JPH01122972A - Unburned shaped refractory - Google Patents

Abstract

PURPOSE:To improve spalling resistance and bending strength by adding specific amounts of carbon fibers and aluminum or its alloy fibers whose diameters and lengths are specified respectively in an unburned shaped refractory containing refractory aggregate. CONSTITUTION:(A) 100pts.wt. of refractory aggregate such as silica or alumina, (B) an organic binder such as a phenolic resin, (C) 0.5-10pts.wt. of carbon fibers of 0.005-0.5mm diameter and 1-15mm length, (D) 0.5-10pts.wt. of metal lic fibers made of aluminum or its alloy of 0.005-0.5mm diameter and 1-15mm length, are mixed so that the total of components (C) and (D) is 1-15pts.wt. to form the subject unburned shaped refractory product. The product is espe cially excellent in the strength and spalling resistance in a low-temperature range from 200-600 deg.C and an intermediate temperature range from 600-1,000 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to low temperature ranges of 200 to 600°C and
The present invention relates to an unfired, shaped, durable material that has particularly improved strength and spalling resistance in the intermediate temperature range of 00°C.

Conventional technology and its problems Unfired shaped refractories made of refractory aggregate and organic binder are less prone to cracking, and even if cracks do occur, cracks are less likely to spread than fired bricks. , has a certain degree of spalling resistance.

However, for special refractories such as plate bricks of sliding nozzles (hereinafter referred to as SN) used for controlling the flow rate of molten metal flow, physical and chemical erosion effects due to rapid thermal shock and wear caused by the molten metal flow occur. Therefore, a higher degree of spalling resistance and corrosion resistance is required.

Carbon has excellent slag resistance, high thermal conductivity (and low coefficient of thermal expansion, so it has excellent spalling resistance, and this property can be used when mixed or combined with base materials. Therefore, materials that require strong spalling resistance often contain carbon.

Organic binders are broadly classified into two types: thermoplastic resins that soften and melt as the temperature rises, and thermosetting resins that harden as the temperature rises. The unfired refractories bonded with the former have 100~
Because the binder softens and melts at a temperature of 300°C, the strength decreases, and those bonded at the latter temperature are
Because the resin carbonizes at a temperature of , the strength decreases.

In order to suppress the decrease in strength in such low temperature ranges (200 to 600 °C) and intermediate temperature ranges (600 to 1000 °C), fine metal powders such as aluminum and aluminum alloys are added. Japanese Patent Publication No. 54-1639
Such examples can be found in No. 13, Japanese Patent Application Laid-open No. 107749/1983, and the like.

Furthermore, attempts have been made to add thin wires (fibers) made of aluminum or aluminum alloy as a means of suppressing the decrease in strength in the intermediate temperature range, improving spalling resistance, and preventing peeling wear due to cracking. For example, JP-A-6
Such techniques are described in Japanese Patent Application Publication No. 1-136966, Japanese Patent Application Laid-open No. 146773/1983, and the like.

However, by adding metal powder or metal fiber such as aluminum or aluminum alloy, intermediate temperature (60
Although considerable effects have been recognized in improving strength and corrosion resistance in the high temperature range (1000°C or higher) from 0 to 1000°C, unlike SN plate bricks, it does not only have corrosion resistance and spalling resistance, but also For refractories with severe usage conditions that require a high degree of dimensional accuracy,
The improvement in effectiveness is still insufficient in terms of preventing the occurrence of cracks and the propagation of cracks that have occurred.

Means for Solving the Problems The present inventor has developed an unfired refractory that exhibits high mechanical strength and excellent corrosion resistance in a wide temperature range from low to high temperatures, and has significantly improved spalling resistance. In order to obtain this, we have conducted various studies.

As a result, a mixture of refractory aggregate and organic binder contains aluminum or aluminum alloy fibers of a certain size and carbon fibers (carbonaceous or graphitic fibers).

The present inventors have discovered that the objective can be achieved by adding the same ingredients (the same applies hereinafter), and have completed the present invention.

That is, the present invention provides an unfired shaped refractory containing a refractory aggregate and an organic inder, which has a diameter of 0.005 to 0.5 mm and a length of 1 to 100 mm, based on 100 parts by weight of the refractory aggregate.
0.5 to 10 parts by weight of 15 mm carbon fiber and 0.5 to 10 parts by weight of a metal fiber made of aluminum or aluminum alloy with a diameter of 0.005 to 5 mm and a length of 1 to 15 mm (however, both fibers The present invention provides an unfired shaped refractory characterized in that the total amount is 1 to 15 parts by weight.

The refractory aggregate used in the present invention is not particularly limited, and includes oxides such as silica (SiO2), alumina (Al2O2), zirconia (ZrO2), magnesia (MgO), and lime (CaO), and compounds thereof. and mixture; 5iC1Tics B4 C-s Si3N4,
AΩN5TiN.

Carbides, nitrides, and borides represented by BN and ZrB2, as well as their compounds and mixtures, graphite (including natural graphite such as scale graphite and globular graphite, and artificial graphite such as pi-sotic coke and needle coke) Any known materials such as carbon materials such as amorphous carbon and the like can be used.

The organic binder is also not particularly limited, but thermosetting resins with a large amount of residual carbon are preferred, and phenolic and furan resins are more preferred in terms of cost. The amount used is not particularly limited, but it is usually about 2 to 10 parts by weight per 100 parts by weight of the total amount of fire-resistant needle material, carbon fiber, and metal fin wood.

Aluminum alone or aluminum and silicon (Si)
), copper (Cu), magnesium (Mg), zinc (Zn)
, tin (Sn), chromium (Cr), -=-nickel (Ni
), barium (Ba), lead (Pb), etc. Metallic fibers made of alloys or intermetallic compounds can be straight, curved,
It can be used in various shapes such as chevron, wave, etc. The thickness of the metal fiber is suitably in the range of 0.005 to 0.5 mm in diameter. If the thickness is less than 0.005 mm, it will be difficult to disperse it into the formulation, and if the thickness exceeds 0.5 mm, no significant improvement in spalling resistance can be expected.

The appropriate length of the metal fiber is 1 to 15 mm.

If the length is longer than 15 mm, the fibers become entangled with each other, making it difficult to uniformly disperse them into the clay or brick composition.
This results in a decrease in spalling resistance and also in filling properties. - On the other hand, if it is shorter than 1 mm, it will not sufficiently contribute to improving the spalling resistance. The amount of metal fiber added is 0.5 to 100 parts by weight of the fireproof equipment.
The amount is 10 parts by weight. This amount is 0. Less than 5 parts by weight,
Sufficient strength and spalling resistance cannot be obtained. On the other hand, 1
If it exceeds 0 parts by weight, the ratio of metal fibers in the matrix increases, and the improvement in spalling resistance becomes less noticeable, and furthermore, mixing or kneading becomes difficult, making it difficult to obtain bricks of good quality. Become.

The carbon fiber may be PAN-based, pitch-based, carbon-based, or graphite-based, but is preferably a high-strength type. The wire diameter may be within the range of 0.005 to 0.5 mm for the same reason as in the case of the metal fiber, and commercially available ones can be used. The length of the carbon fiber is suitably 1 to 15 mm, similar to the aluminum fiber. If the length is longer than 15 mm, the fibers become entangled with each other, making it difficult to uniformly disperse them into the clay. On the other hand, if it is shorter than 1 mm, it hardly contributes to improving the strength and spalling resistance. The appropriate amount of carbon fiber to be added is 0.5 to 10 parts by weight per 100 parts by weight of the fire-resistant aggregate. If it is less than 0.5 part by weight, sufficient strength cannot be obtained,
If it exceeds 10 parts by weight, the amount of fibers in the matrix becomes too large, making it difficult to uniformly disperse the fibers in the clay, making it impossible to obtain bricks of good quality.

The amounts of these aluminum metal fibers and carbon fibers added are as follows:
A total amount of 1 to 15 weights is appropriate, and the upper and lower limits are determined on the same basis as in the case of adding aluminum fiber and carbon fiber alone as described above.

In the present invention, the above-mentioned formulation and further, if necessary,
For example, carbon, aluminum (Aρ), silicon (
Metal powder of Si), magnesium (Mg), zinc (Zn), and alloys thereof with a particle size of 0.5 mm or less can be added in an amount of 1 to 15 parts by weight per 100 parts by weight of the refractory aggregate.

This makes it possible to more effectively prevent a decrease in strength in the intermediate temperature range of 600 to 1000°C.

Effects of the Invention According to the present invention, an unfired shaped refractory which has excellent spalling resistance and whose strength decreases little from a low temperature range to a high temperature range can be obtained.

In addition, aluminum, which is an optionally added component, produces alumina (Ag2O3), which is a typical fire-resistant material, when oxidized, and carbon has excellent slag resistance, so these added components are effective against spalling. This contributes not only to improving properties but also to improving corrosion resistance.

EXAMPLES Hereinafter, examples will be shown to further clarify the features of the present invention.

Examples 1 to 7 and Comparative Examples 1 to 5 Alumina-carbon blends shown in Table 1 (parts by weight)
were mixed and kneaded, and this was pressed into a 1000 m
114mmx230mm at kg/cm2 pressure
After molding to 45 mm x 45 mm, it was heated to 220
A sample was prepared by drying at ℃ for 24 hours.

The results are also shown in Table 2.

As is clear from Table 2, the example product had a bending strength of 150 kgf/cm at all of the tested temperatures.
2 or more, and has excellent corrosion resistance and spalling resistance.

The aluminum fiber used has a diameter of 0.01
The carbon fiber had a diameter of 0.09 mm and a length of 3 mm.

Note 1) For tests at 500°C, 1000°C, and 1400°C, the sample embedded in coke pleat was sent into a tunnel electric furnace, held at a predetermined temperature for 30 minutes, and then measured using the three-point method.

Note 2) 30 mm x in hot metal kept at 1600℃
A test specimen cut to 30 mm x 230 mm was immersed for 3 minutes and air cooled for 15 minutes three times, and after measuring the elastic modulus of the test specimen, it was divided into two equal parts in the length direction and cracks in the cross section were observed. O: Fewer cracks, Δ: Considerable cracks, ×: Significantly more cracks The smaller the rate of decline in elastic modulus, the better the spalling resistance.

Note 3) High-frequency furnace lining method: A high-frequency furnace is lined with sample bricks, ordinary steel is melted, and iron oxide is used as a flux.
Hold at 650°C for 3 hours.

After the test, measure the area of erosion loss and use it as the amount of erosion loss.

The smaller the erosion index, the better the corrosion resistance.

Example 8 and Comparative Example 6 Table 3 shows the formulations of the magnesia-carbon materials used.

After mixing and kneading this mixture and molding it into a size of 114mm x 230mm x 45mm at a molding pressure of 1000kgf/c+a2,
Drying treatment was performed at 200°C for 36 hours.

The results are also shown in Table 3.

As seen in Table 3, it is clear that the products of the present invention are significantly superior in bending strength and spalling resistance.

Example 9 and Comparative Example 7 Plate bricks for sliding nozzles for tundish were molded using the same formulations as in Example 5 and Comparative Example 2, and after drying and polishing under the same conditions as the products shown in Table 1, Actual machine used (Example 9 and Comparative Example 7, respectively)
).

As a result, in Example 9, 12 stations (total amount of molten steel passing through 1
200 tons), and no surface roughness was observed on the sliding surface of the plate bricks, whereas in Comparative Example 7, the molten steel flow rate became uncontrollable due to surface roughness when six rows (600 tons) were used. , scrapped.

(that's all)

Claims (1)

[Claims] 1. In an unfired shaped refractory containing a refractory aggregate and an organic binder, 0.5 to 0.5 to 0.5 mm of carbon fiber with a diameter of 0.005 to 0.5 mm and a length of 1 to 15 mm is added to 100 parts by weight of the refractory aggregate. 10 parts by weight and diameter 0.005~
A defect characterized by blending 0.5 to 10 parts by weight of metal fibers made of aluminum or aluminum alloy with a diameter of 0.5 mm and a length of 1 to 15 mm (however, the total amount of both fibers is 1 to 15 parts by weight). Fired shaped refractories.