KR20190111263A - Surface treating method for controlling surface roughness of carbon material - Google Patents

Abstract

The present invention relates to a surface treating method capable of reducing a failure rate and implementing uniform and high surface roughness conditions by inhibiting damage of a carbon material generated during a surface treating process of a substrate made of the carbon material. The surface treating method comprises a step of arranging the substrate made of the carbon material and a step of treating the surface of the substrate. In the surface treating step, a medium is sprayed to the surface of the carbon material using a thermal spray method. The medium does not form a coating layer on the surface of the substrate but has the roughness having the surface roughness of a certain level on the surface of the substrate.

Description

SURFACE TREATING METHOD FOR CONTROLLING SURFACE ROUGHNESS OF CARBON MATERIAL}

The present invention relates to a surface treatment method for controlling the surface roughness of the carbon material, and more particularly, to suppress the damage of the carbon material generated during the surface treatment process to reduce the defective rate and at the same time to implement a uniform and high surface roughness state It relates to a surface treatment method.

Recently, substrates using carbon materials are increasing in semiconductor parts and components used in LED processes, and products requiring coating treatments are increasing in order to increase the lifetime of the carbon materials used.

In order to form a coating layer having a desired thickness to impart durability or functionality to the surface of the carbon material and to maintain high interfacial adhesion between the formed coating layer and the carbon material, a surface uneven portion is formed to a uniform and desired level on the surface of the carbon material. It is necessary to carry out the surface treatment.

In general, a method for forming irregularities on the surface of a material includes sand blast and hard metal, which pressurizes and accelerates sand onto the surface of a workpiece to remove impurities attached to the surface and to produce a constant irregularities. A method of physically forming irregularities by colliding fine and hard particles at high speed, such as shot peening and shot blast, in which beads are sprayed at a high pressure.

However, in the case of a carbon material such as graphite, since it has a crystallographic layered structure and weak bonding between layers, in general, when using a conventional method used to form a constant unevenness on the surface, such as Ra 3 ~ 20㎛ It is difficult to form relatively high levels of surface roughness.

In addition, in order to form a high level of surface roughness, it is necessary to perform several continuous surface treatments, and in this process, the amount of etching of the surface increases, so that dimensional precision cannot be matched, and defects occur, which causes the manufacturing cost.

In addition, even if the required surface roughness is formed, there is a problem that it is difficult to obtain a sufficient interfacial bonding force when the coating layer is formed because the variation of the formed irregularities is large.

Korean Patent Publication No. 10-2016-0120403

The object of the present invention is not only to easily form a high surface roughness of arithmetic mean roughness (Ra) of 3 ~ 20㎛ level, less damage to the carbon material during the surface treatment process, good uniformity of the irregularities formed, It is to provide a surface treatment method for controlling the surface roughness of the carbon material excellent workability.

One embodiment of the present invention for achieving the above object, comprising the step of placing a substrate formed of a carbon material and surface treatment of the substrate, the surface treatment step in the surface treatment step using a thermal spray method the carbon material Spraying on the surface of the substrate, but preventing the medium from forming a coating layer on the surface of the substrate, and forming a roughness having a predetermined surface roughness on the surface of the substrate, the surface treatment method for controlling the surface roughness of the carbon material To provide.

The present invention is to form irregularities on the surface of the carbon material without forming a coating layer by using a thermal spraying method used in the conventional coating method of durable materials, arithmetic mean that was difficult to easily implement in a conventional method such as sand blasting or shot peening Roughness (Ra) It is possible to easily implement a high surface roughness of 3 ~ 20㎛ level.

In addition, the method according to the present invention, even if a high surface roughness is formed, less etching after the surface treatment, less erosion, easy to maintain flatness, it is possible to significantly reduce the product defect rate occurring during the surface treatment process.

In addition, the uneven portion formed by the method according to the present invention is uniform in acid, valley, wavelength, etc., not only to maintain the dimensional accuracy, but also to improve the durability of the product by improving the interfacial bonding force between the coating layer and the carbon material formed after the surface treatment Can be improved.

In addition, in the conventional method, after the semi-machining is performed, the final machining is performed to match the surface roughness, so that the complete machining state can be realized. There is also a significant advantage in terms of.

In addition, the method according to the invention shows good work reproducibility close to 100%.

1 is a process chart of the surface treatment method according to an embodiment of the present invention.
2 is a cross-sectional view of the high speed flame spraying apparatus used in the high speed flame spraying method.
3 is an optical microscope image of the surface state after the uneven portion is formed on the surface of the graphite substrate using a conventional blasting method.
4 is an optical microscope image of the surface state after forming the uneven portion on the surface of the graphite substrate using a high-speed flame spray method according to an embodiment of the present invention.
5 is a graph showing a result of measuring surface roughness after forming an uneven portion on the surface of the graphite substrate using a conventional blasting method.
Figure 6 is a graph showing the result of measuring the surface roughness after forming the uneven portion on the surface of the graphite substrate using a high-speed flame spraying method according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail based on the preferred embodiments of the present invention. However, the following examples are merely examples to help the understanding of the present invention, whereby the scope of the present invention is not reduced or limited.

1 is a flow chart showing a surface treatment method for controlling the surface roughness of the carbon material according to an embodiment of the present invention. Referring to FIG. 1, the surface treatment method for controlling the surface roughness of a carbon material according to an embodiment of the present invention includes disposing a substrate formed of a carbon material (S100) and surface treating the substrate (S200). can do.

The base material of the carbon material may be a composite material preferably including graphite or graphite.

Graphite has a crystallographically layered structure and forms van-der-walls bonds with weak bonding strength between layers, so that they break easily even with small shear stresses. It has low elastic modulus and fracture toughness.

By applying a method such as sand blast or shot peening, which is a surface treatment method for forming a conventional surface roughness, a solid such as alumina (Al ₂ O ₃ ), silica (SiO ₂ ), silicon carbide (SiC), or hard metal When the particles are projected at high speed onto the substrate made of graphite, the surface of the graphite is easily damaged by the above-described characteristics of the graphite.

For this reason, in order to achieve a predetermined surface roughness (especially high surface roughness), when using the blast method of simple projection of particles, the desired surface roughness level cannot be formed in one process, and the final surface treatment is performed through multiple surface treatments. It is common to realize numerical values of surface roughness.

In contrast, the method according to the invention is characterized in that in the surface treatment step, thermal spraying is used without using the blasting method.

The thermal spraying method is not a method used to form irregularities on the surface of the substrate, but heats the metal or nonmetallic particles to be coated to a high temperature, projects the substrate in a semi-melt or molten state to physically adhere to the surface of the substrate. It is a kind of coating method used to improve durability of a substrate by laminating to form a coating layer.

However, in the present invention, the semi-melt (or molten) particles are projected at high speed by the thermal spraying method so that they are attached to the graphite substrate so that they are not coated, thereby forming irregularities on the surface to impart roughness. It is characterized by controlling the illuminance. That is, the thermal spraying method is used to form the uneven portion on the surface of the graphite substrate without forming the coating layer.

As the thermal spraying method, preferably High Velocity Oxy Fuel (HVOF) may be used.

2 is a cross-sectional view of the spray gun used in the high speed flame spraying method.

As shown in FIG. 2, in general, a spray gun has a line through which kerosene as a fuel is supplied and a line through which oxygen is supplied, and a spark plug is formed at a central portion of the spray gun. When the ignition is performed by the spark plug, fuel gas and oxygen gas cause a combustion reaction to generate heat and volume expansion of the combustion gas. By using this, heat and kinetic energy are supplied to the powder (spray particles) supplied from one side of the gun. The apparatus is a device for forming a coating layer on the surface of the substrate by projecting the semi-melt (or molten) of the particles to the substrate.

Gas used in the high-speed flame spraying method may include oxygen, hydrogen, nitrogen and fuel (Fuel).

In the high-speed flame spraying method, the center temperature of the gun may be about 3500 ° C.

In the high-speed flame spraying method, it may be desirable to maintain the projection speed of the thermal spray particles in the range of 0.1 to 1 ms (1 ms is 1000 m / s), which may not be easily formed on the surface of the graphite substrate when less than 0.1 ms. This is because damage to the graphite substrate may occur in the substrate when it is greater than 1 ms.

The thermal spraying spray particles used in the high-speed flame spraying method, metals, metal oxides, metal carbides, metal nitrides, metal carbonitrides, metal carbonate nitrides and the like, non-metals, complexes such as a mixture of metal and nonmetals or cermet (cermet) can be used , Preferably tungsten (W) or tungsten carbide (WC).

In the surface treatment, the surface roughness can be controlled to the required numerical range depending on the particle size and the projection distance of the projection material.

The surface treatment implemented through the high speed flame spraying method may be suitably used to form a high surface roughness, such as arithmetic mean roughness (Ra) of 3 ~ 20㎛, the present invention is not necessarily limited to the numerical range, various levels It can also be used to form a surface roughness of.

EXAMPLE

In a preferred embodiment of the present invention by applying a high-speed flame spraying method to a graphite plate of 5 ~ 25mm thickness under the following conditions to achieve a surface roughness of about 10㎛ level arithmetic mean roughness (Ra).

Gas: Oxygen

Fuel: kerosene

Center temperature: 3500 ℃

-Projection material: tungsten powder with an average particle size of 20㎛ or more (particle size distribution: 10 ~ 63㎛)

Projection speed: 0.1 to 1ms (1000m / s)

-Projection time: 1000mm × 1000mm graphite plate once every 5 minutes (projection time varies depending on the size and shape of the product)

According to the method according to an embodiment of the present invention, it is possible to achieve the desired surface roughness even with a very small etching amount within 0.005mm.

Accordingly, the surface treatment is performed by a conventional method, which not only solves the problem of a relatively high etching amount occurring during the surface roughness forming process and a high defective rate due to the flatness due to deformation, but also a desired value in the finished state. Surface roughness of is also possible.

[Comparative Example]

For comparison with a preferred embodiment of the present invention, a surface roughness of about 8.4 μm is achieved by applying a conventional blasting method under the following conditions to a graphite plate having the same thickness of 5 to 25 mm under the following conditions. It was.

Projection device: automatic robot suction and direct pressure blast device

-Projection material: Al ₂ O ₃ (Projection material size: # 80 ~ 100)

Projection Pressure: 0.6 ~ 1.0Psi

-Distance between substrate and nozzle: 500 ~ 800mm

In the comparative example, after the blast was first performed under the condition of the distance of 500 mm between the substrate and the nozzle and the projection material (Al ₂ O ₃ # 80), if the target surface roughness was higher than that of the Al ₂ O ₃ # The surface roughness was controlled by changing the amount to 100 and increasing the distance from the substrate to 800mm. If the surface was lower than the target surface roughness, the continuous work was performed under the same conditions, and the etching amount of the substrate was about 0.02mm in one operation. It became.

3 is an optical microscope image of the surface state after the uneven portion is formed on the surface of the graphite substrate using a conventional blasting method, and FIG. 4 is a high speed flame spray method according to an embodiment of the present invention. It is an optical microscope image which observed the surface state after forming an uneven part on the surface.

3 and 4 qualitatively confirm that the graphite plate formed by the method according to the preferred embodiment of the present invention has a uniform uneven portion formed in comparison with the graphite plate formed by the method according to the comparative example which is a conventional method.

5 is a graph showing the results of measuring the surface roughness after forming the uneven portion on the surface of the graphite substrate using a conventional blasting method, Figure 6 is a graphite substrate using a high-speed flame spraying method according to an embodiment of the present invention It is a graph which shows the result of measuring surface roughness after forming the uneven | corrugated part in the surface of.

As can be seen in Figure 5, in the case of the graphite plate formed by the method according to a preferred embodiment of the present invention, while the surface roughness (Ra) 10.09㎛ high level compared to the comparative example, while the height of the acid constituting the uneven portion, The depth of the valleys, the wavelength is uniform.

On the other hand, in the comparative example, while the surface roughness (Ra) is 8.4 占 퐉, which is relatively low, the height of the highest mountain is higher than that of the embodiment of the present invention, and the depth of the deepest bone is not only deeper than the present invention, but also the overall wavelength. It can be seen that the shape is uneven, so that the shape of the uneven portion formed is relatively uneven compared with the embodiment of the present invention.

The uniformity of the irregularities in the shape of the uneven parts greatly affects the dimensional accuracy and / or the damage rate of the graphite plate, which greatly affects the final product failure rate. That is, the method according to the embodiment of the present invention can be said to have a significant advantage in terms of dimensional accuracy while implementing a high level of surface roughness compared to the comparative example.

Although the technical spirit of the present invention has been described above with reference to the accompanying drawings, the present invention has been described by way of example and is not intended to limit the present invention. In addition, it is obvious that any person skilled in the art may make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (6)

Disposing a substrate formed of a carbon material and surface treating the substrate,
In the surface treatment step, a thermal spraying method is used to spray a medium onto the surface of the carbon material, while preventing the medium from forming a coating layer on the surface of the substrate, and having a predetermined surface roughness on the surface of the substrate. Surface treatment method for controlling the surface roughness of the carbon material to form.
The method of claim 1,
The carbon material is graphite (graphite) or a composite material containing graphite, the surface treatment method for controlling the surface roughness of the carbon material.
The method of claim 1,
The thermal spraying method is a high-velocity oxide fuel (HVOF) method, the surface treatment method for controlling the surface roughness of the carbon material.
The method of claim 3,
The thermal spraying method used in the high speed flame spraying method includes tungsten (W) or tungsten carbide (WC), the surface treatment method for controlling the surface roughness of the carbon material.
The method of claim 3,
The surface treatment method for controlling the surface roughness of the carbon material, the projection speed of the sprayed particles in the high-speed flame spraying method is 100 ~ 1000m / s.
The method of claim 1,
The surface roughness of the predetermined value is arithmetic mean roughness (Ra) of 3 to 20㎛, the surface treatment method for controlling the surface roughness of the carbon material.

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