Special ceramic based on modified aluminum ash and preparation method thereof

Abstract

The invention belongs to the technical field of ceramics, and discloses a special ceramic based on modified aluminum ash and a preparation method thereof. The special ceramic comprises the following raw material components in parts by weight: 1-10 parts of modified aluminum ash; 30 to 60 parts of clay; 10 to 20 parts of fly ash; 1 to 10 parts of niobium pentoxide; 1 to 5 parts of albite; 5 to 15 parts of barite; 2-8 parts of a metal oxide; 1-5 parts of carbide; 3 to 10 parts of nitride; 1-5 parts of polyvinyl alcohol; wherein the modified raw materials of the modified aluminum ash comprise a silane coupling agent, acrylate and bisphenol A novolac epoxy resin containing double bonds. The invention provides a reliable scheme for efficient utilization of the secondary aluminum ash and green and high-performance development of special ceramics. The special ceramic has high hardness, high bending strength and corrosion resistance at the same time, the Vickers hardness is 92-95 GPa, the bending strength is 974-991 MPa, and the corrosion depth is 0.20-0.32 mm.

Description

Technical Field

[0001] This invention belongs to the field of ceramic technology, specifically relating to a special ceramic based on modified aluminum ash and its preparation method. Background Technology

[0002] With the rapid development of the aluminum industry, the large amount of aluminum ash generated during aluminum smelting and processing has become an environmental problem that urgently needs to be addressed. Aluminum ash, especially secondary aluminum ash, contains harmful components such as aluminum nitride, salts, and heavy metals. Improper handling can easily lead to soil and water pollution and resource waste. How to achieve the harmless and high-value utilization of aluminum ash has become the key to promoting green manufacturing and a circular economy. Transforming secondary aluminum ash into high-value-added materials such as special ceramics can not only alleviate environmental pressure but also provide low-cost raw materials for the ceramics industry, which has significant economic and social implications.

[0003] Currently, the treatment of secondary aluminum ash mainly focuses on pretreatment technologies such as denitrification, desalination, and stabilization, including processes like water washing, alkali leaching, or pyrometallurgy. In the ceramics field, these methods are mostly applied through direct incorporation or simple modification as raw materials. For example, some studies have improved dispersibility by physically mixing aluminum ash with the ceramic matrix or by surface coating modification. However, these methods are often limited to the primary utilization of aluminum ash and fail to fully control its interfacial properties and compatibility with the ceramic matrix, leading to defects in the internal structure of the material. Furthermore, residual impurities and incompletely removed salts in the aluminum ash may affect the densification process of ceramics, thereby limiting their mechanical properties and chemical stability.

[0004] Despite some progress in the research of alumina ash-based ceramics, existing technologies generally suffer from the following problems: modification processes fail to effectively activate the active components of alumina ash, resulting in weak chemical bonding with the ceramic matrix; the material composition design lacks synergy, making it difficult to balance high hardness, high strength, and corrosion resistance; and the introduction of alumina ash during preparation easily introduces porosity or cracks, leading to performance fluctuations. These problems mean that the overall performance of existing alumina ash-based ceramics still lags behind that of traditional special ceramics, particularly limiting their application in harsh environments such as high temperatures and corrosion.

[0005] Therefore, there is an urgent need to develop a new method for preparing high-performance special ceramics using aluminum ash, so as to further improve the performance of special ceramics in terms of surface hardness, mechanical strength and corrosion resistance. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a special ceramic based on modified aluminum ash and its preparation method, which can simultaneously possess high hardness, high flexural strength and corrosion resistance.

[0007] The inventive concept of this invention is as follows: On the one hand, this invention uses a silane coupling agent to perform surface grafting modification on denitrified and desalted aluminum ash; on the other hand, it synthesizes a functionalized prepolymer (bisphenol A phenolic epoxy resin containing double bonds) that combines the rigidity of epoxy resin with the reactivity of acrylate. Through free radical copolymerization, the aluminum ash with the surface-grafted silane coupling agent, acrylate monomers, and bisphenol A phenolic epoxy resin containing double bonds are combined to construct a multi-scale reinforced aluminum ash-resin synergistic system, thereby solving the interfacial compatibility problem between aluminum ash and the ceramic matrix, and simultaneously improving the hardness, flexural strength, and corrosion resistance of the special ceramics. Furthermore, during calcination, the organic-inorganic hybrid layer on the surface of the modified aluminum ash carbonizes to form a continuous carbon network, which, together with the low-melting-point glass phase formed by albite in the ceramic matrix, promotes grain rearrangement, effectively reducing porosity and microcracks, forming a densification barrier, and further improving the stability and density of the special ceramics.

[0008] To solve the above-mentioned technical problems, the first aspect of the present invention provides a special ceramic, characterized in that its raw material components, by weight, comprise: 1-10 parts of modified aluminum ash; 30-60 parts clay; 10-20 parts fly ash; 1-10 parts of niobium pentoxide; 1-5 parts of albite; 5-15 parts barite; 2-8 parts of metal oxides; 1-5 parts of carbide; Nitrogen compounds 3-10 parts; 1-5 parts of polyvinyl alcohol; The modified aluminum ash uses silane coupling agents, acrylates, and bisphenol A phenolic epoxy resin containing double bonds as the modifying raw materials.

[0009] Specifically, this invention modifies aluminum ash using a silane coupling agent, acrylate, and bisphenol A phenolic epoxy resin containing double bonds. Through free radical copolymerization, the double bonds on the surface of the aluminum ash, the acrylate monomer, and the epoxy resin containing double bonds are grafted onto the silane coupling agent and composited. The silane coupling agent forms a chemical cross-linking network with the double bonds in the resin, while the epoxy groups interact strongly with the polymer polyvinyl alcohol, as well as inorganic components such as fly ash and clay, through hydrogen bonds, thereby constructing a multi-scale reinforced aluminum ash-resin synergistic system. This unique structural design not only solves the interfacial compatibility problem between aluminum ash and the ceramic matrix but also achieves simultaneous optimization of stress transfer efficiency and corrosion resistance through an organic-inorganic hybrid mechanism. This improves the hardness and flexural strength of the special ceramic while optimizing its corrosion resistance.

[0010] Furthermore, during calcination, the organic-inorganic hybrid layer coating the surface of the modified aluminum ash forms a continuous carbon network through high-temperature carbonization, which, together with the Al2O3 phase in the aluminum ash, fills the grain boundary interstices. Simultaneously, the modified aluminum ash and albite generate a low-melting-point glassy phase at high temperatures, promoting grain rearrangement through a liquid-phase sintering mechanism, significantly reducing porosity and microcracks, thereby forming a dense barrier in a high-temperature corrosive environment. This synergistic effect between the calcination process and the modified aluminum ash components jointly enhances the stability and density of the special ceramics during calcination, further improving their hardness and flexural strength.

[0011] In some embodiments of the present invention, the metal compound is selected from at least one of zirconium oxide, nickel oxide, zinc oxide, magnesium oxide, or beryllium oxide.

[0012] In some embodiments of the present invention, the carbide is selected from at least one of silicon carbide, boron carbide, zirconium carbide, vanadium carbide, tantalum carbide or titanium carbide.

[0013] In some embodiments of the present invention, the nitride is selected from at least one of silicon nitride and boron nitride.

[0014] In some embodiments of the present invention, the modification process of the modified aluminum ash includes the following steps: (1) Aluminum ash is mixed with silane coupling agent and heated to react, so as to obtain aluminum ash with surface grafted silane coupling agent; (2) The aluminum ash with surface-grafted silane coupling agent is mixed with acrylate and bisphenol A phenolic epoxy resin containing double bonds, and heated to react to obtain the modified aluminum ash.

[0015] In some embodiments of the present invention, in step (1), the mass ratio of the aluminum ash to the silane coupling agent is 1:(0.1-2); the temperature of the heating reaction is 100-120°C.

[0016] In some embodiments of the present invention, in step (1), the aluminum ash further includes desalting and denitrification steps before being blended with the silane coupling agent.

[0017] In some embodiments of the present invention, a low-temperature rapid leaching method is used to desalinate aluminum ash. The desalination step is as follows: aluminum ash is added to water for leaching to obtain desalinated aluminum ash.

[0018] In some embodiments of the present invention, the temperature of the water is below 25°C, the mass ratio of aluminum ash to water is 1:(5-10), and the leaching time is 5-10 min.

[0019] In some embodiments of the present invention, denitrification is performed by adding an alkaline solution. The denitrification step is as follows: desalted aluminum ash is added to an alkaline solution, heated and stirred to obtain denitrified and desalted aluminum ash.

[0020] In some embodiments of the present invention, the mass concentration of the alkaline solution is 1-10%, the heating temperature is 40-60°C, the reaction time is 4-10 h, and the generated ammonia gas is absorbed by an acid solution. The alkaline solution is preferably sodium hydroxide.

[0021] In some embodiments of the present invention, in step (1), the silane coupling agent is selected from KH750.

[0022] In some embodiments of the present invention, in step (2), the preparation process of the bisphenol A phenolic epoxy resin containing double bonds includes the following steps: first, bisphenol A and formaldehyde solution are mixed and heated to 80-130℃ for 4-10h to obtain bisphenol A phenolic resin; then, the bisphenol A phenolic resin is mixed with epichlorohydrin, a catalyst is added, and the mixture is heated to 60-80℃ for 4-10h to obtain bisphenol A phenolic epoxy resin; then, the bisphenol A phenolic epoxy resin is mixed with acrylic acid and heated to 100-120℃ for 5-10h to obtain the bisphenol A phenolic epoxy resin containing double bonds.

[0023] In some embodiments of the present invention, the molar ratio of bisphenol A to formaldehyde solution is 1:(0.8-1.0), and the concentration of formaldehyde solution is 30-50wt%.

[0024] In some embodiments of the present invention, the mass ratio of the bisphenol A phenolic resin to epichlorohydrin is 1:(2-4).

[0025] In some embodiments of the present invention, the catalyst is a phase transfer catalyst, preferably hexadecyltrimethylammonium bromide, and the amount of the catalyst is 0.2-0.5 wt% of the reactants.

[0026] In some embodiments of the present invention, the molar ratio of the bisphenol A phenolic epoxy resin to acrylic acid is 1:(5-7).

[0027] Specifically, this invention first employs a combined water leaching and alkali treatment process to denitrify and desalinate aluminum ash, efficiently removing harmful components while exposing active sites on the aluminum ash surface and enhancing its reactivity. Based on this, a silane coupling agent is used to perform surface grafting modification on the aluminum ash. The silanol groups generated by the hydrolysis form stable covalent bonds with the hydroxyl groups on the aluminum ash surface, while simultaneously introducing terminal double-bond functional groups, laying the foundation for subsequent chemical bonding with the resin matrix. On the other hand, a phenolic resin skeleton is constructed through the condensation reaction of bisphenol A and formaldehyde, followed by an epoxy ring-opening reaction with epichlorohydrin to form a bisphenol A phenolic epoxy resin. Further, through the esterification reaction of acrylic acid and epoxy groups, polymerizable double bonds are introduced into the molecular chain, forming a functionalized prepolymer that combines the rigidity of epoxy resin with the reactivity of acrylate, namely, a bisphenol A phenolic epoxy resin containing double bonds.

[0028] In some embodiments of the present invention, in step (2), the mass ratio of the aluminum ash, acrylate and bisphenol A phenolic epoxy resin containing double bonds of the surface-grafted silane coupling agent is 1:(1-5):(1-5).

[0029] A second aspect of the present invention provides a method for preparing the above-mentioned special ceramics, comprising the following steps: After mixing the raw materials, they are extruded to form a green body; then the green body is subjected to atmospheric pressure calcination and hot pressing calcination to obtain the special ceramic.

[0030] In some embodiments of the present invention, the mixing steps of the raw materials are as follows: first, clay, fly ash, niobium pentoxide and albite are mixed, ground and passed through a 200-250 mesh sieve, and calcined at 850-920°C for 4-6 hours under inert gas conditions. After cooling, the mixture is ground again and passed through a 100-150 mesh sieve to obtain powder A; then, powder A is mixed with barite, metal oxide, carbide and nitride, calcined at 950-1040°C for 1-3 hours, and after cooling, ground and passed through a 60-100 mesh sieve to obtain powder B; finally, powder B, polyvinyl alcohol, modified aluminum ash and water are mixed and ground.

[0031] In some embodiments of the present invention, the temperature of the atmospheric calcination is 1000-1100℃, and the time of the atmospheric calcination is 2-4 hours.

[0032] In some embodiments of the present invention, the hot pressing and calcining temperature is 1600-1700℃, the hot pressing and calcining pressure is 20-40MPa, and the hot pressing and calcining time is 60-80min.

[0033] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages: (1) This invention modifies aluminum ash using a silane coupling agent, acrylate, and bisphenol A phenolic epoxy resin containing double bonds. The silane coupling agent is grafted onto the double bonds on the aluminum ash surface, along with the acrylate monomer and the epoxy resin containing double bonds, through a free radical copolymerization reaction. The silane coupling agent forms a chemical cross-linking network with the double bonds in the resin, while the epoxy groups interact strongly with the polymer polyvinyl alcohol and inorganic components through hydrogen bonds, thus constructing a multi-scale enhanced aluminum ash-resin synergistic system. This unique structural design not only solves the interfacial compatibility problem between aluminum ash and the ceramic matrix but also achieves simultaneous optimization of stress transfer efficiency and corrosion resistance through an organic-inorganic hybrid mechanism. This improves the hardness and flexural strength of the special ceramic while optimizing its corrosion resistance.

[0034] (2) During the calcination process of the special ceramics of the present invention, the organic-inorganic hybrid layer coated on the surface of the modified aluminum ash will form a continuous carbon network through high-temperature carbonization, which together with the Al2O3 phase in the aluminum ash will fill the intergranular gaps. At the same time, the modified aluminum ash and albite will generate a low-melting-point glass phase at high temperature, which will promote grain rearrangement through the liquid-phase sintering mechanism, significantly reducing porosity and microcracks, thereby forming a densification barrier in the high-temperature corrosive environment. This synergistic effect between the calcination process and the modified aluminum ash components will jointly improve the stability and densification of the special ceramics during the calcination process, and further improve its hardness and bending strength.

[0035] (3) This invention provides a new way for the efficient utilization of aluminum ash and a reliable solution for the green and high-performance development of special ceramics. The special ceramics prepared simultaneously possess high hardness, high flexural strength and corrosion resistance, achieving a Vickers hardness of 92-95 GPa, a flexural strength of 974-991 MPa and a corrosion depth of 0.20-0.32 mm. Detailed Implementation

[0036] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0037] The raw materials used in the following examples and comparative examples were purchased from the following companies, and the water used was deionized water; m / m represents the mass ratio, and n / n represents the molar ratio.

[0038] Red clay: purchased from Lingshou County Aoxin Mineral Products Co., Ltd.

[0039] Fly ash: purchased from Wuhan Jiyesheng Chemical Co., Ltd.

[0040] Sodium feldspar: purchased from Shanghai Yuanye Biotechnology Co., Ltd., grade T22416.

[0041] Barite: Purchased from Shijiazhuang Tourmaline Mineral Products Co., Ltd.

[0042] Polyvinyl alcohol: purchased from Jiangsu Pules Biotechnology Co., Ltd., brand name 17-99S(H).

[0043] Secondary aluminum ash: purchased from Inner Mongolia Huomei Hongjun Aluminum & Electricity Co., Ltd.

[0044] Example 1 A special ceramic, the raw material components of which, by weight, include: 7 parts modified aluminum ash; 45 parts red clay; 15 parts fly ash; 6 parts of niobium pentoxide; 4 parts of albite; 7 parts barite; 3 parts nickel oxide; 3 parts zinc oxide; 3 parts silicon carbide; 6 parts of boron nitride; 4 parts polyvinyl alcohol.

[0045] The modification process of modified aluminum ash includes the following steps: (1) Place the secondary aluminum ash in a leaching kettle, add water (secondary aluminum ash: water = 1:8, m / m), leach at 20℃ for 10 min, filter and dry to obtain desalted aluminum ash; then immerse the desalted aluminum ash in 8wt% sodium hydroxide solution, stir and react at 60℃ for 6 h, filter and dry, absorb ammonia with dilute hydrochloric acid to obtain denitrified and desalted aluminum ash; then blend the denitrified and desalted aluminum ash with KH570 (denitrified and desalted aluminum ash: KH570 = 1:1, m / m), react at 110℃ for 8 h, filter and dry to obtain KH570 grafted aluminum ash.

[0046] (2) Using n-butanol as solvent, bisphenol A and 40wt% formaldehyde solution were mixed (bisphenol A: formaldehyde = 1:0.9, n / n), and 25wt% sodium hydroxide solution was added (the amount of sodium hydroxide was 1.3% of the reactant mass). The mixture was refluxed at 100℃ for 5h. After the reaction was completed, the solvent and water were removed under pressure, and then 50wt% sulfuric acid solution was added to neutralize the sodium hydroxide. The mixture was washed with water until neutral and then vacuum distilled to obtain bisphenol A phenolic resin. Then, bisphenol A phenolic resin and epichlorohydrin were mixed (bisphenol A phenolic resin: epichlorohydrin = 1:3, m / m), and a phase transfer catalyst was added. Hexadecyltrimethylammonium bromide (0.4 wt% of reactants) was reacted at 80°C for 6 h, then cooled to 50°C, and a 10 wt% sodium hydroxide aqueous solution (2 wt% of reactants) was added dropwise. After the addition was complete, the temperature was raised to 70°C and the reaction continued for 4 h. Water and epichlorohydrin were distilled off, purified with benzene solution, and washed with water to obtain bisphenol A phenolic epoxy resin. The bisphenol A phenolic epoxy resin was then blended with acrylic acid (bisphenol A phenolic epoxy resin: acrylic acid = 1:6, n / n) and reacted at 100°C for 7 h to obtain bisphenol A phenolic epoxy resin containing double bonds.

[0047] (3) Using acetone as solvent, KH570 grafted aluminum ash, methyl acrylate and bisphenol A phenolic epoxy resin containing double bonds were blended (KH570 grafted aluminum ash: acrylate: bisphenol A phenolic epoxy resin containing double bonds = 1:5:3, m / m / m), sodium persulfate was added (the amount was 1 wt% of the reactants), and the mixture was reacted at 80℃ for 10 h. After filtration and drying, modified aluminum ash was obtained.

[0048] The preparation method of the above-mentioned special ceramics includes the following steps: Red clay, fly ash, niobium pentoxide, and albite were mixed and ground in a ball mill for 2 hours, then passed through a 230-mesh sieve. The mixture was calcined at 890°C for 5 hours under helium protection, cooled to room temperature, and ground again for 2 hours, then passed through a 120-mesh sieve to obtain powder A. Powder A was then mixed with barite, nickel oxide, zinc oxide, silicon carbide, and boron nitride, stirred, and dispersed. The mixture was calcined at 990°C for 2 hours, cooled to room temperature, ground in a ball mill for 2 hours, and passed through an 80-mesh sieve to obtain powder B. Powder B was then mixed with polyvinyl alcohol, modified aluminum ash, and water (the total mass ratio of powder B, polyvinyl alcohol, modified aluminum ash, and water was 5:3), ground in a ball mill for 18 hours, and then extruded in an extruder to obtain a preliminary blank. This blank was calcined at atmospheric pressure and 1050°C for 3 hours to obtain a dry blank, and then hot-pressed at 1680°C with a pressing pressure of 30 kJ / kg. The pressure was set at MPa, the hot pressing time was 70 min, and after cooling, the special ceramic based on modified aluminum ash in this embodiment was obtained.

[0049] Example 2 A special ceramic, the raw material components of which, by weight, include: 5 parts modified aluminum ash; 41 parts red clay; 12 parts fly ash; 5 parts of niobium pentoxide; 3 parts of albite; 10 parts barite; 3 parts nickel oxide; 3 parts zinc oxide; 3 parts silicon carbide; 6 parts of boron nitride; 4 parts polyvinyl alcohol.

[0050] The modification process of the modified aluminum ash and the preparation method of the special ceramics in Example 2 are the same as those in Example 1.

[0051] Example 3 A special ceramic, the raw material components of which, by weight, include: 9 parts modified aluminum ash; 53 portions of red clay; 17 parts fly ash; 8 parts of niobium pentoxide; 5 parts of albite; 12 parts barite; 3 parts nickel oxide; 3 parts zinc oxide; 3 parts silicon carbide; 6 parts of boron nitride; 4 parts polyvinyl alcohol.

[0052] The modification process of the modified aluminum ash and the preparation method of the special ceramics in Example 3 are the same as those in Example 1.

[0053] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that step (2) in the modification process of modified aluminum ash is different. In Comparative Example 1, the bisphenol A phenolic epoxy resin in step (2) is replaced with an equimolar mass of epoxy resin E44.

[0054] Step (2) of Comparative Example 1 is as follows: epoxy resin E44 and acrylic acid are blended (epoxy resin E44: acrylic acid = 1:6, n / n), and reacted at 100℃ for 7h to obtain epoxy acrylate resin. In the corresponding step (3), an equal amount of epoxy acrylate resin is used to replace the bisphenol A phenolic epoxy resin containing double bonds.

[0055] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that step (3) in the modification process of modified aluminum ash is different. Methyl acrylate was not added in step (3) of Comparative Example 3.

[0056] Step (3) of Comparative Example 2 is as follows: using acetone as solvent, KH570 grafted aluminum ash and bisphenol A phenolic epoxy resin containing double bonds are mixed (KH570 grafted aluminum ash: bisphenol A phenolic epoxy resin containing double bonds = 1:3, m / m), reacted at 80℃ for 10h, filtered and dried to obtain modified aluminum ash.

[0057] Performance testing The performance of the special ceramic samples prepared in Examples 1-3 and Comparative Examples 1-2 was tested. Specifically, the Vickers hardness of the samples was measured using a micro Vickers hardness tester; the flexural strength of the samples was tested using a PT-1036PC universal testing machine; and lithium cobalt oxide was prepared by sintering Li2CO3 and CoCO3 into the samples at 1000℃ and holding at that temperature for 20 hours. The depth of corrosion on the inner wall of the special ceramic materials at different temperatures was then observed.

[0058] The test results are shown in Table 1.

[0059] Table 1:

[0060] As shown in Table 1, the special ceramics prepared in Examples 1-3 of this invention all possess good hardness, flexural strength, and corrosion resistance, achieving a Vickers hardness of 92-95 GPa, a flexural strength of 974-991 MPa, and a corrosion depth of 0.20-0.32 mm. Moreover, all of their properties are superior to those of the special ceramics prepared in Comparative Examples 1-2, which use different methods to modify aluminum ash.

[0061] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. A special ceramic, characterized in that, Its raw material components, by weight, include: 1-10 parts of modified aluminum ash; 30-60 parts clay; 10-20 parts fly ash; 1-10 parts of niobium pentoxide; 1-5 parts of albite; 5-15 parts barite; 2-8 parts of metal oxides; 1-5 parts of carbide; Nitrogen compounds 3-10 parts; 1-5 parts of polyvinyl alcohol; The modified aluminum ash uses silane coupling agents, acrylates, and bisphenol A phenolic epoxy resin containing double bonds as the modifying raw materials.

2. The special ceramic according to claim 1, characterized in that, The metallization is selected from at least one of zirconium oxide, nickel oxide, zinc oxide, magnesium oxide, or beryllium oxide; And / or, the carbide is selected from at least one of silicon carbide, boron carbide, zirconium carbide, vanadium carbide, tantalum carbide or titanium carbide; And / or, the nitride is selected from at least one of silicon nitride and boron nitride.

3. The special ceramic according to claim 1, characterized in that, The modification process of the modified aluminum ash includes the following steps: (1) Aluminum ash is mixed with silane coupling agent and heated to react, so as to obtain aluminum ash with surface grafted silane coupling agent; (2) The aluminum ash with surface-grafted silane coupling agent is mixed with acrylate and bisphenol A phenolic epoxy resin containing double bonds, and heated to react to obtain the modified aluminum ash.

4. The special ceramic according to claim 3, characterized in that, In step (1), the mass ratio of aluminum ash to silane coupling agent is 1:(0.1-2); the heating reaction temperature is 100-120℃.

5. The special ceramic according to claim 3, characterized in that, In step (1), the aluminum ash further includes desalting and denitrification steps before being blended with the silane coupling agent.

6. The special ceramic according to claim 3, characterized in that, In step (2), the preparation process of the bisphenol A phenolic epoxy resin containing double bonds includes the following steps: first, bisphenol A and formaldehyde solution are mixed and heated to 80-130℃ for 4-10h to obtain bisphenol A phenolic resin; then, the bisphenol A phenolic resin is mixed with epichlorohydrin, a catalyst is added, and the mixture is heated to 60-80℃ for 4-10h to obtain bisphenol A phenolic epoxy resin; then, the bisphenol A phenolic epoxy resin is mixed with acrylic acid and heated to 100-120℃ for 5-10h to obtain the bisphenol A phenolic epoxy resin containing double bonds.

7. The special ceramic according to claim 6, characterized in that, The formaldehyde solution has a concentration of 30-50 wt%, and the molar ratio of bisphenol A to formaldehyde solution is 1:(0.8-1.0); the mass ratio of bisphenol A phenolic resin to epichlorohydrin is 1:(2-4); and the molar ratio of bisphenol A phenolic epoxy resin to acrylic acid is 1:(5-7).

8. The special ceramic according to claim 3, characterized in that, In step (2), the mass ratio of the aluminum ash, acrylate and bisphenol A phenolic epoxy resin containing double bonds of the surface-grafted silane coupling agent is 1:(1-5):(1-5).

9. A method for preparing a special ceramic as described in any one of claims 1-8, characterized in that, Includes the following steps: After mixing the raw materials, they are extruded to form a green body; then the green body is subjected to atmospheric pressure calcination and hot pressing calcination to obtain the special ceramic.

10. The method for preparing special ceramics according to claim 9, characterized in that, The calcination temperature under normal pressure is 1000-1100℃, and the calcination time under normal pressure is 2-4 hours; And / or, the hot pressing and calcining temperature is 1600-1700℃, the hot pressing and calcining pressure is 20-40MPa, and the hot pressing and calcining time is 60-80min.

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