JP2019025614A - Diamond grains for tools and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diamond grain for a tool which has fracture resistance and can be manufactured at low cost, and a method for manufacturing the same. SOLUTION: In the diamond grain for a tool according to the present invention, a mixture 12 in which the diamond grain 1 is brought into contact with each other so as to be surrounded by the titanium grain 2 is arranged in a chamber 3 capable of vacuum exhaust and heating. While keeping the inside of the chamber 3 in a vacuum, the mixture 12 is heated at a temperature lower than the melting point of the titanium grains 2 to transfer titanium to the surface of the diamond grains 1. By introducing nitrogen into a nitrogen atmosphere, a film made of titanium carbonitride is formed on the surface of the diamond grain 1 to produce the diamond grain 1. [Selection diagram] Fig. 1

Description

  The present invention relates to diamond grains suitable for a tool used for removal processing such as cutting and polishing, and a method for manufacturing the same.

  Diamond is known as the hardest material on the earth and is industrially used for removing various hard and brittle materials. However, although diamond is a hard material, it has a defect that its toughness is lower than that of a metal material, and there is a problem in terms of fracture resistance when used for removal processing. For example, with regard to the processing of diamond tools using diamond abrasive grains, improvement of processing quality and reduction of processing costs are always an issue, and for this purpose, a tool capable of high-speed processing and having a long life is required. There is also a need to reduce the manufacturing cost of the diamond tool itself.

  Wear of the diamond tool proceeds due to abrasive grains falling off, abrasive grain defects and abrasive chemical wear. By improving the characteristics that lead to these wear factors, the tool life and machining quality will be improved. The removal of the abrasive grains can be improved by increasing the adhesion between the diamond and the metal layer to which the diamond is fixed, or by increasing the durability of the metal layer itself. Further, chemical wear of the abrasive grains can be improved by increasing the cooling capacity of the processed part.

  However, the loss of abrasive grains can be reduced by using high-strength diamond grains, but there is a problem that workability is deteriorated. Further, it can be reduced to some extent by slowing the processing speed, but there is a problem that the processing cost becomes high. As described above, the present situation is that there is no effective countermeasure for the defect of the diamond tool even if it is intended to be improved.

  On the other hand, as a means for improving the fracture resistance of a material, a method of applying a compressive stress to a material surface has been conventionally employed. There are various methods for applying compressive stress, and shot blasting is a typical example. In the field of hard thin films, in particular, it has been confirmed that thin films formed by physical vapor deposition have effects such as compressive stress that is difficult to be lost and increased fatigue strength. It is also well known that when materials with different coefficients of thermal expansion are bonded at high temperatures and cooled to room temperature, tensile stress is generated on the material side with a higher coefficient of thermal expansion and compressive stress is generated on the side of the material with a lower coefficient of thermal expansion. Phenomenon.

  Although not intended to give a compressive stress to diamond grains, many techniques have been proposed so far for coating the diamond grain surface with a material having a thermal expansion coefficient larger than that of diamond. For example, it is carried out for the purpose of improving the tool life by increasing the bondability between diamond grains and a binder or plating film for fixing the diamond grains, and reducing the dropout of abrasive grains. Although these methods result in compressive stress on the diamond grains, it cannot be said that the effect is sufficiently exerted.

  In Patent Document 1, for the purpose of obtaining diamond abrasive grains having improved bonding strength with a metal-based bond material for a metal bond diamond tool, (1) diamond powder and titanium, zirconium, chromium, molybdenum, One or more transition metals selected from tungsten and vanadium and a halogen substance are charged, and then heated to 600 ° C. or higher. (2) A halide of the metal is formed by the reaction between the transition metal and the halogen to form the diamond. (3) A method for producing a carbide-coated diamond powder by allowing the halide to decompose on the diamond surface while allowing the transition metal released by the decomposition to react with diamond is proposed. Yes.

  Patent Document 2 discloses a superabrasive tool such as diamond or cubic boron nitride for the purpose of preventing superabrasive deterioration due to the influence of heat during sintering for forming a superabrasive layer. The surface of the abrasive grains is coated with metal carbide. In this method for producing metal carbide-coated superabrasive grains, the temperature in the reaction chamber is increased to a predetermined temperature, and the atmosphere in the reaction chamber is reduced, and the reaction chamber is depressurized. A first step of holding the superabrasive grains, a second step of introducing a raw material gas containing at least a metal into the reaction chamber holding the superabrasive grains, and the raw material gas in the reaction chamber for a predetermined time. A third step of holding, and a fourth step of exhausting the reaction chamber and reducing the pressure after the step of holding the source gas, and comprising the second, third and fourth steps. By repeating Method of making a metal carbide coated superabrasive has been proposed.

  Patent Document 3 discloses a mixture or alloy of a combination of a metal capable of forming a stable carbide and a low melting point metal for the purpose of firmly fixing a metal layer to a diamond substrate, and diamond abrasive grains or abrasive grains. A method has been proposed in which a metal-coated diamond abrasive grain is produced by forming a layer of a molten alloy formed by heating on a diamond surface and placing it at the same time or further raising the temperature.

  Further, in Patent Document 4, the diamond surface is placed in contact with the metal powder contained in the container for the purpose of forming a bonding layer on the diamond surface to firmly bond the diamond to a different material such as metal. The inside of the container containing the diamond and the metal powder is evacuated, and the metal powder is heated at a temperature not lower than a temperature at which a metal carbide layer can be formed on the diamond surface and not higher than a melting point of the metal powder. A method for forming a metal carbide layer has been proposed.

Japanese Patent Laid-Open No. 2003-55649 JP 2001-332067 A JP-A-2-229878 JP 2001-220251 A

  As described above, with respect to processing using a diamond tool, improvement in processing quality and reduction in processing cost and tool manufacturing cost are required. In response to such a demand, by improving the wear factor of the diamond tool, the tool life can be extended and the processing quality can be improved. In Patent Documents 1 to 4 described above, since the diamond grain surface is coated with a material having a larger thermal expansion coefficient than diamond, the diamond grain is subjected to compressive stress, and the diamond abrasive grains are improved in wear due to wear. There is a possibility that.

  However, since Patent Document 1 is a method of chemically transferring a metal to diamond using a halogen such as iodine, an apparatus for treating halogen gas that is highly corrosive and toxic to the metal is necessary. There is a problem that the manufacturing cost becomes high. In this method, since the thickness of the carbide layer depends on the diffusion rate of carbon, it takes time to increase the thickness of the carbide layer, and there is a problem in terms of manufacturing cost.

  Since Patent Document 2 is also a method using a halogen compound gas containing titanium tetrachloride or the like, equipment such as an apparatus is expensive as in Patent Document 1.

  Since Patent Document 3 is a method of heating a metal to a melting point or higher, it is extremely difficult to separate the diamond grains from the metal after melting, and there are problems in terms of practical use and manufacturing cost.

  Since Patent Document 4 is a method of forming a metal carbide layer for the purpose of improving the bondability between diamond and metal, it cannot be said that the compressive stress applied to diamond is sufficient, and there is a problem in terms of improvement effect.

  As described above, all of the above patent documents have technical problems and cost problems, and it cannot be said that the processing quality is sufficient.

  In view of the above, the present invention has been made in order to provide diamond grains for tools that have fracture resistance and can be manufactured at low cost, and a manufacturing method thereof.

  The diamond particle for a tool according to the present invention is a diamond particle for a tool having a diamond particle having an average particle diameter of 1 μm to 1000 μm and a coating made of titanium carbonitride formed on the surface of the diamond particle, In the coating, the peak position of the diffraction line by X-ray diffraction using a copper target exists between the peak position at the Miller index (220) of titanium carbide and the peak position at the Miller index (220) of titanium nitride. ing.

  In the method for producing diamond particles for a tool according to the present invention, a diamond particle having an average particle diameter of 1 μm to 1000 μm is surrounded by titanium particles having an average particle diameter of 1 μm to 4000 μm in a container that can be evacuated and heated. A transfer step of transferring the titanium to the surface of the diamond grains by placing the mixture mixed in contact and heating the mixture at a temperature lower than the melting point of the titanium grains while keeping the inside of the container in a vacuum; A nitriding step of forming a coating made of titanium carbonitride on the surface of the diamond grains by introducing nitrogen into the container while maintaining the heating state of the transfer step to be in a nitrogen atmosphere.

  In another method for producing diamond particles for tools according to the present invention, a diamond particle having an average particle diameter of 1 μm to 1000 μm is surrounded by titanium particles having an average particle diameter of 1 μm to 4000 μm in a container that can be evacuated and heated. The transfer step of transferring the titanium to the surface of the diamond grains by placing the mixture mixed in contact with each other and heating the mixture at a temperature lower than the melting point of the titanium grains while keeping the inside of the container in a vacuum And removing the transferred diamond particles treated in the transfer step and placing the transferred diamond particles in a container capable of atmospheric heating and heating in a nitrogen atmosphere to form titanium carbonitride on the surface of the diamond particles. And a nitriding step for forming a film made of a material.

  Furthermore, in the above manufacturing method, the heating temperature is set to 700 ° C. or higher and 1000 ° C. or lower in the transfer step and the nitriding step.

  According to the present invention, it is possible to obtain high-quality diamond diamond for a tool having a high fracture resistance in which a coating made of titanium carbonitride is formed on the surface of the diamond grain, and transfer of titanium to the surface of the diamond grain. The process and the nitridation process of the transferred titanium make it possible to easily produce high-quality diamond grains for tools at low cost.

It is a schematic block diagram of the manufacturing apparatus for implementing this invention. It is a schematic cross section of the diamond grain for tools. It is a schematic cross section of a transfer diamond grain. 6 is a graph showing an X-ray diffraction result of a processed plate-like diamond in Example 2. 6 is a graph showing an X-ray diffraction result of a transferred plate-like diamond in Example 3. 6 is a graph showing an X-ray diffraction result of a processed plate-like diamond in Example 3.

  Hereinafter, embodiments according to the present invention will be described in detail. The diamond particle for a tool according to the present invention covers the surface of the diamond particle with a coating made of a plurality of types of materials, thereby utilizing the compressive stress generated between the plurality of types of materials to improve the fracture resistance of the diamond particles. It is something that is going to be raised.

  As the diamond grains used in the present invention, those having an average particle diameter of 1 μm to 1000 μm are preferable for tools. As such diamond grains, those usually available can be used. The shape of the diamond grains can be used in various forms depending on the application, and is not particularly limited.

  The material used for the coating formed on the surface of the diamond grains is preferably a material having adhesion and strength that can withstand high stress generated at the interface between the diamond and the coating material due to a difference in thermal expansion. High adhesion can be obtained by forming a chemically reactive layer between the diamond and the coating material. Such a material preferably forms a high hardness carbide-based material, and examples thereof include materials such as titanium, zirconium, hafnium, tungsten, molybdenum, tantalum, and alloy materials containing these materials. Of these, titanium is preferable because it has a lower melting point than other metals and high adhesion to diamond. Various types of titanium such as sponge titanium and granular titanium can be used. When titanium particles are used, it is preferable to use titanium particles having an average particle size of 1 μm to 4000 μm.

When titanium metal is transferred to the surface of the diamond grains, titanium carbide is formed near the interface between the titanium metal and diamond, but in general, titanium carbonitride has higher hardness or strength than titanium carbide. In addition, since the coefficient of thermal expansion is high, it is preferable as a material for the coating, and it is considered that a stronger compressive stress is generated. Specifically, titanium carbide has a hardness of 16 GPa and a thermal expansion coefficient of 7.8 × 10 ⁻⁶ / ° C., and titanium carbonitride has a hardness of 18 GPa and a thermal expansion coefficient of 8.1 × 10 ⁻⁶ / ° C. .

  The film made of titanium carbonitride formed on the diamond grain surface can be formed by heat-treating the film made of titanium carbide formed on the diamond grain surface in a nitrogen atmosphere.

  The melting point of titanium metal varies somewhat depending on the production method and the content and form of impurities. However, even at temperatures lower than the melting point of titanium metal by 500 ° C. or more, the titanium metal is bonded via the contact portion between the titanium metal and diamond by the chemical driving force. A film is formed so as to diffuse and cover the surface of the diamond, and the diamond surface can be treated. Specifically, if heat treatment is performed at a heating temperature of 700 ° C. to 1000 ° C., a film made of titanium carbide can be formed using a wide variety of titanium such as sponge titanium and granular titanium.

  After the titanium metal is transferred to the diamond surface to form a film made of titanium carbide, the transferred titanium is nitrided by supplying nitrogen gas into the container and putting it in a nitrogen atmosphere. A diamond particle for a tool on which a coating made of titanium carbonitride is formed is obtained. The heating temperature is not necessarily the same as the heating temperature at the time of transfer of titanium, but the temperature range to be selected is preferably set to 700 ° C. to 1000 ° C. as at the time of transfer.

  When particulate titanium is used, by appropriately setting the heating temperature according to the type of titanium, the titanium particles or the titanium particles and the diamond particles are not firmly bonded to each other, and after the coating treatment The tool diamond grains and titanium grains can be easily separated.

  The produced titanium carbonitride can be confirmed by X-ray diffraction, and the distribution of diffraction lines continuously appears as an intermediate phase between the respective diffraction peaks of titanium carbide and titanium nitride. Specifically, in an X-ray diffraction experiment using a copper target, if the diffraction angle of titanium carbide is 2θ = 60.448 ° and the diffraction angle of titanium nitride is 2θ = 61.812 °, the distribution of diffraction lines is Formation of titanium carbonitride can be confirmed in the range between the corners. Specifically, the formation of titanium carbonitride can be confirmed when there is a peak position between each peak position where the intensity is maximum in the distribution of diffraction lines of titanium carbide and titanium nitride. In order to confirm the presence of titanium carbonitride based on the peak position of the diffraction line, the mirror index of the diffraction line is set to (hkl) = (220) to ensure separation from other peak positions such as carbon. The peak position can be confirmed. Therefore, the presence of titanium carbonitride is caused by the fact that the peak position of the diffraction line exists between the peak position at the Miller index (220) of titanium carbide and the peak position at the Miller index (220) of titanium nitride. It becomes possible to specify.

  Next, the manufacturing method of the diamond particle for tools which concerns on this invention is demonstrated. FIG. 1 is a schematic configuration diagram of a manufacturing apparatus for carrying out the present invention. A vacuum exhaust device 5 is connected to the chamber 3 such as a quartz tube via an exhaust valve 8, and a nitrogen cylinder 9 is connected via a nitrogen supply valve 7. A pressure relief valve 10 is attached to the connecting pipe between the vacuum exhaust device 5. A heating device 6 is attached around the chamber 3 so that the entire chamber 3 is heated to a predetermined heating temperature. A mixture 12 of diamond grains 1 and titanium grains 2 is accommodated in a crucible 4 made of alumina and disposed in the chamber 3.

  In the mixture 12, the diamond particles 1 and the titanium particles 2 are uniformly mixed, and the diamond particles 1 are in contact with each other so that the titanium particles 2 surround the diamond particles 1. Although the diamond grain 1 having a pentagonal cross section is used, diamond grains having a different shape such as a plate can be similarly treated. It is also possible to treat differently shaped diamond grains simultaneously. Although it is considered that the melting point of the titanium particles 2 changes when impurities are included, there is no influence on the treatment, and a wide variety of titanium can be used. The crucible 4 in which the mixture 12 is disposed may be made of a material other than alumina as long as it has a heat resistance equal to or higher than the heating temperature and has a property that diffusion to the mixture 12 hardly occurs due to heating. The chamber 3 can also be made of other materials such as alumina as long as it can be evacuated and has heat resistance equal to or higher than the heating temperature, and is not particularly limited.

  After the mixture 12 is placed in the chamber 3, the exhaust valve 8 is opened and the vacuum exhaust device 5 is operated to exhaust the interior of the chamber 3. The pressure region is preferably a high vacuum as much as possible, but may be about 0.01 Pa or less practically. During the exhaust operation, the nitrogen supply valve 7 is set in a closed state.

  After evacuating the chamber 3 to a predetermined pressure, the chamber 3 is heated by the heating device 6 to heat the mixture 12 at a predetermined heating temperature, and a transfer process of titanium to the diamond grain surface is performed. The heating temperature is preferably 700 ° C. or higher, which is the temperature at which titanium is transferred to the diamond grain surface. On the other hand, when the titanium particles 2 are melted by heating, the titanium particles 2 are fixed to each other and the diamond particles 1 cannot be separated from the mixture 12, so that the heating temperature is preferably lower than the melting point of titanium. It is preferable to set it to 1000 ° C. or lower. At a heating temperature of 1000 ° C. or lower, although different depending on the form of titanium, various types of titanium can be processed so as not to melt. The heating temperature and the heating time can be set according to the thickness and properties of the titanium carbide coating to be produced.

  Next, while continuing heating by the heating device 6, the nitrogen supply valve 7 is opened to supply nitrogen from the nitrogen cylinder 9 into the chamber 3 and simultaneously the exhaust valve 8 is closed to set the inside of the chamber 3 to a nitrogen atmosphere. The mixture 12 is heated under a nitrogen atmosphere. Even after the chamber 3 is filled with nitrogen, the supply of nitrogen may be continued. The heating temperature is not necessarily set to the same temperature as the heat treatment in vacuum, but is preferably set to 700 ° C. to 1000 ° C. in consideration of transfer and melting of titanium. The heating temperature and the heating time can be set according to the thickness and properties of the titanium carbonitride film produced.

  Thereafter, the heating operation by the heating device 6 is stopped to cool the mixture 12. After cooling, the nitrogen supply valve 7 is closed, the mixture 12 is taken out from the chamber 3, and the titanium particles 2 are separated from the mixture 12 to obtain diamond grains for tools. FIG. 2 is a schematic cross-sectional view regarding tool diamond grains. The diamond particle for tool 14 has a coating 13 made of titanium carbonitride formed on the surface of the diamond particle 1. In the transfer process of titanium, the chemical driving force of surface diffusion in vacuum is used, and the heating temperature is not increased to the melting point of titanium. Therefore, when the diamond particles for the tool are separated from the mixture 12 after the process. It can be easily done with a sieve.

  Next, a modified example of the manufacturing method described above will be described. 1, after the mixture 12 is placed in the chamber 3 and heated in a vacuum in the same manner as described above, the heating operation of the heating device 6 is once stopped and the mixture 12 is removed. Cooling. After cooling, the nitrogen supply valve 7 is opened, nitrogen is introduced from the nitrogen cylinder 9, the gas in the chamber 3 is replaced, and the mixture 12 is taken out. In the replacement of the gas in the chamber 3 after cooling, a gas introduction port may be separately connected to the manufacturing apparatus shown in FIG. 1 to introduce and replace the atmosphere or inert gas.

  The extracted mixture 12 is separated from the titanium particles 2 using a sieve or the like, and the diamond particles 1 are extracted. A titanium transfer layer is formed around the diamond grains 1 and a film having a surface made of titanium carbide is formed. FIG. 3 is a schematic cross-sectional view of the treated diamond grains. Transfer diamond grains 16 in which a titanium transfer layer 15 is formed around the diamond grains 1 are obtained.

  The obtained transferred diamond grains 16 are again accommodated in the crucible 4 and placed in the chamber 3. Then, the exhaust valve 8 is opened and the vacuum exhaust device 5 is operated to exhaust the interior of the chamber 3. After exhausting to a predetermined pressure, the nitrogen supply valve 7 is opened to introduce nitrogen into the chamber 3 from the nitrogen cylinder 9 and at the same time the exhaust valve 8 is closed to make the inside of the chamber 3 a nitrogen atmosphere. If it is possible to make the inside of the chamber 3 into a nitrogen atmosphere by introducing nitrogen for a long period of time, it is not necessary to perform exhaust before introducing nitrogen. The transferred diamond particles 16 are heated by the heating device 6 while the introduction of nitrogen is continued even after the inside of the chamber 3 is made a nitrogen atmosphere. The heating temperature is not necessarily set to the same temperature as the heat treatment in vacuum, but is preferably set to 700 ° C. to 1000 ° C. in consideration of transfer and melting of titanium. The heating temperature and the heating time can be set according to the thickness and properties of the titanium carbonitride film produced.

  Thereafter, the heating operation by the heating device 6 is stopped and the processed diamond particles for the tool are cooled. After cooling, the nitrogen supply valve 7 is closed and the diamond diamond for tool is taken out from the chamber 3 to obtain the same diamond diamond for tool as shown in FIG.

  Examples will be described below.

[Example 1]
Diamond particles for tools were manufactured using the manufacturing apparatus shown in FIG. First, a commercially available alumina crucible is placed in a chamber (manufactured by Fujiwara Seisakusho Co., Ltd.), and titanium particles (manufactured by High Purity Science Laboratory; average particle size 600 μm to 2000 μm) and diamond particles (manufactured by Tomei Diamond Co., Ltd .; average A mixture in which a particle size of 500 μm) was uniformly mixed at a weight ratio of 6: 1 was put into an alumina crucible. After the mixture is set, the exhaust valve is opened and the vacuum exhaust device (manufactured by ULVAC Kiko Co., Ltd.) is operated to exhaust the chamber to a pressure of 0.002 Pa or less, and the heating device (manufactured by Asahi Rika Seisakusho Co., Ltd.) Were heated to 500 ° C., 550 ° C., 600 ° C., 650 ° C., 700 ° C., 750 ° C., 800 ° C., 850 ° C., 900 ° C., 950 ° C. and 1000 ° C. and held for 60 minutes.

  Then, while continuing heating at each heating temperature, the nitrogen supply valve was opened, nitrogen was introduced into the chamber from a nitrogen cylinder (manufactured by Uno Oxygen Co., Ltd.), and at the same time the exhaust valve was closed to make the inside of the chamber a nitrogen atmosphere. Thereafter, while introducing nitrogen, the nitriding treatment was performed at each heating temperature for 60 minutes.

  Thereafter, the heating operation of the heating device is stopped and the furnace is cooled. After the temperature in the chamber is lowered to 100 ° C. or lower, the introduction of nitrogen is stopped, the alumina crucible is taken out from the chamber, and titanium particles and diamond particles are screened. Treated diamond grains were obtained. The treated diamond grains treated at 700 ° C. or higher had a mixed color of gold and gray on the surface, whereas the treated diamond grains treated at 650 ° C. or lower had no color change.

[Example 2]
Next, in place of the diamond grains of Example 1, a cemented carbide substrate (Mitsubishi Materials Co., Ltd.) was used to treat the plate-like diamond coated with a diamond film having a thickness of about 15 μm using the same manufacturing apparatus as in Example 1. did.

  An alumina crucible was placed in the chamber, and a mixture in which plate-like diamond was embedded in titanium grains was accommodated in the alumina crucible. After the placement, the exhaust valve was opened and the vacuum exhaust device was operated to exhaust the interior of the chamber to a pressure of 0.002 Pa or less, heated with the heating device until the interior of the chamber reached 850 ° C., and held for 60 minutes.

  Thereafter, while continuing the heating, the nitrogen supply valve was opened to introduce nitrogen into the chamber from the nitrogen cylinder, and at the same time the exhaust valve was closed to make the inside of the chamber a nitrogen atmosphere. Thereafter, nitrogen was continuously introduced, and while maintaining the heating temperature of 850 ° C., nitriding treatment was carried out by holding for 60 minutes, 120 minutes, and 240 minutes.

  Thereafter, the heating operation of the heating device is stopped and the furnace is cooled, and after the inside of the chamber is lowered to 100 ° C. or less, the introduction of nitrogen is stopped, the alumina crucible is taken out from the inside of the chamber, and the plate-like diamond treated from the titanium grains Got. The treated plate-like diamond had a mixed color of gold and gray on the surface during each nitriding treatment time, and was similar to the diamond grains treated at 700 ° C. or higher in Example 1.

  X-ray diffraction data was measured for the treated plate-like diamond using an X-ray diffractometer (manufactured by Rigaku Corporation). In the measurement, a copper target was used and the Miller index was set to (220). FIG. 4 is a graph showing the analysis result of the X-ray diffraction data of the processed plate diamond. In the graph, the vertical axis represents intensity, the horizontal axis represents diffraction angle 2θ, and among the measured X-ray diffraction data, data where the diffraction angle 2θ where the (220) peak of titanium carbide and titanium nitride appears is around 61 °. Show. On the surface of the plate-like diamond, a peak position exists between titanium carbide having a diffraction peak at 60.448 ° and titanium nitride having a diffraction peak at 61.812 °, and titanium carbonitride is generated. It was confirmed that

[Example 3]
Next, it heat-processed in the vacuum similarly to Example 2 using the plate-shaped diamond used in Example 2. FIG. Thereafter, the heating operation of the heating device is stopped, the furnace is cooled, and the inside of the chamber is lowered to 100 ° C. or lower. Then, a nitrogen supply valve is opened, nitrogen is introduced from the nitrogen cylinder, and the gas in the chamber is replaced to obtain an alumina crucible. The plate-like diamond was taken out from between the titanium grains.

  The extracted plate-like diamond had a gray color similar to the color of the titanium grains, and it was confirmed that titanium was transferred to the diamond surface.

  The transferred plate-like diamond was subjected to X-ray diffraction in the same manner as in Example 2. FIG. 5 is a graph showing the analysis result of the X-ray diffraction data of the transferred plate-like diamond. On the diamond surface, a peak appeared at the same diffraction angle as that of titanium carbide having a diffraction peak at 60.448 °, and it was confirmed that titanium carbide was formed.

  Thereafter, the plate-like diamond transferred again was accommodated in an alumina crucible placed in the chamber. Then, the exhaust valve is opened and the vacuum exhaust device is operated to exhaust the interior of the chamber. When the pressure is reduced to 0.002 Pa or less, the nitrogen supply valve is opened to introduce nitrogen into the chamber from the nitrogen cylinder and simultaneously the exhaust valve is closed. The inside of the chamber was made a nitrogen atmosphere. While the introduction of nitrogen was continued, the inside of the chamber was heated to 850 ° C., 950 ° C., and 1000 ° C. with a heating device, and held for 240 minutes.

  Thereafter, the heating operation of the heating device was stopped and the furnace was cooled. After the inside of the chamber was lowered to 100 ° C. or lower, the introduction of nitrogen was stopped, and the treated plate diamond was taken out from the alumina crucible.

  The treated plate diamond was subjected to X-ray diffraction in the same manner as in Example 2. FIG. 6 is a graph showing the analysis result of the X-ray diffraction data of the processed plate diamond. From the graph, as in Example 2, the diamond surface has a peak position between titanium carbide having a diffraction peak at 60.448 ° and titanium nitride having a diffraction peak at 61.812 °. It was confirmed that titanium carbonitride was formed.

DESCRIPTION OF SYMBOLS 1 ... Diamond grain, 2 ... Titanium grain, 3 ... Chamber, 4 ... Alumina crucible, 5 ... Vacuum exhaust apparatus, 6 ... Heating apparatus, 7 ... Nitrogen supply valve, 8 ... exhaust valve, 9 ... nitrogen cylinder, 10 ... pressure relief valve, 12 ... mixture of diamond grains and titanium grains, 13 ... coating made of titanium carbonitride, 14 ...・ Diamond grains for tools, 15 ... Titanium transfer layer, 16 ... Transfer diamond grains

Claims (4)

  A diamond particle for a tool having diamond particles having an average particle diameter of 1 μm to 1000 μm and a film made of titanium carbonitride formed on the surface of the diamond particle, the film being an X-ray using a copper target The diamond particle for tools in which the peak position of the diffraction line by diffraction exists between the peak position at the Miller index (220) of titanium carbide and the peak position at the Miller index (220) of titanium nitride.   In a container that can be evacuated and heated, a mixture in which the diamond particles having an average particle diameter of 1 μm to 1000 μm are contacted and mixed so as to be surrounded by titanium particles having an average particle diameter of 1 μm to 4000 μm is placed in the container While maintaining the inside of the container in a vacuum, the mixture is heated at a temperature lower than the melting point of the titanium particles to transfer the titanium to the surface of the diamond particles, and the container is kept in the heated state of the transfer step. And a nitriding step of forming a film made of titanium carbonitride on the surface of the diamond grains by introducing nitrogen into the nitrogen atmosphere.   In a container that can be evacuated and heated, a mixture in which the diamond particles having an average particle diameter of 1 μm to 1000 μm are contacted and mixed so as to be surrounded by titanium particles having an average particle diameter of 1 μm to 4000 μm is placed in the container Heating the mixture at a temperature lower than the melting point of the titanium grains while keeping the inside vacuum, and transferring the titanium to the surface of the diamond grains, and taking out only the transferred diamond grains treated in the transferring process And a nitriding step of forming a film made of titanium carbonitride on the surface of the diamond particles by disposing the transferred diamond particles in a container that can be heated in an atmosphere and heating in a nitrogen atmosphere. Production method of grain.   4. The method for producing diamond grains for a tool according to claim 2, wherein in the transferring step and the nitriding step, the heating temperature is set to 700 ° C. or higher and 1000 ° C. or lower.

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