JP5289829B2 - Polycrystalline diamond dresser - Google Patents

Description

  The present invention relates to a dresser for removing clogging or spillage formed on the surface of a grinding wheel, and even restoring the sharpness of the grinding wheel.

  Conventionally, single-crystal diamond has been used as a dresser material. For example, as shown in Non-Patent Document 1 and Patent Document 1, a dresser made of single crystal diamond uses the apex of the polyhedron as a blade and applies it to the surface of a grinding wheel to remove clogging and spilling on the surface. Used to restore the sharpness of the grindstone. This dresser made of single crystal diamond used the (100) plane or (111) plane as the acting end face, but the (100) plane has poor wear resistance and the (111) plane has the property of being easily cleaved. There is a problem that it breaks during use because it has.

  On the other hand, sintered diamond may be used as a measure against cleavage cracks. In this sintered diamond, diamond particles are sintered using a metal binder such as cobalt, and the metal binder exists between the diamond particles. However, since the metal binder part is softer than the diamond particles, it is considered that the metal binder part wears in a short time. It is also conceivable to remove the metal binder by dissolving it with an acid, but it is thought that the amount of wear increases because the retention of diamond particles decreases.

  In addition, there is a polycrystalline diamond obtained by a CVD method (chemical vapor deposition method) as a polycrystalline diamond not including a metal binder. However, this polycrystalline diamond has a problem in that it has a large amount of wear due to its low interparticle bonding force.

Diamond Technical Overview, Diamond Industry Association JP 59-30668 A

  An object of the present invention is to provide a dresser that can be processed more stably for a longer period of time than a dresser that uses a single-crystal diamond or a diamond sintered body containing a metal binder.

  As a result of diligent research on a dresser material, the inventors of the present invention are a diamond polycrystalline body that does not contain a metal binder such as cobalt as a dresser material, and the diamond sintered body constituting the diamond polycrystalline body. The average particle size of the particles is greater than 50 nm and less than 2500 nm, the purity is 99% or more, and the sintered particles have a D90 particle size of (average particle size + 0.9 × average particle size) or less. The present invention was completed by finding that a dresser can obtain stable processing for a long period of time by using a polycrystalline diamond.

That is, the present invention is a dresser as described below. (1) A diamond polycrystalline body obtained by converting and sintering a carbon material having a graphite-type layered structure under an ultrahigh pressure and high temperature without adding a sintering aid or a catalyst, and constituting the diamond polycrystalline body The average particle size of the diamond sintered particles is greater than 50 nm and less than 2500 nm, the purity is 99% or more, and the D90 particle size of the diamond sintered particles is (average particle size + average particle size × 0.9). A dresser comprising the following polycrystalline diamond.
(2) The dresser according to (1), wherein the diamond has a D90 particle size of (average particle size + average particle size × 0.7) or less.
(3) The dresser according to (1), wherein the diamond has a D90 particle size of (average particle size + average particle size × 0.5) or less.
(4) The dresser according to any one of (1) to (3), wherein the polycrystalline diamond has a hardness of 100 GPa or more.

  According to the dresser of the present invention, it is possible to obtain a stable process for a long period of time as compared with a dresser using a diamond sintered body containing a conventional single crystal diamond or metal binder.

First, the polycrystalline diamond constituting the dresser according to the present invention will be described in detail below.
The diamond polycrystal having a diamond single phase (purity 99% or more) substantially free of a metal binder such as cobalt, which is a material of the dresser of the present invention, is graphite (which is a carbon material having a graphite-type layered structure as a raw material). It can be obtained by using graphite and converting it directly to diamond without any catalyst or solvent under high pressure and high temperature (temperature: 1800 to 2600 ° C., pressure: 12 to 25 GPa) and simultaneously sintering. The dresser made of polycrystalline diamond thus obtained does not cause uneven wear as seen in a dresser using a single crystal.

  The hardness of the polycrystalline diamond constituting the dresser is preferably 100 GPa or more. If the hardness of the polycrystalline diamond is less than 100 GPa, the life of the die is shortened. For this reason, in this invention, the hardness required as a dresser is ensured by making the average particle diameter of the diamond sintered particle which comprises a diamond polycrystal body more than 50 nm and less than 2500 nm. On the other hand, when the average particle size is 50 nm or less and 2500 nm or more, the hardness is less than 100 GPa, and wear progresses in a short time, so that stable processing for a long time cannot be obtained.

In the present invention, the D90 particle size of the diamond sintered particles constituting the diamond polycrystal is set to (average particle size + 0.9 × average particle size) or less. This is to suppress abnormal wear.
The D90 particle size is more preferably (average particle size + 0.7 × average particle size) or less, and the D90 particle size is further preferably (average particle size + 0.5 × average particle size) or less. In addition to the above configuration, in the present invention, the purity of diamond in the polycrystalline diamond is 99% or more.

  The average particle diameter in the present invention is a number average particle diameter measured by using a TEM (transmission electron microscope), and details of the measurement method will be described later. Moreover, the average particle diameter and D90 particle diameter of the sintered particles of the polycrystalline diamond can be controlled by controlling the particle diameter of the starting material and the sintering conditions.

In the polycrystalline diamond, the case where the numerical value of the average particle diameter of the sintered particles and the numerical value of the D90 particle diameter satisfy the above relationship is shown as a specific numerical value as follows.
Example 1: When the average particle size is 60 nm, the D90 particle size is 114 nm or less. Example 2: When the average particle size is 100 nm, the D90 particle size is 190 nm or less. Example 3: When the average particle size is 500 nm, the D90 particle size is 950 nm or less.

A method for producing a diamond sintered body using diamond powder as a raw material is disclosed in, for example, Patent Document 2 below, and, as in the present invention, a sintering aid or catalyst from high-purity graphite under ultrahigh pressure and high temperature. For example, Patent Documents 3 and 4 and Non-Patent Document 2 listed below disclose methods for obtaining a dense and high-purity polycrystalline diamond body that has been converted and sintered without the addition of.
Patent Document 2: Japanese Patent Laid-Open No. 2004-168554 Patent Document 3: Japanese Patent Laid-Open No. 2007-22888 Patent Document 4: Japanese Patent Laid-Open No. 2003-292397 Non-Patent Document 2: SEI Technical Review 165 (2004) 68 (Kakutani et al.)

  Patent Document 2 discloses a method for producing a polycrystalline diamond without using a sintering aid. This polycrystalline diamond is sintered using fine diamond powder as a starting material, and its particle size is also 100 nm or less within the numerical range defined in the present invention. By the way, since the present invention uses a carbon material having a graphite-type layered structure as a starting material, it has a characteristic structure called a lamellar structure that does not exist in the polycrystalline diamond described in Patent Document 2. The non-patent document 2 shows that the progress of cracks is suppressed at the portion of the lamellar structure, which means that the polycrystalline diamond according to the present invention is harder to break than that described in the patent document 2. Is shown. Therefore, the sintered body of the present invention is fundamentally different in structure from the sintered body described in Patent Document 2, and as a result, the mechanical properties are much superior.

In addition, when a dresser is manufactured using diamond obtained by the methods described in Patent Documents 3 and 4 and Non-Patent Document 2, and its workability is examined,
Whether the non-patent document 2 has abnormally grown grains of about 10 times the average particle diameter, or the patent document 3 contains coarse diamonds converted from the added coarse raw materials, It was found that the wear proceeds extremely in the large particle portion. Therefore, in order to obtain a stable target processing, it is necessary to eliminate the extremely worn portion, and for that purpose, it is necessary to control the particle size distribution of the sintered body particle size. It was. Therefore, when a dresser with a controlled particle size distribution was produced, there were no particles that were extremely worn, and it was possible to obtain a stable target processing for a long period of time.
Moreover, because the manufacturing method described in Patent Document 4 is the same manufacturing method as that described in Non-Patent Document 2, there is abnormal grain growth and there is a problem similar to that described in Non-Patent Document 2.

  The above problem is that, as in the present invention, as a dresser material, the average particle diameter is greater than 50 nm and less than 2500 nm, the purity is 99% or more, and the D90 particle diameter of the sintered body particle diameter is (average This can be solved by using a polycrystalline diamond having a particle size of not more than 0.9 × average particle size.

An example of an embodiment of the dresser according to the present invention is shown below.
First, the measurement / evaluation method will be described. <Average particle diameter, D90 particle diameter>
The numerical values of the D50 particle size (average particle size) and D90 particle size of the sintered body in the present invention were obtained by performing image analysis based on a photographed image at a magnification of 100 to 500,000 with a transmission electron microscope. .
The detailed method is shown below.
First, the particle size distribution of the crystal grains constituting the sintered body is measured based on a photographed image taken with a transmission electron microscope. Specifically, individual particles are extracted using image analysis software (for example, ScionImage, manufactured by Scion Corporation), and the extracted particles are binarized to calculate the area (S) of each particle. Then, the particle size (D) of each particle is calculated as the diameter of a circle having the same area (D = 2√ (S / π)).
Next, the particle size distribution obtained above is processed by data analysis software (for example, Origin manufactured by OriginLab, Mathchad manufactured by Parametric Technology, etc.), and D50 (average particle size) and D90 particle size are calculated.
In Examples and Comparative Examples described below, H-9000 manufactured by Hitachi, Ltd. was used as a transmission electron microscope.

<Hardness>
In the examples and comparative examples, the hardness was measured using a Knoop indenter with a measurement load of 4.9N.
<Evaluation of dresser>
The diamond polycrystals obtained in the examples and comparative examples were shaped as follows and used as dressers for evaluation tests.
Specifications: Point type single stone dresser Diamond part size: 1mm x 1mm in cross section
Shape: The tip was processed into a conical shape.
Using the above-mentioned dresser, a WA grindstone was used as the mating material, and the wet grinding was performed under the conditions of a grindstone peripheral speed of 30 m / sec and a cutting depth of 0.05 mm, and the wear amount of the diamond end was evaluated.
In Table 1, the amount of wear was expressed as [amount of wear of example product or comparative product / amount of wear of single crystal product].
The wear amount of the single crystal product was 0.04 mm ³ .

[Example 1]
As a diamond raw material, graphite (graphite) having an average particle size of 100 nm and a D90 particle size of 180 nm or less (average particle size + 0.9 × average particle size) was prepared. Using this as a raw material, it was directly converted and sintered into diamond under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle size of 200 nm and a D90 particle size of 370 nm was obtained. The hardness of the polycrystalline diamond thus obtained was as extremely high as 110 GPa. As a result of producing and evaluating a dresser from the obtained polycrystal, the amount of wear was very small, about 1/50 of that of a single crystal diamond dresser.

[Example 2]
As a diamond raw material, graphite (graphite) having an average particle diameter of 110 nm and a D90 particle diameter of 175 nm which is equal to or less than (average particle diameter + 0.7 × average particle diameter) was prepared. Using this as a raw material, it was directly converted and sintered into diamond under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle size of 230 nm and a D90 particle size of 380 nm was obtained. The hardness of the polycrystalline diamond thus obtained was as extremely high as 115 GPa. As a result of producing and evaluating a dresser from the obtained polycrystal, the amount of wear was very small, about 1/60 of that of a single crystal diamond dresser.

[Example 3]
As a diamond raw material, graphite (graphite) having an average particle size of 95 nm and a D90 particle size of 135 nm or less (average particle size + 0.5 × average particle size) was prepared. Using this as a raw material, it was directly converted and sintered into diamond under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle size of 180 nm and a D90 particle size of 260 nm was obtained. The hardness of the polycrystalline diamond thus obtained was as extremely high as 125 GPa. As a result of producing and evaluating a dresser from the obtained polycrystal, the amount of wear was very small, about 1/70 of that of a single crystal diamond dresser.

[Example 4]
As a diamond raw material, graphite (graphite) having an average particle diameter of 30 nm and a D90 particle diameter of 40 nm or less (average particle diameter + 0.5 × average particle diameter) was prepared. Using this as a raw material, it was directly converted and sintered into diamond under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle size of 55 nm and a D90 particle size of 80 nm was obtained. The hardness of the polycrystalline diamond thus obtained was as extremely high as 105 GPa. As a result of producing and evaluating a dresser with the obtained polycrystal, the amount of wear was very small, which was about 1/40 of a single crystal diamond dresser.

[Example 5]
As a diamond raw material, graphite (graphite) having an average particle diameter of 30 nm and a D90 particle diameter of 40 nm or less (average particle diameter + 0.5 × average particle diameter) was prepared. Using this as a raw material, it was directly converted and sintered into diamond over a longer time than in Example 4 under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle size of 560 nm and a D90 particle size of 830 nm was obtained. The hardness of the polycrystalline diamond thus obtained was as extremely high as 120 GPa. As a result of producing and evaluating a dresser from the obtained polycrystal, the amount of wear was very small, about 1/30 of that of a single crystal diamond dresser.

[Example 6]
As a diamond raw material, graphite (graphite) having an average particle diameter of 30 nm and a D90 particle diameter of 40 nm or less (average particle diameter + 0.5 × average particle diameter) was prepared. Using this as a raw material, it was directly converted and sintered into diamond over a longer time than in Example 5 under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle diameter of 1100 nm and a D90 particle diameter of 1600 nm was obtained. The hardness of the polycrystalline diamond thus obtained was as extremely high as 112 GPa. As a result of producing and evaluating a dresser from the obtained polycrystal, the amount of wear was very small, about 1/30 of that of a single crystal diamond dresser.

[Example 7]
As a diamond raw material, graphite (graphite) having an average particle diameter of 30 nm and a D90 particle diameter of 40 nm or less (average particle diameter + 0.5 × average particle diameter) was prepared. Using this as a raw material, it was directly converted and sintered into diamond over a longer time than Example 6 under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle size of 2400 nm and a D90 particle size of 3500 nm was obtained. The hardness of the polycrystalline diamond thus obtained was as extremely high as 102 GPa. As a result of producing and evaluating a dresser from the obtained polycrystal, the amount of wear was very small, about 1/20 of that of a single crystal diamond dresser.

[Comparative Example 1]
As a raw material of diamond, graphite (graphite) having an average particle diameter of 100 nm and a D90 particle diameter of 210 nm or less (average particle diameter + 1.1 × average particle diameter) was prepared. Using this as a raw material, it was directly converted and sintered into diamond under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle size of 200 nm and a D90 particle size of 400 nm was obtained. The hardness of the polycrystalline diamond thus obtained was as extremely high as 112 GPa. As a result of producing and evaluating a dresser with the obtained polycrystal, it was about 1/3 of the dresser made of single crystal diamond.

[Comparative Example 2]
As a diamond raw material, graphite (graphite) having an average particle diameter of 20 nm and a D90 particle diameter of 37 nm or less (average particle diameter + 0.9 × average particle diameter) was prepared. Using this as a raw material, it was directly converted and sintered into diamond under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle size of 45 nm and a D90 particle size of 80 nm was obtained. The hardness of the polycrystalline diamond thus obtained was 95 GPa and was slightly soft. As a result of producing and evaluating a dresser with the obtained polycrystal, it was about ½ of the dresser made of single crystal diamond.

[Comparative Example 3]
As a diamond raw material, graphite (graphite) having an average particle size of 100 nm and a D90 particle size of 180 nm or less (average particle size + 0.9 × average particle size) was prepared. Using this as a raw material, it was directly converted and sintered into diamond under pressure conditions where diamond was thermodynamically stable. As a result, a polycrystalline diamond having an average particle diameter of 2700 nm and a D90 particle diameter of 3900 nm was obtained. The hardness of the polycrystalline diamond thus obtained was 91 GPa and was slightly soft. As a result of producing and evaluating a dresser from the obtained polycrystal, it was about 1 / 1.5 of the dresser made of single crystal diamond.

Table 1 shows the numerical values of the average particle diameter, the D90 particle diameter, the coefficient (K), the hardness, and the wear life of the sintered particles of the polycrystalline diamond in the above examples and comparative examples. The coefficient (K) is defined by the following equation (1).
D90 particle size = average particle size + average particle size × K (1)

  Polycrystalline diamond used in the present invention can be processed stably for a long period of time without causing uneven wear compared to conventional single crystal diamond or a diamond sintered body containing a metal binder, so it is suitable for dresser applications. Can be used for

Claims (4)

  A diamond polycrystalline body obtained by converting and sintering a carbon material having a graphite-type layered structure under an ultra-high pressure and high temperature without addition of a sintering aid or a catalyst, and comprising the diamond sintered body constituting the diamond polycrystalline body The average particle size of the particles is greater than 50 nm and less than 2500 nm, the purity is 99% or more, and the D90 particle size of the diamond sintered particles is (average particle size + average particle size × 0.9) or less. A dresser comprising a polycrystalline diamond.   The dresser according to claim 1, wherein the diamond sintered particles have a D90 particle size of (average particle size + average particle size × 0.7) or less.   The dresser according to claim 1, wherein the diamond sintered particles have a D90 particle size of (average particle size + average particle size × 0.5) or less.   The dresser according to any one of claims 1 to 3, wherein the polycrystalline diamond has a hardness of 100 GPa or more.