JP4503339B2 - High zirconia electroformed refractories and manufacturing method thereof - Google Patents
High zirconia electroformed refractories and manufacturing method thereof Download PDFInfo
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- JP4503339B2 JP4503339B2 JP2004117462A JP2004117462A JP4503339B2 JP 4503339 B2 JP4503339 B2 JP 4503339B2 JP 2004117462 A JP2004117462 A JP 2004117462A JP 2004117462 A JP2004117462 A JP 2004117462A JP 4503339 B2 JP4503339 B2 JP 4503339B2
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- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 title claims description 126
- 239000011819 refractory material Substances 0.000 title claims description 16
- 238000004519 manufacturing process Methods 0.000 title description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 44
- 229910052799 carbon Inorganic materials 0.000 claims description 40
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 33
- 229910052760 oxygen Inorganic materials 0.000 claims description 33
- 239000001301 oxygen Substances 0.000 claims description 33
- 239000002245 particle Substances 0.000 claims description 33
- 206010021143 Hypoxia Diseases 0.000 claims description 31
- 238000005266 casting Methods 0.000 claims description 14
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 8
- 239000011230 binding agent Substances 0.000 claims description 8
- 229910052735 hafnium Inorganic materials 0.000 claims 1
- 229910052726 zirconium Inorganic materials 0.000 claims 1
- 239000011521 glass Substances 0.000 description 42
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 40
- 229910052697 platinum Inorganic materials 0.000 description 20
- 239000013078 crystal Substances 0.000 description 15
- 238000012360 testing method Methods 0.000 description 15
- 238000005187 foaming Methods 0.000 description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- 238000000034 method Methods 0.000 description 7
- 239000006060 molten glass Substances 0.000 description 7
- 238000004453 electron probe microanalysis Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000002844 melting Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 229910002804 graphite Inorganic materials 0.000 description 5
- 239000010439 graphite Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 238000010583 slow cooling Methods 0.000 description 4
- 230000009466 transformation Effects 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- 230000035939 shock Effects 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 239000004115 Sodium Silicate Substances 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 229910052845 zircon Inorganic materials 0.000 description 2
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 2
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000010954 inorganic particle Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- -1 magenesia clinker Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000004482 other powder Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000005361 soda-lime glass Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
- C03B5/42—Details of construction of furnace walls, e.g. to prevent corrosion; Use of materials for furnace walls
- C03B5/43—Use of materials for furnace walls, e.g. fire-bricks
Description
本発明はガラス溶融炉に適した高ジルコニア質電鋳耐火物とその製造方法、特に酸素不足度が低く、かつ炭素（Ｃ）含有率の少ない高ジルコニア質電鋳耐火物とその製造方法に関する。 The present invention relates to a high zirconia electrocast refractory suitable for a glass melting furnace and a method for producing the same, and more particularly to a high zirconia electrocast refractory having a low oxygen deficiency and a low carbon (C) content and a method for producing the same.
電鋳耐火物は、原料を溶融し、溶融物を所定形状の鋳型で鋳造し、これを徐冷することによって製造される。従って、電鋳耐火物は、焼成法による耐火物とは、組織、製造方法とも異なる非常に緻密な耐火物として知られている。 An electroformed refractory is produced by melting a raw material, casting the melt with a mold having a predetermined shape, and gradually cooling it. Therefore, the electroformed refractory is known as a very dense refractory which is different from the structure and manufacturing method of the refractory by the firing method.
このような電鋳耐火物の中で、ジルコニア含有率が８５〜９６重量％である高ジルコニア質電鋳耐火物は、ジルコニアの結晶と僅かのガラス相からなり、あらゆる種類の溶融ガラスに対し耐食性に極めて優れており、溶融ガラスとの界面に反応層を作らない性質を持つことから、ガラス中にストーンやコードと呼ばれる欠陥を発生させることがない。 Among such electrocast refractories, high zirconia electrocast refractories having a zirconia content of 85 to 96% by weight are composed of zirconia crystals and a slight glass phase, and are resistant to all kinds of molten glass. And has no property of forming a reaction layer at the interface with the molten glass, so that defects such as stones and cords are not generated in the glass.
このような理由で、ジルコニア含有率が８５〜９６重量％である高ジルコニア質電鋳耐火物は、高品位のガラスを製造するのに特に適している。 For this reason, a high zirconia electrocast refractory having a zirconia content of 85 to 96% by weight is particularly suitable for producing high-quality glass.
そのような高ジルコニア質電鋳耐火物において、その大部分を占めるジルコニア結晶は、８００〜１２００℃で急激な体積変化を伴って単斜晶系と正方晶系の可逆的な変態を起こすことが知られている。 In such a high zirconia electrocast refractory, the zirconia crystal occupying most of the zirconia can cause a reversible transformation between a monoclinic system and a tetragonal system with a rapid volume change at 800 to 1200 ° C. Are known.
それゆえ、製作の際に亀裂ない高ジルコニア質電鋳耐火物を得るためには、この変態に伴う応力をいかにして緩和させるかが大きな課題である。 Therefore, in order to obtain a high zirconia electroformed refractory that does not crack during manufacture, how to relieve the stress associated with this transformation is a major issue.
この課題を解決するために、従来、いろいろとガラス相の改善について提案がなされ、ある程度改善されている。 In order to solve this problem, various proposals for improving the glass phase have been made in the past.
しかしながら、高ジルコニア質電鋳耐火物は、ガラス溶融炉に使用する際、溶融ガラスに対して泡を発生させる原因となっていた。 However, the high zirconia electroformed refractory has been a cause of generating bubbles in the molten glass when used in a glass melting furnace.
さらに、高ジルコニア質電鋳耐火物は、熱衝撃に弱く、操炉初期の熱上げの際に、比較的低い３００〜６００℃で剥離や破断が生じることもあった。 Furthermore, the high zirconia electrocast refractory material is vulnerable to thermal shock, and peeling or fracture may occur at a relatively low temperature of 300 to 600 ° C. when the heat is raised in the initial stage of operation.
これらの欠点を取り除くために、種々の改良がなされてきた。 Various improvements have been made to eliminate these drawbacks.
例えば、特許文献１では、ＭｇＯを加えることによって発泡性や熱衝撃性を改善している。 For example, in patent document 1, foaming property and thermal shock property are improved by adding MgO.
また、特許文献２では、原料中に含まれるＦｅやＣｕなどの不純物を少なくすることによって、発泡性を改善している。 Moreover, in patent document 2, foaming property is improved by reducing impurities, such as Fe and Cu, contained in a raw material.
また、特許文献３では、ガラス相の熱膨張係数を低下させ、残留応力の適正化を図り、使用時の熱衝撃によって剥離を生じないように改善している。
高ジルコニア質電鋳耐火物は、一般に、珪砂などの徐冷材中に埋設したグラファイト鋳型に熔湯を入れて鋳造し、そのまま徐冷して製作されている。 High zirconia electrocast refractories are generally produced by pouring molten metal into a graphite mold embedded in a slow cooling material such as silica sand and then cooling it as it is.
しかし、この方法では、耐火物がグラファイトによる還元作用を受け、得られる耐火物は酸素濃度が化学量論値より少ない不飽和酸化物であり、かつ、グラファイト鋳型による浸炭作用で、耐火物中に炭素を含有した状態となってしまう。 However, in this method, the refractory is reduced by graphite, and the resulting refractory is an unsaturated oxide having an oxygen concentration lower than the stoichiometric value. It will be in the state containing carbon.
このような高ジルコニア質電鋳耐火物は、使用されるガラス溶融炉において、ガラス中に気泡を生じさせてガラス製品の品質を低下させる。 Such a high zirconia electrocast refractory causes bubbles in the glass in the glass melting furnace to be used, thereby reducing the quality of the glass product.
また、気泡の発生を防止する対策の一つとして、耐火物の周囲に白金を被覆することがある。 Moreover, as one of the measures for preventing the generation of bubbles, there is a case where platinum is coated around the refractory.
しかし、酸素不足度が高く、炭素を含有した状態の高ジルコニア質電鋳耐火物は、白金と接触すると、白金を劣化させることがある。 However, a high zirconia electrocast refractory having a high degree of oxygen deficiency and containing carbon may deteriorate platinum when it comes into contact with platinum.
前述の特許文献１〜３に開示された発明においても、改善度合いが不十分であり、また、製造工程が複雑で高価になるという欠点があった。 The inventions disclosed in the above-mentioned Patent Documents 1 to 3 have the disadvantage that the degree of improvement is insufficient and the manufacturing process is complicated and expensive.
本発明の目的は、このような従来技術の問題点を克服し、ガラス溶融炉に適した高ジルコニア質電鋳耐火物、たとえば、酸素不足度が低く、炭素の含有率が極めて少なく、そのために溶融ガラスに対して発泡性の少ない特徴を持つ高ジルコニア質電鋳耐火物及びその製造方法を提供することである。 The object of the present invention is to overcome such problems of the prior art, and to provide a high zirconia electroformed refractory suitable for a glass melting furnace, for example, a low oxygen deficiency and a very low carbon content. It is to provide a high zirconia electroformed refractory having characteristics of low foamability with respect to molten glass and a method for producing the same.
本発明者らは、高ジルコニア質電鋳耐火物において、耐火物の不純物を含む化学組成と、その耐火物を使用してガラスを溶融したときの、ガラス中に欠陥として発生する泡の数との関係について鋭意研究を重ねた結果、前記ガラス中における泡の発生が、耐火物中に含まれる酸素不足度と炭素含有率に大きく依存することを見出し、この知見に基づいて本発明をなすに至った。 In the high zirconia electrocast refractory, the present inventors have a chemical composition containing impurities of the refractory, and the number of bubbles generated as defects in the glass when the refractory is used to melt the glass. As a result of earnest research on the relationship, it was found that the generation of bubbles in the glass largely depends on the oxygen deficiency and carbon content contained in the refractory, and the present invention is made based on this finding. It came.
本発明の解決手段を例示すると、請求項１〜７に記載の高ジルコニア質電鋳耐火物とその製造方法である。 Examples of the solution means of the present invention are the high zirconia electroformed refractory according to claims 1 to 7 and a method for producing the same.
本発明の好適な解決手段により提供される高ジルコニア質電鋳耐火物は、次のような耐火物中の化学組成を有する。すなわち、Ｚｒが６３〜７１重量％（ＺｒＯ２換算で８５〜９６重量％）であり、Ｓｉが１〜５重量％（ＳｉＯ２換算で３〜１０重量％）であり、Ａｌが０．３〜１重量％（Ａｌ２Ｏ３換算で０．５〜２重量％）であって、且つ、酸素不足度が１重量％以下であり、Ｃ（炭素）が１５０ｐｐｍ以下である。 The high zirconia electroformed refractory provided by the preferred solution of the present invention has the following chemical composition in the refractory. That is, Zr is 63 to 71 wt% (85 to 96 wt% in terms of ZrO 2 ), Si is 1 to 5 wt% (3 to 10 wt% in terms of SiO 2 ), and Al is 0.3 to a 1 wt% (Al 2 O 3 0.5~2 wt% in terms), and the oxygen deficiency is not less than 1 wt%, C (carbon) is less than 150 ppm.
また、本発明の好適な解決手段により提供される高ジルコニア質電鋳耐火物の製造方法においては、鋳造物の化学組成について、Ｚｒが６３〜７１重量％（ＺｒＯ２換算で８５〜９６重量％）、Ｓｉが１〜５重量％（ＳｉＯ２換算で３〜１０重量％）、Ａｌが０．３〜１重量％（Ａｌ２Ｏ３換算で０．５〜２重量％）となるように、原料を配合し、溶融し、さらに、炭素を含まない耐熱性粒子からなる鋳型によって鋳造し、徐冷する。 Further, in the method for producing a high zirconia electrocast refractory provided by the preferred solution of the present invention, the chemical composition of the cast is 63 to 71% by weight (85 to 96% by weight in terms of ZrO 2). ), Si is 1 to 5 wt% (3 to 10 wt% in terms of SiO 2 ), Al is 0.3 to 1 wt% (0.5 to 2 wt% in terms of Al 2 O 3 ), The raw materials are blended, melted, cast with a mold made of heat-resistant particles not containing carbon, and then slowly cooled.
本発明の高ジルコニア質電鋳耐火物は、酸素不足度が低いため、ガラスに対する発泡性が大きく改善されている。さらに、含まれる炭素を少なくすると、ガラスに対する発泡性が大きく改善されている。 Since the high zirconia electrocast refractory according to the present invention has a low degree of oxygen deficiency, its foamability with respect to glass is greatly improved. Further, when the amount of carbon contained is reduced, the foamability of glass is greatly improved.
酸素不足度の低下と含有炭素の少量化により、耐火物に起因する発泡の抑制効果が顕著となるために、ガラスの品質向上に多大な効果をもたらすことが可能となる。 Since the effect of suppressing foaming due to the refractory becomes remarkable due to the decrease in the degree of oxygen deficiency and the amount of contained carbon, the glass can be greatly improved in quality.
さらに、本発明の高ジルコニア質電鋳耐火物は、高ジルコニア質電鋳耐火物に白金を被覆して使用する際に、白金の劣化を防ぎ、白金の回収を容易にすることが可能となる。 Furthermore, the high zirconia electrocast refractory of the present invention can prevent platinum deterioration and facilitate the recovery of platinum when the high zirconia electrocast refractory is coated with platinum. .
本発明は、高ジルコニア質電鋳耐火物に含まれる酸素および炭素に着目し、溶融ガラスに対して低発泡性を実現した。すなわち、耐火物に含まれる酸素不足度を低くし、炭素含有率を少なくするという構成により、発泡を少なくするようにした。 The present invention pays attention to oxygen and carbon contained in high zirconia electroformed refractories, and realizes low foaming property for molten glass. That is, the degree of oxygen deficiency contained in the refractory is lowered and the carbon content is reduced to reduce foaming.
本発明は、高ジルコニア質電鋳耐火物を改良して、Ｚｒが６３〜７１重量％（ＺｒＯ２換算で８５〜９６重量％）であり、Ｓｉが１〜５重量％（ＳｉＯ２換算で３〜１０重量％）であり、Ａｌが０．３〜１重量％（Ａｌ２Ｏ３換算で０．５〜２重量％）であるように構成して、ガラス類の溶融に有効に作用するようにした。 In the present invention, the high zirconia electrocast refractory is improved so that Zr is 63 to 71 wt% (85 to 96 wt% in terms of ZrO 2 ), Si is 1 to 5 wt% (3 in terms of SiO 2 ). 10% by weight) and Al is 0.3 to 1% by weight (0.5 to 2% by weight in terms of Al 2 O 3 ) so as to effectively act on melting of glasses. I made it.
本発明は、高ジルコニア質電鋳耐火物の酸素不足度を１重量％以下とすることにより、発泡を顕著に少なくするものである。なお、酸素不足度の算出方法は、後述する。 The present invention significantly reduces foaming by setting the oxygen deficiency of the high zirconia electrocast refractory to 1% by weight or less. A method for calculating the oxygen deficiency will be described later.
さらに、本発明は、好適には、炭素含有率を１５０ｐｐｍ以下（より好ましくは１００ｐｐｍ以下）とすることにより、発泡を顕著に少なくするものである。 Furthermore, in the present invention, it is preferable that the foaming is remarkably reduced by setting the carbon content to 150 ppm or less (more preferably 100 ppm or less).
発泡が少なくなる効果は、ガラスの種類にもよるが、ソーダライムガラスにおいて特に顕著である。 The effect of reducing foaming is particularly significant in soda lime glass, although it depends on the type of glass.
高ジルコニア質電鋳耐火物に含まれる酸素不足度が低く、炭素が少ないと、発泡性が改善され他に、高ジルコニア質電鋳耐火物に白金を被覆して使用する際に、白金の劣化を防ぐ意味でも重要な役割を果たす。使用した白金が劣化すると、回収が困難になり、白金の再使用が困難になる。 Low oxygen deficiency contained in high zirconia electrocast refractories and low carbon content will improve foaming. In addition, when high zirconia electrocast refractories are coated with platinum, deterioration of platinum will occur. It also plays an important role in the prevention. When the used platinum deteriorates, it becomes difficult to collect and reuse of platinum becomes difficult.
次に、本発明の電鋳耐火物の、酸素不足度及びＣ（炭素）以外の化学組成について説明する。 Next, the chemical composition other than the oxygen deficiency and C (carbon) of the electrocast refractory of the present invention will be described.
Ｚｒ濃度は６３〜７１重量％（ＺｒＯ２換算で８５〜９６重量％）が好ましい。Ｚｒ濃度が７１重量％より高くなると、得られる電鋳耐火物に亀裂が生じることがある。また、Ｚｒ濃度が６３重量％未満になると、得られる電鋳耐火物の、溶融ガラスに対する耐食性が低下する。 The Zr concentration is preferably 63 to 71% by weight (85 to 96% by weight in terms of ZrO 2 ). If the Zr concentration is higher than 71% by weight, the resulting electroformed refractory may crack. On the other hand, when the Zr concentration is less than 63% by weight, the corrosion resistance of the obtained electroformed refractory to the molten glass is lowered.
Ｓｉ濃度は１〜５重量％（ＳｉＯ２換算で３〜１０重量％）が好ましい。Ｓｉは高ジルコニア質電鋳耐火物のガラス相の網目形成成分として必須である。鋳造したとき、亀裂のない高ジルコニア質電鋳耐火物を得るのに十分なガラス相を形成するためには、１重量％以上のＳｉが必要である。また、Ｓｉ濃度が５重量％よりも高くなると、得られる電鋳耐火物の溶融ガラスに対する耐食性が低下する。 The Si concentration is preferably 1 to 5% by weight (3 to 10% by weight in terms of SiO 2 ). Si is essential as a network forming component of the glass phase of the high zirconia electrocast refractory. When cast, in order to form a glass phase sufficient to obtain a high zirconia electrocast refractory without cracks, 1 wt% or more of Si is required. Moreover, when Si concentration becomes higher than 5 weight%, the corrosion resistance with respect to the molten glass of the electrocast refractory obtained will fall.
また、Ａｌは、ガラス相の粘度を調節するために重要な役割を果たしている。高ジルコニア質電鋳耐火物は、ジルコニア結晶相とガラス相より構成される。ジルコニア結晶には前記のように変態による体積変化が生じる。このジルコニア結晶の体積変化により生じる応力を、ガラス相が緩衝しうるためには、ジルコニア結晶の変態温度域におけるガラス相の粘度を適度な範囲としなければならない。 Further, Al plays an important role in adjusting the viscosity of the glass phase. High zirconia electrocast refractories are composed of a zirconia crystal phase and a glass phase. In the zirconia crystal, a volume change due to transformation occurs as described above. In order for the glass phase to buffer the stress caused by the volume change of the zirconia crystal, the viscosity of the glass phase in the transformation temperature range of the zirconia crystal must be in an appropriate range.
そこで、本発明者らは、Ａｌ濃度と得られる電鋳耐火物の亀裂の有無の関係について鋭意研究を重ねた結果、電鋳耐火物の酸素不足度を１重量％以下、炭素含有率を１５０ｐｐｍ以下として、後述する鋳型によって鋳造して、本発明の電鋳耐火物を得る試みをした。そして、電鋳耐火物のＡｌ濃度が０．３〜１重量％（Ａｌ２Ｏ３換算で０．５〜２重量％）であれば、亀裂のない電鋳耐火物が得られることを見出した。 Therefore, as a result of intensive studies on the relationship between the Al concentration and the presence or absence of cracks in the electrocast refractory, the inventors have found that the oxygen deficiency of the electrocast refractory is 1 wt% or less and the carbon content is 150 ppm. In the following, an attempt was made to obtain the electrocast refractory of the present invention by casting with a mold described later. And if the Al concentration of the electroformed refractory is 0.3 to 1% by weight (0.5 to 2% by weight in terms of Al 2 O 3 ), it was found that an electroformed refractory without cracks can be obtained. .
Ａｌ濃度が０．３重量％（Ａｌ２Ｏ３換算で０．５重量％）よりも低くなると、得られる電鋳耐火物の耐食性が低下することがある。逆に、Ａｌ濃度が１重量％（Ａｌ２Ｏ３換算で２重量％）よりも高くなると、後述する材質の鋳型で鋳造したとき、得られる電鋳耐火物のガラス相の一部が結晶化し、亀裂が生じることがある。 When the Al concentration is lower than 0.3% by weight (0.5% by weight in terms of Al 2 O 3 ), the corrosion resistance of the resulting electroformed refractory may be lowered. Conversely, when the Al concentration is higher than 1% by weight ( 2 % by weight in terms of Al 2 O 3 ), a part of the glass phase of the resulting electroformed refractory crystallizes when cast with a mold made of the material described later. , Cracks may occur.
したがって、本発明の好ましい高ジルコニア質電鋳耐火物は、Ｚｒが６３〜７１重量％（ＺｒＯ２換算で８５〜９６重量％）であり、Ｓｉが１〜５重量％（ＳｉＯ２換算で３〜１０重量％）であり、Ａｌが０．３〜１重量％（Ａｌ２Ｏ３換算で０．５〜２重量％）であり、酸素不足度が１重量％以下であり、かつＣが１５０ｐｐｍ以下である。 Thus, preferred high zirconia electrocast refractories of the present invention, Zr is 63 to 71 wt% (85-96 wt% in terms of ZrO 2), Si is 1 to 5% by weight (3 in terms of SiO 2 10 wt%), Al is 0.3 to 1 wt% (0.5 to 2 wt% in terms of Al 2 O 3 ), oxygen deficiency is 1 wt% or less, and C is 150 ppm or less. It is.
次に、本発明の好ましい高ジルコニア質電鋳耐火物の製造方法の一例を示す。 Next, an example of the manufacturing method of the preferable high zirconia electrocast refractory of this invention is shown.
所定の原料配合物を電気炉にて溶融し、この溶融物を、徐冷材中に埋設した炭素を含まない耐熱性粒子からなる鋳型によって鋳造し、鋳造後も徐冷材中に埋設しておき、十分に徐冷する。 A predetermined raw material composition is melted in an electric furnace, and this melt is cast by a mold made of heat-resistant particles not containing carbon embedded in a slow cooling material, and is embedded in the slow cooling material after casting. Slowly cool.
この製造方法を用いると、高ジルコニア質電鋳耐火物中の酸素不足度を１重量％以下、炭素含有率を１５０ｐｐｍ以下に容易かつ確実に低減できる。これに対し、従来のグラファイト鋳型を用いる製造方法では、このような低い酸素不足度と少量の炭素含有は、実現し難い。 If this manufacturing method is used, the oxygen deficiency in the high zirconia electroformed refractory can be easily and reliably reduced to 1 wt% or less and the carbon content to 150 ppm or less. On the other hand, it is difficult to realize such a low oxygen deficiency and a small amount of carbon by a conventional manufacturing method using a graphite mold.
鋳型は、好ましくは炭素を含まない耐熱性粒子を有機質バインダー或いは無機質バインダーで結合したものを使用する。 As the template, preferably used is one obtained by bonding heat-resistant particles not containing carbon with an organic binder or an inorganic binder.
炭素を含む耐熱性粒子とは、例えばＳｉＣ粒子のように、化学組成としてＣ（炭素）を含むものをいう。これに対し、本発明でいう「炭素を含まない耐熱性粒子」とは、化学組成として実質的にＣを含有しない粒子であり、不純物として微量のＣを含んでいることもある。 The heat-resistant particles containing carbon refer to those containing C (carbon) as a chemical composition, such as SiC particles. On the other hand, “heat-resistant particles not containing carbon” as used in the present invention are particles that do not substantially contain C as a chemical composition, and may contain a trace amount of C as an impurity.
このような耐熱性粒子は、機械的強度と耐熱性に優れていて、炭素を含まない無機粒子が好的な例である。 Such heat-resistant particles are excellent in mechanical strength and heat resistance, and inorganic particles containing no carbon are preferable examples.
このような好ましい耐熱性粒子としては、例えば、アルミナ、ジルコニア、マグネシア、ジルコンなどの粒子がある。これらの耐熱性粒子は、高純度のものが、更に耐熱性に優れていて、より好ましい。 Examples of such preferable heat-resistant particles include particles of alumina, zirconia, magnesia, zircon and the like. As these heat-resistant particles, high-purity particles are more preferable because they are further excellent in heat resistance.
耐熱性粒子の材質としては、特にジルコニア粒子が好ましい。ジルコニア粒子を用いると、断熱性に優れ、鋳造物の酸化が進み、酸素不足度が０．５重量％以下、炭素含有率が１００ｐｐｍ以下の高ジルコニア質電鋳耐火物が得られて、発泡特性が顕著に優れている。 As a material of the heat resistant particles, zirconia particles are particularly preferable. When zirconia particles are used, heat insulation is excellent, oxidation of the casting progresses, high zirconia electroformed refractory having an oxygen deficiency of 0.5 wt% or less and a carbon content of 100 ppm or less is obtained, and foaming characteristics Is significantly better.
耐熱性粒子として、その他に、アルミナ質、高ジルコニア質またはアルミナジルコニアシリカ質などの各種電鋳耐火物を粉砕した粒子が好ましく使用できる。これらの粒子は、炭素を含まず、十分な機械的強度と耐熱性が得られて理想的である。 In addition, particles obtained by pulverizing various electroformed refractories such as alumina, high zirconia, or alumina zirconia silice can be preferably used as the heat resistant particles. These particles are ideal because they do not contain carbon and provide sufficient mechanical strength and heat resistance.
また、耐熱性粒子の粒径（粒径の測定は、振動型篩いにより行った）は、０．１〜５ｍｍとするのが好ましい。粒径が０．１ｍｍ未満の粒子を含むと、鋳型は鋳造時の溶湯によって比較的溶融し易い上、鋳型作製の際に多量のバインダーを必要とする。また、粒径が５ｍｍを超える粒子を含むと、十分な鋳型の強度を確保し難い。 Moreover, it is preferable that the particle size of the heat-resistant particles (the particle size is measured by a vibration type sieve) is 0.1 to 5 mm. If the particle size includes particles of less than 0.1 mm, the mold is relatively easily melted by the molten metal at the time of casting, and a large amount of binder is required for producing the mold. Moreover, when the particle size contains particles exceeding 5 mm, it is difficult to ensure sufficient mold strength.
バインダーとしては、有機質或いは無機質の各種バインダーが使用できる。特に無機バインダーはＣ（炭素）を含まないことから好ましく使用できる。無機バインダーのなかでも珪酸ソーダ水溶液が特に好ましい。 As the binder, various organic or inorganic binders can be used. In particular, the inorganic binder can be preferably used because it does not contain C (carbon). Of the inorganic binders, a sodium silicate aqueous solution is particularly preferable.
また、鋳型は、１０００℃における熱伝導率が１０Ｗ／ｍＫ以下であることが好ましい。熱伝導率が低いと、鋳造後、長時間にわたって鋳造物の温度が高く、例えば電極から混入したＣ（炭素）が酸化され易くなり、結果としてＣの少ない高ジルコニア質電鋳耐火物が得られる。この理由により、１０００℃における熱伝導率は１０Ｗ／ｍＫ以下であることが好ましい。 The mold preferably has a thermal conductivity at 1000 ° C. of 10 W / mK or less. If the thermal conductivity is low, the temperature of the casting is high for a long time after casting. For example, C (carbon) mixed from the electrode is easily oxidized, and as a result, a high zirconia electrocast refractory with less C is obtained. . For this reason, the thermal conductivity at 1000 ° C. is preferably 10 W / mK or less.
本発明の高ジルコニア質電鋳耐火物を次のようにして作製した。 The high zirconia electroformed refractory of the present invention was produced as follows.
脱珪ジルコニアに、シリカ、アルミナ、その他の粉末原料を所定の割合で加え、これらを混合後、アーク電気炉で溶融し、その溶融物を、別に準備した珪砂の中に埋設した鋳型によって鋳造し、そのまま徐冷した。 Silica, alumina, and other powder raw materials are added to desiliconized zirconia at a prescribed ratio, and after mixing these, they are melted in an arc electric furnace, and the melt is cast by a mold embedded in a separately prepared silica sand. Then, it was gradually cooled.
鋳型は、実験例２〜５では各種耐熱性粒子に珪酸ソーダ水溶液を４重量％添加し、混練し、５０ｍｍの厚さに造型した後に、熱硬化して作製し、実験例１ではグラファイト板を使用して作製した。 In Examples 2 to 5, the mold was prepared by adding 4% by weight of a sodium silicate aqueous solution to various heat-resistant particles, kneading and molding to a thickness of 50 mm, and then thermosetting. Made using.
前記の鋳型を構成する耐熱性粒子としては、粒径が０．２〜５ｍｍである、電融アルミナ、マゲネシアクリンカー、ジルコンサンド、ジルコニアを用いた。 As the heat-resistant particles constituting the mold, fused alumina, magenesia clinker, zircon sand, and zirconia having a particle size of 0.2 to 5 mm were used.
鋳型は、製品部分の内寸法が１００×３００×３５０ｍｍで、その上部に内寸法が１８０×３００×１５０ｍｍの押し湯部分を一体に接続したものである。 The mold has an inner dimension of a product portion of 100 × 300 × 350 mm, and a hot water portion having an inner dimension of 180 × 300 × 150 mm is integrally connected to the upper part thereof.
徐冷後、製品部分を押し湯部分から切り離して試験耐火物として使用した。得られた試験耐火物はいずれも外観上亀裂はなかった。 After slow cooling, the product part was separated from the hot water part and used as a test refractory. None of the obtained test refractories had cracks in appearance.
この試験耐火物の化学成分は、Ｚｒ濃度がＺｒＯ２換算で９３．８重量％、Ｓｉ濃度がＳｉＯ２換算で４．５重量％、Ａｌ濃度がＡｌ２Ｏ３換算で１．３重量％、Ｎａ濃度がＮａ２Ｏで０．２重量％であった。 The chemical composition of this test refractory is such that the Zr concentration is 93.8% by weight in terms of ZrO 2 , the Si concentration is 4.5% by weight in terms of SiO 2 , the Al concentration is 1.3% by weight in terms of Al 2 O 3 , The Na concentration was 0.2% by weight with Na 2 O.
表１は、各実験例に用いた鋳型の材質、鋳型の１０００℃における熱伝導率（Ｗ／ｍＫ）、酸素不足度、試験耐火物の炭素含有率、各種ガラスの発泡試験による発泡数および白金回収の難易を示す。
酸素不足度は、試験耐火物の鋳込み面から約２５ｍｍの部分を切り出し、これを試料として、ＥＰＭＡ（電子線マイクロアナライザー）を用いて、酸素および酸素以外の各元素の濃度をジルコニア結晶とガラス相についてそれぞれ測定し、それらの測定値の加重平均をとることで、耐火物全体の酸素濃度と各元素の濃度を求め、酸素以外の各元素の濃度から各元素が完全に酸化される際に化学量論的に必要とする酸素濃度の総和を求め、その値から測定した耐火物全体の酸素濃度を差し引くことで決定した。 The oxygen deficiency is obtained by cutting out a portion of about 25 mm from the cast surface of the test refractory, and using this as a sample, using EPMA (electron beam microanalyzer), the concentration of each element other than oxygen and oxygen is measured with the zirconia crystal and the glass phase. The oxygen concentration of each refractory and the concentration of each element are obtained by taking a weighted average of the measured values, and the chemicals are obtained when each element is completely oxidized from the concentration of each element other than oxygen. The total amount of oxygen concentration required in terms of quantity was obtained, and the oxygen concentration of the entire refractory measured was subtracted from that value.
ＥＰＭＡによる酸素および各元素の濃度の測定は、株式会社島津製作所製ＥＰＭＡ８７０５を使用し、ジルコニア結晶およびガラス相のそれぞれについて行った。測定条件は、加速電圧１５ｋＶ、試料電流０．０５μＡ、ビーム径５μｍ、積算時間１０秒であった。定量補正にはＺＡＦ法を用いた。 The concentration of oxygen and each element by EPMA was measured for each of the zirconia crystal and the glass phase using EPMA 8705 manufactured by Shimadzu Corporation. The measurement conditions were an acceleration voltage of 15 kV, a sample current of 0.05 μA, a beam diameter of 5 μm, and an integration time of 10 seconds. The ZAF method was used for quantitative correction.
次に、酸素不足度の計算方法を説明する。 Next, a method for calculating the degree of oxygen deficiency will be described.
本発明の耐火物は、ジルコニア結晶とその粒界を充填するガラス相より形成されている。ここで、ジルコニア結晶が耐火物中で占める割合をＣＸ重量％、ガラス相が耐火物中で占める割合をＣＹ重量％とする。また、ＥＰＭＡにより定量されたジルコニア結晶中の酸素濃度をＣＯＸ重量％、ガラス相中の酸素濃度をＣＯＹ重量％とする。耐火物全体の酸素濃度をＣＯＲ重量％とすると、ＣＯＲは、以下に示す式１で表される。 The refractory according to the present invention is formed of a zirconia crystal and a glass phase filling the grain boundary. Here, C X wt% the percentage of zirconia crystals occupied by refractories, the proportion of glass phase occupied in refractories and C Y wt%. Further, the oxygen concentration in the zirconia crystal determined by EPMA is C OX wt%, and the oxygen concentration in the glass phase is C OY wt%. When the oxygen concentration of the entire refractory is COR wt%, COR is expressed by the following formula 1.
ＣＯＲ＝｛（ＣＯＸ/100）×（ＣＸ/100）＋（ＣＯＹ/100）×（ＣＹ/100）｝×100 （式１）
また、耐火物中に含まれる酸素以外の元素をＭ１、Ｍ２、Ｍ３、・・・とし、ジルコニア結晶中の酸素以外の元素の濃度をＣＭ１Ｘ、ＣＭ２Ｘ、ＣＭ３Ｘ、・・・重量％、ガラス相中の酸素以外の元素の濃度をＣＭ１Ｙ、ＣＭ２Ｙ、ＣＭ３Ｙ、・・・重量％、耐火物全体の酸素以外の元素の濃度をＣＭ１Ｒ、ＣＭ２Ｒ、ＣＭ３Ｒ、・・・重量％などとすると、例えば、ＣＭ１Ｒは以下の式で表される。
C OR = {(C OX / 100) × (C X / 100) + (C OY / 100) × (C Y / 100)} × 100 (Formula 1)
Further, elements other than oxygen contained in the refractory are defined as M1, M2, M3,..., And the concentration of elements other than oxygen in the zirconia crystal is defined as C M1X , C M2X , C M3X,. The concentration of elements other than oxygen in the glass phase is C M1Y , C M2Y , C M3Y ,... Wt%, and the concentration of elements other than oxygen in the entire refractory is C M1R , C M2R , C M3R,. For example, C M1R is expressed by the following formula.
ＣＭ１Ｒ＝｛（ＣＭ1Ｘ/100）×（ＣＸ/100）＋（ＣＭ１Ｙ/100）×（ＣＹ/100）｝×100 （式２）
さらに、ＣＭ２Ｒ、ＣＭ３Ｒ・・・も同様に表される。
C M1R = {(C M1X / 100) × (C X / 100) + (C M1Y / 100) × (C Y / 100)} × 100 (Formula 2)
Further, C M2R , C M3R .
次に、耐火物中に含まれる酸素以外の元素Ｍ１、Ｍ２、Ｍ３、・・・が化学量論的に必要とする酸素の濃度をＤＭ１、ＤＭ２、ＤＭ３、・・・重量％などとする。例えばＭ１の化学量論的な酸化物の化学式をＭ1ＡＯＢとし、Ｍ１の原子量をＷＭ１ ｇ／ｍｏｌ、酸素の原子量をＷＯ ｇ／ｍｏｌ（＝１６．００）とすると、例えば、ＤＭ１は以下の式で表される。 Next, oxygen concentrations stoichiometrically required by the elements M1, M2, M3,..., Other than oxygen contained in the refractory are set to D M1 , D M2 , D M3,. And For example, if the chemical formula of the stoichiometric oxide of M1 is M1 A O B , the atomic weight of M1 is W M1 g / mol, and the atomic weight of oxygen is W O g / mol (= 16.00), for example, D M1 is represented by the following equation.
ＤＭ１＝ＣＭ１Ｒ×（ＷＯ×Ｂ）／（ＷＭ１×Ａ） （式３）
さらに、ＤＭ２、ＤＭ３、・・・も同様に表される。
D M1 = C M1R × (W O × B) / (W M1 × A) (Formula 3)
Further, D M2 , D M3,.
ＤＭ１、ＤＭ２、ＤＭ３、・・・の総和をＤＴ重量％として、本願明細書では、酸素不足度Δ重量％を以下の式で定義する。 Assuming that the sum of D M1 , D M2 , D M3 ,... Is DT wt%, the oxygen deficiency Δ wt% is defined by the following formula in this specification.
Δ＝ＤＴ−ＣＯＲ （式４）
すなわち、酸素不足度Δとは、耐火物中の酸素以外の元素の定量値から算出された、それらの元素が化学量論的に必要とする酸素の濃度（ＤＴ重量％）と、実際に定量された耐火物中の酸素の濃度（ＣＯＲ重量％）との差である。
Δ = D T -C OR (Formula 4)
That is, the oxygen deficiency Δ is calculated from the quantitative value of elements other than oxygen in the refractory, and the oxygen concentration ( DT weight%) required by these elements stoichiometrically, and actually It is the difference from the quantified oxygen concentration ( COR wt%) in the refractory.
酸素不足度を、具体例を用いて詳細に説明する。 The degree of oxygen deficiency will be described in detail using a specific example.
表２は、本願明細書で述べた耐火物についてのＥＰＭＡ測定値と、酸素不足度Δの計算過程を示す。
この耐火物において、ジルコニア結晶が占める割合ＣＸは９３．８０重量％、ガラス相が占める割合ＣＹは６．２０重量％である。 In this refractory, the proportion C X occupied by zirconia crystals is 93.80 wt%, and the proportion C Y occupied by the glass phase is 6.20 wt%.
ＥＰＭＡによるジルコニア結晶相およびガラス相における酸素以外の各元素の濃度の測定値、ＣＺｒＸ、ＣＨｆＸ、ＣＹＸ、・・・およびＣＺｒＹ、ＣＨｆＹ、ＣＹＹ、・・・は、それぞれ、７２．４重量％、１．６０重量％、０．０１重量％、・・・および１．４０重量％、０．２５重量％、０．９３重量％であった。 The measured value of each element other than oxygen in the zirconia crystal phase and the glass phase by EPMA, C ZrX , C HfX , C YX ,... And C ZrY , C HfY , C YY ,. .4%, 1.60%, 0.01%,... And 1.40%, 0.25%, 0.93% by weight.
また、ジルコニア結晶相およびガラス相における酸素の濃度の測定値ＣＯＸおよびＣＯＹは、それぞれ２５．４９重量％および４８．５４重量％であった。これらの測定値から、耐火物全体における酸素以外の各元素の濃度ＣＺｒＲ、ＣＨｆＲ、ＣＹＲ、・・・は、それぞれ、６８．２８重量％、１．５２重量％、０．０７重量％、・・・と算定され、耐火物全体における酸素の濃度ＣＯＲは２６．９２重量％と算出される。 Further, the measured values C OX and C OY of the oxygen concentration in the zirconia crystal phase and the glass phase were 25.49 wt% and 48.54 wt%, respectively. From these measured values, the concentrations C ZrR , C HfR , C YR ,... Of each element other than oxygen in the entire refractory were 68.28 wt%, 1.52 wt%, and 0.07 wt%, respectively. , calculated to ..., concentration C OR of oxygen in the entire refractory is calculated to be 26.92 wt%.
さらに、耐火物中に含まれる炭素および酸素以外の元素が化学量論的に必要とする酸素の濃度ＤＺｒ、ＤＨｆ、ＤＹ、・・・は、それぞれ６８．２８重量％、１．５２重量％、０．０７重量％、・・・となり、これらの総和ＤＴは２７．３７重量％と求まる。 Further, the oxygen concentration D Zr that elements other than carbon and oxygen included in the refractory needs stoichiometrically, D Hf, D Y, · · ·, respectively 68.28 wt%, 1.52 Wt%, 0.07 wt%, and so on, and the sum DT of these is 27.37 wt%.
そして、ＤＴとＣＯＲの差から、酸素不足度Δは０．４５重量％と決定される。 The oxygen deficiency Δ is determined to be 0.45% by weight from the difference between D T and C OR .
なお、耐火物中に含まれる炭素および酸素以外の元素が化学量論的に必要とする酸素の濃度を算出するための、前記元素の酸化物組成式は、表１に示すように、ＺｒＯ２、ＨｆＯ２、Ｙ２Ｏ３、ＳｉＯ２、ＴｉＯ２、Ｆｅ２Ｏ３、ＣａＯ、Ａｌ２Ｏ３およびＮａ２Ｏとした。 In addition, as shown in Table 1, the oxide composition formula of the element for calculating the oxygen concentration stoichiometrically required by elements other than carbon and oxygen contained in the refractory is ZrO 2 and a HfO 2, Y 2 O 3, SiO 2, TiO 2, Fe 2 O 3, CaO, Al 2 O 3 and Na 2 O.
炭素含有率は、試験耐火物の鋳込み面から約２５ｍｍの部分を切り出し、これを試料として、ＪＩＳ Ｇ１２１１の全炭素量定量方法−高周波誘導加熱炉燃焼−赤外線吸収法により測定した。 The carbon content was measured by a JIS G1211 total carbon content quantification method—high frequency induction furnace combustion—infrared absorption method, with a portion of about 25 mm cut out from the cast surface of the test refractory.
発泡は次の方法で試験した。 Foaming was tested in the following manner.
各試験耐火物の鋳造面から約１５ｍｍ内部の３箇所から直径３３ｍｍ、厚さ８ｍｍの大きさの試験片を切り出し、この試験片を直径６５ｍｍの白金るつぼ内で溶融した３０ｇの３種類のガラスの中に浸漬し、温度１４００℃にて４時間保持した。試験後に白金るつぼの外周部分を水冷により１００℃以下まで急冷し、さらに、これを、６００〜７００℃の温度で８時間保持してガラスの除歪を行った。その後、試験片の中央部分１５×１５ｍｍの上部ガラスに残った泡を数えた。この泡の数を１ｃｍ２あたりに換算して発泡数とした。 A test piece having a diameter of 33 mm and a thickness of 8 mm was cut out from three locations approximately 15 mm from the cast surface of each test refractory, and the test pieces were melted in a platinum crucible having a diameter of 65 mm, and three kinds of 30 g of glass. It was immersed in and held at a temperature of 1400 ° C. for 4 hours. After the test, the outer peripheral part of the platinum crucible was rapidly cooled to 100 ° C. or less by water cooling, and further held at a temperature of 600 to 700 ° C. for 8 hours to remove the distortion of the glass. Thereafter, bubbles remaining in the upper glass of 15 × 15 mm in the central portion of the test piece were counted. The number of bubbles was converted to the number of bubbles per 1 cm 2 .
白金回収の難易度は、耐火物に白金を巻いて使用した後に、白金を回収する際の容易性を示す。 The difficulty level of platinum recovery indicates the ease with which platinum is recovered after the platinum is wrapped around a refractory.
表１の実験例２〜５は、本発明の実施例であるが、実験例１は、酸素不足度が１．２重量％であって、比較例である。 Experimental Examples 2 to 5 in Table 1 are examples of the present invention, but Experimental Example 1 is a comparative example having an oxygen deficiency of 1.2% by weight.
実験例１に示すように、グラファイト板の鋳型の１０００℃における熱伝導率は１００Ｗ／ｍＫと大きく、得られる耐火物の酸素不足度は１．２重量％、炭素含有率が１７０ｐｐｍであり、発泡試験後のガラスの発泡数は大きいものであった。 As shown in Experimental Example 1, the thermal conductivity at 1000 ° C. of the graphite plate mold is as large as 100 W / mK, the oxygen resistance of the obtained refractory is 1.2% by weight, the carbon content is 170 ppm, The number of foamed glass after the test was large.
これに対し、実験例２〜５に示すように、炭素を含まない耐熱性粒子によって作製した鋳型は、１０００℃における熱伝導率が１０Ｗ／ｍＫと小さく、得られる耐火物の酸素不足度は１重量％以下であり、さらに、炭素含有率が１５０ｐｐｍ以下であり、発泡試験後のガラスの発泡数は、より小さくなった。 On the other hand, as shown in Experimental Examples 2 to 5, a mold made of heat-resistant particles not containing carbon has a thermal conductivity at 1000 ° C. as small as 10 W / mK, and the obtained refractory has an oxygen deficiency of 1 The carbon content was 150 ppm or less, and the foaming number of the glass after the foaming test was smaller.
特に、実験例１と実験例５を比較するとよく分かるように、ジルコニア粒子を用いた鋳型は、１０００℃における熱伝導率が１Ｗ／ｍＫと極めて小さく、得られる耐火物の酸素不足度が０．５重量％以下であり、さらに、炭素含有率が１００ｐｐｍ以下であり、グラファイト板を使用した鋳型に鋳造して得られた耐火物に比べ、発泡試験後のガラスの発泡数が１／２以下となった。 In particular, as can be seen from comparison between Experimental Example 1 and Experimental Example 5, the mold using zirconia particles has an extremely low thermal conductivity of 1 W / mK at 1000 ° C., and the resulting refractory has an oxygen deficiency of 0. 5% by weight or less, and the carbon content is 100 ppm or less, and the number of foamed glass after the foaming test is 1/2 or less compared to a refractory obtained by casting into a mold using a graphite plate. became.
また、実験例２〜５に示すように、耐火物の酸素不足度が１重量％以下であり、炭素含有率が１５０ｐｐｍ以下であると、耐火物に白金を巻いて使用した後の、白金の回収が容易であった。 Moreover, as shown in Experimental Examples 2 to 5, when the oxygen deficiency of the refractory is 1% by weight or less and the carbon content is 150 ppm or less, the platinum of the refractory is used after being wrapped with platinum. Recovery was easy.
しかしながら、実験例１に示すように、耐火物の酸素不足度が１重量％を超え、さらには、炭素含有率が１５０ｐｐｍを超えると、耐火物に白金を巻いて使用した後は、白金が脆弱となり、その回収が困難であった。
However, as shown in Experimental Example 1, when the oxygen deficiency of the refractory exceeds 1% by weight and further the carbon content exceeds 150 ppm, the platinum is fragile after being used by winding platinum around the refractory. It was difficult to recover.
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