Anti-pore covering film and sand preparation method thereof
By optimizing the combination of ceramic sand and iron trioxide and combining with cyanate-modified phenolic resin, the porosity problem in the coating sand process is solved, and efficient gas escape and casting quality improvement is achieved.
Patent Information
- Application Number
- CN202510537694.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-27
- Publication Date
- 2025-08-26
AI Technical Summary
In the existing coating sand process, frequent pore defects in castings occur, resulting in a decrease in casting quality and an increase in production costs, and a lack of effective coordinated control schemes for gas generation and discharge paths.
Ceramic sand with a specific angle coefficient and high alumina content is used as aggregate, combined with functional coating of ferric oxide and cyanate-modified phenolic resin, to form a gas escape channel and inhibit gas generation. By defining the amount and particle size of ferric oxide, the chemical properties of the binder are optimized to reduce the decomposition of organic matter gas.
It significantly reduces the gas production of the coated sand, improves breathability and tensile strength, effectively controls pore defects, and improves the quality and pass rate of the castings.
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Figure CN120533003A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of coated sand production, and in particular to an anti-stomata film and a sand preparation method thereof. Background Art
[0002] With the rapid development of industry and increasingly stringent environmental protection requirements, casting molding processes are constantly being upgraded and optimized. Compared with the traditional green sand process, the coated sand shell process has the advantages of better casting surface quality, higher casting qualification rate, and better factory environment. Therefore, the coated sand shell process for casting is gradually replacing the traditional green sand process.
[0003] In the foundry industry, coated sand is the core material of sand casting, and its performance directly affects the quality of castings. Traditional coated sand mostly uses silica sand and other materials as aggregates, and improves strength and disintegration by adding phenolic resin, disintegrating agents, etc. However, the existing technology generally has the following problems: during the casting process, the inside of the sand core is prone to produce gas due to the high-temperature decomposition of organic matter, and the coated sand is not breathable enough, so the gas is difficult to escape quickly, resulting in frequent porosity defects in castings. According to statistics, when foundries use conventional coated sand technology, more than 50% of casting defects are caused by porosity, which seriously reduces the product qualification rate and increases production costs. Although some improvement plans have improved production efficiency or sand core strength by optimizing the cooling process or adjusting the resin ratio, there is still a lack of systematic solutions to the porosity problem, especially the lack of coordinated regulation of gas generation and exhaust paths.
[0004] In view of the above, there is an urgent need for an anti-pore coating and a sand preparation method thereof to solve the pore problem of castings in foundry enterprises and prepare high-quality castings to improve quality. Summary of the Invention
[0005] The present invention aims to solve the technical problems existing in the prior art and provides an anti-pore coating and a sand preparation method thereof, which solves the pore problem of castings in foundries and improves the quality of high-quality castings.
[0006] The technical method of the present invention to solve the above technical problems is as follows: S1. Take 100 parts of 50 / 100 ceramsite sand, the angular coefficient of which is less than 1.1 and the aluminum oxide content of which is greater than or equal to 60%; S2. Take 0.1-1.0 parts of ferric oxide, add ceramsite sand, and stir; S3. Heat the pre-treated ceramsite sand to 130-160℃ and put it into the sand mixer; S4. Add 0.5-1.5 parts of binder and stir; S5. Add 0.2-1.0 parts of curing agent and stir; S6. Add 0.1-0.5 parts of lubricant and stir; S7, obtaining the finished product of the anti-pore coated sand.
[0007] On the basis of the above technical method, the present invention can also be improved as follows.
[0008] Preferably, in step S2, the particle size of ferric oxide is in the range of 1000-2000 mesh.
[0009] Preferably, in step S4, the binder is cyanate-modified phenolic resin, and the binder cyanate-modified phenolic resin is added and stirred for 10 to 50 seconds.
[0010] Preferably, the polymerization rate of the cyanate-modified phenolic resin is 20-60s, and the softening point is 60-100°C.
[0011] Preferably, in step S5, the curing agent is a urotropine aqueous solution, and the curing agent urotropine aqueous solution is added and stirred for 10 to 50 seconds.
[0012] Preferably, the ratio of the urotropine aqueous solution is: urotropine: water = 2:1.
[0013] Preferably, in step S6, the lubricant is calcium stearate, and the lubricant calcium stearate is added and stirred for 10 to 50 seconds.
[0014] The present invention also provides anti-pore coated sand, which is prepared by adopting the above method.
[0015] The beneficial effects of the present invention are: The present invention achieves efficient control of pore defects from two dimensions: physical structure and chemical inhibition, through the synergistic effect of ceramsite sand matrix optimization, ferric oxide functional coating, and cyanate modified resin. The technical effects and mechanism of action are as follows: 1. The pore-draining function of the ceramsite sand matrix: Ceramsite sand with a specific angular coefficient (<1.1) and a high alumina content (≥60%) is used as the aggregate. Its spherical surface and internal pore structure form a continuous gas escape channel, significantly extending the gas diffusion path in the sand core and preventing gas stagnation and pore formation. At the same time, the high alumina content enhances the thermal stability of the sand and reduces the gas production caused by the sand's own decomposition at high temperatures.
[0016] 2. Ferric oxide's gas-regulating effect: By limiting the amount of ferric oxide added (0.1-1.0 parts per million) and its ultrafine particle size (≥1000 mesh), uniform coating of the ceramsite sand surface is achieved. On the one hand, ferric oxide fills the tiny gaps between sand particles, regulating the permeability of the coated sand and creating a stable pore distribution. On the other hand, at high temperatures, it undergoes an oxidation reaction with the resin decomposition products, preferentially consuming active gas components (such as hydrocarbons), reducing the total amount of gas.
[0017] 3. Synergistic Strengthening with Cyanate-Modified Resins: Through molecular structure optimization, cyanate-modified phenolic resins significantly reduce thermal decomposition gas generation while maintaining high bond strength. Working synergistically with ferric oxide, they further inhibit the decomposition and gas production of organic matter, forming a dual gas suppression mechanism of "physical decontamination and chemical depletion." BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 Schematic diagram of the process for preparing the anti-pore coated sand according to the present invention; DETAILED DESCRIPTION The principles and features of the present invention are described below. The examples provided are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.
[0019] Example 1 This embodiment provides an anti-pore coated sand, wherein the raw materials are mixed according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0020] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0021] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0022] Example 2: The difference between this example and Example 1 is that the angular coefficient of the ceramsite sand is 1.06 and the aluminum oxide content is 67%.
[0023] This embodiment provides an anti-pore coated sand, wherein the raw materials are mixed according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0024] The angular coefficient of ceramsite sand is 1.06, and the aluminum oxide content is 67%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0025] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0026] Example 3: The difference between this example and Example 1 is that the angular coefficient of the ceramsite sand is 1.02 and the aluminum oxide content is 71%.
[0027] This embodiment provides an anti-pore coated sand, wherein the raw materials are mixed according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0028] The angular coefficient of ceramsite sand is 1.02, and the aluminum oxide content is 71%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0029] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0030] Example 4: The difference between this example and Example 1 is only 0.1 part of ferric oxide. This embodiment provides an anti-pore coated sand, wherein the raw materials are mixed according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.1 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0031] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0032] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.1 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0033] Example 5: The difference between this example and Example 1 is only 0.9 parts of ferric oxide. This embodiment provides an anti-pore coated sand, wherein the raw materials are mixed according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.9 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0034] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0035] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.9 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0036] Example 6: The only difference between this example and Example 1 is that the angular coefficient of the ceramsite sand is 1.02, the content of aluminum oxide is 71%, and the content of iron oxide is 0.5.
[0037] This embodiment provides an anti-pore coated sand, wherein the raw materials are mixed according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0038] The angular coefficient of ceramsite sand is 1.02, and the aluminum oxide content is 71%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0039] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0040] Example 7: The only difference between this example and Example 1 is that the particle size of ferric oxide is 1000 mesh.
[0041] This embodiment provides an anti-pore coated sand, wherein the raw materials are mixed according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0042] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The particle size of ferric oxide is 1000 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0043] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0044] Comparative Example 1: The difference between this comparative example and Example 1 is that the ceramsite sand in step S1 is changed to silica sand, and the other implementation methods and conditions are the same as those in the example.
[0045] This comparative example provides a coated sand, wherein the raw materials are prepared according to parts by weight, including 100 parts of silica sand, 0.5 parts of ferric oxide, 0.9 parts of a binder cyanate-modified phenolic resin, 0.5 parts of a curing agent urotropine aqueous solution, and 0.2 parts of a lubricant calcium stearate.
[0046] The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0047] The preparation process is as follows: S1, take 100 parts of silica sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated silica sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0048] Comparative Example 2: The difference between this comparative example and Example 1 is that step 2 is removed and the ferric oxide pretreatment is not performed. Other implementation methods and conditions are the same as those in the example.
[0049] This comparative example provides a coated sand, wherein the raw materials are prepared according to parts by weight, wherein 100 parts of 50 / 100 ceramsite sand, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant are taken.
[0050] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0051] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2. Heat the ceramsite sand to 150℃ and put it into the sand mixer; S3, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S4, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S5, add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S6, obtaining the finished product of the anti-pore coated sand.
[0052] Comparative Example 3: The difference between this comparative example and Example 1 is only that step S4 is changed to ordinary phenolic resin, and other implementation methods and conditions are the same as those in the example.
[0053] This comparative example provides a coated sand, wherein the raw materials are prepared according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of ordinary phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0054] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0055] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of binder phenolic resin and stir for 30 seconds, wherein the polymerization speed of phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0056] Comparative Example 4: The difference between this comparative example and Example 1 is that the angular coefficient of the ceramsite sand is 1.12 and the aluminum oxide content is 55%.
[0057] This comparative example provides a coated sand, wherein the raw materials are prepared according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0058] The angular coefficient of ceramsite sand is 1.12, and the aluminum oxide content is 55%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0059] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0060] Comparative Example 5: The difference between this comparative example and Example 1 is that the angular coefficient of the ceramsite sand is 1.15 and the aluminum oxide content is 57%.
[0061] This comparative example provides a coated sand, wherein the raw materials are prepared according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0062] The angular coefficient of ceramsite sand is 1.15, and the aluminum oxide content is 57%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0063] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0064] Comparative Example 6: The difference between this comparative example and Example 1 is only 0.05 parts of ferric oxide. This comparative example provides a coated sand, wherein the raw materials are prepared according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.05 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0065] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0066] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.05 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0067] Comparative Example 7: The difference between this comparative example and Example 1 is only 3 parts of ferric oxide. This comparative example provides a coated sand, wherein the raw materials are prepared according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 3 parts of ferric oxide, 0.9 parts of a binder cyanate-modified phenolic resin, 0.5 parts of a curing agent urotropine aqueous solution, and 0.2 parts of a lubricant calcium stearate.
[0068] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The particle size of ferric oxide is 1200 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0069] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2. Take 3 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0070] Comparative Example 8: The only difference between this comparative example and Example 1 is that the particle size of ferric oxide is 500 mesh. This comparative example provides a coated sand, wherein the raw materials are prepared according to parts by weight, including 100 parts of 50 / 100 ceramsite sand, 0.5 parts of ferric oxide, 0.9 parts of cyanate-modified phenolic resin as a binder, 0.5 parts of urotropine aqueous solution as a curing agent, and 0.2 parts of calcium stearate as a lubricant.
[0071] The angular coefficient of ceramsite sand is 1.02, and the content of aluminum oxide is 67%; The particle size of ferric oxide is 500 mesh; The ratio of urotropine aqueous solution: urotropine: water = 2:1.
[0072] The preparation process is as follows: S1, take 100 parts of 50 / 100 ceramsite sand; S2, take 0.5 parts of ferric oxide, add ceramsite sand, and stir; S3, heat the pre-treated ceramsite sand to 150℃ and put it into the sand mixer; S4, add 0.9 parts of cyanate-modified phenolic resin as a binder and stir for 30 seconds, wherein the polymerization speed of the cyanate-modified phenolic resin is 50 seconds and the softening point is 80°C; S5, add 0.5 parts of curing agent urotropine aqueous solution and stir for 30 seconds; S6. Add 0.2 parts of lubricant calcium stearate and stir for 30 seconds; S7, obtaining the finished product of the anti-pore coated sand.
[0073] The coated sands prepared in the above Examples 1-7 and Comparative Examples 1-8 were tested respectively.
[0074] The test methods for tensile strength, gas evolution and air permeability refer to the standard GB / T2684-2009.
[0075] Among them, the air permeability of the sand core indicates the efficiency of gas passing through; the tensile strength indicates the strength of the sand core; and the gas generation volume indicates the amount of gas generated by the sand core.
[0076] The coated sands prepared in Examples 1-7 and Comparative Examples 1-8 were used to cast castings respectively; the porosity rate of the castings was calculated by casting 100 castings and calculating the qualified rate. The test results are shown in Table 1.
[0077] Table 1 Performance test results of various coated sands:
[0078] Performance test data of the embodiments of the present invention and the comparative examples Figure 1 It shows that the anti-pore coated sand of the present invention exhibits excellent comprehensive performance under the synergistic effect of the angular coefficient of the ceramsite sand, the content of aluminum oxide and the ratio of ferric oxide. The coated sand of all embodiments is significantly better than the comparative example in terms of tensile strength, gas generation, air permeability and the incidence of pores in castings. Specifically, the tensile strength of the coated sand of the embodiment is maintained at a high level, the gas generation is significantly reduced, the air permeability is improved, and the incidence of pores in castings is controlled within an extremely low range, indicating that the technical solution of the present invention can effectively inhibit the formation of pores and improve the quality of castings. The following is an analysis from the perspective of key indicator comparison and technical effects: The impact of ceramsite sand properties on performance: Test results for Comparative Example 1 (replacing ceramsite sand with silica sand) show a significant decrease in tensile strength and air permeability, and a significant increase in the incidence of porosity in the castings. This demonstrates that the unique angularity coefficient and aluminum oxide content of ceramsite sand are crucial for improving sand core density and gas escape efficiency. In Comparative Examples 4 and 5, when the angularity coefficient or aluminum oxide content of the ceramsite sand exceeded the specified ranges, the tensile strength significantly deteriorated and the porosity increased significantly, further validating the parameter ranges for ceramsite sand: an angularity coefficient of <1.1 and an aluminum oxide content of ≥60%.
[0079] Effect of the amount of ferric oxide: Comparative Example 2 (unpretreated ferric oxide) showed a significant increase in gas generation and a sharp rise in the incidence of pores, indicating that the ferric oxide pretreatment step plays a key role in suppressing gas generation. Furthermore, in Comparative Examples 6 and 7, when the amount of ferric oxide exceeded the specified range of 0.1 to 1.0 parts per part, gas generation and pore incidence increased, demonstrating the necessity of strict control of its dosage.
[0080] Effect of ferric oxide particle size: The test results of comparative example 8 (particle size is too large) show that its tensile strength and pore suppression effect are significantly inferior to those of the embodiment, indicating that ultrafine particle size ferric oxide is more conducive to uniform dispersion and sufficient oxidation reaction.
[0081] Advantages of cyanate-modified phenolic resin: The tensile strength of Comparative Example 3 (ordinary phenolic resin) was significantly reduced, and the gas emission increased significantly, proving that cyanate modification can effectively improve the thermal stability and bonding strength of the resin while reducing gas release at high temperatures.
[0082] Optimal Example Results: Example 7, the optimal implementation, achieves a balance between tensile strength and air permeability by optimizing the ferric oxide particle size and ceramic sand parameters. Gas generation is maintained at an extremely low level, with the incidence of porosity in the castings near zero. Compared to the other examples, this method offers superior overall performance, making it particularly suitable for the production of high-precision castings.
[0083] Comparative Examples Defect Analysis: All comparative examples exhibit significant degradation in at least one performance indicator due to deviations from the components or process parameters of the present invention. For example, comparative example 1 exhibits insufficient air permeability, comparative example 2 exhibits excessive gas evolution, and comparative example 3 exhibits insufficient strength. These findings further highlight the necessity of the synergistic effects of the components and the rationality of the parameter ranges in the present invention.
[0084] Tests conducted on the examples of the present invention show that the porosity of castings made from the coated sand of the present invention approaches zero, while both tensile strength and air permeability are superior to those of Comparative Examples 1-8. Specifically, when the angular coefficient and alumina content of the ceramsite sand exceed the ranges of the present invention (Comparative Examples 4-5), the porosity significantly increases; when the amount of ferric oxide is insufficient or excessive (Comparative Examples 6-7), or the particle size is too large (Comparative Example 8), the gas control capability deteriorates; and when the cyanate ester-modified resin is not used (Comparative Example 3), gas generation increases and sand core strength decreases.
[0085] In summary, by limiting the angular modulus and aluminum oxide content of the ceramsite sand, combining it with a specific particle size and dosage range of ferric oxide, and combining it with a cyanate-modified phenolic resin, this invention significantly improves the tensile strength and air permeability of the coated sand, while significantly reducing gas generation and the incidence of porosity in castings. Test data fully validates the scientific and practical nature of the technical effects and scope of protection of this invention, making it particularly suitable for precision castings, which are sensitive to porosity defects.
[0086] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A method for preparing anti-pore coated sand, characterized in that: The following steps are involved: S1. Take 100 parts of 50 / 100 ceramsite sand, the angular coefficient of which is less than 1.1 and the aluminum oxide content of which is greater than or equal to 60%; S2. Take 0.1-1.0 parts of ferric oxide, add ceramsite sand, and stir; S3. Heat the pre-treated ceramsite sand to 130-160℃ and put it into the sand mixer; S4. Add 0.5-1.5 parts of binder and stir; S5. Add 0.2-1.0 parts of curing agent and stir; S6. Add 0.1-0.5 parts of lubricant and stir; S7, obtaining the finished product of the anti-pore coated sand.
2. The method for preparing anti-pore coated sand according to claim 1, characterized in that: In step S2, the particle size of ferric oxide ranges from 1000 to 2000 mesh.
3. The method for preparing anti-pore coated sand according to claim 1, characterized in that: In step S4, the binder is cyanate-modified phenolic resin, and the binder cyanate-modified phenolic resin is added and stirred for 10 to 50 seconds.
4. The method for preparing anti-pore coated sand according to claim 3, characterized in that: The polymerization speed of the cyanate-modified phenolic resin is 20-60s, and the softening point is 60-100°C.
5. The method for preparing anti-pore coated sand according to claim 4, characterized in that, in step S5, the curing agent is a urotropine aqueous solution, and the curing agent urotropine aqueous solution is added and stirred for 10 to 50 seconds.
6. The method for preparing anti-pore coated sand according to claim 5, characterized in that: The ratio of urotropine aqueous solution is: urotropine: water = 2:
1.
7. The method for preparing anti-pore coated sand according to claim 1, characterized in that: In step S6, the lubricant is calcium stearate, and the lubricant calcium stearate is added and stirred for 10 to 50 seconds. 8.An anti-pore coated sand, characterized in that: The method according to any one of claims 1 to 7 is used to prepare the product.