JPH0428672B2 - - Google Patents
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- Publication number
- JPH0428672B2 JPH0428672B2 JP17356883A JP17356883A JPH0428672B2 JP H0428672 B2 JPH0428672 B2 JP H0428672B2 JP 17356883 A JP17356883 A JP 17356883A JP 17356883 A JP17356883 A JP 17356883A JP H0428672 B2 JPH0428672 B2 JP H0428672B2
- Authority
- JP
- Japan
- Prior art keywords
- mgo
- particle size
- corrosion resistance
- refractory material
- spherical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 239000002245 particle Substances 0.000 claims description 29
- 239000011819 refractory material Substances 0.000 claims description 26
- 239000000843 powder Substances 0.000 claims description 17
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 11
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 9
- 229910006501 ZrSiO Inorganic materials 0.000 claims description 9
- 239000011159 matrix material Substances 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 5
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 47
- 230000007797 corrosion Effects 0.000 description 27
- 238000005260 corrosion Methods 0.000 description 27
- 239000000395 magnesium oxide Substances 0.000 description 24
- 229910000831 Steel Inorganic materials 0.000 description 17
- 230000035939 shock Effects 0.000 description 17
- 239000010959 steel Substances 0.000 description 17
- 230000035699 permeability Effects 0.000 description 13
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 12
- 239000012798 spherical particle Substances 0.000 description 8
- 239000011651 chromium Substances 0.000 description 7
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 230000000704 physical effect Effects 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 238000010304 firing Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 238000002844 melting Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 230000035515 penetration Effects 0.000 description 5
- 229910052596 spinel Inorganic materials 0.000 description 5
- 239000011029 spinel Substances 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000003628 erosive effect Effects 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000007664 blowing Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000004927 clay Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 229910000423 chromium oxide Inorganic materials 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 238000005188 flotation Methods 0.000 description 2
- 229910052839 forsterite Inorganic materials 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000002699 waste material Substances 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
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- 241001131796 Botaurus stellaris Species 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 230000003542 behavioural effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- UAMZXLIURMNTHD-UHFFFAOYSA-N dialuminum;magnesium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[Mg+2].[Al+3].[Al+3] UAMZXLIURMNTHD-UHFFFAOYSA-N 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000009970 fire resistant effect Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
Landscapes
- Continuous Casting (AREA)
- Porous Artificial Stone Or Porous Ceramic Products (AREA)
Description
［産業上の利用分野］
本発明は、溶融金属たとえば溶鋼の撹拌又は溶
融中の介在物の浮上分離を目的として、不活性ガ
スを吹込むために取鍋、タンデイツシユ等の溶融
金属容器に装置されるポーラスプラグに係るもの
である。
［背景技術］
現在、製綱プロセスにおいて鋼の品質、耐食性
又は加工性等の品質向上を図るために、耐火物を
通して溶鋼中にガスを吹込む工程が汎用されてい
る。この手段は、ガス吹込により溶鋼を撹拌し溶
鋼温度を均斉化するとか、或いは微細気泡のバブ
リングにより非金属介在物を浮上分離させること
により鋼の品質向上を達成せんとするものであつ
て、この目的に用いられるガス吹込用耐火物は一
般にポーラスプラグと称されるもので、その具備
すべき特性は、
(1) 通気性を有していること
(2) 耐食性に優れていること
(3) 熱衝撃抵抗性が大なること
が不可欠である。
これらのうち、通気性はポーラスプラグの機能
を左右する最も重要な特性である。しかも通気性
は、溶鋼撹拌による温度の均一化及び介在物の浮
上分離の目的により或いは使用条件によつても異
なつた通気性が要請され、従つて通気性のコント
ロールは重要な技術である。
耐食性は大別して次の三点を考慮する必要があ
る。先づ第１に溶鋼そのものに対する耐食性であ
る。第２は酸素ガスに対する耐食性であり、酸素
ガスは付着した地金を除去する（いわゆる酸素洗
浄）のに使用され、使用時には約2000℃の高温に
なるので耐食性に富み耐火度の高いものでなけれ
ばならない。第３はFeOに対する耐食性であつ
て、近年酸素濃度の高い特殊鋼が製造されるよう
になり従来のアルミナ質ポーラスプラグではFeO
とAl2O3との反応で低融点物であるFeO−Al2O3
スピネルが生成し、耐食性の低下が認められるの
でこのような現象を防ぐ必要がある。
熱衝撃抵抗性については、特に上記のような特
殊鋼の溶鋼に対してはマグネシアーアルミナスピ
ネル質又はマグネシア質耐火物のような塩基性材
質が優れた耐食性を示すことが知られているが、
この材質は膨張率が高いために熱衝撃抵抗性に劣
ることが欠点となつており、さらに鋼の浸透によ
り浸透層と原質層との境界部において、構造的ス
ポールを生じ易いことも問題となり、安定使用の
面からポーラスプラグに塩基性材質を適用した例
はみられない。
［解決しようとする問題点］
本発明は斯かる現況に鑑がみなされたもので、
MgOを不可欠成分とするアルミナ−マグネシア
スピネル質球状粒子及びマグネシア質球状粒子を
耐火材料として用いることにより、所要の通気性
並びに組織の均一化を得ると共に、酸素濃度の高
い溶鋼に対して卓越した耐食性を有し、さらに熱
衝撃抵抗性の大なるポーラスプラグの提供を目的
としている。
［問題点を解決するための手段］
以下本発明の構成について説明する。先づ本発
明のポーラスプラグに用いる耐火材料は、マグネ
シアーアルミナスピネル質球状耐火材料及びマグ
ネシア質球状耐火材料であり、それらの化学成分
は塩基性材質としての特性を発現させるために
MgO10％（wt％、以下同じ）以上からなるもの
である。この理由はMgOが10％未満であるとア
ルミナ質ポーラスプラグの耐食性に比べて有利な
点が認められないからである。耐火材料として球
状粒子を用いることにより、
(1) 充填性が向上する、
(2) 均一な充填性のため均斉な組織の成形体が得
られる、
(3) 物性（気孔率、通気率、強度等）のコントロ
ールが容易である。
等の利点がもたらされる。特に市販されているも
のか又は粉砕して得られる非球形粒子に比べて、
球状粒子を用いた成形体の最大の利点は、気孔率
を低くして、すなわち密充填状態としながらポー
ラスプラグが具備すべき通気性が得られるところ
にある。
次に、上記球状耐火材料の最大粒径は２mm以下
のものを用いる。最大粒径が２mmを超すと、それ
以下の粒径のものとの粒度分布の影響もあるが、
総体的に細孔径が大きくなりすぎる傾向がある。
このような傾向のもとでは通気率のコントロール
としての微粉添加が必要以上に大量となり、上記
球状耐火材料を用いる効果が減殺される。その
上、粒径を大きくすると加工性が劣化し、各種の
形状のポーラスプラグに加工する場合に内部組織
の均斉化を阻害したり又は表層外観が見劣りする
こともある。従つて粒径は２mm以下、中でも1.5
mm以下とするのが好ましい。
さらに、焼結促進及び物性コントロール用とし
て平均粒径100μ以下のマトリツクス用微粉アル
ミナ又は微粉マグネシアを添加し、同時に熱衝撃
抵抗性の向上及び溶融金属の浸透防止若しくは構
造スポール防止のために、ZrSiO4，SiO2，ZrO2，
Cr2O3の１種又は２種以上を添加するものであ
る。
ZrSiO4，SiO2はMgO又はMgO−Al2O3の球状
耐火材料又は添加したマトリツクス用微粉マグネ
シアとの反応で、低融点物のフオルステライトを
生成する。その生成量をコントロールすることに
よつて、耐食性を劣化させることなく、熱衝撃抵
抗性を向上させることができる。又、ZrSiO4，
SiO2はAl2O3との反応によりムライトを生成し、
同じく熱衝撃抵抗性を向上させることができる。
ZrO2の添加は、このものがMgO又はAl2O3と容
易に固溶体を形成して成形体の強度を向上させ、
結果的には熱衝撃抵抗性を高めると共に溶鋼に対
するZrO2の挙動特性により耐食性も向上する。
Cr2O3添加の主目的は浸透防止である。これは溶
鋼に対するCr2O3の濡れ性が悪いことに基づくも
のであるが、Cr2O3は焼結を阻害する作用がある
ので、たとえばSiO2，ZrSiO4との併用が望まし
い。
上記したマトリツクス用微粉アルミナ又は微粉
マグネシア等の耐火性微粉の平均粒子径を100μ
以下としたのは、球状粒子との反応性を高めるた
めであり、100μを超えるとポーラスプラグとし
ての粒子間強度が不充分になるからである。
以上の諸要素に基づく本発明のポーラスプラグ
の種々の具体例について説明する。
本発明のポーラスプラグに用いる球状耐火材料
は、市販又は粉砕して得られる平均粒子径100μ
以下のマグネシア及びアルミナ粉末を予め設定さ
れた割合で混合し、パルプ廃液又は苦汁等をバイ
ンダーとして回転皿型造粒機、スプレードライヤ
ー、回転ミキサー等を用いて球状に造粒し、1700
〜2000℃で焼成して得られるものである。焼成さ
れた球状耐火材料は篩分けし、所定の物性が得ら
れるように粒度調整する。粒度分布は熱衝撃抵抗
性の面から、一定粒度のもののみの整流よりも粒
度巾の大きい不連続又は連続粒度分布であること
が望ましい。
粒度調整された球状耐火材料に、マトリツクス
用微粉アルミナ又は微粉マグネシアを配合し、さ
らにZrSiO4，SiO2，Cr2O3，ZrO2の１種又は２
種以上を添加し、フエノール樹脂等のバインダー
を用いてフレツトミルで混練し、その後成形、乾
燥、焼成することによつてポーラスプラグが得ら
れるのである。
具体的実験例を挙げて本発明を詳細に説明す
る。
実験例第１群
先づ、現用されている従来のポーラスプラグの
耐火材料と本発明に用いる球状耐火材料とを用い
た成形体の耐食性を比較検討できる具体例を挙げ
る。
市販の平均粒子径22μの微粉アルミナと、市販
の焼結マグネシアを粉砕して平均粒子径35μとし
たマトリツクス用微粉マグネシアとを、第１表に
示されている球状耐火材料の化学組成となるよう
な割合で混合し、パルプ廃液を用いて転動造粒し
て球状粒子を得た。そして、この粒子を1800℃の
トンネルキルンで焼成し必要強度を具備せしめ本
発明に用いられる球状耐火材料とした。
このようにして得られた球状耐火材料を、第１
表に示す粒度分布に調整し、且つ微粉マグネシア
を外掛け（球状耐火材料100重量％に対する重量
％。以下の各表中のカツコ内数値はすべて外掛け
で示す。）で10％添加し、フエノール樹脂を用い
てフレツトミルで混練した。混練坏土はフリクシ
ヨンプレスで成形し、乾燥後1730℃で焼成し、こ
のポーラスプラグについて物性値、耐食性等の特
性値の調査を行い第１表に併せ示した。
耐食性の試験は下記の条件による回転侵食法に
より行い、その評価は従来品である比較例No.１の
溶損量を100とする溶損指数で表し、数値の低い
ものほど耐食性に優れることを示す。
回転侵食法 温度：1650℃
時間：30分間浸漬の５回反復
鋼種：鉄100％
第１表から明らかなように、球状耐火材料とし
てAl2O3−MgO質及びMgO質のものは比較例No.
１より高耐食性を示しているが、逆に浸透量は大
きくなつている。これはMgOの融点が2800℃と
高く、又、膨張率が高いため、同一焼成温度では
焼結不足となつて気孔率、細孔率が大となり、そ
の結果浸透量が大きくなるものと考えられる。
なお、実験番号No.２の製品は、球状粒子が
MgO5％を含むもので、本願発明の構成に含まれ
ない参考例である。
実験例第２群
第２表に示す諸例は、実験例第１群と全く同様
にして調整した球状耐火材料を用い、同じく焼成
して得た成形体の物性・特性に関し、特に球状耐
火材料の最大粒径がどのような影響を及ぼすかを
調査したものである。
この実験例においても比較の基準は第１表にお
ける比較例No.１である。
第２表から、最大粒径を大きくすることによ
り、成形体の気孔率は小さくなり組織は緻密化す
る。又、それに応じて耐食性も向上し、浸透量も
小さくなつている。しかし、この最大粒径の示す
傾向も、加工性を加味して再検討すると、そのと
きは最大粒径は2.0mm以下、中でも1.5mm程度とな
すことが望ましい。何となれば最大粒径が大きく
なるに従つて、加工成形時に粒子が単体で剥離す
るための切削面の平滑度が低下するからであり、
成形体の強度が低いときにはこの状態は一層顕著
となる。
実験例第３群
第３表に示す諸例は、実験例第１群と全く同様
にして調整した球状耐火材料を用い、同じく焼成
して得た成形体の物性・特性に関し、特に成形体
組織のマトリツクスとなる微粉添加がどのような
影響を及ぼすかを調査したものである。No.14は現
在ポーラスプラグとして汎用されているアルミナ
質球状耐火材料を用いたもので比較例とした。
マトリツクス用微粉の、種別又は添加量等の添
加態様により、
No.15〜18及びNo.19〜22は通気性がどのようにコ
ントロールされるかの検討、
No.23〜26及びNo.27〜30は熱衝撃抵抗性の向上の
検討、
No.31〜35はさらに耐食性を向上させるべく
Cr2O3添加の検討、
No.36〜39及びNo.40は耐食性と熱衝撃抵抗性の両
方の向上につき検討したもの、
No.41〜43はCr2O3添加の有無による耐食性と熱
衝撃抵抗性の両方の向上を達成するにつき検討し
たもの、
の結果をそれぞれ示している。
第３表の実験例並びにそれらの結果よりみて、
通気性のコントロール用としての微粉添加量は、
実際に使用されているポーラスプラグの通気量が
約1.0（cc.cm／cm2．sec.cmH2O）以上であることを
考慮すれば、外掛けで約20％以下が望ましい。勿
論、球状耐火材料の最大径が大きくなるとその添
加所要量が増すが、約20％以下でよい。なお、通
気性のコントロールは上記微粉量以外に粒度分布
によつても可能であることはいうまでもない。
No.15〜18にみるように、耐食性は向上するが熱
衝撃抵抗性については比較例No.14に比べ劣つてい
るものは、添加微粉をNo.19〜22にみるようにアル
ミナにすれば、スピネルボンドの生成により強度
も僅かながら増し、熱衝撃抵抗性の向上が認めら
れるものの実際使用時の性能向上は充分に満足す
るには至つていない。
しかし、SiO2（粘土）を添加したNo.23〜26、ジ
ルコンを添加したNo.27〜30、ジルコニアを添加し
たNo.36〜40では熱衝撃抵抗性の向上が明白であ
る。この理由は以下のように考慮される。すなわ
ち、粘土、ジルコンの熱解離によつて生じた
SiO2はMgOと反応して底融点物のフオルステラ
イトを生成し組織を良化させて強度を発現し、
又、ジルコニアの場合にはMgOと固溶体を形成
するため強度が向上し、これらの結果、熱衝撃抵
抗性が向上するのである。しかし、SiO2及び
ZrSiO4の場合は添加量が多くなるにつれ耐食性
が劣化する傾向があつて、その添加量を限定する
必要があり、第３表の結果からみても望ましい範
囲はSiO2は１〜５％、ZrSiO4は１〜10％である。
また、ジルコニアは価格が高いので必要最小限
の使用量とするのが採算上有利である。
酸化クロムの添加は、このものが溶鋼に対する
濡れ性が悪く高耐食性をもたらす原料であるが、
焼結を阻害する傾向の方が強く影響してNo.31〜35
のように逆に耐食性は悪くなつている。しかしNo.
41にみるように他原料と併用することにより酸化
クロム添加の本来の効果を発揮させることができ
る。
本実験例における熱衝撃抵抗性の評価は、焼成
体から50×50×50mmのテストピースをつくりだ
し、1500℃の電気炉内に30分間保持した後取出し
空冷する。この操作を反復し、テストピース表面
の状態を観察し、
◎〜２回反復亀裂なし
〇〜１回後亀裂なし
△〜１回後微亀裂発生
×〜１回後大亀裂発生
で表わしたものである。
また、実験例第１群及び実験例第２群として第
１表並びに第２表に示すマグネシアーアルミナ質
球状耐火材料を用いた場合でも、通気率又は熱衝
撃抵抗性等同様な傾向・利点を有している。
[Industrial Field of Application] The present invention relates to a porous metal container installed in a molten metal container such as a ladle or tundish for the purpose of blowing inert gas into the molten metal container such as a ladle or tundish for the purpose of stirring molten metal such as molten steel or flotation separation of inclusions during melting. This relates to plugs. [Background Art] Currently, in order to improve the quality, corrosion resistance, workability, etc. of steel in the steel manufacturing process, a process of blowing gas into molten steel through a refractory is widely used. This method aims to improve the quality of steel by stirring the molten steel by blowing gas to equalize the molten steel temperature, or by floating and separating non-metallic inclusions by bubbling fine bubbles. The gas injection refractory used for this purpose is generally called a porous plug, and its characteristics are: (1) It must have air permeability (2) It must have excellent corrosion resistance (3) It is essential that the thermal shock resistance is high. Among these, air permeability is the most important property that affects the functionality of porous plugs. Moreover, different air permeability is required depending on the purpose of equalizing the temperature by stirring the molten steel and flotation separation of inclusions, or depending on the usage conditions, so controlling the air permeability is an important technique. Corrosion resistance can be broadly classified into the following three points. First of all, it has corrosion resistance against the molten steel itself. The second is corrosion resistance against oxygen gas. Oxygen gas is used to remove adhered metal (so-called oxygen cleaning), and the temperature during use reaches a high temperature of approximately 2000°C, so it must be highly corrosion resistant and fire resistant. Must be. The third factor is corrosion resistance against FeO.In recent years, special steels with high oxygen concentrations have been manufactured, and conventional alumina porous plugs have corrosion resistance against FeO.
FeO−Al 2 O 3, which is a low melting point substance, is produced by the reaction with Al 2 O 3
Since spinel is produced and corrosion resistance is decreased, it is necessary to prevent this phenomenon. Regarding thermal shock resistance, it is known that basic materials such as magnesia alumina spinel or magnesia refractories exhibit excellent corrosion resistance, especially for molten special steels such as those mentioned above.
The disadvantage of this material is that it has poor thermal shock resistance due to its high expansion coefficient, and another problem is that structural spalls are likely to occur at the boundary between the permeated layer and the primary layer due to penetration of the steel. However, from the standpoint of stable use, there have been no examples of using basic materials in porous plugs. [Problems to be Solved] The present invention was made in view of the current situation, and
By using alumina-magnesia spinel spherical particles and magnesia spherical particles containing MgO as an essential component as a refractory material, the required air permeability and uniform structure can be obtained, as well as excellent corrosion resistance against molten steel with a high oxygen concentration. The purpose of the present invention is to provide a porous plug that has a high resistance to thermal shock. [Means for Solving the Problems] The configuration of the present invention will be described below. First, the refractory materials used in the porous plug of the present invention are a magnesia-alumina-spinel spherical refractory material and a magnesia-based spherical refractory material.
It consists of 10% (wt%) or more of MgO (wt%, the same applies hereinafter). The reason for this is that if the MgO content is less than 10%, no advantages will be recognized compared to the corrosion resistance of alumina porous plugs. By using spherical particles as a refractory material, (1) the filling property is improved, (2) a molded product with a uniform structure can be obtained due to the uniform filling property, and (3) the physical properties (porosity, air permeability, strength) are improved. etc.) are easy to control. Benefits such as: Especially compared to non-spherical particles that are commercially available or obtained by grinding,
The greatest advantage of a molded article using spherical particles is that it has a low porosity, that is, it can achieve the air permeability that a porous plug should have while maintaining a tightly packed state. Next, the maximum particle size of the spherical refractory material used is 2 mm or less. If the maximum particle size exceeds 2 mm, there will be an influence on the particle size distribution with smaller particle sizes,
Overall, the pore size tends to become too large.
Under such a tendency, the amount of fine powder added to control the air permeability becomes larger than necessary, and the effect of using the spherical refractory material is diminished. Furthermore, when the particle size is increased, the processability deteriorates, and when processed into porous plugs of various shapes, the uniformity of the internal structure may be inhibited or the appearance of the surface layer may become poor. Therefore, the particle size is 2 mm or less, especially 1.5
It is preferable to set it to less than mm. Furthermore, fine alumina or magnesia powder for the matrix with an average particle size of 100μ or less is added to promote sintering and control physical properties, and at the same time ZrSiO 4 is added to improve thermal shock resistance and prevent penetration of molten metal or structural spalling. , SiO 2 , ZrO 2 ,
One or more types of Cr 2 O 3 are added. ZrSiO 4 and SiO 2 produce forsterite, a low melting point substance, by reaction with MgO or MgO-Al 2 O 3 spherical refractory material or added fine powder magnesia for matrix. By controlling the amount produced, thermal shock resistance can be improved without deteriorating corrosion resistance. Also, ZrSiO 4 ,
SiO 2 produces mullite by reaction with Al 2 O 3 ,
Similarly, thermal shock resistance can be improved.
The addition of ZrO 2 easily forms a solid solution with MgO or Al 2 O 3 to improve the strength of the molded product.
As a result, the thermal shock resistance is increased and the corrosion resistance is also improved due to the behavioral characteristics of ZrO 2 with respect to molten steel.
The main purpose of adding Cr 2 O 3 is to prevent penetration. This is due to the poor wettability of Cr 2 O 3 to molten steel, but since Cr 2 O 3 has the effect of inhibiting sintering, it is desirable to use it in combination with, for example, SiO 2 or ZrSiO 4 . The average particle diameter of the refractory fine powder such as fine alumina powder or fine powder magnesia powder for the matrix mentioned above is 100 μm.
The reason for the following is to increase the reactivity with spherical particles, and if it exceeds 100μ, the interparticle strength as a porous plug will be insufficient. Various specific examples of the porous plug of the present invention based on the above factors will be explained. The spherical refractory material used for the porous plug of the present invention has an average particle diameter of 100 μm, which can be obtained commercially or by pulverization.
The following magnesia and alumina powders are mixed in a preset ratio and granulated into spheres using a rotary plate granulator, spray dryer, rotary mixer, etc. using pulp waste liquid or bittern as a binder.
It is obtained by firing at ~2000℃. The fired spherical refractory material is sieved and the particle size is adjusted to obtain predetermined physical properties. From the viewpoint of thermal shock resistance, the particle size distribution is preferably a discontinuous or continuous particle size distribution with a larger particle size width than a rectified particle size distribution of only a fixed particle size. Finely powdered alumina or finely powdered magnesia for the matrix is blended into a spherical refractory material whose particle size has been adjusted, and one or two of ZrSiO 4 , SiO 2 , Cr 2 O 3 , and ZrO 2 are added.
A porous plug is obtained by adding at least one seed, kneading it in a fret mill using a binder such as a phenolic resin, and then molding, drying, and firing. The present invention will be explained in detail by giving specific experimental examples. Experimental Example Group 1 First, a specific example will be given in which the corrosion resistance of a molded article using a conventional porous plug refractory material currently in use and a spherical refractory material used in the present invention can be compared. Commercially available fine powder alumina with an average particle size of 22 μm and commercially available sintered magnesia powdered by pulverizing fine powder magnesia for matrix with an average particle size of 35 μm were mixed so that the chemical composition of the spherical refractory material shown in Table 1 was obtained. The mixture was mixed in a suitable ratio and granulated by rolling using pulp waste liquid to obtain spherical particles. The particles were then fired in a tunnel kiln at 1800°C to provide the necessary strength and to form the spherical refractory material used in the present invention. The spherical refractory material thus obtained was
Adjust the particle size distribution as shown in the table, and add 10% of fine powder magnesia (weight% based on 100% by weight of the spherical refractory material. All figures in brackets in the tables below are expressed as external numbers), and add phenol. The resin was kneaded using a fret mill. The kneaded clay was molded using a friction press, dried and fired at 1730°C. The porous plugs were investigated for physical properties, corrosion resistance, and other characteristic values, which are also shown in Table 1. The corrosion resistance test was carried out by the rotary erosion method under the following conditions, and the evaluation was expressed as an erosion index, where the amount of erosion of Comparative Example No. 1, which is a conventional product, was set as 100. The lower the value, the better the corrosion resistance. show. Rotary erosion method Temperature: 1650°C Time: Repeated immersion 5 times for 30 minutes Steel type: 100% iron As is clear from Table 1, Al 2 O 3 -MgO and MgO spherical refractory materials are comparative example No. .
It shows higher corrosion resistance than No. 1, but on the contrary, the amount of penetration is larger. This is because MgO has a high melting point of 2800℃ and a high expansion rate, so at the same firing temperature, sintering is insufficient and the porosity and porosity become large, resulting in a large amount of permeation. . In addition, the product of experiment number No. 2 has spherical particles.
This is a reference example that contains 5% MgO and is not included in the structure of the present invention. Experimental Example Group 2 The examples shown in Table 2 use spherical refractory materials prepared in exactly the same manner as in Experimental Example Group 1, and are particularly concerned with the physical properties and characteristics of the molded bodies obtained by firing the spherical refractory materials. This study investigated the influence of the maximum particle size of In this experimental example as well, the standard of comparison is Comparative Example No. 1 in Table 1. From Table 2, by increasing the maximum particle size, the porosity of the compact becomes smaller and the structure becomes denser. Corrosion resistance is also improved accordingly, and the amount of penetration is also reduced. However, when this tendency of the maximum particle size is reexamined in consideration of workability, it is desirable that the maximum particle size is 2.0 mm or less, especially about 1.5 mm. This is because as the maximum particle size increases, the smoothness of the cut surface, which allows particles to separate individually during processing and forming, decreases.
This condition becomes even more noticeable when the strength of the molded body is low. Experimental Example Group 3 The examples shown in Table 3 use spherical refractory materials prepared in exactly the same manner as in Experimental Example Group 1, and are particularly concerned with the physical properties and characteristics of molded bodies obtained by firing in the same manner. This study investigated the effect of adding fine powder to the matrix. No. 14 uses an alumina spherical refractory material that is currently widely used as a porous plug, and was used as a comparative example. Nos. 15 to 18 and Nos. 19 to 22 are studies on how air permeability is controlled depending on the addition mode such as type or amount of fine powder for matrix, Nos. 23 to 26 and Nos. 27 to No. 30 is a study to improve thermal shock resistance, and No. 31 to 35 are studies to further improve corrosion resistance.
Study on the addition of Cr 2 O 3 , Nos. 36 to 39 and No. 40 are studies on improving both corrosion resistance and thermal shock resistance, and Nos. 41 to 43 are studies on corrosion resistance and heat with and without addition of Cr 2 O 3 The following are the results of studies conducted to improve both impact resistance and impact resistance. Based on the experimental examples in Table 3 and their results,
The amount of fine powder added to control air permeability is
Considering that the air permeability of the porous plugs actually used is about 1.0 (cc.cm/cm 2 .sec.cmH 2 O) or more, it is desirable that the air flow rate is about 20% or less for the outside. Of course, as the maximum diameter of the spherical refractory material increases, the amount required to be added increases, but it may be about 20% or less. It goes without saying that air permeability can be controlled not only by the amount of fine powder but also by particle size distribution. As shown in Nos. 15 to 18, the corrosion resistance is improved but the thermal shock resistance is inferior to Comparative Example No. 14, if the added fine powder is alumina as shown in Nos. 19 to 22. Although the strength increases slightly due to the formation of spinel bond and the thermal shock resistance is improved, the improvement in performance during actual use has not yet been fully satisfied. However, improvement in thermal shock resistance is evident in Nos. 23 to 26 with SiO 2 (clay) added, Nos. 27 to 30 with zircon added, and Nos. 36 to 40 with zirconia added. The reason for this is considered as follows. In other words, it is produced by thermal dissociation of clay and zircon.
SiO 2 reacts with MgO to produce forsterite, which is a bottom melting point substance, improving the structure and developing strength.
In addition, in the case of zirconia, strength is improved because it forms a solid solution with MgO, and as a result, thermal shock resistance is improved. However, SiO 2 and
In the case of ZrSiO 4 , the corrosion resistance tends to deteriorate as the amount added increases, so it is necessary to limit the amount added. Judging from the results in Table 3, the desirable range is 1 to 5% for SiO 2 and 1% to 5% for ZrSiO 4 . 4 is 1-10%. Furthermore, since zirconia is expensive, it is advantageous for profitability to use the minimum necessary amount. The addition of chromium oxide is a raw material that has poor wettability to molten steel and provides high corrosion resistance.
The tendency to inhibit sintering has a stronger influence on Nos. 31 to 35.
On the contrary, corrosion resistance is getting worse. But no.
41, the original effect of adding chromium oxide can be brought out by using it in combination with other raw materials. For evaluation of thermal shock resistance in this experimental example, a test piece of 50 x 50 x 50 mm was created from the fired body, held in an electric furnace at 1500°C for 30 minutes, and then taken out and cooled in the air. Repeat this operation and observe the condition of the test piece surface. ◎ ~ No crack after 2 repetitions ○ ~ No crack after 1 repetition △ ~ Slight crack after 1 repetition x ~ Large crack after 1 repetition be. Furthermore, even when the magnesia alumina spherical refractory materials shown in Tables 1 and 2 are used as the first experimental group and the second experimental group, similar trends and advantages such as air permeability and thermal shock resistance are obtained. have.
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】
以上の説明のように本発明のポーラスプラグ
は、従来のアルミナ質ポーラスプラグが逢着して
いた種々の問題点を解消して、今後の製鋼の操業
効率の改善に大きく寄与するもので、特許請求の
範囲に従うものであれば上記の各実験例に限定さ
れることはなく、それらから導かれる応用、転用
又は変形はすべて本発明の技術的範囲に包含され
るものであることはいうまでもない。[Table] As explained above, the porous plug of the present invention solves the various problems encountered with conventional alumina porous plugs, and will greatly contribute to improving the operational efficiency of steel manufacturing in the future. It should be noted that the present invention is not limited to the above-mentioned experimental examples as long as they comply with the scope of the claims, and any applications, diversions, or modifications derived therefrom are included within the technical scope of the present invention. Not even.
Claims (1)
MgO又はMgOとAl2O3とを主成分とする粒子径
が２mm以下の球状耐火材料に、マトリツクス用微
粉平均粒子径100μ以下のZrSiO4，SiO2，ZrO2，
Cr2O3，Al2O3，MgOのうちからAl2O3若しくは
MgOを含む１種又は２種以上を添加し成形・焼
成したことを特徴とするポーラスプラグ。1 Contains 10wt% or more of MgO as a chemical component
ZrSiO 4 , SiO 2 , ZrO 2 , ZrSiO 4 , SiO 2 , ZrO 2 with an average particle size of 100 μ or less, fine powder for matrix, and a spherical refractory material with a particle size of 2 mm or less containing MgO or MgO and Al 2 O 3 as main components.
Al 2 O 3 or MgO from Cr 2 O 3 , Al 2 O 3 , MgO
A porous plug characterized by being molded and fired with the addition of one or more types including MgO.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17356883A JPS6065778A (en) | 1983-09-19 | 1983-09-19 | Porous slag |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17356883A JPS6065778A (en) | 1983-09-19 | 1983-09-19 | Porous slag |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6065778A JPS6065778A (en) | 1985-04-15 |
| JPH0428672B2 true JPH0428672B2 (en) | 1992-05-14 |
Family
ID=15962966
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17356883A Granted JPS6065778A (en) | 1983-09-19 | 1983-09-19 | Porous slag |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6065778A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0742161B2 (en) * | 1986-08-26 | 1995-05-10 | 川崎炉材株式会社 | Manufacturing method of magnesia porous plug |
| JPH01320277A (en) * | 1988-06-18 | 1989-12-26 | Mitsui Kensaku Toishi Kk | Porous body of mgo-al2o3 spinel |
| JP2007217260A (en) * | 2006-02-20 | 2007-08-30 | Itochu Ceratech Corp | Porous refractory material |
| CN102308191B (en) * | 2009-02-18 | 2014-06-18 | 贺利氏电子耐特国际股份公司 | Temperature measuring device |
-
1983
- 1983-09-19 JP JP17356883A patent/JPS6065778A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6065778A (en) | 1985-04-15 |
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