Shin-etsu Quartz Products Co., Ltd.

Shin-estu Quartz Products Co., Ltd.

Tomomi Usui

Shigeru Yamagata

A silica container contains a substrate having a rotational symmetry, containing mainly a silica, and gaseous bubbles in a peripheral part of the substrate; a transparent silica glass in an inner peripheral part of the substrate; and an inner layer, formed on an inner surface of the substrate and containing a transparent silica glass; wherein the substrate contains Li, Na, and K in a total concentration of 50 or less ppm by weight; the substrate has a linear light transmittance of 91.8% to 93.2% at a light wavelength of 600 nm; the inner layer contains Li, Na, and K in a total concentration of 100 or less ppb by weight and at least one of Ca, Sr, and Ba in a total concentration of 50 to 2000 ppm by weight; and the inner layer has a linear light transmittance of 91.8% to 93.2% at a light wavelength of 600 nm.

Silica container and method for producing the same

A method for producing a silica container having a rotational symmetry includes forming a preliminarily molded article by feeding a powdered substrate's raw material to an inner wall of an outer frame having aspiration holes with rotating the frame, and forming a silica substrate. The preliminarily molded article is aspirated from an outer peripheral side with controlling a humidity inside the outer frame by ventilating gases present in the outer frame with charging from inside the preliminarily molded article a gas mixture comprised of an O2 gas and an inert gas and made below a prescribed dew-point temperature by dehumidification, and at the same time heated from inside the preliminarily molded article by a discharge-heat melting method with carbon electrodes, thereby making an outer peripheral part of the preliminarily molded article to a sintered body while an inner peripheral part to a fused glass body.

A method for producing a silica container includes forming a preliminarily molded substrate, wherein a first powdered raw material is fed to an inner wall of an outer frame having aspiration holes while rotating the outer frame; forming a preliminarily molded intermediate layer, wherein a second powdered raw material added with an aluminum compound or a crystal nucleating agent as an additive is fed to an inner wall of the preliminarily molded substrate; and forming an inner layer, wherein the preliminarily molded substrate and the preliminarily molded intermediate layer are degassed by aspiration from a peripheral side with heating from an inside forming a substrate and an intermediate layer, and a third powdered raw material having a high silica purity is spread from inside the substrate having the formed intermediate layer with heating from the inside forming an inner layer on an inner surface of the intermediate layer.

Producing a silica container includes forming a powder mixture by adding an Al compound or a crystal nucleating agent into a first powdered raw material; preliminarily molding to an intended shape by feeding the powder mixture to an inner wall of an outer frame while rotating the outer frame having aspiration holes; forming a silica substrate; and forming a transparent silica glass layer on an inner surface of the silica substrate, wherein the preliminarily molded article is degassed by aspiration from a peripheral side and heated from inside the preliminarily molded article at high temperature making a peripheral part of the preliminarily molded article to a sintered body while an inner part to a fused glass body, and a second powdered raw material having a higher silica purity than the first powdered raw material is spread from inside the silica substrate and heated from the inside at high temperature.

A method for producing a silica container having a rotational symmetry is provided. The method includes forming a preliminarily molded article by feeding a powdered substrate's raw material to an inner wall of an outer frame having aspiration holes with rotating the frame, and forming a silica substrate. The preliminarily molded article is aspirated from an outer peripheral side with controlling a humidity inside the outer frame by ventilating gases present in the outer frame with charging from inside the preliminarily molded article a gas mixture comprised of an O2 gas and an inert gas and made below a prescribed dew-point temperature by dehumidification, and at the same time heated from inside the preliminarily molded article by a discharge-heat melting method with carbon electrodes, thereby making an outer peripheral part of the preliminarily molded article to a sintered body while an inner peripheral part to a fused glass body.

A method for producing a silica container, the method including forming a preliminarily molded silica substrate to an intended shape by feeding a powdered substrate's raw material (silica particles) to an inner wall of a carbon-made outer frame having aspiration holes with rotating the outer frame, and forming the silica substrate wherein the preliminarily molded substrate is degassed by aspiration from its outer peripheral side with charging from an inner peripheral side of the preliminarily molded silica substrate a reducing gas containing more than 10% by volume of an Hgas, and at the same time heated from inside the preliminarily molded silica substrate by a discharge-heat melting method with carbon electrodes, thereby making an outer peripheral part of the preliminarily molded silica substrate to a sintered body while an inner peripheral part of the preliminarily molded silica substrate to a fused glass body.

A method is provided for producing a silica container arranged with a substrate, having a rotational symmetry, comprised of mainly a silica, and containing gaseous bubbles at least in its peripheral part, and an inner layer, formed on an inner surface of the substrate and comprised of a transparent silica glass; wherein a powdered silica, having particle diameter of 10 to 1000 &#x3bc;m, containing Ca, Sr, and Ba with the total concentration of 50 to 5000 ppm by weight, and releasing hydrogen molecules with the amount of 3&#xd7;10to 3&#xd7;10molecules/g upon heating at 1000&#xb0; C. under vacuum, is prepared at least as a powdered raw material for forming the inner layer, and then the inner layer is formed from the powdered silica as the powdered raw material for forming the inner layer.

Powdered silica, silica container, and method for producing them

A method for producing a silica container that includes forming a powder mixture by adding an Al compound or a crystal nucleating agent into a first powdered raw material (silica particles), preliminarily molding to an intended shape by feeding the powder mixture to an inner wall of an outer frame while rotating the outer frame having aspiration holes, forming a silica substrate, wherein the preliminarily molded article is degassed by aspiration from a peripheral side and at the same time heated from inside the preliminarily molded article at high temperature thereby making a peripheral part of the preliminarily molded article to a sintered body while an inner part to a fused glass body, and forming a transparent silica glass layer on an inner surface of the silica substrate, wherein a second powdered raw material having a higher silica purity than the first powdered raw material is spread from inside the silica substrate and at the same time heated from the inside at high temperature.

A method for producing a silica container comprising: forming a preliminarily molded substrate, wherein a first powdered raw material is fed to an inner wall of an outer frame having aspiration holes while rotating the outer frame; forming a preliminarily molded intermediate layer, wherein a second powdered raw material added with an aluminum compound or a crystal nucleating agent as an additive is fed to an inner wall of the preliminarily molded substrate; and forming an inner layer, wherein the preliminarily molded substrate and the preliminarily molded intermediate layer are degassed by aspiration from a peripheral side with heating from an inside thereby forming a substrate and an intermediate layer, and while a third powdered raw material having a high silica purity is spread from inside the substrate having the formed intermediate layer with heating from the inside thereby forming an inner layer on an inner surface of the intermediate layer.

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Tokyo, Japan

Tomomi Usui