JP6632287B2 - Zirconia micro media - Google Patents
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- JP6632287B2 JP6632287B2 JP2015184988A JP2015184988A JP6632287B2 JP 6632287 B2 JP6632287 B2 JP 6632287B2 JP 2015184988 A JP2015184988 A JP 2015184988A JP 2015184988 A JP2015184988 A JP 2015184988A JP 6632287 B2 JP6632287 B2 JP 6632287B2
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- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 title claims description 87
- 239000013078 crystal Substances 0.000 claims description 15
- 230000003746 surface roughness Effects 0.000 claims description 11
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 claims description 7
- 239000000843 powder Substances 0.000 description 31
- 239000006185 dispersion Substances 0.000 description 12
- 239000002245 particle Substances 0.000 description 12
- 230000007423 decrease Effects 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 238000005299 abrasion Methods 0.000 description 7
- 239000011324 bead Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000000465 moulding Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 239000004005 microsphere Substances 0.000 description 5
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 3
- 239000010987 cubic zirconia Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 3
- NGDQQLAVJWUYSF-UHFFFAOYSA-N 4-methyl-2-phenyl-1,3-thiazole-5-sulfonyl chloride Chemical compound S1C(S(Cl)(=O)=O)=C(C)N=C1C1=CC=CC=C1 NGDQQLAVJWUYSF-UHFFFAOYSA-N 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000009616 inductively coupled plasma Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- CMOAHYOGLLEOGO-UHFFFAOYSA-N oxozirconium;dihydrochloride Chemical compound Cl.Cl.[Zr]=O CMOAHYOGLLEOGO-UHFFFAOYSA-N 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000004993 emission spectroscopy Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000008204 material by function Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000009700 powder processing Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000004154 testing of material Methods 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
- -1 zirconia compound Chemical class 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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- Compositions Of Oxide Ceramics (AREA)
Description
本発明は耐摩耗性及び耐久性に優れたジルコニア質微小メディアに関する。 The present invention relates to a zirconia-based fine media having excellent wear resistance and durability.
セラミック積層コンデンサは小型化と高特性化が益々進み、最近ではスマートフォン等にかなりの数が搭載されている。小型化や高特性化のため製造に用いる粉体の微粉化及び高純度化が必要不可欠となっており、微粉体の製造技術の向上に加えて、コンデンサを製造する際の粉体の分散も非常に重要となっている。微粉体の分散は現在ジルコニア製メディアを用いて湿式で行われているが、使用する粉体の粒度が微細化するほどメディアサイズも微小化する必要がある。また、コンデンサの高特性化のため処理する粉体への不純物の混入を極力抑制する必要があり、耐摩耗性に優れた微小メディアが求められている。また、微小メディア（直径：０．２ｍｍ以下）は、これより大きいサイズのメディアと異なり、微小なためにミル内での動きが悪い。そこで、ミルの撹拌速度を上げる等の方策がとられているが、撹拌速度を上げると微小メディアであっても非常に大きな負荷が加わるため、微小メディアがミル内で破損し、その破片が粉砕されて被処理粉体中に不純物として混入する。したがって、大きいサイズのメディア以上に強度に関する信頼性が要求される。特に微小メディアは大きいメディアに比べてメディア内部に同じサイズの欠陥があっても圧壊荷重値が大幅に低下する危険性がある。 Ceramic multilayer capacitors have been increasingly miniaturized and improved in characteristics, and recently, a considerable number are mounted on smartphones and the like. It is indispensable to make the powder used for manufacturing finer and highly purified for miniaturization and higher performance.In addition to improving the fine powder manufacturing technology, the dispersion of powder when manufacturing capacitors is also required. It has become very important. The dispersion of the fine powder is currently performed in a wet manner using a zirconia medium, but as the particle size of the powder used becomes finer, the media size also needs to be reduced. In addition, it is necessary to minimize the mixing of impurities into the powder to be processed in order to improve the characteristics of the capacitor, and there is a demand for a fine media having excellent wear resistance. Further, unlike a medium having a size smaller than that of a medium having a diameter of 0.2 mm or less, the minute medium has a small size and therefore has poor movement in a mill. Therefore, measures such as increasing the stirring speed of the mill have been taken.However, when the stirring speed is increased, a very large load is applied even to minute media. And mixed as impurities into the powder to be treated. Therefore, the reliability regarding the strength is required more than the large size media. In particular, there is a risk that the crushing load value of a micro media is significantly reduced even if there is a defect of the same size inside the media as compared with a large media.
特許文献１には高耐摩耗性ジルコニア微小球が開示されている。しかし、この微小球は原料粉末を熱プラズマフレームで加熱溶解して微小球としているため、微小球の表面の結晶粒径が非常に大きく、かつ結晶粒界幅が広くなるため、使用時間が長くなると結晶粒界への腐食により粒界が脆弱化し、摩耗特性の安定化に問題がある。また加熱溶融して固化させるため、得られた微小球に多くの気孔が残存し易く、機械的強度の低下が見られる。
一方、特許文献２には、スラリー温度が高くなっても摩耗特性が低下しないジルコニア質メディアが、特許文献３には、粉体の硬さが硬くなっても耐摩耗性が低下しないジルコニア質メディアがそれぞれ開示されているが、耐摩耗性及び耐久性以外の特性については何等検討されておらず、微小メディアとしての検討はされていない。
Patent Document 1 discloses high wear-resistant zirconia microspheres. However, since these microspheres are made into microspheres by heating and melting a raw material powder in a thermal plasma flame, the crystal grain size on the surface of the microspheres is very large, and the crystal grain boundary width is wide, so that the use time is long. When this occurs, the grain boundaries become brittle due to corrosion at the grain boundaries, and there is a problem in stabilizing the wear characteristics. Further, since the particles are solidified by heating and melting, many pores are likely to remain in the obtained microspheres, and a decrease in mechanical strength is observed.
On the other hand, Patent Literature 2 discloses a zirconia-based media whose wear characteristics do not decrease even when the slurry temperature increases, and Patent Document 3 discloses a zirconia-based media whose wear resistance does not decrease even when the hardness of the powder becomes harder. However, there is no study on characteristics other than abrasion resistance and durability, and there is no study on micro media.
本発明は耐摩耗性及び耐久性に優れたジルコニア質微小メディアの提供を目的とする。 An object of the present invention is to provide a zirconia-based micro media excellent in wear resistance and durability.
本発明らは鋭意研究を重ねた結果、ジルコニア質微小メディアにおいてＹ２Ｏ３を特定の割合で含有させたジルコニア質焼結体であって、相対密度、平均結晶粒径及び圧壊荷重値が特定の範囲内にあり、かつ微小メディアの表面粗さを特定の範囲内とすることにより、耐摩耗性及び耐久性に優れ、高い分散効率を有するジルコニア質微小メディアが得られることを見出し、本発明を完成するに至った。
即ち、上記課題は、次の発明によって解決される。
次の要件（ａ）〜（ｅ）を満たすことを特徴とするジルコニア質微小メディア。
（ａ）９５容積％以上が正方晶系ジルコニアであり、単斜晶系ジルコニアの割合が３容積％以下であるＺｒＯ２−Ｙ２Ｏ３系ジルコニア質焼結体からなり、Ｙ２Ｏ３／ＺｒＯ２（モル比）＝２．５／９７．５〜３．２／９６．８
（ｂ）相対密度≧９５％
（ｃ）平均結晶粒径＝０．２５〜０．５０μｍ
（ｄ）圧壊荷重値Ｐ（Ｎ）≧１３４０×Ｄ２．０８〔Ｄは微小メディアの直径（ｍｍ）〕
（ｅ）表面粗さＲｙ≦０．３μｍ
As a result of intensive studies, the present invention is a zirconia sintered body in which Y 2 O 3 is contained in a specific ratio in a zirconia micro media, and a relative density, an average crystal grain size and a crushing load value are specified. The present invention finds that a zirconia micro media having excellent abrasion resistance and durability and a high dispersion efficiency can be obtained by setting the surface roughness of the micro media to a specific range. Was completed.
That is, the above problem is solved by the following invention.
A zirconia micro media characterized by satisfying the following requirements (a) to (e).
(A) 95% by volume or more of tetragonal zirconia and a monoclinic zirconia ratio of 3% by volume or less made of a ZrO 2 —Y 2 O 3 -based zirconia-based sintered body, Y 2 O 3 / ZrO 2 (molar ratio) = 2.5 / 97.5 to 3.2 / 96.8
(B) Relative density ≧ 95%
(C) Average crystal grain size = 0.25 to 0.50 μm
(D) Crushing load value P (N) ≧ 1340 × D 2.08 [D is the diameter of the minute media (mm)]
(E) Surface roughness Ry ≦ 0.3 μm
本発明によれば耐摩耗性及び耐久性に優れたジルコニア質微小メディアを提供できる。
該微小メディアは機械的特性に優れ、ビーズに高負荷が掛かるようなミルのビーズとして用いた場合でも割れやカケがなく、耐摩耗性及び耐久性に優れるため、長期間の使用でもビーズの摩耗量の変動が非常に少なく、ビーズの摩耗粉が被処理粉体中に不純物として混入することも極力抑制できる。したがって、粉砕・分散用に好適であり、電子部品を始めとする高機能な先端材料の粉体処理に最適である。また、分散効率も高く、結晶粒径が微細で、メディア表面が非常に滑らかなため、被分散粉体表面へのダメージを少なくすることができる。
ADVANTAGE OF THE INVENTION According to this invention, the zirconia-type micro media excellent in abrasion resistance and durability can be provided.
The micro media has excellent mechanical properties, and has no cracks or chips even when used as a bead of a mill in which a high load is applied to the beads, and has excellent wear resistance and durability. The fluctuation of the amount is very small, and it is possible to suppress the wear powder of the beads from being mixed as impurities into the powder to be treated. Therefore, it is suitable for pulverization and dispersion, and is most suitable for powder processing of advanced functional materials such as electronic components. In addition, the dispersion efficiency is high, the crystal grain size is fine, and the media surface is very smooth, so that damage to the surface of the powder to be dispersed can be reduced.
以下、上記要件（ａ）〜（ｅ）について詳しく説明する。
＜要件（ａ）について＞
本発明のジルコニア質微小メディアは９５容積％以上が正方晶系ジルコニアからなり、かつ、単斜晶系ジルコニアの割合が３容積％以下である。焼結体が単斜晶系ジルコニアを３容積％よりも多く含有しているとその結晶周辺に微細なクラックが生じ、応力が加えられるとこの微細なクラックを起点として微小破壊が起こり、摩擦、衝撃、圧壊等に対する抵抗性が低下する。また、焼結体が立方晶系ジルコニアを５容積％よりも多く含有していると、機械的特性の低下が起こるだけでなく、耐久性の低下をきたす。
Hereinafter, the requirements (a) to (e) will be described in detail.
<About requirement (a)>
In the zirconia-based micro media of the present invention, 95% by volume or more is made of tetragonal zirconia, and the ratio of monoclinic zirconia is 3% by volume or less. If the sintered body contains more than 3% by volume of monoclinic zirconia, fine cracks are generated around the crystal, and when stress is applied, microdestruction starts from the fine cracks, causing friction and Resistance to impact, crushing, etc. decreases. When the sintered body contains more than 5% by volume of cubic zirconia, not only the mechanical properties are lowered, but also the durability is lowered.
本発明では、ジルコニア結晶相中の単斜晶系ジルコニア（Ｍ）の存在の有無及び含有量、並びに正方晶系ジルコニア（Ｔ）及び立方晶系ジルコニア（Ｃ）の含有量をＸ線回折により求める。
即ち、微小メディアをメディア直径の１／３研削し、研削した面を鏡面にまで研磨し、Ｘ線回折により回折角２７〜３４度の範囲で測定し、単斜晶系ジルコニアの有無及び含有量を、下記の式から求める。
また、立方晶系ジルコニアの含有量は、前記単斜晶系ジルコニアの場合と同様にして、Ｘ線回折により回折角７０〜７７度の範囲で測定し、下記の式から求める。
更に、上記の結果に基づいて、正方晶系ジルコニアの含有量を下記の式から求める。
なお、Ｘ線回折条件は、Ｘ線源：ＣｕＫα、出力：４０ｋＶ／４０ｍＡ、発散スリット：１／２°、散乱スリット：１／２°、受光スリット：０．１５ｍｍ、スキャンスピード：０．５°／ｍｉｎ、走査軸：２θ／θ、モノクロ受光スリット：０．８ｍｍ、カウンタ：シンチレーションカウンタ、モノクロメーター：自動モノクロメーターで行う。
That is, the micro media is ground to 1/3 of the media diameter, the ground surface is polished to a mirror surface, and measured by X-ray diffraction in a diffraction angle range of 27 to 34 degrees, and the presence and content of monoclinic zirconia Is calculated from the following equation.
Further, the content of cubic zirconia is measured by X-ray diffraction in the range of a diffraction angle of 70 to 77 degrees in the same manner as in the case of the monoclinic zirconia, and is obtained from the following equation.
Further, based on the above results, the content of tetragonal zirconia is determined from the following equation.
The X-ray diffraction conditions are as follows: X-ray source: CuKα, output: 40 kV / 40 mA, divergence slit: 1/2 °, scattering slit: 1/2 °, light receiving slit: 0.15 mm, scan speed: 0.5 ° / Min, scanning axis: 2θ / θ, monochrome light receiving slit: 0.8 mm, counter: scintillation counter, monochrome meter: automatic monochrome meter.
前記ＺｒＯ２−Ｙ２Ｏ３系ジルコニア質焼結体のＹ２Ｏ３／ＺｒＯ２（モル比）は２．５／９７．５〜３．２／９６．８とし、好ましくは２．８／９７．２〜３．０／９７．０とする。なお、ＺｒＯ２原料は通常ＨｆＯ２を少量含有しているので、ＺｒＯ２とＨｆＯ２の合計量をＺｒＯ２量として取り扱う。
前記モル比が２．５／９７．５未満の場合には、焼結体に含まれる単斜晶系ジルコニアが多くなり、正方晶系ジルコニアの安定性が低くなるため、応力により焼結体内部にクラックが発生し、割れやカケの原因となり、耐摩耗性の低下や耐久性の低下をきたす。一方、前記モル比が３．２／９６．８を超えると正方晶系ジルコニア量が減少し、機械的特性の低下を招く。
The ZrO 2 -Y 2 O 3 -based zirconia-based sintered body has a Y 2 O 3 / ZrO 2 (molar ratio) of 2.5 / 97.5 to 3.2 / 96.8, preferably 2.8 /. 97.2 to 3.0 / 97.0. Since ZrO 2 raw material usually contains a small amount of HfO 2, handle the total amount of ZrO 2 and HfO 2 as ZrO 2 amount.
When the molar ratio is less than 2.5 / 97.5, the monoclinic zirconia contained in the sintered body increases, and the stability of the tetragonal zirconia decreases, so that the inside of the sintered body is stressed. Cracks are generated, causing cracks and chips, resulting in a decrease in wear resistance and durability. On the other hand, if the molar ratio exceeds 3.2 / 96.8, the amount of tetragonal zirconia decreases, leading to a decrease in mechanical properties.
＜要件（ｂ）について＞
本発明のジルコニア質微小メディアの相対密度は９５％以上、好ましくは９７％以上とする。相対密度が９５％未満の場合は欠陥となる気孔が多く存在し、強度、硬度の低下が起こり、その結果、耐摩耗性の低下や耐久性の低下が起こる。上限は９９％程度である。
<About requirement (b)>
The relative density of the zirconia micro media of the present invention is 95% or more, preferably 97% or more. When the relative density is less than 95%, there are many pores serving as defects, and strength and hardness are reduced, and as a result, wear resistance and durability are reduced. The upper limit is about 99%.
＜要件（ｃ）について＞
本発明のジルコニア質微小メディアの平均結晶粒径は０．２５〜０．５０μｍとし、好ましくは０．２８〜０．４０μｍとする。平均結晶粒径が０．２５μｍ未満では、メディアの靱性が低下し、ミル内で高負荷が加わった際にチッピングやカケが発生する。一方、０．５０μｍを超えると耐摩耗性の低下が起こる。
なお、ここでいう平均結晶粒径は、微小メディアをメディア直径の１／３研削し、研削した面を鏡面にまで研磨し、熱エッチング又は化学エッチングを施した後、走査型電子顕微鏡で観察してインターセプト法により１０点測定した平均値である。
算出式は次のとおりである。
平均結晶粒径（μｍ）＝１．５×Ｌ／ｎ
〔Ｌ：測定長さ（μｍ）、ｎ：長さＬ当たりの結晶粒子数〕
<About requirement (c)>
The average crystal grain size of the zirconia-based micro media of the present invention is 0.25 to 0.50 μm, preferably 0.28 to 0.40 μm. If the average crystal grain size is less than 0.25 μm, the toughness of the media is reduced, and chipping and chipping occur when a high load is applied in the mill. On the other hand, if it exceeds 0.50 μm, the abrasion resistance decreases.
In addition, the average crystal grain size referred to here is obtained by grinding a micro media to 1/3 of the media diameter, polishing the ground surface to a mirror surface, performing thermal etching or chemical etching, and then observing with a scanning electron microscope. Mean value measured at 10 points by the intercept method.
The calculation formula is as follows.
Average crystal grain size (μm) = 1.5 × L / n
[L: measured length (μm), n: number of crystal particles per length L]
＜要件（ｄ）について＞
本発明のジルコニア質微小メディアの圧壊荷重値は、次の式を満たすようにする。
圧壊荷重値Ｐ（Ｎ）≧１３４０×Ｄ２．０８〔Ｄは微小メディアの直径（ｍｍ）〕
圧壊荷重値が上記の式を満たさないと、ミル内で衝撃等による割れやカケが発生する危険性が高くなる。
また、後述する表面粗さに関する要件（ｅ）を満たしても、圧壊荷重値が要件（ｄ）を満たさないと、短時間使用での摩耗率は低いが、結晶粒子の結合が弱いため、長時間使用の際に微細な脱粒などが発生し、長時間安定した摩耗特性を維持できない。
なお、上記圧壊荷重値は、材料試験機を用いて２枚のダイヤモンド焼結体又はＢＮ焼結体にメディア１個を挟み、クロスヘッドスピード（板間の距離を縮める速度）０．５ｍｍ／ｍｉｎ又は１０３．７ｍＮ／ｓｅｃの速度でメディアに荷重を加え、破壊した時の荷重である。測定は１０個行い、その平均値を圧壊荷重値とする。また、上記式による圧壊荷重値は、式中のＤとしてメディア１０個の平均直径を用いて算出する。
<Requirements (d)>
The crushing load value of the zirconia-based micro media of the present invention is set to satisfy the following expression.
Crush load value P (N) ≧ 1340 × D 2.08 [D is the diameter of the minute media (mm)]
If the crushing load value does not satisfy the above formula, there is a high risk that cracks or chips are generated in the mill due to impact or the like.
If the crushing load value does not satisfy the requirement (d) even if the requirement (e) relating to the surface roughness described later is satisfied, the wear rate in short-time use is low, but the bonding of the crystal particles is weak. When used for a long time, fine shedding occurs, and stable wear characteristics cannot be maintained for a long time.
The crushing load value is determined by sandwiching one medium between two diamond sintered bodies or BN sintered bodies using a material testing machine and setting a crosshead speed (speed of reducing the distance between the plates) to 0.5 mm / min. Or it is a load when a load is applied to the medium at a speed of 103.7 mN / sec and the medium is broken. Ten measurements were made, and the average value was taken as the crush load value. The crushing load value according to the above equation is calculated using the average diameter of 10 media as D in the equation.
＜要件（ｅ）について＞
本発明のジルコニア質微小メディアの表面粗さ（Ｒｙ）は０．３μｍ以下、好ましくは０．２μｍ以下とする。
メディアの表面粗さは機械的特性だけでなく耐摩耗性にも大きく影響する。例えば、メディア材質としての特性が良好であっても表面粗さが悪ければ摩耗特性等のメディアとしての特性は低下する。表面粗さが０．３μｍを超えると、メディア表面の凹凸が大きくなり、メディア同士の摩擦が大きくなって摩耗が促進される。また、摩耗特性だけでなく、粉体の分散の繰り返しによりメディア表面状態が悪くなり、分散処理毎の摩耗率の変動が起こり、耐久性の低下をきたす。更に、被処理粉体の分散が進みにくく、本発明のビーズに比べて、同条件で分散しても分散した粉体の平均粒子径分布が広くなったり、平均粒子径が大きくなったりする。
なお、メディアの表面粗さは、ＪＩＳ Ｂ ０６０１（２００１）に準拠して、レーザー顕微鏡を用いて非接触で５個のビーズについて測定し、その平均値とする。
<About requirement (e)>
The surface roughness (Ry) of the zirconia micro media of the present invention is 0.3 μm or less, preferably 0.2 μm or less.
The surface roughness of the media greatly affects not only mechanical properties but also abrasion resistance. For example, even if the characteristics of the medium are good, if the surface roughness is poor, the characteristics of the medium such as abrasion characteristics are deteriorated. If the surface roughness exceeds 0.3 μm, the unevenness of the media surface becomes large, the friction between the media becomes large, and the wear is promoted. Further, not only the wear characteristics but also the repetition of powder dispersion deteriorates the surface condition of the media, causing a change in the wear rate for each dispersion treatment, resulting in a decrease in durability. Further, the dispersion of the powder to be treated is difficult to progress, and even when dispersed under the same conditions, the average particle size distribution of the dispersed powder becomes wider or the average particle diameter becomes larger as compared with the beads of the present invention.
The surface roughness of the medium is measured for five beads in a non-contact manner using a laser microscope in accordance with JIS B 0601 (2001), and the average value is obtained.
本発明のジルコニア質微小メディアは種々の方法によって製造することができる。
一例を挙げると、ＺｒＯ２とＹ２Ｏ３の含有量が所定のモル比になるようにジルコニア化合物（例えばオキシ塩化ジルコニウム）の水溶液とイットリア化合物（例えば硝酸イットリウム）の水溶液を均一に混合し、加水分解し、水和物を得、脱水、乾燥させた後、４００〜１２５０℃で仮焼し、ジルコニア粉体を作製する。得られた仮焼粉体を湿式で粉砕・分散し乾燥させて成形粉体を得る。なお、成形粉体の平均粒子径は０．３〜０．６μｍ、比表面積は５〜１０ｍ２／ｇであることが好ましい。平均粒子径が上記範囲を外れると、焼結体内部に欠陥が多く発生し、焼結体特性の低下をきたすので好ましくない。
本発明のジルコニア質微小メディアは、上記液相法により作製した成形粉体を用いて造粒成形し焼成することが、優れた高耐摩耗性及び長期安定性を実現するために必要不可欠である。即ち、成形粉体を用い、有機溶媒、水、可溶性高分子などを成形助剤として造粒成形し、得られた成形体を１２５０〜１５５０℃程度で焼成し、更にバレル研磨により所定の表面粗さまで研磨・仕上げをして微小メディアを得る。
The zirconia micro media of the present invention can be produced by various methods.
As an example, an aqueous solution of a zirconia compound (for example, zirconium oxychloride) and an aqueous solution of an yttria compound (for example, yttrium nitrate) are uniformly mixed such that the contents of ZrO 2 and Y 2 O 3 become a predetermined molar ratio. After hydrolysis, a hydrate is obtained, dehydrated and dried, and calcined at 400 to 1250 ° C. to produce a zirconia powder. The obtained calcined powder is pulverized and dispersed by a wet method and dried to obtain a molded powder. The average particle diameter of the molded powder is preferably 0.3 to 0.6 μm, and the specific surface area is preferably 5 to 10 m 2 / g. If the average particle diameter is out of the above range, many defects are generated inside the sintered body, and the characteristics of the sintered body are deteriorated, which is not preferable.
The zirconia-based micro media of the present invention is indispensable for granulating and firing using the molding powder produced by the above liquid phase method and realizing excellent high wear resistance and long-term stability. . That is, using a molding powder, an organic solvent, water, a soluble polymer or the like is granulated and formed using a molding aid, and the obtained molded body is fired at about 1250 to 1550 ° C., and further, barrel polishing is performed to obtain a predetermined surface roughness. Polish and finish to obtain fine media.
以下、実施例及び比較例を挙げて本発明を更に具体的に説明するが、本発明はこれらの実施例により何ら限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
実施例１〜８、比較例１〜８
純度９９．６％のオキシ塩化ジルコニウムと純度９９．９％の硝酸イットリウムを表１の実施例１〜８及び比較例１〜８の各欄に示すＹ２Ｏ３／ＺｒＯ２（モル比）となるように水と混合して水溶液を得た。次いで、加熱環流下で加水分解し、得られた水和ジルコニウムの沈殿物を脱水、乾燥し、１２００℃で１時間仮焼し、湿式分散させ、乾燥、整粒して、平均粒子径が０．３〜０．５μｍ、比表面積が６〜９ｍ２／ｇのジルコニア粉体（成形用粉体）を得た。
なお、比較例２の仮焼は１０００℃で行い、平均粒子径が０．２μｍ、比表面積が１２ｍ２／ｇの成形用粉体を得た。
上記各成形用粉体を用いて造粒成形し、１２００〜１６００℃で焼成して直径５０μｍの微小メディア素材を得、これをバレル研磨して各評価用微小メディアを作製した。
Examples 1 to 8, Comparative Examples 1 to 8
Zirconium oxychloride having a purity of 99.6% and yttrium nitrate having a purity of 99.9% were mixed with Y 2 O 3 / ZrO 2 (molar ratio) shown in each column of Examples 1 to 8 and Comparative Examples 1 to 8 in Table 1. The resulting mixture was mixed with water to obtain an aqueous solution. Next, the precipitate was hydrolyzed under reflux with heating, and the obtained precipitate of hydrated zirconium was dehydrated, dried, calcined at 1200 ° C. for 1 hour, wet-dispersed, dried and sized to obtain an average particle diameter of 0%. A zirconia powder (molding powder) having a thickness of 0.3 to 0.5 μm and a specific surface area of 6 to 9 m 2 / g was obtained.
The calcining of Comparative Example 2 was performed at 1000 ° C. to obtain a molding powder having an average particle diameter of 0.2 μm and a specific surface area of 12 m 2 / g.
Each of the above molding powders was granulated and fired at 1200 to 1600 ° C. to obtain a fine media material having a diameter of 50 μm, and this was barrel-polished to produce each fine media for evaluation.
各評価用微小メディアの結晶相の割合（容量％）を、前述した方法により求めた結果について表１に示す。
また、各評価用微小メディアの物性を以下のようにして測定した。結果を表１に示す。
＜圧壊荷重値Ｐ（Ｎ）＞
島津製作所製微小圧縮試験器：ＭＣＴ−Ｗ５００を用い、加圧板にダイヤモンド焼結体を用いて、１個のビーズに負荷速度＝１０３．７ｍＮ／ｓｅｃで荷重を加え破壊した時の応力を測定し、１０個のビーズの破壊応力の平均値を圧壊荷重値Ｐ（Ｎ）とした。
＜表面粗さＲｙ＞
キーエンス社製レーザー顕微鏡：ＶＫ−９５００を用い、５０倍レンズにより、ピッチ＝０．０１ｍｍ、測定長さ＝１０μｍで、ＪＩＳ Ｂ ０６０１（２００１）に準拠して５個測定し、その平均値を表面粗さＲｙとした。
＜摩耗率＞
寿工業社製のミル：ウルトラアペックスミルＵＡＭ−０５を用い、ミル部材のベッセルにニッカトー社製サイアロン、ロータにニッカトー社製ＹＴＺを用い、メディア充填量をミル容積の７０％、ロータ周速を１０ｍ／ｓとした。テスト条件は、水流量：３００ｍＬ／ｍｉｎ、水循環量：５Ｌ、水温度：５℃で１００時間とした。
摩耗率は、循環水をＩＣＰ分析（高周波誘導結合プラズマ発光分光分析法）し摩耗粉として循環水に含まれているジルコニア量を分析して算出した。
表１の結果から、本発明のジルコニア質微小メディアは長時間の稼働でも摩耗率が低く、耐久性に優れていることが分かる。
Table 1 shows the results of the ratio (volume%) of the crystal phase of each micro media for evaluation obtained by the method described above.
In addition, the physical properties of each evaluation micro media were measured as follows. Table 1 shows the results.
<Crush load value P (N)>
Micro compression tester manufactured by Shimadzu: MCT-W500, using a diamond sintered body as a pressure plate, applying a load to one bead at a load speed of 103.7 mN / sec and measuring the stress when breaking. The average value of the breaking stress of the ten beads was defined as the crushing load value P (N).
<Surface roughness Ry>
Using a laser microscope manufactured by KEYENCE CORPORATION: VK-9500, five samples were measured with a 50 × lens at a pitch of 0.01 mm and a measurement length of 10 μm in accordance with JIS B 0601 (2001), and the average value was measured for the surface. The roughness was defined as Ry.
<Wear rate>
Kotobuki Kogyo Mill: Ultra Apex Mill UAM-05, Nikkato Sialon for the mill material vessel, Nikkato YTZ for the rotor, 70% of the mill volume of the media volume and 10 m for the rotor peripheral speed / S. The test conditions were as follows: water flow rate: 300 mL / min, water circulation amount: 5 L, water temperature: 5 ° C. for 100 hours.
The wear rate was calculated by ICP analysis (high frequency inductively coupled plasma emission spectroscopy) of the circulating water and analyzing the amount of zirconia contained in the circulating water as wear powder.
From the results shown in Table 1, it can be seen that the zirconia-based fine media of the present invention has a low wear rate and excellent durability even when operated for a long time.
実施例９、比較例９
実施例６及び比較例５のメディアを用いて、酸化チタン粉体の分散テストを行った。
被分散粉体として、一次粒子径：３５ｎｍ、比表面積：３１．２ｍ２／ｇの酸化チタン（ルチル）を用い、スラリー濃度：１０％、スラリー流量：３００ｍＬ／ｍｉｎで３時間分散した後、酸化チタン粉体中に含まれるメディアの摩耗粉であるジルコニア量を測定した。
その結果、実施例６のメディアでは５３ｐｐｍ、比較例５のメディアでは９１ｐｐｍであり、実施例６の方が耐摩耗性に優れていた。
また、図１に分散テスト後の酸化チタン粉体の粒度分布を示すが、全く同じ分散条件において、比較例５のメディアに比べて実施例６のメディアの方が一次粒子径に近いレベルまで分散できていた。（なお、分散前の粉体は凝集しているため平均粒子径が大きい値を示している。）
Example 9 and Comparative Example 9
Using the media of Example 6 and Comparative Example 5, a dispersion test of the titanium oxide powder was performed.
As the powder to be dispersed, titanium oxide (rutile) having a primary particle diameter of 35 nm and a specific surface area of 31.2 m 2 / g was used. The slurry was dispersed at a slurry concentration of 10% and a slurry flow rate of 300 mL / min for 3 hours. The amount of zirconia, which is the wear powder of the media contained in the titanium powder, was measured.
As a result, the medium of Example 6 had 53 ppm, and the medium of Comparative Example 5 had 91 ppm. Thus, Example 6 was superior in abrasion resistance.
FIG. 1 shows the particle size distribution of the titanium oxide powder after the dispersion test. Under exactly the same dispersion conditions, the medium of Example 6 was dispersed to a level closer to the primary particle diameter as compared with the medium of Comparative Example 5. It was done. (Because the powder before dispersion is agglomerated, the average particle diameter shows a large value.)
Claims (1)
（ａ）９５容積％以上が正方晶系ジルコニアであり、単斜晶系ジルコニアの割合が３容積％以下であるＺｒＯ２−Ｙ２Ｏ３系ジルコニア質焼結体からなり、Ｙ２Ｏ３／ＺｒＯ２（モル比）＝２．５／９７．５〜３．２／９６．８
（ｂ）相対密度≧９５％
（ｃ）平均結晶粒径＝０．２５〜０．５０μｍ
（ｄ）圧壊荷重値Ｐ（Ｎ）≧１３４０×Ｄ２．０８〔Ｄは微小メディアの直径（ｍｍ）〕
（ｅ）表面粗さＲｙ≦０．３μｍ A zirconia micro media characterized by satisfying the following requirements (a) to (e).
(A) 95% by volume or more of tetragonal zirconia and a monoclinic zirconia ratio of 3% by volume or less made of a ZrO 2 —Y 2 O 3 -based zirconia-based sintered body, Y 2 O 3 / ZrO 2 (molar ratio) = 2.5 / 97.5 to 3.2 / 96.8
(B) Relative density ≧ 95%
(C) Average crystal grain size = 0.25 to 0.50 μm
(D) Crushing load value P (N) ≧ 1340 × D 2.08 [D is the diameter of the minute media (mm)]
(E) Surface roughness Ry ≦ 0.3 μm
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