JP2001322067A - Extra-abrasive grain coated with metal carbide, its manufacturing method and extra-abrasive grain tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide extra-abrasive grain coated with metal carbide and its manufacturing method preventing the separation of metal carbide from the extra-abrasive grain and the degradation of the extra-abrasive grain due to the influence of heat when sintering to form an abrasive grain layer, and to provide an extra-abrasive grain tool having a long tool life. SOLUTION: The extra-abrasive grains are held in a reaction chamber by heightening to a specified temperature, keeping the pressure reduced state of atmosphere, in the reaction chamber. Raw gas containing at least metal is then led in and held in the reaction chamber for a specified time, and the reaction chamber is exhausted so as to be in the pressure-reduced state. Steps of leading in the raw gas, holding and exhausting are repeated to coat the surface of the extra-abrasive grain with metal carbide. The extra-abrasive grain coated with metal carbide is provided with the extra-abrasive grain and a titanium carbide film formed to coat the surface of the extra-abrasive grain, and the average grain diameter of crystal grains of titanium carbide included in the titanium carbide film is 10 nm-30 nm.

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 a metal carbide-coated superabrasive, a metal carbide-coated superabrasive and a superabrasive tool, and more particularly to an abrasive for a superabrasive tool such as a diamond wheel. The present invention relates to a metal carbide-coated superabrasive used for a layer and a method for producing the same.

[0002]

2. Description of the Related Art Diamond or cubic boron nitride (CBN) is used as an abrasive for various superabrasive tools because of its excellent hardness and strength. In a superabrasive tool, a superabrasive layer is formed by molding and sintering a mixture of abrasive grains and a binder. Metal (metal bond), resin (resinoid bond), or vitreous inorganic substance (vitrified bond) is used as a bonding material for bonding the superabrasive grains.

[0003] However, for example, an iron-based metal (nickel, cobalt, iron) used as a binder reacts at the interface with super-abrasive grains such as diamond during high-temperature sintering for forming an abrasive layer. , There is a possibility that the abrasive grain strength is reduced. There is also a problem that the bonding force between the superabrasive and the bonding material is reduced. As a result, there is a problem that the wear resistance of the superabrasive tool is deteriorated, and the life of the tool is shortened.

[0004] In order to solve the above problems, there has been proposed a method of coating the surface of superabrasive grains with a metal carbide such as titanium carbide or silicon carbide. As a method of coating the metal carbide, there is a vapor deposition method, and the vapor deposition method includes a chemical vapor deposition (CVD) method and a physical vapor deposition (PVD) method.

Japanese Patent Application Laid-Open (JP-A) Nos. 61-297079 and 5-220668 disclose a method for enhancing the bonding force when the binder is a resin, and a method for sintering when the binder is a vitreous inorganic substance. In order to prevent the occurrence of thermal corrosion of the abrasive grains themselves, the surface of diamond powder or cubic boron nitride powder was coated with titanium carbide and titanium carbonate, or a CVD method was applied to coat a titanium carbonate film. A method has been proposed.

In Japanese Patent Application Laid-Open No. 11-189492, when a metal or resin having a low melting point is used as a binder, titanium carbide is deposited on the surface of diamond particles by sputtering to improve the heat resistance of the diamond particles. A method for forming a coating layer has been proposed.

[0007]

However, when the method of coating the surface of the superabrasive grains with the metal carbide using the CVD method as described above is employed, the formed metal carbide film is easily peeled off. There was a problem. There is also a problem that it is difficult to form a metal carbide film with a uniform film thickness on the surface of the superabrasive.

In the case where the PVD method is used to coat the surface of the superabrasive with a metal carbide film, the film is formed in an argon gas atmosphere having a low degree of vacuum. However, there is a problem that the metal is easily mixed into the metal carbide film, and the coating is easily peeled off. Further, when the PVD method is employed, there is a problem that it is difficult to set film forming conditions for forming a metal carbide film having a predetermined thickness. In the PVD method, there is also a problem that high-speed particles such as secondary electrons collide with the coating and form defects in the coating, which also makes it easy for the coating to peel off. Further, even when a metal carbide film is formed by employing the PVD method, it has been difficult to form a film with a uniform film thickness on the surface of the superabrasive grains.

[0009] It is said that the metal carbide film is easily peeled and the metal carbide film is difficult to be formed with a uniform film thickness in either case of employing the CVD method or the PVD method as described above. There was a problem. If a superabrasive layer is formed by molding and sintering a mixture of a superabrasive grain coated with a metal carbide film and a binder by a conventional CVD or PVD method, the metal carbide film is easily peeled off In addition, since it is not formed with a uniform film thickness, there is a problem that the hardness and strength of the superabrasive grains are liable to be deteriorated due to heat during sintering. As a result, there is a problem that the life of the superabrasive tool provided with the superabrasive layer is shortened, and the grinding performance such as sharpness is deteriorated.

Accordingly, an object of the present invention is to prevent the metal carbide from peeling off from the superabrasive grains, and to prevent the superabrasive grains from deteriorating due to heat during sintering for forming a superabrasive layer. It is an object of the present invention to provide a metal carbide-coated super-abrasive grain capable of preventing the occurrence of cracks and a method for producing the same.

Another object of the present invention is to provide a superabrasive tool having a long tool life.

[0012]

A method for producing a metal carbide-coated superabrasive according to one aspect of the present invention includes the following characteristic steps.

(I) A first step in which the temperature inside the reaction chamber is raised to a predetermined temperature and the super-abrasive grains are held in the reaction chamber while the atmosphere in the reaction chamber is reduced in pressure.

(Ii) In a reaction chamber holding superabrasive grains,
Second step of introducing a source gas containing at least a metal.

(Iii) A third step of holding the source gas in the reaction chamber for a predetermined time. (Iv) After the step of holding the source gas, a fourth step of evacuating the reaction chamber to reduce the pressure in the reaction chamber.

(V) repeating the second, third and fourth steps. By adopting the method for manufacturing a metal carbide-coated superabrasive grain configured as described above, a metal carbide film covering the surface of the superabrasive grain can be formed with a uniform film thickness. In addition, the average particle size of the metal carbide crystal grains contained in the metal carbide film covering the surface of
Method and PVD method. Furthermore, since the coating layer of the metal carbide can be formed on the surface of the superabrasive grains in a short time, the time for exposing the superabrasive grains to a high-temperature atmosphere in the manufacturing method is shortened, and the deterioration of the superabrasive grains is prevented. Can be.

Further, since the crystal grain size of the metal carbide contained in the metal carbide film coating the surface of the superabrasive grains can be reduced, the bonding force between the metal carbide film and the superabrasive grains can be increased. be able to. For this reason, the metal carbide film formed by the production method of the present invention is hard to peel off from the surface of the superabrasive. As a result, when mixing the metal carbide-coated superabrasive grains and the binder obtained by the above-described manufacturing method and forming a superabrasive layer by sintering, under the influence of heat during the sintering, It is possible to effectively prevent the hardness and strength of the superabrasive from deteriorating. Thus, when a superabrasive tool is manufactured using the superabrasive grains obtained by the manufacturing method of the present invention, it is possible to improve the grinding performance such as sharpness of the superabrasive tool and prolong the tool life. be able to.

In the method of the present invention for producing a metal carbide-coated superabrasive, the metal carbide is preferably titanium carbide or silicon carbide. When the surface of the superabrasive is coated with titanium carbide as a metal carbide, it is preferable to use a raw material gas containing titanium tetrachloride and methane.

In the method for producing a metal carbide-coated superabrasive according to the present invention, the superabrasive preferably includes diamond abrasive, cubic boron nitride abrasive, or a mixed abrasive thereof.

It is to be noted that the method for producing a metal carbide-coated superabrasive according to the present invention makes it possible to superfine the metal carbide film even when the superabrasive has a very small particle size, that is, when the superabrasive is fine. It can be easily formed on the surface of the grains. For example, the particle size of superabrasives is $ 800 or more (the average particle size is 40 μm
Even in the case of the following), if the manufacturing method of the present invention is adopted, a metal carbide film can be formed on the surface of the superabrasive.

[0021] A metal carbide-coated superabrasive according to another aspect of the present invention is manufactured using a manufacturing method having the above-described features.

Further, a metal carbide-coated superabrasive according to still another aspect of the present invention comprises a superabrasive, and a titanium carbide film formed so as to cover the surface of the superabrasive. The average particle diameter of the crystal grains of titanium carbide contained in the titanium carbide film is 10 nm or more and 30 nm or less.

As described above, by setting the average grain size of the crystal grains of the titanium carbide contained in the titanium carbide film covering the surface of the superabrasive grains to be 10 nm or more and 30 nm or less, the titanium carbide film and the superabrasive grains can be separated. The bonding force between them can be increased. Therefore, it is possible to effectively prevent the titanium carbide film from peeling off from the surface of the superabrasive grains. Thereby, mixing the metal carbide coated superabrasive with the above characteristics and the binder,
When the superabrasive layer is formed by sintering, it is possible to prevent the properties such as hardness and strength of the superabrasive grains from deteriorating due to heat during the sintering. Also,
It is possible to prevent the properties of the superabrasive grains from deteriorating due to the reaction between the binder and the superabrasive grains during sintering. As a result, in the superabrasive tool manufactured using the obtained superabrasive layer, the grinding performance can be improved and the tool life can be extended.

In the metal carbide-coated superabrasives of the present invention, the superabrasives preferably include diamond abrasives, cubic boron nitride abrasives, or mixed abrasives thereof.

A superabrasive tool according to still another aspect of the present invention includes an abrasive layer containing a metal carbide coated superabrasive produced by the method for producing a metal carbide coated superabrasive according to the present invention.

A superabrasive tool according to still another aspect of the present invention includes an abrasive layer containing a metal carbide-coated superabrasive, wherein the metal carbide-coated superabrasive includes a superabrasive and a superabrasive. A titanium carbide film formed so as to cover the surface of the superabrasive grains, wherein the average particle size of the crystal grains of titanium carbide contained in the titanium carbide film is 10 nm or more and 30 nm or less. It is.

In the superabrasive tool configured as described above, the wear resistance of the superabrasive layer can be improved, the grinding performance such as sharpness can be improved, and the tool life can be extended. it can.

In the superabrasive tool of the present invention, the superabrasive grains preferably include diamond abrasive grains, cubic boron nitride abrasive grains, or mixed abrasive grains thereof.

Further, in the superabrasive tool of the present invention, the abrasive layer includes a binder for binding the metal carbide-coated superabrasive,
The binder preferably comprises an iron-based metal, for example, iron, cobalt or nickel.

The metal carbide-coated superabrasive according to the present invention can prevent a reaction with a binder containing a ferrous metal, particularly during sintering for forming an abrasive layer, Deterioration of characteristics such as hardness and strength of the superabrasive can be prevented. In the case where a metal other than an iron-based metal, a resin, or a vitreous inorganic material is used as a bonding material for bonding the metal carbide-coated superabrasive particles according to the present invention, the bonding between the superabrasive particles and the bonding material is also possible. The force can be increased, and deterioration of the characteristics of superabrasive grains during sintering can be prevented.

The superabrasive tool of the present invention has a form such as a tool formed of only the superabrasive layer or a tool in which the superabrasive layer is fixed to a disk-shaped base metal or the like. May be.

[0032]

FIG. 1 is a diagram conceptually showing one embodiment of a method for producing a metal carbide-coated superabrasive according to the present invention.

As shown in FIG. 1, the average particle size is 20 to 40 μm.
A (diameter: 800) diamond powder was placed in a 100 ct (carat) (corresponding to a mass of 20 g) container, and this container was set inside an electric furnace. Thereafter, the degree of vacuum inside the electric furnace was set to 133 × 10 ⁻² Pa, and the temperature inside the electric furnace was raised to 900 ° C.

On the other hand, as shown in FIG. 1, liquid titanium tetrachloride (TiCl ₄ ) is heated to a temperature of 55 ° C. inside the heater, and hydrogen is added to the heated titanium tetrachloride at a flow rate of 2.8 liter / min. (H ₂ ) gas was added to generate titanium tetrachloride gas.

The titanium tetrachloride gas generated above and methane (CH ₄ ) gas at a flow rate of 2.5 L / min were introduced into the electric furnace for 12 seconds. Thus, titanium carbide was generated inside the electric furnace. The reaction is performed according to the following equation.

CH ₄ + TiCl ₄ → TiC + 4HCl At this time, by utilizing the difference between the pressure of the titanium tetrachloride gas and the methane gas introduced into the electric furnace and the pressure in the electric furnace, a container provided inside the electric furnace The generated titanium carbide (TiC) was injected into the diamond powder therein, that is, into the gaps between the diamond particles. After that, the introduction of the raw material gas was stopped and maintained for 7 seconds. Thereafter, the gas in the electric furnace and by-products other than titanium carbide were evacuated for 20 seconds, and the inside of the electric furnace was maintained at the original vacuum.

FIG. 2 shows the steps from the step of introducing the raw material gas to the step of exhausting the raw material gas. As shown in FIG. 2, the inside of the electric furnace is evacuated to a predetermined degree of vacuum in step A, and then the raw material gas is introduced into the electric furnace in step B, and the raw material gas is Hold the introduction stopped. These steps A, B, and C were repeated 1000 times as one cycle.

As shown in FIG. 1, nitrogen (N ₂ ) gas is used to replace the atmosphere inside the electric furnace.

As described above, a titanium carbide film was uniformly formed on the surface of the diamond abrasive grains. The thickness of the titanium carbide film is 300 nm at the maximum, and the average value is 220 nm.
nm (range of 140 nm to 300 nm). Further, the titanium carbide film was densely formed over the entire surface of the diamond abrasive grains. The average particle size of the titanium carbide crystal grains in the titanium carbide coating was 10 nm or more and 30 nm or less.

After uniformly mixing the obtained titanium carbide-coated diamond abrasive grains and a binder having the following composition,
This mixed powder was pressed at room temperature. The binder used contained 90% by mass of cobalt (Co), 7% by mass of copper (Cu), 1% by mass of tin (Sn), and 2% by mass of silver (Ag). The obtained compact is put into a sintering furnace and the temperature is 800
Sintered for 0.5 hours at ℃. The outer diameter is 100 mm and the inner diameter is 40 m by polishing the obtained sintered body.
m, a diamond wheel having a thickness of 0.18 mm was produced.

On the other hand, a diamond wheel similar to the above was manufactured using diamond abrasive grains not covered with titanium carbide.

Further, a diamond wheel was manufactured in the same manner as described above using diamond abrasive grains coated with titanium carbide by a conventional CVD method. The average thickness of the titanium carbide film formed by the conventional CVD method is 35
Although it was 0 nm, it varied greatly within the range of 100 to 500 nm. The average particle size of the crystal grains of titanium carbide contained in the titanium carbide coating film was larger than 30 nm and 70 nm.

A diamond wheel using the above-described titanium carbide-coated diamond abrasive grains of the present invention, a conventional diamond wheel using diamond abrasive grains not coated with titanium carbide, and a titanium carbide-coated diamond abrasive grain obtained by a conventional CVD method. A bar cutting test was performed using each of the diamond wheels used. The object of the cutting process was an alumina (Al ₂ O ₃ ) -titanium carbide (TiC) wafer having a thickness of 2 mm. The cutting conditions are a down cut method, a wheel peripheral speed of 4710 mm / min,
The feed rate of the cutting object was set to 200 mm / min, and the cutting depth was set to 3 mm.

FIG. 3 shows the cutting results. FIG. 3 shows the relationship between the number of cuts and the outer diameter wear amount (μm) of the wheel. When the number of cuts was 50, the wear amount of the diamond wheel of the present invention was 25 μm, and the wear amount of the diamond wheel without the titanium carbide coating was 33 μm. After 100 cuts, the outer diameter wear of the diamond wheel of the present invention is 45 μm, the outer diameter wear of the diamond wheel coated with titanium carbide by the conventional CVD method is 51 μm, and the diamond without titanium carbide coating The outer diameter wear of the wheel was 56 μm. As is apparent from the results, it is understood that the diamond wheel using the diamond abrasive grains coated with titanium carbide according to the present invention exhibits the least amount of wear.

In the above embodiment, the cycle consisting of steps A, B, and C in FIG. 2 was repeated 1000 times so that the thickness of the titanium carbide film became 300 nm at the maximum, but by changing this number, It is possible to control the thickness of the titanium carbide film.

The embodiments disclosed above are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the examples above, and includes all modifications and variations within the scope and meaning equivalent to the terms of the claims.

[0047]

As described above, according to the present invention, a metal carbide having a uniform thickness can be formed on the surface of a superabrasive. Further, since a coating made of metal carbide having a smaller average crystal grain size can be formed as compared with the conventional CVD method, the bonding force between the metal carbide coating and the superabrasive grains can be increased. Thereby, the coating can be effectively prevented from peeling off from the surface of the superabrasive grains, and the characteristic of the superabrasive grains due to the reaction with the binder during sintering for forming the superabrasive layer. Deterioration can be prevented. As a result, the grinding performance such as sharpness of a superabrasive tool using the metal carbide-coated superabrasive produced according to the present invention can be improved, and the tool life can be extended.

Further, according to the manufacturing method of the present invention, since the metal carbide film can be formed in a short time, the time for exposing the superabrasive grains to a high-temperature atmosphere can be shortened. Thereby, it is possible to prevent the superabrasive grains from deteriorating due to the thermal influence even in the process of producing the metal carbide coated superabrasive grains.

[Brief description of the drawings]

FIG. 1 is a view conceptually showing one embodiment of a method for producing a metal carbide-coated superabrasive according to the present invention.

FIG. 2 is a diagram showing a manufacturing process which is repeatedly performed in a method for manufacturing a metal carbide-coated superabrasive according to the present invention in relation to a gas pressure of a furnace atmosphere and time.

FIG. 3 shows the relationship between the outer diameter wear amount and the number of cuts of the diamond wheel manufactured in the embodiment of the present invention.
It is a figure shown in comparison with the conventional diamond wheel.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Atsushi Kakitsuji 2-7-1, Ayumino, Izumi-shi, Osaka Prefecture Inside the Osaka Prefectural Institute of Advanced Industrial Science and Technology (72) Daiki Miyamoto 2-7-1, Ayumino, Izumi-shi, Osaka No. 1 Inside Osaka Prefectural Institute of Advanced Industrial Science and Technology (72) Inventor Mizuho Nakata 2-80 Hohokucho, Sakai City, Osaka Prefecture Osaka Diamond Monument Industry Co., Ltd. (72) Masanori Hoshika 2, 80 Hohokucho, Sakai City, Osaka Prefecture Address: Diamond Diamond Industrial Co., Ltd. (72) Inventor: Yozo Ogura 2-80, Hokita-cho, Sakai City, Osaka Prefecture (72) Inventor: Toshio Fukunishi 2-80, Horikita-cho, Sakai, Osaka, Japan (72) Inventor Iihara sequentially 1-1-1 Kunyokita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works in the F-term (reference) 3C063 AA02 AB03 BA02 BB02 BB15 BC02 BC03 CC01 EE31 FF08 FF22

Claims (11)

[Claims] 1. A method for producing a metal carbide-coated superabrasive grain in which the surface of a superabrasive grain is coated with a metal carbide, wherein the temperature in the reaction chamber is increased to a predetermined temperature, and the atmosphere in the reaction chamber is depressurized. A first step of holding superabrasive grains in the reaction chamber; a second step of introducing a source gas containing at least a metal into the reaction chamber holding the superabrasive grains; and placing the source gas in the reaction chamber. 3rd holding for a predetermined time
And after the step of holding the source gas, a fourth step of evacuating the reaction chamber to a reduced pressure state, wherein the second, third, and fourth steps are repeated. A method for producing a metal carbide-coated superabrasive. 2. The method for producing a metal carbide-coated superabrasive according to claim 1, wherein the metal carbide is titanium carbide or silicon carbide. 3. The metal carbide is titanium carbide, and the source gas contains titanium tetrachloride and methane.
3. The method for producing a metal carbide-coated superabrasive according to item 1. 4. The metal carbide-coated super-abrasive according to claim 1, wherein the super-abrasive comprises diamond abrasive, cubic boron nitride abrasive, or a mixed abrasive thereof. A method for manufacturing abrasive grains. 5. The method according to claim 1, wherein:
14. A metal carbide-coated superabrasive produced by using the production method described in the above section. 6. A super-abrasive grain, and a titanium carbide film formed so as to cover the surface of the super-abrasive grain, wherein an average particle size of crystal grains of titanium carbide contained in the titanium carbide film is 10 nm. As described above, a metal carbide-coated superabrasive having a thickness of 30 nm or less. 7. The metal carbide-coated superabrasive according to claim 6, wherein the superabrasive includes diamond abrasive, cubic boron nitride abrasive, or a mixed abrasive thereof. 8. Any one of claims 1 to 4
A superabrasive tool comprising an abrasive layer containing a metal carbide-coated superabrasive produced by the production method described in the above section. 9. An abrasive layer comprising metal carbide-coated superabrasives, wherein the metal carbide-coated superabrasives are superabrasives, and a titanium carbide film formed so as to cover the surface of the superabrasives. A super-abrasive tool, wherein the average particle size of the crystal grains of titanium carbide contained in the titanium carbide film is 10 nm or more and 30 nm or less. 10. The superabrasive tool according to claim 9, wherein the superabrasive includes diamond abrasive, cubic boron nitride abrasive, or a mixed abrasive thereof. 11. The superabrasive tool according to claim 9, wherein the abrasive layer includes a binder for binding the metal carbide-coated superabrasive, and the binder includes an iron-based metal.