JPH0633205B2 - Coating material for carbon-containing bricks - Google Patents

Description

The present invention relates to a coating material for carbon-containing bricks for molten metal containers.

[Conventional technology]

Recent ironmaking, with advances in steel making technology, carbon-containing bricks torpedo car, a converter, Al ₂ O ₃ in the molten metal container such as ladle -
It is used in a composition such as C, Al ₂ O ₃ —SiC—C, and MgO—C.

Carbon-containing bricks are excellent in corrosion resistance, spalling resistance, etc., but have the drawback that they are slippery because the surface of the brick is very smooth. Therefore, when a carbon-containing brick is built on a piggy car, the brick is slippery and the work is very difficult. Further, the carbon-containing brick has a drawback that the carbon on the surface of the brick is oxidized during drying and temperature rise after building.

In order to prevent these, it is disclosed in JP-A-57-145090 that a coating material made of a refractory material and a resin is used.

[Problems to be Solved by the Invention]

However, with this coating material, slippage can be prevented by the frictional resistance of the coating layer, but it is not possible to prevent the carbon-containing bricks from disappearing due to the oxidation of carbon on the surface during drying and temperature rise after construction. did.

In order to prevent the oxidation of carbonaceous products, Japanese Examined Patent Publication No. 52-5049 has an example in which a binder is added to a powdery coating composition consisting of refractory powder, vitrified product, and low expansion powder,
After the low temperature range where the binder decomposes and disappears due to the temperature rise, there is a difficulty in maintaining the refractory powder and the vitrification and preventing the oxidation in the medium temperature range until reaching the high temperature range where the vitrified material melts.

[Means for Solving the Problems]

The present inventors have conducted various studies to solve the above problems, refractory materials, glass substances, and powdered silicic acid that maintains the refractory materials and glass substances on the surface of the carbon-containing bricks up to the temperature at which the glass substances melt. Soda, sodium phosphate,
By coating a carbon-containing brick with one or more aluminum phosphate (hereinafter referred to as sodium silicate) and a synthetic resin or a natural resin, or a coating material obtained by adding a carbon substance thereto, slipping can be achieved. The present invention has been completed by finding that a carbon-containing brick having an excellent stopping effect and an antioxidant effect can be obtained.

The refractory material used for the coating material of the present invention is alumina, silica, magnesia or the like, and imparts an anti-slip effect. This particle size is 1.0-0.125mm, preferably 0.5-0.125mm
If it is larger than 1.0 mm, it becomes difficult to bond the refractory material, and if it is smaller than 0.125 mm, the anti-slip effect is not sufficient. The amount used is 10 to 40% by weight, preferably 20 to 40% by weight, and if it is less than 10% by weight, the anti-slip effect is not sufficient, and if it is more than 40% by weight, pores are formed during glass film formation, Antioxidant effect decreases.

Examples of the glass substance include frit, cullet, and boron-based flux. To these, it is possible to add a carbide or a nitride that reacts with the brick material by oxidation to form a low-melting material. These can prevent carbon oxidation in the range of 500 to 1200 ° C. The amount used is 40 to 87% by weight, preferably 40 to 77% by weight, and if it is less than 40% by weight, the ratio of the refractory material to the glass substance is large and voids are formed at the time of forming the glass film. For this reason, a uniform film cannot be obtained, and the antioxidant effect is reduced. Further, if it exceeds 87% by weight, the anti-slip effect is not sufficient due to the reduction of the refractory material.

Powdered sodium silicate, sodium phosphate, and aluminum phosphate have an adhesion effect after resin decomposition. Sodium silicate has the largest adhesion effect, followed by sodium phosphate and aluminum phosphate in this order. This usage is 3 ~ 20% by weight
If it is less than 3% by weight, the adhesiveness after resin decomposition is poor, and if it is more than 20% by weight, the glass film has low viscosity and the antioxidant effect is lowered.

As synthetic resin, acrylic resin, silicone resin, epoxy resin, phenol resin, vinyl resin, etc., as natural resin, plant resin such as balsam, colophonium, damar, animal resin such as shellac, or kovar, amber etc. A fossil resin which is capable of forming a coating film by firmly adhering a coating material to the surface of a carbon-containing brick and volatilizing a solvent is most preferable. The amount used is a material consisting of refractory materials, glass substances, powdered sodium silicate, etc.
It is 10 to 40 parts by weight with respect to 100 parts by weight, and if it is less than 10 parts by weight, the strength of the coating is small and there is a risk of peeling.
On the other hand, if it exceeds 40 parts by weight, the glass film is not sufficiently formed, and the antioxidant effect is lowered.

The carbon substance improves workability at the time of coating and forms a uniform film, such as carbon black, graphite of 300 mesh or less, and pitch. The amount used is 0.5 to 5 parts by weight per 100 parts by weight of materials consisting of refractory materials, glass substances, powdered sodium silicate, etc. If less than 0.5 parts by weight, sufficient workability cannot be obtained and the coating film is homogeneous. It's hard to be. Furthermore, it also does not serve as a gas vent hole. On the other hand, if the amount is more than 5 parts by weight, the glass film has too many pores, and the antioxidant effect is lowered.

Examples of the solvent for the synthetic resin or natural resin include monohydric alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, polyhydric alcohols such as ethylene glycol and glycerin, and aromatic solvents such as toluene and xylene.

The coating material of the present invention is used for coating the surface of a carbon-containing brick by coating or spraying.

[Action]

The coating material of the present invention can be applied uniformly to the surface of a carbon-containing brick by adjusting the viscosity of the coating material by adding a synthetic resin or a natural resin and a solvent to a refractory material, a glass substance, sodium silicate or the like. When the volatile components of the resin are scattered, the refractory material, glass substance, sodium silicate, etc. are firmly attached to the surface of the brick. However, the resin is oxidatively decomposed at 200 to 300 ° C due to drying and temperature rise after building, and the adhesive function is lost. After the resin is oxidatively decomposed, the adhesion of the refractory material and the glass material to the surface of the brick is maintained by sodium silicate or the like. Further, when heated to a high temperature, the glass substance is melted to form a liquid phase, and a viscous glass film is formed on the surface of the carbon-containing brick to suppress the oxidation disappearance of graphite.

When a carbon material is added to the coating material, a more uniform coating is formed on the surface of the carbon-containing brick and workability is improved.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to examples.

Examples 1 to 6 Apparent porosity 8%, Bulk specific gravity 2.82, Compressive strength 410 kg / cm ² ,
Chemical composition Al ₂ O ₃ 66%, C 15%, SiC 10%, SiO
_{The surface of} an Al ₂ O ₃ —SiC—C brick having a length of 230 mm, a width of 114 mm, and a thickness of 70 mm of 23% and 6% of other components was coated with the coating material shown in Table 1 to a thickness of about 0.5 mm. .

The friction resistance of non-slip was determined by stacking the above bricks on a surface of 230 × 114 mm, placing the bricks on a horizontal rubber plate, pushing the upper brick horizontally, and measuring the maximum stress at the start of sliding with a load cell. Similarly, the maximum stress at the time when the uncoated brick begins to slide is measured, and the ratio of the maximum stress (friction resistance index) is determined based on this, and the value is shown in Table 1.

As for the oxidation resistance, the coating material shown in Table 1 was applied to the surface of a sample of a 40 mm cube having one side of the brick to a thickness of about 1.0 mm. This is 5 ℃ / min in a silicon carbide heating element electric furnace
Up to 800 ° C, hold at 800 ° C for 10 hours, then cut,
The area of the decarburized part was measured. Similarly, the area of the decarburized portion at 1000 ° C. was measured. This is shown in Table 1 as the decarburized area ratio.

[Effects of the invention] As is clear from the results in Table 1, Examples 1 to 6 to which the coating material of the present invention is applied have a greater anti-slip effect than Comparative Example 2 of the related art composed of a refractory material and a resin. In addition, a high antioxidant effect is obtained, which shows the superiority of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Yasui 32 Takeda, Okayama City, Okayama Prefecture (56) References Japanese Patent Publication Sho 52-5049 (JP, B2)

Claims (2)

[Claims] 1. A refractory material of 10 to 40% by weight and a glass substance of 40 to 87.
%, 1% or more of powdered sodium silicate, sodium phosphate, aluminum phosphate, which maintains the refractory material and the glass material on the surface of the carbon-containing brick up to the melting temperature of the glass material, 3 to 20% by weight A carbon-containing brick coating material, which is obtained by adding 10 to 40 parts by weight of a compatible resin or a natural resin to 100 parts by weight of a material. 2. Refractory material 10-40% by weight, glass substance 40-87
%, 1% or more of powdered sodium silicate, sodium phosphate, aluminum phosphate, which maintains the refractory material and the glass material on the surface of the carbon-containing brick up to the melting temperature of the glass material, 3 to 20% by weight For 100 parts by weight of material, compatible resin or natural resin 10-40 parts by weight, carbon substance 0.5
A coating material for carbon-containing bricks, characterized in that the coating material contains 5 to 5 parts by weight.