JPH02217384A - Method for manufacturing metal-impregnated fired refractories - Google Patents

Abstract

PURPOSE:To obtain a calcined refractory having excellent slag-impregnation resistance, structural spalling resistance and thermal spalling resistance by sealing calcined refractory and a metal in a container in vacuum and heating the container under a specific condition while applying a pressure from outside. CONSTITUTION:A calcined refractory and a metal are sealed in a container in vacuum and the container is heated at a temperature above the melting point of the metal and, at the same time, pressurized from outside under a pressure of 0.1-2,000kg/cm<2> to impregnate the metal into the calcined refractory. The maximum pressure in the pressurizing process should be adjusted to be lower than the compression strength of the calcined refractory. The container to be heated and pressurized is preferably made of a heat-resistant glass having high softening point or a metal such as stainless steel. There is no particular restriction in the kind of the metal for impregnation, however, it is preferably stainless steel, an Ni-Cr alloy, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing fired refractories used in metal manufacturing furnaces, heat treatment furnaces, and the like.

[Prior Art] The inner wall of a heat treatment furnace such as a heating furnace is exposed to high temperatures for a long period of time, causing surface peeling. For this reason, refractory bricks with excellent spalling resistance are used for the inner walls of the furnace.

Furthermore, the inner walls of molten metal containers such as converters, ladles, and degassing furnaces come into contact with molten metal and slag, causing erosion and peeling. In particular, in a slag line, the inner wall refractories come into contact with the molten slag and suffer significant erosion damage, and the molten slag also penetrates into the refractories, causing thermal and structural spalling.

Spalling is a phenomenon in which refractories crack and break due to thermal shock, mechanical or structural causes. Spalling due to thermal shock (hereinafter referred to as thermal spalling) occurs due to thermal stress during rapid heating and cooling. Spalling due to mechanical causes (hereinafter referred to as mechanical spalling) mainly occurs due to damage to refractories caused by mechanical operation. Furthermore, spalling due to structural causes (hereinafter referred to as structural spalling) mainly occurs in association with slag intrusion. That is, the slag that has entered the open pores of the brick applies thermal stress to the surrounding brick base material, causing damage to the base material.

Among these spallings, mechanical spalling can be improved to some extent by improving equipment and the like.

Therefore, in terms of the properties of refractory bricks, it is particularly desirable to improve the thermal spalling resistance and the structural spalling resistance. In order to improve structural spalling resistance, it is necessary to improve non-lag infiltration resistance for the above reasons.

In addition, since slag penetration increases erosion loss of the base material from the brick surface, a refractory with excellent slag infiltration resistance is desired in order to suppress erosion loss.

Refractory bricks with relatively excellent properties include high alumina bricks, chamotte bricks, magnesia bricks,
Chrome and magnesia bricks are used. Recently, graphite-added refractories such as magnesia-carbon bricks with improved heat-resistant spalling properties, castables containing metal fibers, and the like have been put into practical use.

Furthermore, in order to improve slag infiltration resistance, tar-impregnated bricks, which are bricks impregnated with tar, are used for lining converters, stainless steel refining furnaces, and the like. Tar-impregnated bricks have open pores filled with tar, which prevents slag from entering and suppresses structural spalling.

One of the methods for manufacturing tar-impregnated bricks is to mix and mold dolomite powder with tar as a binder, sinter it to obtain the desired apparent porosity, and then mix the tar diluted with a solvent in a vacuum chamber at room temperature and pressure. Soak.

In addition, another method of manufacturing tar-impregnated bricks is
Dolomite powder is mixed and molded using tar as a binder, fired to obtain a desired apparent porosity, immersed in a tar bath at a temperature of 200 to 300°C in a vacuum chamber, and pressurized to 3 to 4 kg/cd.

[Problems to be Solved by the Invention] However, the above tar-impregnated brick is heated during use, and the solvent contained in the tar evaporates, increasing the apparent porosity of the brick. For this reason, it is not possible to sufficiently prevent the intrusion of slag, and the life of the bricks is generally short.

Moreover, it is difficult to manufacture large-sized bricks.

Generally, in order to improve the slag infiltration resistance, it is sufficient to densify the refractory, but densification tends to cause thermal spalling. Thus, it is difficult to improve both slag infiltration resistance and spalling resistance.

This invention was made in view of the above circumstances, and
The purpose of this study is to image a method for producing fired refractories with excellent slag infiltration resistance, structural spalling resistance, and heat-resistant spalling resistance.

Means for Solving Problem C] The method for producing a metal-impregnated fired refractory according to the present invention includes vacuum sealing the fired refractory and the metal in a container, heating the container to a temperature equal to or higher than the melting point of the metal, and .1 to 200
It is characterized in that the fired refractory is impregnated with metal by applying pressure from the outside at a pressure of 0 kg/cj.

In this case, it is preferable that the maximum pressure in the pressurizing step is lower than the compressive strength of the fired refractory.

Incidentally, the compressive strength of most fired refractories is 1000 kg/cj or less. Furthermore, it is important to use a non-oxidizing gas such as argon gas or nitrogen gas as the pressurizing medium to prevent oxidation of the metal. Further, although the heating step and the pressurizing step can be performed interchangeably, it is preferable to first heat the container and apply pressure after the container has softened.

In addition, containers that are heated and pressurized can be made of quartz, Pyrex,
It is preferable to use heat-resistant glass with a high softening point such as Vycor. Furthermore, in the case of a container for high temperature and high pressure, it is desirable to use a container made of metal such as stainless steel.

Calcined refractories are refractories that are sintered through a firing process after forming, such as magnesia bricks, chromium/magnesia bricks, magnesia/carbon bricks, high alumina bricks, medium alumina bricks, and low alumina bricks. There are bricks, chamotte bricks, etc.

Further, the metal to be impregnated may be any metal,
Examples include iron, stainless steel, lead, tin, copper, aluminum, chromium, nickel, and alloys thereof. Among these, stainless steel or Ni-Cr alloy is particularly preferred.

In other words, since these alloys contain chromium,
This is because chromium is selectively oxidized and iron oxide, which is highly corrosive among slag components, can be reduced.

The metal to be heated and melted may be in any form, but preferably in a form that is easy to melt, such as a thin plate, chip, particle, or powder. However, when using metal powder, care must be taken to ensure that the metal powder is not entrained in the degassed gas during degassing.

Note that the internal pressure of the container during degassing is preferably in the range of 20 to 10<-4>.

[Function] In the method for manufacturing large metal-impregnated fired refractories according to the present invention, fired refractories and metal are sealed in a container, the metal is heated and melted, and then heated from outside the container at a pressure of 0.1 to 2000 kg/cm2. Apply pressure. Apply pressure from 0.1 to 2000kg/
The reason for choosing the cm2 range is that if no external pressure is applied to the container, the internal pressure of the fired refractory and the penetrating force of the molten metal (this penetrating force is a property that correlates with the wettability of the molten metal to the fired refractory). This is because if the molten metal does not penetrate into the pores (generally larger for easily wetted molten metal) and the molten metal does not penetrate into the pores, and if the applied pressure is too high, there is a risk that the fired refractory will collapse. . In other words, if the maximum pressure exceeds the compressive strength of the fired refractory, the fired refractory itself will be destroyed,
As the amount of metal impregnation decreases, the hot strength of the fired refractory after impregnation decreases.

The reason for deaerating the inside of the container is that if it is not deaerated, even if the pressurized metal once penetrates into the pores, when the pressure is restored, some of the metal will be pushed out by the compressed gas in the pores. This is because the amount of metal impregnation cannot be controlled.

[Embodiments] Various embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

Example 1 Manufacturing method using a heat-resistant glass container An alumina porous brick was used as the fired refractory. The apparent porosity of this fired refractory was adjusted to about 17% by volume, and the average pore diameter was 150 μm. Pig iron was used as the metal to be impregnated. Moreover, a container made of heat-resistant glass (Pyrex) having a softening point of about 1100° C. was used as the container.

As shown in FIG. 2, the glass container 2 has one end closed and the other end open, and has a thickness of 51 mm and a diameter of 150 mm.
all, the height of which is 400IIIl.

The fired refractory 2 is weighed, and the amount of pig iron impregnated is determined based on this. The pig iron piece 4 is weighed so that the proportion of the fired refractory 2 is 35 to 40% by weight (step 31).

As shown in FIG. 2, fired refractories 2 and pig iron pieces 4 are charged into a container 6 (step 32).

As shown in FIG. 3, the opening of the container 6 is narrowed to form a narrow opening 6a, and the gas inside the container 6 is degassed through the narrow opening 6a.
Step 33). In this case, the internal pressure of the container 6 is reduced to about 0.1 Torr.

The narrow opening 6a is closed, and the fired refractory 2 and the metal piece 4 are vacuum sealed in the container 6 (step 34).

The container 6 is placed in the heating/pressurizing furnace 10 and gradually heated by the heater 12 (step 35). In this case, the inside of the furnace is set to an argon gas atmosphere in advance.

When the temperature inside the furnace reaches 660° C., the pig iron piece 4 melts and becomes molten metal 4a, as shown in FIG.

The temperature continues to rise further, and when it reaches about 1450°C, the temperature inside the furnace is maintained. This softens the glass container 6. Next, high-pressure argon gas is supplied into the furnace through the passage 14, and the softened container 6 is pressurized for a predetermined period of time (step 36).
. In this case, the pressure of high-pressure argon gas should be reduced to about 3 kg/
CD. The molten metal 4a becomes the fired refractory 2 by applying pressure.
penetrates into the pores of the body.

The fired refractory 2 is slowly cooled in the furnace (Step 37), and when the furnace temperature has sufficiently dropped, the fired refractory 2 is taken out of the furnace, the glass container 6 that is in close contact with the refractory is broken, and the fired refractory 2 is extracted.

In this way, a pig iron-impregnated alumina brick with an impregnation rate of 33% by weight was obtained.

Example 2 Manufacturing method using metal container A zirconia brick was used as the fired porous refractory body. The apparent porosity of the brick is adjusted to approximately 23% by volume.
The average pore diameter is 300 μm.

Silicon was used as the metal to be impregnated. In addition, the container is made of stainless steel, which has a higher melting point than the metal.
6 was used.

As shown in FIG. 6, the container 26 is closed at one end and open at the other end, has a thickness of 31 mm, a diameter of 230 mm,
Its height is 500 cm.

The fired refractory 22 is weighed, and the amount of silicon impregnated is determined based on this. The silicon pieces 24 are weighed so that the ratio of the silicon pieces 24 to the fired refractory 22 is 45 to 50% by weight (step 31).

The fired refractory 22 and silicon pieces 24 are charged into the container 26 (step 32).

As shown in FIG. 7, cover the opening of the container 26 with M27,
The lid 27 is welded to the container 27 all around. An exhaust passage 28 is attached to the lid 27. The gas in the container 26 is then evacuated via the passage 28 (step 33). In this case,
The internal pressure of vessel 26 is reduced to approximately 0.4 Torr.

The passage 28 is closed, and the fired refractory 22 and the metal piece 24 are vacuum sealed in the container 26 (step 34).

The container 26 is placed in the heating/pressurizing furnace 10 and gradually heated by the heater 12 (step 35). In this case, the inside of the furnace is set to an argon gas atmosphere in advance.

When the temperature inside the furnace reaches approximately 1410° C., the metal piece 24 melts.

While maintaining the furnace temperature at approximately 1440° C., high pressure argon gas is supplied into the furnace through the passage 14 to soften the softened container 26.
is pressurized for a predetermined time (step 36). In this case, the pressure of the high-pressure argon gas is approximately 10 kg/c. The molten metal penetrates into the pores of the fired refractory 2 due to the pressurization.

The fired refractory 22 is gradually cooled in the furnace (step 37), and when the furnace temperature has sufficiently decreased, the fired refractory 22 is taken out from the furnace,
The fired refractory 2 is extracted by breaking the container that is in close contact with the fired refractory.

In this way, a silicon-impregnated zirconia brick with an impregnation rate of 40% by weight was obtained.

[Effects of the Invention] According to the present invention, a fired refractory which has excellent slag infiltration resistance, structural spalling resistance, and thermal spalling resistance, has an extremely low erosion rate, and has excellent durability. can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of a method for manufacturing a metal-impregnated fired refractory according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view showing a glass container into which the fired refractory and metal are to be charged, and FIG. Fig. 4 is a cross-sectional schematic diagram showing a glass container filled with fired refractories and metals, and shows a glass container and heating/pressurizing furnace in which fired refractories and metals are vacuum-sealed, and is used to explain the heating process. A schematic cross-sectional view, FIG. 5 shows a heated and melted glass container and a heating/pressurizing furnace, and a schematic cross-sectional view for explaining the pressurizing process. FIG. 6 shows a fired refractory and a metal to be charged. FIG. 7 is a schematic cross-sectional view showing a container made of a metal container filled with fired refractories and metal. 2; Calcined refractory, 4; Metal piece, 6, 26. container, 10;
Heating φ Pressure Furnace Applicant Representative Patent Attorney Takehiko Suzue Figure Figure 4 Figure Figure 4

Claims (4)

[Claims] (1) A fired refractory and a metal are vacuum sealed in a container, and the container is heated to a temperature equal to or higher than the melting point of the metal and 0.1
Pressurize from the outside with a pressure of 2000 kg/cm^2,
A method for producing a metal-impregnated fired refractory, comprising impregnating the fired refractory with a metal. (2) The method for manufacturing a metal-impregnated fired refractory according to claim 1, characterized in that the maximum pressure in the pressurizing step is lower than the compressive strength of the fired refractory. (3) The method for producing a metal-impregnated fired refractory according to claim 1, characterized in that a glass container is used. (4) Claim 1 characterized in that a metal container is used.
The method for producing the metal-impregnated fired refractory described above.