DE3003046A1 - FIRE-RESISTANT CERAMIC MATERIAL - Google Patents

Description

In the production of Al-killed steels after the deoxidation and alloying of the crude steel alumina as a solid, oxidic phase in liquid steel. In continuous casting of steel there is an immersion nozzle made of refractory material between the distributor and the mold. At the As it flows through the immersion nozzle, part of the alumina in the liquid steel separates on it Immersion nozzle from; large alumina agglomerates are formed, which from time to time are carried away by the flowing steel and become trapped when the steel solidifies.

Previously known immersion nozzles are composed of refractory masses that consist of one or more refractory Oxides (A12O3, SiO2, ZrO2, etc.), carbon (graphite, Coke, soot) and binders. These compositions are not suitable for the deposition of clay particles to prevent from the steel.

The object of the invention is to agglomerate on the inner immersion nozzle wall or on others with the Moldings in contact with liquid steel tend to have an alumina suspension in the liquid steel on the deposit to prevent on the refractory material.

To solve this problem, a structure of the refractory mass is proposed according to the invention, as it is in the patent claim is described. The advantage of the refractory composition according to the invention is that the existing in the steel solid oxidic suspensions (e.g. alumina) in the phase transition of liquid steel - refractory bodies on contact experience a lowering of the melting point with the refractory wall or parts of this refractory wall.

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This lowering of the melting point leads to the fact that the primarily solid alumina particle (approx. 1 to 30 μm in diameter) becomes liquid after contact with the refractory wall and thus does not adhere.

The substance acting on the suspension in the refractory body forms an oxidic melt with it, i.e. the melting point of this slag is below the operating temperature of the steel. In the attached examples are possible embodiments of the invention Refractory races listed. Example 1 consists of corundum, graphite, calcium silicon and binder. That metallic calcium and silicon present in the mass or calcium silicon present as an alloy metallically stable. This stable state becomes relative in comparison to the steel temperature low temperature of the refractory mass and reducing created by the presence of carbon Conditions achieved.

These reducing conditions become more liquid at the phase boundaries (refractory mass - air; refractory mass - more liquid Steel) converted to oxidizing. Once at the phase boundary air - refractory becomes gradually Carbon burn-off the metallic component oxidizes and forms an oxidic mixed phase with the base material. Although this mixed phase is subject to a lowering of the melting point, it is not subject to any erosive force, which means erosion and thus wear does not occur.

130031/0459 BATH ORIGINAL

At the phase boundary between refractory and liquid steel, oxidation of the metal begins after carbon has been burned Component (calcium, silicon, calcium silicon) with Al-killed steel.

This oxidation can take place because of calcium in Al-pacified Steel still has a deoxidizing effect.

The resulting potassium silicon mixed oxide has an effect Alumina lowers the melt material at phase transition and leads to a mixed oxide that is liquid at the phase boundary (Slag film).

This slag film is now carried into the mold bath by the erosive effect of the flowing steel. Here the slag is in the form of a sphere and is then deposited.

This inventive process leads to a desired internal wear of the refractory wall and avoids Deposition of clay on this wall. The wall thickness and the composition of the refractory material must be in relation stand at the intended casting time.

Another application example (see Example 2) can be BN, which is not stable under oxidizing conditions and forms B2O3 and is a liquefier for alumina (present as a suspension in steel) and the like Effect - as listed in Example 1 - shows.

Furthermore, the erision in the slag area can be caused by an already known mass composition with zirconium oxide be counteracted (example 3) ^

It is also possible to replace alumina with quartz glass (Examples 4 and 5).

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BATH ORIGINAL

Example 1: 40 - 70% VZ'rf. 60% Corundum. 5 - 15% VZW. 10% Calcium silicon 15th - 30% VZW. 25% graphite 5 - 15% VZW. 5% binder

Example 2 :

40 - 70% vzw. 60% corundum

5 - 15% VZV- /. 10% boron nitride

15 - 30% vzw. 25% graphite

5 - 15% vzw. 5% binder

example 3: 40-70% VZW. 60% Zirconium oxide 15-30% VZW. 25% graphite 5 - 15% VZW. 10% Ferrosilicon 5 - 15% VZW. 5% binder example 4: 40-70% VZV /. 60% Quartz glass 5 - 15% VZW. 10% Calcium silicon 15-30% VZW. 25% graphite 5 - 15% VZW. 5% binder

Example 5: 40-70% VZVJ. 60% Quartz glass 5 - 15% VZW. 10% Boron nitride 15-30% VZW. 25% graphite 5-15% VZW. 5% binder

130031/0459

Claims (1)

PATENT AGENCY OFFICE BERLIN - MUNICH PATENT LAWYERS DIPL-ING. W. MEISSNER DIPL-ING. P. E. MEISSNER DIPL-ING. H.-J. PRESTING Authorized representatives before the European Patent Office - Professional Representatives before the European Patent Office Your sign Your letter of Our signs mjr / Go. 20574 HERBERTSTR. 22, 1000 BERLIN January 25, 1980 Mannesmann AG
Mannesmannufer 2 4000 Düsseldorf 1 Refractory ceramic mass Claim; Refractory ceramic mass based on aluminum oxide or zirconium oxide or silicon oxide with carbon and binders for the production of immersion nozzles or other molded bodies in contact with liquid steel, characterized in that the mass 5 to 15% weight percent calcium silicon (met.) And / or Contains ferrosilicon (met.) And / or boron nitride. 130031/0459 ■ Branch (§ 28 PaO) TELEX: TELEGRAM: TELEPHONE: Munich: 1-856 44 INVENTION BERLIN ST. ANNASTR. 11 Inven d BERLIN 030/89160 37 8000 MÖNCHEN 22 030/892 23 82 TEL: 063/22 35 44 BANK ACCOUNT: BERLINER BANK AQ. BERLIN 31 3695716000 POST CHECK ACCOUNT: W. MEISSNER, BLN-W 122 82-109