JP2000086251A - Method for sintering sintered quartz glass molding - Google Patents

Method for sintering sintered quartz glass molding

Info

Publication number
JP2000086251A
JP2000086251A JP28045498A JP28045498A JP2000086251A JP 2000086251 A JP2000086251 A JP 2000086251A JP 28045498 A JP28045498 A JP 28045498A JP 28045498 A JP28045498 A JP 28045498A JP 2000086251 A JP2000086251 A JP 2000086251A
Authority
JP
Japan
Prior art keywords
sintering
sintered
quartz glass
molding
moganite
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.)
Pending
Application number
JP28045498A
Other languages
Japanese (ja)
Inventor
Koji Tagawa
幸治 田川
Kenji Morinaga
健次 森永
Tetsuya Torikai
哲哉 鳥飼
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ushio Denki KK
Ushio Inc
Original Assignee
Ushio Denki KK
Ushio Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Ushio Denki KK, Ushio Inc filed Critical Ushio Denki KK
Priority to JP28045498A priority Critical patent/JP2000086251A/en
Publication of JP2000086251A publication Critical patent/JP2000086251A/en
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B32/00—Thermal after-treatment of glass products not provided for in groups C03B19/00, C03B25/00 - C03B31/00 or C03B37/00, e.g. crystallisation, eliminating gas inclusions or other impurities; Hot-pressing vitrified, non-porous, shaped glass products
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/06—Other methods of shaping glass by sintering, e.g. by cold isostatic pressing of powders and subsequent sintering, by hot pressing of powders, by sintering slurries or dispersions not undergoing a liquid phase reaction
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/06—Other methods of shaping glass by sintering, e.g. by cold isostatic pressing of powders and subsequent sintering, by hot pressing of powders, by sintering slurries or dispersions not undergoing a liquid phase reaction
    • C03B19/066—Other methods of shaping glass by sintering, e.g. by cold isostatic pressing of powders and subsequent sintering, by hot pressing of powders, by sintering slurries or dispersions not undergoing a liquid phase reaction for the production of quartz or fused silica articles
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B20/00—Processes specially adapted for the production of quartz or fused silica articles, not otherwise provided for

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Glass Melting And Manufacturing (AREA)

Abstract

PROBLEM TO BE SOLVED: To obtain a crystal-free dense transparent sintered quartz glass which does not get cloudy or crack even after long-time use at a high temperature by selecting a partial pressure of oxygen in a sintering atmosphere and a sintering temperature at which Moganite is formed in a sintering process and carrying out sintering. SOLUTION: A sintered quartz glass molding is sintered in an atmosphere at <=10-2Pa partial pressure of oxygen and >=1,530 deg.K sintering temperature. Microcrystals of cristobalite, β-quartz, etc., formed on the surface of the molding are not further formed and Moganite as one of polymorphisms of silica is formed. Since the formed Moganite is released from the surface at >=1,530 deg.K, the objective dense sintered quartz glass is obtd. A slurry is prepd. from silica powder of 1.5 μm average particle diameter, poured into a gypsum mold and dried to form a primary molding. This molding is heated in hydrogen at 1,273 deg.K for about 1 hr and the resultant temporarily sintered molding is sintered at a partial pressure of oxygen and a sintering temperature at which is formed. The sintered molding does not get cloudy or crack even after long-time use at >=973 deg.K.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、透明な焼結石英ガ
ラス成形体の焼結方法に関する。[0001] The present invention relates to a method for sintering a transparent sintered quartz glass compact.

【０００２】[0002]

【従来の技術】従来、透明石英ガラスは溶融によって得
られていたが、その溶融のためには２２７３Ｋから２５
７３Ｋという高温が必要であった。2. Description of the Related Art Conventionally, transparent quartz glass has been obtained by melting.
A high temperature of 73K was required.

【０００３】この問題を解決するために、焼結法による
製造方法が提案されている。シリカを主成分とした粉末
で一次成形体を形成した後、これを１０-3〜１０-4Ｐａ
の真空中で１６７３Ｋ以上の温度で焼結することによ
り、透明な焼結石英ガラス成形体が得られることが、１
９９７年発行のJournal of the Ceramic Societyof Jap
an 105巻の１７１ページ〜１７４ページに記載されてい
る。In order to solve this problem, a manufacturing method using a sintering method has been proposed. After forming a primary compact with a powder containing silica as a main component, the primary compact is placed at 10 −3 to 10 −4 Pa
By sintering at a temperature of 1673K or more in a vacuum, a transparent sintered quartz glass molded body can be obtained.
Journal of the Ceramic Society of Jap published in 997
an 105 volume, pages 171 to 174.

【０００４】[0004]

【発明が解決しようとする課題】本発明者らによるその
後研究の結果、上記した従来方法によって得られた焼結
石英ガラス成形体には、次の問題があることが判明し
た。それは、９７３Ｋ以上の高温度で長時間使用する
と、焼結石英ガラス成形体表面に白濁が発生し、さらに
はクラックが生じて破損することがあった。この９７３
Ｋ以上のような使用条件は、超高圧水銀ランプのような
高輝度放電ランプの発光管や、半導体製造装置用の炉心
管などがある。As a result of subsequent studies by the present inventors, it has been found that the sintered quartz glass compact obtained by the above-mentioned conventional method has the following problems. When used at a high temperature of 973K or higher for a long time, the surface of the sintered quartz glass molded article may become cloudy, and furthermore, cracks may occur to cause breakage. This 973
Usage conditions such as K or higher include an arc tube of a high-intensity discharge lamp such as an ultra-high pressure mercury lamp and a furnace tube for a semiconductor manufacturing apparatus.

【０００５】そこで、本発明の課題は、９７３Ｋ以上の
高温度で長時間使用しても白濁が発生したり、クラック
が発生しない、緻密な透明焼結石英ガラス成形体を製造
する焼結方法を提供することにある。Accordingly, an object of the present invention is to provide a sintering method for producing a dense transparent sintered quartz glass molded article which does not cause turbidity or crack even when used at a high temperature of 973K or more for a long time. To provide.

【０００６】[0006]

【課題を解決するための手段】上記課題を解決するため
に、請求項１に記載の発明は、焼結過程においてモガナ
イトが生成されるような、焼結雰囲気の酸素分圧及び焼
結温度を選定して、焼結することを特徴とする焼結石英
ガラス成形体の焼結方法とするものであり、請求項２に
記載の発明は、酸素分圧が１０-2Ｐａ以下の雰囲気中
で、焼結温度が１５３０Ｋ以上で、焼結することを特徴
とする請求項１に記載の焼結石英ガラス成形体の焼結方
法とするものである。In order to solve the above-mentioned problems, the invention according to claim 1 is to reduce the oxygen partial pressure and the sintering temperature of the sintering atmosphere such that moganite is generated in the sintering process. A method for sintering a sintered quartz glass compact characterized by selecting and sintering. The invention according to claim 2 is characterized in that the oxygen partial pressure is 10 −2 Pa or less in an atmosphere. The method according to claim 1, wherein the sintering is performed at a sintering temperature of 1530K or more.

【０００７】[0007]

【作用】上記の白濁が発生し、さらにはクラックが生じ
て破損に至る原因は，以下のようであると推測される。
上記従来の方法で得られた透明な焼結石英ガラス成形体
は、光学的に透明であるが、その表面にはクリストバラ
イト（Cristobalite），ベータ水晶（β-Quartz）など
の微結晶が量は少ないが生じている。そして、この焼結
石英ガラス成形体を９７３Ｋ以上の高温度で長時間使用
すると、上記微結晶が核となって結晶化が進行し，白濁
が発生すると考えられる。さらには、これらのクリスト
バライトやベータ水晶の結晶の熱膨張率は石英ガラスの
１０倍以上あるので、石英ガラスにクラックが生じて破
損すると考えられる。The causes of the above-described cloudiness and the occurrence of cracks leading to damage are presumed to be as follows.
The transparent sintered quartz glass compact obtained by the above-mentioned conventional method is optically transparent, but has a small amount of microcrystals such as cristobalite and beta quartz (β-Quartz) on its surface. Has occurred. When this sintered quartz glass molded body is used for a long time at a high temperature of 973 K or more, it is considered that the crystallization proceeds with the microcrystals serving as nuclei, and white turbidity occurs. Furthermore, since the crystal expansion coefficient of these cristobalite and beta quartz crystals is 10 times or more that of quartz glass, it is considered that the quartz glass is cracked and damaged.

【０００８】そこで、発明者は鋭意研究の結果、透明な
焼結石英ガラス成形体が焼結時に結晶化しないための焼
結条件には、酸素分圧が大きく影響していることを見出
し、本発明を完成したものである。すなわち、真空雰囲
気、窒素雰囲気やアルゴン雰囲気等でもよく、酸素分圧
が１０-2Ｐａ以下の雰囲気でさえあれば、透明な焼結石
英ガラス成形体が焼結時に結晶を作らない焼結雰囲気と
して良いことを見出したのである。Accordingly, the present inventors have conducted intensive studies and found that the oxygen partial pressure has a great effect on the sintering conditions for the transparent sintered quartz glass compact not to crystallize during sintering. The invention has been completed. That is, a vacuum atmosphere, a nitrogen atmosphere, an argon atmosphere, or the like may be used. If the oxygen partial pressure is at most 10 −2 Pa or less, the transparent sintered quartz glass compact is used as a sintering atmosphere in which crystals do not form during sintering. I found something good.

【０００９】本発明においては、酸素の分圧が１０-2Ｐ
ａ以下の雰囲気中で、焼結温度が１５３０Ｋ以上で焼結
したので、従来、焼結体の表面に生じていたクリストバ
ライト（Cristobalite），ベータ水晶（β-Quartz）な
どの微結晶が生成されず、焼結体の表面にはシリカ鉱物
の多形の一つであるモガナイト（Moganite）が形成され
る。そして、１５３０Ｋ以上の温度では、モガナイト
（Moganite）は、不安定で昇華しやすい性質を持つの
で，焼結体の表面から離脱してしまう。このようにし
て、石英ガラスは結晶の無い緻密な焼結石英ガラスとす
ることができる。そして、焼結体の表面にクリストバラ
イト（Cristobalite），ベータ水晶（β-Quartz）など
の微結晶が無く、ガラス質のみとなるので、９７３Ｋ以
上の高温度で長時間使用しても、白濁の発生、クラック
が生じない、透明な焼結石英ガラスとすることができ
た。In the present invention, the partial pressure of oxygen is 10 −2 P
Since the sintering was performed at a sintering temperature of 1530 K or more in an atmosphere of a or less, microcrystals such as cristobalite and beta crystal (β-Quartz) which had conventionally occurred on the surface of the sintered body were not generated. On the surface of the sintered body, moganite, one of the polymorphs of the silica mineral, is formed. At a temperature of 1530 K or higher, moganite is unstable and easily sublimates, and thus detaches from the surface of the sintered body. Thus, the quartz glass can be a dense sintered quartz glass having no crystals. And since there is no microcrystal such as cristobalite and beta crystal (β-Quartz) on the surface of the sintered body and it is only vitreous, even if it is used for a long time at a high temperature of 973K or more, it becomes cloudy. Thus, a transparent sintered quartz glass free of cracks could be obtained.

【００１０】[0010]

【発明の実施の形態】鋳込み成形法による焼結石英ガラ
ス成形体からなるランプ形成体の製作について説明す
る。平均粒径１．５μｍのシリカ粉末と純水とバインダ
ーとを混合してスラリーを調合する。高輝度放電ランプ
の発光管の外形と相似形の石膏型に該スラリーを流し込
み、着肉させたのち、乾燥させる。発光管の外形と相似
形の一次成形体が完成する。容器の肉厚は着肉を制御す
ることによって可変できる。DESCRIPTION OF THE PREFERRED EMBODIMENTS The manufacture of a lamp formed body made of a sintered quartz glass formed body by a casting method will be described. A slurry is prepared by mixing silica powder having an average particle size of 1.5 μm, pure water and a binder. The slurry is poured into a gypsum mold having a shape similar to the outer shape of the arc tube of the high-intensity discharge lamp, and the slurry is dried. A primary molded body similar to the outer shape of the arc tube is completed. The thickness of the container can be varied by controlling the deposition.

【００１１】一次成形体を水素中で１２７３Ｋで約１時
間加熱し、仮焼結体とする。この段階では、シリカ粉末
がゆるく結合した状態であり、直線透過率は著しく低
い。この仮焼結体を、酸素分圧、焼結温度を変化させて
焼結石英ガラスを作製した。焼結時に生成されたシリカ
の種類を温度と酸素分圧の関係で表したのが図１であ
る。酸素分圧ＰO2＝２×１０4Ｐａの条件はａｉｒ（空
気）で、ＰO2＝１０Ｐａはｗａｔｅｒ ｖａｐｏｒ Ａ
ｒ（水蒸気を含有したＡｒ）雰囲気で、またＰO2＝１０
-4Ｐａはｄｒｉｅｄ Ａｒ（乾燥Ａｒ）雰囲気で、ＰO2
＝１０-8Ｐａはｄｒｉｅｄ ＆ ｄｅｏｘｉｄｉｚｅｄ
Ａｒ（乾燥Ａｒと還元して脱酸素化したＡｒ）雰囲気
で、ＰO2＝１０-10Ｐａは１０-2Ｐａの低真空で、ＰO2
＝１０-12Ｐａは１０-4Ｐａの高真空でそれぞれ実現し
た。[0011] The primary compact is heated in hydrogen at 1273 K for about 1 hour to obtain a temporary sintered body. At this stage, the silica powder is in a loosely bound state, and the linear transmittance is extremely low. By changing the oxygen partial pressure and the sintering temperature of this temporary sintered body, a sintered quartz glass was produced. FIG. 1 shows the type of silica generated during sintering in the relationship between temperature and oxygen partial pressure. The condition of the oxygen partial pressure P O2 = 2 × 10 4 Pa is air (air), and the water vapor A is P O2 = 10 Pa.
r (Ar including water vapor) atmosphere and P O2 = 10
-4 Pa is a dried Ar atmosphere, and P O2
= 10 -8 Pa is dried & deoxidized
In an Ar (Ar dried and reduced oxygen deoxidized) atmosphere, P O2 = 10 −10 Pa is a low vacuum of 10 −2 Pa, and P O2
= 10 −12 Pa was realized in a high vacuum of 10 −4 Pa, respectively.

【００１２】図１において、記号○は不透明な石英ガラ
スができ、記号□は石英ガラス表面にクリストバライト
やβ−水晶ができ、記号△は石英ガラス表面にモガナイ
トができたことを表している。このモガナイトはＳｉＯ
2シリカ多形の一種で１９８４年に発見された単斜晶系
の結晶構造を有する結晶であり、熱的に不安定で昇華し
易い性質を持つ物質であることが知られている。このよ
うに、図１のある領域に、このような昇華し易い性質の
モガナイトができることが分かった。そこで、この性質
を積極的に利用し、焼結条件をモガナイトができる酸素
分圧、温度とすることで、焼結石英ガラスの表面にクリ
ストバライト等の結晶を生成させずに石英ガラスを焼結
することができることが分かった。そして、できた焼結
石英ガラスの表面に微量残ったモガナイトが存在して
も、熱的に不安定な相であるために、焼結石英ガラス成
形体の熱加工時にモガナイトは昇華してなくなり、従来
の溶融石英ガラスと同等の透明性を有し、かつ白濁を生
じず、クラックも発生しない、焼結石英ガラス成形体か
らなる発光管が得られることが分かる。In FIG. 1, the symbol ○ indicates that opaque quartz glass was formed, the symbol □ indicates that cristobalite or β-quartz was formed on the quartz glass surface, and the symbol △ indicates that moganite was formed on the quartz glass surface. This moganite is SiO
It is a crystal having a monoclinic crystal structure discovered in 1984 as a type of 2- silica polymorph, and is known to be thermally unstable and easily sublimable. Thus, it was found that moganite having such a property of being easily sublimated was formed in a certain region in FIG. Therefore, utilizing this property positively, sintering quartz glass without generating crystals such as cristobalite on the surface of sintered quartz glass by setting the sintering conditions to the oxygen partial pressure and temperature at which moganite can be formed. I found that I could do it. And, even if there is a trace amount of moganite on the surface of the formed sintered quartz glass, because it is a thermally unstable phase, the moganite does not sublimate during thermal processing of the sintered quartz glass molded body, It can be seen that an arc tube made of a sintered quartz glass molded body having transparency equivalent to that of a conventional fused silica glass, not causing white turbidity, and generating no cracks can be obtained.

【００１３】そこで、上記の領域の酸素分圧（１０-4Ｐ
ａ）、温度（１６７３Ｋ）で焼結して得られた発光管を
使用して超高圧水銀ランプを製作した。発光管の寸法
は、内径：４．５ｍｍ、肉厚：３ｍｍ、内容積：１００
ｍｍ3 、封止管の直径：３ｍｍである。そして、発光管の
壁の温度が９７３Ｋ〜１１７３Ｋになるような条件で１
０００時間点灯したが，白濁は発生しなかった。Therefore, the partial pressure of oxygen in the above region (10 -4 P
a) An ultra-high pressure mercury lamp was manufactured using an arc tube obtained by sintering at a temperature (1673K). The dimensions of the arc tube are: inner diameter: 4.5 mm, wall thickness: 3 mm, internal volume: 100
mm 3 , diameter of the sealing tube: 3 mm. Then, under the condition that the temperature of the wall of the arc tube becomes 973K to 1173K, 1
Lighted for 000 hours, but no cloudiness occurred.

【００１４】[0014]

【発明の効果】本発明の方法によって、モガナイトが生
成される、焼結雰囲気の酸素分圧及び焼結温度を選定し
て、焼結した、またはモガナイトが生成される、酸素分
圧が１０-2Ｐａ以下の雰囲気中で、焼結温度１５３０Ｋ
以上で、焼結したので、従来、焼結体の表面に生じてい
たクリストバライト（Cristobalite），ベータ水晶（β
-Quartz）などの微結晶が生成されず、焼結石英ガラス
の表面にシリカ鉱物の多形の一つであるモガナイト（Mo
ganite）が形成される。そして、１５３０Ｋ以上の温度
では、モガナイト（Moganite）は、不安定で昇華しやす
いので，焼結体の表面から離脱してする。このようにし
て、石英ガラスは結晶の無い緻密な透明焼結石英ガラス
とすることができる。そして、焼結体の表面にクリスト
バライト（Cristobalite），ベータ水晶（β-Quartz）
などの微結晶が無いので、９７３Ｋ以上の高温度で長時
間使用しても、白濁の発生、クラックが生じない。By the method of the present invention, moganite is generated, by selecting the partial pressure of oxygen and the sintering temperature of the sintering atmosphere, and sintered, or moganite is generated, oxygen partial pressure is 10 - Sintering temperature 1530K in an atmosphere of 2 Pa or less
As described above, since sintering has been performed, cristobalite and beta crystal (β
-Quartz) and other microcrystals are not generated, and moganite (Mo), one of the polymorphs of silica mineral, is formed on the surface of sintered quartz glass.
ganite) is formed. At a temperature of 1530K or more, moganite is unstable and easily sublimates, and is separated from the surface of the sintered body. In this way, the quartz glass can be a dense transparent sintered quartz glass having no crystals. And, on the surface of the sintered body, cristobalite, beta crystal (β-Quartz)
Because of the absence of microcrystals, white turbidity and cracking do not occur even when used for a long time at a high temperature of 973K or more.

【図面の簡単な説明】[Brief description of the drawings]

【図１】 焼結時に生成されたシリカの種類を温度と酸
素分圧の関係で示す。FIG. 1 shows the type of silica produced during sintering in relation to temperature and oxygen partial pressure.

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 焼結過程においてモガナイトが生成され
るような、焼結雰囲気の酸素分圧及び焼結温度を選定し
て、焼結することを特徴とする焼結石英ガラス成形体の
焼結方法。1. Sintering of a sintered quartz glass compact characterized by selecting an oxygen partial pressure and a sintering temperature of a sintering atmosphere so as to generate moganite in a sintering process and sintering. Method. 【請求項２】 焼結方法において、酸素分圧が１０-2Ｐ
ａ以下の雰囲気中で、焼結温度が１５３０Ｋ以上で、焼
結することを特徴とする請求項１に記載の焼結石英ガラ
ス成形体の焼結方法。2. The sintering method, wherein the oxygen partial pressure is 10 −2 P
The sintering method according to claim 1, wherein the sintering is performed at a sintering temperature of 1530K or more in an atmosphere of a or less.
JP28045498A 1998-09-17 1998-09-17 Method for sintering sintered quartz glass molding Pending JP2000086251A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2263981A3 (en) * 2004-08-23 2013-09-04 Heraeus Quarzglas GmbH & Co. KG Method for producing a component of consisting of quartz glass

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2263981A3 (en) * 2004-08-23 2013-09-04 Heraeus Quarzglas GmbH & Co. KG Method for producing a component of consisting of quartz glass

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