Asahi Glass Company, Limited

Saint-Gobain Tm K.k.

Agc Ceramics Co., Ltd.

Agc Inc.

Nobuo Tomura

Hironori Sato

Shinya Hayashi

Yasuo Misu

Shigeo Endo

Yukihiro Ushimaru

Kenji Matano

To provide a high-zirconia electrocast refractory in which occurrence of cracks in manufacture and occurrence of cracks in use as a furnace material is further reduced while maintaining extremely high corrosion resistance to molten glass. The high-zirconia electrocast refractory contains 96.7 to 98.5 mass % of ZrO, 0.8 to 2.7 mass % of SiO, 0 to 0.2 mass % of NaO, 0.21 to 1 mass % of KO, 0.1 to 0.4 mass % of AlO, and does not substantially contain BO, in terms of oxide, as a chemical composition, wherein contents of the NaO and the KO satisfy a relation of following Formula (1)0.15 mass %&#x2264;C/2+C&#x2264;0.6 mass %&#x2003;&#x2003;(1)where Cis the content of KO and Cis the content of NaO, and each of the contents is expressed by mass % in the refractory.

High-zirconia electrocast refractory and method for manufacturing the same

To provide a high zirconia fused cast refractory having high durability, which hardly has cracks at the time of production of the refractory, during the heating, by temperature changes during use and during the cooling at the time of suspension of operation. A high zirconia fused cast refractory which has a chemical composition comprising from 88 to 96.5 mass % of ZrO, from 2.5 to 9.0 mass % of SiO, from 0.4 to 1.5 mass % of AlO, from 0.07 to 0.26 mass % of NaO, from 0.3 to 1.3 mass % of KO, from 0 to 0.3 mass % by outer percentage of LiO, at most 0.08 mass % by outer percentage of BO, and at most 0.08 mass % by outer percentage of PO, and contains BO+POin a content of at most 0.1 mass % by outer percentage.

High zirconia fused cast refractory

To provide a high zirconia fused cast refractory having high durability, which hardly has cracks during the heating, by temperature changes during use and during the cooling at the time of suspension of operation. A high zirconia fused cast refractory which has a chemical composition comprising from 86 to 96 mass % of ZrO, from 2.5 to 8.5 mass % of SiO, from 0.4 to 3 mass % of AlO, from 0.4 to 1.8 mass % of KO, at most 0.04 mass % of BO, at most 0.04 mass % of POand at most 3.8 mass % of CsO and containing substantially no NaO.

To provide a high zirconia fused cast refractory which hardly has cracks, and has excellent durability and reusability, at the time of production of the refractory and during use for a glass melting furnace. A high zirconia fused cast refractory which has a chemical composition comprising from 85 to 95 mass % of ZrO, at least 2.5 mass % of SiO, at most 0.04 mass % of NaO, at most 0.04 mass % of BO, and at most 0.04 mass % of PO, containing SrO as an essential component, and containing at least one of KO and CsO, wherein contents of SrO, KO and CsO satisfy the relations of the following formula (1) and (2) at the same time:0.20&#x2266;[0.638&#xd7;C+0.213&#xd7;C+0.580&#xd7;C]/C&#x2266;0.40&#x2003;&#x2003;(1)0.10&#x2266;0.580&#xd7;C/C&#x2003;&#x2003;(2)

A high-zirconia cast refractory material which contains 85-95 wt % of ZrO, 4-12 wt % of SiO, 0.1 to less than 0.8 wt % of AlO, less than 0.04 wt % of NaO, 0.01-0.15 wt % of KO, 0.1-1.5 wt % of BO, 0.01-0.2 wt % of CaO, less than 0.4 wt % of BaO, less than 0.2 wt % of SrO, 0.05-0.4 wt % of YO, and 0.3 wt % or less of FeOand TiOtogether, but does not substantially contain CuO and PO(less than 0.01 wt %), such that the molar ratio of the glass-forming oxides (such as SiOand BO) to the glass-modifying oxides (such as NaO, KO, CaO, MgO, SrO, and BaO) is 20-100, said refractory material having an electric resistance being 200 &#x3a9;&#xb7;cm or higher after standing for 12 hours at 1500&#xb0; C.

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Chiyoda-ku, Japan

Nobuo Tomura