Anti-corrosion ceramic sagger and preparation method thereof

Abstract

The invention provides an anti-corrosion ceramic sagger and a preparation method thereof.The anti-corrosion ceramic sagger comprises an aggregate layer and a matrix layer, and the aggregate layer is prepared from, by mass, 30-50 parts of yttrium-stabilized zirconia, 20-30 parts of silicon carbide and 15-25 parts of magnesium aluminate spinel; the matrix layer is prepared from the following raw materials in parts by mass: 40 to 50 parts of mullite micro powder, 30 to 40 parts of cordierite micro powder and 10 to 20 parts of binding agent. According to the anti-corrosion ceramic sagger and the preparation method thereof, by optimizing the raw material ratio and the preparation process, the corrosion depth is smaller than or equal to 0.19 mm after the sagger is soaked in the molten salt environment at 900 DEG C for 72 h, the service life is prolonged by 6-8 times compared with that of a traditional corundum sagger, and the anti-corrosion ceramic sagger has wide application prospects.

Description

Technical Field

[0001] This application relates to the technical field of saggers, and particularly relates to an anti-corrosion ceramic sagger and a preparation method thereof. Background Art

[0002] At present, in the actual production of synthesizing the cathode material of lithium-ion batteries, the high-temperature solid-phase synthesis method is generally adopted. The high-temperature-resistant saggers used in the synthesis process are generally cordierite, mullite, quartz-based, and corundum-based high-temperature-resistant saggers, among which cordierite and corundum are used the most. However, since the raw materials used for synthesizing the lithium-ion cathode material will decompose during the synthesis process to produce lithium oxide (Li2O) with strong penetration ability and reactivity, at high temperatures, the alkaline substance Li2O will chemically react with the acidic substances and amphoteric oxides in the sagger, so it will erode the high-temperature-resistant sagger, greatly reducing the service life of the high-temperature-resistant sagger.

[0003] For the existing sagger, after mixing various raw materials evenly, a composite material is obtained by pressing and sintering. After this sagger is eroded, there is a small amount of cathode material on the surface that is difficult to peel off. After being scrapped, it becomes industrial waste and is very likely to cause heavy metal pollution.

[0004] Currently, in the saggers used for synthesizing the cathode material of lithium-ion batteries, for high-alkaline raw materials, the saggers are corroded during multiple uses. Therefore, how to improve the corrosion resistance of the sagger, reduce heavy metal pollution, and improve the production efficiency of enterprises is an urgent problem to be solved at present. Summary of the Invention

[0005] This application is made in view of the above problems, and its purpose is to provide an anti-corrosion ceramic sagger and a preparation method thereof.

[0006] Specifically, in the first aspect of this application, an anti-corrosion ceramic sagger is provided. The anti-corrosion ceramic sagger includes an aggregate layer and a matrix layer. The aggregate layer includes the following raw materials in parts by mass: 30-50 parts of yttrium-stabilized zirconia, 20-30 parts of silicon carbide, and 15-25 parts of magnesium aluminate spinel; The matrix layer includes the following raw materials in parts by mass: 40-50 parts of mullite fine powder, 30-40 parts of cordierite fine powder, and 10-20 parts of CeO2-modified silica sol.

[0007] Further, the particle size of the yttrium-stabilized zirconia is 60-80 nm.

[0008] In the second aspect of this application, a preparation method of the anti-corrosion ceramic sagger is provided, including the following steps: S1: Ball-mill yttrium-stabilized zirconia, silicon carbide, and magnesium aluminate spinel of the aggregate respectively, and then mix them evenly to obtain a mixed aggregate; Mix matrix mullite fine powder, cordierite fine powder, binder and deionized water, ball mill, and then spray granulate to obtain spherical matrix particles; S2: Customize a graphite mold, fill the mixed aggregate and spherical matrix particles into the cavity of the graphite mold respectively, and use the isostatic pressing forming process to prepare a sagger green body; S3: Dry, sinter, heat preserve, and cool the sagger green body to obtain a sintered sagger body; S4: Spray silicon nitride on the surface of the sintered sagger body, and then perform secondary sintering to obtain a sagger.

[0009] Furthermore, in step S1, the ball milling time for yttria-stabilized zirconia, silicon carbide, and magnesium aluminate spinel is 2 - 3 h, and the rotation speed is 200 - 260 rpm.

[0010] Furthermore, in step S1, the mixing ratio of the matrix mullite fine powder, cordierite fine powder, binder and deionized water is 1.2 - 1.5:1.

[0011] Furthermore, in step S1, when mixing the matrix mullite fine powder, cordierite fine powder, binder and water and ball milling, the time is 4 - 5 h to make the slurry viscosity ≤ 200 mPa·s.

[0012] Furthermore, in step S1, the inlet temperature of the spray granulation is 280 - 320 °C, and the outlet temperature is 110 - 130 °C; and / or the particle size of the spherical matrix particles is 80 - 120 μm.

[0013] Furthermore, in step S2, the mixed aggregate and the spherical matrix particles are mixed in a ratio of 1.2 - 1.8:1, and a polyvinyl alcohol solution is added to the mixed aggregate and stirred until the moisture content of the mixed aggregate is 8 - 10%; and / or The pressure in the isostatic pressing forming process is 80 - 100 MPa, and the pressure is maintained for 5 - 10 min.

[0014] Furthermore, in step S3, the method for sintering the sagger green body is as follows: Heat up to 1000 - 1100 °C at a rate of 2 - 5 °C / min and heat preserve for 30 - 60 min; Under a protective atmosphere, continue to heat up to 1400 - 1500 °C at a rate of 2 - 5 °C / min and heat preserve for 2 - 3 h.

[0015] Furthermore, in step S4, the temperature of the secondary sintering is 800 - 850 °C, and the time is 1 - 1.5 h.

[0016] The present invention has the following beneficial effects: 1. The sagger aggregate layer of the present invention includes yttria-stabilized zirconia, which reacts with molten salt at high temperature to form a dense ZrO2 - Y2O3 layer, blocking Li+ / Na + penetrates to play an anti-corrosion role. Silicon carbide has high thermal conductivity and can buffer thermal stress. At the same time, silicon carbide preferentially oxidizes to form SiO2 glass phase in an oxidizing atmosphere, and reacts with Y in yttrium-stabilized zirconia 3+ to form a Y-Si-O composite phase, and an anti-corrosion gradient layer is formed through gradient sintering; the added magnesium aluminate spinel (MgAl2O4) has amphoteric characteristics, and its spinel structure can react with Li2O to form stable phases of LiAlO2 and MgO, forming a chemical buffer layer; The matrix layer adopts a composite system of mullite and cordierite fine powder. Their thermal expansion coefficients are similar, and close packing is achieved through particle size grading, with a porosity ≤ 15%; combined with Ce in CeO2-modified silica sol 4+ can capture free Li + to generate a CeLiO2 passivation film. At the same time, the Ce-O-Si bond formed by rare earth elements at high temperature can effectively block the diffusion of Li + diffusion.

[0017] 2. In the preparation method of the present invention, an isostatic pressing forming process (80 - 100 MPa) is adopted to form a mechanical interlocking structure between the aggregate layer and the matrix layer, and densification and the formation of an anti-corrosion layer are completed by precisely controlling the temperature during sintering; after testing, the corrosion depth of this sagger is ≤ 0.22 mm after being immersed in a molten salt environment at 900 °C for 72 h, and the service life is several times longer than that of traditional corundum saggers. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments or the prior art of the present drawings, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following described drawings are only some embodiments of the present drawings. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0019] Figure 1 It is the external view of the sagger prepared in Example 1.

[0020] The realization, functional features, and advantages of the present drawings will be further described in conjunction with the embodiments with reference to the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In order to make the purpose, technical solutions, and advantages of the present application clearer, the following will describe and explain the present application in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0022] Obviously, the following description is only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios. In addition, it can also be understood that although the efforts made in such a development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacturing, or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.

[0023] If not specifically stated, the "including" and "comprising" mentioned in the present application mean open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or only the components listed can be included or comprised.

[0024] If not specifically stated, in the present application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0025] In the first aspect of the present invention, an anti-corrosion ceramic crucible is provided. The anti-corrosion ceramic crucible includes an aggregate layer and a matrix layer. The aggregate layer includes the following raw materials in parts by mass: 30 - 50 parts of yttrium-stabilized zirconia, 20 - 30 parts of silicon carbide, and 15 - 25 parts of magnesium aluminate spinel. The matrix layer includes the following raw materials in parts by mass: 40 - 50 parts of mullite fine powder, 30 - 40 parts of cordierite fine powder, and 10 - 20 parts of CeO2-modified silica sol.

[0026] The yttrium-stabilized zirconia has a particle size of 60 - 80 nm, and is purchased from Jiaozuo Zhongcheng New Materials Co., Ltd. Its mass fraction is any value or any value range among 30 parts, 35 parts, 40 parts, 45 parts, and 50 parts. If it is less than 30 parts, the anti-corrosion performance of the crucible is insufficient. If it is higher than 50 parts, it will lead to too high cost of the crucible and may affect the overall performance of the crucible.

[0027] The silicon carbide preferably has a particle size of 1 - 5 μm, and is purchased from Shanghai Chaowei Nano Technology Co., Ltd. Its mass fraction is any value or any value range among 20 parts, 22 parts, 25 parts, 27 parts, and 30 parts. If it is less than 20 parts, the thermal conductivity of the crucible is insufficient. If it is higher than 30 parts, the brittleness of the crucible may increase.

[0028] The particle size of the magnesium aluminate spinel is preferably 5-10 μm, purchased from Gongyi Jufeng Refractory Materials Co., Ltd., and its mass fraction is any value or any value range among 15 parts, 18 parts, 20 parts, 22 parts, and 25 parts. Less than 15 parts will cause a decrease in the corrosion resistance of the sagger, and more than 25 parts may affect the sintering performance of the sagger.

[0029] The particle size of the mullite fine powder is 200 mesh, and its mass fraction is any value or any value range among 40 parts, 42 parts, 45 parts, 48 parts, and 50 parts. Less than 40 parts will result in insufficient strength of the matrix layer of the sagger, and more than 50 parts may cause a decrease in the densification of the sagger, affecting the corrosion resistance. The particle size of the cordierite fine powder is 200 mesh, and its mass fraction is any value or any value range among 30 parts, 32 parts, 35 parts, 38 parts, and 40 parts. Its thermal expansion coefficient is similar to that of the mullite fine powder, which helps to achieve close packing and reduce the porosity. The binder is selected as CeO2-modified silica sol, and its mass fraction is selected in the range of 10-20 parts, which can not only ensure the forming performance of the sagger but also improve the corrosion resistance of the sagger.

[0030] The preparation method of the CeO2-modified silica sol is as follows: Place the silica sol in a reaction vessel, adjust the pH to 9-11, add the Ce(NO3)3·6H2O solution, and stir and react at 60-80 °C for 2-4 h to obtain the CeO2-modified silica sol. Among them, the addition amount of Ce(NO3)3·6H2O is 2-5% of the mass of the silica sol. Through this modification method, Ce 4+ can be uniformly dispersed in the silica sol.

[0031] The second aspect of the present application provides a preparation method of the corrosion-resistant ceramic sagger, including the following steps: S1: Ball-mill the aggregate yttria-stabilized zirconia, silicon carbide, and magnesium aluminate spinel respectively, and then mix them evenly to obtain a mixed aggregate; Mix the matrix mullite fine powder, cordierite fine powder, binder, and deionized water, ball-mill, and then spray granulate to obtain spherical matrix particles; S2: Customize a graphite mold, fill the mixed aggregate and spherical matrix particles into the cavity of the graphite mold respectively, and use an isostatic pressing forming process to prepare a sagger blank; S3: Dry, sinter, heat-insulate, and cool the sagger blank to obtain a sagger sintered body; S4: Spray silicon nitride on the surface of the sagger sintered body, and then perform secondary sintering to obtain the sagger.

[0032] In this embodiment, in step S1, the ball-milling time of the yttria-stabilized zirconia, silicon carbide, and magnesium aluminate spinel is 2-3 h, the rotation speed is 200-260 rpm, and they are ball-milled to 200 mesh respectively.

[0033] In this embodiment, the mixing ratio of the matrix mullite fine powder, cordierite fine powder, binder and deionized water in step S1 is 1.2 - 1.5:1.

[0034] In this embodiment, in step S1, the matrix mullite fine powder, cordierite fine powder, binder and water are mixed, and the ball milling time is 4 - 5 h to make the slurry viscosity ≤ 200 mPa·s. The purpose is to make the slurry evenly mixed, ensure the uniform distribution of the components of the matrix particles, without agglomeration phenomenon, which is beneficial to the subsequent spray granulation process.

[0035] In this embodiment, the inlet temperature of the spray granulation in step S1 is 280 - 320 °C, and the outlet temperature is 110 - 130 °C; and / or the particle size of the spherical matrix particles is 80 - 120 μm. By controlling the inlet temperature and the outlet temperature, it can ensure that the morphology of the spherical matrix particles is regular, the particle size distribution is uniform, and it has a certain strength, which is beneficial to the subsequent forming and sintering processes; the particle size of the spherical matrix particles is 80 - 120 μm, and the spherical matrix particles in this particle size range have good filling and fluidity, which is beneficial to the densification of the sagger blank and the improvement of the corrosion resistance.

[0036] In this embodiment, in step S2, the mixed aggregate and the spherical matrix particles are mixed in a ratio of 1.2 - 1.8:1, 3 - 5 parts of polyvinyl alcohol solution are added to the mixed aggregate, and stirred until the water content of the mixed aggregate is 8 - 10%; the pressure in the isostatic pressing process is 80 - 100 MPa, and the pressure is maintained for 5 - 10 min. In the present invention, by customizing a graphite mold with an inner and outer two-layer cavity, the inner wall is sprayed with a BN coating to prevent sticking, and the mixed aggregate and the spherical matrix particles are respectively filled into the graphite mold. The thickness of the mixed aggregate is 5 - 8 mm, and the thickness of the spherical matrix particles is 8 - 12 mm. The polyvinyl alcohol solution is used as a binder, and the addition amount is 3 - 5 parts, which can effectively improve the forming performance of the mixture and make the sagger blank more dense. The pressure in the isostatic pressing process is 80 - 100 MPa, and the pressure is maintained for 5 - 10 min, which can form a mechanical interlocking structure between the mixed aggregate and the spherical matrix particles, further improving the strength and corrosion resistance of the sagger.

[0037] In this embodiment, the method of drying the sagger green body at room temperature and then sintering it in step S3 is as follows: heating it at a rate of 2 - 5 °C / min to 1000 - 1100 °C and holding for 30 - 60 min. During this process, the silica sol dehydrates, forming a preliminary combination of the Ce - Si - O gel network to inhibit interlayer peeling; under a protective atmosphere, continue to heat at a rate of 2 - 5 °C / min to 1400 - 1500 °C. During this process, yttria - stabilized zirconia reacts with silicon carbide to form a ZrC - ZrSiO4 gradient layer (1 - 2 μm), and an outer corrosion - resistant barrier is formed. Under a protective atmosphere, hold at 1400 - 1500 °C for 2 - 3 h, and MgAl2O4 pre - reacts with the molten salt to generate a LiAlO2 - MgO composite phase to seal the pores, so as to reduce the porosity. Finally, cool with the furnace, and control the cooling rate ≤ 5 °C / min (the cooling can be accelerated below 800 °C) to avoid cracking due to mullite phase transformation.

[0038] In this embodiment, in step S4, a silicon nitride coating is sprayed on the surface of the sagger sintered body; the temperature of the secondary sintering is 800 - 850 °C and the time is 1 - 1.5 h to form a surface silicon nitride sealing layer with a thickness of 0.5 - 1 μm. The silicon nitride coating is a slurry prepared from silicon nitride powder, high - purity water, and silica sol in a ratio of 1.2 - 1.3:1:2.8 - 3.3. The particle size of the silicon nitride powder is 10 - 30 μm, and the colloidal particles of the silica sol are 10 - 20 nm; this sealing layer not only enhances the surface hardness and wear resistance of the sagger, but also further blocks the penetration of the molten salt, improving the overall corrosion - resistant performance.

[0039] Example 1 An anti - corrosion ceramic sagger, the anti - corrosion ceramic sagger includes an aggregate layer and a matrix layer. The aggregate layer includes the following raw materials in parts by mass: 38 parts of yttria - stabilized zirconia, 23 parts of silicon carbide, and 20 parts of magnesium aluminate spinel; The matrix layer includes the following raw materials in parts by mass: 44 parts of mullite fine powder, 36 parts of cordierite fine powder, and 13 parts of CeO2 - modified silica sol; The preparation method of the anti - corrosion ceramic sagger includes the following steps: S1: Ball - mill yttria - stabilized zirconia, silicon carbide, and magnesium aluminate spinel of the aggregate respectively for 3 h at a rotation speed of 200 rpm, and then mix them evenly to obtain a mixed aggregate; Mix the mullite fine powder, cordierite fine powder, binder of the matrix with deionized water in a ratio of 1.5:1, ball - mill for 5 h to make the viscosity of the slurry ≤ 200 mPa·s, and then spray - granulate to obtain spherical matrix particles; the inlet temperature of the spray - granulation is 300 °C, the outlet temperature is 120 °C; the particle size of the spherical matrix particles is 100 μm; S2: Customize a graphite mold. Add 3 parts of polyvinyl alcohol solution to the mixed aggregate. After mixing evenly, fill it into the graphite mold. Then fill the spherical matrix particles into the graphite mold. Use the isostatic pressing forming process to hold the pressure at 80 MPa for 8 minutes to prepare a sagger blank; S3: Dry the sagger blank at room temperature. After drying, heat it up to 1050 °C at a rate of 3 °C / min and hold for 60 minutes. Under a nitrogen atmosphere, continue to heat it up to 1450 °C at a rate of 3 °C / min and hold for 3 hours; finally, cool it down with the furnace to obtain a sintered sagger body; S4: Spray silicon nitride on the surface of the sintered sagger body, and then conduct secondary sintering at a temperature of 800 °C for 1 hour to obtain a sagger. See the appearance diagram of the sagger in Figure 1 。

[0040] Example 2 This example is basically the same as Example 1, except that there are 45 parts of yttrium-stabilized zirconia.

[0041] Example 3 This example is basically the same as Example 1, except that there are 28 parts of silicon carbide.

[0042] Example 4 This example is basically the same as Example 1, except that there are 48 parts of mullite fine powder and 32 parts of cordierite fine powder.

[0043] Example 5 This example is basically the same as Example 1, except that there are 17 parts of CeO2-modified silica sol.

[0044] Example 6 This example is basically the same as Example 1, except that in step S2, the matrix mullite fine powder, cordierite fine powder, binder and deionized water are mixed in a ratio of 1.2:1 and ball-milled for 4 hours.

[0045] Example 7 This example is basically the same as Example 1, except that in step S4, after drying, heat it up to 1050 °C at a rate of 5 °C / min and hold for 40 minutes. Under a nitrogen atmosphere, continue to heat it up to 1500 °C at a rate of 5 °C / min and hold for 2 hours.

[0046] Example 8 This example is basically the same as Example 1, except that the secondary sintering temperature is 850 °C and the time is 1.5 hours.

[0047] Comparative Example 1 This comparative example is basically the same as Example 1, except that the aggregate layer does not contain yttrium-stabilized zirconia.

[0048] Comparative Example 2 This comparative example is basically the same as Example 1, except that zirconia is used instead of yttria-stabilized zirconia.

[0049] Comparative Example 3 This comparative example is basically the same as Example 1, except that silica sol is used instead of CeO2-modified silica sol.

[0050] Comparative Example 4 This comparative example is basically the same as Example 1, except that in step S2, spray granulation is not carried out.

[0051] Comparative Example 5 This comparative example is basically the same as Example 1, except that in step S3, instead of the isostatic pressing forming process, a conventional method is used for pressing and forming.

[0052] Comparative Example 6 This comparative example is basically the same as Example 1, except that in step S4, stepped heating is not used, and it is directly heated to 1450 °C at a rate of 5 °C / min and held for 3 h.

[0053] Comparative Example 7 This comparative example is basically the same as Example 1, except that in step S5, the silicon nitride coating is not sprayed on the sagger sintered body.

[0054] Experimental cases Using Li2CO3-Na2CO3-K2CO3 as the mixed molten salt, with the molar ratio of Li2CO3, Na2CO3, and K2CO3 being 4:3:3, the saggers prepared in Examples 1-8 and Comparative Examples 1-7 were statically immersed in the mixed molten salt at 900 °C, and the test periods were 24 h, 48 h, and 72 h. The corrosion depths of each sagger were detected, and the results are shown in Table 1.

[0055]

[0056] As can be seen from the above table, the saggers prepared in Examples 1-8 of the present invention showed excellent performance in the corrosion resistance test. Especially in the mixed molten salt environment, after 48-hour and 72-hour static immersion tests, the corrosion depth of the saggers in Examples 1-8 was significantly lower than that of the saggers in Comparative Examples 1-6. The reason may be that the present invention uses yttria-stabilized zirconia, silicon carbide and magnesium aluminate spinel as the main components of the aggregate layer. These materials not only have high corrosion resistance, but also can form stable compounds during the sintering process, further enhancing the corrosion resistance barrier of the saggers. At the same time, by optimizing the particle size and ratio of these raw materials, the balance among the thermal conductivity, strength and sintering performance of the saggers was ensured. The selection of mullite fine powder and cordierite fine powder in the matrix layer, as well as the application of CeO2-modified silica sol as a binder, further improved the overall performance of the saggers. The optimization of the particle size and ratio of mullite fine powder and cordierite fine powder helped to achieve close packing and reduce the porosity, thereby improving the densification and corrosion resistance of the saggers. The preparation and application of CeO2-modified silica sol not only enhanced the forming performance of the saggers, but also improved the corrosion resistance of the saggers through the modification effect.

[0057] During the preparation process, through the precise control of key steps such as customizing graphite molds, isostatic pressing, stepwise heating sintering and spraying silicon nitride coatings, the optimization of the microstructure and performance of the saggers was ensured. Especially the application of the isostatic pressing process enabled the formation of a mechanical interlocking structure between the mixed aggregate and the spherical matrix particles, further improving the strength and corrosion resistance of the saggers. The implementation of steps such as stepwise heating sintering and spraying silicon nitride coatings helped to form a dense corrosion resistance barrier and a surface sealing layer, further enhancing the corrosion resistance of the saggers.

[0058] It can be seen from Comparative Examples 1-7 that in Comparative Example 1, when the aggregate layer did not contain yttria-stabilized zirconia, the corrosion resistance of the sagger decreased significantly. The reason may be the lack of the high corrosion resistance of yttria-stabilized zirconia. Yttria-stabilized zirconia reacts with molten salt at high temperature to form a dense ZrO2-Y2O3 layer, blocking Li + / Na +Penetration: When yttria-stabilized zirconia is lacking, the anti-corrosion barrier of the sagger cannot be effectively formed, resulting in a significant increase in the corrosion depth. In Comparative Example 2, ordinary zirconia was used instead of yttria-stabilized zirconia. Although zirconia also has certain corrosion resistance, its stability is not as good as that of yttria-stabilized zirconia. Therefore, the anti-corrosion performance of the sagger also decreases. In Comparative Example 3, unmodified silica sol was used as the binder, lacking the modification effect of CeO2, resulting in a decline in both the forming performance and anti-corrosion performance of the sagger. In Comparative Example 4, spray granulation was not carried out, making the morphology and particle size distribution of the matrix particles uneven, affecting the densification and anti-corrosion performance of the sagger. In Comparative Example 5, conventional pressing was used instead of isostatic pressing to form the sagger, and a mechanical interlocking structure could not be formed, resulting in a decrease in the strength and anti-corrosion performance of the sagger. In Comparative Example 6, stepwise heating was not adopted, and direct high-temperature sintering might lead to uneven internal stress in the sagger, generating cracks and affecting the anti-corrosion performance. In Comparative Example 7, the sagger sintered body was not sprayed with a silicon nitride coating, lacking the surface sealing layer, resulting in a decrease in the anti-corrosion performance of the sagger. In summary, the anti-corrosion ceramic sagger and its preparation method of the present invention achieve excellent anti-corrosion performance by optimizing the raw material ratio, preparation process, and microstructure, and have broad application prospects.

[0059] The reason why the compressive strength of Examples 1-8 is higher than that of Comparative Examples 1-7 is as follows: First, the saggers in the examples adopt specific raw material ratios. For example, yttria-stabilized zirconia, silicon carbide, and magnesium aluminate spinel are used as the main components of the aggregate layer. These materials not only have high corrosion resistance but also can form stable compounds during the sintering process, enhancing the structural strength of the sagger. At the same time, the optimized ratio of mullite fine powder and cordierite fine powder in the matrix layer, as well as the application of CeO2-modified silica sol, further improve the overall strength and densification of the sagger.

[0060] Secondly, key steps in the preparation process, such as isostatic pressing, stepwise heating sintering, and spraying a silicon nitride coating, all have a positive impact on the compressive strength of the sagger. The isostatic pressing process enables the mixed aggregate and spherical matrix particles to form a mechanical interlocking structure, improving the internal bonding force of the sagger. Stepwise heating sintering helps to reduce the thermal stress during the sintering process, avoid generating cracks, and thus maintain the integrity of the sagger. Spraying a silicon nitride coating forms a dense surface sealing layer, further enhancing the compressive performance of the sagger.

[0061] In contrast, the saggers in the comparative examples have deficiencies in raw material ratio, preparation process, or microstructure, resulting in lower compressive strength. For example, in Comparative Example 1, yttria-stabilized zirconia is lacking, making the anti-corrosion barrier of the sagger unable to be effectively formed, and at the same time, the structural strength is also affected. In Comparative Example 5, conventional pressing is used instead of isostatic pressing to form the sagger, and a mechanical interlocking structure cannot be formed, resulting in a weakening of the internal bonding force of the sagger. These deficiencies directly affect the compressive strength of the sagger.

[0062] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same effect within the technical scope of this application are included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways constructed by combining some of the constituent elements in the embodiments are also included in the scope of this application.

Claims

1. An anti-corrosion ceramic crucible, characterized in that, The corrosion-resistant ceramic crucible comprises an aggregate layer and a matrix layer. The aggregate layer comprises the following raw materials in parts by mass: 30-50 parts of yttrium-stabilized zirconia, 20-30 parts of silicon carbide, 15-25 parts of magnesium aluminate spinel; The matrix layer comprises the following raw materials in parts by mass: 40-50 parts of mullite fine powder, 30-40 parts of cordierite fine powder and 10-20 parts of CeO2-modified silica sol.

2. The preparation method of the anti-corrosion ceramic crucible according to claim 1, characterized in that, It includes the following steps: S1: Ball-mill yttrium-stabilized zirconia, silicon carbide and magnesium aluminate spinel respectively, and then mix them evenly to obtain a mixed aggregate; Mix matrix mullite fine powder, cordierite fine powder, binder and water, ball-mill them, and then spray granulate to obtain spherical matrix particles; S2: Customize a graphite mold, fill the mixed aggregate and spherical matrix particles into the cavity of the graphite mold respectively, and prepare a crucible blank by an isostatic pressing forming process; S3: Dry, sinter, heat-insulate and cool the crucible blank to obtain a sintered crucible body; S4: Spray silicon nitride on the surface of the sintered crucible body, and then carry out secondary sintering to obtain a crucible.

3. The preparation method of the corrosion-resistant ceramic crucible according to claim 2, characterized in that, In step S1, the time for ball-milling yttrium-stabilized zirconia, silicon carbide and magnesium aluminate spinel respectively is 2-3 h, and the rotation speed is 200-260 rpm.

4. The preparation method of the corrosion-resistant ceramic crucible according to claim 2, characterized in that, In step S1, the mixing ratio of matrix mullite fine powder, cordierite fine powder, binder and water is 1.2-1.5:

1.

5. The preparation method of the corrosion-resistant ceramic crucible according to claim 2, wherein In step S1, the time for mixing matrix mullite fine powder, cordierite fine powder, binder and water and ball-milling is 4-5 h to make the slurry viscosity ≤ 200 mPa·s.

6. The preparation method of the corrosion-resistant ceramic crucible according to claim 2, characterized in that, In step S1, the inlet temperature of the spray granulation is 280-320 °C, and the outlet temperature is 110-130 °C; and / or the particle size of the spherical matrix particles is 80-120 μm.

7. The preparation method of the corrosion-resistant ceramic crucible according to claim 2, wherein In step S2, the mixed aggregate and the spherical matrix particles are mixed in a ratio of 1.2-1.8:1, and a polyvinyl alcohol solution is added to the mixed aggregate and stirred until the moisture content of the mixed aggregate is 8-10%; and / or The pressure in the isostatic pressing forming process is 80-100 MPa, and the pressure is maintained for 5-10 min.

8. The preparation method of the corrosion-resistant ceramic crucible according to claim 2, characterized in that, The method for sintering the crucible blank in step S3 is: Raise the temperature to 1000-1100 °C at a rate of 2-5 °C / min and keep it warm for 30-60 min; Under a protective atmosphere, continue to raise the temperature to 1400-1500 °C at a rate of 2-5 °C / min and keep it warm for 2-3 h.

9. The preparation method of the corrosion-resistant ceramic crucible according to claim 2, characterized in that, In step S4, the temperature of the secondary sintering is 800-850 °C, and the time is 1-1.5 h.

Images