JP3665664B2 - Method for producing opaque quartz glass - Google Patents

Method for producing opaque quartz glass Download PDF

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Publication number
JP3665664B2
JP3665664B2 JP11767595A JP11767595A JP3665664B2 JP 3665664 B2 JP3665664 B2 JP 3665664B2 JP 11767595 A JP11767595 A JP 11767595A JP 11767595 A JP11767595 A JP 11767595A JP 3665664 B2 JP3665664 B2 JP 3665664B2
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Prior art keywords
silicon dioxide
quartz glass
dioxide powder
melting point
opaque quartz
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JPH08290926A (en
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恭一 稲木
宜正 吉田
護 遠藤
仁 関根
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Shin Etsu Quartz Products Co Ltd
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Shin Etsu Quartz Products Co Ltd
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    • 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
    • C03C3/06—Glass compositions containing silica with more than 90% silica by weight, e.g. quartz
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/09—Other methods of shaping glass by fusing powdered glass in a shaping mould
    • 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
    • C03C2201/00—Glass compositions
    • C03C2201/80—Glass compositions containing bubbles or microbubbles, e.g. opaque quartz glass
    • 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
    • C03C2203/00—Production processes
    • C03C2203/10—Melting processes

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Glass Melting And Manufacturing (AREA)

Description

【０００１】
【産業上の利用分野】
本発明は、高純度で耐熱性が高く、しかも遮熱性の優れた不透明石英ガラス、特に熱処理炉の赤外線散乱および遮熱材料として有用な不透明石英ガラスを効率的に製造する方法に関する。
【０００２】
【従来の技術】
従来、石英ガラスは、高い純度を有し、耐熱性に優れているところから半導体工業用の熱処理炉や熱処理用治具材料として用いられてきた。ところが、前記半導体工業用の熱処理炉は、炉内の温度分布が非常に重要であり、炉内温度を均一にするため、例えば特開平５−９００号公報に開示されているように不透明石英ガラスで炉芯管を形成したり、あるいは実開平１−１６２２３４号公報に開示されているように半導体ウエハ−を載置するボ−トの両端に不透明石英ガラスの熱線散乱板を設けたりしていた。
【０００３】
上記不透明石英ガラス板等の製造には中実の不透明石英ガラスブロックを板状に切り出すのが効率的であり、そのために原料の二酸化珪素粉を耐熱性型内に充填した後、電気炉で加熱溶融して不透明石英ガラスブロックを製造する方法（以下充填式溶融法という）が採用されてきた。ところが、従来の充填式溶融法にあっては、溶融時に最も温度が上がり易い下部表層部で最初の溶融が起こり、次いで側胴表層部に溶融が起こり、最後に上部表層部へと溶融が進む。一方、中心部では、側胴表層部から中心部にかけて温度勾配が発生し、下部中心から上部中心へと溶融が進む。そのため中心部が完全に溶融される前に、上部表層部の溶融が進み中心部で発生したガスが抜けず、図２（ａ）に示すように中心部に大きな泡８が形成されたり、あるいは図２（ｂ）に示すように大きな泡が集まった鬚９が形成されたりし、均質な不透明石英ガラスブロックが得られなかった。
【０００４】
【発明が解決しようとする課題】
そこで、本発明者等は上記問題点を解決すべく鋭意研究を重ねた結果、耐熱性型内に二酸化珪素粉を充填するに際し、表層部に中心部より融点の高い二酸化珪素粉が配置するように充填することで、均質な不透明石英ガラスブロックが得られることを発見し、本発明を完成したものである。すなわち
【０００５】
本発明は、高純度で耐熱性が高く、赤外線散乱および遮熱性に優れた均質な不透明石英ガラスを製造する方法を提供することを目的とする。
【０００６】
【課題を解決するための手段】
上記目的を達成する本発明は、耐熱性型内に融点が異なる２種以上の二酸化珪素粉を充填したのち、該充填二酸化珪素粉を焼結、溶融する不透明石英ガラスの製造方法において、前記充填二酸化珪素粉の表層部が中心部より融点の高い二酸化珪素粉で充填されていることを特徴とする不透明石英ガラスの製造方法に係る。
【０００７】
上記不透明石英ガラスとは、微細な気泡が均一に分散した不透明な石英ガラスをいい、その製造に当たっては、融点が少なくとも２０℃異なる２種以上の天然に産出する結晶質石英粉、又は合成して得られた結晶質石英粉、結晶質クリストバライト粉等であって、粒度が５０〜１０００μｍ、嵩密度が１．０〜１．７ｇ／ｃｍ３、好ましくは１．２〜１．５ｇ／ｃｍ３の二酸化珪素粉が使用される。天然に産出する結晶質石英粉には、鉱脈、精製プロセス、微量不純物含量等ににより融点が少なくとも２０℃異なる石英粉が存在し、それを組合せて使用することにより耐熱性に優れた不透明石英ガラスブロックを得ることができる。また、ゾル−ゲル法等で合成した結晶質クリストバライト粉は、天然に産出する結晶質石英粉より更に融点が約３０℃程度高いことから本発明の表層部形成原料として好適である。本発明の製造方法において、中心部の二酸化珪素粉の粒度が前記範囲から外れると微細な気泡を有する不透明石英ガラスが得られず、また二酸化珪素粉の嵩密度が１．０ｇ／ｃｍ３未満では二酸化珪素粉が断熱材となって焼結が中心部まで進まず、外周部だけが溶融された不中実な不透明石英ガラスブロックとなる。さらに嵩密度が１．７ｇ／ｃｍ３を越える二酸化珪素粉は、前記粒度範囲では困難である。
【０００８】
一方、溶融して得られた不透明石英ガラスブロックの嵩密度は、１．７〜２．１５ｇ／ｃｍ3の範囲が良い。嵩密度が１．７ｇ／ｃｍ3未満では、気泡の含有量が多く機械的強度が低下し、また嵩密度が２．１５ｇ／ｃｍ3を越えると透明度が増し光の散乱効果が低下する。
【０００９】
本発明の製造方法にあっては、図１又は２に示すように耐熱性型内の中心部に融点の低い二酸化珪素粉を充填し、その周囲に融点の高い二酸化珪素粉を層状に充填し、それを非酸化性雰囲気下で焼結、溶融することからなる。前記二酸化珪素粉の充填方法としては、耐熱性型内にガラス製仕切板を配置し、表層部と中心部を形成し、該表層部に融点の高い二酸化珪素粉を、また中心部には融点の低い二酸化珪素粉を充填し、充填終了後ガラス製仕切板を抜き取る等の方法や耐熱性型に先ず融点の低い二酸化珪素粉を充填し、その上部に融点の高い二酸化珪素粉を充填する方法等が採用される。特に後者の充填方法は、効率的に不透明石英ガラスを製造するための充填方法として好適である。前記二酸化珪素粉の充填した型を電気炉内に設置し、１０-2ｔｏｒｒ以下に真空排気し粒子間に残留している空気を除去したのち、炉内を窒素で真空破壊し、５ｌ／ｍｉｎの流量で窒素を流しながら室温から融点の最も高い結晶質二酸化珪素粉の融点未満まで温度を上昇して二酸化珪素粉の焼結、溶融を行う。前記温度の上昇方法としては好ましくは室温から１０００℃までは１０〜５０℃／分の昇温速度で、１０００℃を超え融点が最も低い結晶質二酸化珪素粉の融点又は該融点より１０℃高い温度までは１０℃／分以下の昇温速度で、さらに融点の最も高い結晶質二酸化珪素粉の融点未満まではゆっくりした昇温速度で上昇するのが良い。前記温度上昇により、気泡径１０〜３００μｍ、気泡密度１００，０００〜１，０００，０００個／ｃｍ3の微細な気泡が均一に分散した不透明石英ガラスブロックが得られる。
【００１０】
上記製造方法で使用する耐熱性型としては、カーボン製型、セラミック製型、及び前記型枠内に透明石英ガラス管等を挿入した型等がが用いられる。特に、透明石英ガラス管の使用は、原料の高純度が維持されるとともに、製造されるシリカガラスに形崩れが起らず良好な不透明石英ガラスブロックが得られるので好ましい。また、溶融時の雰囲気は、窒素ガス雰囲気等の不活性ガス雰囲気や真空雰囲気が用いられるが、耐熱性型がカーボン性のときは、不活性ガス雰囲気を必須する。耐熱性型がセラミックス製であれば、任意の雰囲気を選択することができる。
【００１１】
以下に本発明を実施例で詳しく説明するが、本発明はその実施例に限定されるものではない。
【００１２】
【実施例】
実施例１
図１に示す内径２７０ｍｍ、高さ３００ｍｍのグラファイト製型１内に、外径２７０ｍｍ、肉厚４ｍｍ、高さ３００ｍｍの石英ガラス管２を挿入した。前記石英ガラス管２内に、粒径が５０〜２００μｍ、平均粒径が約１００μｍ、嵩密度が１．４ｇ／ｃｍ3、融点が１７３０℃の天然石英結晶粉３を充填し、その上層部に粒径が５０〜２００μｍ、平均粒径が約１００μｍ、嵩密度が１．４ｇ／ｃｍ3、融点が１７８０℃の天然石英結晶粉４を厚さ１ｃｍに充填し、それを電気炉内に設置し、１０-2ｔｏｒｒ以下に真空排気し粒子間に残留している空気を除去したのち、炉内を窒素で真空破壊し、５ｌ／ｍｉｎの流量で窒素を流しながら室温から１２００℃までを１２０分、１２００℃〜１６３０℃までを９０分、１６３０℃〜１７５０℃までを２４０分で昇温し、次いで１７５０℃に６０分保持し、加熱を止めて室温まで冷却し、不透明石英ガラスブロックを取り出した。得られた不透明石英ガラスブロックの上部から１０ｍｍの部分をカットし、鬚の発生の有無を調べた。その結果を表１に示す。
【００１３】
実施例２
図２に示すように内径２７０ｍｍ、高さ３００ｍｍのグラファイト製型１内にガラス製仕切板６で１ｃｍ厚さの表層部が形成できるように型内部を仕切り、前記表層部に粒径が５０〜２００μｍ、平均粒径が約１００μｍ、嵩密度が１．４ｇ／ｃｍ3、融点が１７８０℃の天然石英結晶粉４を型の底部及び胴部の厚さが１ｃｍとなるように充填し、次いで粒径５０〜２００μｍ、平均粒径が約１００μｍ、嵩密度が１．４ｇ／ｃｍ3、融点が１７３０℃の天然石英結晶粉３を中心部に充填し、ガラス製仕切板６を抜き取った後、実施例１と同様に室温から１２００℃までを１２０分で、１２００℃〜１６３０℃までを９０分で、１６３０℃〜１７５０℃までを２４０分で昇温し、最後に１７５０℃に６０分保持したのち、加熱を止めて室温まで冷却し、不透明石英ガラスブロックを取り出した。得られた不透明石英ガラスブロックの上部から１０ｍｍの部分をカットし、鬚の発生の有無を調べた。その結果を表１に示す。
【００１４】
比較例１
内径２７０ｍｍ、高さ３００ｍｍのグラファイト製型内に、粒径が５０〜２００μｍ、平均粒径が約１００μｍ、嵩密度が１．４ｇ／ｃｍ3、融点が１７５０℃の天然石英結晶粉を充填し、それを実施例１と同様に焼結、溶融して不透明石英ガラスブロックを製造した。得られた不透明石英ガラスブロックについて実施例１と同様に鬚の有無を調べた。その結果を表１に示す。
【００１５】
実施例３
実施例１と同様に図１に示す内径２７０ｍｍ、高さ３００ｍｍのグラファイト製型１内に、外径２７０ｍｍ、肉厚４ｍｍ、高さ３００ｍｍの石英ガラス管２を挿入し、該ガラス管２内に、粒径が２５０〜５００μｍ、平均粒径が約３５０μｍ、嵩密度が１．３ｇ／ｃｍ3、融点が１７８０℃の天然石英結晶質粉を充填した。この天然石英結晶質粉の上層部に粒径が２５０〜５００μｍ、平均粒径が約３５０μｍ、融点が１８１０℃の合成クリストバライト結晶粉４′を厚さ１ｃｍに充填し、それを電気炉内に設置し、１０-2ｔｏｒｒ以下に真空排気し粒子間に残留している空気を除去したのち、炉内を窒素で真空破壊し、５ｌ／ｍｉｎの流量で窒素を流しながら室温から１２００℃までを１２０分、１２００℃〜１６３０℃までを９０分、１６３０℃〜１８００℃までを３４０分で昇温し、最後に１８００℃に６０分保持したのち、加熱を止めて室温まで冷却し、不透明石英ガラスブロックを取り出した。得られた不透明石英ガラスブロックについて実施例１と同様に鬚の有無を調べた。その結果を表１に示す。
【００１６】
【表１】

Figure 0003665664
【００１７】
【発明の効果】
本発明の製造方法では、融点の異なる二酸化珪素粉を融点が高い二酸化珪素粉が表層部になるように充填し、それを融点の低い二酸化珪素粉の融点以上に加熱するという簡便な方法で均質な不透明石英ガラスブロックを製造することができ、それを切り出すことで、赤外線散乱および遮熱性の優れた不透明石英ガラス板が得られる。
【図面の簡単な説明】
【図１】本発明の製造方法の１態様を示す。
【図２】本発明の製造方法の他の態様を示す。
【図３】従来の充填式溶融方法による不透明石英ガラスの製造方法を示す。
【符号の説明】
１ 耐熱製型
２ 石英ガラス管
３ 融点の低い二酸化珪素粉
４ 融点の高い二酸化珪素粉
４´合成クリストバライト結晶粉
５ ヒーター
６ 石英ガラス製仕切板
７ ガラスマトリックス
８ 微細気泡
９ 大気泡
１０ 鬚[0001]
[Industrial application fields]
The present invention relates to an opaque quartz glass having high purity, high heat resistance and excellent heat shielding, and more particularly to a method for efficiently producing opaque quartz glass useful as an infrared scattering and heat shielding material in a heat treatment furnace.
[0002]
[Prior art]
Conventionally, quartz glass has been used as a heat treatment furnace or heat treatment jig material for the semiconductor industry because of its high purity and excellent heat resistance. However, in the heat treatment furnace for the semiconductor industry, the temperature distribution in the furnace is very important, and in order to make the furnace temperature uniform, for example, as disclosed in JP-A-5-900, opaque quartz glass is used. Or a heat ray scattering plate made of opaque quartz glass was provided at both ends of a boat on which a semiconductor wafer was placed as disclosed in Japanese Utility Model Laid-Open No. 1-162234. .
[0003]
It is efficient to cut a solid opaque quartz glass block into a plate shape for the production of the opaque quartz glass plate and the like. For this purpose, the silicon dioxide powder as a raw material is filled in a heat-resistant mold and then heated in an electric furnace. A method of melting and producing an opaque quartz glass block (hereinafter referred to as a filling melting method) has been adopted. However, in the conventional filling type melting method, the first melting occurs in the lower surface layer portion where the temperature is most likely to rise during melting, then the melting occurs in the side body surface layer portion, and finally the melting proceeds to the upper surface layer portion. . On the other hand, in the central portion, a temperature gradient is generated from the side trunk surface layer portion to the central portion, and melting proceeds from the lower center to the upper center. Therefore, before the center part is completely melted, the upper surface layer part melts and the gas generated in the center part does not escape, and a large bubble 8 is formed in the center part as shown in FIG. As shown in FIG. 2B, ridges 9 in which large bubbles gathered were formed, and a homogeneous opaque quartz glass block could not be obtained.
[0004]
[Problems to be solved by the invention]
Therefore, as a result of intensive studies to solve the above problems, the present inventors have found that silicon dioxide powder having a melting point higher than that of the central portion is arranged in the surface layer portion when filling the silicon dioxide powder in the heat-resistant mold. It has been found that a homogeneous opaque quartz glass block can be obtained by filling in, and the present invention has been completed. That is, [0005]
An object of the present invention is to provide a method for producing a homogeneous opaque quartz glass having high purity, high heat resistance, and excellent infrared scattering and heat shielding properties.
[0006]
[Means for Solving the Problems]
The present invention that achieves the above object provides a method for producing an opaque quartz glass in which a heat-resistant mold is filled with two or more types of silicon dioxide powders having different melting points, and then the filled silicon dioxide powder is sintered and melted. The present invention relates to a method for producing opaque quartz glass, wherein a surface layer portion of silicon dioxide powder is filled with silicon dioxide powder having a melting point higher than that of the center portion.
[0007]
The opaque quartz glass refers to an opaque quartz glass in which fine bubbles are uniformly dispersed, and in the production thereof, two or more kinds of naturally occurring crystalline quartz powders having melting points different by at least 20 ° C. , or synthesized The obtained crystalline quartz powder, crystalline cristobalite powder, etc. , having a particle size of 50 to 1000 μm and a bulk density of 1.0 to 1.7 g / cm 3 , preferably 1.2 to 1.5 g / cm 3 Silicon dioxide powder is used. Naturally produced crystalline quartz powder includes quartz powder having a melting point that differs by at least 20 ° C. depending on the vein, refining process, trace impurity content, etc., and by using these in combination, opaque quartz glass with excellent heat resistance You can get a block. In addition, crystalline cristobalite powder synthesized by the sol-gel method or the like is suitable as a raw material for forming the surface layer of the present invention because it has a melting point of about 30 ° C. higher than that of naturally produced crystalline quartz powder. In the production method of the present invention, when the particle size of the silicon dioxide powder at the center part is out of the above range, an opaque quartz glass having fine bubbles cannot be obtained, and the bulk density of the silicon dioxide powder is less than 1.0 g / cm 3. The silicon dioxide powder becomes a heat insulating material, so that sintering does not proceed to the central portion, and only the outer peripheral portion is melted to become an innocent opaque quartz glass block. Furthermore, silicon dioxide powder having a bulk density exceeding 1.7 g / cm 3 is difficult in the above particle size range.
[0008]
On the other hand, the bulk density of the opaque quartz glass block obtained by melting is preferably in the range of 1.7 to 2.15 g / cm 3 . When the bulk density is less than 1.7 g / cm 3 , the bubble content is large and the mechanical strength is lowered. When the bulk density exceeds 2.15 g / cm 3 , the transparency is increased and the light scattering effect is lowered.
[0009]
In the production method of the present invention, as shown in FIG. 1 or 2, the silicon dioxide powder having a low melting point is filled in the central portion of the heat-resistant mold, and the silicon dioxide powder having a high melting point is filled in layers around the center. And sintering and melting it in a non-oxidizing atmosphere. As a filling method of the silicon dioxide powder, a glass partition plate is disposed in a heat-resistant mold, a surface layer portion and a center portion are formed, silicon dioxide powder having a high melting point is formed in the surface layer portion, and a melting point is formed in the center portion. A method such as filling a silicon dioxide powder having a low melting point, filling a silicon dioxide powder having a low melting point into a heat-resistant mold, and then filling a silicon dioxide powder having a high melting point on the top. Etc. are adopted. In particular, the latter filling method is suitable as a filling method for efficiently producing opaque quartz glass. The mold filled with silicon dioxide powder was placed in an electric furnace, evacuated to 10 −2 torr or less to remove the air remaining between the particles, and the furnace was vacuum broken with nitrogen to give 5 l / min. While flowing nitrogen at a flow rate of, the temperature is raised from room temperature to below the melting point of the crystalline silicon dioxide powder having the highest melting point to sinter and melt the silicon dioxide powder. Preferably, the temperature is raised from room temperature to 1000 ° C. at a rate of temperature increase of 10 to 50 ° C./min, and the melting point of crystalline silicon dioxide powder having a melting point exceeding 1000 ° C. or the lowest melting point is 10 ° C. or higher. It is preferable that the temperature rises at a rate of 10 ° C./min or less until it is lower than the melting point of the crystalline silicon dioxide powder having the highest melting point, and at a slow rate of temperature rise. By the temperature increase, an opaque quartz glass block in which fine bubbles having a bubble diameter of 10 to 300 μm and a bubble density of 100,000 to 1,000,000 / cm 3 are uniformly dispersed is obtained.
[0010]
As the heat-resistant mold used in the above production method, a carbon mold, a ceramic mold, and a mold in which a transparent quartz glass tube or the like is inserted into the mold are used. In particular, the use of a transparent quartz glass tube is preferable because the high purity of the raw material is maintained and the silica glass to be produced is not deformed and a good opaque quartz glass block is obtained. In addition, an inert gas atmosphere such as a nitrogen gas atmosphere or a vacuum atmosphere is used as the melting atmosphere, but when the heat resistant mold is carbon, an inert gas atmosphere is essential. If the heat resistant mold is made of ceramics, any atmosphere can be selected.
[0011]
EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples.
[0012]
【Example】
Example 1
A quartz glass tube 2 having an outer diameter of 270 mm, a wall thickness of 4 mm, and a height of 300 mm was inserted into a graphite mold 1 having an inner diameter of 270 mm and a height of 300 mm shown in FIG. The quartz glass tube 2 is filled with natural quartz crystal powder 3 having a particle size of 50 to 200 μm, an average particle size of about 100 μm, a bulk density of 1.4 g / cm 3 and a melting point of 1730 ° C. A natural quartz crystal powder 4 having a particle size of 50 to 200 μm, an average particle size of about 100 μm, a bulk density of 1.4 g / cm 3 , and a melting point of 1780 ° C. is filled to a thickness of 1 cm and placed in an electric furnace. After evacuating to 10 -2 torr or less and removing the air remaining between the particles, the inside of the furnace is vacuum-ruptured with nitrogen, and from room temperature to 1200 ° C for 120 minutes while flowing nitrogen at a flow rate of 5 l / min. The temperature was raised from 1200 ° C. to 1630 ° C. for 90 minutes, and from 1630 ° C. to 1750 ° C. in 240 minutes, then held at 1750 ° C. for 60 minutes, stopped heating and cooled to room temperature, and the opaque quartz glass block was taken out. . A 10 mm portion was cut from the upper part of the obtained opaque quartz glass block, and the presence or absence of wrinkles was examined. The results are shown in Table 1.
[0013]
Example 2
As shown in FIG. 2, the interior of the mold is partitioned so that a surface layer portion having a thickness of 1 cm can be formed by a glass partition plate 6 in a graphite mold 1 having an inner diameter of 270 mm and a height of 300 mm. 200 μm, an average particle size of about 100 μm, a bulk density of 1.4 g / cm 3 and a melting point of 1780 ° C. are filled with natural quartz crystal powder 4 so that the thickness of the bottom and body of the mold is 1 cm. Filled with natural quartz crystal powder 3 having a diameter of 50 to 200 μm, an average particle size of about 100 μm, a bulk density of 1.4 g / cm 3 , and a melting point of 1730 ° C. in the center, and after removing the glass partition plate 6 As in Example 1, the temperature was raised from room temperature to 1200 ° C. for 120 minutes, from 1200 ° C. to 1630 ° C. in 90 minutes, from 1630 ° C. to 1750 ° C. in 240 minutes, and finally held at 1750 ° C. for 60 minutes. , Stop heating to room temperature And retirement was removed an opaque silica glass block. A 10 mm portion was cut from the upper part of the obtained opaque quartz glass block, and the presence or absence of wrinkles was examined. The results are shown in Table 1.
[0014]
Comparative Example 1
A graphite mold having an inner diameter of 270 mm and a height of 300 mm is filled with natural quartz crystal powder having a particle size of 50 to 200 μm, an average particle size of about 100 μm, a bulk density of 1.4 g / cm 3 , and a melting point of 1750 ° C. This was sintered and melted in the same manner as in Example 1 to produce an opaque quartz glass block. The obtained opaque quartz glass block was examined for the presence of wrinkles in the same manner as in Example 1. The results are shown in Table 1.
[0015]
Example 3
As in Example 1, a quartz glass tube 2 having an outer diameter of 270 mm, a wall thickness of 4 mm, and a height of 300 mm is inserted into a graphite mold 1 having an inner diameter of 270 mm and a height of 300 mm shown in FIG. A natural quartz crystalline powder having a particle size of 250 to 500 μm, an average particle size of about 350 μm, a bulk density of 1.3 g / cm 3 and a melting point of 1780 ° C. was filled. A synthetic cristobalite crystal powder 4 'having a particle size of 250-500 μm, an average particle size of about 350 μm, and a melting point of 1810 ° C. is filled to a thickness of 1 cm on the upper layer of the natural quartz crystalline powder, and this is installed in an electric furnace. Then, after evacuating to 10 −2 torr or less and removing the air remaining between the particles, the inside of the furnace was vacuum-breaked with nitrogen, and the temperature was increased from room temperature to 1200 ° C. while flowing nitrogen at a flow rate of 5 l / min. The temperature is raised from 1200 ° C to 1630 ° C for 90 minutes, from 1630 ° C to 1800 ° C in 340 minutes, and finally held at 1800 ° C for 60 minutes. Was taken out. The obtained opaque quartz glass block was examined for the presence of wrinkles in the same manner as in Example 1. The results are shown in Table 1.
[0016]
[Table 1]
Figure 0003665664
[0017]
【The invention's effect】
In the production method of the present invention, silicon dioxide powder having a different melting point is filled so that the silicon dioxide powder having a higher melting point becomes a surface layer portion, and then heated to a temperature equal to or higher than the melting point of the silicon dioxide powder having a lower melting point. An opaque quartz glass block can be produced, and by cutting it, an opaque quartz glass plate excellent in infrared scattering and heat shielding properties can be obtained.
[Brief description of the drawings]
FIG. 1 shows one embodiment of the production method of the present invention.
FIG. 2 shows another embodiment of the production method of the present invention.
FIG. 3 shows a method for producing opaque quartz glass by a conventional filling melting method.
[Explanation of symbols]
1 Heat-resistant mold 2 Quartz glass tube 3 Low melting point silicon dioxide powder 4 High melting point silicon dioxide powder 4 'Synthetic cristobalite crystal powder 5 Heater 6 Quartz glass partition plate 7 Glass matrix 8 Fine bubbles 9 Large bubbles 10

Claims (3)

耐熱性型内に融点が異なる２種以上の結晶質二酸化珪素粉を充填したのち、該充填二酸化珪素粉を焼結、溶融する不透明石英ガラスの製造方法において、前記融点が異なる２種以上の結晶質二酸化珪素粉の粒度が５０〜１０００μｍ、嵩密度が１．０〜１．７ｇ／ｃｍ３の範囲にあり、かつ充填二酸化珪素粉の表層部が中心部より融点の高い結晶質二酸化珪素粉で充填されていることを特徴とする不透明石英ガラスの製造方法。In a method for producing opaque quartz glass, in which two or more types of crystalline silicon dioxide powders having different melting points are filled in a heat-resistant mold, and then the filled silicon dioxide powder is sintered and melted, two or more types of crystals having different melting points are used. quality granularity of the silicon dioxide powder is 50 to 1000 [mu] m, in the range bulk density of 1.0~1.7g / cm 3, and a surface layer portion of the filling silicon dioxide powder with high crystalline silicon dioxide powder the melting points of the center portion A method for producing opaque quartz glass, which is filled. 耐熱性型内に融点の低い結晶質二酸化珪素粉を充填し、次いで前記二酸化珪素粉層の上部に融点の高い結晶質二酸化珪素粉を充填したのち焼成、溶融することを特徴とする請求項１記載の不透明石英ガラスの製造方法。2. The heat-resistant mold is filled with crystalline silicon dioxide powder having a low melting point, and then filled with crystalline silicon dioxide powder having a high melting point on the silicon dioxide powder layer, followed by firing and melting. The manufacturing method of the opaque quartz glass of description. 表層部の結晶質二酸化珪素粉の融点が中心部の結晶質二酸化珪素粉の融点より少なくとも２０℃高いことを特徴とする請求項１又は２記載の不透明石英ガラスの製造方法。Method for producing opaque quartz glass according to claim 1 or 2, wherein the melting point of the crystalline silicon dioxide powder of the surface layer portion may be higher at least 20 ° C. above the melting point of the crystalline silicon dioxide powder in the center.
JP11767595A 1995-04-20 1995-04-20 Method for producing opaque quartz glass Expired - Fee Related JP3665664B2 (en)

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