JP2004323265A - Refractory for continuous casting, which inhibits sticking of alumina - Google Patents
Refractory for continuous casting, which inhibits sticking of alumina Download PDFInfo
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- JP2004323265A JP2004323265A JP2003117580A JP2003117580A JP2004323265A JP 2004323265 A JP2004323265 A JP 2004323265A JP 2003117580 A JP2003117580 A JP 2003117580A JP 2003117580 A JP2003117580 A JP 2003117580A JP 2004323265 A JP2004323265 A JP 2004323265A
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- clinker
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 33
- 238000009749 continuous casting Methods 0.000 title claims abstract description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 40
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 37
- 239000010439 graphite Substances 0.000 claims abstract description 37
- 239000002245 particle Substances 0.000 claims abstract description 21
- 230000003647 oxidation Effects 0.000 abstract description 6
- 238000007254 oxidation reaction Methods 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 5
- 230000002401 inhibitory effect Effects 0.000 abstract 2
- 238000005266 casting Methods 0.000 description 9
- 229910000831 Steel Inorganic materials 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 239000011819 refractory material Substances 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- 239000010459 dolomite Substances 0.000 description 5
- 229910000514 dolomite Inorganic materials 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000003963 antioxidant agent Substances 0.000 description 4
- 230000003078 antioxidant effect Effects 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 229910000655 Killed steel Inorganic materials 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical group O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 230000029087 digestion Effects 0.000 description 2
- 230000008034 disappearance Effects 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 229910000532 Deoxidized steel Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 239000012237 artificial material Substances 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012966 insertion method Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 239000011295 pitch Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
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- Continuous Casting (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は溶鋼の鋳造に際して使用するストッパー、ロングストッパーを含むスライディングノズル、上ノズル、下ノズル、中間ノズル、浸漬ノズル等の連続鋳造用ノズルに用いられるアルミナ付着を防止する耐火物に関する。
【０００２】
【従来の技術】
近年、とくに薄板等の高級鋼として鋳造されるアルミニウムで脱酸された鋼、いわゆるアルミキルド鋼の鋼材品質の厳格化に伴い、連続鋳造においてタンディッシュからモールドに注入するために使用されるノズルへのアルミナ付着の防止に多くの努力が払われている。
【０００３】
ノズルに付着したアルミナは合体して、それが溶鋼流に大型の介在物として取り込まれて鋳片の欠陥となり品質を低下させることになる。
【０００４】
その対策の一例として、ノズルの内面からアルゴンガスを溶鋼中に吹き込んで物理的にアルミナの付着を防止する手法がある。しかしながら、この手法はアルゴンガスの吹き込み量が多すぎると気泡が鋳片内に取り込まれて鋳片中のピンホールとなる。従って、鋳片中の欠陥の発生を防止するために、ガスの吹き込み量を制限しなければならず、この手法はアルミナの付着を防止ための十分な対策とはなり得ない。
【０００５】
また、その他の対策の例として、連続鋳造において使用されるノズル等を構成する耐火材にＣａＯを含有させてアルミナ付着防止機能を持たせ、耐火材中のＣａＯとノズルに付着したアルミナとを反応させて低融物を生成してアルミナの付着を低減させる手法も知られている。例えば、特許文献１には、この手法を発展させた形態として、アルミナ付着防止機能と耐熱衝撃性を高めたドロマイトクリンカーと黒鉛とを炭化されたマトリックス組織で結合した耐火材を適用したノズルが開示されている。
【０００６】
しかしながら、このノズルはそれ自体は、優れたアルミナ付着防止機能を有する反面、予熱条件によっては表面が酸化して炭素が消失し、そこに発生した窪みにメタルが沈積し、その上にアルミナが付着してしまい、折角のドロマイトクリンカーによるアルミナ付着防止能が失われてしまう。
【０００７】
この予熱時の酸化による表面炭素の消失は、酸化防止材として、溶融してガラス被膜を形成するガラスフリットを含有する粉末を、ノズル表面に塗布することが効果的であるといえる。
【０００８】
ところが、ノズルにＣａＯを多量に含有する耐火材を使用する場合、耐火材中のＣａＯが、溶融した酸化防止材中に拡散してガラス被膜の粘性を低下させ、このため、被膜が破れたり、ノズルに吸収されたりして酸化防止機能が十分発揮されない場合がある。この様な現象は、予熱温度が高い場合や予熱時間が長い場合にとくに生じ易い。とくに、連続鋳造ノズルに適用されているＣａＯ−ＭｇＯ系クリンカー、すなわち、ドロマー黒鉛系耐火物は、前記特許文献１に記載のように、黒鉛の含有量が３８重量％以上と多い割には、使用しているドロマの粒度は比較的大きいものが使用されている。そのため、黒鉛間に存在するドロマ粒子の数が少なくなり、黒鉛同志が重なり合って大きな固まりとして存在する割合が多くなる。この黒鉛同志が重なり合った大きな固まりは、予熱時に酸化されると黒鉛の消失によって大きな窪みが多数発生し、そこにメタルが侵入して固着し易くなる。メタルが固着すると、付着したアルミナへの耐火材からのＣａＯの拡散が妨げられるのでアルミナが堆積することになる。
【０００９】
【特許文献１】
特表平１１−５０６３９３号公報
【００１０】
【発明が解決しようとする課題】
本発明の課題は、黒鉛およびＣａＯ−ＭｇＯ系クリンカーを主成分とする連続鋳造用耐火物において、予熱時に黒鉛が酸化消失した場合のアルミナ付着防止効果の低減を防止することにある。
【００１１】
【課題を解決するための手段】
本発明は、ＣａＯ含有系耐火物を使用したノズルの場合、このように、酸化防止材によって予熱時の酸化を完全に防止することは困難であり、耐火物自身にも黒鉛の消失を前提とした対策を取っておくことが、長期間の安定鋳造に寄与するという認識の下で完成した。
【００１２】
すなわち、本発明は、ＣａＯ−ＭｇＯ系クリンカーおよび黒鉛を主成分とする耐火物において、クリンカーの平均粒度を黒鉛の含有量に合わせて制御するもので、耐火物中の黒鉛の含有量をａ（質量％）、ＣａＯ−ＭｇＯ系クリンカーの平均粒度をｂ（ｍｍ）とした場合に、前記ａとｂとの関係が下記（１）式を満足することを特徴とする。
【００１３】
ｂ≦−０．０２×ａ＋０．８ （１）
本発明は、黒鉛およびＣａＯ−ＭｇＯ系クリンカーを主成分とする耐火物において、予熱によって黒鉛が消失した際に生成する窪みを小さくするには、黒鉛の分散を良くして重なりを防正することが重要であり、そのためには黒鉛と黒鉛の間にクリンカーを配置させなければならない。 従って、黒鉛の含有量が増えるに従って、クリンカーの個数を増加させる必要があり、（１）式のように黒鉛の含有量の増加に対してクリンカーの平均粒度を制御することで、必要なクリンカーの粒子個数を確保したものである。 これによって、黒鉛間にクリンカーを配置して黒鉛の重なりを抑制し、黒鉛の酸化消失により発生する窪みを小さくすることができる。
【００１４】
本発明において、ＣａＯ−ＭｇＯ系クリンカーとしては、天然ドロマイトを出発原料とした焼結ドロマイトクリンカー、電融ドロマイトクリンカーの他に、人工原料によってＣａＯとＭｇＯの比率を任意に変更したＣａＯ−ＭｇＯクリンカーなどが使用可能である。また、ＣａＯ−ＭｇＯ系クリンカーの一部をＭｇＯ系クリンカーやＣａＯ系クリンカーに置き換えることも可能である。さらには、ＺｒＯ２系クリンカーとも置換可能である。しかしながら、Ａｌ２Ｏ３系やＳｉＯ２系のクリンカーはＣａＯと反応して低融物を生成するため、２０質量％以上の置換は好ましくない。
【００１５】
ＣａＯ−ＭｇＯ系クリンカーを、各種クリンカーと置換した場合は、（１）式のクリンカーの粒度は全クリンカーの平均粒度となる。
【００１６】
黒鉛としては、鱗片状の天然黒鉛の他に、人造黒鉛、膨張黒鉛等各種黒鉛を使用することが可能である。ただし、予熱時の酸化による窪みを小さくするため、例えば、粒度０．５ｍｍを越える黒鉛の使用は少ない方が好ましい。もし、多量に使用する場合は混合中にミキサーによって粉砕する必要がある。
【００１７】
本発明に係る連続鋳造用耐火物は、一般的な黒鉛含有の連続鋳造用耐火物の製法に準じて製造されるが、Ｃａ〇−ＭｇＯ系クリンカーの平均粒度が小さくなるにつれてクリンカーの消化（水和）が発生しやすくなるため、低湿度下で製造するか、クリンカーの表面に消化防止処理を施すことが好ましい。処理の例としては、クリンカー表面のＣａＯをＣａＣＯ３とする方法、シリコーン樹脂、ピッチ、硫酸マグネシウムなどで粒子全体を被覆する方法などがある。出発原料の混練に際しては、本発明の場合黒鉛の分散性が非常に重要なので、その点を考慮したミキサーの選定、混練条件の設定が必要である。
【００１８】
本発明の耐火物はノズル全体に適用しても良いが、アルミナ付着が問題となるのは溶鋼と接触する面であり、溶鋼と接触する面にのみ適用することも可能である。とくに、カーボン量が少ない場合は耐スポール性が低下するためノズル全体ではなく、内孔面に数ｍｍから１０数ｍｍ内張りするか、厚さ数ｍｍから１０数ｍｍのスリーブ状の耐火物を内挿する方法がより好ましい。
【００１９】
【発明の実施の形態】
本発明の実施の形態を実施例によって説明する。
【００２０】
実施例１
表１は、ＣａＯ５７質量％、ＭｇＯ４２質量％の化学成分を有するＣａＯ−ＭｇＯ系クリンカーと純度９５％の黒鉛の粒度構成の配合割合の例を示す。 同表においては、本発明の規定範囲のものを実施例１〜１１として挙げ、規定範囲外の例として比較例１〜１０として挙げている。同表に示す配合割合で秤量し、これに適量のフェノールレジンを添加してミキサーによって均一に混練して配土を得た。得られた配土をゴム型に充填し、成形圧１０００ｋｇ／ｃｍ２でＣＩＰにて成形し、最高１０００℃で還元焼成してサンプルを作製した。
【００２１】
このサンプルから、２０ｍｍ×２０ｍｍ×１７０ｍｍの試験片を切り出し、予熱時の酸化を想定して、大気中にて１２００℃で３０分熱処理を行い、試験片の表面に酸化層を形成させた。
【００２２】
高周波炉にアルミキルド鋼を１５７０℃で溶解し、溶解後アルミニウムを０．２質量％添加した溶鋼に試験片を浸漬させ１２０分後に引き上げて試験片の外観を観察し、表面へのアルミナ付着の有無を調査した結果を表１に示す。
【００２３】
【表１】
【００２４】
すなわち、黒鉛およびＣａＯ−ＭｇＯ系クリンカーを主成分とする耐火物において、耐火物中の黒鉛の含有量をａ（質量％）、ＣａＯ−ＭｇＯ系クリンカーの平均粒度をｂ（ｍｍ）としたとき、アルミナ付着を防止する連続鋳造用耐火物としては、下記（１）式を満足することが必要であることが分かる。
【００２５】
ｂ≦−０．０２×ａ＋０．８ （１）
実施例２
表１に示す実施例７と比較例７の耐火物をそれぞれ内孔に厚さ７ｍｍで配置した浸漬ノズルを作製した。これらのノズルを、最高温度１３００℃で５時間予熱したのち、鍋容量２５０ｔｏｎ、ＴＤ容量４５ｔｏｎのスラブ鋳造機による鋳造に使用した。鋳造した結果、実施例７を内張りしたノズルは１０チャージ鋳造後もアルミナの付着は皆無であった。また、鋳片の品質も良好であった。これに対して比較例７を内張りしたノズルは６チャージ目鋳造中にアルミナ付着によるノズル内孔の閉塞によりノズル交換が必要となった。回収したノズルの稼働面を調査した結果、消失した黒鉛によって生成した窪みにメタルが固着し、その上にアルミナが堆積していた。また、得られた鋳片の品質も不良であつた。
【００２６】
【発明の効果】
本発明の耐火物を使用した連続鋳造用ノズルを使用することによって、予熱時の酸化の有無に関わらず優れたアルミナ付着防止効果を発揮することができる。したがって、鋳造の安定化による鋳造コスト低減、鋳片品質の改善による品質不良率低減につながる。
【図面の簡単な説明】
【図１】アルミナ付着の有無への黒鉛の含有量とクリンカーの平均粒度の影響を示す。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a refractory for preventing the adhesion of alumina used in continuous casting nozzles such as a stopper used for casting molten steel, a sliding nozzle including a long stopper, an upper nozzle, a lower nozzle, an intermediate nozzle, and an immersion nozzle.
[0002]
[Prior art]
In recent years, along with stricter steel quality of aluminum deoxidized steel, so-called aluminum killed steel, which is cast as a high-grade steel such as a thin plate, the nozzle used to inject from the tundish into the mold in continuous casting Many efforts have been made to prevent alumina deposition.
[0003]
Alumina adhering to the nozzle coalesces and is taken into the molten steel stream as large inclusions, resulting in slab defects and deteriorating quality.
[0004]
As an example of the countermeasure, there is a method of physically preventing adhesion of alumina by blowing argon gas into molten steel from the inner surface of the nozzle. However, in this method, if the amount of argon gas blown is too large, bubbles are taken into the slab and become pinholes in the slab. Therefore, in order to prevent the occurrence of defects in the slab, the amount of gas to be blown must be limited, and this method cannot be a sufficient measure for preventing the adhesion of alumina.
[0005]
As another example of countermeasures, a refractory material constituting a nozzle or the like used in continuous casting contains CaO to have an alumina adhesion preventing function, and reacts CaO in the refractory material with alumina adhered to the nozzle. There is also known a method of forming a low melt to reduce the adhesion of alumina. For example, Patent Literature 1 discloses, as a form developed from this method, a nozzle using a refractory material in which dolomite clinker having improved adhesion prevention function against alumina and thermal shock resistance and graphite are combined in a carbonized matrix structure. Have been.
[0006]
However, this nozzle itself has an excellent alumina adhesion prevention function, but depending on the preheating conditions, the surface oxidizes and carbon disappears, and metal deposits in the pit created there, and alumina adheres on it As a result, the ability of the dolomite clinker to prevent adhesion to alumina is lost.
[0007]
It can be said that it is effective to apply a powder containing a glass frit that melts to form a glass coating as an antioxidant to the nozzle surface to eliminate surface carbon due to oxidation during preheating.
[0008]
However, when a refractory material containing a large amount of CaO is used for the nozzle, CaO in the refractory material diffuses into the molten antioxidant material to lower the viscosity of the glass coating, thereby breaking the coating, In some cases, the antioxidant function is not sufficiently exhibited due to absorption by the nozzle. Such a phenomenon tends to occur particularly when the preheating temperature is high or the preheating time is long. In particular, the CaO-MgO-based clinker applied to the continuous casting nozzle, that is, the dolomer graphite-based refractory, as described in Patent Document 1, has a graphite content of as much as 38% by weight or more. The size of the doloma used is relatively large. For this reason, the number of doloma particles existing between graphites decreases, and the ratio of graphites overlapping each other and existing as a large mass increases. When the large lump formed by overlapping graphite is oxidized at the time of preheating, a large number of large depressions are generated due to the disappearance of the graphite, and the metal easily penetrates and adheres thereto. If the metal adheres, diffusion of CaO from the refractory material to the attached alumina is prevented, so that alumina is deposited.
[0009]
[Patent Document 1]
Japanese Patent Publication No. 11-506393
[Problems to be solved by the invention]
An object of the present invention is to prevent a refractory for continuous casting containing graphite and a CaO-MgO-based clinker as main components from preventing a reduction in an effect of preventing alumina from adhering when graphite is oxidized and lost during preheating.
[0011]
[Means for Solving the Problems]
The present invention is based on the premise that in the case of a nozzle using a CaO-containing refractory, it is difficult to completely prevent oxidation during preheating with an antioxidant, and the refractory itself also loses graphite. It was completed with the recognition that the measures taken would contribute to long-term stable casting.
[0012]
That is, the present invention controls the average particle size of the clinker in accordance with the graphite content in the refractory containing CaO-MgO-based clinker and graphite as main components, and adjusts the graphite content in the refractory to a ( Mass%), and the relationship between a and b satisfies the following formula (1) when the average particle size of the CaO—MgO-based clinker is b (mm).
[0013]
b ≦ −0.02 × a + 0.8 (1)
In the present invention, in a refractory containing graphite and CaO-MgO clinker as main components, in order to reduce a dent generated when graphite disappears due to preheating, it is necessary to improve the dispersion of graphite and prevent overlapping. Is important, for which a clinker must be placed between the graphites. Therefore, it is necessary to increase the number of clinkers as the graphite content increases. By controlling the average particle size of the clinker with respect to the increase in the graphite content as shown in the equation (1), the required clinker can be reduced. The number of particles was secured. Thereby, the clinker is arranged between the graphites to suppress the overlapping of the graphites, and it is possible to reduce the depression generated by the oxidized disappearance of the graphites.
[0014]
In the present invention, as the CaO-MgO clinker, in addition to sintered dolomite clinker using natural dolomite as a starting material, electrofused dolomite clinker, CaO-MgO clinker in which the ratio of CaO to MgO is arbitrarily changed by an artificial material, and the like. Can be used. It is also possible to replace a part of the CaO-MgO clinker with an MgO clinker or a CaO clinker. Furthermore, it can be replaced with a ZrO2-based clinker. However, since Al2O3 or SiO2 clinker reacts with CaO to generate a low melt, substitution of 20% by mass or more is not preferable.
[0015]
When the CaO-MgO-based clinker is replaced with various clinkers, the particle size of the clinker in the formula (1) is the average particle size of all clinkers.
[0016]
As the graphite, various graphites such as artificial graphite and expanded graphite can be used in addition to scaly natural graphite. However, in order to reduce the depression caused by oxidation during preheating, it is preferable to use less graphite, for example, having a particle size of more than 0.5 mm. If a large amount is used, it is necessary to pulverize with a mixer during mixing.
[0017]
The refractory for continuous casting according to the present invention is manufactured according to a general method for producing a refractory for continuous casting containing graphite. However, as the average particle size of the Ca〇-MgO-based clinker decreases, digestion of clinker (water Therefore, it is preferable to manufacture under low humidity or to perform a digestion preventing treatment on the surface of the clinker. Examples of the treatment include a method of converting CaO on the clinker surface to CaCO 3, a method of coating the entire particles with a silicone resin, pitch, magnesium sulfate, or the like. In kneading the starting materials, the dispersibility of graphite is very important in the present invention, so it is necessary to select a mixer and set the kneading conditions in consideration of this point.
[0018]
The refractory of the present invention may be applied to the entire nozzle, but it is possible to apply alumina only to the surface that comes into contact with the molten steel, where the adhesion of alumina becomes a problem. In particular, when the amount of carbon is small, the spall resistance decreases, so the inner nozzle surface is lined with several mm to several tens of mm or a sleeve-like refractory with a thickness of several mm to several tens mm instead of the entire nozzle. The insertion method is more preferable.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described with reference to examples.
[0020]
Example 1
Table 1 shows an example of the mixture ratio of the particle sizes of a CaO-MgO-based clinker having a chemical component of 57% by mass of CaO and 42% by mass of MgO and graphite having a purity of 95%. In the same table, those in the specified range of the present invention are listed as Examples 1 to 11, and examples outside the specified range are Comparative Examples 1 to 10. The mixture was weighed at the mixing ratio shown in the same table, an appropriate amount of phenol resin was added thereto, and the mixture was uniformly kneaded with a mixer to obtain earth distribution. The obtained soil was filled in a rubber mold, molded by CIP at a molding pressure of 1000 kg / cm 2 , and reduced and fired at a maximum of 1000 ° C. to produce a sample.
[0021]
From this sample, a test piece of 20 mm × 20 mm × 170 mm was cut out and subjected to a heat treatment at 1200 ° C. for 30 minutes in the air, assuming oxidation during preheating, to form an oxide layer on the surface of the test piece.
[0022]
Aluminum killed steel was melted in a high-frequency furnace at 1570 ° C, and after melting, the test piece was immersed in molten steel containing 0.2% by mass of aluminum. After 120 minutes, the test piece was lifted and the appearance of the test piece was observed. Are shown in Table 1.
[0023]
[Table 1]
[0024]
That is, in a refractory containing graphite and CaO—MgO clinker as main components, when the content of graphite in the refractory is a (mass%) and the average particle size of the CaO—MgO clinker is b (mm), It can be seen that it is necessary for the refractory for continuous casting that prevents the adhesion of alumina to satisfy the following expression (1).
[0025]
b ≦ −0.02 × a + 0.8 (1)
Example 2
An immersion nozzle was prepared in which the refractories of Example 7 and Comparative Example 7 shown in Table 1 were each disposed in an inner hole with a thickness of 7 mm. After preheating at a maximum temperature of 1300 ° C. for 5 hours, these nozzles were used for casting with a slab casting machine having a pot capacity of 250 tons and a TD capacity of 45 tons. As a result of casting, the nozzle lined with Example 7 showed no adhesion of alumina even after 10-charge casting. The quality of the cast slab was also good. On the other hand, the nozzle lined with Comparative Example 7 required replacement of the nozzle due to the blockage of the nozzle hole due to the adhesion of alumina during the sixth charge casting. Investigation of the working surface of the recovered nozzle revealed that metal had adhered to the cavities created by the disappeared graphite, and alumina had deposited on it. Moreover, the quality of the obtained slab was also poor.
[0026]
【The invention's effect】
By using the nozzle for continuous casting using the refractory of the present invention, an excellent effect of preventing alumina adhesion can be exhibited regardless of the presence or absence of oxidation during preheating. Therefore, the casting cost is reduced by stabilizing the casting, and the quality defect rate is reduced by improving the slab quality.
[Brief description of the drawings]
FIG. 1 shows the influence of the graphite content and the average particle size of clinker on the presence or absence of alumina attachment.
Claims (1)
耐火物中の黒鉛の含有量をａ（質量％）、ＣａＯ−ＭｇＯ系クリンカーの平均粒度をｂ（ｍｍ）とした場合、下記（１）式を満したアルミナ付着を防止するための連続鋳造用耐火物。
ｂ≦−０．０２×ａ＋０．８ （１）In a refractory for continuous casting which prevents the adhesion of alumina mainly composed of graphite and CaO-MgO clinker,
When the content of graphite in the refractory is a (mass%) and the average particle size of the CaO-MgO-based clinker is b (mm), it is used for continuous casting for preventing the adhesion of alumina satisfying the following expression (1). Refractory.
b ≦ −0.02 × a + 0.8 (1)
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| JP2003117580A JP4960574B2 (en) | 2003-04-22 | 2003-04-22 | Refractory used for continuous casting nozzles to prevent alumina adhesion |
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| JP2003117580A JP4960574B2 (en) | 2003-04-22 | 2003-04-22 | Refractory used for continuous casting nozzles to prevent alumina adhesion |
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| JP4960574B2 JP4960574B2 (en) | 2012-06-27 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005060128A (en) * | 2003-08-19 | 2005-03-10 | Nippon Steel Corp | Refractory |
| JP2008000809A (en) * | 2006-06-26 | 2008-01-10 | Nisshin Steel Co Ltd | Stopper control type dipping nozzle |
| JP2010167481A (en) * | 2009-01-26 | 2010-08-05 | Kurosaki Harima Corp | Nozzle for continuous casting |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02180753A (en) * | 1988-12-28 | 1990-07-13 | Harima Ceramic Co Ltd | Production of immersion nozzle for continuous casting |
| JPH1177257A (en) * | 1997-09-05 | 1999-03-23 | Shinagawa Refract Co Ltd | Immersion nozzle for continuos casting |
-
2003
- 2003-04-22 JP JP2003117580A patent/JP4960574B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02180753A (en) * | 1988-12-28 | 1990-07-13 | Harima Ceramic Co Ltd | Production of immersion nozzle for continuous casting |
| JPH1177257A (en) * | 1997-09-05 | 1999-03-23 | Shinagawa Refract Co Ltd | Immersion nozzle for continuos casting |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005060128A (en) * | 2003-08-19 | 2005-03-10 | Nippon Steel Corp | Refractory |
| JP4580155B2 (en) * | 2003-08-19 | 2010-11-10 | 新日本製鐵株式会社 | Continuous casting nozzle |
| JP2008000809A (en) * | 2006-06-26 | 2008-01-10 | Nisshin Steel Co Ltd | Stopper control type dipping nozzle |
| JP4519109B2 (en) * | 2006-06-26 | 2010-08-04 | 日新製鋼株式会社 | Stopper control type immersion nozzle |
| JP2010167481A (en) * | 2009-01-26 | 2010-08-05 | Kurosaki Harima Corp | Nozzle for continuous casting |
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| JP4960574B2 (en) | 2012-06-27 |
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