Preparation method of ferrosilicon and nano silicon carbide composite nodular cast iron inoculation enhancer
By tightly covering nano-silicon carbide particles on the surface of ferrosilicon to prepare ferrosilicon @ nano-silicon carbide composite ductile iron incubation enhancer, the problem of limited performance improvement of traditional ductile iron is solved, and better mechanical performance improvement and uniform distribution effect are achieved.
Patent Information
- Application Number
- CN202510319827.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-06-06
AI Technical Summary
The performance improvement of traditional ductile iron is limited, especially under high strength conditions, existing silicon carbide inoculants cannot effectively improve their mechanical properties.
By tightly covering a layer of nano-silicon carbide particles on the surface of ferrosilicon, ferrosilicon @ nano-silicon carbide composite ductile iron incubation enhancer is prepared, and high-temperature smelting and ball milling are used to ensure uniform mixing and coating effect.
This method not only reduces the agglomeration of silicon carbide, improves its uniform distribution and incubation effect in iron liquid, reduces pore defects, and improves the graphite sphere content and spherical shape of ductile cast iron, thereby significantly improving its mechanical properties.
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Figure CN120095155A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of preparation of inoculant enhancers. Background Art
[0002] In the foundry industry, ductile iron is widely used due to its excellent mechanical properties (such as high strength, high toughness and good wear resistance). However, the performance improvement of traditional ductile iron is limited, especially in the context of growing demand under high-strength conditions. In order to further improve the performance of ductile iron, researchers began to explore the optimization of its microstructure and mechanical properties by adding inoculation reinforcement phases. Silicon carbide has high hardness and high temperature resistance, and has excellent thermal stability under high-temperature casting conditions; and can react with elements in molten iron (such as silicon, carbon, and iron) at high temperatures to form fine inoculation cores; it also has a good strengthening effect, can improve the uniformity of the casting structure, improve the graphite morphology, and improve the mechanical properties of cast iron. It is one of the important components for improving the inoculation effect. However, silicon carbide particles tend to agglomerate in molten iron, affecting its uniform distribution and inoculation effect. Therefore, it is urgent to provide a new method for preparing silicon carbide composite inoculant enhancer. Summary of the invention
[0003] The present invention aims to solve the problem that the existing silicon carbide inoculant cannot effectively improve the mechanical properties of ductile iron, and further provides a method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculant enhancer.
[0004] A method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer is carried out according to the following steps:
[0005] 1. Mixing silica, coke and iron source to obtain a mixed material;
[0006] 2. Under stirring conditions, the mixed material is melted at high temperature to obtain a melt;
[0007] 3. Under stirring conditions, adding flux to the melt to remove slag at high temperature, and then standing to remove waste slag to obtain liquid ferrosilicon;
[0008] Fourth, pour the liquid ferrosilicon into a preheated cast iron mold, cool it to room temperature, obtain ferrosilicon blocks, and crush the ferrosilicon blocks to obtain ferrosilicon powder;
[0009] 5. Mixing the nano silicon carbide powder, the silane coupling agent and the water ball mill to obtain a mixed powder slurry;
[0010] 6. The mixed powder slurry and ferrosilicon powder are stirred evenly, and finally heated, dried, ground and crushed to obtain ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer.
[0011] The beneficial effects of the present invention are:
[0012] The present invention prepares a silicon carbide composite ductile iron inoculation enhancer by tightly coating a layer of nano silicon carbide particles on the surface of ferrosilicon. Different from simple mechanical mixing, coating the nano silicon carbide on the surface of ferrosilicon can not only reduce the agglomeration of silicon carbide, but also react with oxygen in the molten iron to reduce defects such as pores generated during the inoculation process of ductile iron. In addition, the silicon carbide composite inoculation enhancer can also increase the content and sphericity of graphite nodules in ductile iron, improve the uniformity of high casting structure, thereby better enhancing the inoculation effect, thereby enhancing the mechanical properties of ductile iron. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 The microscopic morphology spectrum of the ferrosilicon powder prepared in step 4 of Example 1;
[0014] Figure 2 The microscopic morphology of the ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer prepared in Example 1;
[0015] Figure 3 The microscopic morphology of the ductile iron surface prepared by using the ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer of Example 1;
[0016] Figure 4 The mechanical properties of ductile iron prepared by using ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer of Example 1 and Example 2. DETAILED DESCRIPTION
[0017] Specific implementation method 1: This implementation method is a method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer, which is carried out according to the following steps:
[0018] 1. Mixing silica, coke and iron source to obtain a mixed material;
[0019] 2. Under stirring conditions, the mixed material is melted at high temperature to obtain a melt;
[0020] 3. Under stirring conditions, adding flux to the melt to remove slag at high temperature, and then standing to remove waste slag to obtain liquid ferrosilicon;
[0021] Fourth, pour the liquid ferrosilicon into a preheated cast iron mold, cool it to room temperature, obtain ferrosilicon blocks, and crush the ferrosilicon blocks to obtain ferrosilicon powder;
[0022] 5. Mixing the nano silicon carbide powder, the silane coupling agent and the water ball mill to obtain a mixed powder slurry;
[0023] 6. The mixed powder slurry and ferrosilicon powder are stirred evenly, and finally heated, dried, ground and crushed to obtain ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer.
[0024] The beneficial effects of this embodiment are:
[0025] This embodiment prepares a silicon carbide composite ductile iron inoculation enhancer by tightly coating a layer of nano silicon carbide particles on the surface of ferrosilicon. Unlike simple mechanical mixing, coating the nano silicon carbide on the surface of ferrosilicon can not only reduce the agglomeration of silicon carbide, but also react with oxygen in the molten iron to reduce defects such as pores generated during the inoculation process of ductile iron. In addition, the silicon carbide composite inoculation enhancer can also increase the content and sphericity of graphite nodules in ductile iron, improve the uniformity of high casting structure, thereby better enhancing the inoculation effect, thereby enhancing the mechanical properties of ductile iron.
[0026] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: the mass ratio of silica to coke in step 1 is 1:(0.6-0.8); the mass ratio of silica to iron source in step 1 is 1:(0.5-0.7); the purity of silica in step 1 is greater than 98%, and the particle size is 1mm-5mm; the fixed carbon content in the coke in step 1 is ≥90wt%, and the particle size is 1mm-3mm; the iron source in step 1 is scrap steel or iron filings, and the particle size is 1mm-5mm. The rest is the same as specific implementation method 1.
[0027] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that: in step 2, the mixed material is smelted at high temperature for 1 h to 2 h under stirring and at a temperature of 1600° C. to 1800° C. to obtain a melt. The rest is the same as specific implementation method 1 or 2.
[0028] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: in step 3, under stirring and at a temperature of 1600°C to 1800°C, a flux is added to the melt for high-temperature slag removal for 10min to 20min, and then the melt is allowed to stand for 10min to 15min to remove the waste slag to obtain liquid ferrosilicon. The rest is the same as specific embodiment 3.
[0029] Specific implementation method 5: This implementation method is different from specific implementation methods 1 to 4 in that the flux in step 3 is limestone, and the mass of the flux in step 3 is 5% to 10% of the mass of the silica in step 1. Other aspects are the same as specific implementation methods 1 to 4.
[0030] Specific embodiment 6: This embodiment is different from specific embodiments 1 to 5 in that: in step 4, liquid ferrosilicon is poured into a cast iron mold preheated to a temperature of 200°C to 400°C, cooled to room temperature to obtain ferrosilicon blocks, and the ferrosilicon blocks are crushed to a particle size of 0.5mm to 20mm to obtain ferrosilicon powder. The rest is the same as specific embodiments 1 to 5.
[0031] Specific embodiment 7: This embodiment is different from specific embodiments 1 to 6 in that the ball milling mixing described in step 5 is specifically carried out for 10 hours to 30 hours at a rotation speed of 200 r / min to 600 r / min, a water-to-material mass ratio of (5 to 10):1, and a ball-to-material mass ratio of (2 to 6):1. The rest is the same as specific embodiments 1 to 6.
[0032] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that: the mass of the silane coupling agent described in step 5 is 0.5% to 2% of the mass of the nano-silicon carbide powder; the particle size of the nano-silicon carbide powder described in step 5 is 100nm to 500nm; the silane coupling agent described in step 5 is KH-550. Others are the same as specific embodiments 1 to 7.
[0033] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the mass ratio of the mixed powder slurry to the ferrosilicon powder in step 6 is 1:(5-20). The rest is the same as specific embodiments 1 to 8.
[0034] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that: in step 6, the mixed powder slurry and ferrosilicon powder are stirred for 6h to 8h at a stirring rate of 100r / min to 500r / min, and then heated and dried for 10h to 20h at a temperature of 100℃ to 150℃ using a rotary dryer, and finally ground and crushed to a particle size of 0.5mm to 5mm. The rest is the same as specific embodiments 1 to 9.
[0035] The following examples are used to verify the beneficial effects of the present invention:
[0036] Embodiment 1:
[0037] A method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer is carried out according to the following steps:
[0038] 1. Mixing silica, coke and iron source to obtain a mixed material;
[0039] The mass ratio of silica to coke is 1:0.7; the mass ratio of silica to iron source is 1:0.6; the purity of silica is greater than 98%, and the average particle size is 3 mm; the fixed carbon content in the coke is about 90wt%, and the average particle size is 2 mm; the iron source is scrap steel, and the average particle size is 4 mm;
[0040] 2. Under stirring and at a temperature of 1750°C, the mixture is smelted at high temperature for 2 hours to obtain a melt;
[0041] 3. Under stirring and temperature of 1750°C, add flux to the melt and remove slag at high temperature for 15 minutes, then let it stand for 15 minutes to remove waste slag to obtain liquid ferrosilicon;
[0042] The flux is limestone; the mass of the flux is 5% of the mass of the silica in step 1;
[0043] Fourth, pour the liquid ferrosilicon into a cast iron mold preheated to 300°C, cool to room temperature to obtain ferrosilicon blocks, and crush the ferrosilicon blocks to an average particle size of 1 mm to obtain ferrosilicon powder;
[0044] 5. At a rotation speed of 300 r / min, a water-to-material mass ratio of 10:1 and a ball-to-material mass ratio of 5:1, the nano-silicon carbide powder, the silane coupling agent and water were ball-milled for 20 hours to obtain a mixed powder slurry;
[0045] The mass of the silane coupling agent is 0.8% of the mass of the nano-silicon carbide powder; the average particle size of the nano-silicon carbide powder is 140nm; the silane coupling agent is KH-550;
[0046] 6. Stir the mixed powder slurry and ferrosilicon powder for 6 hours at a stirring rate of 200 r / min, then heat and dry for 12 hours at a temperature of 130° C. in a rotary dryer, and finally grind and crush to an average particle size of 1 mm to obtain ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer;
[0047] The mass ratio of the mixed powder slurry to ferrosilicon powder is 1:5.
[0048] Embodiment 2: This embodiment is different from Embodiment 1 in that the average particle size of the nano-SiC powder in step 5 is 500 nm. Other aspects are the same as Embodiment 1.
[0049] Figure 1 This is a microscopic morphology spectrum of the ferrosilicon powder prepared in step 4 of Example 1; as can be seen from the figure, the particle size of the ferrosilicon powder is about 1 mm, the size is uniform, and the surface is relatively smooth.
[0050] Figure 2 This is the microscopic morphology of the ferrosilicon@nano-silicon carbide composite ductile iron inoculant enhancer prepared in Example 1; as can be seen from the figure, the surface of the ferrosilicon is evenly and tightly coated with a layer of nano-silicon carbide particles, indicating that the ferrosilicon@nano-silicon carbide composite material was successfully prepared using the example method.
[0051] Ductile iron experimental castings were cast using industrial raw iron liquid. During the inoculation process, the ferrosilicon@nano-silicon carbide composite ductile iron inoculation enhancer and inoculant prepared in Examples 1 to 2 were added to obtain ductile iron, and the tests were performed as follows: the grade of the cast iron was QT-400, and the test block size was 500mm×500mm×500mm. First, pig iron, scrap steel and QT-400 recycled materials are smelted in a 12T medium frequency induction furnace, and then desulfurized, quenched and tempered to make the composition of the molten iron meet the requirements for casting QT-400 castings. The molten iron is kept warm at the tapping temperature, and the pouring process adopts the flow inoculation method. The amount of the ferrosilicon@nano silicon carbide composite ductile iron inoculant enhancer prepared in Examples 1 to 2 is 20% of the mass of the inoculant. The inoculant is the inoculant produced by Inner Mongolia Haite Huacai Technology Co., Ltd., and its mass percentage is: silicon: 40% to 75%, calcium: 0.5% to 2.5%, aluminum: 0.5% to 2.0%, manganese: 0.2% to 1.0%, iron: balance; the average particle size of the ductile iron inoculant is 1.5 mm, and the amount of the inoculant added is 0.2% of the total mass of the pig iron, scrap steel and QT-400 recycled materials.
[0052] Figure 3 This is a microscopic morphology map of the surface of ductile iron prepared using the ferrosilicon @ nano-silicon carbide composite ductile iron inoculation enhancer in Example 1; as can be seen from the figure, the ductile iron structure inoculated with ferrosilicon @ nano-silicon carbide has a large number of graphite nodules, good sphericity, more uniform distribution and size, and no defects such as pores.
[0053] Tested according to GB / T 228.1-2010 standard; Figure 4 The mechanical properties of ductile iron prepared by using ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer of Example 1 and Example 2; as can be seen from the figure, the mechanical strength of the ductile iron in Example 1 is very good, and the tensile strength reaches 439MPa.
Claims
1. A method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer, characterized in that It is carried out in the following steps:
1. Mixing silica, coke and iron source to obtain a mixed material; 2. Under stirring conditions, the mixed material is melted at high temperature to obtain a melt; 3. Under stirring conditions, adding flux to the melt to remove slag at high temperature, and then standing to remove waste slag to obtain liquid ferrosilicon; Fourth, pouring liquid ferrosilicon into a preheated cast iron mold, cooling to room temperature to obtain ferrosilicon blocks, and crushing the ferrosilicon blocks to obtain ferrosilicon powder; 5. Mixing the nano silicon carbide powder, the silane coupling agent and the water ball mill to obtain a mixed powder slurry; 6. The mixed powder slurry and ferrosilicon powder are stirred evenly, and finally heated, dried, ground and crushed to obtain ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer.
2. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that The mass ratio of silica to coke described in step one is 1:(0.6-0.8); the mass ratio of silica to iron source described in step one is 1:(0.5-0.7); the purity of silica described in step one is greater than 98%, and the particle size is 1mm-5mm; the fixed carbon content in the coke described in step one is ≥90wt%, and the particle size is 1mm-3mm; the iron source described in step one is scrap steel or iron filings, and the particle size is 1mm-5mm.
3. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that In step 2, the mixture is smelted at high temperature for 1 h to 2 h under stirring at a temperature of 1600° C. to 1800° C. to obtain a melt.
4. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that In step three, under stirring and at a temperature of 1600° C. to 1800° C., flux is added to the melt for high-temperature slag removal for 10 to 20 minutes, and then allowed to stand for 10 to 15 minutes to remove waste slag to obtain liquid ferrosilicon.
5. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that The flux described in step three is limestone; the mass of the flux described in step three is 5% to 10% of the mass of the silica in step one.
6. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that In step 4, the liquid ferrosilicon is poured into a cast iron mold preheated to a temperature of 200° C. to 400° C., cooled to room temperature to obtain ferrosilicon blocks, and the ferrosilicon blocks are crushed to a particle size of 0.5 mm to 20 mm to obtain ferrosilicon powder.
7. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that The ball milling mixing described in step 5 is specifically carried out for 10 hours to 30 hours at a rotation speed of 200 r / min to 600 r / min, a water-to-material mass ratio of (5 to 10):1, and a ball-to-material mass ratio of (2 to 6):
1.
8. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that The mass of the silane coupling agent described in step five is 0.5% to 2% of the mass of the nano-silicon carbide powder; the particle size of the nano-silicon carbide powder described in step five is 100nm to 500nm; the silane coupling agent described in step five is KH-550.
9. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that The mass ratio of the mixed powder slurry to ferrosilicon powder described in step six is 1:(5-20).
10. The method for preparing a ferrosilicon@nano silicon carbide composite ductile iron inoculation enhancer according to claim 1, characterized in that Step 6: Stir the mixed powder slurry and ferrosilicon powder for 6h to 8h at a stirring rate of 100r / min to 500r / min, then use a rotary dryer to heat and dry for 10h to 20h at a temperature of 100℃ to 150℃, and finally grind and crush to a particle size of 0.5mm to 5mm.