KR20010060405A - Compositions of Alsica brick - Google Patents

Abstract

PURPOSE: An alsica refractory brick composition having excellent oxidation resistance even in the range of low temperature together with high temperature is provided, which can produce an alsica refractory brick having oxidation resistance capable of being used for a hot metal mixer car as a hot metal vessel. CONSTITUTION: This alsica refractory brick composition contains 100 parts by weight alsica fireproof material containing alumina, silica carbide and carbon; 3 parts by weight of metal silica powder containing Al, Si and Mg-Al; and 0.3 to 1.0 parts by weight of composite oxide containing 20 to 25% by weight of Na2O, 60 to 65% by weight of P2O5 and 10 to 15% by weight of B2O3.

Description

Alsica refractory brick composition {Compositions of Alsica brick}

[TECHNICAL FIELD OF THE INVENTION]

The present invention relates to an Alsica refractory brick composition, and more particularly, (a) alumina (Al ₂ O ₃ ), silicon carbide (SiC), and the like, which have excellent oxidation resistance that can be used in a molten iron container or a molten iron ladle. Alsica refractory containing carbon (C), (b) 3 parts by weight of the metallic silicon powder containing Al, Si and Mg-Al, and (c) 20 to 25% by weight of Na ₂ O, 60 to P ₂ O ₅ It relates to an Alsica refractory brick composition comprising 0.3 to 1.0 parts by weight of a composite oxide containing from about 65% by weight to about 10% by weight of B ₂ O ₃ .

[Private Technology]

The refractory material used in the crossroad car is mainly composed of Al ₂ O ₃ -SiC-C fluorine refractory bricks (hereinafter referred to as "alsica refractory bricks"). It is very important to improve the oxidation resistance because these alicycyl refractories contain carbon. Therefore, metal powders (Al, Si, Al-Mg), carbides (B4C), low-melting composite oxides (borosilicate frits), etc., which are antioxidants, have the purpose of enhancing oxidation resistance against alumina-silicon carbide-carbon refractory materials. It is used.

However, as a result of several oxidation tests on the existing low melting point composite oxides, the antioxidant effect is clearly seen in the high temperature region of 1400 ° C., but the oxidation resistance of carbon is insufficient in the low temperature range of 800 to 1000 ° C.

Therefore, there is a problem that the refractory damage is severe due to the oxidation proceeds when the temperature increase of the crossroad car for the repair of water, or during the repair atmosphere.

SUMMARY OF THE INVENTION In order to solve the problems of the prior art, an object of the present invention is to provide an alsica refractory brick composition having excellent oxidation resistance in a low temperature region as well as a high temperature region.

In order to achieve the above object, the present invention (a) 100 parts by weight of alsica containing alumina (Al ₂ O ₃ ), silicon carbide (SiC) and carbon (C), (b) Al, Si and Mg-Al 3 parts by weight of the metal silicon powder containing (c) 20 to 25% by weight of Na ₂ O, 60 to 65% by weight of P ₂ O ₅ and 10 to 15% by weight of B ₂ O ₃ 0.3 to 1.0 It provides an Alsica refractory brick composition comprising a weight part.

Hereinafter, the present invention will be described in detail.

Since Alsica refractory bricks contain about 10 to 15% by weight of carbon, the oxidation prevention of carbon is very important in order to exhibit the property of having low wettability against molten iron or slag as a refractory and excellent resistance to infiltration and corrosion. to be. The inventors conducted several oxidation tests on borosilicate frit additives that were previously added to prevent oxidation of Alsica refractory bricks. However, the present inventors clearly showed an anti-oxidation effect at a high temperature region of 1400 ° C., but at a low temperature of 800 to 1000 ° C. In the region, the antioxidant effect of carbon was insufficient. The antioxidation effect is obvious at high temperatures because the metal powder and silicon carbide react with carbon or CO gas to reprecipitate carbon, or the composite oxide is melted to react with alumina or silicon carbide to form a dense layer of softened surface. Therefore, it was confirmed that oxidation of carbon is suppressed, and the present inventors have found that phosphate-based frit can be melted even in a low temperature region to prevent oxidation of Alsica soft brick, thereby completing the present invention.

Table 1 below shows the chemical composition of the borosilicate frit used as an antioxidant and the phosphoric acid composite oxide of the present invention as an antioxidant.

TABLE 1

Unit: weight% SiO ₂ Al ₂ O ₃ B ₂ O ₃ CaO MgO PbO Na ₂ O P ₂ O ₅ Borosilicate 60 10 15 5 One 4 5 - Phosphate - - 10 - - - 20 70

Table 1 shows that the borosilicate frit contains a large melting point material (SiO _2, Al ₂ O ₃ ), and the phosphate frit used in the present invention contains a large amount of P ₂ O ₅ .

Table 2 summarizes the softening state of the frit when the borosilicate frit and the phosphate frit are heat treated at different temperatures. In the above, each frit specimen was a pellet of 10 mm × 10 mm (diameter).

TABLE 2

Heat treatment temperature (℃) Borosilicate frit Phosphate Frit 500 No change Melting start 600 No change 15 mm diameter 700 No change 20 mm diameter 800 20% shrinkage 27 mm diameter (spread)

Table 2 shows that even when the borosilicate frit is 800 ° C., only the plastic shrinkage proceeds but no melting occurs, but the phosphate frit melts from 500 ° C. From the above results, it can be seen that the phosphate-based frit melts at a low temperature to cover the surface of the surrounding carbon particles to prevent oxidation of carbon from the outside atmosphere.

In addition, in order to investigate the effect of inhibiting the oxidation of the borosilicate frit and the phosphate frit, 100 wt% of Alsica refractory brick composition including 60 wt% of alumina (Al ₂ O ₃ ), 20 wt% of silicon carbide (SiC), and 20 wt% of graphite 10 parts by weight of the two kinds of frits are added to each part, and the phenol resin, which is a binder, is kneaded with a binder, and then a specimen is prepared at 1 ton / cm ² , and subjected to an oxidation test at each temperature. After the calculation is shown in Table 3. In addition, as a reference example, the specimen was prepared in the same manner as above without addition of the frit and subjected to oxidation test.

[Calculation 1]

Weight loss rate = {(W ₁ -W ₂ ) / W ₁ } × 100

In the above formula, W ₁ is the initial weight of the specimen before the oxidation test, W ₂ is the weight of the specimen after the oxidation test.

TABLE 3

No addition Borosilicate frit addition Phosphoric acid frit addition 800 ℃ × 2 hours 11.2 10.3 4.6 1000 ℃ × 2 hours 16.3 13.0 2.7 1200 ℃ × 2 hours 16.9 4.8 3.8

As can be seen in Table 3, it can be seen that the frit-added product is improved in oxidation resistance compared to the frit-free. In the case of the dispersoid-based frit, the oxidation resistance was clearly improved at 1200 ° C. or higher, but did not show a great effect at a temperature below that. On the other hand, the phosphate frit having a low softening point can be seen that the oxidation inhibitory effect is apparent even at a temperature below 1000 ℃.

In addition, the Alsica refractory brick composition of the present invention comprises a metal silicon powder containing Al, Si and Mg-Al. The metal silicon powder acts as an antioxidant together with the phosphoric acid-based composite oxide. In the Alsica refractory brick composition of the present invention, the amount of the metal silicon powder is used based on 100 parts by weight of the Alsica refractory containing alumina (Al ₂ O ₃ ), silicon carbide (SiC) and carbon (C). It is preferable to use 3 parts by weight of powder.

In addition, the Alsica refractory brick composition of the present invention may include additives that are commonly used in the manufacture of Alsica refractory bricks, in addition to the Alsica refractory, metal silicon, and phosphate complex oxides. Binders.

Hereinafter, examples of the present invention will be described. However, the following examples are intended to illustrate the invention and the present invention is not limited to the following examples.

Example 1

3 parts by weight of metal silicon, 0.3 parts by weight of phosphoric acid-based composite oxide and 4 parts by weight of phenolic resin as binders were added to 100 parts by weight of an alsica refractory containing 75% by weight of alumina, 10% by weight of silicon carbide, and 15% by weight of carbon. After kneading, the Alsica refractory brick was manufactured by molding at a constant pressure.

Example 2 and Comparative Examples 1 to 3

The same method as in Example 1 was used except that the type and amount of the composite oxide was changed as described in Table 4 below.

[Experiment 1]

The specimens prepared according to Examples 1 and 2 and Comparative Examples 1 to 3 were dried at 250 ° C., and their oxidation resistance and erosion resistance were measured at each temperature, and are shown in Table 4 below. Oxidation test in the above was maintained for 3 hours at each temperature using a gas furnace and cooled to compare the thickness of the oxide layer was expressed as an index. In addition, the erosion was carried out for 1 hour at 1500 ℃ using an induction furnace, the molten iron and cross-talk slag was used as an erosion agent.

TABLE 4

Example Comparative example One 2 One 2 3 Al ₂ O ₃ 75 75 SiC 10 10 C 15 15 Metal silicon powder +3 +3 Complex oxide Borosilicate frit - - +1 - - Phosphate Frit +0.3 +1.0 - +0.2 +1.2 Oxidation index 1000 ℃ × 3hr 90 70 100 100 60 1400 ℃ × 3hr 80 62 100 108 65 Erosion Index 85 90 100 100 120

In Table 4, Comparative Example 1 was added to the existing borosilicate-based frit, the oxidation resistance at high temperature was similar to that of the example, but it was found that there is no antioxidant effect at low temperature.

In Table 4, Comparative Examples 2 and 3 are used when the amount of phosphate-based frit is out of the preferred range, Comparative Example 2 can be seen that the oxidation resistance is not enhanced by adding too little phosphate-based frit, Comparative Example 3 When too much phosphate-based frit is added, the oxidation resistance is excellent, but the corrosion resistance of Alsica refractory brick is inferior due to the excessively low melting point product.

Examples 1 and 2 in Table 4 show excellent oxidation resistance without deterioration of erosion resistance.

₃ parts by weight of the metal silicon powder containing Al, Si and Mg-Al with respect to 100 parts by weight of the Alsica refractory containing alumina (Al ₂ O ₃ ), silicon carbide (SiC) and carbon (C) as described above And refractory bricks are prepared by adding 0.3 to 1.0 parts by weight of a composite oxide containing 20 to 25% by weight of Na ₂ O, 60 to 65% by weight of P ₂ O ₅ , and 10 to 15% by weight of B ₂ O ₃ . It is possible to produce an alsica refractory brick having excellent oxidation resistance as well as in the low temperature region.

Claims (1)

(a) 100 parts by weight of an Alsica refractory containing alumina (Al ₂ O ₃ ), silicon carbide (SiC) and carbon (C); (b) 3 parts by weight of a metal silicon powder containing Al, Si and Mg-Al; (c) 0.3 to 1.0 parts by weight of a composite oxide containing 20 to 25% by weight of Na ₂ O, 60 to 65% by weight of P ₂ O ₅ , and 10 to 15% by weight of B ₂ O ₃ ; Alsica refractory brick composition comprising a.