JPS5832080A - Basic 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 a carbon-containing basic refractory.

Carbon-containing refractories are difficult to wet with molten slag and have excellent heat-resistant spalling properties, so the range of their use has been rapidly expanding in recent years. Carbon-containing basic refractories made by blending carbonaceous raw materials have attracted attention as materials with high corrosion resistance and spalling resistance, and are used in electric furnaces, converters,
It is well known that it has a good track record as a refractory lining for ladles, secondary smelting furnaces, etc.

However, such carbon-containing basic refractories have poor bonding strength because their bonding form is carbon bonding derived from phenolic resins, pitch, etc. It is recognized that the connective tissue of the refractory is destroyed, causing internal cracks in the refractory, resulting in peeling and wear. In order to improve the strength characteristics of such carbon-containing basic refractories, attempts have been made to add metals such as aluminum and silicon. It is true that the addition of these metals improves hot strength properties and improves impact resistance and wear resistance, but when metals are even slightly oxidized, hot strength rapidly decreases. , impact resistance and abrasion resistance - the effect almost disappears.

The present inventor conducted various studies on methods for preventing the phenomenon in which such carbon-containing basic refractories peel off due to the presence of chilene, which occurs due to mechanical impact, etc., and as a result, the inventors discovered that carbon or graphite fiber bundles were incorporated inside the refractories. It has been found that by disposing the above-mentioned peeling damage, the above-mentioned peeling wear and tear is significantly reduced.

Conventionally, there have been examples of incorporating ceramic fibers into refractories, but it is difficult to disperse the fibers, and furthermore, the fibers are difficult to be fixed during blending when they are in tension, and they cannot be oriented in any direction. Therefore, the effect of adding fibers was not sufficiently increased because the fibers could not be contained in an appropriate manner with respect to stress. Since these were used in the form of single fibers, this was an unavoidable problem.

The fiber bundle used in the present invention is a secondary fiber obtained by converging carbon or graphite long fibers produced from polyacrylonitrile, polyvinyl alcohol, coal tar pinch, etc., and has a secondary fiber diameter in the range of 0.1 to 5 m1m. It is something.

If the secondary fiber diameter is less than 0.1 m/m, the effect can be sufficiently improved, and if it exceeds 3 m/m, the filling properties and texture will deteriorate, which is preferable.

The amount of such fibers to be added is appropriately expressed in terms of the number of fibers per 1007 cross-sectional areas in the case of the carbon-containing basic refractory according to the present invention. . A region with fewer than 5 fibers is not sufficient to improve the performance of the refractory, and a region with more than 100 fibers causes manufacturing problems and makes it impossible to obtain a refractory with a good structure.

Regarding the arrangement of fiber bundles inside the refractory, it is preferable for the reinforcing effect that one end is on the inside of the furnace and container, such as on the molten metal contact surface, and the other end reaches the cold end of the refractory. It can be a thing. In addition, even if the fiber bundle is not continuous from one end to the other end, if it is interposed parallel to the axis from the inside of the furnace to the cold end side, it can be cut in the middle and made into multiple layers. It may be a method.

Effects of the long fiber bundle according to the present invention id: Improves the bending strength or tensile strength of iJ refractories, suppresses the generation of cracks due to mechanical stress, relieves stress in the fiber part, and prevents the propagation of cracks. It is possible to prevent this.

Therefore, in order to fully demonstrate the above effects,
It is necessary to have a strong bond between the fireproof aggregate and the fibers, and to achieve this, it is necessary to use phenolic resins and coal tar pitch, which have bonding properties with carbon or graphite fibers, as the binder. be. Here, it is obtained by reacting a phenolic resin with a phenol such as phenol, cresol, xylenol, or resorcinol, and an aldehyde such as bomaldehyde under an acid or alkali catalyst.

The aggregate used in the present invention is a combination of one or more basic raw materials such as magnesia, calcia, dolomite, and spinel, and one or more carbon raw materials such as phosphorous graphite, earthy graphite, anthracite, and carbon black. However, from the viewpoint of refractory performance, it is preferable for the blending ratio of the carbon raw material to be in the range of 5 to 40 parts by weight.

The present invention involves kneading the above aggregate using a conventional method using a carbonaceous binder such as a phenolic resin or coal tar pitch,
Carbon or graphite fiber bundles are added during molding. The refractories according to the present invention can be obtained by molding by conventional uniaxial molding or by using an isostatic press.

The present invention is obtained by drying the above-mentioned molded product at 150 to 400°C or firing it at a temperature higher than that, and for the molded product that undergoes a cooking process, Vl is impregnated with tar pitch by a known method. I can't help it.

Examples are given below to explain the invention in more detail.

Example 1 A magnesia-graphite phase material having a compounding ratio shown in Table 1 was kneaded by a conventional method, and then mixed using a friction press at 450 m/yn X150.
When molding bricks of ~130 m/m x 150 m/m, a predetermined number of fiber bundles (450 m/m in length) with a secondary fiber diameter of 1 m/m, which were made by converging carbon fibers with a single fiber diameter of 12.5 μm, were added.

6-Table 1 After molding, dry at 250°C for a day and night to obtain unfired MgO-C71.
K bricks were manufactured. Although there is no difference in quality after drying compared to additive-free products, the quality after reduction firing at 1500°C, especially the strength of the curves, has been greatly improved. Further, even in severe spalling tests, the fiber additives according to the present invention have obtained good results.

Table 2 (Example 2 of Pig Iron Melting at 1600° C. in a High Frequency Induction Furnace) The pitch bonded magnesia-carbon mixture shown in Table 6 was heated and kneaded in a conventional manner, mixed, and then cooled.

An external 2.5% resol type phenolic resin was added, and the above mixture was secondarily kneaded at room temperature. When forming with a friction press after mixing wires (Brick Naino: 450m/m x 150
~130 m/m x 150 m/m),
Graphite fibers with a single fiber diameter of 10.5μ are converged to form a secondary fiber with a diameter of 0.
．． A predetermined amount of fiber bundles of 5771/771 were added. After the molding, it was fired at 1400°C in a reducing atmosphere, and then subjected to tar impregnation treatment.

It has been demonstrated that the fiber additive according to the present invention has significantly superior strength properties and excellent resistance to mechanical stress such as impact.

Table 4 -10-

Claims (1)

[Claims] 60 to 95 parts by weight of basic raw materials such as magnesia, calcia, dolomite, and spinel whose particle size has been adjusted, and 5 to 4 parts by weight of carbon raw materials such as phosphorous graphite, anthracite, carbon black, etc.
1. A basic refractory containing carbon containing 0 parts by weight, characterized in that carbon or graphite fiber bundles are disposed inside the refractory.