阅读说明：本技术 具有包含TaC的涂层的碳材料及其制造方法 (Carbon material having coating layer comprising TaC and method for producing same ) 是由 曺東完 于 2018-04-27 设计创作，主要内容包括：本发明涉及在碳基材上形成有包含TaC(碳化钽)的涂层的碳材料及其制造方法,本发明的具有包含TaC的涂层的碳材料包括碳基材；及在所述碳基材上形成的,由XRD分析的X线回折所发生的(111)面的回折峰值为最大值的包含TaC的涂层。(The present invention relates to a carbon material having a coating layer containing TaC (tantalum carbide) formed on a carbon substrate and a method for producing the same, the carbon material having a coating layer containing TaC of the present invention includes a carbon substrate; and a coating layer containing TaC formed on the carbon substrate, wherein the folding peak value of the (111) plane generated by X-ray folding of XRD analysis is maximum.)

1. A carbon material having a coating comprising TaC, comprising:

A carbon substrate; and

A coating layer containing TaC formed on the carbon substrate, wherein a folding peak of a (111) plane generated by X-ray folding of XRD analysis is maximum.

2. The carbon material having a coating layer comprising TaC according to claim 1, wherein a ratio of a (111) plane inflection peak to a (200) plane inflection peak occurring by X-ray inflection of the coating layer comprising TaC is 0.40 or less.

3. The carbon material having a coating comprising TaC according to claim 1, wherein the XRD analysis of the coating comprising TaC has a half-width of the polyline below 0.15 °.

4. The carbon material having a coating layer containing TaC according to claim 1, wherein the surface hardness of the coating layer containing TaC is calculated according to the following numerical formula 1,

Mathematical formula 1

Surface hardness value (GPa) is-38A²+12A +14 to 17

XRD analysis shows the peak of the (200) plane of the coating containing TaC/(111) plane.

5. The carbon material having a coating layer comprising TaC according to claim 1, wherein the coating layer comprising TaC has an average crystal grain size of 10 μm to 50 μm.

6. The carbon material having a coating layer containing TaC according to claim 1, wherein the surface hardness of the coating layer containing TaC is 15GPa or more.

7. The carbon material having a coating layer comprising TaC according to claim 1, wherein the coating layer comprising TaC has a surface scratch test value of 3.5N or more.

8. The carbon material having a coating comprising TaC according to claim 1, wherein the TaC content of the region having a depth of 80 μ ι η to 150 μ ι η from the surface of the carbon substrate is 15 vol% to 20 vol%.

9. The carbon material having a coating layer containing TaC according to claim 1, wherein a surface scratch value of the coating layer containing TaC is calculated according to the following numerical formula 2,

Mathematical formula 2

Surface scratch value (N) — TaC content (vol%) x (1.4 to 1.6) -19.5 from a region of 80 μm to 150 μm in depth from the surface of the carbon substrate.

10. The carbon material having a coating layer comprising TaC according to claim 1, wherein the carbon substrate has a coefficient of thermal expansion of 7.0 x 10^-6K to 7.5X 10^-6/K。

11. A method of making a carbon material having a coating comprising TaC, comprising the steps of:

Preparing a carbon substrate; and

A coating layer containing TaC having a maximum value of the peak of the (111) plane in the peaks generated by X-ray folding in XRD analysis is formed on the carbon substrate at a temperature of 1500 ℃ or higher by CVD.

12. The method for producing a carbon material having a coating layer containing TaC according to claim 11, wherein the step of forming a coating layer containing TaC is followed by a step of performing heat treatment at a temperature of 1800 ℃.

13. The method for producing a carbon material having a coating layer containing TaC according to claim 12, further comprising a step of cooling between the step of forming a coating layer containing TaC and the step of heat treatment.

14. The method for producing a carbon material having a coating layer containing TaC according to claim 11, wherein the step of forming a coating layer containing TaC is formed to have a ratio of a inflection peak of a (111) plane to a inflection peak of a (200) plane satisfying the following mathematical formula 1, in accordance with a desired surface hardness value of the carbon material having a coating layer containing TaC,

Mathematical formula 1

Surface hardness value (GPa) is-38A²+12A +14 to 17

XRD analysis shows the peak of the (200) plane of the coating containing TaC/(111) plane.

15. The method for producing a carbon material having a coating layer containing TaC according to claim 11, wherein the step of forming a coating layer containing TaC has a TaC content satisfying the following numerical formula 2 in accordance with a necessary surface scratch value of the carbon material having a coating layer containing TaC,

Mathematical formula 2

Surface scratch value (N) — TaC content (vol%) x (1.4 to 1.6) -19.5 from a region of 80 μm to 150 μm in depth from the surface of the carbon substrate.

16. The method for producing a carbon material having a coating layer containing TaC according to claim 11, wherein the step of preparing a carbon substrate includes preparing a carbon substrate having an average porosity of 15 to 20 vol%.

17. The method for producing a carbon material having a coating layer containing TaC according to claim 11, wherein the step of preparing the carbon substrate includes preparing a carbon material having a thermal expansion index of 7.0 x 10^-6K to 7.5X 10^-6A carbon substrate of/K.

Technical Field

The present invention relates to a carbon material having a coating layer containing TaC (tantalum carbide) formed on a carbon substrate, and a method for producing the same

background

In various fields, studies have been made to improve the wear resistance, corrosion resistance, and the like of materials by using various types of thin films on the surface of a base material. Among them, the material coating technology including (TaC) has been particularly drawing attention because it has more excellent characteristics than a thin film material in terms of heat resistance, abrasion resistance, internal gas etching resistance, and the like. Conventionally, in various industrial fields, a carbonaceous material in which a carbonaceous material containing a coating layer of TaC is formed on a carbon substrate has been used for a semiconductor single crystal manufacturing apparatus member, a precision machine tool, an engine member, and the like.

In this case, the coating layer formed containing TaC often has a problem due to adhesion to the substrate. Therefore, various attempts are being made by many enterprises and research institutes to form a coating comprising TaC with a high degree of adhesion on a carbon substrate.

Recently, techniques for controlling the hardness or surface abrasion resistance of a coating layer having TaC material have been attracting attention. If the physical properties of a desired coating layer can be predicted in consideration of the use of the desired material, and a coating layer containing TaC having reasonable physical properties can be formed, the TaC material can be applied to various fields in the industry. However, since there is no technique that can accurately predict physical properties such as a surface scratch value, it has been difficult to accurately predict physical properties of a coating layer to be formed in a process of forming a coating layer including TaC. Furthermore, it is an uncertain problem that is not solved in the industrial field to adjust what kind of variables are to what degree in order to control the surface hardness, surface scratch value, etc.

Disclosure of Invention

Technical subject

The present invention has been made in view of solving the problems, and has an object to provide a carbon material having excellent adhesion for forming a carbon substrate and having a TaC coating layer with high hardness and a high surface scratch value.

Further, another object of the present invention is to provide a technique for controlling controllable variables (selection of a carbon substrate, crystal grain size of a coating layer containing TaC, avoidance characteristics, X-ray folding strength, etc.) to an appropriate degree in order to cope with a desired level of product physical property specifications in manufacturing a carbon material of a coating layer containing TaC.

However, the problems to be solved by the present invention are not limited to the above-described problems, and other problems not mentioned can be understood by those having ordinary knowledge in the art by the following description.

Means for solving the problems

The carbon material of the coating layer comprising TaC of the present invention includes a carbon substrate; and a coating layer containing TaC formed on the carbon substrate, wherein the folding peak value of the (111) plane generated by X-ray folding of XRD analysis is maximum.

According to one embodiment of the invention, the ratio of the (111) plane inflection peak to the (200) plane inflection peak occurring from the X-ray inflection of the coating comprising TaC may be below 0.40.

According to an embodiment of the invention, the half-width of the XRD analysis of the coating comprising TaC may be below 0.15 °.

According to one embodiment of the present invention, the surface hardness of the coating layer comprising TaC may be calculated according to the following mathematical formula 1,

Mathematical formula 1

Surface hardness value (GPa) is-38A²+12A +14 to 17

XRD analysis shows the peak of the (200) plane of the coating containing TaC/(111) plane.

According to one embodiment of the invention, the coating comprising TaC may have an average crystallite size of from 10 μm to 50 μm.

According to one embodiment of the invention, the surface hardness of the coating comprising TaC may be above 15 GPa.

According to one embodiment of the invention, the coating comprising TaC may have a surface scratch test value above 3.5N.

According to an embodiment of the present invention, the TaC content from the region having the depth of 80 μm to 150 μm from the surface of the carbon substrate may be 15 vol% to 20 vol%.

According to one embodiment of the invention, the surface scratch value of the coating comprising TaC may be calculated according to the following mathematical formula 2,

Mathematical formula 2

Surface scratch value (N) — TaC content (vol%) x (1.4 to 1.6) -19.5 from a region of 80 μm to 150 μm in depth from the surface of the carbon substrate.

According to an embodiment of the present invention, the carbon substrate may have a thermal expansion coefficient of 7.0 × 10^-6K to 7.5X 10^-6/K。

The method for producing a carbon material having a coating layer containing TaC of the present invention includes the steps of preparing a carbon substrate; and forming a coating layer containing TaC having a maximum value of a reverse peak of the (111) plane among peaks generated by X-ray reverse of XRD analysis on the carbon substrate at a temperature of 1500 ℃ or higher by a CVD method.

according to an embodiment of the present invention, the step of forming a coating layer comprising TaC may be followed by a step of performing a heat treatment at a temperature of 1800 ℃ or higher.

An embodiment according to the present invention may further comprise a step of cooling between the step of forming a coating layer comprising TaC and the step of heat-treating.

According to an embodiment of the present invention, the step of forming the coating layer including TaC may form the coating layer including TaC to have a ratio of a inflection peak of a (111) plane to a inflection peak of a (200) plane satisfying the following equation 1, according to a desired surface hardness value of the carbon material having the coating layer including TaC

Surface hardness value (GPa) is-38A²+12A +14 to 17

XRD analysis shows the peak of the (200) plane of the coating containing TaC/(111) plane.

According to an embodiment of the present invention, the step of forming a coating layer comprising TaC may have a TaC content satisfying the following numerical formula 2, depending on a necessary surface scratch value of the carbon material having a coating layer comprising TaC,

Mathematical formula 2

Surface scratch value (N) — TaC content (vol%) x (1.4 to 1.6) -19.5 from a region of 80 μm to 150 μm in depth from the surface of the carbon substrate.

According to an embodiment of the present invention, the step of preparing the carbon substrate may include preparing the carbon substrate having an average porosity of 15 vol% to 20 vol%.

According to an embodiment of the present invention, the step of preparing the carbon substrate may include preparing a thermal expansion index of 7.0 × 10^-6K to 7.5X 10^-6A carbon substrate of/K.

Technical effects

According to one aspect of the present invention, there is an effect of providing a carbon material formed with a coating layer including TaC having a high hardness while maintaining a high adhesion with the carbon substrate.

in addition, according to another aspect of the present invention, in order to secure the carbon material of the coating layer containing TaC, the carbon substrate is selected from the pre-production stage, and the folding peak of the coating layer containing TaC is adjusted, whereby a product can be produced with desired physical properties.

Therefore, the carbon material having a coating layer containing TaC according to one embodiment of the present invention has an effect that it can be variously used in various industrial equipments which require precise control of high-level physical material.

Drawings

Fig. 1 is a single-sided conceptual view illustrating a carbon substrate including pores according to one embodiment of the present invention.

Fig. 2 is a single-sided conceptual view illustrating a carbon material comprising a carbon substrate and a coating layer of TaC formed on the carbon substrate, formed according to one embodiment of the present invention.

FIG. 3 is a flow chart illustrating the steps of a method for making a carbon material having a coating comprising TaC according to one embodiment of the present invention.

Fig. 4 is a graph showing a correlation between a ratio of a (111) plane inflection peak to a (200) plane inflection peak and a surface hardness value of an XRD analysis experiment according to an embodiment of the present invention.

Fig. 5a to 5d are graphs showing XRD analysis experiment results of coating layers including TaC in carbon materials manufactured according to examples and comparative examples of the present invention.

Detailed Description

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

The embodiments described below can be variously modified. The following examples are not intended to limit the embodiments, and include all modifications, equivalents, and alternatives to those.

The terms used in the embodiments are used only for describing specific embodiments, and therefore are not intended to limit the embodiments. Singular references include plural references, unless expressly specified in context. In the present specification, terms such as "including" or "having" are to be understood as specifying the presence of the features, numerals, steps, operations, constituent elements, components, or combinations thereof described in the specification, and not excluding the presence or possibility of one or more other features, or numerals, steps, operations, constituent elements, components, or combinations thereof in advance.

Unless defined otherwise, all terms used herein including technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, terms used in advance are to be interpreted as having meanings equivalent to those of the related art, and cannot be interpreted as having ideal or excessive meanings unless explicitly defined in the specification.

In the description with reference to the drawings, the same components are denoted by the same reference numerals regardless of the reference numerals, and redundant description thereof will be omitted. In describing the embodiments, detailed descriptions thereof will be omitted when it is judged that specific descriptions about known techniques unnecessarily obscure the points of the embodiments.

At present, the problem in the process of forming a coating layer on a carbon material with a TaC material is the hardness of the TaC layer of the coating material and the adhesion to the carbon material as a substrate. Recently, many studies have been made to improve the hardness and adhesion of a coating layer containing TaC, which varies depending on various physical properties of a base material. The present invention has an object to effectively ensure a carbon material containing a coating layer of TaC, which has high hardness and high substrate adhesion, by further analyzing the porosity of the carbon material, the crystal of TaC material, and the avoidance characteristics thereof.

the carbon material of the present invention having a coating layer comprising TaC comprises: a carbon substrate; and a coating layer containing TaC formed on the carbon substrate, wherein the folding peak value of the (111) surface generated by X-ray folding of XRD analysis is maximum.

The carbon substrate may include any substrate that includes graphite and has carbon as a constituent. The coating layer containing TaC may contain any one of materials having tantalum (Ta) and carbon (C) as main components.

Also, according to one aspect of the present invention, the present invention provides that the characteristics regarding the crystallinity of the coating layer comprising TaC can be analyzed by X-ray reverse-turn analysis of XRD analytical equipment. At this time, the conventional XRD analysis equipment can be used in the X-ray reverse-turn analysis experiment. The fold-back peak is related to the fold-back intensity, meaning the maximum height of the peak, as can be understood by XRD analysis experiments. Further, the half width of the fold line indicates the width of the fold peak at the maximum height 1/2, which can be an index of crystallinity.

According to one aspect of the present invention, in the process of forming the coating layer containing TaC on the carbon substrate, a CVD method may be used. In this case, in the metallization process of the material containing TaC, the pattern of the X-ray inflection line of the coating layer containing TaC can be changed by adjusting the temperature, pressure, and ejection speed of the TaC precursor.

When analytical experiments were performed on coatings containing TaC, various facet back-fold peaks could occur due to the crystalline character of the TaC material. For example, the folding lines corresponding to the (220) plane, (311) plane, (111) plane, (200) plane, and the like can be formed with a high strength. The carbon material having a coating layer comprising a TaC material provided by the present invention is characterized by having the maximum X-ray inflection peak of the (111) plane.

According to an embodiment of the present invention, a ratio of a folding peak (200) of a (111) plane where an X-ray folding back occurs to a folding peak (200) plane of a coating layer including the TaC may be below 0.40 in XRD analysis.

if the reverse turn peak ratio exceeds 0.40, the surface hardness of the coating layer containing TaC is low, and therefore, there is a problem that it is difficult to apply a coating layer requiring a material having a high surface hardness to a semiconductor manufacturing apparatus requiring such a coating layer. In addition, there is a problem that adhesion between the TaC coating layer and the carbon substrate is reduced, and material uniformity is reduced due to an increase in crystal grain boundaries forming boundaries with crystal grains. Meanwhile, if the ratio of the inflection peaks exceeds 0.40, the surface hardness value may be greatly reduced if the peak rises slightly. Therefore, the ratio of the inflection peaks of 0.40 is a value having significance in one aspect of the present invention. Also, in order to achieve a high surface hardness value of the carbon material, a coating layer containing TaC having the above-described reverse turn peak of 0.40 or less may become an important factor.

Further, a ratio of the inflection peak of the (111) plane to the inflection peak of the (200) plane may be 0.01 or more. The ratio of the inflection peak of the (111) plane to the inflection peak of the (200) plane is 0.19 or less, and it is preferable that the coating layer containing TaC is formed as a high hardness coating layer.

According to an embodiment of the present invention, the layer containing said TaC may be XRD analysis with a half-width of the meander line below 0.15 °. Thus, a coating layer containing TaC can be formed which has high crystallinity and also has TaC crystal grains with an average size sufficient for forming TaC crystal grains.

According to an embodiment of the present invention, the surface hardness of the coating layer comprising said TaC may be according to mathematical formula 1.

Mathematical formula 1

Surface hardness value (GPa) is-38A²+12A +14 to 17

XRD analysis shows the peak of the (200) plane of the coating containing TaC/(111) plane.

According to the carbon material provided in one aspect of the present invention, it is found that there is a close correlation between the surface hardness value and the ratio of the inflection peak of the (200) plane to the inflection peak of the (111) plane of the coating layer containing TaC.

The carbon material provided according to one aspect of the present invention has a tendency that the surface hardness value of the coating layer containing TaC decreases as the ratio of the inflection peak value of the (200) side to the inflection peak value of the (111) side of the coating layer containing TaC increases. At this time, as the ratio of the inflection peak of the (200) plane/(the inflection peak of the (111) plane increases, the reduction width of the surface hardness value of the coating layer containing TaC tends to become gradually larger. This tendency of the surface hardness value can be expressed by a method of determining a slice width suitable for a quadratic function equation having a negative quadratic coefficient by using a ratio of the inflection peak value of the (200) plane/(the inflection peak value of the (111) plane as a variable. (math formula 1)

Therefore, with the carbon material having a coating layer containing TaC of the present invention, the X-ray inflection peak of the coating layer containing TaC can be precisely designed by using the above formula 1 with reference to the surface hardness of the product required from the process of producing the carbon material. Thus, there is an advantage in that a TaC coating layer ensuring a desired level of physical properties can be formed.

According to an embodiment of the present invention, the average grain size of the layer comprising TaC may be 10 μm to 50 μm.

When the average crystal grain size is less than 10 μm, the hardness of the coating layer containing TaC is not more than a certain level, and there is a problem that it is difficult to apply the coating layer to a semiconductor manufacturing apparatus which generally requires a high hardness material. Further, if the crystal grain size of the coating layer exceeds 50 μm, there arises a problem that the engineering energy and cost required for increasing the crystal grain size decrease the productivity.

According to one embodiment of the invention, the surface hardness of the coating comprising TaC may be above 15 GPa.

The coating comprising TaC provided according to the invention ensures a high-strength surface hardness of more than 15 GPa.

According to one embodiment of the invention, the coating comprising TaC may have a surface scratch test value above 3.5N.

In order to confirm the excellent adhesion of the coating layer containing TaC, various experimental methods such as 4-Point Benning experiment, Peel-Off experiment, Scotch tape experiment, Direct Full Off experiment, etc. are used. Among them, the scratch Test (scratch Test) is a Test method frequently used in the industry to confirm the adhesion of a thin film coating because a sample can be easily prepared and measured easily. The scratch test may use a stylus (stylus) to increase the surface load of the film, causing it to move. And calculating the adhesive force by using the critical load value when the film is removed. Thus, a higher scratch value indicates a stronger adhesion strength. In the carbon material having a coating layer including TaC according to an embodiment of the present invention, a surface scratch value including the TaC coating layer may be 3.5N or more. When the surface scratch value of the coating layer containing TaC is 3.5N or less, there arises a problem that the adhesion to the surface of the base material is insufficient, and it is difficult to apply the coating layer to the industry. Furthermore, preferably, the coating comprising TaC has a surface scratch value of above 6.5N. More preferably, the coating comprising said TaC has a surface scratch value above 8.0N. The surface scratch value shows a tendency of increasing on average with an increase in the TaC content from a region having a depth of 80 μm to 150 μm on the surface of the carbon substrate. The content of TaC may be determined by impregnating the TaC component into pores of the carbon substrate, and the pores may pass through the carbon substrate. At this time, as the average porosity from a region having a depth of 80 μm to 150 μm from the surface of the carbon substrate increases, the adhesion between the coating layer including TaC and the substrate may increase.

According to an embodiment of the present invention, the carbon substrate may be a carbon substrate having a TaC content of 15 vol% to 20 vol% from a region having a depth of 80 μm to 150 μm from a surface of the carbon substrate.

In fig. 1, a single-sided conceptual view of a carbon substrate 110 provided according to the one embodiment of the present invention is shown. The carbon substrate is a porous carbon material having pores formed therein, and a coating layer containing TaC is formed on the carbon substrate, and if the TaC component is formed in the pores, the TaC component is impregnated into the pores, thereby forming impregnated regions.

Fig. 2 is a single-sided conceptual view of a high hardness TaC coated carbon material of carbon substrate 110 comprising TaC component impregnated region 130 and coating 120 comprising TaC formed on the carbon substrate, according to one embodiment of the present invention. The infused region 130 may comprise 131 regions having a depth of 80-150 μm from the surface of the carbon substrate. The region where the carbon substrate has a depth of 80 to 150 μm from the surface of the carbon substrate may be a region where the TaC component of the coating layer containing TaC is formed by impregnating the carbon substrate with pores, and the region may substantially affect the surface hardness and the substrate adhesion of the coating layer.

In addition, the TaC content from the region of the carbon substrate surface having a depth of 80 μm to 150 μm may be 15 vol% to 20 vol%. When the TaC content of the region is 15 vol% to 20 vol%, a coating layer containing TaC intended for one side of the present invention, which is excellent in adhesion to a carbon substrate, can be formed. When the TaC content of the region is 15 vol% or less, there is a problem that the adhesion of a coating layer containing TaC becomes weak or the surface hardness becomes low. When the content of TaC exceeds 20 vol%, there arises a problem that the surface illuminance increases and the coating surface is formed roughly because pores of graphite are excessively formed. Furthermore, preferably, the region TaC content is 16.5 vol% to 20 vol%. Furthermore, more preferably, the region TaC content is from 18 vol% to 20 vol%. The increase in TaC content of the region indicates a high porosity of the carbon substrate. In fact, the higher the porosity of the carbon substrate of the coating comprising TaC, the better the adhesion and the surface hardness.

As shown in fig. 2, the region 131 with a depth of 80 μm to 150 μm from the surface of the carbon substrate can be divided into two regions with different TaC contents, i.e., a first region 132 with a relatively shallow region and a second region 133 with a relatively deep region from the surface of the carbon substrate.

The first region is a region adjacent to the coating layer containing TaC and is a region in which the TaC component can be sufficiently impregnated into pores of the substrate. Therefore, the first region belongs to a region having the highest impregnation rate in the carbon substrate. Although the adhesion and the surface hardness of the coating layer including TaC formed on the carbon substrate may vary depending on the process conditions such as the process temperature and the Ta/C ratio, the coating layer including TaC may have excellent surface hardness when the TaC content of the first region formed after the formation of the coating layer including TaC is 16 vol% to 20 vol%. The 2 nd region is a region which is deeper from the surface of the substrate than the first region and is adjacent to the first region, and in which the TaC component of the coating layer is relatively small in impregnation. However, the TaC content of this region may also affect the adhesion and surface hardness of the TaC-containing coating formed on the carbon substrate. When the TaC content of the second region is 13 vol% to 18 vol%, a coating layer including TaC formed on the carbon substrate may have excellent adhesion and surface hardness. The first region and the second region may have gradually smaller TaC contents. The boundary between the first region and the second region may be formed at a portion having a depth of 40 μm to 70 μm from the surface of the coating layer of the carbon material containing TaC.

According to one embodiment of the present invention, the surface scratch value of the coating comprising said TaC may be according to mathematical formula 2.

Mathematical formula 2

Surface scratch value (N) — TaC content (vol%) x (1.4 to 1.6) -19.5 from a region of 80 μm to 150 μm in depth from the surface of the carbon substrate.

the determining factor for the adhesion of the coating comprising TaC to the carbon substrate formed on said carbon substrate can be present in various ways. As one of the factors, the content of TaC from the region with the depth of 80-150 μm on the surface of the carbon substrate plays a great role in determining the adhesion of the coating layer containing TaC. According to one embodiment of the invention, the surface scratch value (N) of the TaC coating is a function of the TaC content (% by volume) as a function of the first order of variables from a region of the carbon substrate surface having a depth of 80 μm to 150 μm. The surface scratch value (N) of the coating layer containing TaC thus determined may represent the TaC content (volume%) x (0.65 to 0.7) -19.5 from a region having a depth of 80 μm to 150 μm from the surface of the carbon substrate.

According to an embodiment of the present invention, the thermal expansion index of the carbon substrate may be 7.0 × 10^-6K to 7.5X 10^-6/K。

The coefficient of thermal expansion of the carbon substrate plays an important role in determining the adhesion of the carbon substrate and the coating comprising TaC formed by said carbon substrate. Carbon materials comprising coatings of TaC of the invention can be formed by preparing carbon substrates having a thermal expansion coefficient that is not significantly different from that of TaC stock, taking into account the thermal expansion coefficient of the coating comprising TaC. In this case, the thermal expansion coefficient of the carbon substrate may be 7.0X 10-6/K to 7.5X 10^-6and/K. Thus, when the temperature of the coating containing TaC is increasedWhen the change expands or contracts, thermal stress with the carbon substrate can be minimized, and adhesion of the coating can be improved.

FIG. 3 is a flow chart illustrating steps of a method for making a carbon material having a coating comprising TaC according to one embodiment of the invention.

The method for producing a carbon material having a coating layer containing TaC of the present invention includes the steps of preparing a carbon substrate; and forming a coating layer containing TaC, in which the peak of the (111) plane is maximum, among peaks generated by X-ray folding in XRD analysis, on the carbon substrate at a temperature of 1500 ℃ or higher by a CVD method.

According to one aspect of the present invention, in the process of forming the coating layer containing TaC on the carbon substrate, a CVD method may be used. In this case, in the metallization process of the material containing TaC, the pattern of the X-ray inflection line of the coating layer containing TaC can be changed by adjusting the temperature, pressure, and ejection speed of the TaC precursor.

When the analytical experiments included TaC coatings, various facet back-fold peaks could occur due to the crystalline character of the TaC material. For example, the folding lines corresponding to the (220) plane, (311) plane, (111) plane, (200) plane, and the like can be formed with a high strength. The carbon material of the coating layer containing TaC material according to the present invention is characterized by the maximum X-ray inflection peak of the (111) plane.

The metallization method of the TaC material CVD method generally used may perform the metallization process in a chamber maintained at a temperature of 800 to 900 c or start the metallization process at a temperature of several hundred c or start the injection of the raw material gas at a temperature of several hundred c. And metallization is performed by raising the temperature in the chamber.

However, according to one aspect of the present invention, the initial temperature for starting metallization is 1500 ℃ or higher by the CVD method, and the metallization is performed isothermally. Thus, high adhesion to the carbon substrate and high surface hardness intended for one aspect of the present invention can be ensured. However, the temperature may be formed below 2500 ℃. When the temperature exceeds 2500 ℃, equipment is difficult to achieve. And the temperature is too high, so that it becomes difficult for the TaC component to be impregnated into the pores of the substrate, and the problem of decrease in adhesion occurs.

According to an embodiment of the present invention, the step of forming the coating layer comprising TaC may be followed by a step of performing a heat treatment at a temperature of 1800 ℃ or higher.

According to one aspect of the present invention, the method may further comprise a step of performing a heat treatment by raising the temperature in the chamber after the starting material gas injection is completed after the coating containing TaC is metallized by the CVD method at a high temperature. This provides an effect of relieving residual stress and promoting crystal grain size growth, and also provides an effect of improving the physical properties of a coating layer containing TaC by forming a relatively uniform coating layer.

According to an embodiment of the present invention, a step of forming a coating layer including TaC and a step of cooling between the steps of the heat treatment may be further included. Wherein the cooling step may cool the surface of the TaC coating or may cool the entire carbon material. The cooling step may be a step of lowering the temperature to normal temperature by taking out the carbon material to the outside, or may be a step of lowering the temperature to a temperature slightly lower than the temperature at the step of forming the coating layer containing TaC.

According to an embodiment of the present invention, the step of forming a coating layer including TaC may be to form the coating layer including TaC to have a ratio of a (111) plane inflection peak value to a (200) plane inflection peak value satisfying the following mathematical formula 1, according to a surface hardness value of the carbon material including the coating layer including TaC.

Mathematical formula 1

Surface hardness value (GPa) is-38A²+12A +14 to 17

XRD analysis shows the peak of the (200) plane of the coating containing TaC/(111) plane.

For the carbon material having a coating layer comprising TaC according to the present invention, engineering can be precisely designed by a method of appropriately adjusting the X-ray inflection peak value of the coating layer comprising TaC according to the hardness value of the surface of the product required from the process of manufacturing the carbon material by using the above mathematical formula 1. Thereby, the surface hardness of the coating layer containing TaC can be precisely and in place, and a product meeting the required surface hardness specification can be ensured by adjusting the ratio of (200) plane inflection peak/(111) plane inflection peak of the coating layer containing TaC in the process of forming the coating layer containing TaC.

According to an embodiment of the present invention, in the forming step of the coating layer comprising TaC, the coating layer comprising TaC may have a TaC content satisfying the following mathematical formula 2 according to a desired surface scratch value of a carbon material comprising the TaC coating layer.

Mathematical formula 2

surface scratch value (N) — TaC content (vol%) x (1.4 to 1.6) -19.5 from a region of 80 μm to 150 μm in depth from the surface of the carbon substrate.

According to an embodiment of the present invention, the step of preparing the carbon substrate may further include a step of preparing the carbon substrate having an average porosity of 15 vol% to 20 vol%.

According to one aspect of the present invention, in order to form the coating layer containing TaC with good adhesion on the carbon substrate, a preparation step of the carbon substrate having an average porosity of 15 vol% to 20 vol% may be further included. By preparing the carbon base material having the average porosity of 15 vol% to 20 vol%, the effect intended in one embodiment of the present invention, that is, the high hardness coating layer containing TaC excellent in adhesion and surface hardness can be realized. Further, preferably, the average porosity is 16.5 vol% to 20 vol%. Further, more preferably, the average porosity is 18 to 20 vol%. The increase in the TaC content in the substrate indicates a high porosity on the carbon substrate, and, in fact, the higher the porosity of the carbon substrate formed with the TaC coating layer, the more excellent the adhesion and surface hardness. The average porosity of the carbon substrate can be measured by mercury adsorption (Prosimeter: pore analyzer).

According to an example of the present invention, the step of forming a coating layer containing TaC may include forming an impregnated region in contact with the coating layer inside the carbon substrate by impregnating pores of the carbon substrate with a coating component containing TaC. When the coating layer of the carbon substrate is formed at a high temperature, the coating component containing TaC starts impregnation from the surface pores to the internal pores of the carbon substrate. Thus, an impregnation region in contact with the coating layer may be formed inside the carbon substrate. The impregnated region having a depth of 80 to 150 μm from the surface of the carbon substrate may be a region having practical significance in determining the adhesion between the coating layer containing TaC and the carbon substrate and the surface hardness of the formed carbon material.

According to an embodiment of the present invention, the step of preparing the carbon substrate may include preparing a thermal expansion coefficient of 7.0 × 10^-6K to 7.5X 10^-6A step of a/K carbon substrate.

The carbon material having a coating layer comprising TaC of the present invention can be formed by preparing a material having a thermal expansion coefficient which is not much different from that of the material having TaC in consideration of the thermal expansion coefficient of the coating layer comprising TaC.