Medium and method for manufacturing the same

Abstract

To provide a medium and a method for manufacturing the same.SOLUTION: There is provided a medium for crushing and / or dispersion using a bead mill, wherein an abrasion rate W2 / W1 of a second abrasion rate W2 of the medium measured when the medium is put in a crushing chamber of a bead mill so as to satisfy the following condition 1, water is circulated in the crushing chamber so as to satisfy the following condition 2, and an agitation rotor is rotated at a second rotation rate with peripheral viscosity of 10 m / sec for 6 hours in the crushing chamber, to a first abrasion rate W1 of the medium when the agitation rotor is rotated at a first rotation rate with peripheral viscosity of 8 m / sec for 6 hours in the crushing chamber is 1.7 or less. Condition 1: Filling amount of the medium is 70 to 85 vol.% of an effective volume of the crushing chamber. Condition 2: Flow rate circulated to the bead mill is 150 to 190 mL / min.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a medium and a manufacturing method thereof. [Background technology]

[0002] Electronic components such as ceramic multilayer capacitors are becoming smaller and more functional. The production of powders used as raw materials requires finer powdering, higher dispersion, and higher purity. To obtain powders that meet these requirements, bead mills using finer media are used for grinding and dispersion. Bead mills grind and disperse the powders to be processed by stirring the micro-media at high speed in the grinding chamber. For this reason, the load on the media used is large, and for example, Y2O3-reinforced zirconia-based micro-media, which has excellent impact resistance and abrasion resistance, are used.

[0003] The micro-media used in bead mills are small in size, so they need to be put in large quantities into the grinding chamber of a bead mill or the like. The micro-media put into a bead mill may experience shedding of crystal particles over a long period of use, or cracks caused by repeated impacts may slowly extend, leading to rapid acceleration of wear and cracking at some point. If the wear rate of the media increases, fine wear powder may get mixed into the workpiece, causing a decrease in the purity of the workpiece. If the media cracks, this leads to the mixing of relatively large foreign matter into the workpiece, which affects the production of high-performance workpieces. Evaluation of the stability of micro media, such as damage that occurs with long-term use, cannot be inferred from the density or crushing load value measured at the time of manufacturing the micro media.

[0004] For example, Patent Document 1 discloses partially stabilized ZrO2 spheres used as a grinding and / or dispersion medium for a ball mill. The partially stabilized ZrO2 spheres disclosed in Patent Document 1 contain a stabilizer and a small amount of Al2O3, and have a specific range of bulk density relative to theoretical density, and a specific range of average crystal grain size and a specific ratio of the average crystal grain size in the region from the surface to 1 / 3 of the radius to the region from the center of the sphere to 2 / 3 of the radius. Patent Document 1 describes that a sphere is placed in a ball mill, water maintained at 20 to 30°C is circulated, and the disk is moved at a constant peripheral speed to rub for 40 hours, and the wear resistance rate is measured from the weight before and after the test. However, for example, when the diameter of the sphere is a small sphere of 0.5 mm or less, even if a stirring member such as a disk is moved at a constant peripheral speed, the load applied to the sphere does not change, so that the stability such as the wear resistance of the sphere may not be evaluated.

[0005] For example, Patent Document 2 discloses a ZrO2-Y2O3-based zirconia sintered body that can be used as a grinding and dispersion medium. The ZrO2-Y2O3-based zirconia sintered body disclosed in Patent Document 2 has a specific composition, a specific range of relative density, and a specific range of average crystal grain size. Patent Document 2 describes that a medium as an evaluation sample was placed in a Dyno Mill, a slurry containing a workpiece was circulated at a specific flow rate, and a stirring member such as a disk was moved at a constant peripheral speed, and the operation was performed five times, with one operation being 24 hours, and the wear rate of the media per hour was measured. However, when the media is a small media with a diameter of 0.5 mm or less, the load applied to the media does not change even if a stirring member such as a disk is moved at a constant peripheral speed, so that the stability of the media may not be evaluated. In addition, when a slurry containing a workpiece is circulated, the stability of the media may change depending on the workpiece, and the stability of the media, such as wear resistance, may not be evaluated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-315246 A [Patent Document 2] JP 2014-205586 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a medium that is evaluated for its stable wear resistance and a method for manufacturing the medium. [Means for solving the problem]

[0008] A first aspect of the present invention is a media, in which a bead mill is used, grinding and / or dispersion media is placed in the grinding chamber of the bead mill so as to satisfy condition 1 below, water is circulated through the grinding chamber so as to satisfy condition 2 below, and an agitator rotor in the grinding chamber is rotated, and a wear ratio W2 / W1 of a first wear rate W1 of the media measured by rotating the agitator rotor for 6 hours at a first rotation speed having a peripheral speed of 8 m / sec and a second wear rate W2 of the media measured by rotating the agitator rotor for 6 hours at a second rotation speed having a peripheral speed of 10 m / sec is 1.7 or less. Condition 1: The amount of media filled is 70-85% of the effective volume of the grinding chamber. Condition 2: Flow rate circulated through the bead mill is 150-190 mL / min

[0009] A second aspect of the present invention is a method for producing media, comprising: using a bead mill, placing grinding and / or dispersion media in a grinding chamber of the bead mill so as to satisfy condition 1 below; circulating water through the grinding chamber so as to satisfy condition 2 below, rotating an agitator rotor in the grinding chamber at a first rotation speed having a peripheral speed of 8 m / sec for 6 hours, and measuring a first wear rate W1 of the media; circulating water through the grinding chamber so as to satisfy condition 2 below, rotating the agitator rotor in the grinding chamber at a second rotation speed having a peripheral speed of 10 m / sec that is faster than the first rotation speed for 6 hours, and measuring a second wear rate W2 of the media; determining a wear ratio W2 / W1 of the second wear rate W2 to the first wear rate W1; and obtaining media having a wear ratio W2 / W1 of 1.7 or less. Condition 1: The amount of media filled is 70-85% of the effective volume of the grinding chamber. Condition 2: Flow rate circulated through the bead mill is 150-190 mL / min Effect of the Invention

[0010] The present invention can provide a medium that is evaluated for its stable wear resistance and a method for manufacturing the medium. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, the present invention will be described based on an embodiment, however, the present invention is not limited to the embodiment described below.

[0012] A method for evaluating media includes using a bead mill and placing grinding and / or dispersion media in a grinding chamber of the bead mill so as to satisfy condition 1 below; circulating water through the grinding chamber so as to satisfy condition 2 below, rotating an agitator rotor in the grinding chamber at a first rotation speed for six hours, and measuring a first wear rate W1 of the media; circulating water through the grinding chamber so as to satisfy condition 2 below, rotating the agitator rotor in the grinding chamber at a second rotation speed faster than the first rotation speed for six hours, and measuring a second wear rate W2 of the media; and deriving a wear ratio W2 / W1 of the second wear rate W2 to the first wear rate W1. Condition 1: The amount of media filled is 70-85% of the effective volume of the grinding chamber. Condition 2: Flow rate circulated through the bead mill is 150-190 mL / min

[0013] Grinding and / or dispersion media rapidly wear out when used for a long period of time due to defects contained in the media and non-uniformity of the microstructure. For such media with non-uniformity inside, even if there is no difference in the amount of wear of the media at a low rotation speed of a media stirring type mill such as a bead mill, when processed at a higher rotation speed, a high load is applied to the non-uniform structure inside the media, the amount of wear increases significantly, and the difference in the amount of wear between low and high rotation speeds becomes large. The stability of such media cannot be evaluated from basic properties such as the density and hardness of the media. In the media evaluation method, when the stirring rotor is rotated at a first rotation speed, a smaller load is applied to the media compared to when the stirring rotor is rotated at a second rotation speed. When the stirring rotor is rotated at a second rotation speed faster than the first rotation speed, a larger load is applied to the media than at the first rotation speed. In the media evaluation method, the first wear rate W1 of the media when the agitation rotor is rotated at a first rotation speed and a small load is applied to the media, and the second wear rate W2 of the media when the agitation rotor is rotated at a second rotation speed faster than the first rotation speed and a large load is applied to the media are measured, and the wear ratio W2 / W1 of the second wear rate W2 to the first wear rate W1 is measured, so that the stable wear resistance of the media can be evaluated. The second wear rate W2 when a large load is applied to the media tends to be larger than the first wear rate W1 when a small load is applied to the media, and a value of the wear ratio W2 / W1 closer to 1.0 indicates a small difference in the wear rate between when a large load is applied to the media and when a small load is applied to the media, and indicates stable wear resistance. It can be confirmed that media with a wear ratio W2 / W1 of 1.7 or less derived by the media evaluation method has a small difference in the wear rate between when a small load is applied to the media for a long time and when a large load is applied to the media for a long time, and indicates stable wear resistance. The media for measuring the first wear rate W1 and the media for measuring the second wear rate W2 may be the same media, or different media of the same type may be used.When the media for measuring the first wear rate W1 and the media for measuring the second wear rate W2 are the same media, the second wear rate W2 may be measured after the first wear rate W1, or the first wear rate W1 may be measured after the second wear rate W2, and the measurement order is not affected by the wear rate measurements.

[0014] When evaluating the wear ratio W2 / W1 of the media, water is passed through the bead mill together with the media, and the wear resistance can be evaluated without being affected by the type of material to be pulverized and / or dispersed. The water may be deionized water.

[0015] Condition 1 in the evaluation method of the media is that the filling amount of the media is 70 to 85 volume % when the effective volume of the grinding chamber of the bead mill is 100 volume %. The effective volume of the grinding chamber of the bead mill refers to the volume obtained by subtracting the volume of the components that are pre-arranged in the grinding chamber, such as the stirring rotor, which is the stirring member present in the grinding chamber, from the volume of the grinding chamber, with the space in the bead mill being the grinding chamber (vessel). The effective volume of the grinding chamber may be expressed as the capacity of the grinding chamber, for example, in a catalog or the like. The effective volume or capacity of the grinding chamber of the bead mill may be the catalog value of the bead mill. When the filling amount of the media is 70 to 85 volume % of the effective volume of the grinding chamber, the media is uniformly stirred in the grinding chamber of the bead mill, and the measurement accuracy of the wear rate and wear ratio when rotating at different rotation speeds of the first rotation speed or the second rotation speed can be improved. If the amount of media filled is less than 70% by volume of the effective volume of the grinding chamber, the media in the grinding chamber will not move smoothly due to the small amount of filling, and the wear of the media will not progress. Even if the wear ratio W2 / W1 between the first wear rate W1 and the second wear rate is 1.7 or less, the third wear rate that can be measured by rotating at the first rotation speed for 100 hours while satisfying conditions 1 and 2 may exceed 50 mass ppm / hour, and it may be difficult to measure the wear rate and wear ratio accurately when considering actual use. If the amount of media filled is more than 85% by volume of the effective volume of the grinding chamber, the amount of filling is too large, and the media may become biased in the grinding chamber, and wear may not progress uniformly. Even if the wear ratio W2 / W1 between the first wear rate W1 and the second wear rate W2 is 1.7 or less, the third wear rate that can be measured by rotating at the first rotation speed for 100 hours while satisfying conditions 1 and 2 described below may exceed 50 mass ppm / hour, and it may be difficult to measure the wear rate and wear ratio accurately when considering actual use.

[0016] Condition 2 in the media evaluation method is that the flow rate of water circulated through the bead mill is 150 to 190 mL / min. If the flow rate of water circulated through the bead mill is within the range of 150 to 190 mL, the stable wear resistance of the media can be confirmed by comparing the first wear rate W1 of the media when the stirring rotor is rotated at the first rotation speed and the second wear rate W2 of the media when the stirring rotor is rotated at the second rotation speed. If the flow rate of water circulated through the bead mill is less than 150 mL / min, the wear of the media may be uneven and the wear may not progress uniformly. If the flow rate of water circulated through the bead mill exceeds 190 mL / min, the media may float in the grinding chamber of the bead mill, the momentum of the media may decrease, and the wear of the media may be uneven and the wear may not progress uniformly.

[0017] In the method for evaluating media, the amount of water circulated to the bead mill is not particularly limited. The amount of water may be about twice the effective volume of the grinding chamber of the bead mill, or about 10 times the effective volume of the grinding chamber. As described later, when measuring the wear rate by element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in water, if the amount of water circulated is too large, the concentration of element M present in the water decreases, so in order to accurately measure the amount of element M, it is preferable that the amount of water circulated to the bead mill is 4 to 5 times the effective volume of the grinding chamber. In the method for evaluating media, condition 3 may be condition 3: water circulated in a volume 4 to 5 times the effective volume of the grinding chamber.

[0018] In the media evaluation method, the stirring rotor is rotated for 6 hours. In the media evaluation method, if the stirring rotor is rotated for 6 hours to measure the wear rate of the media, a difference is likely to be created between the first wear rate W1 when a relatively light load is applied to the media and the second wear rate W2 when a relatively heavy load is applied to the media, and the stable wear resistance of the media can be confirmed. When the material to be processed is pulverized and / or dispersed using a bead mill and media, the processing may be performed for less than 6 hours or for more than 6 hours.

[0019] In the method for evaluating the media, the first rotation speed for rotating the stirring rotor of the bead mill is 8 m / sec, and the second rotation speed is 10 m / sec. If the first rotation speed for applying a relatively small load to the media in the bead mill is 8 m / sec, and the second rotation speed for applying a relatively large load to the media is 10 m / sec, it is possible to compare the wear rates when a small load is applied and when a large load is applied, and it is possible to perform a stable evaluation of the wear resistance of the media.

[0020] In a bead mill, the material to be treated is dispersed in a liquid medium and flows into a grinding chamber, where a dispersion rotor is used to agitate and / or disperse the material to be treated and the media together with the media, thereby grinding and / or dispersing the material to be treated.

[0021] Examples of the media agitation type mill include a bead mill and a ball mill. The bead mill includes a grinding chamber and an agitation member. The bead mill preferably includes a grinding chamber having an effective volume or capacity of, for example, 100 mL to 600 mL. The effective volume or capacity of the grinding chamber is more preferably 120 mL to 550 mL. The grinding chamber includes an inlet and an outlet for inserting the material to be processed and / or liquid. When a liquid is used together with the media, it is preferable that the grinding chamber has a function for circulating the liquid. The media is preferably agitated together with the liquid in the grinding chamber using an agitation member. The material to be processed is preferably placed in the grinding chamber together with the media and the liquid and ground and / or dispersed. When a liquid is used together with the media, a separator may be provided to prevent the media from flowing out of the grinding chamber. The grinding chamber may be provided with a function for adjusting the temperature by heating or cooling. The agitation member provided in the media agitation type mill is preferably capable of being driven by a motor or the like. As the agitation member, it is preferable to use an agitation rotor. The stirring rotor may be a disk stirring rotor having a plurality of disks on a rotating shaft, or a pin-type stirring rotor having a plurality of pins on a rotating shaft. The pin-type stirring rotor may be arranged such that the pins are alternately arranged on the rotating shaft so as to be perpendicular to each other.

[0022] The grinding chamber of the bead mill is preferably a vertical grinding chamber. In the bead mill, a vertical grinding chamber refers to a grinding chamber whose vertical length is longer than its horizontal length. The grinding chamber of the bead mill may be a horizontal grinding chamber whose horizontal length is longer than its vertical length, but a bead mill equipped with a vertical grinding chamber is more likely to apply a load to the media, and the wear ratio W2 / W1 between the first wear rate W1 at the first rotation speed and the second wear rate W2 at the second rotation speed is more likely to be large, making it suitable for evaluating the stable wear resistance of the media.

[0023] The grinding chamber of the bead mill is preferably made of at least one material selected from the group consisting of an alumina-zirconia composite material, a zirconia material, a silicon nitride material, and a urethane resin. Specifically, it is preferable to use a material different from that of the media used for the grinding chamber and the members. By using a material different from that of the media, the components that are abrasively mixed into the water from the grinding chamber material are different from the media components, so that, as described below, when measuring the wear rate based on element M, which is the most abundant metal element or metalloid element among the elements that make up the media contained in the water, it is possible to accurately measure element M, which is the metal element or metalloid element contained in the water.

[0024] The temperature inside the grinding chamber is preferably in the range of 15°C to 25°C. When the stirring rotor is rotated at the first rotation speed for 6 hours or the stirring rotor is rotated at the second rotation speed for 6 hours in the grinding chamber, if the temperature inside the grinding chamber is maintained in the range of 15°C to 25°C, the media is loaded in a stable state, and the wear rate can be measured from fine powder or fragments that have fallen off the media due to shedding or wear of crystal particles. As described later, for example, when the wear rate is measured by element M, which is the most abundant metal element or semimetal element among the elements that constitute the media contained in water, the element M remaining in the water can be accurately measured, and the first wear rate W1 and the second wear rate W2 can be accurately measured. The temperature inside the grinding chamber can be maintained within a certain temperature range by using a double-structure grinding chamber equipped with an outer tank (jacket) and circulating a liquid medium such as hot water or cold water in the jacket, or by heating or cooling the water circulating in the grinding chamber outside the grinding chamber.

[0025] In the grinding chamber of the bead mill, the distance between the outer circumference of the disk, which is the outermost circumference of the stirring rotor, or the tip of the pin and the inner wall of the grinding chamber of the bead mill is preferably within a range of 10% to 15% of the diameter of the grinding chamber of the bead mill, and more preferably within a range of 12% to 14%. For example, if the inner diameter of the grinding chamber of the bead mill is 50 mm and the length of the pin is 44 mm, the distance between the inner wall of the grinding chamber and the tip of the pin is 6 mm, which is the length of the inner diameter of the grinding chamber, 50 mm, minus the length of the pin, 44 mm, and the distance between the tip of the pin and the inner wall is 12% of the inner diameter of the grinding chamber. In the grinding chamber of a bead mill, if the distance between the outermost circumference of the disk or pin of the stirring rotor and the inner wall of the grinding chamber is within the range of 10% to 15% of the inner diameter of the grinding chamber, the media and liquid in the grinding chamber can be sufficiently mixed, the media is likely to be subjected to load, and the wear ratio W2 / W1 between the first wear rate W1 at the first rotation speed and the second wear rate W2 at the second rotation speed is likely to become large, making it possible to evaluate the stable wear resistance of the media.

[0026] In the method for evaluating the media, the first wear rate W1 and the second wear rate W2 are preferably determined by measuring the amount of element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in water, after rotating the stirring rotor at the first rotation speed for 6 hours or after rotating the stirring rotor at the second rotation speed for 6 hours, and deriving the first wear rate W1 and the second wear rate W2 from the amount of element M converted into oxide or nitride based on the following formula (1): In the following formula (1), "time (h)" is the rotation time of the stirring rotor. TIFF2025071802000001.tif31159

[0027] In the method for evaluating media, the amount of element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in the water, is preferably measured by high-frequency inductively coupled plasma atomic emission spectrometry (ICP). When a load is applied by the stirring rotor in the grinding chamber of the bead mill, the media with low wear resistance will have fine fragments remaining in the water circulating through the bead mill due to the shedding and wear of crystal particles. After rotating the stirring rotor at a specific rotation speed for a specific time, the amount of element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in the water circulating through the bead mill, is measured, and the wear rate can be derived based on the above formula (1). By measuring the amount of element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in the water circulating through the bead mill by ICP, even a small value of element M of 1 ppm by mass, which corresponds to 0.0001% by mass, can be measured. When measuring element M in water by ICP, an ICP atomic emission spectrometry analyzer (e.g., ICPS-8100 (manufactured by Shimadzu Corporation)) or the like can be used. The amount of element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in water, may be measured by ICP or may be analyzed by X-ray fluorescence spectrometry (XRF).

[0028] The first wear rate W1 and the second wear rate W2 may be determined by measuring the amount of element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in the water, or by measuring the weight of the media before and after rotating the stirring rotor at the first rotation speed or the second rotation speed for six hours.

[0029] In the method for evaluating the media, a bead mill is used, and the media for grinding and / or dispersion is placed in the grinding chamber of the bead mill so as to satisfy the above-mentioned condition 1 that the amount of the media filled is 70 to 85 volume % of the effective volume of the grinding chamber, and water is circulated through the grinding chamber in an amount that satisfies the above-mentioned condition 2 that the flow rate of the water circulated through the bead mill is 150 to 190 mL / min. The stirring rotor is rotated in the grinding chamber at the above-mentioned first rotation speed for 100 hours, and the third wear rate is measured, and a durability test can be performed. The third wear rate W3 can be derived in the same manner as the first wear rate and the second wear rate based on the above-mentioned formula (1). The amount of element M contained in the water after the durability test can be measured by the above-mentioned method. When performing the durability test, the first rotation speed at which the stirring rotor of the bead mill is rotated is preferably 8 m / s in order to continue applying a relatively small load to the media for 100 hours. The temperature in the grinding chamber is preferably within a range of 15°C to 25°C in order to apply a load to the media in a stable state. The media for measuring the third wear rate W3 may be the same as the media for measuring the first wear rate W1 and the media for measuring the second wear rate W2, or different media of the same type may be used. When the media for measuring the third wear rate W3 is the same as the media for measuring the first wear rate W1 and the media for measuring the second wear rate W2, the third wear rate W3 may be measured after measuring the first wear rate W1 and the second wear rate W3.

[0030] The media is a bead mill, and grinding and / or dispersion media is placed in the grinding chamber so as to satisfy the above-mentioned condition 1, and water is circulated through the grinding chamber so as to satisfy the above-mentioned condition 2 to rotate the agitator rotor in the grinding chamber, and the wear ratio W2 / W1 between a first wear rate W1 measured by rotating the agitator rotor for 6 hours at a first rotation speed having a peripheral speed of 8 m / sec and a second wear rate W2 measured by rotating the agitator rotor for 6 hours at a second rotation speed having a peripheral speed of 10 m / sec is 1.7 or less.

[0031] When the stirring rotor is rotated at the first rotation speed, a small load is applied to the media. When the stirring rotor is rotated at the second rotation speed, a load larger than that at the first rotation speed is applied to the media. When the wear ratio W2 / W1 of the media is 1.7 or less, the difference between the wear rate W1 when a small load is applied to the media for a long time and the wear rate W2 when a large load is applied to the media for a long time is small, and it can be confirmed that the media has stable wear resistance. The wear ratio W2 / W1 of the media may be 1.6 or less, or may be 1.5 or less. Since the wear rate of the media tends to increase when a relatively large load is applied to the media, the wear ratio W2 / W1 will not be 1.0 or less. The wear ratio W2 / W1 of the media is preferably 1.0 or more and 1.7 or less. Media with a wear ratio W2 / W1 of 1.7 or less are also effective as media used for the grinding and / or dispersion treatment of powders used in electronic component materials, etc., and media used for the grinding and / or dispersion treatment of medical powders that need to maintain high purity. Media with a wear ratio W2 / W1 of 1.7 or less measured under the condition that the filling amount of the media is 70 to 85 volume % when the effective volume of the grinding chamber of the bead mill is 100 volume %, and the flow rate of water circulated to the bead mill is 150 to 190 mL / min are satisfied can be effectively used as media for grinding and / or dispersing objects. Even if the wear ratio W2 / W1 measured under the condition that does not satisfy the above-mentioned condition 1 and / or condition 2 is 1.7 or less, the momentum of the media may decrease in the grinding chamber of the bead mill, or the wear of the media may be uneven, and the wear may not progress uniformly, and the media may not be effectively used for grinding and / or dispersing objects. Media with a wear ratio W2 / W1 of 1.7 or less measured under the condition that does not satisfy the above-mentioned condition 1 and / or condition 2 may have a third wear rate of 50 mass ppm / hour or more that can be measured by rotating the media at the first rotation speed for 100 hours while satisfying condition 1 and condition 2, and the wear rate and wear ratio may not be measured accurately when considering actual use.

[0032] The media is preferably zirconia-based media, silicon nitride-based media, or alumina-based (aluminum oxide-based) media, because zirconia-based media, silicon nitride-based media, or alumina-based media are used as media that require wear resistance.

[0033] The media preferably has an average media diameter of 0.015 to 0.5 mm, which is the maximum diameter of the media that can be confirmed in an SEM image using a scanning electron microscope (SEM). Even if the average media diameter is 0.015 to 0.5 mm, by measuring the first wear rate W1 when the stirring rotor is rotated at a first rotation speed and the second wear rate W2 when the stirring rotor is rotated at a second rotation speed faster than the first rotation speed using a bead mill while satisfying the above-mentioned conditions 1 and 2, it is possible to measure the wear ratio W2 / W1, which is the ratio of the first wear rate W1 when a small load is applied to the media and the second wear rate W2 when a large load is applied to the media, and if the wear ratio W2 / W1 is 1.7 or less, it can be confirmed that the media has stable wear resistance with little damage even when used for a long period of time. The average media diameter was calculated by taking images of 200 media using a scanning electron microscope (SEM), and analyzing the images using image analysis software (e.g., Image-Pro Plus (manufactured by Nippon Roper Co., Ltd.)) to determine the maximum diameter of the media as the media diameter, and creating a particle size distribution of the media diameters of the 200 media. The average media diameter of the 200 media can then be calculated.

[0034] As described above, when the first wear rate W1 and the second wear rate W2 are measured based on the element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in water, the element M varies depending on the type of media. The zirconia media is made of a sintered body mainly composed of zirconium oxide. In this specification, "containing as the main component of the media" or "being the main component of the media" means that a specific component is contained in an amount of 50 mass% or more based on the total amount of the media. The specific component that is the main component may be the amount of a metal element or nonmetal element converted into an oxide or nitride.

[0035] In the zirconia media, the most abundant metal element or semimetal element among the elements constituting the media is zirconium (Zr). An example of the zirconia media is a ZrO2-Y2O3-based zirconia sintered body, with a Y2O3 / ZrO2 molar ratio in the range of 2.5 / 97.5 to 3.2 / 96.8, an Al2O3 content in the range of 0.1 mass% to 30.0 mass%, a tetragonal zirconia (T) content of 90 volume% or more, and a relative density of 95% or more. The zirconia media may contain, for example, SiO2 in the range of 0.2 mass% to 1.0 mass%. For the zirconia media, for example, the zirconia media described in International Publication No. 2023 / 210268 may be referred to.

[0036] The relative density of the media can be calculated from the following formula (2). The apparent density is measured by the gas displacement method defined in JIS R1620. The theoretical density can be calculated from the theoretical density and composition ratio of the main components constituting the sintered body that constitutes the media. TIFF2025071802000002.tif31159

[0037] Silicon nitride media is made of a sintered body whose main component is silicon nitride. The most abundant metallic or semi-metallic element among the elements that compose the silicon nitride media is silicon (Si).

[0038] The alumina media is made of a sintered body mainly composed of aluminum oxide. The most abundant metal element or metalloid element among the elements constituting the alumina media is aluminum (Al). The alumina media may contain other metal elements or metalloid elements other than aluminum.

[0039] The media is placed in the grinding chamber of the bead mill so as to satisfy condition 1 that the filling amount of the media is 70 to 85 volume % of the effective volume of the grinding chamber, and water is circulated in the grinding chamber so as to satisfy condition 2 that the flow rate of the water circulated in the bead mill is 150 to 190 mL / min. The third wear rate W3 of the media measured by rotating the stirring rotor at the first rotation speed in the grinding chamber for 100 hours is preferably 50 mass ppm / hour or less. The first rotation speed is preferably 8 m / sec. The temperature in the grinding chamber is preferably in the range of 15°C to 25°C. Media whose wear ratio W2 / W1 measured under conditions satisfying the above-mentioned condition 1 and / or condition 2 is 1.7 or less and whose third wear rate is 50 mass ppm / hour or less have wear rates and wear ratios measured accurately in consideration of actual use, and have excellent wear resistance. The measurement of the third wear rate W3 can be derived based on the above-mentioned formula (1). The third wear rate W3 of the media may be 45 ppm by mass / hour or less, or 40 ppm by mass / hour or less. The third wear rate W3 of the media may be 1 ppm by mass / hour or more, 2 ppm by mass / hour or more, 3 ppm by mass / hour or more, or 5 ppm by mass / hour or more.

[0040] A method for producing media includes using a bead mill and placing grinding and / or dispersion media in a grinding chamber of the bead mill so as to satisfy condition 1 below; circulating water through the grinding chamber so as to satisfy condition 2 below, rotating the stirring rotor in the grinding chamber at a first rotation speed for 6 hours, and measuring a first wear rate W1 of the media; circulating water through the grinding chamber so as to satisfy condition 2 below, rotating the stirring rotor in the grinding chamber at a second rotation speed faster than the first rotation speed for 6 hours, and measuring a second wear rate W2 of the media; and deriving a wear ratio W2 / W1 of the second wear rate W2 to the first wear rate W1, thereby obtaining media having a wear ratio W2 / W1 of 1.7 or less. Condition 1: The amount of media filled is 70-85% of the effective volume of the grinding chamber. Condition 2: Flow rate circulated through the bead mill is 150-190 mL / min

[0041] In the manufacturing method of media, if media having a wear ratio W2 / W1 of 1.7 or less can be obtained using the above-mentioned media evaluation method, the difference in wear ratio between when a small load is applied to the media for a long time and when a large load is applied to the media for a long time will be small, and media with stable wear resistance can be obtained. The wear ratio W2 / W1 of the media is preferably 1.0 or more and 1.7 or less.

[0042] In the media manufacturing method, when the media having a wear ratio W2 / W1 of 1.7 or less is obtained using the above-mentioned media evaluation method, the first rotation speed, the second rotation speed, the shape of the grinding chamber, and the temperature inside the grinding chamber can be in the same range of values ​​as in the above-mentioned media evaluation method. In addition, in the media manufacturing method, when the media having a wear ratio W2 / W1 of 1.7 or less is obtained using the above-mentioned media evaluation method, the first wear rate, the second wear rate, and the amount of element M in water can be derived using a method similar to the above-mentioned media evaluation method.

[0043] The method for producing the media preferably includes using a bead mill, placing the media in the grinding chamber of the bead mill so as to satisfy condition 1 that the filling amount of the media is 70 to 85 volume % of the effective volume of the grinding chamber, circulating water in the grinding chamber so as to satisfy condition 2 that the flow rate of the water circulated in the bead mill is 150 to 190 mL / min, rotating the stirring rotor in the grinding chamber at a first rotation speed for 100 hours, measuring a third wear rate W3 of the media, and conducting a durability test of the media to obtain media having a third wear rate W3 of 50 mass ppm / hour or less. The first rotation speed is preferably 8 m / sec. The temperature in the grinding chamber is preferably in the range of 15°C to 25°C.

[0044] Media having a third wear rate W3 of 50 mass ppm / hour or less measured by the above-mentioned method have stable wear resistance even after a 100-hour durability test, and are also effective as media used in the grinding and / or dispersion treatment of powders used in electronic component materials, etc., and as media used in the grinding and / or dispersion treatment of medical powders that must maintain high purity. The third wear rate W3 and the amount of element M in the water can be derived using a method similar to the above-mentioned media evaluation method, and the third wear rate W3 can be derived based on the above-mentioned formula (1) in the same manner as the above-mentioned first wear rate W1 and second wear rate W2. EXAMPLES

[0045] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0046] Examples 1 to 6 In each example, media was used having the main components, composition, crystal phase, relative density, and average media diameter values ​​shown in Table 1. In Table 1, the components (elements) that represent the composition are shown as values ​​converted into oxides or nitrides. In Table 1, the symbol "-" indicates that there is no value for the corresponding item. The media in Examples 1, 5, and 6 are zirconia-based media, the media in Examples 2 and 4 are silicon nitride-based media, and the media in Example 3 is an alumina-based media. As for theoretical density, the theoretical density of the main component of the zirconia-based media is 6.10 g / cm. 3 The theoretical density of the main component of silicon nitride media is 3.23 g / cm 3 The theoretical density of the main component of the alumina media is 3.75 g / cm 3 indicates the relative density of each medium measured based on the above formula (2). The bead mill used was an Ultra Apex Mill (UAM-015, manufactured by Hiroshima Metal & Machinery Co., Ltd.). The effective volume of the grinding chamber of the bead mill was 170 mL (170 cm 3 ) The stirring rotor installed in the bead mill was a pin-type rotor with 10 pins arranged alternately at right angles to the rotating shaft. The distance between the tips of the pins, which form the outermost periphery of the stirring rotor, and the inner wall of the grinding chamber of the bead mill was 12% of the inner diameter of the grinding chamber. In each example, the grinding chamber of the bead mill was filled with each type of media so as to achieve the media filling amount specified in Condition 1 of Table 1. Deionized water was used as the water, and in each example, the water was circulated through the grinding chamber of the bead mill at a flow rate of condition 2 in Table 1, and the volume of water circulated was 4 to 5 times the effective volume of the grinding chamber. The temperature of the grinding chamber is maintained at a temperature of not less than 20°C and not more than 25°C. After rotating the stirring rotor for 6 hours at a first rotation speed of 8 m / sec, the rotation of the stirring rotor was stopped and the amount of element M (Zr, Si or Al) in the water was determined by ICP using an ICP emission spectrometer (ICPS-8100, manufactured by Shimadzu Corporation). Based on the above formula (1), the first wear rate W1 (mass ppm / hour) was derived. Next, media was filled into the grinding chamber to create conditions similar to those when rotating at the first rotation speed, water was poured into the grinding chamber, and the stirring rotor was rotated for 6 hours at a second rotation speed with a peripheral speed of 10 m / sec. After that, the rotation was stopped and the element M (Zr, Si or Al) in the water was determined by ICP, and a second wear rate W2 (mass ppm / hour) was derived in the same manner as the first wear rate W1. The wear ratio W2 / W1 of the second wear rate W2 to the first wear rate W1 was calculated. The results are shown in Table 1.

[0047] Comparative Examples 1 and 2 In Comparative Examples 1 and 2, media having the main components, composition, crystal phase, relative density, and average media diameter values ​​shown in Table 1 were used. Using a bead mill similar to those used in Examples 1 to 6, media was placed in the grinding chamber so as to satisfy condition 1 shown in Table 1, water was circulated so as to satisfy condition 2, and the stirring rotor was rotated at the first rotation speed and the second rotation speed similar to those used in Examples 1 to 6. The first wear rate W1, the second wear rate W2, and the wear ratio W2 / W1 were measured similar to those used in Examples 1 to 6. The temperature of the grinding chamber is maintained at a temperature of not less than 20°C and not more than 25°C. The media of Comparative Examples 1 and 2 have a wear ratio W2 / W1 exceeding 1.7.

[0048] Comparative Examples 3 to 5 In Comparative Examples 3 to 5, media having the main components, composition, crystal phase, relative density and average media diameter values ​​shown in Table 1 were used. Using a bead mill similar to those used in Examples 1 to 6, media and water were circulated in the grinding chamber so as to satisfy conditions 1 and 2 shown in Table 1, and the stirring rotor was rotated at the first rotation speed and the second rotation speed similar to those used in Examples 1 to 6. The first wear rate W1, the second wear rate W2, and the wear ratio W2 / W1 were measured similar to those used in Examples 1 to 6. The temperature of the grinding chamber is maintained at a temperature of not less than 20°C and not more than 25°C. In Comparative Example 3, the filling amount of the media in Condition 1 is less than 70% by volume of the effective volume of the grinding chamber. In Comparative Example 4, the flow rate of the solution circulated through the bead mill under Condition 2 exceeds 190 mL / min. In Comparative Example 5, the amount of media packed in Condition 1 exceeds 85% by volume of the effective volume of the grinding chamber.

[0049] Media Composition The oxide equivalent value of the components (elements) that represent the composition of each medium in the examples and comparative examples represents the oxide equivalent ratio of the compound containing each element that is the raw material in the mixed powder used as the raw material. Silicon nitride (Si3N4) represents the mass ratio (mass%) of silicon nitride (Si3N4) used as the raw material to the total mass of the mixed powder used as the raw material (100 mass%). In the case where the media are not manufactured from raw materials and the composition is measured by analyzing the media, when the media is zirconia media, the media is crushed and the crushed powder is heat-treated at 1100 to 1300°C to produce glass beads, and the Y2O3 content in the media is measured by X-ray fluorescence analysis (XRF) using an X-ray fluorescence analyzer. The crushed media is dissolved in sulfuric acid using a pressure decomposition vessel to prepare a sample, and the contents of Al2O3, Fe2O3, SiO2, TiO2, CaO, and MgO in the media are measured by high-frequency inductively coupled plasma optical emission spectrometry (ICP) using an ICP optical emission spectrometer (ICPS-8100, manufactured by Shimadzu Corporation). The above-mentioned sample is also measured for the contents of Na2O and K2O by flame photometry using an atomic absorption spectrophotometer (ZA3300, manufactured by Hitachi, Ltd.). The ZrO2 content of the above samples was measured by the difference method (100 - the total amount of each component other than ZrO2). Table 1 lists only the contents of Y2O3 / ZrO2 (molar ratio), ZrO2 (mass%), Al2O3 (mass%), Y2O3 (mass%), and SiO2 (mass%). When the media is silicon nitride media and the composition is measured by analyzing the media, the media is crushed, the crushed powder is heat-treated at 1500 to 1700 ° C in air or an oxidizing atmosphere, the treated powder is heat-treated at 1100 to 1300 ° C to prepare glass beads, and the SiO2 content is measured by X-ray fluorescence analysis (XRF) using the same X-ray fluorescence analyzer as described above. The SiO2 obtained from the measurement result is assumed to be Si3N4 completely oxidized by heat to become SiO2, and the amount of components other than SiO2 is obtained by the difference method (100-SiO2). The obtained SiO2 content is converted to the Si3N4 content before heat treatment and the Si3N4 content is measured in terms of nitrides. In air or an oxidizing atmosphere means an atmosphere containing 20 volume % or more of oxygen in the atmosphere. When the media is an alumina media and the composition is measured by analyzing the media, the media is crushed, and the crushed powder is heat-treated at 1100 to 1300°C to produce glass beads. The contents of components other than Al2O3 are measured by X-ray fluorescence analysis (XRF) using the same X-ray fluorescence analyzer as described above, and the Al2O3 content is measured by the difference method (100-total amount of components other than Al2O3).

[0050] Crystalline phase of media In the cases where the media in the Examples and Comparative Examples were zirconia media, the presence or absence and content of monoclinic zirconia (M), the content of tetragonal zirconia (T), and the presence or absence and content of cubic zirconia (C) in the zirconia crystal phase of the zirconia media were determined by X-ray diffraction. Specifically, the presence or absence and content of monoclinic zirconia (M), the content of tetragonal zirconia (T), and the presence or absence and content of cubic zirconia (C) were determined as follows. The media is placed in the hardening embedding resin so that it is equal to or larger than the area of ​​a circle with a diameter of 10 mm or more, and the hardening embedding resin is hardened. The media embedded in the hardened hardening embedding resin is ground to about one third of the diameter of the cross section. The ground surface is lapped to a depth of 5 μm or more with 4 to 8 μm diamond abrasive grains, and further with 3 μm or less diamond abrasive grains, and finally polished with 1 μm or less diamond abrasive grains, and mirror-polished so that the surface roughness Rz according to JIS B0601:2001 is less than 0.050 μm (surface roughness Rz<0.05 μm), and measured by X-ray diffraction method at a diffraction angle range of 27 degrees to 34 degrees. The monoclinic zirconia (M) content (volume %) can be calculated from the results obtained by the measurement using the following formula (3). In this specification, the hardening embedding resin can be, for example, a polyester resin, an acrylic resin, or an epoxy resin. The conditions for X-ray diffraction are as follows: X-ray source: CuKα, output: 40 kV / 40 mA, incident side divergence slit: 1 / 2°, incident side Soller slit: 4.1°, receiving side divergence slit: 5.2 mm, receiving side Soller slit: OPEN, scan speed: 0.5° / min, scan axis 2θ / θ.

[0051] TIFF2025071802000003.tif48163

[0052] The presence or absence and content (volume %) of cubic zirconia (C) can be determined in the same manner as for the content of monoclinic zirconia (M) by measuring the diffraction angle in the range of 70 degrees to 77 degrees by X-ray diffraction, and the content can be calculated from the obtained results using the following formula (4). Furthermore, based on the above results, the content of tetragonal zirconia (T) can be calculated from the following formula (5).

[0053] TIFF2025071802000004.tif61163

[0054] Media diameter average For each medium used in the examples and comparative examples, 200 media were photographed using a scanning electron microscope (SEM). The photographed images were analyzed using image analysis software (Image-ProPlus, manufactured by Nippon Roper Co., Ltd.) to determine the maximum diameter of the medium as the media diameter, and the arithmetic mean value of the media diameters of the 200 media as the average media diameter.

[0055] Media evaluation (conditions, wear ratio W1 / W2) In the examples and comparative examples, a bead mill shown in the example or comparative example is used. Place media in the grinding chamber of the bead mill so that the media loading amount is equal to Condition 1 described in Table 1. Water is introduced into the grinding chamber at a flow rate that circulates the bead mill under condition 2 in Table 1, and the stirring rotor is rotated in the grinding chamber at a first rotation speed, which is a peripheral speed of 8 m / sec shown in each example and comparative example, for 6 hours, and the first wear rate W1 of each media is measured. Water is introduced into the grinding chamber at a flow rate that circulates the bead mill under condition 2 in Table 1, and the stirring rotor is rotated in the grinding chamber at the second rotation speed, which is a peripheral speed of 10 m / sec shown in each example and comparative example, for 6 hours, and the second wear rate W2 of each media is measured. The wear ratio W2 / W1 of the second wear rate W2 to the first wear rate W1 is calculated. The first wear rate W1 and the second wear rate W2 are determined by measuring the amount of element M, which is the most abundant metal element or semimetal element among the elements constituting each medium contained in water, and deriving the first wear rate W1 and the second wear rate W2 based on the above formula (1) from the amount of element M converted into oxide or nitride. The amount of element M in water is measured by high-frequency inductively coupled plasma optical emission spectroscopy (ICP) using an ICP optical emission spectrometer (ICPS-8100, manufactured by Shimadzu Corporation). In the above formula (1), "time (h)" is the rotation time of the stirring rotor.

[0056] Durability Testing In the examples and comparative examples, a bead mill similar to the one used to determine the wear ratio W2 / W1 was used, and each media was placed in the grinding chamber so that the media filling volume was 75 volume %, and the flow rate of water circulated through the bead mill was set to 170 mL / min, and a volume of water 4 to 5 times the effective volume of the grinding chamber was circulated. After rotating the stirring rotor for 100 hours at a peripheral speed of 8 m / sec, the third wear rate W3 (mass ppm / hour) was derived based on the above formula (1) in the same manner as when the first wear rate W1 and the second wear rate W2 were derived. The third wear rate W3 derived after rotating the stirring rotor for 100 hours was taken as the result of the durability test. The third wear rate W3 was derived in the same manner as the first wear rate W1 and the second wear rate W2. The temperature of the grinding chamber during the durability test was maintained at 20°C or higher and 25°C or lower. The results are shown in Table 1.

[0057] Whether or not the media is cracked For the media before the wear rate measurement, the media after the second wear rate W2 measurement, and the media after the third wear rate W3 measurement, 10% by mass of the total media used was taken out and visually observed at 200x magnification using a digital microscope. The presence or absence of cracks in the media is shown in Table 1.

[0058] [Table 1]

[0059] As shown in Examples 1 to 6, a bead mill is used, and each media is placed in the grinding chamber of the bead mill so as to satisfy condition 1 that the filling amount of the media is 70 to 85 volume% of the effective volume of the grinding chamber. Water is circulated to the grinding chamber so as to satisfy condition 2 that the flow rate circulated to the bead mill is 150 to 190 mL / min. The stirring rotor is rotated in the grinding chamber at a first rotation speed for 6 hours, and the first wear rate W1 of the media is measured. Water is circulated to the grinding chamber so as to satisfy condition 2 that the flow rate circulated to the bead mill is 150 to 190 mL / min. The stirring rotor is rotated in the grinding chamber at a second rotation speed faster than the first rotation speed for 6 hours, and the second wear rate W2 of the media is measured. The wear ratio W2 / W1 of the second wear rate W2 to the first wear rate W1 is derived. The wear ratio W2 / W1 of the media is small at 1.7 or less, and a media having stable wear resistance was obtained.

[0060] As shown in Examples 1 to 6, media with a wear ratio W2 / W1 of 1.7 or less had a third wear rate W3 of 50 mass ppm / hour or less after a 100-hour durability test, and media with stable wear resistance was obtained. According to the media and manufacturing method thereof disclosed herein, the stable wear resistance of media can be evaluated and media with high wear resistance can be obtained by measuring the wear ratio between the first wear rate W1 when a small load is applied to the media under specific conditions and the second wear rate W2 when a larger load is applied compared to the small load.

[0061] Furthermore, in Examples 1 to 6, the media was placed in the grinding chamber of a bead mill similar to the one used to determine the wear ratio W2 / W1, with the media filled in 75% by volume of the grinding chamber, and the flow rate of water circulating through the bead mill was set to 170 mL / min, circulating water at a volume 4 to 5 times the effective volume of the grinding chamber.The stirring rotor was rotated for 100 hours at a peripheral speed of 8 m / sec. After the durability test, the third wear rate W3 of the media was 50 mass ppm / hour or less, and media with stable wear resistance was obtained even after the 100-hour durability test.

[0062] The media in Example 3 was an alumina-based media, and had a wear ratio W2 / W1 of 1.7 or less and a third wear rate of 48.4 mass ppm / hour after a 100-hour durability test, resulting in a media with stable wear resistance.

[0063] In Examples 2 and 4, the media with a wear ratio W2 / W1 of 1.7 or less had a third wear rate W3 of 50 mass ppm / hour or less after a 100-hour durability test, more specifically, a third wear rate of 40 mass ppm / hour or less, and thus had stable wear resistance even after a 100-hour durability test. The media according to Examples 2 and 4 are silicon nitride media made of a sintered body containing silicon nitride as the main component.

[0064] As shown in Comparative Example 1, the media according to Comparative Example 1, which has the same main component as the media used in Example 1, has a wear ratio W2 / W1 exceeding 1.7 and a third wear rate W3 of 99.0 mass ppm / hour after a 100-hour durability test, and does not have stable wear resistance. The media according to Comparative Example 1 is a zirconia-based media, with a Y2O3 / ZrO2 molar ratio in the range of 2.5 / 97.5 to 3.2 / 96.8, an Al2O3 content in the range of 0.1 mass% to 30.0 mass%, and contains 90 volume% or more of tetragonal zirconia, but contains more than 1.0 mass%, and it is presumed that the SiO2 phase is formed at the grain boundaries of ZrO2, causing a decrease in strength. The wear ratio W2 / W1 exceeds 1.7 and the third wear rate exceeds 50 mass ppm / hour even after a 100-hour durability test, causing a decrease in wear resistance.

[0065] As shown in Comparative Example 2, the media according to Comparative Example 2 had a considerably large wear ratio W2 / W1 of 4.29. On the other hand, the media according to Comparative Example 2 had cracks after a 100-hour durability test, and the third wear rate W3 after the 100-hour durability test was 214.2 mass ppm / hour, which was a significant wear. If cracks occur in the media, there is a risk of relatively large foreign matter being mixed into the treated object, and the media cannot be used as a medium for grinding and / or dispersing powders for electronic components or pharmaceutical powders that require high purity to be maintained. It is presumed that the strength of the media according to Comparative Example 2 has decreased, and even after a 100-hour durability test, the third wear rate was very large, wear resistance was reduced, and cracks occurred.

[0066] As shown in Comparative Example 3, if the media filling amount is less than 70 volume % of the effective volume of the grinding chamber and condition 1 that the media filling amount is 70 to 85 volume % of the effective volume of the grinding chamber is not met, the media will not move smoothly inside the grinding chamber of the bead mill, and the wear ratio W2 / W1 will be 1.7 or less. However, in a 100-hour durability test, if the media filling amount is optimized to meet condition 1, such that the media filling amount is 75 volume % of the effective volume of the grinding chamber, the impact on the media will be large, and the third wear rate W3 will exceed 50 mass ppm / hour, and media with stable wear resistance will not be obtained.

[0067] As shown in Comparative Example 4, the flow rate of water circulated through the bead mill exceeds 190 mL / min, which does not satisfy condition 2 of 150 to 190 mL / min, causing the media to float in the bead mill and resulting in low media momentum, and the wear ratio W2 / W1 is 1.7 or less. However, in a 100-hour durability test, the flow rate of water circulated through the bead mill is 170 mL / min. If the flow rate is adjusted to satisfy condition 2, the third wear rate W3 will exceed 50 mass ppm / hour after the durability test, causing cracks to occur in the media, and media with stable wear resistance will not be obtained. The media according to Comparative Example 4 is a zirconia media, with a Y2O3 / ZrO2 molar ratio of 3.5 / 96.5, which exceeds 3.2 / 96.8, an Al2O3 content in the range of 0.1 mass% to 30.0 mass%, and tetragonal zirconia content of 90 volume% or more, but it is presumed that the strength is reduced due to the large amount of Y2O3. The media according to Comparative Example 4 has a wear ratio W2 / W1 of 1.7 or less, but after a 100-hour durability test, the third wear rate exceeded 50 mass ppm / hour, cracks occurred, and wear resistance was reduced.

[0068] As shown in Comparative Example 5, when the filling amount of the media exceeds 85 volume % of the effective volume of the grinding chamber, the momentum of the media decreases, and the wear ratio W2 / W1 is 1.7 or less. However, when the filling amount of the media is optimized to satisfy condition 1, that is, 75 volume % of the effective solution in the grinding chamber in a 100-hour durability test, the third wear rate W3 exceeds 50 mass ppm / hour after the 100-hour durability test, cracks occur, and wear resistance decreases. [Industrial Applicability]

[0069] The media according to the present disclosure and the media produced by the method thereof have stable wear resistance as media that can be used in bead mills and the like. Media with stable wear resistance can be effectively used as media used in the grinding and / or dispersion treatment of powders used in electronic component materials and the like, and media used in the grinding and / or dispersion treatment of pharmaceutical powders that need to maintain high purity. In addition, the media according to the present disclosure and the media produced by the method thereof have stable wear resistance and can be used as bearing balls. When the media is used as bearing balls, bearings equipped with bearing balls can be used in wind power generators, airplanes, automobiles, bicycles, trains, refrigerators, air conditioners, vacuum cleaners, copy machines, washing machines, massage chairs, cameras, electric drivers, personal computers, automatic ticket gates, walking paths, elevators, conveyors, and other medical devices such as computer tomography devices (CT), magnetic resonance imaging devices (MRI), and dental handpieces.

Claims

1. Using a bead mill, Grinding and / or dispersion media are placed in the grinding chamber of the bead mill so as to satisfy the following condition 1, Water is circulated in the grinding chamber so as to satisfy the following condition 2, an agitator rotor in the grinding chamber is rotated, and a wear ratio W2 / W1 of a first wear rate W1 of the media measured by rotating the agitator rotor for 6 hours at a first rotation speed having a peripheral speed of 8 m / sec and a second wear rate W2 of the media measured by rotating the agitator rotor for 6 hours at a second rotation speed having a peripheral speed of 10 m / sec is 1.7 or less. Condition 1: The amount of media filled is 70 to 85% by volume of the effective volume of the grinding chamber. Condition 2: Flow rate of the bead mill is 150 to 190 mL / min

2. The media of claim 1 , wherein the media is a zirconia-based media, a silicon nitride-based media, or an alumina-based media.

3. The media is a zirconia-based media, and the zirconia-based media is ２ O ３ / ZrO ２ The molar ratio is within the range of 2.5 / 97.5 to 3.2 / 96.8, ２ O ３ The content of is in the range of 0.1 mass % or more and 30.0 mass % or less, tetragonal zirconia is contained in an amount of 90 volume % or more, and SiO ２ The media according to claim 1 , wherein the content of the cation is in the range of 0.2% by mass or more and 1.0% by mass or less.

4. 3. The media according to claim 1, wherein the average media diameter, which is the maximum diameter of the media ascertainable in an SEM image using a scanning electron microscope, is 0.015 to 0.5 mm.

5. Place the bead mill in the grinding chamber so as to satisfy condition 1, 3. The media according to claim 1 or 2, wherein a third wear rate W3 of the media is measured by circulating water through the grinding chamber so as to satisfy condition 2 and rotating an agitator rotor in the grinding chamber at the first rotation speed for 100 hours, and the third wear rate W3 of the media is 50 mass ppm / hour or less.

6. 3. The medium according to claim 1 or 2, which is used for grinding and / or dispersing powders used in electronic component materials or powders for medical use.

7. Using a bead mill, Putting a grinding and / or dispersing medium into the grinding chamber of the bead mill so as to satisfy the following condition 1; circulating water in the grinding chamber so as to satisfy the following condition 2, rotating the stirring rotor in the grinding chamber at a first rotation speed having a peripheral speed of 8 m / sec for 6 hours, and measuring a first wear rate W1 of the media; circulating water in the grinding chamber so as to satisfy the following condition 2, rotating the stirring rotor in the grinding chamber at a second rotation speed having a peripheral speed of 10 m / sec higher than the first rotation speed for 6 hours, and measuring a second wear rate W2 of the media; Deriving a wear ratio W2 / W1 of the second wear rate W2 to the first wear rate W1; obtaining a media having a wear ratio W2 / W1 of 1.7 or less. Condition 1: The amount of media filled is 70 to 85% by volume of the effective volume of the grinding chamber. Condition 2: Flow rate of the bead mill is 150 to 190 mL / min

8. The method of claim 7 , wherein the grinding chamber is a vertical grinding chamber.

9. The method for producing media according to claim 7 , wherein the temperature inside the grinding chamber is within a range of 15° C. to 25° C.

10. 8. The method for manufacturing media described in claim 7, wherein the first wear rate W1 and the second wear rate W2 are determined by measuring the amount of element M, which is the most abundant metal element or metalloid element among the elements constituting the media contained in the water, after rotating an agitation rotor at a first rotation speed for six hours or after rotating an agitation rotor at the second rotation speed for six hours, and deriving the first wear rate W1 and the second wear rate W2 from the amount of element M in terms of oxide or nitride based on the following formula (1).

11. The method for producing a medium according to claim 7 , wherein the amount of element M in the water is measured by inductively coupled plasma emission spectrometry (ICP).

12. Putting the beads into the grinding chamber of the bead mill so as to satisfy condition 1; 8. The method for producing media according to claim 7, comprising: circulating water through the grinding chamber so as to satisfy the following condition 2; rotating an agitating rotor at the first rotation speed in the grinding chamber for 100 hours; measuring a third wear rate W3 of the media; and conducting a durability test of the media to obtain media having a third wear rate W3 of 50 mass ppm / hour or less.

13. The method of claim 12, wherein the temperature inside the grinding chamber is in the range of 15°C to 25°C.

14. 13. The method for manufacturing media described in claim 12, wherein the third wear rate W3 is determined by measuring the amount of element M, which is the most abundant metal element or semi-metal element among the elements constituting the media contained in the water after rotating the stirring rotor at a first rotation speed for 100 hours, and deriving the third wear rate W3 from the amount of element M converted into an oxide or nitride based on the following formula (1).

15. The method for producing a medium according to claim 14, wherein the amount of element M in the water is measured by inductively coupled plasma emission spectrometry (ICP).