Alcohol-based low-zirconium coating and preparation method thereof

Abstract

This invention discloses an alcohol-based low-zirconium coating and its preparation method, specifically relating to the field of casting coating technology. The coating comprises 75%-85% modified refractory aggregate, 1%-3% organic binder, 3%-5% suspending agent, 1%-3% additives, and 5%-15% solvent. In the modified refractory aggregate, zircon powder accounts for 20%-40%, high-alumina powder for 50%-60%, aluminum sec-butoxide or aluminum acetylacetonate as a coating aluminum source for 5%-15%, and a silane coupling agent composed of KH550 and KH560 in a 1:1 ratio for 1.5%-2%. The coating aluminum source forms a uniform active alumina layer on the surface of the zircon powder, promoting in-situ formation of the mullite phase at high temperatures, significantly improving the high-temperature strength and anti-stripping properties of the coating. The bifunctional coupling agent enhances the interfacial bonding between the inorganic aggregate and the organic system, improving suspension stability and adhesion. The amount of zircon powder used is reduced by more than 50% compared to traditional coatings, and the preparation process is controllable, suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of casting coating technology, specifically relating to an alcohol-based low-zirconium coating and its preparation method. Background Technology

[0002] In casting production, alcohol-based coatings are widely used as protective materials for sand molds and cores due to their fast drying speed, good coatability, and low gas evolution, effectively preventing defects such as sand adhesion and inclusions in castings. Among them, zircon-based alcohol coatings, with zircon powder as the main refractory aggregate, occupy an important position in the production of high-end castings due to their excellent high-temperature refractoriness and chemical stability. However, zircon powder is expensive, and its large-scale use will significantly increase the production cost of coatings. Moreover, zircon powder itself has poor dispersibility and is prone to agglomeration, leading to easy peeling and insufficient bonding strength of the coating at high temperatures.

[0003] To reduce the amount of zircon powder used, high-alumina powder and other refractory aggregates are often used to partially replace zircon powder in physical mixing. However, simply reducing the amount of zircon powder often leads to a significant decrease in the high-temperature refractory performance of the coating, making it difficult to meet the stringent process requirements of high-end castings. Meanwhile, in a simple physical mixture of high-alumina powder and zircon powder, the contact area between the two particles is limited, making it difficult to fully and efficiently generate the reinforcing mullite phase (3Al2O3·2SiO2) at high temperatures, resulting in poor high-temperature structural strength and thermal shock resistance of the coating. Furthermore, impurities easily adhere to the surface of zircon powder, and the particle size distribution is uneven; direct use of zircon powder will seriously affect the uniformity and performance stability of the coating system. Therefore, developing a low-zirconium-content, high-performance alcohol-based coating that achieves efficient bonding of zircon powder and high-alumina powder through modification with an aluminum source, enabling the coating to generate a stable mullite phase at high temperatures, while balancing the economics and performance of the coating, has become a new and urgent problem to be solved in the field of casting coatings. Summary of the Invention

[0004] The purpose of this invention is to provide an alcohol-based low-zirconium coating and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: An alcohol-based low-zirconium coating, by mass fraction, comprises the following components: Modified refractory aggregate: 75%-85%; Organic binder: 1%-3%; Suspension agent: 3%-5%; Additives: 1%-3%; Solvent: 5%-15%; The modified refractory aggregate is prepared from raw materials including refractory aggregate, coated aluminum source and silane coupling agent; The refractory aggregate is composed of high alumina powder and zircon powder; and the mass ratio of zircon powder to high alumina powder is 30-40:50-60. Based on a total mass of 100 parts of the refractory aggregate, the amount of the coated aluminum source added is 5-15 parts, and the amount of the silane coupling agent added is 1.5-2.5 parts; The silane coupling agent is a compound of KH550 and KH560, with a compounding ratio of 1:1; The coated aluminum source is aluminum sec-butoxide or aluminum acetylacetone.

[0006] Furthermore, the organic binder is one or more of phenolic resin, rosin resin, polyvinyl butyral, and acrylic resin.

[0007] Furthermore, the suspending agent is one or more of organic bentonite and lithium-based bentonite.

[0008] Furthermore, the additive is fumed silica.

[0009] Furthermore, the solvent is one or more of anhydrous ethanol, methanol, and isopropanol.

[0010] Furthermore, the high-alumina powder is one or more of white corundum powder and bauxite powder, with a particle size of 200-400 mesh; the zircon powder has a particle size of 200-325 mesh.

[0011] Furthermore, the coated aluminum source is aluminum sec-butoxide, and its addition amount is 5 parts, 10 parts, or 15 parts.

[0012] Furthermore, the coated aluminum source is aluminum acetylacetonate, and its addition amount is 10 parts or 15 parts.

[0013] A method for preparing an alcohol-based low-zirconium coating includes the following steps: (a) Preparation of modified refractory aggregates: Step 1: Pre-treat the high alumina powder and zircon powder respectively: Dry the high alumina powder and zircon powder at 120℃ for 2 hours, and pass them through a 200-mesh sieve to obtain the pre-treated refractory aggregate; Step 2: Add a coated aluminum source to the pretreated refractory aggregate and mix evenly. Then dry it in an oven at 80°C for 4 hours to obtain the material to be sintered. When the coated aluminum source is aluminum sec-butoxide, first mix the aluminum sec-butoxide and ethanol at a mass ratio of 1:4 and stir at a speed of 300-500 r / min for 10 minutes. Then mix it with the pretreated refractory aggregate and stir at a speed of 500-800 r / min for 20-30 minutes. When the coated aluminum source is aluminum acetylacetonate, first mix the aluminum acetylacetonate and ethanol at a mass ratio of 1:5 and stir at a speed of 300-500 r / min for 10 minutes. Then mix it with the pretreated refractory aggregate and stir at a speed of 500-800 r / min for 20-30 minutes. Step 3: Grind the material to be sintered into powder and perform a two-step high-temperature sintering process: raise the temperature to 400°C at a rate of 2°C / min and hold for 2 hours; then continue to raise the temperature to 1100°C and hold for 6 hours to obtain preliminary modified refractory aggregate. Step 4: Dissolve the KH550 and KH560 compound in 2-5 times its mass of anhydrous ethanol to obtain a coupling agent solution. Then, add the coupling agent solution to the preliminarily modified refractory aggregate for surface treatment. Based on 100 parts of the total mass of the refractory aggregate, the amount of the compound added is 1.5-2 parts. First, stir at 200 r / min for 10 min, then stir at room temperature for 30 min. Then, centrifuge at 4000 r / min for 10 min, discard the supernatant, and remove the residual ethanol and water by vacuum distillation at 50℃ and -0.08 MPa to obtain the surface-treated refractory aggregate. Step 5: Place the surface-treated refractory aggregate in a ball mill and grind it with alumina balls as the grinding medium. The ball-to-material ratio is 3-5:1, the grinding speed is 200-300 r / min, and after grinding for 2-4 hours, pass it through a 200-mesh sieve to obtain the modified refractory aggregate. (II) Preparation of alcohol-based low-zirconium coatings: Step 1: Mix the solvent, organic binder, suspending agent and fumed silica, and stir at 300-500 r / min for 15-20 min to obtain the coating base liquid; Step 2: Add the modified refractory aggregate obtained in step (1) to the coating base liquid and stir at a speed of 600-800 r / min for 30-40 min to obtain the alcohol-based low zirconium coating.

[0014] Beneficial effects of this invention: 1. Achieved a low-zirconium upgrade for alcohol-based casting coatings. Zircon powder accounts for only 20%-40% of the total mass of modified refractory aggregates, which is more than 50% lower than that of traditional high-zirconium coatings (zircon powder content is usually ≥80%), thus reducing the consumption of scarce zirconium resources and the cost of coating production.

[0015] 2. The performance shortcomings caused by low zirconification are compensated by interfacial modification of zircon powder using a coated aluminum source. Aluminum sec-butoxide or aluminum acetylacetonate is used as the coated aluminum source, forming a uniform active alumina coating layer on the zircon powder surface after sintering. Under high-temperature casting conditions, this structure promotes the efficient in-situ formation of the mullite phase, thereby improving the high-temperature structural strength and refractory properties of the coating.

[0016] 3. A strong interfacial bond between inorganic aggregates and organic binders was achieved. Through coating modification and synergistic treatment with KH550 / KH560 bifunctional silane coupling agents, a stable organic-inorganic transition interface was constructed on the surface of the refractory aggregates, improving the wettability and dispersibility of the aggregates, enhancing the bonding strength between the aggregates and the organic binders, and improving the suspension stability, adhesion, and crack resistance of the coating.

[0017] 4. The coating's components are rationally combined, resulting in excellent overall performance. The high-alumina powder and zircon powder form a reasonable particle size distribution, effectively improving coating density. The optimized combination of organic binders, suspending agents, and fumed silica ensures good thixotropic properties, coatability, and storage stability. The coating dries quickly after application and exhibits low gas evolution at high temperatures.

[0018] 5. The preparation method is simple and convenient to operate, the parameters of each step are clear and controllable, the modification effect is stable, and the prepared coating has good performance consistency. It has good industrial application prospects in the casting production of high-end castings. Attached Figure Description

[0019] Figure 1 X-ray diffraction (XRD) patterns of different coating systems after calcination at 1500℃ are shown. Figure 1 (a) is the XRD pattern of pure zircon powder-based coating after calcination; Figure 1 (b) are the XRD patterns of zircon powder + high alumina powder coating after calcination and coated aluminum source modified refractory aggregate after calcination.

[0020] Figure 2 SEM and EDS spectra of coatings prepared from pure zircon powder after calcination. Figure 2 (a) is a SEM image; Figure 2 (b) is a surface distribution diagram of element O; Figure 2 (c) is a surface distribution diagram of Al element; Figure 2 (d) is the surface distribution diagram of Si elements; Figure 2 (e) is a surface distribution diagram of Zr elements; Figure 2 (f) is the EDS energy spectrum.

[0021] Figure 3 SEM and EDS spectra of coatings prepared from zircon powder and high-alumina powder after calcination. Figure 3 (a) is a SEM image; Figure 3 (b) is a surface distribution diagram of element O; Figure 3 (c) is a surface distribution diagram of Al element; Figure 3 (d) is the surface distribution diagram of Si elements; Figure 3 (e) is a surface distribution diagram of Zr elements; Figure 3 (f) is the EDS energy spectrum.

[0022] Figure 4 The images show the SEM and EDS spectra of the coated aluminum-modified refractory aggregate after calcination. Figure 4 (a) is a SEM image; Figure 4 (b) is a surface distribution diagram of element O; Figure 4 (c) is a surface distribution diagram of Al element; Figure 4 (d) is the surface distribution diagram of Si elements; Figure 4 (e) is a surface distribution diagram of Zr elements; Figure 4 (f) is the EDS energy spectrum. Detailed Implementation

[0023] The invention will be described in detail below through experimental examples. To verify the technical effects of the invention, pure zircon powder-based coatings and zircon powder + high-alumina powder physical mixed coatings were established as comparative systems. Each coating was applied to the surface of the sample, dried, and then placed in a muffle furnace and calcined at 1500°C, followed by natural cooling to simulate the high-temperature environment experienced by the coating during the casting process. The cooled samples were characterized by X-ray diffraction (XRD) phase analysis, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) for microstructure and elemental distribution.

[0024] Experimental Example 1 (a) Preparation of modified refractory aggregates: Step 1: Take 55 parts by weight of white corundum powder with a particle size of 200-400 mesh and 35 parts by weight of zircon powder with a particle size of 200-325 mesh, and pre-treat them in a 120℃ forced-air drying oven for 2 hours; then sieve them through a 200-mesh standard sieve and use them together as refractory aggregate.

[0025] Step 2: Weigh 10 parts by weight of aluminum sec-butoxide as the coating aluminum source, mix it with ethanol at a mass ratio of 1:4, and stir at 300 r / min for 10 min to dissolve it; then mix the solution with the refractory aggregate treated in Step 1, stir at 600 r / min for 25 min, and then dry it in an 80℃ oven for 4 h to obtain the material to be sintered.

[0026] Step 3: Grind the dried material into a uniform powder and perform a two-step high-temperature sintering process: raise the temperature to 400℃ at a rate of 2℃ / min and hold for 2 hours; then continue to raise the temperature to 1100℃ and hold for 6 hours. After cooling, the preliminary modified refractory aggregate is obtained.

[0027] Step 4: Weigh 1.8 parts by weight of a 1:1 KH550 and KH560 compound silane coupling agent, dissolve it in 3.6 parts by weight of anhydrous ethanol to prepare a coupling agent solution, and add it to the above 100 parts by weight of the preliminarily modified refractory aggregate. Stir at 200 r / min for 10 min, then stir at room temperature for 30 min; then centrifuge the material at 4000 r / min for 10 min, discard the supernatant and recover the aggregate; transfer the aggregate to a rotary vacuum distillation apparatus, and remove residual ethanol and water under vacuum conditions of 50℃ and -0.08 MPa.

[0028] Step 5: Put the aggregate processed in Step 4 into a ball mill, use alumina balls as the grinding medium, the ball-to-material ratio is 4:1, grind at 250 r / min for 3 hours, and then pass through a 200 mesh sieve to obtain the modified refractory aggregate.

[0029] (II) Preparation of alcohol-based low-zirconium coatings: Step 1: Add 13 parts by weight of anhydrous ethanol, 2 parts by weight of phenolic resin, 4 parts by weight of organobentonite, and 1 part by weight of fumed silica to a mixing tank. Stir at 400 r / min at room temperature for 18 min until the mixture is homogeneous to obtain the coating base liquid.

[0030] Step 2: Slowly add 80 parts by weight of the modified refractory aggregate prepared above into the coating base liquid, increase the stirring speed to 700 r / min, and continue stirring for 35 min to obtain alcohol-based low zirconium coating.

[0031] Phase and microstructure analysis The coating sample prepared in this experimental example was calcined at 1500℃, and the cooled sample was characterized.

[0032] XRD analysis results are as follows: Figure 1 As shown in (b). For Figure 1Phase analysis of the spectrum in (b) identified the main phases as corundum, zircon, quartz, and mullite, with corresponding standard PDF cards labeled for each. Clear and significant characteristic diffraction peaks of mullite (3Al₂O₃·2SiO₂) appeared at the corresponding diffraction angles in the spectrum. Semi-quantitative analysis indicated that the mullite phase content was approximately 37.8%. Simultaneously, the characteristic peak intensity of the zircon (ZrSiO₄) phase decreased relatively. This indicates that at high temperatures, the active alumina coating on the zircon powder surface can undergo an efficient in-situ reaction with the silicon-containing components released from the zircon powder decomposition, generating a large amount of the target product, the mullite phase.

[0033] SEM and EDS analysis results are as follows: Figure 4 (a) to Figure 4 As shown in (f). By Figure 4 (a) It can be seen that after calcination at 1500℃, the coating prepared from coated aluminum-modified refractory aggregate exhibits a relatively dense overall structure, with particle boundaries becoming more continuous and blurred, and pores and gaps significantly reduced, forming a large-area continuous phase. Figure 4 (b) It can be seen that element O is continuously distributed within the observation area; from Figure 4 (c) It can be seen that the Al element is relatively uniformly distributed, indicating that the coated aluminum source formed a relatively uniform aluminum-containing phase in the aggregate system after sintering. Figure 4 (d) It can be seen that the Si element has a good correspondence with the matrix region; from Figure 4 (e) It can be seen that the Zr element still maintains a relatively uniform distribution and is coupled with the distribution areas of Si and O elements. Figure 4 (f) The EDS spectrum shows that the sample mainly contains elements such as O, Al, Si and Zr, which further proves that the coated aluminum source has successfully participated in the interfacial reaction and promoted the formation of a dense bond structure between zircon powder and high alumina powder.

[0034] The performance of the coating in this experiment was tested, and the results were: refractoriness 1770℃, suspension rate 98% after 24 hours, and abrasion amount 19mg.

[0035] Experiment Example 2 (a) Preparation of modified refractory aggregates: Step 1: Take 50 parts by weight of white corundum powder with a particle size of 200-400 mesh and perform the same pretreatment as in Step 1 of Experimental Example 1; take 30 parts by weight of zircon powder with a particle size of 200-325 mesh and perform the same sieving treatment as in Step 1 of Experimental Example 1, and use them together as refractory aggregate.

[0036] Step 2: Weigh 10 parts by weight of aluminum sec-butoxide, dissolve it, mix it with the refractory aggregate, and dry it using the same method as in Step 2 of Experimental Example 1.

[0037] Steps 3 to 5: Using the same process conditions as steps 3 to 5 in Experimental Example 1, sintering, surface treatment, ball milling and sieving are carried out to obtain modified refractory aggregate.

[0038] (II) Preparation of alcohol-based low-zirconium coatings: The proportions and preparation processes of each group were exactly the same as those in step (II) of Experimental Example 1, and alcohol-based low zirconium coatings were obtained.

[0039] The coating in this experiment was characterized after calcination at 1500℃. The XRD patterns, SEM, and EDS analysis results are presented as follows: Figure 1 (b) Figure 4 Consistent and regular changes were observed, resulting in the formation of a significant amount of mullite phase, a dense microstructure, and uniform elemental distribution. Performance test results were: refractoriness 1700℃, 24-hour suspension rate 98%, and abrasion amount 22mg.

[0040] Experimental Example 3 (a) Preparation of modified refractory aggregates: Step 1: The composition and pretreatment method of the refractory aggregate are exactly the same as Step 1 of Experimental Example 1, that is, 55 parts by weight of white corundum powder and 35 parts by weight of zircon powder are taken for pretreatment.

[0041] Step 2: Weigh 10 parts by weight of aluminum acetylacetonate as the coating aluminum source, mix it with ethanol at a mass ratio of 1:5, and stir at 400 r / min for 10 min until completely dissolved; then mix the solution with the refractory aggregate treated in Step 1, stir at 700 r / min for 25 min, and then place it in an 80℃ oven for drying.

[0042] Steps 3 to 5 are performed under the same process conditions as in Steps 3 to 5 of Experimental Example 1, including sintering, surface treatment, ball milling, and sieving.

[0043] (II) Preparation of alcohol-based low-zirconium coatings: The proportions of each component are as follows: 80 parts by weight of the modified refractory aggregate, 2 parts by weight of polyvinyl butyral, 4 parts by weight of lithium-based bentonite, 1 part by weight of fumed silica, and 13 parts by weight of isopropanol. The preparation process is the same as step (ii) of Experimental Example 1, that is, the base liquid is first mixed by stirring at a low speed of 400 r / min for 18 min, and then the aggregate is added and stirred at a high speed of 700 r / min for 35 min to obtain the alcohol-based low zirconium coating.

[0044] The coating in this experiment was characterized after calcination at 1500℃. The XRD patterns, SEM, and EDS analysis results are presented as follows: Figure 1 (b) Figure 4 Consistent and regular changes. Performance test results: fire resistance 1760℃, 24h suspension rate 97%, abrasion amount 21mg.

[0045] Experiment Example 4 (a) Preparation of modified refractory aggregates: Step 1: Take 60 parts by weight of white corundum powder with a particle size of 200-400 mesh and perform the same pretreatment as in Step 1 of Experimental Example 1; take 35 parts by weight of zircon powder with a particle size of 200-325 mesh and perform the same sieving treatment as in Step 1 of Experimental Example 1, and use them together as refractory aggregates.

[0046] Step 2: Weigh 5 parts by weight of aluminum sec-butoxide, dissolve it, mix it with refractory aggregate and dry it using the same method as in Step 2 of Experimental Example 1.

[0047] Steps 3 to 5 are performed under the same process conditions as in Steps 3 to 5 of Experimental Example 1, including sintering, surface treatment, ball milling, and sieving.

[0048] (II) Preparation of alcohol-based low-zirconium coatings: The proportions of each component are as follows: 80 parts by weight of the modified refractory aggregate, 2 parts by weight of rosin resin, 4 parts by weight of lithium-based bentonite, 1 part by weight of fumed silica, and 13 parts by weight of anhydrous ethanol. The preparation process is the same as step (II) of Experimental Example 1, and an alcohol-based low-zirconium coating is obtained.

[0049] The coating in this experiment was characterized after calcination at 1500℃. The XRD patterns, SEM, and EDS analysis results are presented as follows: Figure 1 (b) Figure 4 Consistent and regular changes. Performance test results: fire resistance 1730℃, 24h suspension rate 96%, abrasion amount 28mg.

[0050] Experimental Example 5 (a) Preparation of modified refractory aggregates: Step 1: Take 60 parts by weight of white corundum powder with a particle size of 200-400 mesh and perform the same pretreatment as in Step 1 of Experimental Example 1; take 30 parts by weight of zircon powder with a particle size of 200-325 mesh and perform the same sieving treatment as in Step 1 of Experimental Example 1, and use them together as refractory aggregate.

[0051] Step 2: Weigh 10 parts by weight of aluminum sec-butoxide, dissolve it, mix it with the refractory aggregate, and dry it using the same method as in Step 2 of Experimental Example 1.

[0052] Steps 3 to 5 are performed under the same process conditions as in Steps 3 to 5 of Experimental Example 1, including sintering, surface treatment, ball milling, and sieving.

[0053] (II) Preparation of alcohol-based low-zirconium coatings: The proportions and preparation processes of each group are the same as those in step (II) of Experimental Example 1, and alcohol-based low zirconium coatings are obtained.

[0054] The coating in this experiment was characterized after calcination at 1500℃. The XRD patterns, SEM, and EDS analysis results are presented as follows: Figure 1 (b) Figure 4 The material exhibits a consistent and regular pattern of change, forming a distinct mullite phase with a relatively dense microstructure and a fairly uniform distribution of Al, O, Si, and Zr elements. Performance test results are as follows: refractoriness 1730℃, 24-hour suspension rate 98%, and abrasion amount 21 mg.

[0055] Experimental Example 6 (a) Preparation of modified refractory aggregates: Step 1: Take 50 parts by weight of white corundum powder with a particle size of 200-400 mesh and perform the same pretreatment as in Step 1 of Experimental Example 1; take 40 parts by weight of zircon powder with a particle size of 200-325 mesh and perform the same sieving treatment as in Step 1 of Experimental Example 1, and use them together as refractory aggregates.

[0056] Step 2: Weigh 10 parts by weight of aluminum sec-butoxide, dissolve it, mix it with the refractory aggregate, and dry it using the same method as in Step 2 of Experimental Example 1.

[0057] Steps 3 to 5 are performed under the same process conditions as in Steps 3 to 5 of Experimental Example 1, including sintering, surface treatment, ball milling, and sieving.

[0058] (II) Preparation of alcohol-based low-zirconium coatings: The proportions and preparation processes of each group are the same as those in step (II) of Experimental Example 1, and alcohol-based low zirconium coatings are obtained.

[0059] The coating in this experiment was characterized after calcination at 1500℃. The XRD patterns, SEM, and EDS analysis results are presented as follows: Figure 1 (b) Figure 4 Consistent and regular changes were observed, resulting in the formation of a distinct mullite phase, a dense coating structure, and uniform element distribution. Performance test results were: refractoriness 1780℃, 24-hour suspension rate 97%, and abrasion amount 22mg.

[0060] Comparative Example 1 A coating using pure zircon powder as refractory aggregate was prepared. Except that all the refractory aggregate was zircon powder, the other formulations (2 parts by weight of phenolic resin, 4 parts by weight of organic bentonite, 1 part by weight of fumed silica, and 13 parts by weight of anhydrous ethanol) and preparation process were the same as steps (II) of Experimental Example 1.

[0061] The coating sample was characterized after calcination at 1500℃. The XRD analysis results are as follows: Figure 1 As shown in Figure a, the spectrum only shows the characteristic diffraction peaks of zircon (ZrSiO4), and no characteristic peaks of the mullite phase are present. SEM and EDS analysis results are as follows: Figure 2(a) to Figure 2 As shown in (f). By Figure 2 (a) It can be seen that after calcination, the pure zircon powder-based coating mainly consists of loosely packed, angular particles with clear particle boundaries and numerous pores, failing to form a continuous, dense binder phase. Figure 2 (b) It can be seen that the O element is mainly distributed along the zircon grains; from Figure 2 (c) It can be seen that the Al element signal is extremely weak, indicating that there is essentially no external aluminum source participating in the reaction in this system. Figure 2 (d) and Figure 2 (e) It can be seen that the distribution areas of Si and Zr elements have a high degree of correspondence, indicating that the system mainly retains the zircon phase structure after calcination. Figure 2 (f) The EDS spectrum shows that the main elements in the sample are O, Si and Zr, and the content of Al is very low, indicating that it is difficult for the pure zircon powder system to generate an effective mullite bonding phase under calcination conditions of 1500℃.

[0062] The performance of the coating in this experiment was tested, and the results were: refractoriness 1770℃, suspension rate 91% after 24 hours, and abrasion amount 36mg.

[0063] Comparative Example 2 A coating was prepared using a traditional physical mixing method. 60 parts by weight of white corundum powder and 40 parts by weight of zircon powder were directly dry-mixed without any coating or coupling treatment. This aggregate mixture was used as a raw material to prepare a coating using the exact same formulation and process as in step (ii) of Experimental Example 1.

[0064] The coating sample was characterized after calcination at 1500℃. The XRD analysis results are as follows: Figure 1 As shown in (b), besides the characteristic peaks of zircon and corundum phases, only weak mullite diffraction peaks appear in the spectrum, with a content of approximately 10.1%. SEM and EDS analysis results are as follows: Figure 3 (a) to Figure 3 As shown in (f). By Figure 3 (a) It can be seen that the physical mixture of zircon powder and high-alumina powder, after calcination, exhibits irregular blocky accumulation, with large gaps between particles and insufficient interfacial bonding. Figure 3 (b) It can be seen that the O element is distributed within the particle region, but the overall continuity is insufficient; from Figure 3 (c) It can be seen that Al element exhibits obvious local enrichment, indicating that the high-alumina powder mainly exists in the form of localized particles. Figure 3 (d) and Figure 3 (e) It can be seen that the distribution areas of Si and Zr elements do not fully overlap with those of Al, indicating that the mixing between zircon powder and high-alumina powder is mainly mechanical, with a limited interfacial contact area. Figure 3(f) The EDS spectrum shows that the sample contains elements such as O, Al, Si, and Zr. However, due to insufficient coupling of the distribution of each element, only a small amount of mullite phase can be generated at high temperature, making it difficult to form a continuous and dense reinforced structure.

[0065] The performance of the coating in this experiment was tested, and the results were: refractoriness 1690℃, suspension rate 92% after 24 hours, and abrasion amount 42mg.

[0066] Matters not covered in this invention are common knowledge.

[0067] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An alcohol-based low-zirconium coating, characterized in that, By mass fraction, it consists of the following components: Modified refractory aggregate: 75%-85%; Organic binder: 1%-3%; Suspension agent: 3%-5%; Additives: 1%-3%; Solvent: 5%-15%; The modified refractory aggregate is prepared from raw materials including refractory aggregate, coated aluminum source and silane coupling agent; The refractory aggregate is composed of high alumina powder and zircon powder; and the mass ratio of zircon powder to high alumina powder is 30-40:50-60. Based on a total mass of 100 parts of the refractory aggregate, the amount of the coated aluminum source added is 5-15 parts, and the amount of the silane coupling agent added is 1.5-2.5 parts; The silane coupling agent is a compound of KH550 and KH560, with a compounding ratio of 1:1; The coated aluminum source is aluminum sec-butoxide or aluminum acetylacetone.

2. The alcohol-based low-zirconium coating according to claim 1, characterized in that, The organic binder is one or more of phenolic resin, rosin resin, polyvinyl butyral, and acrylic resin.

3. The alcohol-based low-zirconium coating according to claim 1, characterized in that, The suspending agent is one or more of organic bentonite and lithium-based bentonite.

4. The alcohol-based low-zirconium coating according to claim 1, characterized in that, The additive is fumed silica.

5. The alcohol-based low-zirconium coating according to claim 1, characterized in that, The solvent is one or more of anhydrous ethanol, methanol, and isopropanol.

6. The alcohol-based low-zirconium coating according to claim 1, characterized in that, The high-alumina powder is one or more of white corundum powder and bauxite powder, with a particle size of 200-400 mesh; the zircon powder has a particle size of 200-325 mesh.

7. The alcohol-based low-zirconium coating according to claim 1, characterized in that, The coated aluminum source is aluminum sec-butoxide, and its addition amount is 5 parts, 10 parts or 15 parts.

8. The alcohol-based low-zirconium coating according to claim 1, characterized in that, The coated aluminum source is aluminum acetylacetone, and its addition amount is 10 parts or 15 parts.

9. A method for preparing an alcohol-based low-zirconium coating as described in any one of claims 1-8, characterized in that, Includes the following steps: (a) Preparation of modified refractory aggregates: Step 1: Pre-treat the high-alumina powder and zircon powder respectively: Dry the high-alumina powder at 120℃ for 2 hours; pass the zircon powder through a 200-mesh sieve to obtain the pre-treated refractory aggregate; Step 2: Add a coated aluminum source to the pretreated refractory aggregate and mix evenly. Dry in an oven at 80°C for 4 hours to obtain the material to be sintered. When the coated aluminum source is aluminum sec-butoxide, first mix the aluminum sec-butoxide and ethanol at a mass ratio of 1:4, stir at 300-500 r / min for 10 minutes, and then mix with the pretreated refractory aggregate, stirring at 500-800 r / min for 20-30 minutes. When the coated aluminum source is aluminum acetylacetonate, first mix the aluminum acetylacetonate and ethanol at a mass ratio of 1:5, stir at 300-500 r / min for 10 minutes, and then mix with the pretreated refractory aggregate, stirring at 500-800 r / min for 20-30 minutes. Step 3: Grind the material to be sintered into powder and perform a two-step high-temperature sintering process: raise the temperature to 400°C at a rate of 2°C / min and hold for 2 hours; then continue to raise the temperature to 1100°C and hold for 6 hours to obtain preliminary modified refractory aggregate. Step 4: Dissolve the KH550 and KH560 compound in 2-5 times its mass of anhydrous ethanol to obtain a coupling agent solution. Then, add the coupling agent solution to the preliminarily modified refractory aggregate for surface treatment. The amount of the compound added is 1.5-2 parts per 100 parts of the total mass of the refractory aggregate. Stir at 200 r / min for 10 min, then stir at room temperature for 30 min. Centrifuge at 4000 r / min for 10 min, discard the supernatant, and remove the residual ethanol and water by vacuum distillation at 50℃ and -0.08 MPa to obtain the surface-treated refractory aggregate. Step 5: Place the surface-treated refractory aggregate in a ball mill and grind it with alumina balls as the grinding medium. The ball-to-material ratio is 3-5:1, the grinding speed is 200-300 r / min, and after grinding for 2-4 hours, pass it through a 200-mesh sieve to obtain the modified refractory aggregate. (II) Preparation of alcohol-based low-zirconium coatings: Step 1: Mix the solvent, organic binder, suspending agent and fumed silica, and stir at 300-500 r / min for 15-20 min to obtain the coating base liquid; Step 2: Add the modified refractory aggregate obtained in step (1) to the coating base liquid and stir at a speed of 600-800 r / min for 30-40 min to obtain the alcohol-based low zirconium coating.

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