CN111732418B - Ultra-low carbon magnesia carbon brick for stainless steel ladle bottom and preparation method thereof - Google Patents

Abstract

The invention provides an ultra-low carbon magnesia carbon brick for a stainless steel ladle bottom and a preparation method thereof, wherein the ultra-low carbon magnesia carbon brick for the stainless steel ladle bottom comprises the following preparation raw materials in parts by weight: 50-120 parts of fused magnesia, 0.5-5 parts of graphite, 1-5 parts of liquid phenolic resin, 0.5-5 parts of carbon-containing resin powder, 0.1-5 parts of carbon black and MgO-Al₂O₃‑ZrO₂0.5-5 parts of composite powder, 0.5-8 parts of metal aluminum powder and 0-1 part of boron carbide. The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle has strong thermal shock stability and molten steel scouring resistance; the ultra-low carbon magnesia carbon brick does not carburete molten steel; having a lower thermal conductivity reduces heat loss; CO 2₂The discharge is low, and the environment is friendly; the use of natural resources is reduced in the production process.

Description

Ultra-low carbon magnesia carbon brick for stainless steel ladle bottom and preparation method thereof

Technical Field

The invention belongs to the technical field of refractory materials, and particularly relates to an ultra-low carbon magnesia carbon brick for a stainless steel ladle bottom and a preparation method thereof.

Background

The quality of the working condition of the ladle affects the quality of molten steel, the service life of a furnace lining and the production rhythm of a previous steelmaking process and a subsequent refining and continuous casting process. With the continuous progress and development of high-purity clean steel used in special fields (such as aerospace field), the requirements on the contents of impurities and alloy elements in steel are more and more strict; and the construction of an energy-saving and environment-friendly society also needs more efficient and environment-friendly materials to serve the production of clean steel, the magnesium-chromium products and the magnesium-dolomite products used by the traditional VOD steel ladle have no more advantages, and the low-carbon magnesium-carbon products are produced at the same time.

In the refining process, because the ladle bottom impact area is subjected to repeated violent impact of high-temperature molten steel and the stirring and slag erosion effects in the refining process, the ladle bottom refractory material has good impact resistance, erosion resistance and thermal shock resistance. However, for the low-carbon magnesia carbon brick, along with the reduction of the carbon content, the thermal shock stability and the molten steel scouring resistance of the low-carbon magnesia carbon brick are greatly influenced, and the improvement of the thermal shock stability and the molten steel scouring resistance of a low-carbon magnesia carbon product becomes a problem to be solved urgently.

Disclosure of Invention

The invention solves the technical problem of providing the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle and the preparation method thereof, wherein the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle has strong thermal shock stability and molten steel scouring resistance; the ultra-low carbon magnesia carbon brick does not carburete molten steel; having a lower thermal conductivity reduces heat loss; CO 2₂The discharge is low, and the environment is friendly; the use of natural resources is reduced in the production process.

In order to solve the above problems, one aspect of the present invention provides an ultra-low carbon magnesia carbon brick for a stainless steel ladle bottom, which comprises the following preparation raw materials by weight:

50-120 parts of fused magnesia, 0.5-5 parts of graphite, 1-5 parts of liquid phenolic resin, 0.5-5 parts of carbon-containing resin powder, 0.1-5 parts of carbon black and MgO-Al₂O₃-ZrO₂0.5-5 parts of composite powder, 0.5-8 parts of metal aluminum powder and 0-1 part of boron carbide.

MgO-Al₂O₃-ZrO₂The composite powder is additive MgO-Al₂O₃-ZrO₂The composite powder is added into a low-carbon magnesium-carbon product, and MgO and Al are added in the using process₂O₃The magnesia-alumina spinel is generated by in-situ reaction, the volume expansion generated in the process of generating the magnesia-alumina spinel can play a stronger toughening role on the material, the strength of the material is improved, and the generation of the magnesia-alumina spinel can not cause the consumption of MgO in the ultra-low carbon magnesia carbon brick; the residual zirconia particles in the composite powder are connected with each other to form a staggered columnar structure, and the staggered columnar structure is beneficial to improving the fracture toughness of the material and enhancing the strength of the material. The liquid phenolic resin and the carbon-containing resin powder serve as a binding agent in the raw materials, the single phenolic resin serves as the binding agent, the traditional phenolic resin is carbonized at high temperature and exists in the material in a glassy carbon form, the toughness is not enough, and the reduction of thermal shock stability is mainly shown; and after the single carbon-containing resin powder is used as a bonding agent of the magnesium-carbon material and carbonized at high temperature, the liquid phase is in a non-flowing state due to high viscosity and is in a mosaic structure, the resin is solidified before the liquid phase is formed at high temperature and laminated to form isotropic homogeneous carbon, and compared with anisotropic carbon, the isotropic carbon shrinks by 90 percent and 5 percent, so that high-strength compact carbon is formed. When the carbon-containing resin powder and the phenolic resin are mixed and carbonized, an embedded structure is formed on the interface of a carbonized structure, and the bonding strength of the material is improved.

Carbon black acts as a reinforcing agent in the feedstock. The addition of the carbon black can reduce the damage of thermal shock to the material structure, improve the mechanical property of the material and improve the thermal shock stability and molten steel scouring resistance of the ultra-low carbon magnesia carbon brick.

Preferably, the preparation raw materials comprise the following components in parts by weight:

80-92 parts of fused magnesia, 1-3 parts of graphite, 2.5-3 parts of liquid phenolic resin, 1-2 parts of carbon-containing resin powder, 0.5-2 parts of carbon black and MgO-Al₂O₃-ZrO₂1-3 parts of composite powder, 1-4 parts of metal aluminum powder and 0-0.5 part of boron carbide.

When the optimized raw material proportion is selected, the fused magnesia in the raw materials has the best interaction with the components such as the bonding agent, the reinforcing agent, the additive and the like, so that the obtained ultra-low carbon magnesia carbon brick has the best mechanical strength, and the thermal shock stability and the molten steel scouring resistance of the ultra-low carbon magnesia carbon brick are obviously improved.

Further preferably, the preparation raw materials comprise, by mass:

82 parts of fused magnesia, 3 parts of graphite, 3 parts of liquid phenolic resin, 1 part of carbon-containing resin powder, 2 parts of carbon black and MgO-Al₂O₃-ZrO₂1 part of composite powder and 1 part of metal aluminum powder.

Preferably, the fused magnesite comprises, by mass:

15-30 parts of fused magnesite with the grade of 5-3mm, 15-30 parts of fused magnesite with the grade of 3-1mm, 10-30 parts of fused magnesite with the grade of 1-0.074mm and 10-30 parts of fused magnesite with the grade of 0.074 mm.

Preferably, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1-2): (3-4): (4-5).

Preferably, the graphite is one or a combination of several of graphite with specifications of-190, -193, -194, -197 and-198.

Preferably, the carbon black is one or a combination of two of N330 carbon black and N990 carbon black. The N330 carbon black is beneficial to promoting the densification of the material and effectively playing the absorption effect of nano carbon black particles on thermal stress, and the damage of thermal shock on the material structure is reduced, while the N990 carbon black is beneficial to improving the pore structure of the magnesium carbon material and is beneficial to forming silicon carbide whiskers with larger length-diameter ratio on a sample at high temperature, so that the mechanical property of the material is improved; the strength and the thermal shock resistance of the low-carbon magnesium carbon material sample can be more remarkably improved by compositely adding the N330 and N990 carbon black.

Preferably, the liquid phenolic resin has a viscosity of not less than 1200 mPa · s at 25 ℃ or lower.

In another aspect of the present invention, a method for preparing the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following steps:

s1, mixing the fused magnesia, graphite, liquid phenolic resin, carbon-containing resin powder, carbon black and MgO-Al according to the selected weight portions₂O₃-ZrO₂Mixing the composite powder, the metal aluminum powder and the boron carbide to obtain a mixture;

s2, filling the mixture into a mold for molding;

and S3, carrying out heat treatment on the mixture formed in the step S2 to obtain the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle.

Preferably, step S1 specifically includes the following steps:

dry-mixing 5-3mm, 3-1mm and 1-0.074mm fused magnesite for 0.5-3min, adding liquid phenolic resin, mixing for 0.5-3min, adding graphite, mixing for 1-5min, adding 0.074mm fused magnesite, carbon-containing resin powder, carbon black, MgO-Al₂O₃-ZrO₂And (3) co-grinding the composite powder, the metal aluminum powder and the boron carbide into powder, and mixing for 15-20min to obtain the mixture.

Preferably, in step S2, the mixture is pressed and formed by a press, wherein the press adopts a 630T or 1000T electric spiral brick press;

in the step S3, the heat treatment temperature is 160-240 ℃, and the treatment time is 12-32 h.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention discloses an ultra-low carbon magnesia carbon brick for a stainless steel ladle bottom and a preparation method thereof, wherein MgO-Al is added into raw materials₂O₃-ZrO₂Composite powder additive, MgO-Al₂O₃-ZrO₂The composite powder is added into a low-carbon magnesium-carbon product, and MgO and Al are added in the using process₂O₃In situ reaction to produce magnesium-aluminum tipThe volume expansion generated in the process of generating the spinel, namely the magnesia-alumina spinel, can play a strong toughening role on the material, improve the strength of the material, and simultaneously, the generation of the magnesia-alumina spinel can not cause the consumption of MgO in the low-carbon magnesia-carbon brick; the residual zirconia particles in the composite powder are connected with each other to form a staggered columnar structure, and the staggered columnar structure is beneficial to improving the fracture toughness of the material and enhancing the strength of the material.

2. The invention relates to an ultra-low carbon magnesia carbon brick for a stainless steel ladle bottom and a preparation method thereof, wherein liquid phenolic resin and carbon-containing resin powder are used as bonding agents; the liquid phenolic resin and the carbon-containing resin powder are singly used as a bonding agent, and after the traditional phenolic resin is carbonized at high temperature, the traditional phenolic resin exists in the material in a glassy carbon form, so that the toughness is not enough, and the reduction of thermal shock stability is mainly shown; and after the single carbon-containing resin powder is used as a bonding agent of the magnesium-carbon material and carbonized at high temperature, the liquid phase is in a non-flowing state due to high viscosity and is in a mosaic structure, the resin is solidified before the liquid phase is formed at high temperature and laminated to form isotropic homogeneous carbon, and compared with anisotropic carbon, the isotropic carbon shrinks by 90 percent and 5 percent, so that high-strength compact carbon is formed. When the carbon-containing resin powder and the phenolic resin are mixed and carbonized, an embedded structure is formed on the interface of a carbonized structure, and the bonding strength of the material is improved.

3. According to the ultra-low carbon magnesia carbon brick for the stainless steel ladle bottom and the preparation method thereof, carbon black is used as a reinforcing agent in raw materials. The carbon black is added, so that the damage of thermal shock to the material structure can be reduced, the mechanical property of the material is improved, and the thermal shock stability and molten steel scouring resistance of the low-carbon magnesia carbon brick are improved. The N330 carbon black is beneficial to promoting the densification of the material and effectively playing the absorption effect of nano carbon black particles on thermal stress, and the damage of thermal shock on the material structure is reduced, while the N990 carbon black is beneficial to improving the pore structure of the magnesium carbon material and is beneficial to forming silicon carbide whiskers with larger length-diameter ratio on a sample at high temperature, so that the mechanical property of the material is improved; the strength and the thermal shock resistance of the low-carbon magnesium carbon material sample can be more remarkably improved by compositely adding the N330 and N990 carbon black.

4. According to the ultra-low carbon magnesia carbon brick for the stainless steel ladle bottom and the preparation method thereof, graphite has good heat conduction performance, and the thermal shock stability of the magnesia carbon brick is improved by introducing the graphite into the magnesia carbon brick. When the temperature changes, the temperature gradient in the material can be ensured to be smaller, the stress in the brick is reduced, and the occurrence of cracks of the brick body is also reduced; meanwhile, the wettability of graphite to ladle slag is poor, and the slag resistance of the magnesia carbon brick is improved.

5. According to the ultra-low carbon magnesia carbon brick for the stainless steel ladle bottom and the preparation method thereof, the metal aluminum powder mainly plays a role in oxidation resistance in the magnesia carbon brick, when carbon in the magnesia carbon brick is oxidized, the erosion resistance of the brick is greatly reduced, and the carbon in the magnesia carbon brick can be protected by adding the metal aluminum powder. Boron carbide is also added into the magnesia carbon brick as an antioxidant, and a compact layer is formed on the surface of a magnesia carbon brick sample under high temperature, so that the apparent porosity is reduced, the oxidation of a magnesia carbon brick body is reduced, the oxidation resistance of the magnesia carbon brick is improved, and the slag corrosion resistance can be improved.

6. The components in the formula of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle are matched with each other, so that the obtained low carbon magnesia carbon brick has strong thermal shock stability and molten steel scouring resistance, and the volume density of a product obtained by the optimal formula is more than or equal to 3.15g/cm³The apparent porosity (200 ℃ multiplied by 24 h) is less than or equal to 4.0 percent, the normal-temperature compressive strength (200 ℃ multiplied by 24 h) is more than or equal to 90MPa, the high-temperature rupture strength (1400 ℃ multiplied by 0.5 h) is more than or equal to 20MPa, and the retention rate of the thermal shock residual strength is more than or equal to 22 percent; the low-carbon magnesia carbon brick does not produce recarburization on the molten steel; the thermal conductivity is low, and the heat loss is reduced; CO 2₂The discharge is low, and the environment is friendly; the use of natural resources is reduced in the production process.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

This implementationThe ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by weight: 25 parts of fused magnesia of 5-3mm, 30 parts of fused magnesia of 3-1mm, 15 parts of fused magnesia of 1-0.074mm, 21.7 parts of fused magnesia of 0.074mm, graphite-1981 parts, 1 part of carbon-containing resin powder, 0.5 part of N990 carbon black, MgO-Al₂O₃-ZrO₂1.5 parts of composite powder, 3 parts of metal aluminum powder and 2.8 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following steps:

s1, taking the fused magnesite with the grain size of 5-3mm, 3-1mm and 1-0.074mm according to the mass parts, dry-mixing for 1min, then uniformly and slowly adding the liquid phenolic resin, adding for 2min, then adding the graphite mixture for 3min, and finally adding the fused magnesite with the grain size of 0.074mm, carbon-containing resin powder, carbon black and MgO-Al₂O₃-ZrO₂Co-grinding the composite powder and the metal aluminum powder, and mixing for 15-20min to obtain a mixture;

s2, placing the qualified materials into a mold, and molding on a press with corresponding tonnage according to the variety and shape of the brick, wherein the press is molded by a 630T electric screw brick press;

and S3, pushing the adobes which are inspected and accepted in the step S2 into a heat treatment kiln for heat treatment, wherein the internal temperature of the heat treatment kiln is 200 ℃, and the baking time is 20 hours, so that the ultra-low carbon magnesia carbon bricks for the stainless steel ladle bottom are obtained.

Example 2

The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by mass: 25 parts of fused magnesite 5-3mm, 30 parts of fused magnesite 3-1mm, 15 parts of fused magnesite 1-0.074mm, 21.7 parts of fused magnesite 0.074mm, graphite-1970.5 parts, graphite-1940.5 parts, 1 part of carbon-containing resin powder, 0.5 part of N990 carbon black, 0.5 part of N330 carbon black, MgO-Al₂O₃-ZrO₂1.5 parts of composite powder, 3 parts of metal aluminum powder, 0.3 part of boron carbide and liquid2.8 parts of phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (A) to (B) is 2: 4: 4.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Example 3

The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by mass: 25 parts of fused magnesite 5-3mm, 30 parts of fused magnesite 3-1mm, 15 parts of fused magnesite 1-0.074mm, 21.2 parts of fused magnesite 0.074mm, graphite-1941.5 parts, 1 part of carbon-containing resin powder, 0.5 part of N990 carbon black, 0.5 part of N330 carbon black, MgO-Al₂O₃-ZrO₂1.5 parts of composite powder, 3 parts of metal aluminum powder, 0.3 part of boron carbide and 2.8 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 4: 4.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Example 4

The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by mass: 25 parts of fused magnesite 5-3mm, 30 parts of fused magnesite 3-1mm, 15 parts of fused magnesite 1-0.074mm, 19.7 parts of fused magnesite 0.074mm, graphite-1981.5 parts, 1 part of carbon-containing resin powder, 0.5 part of N990 carbon black, 0.5 part of N330 carbon black, MgO-Al₂O₃-ZrO₂3 parts of composite powder, 3 parts of metal aluminum powder, 0.3 part of boron carbide and 2.8 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Example 5

Stainless steel according to the examplesThe ultra-low carbon magnesia carbon brick for the ladle bottom comprises the following preparation raw materials in parts by mass: 25 parts of fused magnesite 5-3mm, 30 parts of fused magnesite 3-1mm, 15 parts of fused magnesite 1-0.074mm, 19.5 parts of fused magnesite 0.074mm, graphite-1961.5 parts, 1 part of carbon-containing resin powder, 0.5 part of N990 carbon black, 0.5 part of N330 carbon black, MgO-Al₂O₃-ZrO₂1.5 parts of composite powder, 4 parts of metal aluminum powder and 2.8 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Example 6

The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by mass: 25 parts of fused magnesia of 5-3mm, 30 parts of fused magnesia of 3-1mm, 15 parts of fused magnesia of 1-0.074mm, 21.7 parts of fused magnesia of 0.074mm, graphite-1961 parts, 1 part of carbon-containing resin powder, 0.5 part of N990 carbon black, 0.5 part of N330 carbon black, MgO-Al₂O₃-ZrO₂1.5 parts of composite powder, 3 parts of metal aluminum powder, 0.3 part of boron carbide and 2.8 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Example 7

The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by mass: 5-3mm 20 parts of fused magnesia, 3-1mm 20 parts of fused magnesia, 1-0.074mm 20 parts of fused magnesia, graphite-1943 parts of carbon-containing resin powder 2 parts of N990 carbon black, 1 part of N330 carbon black, MgO-Al₂O₃-ZrO₂1 part of composite powder, 1 part of metal aluminum powder, 0.5 part of boron carbide and 2.5 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Example 8

The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by mass: 5-3mm 20 parts of fused magnesia, 3-1mm 22 parts of fused magnesia, 1-0.074mm 20 parts of fused magnesia, graphite-1983 parts, 1 part of carbon-containing resin powder, 1 part of N990 carbon black, 1 part of N330 carbon black, MgO-Al₂O₃-ZrO₂1 part of composite powder, 1 part of metal aluminum powder and 3 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Example 9

The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by mass: 5-3mm 15 parts of fused magnesia, 3-1mm 15 parts of fused magnesia, 1-0.074mm 10 parts of fused magnesia, graphite-1905 parts of carbon-containing resin powder, 0.1 part of N990 carbon black, MgO-Al₂O₃-ZrO₂0.5 part of composite powder, 8 parts of metal aluminum powder, 1 part of boron carbide and 5 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Example 10

The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following preparation raw materials in parts by mass: 30 portions of fused magnesite 5-3mm and 3-1mm of fused magnesite30 parts of fused magnesia 1-0.074mm 30 parts, fused magnesia 0.074mm 30 parts, graphite-1900.5 parts, carbon-containing resin powder 5 parts, N990 carbon black 2.5 parts, N330 carbon black 2.5 parts, MgO-Al₂O₃-ZrO₂5 parts of composite powder, 0.5 part of metal aluminum powder and 1 part of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Comparative example 1

The ultra-low carbon magnesia carbon brick for the stainless steel ladle bottom of the comparative example is prepared from the following raw materials in parts by mass: 25 parts of fused magnesia of 5-3mm, 30 parts of fused magnesia of 3-1mm, 15 parts of fused magnesia of 1-0.074mm, 21.7 parts of fused magnesia of 0.074mm, graphite-1981 parts, 1 part of carbon-containing resin powder, 0.5 part of N990 carbon black, 3 parts of metal aluminum powder and 2.8 parts of liquid phenolic resin. The preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle described in this example is the same as that of example 1.

Comparative example 2

The ultra-low carbon magnesia carbon brick for the stainless steel ladle bottom of the comparative example is prepared from the following raw materials in parts by mass: 25 parts of fused magnesite 5-3mm, 30 parts of fused magnesite 3-1mm, 15 parts of fused magnesite 1-0.074mm, 21.7 parts of fused magnesite 0.074mm, graphite-1981 parts, 0.5 part of N990 carbon black, MgO-Al₂O₃-ZrO₂1.5 parts of composite powder, 3 parts of metal aluminum powder and 2.8 parts of liquid phenolic resin; wherein, MgO-Al₂O₃-ZrO₂In the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1): 3: 5.

determination of physical and chemical indexes of ultra-low carbon magnesia carbon brick for bottom of stainless steel ladle

The volume density, the apparent porosity, the compressive strength, the breaking strength and the thermal shock stability of the ultra-low carbon magnesia carbon bricks for the stainless steel ladle bottoms obtained in the examples and the comparative examples are measured, wherein the method for measuring the retention rate of the thermal shock residual strength comprises the following steps: cut withstand voltage standard brick 65 mm-And (3) respectively detecting the compressive strength before thermal shock and the residual compressive strength after 1 time of air cooling thermal shock by using a sample block of 65mm multiplied by 65mm, and respectively detecting the residual compressive strength after 1 time of air cooling thermal shock/the compressive strength before thermal shock by 100% = the residual strength after shock retention rate. The measurement results are shown in Table 1. The ultra-low carbon magnesia carbon brick of comparative example 1 has no MgO-Al added₂O₃-ZrO₂The composite powder additive has poor compressive strength, breaking strength and thermal shock stability; in the comparative example 2, no carbon-containing resin powder is added, and the single liquid phenolic resin is used as a bonding agent of the magnesia carbon material, so that the ultra-low carbon magnesia carbon brick has poor compression strength, breaking strength and thermal shock stability; the ultralow-carbon magnesia carbon brick for the bottom of the stainless steel ladle has good normal-temperature compressive strength, good high-temperature rupture strength and strong thermal shock stability. Wherein, the preferred formulations of examples 1-8 yield products having a bulk density of 3.15g/cm or more³The apparent porosity (200 ℃ multiplied by 24 h) is less than or equal to 4.0 percent, the normal-temperature compressive strength (200 ℃ multiplied by 24 h) is more than or equal to 90MPa, the high-temperature rupture strength (1400 ℃ multiplied by 0.5 h) is more than or equal to 20MPa, and the retention rate of the thermal shock residual strength is more than or equal to 22 percent. The embodiment 8 is the best embodiment, and the obtained ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle has the highest normal-temperature compressive strength, the highest high-temperature rupture strength and the highest thermal shock stability.

TABLE 1

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (4)

1. The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle is characterized by comprising the following preparation raw materials in parts by mass:

80-92 parts of fused magnesia, 1-3 parts of graphite, 2.5-3 parts of liquid phenolic resin, 1-2 parts of carbon-containing resin powder, 0.5-2 parts of carbon black and MgO-Al₂O₃-ZrO₂1-3 parts of composite powder, 1-4 parts of metal aluminum powder and 0-0.5 part of boron carbide;

the fused magnesia comprises the following components in parts by weight: 15-30 parts of fused magnesite with the grade of 5-3mm, 15-30 parts of fused magnesite with the grade of 3-1mm, 10-30 parts of fused magnesite with the grade of 1-0.074mm and 10-30 parts of fused magnesite with the grade of 0.074 mm;

MgO-Al₂O₃-ZrO₂in the composite powder, MgO and Al₂O₃、ZrO₂The mass ratio of (1-2): (3-4): (4-5);

the carbon black is a combination of N330 carbon black and N990 carbon black;

the preparation method of the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle comprises the following steps:

s1, according to selected mass parts, firstly dry-mixing 5-3mm, 3-1mm and 1-0.074mm of fused magnesia for 0.5-3min, then adding liquid phenolic resin for mixing for 0.5-3min, then adding graphite for mixing for 1-5min, and finally adding 0.074mm of fused magnesia, carbon-containing resin powder, carbon black and MgO-Al₂O₃-ZrO₂Co-grinding the composite powder, the metal aluminum powder and the boron carbide into powder, and mixing for 15-20min to obtain a mixture;

s2, filling the mixture into a mold for molding;

and S3, carrying out heat treatment on the mixture formed in the step S2 to obtain the ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle.

2. The ultra-low carbon magnesia carbon brick for the bottom of the stainless steel ladle as claimed in claim 1, characterized in that:

the graphite is one or a combination of several of graphite with the specifications of-190, -193, -194, -197 and-198.

3. The stainless steel ladle bottom ultra-low carbon magnesia carbon brick according to claim 1 or 2, characterized in that:

the viscosity of the liquid phenolic resin is not lower than 1200 mPa & s at the temperature of below 25 ℃.

4. The stainless steel ladle bottom ultra-low carbon magnesia carbon brick according to claim 1 or 2, characterized in that:

in the step S2, a press is adopted to press and form the mixture, and the press adopts a 630T or 1000T electric spiral brick press;

in the step S3, the heat treatment temperature is 160-240 ℃, and the treatment time is 12-32 h.