JP4726400B2 - Manufacturing method of glass substrate - Google Patents
Manufacturing method of glass substrate Download PDFInfo
- Publication number
- JP4726400B2 JP4726400B2 JP2003153238A JP2003153238A JP4726400B2 JP 4726400 B2 JP4726400 B2 JP 4726400B2 JP 2003153238 A JP2003153238 A JP 2003153238A JP 2003153238 A JP2003153238 A JP 2003153238A JP 4726400 B2 JP4726400 B2 JP 4726400B2
- Authority
- JP
- Japan
- Prior art keywords
- glass substrate
- glass
- substrate
- thermal shock
- thermal expansion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000011521 glass Substances 0.000 title claims description 124
- 239000000758 substrate Substances 0.000 title claims description 110
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 230000035939 shock Effects 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 18
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 12
- 230000009477 glass transition Effects 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 11
- 238000005728 strengthening Methods 0.000 claims description 10
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 9
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 9
- 229910052708 sodium Inorganic materials 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- -1 lanthanoid metal oxides Chemical class 0.000 claims description 5
- 229910052744 lithium Inorganic materials 0.000 claims description 5
- 229910044991 metal oxide Inorganic materials 0.000 claims description 5
- 229910052747 lanthanoid Inorganic materials 0.000 claims description 4
- 229910052700 potassium Inorganic materials 0.000 claims description 4
- 229910018068 Li 2 O Inorganic materials 0.000 claims description 3
- 150000001875 compounds Chemical class 0.000 claims description 3
- 239000010408 film Substances 0.000 description 32
- 239000010410 layer Substances 0.000 description 20
- 230000003287 optical effect Effects 0.000 description 15
- 239000003513 alkali Substances 0.000 description 13
- 230000000694 effects Effects 0.000 description 13
- 239000000126 substance Substances 0.000 description 11
- 238000004891 communication Methods 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 238000005498 polishing Methods 0.000 description 8
- 239000011241 protective layer Substances 0.000 description 8
- 230000003746 surface roughness Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 238000004140 cleaning Methods 0.000 description 6
- 230000001965 increasing effect Effects 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 229910001149 41xx steel Inorganic materials 0.000 description 5
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 5
- 230000000704 physical effect Effects 0.000 description 5
- 238000004544 sputter deposition Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 239000000155 melt Substances 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 238000001771 vacuum deposition Methods 0.000 description 4
- 229910000943 NiAl Inorganic materials 0.000 description 3
- NPXOKRUENSOPAO-UHFFFAOYSA-N Raney nickel Chemical compound [Al].[Ni] NPXOKRUENSOPAO-UHFFFAOYSA-N 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000007772 electroless plating Methods 0.000 description 3
- 238000007373 indentation Methods 0.000 description 3
- 238000005342 ion exchange Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 229910000599 Cr alloy Inorganic materials 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003989 dielectric material Substances 0.000 description 2
- 238000010828 elution Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 239000006249 magnetic particle Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000010702 perfluoropolyether Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- HUAUNKAZQWMVFY-UHFFFAOYSA-M sodium;oxocalcium;hydroxide Chemical compound [OH-].[Na+].[Ca]=O HUAUNKAZQWMVFY-UHFFFAOYSA-M 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000005341 toughened glass Substances 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 238000007088 Archimedes method Methods 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910002441 CoNi Inorganic materials 0.000 description 1
- 229910018979 CoPt Inorganic materials 0.000 description 1
- 229910000684 Cobalt-chrome Inorganic materials 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910002546 FeCo Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000005456 alcohol based solvent Substances 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000003426 chemical strengthening reaction Methods 0.000 description 1
- 239000005345 chemically strengthened glass Substances 0.000 description 1
- 239000010952 cobalt-chrome Substances 0.000 description 1
- 239000008119 colloidal silica Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000004031 devitrification Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000000156 glass melt Substances 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 238000007733 ion plating Methods 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000006060 molten glass Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 239000012788 optical film Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 238000005019 vapor deposition process Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
- C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/095—Glass compositions containing silica with 40% to 90% silica, by weight containing rare earths
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum
Description
【０００１】
【発明の属する技術分野】
本発明は特定のガラス組成物を用いたガラス基板の製造方法に関し、より詳細には磁気ディスク、光磁気ディスク、ＤＶＤ、ＭＤなどの情報記録用媒体や光通信用素子などの基板として用いるガラス基板の製造方法に関するものである。
【０００２】
【従来の技術】
従来、磁気ディスク用基板としては、デスクトップ用コンピュータやサーバなどの据え置き型にはアルミニウム合金が、他方ノート型コンピュータやモバイル型コンピュータなどの携帯型にはガラス基板が一般に使用されていたが、アルミニウム合金は変形しやすく、また硬さが不十分であるため研磨後の基板表面の平滑性が十分とは言えなかった。さらに、ヘッドが機械的に磁気ディスクに接触する際、磁性膜が基板から剥離しやすいという問題もあった。そこで、変形が少なく、平滑性が良好で、かつ機械的強度の大きいガラス基板が携帯型のみならず据え置き型の機器やその他の家庭用情報機器にも今後広く使用されていくものと予測されている。
【０００３】
ガラス基板としては、基板表面のアルカリ元素を他のアルカリ元素と置換することにより圧縮歪みを発生させ、機械的強度を向上させた化学強化ガラスが知られている。しかし化学強化ガラスでは煩雑なイオン交換工程が必要であり、またイオン交換後の再加工が不可能であるため製造歩留を上げることが難しかった。また、ガラス基板にイオン交換性を持たせるために、アルカリイオンの基板中での移動が容易となるようにしていたので、基板表面のアルカリイオンが、磁性膜を成膜する際の加熱工程時に表面に移動して溶出したり、あるいは磁性膜を侵食したり、磁性膜の付着強度を劣化させたりする問題があった。
【０００４】
一方、化学強化処理を行わない一般的なガラス基板としてはソーダライム基板があるが、このソーダライム基板を情報記録用基板として用いるには機械的強度、化学的耐久性が不十分であった。また、液晶基板などに使用されているガラス材料では、高温での熱安定性を維持するため無アルカリあるいは低アルカリ化によって線熱膨張係数を低く抑えているので、SUS鋼などでできたクランプやスピンドルモータ部材の線熱膨張係数との差が大きく、記録媒体の記録装置への取付け時や情報記録時に不具合が生じることがあった。また機械的強度が不十分であるため情報記録用基板へ適用は困難であった。
【０００５】
また光フィルタや光スイッチなどの光通信用素子でも基板としてガラス基板が用いられているが、ガラス基板から溶出したアルカリ成分によって前記素子が劣化することがあった。また、ガラス基板上に形成される膜の密度が大きくなるほど、温度・湿度の変化による波長シフトが抑制されるところ、従来広く用いられている真空蒸着法では形成できる膜の密度に限界があった。
【０００６】
さらには、ガラス基板を情報記録用として用いる場合に、情報記録用膜をガラス基板上に形成する際、表面に加わえられる圧力や加熱、衝撃によりガラス基板にクラックが入り、製品の歩留まりが低下することがあった。
【０００７】
【特許文献１】
特開２００１−１９４６６号公報（特許請求の範囲の欄、表１〜表５）
【０００８】
【発明が解決しようとする課題】
本発明はこのような従来の問題に鑑みてなされたものであり、その目的とするところは、強化処理を行うことなく熱衝撃に強いガラス組成物を用いたガラス基板の製造方法を提供することにあり、さらには高い機械的強度を有し、また線熱膨張係数がモータ部材のそれに近く、さらには高い破壊靭性を有するガラス組成物を用いたガラス基板の製造方法を提供することにある。
【０００９】
【課題を解決するための手段】
本発明によれば、重量％で、ＳｉＯ2：６２．５〜７５％、Ａｌ2Ｏ3：１〜２０％、Ｂ2Ｏ3：０〜８％（ただし、ゼロを含む）、ＳｉＯ2＋Ａｌ2Ｏ3＋Ｂ2Ｏ3：６０〜９０％、Ｌｉ２Ｏ：０．１〜１５％、Ｎａ２Ｏ：０．１〜１５％、Ｋ２Ｏ：０．１〜１０％、Ｒ2Ｏ（Ｒ＝Ｌｉ，Ｎａ，Ｋ）の総量：０．３〜１８％、Ｒ’Ｏ（Ｒ’＝Ｍｇ, Ｃａ,Ｚｎ）の総量：０〜３．０％（ただし、ゼロを含む）、ＴｉＯ ２ を必須成分として、ＴｉＯ2＋ＺｒＯ2＋ＬｎxＯy：０〜１２％（ただし、ＬｎxＯyはランタノイド金属酸化物及びＹ2Ｏ3，Ｎｂ2Ｏ5，Ｔａ2Ｏ5からなる群より選ばれた少なくとも１つの化合物を意味する）の各ガラス成分を有し、ＢａＯ、及びＳｒＯを何れも含有しないガラス組成物を用い、強化処理を行うことなく、下記式（１）から算出される熱衝撃度数（Ｈ）が４０より大きいガラス基板を製造することを特徴とするガラス基板の製造方法が提供される。なお、以下「％」は特に断りのない限り「重量％」を意味するものとする。
熱衝撃度数(H)=500×(1/(α×107))2＋30×(Kc)8＋0.05×(E/ρ)＋0.02×Tg・・・（１）
（式中、α:線熱膨張係数（２５〜１００℃、１／℃）、Ｋｃ:破壊靭性値（ＭＰａ・ｍ１／２）、Ｅ/ρ:比弾性率(Ｇｐａ)、Ｔｇ:ガラス転移温度(℃)）
【００１１】
ここで耐熱衝撃性の観点から、強化処理を行うことなく、前記式（１）から算出される熱衝撃度数を４０より大きくすることが望ましい。
【００１２】
強化処理を行うことなく、比弾性率Ｅ／ρを３０Ｇｐａ以上、破壊靭性値Ｋｃを１．００（ＭＰａ・ｍ １／２ ）以上、線熱膨張係数αを４０×１０-7〜９０×１０-7／℃、ガラス転移温度Ｔｇを５００℃以上とするのが好ましい。
【００１３】
また、表面積／体積（以下、「比表面積」と記すことがある）を１〜５０／ｍｍの範囲とし、最も薄い部分の厚みを２ｍｍ以下とするのが好ましい。
【００１４】
なお、比弾性率（Ｅ／ρ）はヤング率Ｅを比重ρで割った値であって、ヤング率はＪＩＳ Ｒ １６０２ファインセラミックスの弾性試験方法の動的弾性率試験方法に準じて測定し、比重ρはアルキメデス法により２５℃の蒸留水中で測定したものである。また破壊靭性値Ｋｃは、ビッカース硬度試験機を用いて、荷重５００ｇ、負荷時間１５ｓｅｃの条件下にてビッカース圧子にて圧痕をつけ下記式から算出した（図２を参照）。
Ｋｃ＝0.018（Ｅ／Ｈｖ）1/2（Ｐ／Ｃ3/2）＝0.026Ｅ1/2Ｐ1/2ａ／Ｃ3/2
（式中、Ｋｃ：破壊靭性値（Pa・m1/2）、Ｅ：弾性率(Pa)、Ｈｖ：ビッカース硬度(Pa)、Ｐ：押し込み荷重(N)、Ｃ：クラック長さの平均の半分(m)、ａ：圧痕の対角線長さの平均の半分(m)）
【００１５】
線熱膨張係数Ａは、示差膨張測定装置を用いて、荷重：５ｇ、温度範囲：２５〜１００℃、昇温速度：５℃／ｍｉｎの条件で測定した値である。ガラス転移点Ｔｇは、粉末状に調整したガラス試料を示差熱測定装置を用いて、荷重５ｇで、２５〜７００℃の温度範囲を５℃／ｍｉｎの昇温率で加熱し測定した値である。また、比表面積Ｓ／Ｖは、ガラス基板が円盤状の場合には例えば図３に示すようにして算出する。
【００１６】
【発明の実施の形態】
本発明者等は、強化処理を行うことなく耐熱衝撃性を高めるべく鋭意検討を重ねた。その結果、ガラスのマトリックス成分としてＳｉＯ2を用い、そこに所定量のＡｌ2Ｏ3及びＢ2Ｏ3を含有させてガラスの骨格を形成することにより所定の剛性が得られ、またＲ2Ｏ（Ｒ：Ｌｉ，Ｎａ，Ｋ）及びＲ’Ｏ（Ｒ’：Ｍｇ,Ｃａ,Ｚｎ）の総量、さらには（ＴｉＯ2＋ＺｒＯ2＋ＬｎxＯy）の総量を所定範囲とすることにより高い耐熱衝撃性を得られることを見出し本発明をなすに至った。
【００１７】
以下、本発明に係るガラス組成物の成分についてその限定した理由について説明する。まずＳｉＯ2はガラスのマトリックスを形成する成分である。その含有量が６２．５％未満では、ガラスの構造が不安定となり化学的耐久性が劣化すると共に、溶融時粘性特性が悪くなり成形性に支障を来す。一方含有量が７５％を超えると、溶融性が悪くなり生産性が低下すると共に、十分な剛性が得られなくなる。そこで含有量を６２．５〜７５％の範囲と定めた。より好ましい範囲は６２．５〜７４％の範囲である。
【００１８】
Ａｌ2Ｏ3はガラスのマトリックス中に入り、ガラス構造を安定化させ、化学的耐久性を向上させる効果を奏する。含有量が１％未満では十分な安定化効果が得られない。他方２０％を超えると溶融性が悪くなり、生産性に支障を来す。そこで含有量を１〜２０％の範囲と定めた。より好ましい範囲は３〜１８％の範囲である。
【００１９】
Ｂ2Ｏ3は溶融性を改善し生産性を向上させると共に、ガラスのマトリックス中に入りガラス構造を安定化させ、化学的耐久性を向上させる効果を奏する。含有量が８％を超えると、溶融時粘性特性が悪くなり、成形性に支障を来すと共に、ガラスが不安定になる。そこで含有量を８％以下（ただしゼロを含む）の範囲と定めた。より好ましい上限値は６％であり、好ましい下限値は１％である。
【００２０】
ガラスの骨格成分であるこれら３つのガラス成分の総量が６０％より少ないと、ガラスの構造が脆弱となる一方、前記総量が９０％を超えると、溶融性が低下し生産性が落ちる。そこで前記総量を６０〜９０％の範囲と定めた。より好ましい範囲は６５〜８８％の範囲である。
【００２１】
アルカリ金属酸化物Ｒ2Ｏ（Ｒ＝Ｌｉ，Ｎａ，Ｋ）は、溶融性を改善し、線熱膨張係数を増大させる効果を奏する。その総量が２０％超えるとガラス骨格間に分散されるアルカリ量が過剰となりアルカリ溶出量が増大する。そこでアルカリ金属酸化物の総量を２０％以下（ただしゼロを含む）の範囲と定めた。一方、アルカリ金属酸化物の総量が２％未満であると溶融性の改善および線熱膨張係数の増大という効果が充分には得られないことがある。したがって、好ましい下限値は２％である。アルカリ金属酸化物の総量のより好ましい上限値は１８％である。また、アルカリ溶出量を低減する、いわゆるアルカリ混合効果を得るためには、前記アルカリ金属酸化物の各成分の下限含有量をそれぞれ０．１％とするのが望ましい。一方、化学的耐久性および溶融安定性の観点から、上限含有量をＬｉ2ＯとＮａ2Ｏとは１５％、Ｋ2Ｏは１０％とするのが望ましい。
【００２２】
また２価の金属酸化物Ｒ’Ｏ（Ｒ’：Ｍｇ，Ｃａ,Ｚｎ）の含有量を３．０％以下と定めた。
【００２３】
ＭｇＯは剛性を上げると共に溶融性を改善する効果を奏する。含有量が２０％を超えるとガラス構造が不安定となり、溶融生産性が低下すると共に化学的耐久性が低下するおそれがある。したがって含有量は０〜１９％の範囲が好ましい。
より好ましい上限値は１８％である。
【００２４】
またＣａＯは線熱膨張係数及び剛性を上げると共に溶融性を改善する効果を奏する。含有量が１０％を超えると、ガラス構造が不安定となり溶融生産性が低下すると共に化学的耐久性が低下するおそれがある。したがって含有量は０〜１０％の範囲が好ましい。より好ましい上限値は９％である。
【００２５】
ＳｒＯは線熱膨張係数を上げ、ガラス構造を安定化すると共に、溶融性を改善する効果を奏する。含有量が８％を超えるとガラス構造が不安定となるおそれがある。したがって含有量は０〜８％の範囲が好ましい。より好ましい上限値は６％である。
【００２７】
ＺｎＯは化学的耐久性及び剛性を上げると共に溶融性を改善する効果を奏する。含有量が６％を超えると、ガラス構造が不安定となり溶融生産性が低下すると共に化学的耐久性が低下するおそれがある。したがって含有量は０〜６％の範囲が好ましい。より好ましい上限値は５％である。
【００２８】
ＴｉＯ2はガラスの構造を強固にし、剛性を向上させると共に溶融性を改善する効果を奏する。またＺｒＯ2もガラスの構造を強固にし剛性を向上させると共に化学的耐久性を向上させる効果を奏する。そしてＬｎxＯyはガラスの構造を堅固にし剛性および靭性を向上させる効果を奏する。なお、このＬｎxＯyはランタノイド金属酸化物及びＹ2Ｏ3，Ｎｂ2Ｏ5，Ｔａ2Ｏ5からなる群より選ばれた少なくとも１つの化合物を意味し、ランタノイド金属酸化物としては、Ｌｎ2Ｏ3やＬｎＯなどが種類があり、ＬｎとしてはＬａ、Ｃｅ、Ｅｒ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｔｍ、Ｙｂ、Ｌｕなどが挙げられる。ここで（ＴｉＯ2＋ＺｒＯ2＋ＬｎxＯy）が１２％を超えるとガラスが不安定となり、靭性が大幅に低下すると共に失透傾向が高まり生産性が著しく低下する。そこでこれらの総量を１２％以下と定めた。より好ましい総量は０〜１１．５％の範囲である。
【００２９】
本発明のガラス組成物には、Ｓｂ2Ｏ3などの清澄剤を２％以下の範囲でさらに添加してもよい。その他必要により従来公知のガラス成分及び添加剤を本発明の効果を害しない範囲で添加しても構わない。
【００３０】
次に本発明のガラス基板について説明する。本発明のガラス基板の大きな特徴は前記ガラス組成物を用いて製造したことにある。ガラス基板の製造方法に特に限定はなく、これまで公知の製造方法を用いることができる。例えば、各成分の原料として各々相当する酸化物、炭酸塩、硝酸塩、水酸化物等を使用し、所望の割合に秤量し、粉末で十分に混合して調合原料とする。これを例えば１，３００〜１，５５０℃に加熱された電気炉中の白金坩堝などに投入し、溶融清澄後、撹拌均質化して予め加熱された鋳型に鋳込み、徐冷してガラスブロックにする。次に、ガラス転移点付近まで再加熱し、徐冷して歪み取りを行う。そして得られたガラスブロックを円盤形状にスライスして、内周および外周を同心円としてコアドリルを用いて切り出す。あるいは溶融ガラスをプレス成形して円盤状に成形する。そして、このようにして得られた円盤状のガラス基板は、さらにその両面を粗研磨および研磨された後、水、酸、アルカリの少なくとも１つの液で洗浄されて最終的なガラス基板とされる。
【００３１】
ここで、本発明のガラス基板を例えば情報記録用媒体の基板として用いる場合に、ヘッドの浮上量や記録媒体の膜厚を小さくする観点などから、研磨工程後のガラス基板の表面粗度Ｒａを１ｎｍ以下とし、且つ洗浄工程後の表面粗度Ｒａ’を表面粗度Ｒａの１．５倍以下とするのが好ましい。アルカリ成分を多く含む、強化処理を行ったガラス基板の場合には、研磨により表面粗度Ｒａを１ｎｍ以下にすることは可能であるが、次の洗浄工程において、水や酸、アルカリで基板表面を表面洗浄したときに、化学的耐久性が低いため表面が激しく浸食される結果、洗浄工程後の表面粗度Ｒａ’が大きくなってしまう。一方、強化処理しないガラス基板では一般に、基板の表面および内部の組成が均質であるので、洗浄工程においても基板の表面粗度Ｒａ’は大きくは変化しない。このため、ガラス成分を最適化することにより洗浄工程後の表面粗度Ｒａ’を研磨工程後の表面粗度Ｒａの１．５倍以下とすることも可能となる。
【００３２】
本発明に係るガラス基板ではつぎの諸物性を満足しているのが好ましい。まず、前記式（１）から算出される熱衝撃度数が４０より大きいことが好ましい。この熱衝撃度数が４０以下であると、急激な熱衝撃が加わった際基板が割れることがあるからである。より好ましい熱衝撃度数は４５以上である。
【００３３】
比弾性率（Ｅ／ρ）が３０Ｇｐａ以上であるのが好ましい。強化処理を行っていないガラス基板では機械的強度は基板の剛性に依存するため、比弾性率が３０Ｇｐａよりも小さいと、基板の機械的強度が不十分となり、ＨＤＤ搭載時に外部から衝撃を受けた際、ＨＤＤ部材との締結部分から破損しやすくなるからである。より好ましい比弾性率（Ｅ／ρ）は３２Ｇｐａ以上である。
【００３４】
破壊靭性値Ｋｃは１．００（ＭＰａ・ｍ １／２ ）以上が好ましい。ガラス基板を情報記録用媒体として用いる場合、破壊靭性値Ｋｃが１．００（ＭＰａ・ｍ １／２ ）未満であると、ガラス基板表面に磁性膜などの記録膜を形成する工程において加わえられる圧力などによりガラス基板にひび割れが生じることがあるからである。また、破壊靭性値Ｋｃが１．００（ＭＰａ・ｍ １／２ ）未満であると、基板の機械加工において基板が損傷を受けやすくなり、加工歩留まりが大きく低下する。破壊靭性値Ｋｃのより好ましい下限値は１．０２（ＭＰａ・ｍ １／２ ）である。
【００３５】
線熱膨張係数αは４０×１０-7〜９０×１０-7／℃の範囲が好ましい。線熱膨張係数αがこの範囲から外れると、ガラス基板を用いた情報記録用媒体を取り付ける駆動部の材料の線熱膨張係数との差が大きくなって、情報記録用媒体の固定部に応力が発生し、基板の破損や基板の変形による記録位置のズレが発生し、記録の読み書きができなくなるからである。線熱膨張係数のより好ましい下限値は４２×１０-7／℃であり、より好ましい上限値は８５×１０-7／℃である。
【００３６】
ガラス転移温度Ｔｇは５００℃以上が好ましい。ガラス転移温度をこのような範囲とするには、例えば骨格成分であるＳｉＯ2，Ｂ2Ｏ3，Ａｌ2Ｏ3の総量及びそれら比率、そしてガラス転移温度を大幅に低下させる成分であるアルカリ金属酸化物の添加量を、目的とする主物性を劣化させない範囲で調整すればよい。
【００３７】
比表面積Ｓ／Ｖは１〜５０の範囲が好ましい。比表面積Ｓ／Ｖが１より小さいと、板厚が厚くなり実用化が困難となることがあり、一方比表面積Ｓ／Ｖが５０より大きいと、板厚が薄くなり加工の際割れやすくなることがあるからである。比表面積Ｓ／Ｖのより好ましい範囲は１．０２〜４５である。
【００３８】
またガラス基板の最も薄い部分の厚みは２ｍｍ以下であるのが好ましい。ハードディスクドライブ装置などは小型薄型化が近年急速に進んでいるため、前記厚みが２ｍｍより厚いと、現在及び将来におけるハードディスクドライブ装置などへの搭載に適さなくなり汎用性が低下するからである。より好ましい厚みは１．５ｍｍ以下である。
【００３９】
本発明のガラス基板は、その大きさに限定はなく３．５，２．５，１．８インチ、あるいはそれ以下の小径ディスクとすることもでき、またその厚さは２ｍｍや１ｍｍ、０．６３ｍｍ、あるいはそれ以下といった薄型とすることもできる。
【００４０】
次に、本発明のガラス基板を用いた情報記録用媒体について説明する。情報記録用媒体の基板として本発明のガラス基板を用いると、耐久性および高記録密度が実現される。以下、図面に基づき情報記録用媒体について説明する。
【００４１】
図１は磁気ディスクの斜視図である。この磁気ディスクＤは、円形のガラス基板１の表面に磁性膜２を直接形成したものである。磁性膜２の形成方法としては従来公知の方法を用いることができ、例えば磁性粒子を分散させた熱硬化性樹脂を基板上にスピンコートして形成する方法や、スパッタリング、無電解めっきにより形成する方法が挙げられる。スピンコート法での膜厚は約０．３〜１．２μｍ程度、スパッタリング法での膜厚は０．０４〜０．０８μｍ程度、無電解めっき法での膜厚は０．０５〜０．１μｍ程度であり、薄膜化および高密度化の観点からはスパッタリング法および無電解めっき法による膜形成が好ましい。
【００４２】
磁性膜に用いる磁性材料としては、特に限定はなく従来公知のものが使用できるが、高い保持力を得るために結晶異方性の高いＣｏを基本とし、残留磁束密度を調整する目的でＮｉやＣｒを加えたＣｏ系合金などが好適である。具体的には、Ｃｏを主成分とするＣｏＰｔ、ＣｏＣｒ、ＣｏＮｉ、ＣｏＮｉＣｒ、ＣｏＣｒＴａ、ＣｏＰｔＣｒ、ＣｏＮｉＰｔや、ＣｏＮｉＣｒＰｔ、ＣｏＮｉＣｒＴａ、ＣｏＣｒＰｔＴａ、ＣｏＣｒＰｔＢ、ＣｏＣｒＰｔＳｉＯなどが挙げられる。磁性膜は、非磁性膜（例えば、Ｃｒ、ＣｒＭｏ、ＣｒＶなど）で分割しノイズの低減を図った多層構成（例えば、ＣｏＰｔＣｒ／ＣｒＭｏ／ＣｏＰｔＣｒ、ＣｏＣｒＰｔＴａ／ＣｒＭｏ／ＣｏＣｒＰｔＴａなど）としてもよい。上記の磁性材料の他、フェライト系、鉄−希土類系や、ＳｉＯ2、ＢＮなどからなる非磁性膜中にＦｅ、Ｃｏ、ＦｅＣｏ、ＣｏＮｉＰｔ等の磁性粒子を分散された構造のグラニュラーなどであってもよい。また、磁性膜は、内面型および垂直型のいずれの記録形式であってもよい。
【００４３】
また、磁気ヘッドの滑りをよくするために磁性膜の表面に潤滑剤を薄くコーティングしてもよい。潤滑剤としては、例えば液体潤滑剤であるパーフロロポリエーテル（ＰＦＰＥ）をフレオン系などの溶媒で希釈したものが挙げられる。
【００４４】
さらに必要により下地層や保護層を設けてもよい。磁気ディスクにおける下地層は磁性膜に応じて選択される。下地層の材料としては、例えば、Ｃｒ、Ｍｏ、Ｔａ、Ｔｉ、Ｗ、Ｖ、Ｂ、Ａｌ、Ｎｉなどの非磁性金属から選ばれる少なくとも一種以上の材料が挙げられる。Ｃｏを主成分とする磁性膜の場合には、磁気特性向上等の観点からＣｒ単体やＣｒ合金であることが好ましい。また、下地層は単層とは限らず、同一又は異種の層を積層した複数層構造としても構わない。例えば、Ｃｒ／Ｃｒ、Ｃｒ／ＣｒＭｏ、Ｃｒ／ＣｒＶ、ＮｉＡｌ／Ｃｒ、ＮｉＡｌ／ＣｒＭｏ、ＮｉＡｌ／ＣｒＶ等の多層下地層としてもよい。
【００４５】
磁性膜の摩耗や腐食を防止する保護層としては、例えば、Ｃｒ層、Ｃｒ合金層、カーボン層、水素化カーボン層、ジルコニア層、シリカ層などが挙げられる。これらの保護層は、下地層、磁性膜など共にインライン型スパッタ装置で連続して形成できる。また、これらの保護層は、単層としてもよく、あるいは、同一又は異種の層からなる多層構成としてもよい。なお、上記保護層上に、あるいは上記保護層に替えて、他の保護層を形成してもよい。例えば、上記保護層に替えて、Ｃｒ層の上にテトラアルコキシランをアルコール系の溶媒で希釈した中に、コロイダルシリカ微粒子を分散して塗布し、さらに焼成して酸化ケイ素（ＳｉＯ2)層を形成してもよい。
【００４６】
以上、情報記録用媒体の一実施態様として磁気ディスクについて説明したが、情報記録用媒体はこれに限定されるものではなく、光磁気ディスクや光ディスクなどにも本発明のガラス基板を用いることができる。
【００４７】
また、本発明のガラス基板は光通信用素子にも好適に使用できる。従来のガラス基板に比べて線熱膨張係数が４０×１０-7〜９０×１０-7／℃の範囲と大きいので、蒸着工程で加熱されたガラス基板が冷却されて縮む量が大きくなり、このガラス基板の収縮により基板表面に形成された膜が圧縮されてその密度が大きくなる。この結果、温度・湿度の変化による波長シフトが抑制される。
【００４８】
以下、波長多重分割（「ＤＷＤＭ」；Dense Wavelength Division Multiplexing）用の光フィルタを例に本発明のガラス基板を用いた光通信用素子について説明する。誘電体多層膜を用いた光フィルタは高屈折率層と低屈折率層とを有し、これらの層を積層した構造を有している。これらの層を形成する方法としては、特に限定はなく従来公知の方法、例えば真空蒸着法、スパッタリング法、イオンプレーティング法、イオンビームアシスト法などを用いることができる。この中でも生産性が高いことから真空蒸着法が推奨される。真空蒸着は、真空中で蒸着材料を加熱し、発生した蒸気を基体上に凝縮・付着させて薄膜を形成する方法である。蒸着材料の加熱方法には、抵抗加熱、外熱ルツボ、電子ビーム、高周波、レーザーなどの各種方法がある。具体的な蒸着条件として、真空度は１×１０-3〜５×１０-3Ｐａ程度である。蒸着中は真空度が一定となるように電磁弁を制御して導入酸素量を調整する。そして層厚モニターにより所定層厚となったところでシャターを閉じて蒸着を終了する。
【００４９】
各膜厚としては特に限定はないが、光学的膜厚が波長の１／４とするのが基本であって、一般的に１μｍ程度までである。また、総層数は一般的に１００層を超える。用いる膜材料としては例えば、誘電体や半導体、金属であって、この中でも誘電体が特に好ましい。
【００５０】
以上、本発明のガラス基板を用いた光通信用素子の一実施態様としてＤＷＤＭ用の光フィルタについて説明したが、光通信用素子はこれに限定されるものではなく、本発明のガラス基板は光スイッチ、合分波素子などの光通信用素子にも使用できる。
【００５１】
【実施例】
実施例１〜３７，比較例１〜５
定められた量の原料粉末を白金るつぼに秤量して入れ、混合したのち、電気炉中で１，５５０℃で溶解した。原料が充分に溶解したのち、撹拌羽をガラス融液に挿入し、約１時間撹拌した。その後、撹拌羽を取り出し、３０分間静置したのち、治具に融液を流しこむことによってガラスブロックを得た。その後各ガラスのガラス転移点付近までガラスブロックを再加熱し、徐冷して歪取りを行った。得られたガラスブロックを約１.５ｍｍの厚さ、２．５インチの円盤形状にスライスし、内周，外周を同心円としてカッターを用いて切り出した。そして、両面を粗研磨及び研磨、洗浄を行って実施例及び比較例のガラス基板を作製した。作製したガラス基板について各種物性評価を行った。なお、物性評価方法は前記の通りである。また、熱衝撃性試験Ａ及び熱衝撃性試験Ｂについては下記試験方法および判定基準で行った。結果を合わせて表１〜表４に示す。
【００５２】
（熱衝撃性試験Ａ）
外径６５ｍｍ、内径２０ｍｍ、厚さ０．６３５ｍｍの円盤形状のガラス基板を、３００℃の電気炉内に３０分間放置した後、２０℃の冷水中に投入し、ガラス基板が割れなかった場合を「○」、割れた場合を「×」とした。
【００５３】
（熱衝撃性試験Ｂ）
外径４８ｍｍ、内径１２ｍｍ、厚さ０．５０８ｍｍの円盤形状のガラス基板を、３００℃の電気炉内に３０分間放置した後、２０℃の冷水中に投入し、ガラス基板が割れなかった場合を「○」、割れた場合を「×」とした。
【００５４】
【表１】
【表２】
【表３】
【表４】
表１〜表３から明らかなように、実施例１〜３７のガラス基板では、線熱膨張係数αは４３．２×１０-7〜７４．６×１０-7／℃の範囲とＨＤＤの部材と近い値であった。また破壊靭性値Ｋｃは１．０２（ＭＰａ・ｍ１／２）以上であり、比弾性率Ｅ／ρは３２．４Ｇｐａ以上と従来のガラス基板に比べ大きい値であった。そしてまたガラス転移温度Ｔｇは５０４℃以上であった。このようなガラス基板の物性値から算出した実施例１〜３９のガラス基板の熱衝撃度数Ｈは４０よりいずれも大きく、熱衝撃性試験Ａ及びＢにおいてガラス基板が割れることはなかった。
【００５９】
一方、表４によれば、比較例１のガラス基板では、（ＴｉＯ2＋ＺｒＯ2＋ＬｎxＯy）の含有量が１２．５％と多かったため、破壊靭性値が低くなると共に熱衝撃度数Ｈが小さくなり、熱衝撃性試験Ａ及びＢにおいてガラス基板が割れてしまった。また比較例２のガラス基板では、ＳｉＯ2の含有量が４３．６％と少なく、そしてＲ’Ｏの含有量が２２．２％と多く、さらに（ＴｉＯ2＋ＺｒＯ2＋ＬｎxＯy）の含有量が１９．７％と多かったため、ガラスの構造が軟弱となり線熱膨張係数α、破壊靭性値Ｋｃ、熱衝撃度数Ｈにおいて所望値が得られなかった。一方、ＳｉＯ2の含有量が７７．１％と多かった比較例３のガラス基板では、破壊靭性値Ｋｃ及び比弾性率が低下すると共に、熱衝撃度数Ｈが小さくなった。比較例４のガラス基板では、Ａｌ2Ｏ3及びＲ2Ｏ（Ｒ：Ｌｉ，Ｎａ，Ｋ）の含有量が多く、また比較例５のガラス基板では、Ｂ2Ｏ3および骨格成分（ＳｉＯ2＋Ａｌ2Ｏ3＋Ｂ2Ｏ3）の含有量が多かったため、破壊靭性値Ｋｃ及び熱衝撃度数Ｈにおいて所望値が得られなかった。
【００６０】
【発明の効果】
本発明に係るガラス組成物及びガラス基板は、強化処理を行うことなく高い耐熱衝撃性を有するので、ガラス基板表面に記録膜などを形成する工程において生じる急激な熱変化によっても破損することがない。また高い剛性を有し、さらには適度な表面硬度を有し基板表面の傷を防止すると共に研磨などの表面加工が容易である。そしてまた従来に比べ線熱膨張係数が高くＨＤＤの部材のそれに近くなったので、記録装置への取付け時や情報記録時に不具合が生じることがない。また破壊靭性値が高いので情報記録用基板の製造時などに基板が破損することがない。高い比弾性率を有するので、ガラス基板の高速回転時における回転安定性が向上する。
【００６１】
本発明に係るガラス基板を情報記録用媒体に使用すると、表面処理が容易で、製造工程中において破損することがなく、耐久性に優れ、高い記録密度が得られる。
【００６２】
また本発明に係るガラス基板を光通信用素子に使用すると、経時変化が少なく、温度・湿度の変化による波長シフトを抑制できる。
【図面の簡単な説明】
【図１】 本発明のガラス基板を用いた情報記録用媒体の一例を示す斜視図である。
【図２】 ビッカース圧子で押圧したときにできるガラス基板表面の圧痕とクラックの模式図である。
【図３】 比表面積（＝表面積／体積）の算出例を示す図である。
【符号の説明】
１ ガラス基板
２ 磁性膜
Ｄ 磁気ディスク[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a glass substrate using a specific glass composition, and more specifically, a glass substrate used as a substrate for information recording media such as magnetic disks, magneto-optical disks, DVDs, MDs, and optical communication elements. It is related with the manufacturing method .
[0002]
[Prior art]
Conventionally, as a substrate for a magnetic disk, an aluminum alloy is generally used for a stationary type such as a desktop computer or a server, while a glass substrate is generally used for a portable type such as a notebook computer or a mobile computer. Was easily deformed and its hardness was insufficient, so that the substrate surface after polishing was not sufficiently smooth. Further, when the head mechanically contacts the magnetic disk, there is a problem that the magnetic film is easily peeled off from the substrate. Therefore, it is predicted that glass substrates with little deformation, good smoothness and high mechanical strength will be widely used not only for portable devices but also for stationary devices and other household information devices in the future. Yes.
[0003]
As a glass substrate, a chemically strengthened glass is known in which a compressive strain is generated by replacing an alkali element on the surface of the substrate with another alkali element and mechanical strength is improved. However, chemically tempered glass requires a complicated ion exchange process, and rework after ion exchange is impossible, making it difficult to increase the production yield. In addition, in order to give the glass substrate ion exchange properties, it was made easy for alkali ions to move in the substrate, so that alkali ions on the surface of the substrate were transferred during the heating process when forming the magnetic film. There is a problem that it moves to the surface to be eluted, erodes the magnetic film, or deteriorates the adhesion strength of the magnetic film.
[0004]
On the other hand, as a general glass substrate not subjected to chemical strengthening treatment, there is a soda lime substrate, but mechanical strength and chemical durability are insufficient to use this soda lime substrate as an information recording substrate. In addition, glass materials used for liquid crystal substrates, etc. have a low coefficient of linear thermal expansion by alkali-free or low alkali to maintain thermal stability at high temperatures, so clamps made of SUS steel, etc. A difference from the linear thermal expansion coefficient of the spindle motor member is large, and a problem may occur when the recording medium is attached to the recording apparatus or when information is recorded. In addition, since the mechanical strength is insufficient, it is difficult to apply to an information recording substrate.
[0005]
In addition, although a glass substrate is used as a substrate in an optical communication element such as an optical filter or an optical switch, the element may be deteriorated by an alkali component eluted from the glass substrate. In addition, as the density of the film formed on the glass substrate increases, the wavelength shift due to changes in temperature and humidity is suppressed, but there is a limit to the density of the film that can be formed by the conventionally widely used vacuum deposition method. .
[0006]
Furthermore, when a glass substrate is used for information recording, when the information recording film is formed on the glass substrate, the glass substrate is cracked by pressure, heating, or impact applied to the surface, and the yield of the product is reduced. There was something to do.
[0007]
[Patent Document 1]
JP 2001-19466 A (column of claims, Table 1 to Table 5)
[0008]
[Problems to be solved by the invention]
This invention is made | formed in view of such a conventional problem, The place made into the objective is providing the manufacturing method of the glass substrate using the glass composition strong against a thermal shock, without performing a reinforcement | strengthening process. And providing a method for producing a glass substrate using a glass composition having a high mechanical strength, a linear thermal expansion coefficient close to that of a motor member, and having a high fracture toughness.
[0009]
[Means for Solving the Problems]
According to the present invention, by weight percent, SiO 2 : 62.5 to 75%, Al 2 O 3 : 1 to 20%, B 2 O 3 : 0 to 8% (including zero), SiO 2 + Al 2 O 3 + B 2 O 3 : 60 to 90%, Li 2 O: 0.1 to 15%, Na 2 O: 0.1 to 15%, K 2 O: 0.1 to 10%, R 2 O ( R = Li, Na, the total amount of K): 0.3~18%, R'O ( R '= Mg, C a, the total amount of Z n): 0~ 3.0% (however, including zero), TiO 2 as an essential component, TiO 2 + ZrO 2 + Ln x O y : 0 to 12% ( where Ln x O y is a group consisting of a lanthanoid metal oxide and Y 2 O 3 , Nb 2 O 5 , Ta 2 O 5 have each glass component of meaning) more selected at least one compound, BaO, and SrO both used including no glass composition, the strengthening treatment Ukoto no method for producing a glass substrate thermal shock frequency calculated from the following equation (1) (H) is characterized by producing a greater than 40 glass substrate is provided. Hereinafter, “%” means “% by weight” unless otherwise specified.
Thermal shock frequency (H) = 500 × (1 / (α × 10 7 )) 2 + 30 × (Kc) 8 + 0.05 × (E / ρ) + 0.02 × Tg (1)
(Wherein, α: linear thermal expansion coefficient (25-100 ° C., 1 / ° C.), Kc: fracture toughness value (MPa · m 1/2 ), E / ρ: specific elastic modulus (Gpa), Tg: glass transition Temperature (℃)
[0011]
Here, from the viewpoint of thermal shock resistance, it is desirable to make the thermal shock frequency calculated from the formula (1) larger than 40 without performing the strengthening treatment.
[0012]
Without performing a strengthening treatment, the specific elastic modulus E / ρ is 30 Gpa or more, the fracture toughness value Kc is 1.00 (MPa · m 1/2 ) or more, and the linear thermal expansion coefficient α is 40 × 10 −7 to 90 ×. 10 −7 / ° C. and glass transition temperature Tg are preferably 500 ° C. or higher.
[0013]
Further, the surface area / volume (hereinafter sometimes referred to as “specific surface area”) is preferably in the range of 1 to 50 / mm, and the thickness of the thinnest portion is preferably 2 mm or less.
[0014]
The specific elastic modulus (E / ρ) is a value obtained by dividing the Young's modulus E by the specific gravity ρ, and the Young's modulus is measured according to the dynamic elastic modulus test method of the elastic test method of JIS R 1602 fine ceramics. The specific gravity ρ is measured in distilled water at 25 ° C. by the Archimedes method. Further, the fracture toughness value Kc was calculated from the following formula using a Vickers hardness tester, indented with a Vickers indenter under conditions of a load of 500 g and a load time of 15 sec (see FIG. 2).
Kc = 0.018 (E / Hv) 1/2 (P / C 3/2 ) = 0.026 E 1/2 P 1/2 a / C 3/2
(Wherein, Kc: fracture toughness value (Pa · m 1/2 ), E: elastic modulus (Pa), Hv: Vickers hardness (Pa), P: indentation load (N), C: average crack length Half (m), a: Half of the average diagonal length of the indentation (m)
[0015]
The linear thermal expansion coefficient A is a value measured using a differential expansion measuring device under the conditions of load: 5 g, temperature range: 25 to 100 ° C., temperature increase rate: 5 ° C./min. The glass transition point Tg is a value obtained by measuring a glass sample adjusted to a powder form by heating a temperature range of 25 to 700 ° C. at a heating rate of 5 ° C./min with a load of 5 g using a differential calorimeter. . Further, the specific surface area S / V is calculated as shown in FIG. 3, for example, when the glass substrate has a disk shape.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The inventors of the present invention have made extensive studies to increase the thermal shock resistance without performing a strengthening treatment. As a result, SiO 2 is used as the matrix component of the glass, and a predetermined amount of Al 2 O 3 and B 2 O 3 is contained therein to form a glass skeleton, thereby obtaining a predetermined rigidity, and R 2 O. (R: Li, Na, K ) and R'O (R ': Mg, C a, Z n) the total amount of further higher by a total predetermined range of (TiO 2 + ZrO 2 + Ln x O y) The inventors have found that the thermal shock resistance can be obtained, and have made the present invention.
[0017]
Hereinafter, the reason why the components of the glass composition according to the present invention are limited will be described. First, SiO 2 is a component that forms a glass matrix. If the content is less than 62.5 %, the structure of the glass becomes unstable and the chemical durability deteriorates, and at the same time, the viscosity characteristics at the time of melting deteriorate and the moldability is hindered. On the other hand, if the content exceeds 75%, the meltability deteriorates and the productivity is lowered, and sufficient rigidity cannot be obtained. Therefore, the content is determined to be in the range of 62.5 to 75%. A more preferred range is from 62.5 to 74%.
[0018]
Al 2 O 3 enters the glass matrix, stabilizes the glass structure, and improves the chemical durability. If the content is less than 1%, a sufficient stabilizing effect cannot be obtained. On the other hand, if it exceeds 20%, the meltability is deteriorated and the productivity is hindered. Therefore, the content is determined to be in the range of 1 to 20%. A more preferable range is 3 to 18%.
[0019]
B 2 O 3 improves meltability and productivity, and has the effect of entering the glass matrix, stabilizing the glass structure, and improving chemical durability. If the content exceeds 8%, the viscosity characteristics at the time of melting deteriorate, the moldability is hindered, and the glass becomes unstable. Therefore, the content is defined as a range of 8% or less (including zero). A more preferred upper limit is 6%, and a preferred lower limit is 1%.
[0020]
If the total amount of these three glass components, which are the skeleton components of the glass, is less than 60%, the glass structure becomes fragile. On the other hand, if the total amount exceeds 90%, the meltability decreases and the productivity decreases. Therefore, the total amount is set to a range of 60 to 90%. A more preferred range is 65 to 88%.
[0021]
Alkali metal oxide R 2 O (R = Li, Na, K) has the effect of improving the meltability and increasing the linear thermal expansion coefficient. If the total amount exceeds 20%, the amount of alkali dispersed between the glass skeletons becomes excessive and the amount of alkali elution increases. Therefore, the total amount of alkali metal oxides is set to a range of 20% or less (including zero). On the other hand, if the total amount of alkali metal oxides is less than 2%, the effects of improving the meltability and increasing the linear thermal expansion coefficient may not be sufficiently obtained. Therefore, a preferable lower limit is 2%. A more preferable upper limit of the total amount of alkali metal oxides is 18%. Further, in order to obtain a so-called alkali mixing effect that reduces the alkali elution amount, it is desirable that the lower limit content of each component of the alkali metal oxide is 0.1%. On the other hand, from the viewpoint of chemical durability and melt stability, it is desirable that the upper limit contents be 15% for Li 2 O and Na 2 O and 10% for K 2 O.
[0022]
The divalent metal oxide R'O: defining (R 'Mg, C a, Z n) and 3.0% or less of the content of.
[0023]
MgO has the effect of increasing the rigidity and improving the meltability. If the content exceeds 20%, the glass structure becomes unstable, and the melt productivity is lowered and the chemical durability may be lowered. Therefore, the content is preferably in the range of 0 to 19%.
A more preferred upper limit is 18%.
[0024]
CaO has the effect of increasing the linear thermal expansion coefficient and rigidity and improving the meltability. If the content exceeds 10%, the glass structure becomes unstable and the melt productivity is lowered and the chemical durability may be lowered. Therefore, the content is preferably in the range of 0 to 10%. A more preferred upper limit is 9%.
[0025]
SrO has the effect of increasing the linear thermal expansion coefficient, stabilizing the glass structure, and improving the meltability. If the content exceeds 8%, the glass structure may become unstable. Therefore, the content is preferably in the range of 0 to 8%. A more preferred upper limit is 6%.
[0027]
ZnO has the effect of improving chemical durability and rigidity and improving meltability. If the content exceeds 6%, the glass structure becomes unstable and the melt productivity is lowered and the chemical durability may be lowered. Accordingly, the content is preferably in the range of 0 to 6%. A more preferred upper limit is 5%.
[0028]
TiO 2 has the effect of strengthening the glass structure, improving the rigidity and improving the meltability. ZrO 2 also has the effect of strengthening the glass structure and improving the rigidity and chemical durability. Ln x O y has the effect of enhancing the rigidity and toughness of the glass structure. Incidentally, the Ln x O y means lanthanoid metal oxides and Y 2 O 3, Nb 2 O 5, Ta least one compound selected from the group consisting of 2 O 5, as the lanthanoid metal oxide, Ln There are types such as 2 O 3 and LnO, and examples of Ln include La, Ce, Er, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu. Here (TiO 2 + ZrO 2 + Ln x O y) becomes unstable glass exceeds 12%, productivity increases devitrification tendency with toughness is greatly reduced significantly decreases. Therefore, the total amount of these is set to 12% or less. A more preferable total amount is in the range of 0 to 11.5%.
[0029]
A clarifier such as Sb 2 O 3 may be further added to the glass composition of the present invention in a range of 2% or less. If necessary, conventionally known glass components and additives may be added within a range not impairing the effects of the present invention.
[0030]
Next, the glass substrate of the present invention will be described. A major feature of the glass substrate of the present invention is that it is produced using the glass composition. There is no limitation in particular in the manufacturing method of a glass substrate, A conventionally well-known manufacturing method can be used. For example, the corresponding oxides, carbonates, nitrates, hydroxides, etc. are used as raw materials for each component, weighed to a desired ratio, and thoroughly mixed with powder to obtain a blended raw material. This is put into, for example, a platinum crucible in an electric furnace heated to 1,300 to 1,550 ° C., melted and clarified, stirred and homogenized, cast into a preheated mold, and gradually cooled to a glass block. . Next, it is reheated to the vicinity of the glass transition point, and is slowly cooled to remove strain. Then, the obtained glass block is sliced into a disk shape, and the inner periphery and the outer periphery are concentrically cut out using a core drill. Alternatively, the molten glass is press-molded into a disk shape. The disk-shaped glass substrate thus obtained is further subjected to rough polishing and polishing on both surfaces, and then washed with at least one of water, acid, and alkali to form a final glass substrate. .
[0031]
Here, when the glass substrate of the present invention is used as, for example, a substrate for an information recording medium, the surface roughness Ra of the glass substrate after the polishing step is determined from the viewpoint of reducing the flying height of the head or the film thickness of the recording medium. The surface roughness Ra ′ after the cleaning step is preferably 1.5 nm or less of the surface roughness Ra. In the case of a tempered glass substrate containing a large amount of alkali components, it is possible to reduce the surface roughness Ra to 1 nm or less by polishing, but in the next cleaning step, the substrate surface with water, acid, or alkali When the surface is cleaned, since the chemical durability is low, the surface is severely eroded, resulting in an increase in the surface roughness Ra ′ after the cleaning step. On the other hand, since the glass substrate not subjected to the tempering treatment generally has a uniform surface and internal composition, the surface roughness Ra ′ of the substrate does not change greatly even in the cleaning process. For this reason, by optimizing the glass component, the surface roughness Ra ′ after the cleaning process can be 1.5 times or less of the surface roughness Ra after the polishing process.
[0032]
The glass substrate according to the present invention preferably satisfies the following physical properties. First, it is preferable that the thermal shock frequency calculated from the formula (1) is larger than 40. This is because if the thermal shock frequency is 40 or less, the substrate may be cracked when a sudden thermal shock is applied. A more preferable thermal shock frequency is 45 or more.
[0033]
The specific elastic modulus (E / ρ) is preferably 30 Gpa or more. Since the mechanical strength of a glass substrate that has not been tempered depends on the rigidity of the substrate, if the specific elastic modulus is smaller than 30 Gpa , the mechanical strength of the substrate becomes insufficient, and an external shock is applied when the HDD is mounted. This is because it tends to be damaged from the fastening portion with the HDD member. More preferable specific elastic modulus (E / ρ) is 32 Gpa or more.
[0034]
The fracture toughness value Kc is preferably 1.00 (MPa · m 1/2 ) or more. When a glass substrate is used as an information recording medium, if the fracture toughness value Kc is less than 1.00 (MPa · m 1/2 ) , it can be added in the step of forming a recording film such as a magnetic film on the glass substrate surface. This is because cracks may occur in the glass substrate due to pressure or the like. Further, when the fracture toughness value Kc is less than 1.00 (MPa · m 1/2 ) , the substrate is easily damaged in the machining of the substrate, and the processing yield is greatly reduced. A more preferable lower limit value of the fracture toughness value Kc is 1.02 (MPa · m 1/2 ) .
[0035]
The linear thermal expansion coefficient α is preferably in the range of 40 × 10 −7 to 90 × 10 −7 / ° C. When the linear thermal expansion coefficient α is out of this range, the difference between the linear thermal expansion coefficient of the material of the drive unit to which the information recording medium using the glass substrate is attached becomes large, and stress is applied to the fixed part of the information recording medium. This is because the recording position shift occurs due to breakage of the substrate or deformation of the substrate, and reading / writing of the recording becomes impossible. A more preferable lower limit value of the linear thermal expansion coefficient is 42 × 10 −7 / ° C., and a more preferable upper limit value is 85 × 10 −7 / ° C.
[0036]
The glass transition temperature Tg is preferably 500 ° C. or higher. In order to set the glass transition temperature in such a range, for example, the total amount and ratio of SiO 2 , B 2 O 3 , and Al 2 O 3 as skeleton components, and alkali metal as a component that greatly reduces the glass transition temperature. What is necessary is just to adjust the addition amount of an oxide in the range which does not degrade the target main physical property.
[0037]
The specific surface area S / V is preferably in the range of 1-50. When the specific surface area S / V is smaller than 1, the plate thickness becomes thick and it may be difficult to put into practical use. On the other hand, when the specific surface area S / V is larger than 50, the plate thickness becomes thin and it is easy to break during processing. Because there is. A more preferable range of the specific surface area S / V is 1.02 to 45.
[0038]
The thickness of the thinnest portion of the glass substrate is preferably 2 mm or less. This is because hard disk drive devices and the like have been rapidly reduced in size and thickness in recent years, and if the thickness is greater than 2 mm, they are not suitable for mounting on current and future hard disk drive devices and the general versatility is reduced. A more preferable thickness is 1.5 mm or less.
[0039]
The glass substrate of the present invention is not limited in size, and can be a small-diameter disk of 3.5, 2.5, 1.8 inches or less, and the thickness thereof is 2 mm, 1 mm, 0. It can be as thin as 63 mm or less.
[0040]
Next, an information recording medium using the glass substrate of the present invention will be described. When the glass substrate of the present invention is used as a substrate for an information recording medium, durability and high recording density are realized. Hereinafter, an information recording medium will be described with reference to the drawings.
[0041]
FIG. 1 is a perspective view of a magnetic disk. This magnetic disk D is obtained by directly forming a
[0042]
The magnetic material used for the magnetic film is not particularly limited, and a conventionally known material can be used. However, in order to obtain a high coercive force, Ni having a high crystal anisotropy is basically used, and Ni or A Co-based alloy to which Cr is added is suitable. Specific examples include CoPt, CoCr, CoNi, CoNiCr, CoCrTa, CoPtCr, and CoNiPt containing Co as a main component, CoNiCrPt, CoNiCrTa, CoCrPtTa, CoCrPtB, and CoCrPtSiO. The magnetic film may have a multilayer structure (for example, CoPtCr / CrMo / CoPtCr, CoCrPtTa / CrMo / CoCrPtTa) that is divided by a nonmagnetic film (for example, Cr, CrMo, CrV, etc.) to reduce noise. Addition to the above magnetic material, ferrite, iron - rare-earth or be in a non-magnetic film made of SiO 2, BN Fe, Co, FeCo, etc. granular structure magnetic particles are dispersed, such CoNiPt Also good. Further, the magnetic film may be either an inner surface type or a vertical type recording format.
[0043]
In addition, a lubricant may be thinly coated on the surface of the magnetic film in order to improve the sliding of the magnetic head. Examples of the lubricant include those obtained by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a freon-based solvent.
[0044]
Furthermore, you may provide a base layer and a protective layer as needed. The underlayer in the magnetic disk is selected according to the magnetic film. Examples of the material for the underlayer include at least one material selected from nonmagnetic metals such as Cr, Mo, Ta, Ti, W, V, B, Al, and Ni. In the case of a magnetic film containing Co as a main component, Cr alone or a Cr alloy is preferable from the viewpoint of improving magnetic characteristics. Further, the underlayer is not limited to a single layer, and may have a multi-layer structure in which the same or different layers are stacked. For example, a multilayer underlayer such as Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, or NiAl / CrV may be used.
[0045]
Examples of the protective layer that prevents wear and corrosion of the magnetic film include a Cr layer, a Cr alloy layer, a carbon layer, a hydrogenated carbon layer, a zirconia layer, and a silica layer. These protective layers can be formed continuously with an in-line type sputtering apparatus, such as an underlayer and a magnetic film. In addition, these protective layers may be a single layer, or may have a multilayer structure including the same or different layers. Note that another protective layer may be formed on the protective layer or instead of the protective layer. For example, in place of the protective layer, tetraalkoxylane is diluted with an alcohol-based solvent on the Cr layer, and then colloidal silica fine particles are dispersed and applied, and then baked to form a silicon oxide (SiO 2 ) layer. It may be formed.
[0046]
As described above, the magnetic disk has been described as one embodiment of the information recording medium. However, the information recording medium is not limited to this, and the glass substrate of the present invention can be used for a magneto-optical disk, an optical disk, and the like. .
[0047]
Moreover, the glass substrate of this invention can be used conveniently also for the element for optical communications. Compared to the conventional glass substrate, the coefficient of linear thermal expansion is as large as 40 × 10 −7 to 90 × 10 −7 / ° C., so that the amount of glass substrate heated in the vapor deposition process is cooled and shrunk, and this The film formed on the substrate surface is compressed by the shrinkage of the glass substrate, and the density thereof is increased. As a result, wavelength shift due to changes in temperature and humidity is suppressed.
[0048]
Hereinafter, an optical communication element using the glass substrate of the present invention will be described taking an optical filter for wavelength division division (“DWDM”) as an example. An optical filter using a dielectric multilayer film has a high refractive index layer and a low refractive index layer, and has a structure in which these layers are laminated. A method for forming these layers is not particularly limited, and a conventionally known method such as a vacuum deposition method, a sputtering method, an ion plating method, or an ion beam assist method can be used. Among these, vacuum deposition is recommended because of its high productivity. Vacuum deposition is a method of forming a thin film by heating a deposition material in vacuum and condensing and adhering the generated vapor onto a substrate. There are various methods such as resistance heating, an external heating crucible, an electron beam, a high frequency, and a laser as a method for heating the deposition material. As specific vapor deposition conditions, the degree of vacuum is about 1 × 10 −3 to 5 × 10 −3 Pa. During the deposition, the amount of introduced oxygen is adjusted by controlling the solenoid valve so that the degree of vacuum is constant. Then, when the predetermined layer thickness is reached by the layer thickness monitor, the shutter is closed and the deposition is finished.
[0049]
Each film thickness is not particularly limited, but the optical film thickness is basically ¼ of the wavelength, and is generally about 1 μm. Moreover, the total number of layers generally exceeds 100 layers. Examples of the film material to be used include dielectrics, semiconductors, and metals. Among these, dielectrics are particularly preferable.
[0050]
As mentioned above, although the optical filter for DWDM was demonstrated as one embodiment of the element for optical communications using the glass substrate of this invention, the element for optical communications is not limited to this, The glass substrate of this invention is optical. It can also be used for optical communication elements such as switches and multiplexing / demultiplexing elements.
[0051]
【Example】
Examples 1 to 37 , Comparative Examples 1 to 5
A predetermined amount of the raw material powder was weighed into a platinum crucible, mixed, and then melted at 1,550 ° C. in an electric furnace. After the raw materials were sufficiently dissolved, a stirring blade was inserted into the glass melt and stirred for about 1 hour. Thereafter, the stirring blade was taken out and allowed to stand for 30 minutes, and then the melt was poured into a jig to obtain a glass block. Thereafter, the glass block was reheated to near the glass transition point of each glass, and slowly cooled to remove strain. The obtained glass block was sliced into a disc shape of about 1.5 mm in thickness and 2.5 inches, and the inner periphery and outer periphery were cut out using a cutter with concentric circles. And both surfaces were subjected to rough polishing, polishing, and cleaning to produce glass substrates of Examples and Comparative Examples. Various physical properties of the produced glass substrate were evaluated. The physical property evaluation method is as described above. Moreover, about the thermal shock test A and the thermal shock test B, it carried out with the following test method and criteria. The results are shown in Tables 1 to 4.
[0052]
(Thermal shock test A)
When a disk-shaped glass substrate having an outer diameter of 65 mm, an inner diameter of 20 mm, and a thickness of 0.635 mm is left in an electric furnace at 300 ° C. for 30 minutes and then placed in cold water at 20 ° C., the glass substrate does not break. “◯”, and “×” when cracked.
[0053]
(Thermal shock test B)
When a disk-shaped glass substrate having an outer diameter of 48 mm, an inner diameter of 12 mm, and a thickness of 0.508 mm is left in a 300 ° C. electric furnace for 30 minutes and then placed in 20 ° C. cold water, and the glass substrate does not break. “◯”, and “×” when cracked.
[0054]
[Table 1]
[Table 2]
[Table 3]
[Table 4]
As is apparent from Tables 1 to 3, in the glass substrates of Examples 1 to 37 , the linear thermal expansion coefficient α is in the range of 43.2 × 10 −7 to 74.6 × 10 −7 / ° C. and the members of the HDD. It was close to the value. The fracture toughness value Kc was 1.02 (MPa · m 1/2 ) or more, and the specific modulus E / ρ was 32.4 Gpa or more, which was a large value compared to the conventional glass substrate. The glass transition temperature Tg was 504 ° C. or higher. The thermal shock frequency H of the glass substrates of Examples 1 to 39 calculated from the physical property values of such glass substrates was larger than 40, and the glass substrates were not broken in the thermal shock tests A and B.
[0059]
On the other hand, according to Table 4, in the glass substrate of Comparative Example 1, the content of (TiO 2 + ZrO 2 + Ln x O y ) was as high as 12.5%, so the fracture toughness value was lowered and the thermal shock frequency H was In the thermal shock tests A and B, the glass substrate was broken. Further, in the glass substrate of Comparative Example 2, the content of SiO 2 is as small as 43.6%, the content of R′O is as large as 22.2%, and the content of (TiO 2 + ZrO 2 + Ln x O y ) Since the amount was as large as 19.7%, the glass structure was weak, and desired values could not be obtained in terms of linear thermal expansion coefficient α, fracture toughness value Kc, and thermal shock power H. On the other hand, in the glass substrate of Comparative Example 3 in which the content of SiO 2 was as high as 77.1%, the fracture toughness value Kc and the specific elastic modulus were lowered, and the thermal shock frequency H was reduced. In the glass substrate of Comparative Example 4, the contents of Al 2 O 3 and R 2 O (R: Li, Na, K) are large, and in the glass substrate of Comparative Example 5, B 2 O 3 and the skeleton component (SiO 2 + Al 2 O 3 + B 2 O 3 ) was high, so that desired values could not be obtained in the fracture toughness value Kc and the thermal shock power H.
[0060]
【The invention's effect】
Since the glass composition and the glass substrate according to the present invention have high thermal shock resistance without performing a strengthening treatment, the glass composition and the glass substrate are not damaged even by a rapid thermal change that occurs in the process of forming a recording film or the like on the glass substrate surface. . Further, it has high rigidity, and further has an appropriate surface hardness to prevent scratches on the substrate surface and to facilitate surface processing such as polishing. In addition, since the linear thermal expansion coefficient is higher than that of the conventional HDD, it becomes close to that of the HDD member, so that no troubles occur when mounting to a recording apparatus or recording information. Further, since the fracture toughness value is high, the substrate is not damaged at the time of manufacturing the information recording substrate. Since it has a high specific modulus, the rotational stability during high-speed rotation of the glass substrate is improved.
[0061]
When the glass substrate according to the present invention is used for an information recording medium, the surface treatment is easy, the glass substrate is not damaged during the production process, is excellent in durability, and a high recording density is obtained.
[0062]
Further, when the glass substrate according to the present invention is used for an optical communication element, a change with time is small, and a wavelength shift due to a change in temperature and humidity can be suppressed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of an information recording medium using a glass substrate of the present invention.
FIG. 2 is a schematic diagram of indentations and cracks on the surface of a glass substrate formed when pressed with a Vickers indenter.
FIG. 3 is a diagram showing a calculation example of specific surface area (= surface area / volume).
[Explanation of symbols]
1
Claims (3)
ＳｉＯ2：６２．５〜７５％、
Ａｌ2Ｏ3：１〜２０％、
Ｂ2Ｏ3：０〜８％（ただし、ゼロを含む）、
ＳｉＯ2＋Ａｌ2Ｏ3＋Ｂ2Ｏ3：６０〜９０％、
Ｌｉ２Ｏ：０．１〜１５％
Ｎａ２Ｏ：０．１〜１５％
Ｋ２Ｏ：０．１〜１０％
Ｒ2Ｏ（Ｒ＝Ｌｉ，Ｎａ，Ｋ）の総量：０．３〜１８％、
Ｒ’Ｏ（Ｒ’＝Ｍｇ, Ｃａ,Ｚｎ）の総量：０〜３．０％（ただし、ゼロを含む）、
ＴｉＯ ２ を必須成分として、ＴｉＯ2＋ＺｒＯ2＋ＬｎxＯy：０〜１２％（ただし、ＬｎxＯyはランタノイド金属酸化物及びＹ2Ｏ3，Ｎｂ2Ｏ5，Ｔａ2Ｏ5からなる群より選ばれた少なくとも１つの化合物を意味する）の各ガラス成分を有し、
ＢａＯ、及びＳｒＯを何れも含有しないガラス組成物を用い、強化処理を行うことなく、下記式（１）から算出される熱衝撃度数（Ｈ）が４０より大きいガラス基板を製造することを特徴とするガラス基板の製造方法。
熱衝撃度数(H)=500×(1/(α×107))2＋30×(Kc)8＋0.05×(E/ρ)＋0.02×Tg・・・（１）
（式中、α:線熱膨張係数（２５〜１００℃、１／℃）、Ｋｃ:破壊靭性値（ＭＰａ・ｍ１／２）、Ｅ/ρ:比弾性率(Ｇｐａ)、Ｔｇ:ガラス転移温度(℃)）% By weight
SiO 2: 62.5~75%,
Al 2 O 3 : 1 to 20%,
B 2 O 3 : 0 to 8% (including zero),
SiO 2 + Al 2 O 3 + B 2 O 3 : 60 to 90%,
Li 2 O: 0.1 to 15%
Na 2 O: 0.1 to 15%
K 2 O: 0.1~10%
Total amount of R 2 O (R = Li, Na, K): 0.3-18%,
R'O (R '= Mg, C a, Z n) the total amount of: 0 to 3.0% (including zero),
TiO 2 as essential components, TiO 2 + ZrO 2 + Ln x O y: 0~12% ( however, Ln x O y is a group consisting of lanthanoid metal oxides and Y 2 O 3, Nb 2 O 5, Ta 2 O 5 Each glass component), meaning at least one compound selected from
BaO, and SrO both used including no glass composition, without the strengthening process, that thermal shock frequency calculated from the following equation (1) (H) to produce a greater than 40 glass substrate A method for producing a glass substrate .
Thermal shock frequency (H) = 500 × (1 / (α × 10 7 )) 2 + 30 × (Kc) 8 + 0.05 × (E / ρ) + 0.02 × Tg (1)
(Wherein, α: linear thermal expansion coefficient (25-100 ° C., 1 / ° C.), Kc: fracture toughness value (MPa · m 1/2 ), E / ρ: specific elastic modulus (Gpa), Tg: glass transition Temperature (℃)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003153238A JP4726400B2 (en) | 2003-05-29 | 2003-05-29 | Manufacturing method of glass substrate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003153238A JP4726400B2 (en) | 2003-05-29 | 2003-05-29 | Manufacturing method of glass substrate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2004352571A JP2004352571A (en) | 2004-12-16 |
| JP4726400B2 true JP4726400B2 (en) | 2011-07-20 |
Family
ID=34048244
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2003153238A Expired - Fee Related JP4726400B2 (en) | 2003-05-29 | 2003-05-29 | Manufacturing method of glass substrate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4726400B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104246883A (en) * | 2012-03-29 | 2014-12-24 | Hoya株式会社 | Glass for magnetic recording medium substrate, and glass substrate for magnetic recording medium and use thereof |
| CN104303231A (en) * | 2012-05-16 | 2015-01-21 | Hoya株式会社 | Glass for magnetic recording medium substrate and use for same |
| US10189741B2 (en) | 2014-10-08 | 2019-01-29 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4726399B2 (en) | 2003-05-29 | 2011-07-20 | コニカミノルタオプト株式会社 | Glass substrate |
| JP4790300B2 (en) * | 2005-04-14 | 2011-10-12 | 株式会社日立製作所 | Glass |
| JP2009528673A (en) * | 2006-01-03 | 2009-08-06 | コーニング インコーポレイテッド | Germanium structure on glass and glass ceramic |
| JP5720499B2 (en) * | 2010-10-26 | 2015-05-20 | 旭硝子株式会社 | Substrate glass and glass substrate |
| JP5609636B2 (en) * | 2010-12-28 | 2014-10-22 | 旭硝子株式会社 | GLASS PLATE QUALITY TEST METHOD, GLASS PLATE QUALITY TEST DEVICE, AND GLASS PLATE MANUFACTURING METHOD |
| US8885447B2 (en) | 2012-03-29 | 2014-11-11 | Hoya Corporation | Glass for magnetic recording medium substrate, glass substrate for magnetic recording medium, and their use |
| US9139469B2 (en) | 2012-07-17 | 2015-09-22 | Corning Incorporated | Ion exchangeable Li-containing glass compositions for 3-D forming |
| CN108101358B (en) * | 2017-12-15 | 2021-05-18 | 成都光明光电股份有限公司 | Glass composition |
| CN112851142A (en) * | 2018-06-08 | 2021-05-28 | 康宁股份有限公司 | Shatter stress distribution in glass |
| JP2022512405A (en) | 2018-12-12 | 2022-02-03 | コーニング インコーポレイテッド | Ion-exchangeable lithium-containing aluminosilicate glass |
| CN110255895B (en) * | 2019-07-16 | 2021-04-13 | 湖南旗滨医药材料科技有限公司 | Alkali-containing borosilicate glass and preparation method thereof |
| CN117486486A (en) * | 2022-07-20 | 2024-02-02 | 荣耀终端有限公司 | Yttrium aluminium silicate glass, its preparation method and electronic equipment |
-
2003
- 2003-05-29 JP JP2003153238A patent/JP4726400B2/en not_active Expired - Fee Related
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104246883A (en) * | 2012-03-29 | 2014-12-24 | Hoya株式会社 | Glass for magnetic recording medium substrate, and glass substrate for magnetic recording medium and use thereof |
| CN104303231A (en) * | 2012-05-16 | 2015-01-21 | Hoya株式会社 | Glass for magnetic recording medium substrate and use for same |
| US10189741B2 (en) | 2014-10-08 | 2019-01-29 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US10239780B2 (en) | 2014-10-08 | 2019-03-26 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US10427975B2 (en) | 2014-10-08 | 2019-10-01 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US11034610B2 (en) | 2014-10-08 | 2021-06-15 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US11148968B2 (en) | 2014-10-08 | 2021-10-19 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US11168021B2 (en) | 2014-10-08 | 2021-11-09 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US11174194B2 (en) | 2014-10-08 | 2021-11-16 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US11319244B2 (en) | 2014-10-08 | 2022-05-03 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US11384010B2 (en) | 2014-10-08 | 2022-07-12 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US11634357B2 (en) | 2014-10-08 | 2023-04-25 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
| US11952306B2 (en) | 2014-10-08 | 2024-04-09 | Corning Incorporated | High strength glass-ceramics having petalite and lithium silicate structures |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2004352571A (en) | 2004-12-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4530618B2 (en) | Glass composition and glass substrate | |
| JP4039381B2 (en) | Glass substrate for information recording medium using glass composition and information recording medium using the same | |
| JP4726399B2 (en) | Glass substrate | |
| JP4337821B2 (en) | Glass substrate for information recording medium and information recording medium using the same | |
| JP4282273B2 (en) | Glass substrate | |
| JP5613164B2 (en) | Glass substrate for information recording medium and information recording medium | |
| US8916487B2 (en) | Glass substrate for information recording medium | |
| WO2013172247A1 (en) | Glass for magnetic recording medium substrate and use for same | |
| JP4726400B2 (en) | Manufacturing method of glass substrate | |
| JP2006327935A (en) | Glass substrate | |
| JP2023166439A (en) | Glass for magnetic recording medium substrate or for glass spacer for magnetic recording/reproducing device, magnetic recording medium substrate, magnetic recording medium, glass spacer for magnetic recording/reproducing device, and magnetic recording/reproducing device | |
| JP7165655B2 (en) | Glass for information recording medium substrate, information recording medium substrate, information recording medium and glass spacer for recording/reproducing device | |
| JP4161756B2 (en) | Glass substrate | |
| JP2006327936A (en) | Glass substrate | |
| JP4151440B2 (en) | Glass substrate | |
| JP4225086B2 (en) | Glass substrate | |
| JP3793401B2 (en) | Substrate for information recording medium made of crystallized glass and information recording medium | |
| JP5375698B2 (en) | Manufacturing method of glass substrate | |
| JP4442051B2 (en) | Glass substrate, information recording medium using the same, and optical communication element |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A712 Effective date: 20050615 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20050622 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060323 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20070626 |
|
| RD03 | Notification of appointment of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7423 Effective date: 20070628 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20070824 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20071204 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20080125 |
|
| A911 | Transfer to examiner for re-examination before appeal (zenchi) |
Free format text: JAPANESE INTERMEDIATE CODE: A911 Effective date: 20080226 |
|
| A912 | Re-examination (zenchi) completed and case transferred to appeal board |
Free format text: JAPANESE INTERMEDIATE CODE: A912 Effective date: 20080321 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20110314 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20110412 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 Ref document number: 4726400 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140422 Year of fee payment: 3 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313113 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R360 | Written notification for declining of transfer of rights |
Free format text: JAPANESE INTERMEDIATE CODE: R360 |
|
| R360 | Written notification for declining of transfer of rights |
Free format text: JAPANESE INTERMEDIATE CODE: R360 |
|
| R371 | Transfer withdrawn |
Free format text: JAPANESE INTERMEDIATE CODE: R371 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313113 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |