CN119841663A

CN119841663A - Impermeable steel ventilation element and preparation method thereof

Info

Publication number: CN119841663A
Application number: CN202510083146.5A
Authority: CN
Inventors: 王玉龙; 曹亚平; 魏国平; 方斌祥; 邬晓滢; 沈明科; 刘光平
Original assignee: Zhejiang Zili High Temperature Technology Co ltd
Current assignee: Zhejiang Zili High Temperature Technology Co ltd
Priority date: 2025-01-20
Filing date: 2025-01-20
Publication date: 2025-04-18

Abstract

The invention discloses an impermeable steel ventilation element and a preparation method thereof. The impermeable steel ventilation element comprises a body, wherein the body comprises, by weight, 65-85 parts of complex-phase corundum, 10-30 parts of alumina micropowder, 0-6 parts of chromium oxide micropowder, 0.5-5 parts of titanium oxide micropowder, 0.5-2 parts of alpha-cyclodextrin and 1-5 parts of binding agent. The preparation method of the body comprises the steps of stirring and mixing alumina micro powder, optionally added chromium oxide micro powder, alpha-cyclodextrin and a first part of binding agent uniformly to obtain a first component, stirring and mixing the composite corundum with a second part of binding agent uniformly, adding titanium oxide micro powder to obtain a second component, mixing the first component and the second component uniformly, trapping materials, performing mechanical press molding, sintering at high temperature, and processing to form an aeration tank to obtain the body.

Description

Impermeable steel ventilation element and preparation method thereof

Technical Field

The invention relates to the technical field of refractory materials, in particular to an impermeable steel ventilation element for refining ladle ventilation bricks and a preparation method thereof.

Background

The air brick is used as a key functional refractory material for ladle refining and argon blowing, and when molten steel is refined, argon is blown into the molten steel through the air brick to drive the molten steel to circularly flow, so that the components and the temperature of the molten steel are homogenized. However, after refining argon blowing is finished, the gas source pipeline is cut off, and high-temperature molten steel can infiltrate into the gas source pipeline along the argon blowing channel of the air brick, so that the channel is blocked when refining argon blowing is performed again. The ladle air brick conventionally used at home and abroad at present adopts cement combined with corundum spinel castable, and is used after being sintered at high temperature after being cast and molded. Because of the casting molding, a large number of large-size pores are formed in the water in the casting material. Meanwhile, a large number of gaps are formed between the matrix fine powder and the aggregate particles in the castable, which are difficult to sinter at high temperature. The argon blowing channel of the pouring type air brick is easy to infiltrate into molten steel, and the ladle refining argon blowing is failed.

The patent specification with the publication number of CN117962072A discloses a preparation method of a sintered integral mechanical press molding ventilation functional element, wherein the ventilation functional element is in a cylinder or cuboid shape, the periphery of the ventilation functional element is a steel sleeve made of heat-resistant steel, and the ventilation functional element body which is formed by integral mechanical press molding is combined with casting materials and the steel sleeve to form a ventilation functional element with high strength and excellent high temperature resistance; the preparation method comprises the following steps of firstly, preparing ingredients according to the raw material components of the breathable element body and the weight parts of the ingredients; premixing, namely adding the fused white corundum or platy corundum, alumina micropowder, zirconia material and fused mullite weighed in the previous step into a vibration ball mill for premixing, wherein the mixing time is 20-30 min; step three, stirring, granulating and screening, namely adding a certain additive and a bonding agent into the uniformly stirred fine particle powder, stirring for a plurality of minutes in an adjustable speed stirrer, screening by using a 2mm screen, removing agglomerated pug, step four, trapping, namely trapping the evenly fine particle pug after screening for 24 hours, detecting the humidity of the pug to be 0.5-1.5%, carrying out subsequent mechanical press forming, step five, preforming, namely uniformly distributing a plurality of combustible polyester strips at preset positions in a mould, penetrating the polyester strips in the mould, vertically and uniformly arranging the polyester strips at the same direction, arranging polyester strip fixing plates at the upper side and the lower side, putting the pug in the previous step into the mould, vibrating, pressing at two ends, removing the mould after vibration press forming, taking out the preformed green brick, step six, carrying out secondary forming, putting the preformed green brick into an isostatic press or an electric spiral brick press, carrying out high-pressure forming on the preformed green brick press through the prefabricated mould, and adopting a large-tonnage brick press of more than 1000 tons, and step seven, the method comprises the steps of drying, namely placing the green bricks with higher strength in a drying kiln with the temperature of 100-200 ℃ for curing and drying for 24-48 hours, sintering at high temperature, namely placing the dried secondary formed green bricks in a high-temperature tunnel kiln or shuttle kiln with the temperature of 1400-1700 ℃ for high-temperature sintering, wherein combustible polyester strips arranged in the green bricks disappear to form reserved complete slits, cutting grooves, namely cutting and grinding a plurality of transverse grooves on the outer wall of a cylinder or cuboid of the sintered green bricks by using a grinder or a cutting knife, and playing an anti-falling role when the breathable element body is processed and used later, and manufacturing a steel sleeve according to the shape of the sintered green bricks, wherein the reserved slits on the steel sleeve facilitate high-pressure gas to pass along the slits, and the high-temperature resistant steel sleeve is wrapped outside the mechanically pressed breathable element body through welding to form a complete breathable functional element capable of being used for field installation.

Before the invention is put forward, the applicant firstly puts forward an invention patent application with the publication number of CN115572156A, and the specification of the patent application discloses an aluminum-silicon-chromium breathable element which is not infiltrated by molten steel and a preparation method thereof. The aluminum-silicon-chromium ventilation element comprises a plate-shaped body, wherein the plate-shaped body is formed by machine pressing and shaping of the following raw materials in percentage by mass, and a sawtooth ventilation structure is arranged, wherein the composite corundum particles are 51% -72%, the zirconia corundum particles are 1% -10%, the mullite particles are 7% -18%, the alumina micro powder is 10% -20%, the chromium oxide micro powder is 1% -6% and the binding agent is 1% -3%. The technology does not adopt cement, the molding mode is mechanical press molding, the matrix fine powder part is a purer alumina monobasic system, the generation of low-melting phase of the ventilation element in a high-temperature state is greatly reduced, and the porosity is remarkably lower. The air permeable element has high strength, excellent thermal shock stability and molten steel infiltration resistance, and solves the problems that the service life is limited due to the breakage of a brick core caused by poor thermal shock stability of the traditional air permeable brick, the slit is blocked by the infiltration of molten steel, the bottom blowing of the air permeable brick is not feasible, and the like.

Through a great deal of research, the applicant provides a novel impermeable steel ventilation element and a preparation method thereof, wherein the impermeable steel ventilation element has lower apparent porosity, higher strength, stronger thermal shock resistance and stronger capability of resisting molten steel infiltration.

Disclosure of Invention

In order to solve the problems that a traditional air brick argon blowing channel is easy to be permeated by molten steel to cause channel blockage and the like, the invention provides an anti-seepage steel air permeable element and a preparation method thereof. Meanwhile, by regulating and controlling the material mixing process, the titanium oxide micro powder is enriched on the particle surface, and in-situ generation of an Al ₂TiO₅ phase with a low expansion coefficient on the surface of the composite corundum particle is realized in the high-temperature sintering process, so that the composite corundum particle has good thermal shock stability, simultaneously promotes the connection effect of the particle and a matrix, obviously reduces gaps between the particle and the matrix interface, and obviously improves the strength, the thermal shock resistance and the molten steel permeation resistance of the ventilation element. The laminated and assembled air permeable element is used for ladle refining air permeable bricks and has good blowing-through rate and service life.

[1] An impermeable steel breathable element comprising a body;

The main body comprises, by weight, 65-85 parts (e.g., 78 parts, etc.), 10-30 parts (e.g., 15 parts, etc.) of alumina micropowder, 0-6 parts (e.g., 1 part, 3 parts, etc.) of chromia micropowder, preferably 0.5-6 parts (e.g., 1 part, 3 parts, etc.), 0.5-5 parts (e.g., 1 part, 3 parts, etc.) of titania micropowder, 0.5-2 parts (e.g., 1 part, etc.), 1-5 parts (e.g., 2 parts, etc.) of a binding agent;

The preparation method of the body comprises the following steps:

the bonding agent is divided into a first part of bonding agent and a second part of bonding agent, wherein the first part of bonding agent accounts for 30% -50% (such as 40% and the like) of the total weight of the bonding agent, and the second part of bonding agent accounts for 50% -70% (such as 60% and the like) of the total weight of the bonding agent;

Mixing alumina micropowder and optionally (i.e. not adding chromium oxide micropowder when the weight part of the chromium oxide micropowder is 0 and adding the chromium oxide micropowder when the weight part of the chromium oxide micropowder is not 0) and alpha-cyclodextrin as well as a first part of binding agent, and filling micropowder pores by utilizing a unique structure of the alpha-cyclodextrin under the action of the first part of binding agent so as to form a large number of submicron pore structures after high-temperature sintering to obtain a first component;

Stirring and mixing the complex-phase corundum with a second part of binding agent uniformly, adding titanium oxide micropowder, and concentrating the titanium oxide micropowder on the surface of the complex-phase corundum under the action of the second part of binding agent to form a titanium oxide micropowder coating structure to obtain a second component;

And uniformly mixing the first component and the second component, performing mechanical press forming after ageing, sintering at a high temperature of 1500-1700 ℃ and processing to form a ventilation groove, thereby obtaining the body.

The invention adopts the methods of matrix pretreatment and particle-matrix interface treatment to uniformly mix alpha-cyclodextrin in matrix micro powder, fills micro powder pores by utilizing the unique structure of the alpha-cyclodextrin, and forms a large number of submicron pore structures (for example, figure 1) after sintering, thereby improving the thermal shock resistance of the matrix part. Meanwhile, in the stirring process, the titanium oxide micro powder is enriched on the surface of the composite corundum, and in the high-temperature sintering process, the surface of the composite corundum particles and titanium oxide generate Al ₂TiO₅ phase with low expansion coefficient in situ, so that the composite corundum has good thermal shock stability, simultaneously promotes the connection effect of the particles and the matrix, and reduces larger gaps formed at the interface of the particles and the matrix. Compared with the traditional casting material, the material has no large pores in the matrix, and simultaneously forms a submicron pore structure, so that the thermal shock resistance of the material is improved on the premise of reducing the porosity. By intervening the particle-matrix interface reaction, the particle-matrix interface gaps in the traditional materials are obviously reduced, and the molten steel permeation resistance is improved.

In some embodiments, the impermeable steel element is free of calcium aluminate cement in the raw material composition of the body.

In some embodiments, the impermeable steel element may comprise 100 parts by total weight of the composite corundum, alumina micropowder, chromia micropowder, titania micropowder, alpha-cyclodextrin, and binder.

In some embodiments, the main phases of the composite corundum are 75-95 wt% corundum phase and 5-12 wt% aluminum magnesium spinel phase.

In some embodiments, the impermeable steel breathable element comprises more than or equal to 94.0wt% of Al ₂O₃, less than or equal to 5wt% of MgO, and more than or equal to 98.5wt% of Al ₂O₃ +MgO.

In some embodiments, the impermeable steel element may be a combination of particles and fines, and further, the particle size may be 5-0mm.

In some embodiments, the impermeable steel breathable element, the alumina micropowder may comprise one or more of alumina micropowder with median particle diameter D50 of 0.5-1 μm, 1-2 μm, 4-5 μm.

In some embodiments, the content of the chromium oxide micro powder Cr ₂O₃ is more than or equal to 98.0wt percent, and the median particle diameter D50 is less than or equal to 10 mu m.

In some embodiments, the median particle diameter D50 of the titanium oxide micropowder is less than or equal to 5 mu m.

In some embodiments, the bonding agent may include one or more of phosphoric acid, aluminum dihydrogen phosphate solution, PVA (polyvinyl alcohol) solution, phenolic resin, silica sol, and aluminum sol.

In some embodiments, the impermeable steel element and the body may be plate-shaped.

In some embodiments, the number of the ventilation grooves of the impermeable steel ventilation element may be 20-60.

In some embodiments, the impermeable steel venting element and the vent groove may be a saw-tooth square structure.

[2] The method for producing a permeable steel member according to [1], comprising producing a body;

The preparation method of the body comprises the following steps:

The bonding agent is divided into a first part of bonding agent and a second part of bonding agent, wherein the first part of bonding agent accounts for 30% -50% of the total weight of the bonding agent, and the second part of bonding agent accounts for 50% -70% of the total weight of the bonding agent;

Uniformly stirring and mixing alumina micropowder, optionally added chromium oxide micropowder, alpha-cyclodextrin and a first part of binding agent, and filling micropowder pores by utilizing a unique structure of the alpha-cyclodextrin under the action of the first part of binding agent so as to form a large number of submicron pore structures after high-temperature sintering to obtain a first component;

In the preparation method of the body, the time for trapping the materials can be 24 hours.

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

The material of the air permeable element disclosed by the invention is different from the material of the traditional air permeable brick, calcium aluminate cement is not added, the matrix part adopts alumina micro powder and chromia micro powder, a large number of submicron pore structures are formed in the matrix after high-temperature sintering after pretreatment, and the thermal shock resistance of the matrix part is improved on the basis of obviously reducing the air holes in the material of the traditional air permeable brick. Meanwhile, the surface of the composite corundum is coated, and after high-temperature treatment, al ₂TiO₅ phases with low expansion coefficients are generated in situ at the interface of the composite corundum particles and the matrix, so that the composite corundum has good thermal shock stability, simultaneously, the connection effect of the particles and the matrix is promoted, and larger air hole gaps formed at the interface of the particles and the matrix are reduced. And a large number of gaps exist at the interface between the particles of the traditional air brick material and the matrix. These two factors give the breathable element good strength, thermal shock stability and resistance to penetration by molten steel.

Drawings

FIG. 1 is a photograph of the microstructure of the gas permeable element of example 1.

Detailed Description

The invention will be further elucidated with reference to the drawings and to specific embodiments. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. The methods of operation, under which specific conditions are not noted in the examples below, are generally in accordance with conventional conditions, or in accordance with the conditions recommended by the manufacturer. The ventilation element bodies in the following examples are plate-shaped bodies, and ventilation grooves formed on the plate-shaped bodies are of saw-tooth square structures.

Table 1 shows the raw material composition of the impermeable steel breathable element body of each example.

TABLE 1

In table 1:

the main phases in the composite corundum are 75-95 wt% of corundum phase and 5-12 wt% of aluminum-magnesium spinel phase;

The content of Al ₂O₃ and MgO in the composite corundum is more than or equal to 94.0wt%, the content of MgO is less than or equal to 5wt%, and the content of Al ₂O₃ plus MgO is more than or equal to 98.5wt%;

The median particle diameter D50 of the alumina micropowder is 2 mu m;

The content of Cr ₂O₃ in the chromium oxide micro powder is more than or equal to 98.0wt percent, and the median grain diameter D50 is less than or equal to 10 mu m;

The median grain diameter D50 of the titanium oxide micro powder is less than or equal to 5 mu m;

The binding agent is aluminum dihydrogen phosphate solution.

The preparation method of the impermeable steel breathable element body comprises the following steps:

the bonding agent is divided into a first part of bonding agent and a second part of bonding agent, wherein the first part of bonding agent accounts for 40 percent of the total weight of the bonding agent, and the second part of bonding agent accounts for 60 percent of the total weight of the bonding agent;

uniformly stirring and mixing alumina micropowder, chromium oxide micropowder, alpha-cyclodextrin and a first part of binding agent, and filling micropowder pores by utilizing a unique structure of the alpha-cyclodextrin under the action of the first part of binding agent so as to form a large number of submicron pore structures after high-temperature sintering to obtain a first component;

and uniformly mixing the first component and the second component, trapping the materials for 24 hours, performing mechanical press molding, sintering at a high temperature of 1500-1700 ℃ and processing to form a ventilation groove, and obtaining the body.

Comparative example 1:

Compared with example 1, the main body of the ventilation element of this comparative example has the same composition, except for the preparation method. The preparation method of the ventilation element body comprises the steps of uniformly mixing the multiphase corundum, the alumina micro powder, the chromium oxide micro powder, the titanium oxide micro powder and the alpha-cyclodextrin, then adding a binding agent, uniformly mixing, trapping the mixture for 24 hours, performing mechanical press forming, and sintering at a high temperature of 1500-1700 ℃ and processing to form a ventilation groove, so as to obtain the ventilation element body.

Comparative example 2:

compared with the embodiment 1, the raw material composition of the breathable element body of the comparative example is free of alpha-cyclodextrin, and the amount of the complex-phase corundum is 79 parts by weight. The method of making the body of the breathable element of this comparative example was the same as in example 1, except that no alpha-cyclodextrin was added during the preparation of the first pug.

Comparative example 3:

Compared with the embodiment 1, the ventilation element body of the comparative example has no titanium oxide micropowder in the raw material composition, and the composite corundum amount is 81 parts by weight. The method of preparing the body of the ventilation element of this comparative example was the same as in example 1, except that no titanium oxide fine powder was added during the preparation of the second pug.

The results of the body performance test of the breathable element of each example and comparative example are shown in table 2.

TABLE 2

As can be seen from the comparison of the performances of the examples in Table 2, the apparent porosity of the impermeable steel breathable element body of the invention is obviously lower, and the strength and the thermal shock resistance are obviously better. Comparative example 1 did not have a targeted separate pretreatment of aggregate and matrix, but a simple direct disposable blend, the resulting breathable element body was not only significantly reduced in strength, but also reduced in thermal shock from 31 to 15 breaks of example 1. Comparative example 2 was free of the addition of α -cyclodextrin, and the resulting breathable element body was not significantly different in strength from example 1, but the thermal shock property was reduced from 31 breaks to 9 breaks. Comparative example 3 was free of added titanium oxide micropowder. The resulting breathable element body had significantly reduced strength compared to example 1, and thermal shock properties decreased from 31 to 18 breaks.

Fig. 1 shows a large number of submicron-sized pores present in the matrix of the material of example 1, illustrating that the introduction of α -cyclodextrin forms a large number of micropores in the fired matrix, which can significantly improve the thermal shock stability properties of the material.

Further, it is to be understood that various changes and modifications of the present application may be made by those skilled in the art after reading the above description of the application, and that such equivalents are intended to fall within the scope of the application as defined in the appended claims.

Claims

1. An impermeable steel vapor permeable element comprising a body;

The main body comprises, by weight, 65-85 parts of complex-phase corundum, 10-30 parts of alumina micropowder, 0-6 parts of chromium oxide micropowder, preferably 0.5-6 parts of titanium oxide micropowder, 0.5-5 parts of alpha-cyclodextrin, and 1-5 parts of a binding agent;

The preparation method of the body comprises the following steps:

2. The impermeable steel element according to claim 1, characterized in that the raw material composition of said body is free of calcium aluminate cement;

the composite corundum, alumina micropowder, chromia micropowder, titania micropowder, alpha-cyclodextrin and binder are 100 parts by weight.

3. The impermeable steel breathable element according to claim 1, characterized in that the main phases in the composite corundum are 75-95 wt% corundum phase and 5-12 wt% aluminium magnesium spinel phase;

The content of Al ₂O₃ in the composite corundum is more than or equal to 94.0wt%, the content of MgO is less than or equal to 5wt%, and the content of Al ₂O₃ plus MgO is more than or equal to 98.5wt%;

The composite corundum is a combination of particles and fine powder, and the granularity is 5-0mm.

4. The impermeable steel breathable element according to claim 1, characterized in that said aluminium oxide micro powder comprises one or more of aluminium oxide micro powder with median particle size D50 of 0.5-1 μm, 1-2 μm, 4-5 μm.

5. The impermeable steel breathable element according to claim 1, characterized in that said chromium oxide micro powder Cr ₂O₃ content is not less than 98.0wt%, median particle diameter D50 is not more than 10 μm.

6. The impermeable steel breathable element according to claim 1, characterized in that said titanium oxide micro powder has a median particle diameter d50 less than or equal to 5 μm.

7. The impermeable steel breathable element of claim 1, wherein said binder comprises one or more of phosphoric acid, aluminum dihydrogen phosphate solution, PVA solution, phenolic resin, silica sol, aluminum sol.

8. The impermeable steel element according to claim 1, wherein said body is plate-shaped;

the number of the ventilation grooves is 20-60;

the ventilation groove is of a zigzag square structure.

9. The method for manufacturing a permeable steel element according to any one of claims 1 to 8, comprising manufacturing a body;

The preparation method of the body comprises the following steps: