JPH02133166A - Method for reinforcing refractories - Google Patents

Abstract

PURPOSE:To prevent the generation, expansion and dislodgment of cracks by thermal impact by winding the bundle or net-like matter of carbon fibers to the refractories in the direction perpendicular to the direction of the through hole of the refractories and thereby reinforcing the refractories. CONSTITUTION:The bundle or net-like matter of the carbon fibers is wound around the refractories having the through hole of an immersion nozzle, air sealing pipe or plate brick for a slide valve, etc., or is embedded as an annular reinforcing material into the refractories concentrically with the through-hole thereof to reinforce the refractories. The carbon fibers have the coefft. of thermal expansion of 0 or negative value and exhibit a remarkable reinforcing effect at a high temp. as the strength in the longitudinal direction of the fibers is extremely high. The carbon fibers do not come into direct contact with the atmosphere and, therefore, there is no possibility of oxidation, etc., when the carbon fibers are embedded into the refractories. The generation, expansion and dislodgment of the cracks of the refractories having the through-hole in the inside part where the cracks by the thermal impact are liable to arise are thus prevented.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for reinforcing refractories having through holes, such as plate bricks for submerged nozzles, air seal pipes or slide valves, with carbon fiber bundles or nets. .

[Prior art/problems] Refractories that have through holes in their structures, such as submerged nozzles, air seal pipes, or plate bricks for slide valves, in which molten steel flows and the interior is exposed to high temperatures. In the case of immersed nozzles, the stress caused by this thermal shock causes cracks to form in the vicinity of the through-holes, and these cracks expand, causing steel leakage accidents, and in the case of immersed nozzles, serious accidents such as the nozzle falling off can occur.

Conventionally, in order to prevent cracks from forming and expanding in refractories having through-holes such as immersion nozzles, air seal pipes, or plate bricks for slide valves, the composition of refractory materials has been improved. , carbon short fibers having a length of about 5 to 101s11 are mixed into refractory materials. Carbon fiber has a negative coefficient of thermal expansion, and has properties suitable for preventing crack initiation and expansion due to thermal stress in refractories. It is very difficult to uniformly disperse the refractories in the refractory, and therefore it is not possible to expect uniform strength improvement within the refractory structure, and it is difficult to sufficiently prevent crack initiation and expansion caused by thermal stress. I couldn't do that.

In addition, as a method for preventing the occurrence and expansion of cracks in plate bricks for slide valves, the applicant has previously proposed plate bricks for slide valves in which the side peripheral surface of the plate bricks is restrained with steel bands (in practice). Showa 62-7295
No. 1), steel bands have a very high coefficient of thermal expansion,
The total length of the plate brick in the longitudinal direction and the length of the side surface parallel to the longitudinal center line passing through the center of the opening of the plate brick
The ratio 1/L value must be in the range of 0 to 0.35.

Therefore, an object of the present invention is to prevent the occurrence and expansion of cracks in refractories, in which cracks may occur and expand from inside the refractories, by using carbon fibers with a coefficient of thermal expansion of 0 or a negative value, and to An object of the present invention is to provide a method for reinforcing refractories that can prevent such materials from falling off.

[Means for Solving the Problems] That is, the present invention provides a method for reinforcing a refractory having internal through holes, in which a carbon fiber bundle or net is placed around a portion of the refractory that is likely to crack or fall off. The present invention relates to a method for reinforcing a refractory material, which is characterized by winding the material in a direction perpendicular to the direction of the through hole.

Furthermore, the present invention provides a method for reinforcing a refractory having through-holes inside obtained by pouring a refractory composition into a mold of a predetermined shape, curing and removing the frame, or filling the refractory composition and pressurizing it. In this step, an annular frame made of a bundle of carbon fibers or a mesh material is installed at a predetermined position in the formwork concentrically with the through hole, and then a refractory composition is poured or pressure molded. The present invention relates to a method for reinforcing refractories characterized by:

[Function] The present invention involves wrapping a carbon fiber bundle or net around a refractory having through holes, such as a submerged nozzle, an air seal pipe, or a plate brick for a slide valve, or wrapping a carbon fiber bundle or net around a refractory having through holes, such as a submerged nozzle, an air seal pipe, or a plate brick for a slide valve. This is a method of reinforcing a refractory by embedding an annular reinforcing material in the refractory concentrically with the through hole.

As mentioned above, carbon fiber has a coefficient of thermal expansion of O or a negative value, and has very high strength in the longitudinal direction of the fiber.When carbon fiber is wrapped around a refractory, the coefficient of thermal expansion decreases. It exhibits a more pronounced reinforcing effect at high temperatures than the above-mentioned reinforcement using steel bands, which have a large strength.

First, when carbon fibers are used for the purpose of preventing the occurrence and expansion of cracks in refractories having through-holes, carbon fibers are simply bundled into long pieces, and stress caused by thermal shock causes cracks in the refractories. It can be wrapped around the area where this is likely to occur in a direction perpendicular to the direction of the through-hole of the refractory, or it can be embedded inside the refractory concentrically with the through-hole as an annular reinforcing framework of the refractory. In this case, it is preferable to wind the carbon fiber bundle under constraint in a direction perpendicular to the direction of the through hole.

Carbon fibers can cause problems such as oxidation under high temperature conditions. When embedded within a refractory as an annular reinforcing frame, the carbon fibers do not come into direct contact with the atmosphere, so problems such as carbon oxidation are not much of a consideration.

However, when wrapping a bundle of carbon fibers around a refractory, after wrapping the bundle of carbon fibers under predetermined restraint conditions, it is necessary to perfect the adhesion between the refractory and the carbon fibers and to separate the carbon fibers from the atmosphere. In order to block contact, it is preferable to apply a method such as applying an antioxidant such as borosilicate glass or frit.

As a second embodiment of the present invention, when carbon fiber is used for the purpose of preventing the occurrence and expansion of cracks in refractories such as immersed nozzles and the like, as well as preventing the immersed nozzle from falling off from the middle, carbon fibers are used. It is preferable to use reticulated carbon fibers made by knitting bundles of carbon fibers into a reticulated shape.By wrapping the reticulated carbon fibers around and around areas where cracks are likely to occur,
The carbon fibers in the direction perpendicular to the direction of the through hole in the refractory act in the same manner as when wrapping the bundle of carbon fibers described above to prevent the generation and expansion of cracks. The carbon fibers in the same direction as the hole act to prevent the refractory from falling off from the middle.

It is preferable that the reticulated carbon fibers be wound in a direction perpendicular to the direction of the refractory through-holes under predetermined constraint conditions, similar to the above-mentioned carbon fiber bundle; Winding the carbon fibers in the refractory works to prevent the occurrence and expansion of cracks in the refractory, so it is more effective under certain restraint conditions. This is because the refractory acts to prevent the refractory from falling off from the middle, so as long as the refractory and the carbon fiber are firmly bonded, the effect of preventing the refractory from falling off is sufficient.

Similarly to the above, reticulated carbon fibers can be embedded inside the refractory as an annular reinforcing framework. In this case, since the reticulated carbon fibers do not come into direct contact with the atmosphere, problems such as carbon oxidation are not much of a consideration.

However, when winding a reticulated carbon fiber around a refractory, the reticulated carbon fiber is wrapped in a direction perpendicular to the direction of the through hole under predetermined constraint conditions, and then the adhesion between the refractory and the carbon fiber is completely ensured. It is preferable to use a method similar to that described above in order to prevent carbon fibers from coming into contact with the atmosphere.

In addition, when embedding bundled or net-like carbon fibers as a framework inside a refractory, the carbon fibers are installed at a predetermined position in a formwork of the desired shape during the manufacture of the refractory, and then the refractory composition is applied. Conventional methods such as casting or pressing can be used.

The carbon fiber that can be used in the present invention is a bundle of about 1,000 to 15,000 long fibers of a predetermined length with a diameter of 3 to 20 μm, and carbon fiber bundles of such a shape are knitted and used as a net. You can also do that. Note that the mesh size can be varied depending on the application, but it is usually 5.
~15 mm is preferable.

In addition, the refractory reinforced with carbon fibers is not particularly limited in size, shape, material, etc., as long as it is a refractory with internal through holes that are prone to cracking due to stress due to thermal shock. It can be something.

[Example] The method of the present invention will be further explained below with reference to Examples.

(2) A bundle of carbon fibers (a bundle of 3,000 carbon fibers with a diameter of 7 μm) was wound around a plate brick for a slide valve made of Al2O, -C on F under the restraining conditions listed in Table 1.

A spalling test was conducted in which the inside of the through hole of the obtained reinforced brick was heated from room temperature to 1700° C. in 30 seconds by arc discharge. The results are shown in Table 1.

In addition, comparative product 1 is one in which a steel band of 3.2+u++ is wound.

/ Comparing the products of the present invention and comparative products, the stronger the binding force of the carbon fiber bundle, the smaller the size of cracks that occur, indicating that the restraint by carbon fibers has a good effect on spalling resistance. I understand.

E1 1 AbOs Carbon fiber bundle (3000 carbon fibers bundled with a diameter of 7μ) is made into a net shape in a C-quality immersion nozzle with a binding force of 100 ky per roll, and the number of times listed in Table 2 Wrapped around.

A spalling test was conducted by pouring molten steel at a temperature of 1550°C into the through hole of the reinforced immersion nozzle.

The obtained results are also listed in Table 2.

1" [L Outer diameter 110III111, inner diameter 50mm, height 100I
A carbon fiber bundle (a bundle of 3,000 carbon fibers with a diameter of 7 μm) was placed in a cylindrical formwork II11, and further,
Diameter 70m ring (when using one frame) and 901I1m
(Installed on the outside when using two frames) A ring-shaped frame is installed concentrically with the through hole, and A 1203-SiC
- After pouring C quality castable, removing the frame and drying, 1
Reduction firing was performed at 400° C. for 3 hours.

The obtained reinforced fired product was subjected to a spalling test in the same manner as in Example 2. The results are shown in Table 3.

/ / In Examples 1 to 3 described above, the occurrence of cracks could be suppressed or prevented by reinforcing the bricks with carbon fiber bundles or nets.

In addition, in the above-mentioned example, 3 carbon fibers with a diameter of 7 μm were used.
Although a bundle of 000 bricks was used, it should be understood that the diameter, number, etc. can be changed as appropriate within the above range depending on the shape and size of the fire bricks to be reinforced.

[Effects of the Invention] According to the method of the present invention, it is possible to prevent the occurrence and expansion of cracks in a refractory having internal through-holes that are likely to cause cracks due to stress caused by thermal shock.

Further, by reinforcing the refractory using reticulated carbon fibers, it is possible to prevent the generation and expansion of cracks, and at the same time prevent the refractory from falling off from the middle.

Patent applicant Shinagawa White Brick Co., Ltd.

Claims (1)

[Claims] 1. In a method for reinforcing a refractory having a through hole inside,
A method for reinforcing a refractory, comprising wrapping a carbon fiber bundle or a net-like material around a portion of the refractory that is likely to crack or fall off in a direction perpendicular to the direction of the through-hole. 2. The method according to claim 1, wherein the carbon fiber bundle or net-like material is wound while being constrained in a direction perpendicular to the direction of the through-hole of the refractory. 3. A method for reinforcing a refractory having through-holes inside obtained by pouring a refractory composition into a mold of a predetermined shape, curing and removing the frame, or filling the refractory composition and applying pressure. An annular framework made of a bundle of carbon fibers or a net-like material is installed at a predetermined position in the formwork concentrically with the through hole, and then a refractory composition is poured or pressure molded. Reinforcement method for refractories.