JPS61101454A - Aluminum oxynitride-containing 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 relates to an aluminum oxynitride-containing refractory that is highly resistant to pig iron, steel and slag.

With recent advances in ironmaking and steelmaking technology, refractories are being used under increasingly harsh conditions. In order to improve the durability of refractories, it is necessary that the refractories do not react with hot metal, molten steel, molten slag, etc. even when they come into contact with these molten materials. Therefore, manufacturing techniques such as high-pressure forming and homogeneous forming, etc. While results have been achieved through the development of new refractory materials, there are cases in which results can also be achieved by changing the quality of refractory raw materials, processing, and appropriate combinations of various raw materials, even with existing refractory raw materials. Fe in hot metal, molten steel, molten slag, etc.
It is known that as the O concentration increases, the erosion of refractories progresses significantly. Therefore, improving the corrosion resistance against FeO will lead to improving the durability of the refractory. Therefore, the Mg0-C system, Al t O! -C
Refractories such as A lz O3-S i CC type and A lz O3-S i CC type refractories have come to be manufactured.

However, Mg0-C refractories are susceptible to cracking and damage during repeated heating and cooling during furnace operation, so their uses are limited. In addition, Ah03-C series and AhOz
5iC-C refractories have poor corrosion resistance. A1□
Refractories that contain non-oxide raw materials such as silicon carbide, silicon nitride, or silicon oxynitride in refractories mainly composed of oxide raw materials, such as O, -3iC-C refractories, have excellent corrosion resistance and thermal shock resistance. However, when these non-oxide raw materials are oxidized, they become SiOz and easily react with molten metal, especially with FeO in molten metal and slag, so there is room for improvement. . When using existing refractory raw materials, there are many items that must be considered, such as the type of raw materials, quantity, quality, processing conditions, and combination with manufacturing technology, so it takes a huge number of days for development to achieve results. It involves costs.

Even with such efforts, there are many cases where sufficient durability against hot metal, molten steel, and molten slag cannot be obtained.

The present invention provides a refractory with high durability against hot metal, molten steel, molten slag, and the like. That is, the present invention is an aluminum oxynitride-containing refractory characterized by comprising 3 parts by weight or more of aluminum oxynitride, 0.5 to 60 parts by weight of carbon and/or a carbon compound, and the balance consisting of other refractory materials.

Aluminum oxynitride is a solid solution of aluminum nitride and aluminum oxide, and has high heat resistance (does not melt or decompose below 2000°C). It has characteristics such as poor chemical reactivity at high temperatures (especially excellent corrosion resistance to FeO), a lower coefficient of thermal expansion than refractory raw materials such as alumina, magnesia, and zirconia, and difficulty in reacting with various molten metals. Therefore, the present inventors have come to the conclusion that it is suitable as a raw material for refractories used in parts that come into contact with hot metal, molten steel, molten slag, etc., which require corrosion resistance and thermal shock resistance.

Aluminum oxynitride is a solid solution of aluminum nitride AIN and alumina Al z Ox (xAIN-yAhoe
) However, depending on the synthesis conditions, metallic aluminum, alumina, aluminum nitride, etc. may accompany aluminum oxynitride.

When used as a raw material in the present invention, it is desirable that aluminum oxynitride has high purity, but these accompanying substances may remain. As a raw material, it is better to have a small amount of metallic aluminum remaining, and if it is accompanied by alumina and aluminum nitride, it is better to use a raw material with aluminum nitride in view of the density, hardness, and chemical stability of the raw material. It is more preferable to use alumina.

Aluminum oxynitride is contained in an amount of 3 parts by weight or more.

If the content is 3 parts by weight or less, the above-mentioned effects will be small; as the content increases, the coefficient of thermal expansion of the refractory will decrease, the thermal volume stability will be excellent, and the corrosion resistance will improve. Carbon and carbon compounds are contained in an amount of 0.5 to 60 parts by weight.

Coke, globular graphite, scale graphite, etc. are used as carbon raw materials. Carbon compounds are binders for refractories such as tar, pinch, and resin, and become carbon through thermal decomposition or polycondensation. Carbon raw materials have corrosion resistance against hot metal, molten steel, molten slag, etc., have excellent thermal shock resistance, and are effective in suppressing oxidation of aluminum oxynitride. If the content of carbonaceous substances, carbon compounds, etc. is less than 0.5 parts by weight, the above-mentioned effects will not be exhibited, and if the content is more than 60 parts by weight, the performance of the aluminum oxynitride material will be diluted, and the quality of the carbonaceous material will deteriorate. It becomes close to.

Next, as the remaining refractory substances, non-oxide raw materials such as silicon carbide and silicon nitride, oxide raw materials such as zircon, zirconia, alumina, mullite, and magnesia, additives such as metallic silicon, ferrosilicon, and aluminum powder, Binders and binding aids such as aluminum phosphate, sodium silicate, clay, and water are used as necessary. When used in combination with silicon carbide powder, it prevents the oxidation of carbon in the refractory, and when silicon oxide oxidizes during use, it maintains the reducibility in the structure of the refractory, so it has the effect of suppressing the oxidation of aluminum oxynitride. be.

Next, an example will be explained.

Example 1 In Table 1, numbers 1 to 6 are examples of monolithic refractories of the present invention. The formulations using the raw materials shown in Table 1 were thoroughly mixed and then kneaded with water. Aluminum oxynitride was synthesized in a laboratory. FIG. 1 is its X-ray diffraction diagram.

In the figure, S represents aluminum oxynitride. These kneaded materials were placed in a mold with a trapezoidal cross-sectional area of 53 m on the base, 36 m on the top, and 201 m in height, and a length of 120 u. ) were poured into molds. After curing for 24 hours at a temperature of 20±5° C. and a humidity of 80 to 85%, it was removed from the mold. This was dried for 12 hours in a dryer maintained at 105 to 110°C, then buried in coke powder, heated to 350°C in an electric furnace, and held there for 4 hours to be fired. 350°C is the temperature at which water of crystallization and volatile substances disappear. The trapezoidal columnar fired body was used for the corrosion resistance test against molten metal.

A cylinder was made by attaching the fired body to the inside of a crucible in a high-frequency induction furnace with an output of 15 kW. Cast iron (Fe1
2), induction heating is started, and the cylinder temperature reaches 12.
When the temperature reached 00°C or higher, ferrous oxide (Fed) was added, and the temperature was raised to 1550°C to melt the contents. 155
The specimen was kept at 0° C. for 5 hours to react with the molten metal. After the molten metal was discharged and cooled, the joint specimens were taken out and the percentage decrease in thickness of the most eroded area was calculated to compare the corrosion resistance.

Regarding thermal shock resistance, the acoustic emission method (AE
The test was conducted using the following method. The acoustic emission method is a method that has recently been adopted as a method for evaluating the thermal shock resistance of refractories because it is easy to make quantitative comparisons. A2 uses a sensor to detect the elastic waves generated when the m-weave of an object breaks.
The generated amount is read and the thermal shock resistance is evaluated based on the amount. It is evaluated that the smaller the total amount of AE occurrence it (count number), the better the thermal shock resistance. JIS
A flame of oxygen-propane gas at about 1650° C. is applied to the center of the 230×115 m surface of the regular brick-shaped fired body for about 20 seconds to locally heat it. The total amount (count number) of the AE generated there is measured using a commercially available device (DUNGAN/ENDEV).
Read with CO company, MODEL 302A).

As shown in Table 1, compared to conventional products, the products of the present invention have significantly improved corrosion resistance, including resistance to ferrous oxide, which causes severe erosion and erosion of refractories, and It was found that the thermal shock resistance, which improves the resistance to tissue destruction of refractories caused by oxidation, has been greatly improved. If the composition does not contain carbon or carbon compounds, as in the case of the compound with A1, there is not much improvement in corrosion resistance, and if the proportion of carbon or carbon compounds is too high, as in the case with the compound with A5, the thermal shock resistance will deteriorate. Although it is good, there is not much improvement in terms of corrosion resistance.

Example 2 In Table 2, Nos. 1 to 3 are examples of shaped refractories of the present invention. After thoroughly mixing the formulations using the raw materials shown in Table 2, a binder was added and kneaded. The aluminum oxynitride having the same purity as in Example 1 was used. These kneaded products were molded into a trapezoidal column shape with the same dimensions as in Example 1 at a pressure of 600 kg/cd.The molded product was then buried in coke powder and heated at 1200 kg/cd in an electric furnace.
The temperature was raised to ℃ and held there for 4 hours to perform firing. Corrosion resistance and thermal shock resistance were tested using the same test method as in Example 1. As shown in the lower column of Table 2, it can be seen that the products of the present invention are superior in corrosion resistance and thermal shock resistance compared to conventional products. The products of the present invention shown in Table 2 are suitable for immersion nozzles for steel manufacturing.

Table 2 As mentioned above, the refractory of the present invention has excellent corrosion resistance and thermal shock resistance against hot metal, molten steel, and molten slag, so it can be used as a refractory lining material that comes into contact with these molten metals, and can be used in blast furnaces. tension materials, tap trough materials, hot metal ladles, pig iron mixing cars,
It can be used for a wide range of purposes, including tanditshu, immersion nozzles, and tapping gutter material.

[Brief explanation of drawings]

FIG. 1 is an X-ray diffraction diagram of aluminum oxynitride. Figure 1: JEG Procedures Master's Book (Volunteer) 1. Indication of the case 1982 Patent Application No. 222486 2 Title of the invention Aluminum oxynitride-containing refractory 3 Relationship to the case by the person making the amendment Patent application Office 1-21-3 Ebisu, Shibuya-ku, Tokyo two
Hong Le Pot name Nippon Crucible Co., Ltd. (1) In the 8th line from the 6th bottom,
"Trapezoidal cross section" is corrected. (2) In the beginning of page 7, line 9, "common specimen" is corrected to "test specimen." Also, in line 111 of the same page, ``output'' is corrected to ``calculation.'' (3) Add the following text after Table 2 on page 11. "Example 3 In Table 3, numbers N11 to 3 are examples of fillers for blast furnace tap hole plugging of the refractories of the present invention. Compounds using the raw materials shown in Table 3 were mixed well. After that, a binder was added and kneaded. The aluminum oxynitride used had the same particle size as in Examples 1 and 2. These kneaded products were molded into trapezoidal columns with the same dimensions as in Example 1.
It was molded at a pressure of kg/c+a. This is 105-110
The sample was dried for 12 hours in a dryer kept at .degree. C., then heated to 350.degree. C. at a rate of 150.degree. C./hr in an electric furnace, and kept there for 6 hours for baking treatment. These heat-treated specimens were attached to the inside of a normal rotary erosion test furnace to form a tube. After rapidly preheating the cylindrical surface of the specimen to 1500°C using an oxygen/propane gas burner, it was heated to 1,500°C using an oxygen/propane gas burner.
．． 22 blast furnace slags were charged into the cylinder at a weight ratio of 1O:3. The furnace was rotated at 3 Orpm while being heated with a burner so as to maintain the cylinder temperature at 1550±20° C., and the specimen, molten metal, and molten slag were reacted. After a reaction time of 2 hours, the molten material in the cylinder was discharged. Subsequently, the same material as above was reacted with the specimen under the same conditions and then discharged. After repeating this 4 times,
The amount of erosion on the specimen was measured. Corrosion resistance was compared by calculating the rate of decrease in thickness of the most eroded part of the specimen. As shown in the lower column of Table 3, it can be seen that the product of the present invention has superior corrosion resistance compared to the conventional product. By introducing aluminum oxynitride in place of fused alumina, we were able to improve the corrosion resistance of the filler for plugging blast furnace tapholes, thereby significantly improving its durability, as shown in Table 3. The following is an example of this.The product of the present invention can be applied not only to blast furnace tap holes, but also to plugging fillers in general, including tap holes of general metallurgical furnaces such as electric furnaces. Although this example uses anhydrous coal tar as the binder, other binders such as thermosetting resins may also be used.Table 3 and above

Claims (1)

[Claims] An aluminum oxynitride-containing refractory comprising 3 parts by weight or more of aluminum oxynitride, 0.5 to 60 parts by weight of carbon and/or a carbon compound, and the balance consisting of other refractory substances.