DE2363354A1 - Refractory material based on zirconium dioxide - from baddeleyite with addn. of calcium zirconate for stability of cubic structure - Google Patents

Refractory material based on zirconium dioxide - from baddeleyite with addn. of calcium zirconate for stability of cubic structure

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Publication number
DE2363354A1
DE2363354A1 DE2363354A DE2363354A DE2363354A1 DE 2363354 A1 DE2363354 A1 DE 2363354A1 DE 2363354 A DE2363354 A DE 2363354A DE 2363354 A DE2363354 A DE 2363354A DE 2363354 A1 DE2363354 A1 DE 2363354A1
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Germany
Prior art keywords
calcium zirconate
baddeleyite
cubic structure
zro2
zirconium oxide
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Pending
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DE2363354A
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German (de)
Inventor
Wilhelm Dr Brugger
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.)
Evonik Operations GmbH
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TH Goldschmidt AG
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Publication date
Application filed by TH Goldschmidt AG filed Critical TH Goldschmidt AG
Priority to DE2363354A priority Critical patent/DE2363354A1/en
Publication of DE2363354A1 publication Critical patent/DE2363354A1/en
Pending legal-status Critical Current

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    • 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
    • C04B35/486—Fine ceramics
    • C04B35/488—Composites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G25/00—Compounds of zirconium
    • C01G25/02—Oxides
    • 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
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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
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    • 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
    • C04B2235/3248—Zirconates or hafnates, e.g. zircon
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
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    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
    • C04B2235/444—Halide containing anions, e.g. bromide, iodate, chlorite
    • C04B2235/445—Fluoride containing anions, e.g. fluosilicate
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
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    • C04B2235/74—Physical characteristics
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  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

Refractory material based on ZrO2 having stabilised cubic structure is produced by firing a mixt. of purified baddeleyite with a calcium zirconate cpd. in which the molar ratio CaO:ZrO2 is 1:1.5-2.5. The molar excess of ZrO2 in the calcium zirconate cpd. ensures that total CaO is bound, whereby cracking of the material during the firing is prevented (as in the known compsns. in which water absorbed by free CaO evaporates and bursts the prod.). Calcium zirconate stabilises the cubic structure of ZrO2.

Description

Th. G ο 1 d s c h m i d t AG, EssenTh. G ο 1 d s c h m i d t AG, Essen

•Verfahren/ zur Herste].lung von feuerfesten Massen auf Basis von kubisch stabilisiertem Zirkonoxid• Process / for the manufacture of refractories Materials based on cubic stabilized zirconium oxide

Die Erfindung betrifft ein Verfahren zur Herstellung von feuerfesten Massen auf Basis von kubisch stabilisiertem Zirkonoxid durch Glühen von Zirkonoxid mit Calciumzirkonat.The invention relates to a method for producing Refractory masses based on cubic stabilized zirconium oxide by annealing zirconium oxide with calcium zirconate.

In einem noch nicht zum Stand der Technik gehörenden Verfahren ist vorgeschlagen worden, zur Herstellung von feuerfesten Massen auf Basis von kubisch stabilisiertem Zirkonoxid als Äusgangsmaterial natürlichen gereinigten Baddeleyit zu verwenden. Hierzu wird der natürliche gereinigte Baddeleyit in Gegenwart von 8 bis 20 Gew.-% feingemahlenem Calciumzirkonat vermischt und auf Temperaturen von 1400 bis 1700 C erhitzt. Die Masse wandelt sich dabei zu einer dicht gesinterten r mechanisch festen Masse um.In a method that is not yet part of the prior art, it has been proposed to use natural, purified baddeleyite as the starting material for the production of refractory masses based on cubically stabilized zirconium oxide. For this purpose, the naturally purified baddeleyite is mixed in the presence of 8 to 20% by weight of finely ground calcium zirconate and heated to temperatures of 1400 to 1700 C. The mass is converted thereby to a dense sintered r mechanically solid mass.

Dieses Verfahren hat gegenüber den Verfahren des Standes der Technikf bei denen man von synthetischem Zirkonoxid ausgeht,This process has, compared to the processes of the prior art f, in which one starts from synthetic zirconium oxide,

509 826/0 487509 826/0 487

ORlQiMAL INSPECTEDORlQiMAL INSPECTED

den Vorteil, daß einerseits nicht in einem Lichtbogenofen, sondern bei niedrigeren Temperaturen gearbeitet werden kann und andererseits die Umwandlungsrate und die Umwandlungsgeschwindigkeit des Zirkonoxids in die kubisch stabilisiertethe advantage that, on the one hand, in an arc furnace, but can work at lower temperatures and on the other hand the conversion rate and the conversion rate of the zirconium oxide into the cubic stabilized

Form wesentlich erhöht werden.Shape can be increased significantly.

Bei der Anwendung dieses Verfahrens hat sich jedoch gezeigt, daß zuweilen die mit Wasser angeteigten Formmassen beim Glühen zerfallen und nicht die gewünschte mechanische Stabilität aufweisen. However, when using this method it has been shown that that sometimes the molding compositions made into a paste with water disintegrate on firing and do not have the desired mechanical stability.

Überraschenderweise wurde nun gefunden, daß diese Erscheinung auf das verwendete Calciumzirkonat zurückzuführen ist und daß diese nachteiligen Effekte immer dann eintreten, wenn in dem verwendeten Calciumzirkonat ein Anteil an freiem CaO enthalten ist. Beim Glühen von Gemischen aus Zirkonoxid mit derartigem Calciumzirkonat wird an das Calciumoxid gebundenes Wasser bzw. CO^ freigesetzt und sprengt den Formkörper,Surprisingly, it has now been found that this phenomenon is due to the calcium zirconate used and that these adverse effects always occur when in the calcium zirconate used contains a proportion of free CaO. When annealing mixtures of zirconium oxide with such calcium zirconate is released water or CO ^ bound to the calcium oxide and bursts the molded body,

Der Erfindung liegt deshalb die Erkenntnis zugrunde, ein Calciumzirkonat bestimmter Zusammensetzung zu verwenden, wobei die Erfindung sich auf die Kombination der Verwendung von natürlichem gereinigtem Baddeleyit als Zirkonoxidmaterial und Calciumzirkonat eines bestimmten Molverhältnisses bezieht.The invention is therefore based on the knowledge to use a calcium zirconate of a certain composition, the invention being based on the combination of use of natural purified baddeleyite as zirconia material and calcium zirconate of a certain molar ratio.

509826/0487509826/0487

•Das erfindungsgemäße Verfahren ist daher dadurch gekennzeichnet, daß man als Zirkonoxid natürlichen gereinigten Baddeleyit und als Calciumzirkonat eine Verbindung mit einem Molverhältnis von CaO : ZrOp wie 1 : 1,5 bis 1 : 2,5 verwendet. .• The method according to the invention is therefore characterized by that as zirconium oxide natural purified baddeleyite and as calcium zirconate a compound with a Molar ratio of CaO: ZrOp such as 1: 1.5 to 1: 2.5 used. .

Bei der Kombination dieser beiden Materialien im Rahmen des erfindungsgemäßen Verfahrens gelingt es mit der erforderlichen Sicherheit und Reproduzierbarkeit, dicht gesinterte und mechanisch feste Massen zu erhalten, deren Zirkonoxidkomponente mindestens aus 70 bis 95 Gew,-% kubisch stabilisiertem Zirkonoxid, in Abhängigkeit von der Brenntemperatur, die bei 1400 bis 17000C liegt,, besteht.When combining these two materials within the scope of the method according to the invention, it is possible, with the necessary reliability and reproducibility, to obtain densely sintered and mechanically solid masses whose zirconium oxide component consists of at least 70 to 95% by weight of cubically stabilized zirconium oxide, depending on the firing temperature, which is at 1400 to 1700 0 C, exists.

Die zugesetzte Menge Calciumzirkonat beträgt etwa 8 bis 20 Gew.-%.The amount of calcium zirconate added is about 8 to 20% by weight.

Unter natürlichem gereinigtem Baddeleyit ist das Mineral zu verstehen, wie es beispielsweise aus dem Erzkörper Loole Kop bei Phalaborwa (Transvaal) in Südafrika gewonnen wird. Es handelt sich hierbei um ein Baddeleyitkonzentrat, das durch Reinigung auf einen Gehalt von etwa 98 bis 99 Gew.-% (Zr,Hf)O2 gebracht worden ist. Dieses Baddeleyitkonzentrat hat eine Kornverteilung, die gut zur Herstellung von Stampfmassen geeignet ist.Natural, purified baddeleyite is understood to be the mineral such as is extracted from the ore body Loole Kop near Phalaborwa (Transvaal) in South Africa. This is a baddeleyite concentrate that has been purified to a content of about 98 to 99% by weight (Zr, Hf) O 2 . This baddeleyite concentrate has a particle size distribution that is well suited for the production of ramming mixes.

509 826/048509 826/048

-■*-■■- ■ * - ■■

Das erfindungsgemäße Verfahren wird an Hand des folgenden Beispiels näher erläutert.The method of the invention is based on the following Example explained in more detail.

Beispiel νExample ν

Feingemahlenes Calciümzirkonat, das ingesamt 35 % CaO und davon etwa 8 - 9 % nicht gebundenes, freies CaO enthält und durch 5-stündiges Glühen bei 115O°C einer Mischung, bestehend aus 500 g natürlichem Baddeleyit mit einem Gehalt von 98,2 - 99 % (Zr,Hf)O2, 464 g Calciumcarbonat und 15 g Flußspat, hergestellt wurde, wird mit gleichen Gewichtsteilen von feingemahlenem und durch Säurebehandlung gereinigtem Baddeleyit mit 99,2 - 99,5 % (Zr,Hf)O2 gemischt. Die Mischung wird bei 1350 - 145O°C im elektrischen Kammerofen geglüht, wobei eine Haltezeit von 3 1/2 - 4 Stunden bei dieser Temperatur eingehalten wird. Das geglühte Endprodukt enthält 81,5 % (Zr,Hf)O2 und 17,6 % CaO.Finely ground calcium zirconate, which contains a total of 35% CaO and about 8 - 9% of it non-bound, free CaO and, by annealing for 5 hours at 115O ° C, a mixture consisting of 500 g of natural baddeleyite with a content of 98.2 - 99% (Zr, Hf) O 2 , 464 g calcium carbonate and 15 g fluorspar, is mixed with equal parts by weight of finely ground and acid treated baddeleyite with 99.2-99.5% (Zr, Hf) O 2 . The mixture is calcined at 1350-150 ° C. in an electric chamber furnace, with a holding time of 3 1/2 to 4 hours at this temperature. The annealed end product contains 81.5% (Zr, Hf) O 2 and 17.6% CaO.

Das RontgenbeugungsSpektrum des geglühten Endproduktes zeigt, daß es keinerlei freien Kalk enthält und nur aus Calciümzirkonat und kubisch stabilisiertem Zirkonoxid besteht. Es verhält sich gegenüber Wasser und Luft völlig inert und eignet sich deshalb zur Herstellung feuerfester Massen oder feuerfester Auskleidungen auf Basis von kubisch stabilisiertem Zirkonoxid.The X-ray diffraction spectrum of the annealed end product shows that it does not contain any free lime and consists only of calcium zirconate and cubic stabilized zirconium oxide. It behaves completely inert towards water and air and is therefore suitable for the production of refractory masses or Refractory linings based on cubic stabilized zirconium oxide.

50 9826/048750 9826/0487

Claims (1)

PatentanspruchClaim Verfahren zur Herstellung von feuerfesten Massen auf Basis von kubisch 'stabilisiertem Zirkonoxid durch Glühen von Zirkonoxid mit Calciumzirkonat, dadurch gekennzeichnet, daß manProcess for the production of refractory masses based on cubic stabilized zirconium oxide by annealing Zirconium oxide with calcium zirconate, characterized in that one a) als Zirkonoxid natürlichen gereinigten Baddeleyit unda) Baddeleyite and natural purified as zirconium oxide b) als Calciumzirkonat eine yerbindung mit einem Molverhältnis von CaO : Zr02b) as calcium zirconate a compound with a molar ratio of CaO: Zr0 2 verwendet.used. 509826/0487509826/0487
DE2363354A 1973-12-20 1973-12-20 Refractory material based on zirconium dioxide - from baddeleyite with addn. of calcium zirconate for stability of cubic structure Pending DE2363354A1 (en)

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DE2363354A DE2363354A1 (en) 1973-12-20 1973-12-20 Refractory material based on zirconium dioxide - from baddeleyite with addn. of calcium zirconate for stability of cubic structure

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DE2363354A DE2363354A1 (en) 1973-12-20 1973-12-20 Refractory material based on zirconium dioxide - from baddeleyite with addn. of calcium zirconate for stability of cubic structure

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4849383A (en) * 1986-12-24 1989-07-18 Mino Yogyo Company, Ltd. Basic refractory composition

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4849383A (en) * 1986-12-24 1989-07-18 Mino Yogyo Company, Ltd. Basic refractory composition

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