KR100556216B1 - Fabrication method of adherent diamond coated cutting tool - Google Patents

Abstract

The present invention relates to a method for manufacturing a cutting tool for depositing a diamond film on the substrate of the cutting tool placed in the chamber by using a vapor phase chemical vapor deposition method, wherein a diamond film having a predetermined thickness is formed on the substrate of the cutting tool without applying a bias. The first step of the deposition and the second step of depositing a diamond film on the diamond film deposited to a predetermined thickness while applying a direct current or alternating current bias to the cutting tool, thereby providing a diamond film having excellent adhesion to the base material and a fine particle size. Can be deposited.

Description

Fabrication method of adherent diamond coated cutting tool

1 shows a cutting tool on which diamond is deposited;

Figure 2 schematically shows a thermal filament vapor deposition apparatus;

FIG. 3A is a scanning micrograph of a diamond film deposited without a bias using a thermal filament vapor deposition apparatus; FIG.

FIG. 3B is a scanning micrograph of the diamond film changed after applying a bias for 2 hours to the diamond of FIG. 3A;

3C is a scanning micrograph of the diamond film changed after applying a bias for 6 hours to the diamond of FIG. 3A;

3D is a scanning micrograph of the diamond film changed after applying a bias for 8 hours for the diamond of FIG. 3A;

Figure 4a is a scanning microscope photograph showing the hardness test results for the deposited diamond film while applying the bias from the beginning;

4b to 4c are scanning micrographs showing the hardness test results for the diamond film deposited according to the production method of the present invention; And

4D is a scanning micrograph showing the hardness test results for the diamond film deposited without applying a bias.

<Description of Symbols for Main Parts of Drawings>

10: cutting tool 11: base material of the cutting tool

20: diamond film 100: chamber

101: inlet port 102: exhaust port

110: power input unit 111: power for thermal filament

112: bias power supply 120: thermal filament

130: support member 140: holder

The present invention relates to a cutting tool manufacturing method for depositing a diamond film on the base material of the cutting tool placed in the chamber by using a chemical vapor deposition method, and more particularly to deposit a diamond film on the base material of the cutting tool, The present invention relates to a method of manufacturing a cutting tool having a small size of particles forming a diamond film while improving adhesion between diamond films deposited on a base material.

Recently, with the development of various materials having high hardness and wear resistance, there is an increasing need for cutting tools having harder and better wear resistance characteristics capable of processing such materials. Diamond is one of the hardest existing materials, has electrical insulation properties and chemical stability, and is widely used industrially due to many other excellent physical properties. Recently, as shown in FIG. 1, a diamond film 20 is deposited on a surface of a cutting tool 10, which is used in the past, by using such a diamond property, thereby a cutting tool formed by a diamond film having greatly improved hardness and wear resistance. Research has been done intensively. In general, chemical vapor deposition (CVD) is mainly used to uniformly deposit diamond on cutting tools 10 having various shapes and sizes. Microwave plasma vapor deposition method, such as filament (hot filament) or the deposition in the plasma state, and the like. The diamond film 20 deposited in this manner increases the surface particle size of the film as the deposition thickness increases. This increase in particle size is caused by the increase in temperature, concentration of flux, or concentration of plasma. It occurs prominently at the edges (edges, corners, 11). As the particle size of the diamond film 10 increases at the edge portion 11, the roughness of the surface is also increased, and turning or milling is performed using a tool on which a diamond film having a large surface roughness is deposited. When machining materials such as milling, drilling and boring, the surface roughness of the workpiece to be processed is also increased, so that the machining of the workpiece, which requires low surface roughness after processing, or fine or precise machining You cannot use it.

In particular, when the diamond film 20 is deposited on the cutting tool 10 by the vapor phase chemical vapor deposition method, as described above, in the cutting edge portion 11 of the cutting tool 10, when the particle size and roughness are larger than the central portion 12, the cutting edge portion is formed. In addition to the phenomenon that edge 11 becomes dull and edge sharpness decreases, the thickness of the diamond film 20 deposited along the edge 11 is also increased. ) Induces stress on the cutting tool 10 during the actual machining, thereby shortening the life of the cutting tool. Therefore, considering that the part mainly used for machining in the actual cutting tool is the cutting edge 11, the development of a cutting tool having a constant deposition thickness possible for the cutting edge 11, and a small diamond film capable of grain size is deposited. This is essential.

As a method of miniaturizing the particle size of the diamond film 11, a method of increasing the concentration of a process gas (for example, CH ₄ or C ₂ H ₂ ) for forming diamond with deposition time has been proposed (US Patent No. 6,319,610). In general, when the diamond film 11 is deposited by vapor phase chemical vapor deposition, hydrogen and methane (CH ₄ ) are used as injected process gases. In this case, as the concentration of methane increases, the particle size of the deposited diamond film decreases. . Therefore, by increasing the concentration of methane in the process gas injected during the deposition, it is possible to reduce the particle size of the resulting diamond film surface. However, when the diamond film 20 is deposited on the cutting tool 10 in this manner, the overall particle size of the surface of the diamond film 20 decreases as the methane concentration increases, but the edge portion 11 is still in the same specimen. ) Still have a relatively large particle size and roughness relative to the central portion 12. Therefore, there is a need for a method of reducing the relative particle size of the edge portion 11, which is a part mainly used for actual cutting.

As a method for controlling the particle size of the cutting edge portion 11 of the cutting tool 10, a method of applying a bias from the outside during the deposition of the diamond film has been proposed. While depositing the diamond film 20 on the cutting tool 10 using the above-mentioned chemical vapor deposition method, the same cutting is applied by simultaneously applying a negative bias which lowers the surface of the cutting tool 10 from the outside than other electrodes. In the tool 10, the diamond particles deposited on the cutting edge portion 11, which is mainly used for cutting the material, are based on the result that the diamond particles deposited on the center portion 12 have a finer particle size. This is because when the bias is applied to the cutting tool 10, the strength of the bias applied by the shape of the edge portion 11 is largely applied to the edge portion, thereby depositing finer diamond particles. However, in the case of the diamond film 20 deposited by applying a negative bias to the surface of the cutting tool 10 from the beginning of deposition, the Co content generated by applying a bias to the surface of the base material 14 is increased, and the Co is the base material. The adhesion between the 14 and the diamond film 20 is weakened, and the diamond film 20 is peeled off during the cutting process. This is a problem that the performance of the cutting tool is greatly reduced. Therefore, when depositing a diamond film while applying a bias to refine the particle size, a method for increasing the adhesion between the deposited diamond film and the base material is required.

The present invention is to solve the problems of the prior art, while depositing a diamond film on the base material of the cutting tool, while improving the adhesion between the base material of the cutting tool and the diamond film deposited on the base material of the particles to form a diamond film It is an object of the present invention to provide a method for manufacturing a cutting tool having a small size.

In order to achieve the above object, the present invention is a cutting tool manufacturing method for depositing a diamond film on the base material of the cutting tool placed in the chamber by using a chemical vapor deposition method, initially on the base material of the cutting tool without applying a bias A first step of depositing a diamond film of a predetermined thickness and a second step of depositing a diamond film on the diamond film deposited to a predetermined thickness while applying a direct current or alternating current bias to the cutting tool, thereby The particles of the diamond film can be made fine while maintaining the adhesion between the diamond films.

Hereinafter, a cutting tool manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings. 2 is a view schematically showing a thermal filament vapor deposition apparatus.

As shown in FIG. 2, a hot filament vapor chemical vapor deposition apparatus, which is one of devices for depositing diamond at high temperature using vapor chemical vapor deposition, includes a chamber 100 in which a deposition process is performed and a bias during deposition. It is composed of a power input unit 110 for applying. In the chamber, a heat filament 120 is supported by a support member 130 as a heat source, and a cutting tool 10 for depositing a diamond film on a holder 150 installed below the heat filament 120, see FIG. 1. ) Is placed. The base material of the thermal filament 120 and the cutting tool 10 is an electrode, and the thermal filament 120 is connected to a power supply for thermal filament (alternating) 111 to maintain a high temperature state, and the cutting tool 10 ) Is connected to a bias power supply (direct current or alternating current) 112 to apply a bias. The chamber 100 includes an inlet 101 through which process gas is introduced and an exhaust port 102 exhausted.

The apparatus is a device for using a thermal filament vapor phase chemical vapor deposition method for performing vapor phase chemical vapor deposition in a high temperature state, and the present invention can also use a plasma vapor phase chemical vapor deposition device for vapor phase chemical vapor deposition while maintaining a plasma state. The two devices differ in whether the process gas is maintained at a high temperature or a plasma state during deposition, but the basic configuration is the same. For convenience, the filament vapor deposition apparatus will be described below.

In the method for manufacturing a cutting tool according to the present invention, after installing the cutting tool 10 for depositing a diamond film on the holder 150 installed in the chamber 100, the process gas is introduced through the inlet 101, and heat Applying power to the filament 120 to deposit a diamond film, but after the first step of depositing a diamond film of a predetermined thickness on the base material 14 of the cutting tool 10 without applying a bias, the constant A second step of depositing a diamond film is performed on the diamond film deposited to a thickness by applying a direct current or alternating current bias using the bias power supply 112.

The base material of the cutting tool 10 is carbide of metals such as Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, Si, V and W, Si, Ti, Zr, Hf, V Nitrides of metals such as, Nb, Ta, Cr, Mo, Si, V, and W, and a combination of these and binders Ni, Co, Cu, etc. may be used. Ceramics and the like that do not have high electrical conductivity may be used as the base material of the cutting tool 10.

As the process gas, a mixed gas of a gas source containing carbon such as hydrocarbon, carbon vapor, CO or CO ₂ and hydrogen, oxygen, nitrogen, water vapor, fluorine (F ₂ ) or an inert gas, etc. may be used. For example, a mixed gas of hydrogen and methane may be used. At this time, the mixing ratio of the mixed gas depends on the conditions of the diamond film to be deposited, in the case of a mixed gas of hydrogen and methane, it is generally preferable to control the concentration of methane in the range of 0.5 to 10%, the deposited diamond In order to deposit a high quality diamond film having a small amount of non-diamond phase in the film, it is preferable to control the concentration of methane gas to within 3%.

It is preferable that the temperature of the heat filament in the chamber 100 is maintained at 1800 ° C to 2600 ° C in the first and second steps of depositing, and the power required for applying the bias in the second step is 10W to 1000W. desirable.

In the first step of the method for manufacturing a cutting tool according to the present invention, the cutting tool 10 is placed on the holder 150 in the chamber 100, the process gas is injected into the chamber 100, and power is supplied to the thermal filament 120. When the temperature of the heat filament is maintained at 1800 ° C. to 2600 ° C., the process gas is ionized to generate ions and the ions are deposited on the cutting tool 10 substrate. After about 10 to 15 hours of deposition, a diamond film of a certain thickness is formed on the cutting tool base material. As described above, the diamond film deposited without a bias does not generate Co between the base material and thus has a strong adhesion with the base material.

Subsequently, when a bias is applied to the cutting tool 10 placed on the holder 150 by using the bias power supply 112, ions of the process gas collide with the surface of the cutting tool. At this time, as the bias size (power) is increased, the energy of ions colliding with the tool surface is increased, so that the deposited particles are smaller, thereby forming a fine diamond film. Since the particle size of the diamond film is adjusted according to the bias size to be applied, the particle size of the deposited diamond film can be appropriately adjusted by adjusting the size of the bias. The diamond layer with the fine particles will have about 0.1 to 5 μm.

At this time, the bias power supply 112 is preferably 5 V _p (peak voltage) to 500 V _p (peak voltage) at the time of AC power supply, and 5 V to 500 V at the DC power supply. Also, the pressure in the chamber is preferably in the range of 10 torr to 760 torr. It is not preferable that a non-diamond phase (a kind of graphite phase) other than a diamond phase is obtained under conditions other than the bias voltage, the pressure, the temperature of the thermal filament described above, and the power required to apply the bias.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited by the Examples.

Example

The cutting tool (WC-Co, 10) was placed in the holder 150 of FIG. 2 and a process gas (97% H ₂ -3% CH ₄ ) was injected. The pressure inside the chamber 100 was 60 torr, and the flow rates were 480 sccm and 15 sccm, respectively. An alternating current was applied to the thermal filament 120 so that the thermal filament temperature was 2250 ° C., and a diamond film having a thickness of about 8 μm was deposited on the base metal of the cutting tool 10 by evaporation for about 10 hours. 3A is an electron micrograph of a diamond film deposited without applying a bias, and shows a shape of a regular diamond in which large facets are developed as shown in FIG. 3A. As discussed in the prior art, this increases the roughness of the diamond surface, which is not suitable for the precision cutting operation, and reduces the quality of the workpiece.

Scanning photomicrographs of the diamond film deposited for 2 hours, 6 hours and 8 hours while applying a direct current bias of 70 V _pms (root mean square voltage) to the cutting tool 10 having the diamond film having a predetermined thickness as shown in FIG. 3A. Are shown in Figs. 3b, 3c and 3d, respectively. 3B to 3D, it can be seen that as the time for depositing the diamond while applying the bias increases, the large facets shown in FIG. 3A gradually disappear to form a diamond film of small particles. Therefore, it can be seen that a diamond film having a fine surface particle size can be finally deposited by a method of depositing a film without applying a bias to a predetermined thickness at the initial deposition and depositing a diamond film while applying a bias thereon.

Figure 4a is a scanning microscope photograph showing the hardness test results for the diamond film deposited to a thickness of 20㎛ while applying the bias from the beginning, Figure 4b is a 8㎛ thickness of the diamond film after the deposition without the bias is applied again Scanning microscope photograph showing the hardness test results for the diamond film finally deposited to a thickness of 20㎛ while applying a bias, Figure 4c is after depositing the diamond film to 15㎛ thickness without applying a bias initially Scanning microscope photograph showing the hardness test result for the diamond film deposited to have a thickness of 20 μm while applying a bias, and FIG. 4D is a hardness test for the diamond film deposited to a thickness of 20 μm without applying a bias. Scanning micrograph showing the results. Hardness experiments observed the surface condition after pressing under a load of 60 kgf using a Rockwell indenter with a diamond cone on a 20 μm thick diamond film deposited on a cutting tool (WC-Co).

As described above, the diamond film deposited with the bias applied from the beginning of deposition (FIG. 4A) can clearly observe the region where the diamond film is separated from the base material around the indentation due to poor adhesion between the base material of the cutting tool and the diamond film. On the other hand, in the case of a diamond film deposited to a thickness of 20 μm while depositing a diamond film having a predetermined thickness without applying a bias at the initial stage of deposition and then applying a bias again (FIGS. 4B and 4C) without applying a bias from the beginning. It can be seen that the area where the base material and the diamond film were peeled off around the indentation could not be observed without a significant difference from the hardness test result of the diamond film deposited to 20 μm (FIG. 4D).

As described above, in the method for manufacturing a cutting tool according to the present invention, in depositing a diamond film on a base material of a cutting tool by vapor chemical vapor deposition, after the initial thickness is deposited without applying a bias to the cutting tool. After the deposition is applied while applying a bias, it is possible to manufacture a cutting tool in which a diamond film having a fine particle size is deposited with excellent adhesion to the base material.

Claims (8)

A method for manufacturing a cutting tool in which a diamond film is deposited on a substrate of a cutting tool placed in a chamber by using vapor chemical vapor deposition. A first step of depositing a diamond film of a predetermined thickness on the substrate of the cutting tool without initially applying a bias, and And depositing a diamond film over the diamond film deposited to a predetermined thickness while applying a direct current or alternating current bias to the cutting tool. The method of claim 1, When the bias power applied in the second step is DC power, 5 V To 500 V and 5 V _p (peak voltage) for AC power Cutting tool manufacturing method, characterized in that from to 500 V _p (peak voltage). The method of claim 1, The cutting tool base material is a carbide of metals such as Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, Si, V and W, Si, Ti, Zr, Hf, V, Nb, Ta Nitrides of metals such as Cr, Mo, Si, V and W, oxides of metals such as Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, Si, V and W And a combination of these and Ni, Co, Cu, which are binders. The method of claim 1, The process gas introduced into the chamber is a mixed gas of a gas source containing carbon such as hydrocarbon, carbon vapor, CO or CO _2, and hydrogen, oxygen, nitrogen, water, fluorine (F ₂ ) or an inert gas. Cutting tool manufacturing method. The method of claim 4, wherein The mixed gas is a cutting tool manufacturing method, characterized in that hydrogen and methane is mixed in a mixing ratio of 99.5: 0.5 to 90:10. The method of claim 1, Cutting tool manufacturing method, characterized in that the pressure of the process gas in the chamber in each step of 10 torr to 760 torr. The method according to any one of claims 1 to 6, Each step of depositing the diamond film is carried out in a thermal filament vapor deposition apparatus maintaining a high temperature state by the thermal filament, wherein the temperature of the thermal filament in each step is 1800 ° C to 2600 ° C, and the bias in the second step Cutting tool manufacturing method, characterized in that the power required to apply is 10W to 1000W. The method according to any one of claims 1 to 6, Each step of depositing the diamond film is performed in a plasma vapor deposition apparatus that maintains a plasma state, and the power required for applying the bias in the second step is 10 W to 1000 W. .

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