JPH06262406A - Cutting tool and its manufacture - Google Patents

Abstract

PURPOSE:To provide a tool where the cutting property is excellent and the life of the tool is long by making the diamond crystal film as the polycrystal film of the mode where a number of specific plate diamond crystal are synthesized in forming the diamond crystal film on the cutting surface by the vapor phase synthesizing method. CONSTITUTION:A cutting tool is provided with a specified diamond crystal film 2 manufactured by the vapor phase synthesis method on the cutting surface of a tool body 1, and the diamond crystal film 2 is made of the polycrystal film where the ratio of the length in the direction normal to the base material surface to the length in the direction parallel to the base material surface ranges from 1/4 to 1/1000, and a number of plate diamond crystal where the angle between the base material surface and the upper surface of the crystal ranges from 0 to 10 deg. are synthesized. In this cutting tool, the crystal forming density is controlled by using the selective deposition method, the plate diamond crystal is formed by the vapor phase synthesis method where the temperature of the base material is 400-900 deg.C, the diamond crystal film is obtained by executing the growth synthesis and the film growth of this crystal, and the cutter is formed by using this crystal film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool using a vapor phase synthetic diamond crystal, which is most suitable for finishing non-ferrous metals and non-metals, and a method for producing the cutting tool.

[0002]

2. Description of the Related Art In recent years, a diamond-coated cutting tool has been proposed in which a diamond coating layer is formed on the surface of a substrate of cemented carbide, cermet, ceramics or the like by a vapor phase synthesis method.

In particular, a proposal has been made for the purpose of increasing the growth rate of the diamond coating layer and improving the exfoliation resistance by using a mixed gas of hydrocarbon gas, hydrogen gas and oxygen gas as the reaction gas ( JP 63-
25478, JP-A-1-290591 and JP-A-4-223806).

[0004]

However, in a cutting tool using a vapor-phase synthetic diamond crystal deposited on a substrate by a conventional method, the diamond crystal film has various unevenness due to the non-uniformity of the substrate surface state. It is a polycrystalline film in which a large number of crystal grains having different orientations and a relatively small grain size are grown and united. Therefore, a phenomenon occurs in which the force applied to each diamond crystal particle is different due to the difference in the shape of the diamond crystal particles acting during cutting and the difference in the hardness wear due to the difference in the crystal orientation of the cutting action portion. When a cutting tool coated with such a polycrystalline diamond film is used to perform cutting, particularly continuous cutting, an unreasonable force is applied to some diamond crystals. There is a problem that the tool life is shortened due to peeling of the film itself.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a diamond cutting tool having an excellent diamond adhesion strength to the surface of a substrate and an excellent cutting property and having a long tool life.

[0006]

According to the present invention, the crystal density is controlled by the selective deposition method, the composition of the source gas is adjusted, and the substrate temperature is set to 400 to 900 ° C.
Using the VD method, combustion flame method, etc., the height / width is 1 /
A large number of flat diamond crystals having an angle of 4 to 1/1000 and an angle between the upper surface of the crystal and the surface of the substrate being 0 to 10 degrees are formed, and they are subjected to growth coalescence and film-like growth to form a polycrystalline diamond film. A cutting tool using a crystal film as a cutting surface.

Hereinafter, the present invention will be described together with the findings obtained in making the present invention.

In view of the problems of conventional cutting tools, the present inventors have conducted detailed experiments on the influence of the morphology of the vapor phase synthetic diamond crystal used on the cutting performance.
It was possible to clarify that the crystallinity and shape of diamond crystals are involved in cutting performance.

Therefore, an attempt was made to form a diamond crystal having good crystallinity. That is, by adding oxygen to a raw material gas for vapor phase synthesis at a specific ratio, a flat plate-shaped diamond crystal having good crystallinity with a small amount of dislocations and defects in the crystal (height / width value is 1 / 4 or less, generally 1 /
4.5 or less, and the angle formed by the substrate surface and the crystal upper surface is 0 to
(10 degrees) (hereinafter referred to as a flat plate diamond crystal) is obtained, and the flat plate diamond crystal is formed at least in the initial stage of nucleation, and the flat plate diamond crystal is grown and coalesced into a film-like polycrystal having a columnar structure. When a cutting tool was produced from the grown material, it was found that chipping or peeling at the time of cutting does not occur, and that it has good surface roughness, and that it is possible to perform cutting efficiently, and has reached the present invention. is there.

Further, for example, Japanese Patent Laid-Open No. 2-30 of the present inventors.
By using the selective deposition method of diamond crystals based on Japanese Patent No. 697, it is possible to selectively form diamond crystals only at a desired portion on the tool. Alternatively, by adjusting the nucleation density and nucleation site by the selective deposition method, it is possible to form a film in which flat-plate diamond crystals with a relatively large particle size grow and coalesce, and thereby achieve cutting performance close to that of a single-crystal diamond tool. A tool having can be made.

[0011]

The present invention will be described in detail below with reference to the drawings.

FIG. 3 is a schematic diagram of a cross section of a flat diamond crystal which is a unit crystal of the diamond crystal film of the present invention, and FIG. 4 is a schematic diagram of a cross section of a conventional particulate diamond crystal.
Shown in.

Reference numeral 31 in FIG. 3 denotes a substrate on which a flat diamond crystal 32 is formed. The ratio (h / L) of the length (height) h of the flat diamond crystal 32 in the direction perpendicular to the substrate surface and the length (width) L in the direction parallel to the substrate surface is generally ¼ or less, Is 1 / 4.5 or less, preferably,
It is 1/5 to 1/1000. The angle θ between the substrate surface 31a and the crystal upper surface 32a is 10 degrees or less, preferably 5 degrees.
It is below the degree.

In the particle-shaped diamond crystal 42 of the conventional example shown in FIG. 4, the ratio (h / L) of the height h to the lateral width L is 1/3 or more, and generally 1/2 or more. . 41
Is the substrate.

Hereinafter, the diamond crystal having such a form is referred to as a particulate diamond crystal. At this time, the angle θ formed by the upper surface of the particle and the substrate 41 is generally random.

Since flat diamond crystals have their upper surfaces oriented in the same direction, when they are grown and coalesced to form a polycrystalline film, the film thickness is uniform, the flatness is high, and the maximum surface roughness is 200 nm or less. In particular, it is 100 nm or less. Furthermore, since the lateral width is larger than the height, the adhesion to the substrate is larger than that of the particulate diamond crystal, and chipping or peeling during cutting is less likely to occur when a crystal film is formed. For this reason,
As in the present invention, a flat diamond crystal is formed at least at the time of nucleation, and the flat diamond crystal is grown and coalesced to form a film, and a cutting tool is produced by using the obtained diamond crystal film. It is possible to obtain a cutting tool having significantly improved cutting performance as compared with a cutting tool using a vapor phase synthetic diamond crystal film.

In particular, for the flat diamond crystal of the present invention, the crystal orientation can be arbitrarily determined depending on the growth conditions. For example, when the rake face is formed to be the {111} face (the substrate temperature will be described later). The upper surface can be made the {111} plane by adjusting),
Since the hardness of the {111} plane is high, it is possible to further improve the cutting performance.

Such a flat diamond crystal can be formed only by a method suitable for forming a crystal of very high quality, for example, a CVD method, a combustion flame method or the like described below. Hot filament CVD for CVD method
Method, microwave CVD method, magnetic field microwave CVD method,
There are a direct current plasma CVD method, an RF plasma CVD method and the like.

As the carbon source of the raw material gas used in the above gas phase synthesis method, hydrocarbon gas such as methane, ethane, ethylene, acetylene and the like, organic compounds which are liquid at room temperature such as alcohol and acetone, carbon monoxide or halogenated carbon Etc. can be used. Furthermore, hydrogen, oxygen, chlorine,
A gas containing fluorine can be added.

(1) Formation of Flat Diamond Crystals by CVD Method The source gas must contain at least hydrogen, carbon and oxygen, and the composition formula of one component of the source gas contains all of the above elements. Alternatively, a plurality of source gas components containing any element may be combined. in this case,
The carbon source concentration in the raw material gas needs to be 10% or less. The carbon source concentration here is (carbon source gas flow rate)
It is represented by x (number of carbon atoms in the composition formula of carbon source gas) / (total raw material gas flow rate) x 100.

Here, the number of carbon atoms in the carbon source gas composition formula is
For example, methane (CH ₄ ) is 1, propane (C ₃ H ₈ )
If it is 3, then it will be 3 if it is acetone (CH ₃ COCH ₃ ).
The reason for setting the carbon source concentration to 10% or less is to suppress the degree of supersaturation of diamond crystals, and particularly to suppress crystal growth in the height direction. There is no lower limit to the carbon source concentration, but it is 0.
If it is less than 01%, a practical formation rate of flat diamond crystals may not be obtained in some cases.

Further, in the CVD method, the ratio value (O / C) of the number of oxygen atoms to the number of carbon atoms in the source gas is 0.5 ≦ O / C ≦ 1.2, preferably 0.7 ≦ O. / C ≦
Set to 1.1. If it is less than 0.5, there is no effect of adding oxygen,
On the other hand, if it exceeds 1.2, it is not possible to obtain a practically usable diamond formation rate due to the etching effect of oxygen.
To adjust the O / C value, for example, O ₂ , H ₂ O,
An oxygen-added gas such as N ₂ O can be added to the raw material gas.

When an oxygen-containing organic compound such as alcohol is used as the carbon source, a flat diamond crystal can be formed even with a relatively low O / C value. For example, when hydrogen and ethanol (C ₂ H ₅ OH) are used as the source gas, a good quality flat diamond crystal can be formed at O / C = 0.5. Although the details of this reason are unknown, it is considered that in the case of an oxygen-containing compound, active species of oxygen (OH radical) are easily formed.

Further, the flat diamond crystal of the present invention is
It is formed when the nucleation density is relatively low. Plasma C
In the VD method and the hot filament CVD method, 2 × 10 ⁶
Flat diamond crystals are formed only when the number is less than or equal to 1 / mm ² , and the preferable generation density is 1 × 10 ² to 1 × 10 ⁵ /
mm ² .

Although the details of this reason are not clear, a sufficient amount of etching gas (hydrogen radical, hydrogen radical,
Or OH radicals), and in order to promote lateral growth, it is necessary that a sufficient amount of active species (CH _x radical species, etc.) involved in diamond formation reach the side surfaces. , It is thought that the nucleation density should be lowered.

(2) Formation of Flat Diamond Crystals by Combustion Flame Method Oxygen-acetylene flame is used in the combustion flame method, and the value of the molar ratio of oxygen gas, which is the main component in the raw material gas, to acetylene is 0. 9 ≦ O ₂ / C ₂ H ₂ ≦ 1.0, preferably 0.95 ≦ O ₂ / C ₂ H ₂ ≦ 0.99.
With this, the diamond crystal can be formed with good reproducibility and at a relatively high growth rate (tens of μm / hr: lateral growth rate).

In the case of the above combustion flame method, diamond crystals
Nucleation density of 1 × 10^Five Pieces / mm ² Below, preferably
1 x 10² ~ 1 x 10^Five Pieces / mm² And By combustion flame method
The reason why the nucleation density must be lowered is that of the combustion flame method.
In case of filament CVD method and microwave CVD method,
Overall, the lateral growth rate of flat diamond crystals is 10 times
This is because the above is (several tens of μm / hr).

In the case of increasing the nucleation in adjusting the nucleation density, a method of scratching the surface of the substrate with diamond paste or silicon carbide abrasive grains, such as diamond, silicon carbide, boron nitride, carbon nitride having a size of 1 μm or less is used. A method of coating fine particles on the surface of the substrate, a film of an iron-based metal such as iron, cobalt, or nickel is very thin on the surface of the substrate (several nm to several tens n
m) A forming method or the like can be used. Further, in order to reduce the nucleation density, a method of mirror-polishing the surface of the substrate by mechanochemical polishing, a method of annealing at 600 to 1000 ° C. in the air or an oxygen atmosphere, a reactive ion etching method, an ion beam etching. A method of performing dry etching treatment by the method, a method of performing wet etching treatment with various acids and alkalis, and the like can be performed. By the nucleation generation density adjusting method as described above, the nuclei of the flat plate diamond crystal can be formed on the substrate at a desired density.

The upper surface of the flat diamond crystal of the present invention is a {111} surface having a triangular or hexagonal morphology, and a {100} surface having a tetragonal or octagonal morphology. . The side surface is {11
1} plane or {100} plane.

In the cutting tool of the present invention, as described above, since the rake face is the {111} face, the hardness is higher. Therefore, the rake face is the {111} face and the flat diamond crystal is grown. Is desirable.

The morphology of this upper surface mainly depends on the temperature of the substrate during crystal formation. This substrate temperature is 40
When the temperature is 0 ° C. or higher and 900 ° C. or lower, preferably 600 ° C. or higher and 700 ° C. or lower, the upper surface becomes a triangular or hexagonal {111} plane.

The flat diamond crystal of the present invention is a single crystal or a twin crystal in which a twin plane is formed in a flat plate. In particular, it was formed at a substrate temperature of 400 ° C or higher and 900 ° C or lower,
In many flat diamond crystals having an upper surface of {111} plane, twin planes are formed parallel to the upper surface. This is because the formation of the twin plane forms a recessed angle, and the action called the recessed angle effect facilitates the growth of crystals in the direction of the recessed angle, which promotes the formation of flat diamond crystals. It is thought to be because. It should be noted that the number of twin planes formed parallel to the upper surface is not limited to one, and two or more twin planes may be formed.

The substrate used in the present invention includes oxide-based ceramics such as alumina / zirconia, carbide / nitride-based ceramics such as silicon carbide, silicon nitride, titanium carbide, titanium nitride and tungsten carbide, and WC-based ceramics. Metals such as cemented carbide, molybdenum, tungsten and tantalum can be used.

In the cutting tool of the present invention, the diamond crystal film may be directly formed on the tool support as shown in FIG. In the figure, 1 is a tool support, and 2 is a diamond crystal film. Further, as shown in FIG. 2, a diamond crystal film may be formed on another substrate and brazed on the tool support. At this time, the substrate with the diamond film may be directly brazed to the tool support (see FIG. 2).
A) The substrate may be removed and only the diamond film may be brazed to the tool support (FIG. 2B). In the figure, 21 is a tool support, 22 is a diamond crystal film, 23 is a base, and 24 is a brazing part.

Further, the flat plate diamond crystal may be formed only at a desired portion by the selective deposition method of the diamond crystal based on, for example, JP-A-2-30697 of the present inventors. Further, based on the above-mentioned JP-A-2-30697, a diamond crystal having a single nucleus may be used by sufficiently reducing the nucleation site to 10 μm ² or less. However, when a diamond crystal consisting of a single nucleus is formed in the combustion flame method, the nucleus generation density is smaller than that in other synthesis methods, and the nucleus generation site is 10 μm ²
If the content is less than the above, precipitation precipitation is likely to occur. Therefore, the value of the nucleation site is 100 μm ² or less and more than 10 μm ² , preferably 25 μm ² to 80 μm ² .

As the selective deposition method of diamond, for example, the method disclosed in Japanese Patent Laid-Open No. 2-30697 of the present inventors can be mentioned, but the method is not particularly limited to this method.

According to the method disclosed in Japanese Patent Laid-Open No. 2-30697, after the substrate surface is scratched, a patterned mask is formed on the substrate, an etching process is performed, and the mask is removed to remove the scratched portion. Is formed in a pattern. By applying a mask on the substrate pattern, subjecting the surface of the substrate to scratching, and further removing the patterned mask by etching,
A method of forming the scratched portion in a pattern may be used. Alternatively, a method may be used in which after the surface of the substrate is scratched, a patterned mask made of a heat-resistant material is applied to form the scratched portion in a pattern. The method of the scratching treatment using the diamond abrasive grains is not limited to a specific method, and examples thereof include polishing using the diamond abrasive grains, ultrasonic treatment, and sandblasting.

7A to 7 show an example of a method for selectively depositing diamond by forming a pattern on the surface of a substrate on which a portion damaged by diamond abrasive grains is applied.
A description will be given according to the schematic diagram of F. First, the surface of the base 71 is uniformly scratched by using diamond abrasive grains (FIG. 7A). A mask 72 is formed on the surface of this substrate (FIG. 7B). Although any material may be used as the material of the mask, for example, a resist formed in a pattern using a photolithography method (optical drawing method) or the like can be used. Next, the substrate 71 provided with the mask 72 is etched (FIG. 7C). This etching may be either dry etching or wet etching. In the case of wet etching, etching with a mixed solution of hydrofluoric acid and nitric acid can be used. Examples of dry etching include plasma etching and ion beam etching. As the etching gas for plasma etching, CF ₄ gas and CF ₄ gas to which a gas such as oxygen or argon is added can be used. As an etching gas for the ion beam etching, a rare gas such as Ar, He, Ne, oxygen, fluorine, hydrogen or C is used.
Gases such as F ₄ can also be used. Etching depth is 10 nm
Above, preferably 50-1000 nm, optimally 80-
It is about 200 nm. Next, the mask 72 is removed to obtain a patterned substrate surface that has been scratched (FIG. 7D).
When the flat-plate diamond crystal is formed by using the vapor-phase synthesis method, the flat-plate diamond crystal 73 is selectively formed only on the damaged portion (FIG. 7E). Further, the flat plate diamond crystal is grown and united to grow into a columnar shape, whereby a polycrystalline film 74 having a good surface flatness can be formed (FIG. 7F).

[0039]

EXAMPLES Next, the present invention will be described in detail based on examples.

Example 1 First, FIG. 1 was obtained by the combustion flame method.
A diamond crystal film was formed directly on the tool support as shown in FIG.

FIG. 5 is a schematic view showing a combustion flame method using an oxygen-acetylene flame burner, 51 is a burner and 52 is
Is a base, 53 is an internal flame, 54 is an external flame, and 55 is a base holder. Here the substrate holder is water cooled, whereby the substrate is cooled.

As the tool support, a commercially available tungsten carbide (WC) type cemented carbide processed into a predetermined shape was used.

The gas flow rate is acetylene: 2.0 liters /
min, oxygen: 1.9 l / min (O ₂ / C ₂ H
₂ = 0.95), the substrate temperature was 650 ° C., and the synthesis time was 5 hours. The diamond crystal film thus formed was a polycrystalline film having a thickness of about 80 μm and good flatness.

An observation sample was prepared under the same synthesis conditions as above except that the synthesis time was 15 minutes, and was observed using a scanning electron microscope. A flat diamond crystal having a height / width value of ⅕ or less was observed with the {111} plane of the above as the upper surface.

The side surface (flank surface) of the tip of the polycrystalline film is
A diamond-coated cutting tool was obtained by finishing it into a predetermined shape by machining and forming a cutting edge, and a cutting test was performed using it.

In the cutting test, an aluminum alloy having a diameter of 50 mm was attached to the spindle of the lathe, and the outer peripheral surface of the spindle was rotated at a spindle speed of 1: 1.
000rev / min, depth of cut: 0.05mm, feed:
It was carried out by continuous cutting for 24 hours under 0.1 mm / rev and dry processing conditions.

As a result, during the continuous cutting test, stable cutting resistance was exhibited and good surface roughness was maintained.

When the surface of the cutting tool after the cutting test was observed with a scanning microscope, the diamond film was not chipped, cracked or worn.

<Comparative Example 1> The flow rate of oxygen gas was lowered to reduce O ₂
A diamond crystal film was formed in the same manner as in Example 1 except that / C ₂ H ₂ = 0.85. In this case, the obtained diamond crystal film was a polycrystalline film with a large film thickness of about 100 μm and large irregularities.

An observation sample was prepared under the same synthesis conditions as above except that the synthesis time was 15 minutes.
As a result of observation using a scanning electron microscope, it was a particulate diamond crystal having a particle size of about 20 μm and a direction of the crystal upper surface being random.

The side surface (flank surface) of the tip of the polycrystalline film is
A diamond-coated cutting tool was obtained by finishing it into a predetermined shape by machining and forming a cutting edge, and a cutting test was performed using it.

The cutting test was carried out by the same continuous cutting for 24 hours as in Example 1.

As a result, the cutting resistance was gradually increased from the cutting time of about 15 hours, and the surface roughness of the cutting surface was deteriorated.

When the surface of the cutting tool after the cutting test was observed with a scanning electron microscope, chipping and cracking of the diamond film were observed, and further wear was observed.

Example 2 In this example, flat diamond crystals were formed by using the hot filament CVD method.

FIG. 6 is a schematic view showing an example of the hot filament CVD method using hydrogen-ethyl alcohol as a source gas. Reference numeral 61 is a quartz reaction tube, 62 is an electric furnace, 63 is a tantalum filament, 64 is a substrate, 65 is a raw material gas inlet, and a gas cylinder and an alcohol vaporizer (not shown), a flow rate regulator, a valve, etc. are provided at the inlet. It is connected.
A gas exhaust port 66 is connected to a pressure adjusting valve (not shown) and an exhaust system (mechanical booster pump to which a rotary pump is connected).

As the substrate, a WC-based cemented carbide substrate processed into a predetermined shape was used, and as a substrate pretreatment, a scratch treatment with silicon carbide abrasive grains (1 μm or less) was performed.

The flow rate of the raw material gas is hydrogen: 200 ml / mi
n, ethyl alcohol: 2 ml / min, filament temperature: 2050 ° C., substrate temperature: 660 ° C., pressure: 5.
6 × 10 ³ Pa, synthesis time: 24 hours. The diamond crystal film thus formed has a film thickness of about 75 μm.
Was a highly flat polycrystalline film.

An observation sample was prepared under the same synthesis conditions as above except that the synthesis time was 1 hour.
As a result of observation using a scanning electron microscope, a flat diamond crystal having a grain size of about 15 μm and a hexagonal {111} plane as an upper surface and a height / width value of ⅕ or less was observed.

The side surface (flank surface) of the end portion of the polycrystalline film is
A diamond-coated cutting tool was obtained by finishing it into a predetermined shape by machining and forming a cutting edge, and a cutting test was performed using it.

The cutting test was carried out by the same continuous cutting for 24 hours as in Example 1.

As a result, stable cutting resistance was exhibited and good surface roughness was maintained during the continuous test.

The surface of the cutting tool after the cutting test was observed with a scanning electron microscope.
No chipping or wear was observed.

Example 3 In this example, a flat diamond crystal was formed by a known microwave CVD method.

As the tool support, WC type cemented carbide was used after being processed into a predetermined shape.

As a condition for synthesizing a diamond crystal, gas is used.
Flow rate: Hydrogen: 100 ml / min, carbon monoxide: 5 m
l / min, substrate temperature 650 ° C., pressure: 5.6 ×
10 ³ Pa, microwave output: 550 W, synthesis time is 2
It was set to 0 hours. The diamond bond formed in this way
The crystal film is a highly flat polycrystalline film with a film thickness of about 70 μm.
It was

An observation sample was prepared under the same synthesis conditions as above except that the synthesis time was 1 hour.
As a result of observation using a scanning electron microscope, a flat diamond crystal having a grain size of about 15 μm and a hexagonal {111} plane as an upper surface and a height / width value of ⅕ or less was observed.

The side surface (flank surface) of the end portion of the polycrystalline film is
A diamond-coated cutting tool was obtained by finishing it into a predetermined shape by machining and forming a cutting edge, and a cutting test was performed using it.

The cutting test was carried out by the same continuous cutting for 24 hours as in Example 1.

As a result, stable cutting resistance was exhibited and good surface roughness was maintained during the continuous test.

The surface of the cutting tool after the cutting test was observed with a scanning electron microscope.
No chipping or wear was observed.

<Comparative Example 2> CO gas flow rate is 15 ml / m.
A diamond crystal film was formed in the same manner as in Example 3 except that the value was in. In this case, the obtained diamond crystal film was a polycrystalline film with large irregularities.

An observation sample was prepared under the same synthesis conditions as above except that the synthesis time was 1 hour.
Observation with a scanning electron microscope revealed that the diamond particles had a particle diameter of about 8 μm and the orientation of the crystal upper surface was random.

The tip side surface (flank surface) of the polycrystalline film is
A diamond-coated cutting tool was obtained by finishing it into a predetermined shape by machining and forming a cutting edge, and a cutting test was performed using it.

The cutting test was carried out by continuous cutting for 24 hours as in Example 1.

As a result, the cutting resistance gradually increased from the cutting time of about 18 hours, and the surface roughness of the cutting surface deteriorated.

When the surface of the cutting tool after the cutting test was observed with a scanning electron microscope, peeling and chipping of the diamond film were observed, and further wear was observed.

Example 4 In this example, a diamond crystal film was formed on another substrate and then brazed to a tool support to prepare a cutting tool as shown in FIG. 2A.

Furthermore, in this embodiment, the selective deposition method is used.
A flat diamond crystal was formed at a predetermined site.

A commercially available silicon nitride sialon substrate (Φ25 × 2 ^t ) was used as the substrate.

This substrate was put in ethanol in which diamond abrasive grains were dispersed, and scratched using an ultrasonic cleaner. Next, using a mask aligner, a resist pattern (PMMA-based resist) having a diameter of 2 μm is formed on the substrate.
It was formed at a pitch of 40 μm. Further, this substrate was put in an ion beam etching apparatus and subjected to etching treatment using argon gas. The condition is pressure: 2 × 10 ^-4 P
a, acceleration voltage: 500 V, current density: 0.5 mA / cm
² , processing time: 10 minutes. This processing depth is about 100
nm etching was performed. Further, after removing the resist and washing with an organic solvent, flat diamond crystal synthesis was carried out using the same hot filament CVD apparatus as in Example 2.

The synthesis condition is that the flow rate of the raw material gas is hydrogen: 200
ml / min, ethyl alcohol: 3 ml / min, filament temperature: 2100 ° C., substrate temperature: 650
C., pressure: 1.3 × 10 ⁴ Pa, synthesis time: 25 hours. The diamond crystal film thus formed is
It had a good smoothness with a film thickness of about 100 μm.

An observation sample was prepared under the same synthesis conditions as above except that the synthesis time was 1 hour.
When observed with a scanning electron microscope, it was a flat diamond crystal having a height / width value of ⅕ or less and a particle diameter of about 15 μm. In addition, this flat diamond crystal,
It was selectively formed on the position where the mask pattern was formed.

The silicon nitride sialon substrate on which the diamond crystal film is formed is cut into a predetermined size by using a laser processing machine, and the cutting edge is machined to obtain a tool material, which is used as a tool support. The above was brazed and bonded to obtain a diamond-coated cutting tool.

Using this diamond-coated cutting tool,
A cutting test was conducted under the following conditions.

In the cutting test, an aluminum alloy having a diameter of 50 mm was attached to the spindle of the lathe, and the outer peripheral surface of the spindle was rotated at a spindle speed of 10
00 rev / min, depth of cut: 0.05 mm, feed:
It was performed by continuous cutting for 48 hours under 0.1 mm / rev and dry processing conditions.

As a result, this cutting tool exhibited stable cutting resistance and maintained good surface roughness during the continuous cutting test.

The surface of the cutting tool after the cutting test was observed with a scanning electron microscope.
No cracking or wear was observed.

<Comparative Example 3> The flow rate of ethyl alcohol was 25
The diamond crystal film was formed and processed in the same manner as in Example 4 except that the substrate temperature was 1000 ° C., and the diamond-coated tool was obtained. in this case,
The deposited diamond crystal film was a polycrystalline film with large irregularities.

An observation sample was prepared under the same synthesis conditions as above except that the synthesis time was 1 hour.
As a result of observation using a scanning electron microscope, it was a particulate diamond crystal having a particle diameter of about 12 μm and a random orientation of the crystal upper surface. In addition, this diamond crystal,
It was selectively formed in the area where the mask pattern was formed.

The same cutting test as in Example 4 was conducted using the above diamond-coated cutting tool.

As a result, the cutting resistance gradually increased from the cutting time of about 20 hours, and the surface roughness of the cutting surface deteriorated.

When the surface of the cutting tool after the cutting test was observed with a scanning electron microscope, peeling and chipping of the diamond film were observed, and further abrasion was observed.

Example 5 In this example, a silicon single crystal substrate (30 mm square, 1 mm thick) was used as the substrate.

Substrate pretreatment (damage treatment, pattern formation, etching, etc.) was performed on this substrate in the same manner as in Example 4. A diamond crystal film was formed on this substrate by the same microwave plasma CVD apparatus as in Example 3.

As conditions for synthesizing diamond crystals, the gas flow rate was hydrogen: 200 ml / min, carbon monoxide: 12
ml / min, substrate temperature: 690 ° C., pressure: 5.6
× 10 ³ Pa, microwave output: 650 W, synthesis time was 30 hours. The diamond crystal film thus formed was a highly flat polycrystalline film with a film thickness of about 100 μm.

An observation sample was prepared under the same synthesis conditions as above except that the synthesis time was 1 hour, and the sample was observed using a scanning electron microscope.
A flat diamond crystal having a height / width value of ⅕ or less was observed with a hexagonal {111} plane of 5 μm as an upper surface. The flat diamond crystal was selectively formed in the mask pattern forming portion.

The silicon single crystal substrate on which the diamond crystal film is formed is cut into a predetermined size by using a laser beam machine, and the cutting edge portion is machined to finish the silicon single crystal substrate. The diamond polycrystal film alone was used as a tool material after being melted and removed by using, and was brazed and bonded to a tool support to obtain a diamond-coated cutting tool.

Using this diamond-coated cutting tool,
A cutting test was conducted under the same conditions as in Example 4.

As a result, during the continuous cutting test, stable cutting resistance was exhibited and good surface roughness was maintained.

Further, when the surface of the cutting tool after the cutting test was observed with a scanning electron microscope, the peeling of the diamond film was observed.
No chipping or wear was observed.

[0102]

As described above, the use of the diamond crystal film formed by the growth coalescence of flat diamond crystals in the cutting tool makes
It is possible to obtain a cutting tool that is excellent in abrasion resistance and that is unlikely to cause peeling or chipping of a diamond crystal film and that can perform continuous cutting under good cutting conditions for a long time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a cutting edge of an embodiment of a cutting tool of the present invention.

FIG. 2 is a cross-sectional view of a cutting edge of another embodiment of the cutting tool of the present invention, where A is a base having a diamond film brazed to a tool support, and B is only the diamond film. It is brazed.

FIG. 3 is a schematic cross-sectional view of a flat diamond crystal of the present invention.

FIG. 4 is a schematic cross-sectional view of a particulate diamond crystal prepared by a conventional method.

FIG. 5 is a schematic cross-sectional view in the vicinity of a forming portion when a diamond crystal is formed by a combustion flame method.

FIG. 6 is a schematic sectional view of a hot filament CVD apparatus.

FIG. 7 is a diagram showing a procedure for forming a diamond film of the present invention by a selective deposition method, where A is a substrate that has been subjected to a scratching treatment, B is a substrate of A that has been subjected to a patterned mask,
C is an etched B substrate, D is a C substrate mask removed, E is a flat diamond crystal selectively deposited on the D substrate, and F is an E crystal. FIG. 3 is a diagram of a polycrystalline film obtained by growing and coalescing.

[Explanation of symbols] 1 tool support 2 diamond crystal film 21 tool support 22 diamond crystal film 23 base 24 brazing part 31 base 32 flat plate diamond crystal 41 base 42 particulate diamond crystal 51 burner 52 base 53 inner flame 54 external flame 55 Substrate holder 61 Quartz reaction tube 62 Electric furnace 63 Filament 64 Substrate 65 Raw material gas inlet 66 Gas exhaust port 71 Substrate 72 Mask 73 Flat diamond crystal 74 Diamond film

Claims (4)

[Claims] 1. A cutting tool having a diamond crystal film formed on a cutting surface by a vapor phase synthesis method, wherein the diamond crystal film has a ratio of a length in a direction perpendicular to the base surface to a length in a direction parallel to the base surface. A cutting tool having a value of ¼ to 1/1000, and a polycrystalline film in which a large number of flat plate diamond crystals having an angle between the substrate surface and the crystal upper surface of 0 to 10 degrees are united. . 2. A flat diamond crystal is formed by a vapor phase synthesis method in which a crystal formation density is controlled by using a selective deposition method and a substrate temperature is 400 ° C. to 900 ° C., and the crystal is grown and coalesced into a film. As a diamond crystal film,
The method for manufacturing a cutting tool according to claim 1, wherein a cutting edge is formed using the crystal film. 3. A crystal formation density of 2 × 10 ⁶ pieces / mm ² or less, a vapor phase synthesis method of CVD method, a carbon source concentration of a raw material gas in the CVD method of 10% or less, and oxygen atoms per unit amount. The method of manufacturing a cutting tool according to claim 2, wherein the value of the ratio of the number to the number of carbon atoms is 0.5 to 1.2. 4. The crystal formation density is set to 1 × 10 ⁵ pieces / mm ² or less, the gas-phase synthesis method is set to a combustion flame method, and the ratio of oxygen to acetylene in an oxygen-acetylene flame of the combustion flame method is set to 0. The method for manufacturing a cutting tool according to claim 2, wherein the cutting tool is 9 to 1.0.