the drawings are used to indicate similar elements. For purposes of illustration, various descriptions are presented to provide an understanding of the invention. However, it is clear that these embodiments can be practiced without these specific details. In other instances, well-known structures and devices are presented in block diagram form in order to facilitate describing the embodiments.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention can be applied to various changes and may have various forms, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosure form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals are used for similar components.

The terms used in the present application are only used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to indicate the presence of features, steps, actions, components, parts or combinations thereof described in the specification, one or more other features or steps. It should be understood that it does not preclude the existence or addition possibility of the operation, components, parts or combinations thereof.

The present invention relates to a method for producing a crystalline coating using a suspension plasma spray method and a crystalline coating produced thereby. Such a coating is used as an environmental shielding coating by having chemical resistance and phase stability at high temperatures as crystallinity increases. The present invention provides a coating layer having high crystallinity by controlling the content of H _{2 and} the content of distilled water when using the suspension plasma spray method. By using the coating layer having high crystallinity, an environmental shielding coating having improved high temperature and chemical stability, which is an existing problem, is provided.

Figure 1 shows a flow chart of a method for producing a crystalline coating using a suspension plasma spray method according to an embodiment of the present invention.

As shown in Figure 1, the method of manufacturing a crystalline coating using a suspension plasma spray method according to an embodiment of the present invention, preparing a suspension in which calcined yttrium silicate or calcined lanthanum rare earth silicate raw material powder is dispersed (S 110); A step of coating the suspension by spraying the suspension onto a base material using a suspension plasma spray (SPS) method (S 120); And heat-treating the coated coating film (S 130).

In step S 110, a suspension in which raw material powder of calcined yttrium silicate or calcined lanthanum rare earth silicate is dispersed is prepared. The raw powders are mixed in a certain ratio, mixed through a ball mill, etc., and calcined at a high temperature to prepare the powder and use it to prepare a suspension.

Lanthanum rare earth elements are used from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

Ethanol and distilled water are used as solvents in preparing the suspension. In the present invention, distilled water is controlled as a solvent condition, and its content is also an important point. The content of distilled water is more than 0 and less than or equal to 20 wt%, preferably controlled to 10 to 20 wt%. Preferably it may be controlled to 10 to 15wt%, 5 to 15wt%.

In step S 120, the suspension is sprayed onto the base material and coated using a suspension plasma spray (SPS) method.

Suspension plasma spray (SPS) method uses a small-sized particle material in the form of droplets, compared to atmospheric plasma sprays using powdered raw materials, and the particle size of the sprayed droplets is as small as a few microns, resulting in atmospheric plasma spraying. Compared to this, a denser and higher density coating layer can be obtained.

In step S 120, Ar, N ₂ and H ₂ are used as the plasma forming gas.

In this case, control of the content of H ₂ is an important point in the present invention. In the present invention, H ₂ is preferably controlled to 10 wt% or less, preferably 5 wt% or less, and most preferably, H ₂ is not included. That is, it is preferable to use Ar and N ₂ as plasma forming gases in step S 120. This part will be described in more detail in the embodiments described below.

On the other hand, Ar is preferably controlled between 70 to 90 wt%, N ₂ is preferably controlled to 5 to 30 wt%, 10 to 20 wt%.

In step S 130, the coated coating film is heat treated. The heat treatment may be performed in various ways depending on the use and condition, and representatively, a fusion method by flame or a heating method by a lamp after forming a coating layer may be used, but is not limited thereto.

The base material on which the coating is made is characterized by being SiC or Si ₃ N ₄ , and these base materials are representative materials exposed to extreme environments such as ultra-high temperature, high pressure, and chemical deterioration. . It is used as core parts such as turbine engine and peripheral equipment.

In the present invention by the method described so far, it is possible to manufacture a crystalline coating film using a suspension plasma spray method. It is preferable that such a crystalline coating film has the following characteristics. This crystalline coating film is made of crystalline.

The base material of the coating film is coated on a base material such as a turbine or a generator as described above. The base material is made of SiC or Si ₃ N ₄ . The coating film ultimately improves the reliability of the base material by inhibiting moisture or oxygen from penetrating the base material.

So far, a method of manufacturing a crystalline coating film using a suspension plasma spray method according to an embodiment of the present invention and a crystalline coating film produced by such a method have been described. Hereinafter, the contents of the present invention will be further described together with specific examples.

As the coating substrate, a coin-shaped sintered silicon carbide (Silicon carbide, SiC, 99.9%, MAX-TECH, Korea) substrate having a thickness of 3 mm and a diameter of 1 inch was used. To increase the adhesion between the substrate material and the coating layer, the surface of the substrate was treated with sand blasting before coating, and then the surface roughness Ra value was measured using a surface profiler (Surface profiler, SJ-410, Mitutoyo, Japan). Μm (Ra) levels are shown. Then, after 30 minutes of ultrasonic cleaning with acetone, dried and sprayed.

The coating layer was prepared in a double layer structure consisting of a bond coat and a top coat. Si (99.9%, Vesta, Sweden) powder was used as the bond coat material, and Ytterbium disilicate (Yb ₂ Si ₂ O ₇ ) powder was used as the top coat. Yb ₂ Si ₂ O _{7 As} raw material powder for producing top coat, Yb ₂ O ₃ (99.9%, Materion, USA, 4μm) and SiO ₂ (99.9%, kojundo chemical, Japan, 4μm) powder 1: 2 ( mol. ratio), mixed for 6 hours through a ball mill, calcined at 1500 ° C for 12 hours, Yb ₂ Si ₂ O ₇ The powder was prepared. The calcination conditions were 1400 ° C, 1450 ° C, and 1500 ° C, respectively, and heat treatment was performed at a heating rate of 5 ° C / min for 12 hours, and then 1500 ° C conditions were selected and applied to the suspension preparation. A suspension having a particle size of about 4 μm was prepared by a ball mill method using zirconia balls for 24 hours by adding 0.5 wt% of dibuthyl phosphate as a dispersant to 10 wt% of Yb ₂ Si ₂ O ₇ and ethanol solvent 900 ml. The suspension for manufacturing the bond coat was prepared by preparing 10 wt% of Si powder in 900 ml of ethanol solvent, and at this time, 0.5 wt% of dibuthyl phosphate was added as a dispersant. The suspension for the bond coat was prepared through ball milling for 4 hours. At this time, the particle size was observed at a level of about 3 μm.

In the plasma spray coating process, a substrate was fixed on a rotating table, and rotated at 250 RPM to spray the suspension to prepare a coating layer. Before the bond coat and the top coat were prepared, the mixture was preheated through plasma irradiation for 70 times under a mixed condition of Ar and N ₂ gas (Ar: N ₂ = 80: 20). At this time, the surface temperature of the substrate material was 270 ° C. In order to deposit the bond coat on the surface of the substrate material, a Si bond coat layer was prepared by plasma spraying under conditions such as preheating. The top coat was intended to produce a coating layer composed of a composition of Yb ₂ Si ₂ O ₇ using a suspension made of calcined powder at 1500 ° C. At this time, Ar 60-80% of gas conditions, 10-20% of N _{2, and} 10-20% of H ₂ were flowed at 45 ml per minute, and coating was performed under the current condition of 230A. In another condition, to lower the plasma enthalpy, the hydrogen concentration was changed and sprayed. At this time, the hydrogen was sprayed by changing the concentration from 0% to 10%. In addition, suspension was prepared by adding 10% and 20% of distilled water to the ethanol of the solvent, respectively. Table 1 shows detailed process conditions.

The prepared coating layer was analyzed for phase formation behavior of the coating layer under the conditions of 40 kV, 200 mA, Cu-Kα radiation, and scan rate of 5 ° / min using X-Ray diffraction (RINT-2500HF, Rigaku, JAPAN). Did. In addition, in order to observe the formation of a fine structure for the coating sample for each condition, the coated specimen was cut using a diamond cutter, and the cross section was polished to a surface of 1 μm using a diamond suspension. After polishing, ultrasonic washing was performed for 30 minutes in ethanol, followed by drying in a dryer for 12 hours. Then, microstructure and composition were analyzed using a scanning electron microscope (JSM-6701F, ZEOL Co., Ltd., Korea) and EDS (JSM-6390, JELO, Japan). In addition, a specimen was prepared using a focused ion beam system (FIB, NOVA 200, Fei company Co., Ltd., Korea) to determine the microstructure and image formation behavior of the microregion of the coating layer, and a transmission electron microscope (Tecnai G2) F30 S-twin, AP tech Co., Ltd, USA) for microstructure and diffraction pattern analysis.

2 is a result of XRD analysis of the coating layer prepared under the spray condition of Condition 1 in Table 1. The gas mixing ratio in the coating spraying conditions at this time was Ar ₂ : N ₂ : H ₂ = 80: 10: 10%, and this is the case of using calcined powder at 1500 ° C. As a result of the analysis, a peak indicating Yb ₂ Si ₂ O ₇ was observed, but it is presumed that the fine particles or the amorphous particles are mixed because the broad peak is observed together. This is considered to be a peak generated by phase change and refinement of the raw material powder due to the high plasma energy.

In order to prepare a coating layer of high crystallinity Yb ₂ Si ₂ O ₇ , plasma enthalpy was lowered and sprayed. Conditions to reduce the content of hydrogen were applied by lowering the plasma enthalpy. At this time, the gas content was sprayed under the process conditions of Ar ₂ : N ₂ : H ₂ = 80: 15: 5. The detailed process conditions are shown in Condition 2 of Table 1. In addition, it was sprayed by adding distilled water in a suspension solvent while maintaining hydrogen at 5% for higher crystallinity. The process conditions were the same as those of conditions 3 and 4, and 10% and 20% of distilled water was added to the ethanol solvent, respectively, to prepare a suspension. The result of XRD analysis of the coating layer after the above process is shown in FIG. 3. The XRD analysis results of FIG. 3 are displayed according to each distilled water content under a spray condition of 5% hydrogen concentration. In the analysis result of 0% of the distilled water content of FIG. 3, when the concentration of hydrogen was reduced compared to condition 1, which is a general thermal spray condition, a relatively broad peak was decreased. In addition, in the suspension to which distilled water was added, as the content of distilled water increased, the broad peak content decreased and a crystalline Yb ₂ Si ₂ O ₇ peak was observed. In addition, it was observed that the crystalline Yb ₂ Si ₂ O ₇ increased in the suspension with distilled water. In order to prepare a higher crystal form of Yb ₂ Si ₂ O ₇ , spraying in which hydrogen was excluded was additionally performed. At this time, the process conditions are shown in Condition 5 of Table 1. Further, hydrogen was excluded, and 10% and 20% of distilled water was added to the suspension, respectively, and thermal spray conditions were shown in conditions 6 and 7 of Table 1. The XRD diffraction analysis results of the coating layer prepared under each process condition are shown in FIG. 4. In the thermal spray conditions where the content of distilled water was 0% and hydrogen was excluded, relatively high peaks of crystallinity of Yb ₂ Si ₂ O ₇ were observed than those of 5% of hydrogen and 20% of distilled water. In addition, under the spraying conditions to which distilled water was added, Yb ₂ Si ₂ O ₇ in the crystal phase was predominant, and under the spraying conditions of 20% distilled water, the crystallinity of Yb ₂ Si ₂ O ₇ peak similar to that of the raw material powder was shown. In order to manufacture Yb ₂ Si ₂ O ₇ with the highest crystallinity as a suspension plasma spray, it was confirmed that hydrogen is excluded, or distilled water is added to the suspension to spray the product with low plasma heat.

Crystalline Yb ₂ Si ₂ O ₇ in XRD analysis of each process condition For detailed image formation and microstructure analysis of the peaks and broad peaks in a more microscopic region, the thermal spray coating layer of 10% hydrogen under process condition 1 and the distilled water content in the suspension solvent under condition 4 are 20%, and the content of hydrogen is 5%. When the coating layer and the distilled water content in the solvent of condition 7 was 20%, and the hydrogen was excluded, the coating layer was subjected to TEM and EDS analysis, respectively. 5 is a result of TEM analysis of the coating layer of process condition 1. The structure of the coating layer was observed in various shapes, and as shown in the microstructure of Figure 6 (a), it showed a typical plasma spray coating type in which particles are deposited as droplets and stacked. In the photo of FIG. 5, a darker colored droplet layer was observed in areas A and D than the coating layer of other parts. The results of the electron beam diffraction pattern analysis of Part A are shown in (b). When looking at the diffraction pattern, it was found that a few nanometers of very fine particles and polycrystalline particles gathered to generate a diffraction ring. At this time, as a result of analyzing the diffraction pattern, it could be seen as fine Yb ₂ Si ₂ O ₇ of polycrystalline showing the diffraction surfaces of (021) and (201). When each of them was analyzed with a high resolution image, it was found that fine particles of about 7 nm were included. The results of the diffraction pattern at the position B in FIG. 5 are shown in (d). In this case, the crystalline form was not clearly visible and was observed as an amorphous form with a halo morphology, and the insignificant diffraction ring was estimated to be several nanometer fine particles. FIG. 5 shows a partial diffraction pattern (e) in the form of particles observed brighter than the surrounding coating layer at the position C. At this time, it was confirmed that the bright particle portion of the C region is a crystal phase of Yb ₂ SiO ₅ . At D position in FIG. 5, an amorphous phase in which fine particles of a crystalline phase are distributed can be observed. Based on this, it is shown that the fine particles of the crystalline form are mainly included in the amorphous, and it is shown that the crystalline particles such as the C region of FIG. 5 are distributed in a part of the coating layer.

Process condition 4 is a case of spraying with a relatively low plasma enthalpy by lowering the content of hydrogen and adding distilled water to a solvent to produce a higher crystallinity Yb ₂ Si ₂ O ₇ coating layer. A coating sample was prepared by adding 20% of distilled water to a gas concentration of Ar ₂ : N ₂ : H ₂ = 80: 15: 5 and a suspension solvent. As the content of hydrogen decreases and the content of distilled water increases, XRD analysis results show that Yb ₂ Si ₂ O ₇ It was observed that the peak was increased, and the relatively broad peak was decreased. In order to examine the effect of the addition of distilled water in detail, the results observed by performing TEM analysis are shown in FIG. 6. When the microstructure of FIG. 6 (a) is seen, it is seen that the coating in the form of a round particle rather than the coating layer in the form of a droplet is more than before the addition of distilled water. The results of analyzing the electron beam diffraction images at various positions are shown in FIG. 6. When the position A shown in (b) was viewed, particles of the crystalline phase were observed. (c) Particle morphology was observed inside the coating layer at position A. These particles showed a diffraction image of the crystal form of Yb ₂ SiO ₅ . This is seen as particles of the monoclinic system Yb ₂ Si ₂ O ₇ showing the crystal planes of (011) and (110) under the zone axis [010] condition. When the position of B in FIG. 6 was seen, a diffraction ring was seen, but it was found that amorphous and fine particles were formed by showing a shape like a halo nearby. In addition, when analyzing different parts, most of the crystalline particles are seen, and the proportion of the crystalline phase is higher than that of the coating layer under condition 1. It was found that a higher crystalline Yb ₂ Si ₂ O ₇ was observed in the sprayed coating layer by lowering the hydrogen concentration to 5% and adding 20% distilled water than when spraying with a hydrogen concentration of 10%.

The result of TEM analysis in FIG. 7 shows high crystallinity of Yb ₂ Si ₂ O ₇ In order to prepare the coating layer, hydrogen was removed and plasma spraying was performed. Excluding hydrogen and TEM analysis of a coating layer with a very low enthalpy spray condition of 20% distilled water. The diffraction pattern analysis results of the coating layer are shown in FIG. 7. It was found that a coating layer in the form of very small crystalline particles was formed at most locations. (a) shows the observation result of the diffraction image analysis at the position of A. At this time, in FIG. 7 (b), crystalline Yb ₂ Si ₂ O ₇ having diffraction surfaces of (201) and (001) was observed under the zone axis [010] condition. In addition, the A-like form was observed in most positions.

As can be seen from the above examples, it was found that in the present invention, a coating layer with improved crystallinity was produced through the control of hydrogen content and the addition of distilled water as a solvent. As the optimal condition, it was confirmed that the condition of adding distilled water without using H ₂ and preferably adding 20 wt% of distilled water was the optimal condition.

The description of the presented embodiments is provided to enable any person of ordinary skill in the art to use or practice the present invention. Various modifications to these embodiments will be apparent to those skilled in the art of the present invention, and the general principles defined herein can be applied to other embodiments without departing from the scope of the present invention. Thus, the present invention should not be limited to the embodiments presented herein, but should be interpreted in the broadest scope consistent with the principles and novel features presented herein.

Claims (12)

Preparing a suspension in which calcined yttrium silicate or calcined lanthanide rare earth silicate raw powder is dispersed;
Coating the suspension by spraying the suspension onto a base material using a Suspension Plasma Spray (SPS) method; And
Comprising the step of heat-treating the coated coating film,
Method for producing a crystalline coating using a suspension plasma spray method.
According to claim 1,
The lanthanide rare earth element is characterized in that La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,
Method for producing a crystalline coating using a suspension plasma spray method.
According to claim 1,
In the step of coating by spraying the suspension to the base material using the suspension plasma spray method,
Ar, N ₂ , H ₂ is used as the plasma forming gas, and in this case, H ₂ is controlled to 10 wt% or less.
Method for producing a crystalline coating using a suspension plasma spray method.
The method of claim 3,
Characterized in that the H ₂ is controlled to 5 wt% or less,
Method for producing a crystalline coating using a suspension plasma spray method.
According to claim 1,
In the step of coating by spraying the suspension to the base material using the suspension plasma spray method,
Characterized in that it is controlled by using Ar and N ₂ as a plasma forming gas,
Method for producing a crystalline coating using a suspension plasma spray method.
According to claim 1,
In the step of preparing the suspension,
Characterized in that ethanol and distilled water are used as a solvent,
Method for producing a crystalline coating using a suspension plasma spray method.
The method of claim 6,
The distilled water is characterized in that it is controlled to more than 0 and less than 20 wt%,
Method for producing a crystalline coating using a suspension plasma spray method.
The method of claim 6,
The distilled water is characterized in that controlled to 10 to 20 wt%,
Method for producing a crystalline coating using a suspension plasma spray method.
It is prepared according to the method of any one of claims 1 to 8,
Characterized by consisting of crystalline,
Crystalline coating film.
The method of claim 9,
The coating film is characterized in that to inhibit the penetration of moisture or oxygen to the base material,
Crystalline coating film.
The method of claim 10,
The base material is characterized in that the SiC or Si ₃ N ₄ ,
Crystalline coating film.
Preparing a suspension in which calcined yttrium silicate or calcined lanthanide rare earth silicate raw powder is dispersed;
Coating the suspension by spraying the suspension onto a base material using a Suspension Plasma Spray (SPS) method; And
And heat-treating the coated coating film,
Ar, N ₂ is used as a plasma forming gas in the step of spraying and coating the suspension on the base material using the suspension plasma spray method,
In the step of preparing the suspension, using ethanol and distilled water as a solvent,
The distilled water is characterized in that controlled to 10 to 20 wt%,
Method for producing a crystalline coating using a suspension plasma spray method.

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