JPWO2016024624A1 - Abrasive, manufacturing method thereof and abrasive composition - Google Patents

Abstract

In view of the fact that conventional polishing α-alumina particles do not have sufficient mirror finish or polishing rate, and there is a demand for polishing particles with better polishing properties, the polishing properties are excellent, especially the polishing rate is high. Provided is α-alumina for polishing which can be used for mirror surface processing with less scratching on the polished surface. An abrasive comprising α-alumina having a BET specific surface area of 0.01 to 20 m 2 / g, wherein the α-alumina is obtained by firing an aluminum compound in the presence of a molybdenum compound, Abrasive.

Description

The present invention relates to an abrasive comprising α-alumina having excellent polishing characteristics obtained by a flux method using molybdenum oxide.
The present invention also relates to a method for producing an abrasive comprising α-alumina having excellent polishing characteristics.
Furthermore, the present invention relates to an abrasive composition containing an abrasive having excellent polishing characteristics.

  Alumina is used in a wide range of applications such as abrasives, electronic materials, heat dissipating fillers, optical materials, catalyst carriers, and biomaterials because of its excellent chemical stability, thermal conductivity, and heat resistance. Yes. Alumina has various crystal forms such as α, κ, γ, δ, θ, and the like. In particular, alumina in the α crystal form has a Mohs hardness of 9, and is widely used for polishing applications.

  Generally, α-alumina used as an abrasive is produced by high-temperature firing of fused alumina or alumina synthesized by the Bayer method in a firing furnace. The produced α-alumina is pulverized by a pulverizer such as a ball mill, the particle diameter is adjusted by pulverization conditions, classification, etc., and used for abrasives. However, since the alumina particles produced in this way have a wide particle size distribution and include coarse particles having a crushing surface and sharp edges, scratches (scratches) larger than the average surface roughness are generated on the surface to be polished. I will let you. Further, there are problems such as balls used for pulverization such as a ball mill, mixing of impurities from pulverizing equipment, etc., pulverization for a long time and a large amount of energy being consumed.

  Against this background, the synthesis of α-alumina abrasive particles having a narrow particle size distribution has attracted attention. For example, in Patent Document 1, a mirror surface having excellent polishing properties and less scratches is obtained by using aluminum hydroxide having specific physical properties as a raw material, pulverizing with an airflow collision pulverizer after high-temperature baking exceeding 1200 ° C. An α-alumina that can also be applied to polishing is disclosed. Patent Document 2 discloses that halogen gas is used as an atmospheric gas, an alkaline earth metal compound is added to aluminum hydroxide or transition alumina, and the surface to be polished is free from a polyhedral-shaped crushing surface by high-temperature firing. Abrasive α-alumina particles that are less likely to occur are disclosed. However, in these methods, mirror finishing and polishing rate are not sufficient, and there is a demand for abrasive particles with better polishing properties. In addition, any α-alumina described in Patent Documents 1 and 2 is obtained by alumina particles that can be used as an abrasive by physical pulverization using a jet mill.

  In recent years, research on synthesis of inorganic materials learned from nature and living organisms has been actively conducted. Among them, the flux method is a method for precipitating crystals from a solution of an inorganic compound or a metal at a high temperature by utilizing the wisdom that crystals (minerals) are created in nature. Features of this flux method include that crystals can be grown at a temperature much lower than the melting point of the target crystal, crystals with extremely few defects grow, and self-forms develop.

Non-Patent Document 1 reports the formation of a hexagonal bipyramidal ruby crystal by firing a high temperature using a large amount of molybdenum oxide (MoO ₃ ) as a fluxing agent. According to Non-Patent Document 1, molybdenum oxide is selectively adsorbed on the [113] plane of a ruby crystal, and the crystal component is less likely to be supplied to the [113] plane, so that the appearance of the [001] plane can be completely suppressed. Is. Patent Document 3 discloses a hexagonal bipyramidal artificial corundum having a particle diameter of 1 mm to 3 mm by firing a mixture of molybdenum oxide, alumina and other auxiliary agents (containing 95% molybdenum oxide) at 1100 ° C. A method for producing a crystal is disclosed.

However, in these methods, it is difficult to produce α-alumina having a particle size of 100 μm or less that can be used as an abrasive. In addition, since a large amount of molybdenum oxide is used as a fluxing agent, there are problems in terms of environment and cost.
Patent Document 4 discloses α-alumina synthesized by molybdenum oxide as a fluxing agent in Patent Document 4, but does not mention characteristics as an abrasive.

JP-A-8-2913 JP 2002-68739 A WO2005 / 054550 WO2014 / 051091 publication

Oishi et al. , J .; Am. Chem. Soc. 2004, 126, 4768-4769.

  In view of the above circumstances, the problem of the present inventors is to provide an α-alumina for polishing that is excellent in polishing characteristics, has a particularly high polishing rate, has few scratches on the surface to be polished, and can be used for mirror finishing. That is.

As a result of diligent research to solve such problems, the present inventors have used a molybdenum compound as a fluxing agent, a novel α-alumina abrasive having physical properties satisfying all of the above polishing characteristics, and this The present inventors have found a simple and efficient production method of an abrasive and an abrasive composition containing the abrasive. That is, when an aluminum compound is used as a precursor and it is fired in the presence of a molybdenum compound, the molybdenum compound acts on the aluminum compound as a fluxing agent to form polyhedral α-alumina fine particles at a relatively low temperature. The present inventors have found that the α-alumina is useful as an abrasive and have completed the present invention.

That is, the present invention is an abrasive comprising α-alumina having a BET specific surface area of 0.01 to ²⁰ m ² / g, and the α-alumina is obtained by firing an aluminum compound in the presence of a molybdenum compound. The above-described problems are solved by providing an abrasive that is characterized.

  Moreover, this invention solves the said subject by providing the abrasive | polishing material in which the said alpha alumina contains molybdenum in particle | grains.

  Further, the present invention is characterized in that in the firing of the aluminum compound in the presence of the molybdenum compound, the aluminum compound and the molybdenum compound form a step of forming aluminum molybdate and the step of decomposing the aluminum molybdate. The above-mentioned problems are solved by providing a polishing material.

  In the present invention, the α-alumina has an average particle diameter of 100 μm or less, or the cumulative volume distribution of the α-alumina has a ratio D90 of 50% (D50) and 90% (D90). / D50 is the range of 1.2-2.5, and the said subject is solved by providing the abrasive | polishing material of the said description.

  The present invention also provides the abrasive described above, wherein the α-alumina has a polyhedral shape having an edge, wherein the α crystallization ratio is 90% or more, the main crystal plane is a crystal plane other than the [001] plane. This solves the above problem.

  Further, the present invention includes a step of firing an aluminum compound in the presence of a molybdenum compound, a step of obtaining α-alumina after firing, and a step of removing a molybdenum metal salt remaining after firing. A method for producing an abrasive comprising alumina, and a method for producing an abrasive comprising α-alumina, further comprising a step in which an aluminum compound and a molybdenum compound form aluminum molybdate and a step in which aluminum molybdate decomposes. Is.

  The present invention also provides an abrasive composition containing the above abrasive.

The abrasive comprising α-alumina of the present invention has excellent polishing properties such as efficient polishing, suppression of clutch generation and mirror finish due to high α crystallinity, narrow particle size distribution, narrow specific surface area, and presence of sharp edges. It has characteristics and can be usefully used for rough polishing, intermediate polishing, finishing / mirror finishing of a wide range of materials such as electrode materials, metals, ceramics, and semiconductors as an abrasive or as an abrasive composition.
Furthermore, the method for producing an abrasive of the present invention is a simple production method only for firing under specific conditions, and is a low-cost method that does not involve physical pulverization using a solvent, waste liquid discharge, complicated process, pulverizer, or the like. It is a manufacturing method that is environmentally friendly and energy-saving, and is a manufacturing method that suppresses the mixing of impurities from equipment accompanying grinding and the generation of coarse particles having sharp sharp edges, and can produce a high-performance abrasive.

2 is a scanning electron micrograph of an abrasive made of α-alumina containing molybdenum obtained in Example 1. FIG. 2 is an XRD chart of an abrasive made of α-alumina containing molybdenum obtained in Example 1. FIG. 4 is a scanning electron micrograph of an abrasive made of α-alumina containing molybdenum obtained in Example 2. FIG. 4 is a scanning electron micrograph of an abrasive made of α-alumina containing molybdenum obtained in Example 3. FIG. 2 is a scanning electron micrograph of the surface to be polished obtained in Example 1. FIG. 2 is a scanning electron micrograph of a surface to be polished obtained in Comparative Example 1.

The abrasive of the present invention can be obtained by using an aluminum compound of an arbitrary shape as a precursor and firing in the presence of a molybdenum compound, and has a narrow particle size distribution and mainly has a crystal plane other than the [001] plane. It is an abrasive made of polyhedral α-alumina having a crystal plane. By adjusting the compounding ratio between the aluminum compound used as the precursor and the molybdenum compound, the type and firing temperature of the molybdenum compound, the firing time and the type, specific surface area, particle size and shape of the precursor aluminum compound. It is possible to control the shape, particle diameter, etc. of the abrasive made of α-alumina. Furthermore, by firing using a molybdenum compound as a fluxing agent, an α crystallization rate of 100% is obtained, crystal planes other than the [001] plane grow, the particle size distribution is extremely narrow, and has an edge. A polyhedral shape with excellent polishing characteristics can be obtained.
The abrasive comprising α-alumina of the present invention is obtained by firing an aluminum compound in the presence of a molybdenum compound. Details will be described below.

<Aluminum compound>
The aluminum compound in the present invention is a raw material of the abrasive material comprising the α-alumina of the present invention and is not particularly limited as long as it becomes alumina by heat treatment. For example, aluminum chloride, aluminum sulfate, basic aluminum acetate, water Aluminum oxide, boehmite, pseudoboehmite, transition alumina (γ-alumina, δ-alumina, θ-alumina, etc.), α-alumina, mixed alumina having two or more kinds of crystal phases, etc. can be used, and aluminum as a precursor thereof The physical form such as the shape, particle diameter, specific surface area, etc. of the compound is not particularly limited.

  In the flux method described in detail later, since the shape of the raw material aluminum compound is hardly reflected in the shape of the abrasive comprising α-alumina of the present invention, for example, a spherical structure, an amorphous structure, an aspect structure (wire, Any of fiber, ribbon, tube, etc.) and sheet can be suitably used.

  Similarly, since the particle diameter of the aluminum compound is hardly reflected in the abrasive material made of α-alumina of the present invention in the flux method described in detail later, a solid aluminum compound of several nm to several hundred μm is used. It can be used suitably.

  The specific surface area of the aluminum compound is not particularly limited. Since the molybdenum compound acts effectively, it is preferable that the specific surface area is large. However, any specific surface area can be used as a raw material by adjusting the firing conditions and the amount of the molybdenum compound used.

  Further, the aluminum compound may be composed of only an aluminum compound or a complex of an aluminum compound and an organic compound. For example, an organic / inorganic composite obtained by modifying alumina using organosilane and an aluminum compound composite adsorbed with a polymer can be suitably used. When these composites are used, the content of the organic compound is not particularly limited, but from the viewpoint of efficiently producing alumina fine particles having excellent polishing characteristics, the content may be 60% by mass or less. Preferably, it is 30% by mass or less.

<Molybdenum compound>
The molybdenum compound used in the present invention may be, for example, molybdenum oxide or a compound containing an acid radical anion formed by bonding molybdenum metal with oxygen. The compound containing an acid radical anion formed by bonding molybdenum metal with oxygen is not particularly limited as long as it can be converted into molybdenum trioxide by high-temperature baking. As such a molybdenum compound, for example, molybdic acid, hexaammonium heptamolybdate, diammonium molybdate, phosphomolybdic acid, molybdenum disulfide, and the like can be preferably used. Particularly preferred is the use of molybdenum trioxide.

The molybdenum compound may be molybdenum oxide or a compound containing an acid radical anion (MoO _x ⁿ⁻ ) formed by bonding molybdenum metal with oxygen. Among these, it is preferable to use molybdenum oxide from the viewpoint of cost.

The compound containing an acid radical anion (MoO _x ⁿ⁻ ) formed by bonding molybdenum metal with oxygen is not particularly limited as long as it can be converted into molybdenum oxide by high-temperature baking. For example, molybdic _{acid, H 3 PMo 12 O 40,} H 3 SiMo 12 O 40, NH 4 Mo 7 O 12 , etc. can be suitably used.

<Baking>
The abrasive comprising α-alumina of the present invention can be obtained, for example, by firing an aluminum compound in the presence of a molybdenum compound. This manufacturing method is called a flux method. The specific surface area of the abrasive comprising α-alumina of the present invention is greatly reduced by firing from the specific surface area of the aluminum compound as a raw material, and the specific surface area is in the range of 0.001 to 50 m ² / g, The thing of the range of 01-20m < ² > / g is obtained suitably.

  In the flux method using a molybdenum compound as a fluxing agent, most of the used molybdenum compound is sublimated by the baking treatment at a high temperature. However, a part of the molybdenum compound is incorporated into the α-alumina particles, and α containing molybdenum. -Alumina is obtained. Since α-alumina used as an abrasive material has problems such as a decrease in polishing characteristics such as a decrease in hardness due to the inclusion of impurities and a tendency to crushing, a high-purity material is used. The abrasive α-alumina has high hardness and does not deteriorate the polishing characteristics even though it contains molybdenum inside. In addition, since it is contained inside, α-alumina of the abrasive of the present invention is a colored particle different from a normal white alumina abrasive, and is a light blue to dark blue particle close to black. Further, the production method of the present invention is characterized in that other trace metals, for example, red with chromium and yellow with nickel, and the abrasive made of α-alumina of the present invention is colored particles that are not white. The colored particles are preferable because the abrasive can be distinguished from the fine powder that appears when the object to be polished is polished.

The content of molybdenum in the abrasive comprising the α-alumina of the present invention is not particularly limited, but from the viewpoint of efficiently producing α-alumina having excellent polishing characteristics, The molybdenum content of α-alumina is preferably 10% by mass or less, and more preferably 1% by mass or less by adjusting the firing temperature, firing time, and sublimation rate of the molybdenum compound.

In addition, in a manufacturing method in which a large amount of molybdenum compound is used as a fluxing agent and a long time is taken, it is not preferable because a large alumina of molybdenum of the order of mm or more is generated, and the amount of aluminum compound and molybdenum compound used is particularly Although there is no limitation, the molar ratio of molybdenum in the molybdenum compound to aluminum in the aluminum compound is 0. From the viewpoint of efficiently obtaining polyhedral particles having a high α crystallization rate preferable for polishing characteristics and an edge with a narrow particle size distribution. It is preferably in the range of 03 to 3.0, more preferably in the range of 0.08 to 0.7, and the firing time is not particularly limited, but the α-alumina of the abrasive of the present invention is not limited. In general, the temperature is raised to a predetermined firing temperature in the range of 15 minutes to 10 hours, and at the firing temperature. By performing the holding time in the range of 5 minutes to 30 hours, it is possible to form α-alumina that is optimal for abrasives of 100 μm or less.

Further, the temperature of calcination, the maximum temperature may be at least 900 ° C. is a decomposition temperature of aluminum molybdate _{(Al 2 (MoO 4) 3} ).
Generally, to control the shape of α-alumina obtained after firing, it is necessary to perform high-temperature firing at 2000 ° C. or higher, which is close to the melting point of α-alumina, but from the viewpoint of burden on the firing furnace and fuel cost, There are major challenges for industrial use.
The production method of the present invention can be carried out even at a high temperature exceeding 2000 ° C., but even at a temperature much lower than the melting point of α-alumina of 1600 ° C. or less, α It is possible to form α-alumina that has a high crystallization rate and has a polyhedral shape, which is optimal for an abrasive.
According to the present invention, even when the maximum firing temperature is 900 ° C. to 1600 ° C., it is possible to form alumina fine particles that are optimal for abrasives that are nearly spherical and have an α crystallization rate of 90% or more at low cost. Baking can be performed efficiently, baking at a maximum temperature of 950 to 1500 ° C is more preferable, and baking at a maximum temperature in the range of 1000 to 1400 ° C is most preferable.

  Regarding the firing time, it is preferable to perform the temperature raising time to a predetermined maximum temperature in the range of 15 minutes to 10 hours, and the holding time at the maximum firing temperature in the range of 5 minutes to 30 hours. In order to efficiently form α-alumina fine particles that are optimal as an abrasive, a firing holding time of about 10 minutes to 15 hours is more preferable.

  The firing atmosphere is not particularly limited as long as the effects of the present invention can be obtained. For example, an oxygen-containing atmosphere such as air or oxygen, or an inert atmosphere such as nitrogen or argon is preferable, in consideration of cost. Is more preferably an air atmosphere. A non-corrosive atmosphere such as halogen gas is preferable from the viewpoint of the safety of the practitioner and the durability of the furnace.

  The apparatus for firing is not necessarily limited, and a so-called firing furnace can be used. The firing furnace is preferably made of a material that does not react with the sublimated molybdenum oxide, and it is preferable to use a highly sealed firing furnace so that molybdenum oxide can be used efficiently.

  In some cases, molybdenum oxide or metal molybdate contained in the raw material may remain as impurities on the surface of the α-alumina thus obtained. Since impurities remaining on the surface may deteriorate the characteristics of α-alumina as an abrasive or contaminate the workpiece, it is preferable to remove them. As the removal method, firing may be performed for a long time at a high temperature of 1300 ° C. or higher, or cleaning may be performed with a basic aqueous solution such as water or aqueous ammonia. can get. The fact that there is no unevenness on the surface leads to the absence of fine holes on the surface and the low specific surface area due to the synthesis by crystal growth by the flux method.

<Abrasive made of α-alumina containing molybdenum>
The abrasive of the present invention is α-alumina containing molybdenum having a BET specific surface area of 0.01 to ²⁰ m ² / g and a particle diameter of 100 μm or less. As a polishing agent, a preferable particle size is 100 μm or less, and a material having a narrow particle size distribution is used. Since α-alumina used for ordinary abrasives is manufactured by pulverization, it has a wide particle size distribution and particles with sharp sharp edges, etc., aiming for higher performance abrasives, Adjustment is made so that the distribution is narrowed by pulverization for a long time, or classification is performed. However, since the α-alumina of the abrasive of the present invention is synthesized by the flux method, the particle size distribution is sharp and the polishing characteristics are more excellent without performing pulverization or classification.

  Therefore, the average particle diameter of α-alumina of the abrasive of the present invention is not particularly limited, but is preferably 0.05 μm to 100 μm in order to obtain good polishing characteristics. If the average particle diameter of α-alumina of the abrasive of the present invention is 0.05 μm or more, a sufficient polishing rate can be obtained, and if it is 100 μm or less, deep scratches are less likely to occur on the surface to be polished. ,preferable. Moreover, the abrasive | polishing material consisting of (alpha) -alumina of this invention can select and use a particle diameter according to target grinding | polishing. For example, 10 μm or more can be used for roughing, 5 μm to 10 μm for intermediate polishing, and 5 μm or less for finishing or mirror polishing.

  Furthermore, the particle size distribution of α-alumina of the abrasive of the present invention is not particularly limited, but preferably 50% cumulative (D50) from the small diameter side of the cumulative volume distribution in order to reduce the occurrence of scratches on the surface to be polished. And 90% cumulative (D90) ratio D90 / D50 is in the range of 1.5 to 5.0, more preferably in the range of 1.3 to 3.0, and most preferably 1.1 to 2. The range is 5. A narrow particle size distribution is advantageous in obtaining a clean polished surface with less scratching on the polished surface. In particular, by synthesizing by the above-described flux method, it is possible to suitably obtain polyhedral particles having self-shaped, low-aggregation, and edges having a narrow particle size distribution.

  The shape, particle size distribution, size, specific surface area and the like of the abrasive comprising α-alumina of the present invention can be controlled by selecting the use ratio of the aluminum compound and the molybdenum compound, the firing temperature, and the firing time.

  The α-alumina of the abrasive of the present invention may be in various crystal forms such as κ, χ, η, γ, δ, θ, etc., but basically, in terms of high hardness and excellent polishing characteristics. The α crystal form is preferred. The crystal structure of a general α-type alumina is a dense hexagonal lattice, and the most thermodynamically stable crystal structure is a plate shape with a developed [001] plane. By firing the aluminum compound in the presence, the molybdenum compound acts as a fluxing agent and has a high α crystallization rate with a crystal plane other than the [001] plane as the main crystal plane, and in particular, the α crystallization rate is 90% or more. Α-alumina can be formed more easily. The crystal plane other than the [001] plane being the main crystal plane means that the area of the [001] plane is 20% or less with respect to the total area of the fine particles.

  The shape of the alumina abrasive according to the present invention is not particularly limited, but a polyhedral shape having an edge with a small flat surface area is advantageous in improving the polishing rate. With the above-described flux method, polyhedral particles having edges can be obtained. Among them, the area of the largest flat surface is less than one-eighth of the area of the structure, and the area of the largest flat surface is particularly the structure. Those of 1/16 or less of the body area are preferably obtained.

  In addition, α-alumina obtained by the flux method using a large amount of fluxing agent that is generally performed is a hexagonal bipyramidal type milli-order large particle, and as an abrasive, it causes a large scratch on the surface to be polished. ,Not appropriate.

  The form of molybdenum contained in the α-alumina of the abrasive of the present invention is not particularly limited. For example, the structure of molybdenum compound such as molybdenum trioxide or partially reduced molybdenum dioxide or alumina is used. A part of aluminum may be included in the form of being replaced by molybdenum.

<Abrasive composition>
The abrasive comprising α-alumina of the present invention can be made into an abrasive composition by being dispersed in a medium or mixed with a polishing accelerator or additive. The dispersion medium is usually water, but it is possible to use an aqueous solvent or an organic solvent. Examples of the polishing accelerator and additive include various metal salts, resins, and surface active agents. In addition, other abrasives such as silica and magnesium oxide can be used in combination as long as the characteristics of the abrasive comprising α-alumina of the present invention are not lost.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these Examples. Note that “%” represents “% by mass” unless otherwise specified.

[Analysis of the shape of an abrasive made of α-alumina and observation of scratches on the polished surface with a scanning electron microscope]
The sample was fixed to a sample support with a double-sided tape, and observed with a surface observation device VE-9800 manufactured by Keyence Corporation. 100 alumina particles containing molybdenum confirmed by a scanning electron microscope were selected at random, and the maximum diameter of the alumina particles containing molybdenum was measured, and the range of the particle diameters was shown. Moreover, the average value of the measured value was made into the average particle diameter.
The polished glassy carbon cross section was fixed to a sample support with a double-sided tape, and the polished surface was observed with a surface observation device VE-9800 manufactured by Keyence Corporation.

[Analysis of particle size distribution of abrasives made of α-alumina using Shimadzu laser diffraction particle size distribution analyzer]
A sample of the produced abrasive material made of α-alumina was dispersed in water, and the particle size distribution was measured with a laser diffraction particle size distribution analyzer SALD-7000 manufactured by Shimadzu Corporation.

[Analysis of abrasives made of α-alumina by XRD]
Place the prepared sample on the measurement sample holder, set it on the wide-angle X-ray diffractometer [Rint-Ultma] manufactured by Rigaku Corporation, Cu / Kα ray, 40 kV / 30 mA, scan speed 1.0 ° / min, scanning Measurement was performed under conditions of a range of 5 to 80 °.

[Specific surface area measurement of abrasives made of α-alumina by BET method]
The specific surface area was measured by a nitrogen gas adsorption / desorption method using a Tris star 3000 type apparatus manufactured by Micromeritics.

[Evaluation of chemical bond of abrasives made of α-alumina by ²⁷ Al-NMR measurement]
Using JNM-ECA600 manufactured by JEOL Ltd., solid ²⁷ Al single pulse non-decoupling CNMR measurement was performed. The chemical shift was determined by the automatic reference setting of the instrument.

[Composition analysis of abrasives made of α-alumina by fluorescent X-ray]
About 100 mg of a sample was placed on a filter paper and covered with a PP film, and fluorescent X-ray measurement (ZSX100e / Rigaku Corporation) was performed.

[Baking]
Firing was performed in a ceramic electric furnace ARF-100K type firing furnace apparatus with an AMF-2P type temperature controller manufactured by Asahi Rika Seisakusho Co., Ltd.

Example 1 <Production of Abrasive Material Containing α-Alumina>
48 g of transition alumina (manufactured by Wako Pure Chemical Industries, Ltd., activated alumina, average particle size 45 μm) and 12 g of molybdenum trioxide (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed in a mortar, and transition alumina and molybdenum oxide were mixed. 60 g of a mixture was obtained. The obtained mixture was put in a crucible and fired at 1000 ° C. for 3 hours in a ceramic electric furnace. After the temperature was lowered, the crucible was taken out, and the contents were washed with 10% ammonia water and ion exchange water and then dried at 150 ° C. for 2 hours to obtain 47 g of a blue powder.

The obtained powder is a polyhedral particle having a particle diameter of 4 to 6 μm (average particle diameter of 5 μm) by SEM observation, having a crystal plane other than the [001] plane as a main crystal plane, and an edge of a narrow particle size distribution. This was confirmed (Fig. 1). Other than the hexagonal bipyramidal shape, it was an octahedral or higher polyhedral particle. The particle size distribution was measured with SALD-7000, and the obtained abrasive particles had a D50 of 6.0 μm and a D90 / D50 of 1.8. Further, when XRD measurement was performed, a sharp scattering peak derived from α-alumina appeared, and no crystal system peak other than the α crystal structure was observed (FIG. 2). According to solid ²⁷ Al-NMR measurement, only a peak derived from α-coordinate 6-coordinated aluminum was observed in the range from 15 ppm to 19 ppm. These suggest that α-alumina having an α crystallization rate of 100% is formed. Furthermore, the BET specific surface area was 0.45 m ² / g, indicating a high hardness and a dense particle structure. Moreover, from the result of the fluorescent X-ray quantitative analysis, it was confirmed that the obtained particles contained 98.4% alumina and 0.67% molybdenum. From the above analysis, it was confirmed that α-alumina obtained by this method had a good form as an abrasive.

<Abrasiveness evaluation by abrasive composition containing abrasive that is α-alumina>
Using round paper glassy carbon (diameter 3 mm, length 100 mm, manufactured by BAS), polishing paper DCCS600 and DCCS2000 (manufactured by Sankyo Rikagaku Co., Ltd.), rough cutting of the glassy carbon and intermediate polishing were sequentially performed. The glassy carbon cross section was subjected to final polishing with the abrasive made of α-alumina manufactured above.
0.5 g of an abrasive made of α-alumina is placed on a polishing pad (alumina polishing pad, manufactured by BAS), and about 10 drops of water are dropped thereon to form a slurry. The round bar glassy carbon after rough cutting and intermediate polishing was pressed vertically against the slurry on the pad, and polishing was performed 150 times so as to draw a figure 8. It was confirmed by visual observation that the polished surface of the round bar glassy carbon can be processed into a beautiful mirror surface. Further, it was confirmed by SEM observation that the surface to be polished had very few scratches (FIG. 5). The excellent polishing characteristics of the abrasive composition containing the abrasive that was α-alumina of the present invention were confirmed.

Example 2 <Production of Abrasive Material Containing α-Alumina>
30 g of aluminum hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., particle size 0.2 to 1.0 μm) and 30 g of molybdenum oxide (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed in a mortar. The obtained mixture was fired at 1100 ° C. for 10 hours in a ceramic electric furnace. After the temperature was lowered, the crucible was taken out, and the contents were washed with 10% ammonia water and ion exchange water and then dried at 150 ° C. for 2 hours to obtain 19 g of blue powder. SEM observation reveals that the particle size is 2 to 3 μm (average particle size 2.5 μm), the shape is nearly spherical, the crystal plane other than the [001] plane is the main crystal plane, and the polyhedral particles have edges with a narrow particle size distribution (Fig. 3). Other than the hexagonal bipyramidal shape, it was an octahedral or higher polyhedral particle. The particle size distribution was measured with SALD-7000, and the obtained abrasive particles had a D50 of 4.4 μm and a D90 / D50 of 1.6. Furthermore, when XRD measurement was performed, a sharp scattering peak derived from α-alumina appeared, and no crystal system peak other than the α crystal structure was observed (α crystallization rate 100%). Furthermore, the BET specific surface area was 1.0 m ² / g, indicating a high hardness and dense particle structure. Moreover, from the result of the fluorescent X-ray quantitative analysis, it was confirmed that the obtained particles contained 98.6% alumina and 0.30% molybdenum. From the above analysis, it was confirmed that α-alumina obtained by this method had a good form as an abrasive.

Example 3 <Production of Abrasive Material Containing α-Alumina>
50 g of γ-alumina (manufactured by STREM CHEMICALS, particle size 40 to 70 μm) and 50 g of molybdenum trioxide (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed in a mortar. The obtained mixture was fired at 1100 ° C. for 10 hours in a ceramic electric furnace. After the temperature was lowered, the crucible was taken out, and the contents were washed with 10% ammonia water and ion exchange water and then dried at 150 ° C. for 2 hours to obtain 49 g of a blue powder. By SEM observation, it was confirmed that the particle size was 20 to 25 μm (average particle size 23 μm), the crystal plane other than the [001] plane was a main crystal plane, and it was a polyhedral particle having an edge with a narrow particle size distribution (see FIG. 4). Other than the hexagonal bipyramidal shape, it was an octahedral or higher polyhedral particle. Further, the particle size distribution was measured with SALD-7000. The obtained abrasive particles had a D50 of 25 μm and a D90 / D50 of 1.3. Furthermore, when XRD measurement was performed, a sharp scattering peak derived from α-alumina appeared, and no crystal system peak other than the α crystal structure was observed (α crystallization rate 100%). Furthermore, the BET specific surface area was 0.04 m ² / g, indicating a high hardness and dense particle structure. Moreover, from the result of the fluorescent X-ray quantitative analysis, it was confirmed that the obtained particles contained 97.3% alumina and 0.45% molybdenum. From the above analysis, it was confirmed that α-alumina obtained by this method had a good form as an abrasive.

Comparative Example 1
In the same manner as in Example 1, polishing properties were evaluated using a commercially available α-alumina abrasive (AP-A Powder, manufactured by Struers) having an average particle diameter of 5 μm. Although it was confirmed by visual observation that the polished surface was a mirror surface, it was confirmed by SEM observation that relatively many deep scratches were generated on the polished surface (FIG. 6). This is because a commercially available α-alumina oxide material is produced by pulverization and contains amorphous coarse particles having sharp and sharp edges, resulting in deep scratches on the surface to be polished and a decrease in polishing characteristics.

The abrasive comprising α-alumina of the present invention has excellent polishing properties such as efficient polishing, suppression of clutch generation and mirror finish due to high α crystallinity, narrow particle size distribution, narrow specific surface area, and presence of sharp edges. It has characteristics and can be usefully used for rough polishing, intermediate polishing, finishing / mirror finishing of a wide range of materials such as electrode materials, metals, ceramics, and semiconductors as an abrasive or as an abrasive composition.
Furthermore, the method for producing an abrasive of the present invention is a simple production method only for firing under specific conditions, and is a low-cost method that does not involve physical pulverization using a solvent, waste liquid discharge, complicated process, pulverizer, or the like. It is a manufacturing method that is environmentally friendly and energy-saving, and is a manufacturing method that suppresses the mixing of impurities from equipment accompanying grinding and the generation of coarse particles having sharp sharp edges, and can produce a high-performance abrasive.

Claims (11)

A polishing material comprising α-alumina having a BET specific surface area of 0.01 to ²⁰ m ² / g, wherein the α-alumina is obtained by firing an aluminum compound in the presence of a molybdenum compound. , Abrasive.   The abrasive according to claim 1, wherein the α-alumina contains molybdenum in the particles.   The firing of the aluminum compound in the presence of the molybdenum compound includes a step in which the aluminum compound and the molybdenum compound form aluminum molybdate and a step in which the aluminum molybdate decomposes. Abrasive.   4. The abrasive according to claim 1, further comprising a step of removing a metal molybdate existing on the particle surface after firing in firing the aluminum compound in the presence of the molybdenum compound. 5.   The abrasive | polishing material in any one of Claims 1-4 whose average particle diameter of the said alpha alumina is 100 micrometers or less.   The cumulative volume distribution of the α-alumina has a ratio D90 / D50 of a cumulative 50% (D50) and a cumulative 90% (D90) from the smaller diameter side in a range of 1.2 to 2.5. The abrasive | polishing material in any one.   The polishing according to any one of claims 1 to 6, wherein the α-alumina has a polyhedral shape having an α crystallization ratio of 90% or more, a main crystal plane other than the [001] plane, and an edge. Wood.   Polishing comprising α-alumina, characterized by comprising a step of firing an aluminum compound in the presence of a molybdenum compound, a step of obtaining α-alumina after firing, and a step of removing molybdenum metal salt remaining after firing. A method of manufacturing the material.   The step of firing the aluminum compound in the presence of the molybdenum compound further includes a step of forming the aluminum molybdate by the aluminum compound and the molybdenum compound and a step of decomposing the aluminum molybdate. The manufacturing method of the abrasive | polishing material as described in any one of.   The abrasive | polishing material obtained by the manufacturing method of Claim 8 or 9.   An abrasive composition comprising the abrasive according to any one of claims 1 to 7 or 10.

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