KR20070021860A - Al2O3-TiO2 SYSTEM COATING LAYER HAVING EXCELLENT WEARABILITY MANUFACTURED BY PLASMA SPRAYING - Google Patents

Abstract

The present invention relates to a coating layer produced by a plasma spraying method, and in particular, an object of the present invention is to provide an Al ₂ O ₃ -TiO ₂ -based coating layer excellent in wear resistance.

As a constitution for achieving the object of the present invention, the present invention is a coating layer prepared by plasma spraying method using a ceramic powder containing 10 to 14% by weight of TiO ₂ and the remainder substantially Al ₂ O ₃ as a thermal spraying material, Provided is an Al ₂ O ₃ -TiO ₂ based coating layer having excellent abrasion resistance, characterized in that the content of TiO ₂ in the splat of the microstructure of the coating layer is 9 to 13% by weight.

By limiting the composition of the ceramic powder and the content of TiO ₂ in the splat of the coating layer, the thermal spray coating layer of the present invention exhibits very good wear resistance.

Thermal Spray, Coating Layer, Splat, Wear Resistance

Description

Alumina-titania-based coating layer having excellent abrasion resistance manufactured by plasma spraying method {Al2O3-TiO2 SYSTEM COATING LAYER HAVING EXCELLENT WEARABILITY MANUFACTURED BY PLASMA SPRAYING}

1A shows Al ₂ O ₃ and TiO ₂ Scanning electron micrograph showing the shape and size of the granulated powder prepared by using a spray drying method after mixing the nanopowder.

1b shows Al ₂ O ₃ and TiO ₂ It is a scanning electron micrograph of the granulated powder prepared by using the spray drying method after mixing the nanopowder.

2a shows Al ₂ O ₃ and TiO ₂ Scanning electron micrograph of the powder prepared by melting and grinding the components.

2b to 2e are Al ₂ O ₃ and TiO ₂ This figure shows the result of EDS mapping on powder manufactured by melting and grinding the components.

Figure 3a is an optical micrograph of the coating layer prepared by the plasma spray method using nano-assembly powder.

FIG. 3B is a scanning electron micrograph of the portion indicated by the arrow in FIG. 3A.

Figure 4a is an optical micrograph of the coating layer prepared by the plasma spray method using a commercial powder.

4b and 4c are scanning electron micrographs of the coating layer prepared by the plasma spray method using a commercial powder.

Figures 5a and 5c is a scanning electron microscope cross-sectional photograph of the wear cross-section after the wear test of the coating layer prepared by the plasma spray method using nano-assembly powder at the load of 5kgf and 20kgf, respectively.

5B and 5D are scanning electron microscope cross-sectional photographs of abrasion cross-sections of a coating material prepared by a plasma spray method using a conventional powder at a load of 5 kgf and 20 kgf, respectively.

6a and 6c are scanning electron micrographs of abrasion powder after abrasion test was carried out at a load of 20kgf coating layer prepared by the plasma spray method using nano-assembly powder.

6b and 6d are scanning electron micrographs of abrasion powder after abrasion test of a coating layer prepared by a plasma spray method using a conventional powder at a load of 20kgf.

7 is TiO ₂ It is a graph showing the change in the wear rate of the coating layer prepared by the plasma spray method using the nano-assembly powder according to the change of the component.

8 is a graph showing the change of the content of TiO ₂ in the splat of the thermal spray coating layer with the change of the content of TiO ₂ in nanopowder and commercial powder.

The present invention relates to a thermal spray coating layer, specifically Al ₂ O ₃ -TiO ₂ The present invention relates to a coating layer prepared by plasma spraying using a component powder.

Plasma spraying method which melts powdered thermal spraying material using high temperature plasma heat source and sprays it on substrate at high speed to produce coating layer has no restriction on the selection of materials compared to other thermal spraying methods It has speed and deposition efficiency, low fuel gas consumption, low cost, minimal preheating and cooling when spraying, and plasma system is technically and industrially proven for high reliability and application in production. This is an easy advantage.

In this regard, as a method for improving the surface properties of the bulk material, in particular hardness, strength, corrosion resistance, etc., a method of preparing a coating layer through the above-described plasma spraying method using a ceramic powder of several tens of micro-size Known. However, in this method, there is a problem that the bonding strength between the ceramic powder in the coating layer falls, there is much room for improvement in wear resistance and durability.

In addition, in order to prevent the bonding force between the ceramic powder of the coating layer from falling, a method of using nanopowder as a powder used for thermal spray coating is known, but this method also has an improvement in control of composition according to the kind of physical properties required for the coating layer. There is a lot of room.

The present invention is to improve the above-mentioned problems of the prior art, specifically, prepared by the plasma spray method, in particular Al ₂ O ₃ -TiO ₂ excellent in wear resistance It is a technical problem to provide a system coating layer.

The wear resistance of the coating layer produced by plasma spraying using Al ₂ O ₃ -TiO ₂ -based ceramic powder, which is known to be effective in improving ceramic powder, particularly wear resistance, corrosion resistance, and erosion resistance, can be partially melted in the coating layer. It is known that the volume fraction of the area and the hardness of the coating layer have a major influence, and based on this, there have been attempts to improve the wear resistance of the coating layer.

However, as a result of studies so inventors of field, factors affecting the wear resistance of the coating layer, as opposed to the prior known, the composition of TiO ₂ in the splat (splat) of the microstructure of the content of TiO ₂ and a coating layer, and a plasma The viscosity of the powder droplets formed during thermal spraying has a particularly large influence, and the known factors have not been found to have a large influence, thus completing the present invention.

A structure for achieving the object of the present invention, the present invention containing TiO ₂ 10~14% by weight and the remainder to a substantially ceramic powder Al ₂ O ₃ by thermal spraying material as a coating layer prepared by the plasma spraying method, It provides an Al ₂ O ₃ -TiO ₂ -based coating layer having excellent abrasion resistance, characterized in that the content of TiO ₂ in the splat (splat) of the microstructure of the coating layer is 9 to 13% by weight.

In the above configuration of the present invention, the content of TiO ₂ in the ceramic powder is 10 to 14% by weight, and at the same time, a shape in which a droplet is formed on the substrate during the splat of the thermal spray coating layer formed after plasma spraying. The content of TiO _{2 in} the)) is characterized in that 9 to 13% by weight.

As can be seen in Figure 7, when the TiO ₂ content of the ceramic powder is in the range of 10 to 14% by weight, the wear resistance of the plasma spray coating layer is significantly improved compared to the case out of the above range.

On the other hand, as will be described in detail in the following examples of the present invention, the wear resistance of the thermal spray coating layer largely depends on the bonding force at the splat interface. However, when the content of TiO ₂ in the splats is in the range of 9 to 13% by weight, the splats have sufficient wettability, thereby improving the bonding force at the splat boundary, and as shown in FIG. 7, Wear resistance is remarkably improved.

On the other hand, even if the content of TiO ₂ in the ceramic powder is in the range of 10 to 14% by weight, as shown in the commercial powder of FIG. 8, when the TiO ₂ content in the splat after spray coating is less than 9% by weight, it is known from FIG. As can be seen, wear resistance is poor.

When molten droplets impinge on a substrate and are flattened in the form of a disk during typical thermal spray coating, the detailed shape of the disk depends on the surface tension, density, viscosity, speed, etc. of the droplet. However, it is known that the viscosity of Al ₂ O ₃ -TiO ₂ -based liquid oxide gradually decreases as the content of TiO ₂ increases in the range of 2100 to 2300 ° C. Therefore, since the viscosity of the Al ₂ O ₃ -TiO ₂ droplets decreases when the content of TiO ₂ increases at the temperature during plasma spraying, the wettability of the ceramic droplets formed during the thermal spraying is greatly improved. Accordingly, the bonding force between the splat interface in the microstructure formed on the coating layer is significantly increased.

However, since the wear of the coating layer is largely dependent on the bonding force between the splat interfaces, the improvement of the bonding force of the splat interface leads to the improvement of the wear resistance of the coating layer. Accordingly, the present invention by not only the content of TiO ₂ in the powder used as a sprayed material, only the content of TiO ₂ in the splat of a coating layer coating after spraying, it is possible to wear a stable provided with an excellent coating layer.

On the other hand, when the content of TiO ₂ in the splat is less than 9% by weight, the viscosity of the Al ₂ O ₃ -TiO ₂ -based liquid oxides formed during the thermal spray coating is high, so that the wettability of the droplets during plasma spraying decreases, so Adhesion is also lowered, thereby significantly reducing the wear resistance of the coating material. On the other hand, when the content of TiO ₂ in the splat exceeds 13% by weight, the wettability of the droplets is improved, but the content of TiO ₂ is excessively high, which adversely affects wear resistance.

Also, in the powder used as the thermal spraying material, when the content of TiO ₂ is less than 10% by weight, the content of TiO ₂ in the splat is not more than 9% by weight, and the content of TiO _{2 in} the thermal spraying powder is 10% by weight. Must be at least% Similarly, in the powder used as the thermal spraying material, when the content of TiO ₂ exceeds 14% by weight, the content of TiO ₂ in the splat also exceeds 13% by weight, so the content of TiO _{2 in} the thermal spraying powder is 14% by weight. It is preferable that it is% or less.

In addition, the present invention is to make a granulated powder by mixing TiO ₂ nano powder and Al ₂ O ₃ nano powder to contain 10 to 14% by weight of TiO ₂ nano powder, prepared by a plasma spraying method using the granulated powder as a thermal spraying material As the coating layer, an Al ₂ O ₃ -TiO ₂ based coating layer having excellent abrasion resistance is characterized in that the content of TiO ₂ in the splat (splat) of the microstructure of the coating layer is 9 to 13% by weight.

The above structure of the present invention, as a powder used as the thermal spraying material, by using the nano-powder, it is possible to ensure uniformity between the composition of TiO ₂ and Al ₂ O ₃ , segregation of TiO ₂ in the coating layer formed after the thermal spraying It can be easily prevented, and the content of TiO ₂ in the splat also has the effect of being easy to control.

In addition, the present invention provides an Al ₂ O ₃ -TiO ₂ -based coating layer having excellent abrasion resistance, characterized in that in the above-described coating layer, there is no layer TiO ₂ segregated at the splat interface.

As described in detail in the following Examples of the present invention, the TiO ₂ segregation layer present at the splat interface becomes a starting point of cracking during wear and easily propagates, causing a significant decrease in the wear resistance of the coating layer. Therefore, the coating layer of the present invention can be more improved wear resistance because the TiO ₂ segregation layer does not exist at the splat interface.

Hereinafter, the present invention will be described in more detail based on the embodiments of the present invention. However, the following examples are merely examples and should not be construed as limiting the present invention.

EXAMPLE

The nano powders used in the present invention are Al ₂ O ₃ (melting point: 2070 ° C.) and “P25” TiO ₂ (melting point) manufactured by Degussa (Frankfurt, Germany). : 1830 ° C.) powder. However, the average size of these Al ₂ O ₃ and TiO ₂ nanoparticles are very fine, about 13 and ₂₁ nm, respectively, so that it is difficult to use them in the spray coating process.

Therefore, after the two nanopowders were mixed so that TiO ₂ had a predetermined fraction, it was prepared as a reconstituted powder having a size of 61 to 70 μm by spray drying, which was 900 ° C. Heat treatment was carried out for 1 hour.

As shown in FIG. 1A, the granulated powder is generally spherical, and the granulated powder is composed of a plurality of nano-sized particles, as shown in FIG. 1B, an enlarged view thereof.

On the other hand, for comparison with the coating layer made of nano-powder Al ₂ O ₃ -13wt% TiO ₂ powder of the brand name "Metco 130NS" manufactured by Schulzer metkosa (Hollen, Switzerland) by using a plasma spray method Prepared. The powder is a fused and crushed powder (hereinafter referred to as " commercial powder "), which is very irregular in shape as shown in FIG. 2A, and has an average size of about 35 mu m. And as can be seen in Figure 2b to 2e showing the EDS (Energy Dispersive Spectrometer) surface analysis results of the commercial powder, most of the powder is composed of Al and O components, around some powders Ti and O The component is detected. That is, some Al ₂ O ₃ powder is coated with 13% by weight TiO ₂ . In addition, TiO ₂ may also be present and are also Al ₂ O ₃ powder is not coated, that are present in less than TiO ₂ powder state is coated on the Al ₂ O _3. That is, in the case of the commercial powder used as the comparative example of this invention, the composition nonuniformity is high.

In the present invention, the atmospheric plasma spraying method is used among the plasma spraying methods. In this regard, the critical plasma spray parameter (hereinafter referred to as "CPSP") is represented by the expression of the plasma output in the molecular term and the flow rate of Ar gas in the denominator term. It is widely used as a variable to identify temperature qualitatively.

CPSP = Voltage [V] × Current [A] / Primary Gas (Ar) Flow Rate [psi]

The larger the output of the plasma, and the lower the flow rate of the Ar gas, the longer the residence time that the thermal spray powder is in the plasma flame, providing sufficient time for the powder to melt.

The CPSP was changed in the range of 320 to 510 to prepare a coating layer using four kinds of nanopowders, and a coating layer using a commercial powder was also prepared for comparison thereto.

The thermal substrate was made of ordinary carbon steel (Fe-0.45C-0.3Si-0.75Mo-0.03P-0.035S), and was cut into 30 × 30 × 5mm for the purpose of abrasion test, and then ground both sides of the specimen. In order to improve the interfacial adhesion between the coating layer and the substrate before coating, blasting was performed with Al ₂ O ₃ grit (diameter: 0.6 to 1.4 mm) and ultrasonically washed with acetone and alcohol to remove impurities.

Plasma spray used 9 MB of Schulme Mekko, and used argon and hydrogen as fuel gas. In addition, the specimen holder was cooled by compressed air to prevent overheating of the specimen during the spraying process, and the feed rate of the spray gun was kept constant.

The coating layer was cut and polished perpendicular to the coating surface, and the microstructure was observed with an optical microscope and a scanning electron microscope. The phase and chemical components of the coating layer were analyzed by X-ray diffraction and EDS methods. The volume fraction of the phases and pores formed in the coating layer was quantified. In addition, the hardness of the coating layer was measured under a load of 300g using a Vickers microhardness tester.

On the other hand, the wear test was carried out by a pin-on-disc method based on ASTM G99-95a using a friction wear tester (model name: EFM-III-EN / F, Orientec). As the specimen counterpart, SiC was used in the form of a fin having a diameter of 5.0 mm and a radius of curvature of a fin tip of 2.5 mm. The coating layer was ground with a surface grinding machine to make the surface roughness constant at about 0.1 μm, and then used as a wear specimen in the form of a disk.

The abrasion specimen is abraded by mutual friction with the upper pin while the lower rotating shaft rotates while pressed from the top of the abrasion tester body. Abrasion test was carried out under dry conditions for 5 minutes at 5kgf or 20kgf pressure, 100rpm rotation speed at room temperature. The wear rate was calculated by measuring the weight before and after the wear, and converted to the amount of wear (m / m) using the formula of ASTM G99-95a.

In order to investigate the wear mechanism of the coating layer, the wear section and the wear debris of the specimen were examined by a scanning electron microscope after the abrasion test.

Figure 3a is a microstructure of the coating layer (CPSP = 369) prepared by the plasma spray method using the nano-powder as a thermal spraying material. A small amount of micropores is found in the coating layer, and the splat boundary is not apparent. Referring to FIG. 3B in which the partially melted region indicated by the arrow in FIG. 3A is enlarged, the region “A” is a region in which the nano powder is completely melted and the region “B” is partially in the nano powder. Melted area.

As such, the nano-coating layer shows a dual structure consisting of a partially molten region in which the melting point of TiO ₂ is lower than that of Al ₂ O ₃ and thus the melting point of the molten particles is not sufficiently high. The complete melting region is mainly composed of γ-Al ₂ O ₃ as a result of X-ray diffraction analysis, and the partial melting region is in the form of Al ₂ O ₃ dispersed in TiO ₂ matrix.

On the other hand, referring to Figures 4a to 4c showing a coating layer made of a commercial powder, unlike the coating layer made of nano-powder, the boundaries between the splats are observed relatively clearly, the partial melting region is hardly observed. The boundary of the splat has a smooth curved shape, and as shown in FIG. 4C, there may be Al ₂ O ₃ powder in which only the powder surface is melted to maintain a round shape. In addition, a small amount of vertical cracks and micropores generated in the vertical direction of the splat due to the stress generated as a result of rapid solidification after the spray coating are observed.

As a result of analyzing the white region around the splat boundary of the coating layer made of commercial powder by EDS, many Ti and O components were detected. This means that TiO ₂ coated or powdered around Al ₂ O _{3 as} shown in FIGS. 2A and 2B is distributed around the splat boundary without being sufficiently melted during spray coating. That is, the white region shown in FIGS. 4B and 4C is a region in which TiO ₂ is rich.

Analysis of the nanopowder coating layer and the commercial powder coating layer using an image analyzer (image analysis) and the volume fraction of pores using the Archimedes method were measured, and the results are shown in Table 1 below.

Quantitative Analysis Data of Plasma Coating Layer Using Al ₂ O ₃ -13 wt% TiO ₂ System Commercial and Nano Powder Coating layer CPSP Volume fraction (%) Coating thickness (㎛) Bulk Density (g / cm 3) α-Al ₂ O ₃ Partial Melting Area pore Nano powder 324 369 444 508 12.7 11.9 10.5 7.0 21.5 19.5 17.5 11.0 6.8 6.1 5.8 5.6 320 330 325 340 3.38 3.42 3.45 3.46 Common Powder 369 5.2 - 4.2 340 3.47

As shown in Table 1, in the nanopowder coating layer (CSCP = 369) and the commercial powder coating layer prepared under the same CSCP conditions, that is, the same heat input amount, the coating layer made of the commercial powder has little pores and no partial melting region. Also, the fraction of α-Al ₂ O _{3 in} the X-ray analysis results is low. This means that the commercial powder is more easily melted during the thermal spray coating than the nanopowder. The reason is that in the commercial powder, since TiO ₂ having a low melting point is coated around Al ₂ O ₃ , it is denser than the nanopowder. This is because the thermal conductivity of the thermal spray coating is superior to that of the nano powder.

The hardness and wear test results of the nanopowder coating layer and the commercial powder coating layer are shown in Table 2 below.

Vickers hardness and abrasion test results of plasma coating layer using Al ₂ O ₃ -13 wt% TiO ₂ commercial and nano powder Coating layer CPSP Vickers Hardness (VHN) Wear rate (㎣ / m) Nano powder 324 369 444 508 758 793 817 796 0.106 0.071 0.058 0.056 Common Powder 369 842 0.196

* Abrasion rate was tested under 20kgf load

As shown in Table 2, the hardness of the nanopowder coating layer shows a maximum hardness 814 when the CPSP is 444, which is lower than the hardness 842 of commercial powder prepared under the same CPSP conditions. On the other hand, it can be seen that the nanopowder coating layer exhibits excellent properties 3 to 4 times compared to the commercial powder coating layer in wear characteristics.

In addition, as can be seen in Table 2, when forming the thermal spray coating layer with nano-powder, CPSP should be at least 370 as the thermal spraying conditions, which appears to depend on the degree of melting of the droplets during thermal spraying.

5A to 5D are scanning electron micrographs of the nano- and commercial powder coating layers prepared under the same CPSP (= 369) conditions, cut perpendicularly to the wear surface, to observe a wear cross section. As shown in FIGS. 5A and 5B, both coating layers crack at the splat boundary under 5 kgf load, or the splat itself breaks and wear progresses.

However, the wear surface of the nanopowder coating layer is flatter than the wear surface of the commercial powder coating layer, and the number of cracks present in the area under the wear surface is small (see FIG. 5A). On the contrary, it can be seen that white TiO ₂ rich regions exist along the splat boundary under the wear surface of the commercial powder coating layer, and cracks starting from the wear surface progress deeply along the splat boundary.

In addition, as shown in 5c and 5d, under 20 kgf load, cracking under the wear surface occurs more severely under 5 kgf load, especially in the case of commercial powder coating layer, peeling occurs more severely along the splat boundary than in the nano powder coating layer, and wear Shaving rough (see FIG. 5D).

6a to 6d are scanning electron micrographs of the wear particles observed after the abrasion test under a load of 20kgf. Very fine particles are observed on the surface of the wear powder of the nanopowder coating layer, which shows a fairly rough shape (see FIG. 6C). On the other hand, the wear powder of the commercial powder coating layer is often peeled off along the splat boundary, as shown in FIG. 6D, and has a smooth surface (arrow of FIG. 6D).

In summary, as described above (see FIGS. 2A to 2E), Al ₂ O ₃ and TiO ₂ are uniformly distributed, and after spray coating, TiO ₂ segregates along the boundary, and the segregated TiO ₂ deteriorates the boundary of the splat, which can be said to cause a decrease in the wear resistance of the coating layer.

In contrast, TiO ₂ is not segregated at the boundary of the splat in the case of the coating layer made of nanopowder. Therefore, it can be seen that the segregation of TiO ₂ at the boundary of the splat is one cause that affects the wear resistance of the coating layer. have.

Therefore, even in the case of commercial powders, which are usually manufactured in the size of several tens of micrometers, if Al ₂ O ₃ and TiO ₂ are uniformly produced, it can be seen that they can exhibit wear resistance similar to that of nanopowders.

On the other hand, the increase in the interfacial bonding force between the splats of the conventional spray coating layer is known to be due to the prevention and bending of crack propagation by the partial melting region. However, looking at the results of Tables 1 and 2, despite the decrease in the volume fraction of the partial melting region, the wear resistance was rather increased.

In this regard, the Al ₂ O ₃ -TiO ₂ -based spray coating layer was prepared under the same CPSP (= 369) by changing the composition of TiO _{2 in} the nanopowder, and subjected to quantitative analysis, hardness and abrasion test of the microstructures. As a result, it was as Table 3 below.

Quantitative Analysis, Hardness and Abrasion Test Results of Nano Powder Al ₂ O ₃ -TiO ₂ Spray Coating TiO ₂ content (wt%) Bulk Density (g / cm 3) Volume fraction (%) Vickers Hardness (VHN) Wear rate (㎣ / m) α-Al ₂ O ₃ pore 0 5 8 10 13 15 3.15 3.18 3.26 3.32 3.42 3.47 23.2 18.1 16.8 15.5 11.9 7.9 10.1 9.2 7.0 6.7 6.1 5.8 703 844 817 794 793 794 2.127 0.569 0.457 0.185 0.071 0.466

As can be seen from the Figure 7 showing the results, when the thermal spray coating by using only the Al ₂ O ₃ powder without TiO ₂ has low hardness, and abrasion resistance nappeujiman, TiO increased ₂ content of more wear rate is reduced, TiO ₂ is After showing the minimum at 13% by weight, wear resistance decreases when TiO ₂ exceeds 14% by weight again.

And as can be seen from the value in parentheses showing the hardness in Figure 7, in the Al ₂ O ₃ -TiO ₂ -based nano-powder spray coating layer according to the present invention, it can be seen that the hardness and the wear resistance has little correlation.

Figure 8 shows the results of measuring the content of TiO ₂ present in the splats of the spray coating layer prepared by nano powder and commercial powder using the EDS quantitative analysis method. As shown in FIG. 8, in the case of the spray coating layer made of nanopowder, the content of TiO ₂ in the splat and the content of TiO ₂ contained in the mixed powder are almost similar. However, in the case of the spray coating layer prepared by commercial powder, a large difference occurs in the content of TiO _{2 in} the powder and the splat. This difference seems to depend on the uniformity of the composition in the thermal spray powder. Therefore, it is very important to make the composition of the thermal spray powder uniform.

On the other hand, the viscosity of Al ₂ O ₃ -TiO ₂ -based liquid oxide is known to decrease as the content of TiO ₂ increases at 2100 ~ 2300 ℃. That is, since the viscosity of the droplets decreases as the content of TiO ₂ increases, the wettability (wettablity) is improved with this, and thus the binding force between the splats is also improved.

That is, as shown in Fig. 8, since the content of TiO ₂ in the splat is only 8.7% by weight in the thermal spray coating layer made of Al ₂ O ₃ -13% by weight TiO ₂ commercial powder, The wettability of the enemy is also significantly lower than that prepared with nanopowder, and as shown in FIG. 7, the wear resistance of the sprayed coating layer formed is inferior to that of the nanopowder.

On the other hand, if the content of TiO ₂ in the powder used as the thermal spraying material is lower than 10% by weight, the content of TiO ₂ in the splat is also low, resulting in poor wettability of the splat. Due to this, the bonding force between the splats of the formed coating layer is lowered, and the wear resistance seems to be lowered. On the other hand, if the TiO ₂ content of the powder used as the spraying material is higher than 14% by weight, the cause is not known precisely, but despite the good wettability of the splat, the wear resistance of the coating layer itself is reduced by excessive TiO ₂ content. see. Therefore, the content of TiO ₂ contained in the thermal spray powder is preferably 10% by weight to 14% by weight.

In accordance with the present invention, the thermal spray coating layer is not only excellent in corrosion resistance and erosion resistance, but also particularly excellent in wear resistance.

Claims (10)

A coating layer prepared by a plasma spray method containing 10-14% by weight of TiO ₂ and the remainder of which is substantially Al ₂ O ₃ as a thermal spraying material. the content of the _two is excellent in wear resistance, characterized in that 9-13% by weight Al ₂ O ₃ -TiO ₂ based coating. The Al ₂ O ₃ -TiO ₂ based coating layer of claim 1, wherein the ceramic powder is made by melting and pulverizing TiO ₂ and Al ₂ O ₃ . TiO ₂ nanopowder and Al ₂ O ₃ nanopowder are mixed to contain 10 to 14% by weight of TiO ₂ nanopowder to make granulated powder, and this coating layer is manufactured by plasma spraying using the granulated powder as a spraying material. The Al ₂ O ₃ -TiO ₂ based coating layer having excellent abrasion resistance, characterized in that the content of TiO ₂ in the splat of the microstructure of 9 to 13% by weight. Any one of claims 1 to A method according to any one of claim 3, wherein in the splat interface, Al ₂ O excellent wear resistance, characterized in that the TiO ₂ layer does not have the segregation ₃ -TiO ₂ based coating is wear resistant Al ₂ Excellent O ₃ -TiO ₂ -based coating layer. 4. The Al ₂ O ₃ -TiO ₂ -based coating layer having excellent abrasion resistance according to claim 3, wherein the granulated powder is made by a spray drying method. The Al ₂ O ₃ -TiO ₂ -based coating layer having excellent abrasion resistance according to claim 5, wherein the granulated powder produced by the spray drying method has a size of 61 to 70 μm. The Al ₂ O ₃ -TiO ₂ -based coating layer having excellent abrasion resistance according to claim 6, wherein heat treatment is further performed at 900 ° C. for 1 hour after the spray drying method. The Al ₂ O ₃ —TiO ₂ based coating layer having excellent abrasion resistance according to claim 6 or 7, wherein the average size of the nanoparticles is 10 to 50 nm. Claim 3, claim 5, claim 6, and claim 7 according to any one of claims, wherein the plasma thermal spraying is air plasma spraying method, and the fuel gas is excellent in wear resistance, characterized in that hydrogen and argon Al ₂ O ₃ - TiO ₂ coating layer. 9. The Al ₂ O ₃ -TiO ₂ -based coating layer having excellent abrasion resistance according to claim 8, wherein the critical plasma process variable (CSCP) of the plasma spraying method is 370 to 510.

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