JP6140687B2 - High zirconia electroformed refractory - Google Patents

High zirconia electroformed refractory Download PDF

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JP6140687B2
JP6140687B2 JP2014509197A JP2014509197A JP6140687B2 JP 6140687 B2 JP6140687 B2 JP 6140687B2 JP 2014509197 A JP2014509197 A JP 2014509197A JP 2014509197 A JP2014509197 A JP 2014509197A JP 6140687 B2 JP6140687 B2 JP 6140687B2
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戸村　信雄
信雄 戸村
之浩 牛丸
之浩 牛丸
晋也 林
晋也 林
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Description

本発明は、高ジルコニア質電鋳耐火物に係り、特に、ガラス溶融炉に適用した際にも、優れた耐久性及び再使用性を有し、かつ生産性にも優れた高ジルコニア質電鋳耐火物に関する。   The present invention relates to a high zirconia electrocast refractory, and in particular, when applied to a glass melting furnace, the high zirconia electroforming has excellent durability and reusability and excellent productivity. Regarding refractories.

化学成分としてＺｒＯ2 を８０質量％以上含む高ジルコニア質電鋳耐火物は、従来からガラス溶融炉用耐火物として使用されている。高ジルコニア質電鋳耐火物は、溶融ガラスに対する高い耐食性と低汚染性ゆえに、フラットパネルディスプレー用基板ガラスなどの高い品質が要求されるガラス溶融炉において、溶融ガラスとの接触部分に多用されている。High zirconia electrocast refractories containing 80% by mass or more of ZrO 2 as chemical components have been conventionally used as refractories for glass melting furnaces. High zirconia electrocast refractories are frequently used in contact with molten glass in glass melting furnaces that require high quality such as substrate glass for flat panel displays due to high corrosion resistance and low contamination to molten glass. .

高ジルコニア質電鋳耐火物の微細組織は、わずかな気孔、および多量のジルコニア（ＺｒＯ2 ）結晶粒とその粒間を充填する少量のマトリックスガラスから構成されている。このマトリックスガラスは、ＳｉＯ2 を主成分として、その他の酸化物、例えば、Ａｌ2 Ｏ3 、Ｎａ2 Ｏ、Ｂ2 Ｏ3 、Ｐ2 Ｏ5 、などの酸化物から構成される。The microstructure of the high zirconia electrocast refractory is composed of few pores and a large amount of zirconia (ZrO 2 ) crystal grains and a small amount of matrix glass filled between the grains. This matrix glass is composed of SiO 2 as a main component and other oxides such as Al 2 O 3 , Na 2 O, B 2 O 3 , and P 2 O 5 .

高ジルコニア質電鋳耐火物は、その製造時の冷却過程、ガラス溶融炉での熱上げ時、稼働休止する際の熱下げ時、および稼働中の運転操作や耐火物自身の侵食により、温度変化に曝される。これらの温度変化により、熱応力、および１０００℃付近の温度域において大きな体積変化を伴うジルコニア結晶の可逆的な変態で生じる変態応力が、当該耐火物内部に発生する。適切な熱機械特性と量を兼ね備えたマトリックスガラスが当該耐火物に含まれていれば、前述の応力に対して当該耐火物は柔軟となり応力が緩和されて、耐火物に亀裂は発生しない。なお、本明細書においては、以下、電鋳耐火物は単に耐火物ともいう。   High zirconia electrocast refractories change in temperature due to the cooling process during production, when heating up in a glass melting furnace, when cooling down during operation, and during operation and erosion of the refractory itself during operation. Exposed to. Due to these temperature changes, thermal stress and transformation stress generated by a reversible transformation of the zirconia crystal accompanied by a large volume change in a temperature range near 1000 ° C. are generated inside the refractory. If a matrix glass having appropriate thermomechanical properties and amount is contained in the refractory, the refractory becomes flexible with respect to the stress described above and the stress is relieved, and the refractory does not crack. In the following description, the electroformed refractory is also simply referred to as refractory.

一方で、マトリックスガラスの熱的機械的特性が不適切である場合やマトリックスガラス量が不足した場合、高ジルコニア質電鋳耐火物の製造時やガラス溶融炉に適用する際の熱上げ時に亀裂が生じる。当該耐火物を溶融ガラス接触部分へ適用する場合、亀裂があるとその部分は溶融ガラスにより激しい侵食を受けるため、当該耐火物の耐久性は大きく低下する。   On the other hand, if the thermal mechanical properties of the matrix glass are inadequate or the amount of matrix glass is insufficient, cracks will occur during the production of high zirconia electroformed refractories or when heating up when applied to a glass melting furnace. Arise. When the refractory is applied to the molten glass contact portion, if there is a crack, the portion is severely eroded by the molten glass, so the durability of the refractory is greatly reduced.

高ジルコニア質電鋳耐火物は、その内部にジルコン結晶（ＺｒＯ2 ・ＳｉＯ2 ）を生成する場合がある。当該耐火物内部でのジルコン結晶はＺｒＯ2 とマトリックスガラス中のＳｉＯ2 とが反応して生成するため、ジルコン結晶の生成は耐火物中のマトリックスガラスの減少をもたらす。ジルコン結晶が生成し、熱応力、変態応力を緩和するマトリックスガラス量が減少した当該耐火物は、脆化し、わずかな温度変動によっても亀裂が生じやすくなる。High zirconia electrocast refractories may produce zircon crystals (ZrO 2 · SiO 2 ) inside. Since the zircon crystal inside the refractory is formed by the reaction of ZrO 2 and SiO 2 in the matrix glass, the formation of the zircon crystal causes a decrease in the matrix glass in the refractory. The refractory in which zircon crystals are formed and the amount of matrix glass that reduces thermal stress and transformation stress is reduced becomes brittle, and cracks are easily generated even by slight temperature fluctuations.

さらに、耐火物単体ではジルコン結晶を生成し難い高ジルコニア質電鋳耐火物においても、溶融ガラスとの反応によりジルコン結晶を生成する場合がある。これは、当該耐火物中に含まれるジルコン結晶の生成を抑制する化学成分の溶融ガラス中への溶出、当該耐火物中へジルコン結晶の生成を促進する化学成分の溶融ガラスから侵入、のいずれか一方または双方が起こるためである。溶融ガラスとの反応によりジルコン結晶を生成する傾向は、液晶基板ガラスなどの低アルカリガラスまたは無アルカリガラスと当該耐火物が接触した場合に顕著に生じる。   Furthermore, even in a high zirconia electroformed refractory which is difficult to produce a zircon crystal with a refractory alone, a zircon crystal may be produced by reaction with molten glass. This is either the elution of chemical components that suppress the formation of zircon crystals contained in the refractory into the molten glass, or the penetration of chemical components that promote the formation of zircon crystals into the refractory from the molten glass. One or both occur. The tendency to produce zircon crystals by reaction with molten glass is prominent when the refractory is in contact with low alkali glass or non-alkali glass such as liquid crystal substrate glass.

したがって、耐火物単体で熱履歴によりジルコン結晶を生成しやすい高ジルコニア質電鋳耐火物、および耐火物単体ではジルコン結晶を生成し難くとも溶融ガラスとの反応によりジルコン結晶を生成しやすい高ジルコニア質電鋳耐火物を、ガラス溶融炉の耐火物として用いた場合、製造時に亀裂がなくかつ熱上げ時に亀裂が発生しなくても、稼働中に当該耐火物内部にジルコン結晶が生成して稼働中の温度変動により亀裂が生じやすくなり、当該耐火物の耐久性が大きく低下する場合がある。   Therefore, high zirconia electroformed refractories that easily produce zircon crystals due to thermal history in refractory alone, and high zirconia that easily produces zircon crystals by reaction with molten glass even if refractory alone cannot produce zircon crystals. When an electroformed refractory is used as a refractory for a glass melting furnace, a zircon crystal is generated inside the refractory during operation even if there is no crack at the time of production and no crack is generated during heating. Cracks are likely to occur due to temperature fluctuations, and the durability of the refractory may be greatly reduced.

一般に、耐火物の耐久性は、ガラス溶融炉の寿命を決定する要因である。そのため、耐火物の亀裂発生は、ガラス溶融炉の寿命を短くし、これがガラス製造原価を上昇させる１つの原因となる。   In general, the durability of a refractory is a factor that determines the life of a glass melting furnace. Therefore, the occurrence of cracks in the refractory shortens the life of the glass melting furnace, which is one cause of increasing the glass manufacturing cost.

また、ガラス溶融炉稼働中の状態においてジルコン結晶を生成していない高ジルコニア質電鋳耐火物は、亀裂が生じないか、生じたとしてもジルコン結晶を生成する耐火物よりも亀裂が僅少で済み、生産調整などによりガラス溶融炉の稼働を休止させる際の熱下げ時に新たな亀裂の発生や既存亀裂の伝播が少ないため、比較的再使用しやすい。   In addition, high zirconia electrocast refractories that do not produce zircon crystals while the glass melting furnace is in operation do not crack or, if they do, have fewer cracks than refractories that produce zircon crystals. Because the occurrence of new cracks and the propagation of existing cracks are low when the temperature is lowered when the operation of the glass melting furnace is suspended due to production adjustment, etc., it is relatively easy to reuse.

一方で、ジルコン結晶を生成した高ジルコニア質電鋳耐火物は、この熱下げ時における新たな亀裂の発生と既存亀裂の伝播が顕著であり、さらに再熱上げ時にも同様に亀裂の発生と伝播が生じるため再使用は困難である。仮に再使用しても、高い耐久性は得られずにガラス溶融炉は短命に終わる。すなわち、単体または溶融ガラスとの反応によりジルコン結晶を生成しやすい高ジルコニア質電鋳耐火物は、ガラス溶融炉稼働中の状態において寿命を残していても、稼働休止後の再使用には不適である。   On the other hand, high zirconia electroformed refractories that produced zircon crystals are prominent in the occurrence of new cracks and propagation of existing cracks during this temperature reduction, and also when cracks are reheated. Is difficult to reuse. Even if it is reused, high durability is not obtained and the glass melting furnace is short-lived. In other words, high zirconia electrocast refractories that easily generate zircon crystals by reaction with a single substance or molten glass are unsuitable for re-use after operation stoppage, even if they remain in service while the glass melting furnace is in operation. is there.

高ジルコニア質電鋳耐火物の、製造時、熱上げ時および稼働中における亀裂発生抑制手段は従来から検討されている。   Conventionally, means for suppressing the occurrence of cracks in high-zirconia electroformed refractories during production, heating and during operation have been studied.

特許文献１では、耐火物の化学組成を、ＺｒＯ2 が８５〜９７質量％、ＳｉＯ2 が２〜１０質量％、Ａｌ2 Ｏ3 が最大３質量％、Ｐ2 Ｏ5 が０．１〜３質量％、希土類酸化物を実質的に含有せず、製造時に生ずる亀裂が抑制された高ジルコニア質電鋳耐火物が提案されている。しかし、ジルコン結晶の生成を促進するＰ2 Ｏ5 が含有されており、耐火物単体でもジルコン結晶を生成しやすいという欠点がある。In Patent Document 1, the chemical composition of the refractory, ZrO 2 is 85 to 97 wt%, SiO 2 is 2 to 10 wt%, Al 2 O 3 up to 3 wt%, P 2 O 5 0.1 to 3 A high zirconia electroformed refractory material is proposed that is substantially free of mass%, rare earth oxides, and suppresses cracks that occur during production. However, since P 2 O 5 that promotes the formation of zircon crystals is contained, there is a drawback that a zircon crystal is easily generated even with a refractory alone.

特許文献２では、耐火物の化学組成を、ＺｒＯ2 が９０〜９８質量％、Ａｌ2 Ｏ3 が１質量％以下であり、Ｌｉ2 Ｏ、Ｎａ2 Ｏ、ＣｕＯ、ＣａＯ、ＭｇＯを含有せず、Ｂ2 Ｏ3 が０．５〜１．５質量％含有するか、または、Ｂ2 Ｏ3 が０．５〜１．５％であるとともにＫ2 Ｏ、ＳｒＯ、ＢａＯ、Ｒｂ2 Ｏ、Ｃｓ2 Ｏのうちから選ばれた１種が１．５％以下、または２種以上の合計が１．５％以下、として製造時の亀裂を抑制して、かつ陽イオン半径が大な成分を用いて電気抵抗も高い、高ジルコニア質電鋳耐火物が提案されている。しかし、ジルコン結晶の生成を促進するＢ2 Ｏ3 が高含有量であり、耐火物単体でもジルコン結晶を生成しやすいという欠点がある。In Patent Document 2, the chemical composition of the refractory is such that ZrO 2 is 90 to 98% by mass, Al 2 O 3 is 1% by mass or less, and Li 2 O, Na 2 O, CuO, CaO, and MgO are not contained. , B 2 O 3 is contained in an amount of 0.5 to 1.5% by mass, or B 2 O 3 is contained in an amount of 0.5 to 1.5% and K 2 O, SrO, BaO, Rb 2 O, Cs One component selected from 2 O is 1.5% or less, or the total of two or more species is 1.5% or less, and a component that suppresses cracking during production and has a large cation radius is used. High zirconia electroformed refractories with high electrical resistance have been proposed. However, there is a drawback in that the content of B 2 O 3 that promotes the formation of zircon crystals is high, and even a refractory alone can easily generate zircon crystals.

特許文献３では、耐火物の化学組成を、ＺｒＯ2 を９０〜９５質量％、ＳｉＯ2 を３．５〜７質量％、Ａｌ2 Ｏ3 を１．２〜３質量％、Ｎａ2 Ｏおよび／またはＫ2 Ｏを合量で０．１〜０．３５質量％含有し、Ｐ2 Ｏ5 、Ｂ2 Ｏ3 およびＣｕＯのいずれも実質的に含まないものとして、耐熱サイクル抵抗性の向上とジルコン結晶の生成を抑制した耐火物が提案されている。しかし、この発明に基づく耐火物といえども、溶融ガラス接触条件においてはジルコン結晶の生成抑制効果が不十分であった。また、耐火物製造時、特に鋳塊の質量が３００ｋｇ以上となるような大型の耐火物製造時に亀裂を生じやすいという問題があった。In Patent Document 3, the chemical composition of the refractory is as follows: ZrO 2 is 90 to 95% by mass, SiO 2 is 3.5 to 7% by mass, Al 2 O 3 is 1.2 to 3 % by mass, Na 2 O and / or Alternatively, it is assumed that the total amount of K 2 O is 0.1 to 0.35% by mass and substantially does not contain any of P 2 O 5 , B 2 O 3 and CuO. Refractories that suppress the formation of crystals have been proposed. However, even in the refractory based on the present invention, the effect of suppressing the formation of zircon crystals was insufficient under the molten glass contact conditions. In addition, there is a problem that cracks are likely to occur during the manufacture of refractories, particularly during the manufacture of large refractories that have an ingot mass of 300 kg or more.

特許文献４では、化学組成が、ＺｒＯ2 を８９〜９６質量％、ＳｉＯ2 を３．５〜７質量％、Ａｌ2 Ｏ3 を０．２〜１．５質量％、Ｎａ2 Ｏ＋Ｋ2 Ｏを０．０５〜１．０質量％、Ｂ2 Ｏ3 を１．２質量％未満、Ｐ2 Ｏ5 を０．５質量％未満、Ｂ2 Ｏ3 ＋Ｐ2 Ｏ5 を０．０１質量％を超え１．７質量％未満、ＣｕＯを０．３質量％未満、Ｆe2 Ｏ3 ＋ＴｉＯ2 を０．３質量％以下、ＢａＯを０．０１〜０．５質量％、ＳｎＯ2 を０．３質量％以下、である耐火物が提案されている。この特許文献によれば、耐火物製造時の割れおよび熱サイクルによる割れが発生しないとされ、さらにＮａ2 Ｏ、Ｋ2 Ｏ、ＢａＯを添加して、Ｐ2 Ｏ5 やＢ2 Ｏ3 が持っているジルコン結晶の生成を促進するという不都合な特性を消失させる、とされている。しかし、この発明をもってしてもやはり溶融ガラス接触条件においてはジルコン結晶の生成を抑制する効果が不十分であった。その理由としては、この発明の実施例は、ジルコン結晶の生成を促進する作用のあるＢ2 Ｏ3 およびＰ2 Ｏ5 を比較的高含有量に含んでいること、さらにＢ2 Ｏ3 およびＰ2 Ｏ5 を比較的高含有量に含んでいることに対して十分なＫ2 ＯおよびＡｌ2 Ｏ3の含有量となっていないことが挙げられる。In Patent Document 4, the chemical composition, the ZrO 2 89 to 96 wt%, a SiO 2 3.5 to 7 wt%, the Al 2 O 3 0.2 to 1.5 wt%, a Na 2 O + K 2 O 0.05-1.0% by mass, B 2 O 3 less than 1.2% by mass, P 2 O 5 less than 0.5% by mass, B 2 O 3 + P 2 O 5 more than 0.01% by mass Less than 1.7% by mass, CuO less than 0.3% by mass, Fe 2 O 3 + TiO 2 less than 0.3% by mass, BaO from 0.01 to 0.5% by mass, and SnO 2 to 0.3% by mass. The following refractories have been proposed. According to this patent document, cracks during the production of refractories and cracks due to thermal cycles do not occur, and Na 2 O, K 2 O, BaO are further added to have P 2 O 5 and B 2 O 3. The disadvantageous property of promoting the formation of the zircon crystals is lost. However, even with this invention, the effect of suppressing the formation of zircon crystals was insufficient under the molten glass contact conditions. The reason for this is that the embodiment of the present invention contains B 2 O 3 and P 2 O 5 having a relatively high content, which act to promote the formation of zircon crystals, and further B 2 O 3 and P It is mentioned that the content of K 2 O and Al 2 O 3 is not sufficient for containing 2 O 5 in a relatively high content.

特許文献５では、耐火物の化学組成を、ＺｒＯ2 を８７〜９４質量％、ＳｉＯ2 を３．０〜８．０質量％、Ａｌ2 Ｏ3 を１．２〜３．０質量％、Ｎａ2 Ｏを０．３５質量％を超え１．０質量％以下、Ｂ2 Ｏ3 を０．０２質量％を超えて０．０５質量％未満、Ｐ2 Ｏ5 、ＣｕＯは実質的に含ませず、かつＡｌ2 Ｏ3とＮａ2 Ｏの質量比を２．５から５．０、として耐火物単体でのジルコン結晶の生成を抑制する、という効果を得ている。しかし、この発明に基づく耐火物は、Ｎａ2 ＯとＡｌ2 Ｏ3 の含有量比を最適化してジルコン結晶の生成を抑制しているために、Ｎａ2 Ｏを低含有量でしか含んでいない溶融ガラスとの接触条件においてはＮａ2 Ｏの優先的な溶出が生じてしまう。この溶出によりＮａ2 ＯとＡｌ2 Ｏ3 の比率は、早々に未使用状態の初期値からずれ、耐火物の組成は、ジルコン結晶の生成を抑制するのに有利な組成から短期間のうちに外れ、耐火物単体で得られるジルコン結晶の生成を抑制する効果が早期に消失してしまうという欠点がある。In Patent Document 5, the chemical composition of the refractory is as follows: ZrO 2 is 87 to 94 mass%, SiO 2 is 3.0 to 8.0 mass%, Al 2 O 3 is 1.2 to 3.0 mass%, Na 2 O exceeds 0.35% by mass and 1.0% by mass or less, B 2 O 3 exceeds 0.02% by mass and less than 0.05% by mass, and substantially does not contain P 2 O 5 or CuO. And the mass ratio of Al 2 O 3 and Na 2 O is 2.5 to 5.0, and the effect of suppressing the formation of zircon crystals in the refractory alone is obtained. However, since the refractory based on this invention optimizes the content ratio of Na 2 O and Al 2 O 3 to suppress the formation of zircon crystals, it contains only a low content of Na 2 O. Preferential elution of Na 2 O occurs under the contact condition with molten glass. As a result of this elution, the ratio of Na 2 O to Al 2 O 3 quickly deviates from the initial value of the unused state, and the composition of the refractory is a composition that is advantageous for suppressing the formation of zircon crystals within a short period of time. This has the disadvantage that the effect of suppressing the formation of zircon crystals obtained with a single refractory disappears early.

特開昭５６−１２９６７５号公報JP-A-56-129675 特開昭６３−２８５１７３号公報Japanese Unexamined Patent Publication No. 63-285173 特開平６−７２７６６号公報Japanese Patent Laid-Open No. 6-72766 特開平９−２８７０号公報Japanese Patent Laid-Open No. 9-2870 特開２００７−１７６７３６号公報JP 2007-176736 A

本発明は、上記した問題を解決すべく、耐火物製造時、熱上げ時、使用中の温度変化や稼働休止時の熱下げのいずれにおいても亀裂を発生し難く、高い耐久性を有する高ジルコニア質電鋳耐火物の提供を目的とする。   In order to solve the above-mentioned problems, the present invention is highly resistant to high zirconia, which does not easily crack in any of refractory production, heating up, temperature change during use and temperature reduction during operation stop, and high durability. The purpose is to provide quality cast refractories.

本発明者らは、鋭意検討を重ねた結果、マトリックスガラス組成を調整し、特にＫ2 ＯとＡｌ2 Ｏ3 の含有量を適切な範囲とすることで、耐火物単体でも溶融ガラス接触条件下でもジルコン結晶を生成し難く、温度サイクル条件下でも残存体積膨張が小さく、さらに、耐火物製造時における亀裂の発生を効果的に抑制できる高ジルコニア質電鋳耐火物を見出した。As a result of intensive studies, the present inventors have adjusted the matrix glass composition, and in particular, by adjusting the content of K 2 O and Al 2 O 3 to an appropriate range, even a refractory alone can be used under molten glass contact conditions. However, the present inventors have found a high zirconia electroformed refractory material that is difficult to produce zircon crystals, has a small residual volume expansion even under temperature cycle conditions, and can effectively suppress the occurrence of cracks during refractory production.

すなわち、本発明の高ジルコニア質電鋳耐火物は、化学組成として、ＺｒＯ2 が８７〜９６質量％、ＳｉＯ2 が２．５〜９．０質量％、Ａｌ2 Ｏ3 が１．５質量％超、２．５質量％以下、Ｎａ2 Ｏが０．１５〜０．６質量％、Ｋ2 Ｏが０．３〜１．３質量％、Ｌｉ２Ｏが外掛けで０〜０．３質量％で、含有することを特徴とする。That is, the high zirconia electrocast refractory of the present invention has a chemical composition of 87 to 96% by mass of ZrO 2 , 2.5 to 9.0% by mass of SiO 2 , and 1.5% by mass of Al 2 O 3. ultra, 2.5 wt% or less, Na 2 O is 0.15 to 0.6 wt%, K 2 O is 0.3 to 1.3 wt%, 0 to 0.3 weight Li 2 O is in outer percentage It is characterized by containing in%.

本発明の高ジルコニア質電鋳耐火物によれば、耐火物製造時の亀裂の問題がなく生産性に優れ、かつ耐火物単体でも溶融ガラス接触下でもジルコン結晶を生成し難く、耐火物製造時、熱上げ時、使用時、および熱下げ時に亀裂が生じ難く、耐久性と再使用性に富んだ耐火物が得られる。   According to the high zirconia electrocast refractory of the present invention, there is no problem of cracking during the production of refractory, and the productivity is excellent, and it is difficult to produce zircon crystals even in the refractory alone or in contact with molten glass. Refractories with high durability and reusability can be obtained because cracks are unlikely to occur during heating, during use, and during heating.

また、本発明の高ジルコニア質電鋳耐火物は、溶融ガラス接触下でも亀裂が生じ難く耐久性に富むため、ガラス溶融炉の溶融ガラス接触部分に適用すると長い炉寿命が得られ、耐火物の侵食量を少なくして溶融ガラスの汚染を少なくできる。さらには、生産調整などによるガラス溶融炉の稼働停止時による熱下げ時、再熱上げ時にも亀裂を生じ難いため、侵食が少なく寿命を迎えていない耐火物の再使用が容易である。また、本発明の高ジルコニア質電鋳耐火物は、製造時の歩留まりを左右する亀裂の問題がないため、耐火物の生産性に優れるものであり、結果として製造原価面でも有利である。   In addition, the high zirconia electroformed refractory of the present invention is resistant to cracking even under molten glass contact, and has a high durability. By reducing the amount of erosion, contamination of the molten glass can be reduced. Furthermore, since it is difficult for cracks to occur when the glass melting furnace is shut down due to production adjustment or when it is reheated, it is easy to reuse refractories that have little erosion and have not reached the end of their lives. In addition, the high zirconia electrocast refractory of the present invention has no problem of cracking that affects the yield during production, and thus has excellent refractory productivity, and as a result, is advantageous in terms of production cost.

本発明の高ジルコニア質電鋳耐火物は、上記記載したＺｒＯ2 、ＳｉＯ2 、Ａｌ2 Ｏ3 、Ｎａ2 ＯおよびＫ2 Ｏの５つの化学成分を主要成分として構成される。これらの各化学成分が当該耐火物中で果たす役割について以下に説明する。なお、本明細書において、これら５成分の含有量は内掛け表示とする。そして、上記に記載されていない成分については５成分の合計を１００質量％とした場合の外掛け表示とする。The high zirconia electrocast refractory according to the present invention is composed mainly of the five chemical components ZrO 2 , SiO 2 , Al 2 O 3 , Na 2 O and K 2 O described above. The role each of these chemical components plays in the refractory will be described below. In the present specification, the contents of these five components are displayed in an inner line. And about the component which is not described above, it is set as the external display when the sum total of 5 components is 100 mass%.

本明細書において、内掛けとは、高ジルコニア質電鋳耐火物中の上記５成分の合量を１００質量％としたとき、１００質量％の中でのそれぞれの成分割合をいう。例えば、ＺｒＯ2 を内掛けで９０質量％含むとは、上記５成分の合量を１００質量％とし、１００質量％中、ＺｒＯ2 を９０質量％含むことを示す。In the present specification, the term “inner” refers to the ratio of each component in 100% by mass, when the total amount of the five components in the high zirconia electroformed refractory is 100% by mass. For example, including 90% by mass of ZrO 2 as an inner part indicates that the total amount of the five components is 100% by mass and that 90% by mass of ZrO 2 is included in 100% by mass.

一方、外掛けとは、高ジルコニア質電鋳耐火物中の上記５成分の合量を１００質量％としたとき、５成分以外の成分について上記１００質量％を基準にした割合をいう。例えば、Ｂ2 Ｏ3 を外掛けで０．０１質量％含むとは、上記５成分の合量を１００質量％とし、それ以外にＢ2 Ｏ3 を付加的に０．０１質量％含むことをいう。On the other hand, the overhang refers to a ratio based on 100% by mass of the components other than the 5 components when the total amount of the 5 components in the high zirconia electrocast refractory is 100% by mass. For example, including 0.01% by mass of B 2 O 3 on the outside means that the total amount of the five components is 100% by mass, and additionally 0.01% by mass of B 2 O 3 is included. Say.

高ジルコニア質電鋳耐火物の製造に用いられるジルコニア原料およびジルコン原料は、不可避的に１〜３質量％のＨｆＯ2 を含んでおり、ＨｆＯ2 は、製造時に蒸発などの損失はほとんどなく耐火物中に残存するため、本発明も含めた通常の高ジルコニア質電鋳耐火物は、１〜３質量％のＨｆＯ2 を含んでいる。ＨｆＯ2 は、高ジルコニア質電鋳耐火物一般においてＺｒＯ2 と同じ役割を果たすため、ＺｒＯ２ ＋ＨｆＯ２の値をもって単にＺｒＯ2 と表記するのが通例であり、本発明においてもＺｒＯ2 ＋ＨｆＯ2 の値をもってＺｒＯ2 と表記する。The zirconia raw material and the zircon raw material used for the production of the high zirconia electrocast refractory inevitably contain 1 to 3% by mass of HfO 2 , and HfO 2 has almost no loss such as evaporation during production. Therefore, the normal high zirconia electrocast refractory including the present invention contains 1 to 3% by mass of HfO 2 . HfO 2, since the same function as the ZrO 2 in the high-zirconia electrocast refractories generally have a value of ZrO 2 + HfO 2 are merely customary to denoted as ZrO 2, in the present invention ZrO 2 + of HfO 2 The value is expressed as ZrO 2 .

本発明の高ジルコニア質電鋳耐火物は、多量のジルコニア結晶と少量のマトリックスガラス、およびわずかの気孔により構成される高ジルコニア質電鋳耐火物である。内掛け成分であるＺｒＯ2 は、溶融ガラスの侵食に対する抵抗力が強く、耐火物の主要成分として含有される。このＺｒＯ2 のほとんどは溶融ガラスに対して優れた耐食性を有するジルコニア結晶として存在し、ごくわずかだけがマトリックスガラス中に存在する。The high zirconia electrocast refractory of the present invention is a high zirconia electrocast refractory composed of a large amount of zirconia crystals, a small amount of matrix glass, and a few pores. ZrO 2 , which is an inner coating component, has a strong resistance to erosion of molten glass and is contained as a main component of the refractory. Most of this ZrO 2 exists as zirconia crystals having excellent corrosion resistance against molten glass, and only a very small amount is present in the matrix glass.

すなわち、ＺｒＯ2 含有量は、本発明の高ジルコニア質電鋳耐火物中のジルコニア結晶含有率を支配し、ひいては耐火物の溶融ガラスに対する耐食性を左右する。溶融ガラスに対して高い耐食性を得るためにＺｒＯ2 は、８７質量％以上である必要があり、好ましくは８８質量％以上である。一方、ＺｒＯ2 が９６質量％より多くなると、応力緩和の働きをするマトリックスガラスの量が相対的に少なくなり、製造時や熱上げ時、使用時、熱下げ時の温度変化で亀裂が生じやすくなる。したがって、本発明の高ジルコニア質電鋳耐火物におけるＺｒＯ2 は、８７〜９６質量％である。That is, the ZrO 2 content dominates the zirconia crystal content in the high zirconia electroformed refractory of the present invention, and thus affects the corrosion resistance of the refractory to the molten glass. In order to obtain high corrosion resistance to the molten glass, ZrO 2 needs to be 87% by mass or more, and preferably 88% by mass or more. On the other hand, when the amount of ZrO 2 exceeds 96% by mass, the amount of matrix glass that acts to relieve stress is relatively small, and cracks are likely to occur due to temperature changes during production, heating, use, and cooling. Become. Therefore, ZrO 2 in the high zirconia electrocast refractory of the present invention is 87 to 96% by mass.

内掛け成分であるＳｉＯ2 は、マトリックスガラスを形成する主成分である。応力緩和の働きをするマトリックスガラスの量を確保するためには、２．５質量％以上のＳｉＯ2 が必要である。一方で、多量のＳｉＯ2 を耐火物に含ませると、必然としてＺｒＯ2 を多く含ませられなくなり耐食性を損なう。したがって、本発明の高ジルコニア質電鋳耐火物におけるＳｉＯ2 は、２．５〜９．０質量％であり、好ましくは３．０〜８．５質量％である。SiO 2 that is an inner coating component is a main component that forms matrix glass. In order to ensure the amount of matrix glass that acts to relieve stress, 2.5 mass% or more of SiO 2 is required. On the other hand, when a large amount of SiO 2 is contained in the refractory, a large amount of ZrO 2 is inevitably contained and the corrosion resistance is impaired. Thus, SiO 2 in the high-zirconia electrocast refractories of the present invention is 2.5 to 9.0 wt%, preferably from 3.0 to 8.5 wt%.

内掛け成分であるＡｌ2 Ｏ3 は、マトリックスガラスの粘度を低下させる成分であると同時にジルコン結晶の生成をある程度抑制する成分である。ジルコン結晶の生成が顕著となる低アルカリガラス、無アルカリガラス接触条件下においても、これらのガラスの多くはＡｌ2 Ｏ3 が比較的高含有量であり、耐火物と溶融ガラスの間に生じる濃度勾配差は小さく、耐火物からのＡｌ2 Ｏ3 の溶出は遅い。そのため長期間にわたりＡｌ2 Ｏ3 によるジルコン結晶の生成抑制効果を享受できる。さらに、適切な含有量でＡｌ2 Ｏ3 を含んでいると、耐火物製造時の溶解性が良好となり、耐火物製造時の溶解に必要な時間および電力を削減する効果が得られる。また、鋳造時の湯流れが良くなり、鋳型の隅々にまで溶湯がまわり込むため、鋳型の角部に溶湯が到達しないことによる欠陥の発生が抑えられる。さらに、湯流れが良いことにより、例えば厚み１００ｍｍ以下であるような比較的薄型の鋳型を用いる際の耐火物の生産が容易となる。すなわち、適切な含有量でＡｌ2 Ｏ3 を含んでいると鋳造耐火物の生産性を向上できる。Al 2 O 3, which is an inner coating component, is a component that lowers the viscosity of the matrix glass and at the same time suppresses the formation of zircon crystals to some extent. Even under low alkali glass and non-alkali glass contact conditions where the formation of zircon crystals becomes significant, many of these glasses have a relatively high content of Al 2 O 3 , and the concentration generated between the refractory and the molten glass The gradient difference is small and the dissolution of Al 2 O 3 from the refractory is slow. Therefore, the effect of suppressing the formation of zircon crystals by Al 2 O 3 can be enjoyed over a long period of time. Furthermore, when Al 2 O 3 is contained at an appropriate content, the solubility during refractory production becomes good, and the effect of reducing the time and power required for dissolution during refractory production is obtained. In addition, since the molten metal flow at the time of casting is improved and the molten metal flows into every corner of the mold, the occurrence of defects due to the molten metal not reaching the corners of the mold is suppressed. Furthermore, the good hot water flow facilitates the production of refractories when using a relatively thin mold having a thickness of, for example, 100 mm or less. That is, when Al 2 O 3 is contained at an appropriate content, the productivity of the cast refractory can be improved.

Ａｌ2 Ｏ3 が１．６質量％未満、特に１．５質量％以下であると、耐火物製造時の溶解性が良好とならず、耐火物製造時の溶解に必要な時間および電力を削減する効果が得られない。さらに、鋳造時の湯流れが不十分となり、比較的薄型の鋳型を用いる際の耐火物の生産時に鋳型の角部に溶湯が到達しないことによる欠陥の発生が増加する。Ａｌ2 Ｏ3 が２．５質量％を超えると製造時や使用中の時点でムライトなどアルミノシリケート系結晶を生成してしまい、マトリックスガラス量の低下をもたらして、製造時や熱上げ時、使用時、熱下げ時の温度変化で亀裂が生じやすくなる。したがって、本発明の高ジルコニア質電鋳耐火物におけるＡｌ2 Ｏ3 は、１．５質量％超、２．５質量％以下、好ましくは１．６〜２．５質量％であり、好ましくは１．８〜２．３質量％である。 Al 2 O 3 is less than 1.6 wt%, in particular is 1.5 wt% or less, not soluble at resistant fire was produced good, the time and power required for dissolution at the time of refractory manufacturing The effect of reduction cannot be obtained. Furthermore, the molten metal flow at the time of casting becomes insufficient, and the occurrence of defects due to the molten metal not reaching the corners of the mold during production of refractories when using a relatively thin mold is increased. When Al 2 O 3 exceeds 2.5% by mass, aluminosilicate crystals such as mullite are produced at the time of production or in use, resulting in a decrease in the amount of matrix glass, which is used during production or heating. Sometimes, cracks are likely to occur due to temperature changes when the temperature is lowered. Therefore, Al 2 O 3 in the high zirconia electroformed refractory of the present invention is more than 1.5 mass% and not more than 2.5 mass%, preferably 1.6 to 2.5 mass%, preferably 1 .8 to 2.3 mass%.

内掛け成分であるＮａ2 Ｏは、電鋳耐火物の製造時における亀裂の発生を効果的に抑制する成分である。また、Ｎａ2 Ｏは、耐火物単体での熱履歴においてジルコン結晶の生成の抑制効果を有する成分である。ただし、Ｎａ2 Ｏは、ジルコン結晶の生成を抑制する効果はＫ2 ＯやＣｓ2 Ｏに及ばない。また、Ｎａ2 Ｏは、Ａｌ2 Ｏ3 やＫ2 Ｏと同様にマトリックスガラスの粘度を低下させる成分でもあるが、その粘度低下効果は特に著しく、溶融ガラス接触条件においてジルコン結晶の生成抑制に有効な成分であるＡｌ2 Ｏ3 やＫ2 Ｏ、およびＣｓ2 Ｏの溶融ガラスへの溶出を速め、かつＢ2 Ｏ3 などジルコン結晶の生成促進する成分の溶融ガラスからの侵入を速めるおそれがあるため、多量に含有させることはできない。Na 2 O, which is an inner coating component, is a component that effectively suppresses the occurrence of cracks during the production of electrocast refractories. Na 2 O is a component having an effect of suppressing the formation of zircon crystals in the thermal history of the refractory alone. However, Na 2 O does not have the effect of suppressing the formation of zircon crystals as much as K 2 O or Cs 2 O. Na 2 O, as well as Al 2 O 3 and K 2 O, is a component that lowers the viscosity of the matrix glass, but its viscosity-reducing effect is particularly remarkable and effective in suppressing the formation of zircon crystals under molten glass contact conditions. as Al 2 O 3 and K 2 O is a component, and accelerate the dissolution of Cs 2 O to the molten glass, and there is a possibility to increase the penetration of the molten glass components produced promotion of B 2 O 3, etc. zircon Therefore, it cannot be contained in a large amount.

以上より、Ｎａ2 Ｏは、低含有量が好ましく、本発明の高ジルコニア質電鋳耐火物におけるＮａ2 Ｏの含有量は、０．１５〜０．６質量％であり、好ましくは０．１７〜０．５８質量％であり、さらに好ましくは０．２０〜０．５５質量％である。From the above, Na 2 O, the low content of preferably Na 2 O content of the high-zirconia electrocast refractories of the present invention is 0.15 to 0.6 wt%, preferably 0.17 It is -0.58 mass%, More preferably, it is 0.20-0.55 mass%.

内掛け成分であるＫ2 Ｏもまたマトリックスガラスの粘度を低下させる成分であると同時にジルコン結晶の生成を抑制する成分である。Ａｌ2 Ｏ3、Ｎａ2 Ｏと同様にＫ2 Ｏは、マトリックスガラスの粘度を低下させる役割があり、Ｋ2 Ｏを耐火物に含ませると、製造時や熱上げ時、使用時、熱下げ時の温度変化による耐火物の亀裂を抑制する作用が得られる。また、Ｋの陽イオン半径は大きいために溶融ガラスと接触しても溶出が遅く、長期にわたりジルコン結晶の生成抑制効果を与える。K 2 O, which is an inner coating component, is also a component that reduces the viscosity of the matrix glass and at the same time suppresses the formation of zircon crystals. Like Al 2 O 3 and Na 2 O, K 2 O has the role of lowering the viscosity of the matrix glass. If K 2 O is included in the refractory, the temperature is lowered during production, during heating, during use, or during use. The action which suppresses the crack of the refractory by the temperature change at the time is acquired. In addition, since the cation radius of K is large, elution is slow even when it comes into contact with molten glass, and the effect of suppressing the formation of zircon crystals is given over a long period of time.

Ｋ2 Ｏが不足すると製造時や使用による加熱でムライトなどアルミノシリケート系結晶を生成してしまい、マトリックスガラス量の低下をもたらして、製造時や熱上げ時、使用時、熱下げ時の温度変化で亀裂が生じやすくなる。一方で、Ｋ2 Ｏが１．３質量％以上、特には１．３質量％を超えて存在すると、製造時あるいは使用による加熱でリューサイトなどカリウム含有のアルミノシリケート系結晶を生成してしまい、マトリックスガラス量の低下をもたらして、製造時や熱上げ時、使用時、熱下げ時の温度変化で亀裂を生じやすくなる。わずかなＫ2 Ｏだけでも耐火物単体におけるジルコン結晶の生成を抑制する効果を得られるが、溶融ガラス接触条件、特に低アルカリガラスや無アルカリガラスに接触する条件下でもジルコン結晶の生成を抑制するためには、０．３質量％以上のＫ2 Ｏが必要である。したがって、本発明の高ジルコニア質電鋳耐火物におけるＫ2 Ｏは０．３〜１．３質量％であり、好ましくは０．４〜１．２質量％であり、さらに好ましくは０．５〜１．１質量％である。Insufficient K 2 O produces aluminosilicate crystals such as mullite during manufacturing and use, resulting in a decrease in the amount of matrix glass, and temperature changes during manufacturing, heating, use, and temperature reduction Cracks are likely to occur. On the other hand, if K 2 O is present in an amount of 1.3% by mass or more, particularly exceeding 1.3% by mass, potassium-containing aluminosilicate crystals such as leucite are produced during production or heating by use, This results in a decrease in the amount of matrix glass, and cracks are likely to occur due to temperature changes during manufacturing, heating, use, and heating. Even a small amount of K 2 O can suppress the formation of zircon crystals in a refractory alone, but it also suppresses the formation of zircon crystals even under molten glass contact conditions, particularly under conditions of contact with low alkali glass or non-alkali glass. For this purpose, 0.3% by mass or more of K 2 O is necessary. Therefore, K 2 O in the high zirconia electroformed refractory of the present invention is 0.3 to 1.3% by mass, preferably 0.4 to 1.2% by mass, and more preferably 0.5 to 1.1% by mass.

ここで、耐火物中におけるＮａ2 ＯとＫ2 Ｏの含有量については、Ｎａ2 Ｏに対するＫ2 Ｏの比（Ｋ2 Ｏ／Ｎａ2 Ｏ）を所定の関係に調製することが好ましい。具体的には、Ｋ2 Ｏ／Ｎａ2 Ｏの数値が、好ましくは０．５〜８であり、より好ましくは０．８〜７であり、さらに好ましくは１．１〜６である。Here, the content of Na 2 O and K 2 O in the refractories, it is preferable to prepare the ratio of K 2 O with respect to Na 2 O of (K 2 O / Na 2 O ) in a predetermined relationship. Specifically, the numerical value of K 2 O / Na 2 O is preferably 0.5 to 8, more preferably 0.8 to 7, and further preferably 1.1 to 6.

Ｎａ2 Ｏが多すぎると、熱上げ時、使用時および熱下げ時のように溶融ガラスと接触している際におけるジルコン結晶の生成を抑制する効果が十分得られないおそれがある。一方、Ｋ2 Ｏは、上記のような溶融ガラスとの接触条件でも、安定してジルコン結晶の生成を抑制できる。しかしながら、本発明者らは、Ｋ2 ＯとＡｌ2 Ｏ3 を多く含み、Ｎａ2 Ｏが含まれないような条件では、電鋳耐火物の製造時において亀裂が生じ易くなることを新たに知見した。そこで、本発明においては、耐火物の製造時においても、溶融炉の熱上げ時、使用時および熱下げ時においても、いずれの場合でも亀裂の発生を抑制する効果を、必要十分に、かつ、バランス良く得られる耐火物とできることを新たに見出したものである。When there is too much Na 2 O, there is a possibility that the effect of suppressing the formation of zircon crystals at the time of contact with the molten glass at the time of heating up, at the time of use and at the time of heating down may not be obtained sufficiently. On the other hand, K 2 O can stably suppress the formation of zircon crystals even under the contact conditions with the molten glass as described above. However, the present inventors have newly found that cracks are likely to occur during the production of electroformed refractories under conditions that contain a large amount of K 2 O and Al 2 O 3 and no Na 2 O. did. Therefore, in the present invention, it is necessary and sufficient to suppress the occurrence of cracks in any case, both in the production of refractories, in the heating up of the melting furnace, in use and at the time of heat reduction, and It has been newly found that it can be made with a refractory that can be obtained in a well-balanced manner.

さらに、これらＮａ2 ＯおよびＫ2 Ｏの合量（Ｎａ2 Ｏ＋Ｋ2 Ｏ）は、好ましくは０．５〜１．６質量％であり、より好ましくは０．５５〜１．４質量％であり、さらに好ましくは０．６〜１．２質量％である。Ｎａ2 ＯおよびＫ2 Ｏの合量（Ｎａ2 Ｏ＋Ｋ2 Ｏ）が不足すると、耐火物の製造時に亀裂が生じやすく、かつ、耐火物単体でのジルコン結晶の生成が抑制されにくく、さらに、耐火物製造時の溶解性が良好とならず、耐火物製造時の溶解に必要な時間および電力を削減する効果が得られない。さらに、鋳造時の湯流れが不十分となり、比較的薄型の鋳型を用いる際の耐火物の生産時に鋳型の角部に溶湯が到達しないことによる欠陥の発生が増加する。一方で、Ｎａ2 ＯおよびＫ2 Ｏの合量（Ｎａ2 Ｏ＋Ｋ2 Ｏ）が過剰になると、耐火物の製造時に亀裂が生じやすい。Furthermore, the total amount of Na 2 O and K 2 O (Na 2 O + K 2 O) is preferably 0.5 to 1.6% by mass, more preferably 0.55 to 1.4% by mass. More preferably, it is 0.6 to 1.2% by mass. If the total amount of Na 2 O and K 2 O (Na 2 O + K 2 O) is insufficient, cracks are likely to occur during the production of the refractory, and the formation of zircon crystals in the refractory alone is difficult to suppress. The solubility at the time of manufacturing the product is not good, and the effect of reducing the time and power required for the melting at the time of manufacturing the refractory cannot be obtained. Furthermore, the molten metal flow at the time of casting becomes insufficient, and the occurrence of defects due to the molten metal not reaching the corners of the mold during production of refractories when using a relatively thin mold is increased. On the other hand, if the total amount of Na 2 O and K 2 O (Na 2 O + K 2 O) is excessive, cracks are likely to occur during the production of the refractory.

さらに、Ｌｉ２Ｏを外掛けで０〜０．３質量％含有することができる。Ｌｉ２Ｏは、ジルコン結晶の生成の抑制に関与しないものの、他の原料の溶融を促進する作用があるため、耐火物を製造する際の生産性が向上する。一方、Ｌｉ２Ｏの含有量が０．３質量％を超えると、耐火物製造時に耐火物に亀裂が発生するおそれがある。Ｌｉ２Ｏの含有量は、０．１５質量％以下が好ましく、０．１質量％以下がより好ましく、不可避的不純物を除き実質的に含有しないことがさらに好ましい。Ｌｉ２Ｏを含有させる場合には、０．０３質量％以上が好ましく、０．０５質量％以上がより好ましい。Furthermore, 0 to 0.3% by mass of Li 2 O can be contained as an outer shell. Although Li 2 O is not involved in the suppression of the formation of zircon crystals, it has the effect of promoting the melting of other raw materials, so the productivity when manufacturing a refractory is improved. On the other hand, if the content of Li 2 O exceeds 0.3% by mass, the refractory may be cracked during refractory production. The content of Li 2 O is preferably 0.15% by mass or less, more preferably 0.1% by mass or less, and still more preferably substantially free of unavoidable impurities. When Li 2 O is contained, 0.03% by mass or more is preferable, and 0.05% by mass or more is more preferable.

外掛け成分であるＢ2 Ｏ3 は、ジルコン結晶の生成を促進する成分である。Ｂ2 Ｏ3 が多量に含まれると、耐火物は熱履歴のみでジルコン結晶を生成し、少量であっても溶融ガラス接触条件でのジルコン結晶の生成を促進する場合がある。そのため、ジルコン結晶の生成の抑制という点でＢ2 Ｏ3 は低含有量が好ましい。Ａｌ2 Ｏ3 、Ｎａ2 Ｏ、Ｋ2 ＯおよびＣｓ2 Ｏがジルコン結晶の生成抑制に大きく貢献している本発明において、Ｂ2 Ｏ3 は外掛けで０．２５質量％まで許容され、好ましくは０．１５質量％以下である。Ｂ2 Ｏ3 が０．０８質量％以下であるとより好ましい。B 2 O 3, which is an outer coating component, is a component that promotes the formation of zircon crystals. When a large amount of B 2 O 3 is contained, the refractory produces a zircon crystal only with a thermal history, and even a small amount may promote the formation of the zircon crystal under molten glass contact conditions. Therefore, a low content of B 2 O 3 is preferable in terms of suppressing the formation of zircon crystals. In the present invention in which Al 2 O 3 , Na 2 O, K 2 O and Cs 2 O contribute greatly to the suppression of the formation of zircon crystals, B 2 O 3 is allowed up to 0.25% by mass, preferably Is 0.15 mass% or less. B 2 O 3 is more preferably 0.08% by mass or less.

一方で、Ｂ2 Ｏ3 は、低含有量でも耐火物製造時の亀裂発生を抑制する効果があるため、ジルコン結晶の生成抑制に不都合のない範囲内でＢ2 Ｏ3 を耐火物に含ませ、精緻な組成制御を実施して耐火物の生産性を高く保持できる。On the other hand, B 2 O 3 has the effect of suppressing cracking during refractory production even at a low content, so B 2 O 3 is included in the refractory within a range that is not inconvenient for suppressing the formation of zircon crystals. In addition, precise composition control can be performed to maintain high refractory productivity.

外掛け成分であるＰ2 Ｏ5 は、Ｂ2 Ｏ3 と同様にジルコン結晶の生成を促進する成分である。Ｐ2 Ｏ5 が多量に含まれると耐火物は熱履歴のみでジルコン結晶を生成し、少量であっても溶融ガラス接触条件でのジルコン結晶の生成を促進する場合がある。そのため、ジルコン結晶の生成の抑制という点でＰ2 Ｏ5 は可及的低含有量が好ましい。P 2 O 5, which is an outer coating component, is a component that promotes the formation of zircon crystals in the same manner as B 2 O 3 . When a large amount of P 2 O 5 is contained, the refractory produces a zircon crystal only with a thermal history, and even a small amount may promote the formation of a zircon crystal under molten glass contact conditions. Therefore, P 2 O 5 is preferably as low as possible in terms of suppressing the formation of zircon crystals.

一方で、Ｐ2 Ｏ5 は、低含有量でも耐火物製造時の亀裂発生を抑制する効果があり、さらに、ジルコニア原料やジルコン原料の種類によっては不可避的に混入してくる成分でもある。Ｐ2 Ｏ5 の含有を一切許容できないとなると、高価な精製原料や産地が限定された比較的高価なジルコン原料、ジルコニア原料を使用せねばならなくなる。しかし、Ａｌ2 Ｏ3 、Ｎａ2 Ｏ、Ｋ2 Ｏ、およびＣｓ2 Ｏがジルコン結晶の生成の抑制に大きく貢献している本発明において、Ｐ2 Ｏ5 は外掛けで０．２５質量％まで許容され、好ましくは０．１５質量％以下である。Ｐ2 Ｏ5 が０．０８質量％以下であるとより好ましい。
そのため、ジルコン原料、ジルコニア原料の選定幅は狭まらず、比較的安価な原料コストを達成できる。さらに、Ｂ2 Ｏ3 の場合と同様に、ジルコン結晶の生成抑制に不都合のない範囲内でＰ2 Ｏ5 を耐火物に含ませ、精緻な組成制御を実施すれば耐火物の生産性を高く保てる。On the other hand, P 2 O 5 has an effect of suppressing cracking during refractory production even at a low content, and is also a component that is inevitably mixed depending on the type of zirconia raw material or zircon raw material. If the inclusion of P 2 O 5 is unacceptable at all, it is necessary to use an expensive refining raw material or a relatively expensive zircon raw material or zirconia raw material with a limited production area. However, in the present invention in which Al 2 O 3 , Na 2 O, K 2 O, and Cs 2 O greatly contribute to the suppression of the formation of zircon crystals, P 2 O 5 is up to 0.25% by mass as an outer shell. Acceptable, preferably 0.15% by weight or less. P 2 O 5 is more preferably 0.08% by mass or less.
Therefore, the selection range of the zircon raw material and the zirconia raw material is not narrowed, and a relatively inexpensive raw material cost can be achieved. Furthermore, as in the case of B 2 O 3 , if P 2 O 5 is included in the refractory within a range that does not cause inconvenience in suppressing the formation of zircon crystals, and precise composition control is performed, the productivity of the refractory increases. I can keep it.

なお、上記のとおり、Ｂ2 Ｏ3 とＰ2 Ｏ5 は、共にジルコン結晶の生成を促進する成分であり、これら成分に抗して、耐火物中のジルコン結晶の生成を抑制する作用を十分に確保するため、本発明においてＢ2 Ｏ3 とＰ2 Ｏ5 との合量は、外掛けで０．４質量％以下が好ましく、そして、より好ましくは、０．３質量％以下であり、特に好ましくは、０．１質量％以下である。ジルコン結晶の生成の抑制を考慮すると、０．０５質量％以下が好ましく、不可避的不純物を除き実質的に含有しないことがより好ましい。As described above, both B 2 O 3 and P 2 O 5 are components that promote the formation of zircon crystals and have a sufficient effect of suppressing the formation of zircon crystals in the refractory against these components. In the present invention, the total amount of B 2 O 3 and P 2 O 5 is preferably 0.4% by mass or less, more preferably 0.3% by mass or less, Especially preferably, it is 0.1 mass% or less. Considering the suppression of the formation of zircon crystals, 0.05% by mass or less is preferable, and it is more preferable not to contain substantially except for inevitable impurities.

また、本発明においては、上記説明した成分に加えて、外掛け成分であるＣｓ2 Ｏを含有させてもよい。Ｃｓ2 Ｏもジルコン結晶の生成を抑制する成分であり、低含有量においてもその効果は発現する。また、Ｃｓの陽イオン半径は、非常に大きいため溶融ガラスと接触しても耐火物からの溶出が極めて遅く、特に長期にわたりジルコン結晶の生成抑制効果を与える。一方で、理由は定かでないが、過剰のＣｓ2 Ｏは製造時の時点で亀裂を生じさせる傾向があるため、Ｃｓ2 Ｏの含有量は、外掛けで０．０５〜３．８質量％、さらには０．０５〜３．５質量％が好ましく、より好ましくは０．０５〜２．５質量％以下であり、特に好ましくは０．０５〜０．７質量％である。In the present invention, in addition to the above-described components, Cs 2 O which is an outer coating component may be included. Cs 2 O is also a component that suppresses the formation of zircon crystals, and the effect is exhibited even at a low content. Moreover, since the cation radius of Cs is very large, even if it contacts with molten glass, the elution from a refractory material is very slow, and the effect of suppressing the formation of zircon crystals is given particularly for a long period of time. On the other hand, although the reason is not clear, excess Cs 2 O tends to cause cracks at the time of production, so the content of Cs 2 O is 0.05 to 3.8% by mass as an outer coating, Furthermore, 0.05-3.5 mass% is preferable, More preferably, it is 0.05-2.5 mass% or less, Most preferably, it is 0.05-0.7 mass%.

主に、原料中に不純物として含まれるＦｅ2 Ｏ3 とＴｉＯ2 は、溶融ガラスへの着色と発泡を生じさせる成分であり、高含有量となるのは好ましくない。これらＦｅ2 Ｏ3 とＴｉＯ2 との合量は、外掛けで０．３質量％以下において着色の問題はなく、好ましくは０．２質量％を超えない量である。Mainly, Fe 2 O 3 and TiO 2 contained as impurities in the raw material are components that cause coloring and foaming of the molten glass, and it is not preferable to have a high content. The total amount of these Fe 2 O 3 and TiO 2 is an amount that does not exceed 0.2% by mass, and there is no problem of coloring when the outer coating is 0.3% by mass or less.

同様に、原料中には不純物としてＹ2 Ｏ3 とＣａＯが含まれるが、これらは熱サイクル試験での残存体積膨張率を増加させる傾向があり、これらＹ2 Ｏ3 とＣａＯとの合量は、外掛けで０．３質量％以下において問題はなく、好ましくは０．２質量％を超えない量である。Similarly, the raw materials contain Y 2 O 3 and CaO as impurities, but these tend to increase the residual volume expansion coefficient in the thermal cycle test, and the total amount of these Y 2 O 3 and CaO is When the outer coating is 0.3% by mass or less, there is no problem, and the amount is preferably not more than 0.2% by mass.

また、外掛け成分であるＢａＯは、マトリックスガラスの粘性を低下させる性質を持つアルカリ土類金属酸化物成分である。ＢａＯは、必須成分ではなく、低濃度での含有は耐火物の特性を悪化させないため、低濃度で耐火物に含有させることに問題はない。一方で、高濃度でＢａＯを耐火物に含有させるとマトリックスガラスの粘性を大幅に低下させるために、製造時に耐火物の亀裂の発生を助長する傾向がある。そのため、ＢａＯを含有させる場合には、外掛けで０〜１質量％とするのが好ましい。   BaO, which is an outer coating component, is an alkaline earth metal oxide component having a property of reducing the viscosity of the matrix glass. BaO is not an essential component, and its inclusion at a low concentration does not deteriorate the properties of the refractory. Therefore, there is no problem in including it in the refractory at a low concentration. On the other hand, when BaO is contained in the refractory at a high concentration, the viscosity of the matrix glass is greatly reduced, and thus there is a tendency to promote the occurrence of cracks in the refractory during production. Therefore, when it contains BaO, it is preferable to set it as 0-1 mass% with an outer shell.

以下に、本発明の高ジルコニア質耐火物を実施例によって具体的に説明するが、本発明はこれらの実施例によって何ら限定されるものではない。   Hereinafter, the high zirconia refractory of the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

電融鋳造法で耐火物を得るために、ジルコニア原料である脱珪ジルコンにアルミナ、ジルコンサンド、シリカ、炭酸カリウム、炭酸セシウム、Ｂ2 Ｏ3 、Ｐ2 Ｏ5 などの原料を調合して混合原料とし、この混合原料を３本の黒鉛電極を備えた出力１５００ｋＶＡの三相アーク電気炉に装入して、通電加熱により完全に溶融した。In order to obtain a refractory by the electrocasting method, raw materials such as alumina, zircon sand, silica, potassium carbonate, cesium carbonate, B 2 O 3 and P 2 O 5 are mixed and mixed with desiliconized zircon which is a zirconia raw material. This raw material was charged into a three-phase arc electric furnace with an output of 1500 kVA equipped with three graphite electrodes and completely melted by energization heating.

この溶湯を徐冷材であるケイ砂の中に予め埋めておいた黒鉛製の鋳型に５００〜６００ｋｇ流し込んで鋳造し、室温付近の温度になるまで放冷した。この黒鉛製の鋳型は、厚み２５０ｍｍ×幅３１０ｍｍ×高さ８２０ｍｍの引け巣を含まない耐火物製品の素材が得られるように製作した。具体的には、耐火物製品の素材用とする部分の上方に耐火物製品の素材用の部分と同体積の押し湯部分を設けた鋳塊となるように、鋳型は設計、製作された。   This molten metal was cast by casting 500 to 600 kg into a graphite mold previously buried in silica sand as a slow cooling material, and allowed to cool to a temperature near room temperature. This graphite mold was manufactured so as to obtain a material for a refractory product having a thickness of 250 mm, a width of 310 mm, and a height of 820 mm and containing no shrinkage nest. Specifically, the mold was designed and manufactured so as to be an ingot in which a hot metal portion having the same volume as the material portion of the refractory product was provided above the portion used for the material of the refractory product.

鋳造、放冷の後、鋳塊と黒鉛鋳型を徐冷材中から抜き出し、さらに黒鉛鋳型と鋳塊を分離し、高ジルコニア質電鋳耐火物を製造した。   After casting and allowing to cool, the ingot and the graphite mold were extracted from the gradually cooled material, and the graphite mold and the ingot were further separated to produce a high zirconia electroformed refractory.

原料組成を調整し、表１〜表５に示した化学組成を有する高ジルコニア質電鋳耐火物を得た。ここで、表１、表２、表４には実施例（例１〜例１５、例２３〜例２５）を、表３、表５には比較例（例１６〜例２２、例２６〜２８）を示した。なお、耐火物中の化学組成について、ＺｒＯ2 、ＳｉＯ2 、Ａｌ2 Ｏ3 は波長分散型蛍光Ｘ線分析法により決定した定量分析値であり、その他の成分は高周波誘導結合プラズマ発光分光分析法により決定した定量分析値である。しかし、各成分の定量はこの分析方法に限定されるものではなく、他の定量分析方法で行ってもよい。The raw material composition was adjusted to obtain high zirconia electroformed refractories having chemical compositions shown in Tables 1 to 5. Here, Tables 1, 2 and 4 show Examples (Examples 1 to 15 and Examples 23 to 25), and Tables 3 and 5 show Comparative Examples (Examples 16 to 22 and Examples 26 to 28). )showed that. In addition, regarding the chemical composition in the refractory, ZrO 2 , SiO 2 , and Al 2 O 3 are quantitative analysis values determined by wavelength dispersive X-ray fluorescence analysis, and other components are high frequency inductively coupled plasma emission spectroscopy. Quantitative analysis value determined by However, the quantification of each component is not limited to this analysis method, and other quantitative analysis methods may be used.

Figure 0006140687
Figure 0006140687

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〔製造時の亀裂〕
鋳塊の外観上の亀裂について次のように評価した。
まず、高ジルコニア質電鋳耐火物の鋳塊から押し湯部分を切除して、厚み２５０ｍｍ×幅３１０ｍｍ×高さ８２０ｍｍの耐火物製品の素材を製造した。次いで、その素材にある肉眼で確認できる亀裂の長さをノギスにて計測した。[Cracks during manufacturing]
The crack on the appearance of the ingot was evaluated as follows.
First, a hot metal portion was cut out from an ingot of a high zirconia electrocast refractory to produce a refractory product material having a thickness of 250 mm × width of 310 mm × height of 820 mm. Subsequently, the length of the crack which can be confirmed with the naked eye in the raw material was measured with calipers.

耐火物製品の素材における亀裂の最大長さが１００ｍｍ以上である場合、必要な耐火物製品寸法に対して非常に大きな鋳塊を製作した上で高負荷の研削や切断が必要となるため、その耐火物製造は非常に原価が高くなり現実的でない。耐火物製品の素材における亀裂長さが短ければ、必要な耐火物製品の寸法よりわずかに大きい鋳塊を製造し、表面に軽度の研削を行うだけで良いので耐火物の製造は容易である。そのため、耐火物製品の素材における亀裂長さは、１００ｍｍ未満であることが好ましく、より好ましくは７０ｍｍ以下、さらに好ましくは５０ｍｍ以下、最も好ましくは３０ｍｍ未満である。   If the maximum length of cracks in the material of the refractory product is 100 mm or more, it is necessary to grind and cut with a high load after manufacturing a very large ingot for the required refractory product dimensions. Refractory manufacturing is very expensive and unrealistic. If the crack length in the material of the refractory product is short, the production of the refractory is easy because it is only necessary to produce an ingot that is slightly larger than the required refractory product dimensions and to perform light grinding on the surface. Therefore, the crack length in the material of the refractory product is preferably less than 100 mm, more preferably 70 mm or less, still more preferably 50 mm or less, and most preferably less than 30 mm.

〔熱サイクル試験での残存体積膨張率〕
製造した電鋳耐火物から４０ｍｍ×４０ｍｍ×４０ｍｍの試料を切り出し、８００℃と１２５０℃の間を４０回往復させる加熱・冷却を電気炉中で実施した。この際、室温から８００℃の間の加熱は毎時１６０℃にて行い、ここから、８００℃到達後直ちに１２５０℃の加熱を毎時４５０℃にて行い、１２５０℃到達後直ちに８００℃までの冷却を毎時４５０℃にて行って１回の熱サイクルとした、８００℃と１２５０℃の熱サイクルを４０回繰り返した。最終の熱サイクル後は毎時１６０℃にて８００℃から室温まで冷却した。この試験前および試験後で試料の寸法を測定し、その寸法変化から残存体積膨張率を求めた。[Residual volume expansion coefficient in thermal cycle test]
A 40 mm × 40 mm × 40 mm sample was cut out from the produced electroformed refractory, and heating / cooling was performed in an electric furnace to reciprocate between 800 ° C. and 1250 ° C. 40 times. At this time, heating from room temperature to 800 ° C. is performed at 160 ° C. per hour, and from here, immediately after reaching 800 ° C., heating at 1250 ° C. is performed at 450 ° C. per hour, and cooling to 800 ° C. is performed immediately after reaching 1250 ° C. A thermal cycle of 800 ° C. and 1250 ° C., which was performed at 450 ° C. per hour to form one thermal cycle, was repeated 40 times. After the final thermal cycle, it was cooled from 800 ° C. to room temperature at 160 ° C. per hour. The dimensions of the sample were measured before and after the test, and the residual volume expansion coefficient was determined from the dimensional change.

この熱サイクル試験において高ジルコニア質電鋳耐火物は、一般に残存体積膨張を示し、場合によっては亀裂を生じる。この残存体積膨張は、比較的低温域での熱サイクルに対する耐火物単体での試験により得られ、ガラス溶融炉へ耐火物を適用した際に溶融ガラスから離れて比較的低温である炉外面付近の割れ耐性を示している。この試験による残存体積膨張率が３体積％未満であると好ましく、２体積％未満であるとさらに好ましい。   In this thermal cycle test, high zirconia electroformed refractories generally exhibit residual volume expansion and in some cases crack. This residual volume expansion is obtained by testing the refractory alone against a thermal cycle in a relatively low temperature region, and when the refractory is applied to a glass melting furnace, it is near the outer surface of the furnace that is relatively low temperature away from the molten glass. It shows crack resistance. The residual volume expansion rate by this test is preferably less than 3% by volume, and more preferably less than 2% by volume.

〔熱サイクル試験でのジルコン結晶生成率〕
さらに、この熱サイクル試験でジルコン結晶が生成する耐火物もある。上記熱サイクル試験を経た電鋳耐火物について、ジルコン結晶の生成率を粉末エックス線回折法により求めた。すなわち、試験後試料を粉砕した粉末でエックス線回折測定をし、その回折パターンからジルコン結晶、ジルコニア結晶のピーク面積比を求めて、ジルコン結晶量／（ジルコン結晶量＋ジルコニア結晶量）の比により質量％を決定した。これを熱サイクル試験でのジルコン結晶生成率とした。ジルコン結晶生成率は、４質量％以下が好ましく、２質量％以下がより好ましい。[Zircon crystal formation rate in thermal cycle test]
In addition, some refractories produce zircon crystals in this thermal cycle test. About the electrocast refractory which passed the said heat cycle test, the production | generation rate of the zircon crystal was calculated | required with the powder X ray diffraction method. That is, after the test, X-ray diffraction measurement was performed on the pulverized powder and the peak area ratio of the zircon crystal and zirconia crystal was obtained from the diffraction pattern. %It was determined. This was defined as the zircon crystal production rate in the thermal cycle test. The zircon crystal production rate is preferably 4% by mass or less, and more preferably 2% by mass or less.

〔浸漬試験でのジルコン結晶生成率〕
溶融ガラスとの接触条件下におけるジルコン結晶生成率は、次の浸漬試験により求めた。すなわち、得られた電鋳耐火物から１５ｍｍ×２５ｍｍ×３０ｍｍの試料を切り出して、これを２００ｃｃ白金るつぼ中に２５０ｇの無アルカリガラスカレットとともに挿入し、所定の温度と所定の時間、電気炉中で加熱した。冷却後、試料を取り出し、試料を粉砕した。粉砕した試料粉末でエックス線回折測定をし、その回折パターンからジルコン結晶、ジルコニア結晶のピーク面積比を求めて、ジルコン結晶量／（ジルコン結晶量＋ジルコニア結晶量）の比により質量％を決定し、これを浸漬試験でのジルコン結晶生成率とした。[Zircon crystal formation rate in immersion test]
The zircon crystal production rate under the contact condition with molten glass was determined by the following immersion test. That is, a 15 mm × 25 mm × 30 mm sample was cut out from the obtained electroformed refractory, and this was inserted into a 200 cc platinum crucible together with 250 g of an alkali-free glass cullet, and a predetermined temperature and a predetermined time in an electric furnace. Heated. After cooling, the sample was taken out and crushed. X-ray diffraction measurement is performed on the pulverized sample powder, the peak area ratio of the zircon crystal and zirconia crystal is obtained from the diffraction pattern, and the mass% is determined by the ratio of zircon crystal amount / (zircon crystal amount + zirconia crystal amount), This was defined as the zircon crystal production rate in the immersion test.

この試験に用いたガラスは、化学組成が、ＳｉＯ2 が６０質量％、Ｂ2 Ｏ3 が８質量％、Ａｌ2 Ｏ3 が１７質量％、ＭｇＯが３質量％、ＣａＯが４質量％、ＳｒＯが８質量％、である無アルカリガラスである。The glass used in this test has a chemical composition of SiO 2 60 mass%, B 2 O 3 8 mass%, Al 2 O 3 17 mass%, MgO 3 mass%, CaO 4 mass%, SrO. Is an alkali-free glass.

なお、浸漬試験における試験条件は、下記の通りとした。
浸漬試験１としては、１２５０℃にて２０日間の試験を行った。このとき、室温から１２５０℃までの加熱は、毎時３００℃とし、１２５０℃到達後２０日間の温度保持をした後、７００℃まで毎時５００℃で冷却、さらに７００℃から室温まで毎時６０℃の冷却をした。この試験においてジルコン結晶生成率は、４質量％以下が好ましく、２質量％以下がより好ましい。The test conditions in the immersion test were as follows.
As immersion test 1, a test was conducted at 1250 ° C. for 20 days. At this time, heating from room temperature to 1250 ° C. is performed at 300 ° C. per hour, and after holding at 1250 ° C., the temperature is maintained for 20 days, then cooled to 700 ° C. at 500 ° C. per hour, and further cooled from 700 ° C. to room temperature at 60 ° C. per hour. Did. In this test, the zircon crystal production rate is preferably 4% by mass or less, and more preferably 2% by mass or less.

浸漬試験２としては、１４５０℃にて４日間の試験を行った。このとき、室温から１４５０℃までの加熱は、毎時３００℃とし、１４５０℃到達後４日間の温度保持をした後、７００℃まで毎時５００℃で冷却、さらに７００℃から室温まで毎時６０℃の冷却をした。この試験においてジルコン結晶生成率は、４質量％以下が好ましく、２質量％以下がより好ましい。   As the immersion test 2, a test was conducted at 1450 ° C. for 4 days. At this time, heating from room temperature to 1450 ° C. is performed at 300 ° C. per hour. After reaching 1450 ° C., the temperature is maintained for 4 days, then cooled to 700 ° C. at 500 ° C. per hour, and further cooled from 700 ° C. to room temperature at 60 ° C. per hour. Did. In this test, the zircon crystal production rate is preferably 4% by mass or less, and more preferably 2% by mass or less.

上記した試験結果について、表１〜表５に併せて示した。
表１および表２、表４から明らかなように、本発明による高ジルコニア質電鋳耐火物は、製造時の亀裂が３０ｍｍ未満と十分に抑制されているか、亀裂があっても７０ｍｍ以下であった。したがって、本発明の高ジルコニア質電鋳耐火物は、高い生産性で容易に製造できる。The above test results are shown in Tables 1 to 5 together.
As is clear from Table 1, Table 2, and Table 4, the high zirconia electrocast refractory according to the present invention has a crack sufficiently controlled to be less than 30 mm during production, or is 70 mm or less even if there is a crack. It was. Therefore, the high zirconia electrocast refractory of the present invention can be easily manufactured with high productivity.

実施例である例１〜例１５および例２３〜２５の電鋳耐火物は、どれも熱サイクル試験での残存体積膨張率が３体積％未満であった。さらに表中には記載していないが、この試験ではどの実施例においても試料に亀裂は生じなかった。本発明の高ジルコニア質電鋳耐火物は、耐火物単体での温度変化に対する割れ耐性が高いことがわかった。   The electrocast refractories of Examples 1 to 15 and Examples 23 to 25, which are examples, all had a residual volume expansion coefficient of less than 3% by volume in a thermal cycle test. Further, although not shown in the table, the sample did not crack in any of the examples in this test. It was found that the high zirconia electrocast refractory of the present invention has high crack resistance against temperature changes in the refractory alone.

例１，３，７〜１４，２３，２５の電鋳耐火物は、熱サイクル試験後試料からはジルコン結晶が検出されなかった。この測定法によれば、ジルコン結晶生成率の値が、０．５質量％以上であればジルコン結晶が検出できるので、例１，３，７〜１４，２３，２５の電鋳耐火物は熱サイクル試験においてジルコン結晶を生成する反応が実質的に皆無だといえる。また、例２，４〜６，１５，２４は、ジルコン結晶の生成を抑制する成分、すなわち、Ａｌ2 Ｏ3、Ｋ2 Ｏ、Ｃｓ2 Ｏと、ジルコン結晶の生成を促進する成分、すなわち、Ｂ2 Ｏ3 とＰ2 Ｏ5の含有量の兼ね合いの結果、わずかだけジルコン結晶が生成する組成となったため、多少ジルコン結晶が生成しているが、その結晶生成率は、１．２質量％以下であり、亀裂の発生は十分に抑制できる範囲である。すなわち、本発明の高ジルコニア質電鋳耐火物は、耐火物単体でのジルコン結晶の生成が抑制されている。In the electrocast refractories of Examples 1, 3, 7 to 14, 23, and 25, no zircon crystals were detected from the samples after the thermal cycle test. According to this measurement method, since the zircon crystal can be detected if the value of the zircon crystal production rate is 0.5% by mass or more, the electroformed refractories of Examples 1, 3, 7 to 14, 23, and 25 are heated. In the cycle test, it can be said that there is virtually no reaction to form zircon crystals. Examples 2, 4 to 6, 15, and 24 are components that suppress the formation of zircon crystals, that is, Al 2 O 3 , K 2 O, Cs 2 O, and components that promote the formation of zircon crystals, that is, As a result of the balance between the contents of B 2 O 3 and P 2 O 5 , the composition was such that only a small amount of zircon crystals was produced, and thus some zircon crystals were produced, but the crystal production rate was 1.2% by mass. It is the following and it is the range which can fully suppress generation | occurrence | production of a crack. That is, in the high zirconia electrocast refractory of the present invention, the formation of zircon crystals in the refractory alone is suppressed.

例１〜１５，２３〜２５の電鋳耐火物の浸漬試験１でのジルコン結晶生成率は、１．８質量％以下である。さらに、例１〜１５，２３〜２５の電鋳耐火物の浸漬試験２でのジルコン結晶生成率もまた２．０質量％以下である。   The zircon crystal production rate in the immersion test 1 of the electrocast refractories of Examples 1 to 15 and 23 to 25 is 1.8% by mass or less. Furthermore, the zircon crystal production rate in the immersion test 2 of the electrocast refractories of Examples 1 to 15 and 23 to 25 is also 2.0% by mass or less.

浸漬試験１および浸漬試験２の双方において例１〜１５，２３〜２５の耐火物は、ジルコン結晶生成率が２．０質量％以下と非常に低く、本発明の高ジルコニア質電鋳耐火物は、ガラス接触条件下においてもジルコン結晶を生成し難いといえる。   In both immersion test 1 and immersion test 2, the refractories of Examples 1 to 15 and 23 to 25 have a very low zircon crystal production rate of 2.0% by mass or less, and the high zirconia electroformed refractory of the present invention is It can be said that it is difficult to produce zircon crystals even under glass contact conditions.

すなわち、本発明の高ジルコニア質電鋳耐火物は、製造時の亀裂も問題なく、耐火物単体での熱サイクルによる残存体積膨張率も低く、ジルコン結晶も生成し難く、さらには溶融ガラス接触条件においてもジルコン結晶の生成が抑制されており、生産性、使用時の温度変化、さらには再使用性にも優れた耐久性の高い耐火物である。   That is, the high zirconia electrocast refractory of the present invention has no problem of cracking during production, the residual volume expansion coefficient due to the thermal cycle of the refractory alone is low, it is difficult to produce zircon crystals, and the molten glass contact conditions Is also a highly durable refractory that is excellent in productivity, temperature change during use, and reusability.

表３および表５には、本発明に該当しない高ジルコニア質電鋳耐火物を比較例として示した。
例１６、例１８〜２２、例２６の耐火物では製造時の亀裂が１００ｍｍ以上であった。従って、これらの耐火物は、たとえ耐火物単体での温度変化に対する割れ耐性や耐火物単体でジルコン結晶の生成およびガラス接触条件下においてジルコン結晶の生成という点に問題がなくとも、生産性に問題がある。製造時の亀裂が３０ｍｍ未満であった、例１７、２７、２８については、後述するように、耐火物単体でのジルコン結晶およびガラス接触条件下におけるジルコン結晶が生じ易いといった問題点がある。In Tables 3 and 5, high zirconia electroformed refractories not corresponding to the present invention are shown as comparative examples.
In the refractories of Example 16, Examples 18 to 22, and Example 26, cracks during production were 100 mm or more. Therefore, these refractories have a problem in productivity even if there is no problem in crack resistance against temperature changes in the refractory alone, formation of zircon crystals in the refractory alone and formation of zircon crystals under glass contact conditions. There is. Examples 17, 27, and 28, in which cracks during production were less than 30 mm, had the problem that zircon crystals in a refractory alone and zircon crystals under glass contact conditions were likely to occur, as will be described later.

例２１、例２２の耐火物は、熱サイクル試験での残存体積膨張率が３体積％以上である。すなわち、この耐火物は、耐火物単体での温度変化に対する割れ耐性が不十分である。
例１６、１７、２２、２８の耐火物は、熱サイクル試験後試料からは４質量％以上のジルコン結晶が検出されている。すなわち、これらの耐火物は、耐火物単体でジルコン結晶を生成しやすい。
例１６、１７、２２、２７、２８の耐火物は、浸漬試験１および浸漬試験２でのジルコン結晶生成率はいずれも５質量％以上である。すなわち、これらの耐火物はガラス接触条件下においてジルコン結晶を生成しやすい。In the refractories of Examples 21 and 22, the residual volume expansion coefficient in the thermal cycle test is 3% by volume or more. In other words, this refractory has insufficient crack resistance against temperature changes in the refractory alone.
In the refractories of Examples 16, 17, 22, and 28, 4% by mass or more of zircon crystals were detected from the samples after the thermal cycle test. That is, these refractories easily generate zircon crystals with the refractory alone.
The refractories of Examples 16, 17, 22, 27, and 28 all have a zircon crystal production rate of 5% by mass or more in the immersion test 1 and the immersion test 2. That is, these refractories tend to form zircon crystals under glass contact conditions.

以上の結果より、本発明の高ジルコニア質電鋳耐火物は、生産性に優れ、熱上げ時に亀裂が発生し難く、耐火物単体で熱履歴を受けてもジルコン結晶を生成し難く、かつ溶融ガラスと接触してもジルコン結晶を生成し難いとわかる。そのため、使用中の温度変化や稼働休止時の熱下げにおいても亀裂を発生し難く、高い耐久性を有し、再使用性にも優れた高ジルコニア質電鋳耐火物であって、特に、低アルカリガラスおよび無アルカリガラスの溶融炉に好適である。   From the above results, the high zirconia electrocast refractory of the present invention is excellent in productivity, hardly cracks when heated up, hardly forms a zircon crystal even when subjected to a heat history alone, and melts. It can be seen that it is difficult to form zircon crystals even when in contact with glass. Therefore, it is a highly zirconia electroformed refractory material that is resistant to cracking even during temperature changes during use and heat reduction during operation suspension, has high durability, and is excellent in reusability. It is suitable for melting furnaces of alkali glass and non-alkali glass.

本発明の高ジルコニア質電鋳耐火物は、生産性に優れ、高い耐久性および良好な再使用性を有し、ガラス溶融炉の寿命を延長し、ガラス欠陥を低減させ、ガラス溶融炉の稼働停止と再稼働が容易となるため、特にガラス溶融炉の耐火物として好適である。
なお、２０１２年４月６日に出願された日本特許出願２０１２−０８７３０９号の明細書、特許請求の範囲、および要約書の全内容をここに引用し、本発明の開示として取り入れるものである。The high zirconia electrocast refractory of the present invention is excellent in productivity, has high durability and good reusability, extends the life of the glass melting furnace, reduces glass defects, and operates the glass melting furnace Since it is easy to stop and restart, it is particularly suitable as a refractory for a glass melting furnace.
It should be noted that the entire content of the specification, claims, and abstract of Japanese Patent Application No. 2012-087309 filed on April 6, 2012 is incorporated herein by reference.

Claims (6)

化学組成として、ＺｒＯ2 が８７〜９６質量％、ＳｉＯ2 が２．５〜９．０質量％、Ａｌ2 Ｏ3 が１．５質量％超、２．５質量％以下、Ｎａ2 Ｏが０．１５〜０．６質量％、Ｋ2 Ｏが０．３〜１．３質量％、Ｌｉ２Ｏが外掛けで０〜０．３質量％、Ｃｓ 2 Ｏが外掛けで０〜３．８質量％で含有することを特徴とする高ジルコニア質電鋳耐火物。 As chemical composition, ZrO 2 is 87-96 wt%, SiO 2 is 2.5 to 9.0 wt%, Al 2 O 3 is 1.5 wt percent, 2.5 wt% or less, Na 2 O is 0 .15-0.6% by mass, K 2 O: 0.3-1.3% by mass, Li 2 O: 0-0.3% by mass , and Cs 2 O: 0-3.8 A high zirconia electroformed refractory characterized by containing at a mass% . Ｂ２Ｏ３ とＰ２ Ｏ５ とを含有し、これらの合量（Ｂ２Ｏ３ ＋Ｐ２ Ｏ５ ）が外掛けで０．４質量％以下の範囲で含有する請求項１に記載の高ジルコニア質電鋳耐火物。 Containing a B 2 O 3 and P 2 O 5, these total amount (B 2 O 3 + P 2 O 5) is high according to claim 1 containing in the range of 0.4 wt% or less in outer percentage Zirconia electroformed refractory. さらに、Ｃｓ2 Ｏを外掛けで０．０５〜３．８質量％含有する請求項１または２のいずれかに記載の高ジルコニア質電鋳耐火物。 Furthermore, the high zirconia electrocast refractory according to any one of claims 1 and 2 containing 0.05 to 3.8% by mass of Cs 2 O as an outer shell. さらに、前記ＮａFurthermore, the Na 22 Ｏと前記Ｋ O and K 22 Ｏの合量（Ｎａ Total amount of O (Na 22 Ｏ＋Ｋ O + K 22 Ｏ）が、０．５〜１．６質量％である請求項１〜３のいずれかに記載の高ジルコニア質電鋳耐火物。 The high zirconia electroformed refractory according to any one of claims 1 to 3, wherein O) is 0.5 to 1.6 mass%. さらに、前記ＮａFurthermore, the Na 22 Ｏと前記Ｋ O and K 22 Ｏの比（Ｋ O ratio (K 22 Ｏ／Ｎａ O / Na 22 Ｏ）が、０．５〜８である請求項１〜４のいずれかに記載の高ジルコニア質電鋳耐火物。 O) is 0.5-8, The high zirconia electrocast refractory according to any one of claims 1 to 4. ガラス溶融炉用である請求項１〜５のいずれかに記載の高ジルコニア質電鋳耐火物。 The high zirconia electroformed refractory according to any one of claims 1 to 5 , which is used for a glass melting furnace.
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