SU1752506A1 - Biceramic tundish nozzle for teeming of steel - Google Patents

Abstract

The invention relates to the refractory industry and can be used for the production of bieceramic glasses for casting manganese raw and carbon steels on continuous casting machines (continuous casting machines). The goal is to ensure high durability when casting steel and reliability of a double-layer glass service. The inner working layer is made of electroplastic zirconia stabilized with calcium oxide in an amount of 70-78% by weight and a mixture of alumina and fine-ground baddeleyite taken in a ratio of 1: (3.3-14). in the amount of 12-30 wt.%. The outer layer is made of the following composition, wt%: a mixture of mullite-corundum chamotte and corundum, taken in a ratio of 1: (3-5). 70-80; joint powder of a mixture of chamotte, kaolin and alumina, taken in the ratio (6-3) :( 2-1) (1-12), 20-30 1 tab. cl

Description

The invention relates to the refractory materials industry and is intended for the production of bi-ceramic (two-layer) glasses for casting manganese and carbon steels on continuous casting machines (continuous casting machines).

A two-layer casting nozzle for tanks with liquid metal is known, in which the refractory ceramic base is equipped with one or several wear-resistant refractory inserts, which are ring-shaped parts of high-refractory cermet that are retained by an annular abutment

from a ceramic base or with a solution.

However, the use of such dosing inserts does not completely protect the working part of the glass from erosion. Such glasses are suitable for casting Only single heats and do not allow to pour a series of heats with a long time effect of corrosive steels on the refractory (3-5 hours or more).

Baddeleyite glasses made of electroplating baddeleyite with sintering agent technical alumina and calcined at 1750 ° C are known. These glasses have well recommended themselves when casting aggressive manganese steels on a caster Baddelitic glasses are not

4 SL Y SL

I

they are reduced by manganese and, having provided a reliable service, have a small degree of erosion (0.5–2 mm for casting or 0.3–2 mm for hot hour), which allows the series to be cast.

However, the impossibility of re-using zirconium glasses due to the overgrowth of metal and slag, as well as taking into account the deficiency of zirconia and the high cost of refractories based on it (4,210 rubles / ton), makes it impractical to use whole-zirconia products per one casting.

The closest to the technical essence of the invention is a bieceramic cup, the outer layer of which is made of kaolinized chamotte fractions of 0.5-3 mm and clay no more than 10%, and the outer layer is made of zircon and clay up to 12%.

A disadvantage of the known bicaramic glass is that it cannot be burned above 1450 ° C due to the discrepancy between the volume changes of dissimilar layers: chamotte and zircon. And during low-temperature calcination, a ceramic-glass cup does not ensure complete sintering of the working layer, which leads to its erosion during casting of aggressive manganese steels. This disadvantage limits the extent to which a known bicerramic glass is used for spilling solid quiet steels.

The aim of the invention is to increase the durability and reliability of the service of a bikeramic glass when spilling aggressive steels.

This goal is achieved by the fact that in a bieceramic cup, including a non-working outer and inner working layer, the inner layer is made of the following composition, wt%: electrofusion zirconia stabilized with calcium oxide 70-88; a mixture of alumina and tokomolado baddeleyite in the ratio of 1: (3.3-14) 12-30. and the outer layer is made of a composition, May%: a mixture of mullite-corundum chamotte and corundum in a ratio of 1: (3-5) 70-80; fine ground powder from a mixture of mullite-corundum chamotte, kaolin and alumina in the ratio (6-3) :( 2-1) :( 1-12) 20-30.

Such a bieceram glass allows it to be calcined at 1750 ° C, since both layers have a similar thermal expansion coefficient (zirconium layer OJ & 10 5 1 / ° C, fireclay layer O, 1 / ° C), the inner working layer has high durability and reliability on contact with the melt of aggressive steels and practically does not contaminate them.

The outer non-working layer is strong enough and maintains the conditions of service. The preparation of baddeleyite and high-alumina masses is carried out by separately mixing the components of the mixture.

The high alumina mass is prepared as follows. First, a coarse-grained component — mullite-alumina chamotte and corundum — is fed to the mixer and moistened with technical lignosulfonate. After stirring for 5-7 minutes, a fine-grained component is added - pre-prepared joint grinding of chamotte, kaolin and alumina fractions of 0.09 µm. Mixing is continued for 15-20 minutes.

To prepare zirconium mass 0, zirconia stabilized with CaO, fractions 2-0.5 and less than 0.5 mm are loaded into the mixer, and a mixture of joint grinding of alumina and baddeleite is introduced and moistened with technical lignosulfonate or with an aqueous solution of technical lignosulfonate and alumina, and after mixing, the initial baddeleyite of a fraction less than 0.06 mm is added to the mixer while maintaining the ratio of alumina and bad-0 delite 1; (3.3-14). Then the masses are poured separately into the form - the working layer in the inner part between the separation tube and the rod, and the high-alumina mass - between the separation tube and the 5th form body. After that, the separation tube is removed and filled with a baddeleyite mass from above so that a layer of glass saddle is formed with a thickness of 10-15 mm, completely sealing the reinforcing part.

Then, a bicaramical product is molded to a density of the working layer of at least 4.60-4.75 g / cm, followed by drying and firing the bicaramical glass at 5 1650-1750 ° С, which ensures sintering of the working layer to a porosity of 13-16%.

PRI me R 1. The outer layer containing, in wt.%:

High-alumina mass (ratio 1: 1)

mullite-corundum chamotte35

corundum35

Fine powder from a mixture (ratio 6: 2: 1):

chamotte20

5 kaolin 6,7

alumina fraction 0.09 µm3.3

Inner working layer containing may%:

Zirconist mass

stabilized zirconia

CaO fusion fraction 2-0.5 mm40

0.5 mm30 5

A slip (1:14 ratio) initial baddeleyite fraction less than 0.09 micron28

technical lignosulfonate with a density of 1.17 g / cm3.10

alumina2

PRI mme R 2. The outer layer, content, wt.%:

High-alumina mass (ratio 3: 5): 15 mullite-alum fireclay 30 corundum 50 Fine ground powder from a mixture (ratio 3: 1: 12)

ShaMot 3.75 20

kaolin1.25

alumina fraction 0.09 µm15

The inner working layer content, wt.%:

Zirconist weight: .25

zirconium dioxide stabilized by CaO by melting fraction: 2-0.5 mm30

0.05 µm40

0.09 µm18 25

Mix joint grinding (ratio 1: 3.3):

alumina2

initial baddeleyite fraction 0.09 mm10 30

Froze The outer layer content wt.%:

High-alumina mass (ratio 3.6: 4):

mullite-corundum chamotte36 35 corundum40 Fine ground powder from a mixture (compaction 3: 1: 2):

chamotte 12

kaolin4 40

alumina fraction 0.09 µm8

The inner working layer content, wt.%:

Zirconist mass:

Zirconium dioxide, stabilized by 45 CaO by melting fraction: 2-0,5mm30

0.5 mm40

Co-milling (1: 9 ratio): alumina3 50

original badeleite fraction of 0.09 mm 27 PRI me R 4. The outer layer, content, wt.%:

High alumina mass (ratio 3: 4)

mullite corundum chamotte30

corundum40

Fine ground powder from the mixture (4: 1: 1 ratio):

chamotte20

kzolin5

alumina fraction 0.09 mm5

The inner working layer containing

zircon mass (composition is the same as in

example 3).

PRI me R 5 (extreme values). Outer layer:

High alumina mass (ratio 2: 1):

mullite corundum chamotte40

corundum20

Fine powder from a mixture (ratio 9: 3: 1):

chamotte27

kaolin 9

alumina fraction 0.09 mm3

The inner working layer containing, in wt.%:

Zirconist mass:

CaO stabilized zirconia by melting fraction: 2-0.5 mm30

 0.05 mm25

Slip (1:15 ratio): technical lignosulfonate with a density of 1.17 g / cm3

alumina3

baddeleyite initial fraction less than 0.09 mm45

Example (extreme values). The outer layer containing, in wt.%: High-alumina mass (ratio 1: 1.9):

mullite corundum chamotte30

corundum58

Fine powder from a mixture (ratio 2: 1: 6):

fireclay 4

kaolin2

alumina fraction 0; 09 mm6

Inside working layer: Zirconist weight:

zirconium dioxide, stabilized by CaO melting fraction:

2-0,5 mm40

less than 0.05 mm55

A slip (1: 1 ratio) technical lignosulfonate with a density of 1.17 g / cm3,

alumina2.5

baddeleyite initial fraction

0.09 µm2.5

EXAMPLE 7 A bicarame glass was prepared using a known technology.

The compositions according to examples 1-7 are shown in table.

Tests of bieceramical glasses were carried out when pouring manganese steel 09G2 with a temperature of 1545-1580 ° C. Both individual smelting and a series of two smelting by melting into smelting with a casting time from 1 h 30 min to 2 h 45 min and a total volume of up to 125 tons are poured

The test results are shown in the table. Tests have shown that the proposed ceramic-glass provides high durability and reliability when pouring aggressive steels. At the same time, the known glass did not withstand these conditions, since the working layer was eroded with aggressive steel.

0

five

Claims (1)

The formula of the invention of a bieceramic steel casting glass containing a non-working outer layer and an inner working layer, characterized in that, in order to increase its reliability and durability, the inner layer is made of the composition, wt%: electrofusion zirconia, stabilized - Calcium oxide, 70-88: a mixture of alumina and fine-ground baddeleyite in the ratio 1: (3.3-14) 12-30; and the outer layer is made of the composition, wt.%: a mixture of mullite-corundum chamotte and corundum in the ratio of 1: (3-5) 70-80; fine ground powder of a mixture of chamotte kaolin and alumina in the ratio (b-3) :( 2-1) :( 1-12) 20-30.