JP3819960B2 - Manufacturing method of conductive ceramic and magnetic disk holding member using the same - Google Patents

Description

【００２６】
仮焼後の原料に別途合成した純度９９％以上のＺｎＦｅ₂ Ｏ₄ 原料を所定量加え、アルミナボールまたはジルコニアボール、メノーボールを用い平均粒系が２μｍ以下となるよう微粉砕する。なお、この粉砕によりジルコニアまたはアルミナ、シリカ等が３重量％以下混入することがある。これにバインダーを加えて造粒を行った後、０．８から２．０ｔｏｎ／ｃｍ² の圧力でプレス成形した。その後、酸化性雰囲気において常圧下所定温度で焼成した。得られた試料について嵩比重、熱膨張係数、ポア率、焼結性、ヤング率、電気抵抗について調べ、表２に結果を記した。
【００２７】
【表２】

【００２８】
ここで、嵩比重は水中におけるアルキメデス法により求め、熱膨張係数は熱膨張係数測定装置により求めた。ポアの発生率は１μｍのダイヤモンド砥粒による最終ラップ面に生じるポア径を測定することにより評価した。ポア率はポア平均径が５μｍを越えるものを×印、３〜５μｍを△印、２〜３μｍを○印、２μｍ以下を◎印で示した。焼結性は吸水率２％以上を×印、０％を○印、その中間を△印で示した。
【００２９】
表２の結果において、試料 No.２から５、 No.７から１１、 No.１３は本発明の範囲内の導電性磁器であり、熱膨張係数はそれぞれ９０〜１１８ｘ１０^-7／℃の範囲であり、ポアの発生率および焼結性は良好であった。これ対し、試料 No.１は酸化カルシウムが多いことから、焼結性が劣っている。また、 No.６は電気抵抗値が１０⁶ Ω・ｃｍ以上と大きく導電性材料として適切でなかった。 No.１２は亜鉛フェライトの量が多く、ヤング率が１６４ＧＰａと小さく本発明の範囲外の組成である。 No.１４は酸化鉄が多く非磁性材料としては適切ではなかった。
【００３０】
表２の試料 No.３、５、７、９の焼結体を１０００℃から１２００℃でアルゴン雰囲気中２０００気圧でＨＩＰ処理した。得られた試料をそれぞれ No.１５、１６、１７、１８とした。これらの試料について同様に嵩比重、熱膨張係数、ポア率、焼結性、ヤング率、電気抵抗について調べ、表３に記した。
【００３１】
【表３】

【００３２】
「実施例２」
市販されている純度９９％の酸化鉄Ｆｅ₂ Ｏ₃ （不純物としてＳｉ、Ａｌ、Ｍｎ、Ｃａ、Ｎａ、Ｓ、Ｃｌ、Ｍｇ、Ｓ、Ｃｒ、Ｐ、Ｎａ、Ｎｂ等を含む）を使い、ＣａＯ源としてＣａＣｌ₂ 、ＣａＣＯ₃ 等を使用し、ＺｎＯ源としてＺｎＯ、ＺｎＦｅ₂ Ｏ₄ 等を使い、さらに焼結体中におけるＭｇＯ、ＴｉＯ₂ 、ＭｎＯ、ＳｉＯ₂ 、ＺｒＯ₂ の含有量が表４となるよう所定量秤量し、この後ボールミルを用いて湿式混合した。後は上記実施例１と同様にして各試料を得た。得られた試料について実施例１と同様に嵩比重、熱膨張係数、ポア率、焼結性、電気抵抗、ヤング率について調べ、表５に記した。 No.２６はＺｒＯ₂ を４重量％含み焼結体にクラックが発生した。
【００３３】
【表４】

【００３４】
表５によりＭｇＯ、ＴｉＯ₂ 、ＭｎＯ、ＳｉＯ₂ 、ＺｒＯ₂ 、Ａｌ₂ Ｏ₃ を３重量％以下含有することにより焼結性が良くなり、ポアサイズも小さくなることが判明した。
【００３５】
【表５】

【００３６】
何れも体積固有抵抗値１０⁶ Ω・ｃｍ以下、ヤング率１８０ＧＰａ以上かつ熱膨張係数が９０から１１８×１０^-7／℃の範囲にあり、基準値を満足することができた。
【００３７】
【発明の効果】
以上詳述した通り、本発明の導電性セラミックスは、ＣａＦｅ₂ Ｏ₄ あるいはＣａ₂ Ｆｅ₂ Ｏ₅ の一種あるいは二種を９５〜１０重量％含みしかも亜鉛フェライトを５から９０重量％含む組成物よりなり、材料の電気抵抗は１０⁶ Ω・ｃｍ以下と小さく、電子部品等、例えば各種の情報記録用ディスクの熱膨張係数の１２０〜９０×１０^-7／℃に近づけることができる。これにより、導電性磁器を電子部品構造体、例えば情報記録用ディスクとクランプしても温度上昇による歪みを生ぜず、電子部品の機能を阻害することがなく、しかも帯電による機能素子の破壊を防止できる。また、電子機能の破損を確実に防止し、電子部品や装置の信頼性を著しく向上させることができる。
【００３８】
さらに、上記組成物にＭｇＯ、ＴｉＯ₂ 、ＭｎＯ、ＳｉＯ₂ 、ＺｒＯ₂ のうちの少なくとも１種を合計で３重量％以下含有させることで、焼結性が向上し、ポアサイズも小さくなり機械的強度を大きくさせることができる。
例えば、本発明はシム、クランプおよびスペーサなどの保持部材を体積固有抵抗値が１０⁶ Ω・ｃｍ以下の導電性を有するカルシウムフェライトと亜鉛フェライトの複合化合物より形成したことにより、情報記録用ディスク基板の熱膨張係数と類似した値とすることができ、装置の運転時の温度変化から生じる熱膨張差に伴う不都合を生じることがなく、また、情報記録用ディスク基板に帯電した静電気を効率良く逃がすことができる。
【００３９】
また、本発明は、上記保持部材を用いて情報記録用ディスク基板を導電性材料からなるハブに順次挿入して磁気ディスク装置を構成したことにより、情報記録用ディスク基板に対するヘッドの浮上量を極めて小さくすることができ、高密度記録（大容量化）と小型化を実現できるとともに、磁気ディスク基板に帯電する静電気を保持部材、ハブを介して効率良く逃がすことができるため、記録内容の破壊を防止することができる。
【図面の簡単な説明】
【図１】本発明に係る情報記録再生用ディスク装置の要部の概略縦断面図である。
【符号の説明】
１…ジンバル
２…記録再生用ヘッド
３…固定ネジ
４…シム
５…ディスク基板
６…ハブ
７…回転軸
８…スペーサ
９…クランプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductive ceramic member for charge removal or prevention that prevents destruction of element functions that occur when an electronic component or the like is charged and discharged by mechanical friction or friction with charged particles. The present invention also relates to an antistatic member or a charge removing member that is necessary for manufacturing these electronic components.
[0002]
In addition, it is a ceramic material that is small in deformation due to stress in an electronic component or an electronic component manufacturing apparatus and can be applied to a highly accurate structure.
For example, it is a part used in a magnetic recording disk drive device, and particularly relates to a material or a part used in a spacer, a hub, a shim, or a clamp for maintaining a space between the disks in an apparatus using a plurality of magnetic disks.
[0003]
[Prior art]
The information recording / reproducing apparatus is increasing in recording density and capacity, and accordingly, the magnetic disk is required to cope with increasing linear density and track density.
In a magnetic drive device using such magnetic recording, as one of the methods for achieving high linear density and high track density corresponding to high capacity, the disk surface has low surface roughness, high rigidity and flatness. Smaller discs are used. In addition, there is a demand for a material composition that can be mass-produced at the same cost as aluminum.
[0004]
In order to satisfy these requirements, aluminum or a glass substrate having a large Young's modulus is employed as a disk substrate material. In addition, in order to use these discs and rotate the discs with high precision, spacers and hubs for holding the discs, and aluminum and aluminum alloys are used as clamp materials.
Conventionally, as shown in FIG. 1, an information recording / reproducing disk device has a plurality of information recording / reproducing disk substrates 5 and spacers 8 alternately inserted into a hub 6 fixed to a rotating shaft 7, and finally, It is fixed by pressing with the shim 4 and the clamp 9 and tightening with the fixing screw 3. Then, while the information recording disk substrate 5 is rotated by the rotation of the rotating shaft 7, the recording / reproducing head 2 moves on the surface of the information recording disk substrate 5, thereby writing information on the recording / reproducing disk substrate 5. And reading.
[0005]
In recent years, the information recording disk drive apparatus has a distance (flying height) between the recording / reproducing head 2 and the recording / reproducing disk substrate 5 as the capacity of information increases and the apparatus becomes smaller. Miniaturization to about 0.05 μm and higher leveling of the recording / reproducing disk substrate 5 and miniaturization of surface roughness are required. Therefore, there has been proposed a recording / reproducing disk substrate using a glass substrate that can effectively obtain a smaller flatness and a smaller surface roughness of the information recording disk substrate, and the disk substrate is fixed and held in place. Holding members such as spacers, shims, and clamps are made of metal, ceramics, or glass that is approximately equivalent to the thermal expansion coefficient of the disk in order to prevent distortion of the disk substrate for information recording due to the difference in thermal expansion from the disk (Japanese Patent Laid-Open No. 61-148667).
[0006]
However, since the ceramic and glass constituting the holding member are generally insulating materials, when the information recording disk substrate is held by these holding members, the disk substrate is charged, and information is read or written. It is known that there is a risk of discharging and generating noise, destroying the recorded contents. Therefore, information recording is performed using a holding member in which a metal film such as aluminum or zinc is coated on the contact surface with the information recording disk substrate, or a holding member made of conductive ceramics in which a conductive material is added to alumina or the like. In some cases, the disk substrate is prevented from being charged (Japanese Patent Laid-Open No. 2-226666).
[0007]
In addition, the Young's modulus of aluminum and aluminum alloy materials used as these disk holding parts is as small as about 70 GPa, and it is becoming difficult to hold the disk precisely by deformation due to the holding of the parts and the ambient temperature. In order to hold the disc precisely, a spacer made of a material having a higher Young's modulus is required.
[0008]
Furthermore, an inexpensive forsterite is as small as about 100 GPa, and a spacer made of a highly rigid material is required to hold the disk substrate with high accuracy.
[0009]
[Problems to be solved by the invention]
It has an electric resistance value that can release static electricity generated in electronic components, and has a large Young's modulus, and has a conductivity that can be used in a precision electronic component structural material or an electronic component manufacturing apparatus. A material having a Young's modulus is intended to be provided at a low cost.
[0010]
For example, in an information recording / reproducing apparatus, a material having a large Young's modulus that can match the thermal expansion coefficient to the thermal expansion coefficient of a recording disk substrate material and has an electrical resistance value that can release static electricity. Is to provide.
[0011]
[Means for Solving the Problems]
The inventor has focused on ceramic materials as a material having a Young's modulus larger than that of metal or the like and having a small electric resistance value.
As a result, the inventors focused on calcium ferrite having a high Young's modulus and found that a nonmagnetic conductive ceramic material can be obtained by adding zinc ferrite thereto.
[0012]
The porcelain of the present invention is a composite ceramic material having an electric resistance of 10 ⁶ Ω · cm or less and a Young's modulus of 180 GPa or more. A composite ceramic material made of zinc oxide ferrite having a small Young's modulus and calcium ferrite having a large Young's modulus can achieve a Young's modulus of 180 GPa to 240 GPa. In addition, they found a material that has electrical conductivity.
[0013]
Since it is possible to obtain a conductive composition having a thermal expansion coefficient similar to the thermal expansion coefficient of the counterpart material when bonded or clamped and bonded to the above conductive ceramics in an electronic component or an electronic component manufacturing apparatus, the temperature change It does not cause damage due to deformation or peeling with the mating material.
That is, the conductive ceramic of the present invention is characterized by containing 95 to 10% by weight of calcium ferrite having a composition of 55 to 33 mol% of iron oxide, 45 to 67 mol% of calcium oxide, and zinc ferrite in the balance. To do.
[0014]
When calcium oxide exceeds 55 mol% in calcium ferrite (calcium oxide is 45 mol% or less), magnetic ferrite may be generated, which is not preferable. Moreover, if the iron oxide of calcium ferrite is less than 33 mol% (calcium oxide exceeds 67 mol%), a crystalline phase of calcium oxide is generated, and the sinterability is remarkably inferior. In order to obtain a composite material having a large Young's modulus, it is preferable to contain a large amount of monocalcium ferrite having a molar ratio of 1: 1.
[0015]
If zinc ferrite is 5 wt% or less, that is, calcium ferrite is 95 wt% or more, the electrical conductivity of the material exceeds 10 ⁶ Ω · cm, and the effect is small in releasing static electricity. Further, when zinc ferrite exceeds 90%, that is, when calcium ferrite is less than 10% by weight, the Young's modulus is less than 180 GPa, which is not suitable as a structural material or a movable part material for precision electronic parts or precision equipment for manufacturing electronic parts. Preferred is a composite ceramic material having a zinc ferrite content of 10 to 50% by weight, an electric resistance of 10 ⁴ Ω · cm or less and a Young's modulus of 200 GPa or more.
[0016]
Moreover, it has been found that a nonmagnetic material having a thermal expansion coefficient of 90 to 118 × 10 ⁻⁷ / ° C. can be provided by changing the ratio of calcium ferrite and zinc ferrite having the above composition.
In addition, the sinterability can be improved by incorporating at least 3 wt% of at least one of MgO, TiO ₂ , MnO, SiO ₂ , ZrO ₂ , and Al ₂ O _{3 in} the porcelain. That is, when at least one of MgO, TiO ₂ , MnO, SiO ₂ , and ZrO ₂ is contained in a total amount of more than 3% by weight, the sinterability is deteriorated and cracks are generated in the material. Because there are things. These oxides may be added separately as a sintering aid, and may be mixed in raw materials such as CaO, Fe ₂ O ₃ , ZnO, and the like due to ball wear such as grinding and mixing.
[0017]
The conductive ceramic of the present invention is, for example, a commercially available Fe ₂ O ₃ having a purity of 99% or more (as impurities, Si, Al, Mn, Ca, Na, S, Cl, Mg, S, Cr, P, Na, Nb and the like), CaCl ₂ , CaCO ₃ , CaFe ₂ O ₄ , Ca ₂ Fe ₂ O _5, etc. are used as the CaO source, and a predetermined amount of these are weighed and then wet-mixed using a ball mill. The dried raw material is calcined at a predetermined temperature for a predetermined time in an oxidizing atmosphere, a predetermined amount of ZnO or a separately synthesized ZnFe ₂ O ₄ raw material is added to the calcined raw material, and alumina balls, zirconia balls, menor balls are added. Etc. to finely pulverize so that the average particle size becomes 2 μm or less. Here, adding Zn ferrite separately prepared to calcined calcium ferrite can adjust the thermal expansion coefficient depending on the amount of Zn ferrite added, and materials with various thermal expansion coefficients can be easily manufactured Because. And after adding a binder to this and performing granulation, the sintered compact with a relative density of 95% or more is obtained by press-molding and baking by a predetermined pressure. As the firing method, firing is performed at 1000 ° C. to 1200 ° C. in an oxidizing atmosphere. Since the conductive material of the present invention can be fired in an oxidizing atmosphere or an atmospheric atmosphere and is made of inexpensive calcium oxide, iron oxide, or zinc oxide, the cost of the manufactured material is low, and electronic components and these It can be provided in large quantities and inexpensively as a component material for manufacturing equipment.
[0018]
In addition, a sintered body having a pore size of 1 μm or less can be obtained by subjecting these sintered bodies to hot isostatic pressing at 1000 to 1200 ° C. in an inert gas atmosphere.
In particular, a high-density sintered body can be obtained by subjecting a pre-sintered body produced in an oxidizing atmosphere firing furnace to hot isostatic pressing.
[0019]
In the present invention, in view of the above problems, magnetic disk substrate holding members such as shims, spacers, and clamps are formed of the above composite compound having a conductivity with a volume resistivity of 10 ⁶ Ω · cm or less.
Further, according to the present invention, a magnetic disk device is constructed by sequentially inserting and fixing the holding member and the information recording disk substrate into a hub made of a conductive material.
[0020]
The reason why the ceramic of the present invention has conductivity is as follows.
For example, Ca ₂ Fe ₂ O ₅ belongs to the tetragonal system, and the iron element is located in two places (Fe _I and Fe _II ) alternately located along the b axis. Fe _I is at a position surrounded by eight oxygen elements (octahedral position), and Fe _II is at a position surrounded by four oxygen atoms (tetrahedral position). This crystal structure can be regarded as consisting of four perovskite structures stacked in the b-axis direction.
[0021]
Here, Fe is stable in Fe ³⁺ in order to maintain its crystal structure and electrical neutrality, but the material produced under the condition that is liable to generate lattice defects is selectively 2 at the tetrahedral or octahedral positions. It is considered that the valence element is generated and the generation of the divalent element causes electron hopping between Fe ²⁺ and Fe ³⁺ , resulting in conductivity.
Further, it is known that in the MO-Fe ₂ O ₃ system, the degree of dissociation of Fe ³⁺ into Fe ²⁺ increases in the composition region rich in Fe ₂ O ₃ and the electrical resistance decreases.
[0022]
However, in a composition system in which CaFe ₂ O ₄ and Ca ₂ Fe ₂ O ₅ are present, these phenomena have not been clarified quantitatively.
The present invention, CaFe ₂ O ₄ and Ca ₂ Fe exist ZnFe ₂ O ₄ in the composition system of the ₂ O _5, moreover the cooling rate is not less than 300 ° C. per hour condition during sintering, Fe ²⁺ more generated It can be considered to have conductivity.
[0023]
Here, the cooling rate is one factor that imparts conductivity, but in addition to this, this dissociation is a reduction action, and it is apparent that the oxygen partial pressure is affected. The lower the oxygen partial pressure, the more dissociation is promoted.
It is considered that a large amount of Fe ²⁺ is generated in a material sintered at an atmospheric furnace oxygen partial pressure of 0.21 atm, and a material having a Young's modulus greater than 180 GPa and 10 ⁶ Ω · cm or less and a non-magnetic property. There is a feature in the point to be obtained.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
"Example 1"
Using commercially available Fe ₂ O ₃ with a purity of 99% or more (including impurities such as Si, Al, Mn, Ca, Na, S, Cl, Mg, S, Cr, P, Na, Nb, etc.) CaCl ₂ , CaCO _3, etc. are used and weighed in a predetermined amount so that these final compositions are as shown in Table 1, and then wet-mixed using a ball mill, dried, and the dried raw material is heated to a predetermined temperature in an oxidizing atmosphere. And calcined for a predetermined time.
[0025]
[Table 1]

[0026]
A predetermined amount of a 99% pure ZnFe ₂ O ₄ raw material synthesized separately is added to the calcined raw material, and finely pulverized using alumina balls, zirconia balls, or menor balls so that the average grain size is 2 μm or less. This pulverization may contain 3% by weight or less of zirconia, alumina, silica, or the like. This was granulated by adding a binder, and then press-molded at a pressure of 0.8 to 2.0 ton / cm ² . Thereafter, firing was performed at a predetermined temperature under normal pressure in an oxidizing atmosphere. The obtained samples were examined for bulk specific gravity, thermal expansion coefficient, pore ratio, sinterability, Young's modulus, and electrical resistance, and the results are shown in Table 2.
[0027]
[Table 2]

[0028]
Here, the bulk specific gravity was determined by the Archimedes method in water, and the thermal expansion coefficient was determined by a thermal expansion coefficient measuring device. The pore generation rate was evaluated by measuring the pore diameter generated on the final lapping surface with 1 μm diamond abrasive grains. The pore ratio was indicated by a cross mark when the average pore diameter exceeded 5 μm, a triangle mark at 3 to 5 μm, a circle mark at 2 to 3 μm, and a circle mark at 2 μm or less. As for sinterability, a water absorption rate of 2% or more is indicated by an X mark, 0% is indicated by a ◯ mark, and the middle thereof is indicated by a △ mark.
[0029]
In the results of Table 2, Samples Nos. 2 to 5, Nos. 7 to 11, and No. 13 are conductive porcelains within the scope of the present invention, and their thermal expansion coefficients are in the range of 90 to 118 × 10 ⁻⁷ / ° C., respectively. Yes, the pore generation rate and sinterability were good. On the other hand, Sample No. 1 has poor calcium sinterability due to the large amount of calcium oxide. In addition, No. 6 had a large electrical resistance value of 10 ⁶ Ω · cm or more and was not suitable as a conductive material. No. 12 has a large amount of zinc ferrite and a Young's modulus as small as 164 GPa, which is a composition outside the scope of the present invention. No. 14 is not suitable as a non-magnetic material because it contains iron oxide.
[0030]
The sintered bodies of Sample Nos. 3, 5, 7, and 9 in Table 2 were subjected to HIP treatment at 1000 to 1200 ° C. and 2000 atmospheres in an argon atmosphere. The obtained samples were designated as Nos. 15, 16, 17, and 18, respectively. These samples were similarly examined for bulk specific gravity, thermal expansion coefficient, pore ratio, sinterability, Young's modulus, and electrical resistance, and are shown in Table 3.
[0031]
[Table 3]

[0032]
"Example 2"
Using commercially available iron oxide Fe ₂ O ₃ having a purity of 99% (including impurities such as Si, Al, Mn, Ca, Na, S, Cl, Mg, S, Cr, P, Na, Nb, etc.), CaO CaCl ₂ , CaCO ₃ or the like is used as the source, ZnO, ZnFe ₂ O ₄ or the like is used as the ZnO source, and the contents of MgO, TiO ₂ , MnO, SiO ₂ , ZrO _{2 in} the sintered body are as shown in Table 4. Then, a predetermined amount was weighed and then wet mixed using a ball mill. Thereafter, each sample was obtained in the same manner as in Example 1. The obtained sample was examined for bulk specific gravity, thermal expansion coefficient, pore ratio, sinterability, electrical resistance and Young's modulus in the same manner as in Example 1, and described in Table 5. No. 26 contained 4% by weight of ZrO ₂ and cracked in the sintered body.
[0033]
[Table 4]

[0034]
Table 5 shows that the inclusion of 3 wt % or less of MgO, TiO ₂ , MnO, SiO ₂ , ZrO ₂ , and Al ₂ O ₃ improves the sinterability and reduces the pore size.
[0035]
[Table 5]

[0036]
In all cases, the volume resistivity value was 10 ⁶ Ω · cm or less, the Young's modulus was 180 GPa or more, and the thermal expansion coefficient was in the range of 90 to 118 × 10 ⁻⁷ / ° C., and the standard value could be satisfied.
[0037]
【The invention's effect】
As described above in detail, the conductive ceramic of the present invention is composed of a composition containing 95 to 10 % by weight of CaFe ₂ O ₄ or Ca ₂ Fe ₂ O ₅ and 5 to 90 % by weight of zinc ferrite. Thus, the electrical resistance of the material is as small as 10 ⁶ Ω · cm or less, and can approach the thermal expansion coefficient of 120 to 90 × 10 ⁻⁷ / ° C. of electronic components, for example, various information recording disks. As a result, even if the conductive porcelain is clamped with an electronic component structure, for example, an information recording disk, no distortion occurs due to temperature rise, the function of the electronic component is not hindered, and the functional element is prevented from being destroyed by charging. it can. In addition, it is possible to reliably prevent the electronic function from being damaged, and to significantly improve the reliability of electronic components and devices.
[0038]
Further, by containing at least one of MgO, TiO ₂ , MnO, SiO ₂ , and ZrO _{2 in} a total amount of 3 % by weight or less, the sinterability is improved, the pore size is reduced, and the mechanical strength is reduced. Can be increased.
For example, in the present invention, a holding member such as a shim, a clamp, and a spacer is formed from a composite compound of calcium ferrite and zinc ferrite having a conductivity having a volume resistivity of 10 ⁶ Ω · cm or less. The thermal expansion coefficient can be set to a value similar to that of the apparatus, and there is no inconvenience associated with a difference in thermal expansion caused by a temperature change during operation of the apparatus, and the static electricity charged on the information recording disk substrate is efficiently released. be able to.
[0039]
Further, according to the present invention, since the information recording disk substrate is sequentially inserted into the hub made of a conductive material using the holding member, the magnetic disk device is configured, so that the flying height of the head with respect to the information recording disk substrate is extremely reduced. The size can be reduced, high-density recording (capacity increase) and miniaturization can be realized, and the static electricity charged to the magnetic disk substrate can be efficiently released through the holding member and hub, thus destroying the recorded contents. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a main part of an information recording / reproducing disk apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gimbal 2 ... Recording / reproducing head 3 ... Fixing screw 4 ... Shim 5 ... Disk substrate 6 ... Hub 7 ... Rotating shaft 8 ... Spacer 9 ... Clamp

Claims (2)

Fe with a purity of 99% or more ₂ O _Three And CaCl as the source of CaO ₂ , CaCO _Three , CaFe ₂ O _Four , Ca ₂ Fe ₂ O _Five And then drying the raw material, and calcining the dried raw material in an oxidizing atmosphere. ₂ O _Four A step of mixing and pulverizing, a step of forming the mixed powder to obtain a molded body, and a firing step of firing the molded body at 1000 to 1200 ° C. and cooling at a cooling rate of 300 ° C./hour or more. A method for producing a conductive ceramic characterized by the above. A holding member for holding the information recording disk medium substrate in a predetermined position is formed of CaFe. ₂ O _Four Or Ca ₂ Fe ₂ O _Five ZnFe containing 95 wt% to 10 wt% of one kind or two kinds of ZnFe ₂ O _Four 5 to 90% by weight, and the volume resistivity is 10 ⁶ Conductive ceramics of Ω · cm or less, or CaO / Fe ₂ O _Three The molar ratio represented by the formula is 45/55 to 67/33, and these CaO and Fe ₂ O _Three A total weight of 95 to 10% by weight, ZnFe ₂ O _Four 5 to 90% by weight, and the volume resistivity is 10 ⁶ A magnetic disk holding member formed of a conductive ceramic having an Ω · cm or less.

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