JPH10158028A - Glass substrate for magnetic disk and magnetic disk - Google Patents
Glass substrate for magnetic disk and magnetic diskInfo
- Publication number
- JPH10158028A JPH10158028A JP31975296A JP31975296A JPH10158028A JP H10158028 A JPH10158028 A JP H10158028A JP 31975296 A JP31975296 A JP 31975296A JP 31975296 A JP31975296 A JP 31975296A JP H10158028 A JPH10158028 A JP H10158028A
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- glass
- magnetic disk
- glass substrate
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は磁気ディスク用ガラ
ス基板および磁気ディスクに関する。The present invention relates to a glass substrate for a magnetic disk and a magnetic disk.
【０００２】[0002]
【従来の技術】磁気ディスクは、基板の上にスパッタ、
メッキ、蒸着等のプロセスにより磁性膜および保護膜が
形成されたものであり、一般にガラスは表面の平滑性に
優れ、硬く、変形抵抗が大きく、かつ表面欠陥が少ない
等の理由から高密度化に適した磁気ディスク用基板の材
料として注目されている。2. Description of the Related Art A magnetic disk is sputtered on a substrate,
A magnetic film and a protective film are formed by processes such as plating and vapor deposition.Generally, glass has high density due to its excellent surface smoothness, hardness, large deformation resistance, and few surface defects. It is attracting attention as a suitable material for a magnetic disk substrate.
【０００３】ガラス基板として比較的安価なアルカリを
含むガラス、たとえばソーダライムシリカガラス、を用
いた場合、特に多湿環境下やエイジング処理をした場合
において磁性膜のピンホール部または磁性膜の周辺部な
ど磁性膜が薄い部分またはガラスが露出した部分からア
ルカリイオンが析出し、これが引きがねとなって磁性膜
が腐食または変色することが見出されている。When a relatively inexpensive glass containing alkali, such as soda lime silica glass, is used as a glass substrate, especially in a humid environment or when subjected to aging treatment, the pinhole portion of the magnetic film or the peripheral portion of the magnetic film is used. It has been found that alkali ions are precipitated from a thin portion of the magnetic film or a portion where the glass is exposed, and this causes a trigger to cause corrosion or discoloration of the magnetic film.
【０００４】また、ガラス基板は従来のアルミニウム合
金等の基板に比べ破壊強度が低い。従って、スピンドル
への装着その他取扱い時において形成されるわずかな傷
の存在が破損につながる。A glass substrate has a lower breaking strength than a conventional substrate made of an aluminum alloy or the like. Therefore, the presence of slight scratches formed during mounting on the spindle or other handling can lead to breakage.
【０００５】そのため、ガラス基板に化学強化を施し表
面に圧縮応力層を形成することが行われているが、それ
だけでは不十分な場合が多い。[0005] For this reason, chemical strengthening is applied to a glass substrate to form a compressive stress layer on the surface, but this is often insufficient.
【０００６】[0006]
【発明が解決しようとする課題】本発明の目的は、上記
欠点を解決し、従来のソーダライムガラスシリカで問題
となっていたガラス基板上の金属磁性膜の腐食を改善す
るとともに、傷がつきにくく破損しにくいガラス基板を
提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, to improve the corrosion of a metal magnetic film on a glass substrate, which has been a problem with conventional soda-lime glass silica, and to improve the scratch resistance. An object of the present invention is to provide a glass substrate which is hard to be broken.
【０００７】[0007]
【課題を解決するための手段】組成が重量％表示で実質
的に、 ＳｉＯ2 ６０〜７０、 Ａｌ2 Ｏ3 １〜１２、 Ｎａ2 Ｏ １〜 ７、 Ｋ2 Ｏ ９〜１６、 Ｎａ2 Ｏ＋Ｋ2 Ｏ １０〜１７、 ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ ８〜１７、 ＺｒＯ2 ０．５〜 ５、 からなるガラスを化学強化処理してなる磁気ディスク用
ガラス基板である。Substantially in [Summary of Composition weight percentages, SiO 2 60~70, Al 2 O 3 1~12, Na 2 O 1~ 7, K 2 O 9~16, Na 2 O + K This is a glass substrate for a magnetic disk obtained by chemically strengthening glass consisting of 2O 10 to 17, MgO + CaO + SrO + BaO 8 to 17 and ZrO 2 0.5 to 5.
【０００８】[0008]
【発明の実施の形態】本発明におけるガラスの組成につ
いて以下に説明する。ＳｉＯ2 はガラスのネットワーク
フォーマーであり、本発明では、６０〜７０重量％とす
る。これが少ないと傷がつきやすくなり、また化学的耐
久性が低下する。多すぎると熔解が困難になる傾向があ
る。より好ましくは６２〜６８重量％である。DESCRIPTION OF THE PREFERRED EMBODIMENTS The composition of the glass according to the present invention will be described below. SiO 2 is a glass network former, and in the present invention, it is 60 to 70% by weight. If the amount is small, the film is easily damaged and the chemical durability is reduced. If it is too large, melting tends to be difficult. More preferably, it is 62 to 68% by weight.
【０００９】Ａｌ2 Ｏ3 はガラスの化学的耐久性を向上
させるとともに、ガラス表層部のアルカリ金属をよりイ
オン半径の大きいアルカリ金属で置換するイオン交換の
速度を増大させ、深い圧縮応力を形成させやすくする作
用があり、本発明では１〜１２重量％とする。これが多
すぎると、熔解が困難になる。より好ましくは７重量％
以下である。Al 2 O 3 not only improves the chemical durability of the glass, but also increases the rate of ion exchange in which the alkali metal in the surface layer of the glass is replaced with an alkali metal having a larger ionic radius, thereby forming a deep compressive stress. In the present invention, the content is 1 to 12% by weight. If this is too much, melting becomes difficult. More preferably 7% by weight
It is as follows.
【００１０】Ｎａ2 Ｏはガラス熔解時の粘性を下げ、溶
解を促進するとともに、化学強化時にイオン交換される
主たる成分となる。本発明では、１〜７重量％とする。
これが多すぎると、化学的耐久性が低下するだけでな
く、Ｎａ+ イオンがガラス基板表面へ多く析出するよう
になるため、磁性膜の耐食性が劣化するおそれがある。
好ましくは４重量％以下である。[0010] Na 2 O lowers the viscosity at the time of glass melting, promotes melting, and is a main component that is ion-exchanged during chemical strengthening. In the present invention, the content is 1 to 7% by weight.
If the amount is too large, not only does the chemical durability decrease, but also a large amount of Na + ions precipitate on the surface of the glass substrate, so that the corrosion resistance of the magnetic film may deteriorate.
It is preferably at most 4% by weight.
【００１１】Ｋ2 Ｏの添加は化学強化時のイオン交換の
速度を向上させる。また、Ｎａ2 Ｏを一部置換すること
により、Ｎａ2 Ｏの添加量を低減させ、磁性膜の耐食性
を高めうる。逆にＫ2 Ｏが多くなり、Ｎａ2 Ｏが相対的
に少なくなりすぎると、イオン交換そのものが起こりに
くくなる。本発明ではＫ2 Ｏの添加量は９〜１６重量％
とする。イオン交換を容易にする観点で、Ｋ2 Ｏは好ま
しくは１２重量％以上、特に１３重量％以上である。ま
た、Ｋ2 Ｏ＋Ｎａ2 Ｏは以上の観点で、１０〜１７重量
％とする。The addition of K 2 O improves the rate of ion exchange during chemical strengthening. Also, by replacing part of the Na 2 O, to reduce the amount of Na 2 O, it may enhance the corrosion resistance of the magnetic film. Conversely, if K 2 O is increased and Na 2 O is relatively decreased too much, ion exchange itself is less likely to occur. In the present invention, the added amount of K 2 O is 9 to 16% by weight.
And From the viewpoint of facilitating ion exchange, K 2 O is preferably at least 12% by weight, particularly at least 13% by weight. Further, K 2 O + Na 2 O is set to 10 to 17% by weight from the above viewpoint.
【００１２】ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯはガ
ラス熔解時の粘性を下げ、溶解しやすくするために合量
で８重量％以上含有される。好ましくは合量で１３重量
％以上である。他方、合量で１７重量％を超えるとガラ
スが傷つきやすくなり、また、失透温度が高くなる傾向
がある。MgO, CaO, SrO and BaO are contained in a total amount of 8% by weight or more in order to lower the viscosity at the time of glass melting and to facilitate melting. Preferably, the total amount is 13% by weight or more. On the other hand, if the total amount exceeds 17% by weight, the glass tends to be damaged, and the devitrification temperature tends to increase.
【００１３】フロート法による成形を容易にするために
は、ＭｇＯは０．５〜９重量％、特に１〜７重量％と
し、ＣａＯは０．５〜１０重量％、特には１〜８重量％
とし、またＭｇＯ＋ＣａＯは５〜１３重量％、特には６
〜１３重量％とすることが好ましい。これらが多すぎる
と、失透温度が高くなりフロート法による成形が困難に
なるおそれがある。In order to facilitate molding by the float method, MgO is 0.5 to 9% by weight, particularly 1 to 7% by weight, and CaO is 0.5 to 10% by weight, particularly 1 to 8% by weight.
And MgO + CaO is 5 to 13% by weight, especially 6%
It is preferable to set it to 13% by weight. If these are too large, the devitrification temperature may increase, and molding by the float method may be difficult.
【００１４】ＳｒＯは必須ではないが熔解性向上のため
に添加できる。フロート法による成形を容易にするため
には、０〜５重量％、特には０〜３重量％とすることが
好ましい。これが多すぎると失透温度が高くなり、ガラ
スが傷つきやすくなるおそれがある。SrO is not essential, but can be added to improve the meltability. In order to facilitate molding by the float method, it is preferably 0 to 5% by weight, particularly preferably 0 to 3% by weight. If the amount is too large, the devitrification temperature increases, and the glass may be easily damaged.
【００１５】ＢａＯも必須ではないが熔解性向上のため
に添加でき、０〜２重量％とすることが好ましい。これ
も多すぎると、失透温度が高くなり、ガラスが傷つきや
すくなるおそれがある。BaO is not essential, but can be added to improve the meltability, and is preferably 0 to 2% by weight. If the amount is too large, the devitrification temperature may increase, and the glass may be easily damaged.
【００１６】ＺｒＯ2 は化学的耐久性を向上させる効果
がある。本発明では０．５〜５重量％とする。化学的耐
久性向上の点で、好ましくは２重量％以上含有する。一
方多すぎると、熔解性が低下し、ガラスが傷つきやすく
なるおそれがある。好ましくは４重量％以下である。ZrO 2 has the effect of improving chemical durability. In the present invention, the content is 0.5 to 5% by weight. From the viewpoint of improving chemical durability, the content is preferably 2% by weight or more. On the other hand, if the amount is too large, the melting property is reduced and the glass may be easily damaged. It is preferably at most 4% by weight.
【００１７】本発明によるガラス基板は上記成分以外
に、ガラスの熔解性、清澄性、成形性を改善するため、
Ａｓ2 Ｏ3 、Ｓｂ2 Ｏ3 、Ｐ2 Ｏ5 、Ｆ、Ｃｌ、ＳＯ3
を合量で２重量％以下添加できる。また、ガラスの化学
的耐久性向上のため、Ｌａ2 Ｏ3 、ＴｉＯ2 、ＳｎＯ
2 、Ｂ2 Ｏ3 を合量で５重量％以下添加できる。またＺ
ｎＯも化学的耐久性向上のために添加できるが、フロー
ト成形性を損なわないために１重量％以下とすることが
好ましい。特に好ましくは、ＺｎＯは実質的には含有さ
れない。The glass substrate according to the present invention, in addition to the above components, improves the melting, clarity and moldability of the glass.
As 2 O 3 , Sb 2 O 3 , P 2 O 5 , F, Cl, SO 3
In a total amount of 2% by weight or less. In order to improve the chemical durability of glass, La 2 O 3 , TiO 2 , SnO
2 , B 2 O 3 can be added in a total amount of 5% by weight or less. Also Z
Although nO can be added to improve chemical durability, it is preferably 1% by weight or less so as not to impair float moldability. Particularly preferably, ZnO is substantially not contained.
【００１８】さらに、Ｆｅ2 Ｏ3 、ＣｏＯ、ＮｉＯ、Ｎ
ｄ2 Ｏ3 、Ｓｅ等の着色材を添加してガラスの色調を調
整できる。この着色材の含有量は合量で１重量％以下が
好ましい。なお、Ｋ2 Ｏ、Ｎａ2 Ｏなどのアルカリ成分
は、この若干量をＬｉ2 Ｏに置換できる。Ｌｉ2 Ｏの含
有量は３重量％以下が好ましい。Further, Fe 2 O 3 , CoO, NiO, N
The color tone of the glass can be adjusted by adding a coloring material such as d 2 O 3 or Se. The total content of the coloring material is preferably 1% by weight or less. It is to be noted that some of the alkali components such as K 2 O and Na 2 O can be replaced with Li 2 O. The content of Li 2 O is preferably 3% by weight or less.
【００１９】本発明においてガラスの脆さを示す指標値
としてはローンらによって提案された脆さ指標値Ｂを使
用する（B.R.Lawn and D.B.Marshall, J.Am.Ceram.So
c.,62(7-8)347-350(1979) ）。ここで、脆さ指標値Ｂは
材料のビッカース硬さＨV と破壊靱性値ＫC から数１に
より定義される。In the present invention, a brittleness index value B proposed by Lawn et al. Is used as an index value indicating the brittleness of glass (BRLawn and DBMarshall, J. Am. Ceram. So
c., 62 (7-8) 347-350 (1979)). Here, fragility index value B is defined by 1 the number of Vickers hardness H V and fracture toughness value K C of the material.
【００２０】[0020]
【数１】Ｂ＝ＨV ／ＫC （１）B = H V / K C (1)
【００２１】本発明のガラスの脆さ指標値は７４００ｍ
-1/2以下であることが好ましく、より好ましくは７３０
０ｍ-1/2以下である。また、本発明のガラスは、化学強
化が可能である。化学強化は通常、硝酸カリウム融液も
しくは、硝酸カリウムと硝酸ナトリウムの混合融液にガ
ラス板を浸漬することによって行われる。本発明のガラ
スにおいては化学強化によって、表面から５μｍ以上、
特には１０μｍ以上の厚さの圧縮圧力層を生じさせるこ
とができる。The brittleness index value of the glass of the present invention is 7400 m
-1/2 or less, more preferably 730
0 m -1/2 or less. Further, the glass of the present invention can be chemically strengthened. Chemical strengthening is usually performed by immersing a glass plate in a potassium nitrate melt or a mixed melt of potassium nitrate and sodium nitrate. In the glass of the present invention, by chemical strengthening, 5 μm or more from the surface,
In particular, a compression pressure layer having a thickness of 10 μm or more can be generated.
【００２２】上述のように本発明のガラスは、傷がつき
にくいうえ、従来の磁気ディスク用ガラスと同等以上の
化学強化が可能であるため、製造工程中や、製品として
使用中の破損おそれを大幅に減じることができる。な
お、本発明のガラスは典型的には密度が２．７ｇ／ｃｃ
以下、特には２．６ｇ／ｃｃ以下である。このことも落
下時の衝撃を小さくし、破損のおそれを小さくしてい
る。As described above, the glass of the present invention is not easily scratched and can be chemically strengthened at the same level or more than conventional glass for magnetic disks, so that there is no possibility of breakage during the manufacturing process or during use as a product. It can be greatly reduced. The glass of the present invention typically has a density of 2.7 g / cc.
Below, especially 2.6 g / cc or less. This also reduces the impact at the time of dropping and reduces the possibility of breakage.
【００２３】また、本発明のガラスの１つの重要な特徴
として、フロート成形が可能なことがある。すなわち、
フロート成形時の成形温度である１０4 ポイズの粘性を
示す温度に比べて失透温度が低い。従って、失透などの
不具合を生じることなく、フロート成形が可能である。Another important feature of the glass of the present invention is that float molding is possible. That is,
The devitrification temperature is lower than the temperature showing a viscosity of 10 4 poise, which is the molding temperature during float molding. Accordingly, float molding can be performed without causing problems such as devitrification.
【００２４】本発明のガラスは、たとえば、次のような
方法で製造できる。すなわち、通常使用される各成分の
原料を目標成分になるように調合し、これを熔解炉に連
続的に投入し、１５００〜１６００℃に加熱して、熔融
する。この熔融ガラスをフロート法により所定の板厚に
成形し、徐冷後切断する。The glass of the present invention can be produced, for example, by the following method. That is, a raw material of each component usually used is prepared so as to become a target component, and this is continuously charged into a melting furnace, heated to 1500 to 1600 ° C. and melted. This molten glass is formed into a predetermined thickness by a float method, and then cooled and cut.
【００２５】本発明のガラス基板においては、所定のサ
イズに切断されたガラス板を化学強化処理する。化学強
化処理は公知の方法で行えばよい。すなわち、４００〜
５３０℃の硝酸カリウムまたはこれと硝酸ナトリウムと
の混合液にガラス物品を２〜２０時間程度浸漬した後取
り出し、徐冷することにより行える。In the glass substrate of the present invention, a glass plate cut to a predetermined size is subjected to a chemical strengthening treatment. The chemical strengthening treatment may be performed by a known method. That is, 400-
This can be performed by immersing the glass article in 530 ° C. potassium nitrate or a mixed solution of sodium nitrate and potassium nitrate for about 2 to 20 hours, taking out the glass article, and gradually cooling it.
【００２６】本発明の磁気ディスク用ガラス基板によっ
て、磁気ディスクを形成するには、ガラス基板の上に順
次、下地層、磁性層、保護層、潤滑層を設ければよい。In order to form a magnetic disk using the glass substrate for a magnetic disk of the present invention, an underlayer, a magnetic layer, a protective layer, and a lubricating layer may be sequentially provided on the glass substrate.
【００２７】本発明で用いられる磁気記録層としての磁
性層としては、Ｃｏ−Ｃｒ系、Ｃｏ−Ｃｒ−Ｐｔ系、Ｃ
ｏ−Ｎｉ−Ｃｒ系、Ｃｏ−Ｎｉ−Ｃｒ−Ｐｔ系、Ｃｏ−
Ｎｉ−Ｐｔ系、Ｃｏ−Ｃｒ−Ｔａ系などのＣｏ系合金を
好ましく採用できる。耐久性や磁気特性を向上するため
に、磁性層の下に設けられる下地層としては、Ｎｉ層、
Ｎｉ−Ｐ層、Ｃｒ層、ＳｉＯ2 層などを採用できる。The magnetic layer as the magnetic recording layer used in the present invention may be a Co—Cr-based, Co—Cr—Pt-based,
o-Ni-Cr-based, Co-Ni-Cr-Pt-based, Co-
Co-based alloys such as Ni-Pt-based and Co-Cr-Ta-based can be preferably used. In order to improve durability and magnetic characteristics, a Ni layer,
Ni-P layer, Cr layer, such as SiO 2 layer can be adopted.
【００２８】本発明では、Ｃｒ層、Ｃｒ合金層、他の材
料からなる金属または合金層を磁性層の上または下に設
けうる。In the present invention, a Cr layer, a Cr alloy layer, and a metal or alloy layer made of another material may be provided above or below the magnetic layer.
【００２９】保護層としては、５０〜１０００Åの厚み
のカーボンまたはシリカの層が使用でき、潤滑層を形成
するためには、３０Å程度の厚みのパーフルオロポリエ
ーテル系の液体潤滑剤が使用できる。As the protective layer, a carbon or silica layer having a thickness of 50 to 1000 ° can be used, and a perfluoropolyether liquid lubricant having a thickness of about 30 ° can be used to form a lubricating layer.
【００３０】[0030]
＜板状ガラスの作成＞表１に示した例１〜４の４種類の
組成について常法に従い調合・混合し、ガラスバッチを
調製した。次いで容量約５００ｍｌのＰｔ−Ｒｈ１０％
坩堝にガラスバッチを入れ１５００℃で均質化のため約
１時間の撹拌を含め約４時間熔解し、カーボン板上に流
し出して板状とし徐冷後、常法に従い切断・研磨して約
１ｍｍ厚の板状ガラスサンプルを得た。なお、例１〜５
は実施例であり、例６、７は比較例である。<Preparation of Sheet Glass> Four kinds of compositions of Examples 1 to 4 shown in Table 1 were prepared and mixed according to a conventional method to prepare a glass batch. Then, about 500 ml of Pt-Rh 10%
Put the glass batch in a crucible, melt at 1500 ° C for about 4 hours including homogenization for about 1 hour, pour it out onto a carbon plate, make it into a plate, gradually cool it, cut and polish it according to the usual method, about 1mm A thick sheet glass sample was obtained. Examples 1 to 5
Are Examples, and Examples 6 and 7 are Comparative Examples.
【００３１】これらのガラスの失透温度、１０4 ポイズ
の温度、１０2 ポイズの温度、歪点温度、脆さ指標値を
測定し、表１に併記した。ついで例１〜５の板状ガラス
サンプルを切断・研磨して外径６５ｍｍ、内径２０ｍ
ｍ、厚さ０．６３５ｍｍのドーナツ状の円形ガラスディ
スク基板を各２０枚作成した。The devitrification temperature, the temperature of 10 4 poise, the temperature of 10 2 poise, the strain point temperature, and the brittleness index value of these glasses were measured and are shown in Table 1. Next, the plate-shaped glass samples of Examples 1 to 5 were cut and polished to obtain an outer diameter of 65 mm and an inner diameter of 20 m.
Twenty donut-shaped circular glass disk substrates each having a thickness of 0.635 mm were prepared.
【００３２】脆さ指標値（単位：ｍ-1/2）は次のように
して求めた。脆さ指標値をガラスに適用する際の大きな
問題は破壊靱性値ＫC が正確に評価しにくいことであ
る。しかし、本出願人は、いくつかの手法を検討した結
果、ビッカース圧子を押し込んだときにガラス表面に残
る圧子の痕の大きさと痕の四隅から発生するクラックの
長さとの関係から脆さを定量的に評価できることを見出
している。その関係式は式（２）により定義される。こ
こで、Ｐはビッカース圧子の押し込み荷重でありａ、ｃ
は、それぞれ、ビッカース圧痕の対角長および四隅から
発生するクラックの長さ（圧子の痕を含む対称な２つの
クラックの全長）である。各種ガラスの表面に打ち込ん
だビッカース圧痕の寸法と数２を用いて、脆さ指標値を
評価する。The brittleness index value (unit: m -1/2 ) was determined as follows. A major problem when applying the brittleness index value to glass is that it is difficult to accurately evaluate the fracture toughness value K C. However, as a result of studying several methods, the present applicant has determined the brittleness from the relationship between the size of the indenter mark remaining on the glass surface when the Vickers indenter is pushed in and the length of cracks generated from the four corners of the indenter. Have been found to be able to be evaluated. The relational expression is defined by Expression (2). Here, P is the pushing load of the Vickers indenter, a, c
Are the diagonal lengths of the Vickers indentations and the lengths of the cracks generated from the four corners (total lengths of two symmetric cracks including the indenter indentations). The brittleness index value is evaluated by using the dimensions of Vickers indents and the number 2 of the Vickers indented on the surface of each glass.
【００３３】[0033]
【数２】 ｃ／ａ＝０．００５６Ｂ2/3 Ｐ1/6 （２）## EQU2 ## c / a = 0.0056B 2/3 P 1/6 (2)
【００３４】例７のガラス基板は、脆さ指標値が７４０
０ｍ-1/2を超えるので、傷がつきやすく回転時に破損す
る確率が大きいことになる。The glass substrate of Example 7 had a brittleness index of 740.
Since it exceeds 0 m -1/2 , it is easily damaged and has a high probability of being damaged during rotation.
【００３５】＜化学強化性テスト＞上記ガラスディスク
の基板各１０枚について化学強化処理を行った。すなわ
ち、例１〜４および例７については４８０℃の熔融硝酸
カリウム塩に、また、例６については４５０℃の熔融硝
酸カリウム塩に、それぞれ１０時間浸漬し、化学強化処
理を行った。上記各ガラスディスク基板について、東芝
硝子製の主表面応力計ＦＳＷ−６０にて表面圧縮応力層
の厚みを測定した結果を表１に併記する。表から明らか
なように本発明によるガラス基板は１０μｍ以上の圧縮
応力層を生じさせることができる。<Chemical Strengthening Test> Each of the ten glass disk substrates was chemically strengthened. That is, each of Examples 1 to 4 and Example 7 was immersed in a molten potassium nitrate salt at 480 ° C., and Example 6 was immersed in a molten potassium nitrate salt at 450 ° C. for 10 hours to perform a chemical strengthening treatment. Table 1 also shows the results of measuring the thickness of the surface compressive stress layer of each of the above glass disk substrates using a main surface stress meter FSW-60 manufactured by Toshiba Glass. As is clear from the table, the glass substrate according to the present invention can generate a compressive stress layer of 10 μm or more.
【００３６】＜磁気記録媒体の耐湿テスト＞上記未強化
品および強化品のそれぞれの主表面上にスパッタ法によ
り厚さ約５００ÅのＣｒからなる下地層を形成した後、
厚さ約６００ÅのＣｏ−３０原子％Ｎｉ合金磁性層を形
成し、その上に厚さ約３００Åのカーボン保護膜を形成
し、さらにその上にパーフルオロポリエーテル系の液体
潤滑剤を塗布することにより磁気記録媒体を得た。これ
らについて８０℃、９０％ＲＨの雰囲気条件で１００時
間保持することにより耐湿テストを実施した。<Moisture Resistance Test of Magnetic Recording Medium> An underlayer made of Cr having a thickness of about 500 ° was formed on the main surface of each of the unreinforced product and the reinforced product by a sputtering method.
Forming a Co-30 atomic% Ni alloy magnetic layer having a thickness of about 600 Å, forming a carbon protective film having a thickness of about 300 そ の thereon, and further applying a perfluoropolyether-based liquid lubricant thereon; Thus, a magnetic recording medium was obtained. A moisture resistance test was performed on these samples by maintaining them at 80 ° C. and 90% RH for 100 hours.
【００３７】表より明らかなように、本発明によるガラ
ス基板の脆さ指標値は、７４００ｍ-1/2以下であり、傷
がつきにくい。そのため、スピンドルへの装着その他取
扱い時においても傷がつきにくく回転時に破損が起こる
等の問題がない。更に、例１〜５のガラス基板からなる
磁気記録媒体は未強化品、強化品ともに変色が認められ
なかった。また、失透温度は、フロート法の成形粘度で
ある１０4 ポイズに相当する温度よりも低く、フロート
法による製造に好適であることがわかる。As is clear from the table, the brittleness index value of the glass substrate according to the present invention is 7400 m -1/2 or less, and the glass substrate is hardly damaged. For this reason, there is no problem such as being less likely to be damaged during mounting on the spindle or other handling and causing breakage during rotation. Further, in the magnetic recording media comprising the glass substrates of Examples 1 to 5, no discoloration was observed in both the unreinforced product and the reinforced product. Further, the devitrification temperature is lower than the temperature corresponding to 10 4 poise, which is the molding viscosity of the float method, and it can be seen that it is suitable for production by the float method.
【００３８】一方、例６のガラス基板からなる未強化品
磁気記録媒体はディスクの内周および外周の端面から２
〜３ｍｍの範囲にわたってＣｏ−Ｎｉ合金層とガラスと
の界面から面内にかけて変色が認められ、例６のガラス
基板からなる強化品磁気記録媒体では同じく１〜２ｍｍ
の範囲にわたって変色が認められた。On the other hand, the unstrengthened magnetic recording medium made of the glass substrate of Example 6 is 2 mm from the inner and outer end faces of the disk.
Discoloration was observed from the interface between the Co—Ni alloy layer and the glass over the range of up to 3 mm from the interface to the in-plane.
Discoloration was observed over the range.
【００３９】[0039]
【表１】 [Table 1]
【００４０】[0040]
【発明の効果】本発明の高強度な磁気ディスク用ガラス
基板はソーダライムシリカガラスを使用したガラス基板
に比べ、傷がつきにくく、耐食性および耐エージング性
がきわめて優れる。さらに、本発明の磁気ディスク用ガ
ラス基板は、フロート法による成形にも適するものであ
る。The glass substrate for a high-strength magnetic disk of the present invention is less likely to be damaged and has extremely excellent corrosion resistance and aging resistance as compared with a glass substrate using soda lime silica glass. Further, the glass substrate for a magnetic disk of the present invention is suitable for molding by a float method.
Claims (8)
なるガラスを化学強化処理してなる磁気ディスク用ガラ
ス基板。1. A substantially in composition by weight percentages, SiO 2 60~70, Al 2 O 3 1~12, Na 2 O 1~ 7, K 2 O 9~16, Na 2 O + K 2 O 10~ 17, a glass substrate for a magnetic disk obtained by chemically strengthening a glass consisting of MgO + CaO + SrO + BaO 8-17 and ZrO 2 0.5-5.
記載の磁気ディスク用ガラス基板。2. The method according to claim 1, wherein the density is 2.7 g / cc or less.
The glass substrate for a magnetic disk according to the above.
求項１または２記載の磁気ディスク用ガラス基板。3. The glass substrate for a magnetic disk according to claim 1, wherein the brittleness index value is 7400 m −1/2 or less.
ラス基板。4. A substantially in composition by weight percentages, SiO 2 60~70, Al 2 O 3 1~ 7, Na 2 O 1~ 7, K 2 O 9~16, Na 2 O + K 2 O 10~ 17, MgO 0.5~ 9, CaO 0.5~10 , SrO 0~ 5, BaO 0~ 2, MgO + CaO 5~13, ZrO 2 0.5~ 5, according to claim 1, wherein consisting Glass substrate for magnetic disk.
用ガラス基板。5. The composition is substantially expressed in terms of% by weight: SiO 2 60 to 70, Al 2 O 3 1 to 7, Na 2 O 1 to 7, K 2 O 12 to 16, Na 2 O + K 2 O 13 to The magnetic disk according to claim 1, 2, 3, or 4, comprising: MgO 1-7, CaO 1-8, SrO 0-3, BaO 0-1, MgO + CaO 6-13, ZrO 2 0.5-4. For glass substrates.
有する請求項１、２、３、４または５記載の磁気ディス
ク用ガラス基板。6. The glass substrate for a magnetic disk according to claim 1, further comprising a compressive stress layer having a thickness of 5 μm or more from the surface.
れと硝酸ナトリウムとの混合液にガラスを１〜２０時間
浸漬することによって化学強化処理されていることを特
徴とする請求項１、２、３、４、５または６記載の磁気
ディスク用ガラス基板。7. A chemical strengthening treatment by dipping glass in a mixed solution of potassium nitrate or sodium nitrate at 400 to 530 ° C. for 1 to 20 hours. 7. The glass substrate for a magnetic disk according to 4, 5, or 6.
載の磁気ディスク用ガラス基板の上に、順次、下地層、
磁性層、保護層、潤滑層を設けてなる磁気ディスク。8. A magnetic disk according to claim 1, 2, 3, 4, 5, 6 or 7, wherein an underlayer,
A magnetic disk provided with a magnetic layer, a protective layer, and a lubricating layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31975296A JP4081826B2 (en) | 1996-11-29 | 1996-11-29 | Glass substrate for magnetic disk, magnetic disk and donut-shaped circular glass disk substrate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31975296A JP4081826B2 (en) | 1996-11-29 | 1996-11-29 | Glass substrate for magnetic disk, magnetic disk and donut-shaped circular glass disk substrate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10158028A true JPH10158028A (en) | 1998-06-16 |
| JP4081826B2 JP4081826B2 (en) | 2008-04-30 |
Family
ID=18113783
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31975296A Expired - Fee Related JP4081826B2 (en) | 1996-11-29 | 1996-11-29 | Glass substrate for magnetic disk, magnetic disk and donut-shaped circular glass disk substrate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4081826B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6436859B1 (en) | 1999-03-25 | 2002-08-20 | Central Glass Company, Limited | Glass composition and ion exchange strengthened glass article produced from same |
| WO2004041740A1 (en) * | 2002-11-07 | 2004-05-21 | Hoya Corporation | Substrate for information recording medium, information recording medium and method for manufacturing same |
| JP2005302289A (en) * | 2005-05-18 | 2005-10-27 | Hoya Corp | Glass substrate for information recording medium and magnetic information recording medium using the same |
| US8222170B2 (en) | 2001-05-31 | 2012-07-17 | Hoya Corporation | Glass substrate for information recording medium and magnetic information recording medium to which the glass substrate is applied |
| JP2015096465A (en) * | 2014-12-17 | 2015-05-21 | Hoya株式会社 | Glass substrate |
| JP2016117649A (en) * | 2009-04-02 | 2016-06-30 | 旭硝子株式会社 | Glass for information recording medium substrate, glass substrate for information recording medium and magnetic disc |
-
1996
- 1996-11-29 JP JP31975296A patent/JP4081826B2/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6436859B1 (en) | 1999-03-25 | 2002-08-20 | Central Glass Company, Limited | Glass composition and ion exchange strengthened glass article produced from same |
| US8222170B2 (en) | 2001-05-31 | 2012-07-17 | Hoya Corporation | Glass substrate for information recording medium and magnetic information recording medium to which the glass substrate is applied |
| US20130040169A1 (en) * | 2001-05-31 | 2013-02-14 | Hoya Corporation | Glass substrate for information recording medium and magnetic information recording medium to which the glass substrate is applied |
| US8697592B2 (en) | 2001-05-31 | 2014-04-15 | Hoya Corporation | Glass substrate for information recording medium and magnetic information recording medium to which the glass substrate is applied |
| WO2004041740A1 (en) * | 2002-11-07 | 2004-05-21 | Hoya Corporation | Substrate for information recording medium, information recording medium and method for manufacturing same |
| US7601446B2 (en) | 2002-11-07 | 2009-10-13 | Hoya Corporation | Substrate for information recording medium, information recording medium and method for manufacturing same |
| JP2005302289A (en) * | 2005-05-18 | 2005-10-27 | Hoya Corp | Glass substrate for information recording medium and magnetic information recording medium using the same |
| JP2016117649A (en) * | 2009-04-02 | 2016-06-30 | 旭硝子株式会社 | Glass for information recording medium substrate, glass substrate for information recording medium and magnetic disc |
| JP2015096465A (en) * | 2014-12-17 | 2015-05-21 | Hoya株式会社 | Glass substrate |
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| Publication number | Publication date |
|---|---|
| JP4081826B2 (en) | 2008-04-30 |
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