JPS5849669A - Anticorrosive indefinite form refractories - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a monolithic refractory having excellent corrosion resistance and used in steel works as a material for blast furnace troughs, taphole fillers, etc.

The applicant disclosed silicon nitride in Japanese Patent Application Laid-open No. 56-26776.
We have proposed a material characterized by using an alumina-based or silicon nitride-iron-alumina-based sintered body as the aggregate and/or matrix of a monolithic refractory. Although this material has superior corrosion resistance when compared to conventional monolithic refractories, there are still points to be improved.

In other words, since silicon nitride-alumina sintered bodies contain a considerable number of pores, they have some problems in corrosion resistance when used as aggregates for monolithic refractories. Although the system sintered body contains a considerably large amount of iron, it can be obtained as a dense sintered body, but there remains a problem in terms of corrosion resistance.

The present invention aims to improve the shortcomings of conventional monolithic refractories or raw materials thereof, and to provide monolithic refractories with greater corrosion resistance.

The inventors have discovered that clay, like waxite, Sin, and AAzO
Sialon obtained by mixing and molding a clay silicate raw material whose main component is J and carbon powder and heating it in a nitrogen atmosphere, and Tiaron sintered obtained by pulverizing and molding this sialon and sintering it at a high temperature. Focusing on the fact that the body (hereinafter referred to as sialon sintered body) is extremely dense and has excellent corrosion resistance,
It was discovered that fire resistance can be improved when these are used in a refractory with a variable expansion surface, leading to the present invention. Sialon and its sintered body obtained by the method described above are
A denser sintered body is obtained than the conventional A40a-5fsN4-based sintered body obtained by sintering a mixed molded body of silicon nitride and alumina. This is thought to be due to the effect of trace amounts of impurities contained in the raw materials. Therefore, by using such sialon and its sintered body as structural particles of a refractory, corrosion resistance can be improved due to its denseness. Furthermore, the Sialon and Sialon sintered body used as the aggregate and/or matrix of the monolithic refractory of the present invention are silicon nitride iron-alumina based sintered bodies obtained by firing a mixed molded product of silicon nitride iron and alumina. Sialon and Sialon sintered compacts with comparatively large particle sizes, as described below, have a significantly lower iron content than those of monolithic refractories. By using it as a material, its corrosion resistance can be significantly improved, but by using Sialon and Sialon sintered bodies with relatively small particle sizes as a matrix, its corrosion resistance can be further improved. In this case, it is preferable to use a matrix obtained by finely pulverizing a sialon sintered body, but a fine powder obtained by heating a molded mixture of a clay silicate raw material and carbon powder in a nitrogen atmosphere is preferable. The present invention will be described in more detail below.

Monolithic refractories are generally made of aggregate particles such as alumina, magnesia, mullite, silicon carbide, zircon, chamotte, waxite, silica, coke, and graphite, and alumina, magnesia,
It consists of fine powder such as mullite, silica, clay, coke, silicon carbide, etc., and if necessary, pitch, tar, 1aJN or sodium silicate,
Binders such as lignin sulfonic acid, phosphates, and alumina cement are blended and molded, but erosion due to hot metal, molten steel, or hot metal slag ζ progresses mainly because the matrix portion is preferentially eroded. Conceivable. That is, clay and other matrix materials are added to sinter the aggregates such as alumina and silicon carbide, and this is said to be because the corrosion resistance of this matrix material is inferior to that of the aggregates. In addition, aggregates with poor corrosion resistance are also used.

The above-mentioned monolithic refractories are generally used in pig iron and steel manufacturing, and include (1) castable, (plastic), and (3)
It is classified as mortar, seepage ramming material, etc., and a molding method is adopted that is suitable for each material.

For example, blast furnace tap runners are generally made of a mixture of aggregate particles such as alumina, mullite, silicon carbide, and graphite, and fine powders such as coke, clay, and silicon carbide. It is used as a ramming material or a casting material.

For example, mud for tapholes in blast furnaces is generally made of materials such as alumina, chamotte, silica, waxite, silicon carbide, coke, and clay mixed with binders such as tar and resin. It is used to fill and close the taphole using an electric or hydraulically operated mud gun at the front of the furnace to stop hot metal and molten slag flowing out.

Oxide-based materials such as alumina, mullite, and chamotte have poor sinterability with silicon carbide, and cannot provide sufficient strength even at high temperatures. Therefore, there is a problem in terms of wear resistance against hot metal flow, and the excellent characteristics of aggregates such as silicon carbide cannot be fully utilized. Among the aforementioned aggregates, there are
Some materials have low corrosion resistance against slag.
□In view of the problems of conventional monolithic refractories as described above, the present invention has been developed by using an appropriate amount of sialon and sialon sintered bodies, which have excellent mechanical strength, corrosion resistance, and sintering properties, into ordinary undersized refractories. The present invention provides a monolithic refractory which has high mechanical strength and excellent corrosion resistance and is added as a refractory aggregate and/or matrix.

The monolithic refractory of the present invention is an ordinary monolithic refractory made of one or more of alumina, magnesia, mullite, chamotte, waxite, silica, clay, coke, graphite, silicon carbide, and zircon. Particle size of oy and/or Sialon sintered body5. J6- A monolithic refractory with high mechanical strength and excellent corrosion resistance, in which 5 to 70 weight 5C of the following particles are added.

As mentioned above, the Sialon or Sialon sintered body used here is 5iO2-A such as clay or waxite.
A material obtained by adding a predetermined amount of carbon powder to the raw materials of the go system, mixing and molding it, and then heating it in a nitrogen atmosphere, or a material obtained by pulverizing this, re-forming, and sintering, s
i % hts O % It is a complex solid solution material consisting of N and other inevitable elements derived from the raw materials. especially,
Sialon sintered bodies exhibit high mechanical strength and excellent corrosion resistance, and also combine the unique properties of silicon nitride and alumina. Among the constituent components of Sialon, the silicon nitride component acts as a bond for silicon carbide, which is used as a component of the aggregate of ordinary refractories.
The alumina component also acts as a bond for other oxides as aggregate. In this way, since both silicon carbide and oxide have a great bonding effect, the two, which are difficult to sinter using normal methods, are well bonded together.

Therefore, when fine powder of such sialon-based substances is added, it undergoes heat treatment with hot metal or bath molten slag, and it strongly binds silicon carbide, alumina, mullite, etc. used as aggregates, and it itself does not react with hot metal or molten slag. Since it has excellent corrosion resistance against slag, it exhibits much better corrosion resistance than conventional deficient refractories that use clay as a matrix. In addition, as mentioned above, Sialon and Sialon sintered bodies have greater corrosion resistance against hot metal and slag than conventional silicon nitride iron-alumina or silicon nitride-alumina sintered bodies, so the monolithic refractories concerned By using it as an aggregate, corrosion resistance can be further improved.

In the present invention, among the particles of Sialon or Sialon sintered body with a particle size of 5H or less added to the ordinary monolithic refractory, fine powder with a particle size of 0.1u or less is added to mainly form a matrix, or Intermediate and coarse particles with a particle size of 0.1 to 5H are added to mainly form aggregate, or a mixture of fine, intermediate and coarse particles with a particle size of 5U or less is added to form aggregate and ma) IJ Whether or not to form a rack may be appropriately selected by taking into account the place where the deficient refractory is used, its purpose, and other conditions.

In the present invention, Sialon or its sintered body can be used in any particle size range from coarse particles to fine particles, but when used as coarse particles or intermediate particles, the particle size should be 0.1 m or more and 5 u or less, and the amount added is preferably in the range of 10 to 6ON. If it is less than 10, there is no effect of improving corrosion resistance;
This is because if it exceeds X, close packing cannot be obtained due to the particle size structure. In addition, when used in the fine powder part, either Sialon powder or Sialon sintered body stage may be used, and the particle size is 0.1
m or less, and the amount added is preferably in the range of 5 to 30%. This is less than 5X, which has no effect on corrosion resistance, and 30%
If the amount exceeds 0, the filling properties will deteriorate.If coarse particles, intermediate particles, and fine particles are used together (less than 5 particles), the total amount will be 10 to 70.
It is preferable to use the range of %. In either case, any other fireproof material may be used, but the smaller the amount of clay, the better.
Effective in terms of corrosion resistance and hot strength.

9- Next, the present invention will be specifically explained based on examples.

[Example 1] 40% by weight of coarse grains of 5-IM, 25% of intermediate grains of 1-0.1M
Part of the aggregate and fine powder (matrix) is replaced with a gutter material consisting of 35% by weight of fine powder of 0.1 m or less, □Silicon nitride-aluminum sintered body (alumina 50X) or Sialon sintered body. Add an appropriate amount of bangu to the mixture substituted with aggregates, knead the mixture, and pressurize the mixture into 40×40
The physical properties of the material were determined by molding it into a size of 60++w with 1'OOb/cr/I and calcining it in coke pleat at a temperature of 1400°C for 2 hours each.

Further, using both blast furnace slag and pig iron, an erosion test was conducted for 1 hour at 15 a.m. using a rotary erosion tester. These results are shown in Table 1.

As is clear from this table, gutter materials using sialon sintered bodies have greater strength than conventional sintered silicon nitride-alumina sintered bodies at both room temperature and 1400°C. Among them, the increase in hot strength is remarkable, which shows that the sintered body is in good condition.In terms of 4-corrosion resistance, the amount of erosion is reduced to 60-70% compared to the conventional product, which shows that the sintered body is in good condition. I got the results.

Table 1 Note: Corrosion Resistance 1 3,007 slag and 3,007 grams of pig iron each were charged into the hollow part of a hollow regular hexagonal columnar test piece group consisting of 6 test pieces, and the test piece group was rotated (6 rpm). 1 slag and pig iron
The specimens were heated and melted at 530° C. for 1 hour, and the erosion i of each specimen was expressed as a numerical value, with the conventional example being 100.

[Example 2] A taphole mud consisting of 20% by weight of coarse particles of 3 to IM, 40% by weight of intermediate particles of 1 to 0.1+c++, and 40% by weight of fine particles of 0.1 m or less was used to produce 1 fine powder (matrix). Approximately 20X of tar is added externally to a mixture in which a portion of the material is replaced with fine powder of silicon nitride iron-alumina sintered body (alumina 45X), Sialon or Sialon aggregate, and the mixture obtained by kneading is hand-pounded. Mold it and heat it in Fuchs Breeze for 80 minutes.
Sintering was carried out at a temperature of 0° C. for 2 hours. Its physical properties and the results of erosion tests with both blast furnace slag and pig iron conducted in the same manner as in Example 1 are shown in Table 2. As is clear from this table, those to which fine powder of Sialon or Sialon sintered body is added have greater strength than those to which fine powder of silicon nitride iron-alumina sintered body is added, and the increase in hot strength is remarkable. It can be seen that the sintered body is in good condition. The amount of erosion of the inventive product is 5 to 85% compared to the conventional product.
〇13- Table 2 14- Sialon synthesized from the aminosilicate of the present invention and carbon powder or As is clear from the above examples, the deficient refractory added with the Zialon sintered body obtained by sintering this Sialon powder has greater mechanical strength than conventional products (, Due to its excellent corrosion resistance against slag, it is used in the field of monolithic refractories, which were previously used.
It is possible to significantly improve service life, develop new fields of use, and make a significant contribution to saving materials and labor.

Patent applicant: Kawasaki Steel Corporation Showa Denko Co., Ltd. Kawasaki Rozai Co., Ltd. Agent Patent Attorney Minoru Watanabe 15- 381-

Claims (1)

[Claims] Sialon obtained by heating a mixture of clay silicate powder and carbon powder in a nitrogen gas atmosphere and/or a sialon sintered body obtained by sintering the sialon are used as aggregates and silica or matrix. A monolithic refractory with excellent corrosion resistance.