JPH08151297A - Production of diamond - Google Patents

Abstract

PURPOSE: To produce a vapor synthesized diamond better in abrasion resistance than that of a conventional diamond. CONSTITUTION: The concentration of a carbon source based on hydrogen in a raw material gas is changed with time and periodically to thereby vapor synthesize a polycrystal diamond having a value of full width at half maximum intensity (FWHM) within the range of 2-20 deg. in a locking curve of the (111) crystal face by making X-rays incident from the surface in the raw material gas in a method for vapor synthesizing the polycrystal diamond from the raw material gas consisting essentially of the hydrogen and the organic compound which is the carbon source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing diamond, and more particularly to a method for producing diamond for a tool having excellent wear resistance, heat resistance and fracture resistance.

[0002]

BACKGROUND OF THE INVENTION Since diamond has high hardness and high thermal conductivity, it is useful as a tool material, especially a tool material for cutting difficult-to-cut materials.

Diamond used as a tool material is classified into single crystal and polycrystalline. Single crystal diamond is a material excellent in its physical properties, but it is very expensive, and it is not easy to process it into a desired shape as a tool material, and it has the drawback of being cleaved. .

On the other hand, polycrystalline diamond as a tool material can be roughly classified into two types. One of them is a sintered diamond obtained by sintering a fine diamond powder at an iron group metal such as Co and diamond under stable ultra-high pressure and high temperature. This kind of sintering technology
For example, it is described in Japanese Examined Patent Publication No. 52-12126. Among the commercially available sintered diamonds, those having a grain size of several tens of μm or less may have excellent wear resistance without causing the cleavage phenomenon as seen in the above single crystal diamond. Are known. However, since the sintered diamond contains several percent to several tens percent of the binder, the diamond particles constituting the sintered body may fall off during cutting, and the diamond cutting edge may be chipped. This falling phenomenon becomes more remarkable as the wedge angle of the tool edge becomes smaller, and it has been difficult to make the sharp cutting edge made of sintered diamond long-lasting. Further, since sintered diamond contains a binder, it is inferior in heat resistance to a single crystal and is likely to be worn during cutting.

On the other hand, vapor-phase synthetic diamond, which is another polycrystalline diamond for tools, is dense and consists only of diamond, so that it is superior in heat resistance and wear resistance to sintered diamond, and moreover, has no chipping. It is unlikely to occur. Such vapor-phase synthetic diamond is generally a chemical vapor deposition (CVD) method that decomposes and excites hydrocarbons such as methane and a raw material gas containing hydrogen as a main component under low pressure.
It is made by.

As a cutting tool using vapor-phase synthetic diamond, for example, a diamond-coated tool in which a tool base is directly coated with diamond has been developed.
However, in the case of a diamond-coated tool, the adhesion between the tool substrate and the diamond thin film is important. For example, in a tool in which a diamond thin film is formed on a cemented carbide, the diamond thin film tends to peel during cutting. . Further, JP-A-1-153228 and JP-A-1-210201 disclose a technique of directly brazing a base material coated with vapor-phase synthetic diamond on a tool base body made of cemented carbide and using it as a cutting tool. There is.

[0007]

In the vapor phase synthetic diamond, the diamond surface immediately after vapor phase synthesis is rough, and if it is desired to make it the rake face of the cutting edge, it is necessary to carry out polishing finish. Therefore, in order to facilitate the finishing process,
Diamonds vapor-deposited on a substrate were often formed so that the (100) plane and / or the (110) plane were oriented parallel to the substrate plane. Therefore, in many cases, the surface of the diamond for tools, for example, the rake face of the cutting edge made of vapor-phase synthetic diamond is constituted by the (100) face or the (110) face. However, such (100) plane and (110) plane are preferable from the viewpoint of polishing finish as described above, but are not optimum from the viewpoint of wear resistance of the tool material.

An object of the present invention is to produce a vapor-phase synthetic diamond which is more excellent in wear resistance than conventional ones, in particular, a vapor-phase synthetic diamond for tools.

[0009]

A method for producing diamond according to the present invention is a method for vapor-phase synthesis of polycrystalline diamond from a raw material gas containing hydrogen and an organic compound as a carbon source as main components. In the raw material gas supply step of changing the concentration of the carbon source with respect to hydrogen periodically with time, whereby the FW of the rocking curve of the (111) crystal plane obtained by incident X-rays from the surface.
HM value (Full Width at Half Maximum Intensity) is 2
It is characterized by vapor-phase synthesis of polycrystalline diamond in the range of 20 ° to 20 °.

In the present invention, as the source gas, a first source gas in which the ratio of the number of carbon atoms to the number of hydrogen atoms (C / H) is greater than 0% and 1% or less, and the ratio (C / H) The second raw material gas whose content of () is more than 1% and 8% or less can be used. Then, in the raw material gas supply step, the supply of the first raw material gas and the supply of the second raw material gas can be alternately repeated. The supply time of the first source gas is preferably longer than the supply time of the second source gas.

In the present invention, when the supply time of the first source gas is a minute and the supply time of the second source gas is b minute, the relationship between a and b can be defined by the following equation. it can.

0.001≤b / (a + b) ≤0.5 The present invention is a method for synthesizing diamond in which the (111) crystal plane of diamond is strongly oriented. In the present invention, when the intensity of the (111) crystal face on the surface by X-ray analysis is set to 100, the (220) crystal face and the (31
It is possible to carry out vapor phase synthesis of polycrystalline diamond having strengths of 1) crystal face, (400) crystal face and (331) crystal face of 1 to 80, respectively.

In the present invention, various compounds such as hydrocarbons, alcohols and esters can be used as the organic compound which is a carbon source, but methane can be more preferably used as a carbon source.

As will be described below, the present invention is particularly suitable for producing tool diamonds, such as cutting tool diamonds.

[0015]

In order to obtain a vapor-phase synthetic diamond that is harder and less likely to wear, it is desirable to orient the (111) crystal plane. When providing diamonds for tools,
For example, in the case of a cutting tool diamond, the main face of the diamond crystal that constitutes the rake face is (1
11) surface is desirable. On the other hand, when the (111) planes are uniformly oriented in parallel, diamond comes to have a characteristic close to that of a single crystal and easily cleaves. Therefore, it is desired to manufacture polycrystalline diamond that is difficult to cleave while strongly orienting the (111) plane. The present invention meets this need.

Hereinafter, the present invention will be described in more detail with reference to a diamond for a cutting tool as an example.

For example, in the diamond for a cutting tool obtained according to the present invention, while the main diamond crystal plane constituting the rake face of the cutting edge is the (111) face,
The rake face is made of polycrystalline diamond. The rake face is composed of a large number of crystal grains in which the <111> crystal axes are oriented. The state of such a rake face is shown in FIG.
Can be shown schematically. In the figure, the arrow indicates the direction of the <111> axis, and the (111) plane is perpendicular to this direction. On the rake face 35,
The (111) plane is not oriented in a uniform direction, but
The orientation varies within a certain range. This variation (hereinafter referred to as (111) plane fluctuation) is important. If there is no fluctuation of the (111) plane on the rake face, the rake face has characteristics close to those of the (111) single crystal. The rake face composed of a (111) single crystal is not preferable because it easily cleaves. Fluctuations in the (111) plane are important in preventing defects due to cleavage.

The fluctuation of the (111) plane in the rake face can be defined by the FWHM value of the rocking curve of the (111) face obtained by making X-rays incident on the rake face. When the FWHM value is close to 0, the single crystallinity of the rake face is strong and the cutting edge is likely to be cleaved. On the other hand, FWHM
If the value is too large, it is enough for the rake face (111)
Since the surfaces are not oriented, it is not possible to obtain a cutting edge with excellent wear resistance. An appropriate range of fluctuations, that is, an appropriate range of FWHM value, imparts excellent wear resistance to the rake face. In the tool material produced according to the present invention, in the case of a cutting tool material, for example, a cutting tool material, the FWHM value of the rocking curve of the (111) surface obtained by injecting X-rays into the rake surface of the blade member is 2 ° to 20 °. Is. When the FWHM value is 0 ° to 2 °, the crystal grains forming the rake face are large, the single crystallinity is strong, and the tool material, that is, the cutting edge member is easily cleaved. When the FWHM value exceeds 20 °, sufficient orientation of the (111) plane cannot be obtained in the rake face, and it becomes difficult to obtain excellent wear resistance.

A diamond polycrystal having a FWHM value in the range of 2 ° to 20 ° with respect to the (111) plane can be formed by changing the concentration of carbon with respect to hydrogen with time and periodically. Typically, supply of a raw material gas having a low carbon concentration and supply of a raw material gas having a high carbon concentration are alternately and periodically repeated in the vapor phase synthesis of diamond. Specifically, the raw material gas (A) having a ratio of the number of carbon atoms to the number of hydrogen atoms (C / H) of more than 0% and not more than 1% is used as a raw material gas having a low carbon concentration, and the ratio (C / H A source gas (B) having H) of more than 1% and 8% or less is used as a source gas having a high carbon concentration. In the supply of the raw material gas, the supply period (Pa) of the raw material gas A,
The supply period (Pb) of the raw material gas B is alternately repeated.
It is preferable that Pa is longer than Pb, and Pb is intermittently repeated in a pulse shape between Pas. Pa for a minute,
If Pb is b minutes, the relationship between a and b can be defined by the following equation, for example.

0.01 ≦ b / (a + b) ≦ 0.5 (0
<A, 0 <b) In the supply of such a source gas, for example, Pa can be 0.5 to 30 minutes and Pb can be 0.5 to 5 minutes.

If the carbon concentration is not changed in this way,
It is difficult to give fluctuations in an appropriate range for the orientation of the (111) plane. For example, European patent application 0
319926 and European patent application 044957.
No. 1 describes a number of conditions for vapor phase synthesis using a raw material gas with a constant carbon concentration. Under these conditions, a (111) -oriented diamond is vapor-deposited while giving an appropriate range of fluctuation. It is difficult to get it done. 2 ° to 20 °
In order to form a diamond in which the (111) plane is oriented in the range of FWHM value of 1, it is not enough to constantly supply the raw material having a low carbon concentration. By supplying the raw material having a high carbon concentration intermittently, a large number of crystal nuclei can be generated, and an appropriate fluctuation can be brought about in the orientation of the crystal axis.

Incidentally, it is desirable that the surface of the diamond for a tool produced in the present invention, for example, the (111) plane from the rake surface of the cutting edge member to a depth of at least 20 μm is oriented as a major surface. For example, the intensity of the (111) plane by X-ray analysis on the rake face is 10
When set to 0, (220) plane, (311) plane, (40
The strengths of the (0) plane and the (331) plane are each about 80 or less,
For example, 1 to 80 is preferable, and more preferably about 1 each.
It is 0 or less, for example, 1 to 10. With respect to the surface roughness of the surface of the tool diamond, for example, the rake surface of the cutting tool diamond, it is preferable that R _max is 0.5 μm or less. The FWHM value of the rocking curve of the (220) plane is preferably 20 ° or more.

In the present invention, various vapor phase methods can be applied to the formation of diamond by vapor phase synthesis. For example, a CVD method that decomposes and excites a raw material gas by utilizing thermoelectron radiation or plasma discharge, and a CVD method that uses a combustion flame are effective. As the raw material gas, for example, a gas obtained by mixing hydrocarbons such as methane, ethane, and propane, organic carbon compounds such as alcohols and esters such as methanol and ethanol, and hydrogen as main components can be used. In addition to these, an inert gas such as argon, oxygen, carbon monoxide, water or the like may be contained in the raw material within a range not impairing the synthetic reaction of diamond and its characteristics.

In the present invention, the (111) plane can be formed with a certain range of fluctuation by changing the carbon concentration with respect to hydrogen with time in the above-mentioned CVD as described above. For the base material for vapor phase synthesis, for example, Si and Mo are preferably used. Such a base material can be separated and removed from diamond by melting, separation, etc. by mechanical processing or chemical treatment. The surface of the base material on which diamond is to be formed is preferably mirror-finished so that the surface roughness R _max is 1 μm or less, preferably 0.2 μm or less. C on the mirror-finished substrate surface
By VD or the like, diamond can be deposited with a thickness of, for example, about 20 to 3,000 μm. In the present invention, after the base material is separated or removed, the remaining diamond may be used as a tool diamond as it is, or may be processed into a suitable size by cutting or the like and used as a tool diamond.

The diamond material obtained by separating or removing the substrate can be brazed to the tool substrate in order to obtain the required tool. In brazing, the diamond surface side that was in contact with the base material, that is, the crystal growth start surface side can be set as the rake surface side of the cutting edge of the cutting tool, for example. Therefore, the surface side facing this surface side, that is, the end surface side of the crystal growth can be the normal brazing surface. This surface to be brazed includes IV of the periodic table
A metallized layer of a metal from group a, IVb, Va, Vb, VIa, VIb, VIIa or VIIb as well as any of these compounds can be formed prior to brazing. Brazing can be performed more effectively through this metallization layer.

Further, a cutting tool can be manufactured as described below while using the diamond synthesizing method according to the present invention. In one method, first, a substrate having a mirror-finished surface on which diamond is to be deposited is provided. Diamond is then deposited on this substrate surface according to the present invention. The base material on which diamond is deposited is separated or removed to obtain a diamond material as a blade member. Next, the diamond material is brazed to the tool base by using the side of the diamond material that was in contact with the base material as the rake surface.

In this method, first, diamond is deposited according to the present invention by vapor phase synthesis on a mirror-finished substrate surface. Therefore, in the diamond material obtained by separating or removing the base material after diamond synthesis,
The surface in contact with the base material is a mirror surface. This side is
It is not necessary to perform polishing finishing, or if necessary, simple polishing finishing is sufficient. Further, in the obtained diamond material, the surface in contact with the base material is occupied by the (111) surface having an appropriate fluctuation. Therefore,
If the diamond material is brazed to the tool base so that the surface that has been in contact with the base material becomes the rake surface, it is possible to easily obtain a tool having better wear resistance than conventional ones.

On the other hand, in the case of a diamond material produced by vapor phase synthesis, when the rake surface is not the surface in contact with the base material, the following problems occur. The other surface, for example, the growth end surface in vapor phase synthesis is also occupied by the (111) surface. However, this growth-finished surface is rough, and if it is intended to make it a rake surface, it is necessary to carry out polishing finishing, and such polishing is difficult due to the high hardness of the (111) surface. Moreover, the grain size of the diamond crystal on the growth end surface is relatively large, and if this is used as a rake surface, the high hardness of the (111) plane easily causes chipping during tool use. On the other hand, if the face that was in contact with the base material is a rake face, that face is flat and has a structure with a fine grain size, so that no defects occur and wear resistance is also improved. Are better. It is not necessary to polish this surface, or if necessary, simple processing is sufficient.

In another method, a substrate having a surface on which diamond is to be deposited is first prepared. Next, diamond is deposited on the substrate surface according to the present invention. Then, on the diamond obtained according to the invention, (1
11) After depositing another diamond layer so that a crystal plane having a hardness lower than that of the (11) plane is oriented, a diamond material as a blade member is obtained. Next, the diamond material is brazed to the tool base with the other diamond layer side as the rake face side of the cutting edge. After that, the other diamond layer is removed by mirror polishing to expose the (111) plane.

In this method, low hardness diamond is deposited on the (111) face diamond formed to a thickness of about 20 to 3000 μm. The crystal plane having a hardness lower than that of the (111) plane can be formed by a gas in which the carbon concentration is constantly increased with respect to hydrogen gas in the above-described CVD. The crystal plane having such low hardness is preferably, for example, the (220) plane. (11
The thickness of the diamond layer having a hardness lower than that of the surface 1) is preferably 50 μm, more preferably 10 μm. In this method, the diamond material as the cutting edge member may be prepared by separating or removing the base material from the diamond alone, or may be prepared with the diamond deposited on the base material. The obtained diamond material may be subjected to the next step as it is, or may be processed into an appropriate size by cutting, for example. The diamond material as the blade member is brazed to the tool base with the diamond layer side having low hardness as the rake face side. Therefore, when the diamond material obtained by separating the base material is brazed, the diamond surface side in contact with the base material, that is, the crystal growth start surface side is brazed. A metallization layer as described above may be formed on the surface to be brazed prior to brazing. Brazing can be effectively done through the metallization layer. next,
With respect to the brazed diamond material, low hardness diamond is removed by polishing. Then, the previously formed (111) plane diamond is exposed. In this step, the surface roughness of the rake face obtained by exposing the (111) face by mirror polishing is, for example, R
It is desirable that the _{maximum is} 0.2 μm or less. Further, it is preferable to suppress mixing of crystal planes other than the (111) plane in the rake surface obtained after mirror surface processing and in the vicinity thereof (for example, from the rake surface to a depth of 20 μm) as much as possible,
For example, the intensity of the (111) plane obtained by X-ray analysis is 100
, Then (220) plane, (311) plane, (400)
The strengths of the plane and the (331) plane are each preferably 80 or less, for example, 1 to 80, and more preferably 10 or less, for example, 1 to 10. According to this method, a more flat rake face can be obtained, so that mirror polishing can be easily performed.

Hereinafter, as an example, an example of preparing a diamond for a cutting tool and using the diamond to obtain a cutting tool will be shown, but the present invention is not limited to the method for producing the diamond for a cutting tool, and other It can also be applied to the preparation of diamond material.

[0032]

【Example】

Example 1 A Si base material mirror-finished to have R _{max of} 0.2 μm or less was prepared. 0.5mm diameter and 1 length for thermionic emission material
In a known hot filament CVD using a 00 mm linear tungsten filament, a polycrystalline diamond having a thickness of about 500 μm was deposited on a Si mirror surface under the following conditions.

A mixed gas of hydrogen and methane was used as a raw material gas. The total flow rate of the source gas was 1000 cc / min. The gas supply process as shown in FIG. 2 was adopted.
And low methane concentration gas molar ratio CH ₄ / H ₂ methane is 0.5% of hydrogen, CH ₄ / H ₂ to 3% of the high methane concentration gas and are alternately automatically from the raw material supplying device in accordance with a program Supplied. Specifically, the following ABCC-
This cycle was repeated with 16 minutes of D-E-F as one cycle.

A: CH ₄ / H ₂ 0% (H ₂ only), 1 minute B: CH ₄ / H ₂ 0 → 0.5%, 1 minute C: CH ₄ / H ₂ 0.5%, 10 minutes D: CH ₄ / H ₂ 0.5% → 3%, 1 minute E: CH ₄ / H ₂ 3%, 2 minutes F: CH ₄ / H ₂ 3% → 0%, 1 minute Was given.

Gas pressure: 80 Trr Filament temperature: 2100 ° C. Filament-substrate distance: 5 mm Substrate temperature: 920 ° C. Next, the polycrystalline diamond on the Si substrate is laser-cut into the size and shape required for the cutting edge of the tool. After that, the Si base material was dissolved and removed with hydrofluoric nitric acid to obtain a polycrystalline diamond blade member. In the obtained member, Ti having a thickness of 1 μm and Ni having a thickness of 2 μm were sequentially laminated on the end surface of crystal growth,
Using the surface on which the metallized layer was formed as a bonding surface, the blade member was vacuum brazed to the base metal of the cemented carbide (SPG422) using silver solder. R _max of the rake face of the cutting edge is 0.2
μm. The main part of the tool obtained by brazing is shown in FIG. Base metal 1 made of cemented carbide
The diamond edge member 2 is fixed to a predetermined region of the diamond via the brazing layer 3 and the metallized layer 4. The rake face 5 of the blade member 2 is preferentially constituted by the (111) face. Further, the flank 7 is provided on the end face of the blade member 2.
Are formed.

When X-rays are incident on the rake face of the blade member, θ
The strength was measured for each face index of the diamond by a −2θ scan. The results are shown in Table 1. In the table, (11
1) The strength of each surface is shown when the strength of the surface is 100.

[0037]

[Table 1]

Next, in order to quantitatively measure the fluctuation in the rake face of the (111) face, a rocking curve for the (111) face and the (220) face was obtained by using an ordinary X-ray fold analyzer. The FWHM value of the rocking curve for the (111) plane was 5 °. The FWHM value of the rocking curve for the (220) plane was 60 °.

Examples 2 to 8 In Example 2, the following 19 minutes was set as one cycle, and this cycle was repeated to prepare a diamond having a thickness of about 450 μm as Si.
It was deposited on the substrate. Except for this cycle, the same conditions as in Example 1 were used.

CH ₄ / H ₂ hours A: 0%, 1 minute B: 0 → 0.2%, 1 minute C: 0.2%, 10 minutes D: 0.2 → 1%, 1 minute E: 1 %, 2 minutes F: 1 → 5%, 1 minute G: 5%, 2 minutes H: 5 → 0%, 1 minute In Example 3, this cycle was repeated with the next 34 minutes as one cycle. Also, during the period E, O _{2 with} respect to CH _{4 is}
O ₂ was added at a molar ratio of (O ₂ / CH ₄ ) of 30%.
Diamond was deposited under the same conditions as in Example 1 except for this cycle.

CH ₄ / H ₂ (%) Time A: 0 1 minute B: 0 → 0.6 1 minute C: 0.6 10 minutes D: 0.6 → 3 1 minute E: 3 20 minutes F: 3 → 0 1 minute In Example 4, this cycle was repeated with the next 16 minutes as one cycle, and diamond having a thickness of about 500 μm was deposited. The other conditions were the same as in Example 1.

CH ₄ / H ₂ (%) Time A: 0 1 minute B: 0 → 0.2 1 minute C: 0.2 10 minutes D: 0.2 → 1.5 1 minute E: 1.5 2 Minute F: 1.5 → 0 1 minute In Example 5, the cycle of the next 16 minutes was repeated to obtain about 500
Diamond with a thickness of μm was vapor deposited. The other conditions were the same as in Example 1.

CH ₄ / H ₂ (%) Time A: 0 1 minute B: 0 → 0.8 1 minute C: 0.8 10 minutes D: 0.8 → 3 1 minute E: 3 2 minutes F: 3 → 01 min In Comparative Example 6, diamond was deposited in the same manner as in Example 1 except that CH ₄ / H ₂ was constant at 0.1%.

In Comparative Example 7, diamond was deposited in the same manner as in Example 1 except that CH ₄ / H ₂ was constant at 2%.

In Comparative Example 8, diamond was deposited in the same manner as in Example 1 except that CH ₄ / H ₂ was constant at 4%.

In these examples, CH ₄ / H ₂ (%)
The ratio values of 0.1, 0.2, 0.5, 0.6, 0.
8, 1, 1.5, 2, 3, 4, and 5, respectively,
0.05, 0.10, 0.25, 0.3, 0.39,
Corresponds to C / H ratios (atomic percentage, atm.%) Of 0.49, 0.73, 0.96, 1.4, 1.9 and 2.3.

A cutting tool was produced in the same manner as in Example 1 using the obtained diamond. Table 2 summarizes the relative intensities of the crystal planes with respect to the rake plane and the FWHM values of the rocking curves with respect to the (111) plane and the (220) plane for each of the obtained diamonds. Also, Example 1
Each sample obtained in ~ 8 was attached to a milling cutter, and 12% Si-containing Al in the engine block was attached.
The alloy cylinder head was milled. The milling conditions are as follows.

Peripheral speed: V = 1190 m / min Depth of cut: d = 0.5 mm Feed: f = 0.12 mm / blade Environment: wet The results of milling are also shown in Table 2.

[0049]

[Table 2]

The rocking curves for the (111) plane of Example 3 and Comparative Example 7 are shown in FIGS. 4 and 5.

Example 9 Using a Si substrate mirror-finished to have R _{max of} 0.2 μm or less, under the same synthesis conditions as in Example 1, polycrystalline diamond having a thickness of 250 μm was formed on the Si mirror surface.

Subsequently, hot filament CVD was performed under the following conditions to further deposit diamond on the formed diamond.

Source gas (flow rate): C ₂ H ₂ / H ₂ = 3
%, Total flow rate 1000 cc / min Gas pressure: 80 Torr Filament temperature: 2150 ° C. Filament-substrate distance: 7 mm Substrate temperature: 960 ° C. In the diamond layer formed afterwards, the strength ratio I of the (111) face to the (220) face is I ( 111) / I (220)
Was 0.08, and it was revealed that the (220) plane was strongly oriented substantially parallel to the substrate surface. The thickness of the diamond formed later was 20 μm. Si
After cutting the diamond on the base material with a laser into a size and shape required for a tool, the silicon base material was dissolved and removed with hydrofluoric nitric acid to obtain a diamond edge member. In the obtained diamond blade member, Ti having a thickness of 1 μm and Ni having a thickness of 2 μm were sequentially laminated on the surface in contact with the base material,
Using the surface on which the metallized layer was formed as a bonding surface, the blade member was vacuum brazed to the base metal of the cemented carbide (SPG422) using silver solder. The main part of the tool immediately after brazing is shown in FIG. Base metal made of cemented carbide 11
In a predetermined area of the brazing layer 13 and the metallization layer 1
A diamond edge member 12 is fixed via 4. In the blade member 12, a portion D _{1 having} a thickness of 250 μm from the joint surface 6 has a (111) plane oriented,
The region D ₂ having a thickness of 20 μm deposited thereon is (22
The (0) plane is oriented. Next, the region of the diamond layer 22 indicated by D ₂ in FIG. 6A was removed by lapping. The (111) surface of the diamond previously formed by this mirror polishing is exposed and the surface roughness R
A mirror surface with a _{maximum of} 0.1 μm could be obtained. The main part of the diamond cutting tool thus obtained is shown in FIG.
It shows in (b). The rake face 15 of the cutting edge member 12 is flattened, and most of it is composed of the (111) face.

Comparative Example 10 A hot filament CV was prepared using the same equipment as used in Example 1.
According to the D method, a 200 μm thick polycrystalline diamond was formed on the Si mirror surface under the following conditions.

Source gas (flow rate): CH ₄ / H ₂ = 3%,
Total flow rate 1000 cc / min Gas pressure: 80 Torr Filament temperature: 2150 ° C. Filament-substrate distance: 6 mm Substrate temperature: 920 ° C. Next, the polycrystalline diamond on the Si substrate is laser-cut into the size and shape required for the tool. After that, add
The base material was dissolved and removed to obtain a diamond blade member. When an X-ray analysis was performed on the obtained diamond blade member, the peak intensity ratio I (111) / I (220)
Was 0.1, and it was found that the (220) plane was strongly oriented. The FWHM value of the rocking curve of the (220) plane was 10 °. The cutting edge member thus obtained was brazed to a base metal of cemented carbide in the same manner as in Example 1.

In order to evaluate the performance of the diamond cutting tools produced in Example 9 and Comparative Example 10, a cutting test (turning) was carried out under the following cutting conditions.

Work Material: A390 Alloy (A-17% Si) Cutting Speed: 800 m / min Feed: 0.12 mm / rev Depth of Cut: 0.5 mm As a result of continuous cutting test for about 30 minutes, the maximum flank of each sample The wear width (V _Bmax : μm) was 48 μm in the sample of Example 9, showing good characteristics. On the other hand, in Comparative Example 10, when a continuous cutting test for 1 minute was performed, a large defect of 100 μm or more occurred.

[Brief description of drawings]

FIG. 1 is a schematic view showing fluctuations of a (111) plane in a tool diamond produced according to the present invention.

FIG. 2 is a diagram showing changes over time in the composition of the source gas in one specific example of the source gas supply process used in the present invention.

FIG. 3 is a cross-sectional view showing an outline of a diamond cutting tool produced in Example 1.

FIG. 4 is a diagram showing a rocking curve for the (111) plane of the diamond material produced in Example 3 according to the present invention.

5 is a diagram showing a rocking curve for a (111) plane of a diamond material produced in Comparative Example 7. FIG.

FIG. 6 is a schematic cross-sectional view showing a process for manufacturing a diamond cutting tool in Example 9.

[Explanation of symbols]

 1 base metal 2,12 cutting edge 3,13 brazing layer 4,14 metallization layer 5,15 rake face 6 joining face 7 flank face

Claims (6)

[Claims] 1. A method for vapor-phase synthesis of polycrystalline diamond from a raw material gas containing hydrogen and an organic compound as a carbon source as main components, wherein the concentration of the carbon source with respect to the hydrogen in the raw material gas changes with time. The method comprises a step of supplying a source gas that changes periodically and periodically, whereby an X-ray is incident on the surface to obtain (11).
1) The FWHM value of the rocking curve of the crystal plane is 2 ° to 2
A method for producing diamond, which comprises subjecting polycrystalline diamond in a range of 0 ° to gas phase synthesis. 2. A first source gas having a ratio of the number of carbon atoms to the number of hydrogen atoms (C / H) of more than 0% and not more than 1% as the source gas, and the ratio (C
/ H) is greater than 1% and equal to or less than 8%, and in the raw material gas supply step, the supply of the first raw material gas and the supply of the second raw material gas are alternately repeated. The method for producing a diamond according to claim 1, wherein: 3. When the supply time of the first source gas is a minute and the supply time of the second source gas is b minute, the relationship between a and b is defined by the following equation. The method for producing a diamond according to claim 2, which is characterized in that. 0.01 ≦ b / (a + b) ≦ 0.5 4. The (11) by X-ray analysis on the surface.
1) When the strength of the crystal face is 100, the (220) crystal face, the (311) crystal face, the (400) crystal face, and the (33)
1) The method for producing a diamond according to any one of claims 1 to 3, wherein polycrystalline diamond having a crystal plane strength in the range of 1 to 80 is subjected to vapor phase synthesis. 5. The method for producing diamond according to claim 1, wherein the carbon source organic compound is methane. 6. The method for producing a diamond according to claim 1, wherein the diamond is a diamond for a cutting tool.