Corundum-silicon carbide self-flowing material and method for preparing the same

Abstract

The application discloses corundum-silicon carbide self-flowing material and a preparation method thereof, and belongs to the technical field of refractory materials. The self-flowing material comprises the following raw materials in percentage by mass: dense corundum particles 50-70%, dense corundum powder 10-20%, silicon carbide 10-20%, Al2O3 micro powder 3-6%, activated powder 1-2%, solidifying agent 0.5-2%, tungsten oxide 1-2%, and metallic silicon 1-2%; and 8-11% of silicon sol of the weight of the above-mentioned raw material components is additionally added; wherein: the activated powder is prepared by high-energy ball milling of tungsten oxide and carbon black in a mass ratio of 5:1-2, coating with silicon sol, drying, and finally ball milling. The castable has the advantages of wear resistance, erosion resistance, volume stability, high thermal conductivity, good anti-infiltration corrosion, and the like, solves the problems of easy damage and frequent maintenance after lining repair in a blast furnace, and guarantees long-term continuous and stable operation of the blast furnace.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a corundum-silicon carbide self-flowing material and its preparation method. Background Technology

[0002] As a core and critical piece of equipment in steel smelting, the blast furnace's inner lining above the hearth operates in a harsh environment of 800~1500℃ for extended periods. It is subjected to continuous scouring by the furnace charge and high-temperature gas, as well as the penetration and erosion of molten slag. At the same time, it faces the thermal stress caused by frequent temperature fluctuations. After long-term operation, the inner lining is prone to serious damage such as cracking, peeling, and erosion, which can lead to damage to the cooling system and abnormal increases in the furnace shell temperature. This not only affects the continuous and stable operation of the blast furnace but may also cause safety hazards.

[0003] Currently, the main method for repairing damaged blast furnace linings is to use spray coatings to completely rebuild the lining. However, this method still has significant technical shortcomings. In the upper and middle sections of the furnace body, the material has low strength and insufficient wear resistance in the mid-temperature zone, leading to severe lining wear. In the high-temperature zones of the furnace belly and waist, the material has low thermal conductivity, unstable slag adhesion, and is prone to detachment. Alkaline slag easily reacts with and penetrates the material, damaging its crystal structure and causing expansion and spalling. Repaired linings can only maintain service life for 2-5 months before secondary damage such as wear, spalling, and cracking occurs again, causing the furnace shell temperature to rise. The repair effect is poor, and long-term repair is difficult to achieve. Furthermore, frequent shutdowns for repairs not only significantly increase construction and maintenance costs but also severely impact the continuity and efficiency of steel production. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a corundum-silicon carbide self-flowing material and its preparation method. This self-flowing material has advantages such as wear resistance, erosion resistance, volume stability, high thermal conductivity, and good resistance to penetration and erosion, solving the problems of easy damage and frequent maintenance after blast furnace lining repair, and ensuring long-term continuous and stable operation of the blast furnace.

[0005] To achieve the above objectives, the following technical solution is adopted: A corundum-silicon carbide self-flowing material is provided, comprising, by mass percentage: The composition comprises: 50-70% dense corundum particles, 10-20% dense corundum powder, 10-20% silicon carbide, 3-6% Al2O3 micro powder, 1-2% activating powder, 0.5-2% curing agent, 1-2% tungsten oxide, and 1-2% metallic silicon; plus 8-11% by weight of the above raw materials in the form of silica sol; wherein: The activated powder is prepared by high-energy ball milling of tungsten oxide and carbon black in a mass ratio of 5:1~2, followed by silica sol coating, drying, and finally ball milling.

[0006] According to the above scheme, the high-energy ball mill activation process is as follows: rotation speed 350~400 rpm, time 10~15h.

[0007] According to the above scheme, the milling medium during high-energy ball milling activation is anhydrous ethanol; no milling medium is added during ball milling.

[0008] According to the above scheme, the silica sol added during the preparation of the activated powder is 5 to 10 wt% of the total mass of tungsten oxide and carbon black.

[0009] According to the above scheme, the ball milling process is as follows: rotation speed 150~200 rpm, time 5~10 min.

[0010] According to the above plan, the drying conditions are: vacuum drying at 60-80℃.

[0011] According to the above scheme, the dense corundum particles contain Al2O3 ≥ 98%, and the particle size is composed of 0~1mm, 1~3mm, 3~5mm, and 5~8mm in mass percentages of 20~25%, 25~30%, 30~40%, and 12~20%, respectively.

[0012] According to the above scheme, the dense corundum powder contains Al2O3 ≥ 98% and has a particle size ≤ 0.074 mm.

[0013] According to the above scheme, the silicon carbide contains ≥98% SiC and is composed of 0~1 mm and 0~0.074 mm silicon carbide mixed at a mass ratio of 2~4:1~2.

[0014] According to the above scheme, the Al2O3 micro powder meets the following requirements: Al2O3 ≥ 99%, D 50 ≤1.7μm.

[0015] According to the above scheme, the curing agent is magnesium oxide.

[0016] According to the above scheme, the tungsten oxide content is ≥98% and D50≤20μm.

[0017] According to the above scheme, the carbon black contains C ≥ 97% and D50 is 300~500nm.

[0018] According to the above scheme, the Si content in the metallic silicon is ≥98%, and the particle size is ≤0.045mm.

[0019] According to the above scheme, the silica sol has a solid content of 39-41%, a pH of 7-9, and an average particle size of 10-20 nm.

[0020] A method for preparing the above-mentioned corundum-silicon carbide self-flowing material is provided, comprising the following steps: Dense corundum particles, dense corundum powder, silicon carbide, Al2O3 micro powder, curing agent, tungsten oxide, metallic silicon and activating powder are mixed together, and then silica sol is added and stirred evenly to obtain corundum-silicon carbide self-flowing material.

[0021] According to the above plan, the mixing time is 3-5 minutes.

[0022] According to the above scheme, the preparation of the activated powder includes the following steps: 1) Tungsten oxide and carbon black were activated by high-energy ball milling until the powder particle size was nanometers; 2) Add silica sol to the powder obtained in step 1), stir evenly, and then vacuum dry to obtain a silica sol-coated tungsten oxide-carbon black composite activation mixture; 3) The tungsten oxide-carbon black composite activation mixture obtained in step 2) is ball-milled to obtain activation powder.

[0023] Preferably, in step 1), the high-energy ball milling process conditions are: a rotation speed of 350~400 rpm and a high-energy ball milling time of 10~15 h.

[0024] Preferably, in step 1), the high-energy ball milling medium is anhydrous ethanol.

[0025] Preferably, in step 2), vacuum drying is performed at 60~80℃.

[0026] Preferably, in step 2), the amount of silica sol added is 5-10 wt% of the total mass of tungsten oxide and carbon black.

[0027] Preferably, in step 3), the ball milling process conditions are: rotation speed of 150~200 rpm and time of 5~10 min.

[0028] The temperature of the blast furnace lining varies depending on its location. The upper and middle parts of the furnace body are in the medium-temperature zone, with a relatively low temperature of 800~1000℃. This zone is subject to the erosion and wear of materials, and the lining should have good wear resistance, dust erosion resistance, and good thermal stability. The middle and belly parts of the furnace body are high-temperature zones, with temperatures as high as 1300~1500℃. These are harsh working conditions, requiring the lining material to have good corrosion resistance, high high-temperature strength, high thermal conductivity, and good thermal shock resistance.

[0029] This invention provides a corundum-silicon carbide self-flowing material, with dense corundum particles, dense corundum powder, and silicon carbide as the main components, combined with Al2O3 micro powder, curing agent, tungsten oxide, metallic silicon, and silica sol, and further synergistically activated powder, to achieve improved performance for different temperature ranges. The specific mechanism is as follows: By activating carbon black and tungsten oxide through high-energy ball milling and reducing the particle size to the nanoscale, a large number of microscopic defects such as lattice distortion and carbon atom vacancies are induced, forming high-density unsaturated bonds and ultra-high-activity carbon reaction sites. This achieves close solid-phase contact at the nanoscale, avoids long-distance diffusion mass transfer, significantly reduces the reaction activation energy, and lowers the reaction temperature to 800~1000℃. High thermal conductivity tungsten carbide ultra-hard particle phases can be generated in situ in the mid-temperature region, which pin grain boundaries and inhibit grain slip within the material. At the same time, the externally coated silica sol reacts with alumina to form mullite, which interweaves with tungsten carbide to form a dense reinforcing skeleton structure, giving the material good wear resistance, erosion resistance, and thermal conductivity in the mid-temperature region of the blast furnace body.

[0030] Meanwhile, in the high-temperature zone of the furnace waist and belly, where the temperature reaches 1300~1500℃, tungsten oxide and silicon in the self-flowing material can generate tungsten silicide in situ at temperatures above 1300℃. This tungsten silicide covers the material surface, forming a continuous and dense protective film and blocking pores. As a high-temperature surface protective phase, it effectively prevents alkaline slag from penetrating and eroding the material. The in-situ generated high thermal conductivity tungsten carbide and tungsten silicide, together with the silicon carbide matrix, form a high thermal conductivity system for the material, creating suitable conditions for slag skin formation: it can quickly dissipate heat from the furnace wall, reduce the surface temperature of the lining, and promote the rapid solidification and adhesion of molten slag, forming a uniform, dense, structurally stable, and non-detachable protective slag skin to protect the furnace lining, thus forming a "slag skin-furnace lining" dual protection system. At the same time, it also improves the toughness and wear resistance of the material, alleviates thermal shock cracks, and extends the service life of the furnace lining. In addition, the reaction of activated alumina and silicon dioxide to form needle-like mullite improves volume stability and, together with silicon carbide, tungsten carbide and tungsten silicide, forms an interwoven continuous solid solution structure, thereby optimizing the material's wear resistance, corrosion resistance, thermal shock resistance and high thermal conductivity.

[0031] The beneficial effects of this invention are as follows: 1. This invention provides a corundum-silicon carbide self-flowing material, which improves the performance requirements of blast furnace linings at different temperature zones. Specifically, it achieves good wear resistance, erosion resistance, and thermal conductivity in the upper-middle temperature zone of the blast furnace lining; while in the high-temperature zone of the furnace waist and belly, it optimizes the material's wear resistance, erosion resistance, thermal shock resistance, and high thermal conductivity. The self-flowing material obtained by this invention has the characteristics of high strength, wear resistance, erosion resistance, volume stability, good thermal conductivity, and resistance to alkali erosion. It solves the problems of easy damage and frequent maintenance after blast furnace lining repair, ensuring long-term continuous and stable operation of the blast furnace, and has broad application prospects.

[0032] 2. This invention provides a method for preparing the above-mentioned self-flowing material, which is simple in process, mild in conditions, and suitable for industrial applications. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] This invention provides a corundum-silicon carbide self-flowing material, comprising, by mass percentage: The composition consists of 50-70% dense corundum particles, 10-20% dense corundum powder, 10-20% silicon carbide, 3-6% Al2O3 micro powder, 1-2% industrial tungsten oxide, 0.5-2% curing agent, 1-2% tungsten oxide, and 1-2% metallic silicon; the sum of the mass percentages of the above components is 100%, plus 8-11% by weight of silica sol.

[0035] In the following detailed implementation method, the specific indicators of each raw material are as follows: In the dense corundum particles, Al2O3≥98%, and the particle size is composed of 0~1mm, 1~3mm, 3~5mm, and 5~8mm in mass percentages of 20~25%, 25~30%, 30~40%, and 12~20%, respectively.

[0036] In dense corundum powder, Al2O3 ≥ 98% and particle size ≤ 0.074 mm.

[0037] In silicon carbide, SiC ≥ 98% is composed of 0 ~ 1 mm and 0 ~ 0.074 mm particles mixed at a mass ratio of 2 ~ 4: 1 ~ 2.

[0038] Al2O3 micro powder must meet the following requirements: Al2O3 ≥ 99%, D 50 ≤1.7μm.

[0039] The curing agent is magnesium oxide.

[0040] In tungsten oxide, the tungsten oxide content is ≥98%, and D50≤20μm.

[0041] In carbon black, the C content is ≥97% and the D50 is 300~500nm.

[0042] In metallic silicon, the Si content is ≥98% and the particle size is ≤0.045mm.

[0043] Silica sol, solid content 40%, pH=7~9, average particle size 10~20nm.

[0044] The preparation method of the corundum-silicon carbide self-flowing material according to the embodiments of the present invention includes the following steps: 1) After sealing the tungsten oxide and carbon black in a high-energy ball mill jar according to the proportion, add cemented carbide grinding balls. The mass ratio of the ball to the material is tungsten oxide: carbon black 5:1. The rotation speed is 380 rpm and the ball milling time is 15 h. The ball milling medium is anhydrous ethanol. The powder is ball milled to a particle size of 50~100 nm.

[0045] 2) Slowly add silica sol (6wt% of the total mass of tungsten oxide and carbon black) to the slurry, stir evenly, and then vacuum dry at 70°C to remove ethanol to obtain a silica sol-coated tungsten oxide-carbon black composite activation mixture.

[0046] 3) Place the activated mixture back into the ball mill and ball mill without adding any ball milling media. The speed is 180 rpm and the ball milling time is 8 minutes. Then take out the activated powder for later use.

[0047] 4) Weigh out the dense corundum particles, dense corundum powder, silicon carbide, Al2O3 micro powder, curing agent, tungsten oxide, metallic silicon and activating powder according to the proportion and mix for 3 minutes. Then add the silica sol evenly to the mixture and stir evenly to obtain the self-flowing castable.

[0048] Construction is carried out using a pumping and pouring method.

[0049] Example 1 A corundum-silicon carbide self-flowing material and its preparation method are provided, the composition of which, by mass percentage, is as follows: The composition consists of 52% dense corundum particles, 18.8% dense corundum powder, 18% silicon carbide, 5% Al2O3 micro powder, 2% activating powder, 1.6% curing agent, 1.1% tungsten oxide, and 1.5% metallic silicon. The above components constitute 100% by weight, plus 10.2% by weight of silica sol.

[0050] Tests showed that the material has a thermal conductivity of 8.7 W / mK at 1400℃ and a wear resistance of 2.5 cm at 1000℃. 3 After being fired at 1400℃, a dense film is formed on the surface of the material, which effectively blocks the erosion and penetration of the medium.

[0051] Example 2 A corundum-silicon carbide self-flowing material and its preparation method are provided, the composition of which, by mass percentage, is as follows: The composition consists of 58% dense corundum particles, 16.4% dense corundum powder, 18% silicon carbide, 3% Al2O3 micro powder, 1% activating powder, 1.1% curing agent, 1.5% tungsten oxide, and 1% metallic silicon; the above components constitute 100% by weight, plus 9.8% by weight of silica sol.

[0052] Tests showed that the material has a thermal conductivity of 8 W / mK at 1400℃ and a wear resistance of 2.8 cm at 1000℃. 3After being fired at 1400℃, a dense film is formed on the surface of the material, which effectively blocks the erosion and penetration of the medium.

[0053] Example 3 A corundum-silicon carbide self-flowing material and its preparation method are provided, the composition of which, by mass percentage, is as follows: The composition comprises 65% dense corundum particles, 13.8% dense corundum powder, 12% silicon carbide, 4% Al2O3 micro powder, 1.5% activating powder, 0.7% curing agent, 1.8% tungsten oxide, and 1.2% metallic silicon; the above components constitute 100% by weight, plus 9.1% by weight of silica sol.

[0054] Tests showed that the material has a thermal conductivity of 7.6 W / mK at 1400℃ and a wear resistance of 2.8 cm at 1000℃. 3 After being fired at 1400℃, a dense film is formed on the surface of the material, which effectively blocks the erosion and penetration of the medium.

[0055] Example 4 A corundum-silicon carbide self-flowing material and its preparation method are provided, the composition of which, by mass percentage, is as follows: The composition consists of 70% dense corundum particles, 11.6% dense corundum powder, 10% silicon carbide, 3% Al2O3 micro powder, 1.7% activating powder, 0.6% curing agent, 1.3% tungsten oxide, and 1.8% metallic silicon; the above components constitute 100% by weight, plus 8.5% by weight of silica sol.

[0056] Tests showed that the material has a thermal conductivity of 7.5 W / mK at 1400℃ and a wear resistance of 2.6 cm at 1000℃. 3 After being fired at 1400℃, a dense film is formed on the surface of the material, which effectively blocks the erosion and penetration of the medium.

[0057] Example 5 A corundum-silicon carbide self-flowing material and its preparation method are provided, the composition of which, by mass percentage, is as follows: The composition consists of 60% dense corundum particles, 16% dense corundum powder, 14% silicon carbide, 4% Al2O3 micro powder, 1.3% activating powder, 1% curing agent, 1.7% tungsten oxide, and 2% metallic silicon; the above components constitute 100% by weight, plus 9.6% by weight of silica sol.

[0058] Tests showed that the material has a thermal conductivity of 7.7 W / mK at 1400℃ and a wear resistance of 2.9 cm at 1000℃. 3 After being fired at 1400℃, a dense film is formed on the surface of the material, which effectively blocks the erosion and penetration of the medium.

[0059] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A corundum-silicon carbide self-flowing material, characterized in that, By weight percentage, the raw materials include: The composition comprises: 50-70% dense corundum particles, 10-20% dense corundum powder, 10-20% silicon carbide, 3-6% Al2O3 micro powder, 1-2% activating powder, 0.5-2% curing agent, 1-2% tungsten oxide, and 1-2% metallic silicon; plus 8-11% by weight of the above raw materials in the form of silica sol; wherein: The activated powder is prepared by high-energy ball milling of tungsten oxide and carbon black in a mass ratio of 5:1~2, followed by silica sol coating, drying, and finally ball milling.

2. The self-flowing material according to claim 1, characterized in that, The high-energy ball milling activation process is: rotation speed 350~400 rpm, time 10~15 h; the ball milling process is: rotation speed 150~200 rpm, time 5~10 min.

3. The self-flowing material according to claim 1, characterized in that, During high-energy ball milling activation, anhydrous ethanol is used as the milling medium; no milling medium is added during ball milling.

4. The self-flowing material according to claim 1, characterized in that, During the preparation of the activated powder, the added silica sol is 5-10 wt% of the total mass of tungsten oxide and carbon black.

5. The self-flowing material according to claim 1, characterized in that, The dense corundum particles contain Al2O3 ≥ 98%, and the particle size is composed of 0~1mm, 1~3mm, 3~5mm, and 5~8mm in mass percentages of 20~25%, 25~30%, 30~40%, and 12~20%, respectively. The dense corundum powder contains Al2O3 ≥ 98% and has a particle size ≤ 0.074 mm. The silicon carbide contains ≥98% SiC and is composed of 0~1 mm and 0~0.074 mm silicon carbide mixed in a mass ratio of 2~4:1~2. The Al2O3 micro powder meets the following requirements: Al2O3 ≥ 99%, D 50 ≤1.7μm; The curing agent is magnesium oxide; The silicon metal has a Si content of ≥98% and a particle size of ≤0.045mm. The silica sol has a solid content of 39-41%, a pH of 7-9, and an average particle size of 10-20 nm.

6. The self-flowing material according to claim 1, characterized in that, The tungsten oxide has a tungsten oxide content of ≥98% and a D50 of ≤20μm; the carbon black has a C content of ≥97% and a D50 of 300~500nm.

7. A method for preparing the corundum-silicon carbide self-flowing material according to any one of claims 1-6, characterized in that, Includes the following steps: Dense corundum particles, dense corundum powder, silicon carbide, Al2O3 micro powder, curing agent, tungsten oxide, metallic silicon and activating powder are mixed together, and then silica sol is added and stirred evenly to obtain corundum-silicon carbide self-flowing material.

8. The preparation method according to claim 7, characterized in that, Mixing time is 3-5 minutes.

9. The preparation method according to claim 7, characterized in that, The preparation of the activated powder includes the following steps: 1) Tungsten oxide and carbon black were activated by high-energy ball milling until the powder particle size was nanometers; 2) Add silica sol to the powder obtained in step 1), stir evenly, and then vacuum dry to obtain a silica sol-coated tungsten oxide-carbon black composite activation mixture; 3) The composite activation mixture obtained in step 2) is ball-milled to obtain activation powder.

10. The preparation method according to claim 9, characterized in that, In step 1), the high-energy ball milling process conditions are: rotation speed of 350~400 rpm, time of 10~15 h; and the high-energy ball milling medium is anhydrous ethanol. In step 2), the amount of silica sol added is 5-10 wt% of the total mass of tungsten oxide and carbon black. In step 3), the ball milling process conditions are: rotation speed of 150~200 rpm and time of 5~10 min.