A ladle castable resistant to slag erosion and its preparation method

Abstract

The present invention relates to the technical field of ladle castables, and specifically discloses a slag-resistant ladle castable, which includes: a green body and a protective layer coated on the surface of the green body; the raw materials of the green body include, by mass: 40-70 parts of corundum aggregate, 10-20 parts of corundum fine powder, 5-15 parts of aluminum-magnesium spinel, 5-15 parts of activated alumina micro-powder, 1-5 parts of polystyrene microspheres, 1-3 parts of aluminate cement, and 1-2 parts of polycarboxylate water reducer; the raw materials of the protective layer include, by mass: 5-15 parts of activated alumina micro-powder, 1-3 parts of chromium trioxide, 1-2 parts of titanium dioxide, 1-2 parts of bismuth germanate powder, 1-2 parts of pretreated nickel ferrite micro-powder, and 1-3 parts of polyvinyl alcohol; the pretreated nickel ferrite micro-powder is nickel ferrite micro-powder coated with rare earth zirconate on the outside. The obtained ladle castable has high strength, excellent slag erosion resistance, and excellent structural stability, and can meet the long-term use of the ladle lining structure in the high-temperature molten steel erosion environment.

Description

Technical Field

[0001] The present invention relates to the technical field of ladle castables, and particularly to a slag-resistant ladle castable and a preparation method thereof. Background Art

[0002] A ladle is an extremely important thermal equipment in the steelmaking process, and its inner lining is made of refractory materials. Since ladle castables have the advantages of simple production process, low production cost, excellent high-temperature performance, etc., they have great application potential in the high-temperature industrial field and are considered to be one of the best refractory materials for the ladle inner lining structure. The selection of ladle castables directly affects the production quality of steel.

[0003] With the wide application of domestic refining technology, due to the prolonged direct contact time between molten steel and the ladle inner lining, the service temperature of the ladle increases, and at the same time, the ladle also serves in various extreme environments. Therefore, optimizing the performance of ladle castables is an important way to improve the service life of ladles and reduce steelmaking costs.

[0004] Existing ladle inner linings generally use spinel castables, but their slag resistance, thermal shock resistance, and mechanical strength need to be improved, and they cannot serve in various extreme environments for a long time, thus directly affecting the service life of ladles. How to improve the service life of ladles has become an urgent technical problem to be solved at present. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies existing in the prior art, and to provide a slag-resistant ladle castable and a preparation method thereof.

[0006] A slag-resistant ladle castable includes: a green body and a protective layer coated on the surface of the green body;

[0007] The raw materials of the green body include, by mass: 40-70 parts of corundum aggregate, 10-20 parts of corundum fine powder, 5-15 parts of alumina-magnesia spinel, 5-15 parts of activated alumina micro-powder, 1-5 parts of polystyrene microspheres, 1-3 parts of aluminate cement, and 1-2 parts of polycarboxylate water reducer;

[0008] The raw materials of the protective layer include, by mass: 5-15 parts of activated alumina micro-powder, 1-3 parts of chromium trioxide, 1-2 parts of titanium dioxide, 1-2 parts of bismuth germanate powder, 1-2 parts of pretreated nickel ferrite micro-powder, and 1-3 parts of polyvinyl alcohol;

[0009] The pretreated nickel ferrite micro-powder is nickel ferrite micro-powder coated with rare earth zirconate on the outside.

[0010] Preferably, the particle size of the activated alumina micro-powder is 1-3 μm.

[0011] Preferably, the pre-treated nickel ferrite micropowder is prepared by the following specific operations: Add lanthanum nitrate, zirconium oxychloride, and urea to ethanol and stir for 10 - 30 min. Add nickel ferrite micropowder thereto and perform ultrasonic treatment for 1 - 2 h. Adjust the temperature to 90 - 96 °C and stir for 10 - 30 min. Centrifuge, wash with water, and dry in vacuum.

[0012] Preferably, the mass ratio of lanthanum nitrate, zirconium oxychloride, urea, and nickel ferrite micropowder is 0.1 - 1:0.1 - 1:1 - 2:1 - 2.

[0013] Preferably, the particle size of the nickel ferrite micropowder is 0.01 - 0.1 mm.

[0014] Preferably, the particle size of the corundum aggregate is 0.1 - 5 mm; among them, the mass of the corundum aggregate with 0.1 mm ≤ particle size < 1 mm accounts for 40 - 50% of the total mass of the corundum aggregate, the mass of the corundum aggregate with 1 mm ≤ particle size < 3 mm accounts for 10 - 20% of the total mass of the corundum aggregate, and the rest is the corundum aggregate with 3 mm ≤ particle size ≤ 5 mm.

[0015] Preferably, the particle size of the corundum fine powder is 0.01 - 0.09 mm; among them, the mass of the corundum fine powder with 0.01 mm ≤ particle size < 0.04 mm accounts for 20 - 35% of the total mass of the corundum fine powder, the mass of the corundum fine powder with 0.04 mm ≤ particle size < 0.06 mm accounts for 10 - 20% of the total mass of the corundum fine powder, and the rest is the corundum fine powder with 0.06 mm ≤ particle size ≤ 0.09 mm.

[0016] Preferably, the particle size of the polystyrene microspheres is 0.1 - 5 mm; among them, the mass of the polystyrene microspheres with 0.1 mm ≤ particle size < 1 mm accounts for 60 - 75% of the total mass of the polystyrene microspheres, the mass of the polystyrene microspheres with 1 mm ≤ particle size < 2 mm accounts for 10 - 17% of the total mass of the polystyrene microspheres, and the rest is the polystyrene microspheres with 2 mm ≤ particle size ≤ 5 mm.

[0017] The preparation method of the above slag-resistant ladle castable includes the following steps:

[0018] S1. Mix the corundum aggregate, corundum fine powder, spinel, activated alumina micropowder, polystyrene microspheres, and aluminate cement evenly. Add a polycarboxylate water reducer thereto and stir for 1 - 5 min. Add deionized water and continue to stir for 1 - 5 min. Pour into a mold, vibrate to form, cure at room temperature for 20 - 30 h, the curing humidity is 70 - 80%, and dry to obtain a green body.

[0019] S2. Mix the activated alumina micropowder, chromium sesquioxide, titanium dioxide, bismuth germanate powder, and pretreated nickel ferrite micropowder evenly. Add deionized water and polyvinyl alcohol to it, grind evenly at room temperature, then brush it onto the surface of the green body. Set up and start an induction coil outside it, with a current intensity of 100 - 200 A and a current frequency of 500 - 1500 Hz. Let it stand for 5 - 15 min, and then turn off the induction coil. Dry it at 100 - 120 °C for 10 - 20 h, heat it up to 400 - 600 °C, keep it warm for 2 - 5 h, continue to heat it up to 800 - 1000 °C for heat treatment for 1 - 2 h, and then heat it up to 1400 - 1540 °C for heat treatment for 1 - 3 h, and then cool it to room temperature with the furnace.

[0020] Preferably, in S1, the drying temperature is 120 - 140 °C and the drying time is 10 - 20 h.

[0021] Preferably, in S2, during the process of heating up to 400 - 600 °C, the heating rate is 5 - 10 °C / min.

[0022] Preferably, in S2, during the process of heating up to 1400 - 1540 °C, the heating rate is 1 - 5 °C / min.

[0023] Beneficial effects:

[0024] 1. The present invention pretreats the ferrite micropowder so that a layer of rare earth zirconate is bonded to its surface, thus having excellent surface activity, high affinity on the surface of the green body, and excellent coating performance. When combined with the activated alumina micropowder, it has good sintering activity at high temperatures, effectively promotes the tight combination of the green body and the protective layer, and at the same time, the microporous structure formed by high-temperature decomposition can absorb a large amount of liquid slag, effectively inhibiting the further penetration of the slag into the core layer structure, and having excellent slag erosion resistance.

[0025] 2. The present invention further applies a magnetic field around it, and the microsphere structure forms a regular complex structure along the magnetic field direction. This not only further enhances the coating effect on the green body, but also forms a regular solid network structure after multi-stage high-temperature treatment. It can not only significantly enhance the firmness of the inner and outer layers, improve the mechanical strength of the material, but also effectively inhibit the crack propagation and improve the thermal shock resistance of the castable.

[0026] 3. By combining polystyrene microspheres with corundum aggregate, corundum fine powder, aluminum-magnesium spinel, and activated alumina micropowder, and through reasonable control of the proportion of each component, and cooperating with multi-stage heat treatment after applying a magnetic field around it, the present invention can effectively reduce the permanent linear expansion brought by the spinel reaction process, effectively improve the volume stability of the material. It can not only effectively inhibit the collapse of the porous structure, but also effectively avoid the cracking and peeling of the shell layer structure. The ladle castable has high strength, excellent slag erosion resistance, and excellent structural stability, and can meet the long-term use of the ladle lining structure in the high-temperature molten steel erosion environment, effectively extending the service life. Description of the Drawings

[0027] Figure 1 It is a comparison chart of the slag corrosion rate and refractoriness of the ladle castables obtained in Example 5 and Comparative Examples 1-2.

[0028] Figure 2 It is a comparison chart of the room temperature flexural strength and room temperature compressive strength of the ladle castables obtained in Example 5 and Comparative Examples 1-2.

[0029] Figure 3 It is a comparison chart of the thermal shock stability and strength retention rate of the ladle castables obtained in Example 5 and Comparative Examples 1-2. Detailed Embodiments

[0030] The present invention will be further described below in conjunction with specific embodiments.

[0031] The grain size of the corundum aggregate used below is 0.1 - 5 mm; among them, the mass of the corundum aggregate with 0.1 mm ≤ grain size < 1 mm accounts for 45% of the total mass of the corundum aggregate, the mass of the corundum aggregate with 1 mm ≤ grain size < 3 mm accounts for 15% of the total mass of the corundum aggregate, and the rest is the corundum aggregate with 3 mm ≤ grain size ≤ 5 mm.

[0032] The grain size of the corundum fine powder used below is 0.01 - 0.09 mm; among them, the mass of the corundum fine powder with 0.01 mm ≤ grain size < 0.04 mm accounts for 30% of the total mass of the corundum fine powder, the mass of the corundum fine powder with 0.04 mm ≤ grain size < 0.06 mm accounts for 15% of the total mass of the corundum fine powder, and the rest is the corundum fine powder with 0.06 mm ≤ grain size ≤ 0.09 mm.

[0033] The particle size of the polystyrene microspheres used below is 0.1 - 5 mm; among them, the mass of the polystyrene microspheres with 0.1 mm ≤ particle size < 1 mm accounts for 65% of the total mass of the polystyrene microspheres, the mass of the polystyrene microspheres with 1 mm ≤ particle size < 2 mm accounts for 15% of the total mass of the polystyrene microspheres, and the rest is the polystyrene microspheres with 2 mm ≤ particle size ≤ 5 mm.

[0034] The particle size of the activated alumina micro powder used below is 1 - 3 μm, and it is purchased from Henan Fengkai Refractory Materials Co., Ltd.

[0035] Example 1

[0036] A slag-resistant ladle castable, comprising: a green body and a protective layer coated on the surface of the green body.

[0037] The raw materials of the green body include: 40 kg of corundum aggregate, 10 kg of corundum fine powder, 5 kg of aluminum-magnesium spinel, 5 kg of activated alumina micro powder, 1 kg of polystyrene microspheres, 1 kg of aluminate cement, and 1 kg of polycarboxylate water reducer.

[0038] The raw materials for the protective layer include: 5 kg of activated alumina fine powder, 1 kg of chromium sesquioxide, 1 kg of titanium dioxide, 1 kg of bismuth germanate powder, 1 kg of pretreated nickel ferrite fine powder, and 1 kg of polyvinyl alcohol.

[0039] The pretreated nickel ferrite fine powder is prepared by the following specific operations: Add 0.1 kg of lanthanum nitrate, 0.1 kg of zirconium oxyhydroxide, and 1 kg of urea to 10 kg of ethanol, stir at a speed of 100 r / min for 10 min, add 1 kg of nickel ferrite fine powder thereto, perform ultrasonic treatment for 1 h, with an ultrasonic frequency of 5 kHz, stir at a temperature of 90 °C for 10 min, centrifuge, wash with deionized water, and dry in vacuum.

[0040] The preparation method of the above slag-resistant erosion ladle castable includes the following steps:

[0041] S1. Mix the corundum aggregate, corundum fine powder, alumina-magnesia spinel, activated alumina fine powder, polystyrene microspheres, and aluminate cement evenly, add a polycarboxylate water reducer thereto, stir at a speed of 100 r / min for 1 min, add 5 kg of deionized water, continue to stir for 1 min, pour into a mold, vibrate to form, cure at a temperature of 20 °C for 20 h, with a curing humidity of 70%, dry at a temperature of 120 °C for 10 h to obtain a green body;

[0042] S2. Mix the activated alumina fine powder, chromium sesquioxide, titanium dioxide, bismuth germanate powder, and pretreated nickel ferrite fine powder evenly, add 1 - 5 kg of deionized water and polyvinyl alcohol thereto, grind evenly at room temperature, brush-coat onto the surface of the green body, set up and start an induction coil on its outer side, with a current intensity of 100 A and a current frequency of 500 Hz, let stand for 5 min, and turn off the induction coil; dry at a temperature of 100 °C for 10 h, heat up from room temperature to 400 °C at a rate of 5 °C / min, hold for 2 h, continue to heat up to 800 °C, perform heat treatment for 1 h, continue to heat up to 1400 °C at a rate of 1 °C / min, perform heat treatment for 1 h, and cool in the furnace to room temperature.

[0043] Example 2

[0044] A slag-resistant erosion ladle castable includes: a green body and a protective layer coated on the surface of the green body.

[0045] The raw materials for the green body include: 70 kg of corundum aggregate, 20 kg of corundum fine powder, 15 kg of alumina-magnesia spinel, 15 kg of activated alumina fine powder, 5 kg of polystyrene microspheres, 3 kg of aluminate cement, and 2 kg of polycarboxylate water reducer.

[0046] The raw materials for the protective layer include: 15 kg of activated alumina fine powder, 3 kg of chromium sesquioxide, 2 kg of titanium dioxide, 2 kg of bismuth germanate powder, 2 kg of pretreated nickel ferrite fine powder, and 3 kg of polyvinyl alcohol.

[0047] The pretreated nickel ferrite micropowder is prepared by the following specific operations: Add 1 kg of lanthanum nitrate, 1 kg of zirconium oxychloride, and 2 kg of urea to 30 kg of ethanol, stir at a speed of 500 r / min for 30 min, add 2 kg of nickel ferrite micropowder thereto, perform ultrasonic treatment for 2 h, with an ultrasonic frequency of 12 kHz, stir at a temperature of 96 °C for 30 min, centrifuge, wash with deionized water, and dry in vacuum.

[0048] The preparation method of the above slag erosion-resistant ladle castable includes the following steps:

[0049] S1. Mix the corundum aggregate, corundum fine powder, alumina-magnesia spinel, activated alumina micropowder, polystyrene microspheres, and aluminate cement evenly, add a polycarboxylate water reducer thereto, stir at a speed of 500 r / min for 5 min, add 10 kg of deionized water, continue to stir for 5 min, pour into a mold, vibrate and form, cure at a temperature of 30 °C for 30 h, with a curing humidity of 80%, and dry at a temperature of 140 °C for 20 h to obtain a green body;

[0050] S2. Mix the activated alumina micropowder, chromium trioxide, titanium dioxide, bismuth germanate powder, and pretreated nickel ferrite micropowder evenly, add 5 kg of deionized water and polyvinyl alcohol thereto, grind evenly at room temperature, brush-coat on the surface of the green body, set up and start an induction coil outside it, with a current intensity of 200 A and a current frequency of 1500 Hz, let it stand for 15 min, and turn off the induction coil; dry at a temperature of 120 °C for 20 h, heat up from room temperature to 600 °C at a rate of 10 °C / min, hold for 5 h, continue to heat up to 1000 °C, perform heat treatment for 2 h, continue to heat up to 1540 °C at a rate of 5 °C / min, perform heat treatment for 3 h, and cool in the furnace to room temperature.

[0051] Example 3

[0052] A slag erosion-resistant ladle castable includes: a green body and a protective layer coated on the surface of the green body.

[0053] The raw materials of the green body include: 50 kg of corundum aggregate, 18 kg of corundum fine powder, 8 kg of alumina-magnesia spinel, 13 kg of activated alumina micropowder, 2 kg of polystyrene microspheres, 2.5 kg of aluminate cement, and 1.3 kg of polycarboxylate water reducer.

[0054] The raw materials of the protective layer include: 12 kg of activated alumina micropowder, 1.5 kg of chromium trioxide, 1.7 kg of titanium dioxide, 1.2 kg of bismuth germanate powder, 1.7 kg of pretreated nickel ferrite micropowder, and 1.5 kg of polyvinyl alcohol.

[0055] The pretreated nickel ferrite micropowder is prepared by the following specific operations: Add 0.8 kg of lanthanum nitrate, 0.3 kg of zirconium oxychloride, and 1.8 kg of urea to 15 kg of ethanol, stir at a speed of 400 r / min for 15 min, add 1.7 kg of nickel ferrite micropowder thereto, perform ultrasonic treatment for 80 min, with an ultrasonic frequency of 9 kHz, stir at a temperature of 92 °C for 25 min, centrifuge, wash with deionized water, and dry in vacuum.

[0056] The preparation method of the above slag erosion-resistant ladle castable includes the following steps:

[0057] S1. Mix the corundum aggregate, corundum fine powder, alumina-magnesia spinel, activated alumina micropowder, polystyrene microspheres, and aluminate cement evenly, add a polycarboxylate water reducer thereto, stir at a speed of 200 r / min for 4 min, add 6 kg of deionized water, continue to stir for 4 min, pour into a mold, vibrate and form, cure at a temperature of 22 °C for 27 h, with a curing humidity of 73%, and dry at a temperature of 135 °C for 12 h to obtain a green body;

[0058] S2. Mix the activated alumina micropowder, chromium trioxide, titanium dioxide, bismuth germanate powder, and pretreated nickel ferrite micropowder evenly, add 4 kg of deionized water and polyvinyl alcohol thereto, grind evenly at room temperature, brush-coat on the surface of the green body, set up and start an induction coil outside it, with a current intensity of 120 A and a current frequency of 1200 Hz, let it stand for 7 min, and turn off the induction coil; dry at a temperature of 115 °C for 12 h, heat up from room temperature to 450 °C at a rate of 8 °C / min, hold for 4 h, continue to heat up to 850 °C, perform heat treatment for 100 min, continue to heat up to 1500 °C at a rate of 2 °C / min, perform heat treatment for 1.5 h, and cool in the furnace to room temperature.

[0059] Example 4

[0060] A slag erosion-resistant ladle castable includes: a green body and a protective layer coated on the surface of the green body.

[0061] The raw materials of the green body include: 60 kg of corundum aggregate, 12 kg of corundum fine powder, 12 kg of alumina-magnesia spinel, 7 kg of activated alumina micropowder, 4 kg of polystyrene microspheres, 1.5 kg of aluminate cement, and 1.7 kg of polycarboxylate water reducer.

[0062] The raw materials of the protective layer include: 8 kg of activated alumina micropowder, 2.5 kg of chromium trioxide, 1.3 kg of titanium dioxide, 1.8 kg of bismuth germanate powder, 1.3 kg of pretreated nickel ferrite micropowder, and 2.5 kg of polyvinyl alcohol.

[0063] The pretreated nickel ferrite micropowder is prepared by the following specific operations: Add 0.2 kg of lanthanum nitrate, 0.7 kg of zirconium oxychloride, and 1.2 kg of urea to 25 kg of ethanol, stir at a speed of 200 r / min for 25 min, add 1.3 kg of nickel ferrite micropowder thereto, perform ultrasonic treatment for 100 min, with the ultrasonic frequency being 6 kHz, stir at a temperature of 94 °C for 15 min, centrifuge, wash with deionized water, and dry in vacuum.

[0064] The preparation method of the above slag erosion-resistant ladle castable includes the following steps:

[0065] S1. Mix the corundum aggregate, corundum fine powder, alumina-magnesia spinel, activated alumina micropowder, polystyrene microspheres, and aluminate cement evenly, add a polycarboxylate water reducer thereto, stir at a speed of 400 r / min for 2 min, add 8 kg of deionized water, continue to stir for 2 min, pour into a mold, vibrate to form, cure at a temperature of 28 °C for 23 h, with the curing humidity being 77%, and dry at a temperature of 125 °C for 18 h to obtain a green body;

[0066] S2. Mix the activated alumina micropowder, chromium trioxide, titanium dioxide, bismuth germanate powder, and pretreated nickel ferrite micropowder evenly, add 2 kg of deionized water and polyvinyl alcohol thereto, grind evenly at room temperature, brush-coat on the surface of the green body, set up and start an induction coil on its outer side, with the current intensity being 180 A and the current frequency being 800 Hz, let stand for 13 min, and turn off the induction coil; dry at a temperature of 105 °C for 18 h, heat up from room temperature to 550 °C at a rate of 6 °C / min, hold for 3 h, continue to heat up to 950 °C, perform heat treatment for 80 min, continue to heat up to 1440 °C at a rate of 4 °C / min, perform heat treatment for 2.5 h, and cool to room temperature in the furnace.

[0067] Example 5

[0068] A slag erosion-resistant ladle castable includes: a green body and a protective layer coated on the surface of the green body.

[0069] The raw materials of the green body include: 55 kg of corundum aggregate, 15 kg of corundum fine powder, 10 kg of alumina-magnesia spinel, 10 kg of activated alumina micropowder, 3 kg of polystyrene microspheres, 2 kg of aluminate cement, and 1.5 kg of polycarboxylate water reducer.

[0070] The raw materials of the protective layer include: 10 kg of activated alumina micropowder, 2 kg of chromium trioxide, 1.5 kg of titanium dioxide, 1.5 kg of bismuth germanate powder, 1.5 kg of pretreated nickel ferrite micropowder, and 2 kg of polyvinyl alcohol.

[0071] The pre-treated nickel ferrite fine powder is prepared by the following specific operations: Add 0.5 kg of lanthanum nitrate, 0.5 kg of zirconium oxychloride, and 1.5 kg of urea to 20 kg of ethanol, stir at a speed of 300 r / min for 20 min, add 1.5 kg of nickel ferrite fine powder thereto, perform ultrasonic treatment for 90 min, with the ultrasonic frequency being 7.5 kHz, stir at a temperature of 93 °C for 20 min, centrifuge, wash with deionized water, and dry in vacuum.

[0072] The preparation method of the above-mentioned slag-resistant ladle castable includes the following steps:

[0073] S1. Mix the corundum aggregate, corundum fine powder, aluminum-magnesium spinel, activated alumina fine powder, polystyrene microspheres, and aluminate cement evenly, add a polycarboxylate water reducer thereto, stir at a speed of 300 r / min for 3 min, add 7 kg of deionized water, continue to stir for 3 min, pour into a mold, vibrate and form, cure at a temperature of 25 °C for 25 h, with the curing humidity being 75%, and dry at a temperature of 130 °C for 15 h to obtain a green body;

[0074] S2. Mix the activated alumina fine powder, chromium trioxide, titanium dioxide, bismuth germanate powder, and pre-treated nickel ferrite fine powder evenly, add 3 kg of deionized water and polyvinyl alcohol thereto, grind evenly at room temperature, brush-coat onto the surface of the green body, set up and start an induction coil on its outer side, with the current intensity being 150 A and the current frequency being 1000 Hz, let stand for 10 min, and turn off the induction coil; dry at a temperature of 110 °C for 15 h, heat up from room temperature to 500 °C at a rate of 7 °C / min, hold for 3.5 h, continue to heat up to 900 °C, perform heat treatment for 90 min, continue to heat up to 1470 °C at a rate of 3 °C / min, perform heat treatment for 2 h, and cool to room temperature with the furnace.

[0075] Comparative Example 1

[0076] A ladle castable includes: a green body and a protective layer coated on the surface of the green body.

[0077] The raw materials of the green body include: 55 kg of corundum aggregate, 15 kg of corundum fine powder, 10 kg of aluminum-magnesium spinel, 10 kg of activated alumina fine powder, 3 kg of polystyrene microspheres, 2 kg of aluminate cement, and 1.5 kg of polycarboxylate water reducer.

[0078] The raw materials of the protective layer include: 10 kg of activated alumina fine powder, 2 kg of chromium trioxide, 1.5 kg of titanium dioxide, 1.5 kg of bismuth germanate powder, 1.5 kg of nickel ferrite fine powder, and 2 kg of polyvinyl alcohol.

[0079] The preparation method of the above-mentioned ladle castable includes the following steps:

[0080] S1. Mix the corundum aggregate, corundum fine powder, aluminum-magnesium spinel, activated alumina micro-powder, polystyrene microspheres, and aluminate cement evenly. Add polycarboxylate superplasticizer thereto, stir at a speed of 300 r / min for 3 min, add 7 kg of deionized water, continue stirring for 3 min, pour it into a mold, vibrate and form it, cure at a temperature of 25 °C for 25 h, the curing humidity is 75%, and dry at a temperature of 130 °C for 15 h to obtain a green body;

[0081] S2. Mix the activated alumina micro-powder, chromium trioxide, titanium dioxide, bismuth germanate powder, and nickel ferrite micro-powder evenly. Add 3 kg of deionized water and polyvinyl alcohol thereto, grind evenly at room temperature, brush it onto the surface of the green body, set up and start an induction coil outside it, the current intensity is 150 A, the current frequency is 1000 Hz, let it stand for 10 min, and turn off the induction coil; dry at a temperature of 110 °C for 15 h, heat up from room temperature to 500 °C at a speed of 7 °C / min, keep the temperature for 3.5 h, continue to heat up to 900 °C, heat-treat for 90 min, continue to heat up to 1470 °C at a speed of 3 °C / min, heat-treat for 2 h, and cool down to room temperature with the furnace.

[0082] Comparative Example 2

[0083] A ladle castable, comprising: a green body and a protective layer coated on the surface of the green body.

[0084] The raw materials of the green body include: 55 kg of corundum aggregate, 15 kg of corundum fine powder, 10 kg of aluminum-magnesium spinel, 10 kg of activated alumina micro-powder, 3 kg of polystyrene microspheres, 2 kg of aluminate cement, and 1.5 kg of polycarboxylate superplasticizer.

[0085] The raw materials of the protective layer include: 10 kg of activated alumina micro-powder, 2 kg of chromium trioxide, 1.5 kg of titanium dioxide, 1.5 kg of bismuth germanate powder, 1.5 kg of pretreated nickel ferrite micro-powder, and 2 kg of polyvinyl alcohol.

[0086] The pretreated nickel ferrite micro-powder is prepared by the following specific operations: Add 0.5 kg of lanthanum nitrate, 0.5 kg of zirconium oxychloride, and 1.5 kg of urea to 20 kg of ethanol, stir at a speed of 300 r / min for 20 min, add 1.5 kg of nickel ferrite micro-powder thereto, perform ultrasonic treatment for 90 min, the ultrasonic frequency is 7.5 kHz, stir at a temperature of 93 °C for 20 min, centrifuge, wash with deionized water, and vacuum dry.

[0087] The preparation method of the above ladle castable includes the following steps:

[0088] S1. Mix the corundum aggregate, corundum fine powder, aluminum-magnesium spinel, activated alumina micropowder, polystyrene microspheres, and aluminate cement evenly. Add polycarboxylate water reducer thereto, stir at a speed of 300 r / min for 3 min, add 7 kg of deionized water, continue stirring for 3 min, pour into a mold, vibrate to form, cure at a temperature of 25 °C for 25 h, the curing humidity is 75%, and dry at a temperature of 130 °C for 15 h to obtain a green body;

[0089] S2. Mix the activated alumina micropowder, chromium trioxide, titanium dioxide, bismuth germanate powder, and pretreated nickel ferrite micropowder evenly. Add 3 kg of deionized water and polyvinyl alcohol thereto, grind evenly at room temperature, brush-coat on the surface of the green body, dry at a temperature of 110 °C for 15 h, heat up from room temperature to 500 °C at a rate of 7 °C / min, hold for 3.5 h, continue heating to 900 °C, heat-treat for 90 min, continue heating to 1470 °C at a rate of 3 °C / min, heat-treat for 2 h, and cool to room temperature in the furnace.

[0090] Refer to YB / T 5083-2014 "Clay and High-Alumina Dense Refractory Castables" to detect the heating permanent linear change (1550 °C × 3 h) of the ladle castables obtained in Example 5 and Comparative Examples 1-2, as shown in the following table:

[0091]

[0092] It is confirmed that the permanent linear changes of all three are small, indicating that the ladle castable obtained by the present invention has high volume stability.

[0093] Refer to the static sample slag immersion ventilation method in GB / T 8931-2007 "Refractory Materials - Test Method for Slag Resistance" to determine the slag corrosion rate of the ladle castable samples obtained in Example 5 and Comparative Examples 1-2. Refer to YB / T 5083-2014 "Clay and High-Alumina Dense Refractory Castables" to detect the refractoriness, room temperature flexural strength, and room temperature compressive strength of the ladle castable samples obtained in Example 5 and Comparative Examples 1-2.

[0094] As Figure 1 and Figure 2 shown, the slag corrosion rate of the ladle castable obtained in Example 5 is the lowest, and the refractoriness, room temperature flexural strength, and room temperature compressive strength are the highest, which are significantly better than the other two groups (P < 0.05).

[0095] Use 2 detection methods to characterize the thermal shock resistance of the ladle castables obtained in Example 5 and Comparative Examples 1-2:

[0096] (1) Refer to Method 1 (water quenching method - straight brick sample) in GB / T 30873-2014 "Refractory Materials - Test Method for Thermal Shock Resistance" to determine the thermal shock resistance of the three groups of samples.

[0097] (2) Place the three groups of specimens into an electric furnace. After the temperature in the furnace reaches 1050 °C and is kept warm for 25 min, take them out of the electric furnace, then air-cool the specimens. After 4 cycles, measure the residual flexural strength of the specimens, and finally use the strength retention rate to characterize its thermal shock stability.

[0098] As Figure 3 shown, the thermal shock resistance of the ladle castable obtained in Example 5 is significantly better than the other two groups (P < 0.05).

[0099] The applicant believes that: This is because the present invention can effectively reduce the permanent linear expansion brought by the spinel formation reaction process by reasonably controlling the proportion of each component, effectively improve the volume stability of the material, and facilitate the smooth progress of the subsequent coating process. And the present invention pretreats the ferrite fine powder to make a layer of rare earth zirconate bind to its surface, so it has excellent surface activity, high affinity on the surface of the green body, and excellent coating performance; combined with activated alumina fine powder, it has good sintering activity at high temperature, effectively promotes the tight combination of the green body and the protective layer, and at the same time, the microporous structure formed by high-temperature decomposition can absorb a large amount of liquid slag, effectively inhibiting the further penetration of the slag into the core layer structure, and has excellent slag erosion resistance.

[0100] The present invention further applies a magnetic field around, and the microsphere structure forms a regular complex structure along the magnetic field direction, which not only further enhances the coating effect on the green body, but also forms a regular solid network structure after multi-stage high-temperature treatment, which can not only significantly enhance the firmness of the inner and outer layers, improve the mechanical strength of the material, but also effectively inhibit the crack propagation and improve the thermal shock strength of the castable.

[0101] By applying a magnetic field around and cooperating with multi-stage heat treatment, the present invention can not only effectively inhibit the collapse of the porous structure, but also effectively avoid the cracking and falling off of the shell structure. The ladle castable has high strength, excellent slag erosion resistance, and excellent structural stability, can meet the long-term use of the ladle lining structure in the high-temperature molten steel erosion environment, and effectively extends the service life.

[0102] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A slag erosion resistant ladle castable, characterized in that: include: A blank and a protective layer coated on the surface of the blank; The raw materials of the green body include, by mass: 40-70 parts of corundum aggregate, 10-20 parts of corundum fine powder, 5-15 parts of aluminum-magnesium spinel, 5-15 parts of activated alumina micropowder, 1-5 parts of polystyrene microspheres, 1-3 parts of aluminate cement, and 1-2 parts of polycarboxylate water reducer; The particle size of the polystyrene microspheres is 0.1-5 mm; the mass of the polystyrene microspheres with a particle size of 0.1 mm ≤ < 1 mm accounts for 60-75% of the total mass of the polystyrene microspheres, the mass of the polystyrene microspheres with a particle size of 1 mm ≤ < 2 mm accounts for 10-17% of the total mass of the polystyrene microspheres, and the rest are polystyrene microspheres with a particle size of 2 mm ≤ ≤ 5 mm; The raw materials of the protective layer include, by mass: 5-15 parts of activated alumina powder, 1-3 parts of chromium trioxide, 1-2 parts of titanium dioxide, 1-2 parts of bismuth germanate powder, 1-2 parts of pretreated nickel ferrite powder, and 1-3 parts of polyvinyl alcohol; The pretreated nickel ferrite powder is a nickel ferrite powder coated with rare earth zirconate on the outside; the pretreated nickel ferrite powder is prepared by the following specific operation: adding lanthanum nitrate, zirconium oxychloride and urea to ethanol and stirring for 10-30 minutes, adding nickel ferrite powder to the ethanol and ultrasonically treating for 1-2 hours, adjusting the temperature to 90-96° C. and stirring for 10-30 minutes, centrifuging, washing with water and vacuum drying; The preparation method of the slag erosion resistant ladle castable comprises the following steps: S1. Evenly mix corundum aggregate, corundum fine powder, aluminum magnesium spinel, activated alumina powder, polystyrene microspheres and aluminate cement, add polycarboxylate water reducer and stir for 1-5 minutes, add deionized water and continue stirring for 1-5 minutes, pour into a mold, vibrate to form, cure at room temperature for 20-30 hours, and the curing humidity is 70-80%, and dry to obtain a green body; S2. Evenly mix activated alumina powder, chromium oxide, titanium dioxide, bismuth germanate powder and pretreated nickel ferrite powder, add deionized water and polyvinyl alcohol, grind evenly at room temperature, then brush it on the surface of the blank, set and start an induction coil on the outside, with a current intensity of 100-200A and a current frequency of 500-1500Hz, let it stand for 5-15min, turn off the induction coil; dry at 100-120℃ for 10-20h, heat to 400-600℃, keep warm for 2-5h, continue to heat to 800-1000℃ for heat treatment for 1-2h, heat to 1400-1540℃ for heat treatment for 1-3h, and cool to room temperature with the furnace.

2. The slag corrosion resistant ladle castable according to claim 1, characterized in that: The mass ratio of lanthanum nitrate, zirconium oxychloride, urea and nickel ferrite powder is (0.1-1): (0.1-1): (1-2): (1-2).

3. The slag corrosion resistant ladle castable according to claim 1, characterized in that: The particle size of nickel ferrite powder is 0.01-0.1mm.

4. The slag corrosion resistant ladle castable according to claim 1, characterized in that: The particle size of the corundum aggregate is 0.1-5mm; among them, the mass of the corundum aggregate with a particle size of 0.1mm≤<1mm accounts for 40-50% of the total mass of the corundum aggregate, the mass of the corundum aggregate with a particle size of 1mm≤<3mm accounts for 10-20% of the total mass of the corundum aggregate, and the rest is the corundum aggregate with a particle size of 3mm≤≤5mm.

5. The slag corrosion resistant ladle castable according to claim 1, characterized in that: The particle size of the corundum fine powder is 0.01-0.09mm; among them, the mass of the corundum fine powder with a particle size of 0.01mm≤<0.04mm accounts for 20-35% of the total mass of the corundum fine powder, the mass of the corundum fine powder with a particle size of 0.04mm≤<0.06mm accounts for 10-20% of the total mass of the corundum fine powder, and the rest is the corundum fine powder with a particle size of 0.06mm≤≤0.09mm.

6. A method for preparing the slag corrosion resistant ladle castable according to any one of claims 1 to 5, characterized in that: The steps include: S1. Evenly mix corundum aggregate, corundum fine powder, aluminum magnesium spinel, activated alumina powder, polystyrene microspheres and aluminate cement, add polycarboxylate water reducer and stir for 1-5 minutes, add deionized water and continue stirring for 1-5 minutes, pour into a mold, vibrate to form, cure at room temperature for 20-30 hours, and the curing humidity is 70-80%, and dry to obtain a green body; S2. Evenly mix activated alumina powder, chromium oxide, titanium dioxide, bismuth germanate powder and pretreated nickel ferrite powder, add deionized water and polyvinyl alcohol, grind evenly at room temperature, then brush it on the surface of the blank, set and start an induction coil on the outside, with a current intensity of 100-200A and a current frequency of 500-1500Hz, let it stand for 5-15min, turn off the induction coil; dry at 100-120℃ for 10-20h, heat to 400-600℃, keep warm for 2-5h, continue to heat to 800-1000℃ for heat treatment for 1-2h, heat to 1400-1540℃ for heat treatment for 1-3h, and cool to room temperature with the furnace.

7. The method for preparing the slag corrosion resistant ladle castable according to claim 6, characterized in that: In S1, the drying temperature is 120-140°C and the drying time is 10-20h.

8. The method for preparing the slag corrosion resistant ladle castable according to claim 6, characterized in that: In S2, during the process of heating to 400-600°C, the heating rate is 5-10°C / min; during the process of heating to 1400-1540°C, the heating rate is 1-5°C / min.

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