JPH03169477A - Plate brick for unburnt sliding nozzle - Google Patents

Abstract

PURPOSE:To restrain oxidation of the sliding face of a unburnt SN plate brick and to reduce face roughing by adding the polycarbosilane powder of a prescribed grain diameter at the limited wt.% to body composed of refractory inorganic material. CONSTITUTION:By adding the polycarbosilane powder having <=0.2mm grain diameter at 1-10wt.% in the outside ratio to the body composed of the refractory inorganic material, and kneading the mixture to form the unburnt SN plate brick, the oxidation of the sliding face is restrained, the face roughing can be reduced and an effect improving the service life in reusable degree is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sliding nozzle plate brick (hereinafter referred to as SN plate brick) that is installed in a ladle, tundish, etc. in a steel factory.

[Conventional technology]

Generally, SN plate bricks are installed at the bottom of ladles and tundishes in steel factories, and are widely used to control the flow rate of molten steel.

However, SN plate bricks are approximately 1550-1
Radial cracks may occur in the nozzle hole due to rapid thermal shock and wear due to the molten metal flow reaching temperatures as high as 600°C, and there is a risk of molten steel leaking due to such cracks. Since so-called squeeze injection is commonly used, the edges of the nozzle hole on the sliding surface and the areas where the molten metal flow collides are particularly susceptible to melting damage. SN after injection
As the plate bricks slide, molten steel gets caught (so-called metal entrapment), and the sliding surfaces gradually wear out, resulting in so-called sliding surface roughness.

Under these circumstances, the SN plate brick is a part that requires the most advanced functionality in order to control the flow rate of molten metal.

On the other hand, in recent years, unfired SN plate bricks have been developed and are being used instead of carbon bond fired bricks, which have traditionally been used as SN plate bricks, in order to streamline the brick manufacturing process and reduce manufacturing costs. but,
Since the deterioration of the Mi weave after oxidation of the above-mentioned non-burnable SN plate bricks is more remarkable than that of burnt bricks, various methods have been investigated to improve the oxidation resistance. For example, Tokuko Sho 63-32
B. 097, etc. Those added with C or BN to form a glass layer in the oxidized part, and
Unfired SN plate bricks have been proposed in which metal aluminum powder having a higher oxidation affinity than carbon is added as disclosed in .

Furthermore, JP-A-60-81068, JP-A-61-1
46773 etc., S heated to about 500-800℃
At the outer periphery of N-plate bricks, carbonization of the binder causes a decrease in strength, which tends to cause cracks and surface roughness due to wear, so a method of adding aluminum fibers, etc. to improve the strength of the brick structure has also been proposed. There is.

[Problem to be solved by the invention]

However, in response to the recent demand for further reduction in steel manufacturing costs, tandy sosh has been reused, and SN plate bricks have also been reused in the same way. When reusing SN plate bricks, it is necessary to spray an oxygen jet to melt and remove the base metal adhering to the nozzle holes and sliding surfaces, and the nozzle holes and sliding surfaces are subject to rapid oxidation. receive.

Generally, when unfired SN plate bricks undergo oxidation, some of the carbon they contain disappears, or in other words, when they are decarburized, that part becomes brittle, becomes more susceptible to melting and wear, and its durability is significantly reduced. Also, in the portion heated to about 500 to 800° C., strength decreases due to carbonization of the binder, and there is a drawback that cracks and base metal adhesion due to thermal stress are likely to occur.

This invention has been proposed in view of the above-mentioned conventional circumstances, and is aimed at improving the durability of unfired SN plate bricks by improving their oxidation resistance.

[Means to solve the problem]

In order to solve the above problems, the present invention employs the following means. That is, 1 to 10% by weight of polycarbosilane with a particle size of 0.2 mm or less is added to the clay made of a fire-resistant inorganic material, or a polycarbosilane solution is added to the clay. This is a plate brick for an unfired sliding nozzle which is added in an amount of 1 to 10% by weight and can also be used in combination with a thermosetting silicone resin solution, phenol resin, tar, etc.

[For production]

The polycarbosilane used in the present invention is an organosilicon resin mainly having an St--C skeleton structure within the molecule, as exemplified by the following formula.

Here, Rl and R2 represent organic functional groups such as hydrogen, methyl, and phenyl groups, and n is a coefficient representing the degree of polymerization.

The added polycarbosilane and silicone resin cause a demethanization reaction due to thermal decomposition of the methyl groups in the side chain at 400 to 800 °C when the brick is used, producing SiC.
The dimensional Si-C bond increases the bonding strength of the brick structure and contributes to improving the strength of the brick. Furthermore, sliding surfaces and nozzle holes that are exposed to high heat are oxidized and cause Sin. This produces the effect of suppressing carbon oxidation by densifying the oxidized layer and suppressing carbon oxidation.

When the polycarbosilane to be added is a powder, the particle size is 0.
The thickness is preferably 2 mm or less; if it is larger than 0.2 mm, uniformity within the brick will be lacking and the oxidation inhibiting effect will be reduced. Also,
The appropriate amount of addition is 1 to 10% by weight; if it is less than 1% by weight, a sufficient effect will not be obtained, and if it exceeds IO weight%, the deterioration of the brick structure during oxidation will be significant, and the oxidation resistance will be reduced. This is not preferable because it reduces the properties and abrasion resistance.

When the polycarbosilane to be added is in the form of a solution, the amount of resin contained in the solution is preferably 1 to 10% by weight,
If it is less than 1% by weight, a sufficient effect cannot be obtained, and if it exceeds 10% by weight, the amount of binder becomes excessive, resulting in a decrease in kneading workability and a decrease in the mechanical strength of the bricks, which is not preferable.

Polycarbosilane solution and thermosetting silicone resin solution,
When used in combination with phenol resin, tar, etc., the total amount added is preferably 2 to 15% by weight based on the fire-resistant inorganic material; if it is less than 2% by weight, sufficient effects cannot be obtained, and if it exceeds 15% by weight, This is not preferable because the amount of binder becomes too large, resulting in a decrease in kneading workability and a decrease in the mechanical strength of the bricks.

〔Example〕

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

The blending ratio of the bricks of the present invention is shown in the upper column of Table 1.

In Examples 1 to 3, polycarbosilane powder was mixed with fine powder of a refractory inorganic material in advance using an all-purpose mixer, and then kneaded and mixed.
Performed the bogata. Further, as a binder, tar and phenol resin liquid were added and kneaded singly or in combination.

Further, in Examples 4 to 8, a polycarposilane solution prepared by dissolving 60 parts by weight of polycarbosilane powder with a particle size of 1 m1 or less in 40 parts by weight of xylene was added, and a thermosetting silicone resin solution, a phenol When used in combination with resin, tar, etc., the mixture was mixed with the above polycarposilane solution in advance and then added to and kneaded with the refractory inorganic material.

In addition, in order to prevent lamination during precepts, 10
Heat treatment was performed in a hot air dryer maintained at 0° C. so that the volatile content of the clay reached the values shown in Table 1. The drying temperature was 100°C for the tar-added clay and 60°C for the others.

The command form is S for tundish using a friction press.
N-plate bricks were shaped. If the base material is tar-added, it is heated in a coke breeze at 400℃ for 10 hours.
Others were heat treated in air at 180°C for 24 hours.

The quality characteristics of the SN plate bricks produced in this manner are shown in the middle column of Table 1.

The results of Examples 1 to 8 show that the oxidation resistance is improved by adding polycarposilane powder or its solution.

The above quality characteristic values were measured in the following manner using the usual method for refractories.

■Thickness of oxide layer: 30x30x30 from the prototype brick 1
Two specimens of each of No. 11 were cut out, and the specimens were placed in an electric furnace in an air atmosphere maintained at 800° C. and heat treated for 3 hours.

The thickness of the oxidized layer is indicated by the thickness of the oxidized layer at the cut surface at the center of the height during the heating test.

■ Molten steel erosion index: 1650 when the sample is lined in a high frequency furnace
After carrying out a molten steel erosion test at ℃ for 3 hours, the central part of the sample was cut in the longitudinal direction, and the erosion area on the cut surface was measured.
It is shown as a relative value to Comparative Example 1.

Next, three sets each of the bricks of Comparative Examples 1 and 2 and Examples 1 to 8 were actually used as SN plate bricks for Tandi Sosh. When using the actual machine, one charge (hereinafter referred to as "ch") of molten steel ladle (approximately 280 tons) was continuously injected into the mold through 6 channels, and then the slag was discharged and the nozzle hole was cleaned with an oxygen jet. Further series [6
Channel casting was performed (total 12 channel casting). As a result of collecting and observing the used product, it was found that the product was damaged as shown in the lower column of Table 1. By adding polycarbosilane powder and adding polycarbosilane solution as a binder alone or in combination with thermosetting silicone resin, phenol resin, or tar, oxidation of the sliding surface of SN plate bricks was reduced and surface roughness was significantly reduced. . Although the addition of polysilane tended to slightly increase the erosion loss of the nozzle hole, the amount of erosion was small and did not pose a problem in practice. In addition, the occurrence of cracks was relatively small in all cases, and did not cause the SN plate bricks to be discarded.

In this way, the addition of polycarbosilane made it possible to improve the oxidation resistance, prevent the sliding surface from becoming brittle due to oxidation, suppress metal entrapment, and reduce surface roughness.

[Effects of the present invention] As described above, the unfired SN plate brick of the present invention can be produced by adding polycarbosilane powder to the conventional carbon-containing unfired material, or by adding a polycarbosilane solution as a binder alone or by heat treatment. By adding it in combination with a curable silicone resin solution, phenol resin, tar, etc., it is possible to suppress oxidation of the sliding surface and reduce surface roughness, resulting in the effect of increasing durability to the extent that it can be reused. It was done.

Claims (3)

[Claims] (1) Particle size of 0.2 for clay made of fire-resistant inorganic material
A plate brick for an unfired sliding nozzle, characterized in that an outer layer of polycarbosilane powder of 1 mm or less is added in an amount of 1 to 10% by weight. (2) Add a polycarbosilane solution to the clay made of a fire-resistant inorganic material and apply the polycarbosilane amount to 1 to 10.
A plate brick for an unfired sliding nozzle characterized by adding % by weight. (3) Adding a polycarbosilane solution in combination with a thermosetting silicone resin solution, phenol resin, tar, etc. to clay made of a fire-resistant inorganic material in an amount of 1 to 10% by weight as an external amount of polycarbosilane. A plate brick for an unfired sliding nozzle, which is characterized by: