EP1562875A1 - Refractory ceramic molded article - Google Patents

Refractory ceramic molded article

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Publication number
EP1562875A1
EP1562875A1 EP03811763A EP03811763A EP1562875A1 EP 1562875 A1 EP1562875 A1 EP 1562875A1 EP 03811763 A EP03811763 A EP 03811763A EP 03811763 A EP03811763 A EP 03811763A EP 1562875 A1 EP1562875 A1 EP 1562875A1
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EP
European Patent Office
Prior art keywords
spinel
mass
shaped body
body according
zro
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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Application number
EP03811763A
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German (de)
French (fr)
Inventor
Robert Sherriff
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Refractory Intellectual Property GmbH and Co KG
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Refractory Intellectual Property GmbH and Co KG
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Publication of EP1562875A1 publication Critical patent/EP1562875A1/en
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
    • C04B35/482—Refractories from grain sized mixtures
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/007—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof characterised by the pore distribution, e.g. inhomogeneous distribution of pores
    • C04B38/0074—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof characterised by the pore distribution, e.g. inhomogeneous distribution of pores expressed as porosity percentage
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3206—Magnesium oxides or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3208—Calcium oxide or oxide-forming salts thereof, e.g. lime
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3217—Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
    • C04B2235/3222—Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3244—Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3244—Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
    • C04B2235/3246—Stabilised zirconias, e.g. YSZ or cerium stabilised zirconia
    • C—CHEMISTRY; METALLURGY
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
    • C04B2235/5427—Particle size related information expressed by the size of the particles or aggregates thereof millimeter or submillimeter sized, i.e. larger than 0,1 mm
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/72—Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/77—Density
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/9607—Thermal properties, e.g. thermal expansion coefficient

Definitions

  • the invention relates to a refractory ceramic molded body.
  • molded body includes all shaped ceramic refractory products, for example stones, plates, pipes, etc.
  • Refractory ceramic shaped bodies in plate form are used in slide closures (rotary or linear slides). Such slide closures are used to control a molten metal during casting, for example from a pan or from a tundish. Likewise, the use of slide closure systems on converters is known where high melting temperatures prevail, an aggressive slag is produced and the slide plates are required to have a long service life.
  • the plates - with the exception of very small plates - are often formed with so-called inserts made of zirconium dioxide (ZrO 2 ), the inserts being installed in the zones of the plates which have to have particular durability or which are particularly stressed.
  • ZrO 2 zirconium dioxide
  • the special requirements also include thermal shock resistance, i.e. resistance to frequent or rapid temperature changes.
  • DE 3341524 C3 describes a refractory molded body with a zirconium dioxide content of 94-97% by weight, the zirconium dioxide being fully or partially stabilized with CaO, MgO or Y 2 O 3 , with certain contents of silica (SiO ) To be defined.
  • a shaped body is essentially single-phase (at most with small amounts of forsterite at the grain boundaries).
  • the shaped bodies known from DE 3341 524 C3 have proven themselves in principle, their resistance to thermal shock is in some cases insufficient for individual applications mentioned at the beginning. In the Use as inserts in the pouring hole area of a slide plate can cause radial and / or tangential cracks during temperature changes, which can also lead to flaking.
  • DE 19938752 AI describes a process for producing a material based on ZrO 2 , in which an oxide is added to the batch, which forms up to 5% by weight of spinel phases in the zirconium dioxide matrix when the batch is sintered. In this way, the degree of stabilization of the ZrO should be reduced. Micro-cracks are specifically formed by spinel growth.
  • the invention is based on the object of providing a refractory ceramic molded body which, in particular, has a higher thermal shock resistance than the aforementioned molded bodies based on ZrO 2 .
  • the invention is based on the knowledge that materials based on ZrO 2 lead to improved thermal shock resistance if the proportion of MA spinel (MgAl 2 O) is increased compared to the proportion of 5 mass% known from DE 19938752 A1, and to a value in the range "> 5-20 M .-%".
  • the thermal shock resistance could be further increased if the proportion of MA spinel was set to a value in the range "> 10-20 M .-%".
  • the firing process must be carried out in such a way that the open porosity (according to EN 993-1) is in the range between 5 and 20 vol.%.
  • the increase in the fracture work in a molded article according to the invention by almost 100% compared to the comparative sample means a drastic improvement in the service life of the corresponding molded part, for example when using a converter. slide plate.
  • ZrO 2 -containing raw materials preferably those which have only a small part of SiO 2.
  • Oxides such as CaO, MgO or Y 2 O 3 can be added for stabilization.
  • the grain size of the zirconium dioxide is, for example, in the range ⁇ 3 mm, although a fine fraction ⁇ 0.063 mm can also be present.
  • the proportion of ZrO (not, partially or fully stabilized) can be between 85 and 95% by mass and the MA spinel proportion can be between 5 and 15% by mass.
  • the total proportion of MgO, including any proportion to stabilize the ZrO 2 is between 5 and 10% by mass, the total proportion of aluminum oxide (Al 2 O 3 ) between 3 and 14% by mass.
  • the open porosity is limited to a value between 8 and 17% by volume.
  • the MA spinel can be formed in situ or added as a pre-synthesized spinel, for example as a sintered spinel or melt spinel.
  • a pre-synthesized MA spinel leads to particularly advantageous property values of the type mentioned.
  • a spinel content significantly above 20% by mass proves to be disadvantageous.
  • the open porosity decreases drastically (towards 0) and the wear behavior of the molded part becomes significantly worse. Even if this is offset by an increased cold bending strength or hot bending strength, the disadvantages predominate, which is why the proportion of spinel is limited to> 5 to 20% by mass.

Abstract

The invention relates to a refractory ceramic molded article whose structure comprises a) 80-95 % by weight ZrO2 and b) 5-20 % MA spinel, which in turn comprises c) <0.8 % by weight Si02 and d) <1.0 % by weight iron oxides, and e) has an apparent porosity (according to EN 993-1) of 5-20 % by volume.

Description

Feuerfester keramischer Formkörper Refractory ceramic molded body
B e s c h r e i b u n gDescription
Die Erfindung betrifft einen feuerfesten keramischen Formkörper. Der Begriff "Formkörper" umfaßt dabei alle geformten keramischen feuerfesten Erzeugnisse, also beispielsweise Steine, Platten, Rohre etc.The invention relates to a refractory ceramic molded body. The term "molded body" includes all shaped ceramic refractory products, for example stones, plates, pipes, etc.
Feuerfeste keramische Formkörper in Plattenform werden bei sogenannten Schieberverschlüssen (Dreh- oder Linearschieber) eingesetzt. Derartige Schieberverschlüsse dienen der Regelung einer Metallschmelze beim Vergießen, beispielsweise aus einer Pfanne oder aus einem Tundish. Ebenso ist die Anwendung von Schieberverschlußsystemen an Konvertern bekannt, wo hohe Schmelztemperaturen herrschen, eine aggressive Schlacke anfällt und von den Schieberplatten hohe Standzeiten verlangt werden.Refractory ceramic shaped bodies in plate form are used in slide closures (rotary or linear slides). Such slide closures are used to control a molten metal during casting, for example from a pan or from a tundish. Likewise, the use of slide closure systems on converters is known where high melting temperatures prevail, an aggressive slag is produced and the slide plates are required to have a long service life.
Werkstoffe auf Basis Aluminiumoxid weisen häufig keine ausreichende Korrosionsbeständigkeit auf. Besser sind Werkstoffe auf Basis Zirkoniumdioxid. Solche zeigen die DE 36 10 041 C2 und DE 36 34 588 AI . Beide führen zu nahezu dichten Formteilen mit Porositäten bis ca. 1 % (DE 36 10 041 C2) beziehungsweise bis 4 % (DE 36 34 588 A I ), sofern Werkstoffe auf Basis ZrO2 mit Spinellanteilen offenbart sind. Solche Werkstoffe sind für Schieberplatten ungeeignet.Materials based on aluminum oxide often do not have sufficient corrosion resistance. Materials based on zirconium dioxide are better. Such show DE 36 10 041 C2 and DE 36 34 588 AI. Both lead to almost sealed molded parts with porosities of up to approx. 1% (DE 36 10 041 C2) or up to 4% (DE 36 34 588 AI), provided that materials based on ZrO 2 with spinel components are disclosed. Such materials are unsuitable for slide plates.
Aus Kostengründen werden die Platten - außer bei sehr kleinen Platten - häufig mit sogenannten Einsätzen (Inserts) aus Zirkoniumdioxid (ZrO2) gebildet, wobei die Einsätze in den Zonen der Platten eingebaut werden, die besondere Haltbarkeiten aufweisen müssen, oder besonders beansprucht werden.For reasons of cost, the plates - with the exception of very small plates - are often formed with so-called inserts made of zirconium dioxide (ZrO 2 ), the inserts being installed in the zones of the plates which have to have particular durability or which are particularly stressed.
Zu den besonderen Anforderungen gehört auch die Thermoschockbeständigkeit, also die Widerstandsfähigkeit gegenüber häufigen beziehungsweise schnellen Temperaturwechseln.The special requirements also include thermal shock resistance, i.e. resistance to frequent or rapid temperature changes.
Die DE 3341524 C3 beschreibt einen feuerfesten Formkörper mit einem Anteil an Zirkoniumdioxid von 94-97 Gew.-%, wobei das Zirkoniumdioxid mit CaO, MgO oder Y2O3 ganz oder teilweise stabilisiert ist, wobei je nach Stabilisierungsoxid bestimmte Gehalte an Kieselsäure (SiO ) definiert werden. Ein solcher Formkörper ist im Wesentlichen einphasig (allenfalls mit geringen Mengen an Forsterit an den Korngrenzen). Wenngleich sich die aus der DE 3341 524 C3 bekannten Formkörper prinzipiell bewährt haben, so ist ihre Thermoschockbeständigkeit für einzelne der Eingangs genannten Anwendungen teilweise nicht ausreichend. Bei der Verwendung als Einsätze im Gießlochbereich einer Schieberplatte können sich radiale und/oder tangentiale Risse bei Temperaturwechseln bilden, die im Weiteren zu Abplatzungen führen können.DE 3341524 C3 describes a refractory molded body with a zirconium dioxide content of 94-97% by weight, the zirconium dioxide being fully or partially stabilized with CaO, MgO or Y 2 O 3 , with certain contents of silica (SiO ) To be defined. Such a shaped body is essentially single-phase (at most with small amounts of forsterite at the grain boundaries). Although the shaped bodies known from DE 3341 524 C3 have proven themselves in principle, their resistance to thermal shock is in some cases insufficient for individual applications mentioned at the beginning. In the Use as inserts in the pouring hole area of a slide plate can cause radial and / or tangential cracks during temperature changes, which can also lead to flaking.
Die DE 19938752 AI beschreibt ein Verfahren zur Herstellung eines Werkstoffs auf Basis ZrO2, wobei dem Versatz ein Oxid zugegeben wird, welches beim Sintern des Versatzes bis zu 5 Gew.-% Spinellphasen in der Zirkoniumdioxidmatrix bildet. Auf diese Weise soll der Stabilisierungsgrad des ZrO herabgesetzt werden. Durch ein Spinellwachstum werden gezielt Mikrorisse gebildet.DE 19938752 AI describes a process for producing a material based on ZrO 2 , in which an oxide is added to the batch, which forms up to 5% by weight of spinel phases in the zirconium dioxide matrix when the batch is sintered. In this way, the degree of stabilization of the ZrO should be reduced. Micro-cracks are specifically formed by spinel growth.
Der Erfindung liegt die Aufgabe zugrunde, einen feuerfesten keramischen Formkörper bereitzustellen, der gegenüber den genannten Formkörpern auf Basis ZrO2 insbesondere eine höhere Thermoschockbeständigkeit aufweist.The invention is based on the object of providing a refractory ceramic molded body which, in particular, has a higher thermal shock resistance than the aforementioned molded bodies based on ZrO 2 .
Der Erfindung liegt die Erkenntnis zugrunde, dass Werkstoffe auf Basis ZrO2 zu einer verbesserten Thermoschockbeständigkeit führen, wenn der Anteil an MA-Spinell (MgAl2O ) gegenüber dem aus der DE 19938752 AI bekannten Anteil von 5 M.-% erhöht wird, und zwar auf einen Wert im Bereich "> 5-20 M.-%" .The invention is based on the knowledge that materials based on ZrO 2 lead to improved thermal shock resistance if the proportion of MA spinel (MgAl 2 O) is increased compared to the proportion of 5 mass% known from DE 19938752 A1, and to a value in the range "> 5-20 M .-%".
Die Thermoschockbeständigkeit konnte noch gesteigert werden, wenn der Anteil an MA-Spinell auf einen Wert im Bereich "> 10-20 M.-%" eingestellt wurde.The thermal shock resistance could be further increased if the proportion of MA spinel was set to a value in the range "> 10-20 M .-%".
Der größere MA-Spinellanteil im gebrannten Produkt führt überraschend zu einer erheblichen Steigerung der Brucharbeit Gf (zur Bestimmung der Brucharbeit mittels Keilspalttest: Krobath, Harmuth in Keramische Zeitschrift, 46. Jahrgang, Nr. 1 1 , 1994, S . 876-879) bei erhöhter Temperatur (beispielsweise 1 500 °C) gegenüber den genannten Produkten aus dem Stand der Technik. Bei Werkstoffen mit höherer Brucharbeit ist bei gleicher (thermo-) mechanischer Belastung der Rissfortschritt geringer als bei Werkstoffen mit niedriger Brucharbeit: Die erfindungsgemäßen Materialien sind somit widerstandsfähiger z.B. bei thermischer Wechselbeanspruchung, wie sie typischerweise in Schieberverschlussplatten auftreten.The larger proportion of MA spinel in the fired product surprisingly leads to a considerable increase in the fracture work Gf (for determining the fracture work by means of a wedge gap test: Krobath, Harmuth in Keramische Zeitschrift, 46th year, No. 1 1, 1994, p. 876-879) at elevated temperature (for example 1,500 ° C.) compared to the products mentioned from the prior art. In the case of materials with higher fracture work, the crack propagation is less with the same (thermo) mechanical load than with materials with low fracture work: The materials according to the invention are therefore more resistant, for example in the event of thermal alternating loads, as typically occur in slide closure plates.
Gleichzeitig tritt eine nachhaltige Verbesserung der Heißbiegefestigkeit (insbesondere bei 1600 °C) ein.At the same time, there is a lasting improvement in the heat bending strength (especially at 1600 ° C).
Der Anteil an MA-Spinell von 5-20 M.-% alleine reicht aber nicht aus, die gewünschten vorteilhaften Eigenschaften zu erreichen. Vielmehr muß weiterhin sichergestellt sein, dassThe proportion of MA spinel of 5-20% by mass alone is not sufficient to achieve the desired advantageous properties. Rather, it must still be ensured that
- der Anteil an Kieselsäure <0,8 M.-% ist, und- The proportion of silica is <0.8 M .-%, and
- der Anteil an Eisenoxiden (FeO, Fe O3) < 1 ,0 M.-% beträgt.- The proportion of iron oxides (FeO, Fe O 3 ) is <1.0 mass%.
Außerdem ist der Brennprozess so zu führen, dass die offene Porosität (nach EN 993- 1 ) im Bereich zwischen 5 und 20 Vol. -% liegt.In addition, the firing process must be carried out in such a way that the open porosity (according to EN 993-1) is in the range between 5 and 20 vol.%.
Der Einfluß des MA-Spinellanteils im Zusammenhang mit den weiteren Merkmalen wird besonders deutlich im Vergleich zu einem konventionellen Produkt, wie sich aus nachfolgender Tabelle ergibt: The influence of the MA spinel content in connection with the other characteristics is particularly clear in comparison to a conventional product, as can be seen from the following table:
Alle Angaben in Masse-%, soweit nicht anders angegeben.All data in mass%, unless otherwise stated.
Da die Brucharbeit mit einer guten Thermoschockbeständigkeit korreliert (mit Zunahme der Brucharbeit verbessert sich die Thermschockbeständigkeit), bedeutet die Erhöhung der Brucharbeit bei einem erfindungsgemäßen Formkörper um nahezu 100 % gegenüber der Vergleichsprobe eine drastische Verbesserung der Standzeit des entsprechenden Formteils, beispielsweise als Einsatz einer Konverter- Schieberplatte.Since the fracture work correlates with good thermal shock resistance (the thermal shock resistance improves with an increase in the fracture work), the increase in the fracture work in a molded article according to the invention by almost 100% compared to the comparative sample means a drastic improvement in the service life of the corresponding molded part, for example when using a converter. slide plate.
Erfindungsgemäß wurde festgestellt, dass eine gute Thermoschockbeständigkeit bei einer Brucharbeit bei 1 500°C von >400 J/m2 oder sogar von >500 J/m2 gegeben ist.According to the invention, it was found that there is good thermal shock resistance with a work at break at 1500 ° C. of> 400 J / m 2 or even of> 500 J / m 2 .
Zur Herstellung der Teile kann auf ZrO2-haltige Rohstoffe wie Baddeleyit zurückgegriffen werden, vorzugsweise solche, die nur einen geringen Teil an SiO2 aufweisen. Zur Stabilisierung können Oxide wie CaO, MgO oder Y2O3 zugesetzt werden. Die Korngröße des Zirkoniumdioxids liegt beispielsweise im Bereich <3 mm, wobei auch ein Feinanteil <0,063 mm vorhanden sein kann. Nach Zugabe von Wasser beziehungsweise eines Bindemittels kann die Oxidmischung (der Versatz) homogenisiert und zu einem Formkörper verpresst, anschließend getrocknet sowie danach gebrannt werden. Die Brenntemperatur kann bis zu 2000 °C betragen.For the manufacture of parts can be resorted to as baddeleyite ZrO 2 -containing raw materials, preferably those which have only a small part of SiO 2. Oxides such as CaO, MgO or Y 2 O 3 can be added for stabilization. The grain size of the zirconium dioxide is, for example, in the range <3 mm, although a fine fraction <0.063 mm can also be present. After adding Water or a binder, the oxide mixture (the batch) can be homogenized and pressed into a shaped body, then dried and then fired. The firing temperature can be up to 2000 ° C.
Ausgehend vom fertigen Produkt kann der Anteil an ZrO (nicht-, teil- oder vollstabilisiert) zwischen 85 und 95 M.-% betragen und der MA-Spinellanteil kann zwischen 5 und 15 M.-% liegen.Starting from the finished product, the proportion of ZrO (not, partially or fully stabilized) can be between 85 and 95% by mass and the MA spinel proportion can be between 5 and 15% by mass.
Der Gesamtanteil an MgO, einschließlich eines etwaigen Anteils zur Stabilisierung des ZrO2, liegt nach einer Ausführungsform zwischen 5 und 10 M.-%, der Gesamtanteil an Aluminiumoxid (Al2O3) zwischen 3 und 14 M. -%.According to one embodiment, the total proportion of MgO, including any proportion to stabilize the ZrO 2 , is between 5 and 10% by mass, the total proportion of aluminum oxide (Al 2 O 3 ) between 3 and 14% by mass.
Die offene Porosität wird nach einer Ausführungsform auf einen Wert zwischen 8 und 17 Vol.-% beschränkt.In one embodiment, the open porosity is limited to a value between 8 and 17% by volume.
Der MA-Spinell kann insitu gebildet werden oder als vorsynthetisierter Spinell, beispielsweise als Sinterspinell oder Schmelzspinell, zugesetzt werden. Die Zugabe eines vorsynthetisierten MA-Spinells führt zu besonders vorteilhaften Eigenschaftswerten der genannten Art.The MA spinel can be formed in situ or added as a pre-synthesized spinel, for example as a sintered spinel or melt spinel. The addition of a pre-synthesized MA spinel leads to particularly advantageous property values of the type mentioned.
Ein Spinellanteil wesentlich über 20 M.-% erweist sich als nachteilig. Die offene Porosität geht drastisch zurück (gegen 0) und das Verschleißverhalten des Formteils wird deutlich schlechter. Auch wenn dem eine gesteigerte Kaltbiegefestigkeit beziehungsweise Heißbiegefestigkeit gegenübersteht, überwiegen die Nachteile, weshalb der Anteil an Spinell auf >5 bis 20 M.-% beschränkt ist. A spinel content significantly above 20% by mass proves to be disadvantageous. The open porosity decreases drastically (towards 0) and the wear behavior of the molded part becomes significantly worse. Even if this is offset by an increased cold bending strength or hot bending strength, the disadvantages predominate, which is why the proportion of spinel is limited to> 5 to 20% by mass.

Claims

Feuerfester keramischer FormkörperP at e nt an s p rü ch e Fireproof ceramic moldingP at e nt to spokes
1. Feuerfester keramischer Formkörper, dessen Gefüge a) 80-95 M.-% ZrO2 und b) 5-20 M.-% MA-Spinell umfaßt, der c) <0,8 M.-% SiO2 und d) <1,0 M.-% Eisenoxide aufweist, und e) eine offene Porosität (nach EN 993-1) von 5-20 Vol.-% besitzt.1. Refractory ceramic molded body, the structure of which comprises a) 80-95% by mass of ZrO 2 and b) 5-20% by mass of MA spinel, which c) <0.8% by mass of SiO 2 and d) <1.0% by mass of iron oxides, and e) has an open porosity (according to EN 993-1) of 5-20% by volume.
2. Formkörper nach Anspruch 1, dessen Gefüge MgO- stabilisiertes ZrO2 umfaßt. 2. Shaped body according to claim 1, whose structure comprises MgO-stabilized ZrO 2 .
3. Formkörper nach Anspruch 1 , dessen Gefüge 85-95 M.-% ZrO2 umfaßt.3. Shaped body according to claim 1, whose structure comprises 85-95 M .-% ZrO 2 .
4. Formkörper nach Anspruch 1 , dessen Gefüge 5- 15 M.-% MA-Spinell umfaßt.4. Shaped body according to claim 1, the structure of which comprises 5-15% by mass of MA spinel.
5. Formkörper nach Anspruch 1 mit einem Gesamtanteil MgO zwischen 5 und 10 M.-%.5. Shaped body according to claim 1 with a total amount of MgO between 5 and 10% by mass.
6. Formkörper nach Anspruch 1 mit einem Gesamtanteil Al2O3 zwischen 3 und 14 M.-%.6. Shaped body according to claim 1 with a total proportion of Al 2 O 3 between 3 and 14 M .-%.
7. Formkörper nach Anspruch 1 mit einer offenen Porosität zwischen 8 und 17 Gew.-%.7. Shaped body according to claim 1 with an open porosity between 8 and 17 wt .-%.
8. Formkörper nach Anspruch 1 , wobei der MA-Spinell ein Sinterspinell ist.8. Shaped body according to claim 1, wherein the MA spinel is a sintered spinel.
9. Formkörper nach Anspruch 1 , wobei der MA-Spinell ein Schmelzspinell ist. 9. Shaped body according to claim 1, wherein the MA spinel is a melt spinel.
EP03811763A 2002-11-22 2003-11-19 Refractory ceramic molded article Withdrawn EP1562875A1 (en)

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JP4853103B2 (en) 2006-05-18 2012-01-11 東ソー株式会社 Powder for black zirconia sintered body, sintered body thereof, and colorant
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DE102007010173B4 (en) 2007-02-28 2009-04-16 Refractory Intellectual Property Gmbh & Co. Kg Melt-cast refractory product
EP2169311A1 (en) 2008-09-29 2010-03-31 Siemens Aktiengesellschaft Material mixture for producing a fire-retardant material, fire-retardant moulding body and method for its manufacture

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DE3634588A1 (en) * 1986-10-10 1988-04-21 Feldmuehle Ag SINTER MOLDED BODY
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