Vitrified bond superabrasive wheel

Abstract

A vitrified bond superabrasive wheel is provided, in which a superabrasive layer of vitrified bond is fixed to a base metal, wherein the superabrasive layer comprises superabrasive grains, vitrified bond, and pores, the average particle size of the superabrasive grains being 0.02 μm or more and 1.0 μm or less, the pores including small pores with a diameter of 0.10 μm or more and less than 10 μm, the average diameter of the small pores being 0.3 μm or more and 3.0 μm or less, the pores including large pores with a diameter of 20 μm or more and 500 μm or less, the average diameter of the large pores being 20 μm or more and 120 μm or less, and the average inter-pore distance of the large pores being 40 μm or more and 300 μm or less.

Description

Technical Field

[0001] The present disclosure relates to a vitrified bond superabrasive wheel. This application claims priority based on Japanese Patent Application No. 2024-113328 filed on July 16, 2024. All the descriptions set forth in the Japanese patent application are incorporated herein by reference.

Background Art

[0002] Conventionally, vitrified bond superabrasive wheels are disclosed in, for example, Patent Document 1: Japanese Patent Application Laid-Open No. 2012-152881, Patent Document 2: Japanese Patent Application Laid-Open No. 2012-200831, Patent Document 3: Japanese Patent Application Laid-Open No. 2010-521326, Patent Document 4: Japanese Patent Application Laid-Open No. 2019-181614, Patent Document 5: Japanese Patent Application Laid-Open No. 2018-510074, and Patent Document 6: Japanese Patent Application Laid-Open No. 2019-59019.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

[0004] A vitrified bond superabrasive wheel according to this disclosure has a superabrasive layer of vitrified bond fixed to a base metal. The superabrasive layer has superabrasive grains, a vitrified bond, and pores. The average particle size of the superabrasive grains is 0.02 μm or more and 1.0 μm or less. The pores include small pores with a diameter of 0.10 μm or more and less than 10 μm. The average diameter of the small pores is 0.3 μm or more and 3.0 μm or less. The pores include large pores with a diameter of 20 μm or more and 500 μm or less. The average diameter of the large pores is 20 μm or more and 120 μm or less. The average interpore distance of the large pores is 40 μm or more and 300 μm or less. [Brief explanation of the drawing]

[0005] [Figure 1] Figure 1 shows a high-magnification image of the microstructure of the superabrasive layer 6. [Figure 2] Figure 2 shows a low-magnification image of the microstructure of the superabrasive layer 6. [Figure 3] Figure 3 is a schematic diagram of a superabrasive wheel 10 having a superabrasive layer 6. [Figure 4] Figure 4 is a Delaunay diagram, represented by a collection of Delaunay triangles, used to measure the distance between the seven air vents. [Figure 5] Figure 5 is a schematic diagram of the superabrasive wheel 20 and table 110 shown to illustrate the grinding method using the superabrasive wheel 20. [Modes for carrying out the invention]

[0006] [Issues this disclosure aims to address] Conventional vitrified bond superabrasive wheels had a problem where good cutting performance resulted in high wear rates, and reducing wear rates resulted in poor cutting performance.

[0007] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described.

[0008] Porous materials tend to aggregate, and if the dispersion of medium-sized and larger pores is poor, localized clogging occurs, resulting in excessive grinding resistance for the abrasive layer as a whole. This is because the wear-resistant superabrasive layer is prone to clogging because it does not self-sharpen easily, but clogging can be resolved by adding medium-sized and larger porosity agents. On the other hand, if the amount of medium-sized and larger porosity agent added is small, clogging can be resolved around the pores, but clogging occurs in areas away from the pores.

[0009] Furthermore, excessive addition of small pores can lead to increased wear. This is because, while a certain level of abrasive layer strength is necessary for processing high-hardness materials such as SiC and sapphire, excessive addition of small pores significantly reduces the abrasive layer strength, leading to increased wear.

[0010] A vitrified bond superabrasive wheel according to this disclosure has a superabrasive layer of vitrified bond fixed to a base metal. The superabrasive layer has superabrasive grains, a vitrified bond, and pores. The average particle size of the superabrasive grains is 0.02 μm or more and 1.0 μm or less. The pores include small pores with a diameter of 0.10 μm or more and less than 10 μm. The average diameter of the small pores is 0.3 μm or more and 3.0 μm or less. The pores include large pores with a diameter of 20 μm or more and 500 μm or less. The average diameter of the large pores is 20 μm or more and 120 μm or less. The average interpore distance of the large pores is 40 μm or more and 300 μm or less.

[0011] With such a vitrified bond superabrasive wheel, the pores formed by air pores ranging from 20 μm to 500 μm or larger are dispersed and have reduced variation, thereby maximizing the chip removal effect. As a result, a consistently sharp abrasive cutting edge acts on the workpiece, enabling highly efficient machining of the workpiece. Generally, if chips are present between the workpiece and the abrasive grains, workpiece removal does not proceed. Consequently, grinding resistance increases and wear increases. The abrasive layer according to this disclosure can solve such problems.

[0012] The grinding surface can be stably processed without clogging to discharge the cut noodles. Furthermore, there is an effect that the abrasive grains can be stably processed without being clogged by the processing heat due to the cooling of the processing heat by the coolant holding.

[0013] If the average value of the pore distance is large and the variation in the pore distribution is large, the desired effect cannot be obtained and stable processing cannot be performed. If the average value of the pore distance is small, sufficient strength cannot be provided as a chip and the desired effect cannot be obtained.

[0014] Also, the shape of the pores is preferably spherical in order to uniformly disperse the pores and suppress the variation in the pore distance.

[0015] The small pores form irregularities on the grinding surface and have the effect of enabling stable processing without clogging.

[0016] Preferably, the standard deviation of the pore distance of the large pores is 1 / 2 or less of the average value of the pore distance of the large pores.

[0017] The standard deviation σ of the pore distance of the large pores is obtained by the following formula. σ = [(1 / n){(W1 - A) 2 +(W2 - A) 2 +...+(Wn - A) 2}] 1 / 2 Here, let the pore distances of n large pores be W1, W2...Wn.

[0018] Let the average value of the distances between n large pores be A. A is obtained by the following formula. A = (1 / n)(W1 + W2 +...Wn) By making the standard deviation of the pore distance of the large pores half or less of the average value, the dispersibility of the large pores is increased and the desired effect is more easily obtained.

[0019] Preferably, the average value of the diameters of the small pores is 1.0 μm or more and 2.0 μm or less. Preferably, the proportion of the small pores in the superabrasive layer is 5.0% by volume or more and 40.0% by volume or less.

[0020] Preferably, the air vents are spherical, and the ratio of the short axis a to the long axis b of the air vent (a / b) is 0.5 or more and 1.0 or less. The spherical shape of the air vents suppresses variations in the distance between vents, thereby achieving the desired effect. To make the vents spherical, a spherical resin-based pore-forming material is used and the vents are formed by burning them off during the firing process.

[0021] Preferably, the proportion of the air pores in the superabrasive layer is 5.0% by volume or more and 50.0% by volume or less. If the air pores are within this range, it is easy to form consistent interpore distances at low cost.

[0022] Preferably, the superabrasive layer contains a filler, the filler contains at least one selected from the group consisting of silicon carbide, hBN, and alumina, and the filler content in the superabrasive layer is 2% by volume or more and 40% by volume or less. By adding the filler, the concentration of superabrasive grains in the superabrasive layer can be adjusted. Preferably, a low concentration can be achieved. This makes it possible to achieve low grinding resistance.

[0023] Preferably, the softening temperature of the vitrified bond is between 600°C and 900°C. For vitrified bonds with high self-sharpening properties, a lower softening point temperature is desirable. Preferably, the softening point temperature is between 600°C and 700°C. The softening point of the vitrified bond can be measured, for example, by the glass softening point measurement method specified in JIS R3101-1 (2001).

[0024] Preferably, the vitrified bond superabrasive wheel is used for processing compound semiconductor wafers of SiC, GaN, LiTaO3 (lithium tantalate), or LiNbO3 (lithium niobate).

[0025] Figure 1 shows a high-magnification image of the structure of the superabrasive layer. The vitrified bond superabrasive wheel of this disclosure has a bond called the abrasive layer, in which small pores on the order of several microns are provided as shown in Figure 1. The superabrasive layer 6 has a vitrified bond 2, superabrasive grains 3 and filler 4 held by the vitrified bond 2, and small pores 5 surrounded by the vitrified bond 2, superabrasive grains 3 and filler 4. The superabrasive layer 6 can grind a workpiece 11 made of, for example, SiC.

[0026] Vitrified bond 2 has, for example, the following composition: SiO2: 30-60% by mass, Al2O3: 2-15% by mass, B2O3: 15-40% by mass, RO (RO is one or more oxides selected from CaO, MgO, and BaO): 1-10% by mass, R2O (R2O is one or more oxides selected from Li2O, Na2O, and K2O): 5-15% by mass, ZrO2: 0-8% by mass, Others: 0-5% by mass.

[0027] The superabrasive grain 3 is composed of, for example, diamond, CBN, or a mixture thereof. Filler 4 is an additive used to reduce the concentration of superabrasive grains 3.

[0028] When the superabrasive grains 3 of the superabrasive layer 6 grind the workpiece 11, chips 12 are generated and adhere to the surface of the superabrasive layer 6.

[0029] Figure 2 shows a high-magnification image of the superabrasive structure of the vitrified bond. As shown in Figure 2, the superabrasive layer 6 has air pores 7 on the order of tens to hundreds of microns. Due to the uniform dispersion of multiple air pores 7, the average distance between air pores 7 is distributed within the range of 100 μm to 300 μm. Furthermore, due to the uniform dispersion, the standard deviation of these pores is kept below half of the average value.

[0030] Figure 3 is a schematic diagram of a superabrasive wheel 10 having a superabrasive layer 6 and a workpiece 11. As shown in Figure 3, in the superabrasive wheel 10, multiple segmented superabrasive layers 6 are fixed to a base metal 9. An adhesive layer may be provided between the superabrasive layer 6 and the base metal 9. The superabrasive wheel 10 is a so-called grinding wheel, and the superabrasive layer 6 is provided on either the axial or radial surface. That is, the superabrasive wheel 10 may be either a surface grinding wheel or a cylindrical grinding wheel.

[0031] This disclosure relates to a wheel used, for example, for precision grinding of SiC wafers, wherein the average particle size of the superabrasive grains 3, which are made of diamond, is in the range of 0.02 μm to 1.00 μm.

[0032] (Manufacturing method) A method for manufacturing such a superabrasive wheel 10 will be described.

[0033] (Step 1) First, superabrasive grains 3 made of diamond, vitrified bond 2 which is a glass binder, filler 4, pore-forming material with an average particle size of Φ0.3 to 3.0 μm, and binder are blended in various compositions and wet-mixed to obtain the first mixture. At this time, the mixture is mixed at a constant rotation speed (15-400 rpm) for 120 hours to ensure that these raw materials are uniformly mixed. The first mixture is dried and pulverized to obtain a pulverized product. At this time, the pulverized product is pulverized at a constant rotation speed (15-400 rpm) for 48 hours or more so that the average particle size of the pulverized product is 50 μm or less.

[0034] (Step 2) Next, in a separate container, porosity-forming materials with average particle sizes ranging from Φ30 μm to 300 μm are blended in various compositions and mixed at a constant rotation speed (15-400 rpm) for 60 hours to obtain a second mixture of homogeneous porosity-forming materials. To homogeneously mix the pulverized material and the second mixture, they are mixed at a constant rotation speed (15-400 rpm) for 120 hours to obtain a third mixture.

[0035] The third mixture is molded into chips of a certain size by pressure molding, and the chips are fired to burn off the pore-forming material and binder, thereby producing a superabrasive layer 6 as a fired chip composed of superabrasive grains 3, vitrified bond 2, filler 4, small pores 5 and air pores 7. The fired chips are bonded to a metal body base 9, and the chips are ground to a predetermined size to produce a vitrified bond superabrasive wheel 10.

[0036] The pore-forming material used is a spherical resin, and since the traces left by the pore-forming material during firing are retained, spherical pores generally remain in the vitrified bond 2 after firing.

[0037] [Details of the embodiments of this disclosure] (Manufacturing of vitrified bonds for sample numbers 1 to 17)

[0038] [Table 1]

[0039] Vitrified bond superabrasive wheels for samples 2 to 5, 9 to 13, and 15 to 17 were manufactured according to the "(Manufacturing Method)" described above. Furthermore, vitrified bond superabrasive wheels for samples 1, 6, 7, 8, and 14 were manufactured using a method different from the "(Manufacturing Method)" described above. In the manufacturing method for sample 1, a porosity-forming material with an average particle diameter of Φ0.2 μm was used in step 1. In the manufacturing method for sample 6, a porosity-forming material with an average particle diameter of Φ3.5 μm was used in step 1. In the manufacturing method for sample 7, a porosity-forming material with an average particle diameter of Φ12 μm was used in step 1.

[0040] In the manufacturing method for sample number 8, a porosity-forming material with an average particle size of Φ20 μm was used in step 2. In the manufacturing method for sample number 14, a porosity-forming material with an average particle size of Φ180 μm was used in step 2. For all samples, the composition of the vitrified bond was as follows.

[0041] SiO2: 30-60% by mass, Al2O3: 2-15% by mass, B2O3: 15-40% by mass, RO (RO is one or more oxides selected from CaO, MgO, and BaO): 1-10% by mass, R2O (R2O is one or more oxides selected from Li2O, Na2O, and K2O): 5-15% by mass, ZrO2: 0-8% by mass, Others: 0-5% by mass.

[0042] (Method for measuring the average particle size of superabrasive grains 3) To measure the average particle size of the superabrasive grains 3 contained in a vitrified bond superabrasive wheel, the superabrasive layer 6 was dissolved with an acid or the like to extract the superabrasive grains 3. If the superabrasive wheel is large, the superabrasive layer 6 is dissolved in a predetermined volume (for example, 0.5 cm³). 3 Only the superabrasive layer 6 was cut out, and this cut-out superabrasive layer 6 was dissolved with acid or the like to extract the superabrasive grains. The average particle size was then measured using a laser diffraction particle size distribution analyzer (for example, the SALD series manufactured by Shimadzu Corporation). The average particle size in this case refers to the D50 value.

[0043] (Method for measuring the diameter of small pores 5) The diameter of the small pores 5 was measured in the following manner. The superabrasive layer 6 was cut with a diamond cutter, and the cut surface was polished by ion milling (for example, JEOL CROSSSECTION POLISHER IB-19530). Then, three or more images were taken using FE-SEM (for example, JEOL JSM-IT800 with a lens magnification of ×5000).

[0044] In the images, pores 5 appear as a dark gray or out of focus. Using image analysis software (e.g., WinROOF from Mitani Corporation), the observer measures the length of these images to determine their major axis. Areas with a major axis between 0.1 μm and 10 μm were defined as pores 5, and more than 100 pores 5 were extracted. The major axis of the extracted pores 5 was defined as the diameter, and the diameter of each pore 5 was measured.

[0045] (Measurement of the diameter of air vent 7) The air pores 7 within the abrasive layer were extracted by image analysis using the following image analysis software. Three images were taken from three different locations using a stereomicroscope (for example, a KEYENCE VHX7000 with a lens magnification of ×50) (without any overlapping parts of the images). More specifically, the original images were converted to grayscale and the boundaries were extracted. More than 300 regions corresponding to pores were extracted by image binarization. These regions were filtered by aspect ratio (minimum diameter / maximum diameter) between 0.5 and 1.0, and air pores 7 were defined as those with a minimum circumscribed circle between 20 μm and 500 μm in diameter within the region with an aspect ratio between 0.5 and 1.0. The lower limit of the diameter of these air pores, 20 μm, was set because the lower limit of the recognizable diameter in the images taken here is around 20 μm.

[0046] The original pore-forming material was spherical and included in the aspect ratio mentioned above. Since the spherical shape remained after molding, only a very small amount was excluded by aspect ratio filtering.

[0047] (Calculation of the volume ratio of air vent 7) In the above "(Measurement of the diameter of air vent 7)," the total area of ​​the captured images was taken as S1, and the total area of ​​the measured air vents was taken as S2. The average value of S2 / S1 calculated for each of the three images was taken as the volume ratio of air vent 7.

[0048] (Calculation of the volume ratio of small pore 5) In the above "(Measurement of the diameter of pore 5)", the total area of ​​the captured images was taken as S3, and the total area of ​​the measured pores was taken as S4. The average value of S4 / S3 calculated for each of the three or more images was taken as the volume ratio of pore 5.

[0049] (Measurement of stomatal distance) The distance between air vents 7 was defined by the distance between the centroids of the air vents 7. The centroid of an air vent 7 was the center of its least circumscribed circle.

[0050] The distance between the centroids of stomatal vents was measured by calculating the distance between the centroids of the vents extracted above using a Delaunay diagram. In other words, the measurement surface containing multiple vents was represented by a collection of Delaunay triangles.

[0051] Figure 4 is a Delaunay diagram, represented by a collection of Delaunay triangles, used to measure the distance between air vents 7. The centroids 7G of multiple air vents 7 are connected by straight lines 7A. This forms multiple Delaunay triangles 7T. Each of these straight lines 7A represents the distance between the air vents 7.

[0052] To measure the distance between air pores 7, air pores 7 exposed on the surface of the superabrasive layer 6 were extracted. At least 300 or more air pores 7 were extracted.

[0053] As a precaution during photography, the surface of the chip with the superabrasive layer 6 after firing was roughly polished with #400 abrasive paper. Then, the chip surface was further polished with #1200 abrasive paper, and three surface photographs were taken using a KEYENCE VHX7000 with a lens magnification of x50, ensuring that the field of view did not overlap.

[0054] (Image analysis software and commands to be used) For the measurement of the diameter of atmospheric vents and the distance between stomatal holes described above, the commands shown in Table 2, created for this analysis using MultiImageTool, a multi-purpose image processing tool manufactured by System Infrontia Co., Ltd., were used to perform image analysis and calculate the diameter of atmospheric vents and the distance between stomatal holes.

[0055] [Table 2]

[0056] (Measurement of the volume percentage of filler 4) The volume ratio of filler 4 was measured using the following procedure. The superabrasive layer 6 was cut with a diamond cutter, and the cut surface was polished by ion milling (e.g., JEOL CROSSSECTION POLISHER IB-19530). Then, three or more images were taken using FE-SEM (e.g., JEOL JSM-IT800 with lens magnification ×5000). In the images, filler 4 appeared as a light gray color. Using image analysis software (e.g., WinROOF from Mitani Corporation), the observer extracted the light gray areas from these images and measured their area. The volume ratio of filler 4 was calculated as the average of S6 / S5, where S5 was the area of ​​the image taken and S6 was the area of ​​the measured filler 4, for each of the three or more images.

[0057] (Processing test) Multiple superabrasive wheels 10 with a diameter D of 250 mm were fabricated, as shown in Figure 3. Each superabrasive wheel has a superabrasive layer 6 corresponding to sample numbers 1-13. These superabrasive wheels 10 were mounted on a Tokyo Seimitsu HRG200X high-rigidity grinding machine and used to process the thickness of 10 single-crystal 6-inch SiC wafers.

[0058] Figure 5 is a schematic diagram of the superabrasive wheel 10 and table 110 shown to illustrate a grinding method using the superabrasive wheel 10. In the grinding method 100, a workpiece 11, which is a SiC wafer, is fixed on the table 110. Here, the table 110 is rotatable in the direction indicated by arrow 110R. The superabrasive wheel 10 is rotatable in the direction indicated by arrow 1R. Furthermore, the direction indicated by arrow 1F is the cutting direction.

[0059] Machining conditions: Spindle rotation speed 1250 min⁻¹ -1 Work rotation speed 300 min -1The feed rate was set to 0.3 μm / sec, the material removal amount to 10 μm, and the spark-out time to 10 sec. During the grinding process, the wear rate (change in height of the superabrasive layer 6 before and after grinding / change in thickness of the workpiece (wafer) in the ground portion before and after grinding) × 100), the load current value for rotating the superabrasive wheel 10, and the normal resistance in the direction indicated by arrow 11F in Figure 5 were measured. These results are shown in Table 3.

[0060] [Table 3]

[0061] The processing results in Table 3 are the average of 10 samples. Table 3 shows that, considering the grinding efficiency and grinding quality required in the actual market, a good product was defined as one that met all the performance requirements: wear rate of 200% or less, load current value of 4A or less, and normal resistance of 30kgf or less. Samples 2 to 5, 9 to 13, and 15 to 17 were found to have a wear rate of 200% or less, a load current value of 4A or less, and a normal resistance of 30kgf or less. Samples 1, 6, 7, 8, and 14 were found to have a high or low wear rate, load current value, or normal resistance.

[0062] From these results, it was found that the average diameter of small pores needs to be between 0.3 μm and 3 μm. The average diameter of atmospheric vents needs to be between 20 μm and 120 μm. The average distance between atmospheric vents needs to be between 40 μm and 300 μm. (Note 1) A vitrified bond superabrasive wheel in which a vitrified bond superabrasive layer is fixed to a base metal, The superabrasive layer has superabrasive grains, a vitrified bond, and pores. The average particle size of the superabrasive grains is 0.02 μm or more and 1.0 μm or less. The pores include small pores with a diameter of 0.10 μm or more and less than 10 μm. The average diameter of the aforementioned small pores is between 0.3 μm and 3.0 μm. The aforementioned pores include air pores with a diameter of 20 μm or more and 500 μm or less. The average diameter of the aforementioned air vents is between 20 μm and 120 μm. A vitrified bond superabrasive wheel in which the average interporeal distance of the aforementioned air pores is 40 μm or more and 300 μm or less. (Note 2) The vitrified bond superabrasive wheel as described in Appendix 1, wherein the standard deviation of the inter-pore distance of the air vents is 1 / 2 or less of the average value of the inter-pore distance of the air vents. (Note 3) The vitrified bond superabrasive wheel described in Appendix 1 or 2, wherein the average diameter of the small pores is 1.0 μm or more and 2.0 μm or less. (Note 4) A vitrified bond superabrasive wheel according to any one of the appendices 1 to 3, wherein the air vent is spherical, and the ratio of the short axis a to the long axis b of the air vent (a / b) is 0.5 or more and 1.0 or less. (Note 5) A vitrified bond superabrasive wheel according to any one of the appendices 1 to 4, wherein the proportion of the air pores in the superabrasive layer is 15% by volume or more and 50% by volume or less. (Note 6) The vitrified bond superabrasive wheel according to any one of Appendix 1 to 5, wherein the superabrasive layer contains a filler, the filler contains at least one selected from the group consisting of silicon carbide, hBN, and alumina, and the filler content in the superabrasive layer is 2% by volume or more and 40% by volume or less. (Note 7) The vitrified bond superabrasive wheel according to any one of the appendices 1 to 6, wherein the softening temperature of the vitrified bond is 600°C or higher and 900°C or lower. (Note 8) A vitrified bond superabrasive wheel as described in any one of Appendix 1 to 7, for processing compound semiconductor wafers of SiC, GaN, LiTaO3 (lithium tantalate), or LiNbO3 (lithium niobate).

[0063] The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the embodiments described above, and all modifications within the scope of the claims are intended to be included in the meaning of equivalents and within the scope. [Explanation of Symbols]

[0064] 2 Vitrified bond, 3 Superabrasive grains, 4 Filler, 5 Small pores, 6 Superabrasive grain layer, 7 Air pores, 7A Straight line, 7G Center of gravity, 7T Delaunay triangle, 9 Base metal, 10 Superabrasive wheel, 11 Workpiece (SiC wafer), 12 Chips, 100 Grinding method, 110 Table.

Claims

1. A vitrified bond superabrasive wheel in which a vitrified bond superabrasive layer is fixed to a base metal, When a region with a major axis of 0.1 μm or more and 10 μm or less is defined as a small pore, and within a region with an aspect ratio of 0.5 or more and 1.0 or less, a small pore has a minimum circumscribed circle with a diameter of 20 μm or more and 500 μm or less, and the distance between such pores is defined by the distance between the centroids of the pores, and the centroid of the pore is the center of its minimum circumscribed circle, The superabrasive layer has superabrasive grains, a vitrified bond, and pores. The average particle size of the superabrasive grains is 0.02 μm or more and 1.0 μm or less. The pores include the small pores with a diameter of 0.10 μm or more and less than 10 μm. The average diameter of the aforementioned small pores is 0.3 μm or more and 3.0 μm or less. The aforementioned pores include air pores with a diameter of 20 μm or more and 500 μm or less. The average diameter of the aforementioned air vents is between 20 μm and 120 μm. A vitrified bond superabrasive wheel in which the average interporeal distance of the aforementioned air pores is 40 μm or more and 300 μm or less.

2. The vitrified bond superabrasive wheel according to claim 1, wherein the standard deviation of the inter-pore distance of the air vents is 1 / 2 or less of the average value of the inter-pore distance of the air vents.

3. The vitrified bond superabrasive wheel according to claim 1 or 2, wherein the average diameter of the small pores is 1.0 μm or more and 2.0 μm or less.

4. The vitrified bond superabrasive wheel according to claim 1 or 2, wherein the proportion of the small pores in the superabrasive layer is 5.0 volume% or more and 40.0 volume% or less.

5. The vitrified bond superabrasive wheel according to claim 1 or 2, wherein the air pores are spherical, and the ratio of the short diameter a to the long diameter b of the air pores (a / b) is 0.5 or more and 1.0 or less.

6. The vitrified bond superabrasive wheel according to claim 1 or 2, wherein the proportion of the air pores in the superabrasive layer is 5.0 volume% or more and 40.0 volume% or less.

7. The vitrified bond superabrasive wheel according to claim 1 or 2, wherein the superabrasive layer contains a filler, the filler contains at least one selected from the group consisting of silicon carbide, hBN, and alumina, and the filler content in the superabrasive layer is 2% by volume or more and 40% by volume or less.

8. The vitrified bond superabrasive wheel according to claim 1 or 2, wherein the softening temperature of the vitrified bond is 600°C or higher and 900°C or lower.

9. SiC, GaN, LiTaO ３ (Lithium tantalate), or LiNbO ３ A vitrified bond superabrasive wheel according to claim 1 or 2, for processing compound semiconductor wafers of (lithium niobate).

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