JPH07290230A - Plate for alumina carbonacious slide gate - Google Patents

Abstract

PURPOSE:To make a plate for an alumina carbonaceous slide gate high in durability due to the improvement of its oxidation resistance. CONSTITUTION:A plate for an alumina carbonaceous slide gate is added with 0.5 to 10wt.% boron-modified phenol resin contg. B as a binder, and imparted with high oxidation resistance in kneading, compacting, drying and burning processes. By using boron-modified phenol resin, the oxidation resistance is improved to improve the durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the material of a slide gate plate for controlling the flow rate of molten metal.

[0002]

2. Description of the Related Art Sliding gates are a useful means for controlling the flow rate of molten metal and are widely used. Especially in the steel industry, due to the severe operating conditions,
Widely used as a very informative method. The sliding gate consists of an upper nozzle, a fixed plate, a slide plate and a lower nozzle, each of which must have its own function. In particular, plate bricks are exposed to the severe environment of rapid thermal shock and physical wear due to the flow of molten metal and chemical erosion due to molten metal, so it is required to have a good balance of spalling resistance and corrosion resistance.

A high alumina material has been conventionally used for the slide gate plate. By impregnating the high alumina material with tar or pitch for the purpose of improving durability, stable use was possible. But,
The smoke generated during the operation of the tar pitch causes a serious problem that the work environment is deteriorated and the operability is deteriorated due to the adhesion of the tar and the pitch to the sliding device. Smokeless A
G quality plates have been developed and are in use. The AG quality plate had a good balance of spalling resistance, corrosion resistance, and other conditions to be satisfied, and was used with high durability.
However, in recent years, operating conditions have become more and more severe, and further high durability is desired.

[0004]

As a factor for limiting the service life of the slide gate plate, carbon is oxidized by the inflow of air from the plate surface, the surface is roughened due to the weakening of the tissue, and the nozzle. The edge of the hole may be damaged. In addition, in the case of Ca-added steel, which is often produced in recent years, it is often observed that the aggregate exposed by the oxidation of carbon and Ca react with each other to a large extent, which contributes to surface roughening and low durability. Therefore, it is considered that the improvement of the oxidation resistance is an effective means for increasing the durability of the AG plate.

[0005]

In order to improve the oxidation resistance of an AG plate, the present invention uses a boron-modified phenol resin having a higher oxidation resistance than the conventional novolac and resole phenol resins. , Has developed a highly durable AG plate. Conventionally, AG plates have been manufactured using a novolac or resol type phenol resin as a binder. It has been conventionally known that these phenolic resins are carbonized by a heat treatment such as drying or firing in a reducing atmosphere to remain in the brick structure by about 50% to form a carbon bond. However, it is considered that carbon derived from these binders is extremely unstable, and in actual use, carbon is preferentially oxidized before other carbon species, leading to weakening of the structure.

FIG. 1 shows TG curves of a normal novolac resin and a boron-modified phenol resin. As shown in FIG. 1, the boron-modified resin has 60
Oxidation at 0 ° C. to 800 ° C. is suppressed, and it is considered that when used as a binder in an AG plate, it most affects the weakening of the tissue. It is considered to have the effect of suppressing oxidation in the temperature range of 600 ° C to 800 ° C.
The boron-modified phenolic resin can be used either as a liquid or a powder, but the powder is easier to obtain from the current resin manufacturing technology. Further, the addition amount is set to 0.5 to 10% by weight, if 0.5% by weight or less, the sufficient effect cannot be obtained, and if it is 10% by weight or more, in terms of cost and moldability,
This is because there is no merit. The boron-modified phenol resin can be used alone as a binder, but in consideration of cost and moldability, it is desirable to use it together with a normal novolac or resol phenol resin. Alumina, alumina-zirconia, mullite-zirconia, carbon and additives are blended using the above resins, and organic resins such as pitch, tar and phenol resin,
It is used together with a binder such as pulp waste liquid and mixed and kneaded in a wet pan or a mixer. After press molding with a friction press or hydraulic press, 3
After removing the volatile components within a range of 0 ° C. to 300 ° C. to such an extent that the firing is not hindered, firing is performed in a reducing atmosphere or a non-oxidizing atmosphere such as a N ₂ stream.

[0007]

The AG plate obtained as described above is usually impregnated with pitch, tar and silicone resin, and heat-treated to completely remove volatile components, but impregnated depending on use conditions. Used as it is. The effect of addition will be described below with reference to examples.

[0008]

[Examples] Raw materials were mixed in the ratio shown in Table 1 and kneaded in a wet pan. Subsequently, pressure molding was performed using a friction press, drying was performed at 180 ° C., and reduction baking was performed at 1500 ° C. to obtain a slide valve plate. The physical properties of the obtained refractories and the test results are also shown in Table 1. Physical properties (apparent porosity, bulk specific gravity, compressive strength) were measured according to JIS. Oxidation resistance is 8mm for 40mm × 40mm × 40mm samples
After cutting for 5 hours in an electric furnace in an oxidizing atmosphere at 00 ° C, after cutting,
The oxide layer thickness was measured and evaluated.

[0009]

[Table 1]

As shown in the above table test, the use of the boron-modified phenolic resin as the binder improved the oxidation resistance. No deterioration in strength was observed. Alumina-zirconia was added based on the formulation based on these results. Material A company 300to
As a result of performing an actual machine test with a ladle of n, the durability is 10 to 1
It was possible to improve by about 5%. By using the boron-modified phenol resin as described above, the oxidation resistance and the durability can be improved.

[Brief description of drawings]

FIG. 1 is a comparison chart of thermal loss due to TG of a normal novolac resin and a boron-modified phenolic resin.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C04B 35/632 35/103 C09J 161/14 JEQ

Claims (1)

[Claims] Alumina-carbon-based slide gate plate (hereinafter referred to as AG-based plate), a boron-modified phenolic resin having a B content of 10 to 50% by weight as a binder,
A plate for a sintered alumina-carbon slide gate, which is obtained by the steps of kneading, molding, drying and baking by adding 0.5 to 10% by weight, and which has high oxidation resistance.