WO2022044983A1 - Ceramic spheres - Google Patents

Abstract

Ceramic spheres that include zirconia as a primary component and are 80–95 volume% tetragonal crystals and no more than 5 volume% monoclinic crystals, the ceramic spheres being characterized in that, when average particle diameter is X (μm), the maximum height of waviness Wz (μm) of the line of intersection between a cross-section and the surface of spheres that have a diameter of X/2 (μm) is 0.5%–1.2% of the average particle diameter X (μm).　The present invention provides ceramic spheres that can be used as a medium, such as balls or beads, that is for use in a grinder and do not readily break, even when grinding and dispersion are performed at normal temperature and a high water temperature.

Description

Translated fromJapanese

セラミックス球形体Ceramic sphere

　本発明は、セラミックス球形体に関する。The present invention relates to a ceramic sphere.

　電子材料用途で使用される粉末の微粉砕やインク用途における顔料の分散時に、粉砕用メディアを用いて粉砕するボールミル、振動ミル、サンドミル、ビーズミル等の粉砕機が広く使用されている。こうした粉砕機用に用いられる、ボール、ビーズ等の粉砕用メディア（以下、単に「メディア」という場合がある）として、耐摩耗性、耐衝撃性の面で優れるジルコニアを主成分とするセラミックス焼結体が使用されている。Crushers such as ball mills, vibration mills, sand mills, and bead mills that grind using a crushing medium when finely pulverizing powders used in electronic materials and dispersing pigments in ink applications are widely used. Ceramic sintering containing zirconia as a main component, which is excellent in wear resistance and impact resistance, as a medium for crushing balls, beads, etc. (hereinafter, may be simply referred to as "media") used for such a crusher. The body is being used.

　ジルコニアを主成分とするセラミックス焼結体としては、ＺｒＯ_２とＹ_２Ｏ_３の組成比率を限定し、Ａｌ_２Ｏ_３量およびＳｉＯ_２量を制御することで、耐久性および耐摩耗性を向上したとするメディアが開示されている（例えば特許文献１）。As a ceramic sintered body containing zirconia as a main component, durability and wear resistance are improved by limiting the composition ratio of ZrO₂ and Y₂ O₃ and controlling the amount of Al₂ O₃ and SiO₂ . The media in which it is said to have been disclosed (for example, Patent Document 1).

特開２００１－３１６１７８号公報Japanese Unexamined Patent Publication No. 2001-316178

　近年は特に被粉砕物の性能向上を目的として粒子の微細化が一層求められており、それに伴い、３００μｍ以下の粉砕用微小径メディアの利用が拡大している。微小径メディアは、転動造粒成形法、液中造粒成形法、プラズマ溶融成形法などにより製造されることが一般的であるが、いずれの造粒方法においても成形過程における粒の成長履歴、熱履歴、表面張力などの影響によりメディア表面にうねり形状が存在する。In recent years, there has been a demand for further miniaturization of particles especially for the purpose of improving the performance of the object to be crushed, and along with this, the use of pulverizing microdiameter media of 300 μm or less is expanding. The micro-diameter media is generally manufactured by a rolling granulation molding method, an in-liquid granulation molding method, a plasma melt molding method, etc., but in any of the granulation methods, the growth history of grains in the molding process , There is a wavy shape on the surface of the media due to the influence of thermal history, surface tension, etc.

　このようなメディア表面のうねりは局所的に曲率半径が小さい箇所である。本発明者らが検討した結果、メディア同士、メディアと被粉砕物およびメディアと装置壁面との衝突の際、メディア表面のうねり箇所では接触面積が小さく、高い圧力が印加される結果、メディアの破損が生じやすい要因となっていることがわかった。特に、水中に被粉砕物およびメディアを粉砕機等に混合して粉砕・分散を長時間行った場合、水温が高くなり、セラミックス焼結体の劣化が進み、破損が起きやすかった。Such undulations on the surface of the media are locally small radius of curvature. As a result of the study by the present inventors, when the media collide with each other, the media with the object to be crushed, and the media with the wall surface of the device, the contact area is small at the wavy portion on the surface of the media, and as a result of high pressure being applied, the media is damaged. It was found that this is a factor that tends to occur. In particular, when the object to be crushed and the media were mixed in water with a crusher or the like and crushed / dispersed for a long time, the water temperature became high, the ceramic sintered body deteriorated, and damage was liable to occur.

　本発明は、粉砕機に用いられるボール、ビーズ等のメディアとして用いることが可能で、常温の状態および水温が高い状態で粉砕・分散を行っても破損が生じにくいセラミックス球形体を提供することを目的とする。The present invention provides a ceramic sphere that can be used as a medium for balls, beads, etc. used in a crusher and is less likely to be damaged even if crushed and dispersed at room temperature and high water temperature. The purpose.

　すなわち、上記課題を解決するための本発明は、ジルコニアを主成分とし、正方晶の割合が８０容量％以上９５容量％以下、単斜晶の割合が５容量％以下であるセラミックス球形体であって、平均粒径をＸ（μｍ）とした時に直径がＸ／２（μｍ）となるような該球形体の断面と該球形体の表面との交線部における最大高さうねりＷｚ（μｍ）が、平均粒径Ｘ（μｍ）の０．５％以上１．２％以下であることを特徴とするセラミックス球形体である。That is, the present invention for solving the above-mentioned problems is a ceramic sphere containing zirconia as a main component, having a square crystal ratio of 80% by volume or more and 95% by volume or less, and a monoclinic crystal ratio of 5% by volume or less. The maximum height swell Wz (μm) at the intersection of the cross section of the sphere and the surface of the sphere so that the diameter becomes X / 2 (μm) when the average particle size is X (μm). Is a ceramic sphere characterized by having an average particle size X (μm) of 0.5% or more and 1.2% or less.

　本発明のセラミックス球形体は、これを用いて常温の状態および水温が高い状態で被粉砕物の粉砕・分散を行ってもセラミックス球形体の破損が抑制されるという効果を奏する。The ceramic sphere of the present invention has the effect of suppressing damage to the ceramic sphere even when the object to be crushed is crushed and dispersed at room temperature and at a high water temperature.

本発明のセラミックス球形体における最大高さうねりＷｚの測定箇所、測定方向、および実際に測定したうねりプロファイル例を示した図である。図中のｚ軸方向の最大高さうねりを測定しており、ｘ軸、ｙ軸はそれに直交する平面を示している。It is a figure which showed the measurement point of the maximum height swell Wz in the ceramic sphere of this invention, the measurement direction, and the swell profile example actually measured. The maximum height swell in the z-axis direction in the figure is measured, and the x-axis and y-axis indicate planes orthogonal to it.

　本発明のセラミックス球形体は、ジルコニアを主成分とするセラミックス焼結体からなる。なお、以下本明細書においては、最終製品としてのセラミック焼結体、すなわち粉砕用メディア以外の、製造工程において一度以上の焼結を経て得られる中間体としてのセラミックス焼結体を総称して「中間焼結体」と呼称する。また、最終製品としてのセラミックス焼結体および中間焼結体の両者を総称して単に「焼結体」と呼称する。The ceramic spherical body of the present invention is made of a ceramic sintered body containing zirconia as a main component. Hereinafter, in the present specification, ceramic sintered bodies as final products, that is, ceramic sintered bodies as intermediates obtained through one or more sinterings in a manufacturing process other than crushing media, are collectively referred to as "ceramic sintered bodies". It is called "intermediate sintered body". Further, both the ceramic sintered body and the intermediate sintered body as the final product are collectively referred to simply as "sintered body".

　本発明のセラミックス球形体は、ジルコニアを主成分とするセラミック原料粉末（以下、単に「原料粉末」という場合がある）を球状に成形することで得られる。ここで、本明細書においてジルコニアを主成分とする、とは、ジルコニアの比率が９０重量％以上であることを意味するが、ジルコニアの比率が全成分の９３重量％以上であれば、特に高い強度を得ることができるため好ましい。The ceramic spherical body of the present invention is obtained by forming a ceramic raw material powder containing zirconia as a main component (hereinafter, may be simply referred to as "raw material powder") into a spherical shape. Here, the fact that zirconia is the main component in the present specification means that the ratio of zirconia is 90% by weight or more, but it is particularly high if the ratio of zirconia is 93% by weight or more of all the components. It is preferable because strength can be obtained.

　セラミックスにおける各成分の含有量は次のようにして求めることができる。まず、セラミックスの試料を、万能試験機を用いて圧壊し、圧壊片約０．３ｇを白金るつぼに入れ、硫酸水素カリウムで融解する。これを希硝酸で溶解して定溶し、ＩＣＰ発光分光分析法を用いて各金属元素を定量し、さらにそれを酸化物に換算して含有量を求める。以下、本発明のセラミックス球形体における成分を金属元素で表記することもあれば、酸化物で表記することもある。The content of each component in ceramics can be determined as follows. First, a ceramic sample is crushed using a universal testing machine, and about 0.3 g of crushed pieces are placed in a platinum crucible and melted with potassium hydrogensulfate. This is dissolved in dilute nitric acid to a constant solution, each metal element is quantified using ICP emission spectroscopy, and the content is determined by converting it into an oxide. Hereinafter, the components in the ceramic sphere of the present invention may be represented by metal elements or oxides.

　また、本発明のセラミックス球形体は、上記のような主成分以外に、酸化物換算でイットリア（Ｙ_２Ｏ_３）、セリア（ＣｅＯ_２）、アルミナ（Ａｌ_２Ｏ_３）、マグネシア（ＭｇＯ）、カルシア（ＣａＯ）等を含むことが好ましい。これらは安定化剤として機能し、セラミックス球形体の強度、靭性を向上させることができる。中でもイットリアを含有することが好ましい。イットリアの含有量は、セラミックス球形体におけるイットリア／ジルコニアのモル比で４．６／９５．４以上５．６／９４．４以下が好ましく、より好ましくは４．８／９５．２以上５．５／９４．５以下である。In addition to the main components as described above, the ceramic sphere of the present invention has yttrium (Y₂ O₃ ), ceria (CeO₂ ), alumina (Al₂ O₃ ), magnesia (MgO), etc. in terms of oxides. It is preferable to include calcia (CaO) and the like. These function as stabilizers and can improve the strength and toughness of the ceramic sphere. Above all, it is preferable to contain itria. The yttria content is preferably 4.6 / 95.4 or more and 5.6 / 94.4 or less, more preferably 4.8 / 95.2 or more and 5.5, in terms of the molar ratio of yttria / zirconia in the ceramic sphere. It is less than / 94.5.

　本発明のセラミックス球形体は正方晶の割合が８０容量％以上９５容量％以下、単斜晶の割合が５容量％以下である。正方晶の含有量が８０容量％以上であると、応力が印加された時に正方晶が単斜晶に変異して体積膨張し、メディアの亀裂を抑制することができるが、８０容量％未満だとその効果が小さくなる場合がある。一方、正方晶の含有量が９５容量％より大きいと、高温の水中において劣化が生じやすいため、粉砕・分散を長時間行う等して水温が上昇した場合に、セラミックス球形体が破損しやすくなる場合がある。また、破損防止の点から単斜晶の割合は少なければ少ないほど良く、５容量％以下である。好ましくは３容量％以下、より好ましくは１容量％以下である。しかしながら、セラミックス球形体の製造工程において、表面形状を平滑にするために後述の通り湿式研磨や後洗浄を行うことが一般的であり、湿式研磨時の水温上昇や研磨後の洗浄、乾燥する過程において、単斜晶が少なくとも０．１％以上は形成されることから、完全なゼロにはならないことが一般的である。セラミックス球形体の各結晶相の割合は、粉末Ｘ線回折法により測定することができる。The ceramic sphere of the present invention has a tetragonal ratio of 80% by volume or more and 95% by volume or less, and a monoclinic crystal ratio of 5% by volume or less. When the content of the tetragonal crystal is 80% by volume or more, the tetragonal crystal mutates into a monoclinic crystal and expands in volume when stress is applied, and cracks in the media can be suppressed, but it is less than 80% by volume. And the effect may be small. On the other hand, if the content of tetragonal crystals is larger than 95% by volume, deterioration is likely to occur in high-temperature water, so that the ceramic spheres are likely to be damaged when the water temperature rises due to long-term pulverization / dispersion. In some cases. Further, from the viewpoint of preventing damage, the smaller the proportion of monoclinic crystals, the better, and it is 5% by volume or less. It is preferably 3% by volume or less, more preferably 1% by volume or less. However, in the process of manufacturing a ceramic spherical body, it is common to perform wet polishing and post-cleaning as described later in order to smooth the surface shape, and the process of raising the water temperature during wet polishing and cleaning and drying after polishing. In, since at least 0.1% or more of monoclinic crystals are formed, it is generally not completely zero. The ratio of each crystal phase of the ceramic spherical body can be measured by the powder X-ray diffraction method.

　本発明のセラミックス球形体は、平均粒径をＸ（μｍ）とした時に直径がＸ／２（μｍ）となるような該球形体の断面と該球形体の表面との交線部における最大高さうねりＷｚ（μｍ）が、平均粒径Ｘ（μｍ）の０．５％以上１．２％以下、すなわち、（Ｗｚ／Ｘ）×１００が０．５以上１．２以下である。一般に最大高さうねりは粒子の粒径に応じて大きくなるので、本発明では最大高さうねりを平均粒径で除した値を評価する。（Ｗｚ／Ｘ）×１００が１．２より大きいと、粉砕中のセラミックス球形体同士またはセラミックス球形体と被粉砕物等との衝突において、セラミックス球形体に局所的な圧力集中が生じる結果、破損が生じやすくなる。（Ｗｚ／Ｘ）×１００は１．０以下がより好ましい。また、（Ｗｚ／Ｘ）×１００が０．５より小さいと、工業製品としての生産性に乏しい。The ceramic sphere of the present invention has a maximum height at the intersection of the cross section of the sphere and the surface of the sphere so that the diameter becomes X / 2 (μm) when the average particle size is X (μm). The swell Wz (μm) is 0.5% or more and 1.2% or less of the average particle size X (μm), that is, (Wz / X) × 100 is 0.5 or more and 1.2 or less. In general, the maximum height swell increases according to the particle size of the particles. Therefore, in the present invention, the value obtained by dividing the maximum height swell by the average particle size is evaluated. When (Wz / X) × 100 is larger than 1.2, the ceramic spheres are damaged as a result of local pressure concentration on the ceramic spheres in the collision between the ceramic spheres during crushing or between the ceramic spheres and the object to be crushed. Is likely to occur. (Wz / X) × 100 is more preferably 1.0 or less. Further, when (Wz / X) × 100 is smaller than 0.5, the productivity as an industrial product is poor.

　ここで、平均粒径Ｘはセラミックス球形体を撮影した後、画像解析・計測ソフトを用いて測定することができる。具体的には以下のようにして測定される値である。セラミックス球形体の集合体をデジタルマイクロスコープで倍率１０～２００倍で撮影する。画像解析・計測ソフトを用いて、測定用画像の明度を基準として撮影画像を２値化する。２値化画像を最小二乗平均により円型図形分離し、分離したそれぞれの円の直径を個々のセラミックス球形体の直径として算出する。１０００個のセラミックス球形体の直径の数平均値を平均粒径Ｘとする。Here, the average particle size X can be measured by using image analysis / measurement software after photographing the ceramic sphere. Specifically, it is a value measured as follows. An aggregate of ceramic spheres is photographed with a digital microscope at a magnification of 10 to 200 times. Using image analysis / measurement software, the captured image is binarized based on the brightness of the measurement image. The binarized image is separated into circular figures by the minimum squared average, and the diameter of each separated circle is calculated as the diameter of each ceramic sphere. The average value of the diameters of 1000 ceramic spheres is defined as the average particle size X.

　また、「最大高さうねりＷｚ」はＪＩＳ　Ｂ　０６０１：２０１３に基づき、図１に示す通り、セラミックス球形体の直径１よりも小さい、Ｘ／２の直径２となるような該球形体の断面と該球形体の表面との交線部３について、上方４からセラミックス球形体をレーザー顕微鏡で観察して求めることができる。最大高さうねりＷｚを小さくする方法としては、例えば、後述する転動造粒機内で水のみを添加しながら長時間の転動を行うことが挙げられる。Further, the "maximum height swell Wz" is based on JIS B 0601: 2013, and as shown in FIG. 1, the cross section of the sphere having an X / 2diameter 2 which is smaller than thediameter 1 of the ceramic sphere. The line ofintersection 3 with the surface of the sphere can be determined by observing the ceramic sphere from above 4 with a laser microscope. As a method for reducing the maximum height swell Wz, for example, rolling for a long time while adding only water in a rolling granulator described later can be mentioned.

　本発明のセラミックス球形体の内部欠陥率は０．５％以下が好ましい。ここで「内部欠陥」とは、セラミックス球形体内部における割れや空孔をいう。内部欠陥はセラミックス球形体を研削し、内部欠陥率が０．５％以下であることにより、セラミックス球形体の破損をより抑制することができる。内部欠陥率を０．５％以下とする方法としては、例えば、得られたセラミックス球形体に後述する熱間等方圧加圧処理を施す、後述する成形体の表面うねり低減工程を行うなどが挙げられる。The internal defect rate of the ceramic sphere of the present invention is preferably 0.5% or less. Here, the "internal defect" means a crack or a hole inside the ceramic sphere. For internal defects, the ceramic sphere is ground, and the internal defect rate is 0.5% or less, so that damage to the ceramic sphere can be further suppressed. As a method for reducing the internal defect rate to 0.5% or less, for example, the obtained ceramic spherical body is subjected to a hot isotropic pressure pressure treatment described later, or a surface waviness reduction step of the molded body described later is performed. Can be mentioned.

　本発明のセラミックス球形体は、平均粒径Ｘが３０μｍ以上３００μｍ以下であることが好ましい。平均粒径Ｘが３０μｍ以上であることにより、被粉砕物とセラミックス球形体の分離が容易となり、セラミックス球形体の混入を防ぐことができる。平均粒径Ｘが３００μｍ以下であることにより、被粉砕物を均一かつ微小に粉砕・分散することができる。平均粒径Ｘは後述する篩式分級などにより上記範囲とすることができる。The ceramic sphere of the present invention preferably has an average particle size X of 30 μm or more and 300 μm or less. When the average particle size X is 30 μm or more, the object to be crushed and the ceramic sphere can be easily separated, and the ceramic sphere can be prevented from being mixed. When the average particle size X is 300 μm or less, the object to be crushed can be uniformly and finely pulverized and dispersed. The average particle size X can be set in the above range by a sieve type classification described later.

　本発明のセラミックス球形体は、最小粒径が０．７Ｘ（μｍ）以上であり、最大粒径が１．３Ｘ（μｍ）以下であることが好ましい。最小粒径が０．７Ｘ以上であることにより、被粉砕物とセラミックス球形体の分離が容易となり、セラミックス球形体の混入を防ぐことができる。また、最大粒径が１．３Ｘ（μｍ）以下であることにより、粉砕後の被粉砕物を均一な粒度分布とすることができる。最小粒径および最大粒径は、前述の平均粒径Ｘの測定と同様にして画像解析・計測ソフトを用い、円型図形分離したそれぞれの円の直径の最小値を最小粒径、最大値を最大粒径とすることで測定することができる。最小粒径および最大粒径は後述する篩式分級などにより上記範囲とすることができる。The ceramic sphere of the present invention preferably has a minimum particle size of 0.7X (μm) or more and a maximum particle size of 1.3X (μm) or less. When the minimum particle size is 0.7X or more, the object to be crushed and the ceramic sphere can be easily separated, and the ceramic sphere can be prevented from being mixed. Further, when the maximum particle size is 1.3 X (μm) or less, the object to be pulverized can have a uniform particle size distribution. For the minimum particle size and the maximum particle size, use image analysis / measurement software in the same way as the above-mentioned measurement of the average particle size X, and set the minimum value and maximum value of the diameter of each circle separated into circular figures to the minimum particle size. It can be measured by setting the maximum particle size. The minimum particle size and the maximum particle size can be set in the above range by a sieve type classification described later.

　なお、セラミックス球形体の製造過程における不均一性に起因して、全ての粒子を球形状にすることは難しく、真球性の悪い粒子が１～数％ほど存在するケースが一般的である。特に、楕円形状の物は、円相当径よりも小さい開口幅の分級網を楕円短軸で通過してくる可能性や、逆に円相当径よりも大きい開口幅の分級網を楕円長軸で捕捉される可能性があり、セラミックス球形体の粒度分布の外側に外れ値として存在する可能性がある。そのため、抜き取りでの粒径評価で上記のような特殊形状の粒子の影響を排除できるよう、最小粒径や最大粒径ではなく、１％粒径（Ｄ１）、９９％粒径（Ｄ９９）で定義するほうがセラミックス球形体の粒径範囲をより正しく把握する上で好ましい。したがって、本発明におけるセラミックス球形体は、Ｄ１が０．７Ｘ（μｍ）以上であり、Ｄ９９が１．３Ｘ（μｍ）以下であることが好ましい。Ｄ１、Ｄ９９は最小粒径、最大粒径と同様の手法で評価可能である。It is difficult to make all the particles spherical due to the non-uniformity in the manufacturing process of the ceramic sphere, and it is common that 1 to several% of the particles have poor sphericity. In particular, an elliptical object may pass through a classification net with an opening width smaller than the equivalent circle diameter on the elliptical minor axis, and conversely, a classification net with an opening width larger than the equivalent circle diameter on the elliptical major axis. It may be captured and may be present as an outlier outside the particle size distribution of the ceramic sphere. Therefore, in order to eliminate the influence of the above-mentioned specially shaped particles in the particle size evaluation by sampling, 1% particle size (D1) and 99% particle size (D99) are used instead of the minimum and maximum particle sizes. It is preferable to define it in order to more accurately grasp the particle size range of the ceramic sphere. Therefore, in the ceramic spherical body in the present invention, it is preferable that D1 is 0.7X (μm) or more and D99 is 1.3X (μm) or less. D1 and D99 can be evaluated by the same method as the minimum particle size and the maximum particle size.

　本発明のセラミックス球形体は種々の方法で製造することができる。以下、一例として、転動造粒成形法により製造した例の詳細を説明する。The ceramic sphere of the present invention can be manufactured by various methods. Hereinafter, as an example, details of an example manufactured by the rolling granulation molding method will be described.

　原料粉末はまず、転動造粒成形法を用いて球状に成形される。転動造粒成形法は、回転しているドラム内に、セラミックス原料粉末と、結合剤および水分を含む液体バインダーとを交互に添加することによって球状の微粒を形成し、その後、回転の連動を微粒及び粉末に与えることで粒を成長させ、球状の成形体を作製する方法である。The raw material powder is first formed into a spherical shape using a rolling granulation molding method. In the rolling granulation molding method, spherical fine particles are formed by alternately adding ceramic raw material powder and a liquid binder containing a binder and water in a rotating drum, and then the rotation is interlocked. It is a method of producing a spherical molded body by growing particles by giving them to fine particles and powder.

　次に、得られた成形体の表面うねり低減工程として、少なくとも重量１００ｋｇ以上の成形体を転動造粒機内で水のみを添加しながら少なくとも１０時間以上、好ましくは約２０時間、より好ましくは３０時間以上、更に転動を行う。これにより、成形体表面が平坦化し、表面うねりが小さくなる。この工程中の転動造粒機中の水分率は造粒成長時よりも２～５％高めに設定することが望ましい。これによりセラミックス球形体の表層が水分を多く含む状態とすることで、転動圧力を受けた際の粒子移動（可塑性変形）が容易になる結果、凸部分が平坦化し、最大高さうねりＷｚの小さい平滑なセラミックス球形体を得ることができる。尚、水分過剰で粒子同士の凝集が生じないよう、経過時間毎に転動造粒中の粒子の加湿状態を把握するための外観目視観察や、サンプルを少量抜き取って行う粒子状態の顕微鏡観察、あるいは水分率やかさ密度といった加湿状態を示す物理量の把握など、品質管理をしながら転動を行う必要がある。Next, as a step of reducing the surface waviness of the obtained molded product, the molded product having a weight of at least 100 kg or more is added only with water in the rolling granulator for at least 10 hours or more, preferably about 20 hours, more preferably 30 hours. Roll further for more than an hour. As a result, the surface of the molded product is flattened and the surface waviness is reduced. It is desirable to set the moisture content in the rolling granulator during this step to be 2 to 5% higher than that at the time of granulation growth. As a result, the surface layer of the ceramic sphere contains a large amount of water, which facilitates particle movement (plastic deformation) when subjected to rolling pressure, resulting in flattening of the convex portion and maximum height swell Wz. A small smooth ceramic sphere can be obtained. In addition, visual observation of the appearance to grasp the humidified state of the particles during rolling granulation and microscopic observation of the particle state by extracting a small amount of sample so that the particles do not agglomerate due to excessive water content. Alternatively, it is necessary to perform rolling while performing quality control, such as grasping physical quantities that indicate the humidified state such as moisture content and bulk density.

　また、上記の表面うねり低減工程は、成形体の緻密化を促進する効果も有しており、内部欠陥率の低減にも有効である。Further, the above-mentioned surface waviness reduction step also has an effect of promoting densification of the molded product, and is also effective in reducing the internal defect rate.

　このように得られた成形体は水分を含んでいるため、そのまま後述する焼結工程に供すると、成形体内部の水分が急激に蒸発することで成形体に割れが生じる可能性がある。そのため、成形体は、焼結工程に供する前に、乾燥機等を用いて成形体内部の水分を徐々に減少させる乾燥工程に供される。Since the molded product thus obtained contains water, if it is directly subjected to the sintering process described later, the water inside the molded product may evaporate rapidly and the molded product may be cracked. Therefore, the molded product is subjected to a drying step of gradually reducing the water content inside the molded product by using a dryer or the like before the molded product is subjected to the sintering step.

　このように、成形され、乾燥工程を経た成形体をコウバチ等に入れて焼成炉で焼成する焼結工程を行うことで、バインダーの除去および粉末粒子の結合がなされ、セラミックス焼結体が得られる。焼結工程では、１３５０～１４５０℃で１～３時間焼成することが好ましい。By performing a sintering step in which the molded body that has been molded and dried in this way is placed in a bee or the like and fired in a firing furnace, the binder is removed and the powder particles are bonded, and a ceramic sintered body is obtained. .. In the sintering step, it is preferable to bake at 1350 to 1450 ° C. for 1 to 3 hours.

　焼結工程を経た焼結体は、そのまま、あるいはさらに後述する研磨を経て、粉砕用メディアとして使用することができる。しかし、粉砕用メディアの欠陥をさらに減少させるためには、後述する熱間等方圧加圧工程を行うことが好ましい。以下、焼結工程後にさらに熱間等方圧加圧工程を行う場合について説明する。なお、熱間等方圧加圧工程を行わない場合、前述の焼結工程後の焼結体は最終製品であって「中間焼結体」ではないが、熱間等方圧加圧工程を行う場合の以下の説明においては「中間焼結体」として記述する。The sintered body that has undergone the sintering process can be used as it is, or after further polishing, which will be described later, as a medium for crushing. However, in order to further reduce the defects of the pulverizing media, it is preferable to carry out the hot isotropic pressure pressurization step described later. Hereinafter, a case where a hot isotropic pressure pressurization step is further performed after the sintering step will be described. If the hot isotropic pressure pressurization step is not performed, the sintered body after the above-mentioned sintering step is a final product and not an "intermediate sintered body", but the hot isotropic pressure pressurization step is performed. In the following description, it will be described as "intermediate sintered body".

　前述のように、焼結工程で得られた中間焼結体は、次に、熱間等方圧加圧（Ｈｏｔ　Ｉｓｏｓｔａｔｉｃ　Ｐｒｅｓｓｉｎｇ）処理（以下「ＨＩＰ処理」という）を行う熱間等方圧加圧工程に供することが好ましい。ＨＩＰ処理は、高温と等方的な圧力を被処理物に同時に加える処理であり、中間焼結体にＨＩＰ処理を行うことで、形状を変えることなく中間焼結体内部に残存する空隙や割れなどの欠陥を除去することができる。As described above, the intermediate sintered body obtained in the sintering step is then subjected to hot isostatic pressing (Hot Isostatic Pressing) treatment (hereinafter referred to as “HIP treatment”). It is preferable to use it for a compression step. The HIP treatment is a treatment in which high temperature and isotropic pressure are applied to the object to be processed at the same time. By performing the HIP treatment on the intermediate sintered body, voids and cracks remaining inside the intermediate sintered body without changing the shape. Defects such as can be removed.

　ＨＩＰ処理は、焼結工程における焼結温度に対して０℃～５０℃低い温度で行うことが好ましい。それより低い温度であると、ＨＩＰ処理中におけるジルコニア等のセラミックス粉末の拡散が不十分となり、欠陥が残ってしまう場合がある。一方、ＨＩＰ処理の温度が焼結温度より高いと、中間焼結体が粒成長することで強度低下を招き、また強度のバラツキも大きくなってしまう場合がある。ＨＩＰ処理の温度は、より好ましくは焼結工程における焼結温度に対して０℃～４０℃低い温度であり、さらに好ましくは０℃～３０℃低い温度である。The HIP treatment is preferably performed at a temperature 0 ° C. to 50 ° C. lower than the sintering temperature in the sintering step. If the temperature is lower than that, the diffusion of ceramic powder such as zirconia during the HIP treatment becomes insufficient, and defects may remain. On the other hand, if the temperature of the HIP treatment is higher than the sintering temperature, the intermediate sintered body may grow into grains, resulting in a decrease in strength and a large variation in strength. The temperature of the HIP treatment is more preferably 0 ° C. to 40 ° C. lower than the sintering temperature in the sintering step, and further preferably 0 ° C. to 30 ° C. lower.

　ＨＩＰ処理の圧力は、欠陥を除去できるのに十分な圧力があればよく、１００ＭＰａ以上の圧力で処理すれば問題無く処理することができる。高圧状態にするにはＡｒガス雰囲気中で処理することが好ましい。The pressure for HIP treatment should be sufficient to remove defects, and if the pressure is 100 MPa or more, the treatment can be performed without any problem. In order to obtain a high pressure state, it is preferable to treat in an Ar gas atmosphere.

　以上のようにして得られた焼結体は、そのまま粉砕用メディアとして用いることができるが、さらにバレル研磨装置、ボールミル、ビーズミル等の装置を用いて表面を研磨することによって、より高品質な粉砕用メディアを得ることができる。The sintered body obtained as described above can be used as a crushing medium as it is, but by further polishing the surface using a device such as a barrel polishing device, a ball mill, or a bead mill, higher quality crushing can be performed. You can get media for.

　さらに、焼結体を分級工程により分級することが好ましい。分級工程により所望の平均粒径、最小粒径および最大粒径とすることができる。分級方法としては、メッシュ状の篩を用いて分級する篩式分級などが挙げられる。篩分級は、篩を２段重ねて、相対的に粒径の大きい粗粉と相対的に粒径の小さい微粉を１回の操作で分離するようにしてもよい。Further, it is preferable to classify the sintered body by a classification process. The desired average particle size, minimum particle size and maximum particle size can be obtained by the classification step. Examples of the classification method include a sieve type classification in which a mesh-shaped sieve is used for classification. In the sieve classification, two sieves may be stacked to separate the coarse powder having a relatively large particle size and the fine powder having a relatively small particle size in one operation.

　なお、上記の表面研磨工程に関して、本発明者らが検討した結果、特に、高い攪拌エネルギーを有するビーズミル装置を用いた湿式研磨を行うことで、より良好な表面平滑性が得られることを見い出した。表面平滑性は、湿式分散プロセスにおけるセラミックス球形体の摩耗量に大きく影響する因子であり、表面平滑性が悪い場合、すなわち表面の凹凸が大きい又は多い場合、セラミックス球形体同士あるいはセラミックス球形体と被分散物との間で生じる衝突の際に、凸形状部分が容易に削れることでセラミックス球形体の主要成分であるジルコニアの摩耗量が増大する結果、被分散物の品質に大きな影響を与えうる。特に、本発明のセラミックス球形体メディアの主要な用途である、積層セラミックスコンデンサ製造用の高誘電体原料に用いられるチタン酸バリウム粉末を湿式分散する工程においては、セラミックス球形体の摩耗に起因するジルコニア成分がチタン酸バリウムに混入することで、チタン酸バリウムの焼結反応を阻害する影響を及ぼし、焼結後のチタン酸バリウムの一次粒子径の均一性が損なわれることが知られている。このような一次粒子径の不均一さは、コンデンサの電気特性（容量、誘電損失など）を悪化させたり、１層当りの厚さが僅か１μｍにも満たない薄い誘電体層の形成において表面凹凸を助長し、平坦な積層構造を形成するプロセスにおける阻害要因となりうる。そのため、チタン酸バリウムの湿式分散工程において、被粉砕物に混入したジルコニア摩耗量は高い精度で管理されており、摩耗量が少ない且つ安定したセラミックス球形体メディアが望まれている。それを実現するためには、セラミックス球形体表面の平滑性の確保が必要である。As a result of studies by the present inventors regarding the above-mentioned surface polishing process, it has been found that better surface smoothness can be obtained by performing wet polishing using a bead mill device having a high stirring energy. .. The surface smoothness is a factor that greatly affects the amount of wear of the ceramic spheres in the wet dispersion process. In the event of a collision with a dispersion, the convex portion is easily scraped off, which increases the amount of wear of zirconia, which is the main component of the ceramic spherical body, and as a result, can greatly affect the quality of the dispersion. In particular, in the step of wet-dispersing barium titanate powder used as a raw material for a high dielectric material for manufacturing a laminated ceramics capacitor, which is a main application of the ceramic spherical body media of the present invention, zirconia caused by wear of the ceramic spherical body It is known that when a component is mixed with barium titanate, it has an effect of inhibiting the sintering reaction of barium titanate, and the uniformity of the primary particle size of barium titanate after sintering is impaired. Such non-uniformity of the primary particle diameter deteriorates the electrical characteristics (capacity, dielectric loss, etc.) of the capacitor, and surface unevenness in the formation of a thin dielectric layer having a thickness of less than 1 μm per layer. Can be an obstacle in the process of forming a flat laminated structure. Therefore, in the wet dispersion step of barium titanate, the amount of zirconia wear mixed in the object to be crushed is controlled with high accuracy, and a stable ceramic spherical medium with a small amount of wear is desired. In order to achieve this, it is necessary to ensure the smoothness of the surface of the ceramic spherical body.

　上記のビーズミル装置を用いた研磨工程において、良好な表面平滑性を得るために重要なプロセス因子は、研磨材の種類（素材、粒径）およびそのスラリー濃度、攪拌速度（周速）、処理時間である。微小なサイズのセラミックス球形体ほど自重が軽いため、表面を研磨するためには高い研磨エネルギーが必要である。研磨材としては、切削力の高いシリコンカーバイト（ＳｉＣ）やアルミナ（Ａｌ_２Ｏ_３）を用いることが望ましく、その粒径は大きいほど切削力が高い反面、粒径が小さいほど切削傷を低減できるため平滑な表面が得られやすい。そのため、生産効率観点からは、最初に大きな粒径の研磨材で粗研磨したのち、仕上げ研磨として小さい粒径の研磨材を用いることが有用であり、粗研磨用としては粒径３～１０μｍ程度、仕上げ研磨用としては０．５～２μｍ程度の粒径が望ましい。また、研磨材のスラリー濃度は、研磨処理中の研磨材自身の凝集防止の観点から１～５重量％程度とすることが望ましい。同じく凝集防止の観点からは、研磨材の種類に応じた分散剤を０．３～３重量％ほど添加することが望ましい。装置運転条件である攪拌速度（周速）は、生産能力の観点からは速いほうが望ましいが、速すぎる場合にはセラミックス球形体の表面に研磨材の残渣付着が発生しやすくなるため、両立の観点からは８～１４ｍ／ｓの範囲が望ましい。処理時間は、装置スペックやセラミックス球形体のサイズ、研磨材の種類などに応じて異なるが、少なくとも２時間以上、望ましくは４時間以上行うことが望ましい。また、研磨処理が完了したのちに、研磨材を含まない水のみ、もしくは水と分散剤のみで処理することで、セラミックス球形体表面に付着した残渣を除去することが可能であり、０．５～２時間程度行うことが望ましい。In the polishing process using the above-mentioned bead mill device, the important process factors for obtaining good surface smoothness are the type of abrasive (material, particle size) and its slurry concentration, stirring speed (peripheral speed), and processing time. Is. Since the smaller the size of a ceramic sphere, the lighter its own weight, high polishing energy is required to polish the surface. As the abrasive, it is desirable to use silicon carbide (SiC) or alumina (Al₂ O₃ ), which have high cutting power. The larger the particle size, the higher the cutting power, while the smaller the particle size, the smaller the cutting scratches. Therefore, a smooth surface can be easily obtained. Therefore, from the viewpoint of production efficiency, it is useful to first perform rough polishing with a polishing material having a large particle size, and then use a polishing material having a small particle size for finish polishing, and for rough polishing, the particle size is about 3 to 10 μm. For finish polishing, a particle size of about 0.5 to 2 μm is desirable. Further, the slurry concentration of the abrasive material is preferably about 1 to 5% by weight from the viewpoint of preventing aggregation of the abrasive material itself during the polishing treatment. Similarly, from the viewpoint of preventing aggregation, it is desirable to add about 0.3 to 3% by weight of a dispersant according to the type of abrasive. It is desirable that the stirring speed (peripheral speed), which is the equipment operating condition, be high from the viewpoint of production capacity, but if it is too fast, the residue of the abrasive material tends to adhere to the surface of the ceramic sphere, so from the viewpoint of compatibility. From 8 to 14 m / s is desirable. The processing time varies depending on the device specifications, the size of the ceramic sphere, the type of abrasive, and the like, but it is preferably at least 2 hours or more, preferably 4 hours or more. Further, after the polishing treatment is completed, it is possible to remove the residue adhering to the surface of the ceramic sphere by treating with only water containing no abrasive or only with water and a dispersant. It is desirable to do it for about 2 hours.

　以上のようなビーズミルを用いた湿式研磨を適正な条件で行った結果、例えばバレル研磨方式では表面粗さＲａ＝２０～４０ｎｍ程度の平滑性に対して、Ｒａ＝２～１０ｎｍの平滑性を得ることが可能になる。２ｎｍ以下にするにはより微小な粒径の研磨材を用いて長時間もしくは高い周速での研磨を行う必要があるが、研磨材の凝集が生じやすくなる結果、製品への混入が懸念されるため、本発明による製法としては上記の表面粗さ範囲が妥当である。表面粗さＲａは、原子間力顕微鏡（ＡＦＭ）を用いて評価することが可能である。なお、本発明では、セラミックス球形体１０個を抜き取り評価し、その平均値を表面粗さ値Ｒａとしている。As a result of performing wet polishing using the bead mill as described above under appropriate conditions, for example, in the barrel polishing method, smoothness of surface roughness Ra = 20 to 40 nm is obtained, whereas smoothness of Ra = 2 to 10 nm is obtained. Will be possible. In order to make it 2 nm or less, it is necessary to polish for a long time or at a high peripheral speed using an abrasive with a finer particle size, but as a result of the tendency of the abrasive to agglomerate, there is concern that it may be mixed into the product. Therefore, the above-mentioned surface roughness range is appropriate for the production method according to the present invention. The surface roughness Ra can be evaluated using an atomic force microscope (AFM). In the present invention, 10 ceramic spherical bodies are sampled and evaluated, and the average value thereof is defined as the surface roughness value Ra.

　上記の表面粗さＲａ＝２～１０ｎｍのセラミックス球形体のチタン酸バリウムの湿式分散における摩耗量を評価した結果、Ｒａ＝１０ｎｍから５ｎｍまでは平滑なほど摩耗量も低減するが、５ｎｍ以下ではほぼ横ばいになることが分かった。これは、ジルコニア球形体がチタン酸バリウムからの切削作用を受けるため、例え初期平滑性が２ｎｍ程度であっても、使用後には切削傷により５ｎｍ前後の平滑性に悪化するためであると考えられる。以上の結果から、本発明におけるチタン酸バリウムの湿式分散用途に関して、セラミックス球形体起因のジルコニア摩耗量を低減かつ安定化させるには、セラミックス球形体の表面粗さＲａ＝２～５ｎｍの範囲が望ましい。As a result of evaluating the amount of wear in the wet dispersion of barium titanate of a ceramic sphere having a surface roughness Ra = 2 to 10 nm, the smoother the surface roughness is from Ra = 10 nm to 5 nm, the less the wear amount is, but at 5 nm or less, the wear amount is almost the same. It turned out to be flat. It is considered that this is because the zirconia sphere is subjected to the cutting action from barium titanate, and even if the initial smoothness is about 2 nm, the smoothness deteriorates to about 5 nm due to cutting scratches after use. .. From the above results, it is desirable that the surface roughness Ra of the ceramic sphere is in the range of 2 to 5 nm in order to reduce and stabilize the amount of zirconia wear caused by the ceramic sphere in the wet dispersion application of barium titanate in the present invention. ..

　以下、実施例に基づいて本発明を具体的に説明するが、本発明はこれらの実施例により限定されるものではない。Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

　（測定方法）
　（平均粒径、最小粒径、最大粒径、１％粒径（Ｄ１）、９９％粒径（Ｄ９９）
　粒径は次の方法で測定した。セラミックス球形体の集合体をデジタルマイクロスコープＶＨＸ－２０００（Ｋｅｙｅｎｃｅ製）で倍率１０～２００倍で撮影した。画像解析・計測ソフトウェアＷｉｎＲＯＯＦ(登録商標：三谷商事社製)を用いて、測定用画像の明度を基準として２値化した。２値化画像を最小二乗平均により円型図形分離し、分離したそれぞれの円の直径を個々のセラミックス球形体の直径として算出した。また、１０００個のセラミックス球形体の直径の数平均値を平均粒径Ｘとした。また、円型図形分離したそれぞれの円の直径の最小値を最小粒径、最大値を最大粒径とした。加えて、個数割合で最小側から数えて累積個数１％の相当径を１％粒径（Ｄ１）、累積個数９９％の相当径を９９％粒径（Ｄ９９）とした。(Measuring method)
(Average particle size, minimum particle size, maximum particle size, 1% particle size (D1), 99% particle size (D99)
The particle size was measured by the following method. An aggregate of ceramic spheres was photographed with a digital microscope VHX-2000 (manufactured by Keyence) at a magnification of 10 to 200 times. Image analysis / measurement software WinROOF (registered trademark: manufactured by Mitani Corporation) was used to binarize the image for measurement based on the brightness. The binarized image was separated into circular figures by the minimum squared average, and the diameter of each separated circle was calculated as the diameter of each ceramic sphere. Further, the number average value of the diameters of 1000 ceramic spheres was defined as the average particle size X. Further, the minimum value and the maximum value of the diameter of each circle separated by the circular figure were set as the minimum particle size, and the maximum value was set as the maximum particle size. In addition, the equivalent diameter of the cumulative number of 1% was defined as the 1% particle size (D1), and the equivalent diameter of the cumulative number of 99% was defined as the 99% particle size (D99).

　（結晶相の割合）
　試料を樹脂包埋し、断面出しおよび鏡面研磨を行って測定試料とした。それを試料ホルダーに貼り付け、広角Ｘ線回折法（微小部Ｘ線回折）で測定を行った。測定条件は以下のとおりである。
Ｘ線源：ＣｕＫ線（多層膜ミラー使用）
出力：５０ｋＶ、２２ｍＡ
スリット系：１００μｍφピンホール
測定範囲：２θ＝２３°～３３°、７０°～７７°
積算時間：３６００秒／フレーム。(Ratio of crystalline phase)
The sample was embedded in resin, cross-sectioned and mirror-polished to obtain a measurement sample. It was attached to a sample holder and measured by wide-angle X-ray diffraction method (micro part X-ray diffraction). The measurement conditions are as follows.
X-ray source: CuK line (using multilayer mirror)
Output: 50kV, 22mA
Slit system: 100 μmφ Pinhole measurement range: 2θ = 23 ° to 33 °, 70 ° to 77 °
Accumulated time: 3600 seconds / frame.

　測定結果より、以下の式を用いてジルコニアの各結晶層の含有率を算出した。
単斜晶の含有率（％）＝［｛Ｉ_ｍ（１１１）＋Ｉ_ｍ（１－１－１）｝／｛Ｉ_ｍ（１１１）＋Ｉ_ｍ（１－１－１）＋Ｉ_ｔ＋ｃ（１１１）｝］×１００
立方晶の含有率（％）＝［Ｉ_ｔ＋ｃ（１１１）／｛Ｉ_ｍ（１１１）＋Ｉ_ｍ（１－１－１）＋Ｉ_ｔ＋ｃ（１１１）｝］×［｛Ｉ_ｃ（４００）／｛Ｉ_ｃ（４００）＋Ｉ_ｔ（４００）＋Ｉ_ｔ（００４）｝×１００
正方晶の含有率（％）＝１００－単斜晶の含有率－立方晶の含有率
ここに、Ｉは回折強度を示す。添え字のｍ、ｔ、ｃはそれぞれ単斜晶、立方晶、正方晶を示す。回折強度の（　　）内は各結晶の指数を示す。From the measurement results, the content of each crystal layer of zirconia was calculated using the following formula.
Content of monoclinic crystal (%) = [{I_m (111) +_Im (1-1-1)} / {I_m (111) +_Im (1-1-1) + It_{+ c} (111)}] × 100
Cubic crystal content (%) = [It_{+ c} (111) / {I_m (111) +_Im (1-1-1) + It_{+ c} (111)}] x [{I_c (400) / {I_c (400) + It (400) +_{It (} 004)_} × 100
Tetragonal content (%) = 100-Monocclinic content-Cubic content Here, I indicates the diffraction intensity. The subscripts m, t, and c indicate monoclinic, cubic, and tetragonal, respectively. The index of each crystal is shown in parentheses of the diffraction intensity.

　（最大高さうねりＷｚ）
　最大高さうねりＷｚ（μｍ）はＪＩＳ　Ｂ　０６０１：２０１３に基づく。セラミックス球形体をレーザー顕微鏡ＶＫ－Ｘ－１５０（Ｋｅｙｅｎｃｅ製）を用いて、図１中の４に示す測定方向（図１中のｚ軸方向）から、直径が図１中の２に示すＸ／２（μｍ）となるような該球形体の断面（図１中のｚ軸と直行するｘｙ平面上）と該球形体の表面との交線部、すなわち図１中の３に示す箇所について、非接触で１０個の球形体を対象に、測定長＝平均粒径Ｘ／２×３．１４１（μｍ）、高周波成分除去用カットオフ値λs＝２．５（μｍ）、低周波成分除去用λc＝無しの条件でｚ軸方向の最大高さうねりＷｚを測定し、最大高さうねりＷｚの平均値を算出した。ここで図１中の５は、本発明における最大高さうねりＷｚの測定プロファイル例である。(Maximum height swell Wz)
The maximum height swell Wz (μm) is based on JIS B 0601: 2013. Using a laser microscope VK-X-150 (manufactured by Keyence), the ceramic sphere is X / whose diameter is shown in 2 in FIG. 1 from the measurement direction shown in 4 in FIG. 1 (z-axis direction in FIG. 1). The intersection of the cross section of the spherical body (on the xy plane orthogonal to the z-axis in FIG. 1) and the surface of the spherical body so as to be 2 (μm), that is, the portion shown in 3 in FIG. For 10 non-contact spherical objects, measurement length = average particle size X / 2 × 3.141 (μm), cutoff value for removing high frequency components λs = 2.5 (μm), for removing low frequency components The maximum height swell Wz in the z-axis direction was measured under the condition of no λc =, and the average value of the maximum height swell Wz was calculated. Here, 5 in FIG. 1 is an example of the measurement profile of the maximum height swell Wz in the present invention.

　（表面粗さＲａ）
　表面粗さＲａ（ｎｍ）はＪＩＳ　Ｂ　０６０１：２０１３に基づく。セラミックス球形体の集合体から粒子を任意に１０個抜き取りし、原子間力顕微鏡（Ｂｒｕｋｅｒ社、ＮａｎｏＳｃｏｐｅＶ）を用いて、セラミックス球形体の平均粒径Ｘの１／１０四方サイズの測定エリアで球形体中心付近を走査速度＝０．３Ｈｚ、解像度２５６×２５６で走査して、得られた画像について、Ｆｌａｔｔｅｎ１次、ＰｌａｎｅＦｉｔ－ｘ３次処理を行い、曲面を平面にフィッテイング補正した画像を得た。平面補正した画像について、表面粗さＲａを評価する。各粒子につき３回ずつ評価し、１０粒子×３回＝計３０点のＲａの平均値をこのセラミックス球形体での表面粗さ値Ｒａとした。(Surface roughness Ra)
The surface roughness Ra (nm) is based on JIS B 0601: 2013. Arbitrarily 10 particles are extracted from the aggregate of ceramic spheres, and using an atomic force microscope (Bruker, NanoScopeV), the spheres are measured in a measurement area of 1/10 square size of the average particle size X of the ceramic spheres. The vicinity of the center was scanned at a scanning speed of 0.3 Hz and a resolution of 256 × 256, and the obtained image was subjected to Flatten primary and PlaneFit-x tertiary processing to obtain an image in which the curved surface was fitted to a flat surface. The surface roughness Ra is evaluated for the plane-corrected image. Each particle was evaluated three times, and the average value of Ra of 10 particles × 3 times = 30 points in total was taken as the surface roughness value Ra in this ceramic sphere.

　（内部欠陥率）
　内部欠陥率は次の方法で測定した。セラミックス球形体を研削機で球形体径の４０～６０％の大きさまで研削した後、さらに粒径６μｍのダイヤモンドスラリーで１０分以上仕上げ研磨して略断面を得た。得られたサンプルを、デジタルマイクロスコープＶＨＸ－２０００（Ｋｅｙｅｎｃｅ製）で倍率１０～２００倍で観察し、観察できる割れの数をカウントした。２００個のセラミックス球形体を観察し、それらの内、割れや点欠陥があるセラミックス球形体の割合を算出し、内部欠陥率とした。(Internal defect rate)
The internal defect rate was measured by the following method. The ceramic spherical body was ground to a size of 40 to 60% of the spherical body diameter with a grinder, and then finished and polished with a diamond slurry having a particle size of 6 μm for 10 minutes or more to obtain a substantially cross section. The obtained sample was observed with a digital microscope VHX-2000 (manufactured by Keyence) at a magnification of 10 to 200 times, and the number of observable cracks was counted. 200 ceramic spheres were observed, and the ratio of the ceramic spheres having cracks and point defects was calculated and used as the internal defect rate.

　（圧壊荷重値）
　圧壊荷重値は次の方法で測定した。セラミックス球形体を直径２０ｍｍのジルコニア製の円柱状冶具で挟み、電子式万能試験機ＣＡＴＹ－２０００ＹＤ（米倉製作所製）で０．５ｍｍ／ｍｉｎの速度で圧縮荷重をかけ、破壊したときの荷重値を測定した。測定は３０個のセラミックス球形体で行い、値は平均値を採用した。また、セラミックス球形体が高温の水中に曝された場合の強度試験として、得られたセラミックス球形体を水温９０℃中に５０時間静置し、その後のセラミックス球形体の圧壊荷重値を「水熱試験後の圧壊荷重値」として測定した。測定は３０個の球形体で行い、値は平均値を採用した。さらに、｛（水熱試験前の圧壊荷重値）―（水熱試験後の圧壊荷重値）｝／（水熱試験前の圧壊荷重値）×１００により水熱試験後の圧壊荷重の低下率として算出した。(Crushing load value)
The crushing load value was measured by the following method. A ceramic sphere is sandwiched between zirconia columnar jigs with a diameter of 20 mm, and a compressive load is applied at a speed of 0.5 mm / min with an electronic universal testing machine CATY-2000YD (manufactured by Yonekura Seisakusho) to determine the load value when broken. It was measured. The measurement was performed with 30 ceramic spheres, and the average value was adopted as the value. Further, as a strength test when the ceramic sphere is exposed to high temperature water, the obtained ceramic sphere is allowed to stand at a water temperature of 90 ° C. for 50 hours, and the crushing load value of the ceramic sphere thereafter is set to "water heat". It was measured as "crushing load value after the test". The measurement was performed with 30 spherical bodies, and the average value was adopted as the value. Furthermore, {(crushing load value before the hydrothermal test)-(crushing load value after the hydrothermal test)} / (crushing load value before the hydrothermal test) × 100 indicates the rate of decrease in the crushing load after the hydrothermal test. Calculated.

　（割れ試験）
　次の方法により割れ試験を行った。得られたセラミックス球形体の集合体をビーズミル装置（広島メタル＆マシナリー社製、型式ＵＡＭ－０１５）に２２０ｇ充填し、２０℃の純水３００ｇを循環し、周速１２ｍ／ｓで２４時間の攪拌を行った。攪拌後、セラミックス球形体を取り出し、デジタルマイクロスコープＶＨＸ－２０００（Ｋｅｙｅｎｃｅ）を用いて倍率１０～２００倍で観察を行い、割れの有無を確認した。１０００個のセラミックス球形体を確認し、割れたセラミックス球形体の個数を割れ個数とした。(Crack test)
A crack test was performed by the following method. 220 g of the obtained aggregate of ceramic spheres was filled in a bead mill device (manufactured by Hiroshima Metal & Machinery Co., Ltd., model UAM-015), 300 g of pure water at 20 ° C. was circulated, and stirring was performed at a peripheral speed of 12 m / s for 24 hours. Was done. After stirring, the ceramic sphere was taken out and observed with a digital microscope VHX-2000 (Keyence) at a magnification of 10 to 200 times to confirm the presence or absence of cracks. 1000 ceramic spheres were confirmed, and the number of broken ceramic spheres was defined as the number of cracks.

　（チタン酸バリウムの湿式分散における摩耗量評価、割れ評価）
　次の方法によりチタン酸バリウムの湿式分散におけるセラミックス球形体の摩耗量評価を行った。得られたセラミックス球形体の集合体をビーズミル装置（広島メタル＆マシナリー社製、型式ＵＡＭ－０１５）に２２０ｇ充填し、２０℃の純水３００ｇにチタン酸バリウム３０ｇ（シグマアルドリッチ社、チタン（ＩＶ）酸バリウム）、分散剤を３ｇ（東京化成工業（株）、ドデシルベンゼンスルホン酸ナトリウム）を調合して作製したスラリーを循環し、周速１２ｍ／ｓで４時間の湿式分散を実施。得られたスラリーを熱風乾燥機で９０℃×２４時間乾燥し、乾固したチタン酸バリウム粉末をすり鉢を用いて微粉砕したのち、蛍光Ｘ線分析装置（理学電気工業製　ＺＳＸ　ＰｒｉｍｕｓＩＩ）を用いてチタン、バリウムの強度ピーク面積に対するジルコニウムの強度ピーク面積の比率を求めることで、チタン酸バリウム粉末中のジルコニア量（セラミックス球形体摩耗量）を算出した。また、この試験の実施後に、前述の割れ試験と同様の手法にて、デジタルマイクロスコープを用いてセラミックス球形体の割れ個数を確認した。(Evaluation of wear amount and crack evaluation in wet dispersion of barium titanate)
The amount of wear of the ceramic sphere in the wet dispersion of barium titanate was evaluated by the following method. 220 g of the obtained aggregate of ceramic spheres was filled in a bead mill device (Hiroshima Metal & Machinery Co., Ltd., model UAM-015), and barium titanate 30 g (Sigma Aldrich Co., Ltd., titanium (IV)) was filled in 300 g of pure water at 20 ° C. Barium acid) and 3 g of dispersant (Tokyo Kasei Kogyo Co., Ltd., sodium dodecylbenzene sulfonate) were mixed to circulate the slurry, and wet dispersion was carried out at a peripheral speed of 12 m / s for 4 hours. The obtained slurry was dried at 90 ° C. for 24 hours in a hot air dryer, and the dried barium titanate powder was finely pulverized using a mortar, and then using a fluorescent X-ray analyzer (ZSX PrimusII manufactured by Rigaku Denki Kogyo). The amount of zirconia (ceramic spherical body wear) in the barium titanate powder was calculated by obtaining the ratio of the intensity peak area of zirconium to the intensity peak area of titanium and barium. In addition, after carrying out this test, the number of cracks in the ceramic sphere was confirmed using a digital microscope by the same method as the crack test described above.

　［実施例１］
　オキシ塩化ジルコニウムに塩化イットリウムを、得られるセラミックス球形体における酸化物換算で表１のイットリア／ジルコニアモル比に示す割合となるよう加え、共沈法で原料粉末を作製した。[Example 1]
Yttrium chloride was added to zirconium oxychloride so as to have a ratio shown in the yttria / zirconia molar ratio in Table 1 in terms of oxide in the obtained ceramic sphere, and a raw material powder was prepared by a coprecipitation method.

　次に上記原料粉末を用いて転動造粒成形法で焼結後の平均粒径Ｘが５０μｍ前後となるサイズまで成形体を造粒成型した。Next, using the above raw material powder, the molded product was granulated and molded to a size in which the average particle size X after sintering was about 50 μm by the rolling granulation molding method.

　次に、得られた成形体の表面うねり低減工程として、転動造粒機内で水分率を一定に保つよう水のみを添加しながら約４０時間の転動を行うことにより、表面うねりを低減させた。Next, as a step of reducing the surface waviness of the obtained molded product, the surface waviness is reduced by rolling for about 40 hours while adding only water so as to keep the moisture content constant in the rolling granulator. rice field.

　以上のとおり得られた成形体を乾燥した後に、１４００℃で２時間焼成し、中間焼結体を得た（焼結工程）。その後、中間焼結体に対し、１３８０℃、１２０ＭＰａで１．５時間ＨＩＰ処理を行った（熱間等方圧加圧工程）。得られた焼結体についてバレル研磨装置を用いて表面研磨した後、篩式分級を行うことで、表１に示す粉砕用球形メディアを作製した。After drying the molded product obtained as described above, it was fired at 1400 ° C. for 2 hours to obtain an intermediate sintered body (sintering step). Then, the intermediate sintered body was subjected to HIP treatment at 1380 ° C. and 120 MPa for 1.5 hours (hot isotropic pressure pressurization step). The obtained sintered body was surface-polished using a barrel polishing device, and then sieve-type classification was performed to prepare a spherical media for pulverization shown in Table 1.

　［実施例２］
　実施例１の原料粉末を用いて、実施例１と同様に転動造粒成形法で焼結後の平均粒径Ｘが１００μｍ前後となるサイズまで成形体を造粒し、表面うねり低減工程を実施した。得られた成形体を乾燥して水分を除去した後に、焼成、ＨＩＰ処理を行った。得られた焼結体はバレル研磨装置で表面を研磨した後、篩式分級を行うことで、表１に示す粉砕用球形メディアを作製した。[Example 2]
Using the raw material powder of Example 1, the compact is granulated to a size where the average particle size X after sintering is about 100 μm by the rolling granulation molding method in the same manner as in Example 1, and the surface waviness reduction step is performed. Carried out. The obtained molded product was dried to remove water, and then fired and subjected to HIP treatment. The surface of the obtained sintered body was polished with a barrel polishing device, and then sieve-type classification was performed to prepare a spherical medium for pulverization shown in Table 1.

　［実施例３］
　実施例１の原料粉末を用いて、実施例１と同様に転動造粒成形法で焼結後の平均粒径Ｘが２００μｍ前後となるサイズまで成形体を造粒し、表面うねり低減工程を実施した。得られた成形体を乾燥して水分を除去した後に、焼成、ＨＩＰ処理を行った。得られた焼結体はバレル研磨装置で表面を研磨した後、篩式分級を行うことで、表１に示す粉砕用球形メディアを作製した。[Example 3]
Using the raw material powder of Example 1, the compact is granulated to a size where the average particle size X after sintering is about 200 μm by the rolling granulation molding method in the same manner as in Example 1, and the surface waviness reduction step is performed. Carried out. The obtained molded product was dried to remove water, and then fired and subjected to HIP treatment. The surface of the obtained sintered body was polished with a barrel polishing device, and then sieve-type classification was performed to prepare a spherical medium for pulverization shown in Table 1.

　［実施例４］
　実施例1と同様に、転動造粒成形法で焼結後の平均粒径Ｘが５０μｍ前後となるサイズまで成形体を造粒した。表面うねり低減工程の時間を１０時間に短縮した以外は実施例１と同様に実施して、表１に示す粉砕用球形メディアを作製した。[Example 4]
In the same manner as in Example 1, the compact was granulated to a size in which the average particle size X after sintering was about 50 μm by the rolling granulation molding method. The same procedure as in Example 1 was carried out except that the time of the surface waviness reduction step was shortened to 10 hours to prepare the spherical media for pulverization shown in Table 1.

　［実施例５］
　実施例２と同様に、転動造粒成形法で焼結後の平均粒径Ｘが１００μｍ前後となるサイズまで成形体を造粒した。表面うねり低減工程の時間を１０時間に短縮した以外は実施例２と同様に実施して、表１に示す粉砕用球形メディアを作製した。[Example 5]
In the same manner as in Example 2, the compact was granulated to a size in which the average particle size X after sintering was about 100 μm by the rolling granulation molding method. The same procedure as in Example 2 was carried out except that the time of the surface waviness reduction step was shortened to 10 hours to prepare the spherical media for pulverization shown in Table 1.

　［実施例６］
　実施例３と同様に、転動造粒成形法で焼結後の平均粒径Ｘが２００μｍ前後となるサイズまで成形体を造粒した。表面うねり低減工程の時間を１０時間に短縮した以外は実施例３と同様に実施して、表１に示す粉砕用球形メディアを作製した。[Example 6]
In the same manner as in Example 3, the compact was granulated to a size in which the average particle size X after sintering was about 200 μm by the rolling granulation molding method. The same procedure as in Example 3 was carried out except that the time of the surface waviness reduction step was shortened to 10 hours to prepare the spherical media for pulverization shown in Table 1.

　［実施例７］
　実施例２と同様に、転動造粒成形法で焼結後の平均粒径Ｘが１００μｍ前後となるサイズまで成形体を造粒した。ＨＩＰ工程の処理温度を１３８０℃から１３００℃に変更した以外は実施例２と同様に実施して、表１に示す粉砕用球形メディアを作製した。[Example 7]
In the same manner as in Example 2, the compact was granulated to a size in which the average particle size X after sintering was about 100 μm by the rolling granulation molding method. The same procedure as in Example 2 was carried out except that the treatment temperature of the HIP step was changed from 1380 ° C. to 1300 ° C. to prepare a spherical media for pulverization shown in Table 1.

　［実施例８］
　実施例１と同じ製造プロセスをＨＩＰ処理まで行い、研磨工程はビーズミルを用いて以下の通り実施した。研磨材として粒径３μｍのアルミナ（（株）チップトン社、ライト１Ａ）を３．０重量％、分散剤としてポリカルボン酸ナトリウム塩（中京油脂（株）、セルナＤ－３０５）を０．５重量％調合した研磨スラリーを用いて、ビーズミル攪拌周速＝１２ｍ／ｓで計６時間研磨したのち、粒径１μｍのアルミナ（（株）チップトン社、ライト１Ａ）を１．０重量％、分散剤は同じくＤ－３０５を０．５重量％調合した研磨スラリーで４時間の研磨を実施。最後にＤ－３０５のみ０．５重量％調合したスラリーで２時間の共摺りを行うことでセラミックス球形体の表面残渣を除去し、表面粗さＲａ＝２ｎｍのセラミックス球形体を得た。その後の篩式分級は実施例１と同様の手法で行った。[Example 8]
The same manufacturing process as in Example 1 was carried out up to HIP treatment, and the polishing step was carried out using a bead mill as follows. Alumina with a particle size of 3 μm (Chipton Co., Ltd., Light 1A) is 3.0% by weight as an abrasive, and polycarboxylic acid sodium salt (Chukyo Yushi Co., Ltd., Serna D-305) is 0.5% by weight as a dispersant. After polishing for a total of 6 hours at a bead mill stirring peripheral speed = 12 m / s using the prepared polishing slurry, 1.0% by weight of alumina (Chipton Co., Ltd., Light 1A) having a particle size of 1 μm was used as the dispersant. Similarly, polishing was carried out for 4 hours with a polishing slurry containing 0.5% by weight of D-305. Finally, the surface residue of the ceramic sphere was removed by co-rubbing only D-305 with a slurry prepared in an amount of 0.5% by weight for 2 hours to obtain a ceramic sphere having a surface roughness Ra = 2 nm. Subsequent sieve classification was performed in the same manner as in Example 1.

　［実施例９］
　実施例１と同じ製造プロセスをＨＩＰ処理まで行い、研磨工程はビーズミルを用いて以下の通り実施した。研磨材として粒径３μｍのアルミナ（（株）チップトン社、ライト１Ａ）を３．０重量％、分散剤としてポリカルボン酸ナトリウム塩（中京油脂（株）、セルナＤ－３０５）を０．５重量％調合した研磨スラリーを用いて、ビーズミル攪拌周速＝１２ｍ／ｓで計６時間研磨したのち、Ｄ－３０５のみ０．５重量％調合したスラリーで２時間の共摺りを行うことでセラミックス球形体の表面残渣を除去して表面粗さＲａ＝５ｎｍのセラミックス球形体を得た。その後の篩式分級は実施例１と同様の手法で行った。[Example 9]
The same manufacturing process as in Example 1 was carried out up to HIP treatment, and the polishing step was carried out using a bead mill as follows. Alumina with a particle size of 3 μm (Chipton Co., Ltd., Light 1A) is 3.0% by weight as an abrasive, and polycarboxylic acid sodium salt (Chukyo Yushi Co., Ltd., Serna D-305) is 0.5% by weight as a dispersant. After polishing for a total of 6 hours at a bead mill stirring peripheral speed = 12 m / s using the prepared abrasive slurry, ceramic spheres were rubbed together for 2 hours with the 0.5% by weight mixed slurry only for D-305. The surface residue of the above was removed to obtain a ceramic sphere having a surface roughness Ra = 5 nm. Subsequent sieve classification was performed in the same manner as in Example 1.

　［実施例１０］
　実施例１と同じ製造プロセスをＨＩＰ処理まで行い、研磨工程はビーズミルを用いて以下の通り実施した。研磨材として粒径３μｍのアルミナ（（株）チップトン社、ライト１Ａ）を３．０重量％、分散剤としてポリカルボン酸ナトリウム塩（中京油脂（株）、セルナＤ－３０５）を０．５重量％調合した研磨スラリーを用いて、ビーズミル攪拌周速＝１２ｍ／ｓで計３時間研磨したのち、Ｄ－３０５のみ０．５重量％調合したスラリーで２時間の共摺りを行うことでセラミックス球形体の表面残渣を除去して表面粗さＲａ＝１０ｎｍのセラミックス球形体を得た。その後の篩式分級は実施例１と同様の手法で行った。[Example 10]
The same manufacturing process as in Example 1 was carried out up to HIP treatment, and the polishing step was carried out using a bead mill as follows. Alumina with a particle size of 3 μm (Chipton Co., Ltd., Light 1A) is 3.0% by weight as an abrasive, and polycarboxylic acid sodium salt (Chukyo Yushi Co., Ltd., Serna D-305) is 0.5% by weight as a dispersant. After polishing for a total of 3 hours at a bead mill stirring peripheral speed = 12 m / s using the prepared abrasive slurry, the ceramic sphere was rubbed with the slurry containing 0.5% by weight of D-305 for 2 hours. The surface residue of the above was removed to obtain a ceramic sphere having a surface roughness Ra = 10 nm. Subsequent sieve classification was performed in the same manner as in Example 1.

　［比較例１］
　実施例１と同様に、転動造粒成形法で焼結後の平均粒径Ｘが５０μｍ前後となるサイズまで成形体を造粒した。表面うねり低減工程を省略した以外は実施例１と同様に実施して、表１に示す粉砕用球形メディアを作製した。[Comparative Example 1]
In the same manner as in Example 1, the compact was granulated to a size in which the average particle size X after sintering was about 50 μm by the rolling granulation molding method. The same procedure as in Example 1 was carried out except that the surface waviness reduction step was omitted, to produce the spherical media for pulverization shown in Table 1.

　［比較例２］
　実施例２と同様に、転動造粒成形法で焼結後の平均粒径Ｘが１００μｍ前後となるサイズまで成形体を造粒した。表面うねり低減工程を省略した以外は実施例２と同様に実施して、表１に示す粉砕用球形メディアを作製した。[Comparative Example 2]
In the same manner as in Example 2, the compact was granulated to a size in which the average particle size X after sintering was about 100 μm by the rolling granulation molding method. The same procedure as in Example 2 was carried out except that the surface waviness reduction step was omitted, to produce the spherical media for pulverization shown in Table 1.

　［比較例３］
　実施例３と同様に、転動造粒成形法で焼結後の平均粒径Ｘが２００μｍ前後となるサイズまで成形体を造粒した。表面うねり低減工程を省略した以外は実施例３と同様に実施して、表１に示す粉砕用球形メディアを作製した。[Comparative Example 3]
In the same manner as in Example 3, the compact was granulated to a size in which the average particle size X after sintering was about 200 μm by the rolling granulation molding method. The same procedure as in Example 3 was carried out except that the surface waviness reduction step was omitted, to produce the spherical media for pulverization shown in Table 1.

　［比較例４～６］
　オキシ塩化ジルコニウムに塩化イットリウムを、得られるセラミックス球形体における酸化物換算で表１のイットリア／ジルコニアモル比に示す割合となるよう加え、共沈法で原料粉末を作製した。[Comparative Examples 4 to 6]
Yttrium chloride was added to zirconium oxychloride so as to have a ratio shown in the yttria / zirconia molar ratio in Table 1 in terms of oxide in the obtained ceramic sphere, and a raw material powder was prepared by a coprecipitation method.

　次に上記原料粉末を用いて、実施例２と同様に、転動造粒成形法で焼結後の平均粒径が１００μｍとなるサイズまで成形体を造粒し、表面うねり低減工程を実施した。得られた成形体を乾燥して水分を除去した後に、焼成、ＨＩＰ処理を行った。得られた焼結体はバレル研磨装置で表面を研磨した後、篩式分級を行うことで、表１に示す粉砕用球形メディアを作製した。Next, using the above raw material powder, a molded body was granulated to a size in which the average particle size after sintering was 100 μm by the rolling granulation molding method in the same manner as in Example 2, and a surface waviness reduction step was carried out. .. The obtained molded product was dried to remove water, and then fired and subjected to HIP treatment. The surface of the obtained sintered body was polished with a barrel polishing device, and then sieve-type classification was performed to prepare a spherical medium for pulverization shown in Table 1.

　[比較例７]
　比較例１と同じ製法をＨＩＰ工程まで行い、研磨工程は実施例８と同じビーズミルを用いた研磨条件にて実施することで、表面粗さＲａ＝３ｎｍの表面平滑性を得た。篩式分級も実施例８と同様に実施した。[Comparative Example 7]
The same manufacturing method as in Comparative Example 1 was carried out up to the HIP step, and the polishing step was carried out under the same polishing conditions as in Example 8 using a bead mill to obtain surface smoothness with a surface roughness Ra = 3 nm. Sieve classification was also carried out in the same manner as in Example 8.

　評価結果を表１～２に示す。The evaluation results are shown in Tables 1 and 2.

　実施例１～６に示されるとおり、表面うねりを低減することにより、破損しにくいセラミックス球形体が得られた。実施例７では、ＨＩＰ温度を下げたことで内部欠陥率が高くなり、割れ個数がやや増加したが、許容範囲内であった。As shown in Examples 1 to 6, by reducing the surface waviness, a ceramic sphere that is not easily damaged was obtained. In Example 7, by lowering the HIP temperature, the internal defect rate increased and the number of cracks increased slightly, but it was within the permissible range.

　比較例１～３では、表面うねりが大きいため、破損しやすいセラミックス球形体であった。比較例４では、単斜晶の割合が大きいため、破損しやすいセラミックス球形体であった。比較例５では、正方晶の割合が大きいため水熱試験後の圧壊荷重値の低下率が大きく、水温が上昇した場合に破損する可能性の高いセラミックス球形体であった。比較例６では正方晶の割合が小さいため、破損しやすいセラミックス球形体であった。In Comparative Examples 1 to 3, the ceramic sphere was easily damaged due to the large surface swell. In Comparative Example 4, since the proportion of monoclinic crystals was large, it was a ceramic sphere that was easily damaged. In Comparative Example 5, since the proportion of tetragonal crystals was large, the rate of decrease in the crushing load value after the hydrothermal test was large, and the ceramic sphere was highly likely to be damaged when the water temperature rose. In Comparative Example 6, since the proportion of tetragonal crystals was small, it was a ceramic sphere that was easily damaged.

　また、実施例１および実施例８～１０に示されるとおり、表面粗さＲａ＝５～２０ｎｍの範囲では、Ｒａの低減に伴いチタン酸バリウムの湿式分散におけるジルコニア摩耗量は低減するが、５ｎｍと２ｎｍでは同程度となった。また、その際のセラミックス球形体の割れ個数は、実施例１，８～１０いずれも発生ゼロであった。また、割れ試験における割れ耐性は、実施例１と同様に実施例８～１０においても発生ゼロであった。Further, as shown in Examples 1 and 8 to 10, in the range of surface roughness Ra = 5 to 20 nm, the amount of zirconia wear in the wet dispersion of barium titanate decreases with the reduction of Ra, but it is 5 nm. At 2 nm, it was about the same. In addition, the number of cracks in the ceramic sphere at that time was zero in all of Examples 1 and 8 to 10. In addition, the crack resistance in the crack test was zero in Examples 8 to 10 as in Example 1.

　比較例７では、チタン酸バリウムの湿式分散におけるジルコニア摩耗量は実施例１０よりは少ないものの実施例８～９よりは高めの数値となった。セラミックス球形体の割れ発生が見られており、微小な割れ破片がチタン酸バリウム分散物に混入した影響との可能性が考えられる。割れ試験における割れ個数についても比較例１と大差無く、割れ発生が見られた。In Comparative Example 7, the amount of zirconia wear in the wet dispersion of barium titanate was smaller than that of Example 10, but higher than that of Examples 8 to 9. Cracks have been observed in the ceramic sphere, and it is possible that minute crack fragments were mixed into the barium titanate dispersion. The number of cracks in the crack test was not much different from that of Comparative Example 1, and cracks were observed.

１：セラミックス球形体の直径
２：Ｘ／２（μｍ）となる直径
３：直径がＸ／２（μｍ）となるようなセラミックス球形体の断面と該球形体の表面との交線部
４：最大高さうねりＷｚの測定方向
５：最大高さうねりＷｚの測定プロファイルの事例
 1: Diameter of ceramic sphere 2: Diameter of X / 2 (μm) 3: Intersection between cross section of ceramic sphere with diameter of X / 2 (μm) and surface of the sphere 4: Maximum height swell Wz measurement direction 5: Example of maximum height swell Wz measurement profile

Claims (7)

Translated fromJapanese

ジルコニアを主成分とし、正方晶の割合が８０容量％以上９５容量％以下、単斜晶の割合が５容量％以下であるセラミックス球形体であって、
平均粒径をＸ（μｍ）とした時に直径がＸ／２（μｍ）となるような該球形体の断面と該球形体の表面との交線部における最大高さうねりＷｚ（μｍ）が、平均粒径Ｘ（μｍ）の０．５％以上１．２％以下であることを特徴とするセラミックス球形体。A ceramic sphere containing zirconia as a main component, having a tetragonal ratio of 80% by volume or more and 95% by volume or less, and a monoclinic crystal ratio of 5% by volume or less.
The maximum height swell Wz (μm) at the line of intersection between the cross section of the sphere and the surface of the sphere so that the diameter becomes X / 2 (μm) when the average particle size is X (μm). A ceramic sphere characterized by having an average particle size X (μm) of 0.5% or more and 1.2% or less.単斜晶の割合が０．１容量％以上である請求項１に記載のセラミックス球形体。The ceramic sphere according to claim 1, wherein the proportion of monoclinic crystals is 0.1% by volume or more.粒度分布における１％粒径（Ｄ１）が０．７Ｘ（μｍ）以上であり、９９％粒径（Ｄ９９）が１．３Ｘ（μｍ）以下である請求項１又は２に記載のセラミックス球形体。The ceramic sphere according to claim 1 or 2, wherein the 1% particle size (D1) in the particle size distribution is 0.7X (μm) or more and the 99% particle size (D99) is 1.3X (μm) or less.最小粒径が０．７Ｘ（μｍ）以上であり、最大粒径が１．３Ｘ（μｍ）以下である請求項１～３のいずれかに記載のセラミックス球形体。The ceramic spherical body according to any one of claims 1 to 3, wherein the minimum particle size is 0.7 X (μm) or more and the maximum particle size is 1.3 X (μm) or less.前記セラミックス球形体の内部欠陥率が０．５％以下である請求項１～４のいずれかに記載のセラミックス球形体。The ceramic sphere according to any one of claims 1 to 4, wherein the ceramic sphere has an internal defect rate of 0.5% or less.前記セラミックス球形体の平均粒径が、３０μｍ以上３００μｍ以下である請求項１～５のいずれかに記載のセラミックス球形体。The ceramic sphere according to any one of claims 1 to 5, wherein the ceramic sphere has an average particle size of 30 μm or more and 300 μm or less.表面粗さＲａが２．０ｎｍ以上５．０ｎｍ以下であり、チタン酸バリウム粉末の湿式粉砕に用いられる請求項１～６のいずれかに記載のセラミックス球形体。
 The ceramic sphere according to any one of claims 1 to 6, which has a surface roughness Ra of 2.0 nm or more and 5.0 nm or less and is used for wet pulverization of barium titanate powder.

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