JPH10158071A - Graphite patching material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a patching material having high bonding strength between the carbon source and other materials and excellent corrosion resistance and oxidation resistance as compared to a conventional product and having a durable life for use by kneading a material containing zirconia, SiC, metal powder and graphite, compacting, firing and granulating to obtain a specified grain size and then incorporating the obtd. granulated material by a specified amt. into the patching material. SOLUTION: A source material containing zirconia, SiC, metal powder (such as metal silicon powder) and preferably 5 to 30wt.% graphite is kneaded, compacted, fired and granulated into <=5mm grain size to obtain a granulated material. The obtd. granulated product is further compounded by 35 to 80wt.% with a clay, silica sand or alumina brick chips having preferably <=5mm grain size by 20 to 65wt.% to obtain a patching material. The whole chemical compsn. of the patching material consists of, preferably by wt.%, 18.3 to 60.3% Al2 O3 , 11.0 to 62.1% SiO2 , 5.4 to 12.3% ZrO2 , 1.2 to 3.6% SiC, 0.49 to 1.1% metal Si and the balance carbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphitic patching material.

[0002]

2. Description of the Related Art A patching material is a soft refractory material in the form of a soft clay, and is a repair material that is driven into a small area of a damaged area such as a kiln or is painted with a trowel.

In the casting industry, patching materials are used as repair materials for induction furnaces and cupolas, and in the steelmaking industry, patching materials are used as repair materials for ladles and the like.

[0004] Conventional patching materials are generally manufactured by mixing earth graphite, pitch powder, tar powder, amorphous carbon, and silica sand into a clay mortar, kneading the mixture, and forming the mixture using a drawing machine. Was.

For example, a patching material has been manufactured using 10% by weight of a carbon source, 50% by weight of silica sand, 40% by weight of clayey mortar, and 20% by weight of water as raw materials.

[0006]

However, the conventional patching material has insufficient bondability between the carbon source and other raw materials, and is inferior in corrosion resistance.

Accordingly, an object of the present invention is to provide a patching material which is superior in corrosion resistance and oxidation resistance as compared with conventional products and has a long service life.

[0008]

According to the present invention, there are provided the following:
A granulated product obtained by kneading, shaping, and firing a raw material containing a graphite-based patching material described in (1), for example, zirconia, silicon carbide, metal powder, and graphite, to have a particle size of 5 mm or less, is 35
The present invention provides a graphite-based patching material characterized by containing about 80% by weight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The graphite patch material of the present invention comprises:
It is characterized by containing 35 to 80% by weight of a granulated product obtained by kneading, shaping and firing a raw material containing zirconia, silicon carbide, metal powder and graphite to a particle size of 5 mm or less.

When the amount of the granulated product is less than 35% by weight, sufficient corrosion resistance cannot be obtained. On the other hand, when the granulated product exceeds 80% by weight, the granulated product is likely to fall due to rapid heating during use. The metal powder is metal silicon, metal aluminum or the like, but metal silicon is particularly preferable.

[0011] Graphite, zirconia, silicon carbide, and metallic silicon are materials used for continuous cast refractories, and they help to improve the corrosion resistance of the graphite-based patching material. Particularly, oxidation resistance can be improved by using silicon carbide and metal silicon.

By setting the particle size of the granulated product to 5 mm or less, the packing density can be increased and the corrosion resistance can be improved. From such a viewpoint, the more preferable particle size of the granulated product is 4 mm or less.

The graphite content is preferably 5 to 30% by weight. A more preferred content is 10 to 24% by weight.

By limiting the graphite content to the above range, corrosion resistance, oxidation resistance and hot strength can be improved.

As raw materials for granulated products other than zirconia, silicon carbide, metal powder and graphite, alumina, mullite and silica can be used.

The graphite-based patching material has an overall chemical composition of 18.3 to 60.3% by weight of Al ₂ O ₃ and SiO ₂ 1
1.0 to 62.1 wt%, ZrO ₂ 5.4-12.3 wt%, 5-30 wt% of graphite, SiC1.2～3.6 wt%, and the metal Si0.49~1.1 wt% Preferably,

By limiting SiC and metal Si to the above ranges, it is possible to enjoy more excellent oxidation resistance.

By limiting ZrO ₂ to the above range, it is possible to reliably improve corrosion resistance.

For the granulated product, for example, a phenol resin is added to the above-mentioned raw material at an external ratio of about 5 to 25% by weight, and the kneaded material is subjected to a hydraulic press or a hydrostatic press (forming pressure 0.25 to 3.0 t / cm).
² ) A molded article can be obtained by calcining the molded article at 900 to 1100 ° C. and crushing the resulting calcined article to a particle size of 5 mm or less.

As a raw material of the graphite-based patching material other than the granulated product, silica sand having a particle size of 5 mm or less, alumina brick waste having a particle size of 5 mm or less, clay, and the like can be used.

At this time, the packing density is increased by reducing the particle size of silica sand and alumina brick debris to 5 mm or less.
Corrosion resistance can be increased.

Alumina brick waste is, for example, immersion nozzle,
It is cutting chips and the like that are generated when manufacturing a long nozzle. By using such cutting chips, it is possible to reduce the manufacturing cost.

[0023]

EXAMPLE As shown in Table 1, 35 to 80% by weight of the granulated product was used.
By blending, the graphite patch materials of Examples 1 to 7 were manufactured.

The granulated product was manufactured according to the procedure shown in FIG.

That is, phenol was added to 30% by weight of alumina, 9% by weight of mullite, 11% by weight of silica, 30% by weight of graphite, 15% by weight of zirconia, 3.5% by weight of silicon carbide and 1.5% by weight of metallic silicon powder. A resin is added at an external ratio of 20% by weight, and the kneaded product is pressed at a molding pressure of 2 t / cm ² to obtain a molded product, which is fired at 950 ° C., and the fired product has a particle size of 5 mm.
A granulated product was obtained as follows.

Using this granulated product, a graphite batching material was produced according to the procedure shown in FIG.

That is, 10 to 15% by weight of elutriated clay and 10 to 50% by weight of silica sand or 15 to 55% by weight of alumina brick waste are added to 35 to 80% by weight of the granulated product, and an appropriate amount of water ( Then, the mixture was kneaded with a mortar mixer, and subjected to a vacuum degassing / extracting machine to obtain a graphite patch material.

Silica sand having a particle size of 5 mm or less was used.

As the alumina brick waste, those having a particle size of 5 mm or less and those having a particle size of 0.5 mm or less were appropriately used.

When the chemical components of the graphite patch material thus obtained were examined, the numerical values shown in Table 1 were obtained.

For comparison, the patching materials of Comparative Examples 8 to 9 in which the ratio of the granulated product was 85 and 30% by weight outside the range of the present invention, and Conventional Examples 10 to 12 in which no granulated product was used, were substantially used. Was manufactured in the same procedure as above, and the chemical components were examined. Comparative Example 8
Tables 9 to 9 and Conventional Examples 10 to 12 are shown in Table 2.

Next, for the patching materials of Examples 1 to 7, Comparative Examples 8 to 9, and Conventional Examples 10 to 12, the required construction amount (k
g / m ³ ), the residual linear change rate (%), bending strength (MPa), and erosion index of 1500 ° C. × ³ hours were examined.

The erosion index of the patching material was 40 × 40 ×
Create a 160mm rectangular parallelepiped and cast on cast iron at 1500 ° C for 10
The erosion amount when immersed for one minute was evaluated by a value with the erosion amount in Comparative Example 9 being 100. Therefore, the smaller the value, the better the corrosion resistance.

Looking at the erosion indexes in Tables 1 and 2,
7 was confirmed to have better corrosion resistance than Comparative Example 9.

Comparative Example 8 has the same corrosion resistance as Examples 1 to 3 and 7, but when used as a repair material, it was recognized that it could fall off due to rapid heating.

In addition, all of Conventional Examples 10 to 12 were inferior in corrosion resistance to Comparative Example 9.

Next, a modification of the present invention will be described.

In Example 6, clay kneaded with a water content of 13%, for example, 0.25% of a plasticizer such as sodium alginate, for example, 0.02% of a time-delaying agent such as boric acid, was subjected to an extraction machine, and alumina-carbon was added. High quality plastic refractory can be obtained.

The alumina-carbon plastic refractory obtained in this way can be used as a plastic refractory which maintains the airtightness between the 70-ton ladle and the lid, for example.

It is also possible to mix clay, silica sand and alumina brick chips with the cutting chips of the immersion nozzle and the long nozzle, and to extract the mixture to produce a graphitic patching agent.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

The graphite-based patching material of the present invention has a high bondability between a carbon source and other raw materials, is excellent in corrosion resistance and oxidation resistance as compared with conventional products, and therefore has a long service life. Having.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a manufacturing process in an embodiment of the present invention, wherein (A) is a process for obtaining a granulated product,
(B) shows the subsequent steps.

Claims (5)

[Claims] 1. A granulated product obtained by kneading, shaping, and sintering a raw material containing zirconia, silicon carbide, metal powder, and graphite to a particle size of 5 mm or less, comprising 35 to 80% by weight. Graphitic patching material. 2. The composition according to claim 1, further comprising 20 to 65.
The graphite-based patching material according to claim 1, comprising one or more of clay, silica sand and alumina brick by weight. 3. The graphite-based patching material according to claim 1, wherein the graphite content is 5 to 30% by weight. 4. The overall chemical composition is Al ₂ O ₃ .
3 to 60.3 wt%, SiO ₂ 11.0~62.1 wt%, ZrO ₂ 5.4~12.3 wt%, SiC1.2~
The graphite-based patching material according to any one of claims 1 to 3, wherein 3.6% by weight, 0.49 to 1.1% by weight of metal Si and the balance are carbon. 5. The graphitic patching material according to claim 1, wherein the raw material of the granulated product contains one or more of alumina, mullite, and silica.