ZTA ceramic powder, ceramic substrate and preparation method thereof

Abstract

The invention discloses ZTA ceramic powder, a ceramic substrate and a preparation method of the ceramic substrate, and relates to the field of ceramic substrate materials. The preparation method of the ZTA ceramic powder comprises the following steps: dissolving aluminum alkoxide in an organic solvent, adding a polyether alcohol dispersant, uniformly stirring, and adjusting the pH value to 2.8-3.2 to obtain an aluminum precursor solution; the zirconium precursor solution is dropwise added into the aluminum precursor solution, the molar ratio of Al to Zr in an aluminum precursor and a zirconium precursor is (5-20): 1, and an aluminum-zirconium mixed solution is obtained; and adding water into the aluminum-zirconium mixed solution, heating for hydrolysis reaction, cooling and stirring to form gel, freeze-drying and calcining to obtain the ZTA ceramic powder with uniform particle size, good dispersity and regular morphology, thereby enhancing the density, thermal conductivity, hardness and bending strength of the substrate.

Description

Technical Field

[0001] This application relates to the field of ceramic substrate materials technology, and in particular to a ZTA ceramic powder, a ceramic substrate, and a method for preparing the same. Background Technology

[0002] Zirconia-toughened alumina (ZTA) ceramic substrates are composite ceramic materials formed by adding a zirconia (ZrO2) toughening phase to an alumina (Al2O3) matrix. This material combines the high hardness, high insulation, and good chemical stability of alumina with the high toughness and phase transformation toughening properties of zirconia, resulting in a high-performance ceramic substrate material. ZTA ceramic substrates, with their excellent mechanical strength, thermal stability, and electrical insulation properties, are widely used in electronic packaging, power modules, high-frequency communications, LED substrates, and automotive electronics.

[0003] Currently, ZTA ceramic substrate products on the market mainly achieve different performance balances by controlling the zirconium oxide content (10-20%), optimizing the sintering process, and improving the microstructure design to meet the needs of various electronic applications. One of the keys to preparing high-performance ZTA ceramics lies in highly uniform nanopowder raw materials. Traditional mechanical mixing methods and high-temperature calcination processes are difficult to meet the uniformity and activity requirements of nanoscale powders. Chemical preparation methods, including sol-gel methods and chemical coprecipitation methods, can effectively control powder characteristics to a certain extent through molecular-level mixing. Regarding the chemical coprecipitation method, it depends on the precipitation conditions and is prone to local segregation and particle agglomeration. For example, a method for preparing ZTA ceramic-reinforced iron-based composite materials in patent CN115627407A involves coprecipitating ZTA precursors from solutions of ammonium aluminum sulfate, zirconium oxychloride, and rare earth nitrates, followed by calcination, reduction, and sintering processes to obtain ZTA ceramic-reinforced iron-based composite materials. The method employs co-precipitation to prepare ZTA ceramic-reinforced iron-based composite materials at room temperature and atmospheric pressure, reducing experimental conditions and improving the experimental environment. However, the powder morphology shows agglomeration, poor uniformity and dispersibility, and failure to form a regularly shaped crystal structure. Regarding the sol-gel method, such as patent CN113862548A, a method for preparing in-situ self-generated ZTA particles-reinforced steel-based composite materials, a transparent sol is prepared using aluminum nitrate nonahydrate and zirconium oxynitrate hydrate as raw materials. Steel-based powder is added to the sol for liquid-solid doping, and after stirring until solidification, vacuum drying and reduction of the ZTA / steel mixed powder are performed sequentially. The ZTA ceramic is generated in-situ, the ceramic particle surface is uncontaminated, and it has good compatibility with the steel matrix, with high interfacial bonding strength. This method directly mixes aluminum and zirconium precursors to prepare the sol, resulting in poor material dispersibility, severe agglomeration, and failure to form regularly shaped crystals in its microstructure. Therefore, it is necessary to study a ZTA powder with high uniformity, dispersibility and regular crystal morphology, so as to improve grain boundary strength, reduce thermal expansion mismatch, enhance the density of ZTA substrate, and improve thermal conductivity and mechanical properties. Summary of the Invention

[0004] The purpose of this invention is to overcome the existing defects and shortcomings and provide a method for preparing ZTA ceramic powder, so as to obtain ZTA ceramic powder with uniform particle size, good dispersibility and regular morphology.

[0005] Another object of the present invention is to provide a ZTA ceramic substrate obtained by the above preparation method.

[0006] Another objective of this invention is to provide a ZTA ceramic substrate that is sintered at a lower temperature to obtain a ZTA ceramic substrate with higher density, while simultaneously achieving both high density and rigidity.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution: This invention protects a method for preparing ZTA ceramic powder, comprising the following steps: S1, dissolve aluminum alkoxide in an organic solvent, add polyether alcohol dispersant and stir until homogeneous, adjust pH to 2.8-3.2 to obtain aluminum precursor solution; S2, dissolve zirconium alkoxide in an organic solvent to prepare a zirconium precursor solution; S3, the zirconium precursor solution from step S2 is added dropwise to the aluminum precursor solution from step S1, wherein the molar ratio of Al and Zr in the aluminum precursor and zirconium precursor is (5-20):1, to obtain an aluminum-zirconium mixture. S4, add water to the aluminum-zirconium mixture, heat to carry out hydrolysis reaction, cool and stir to form a gel, freeze dry, calcine to obtain the ZTA ceramic powder.

[0008] The method for preparing ZTA ceramic powder of the present invention involves mixing aluminum alkoxide and polyether alcohol dispersant in an aluminum precursor solution to form a stable dispersion network, while the oxygen atoms in the ether bonds react with Al. 3+ Coordination bonds are formed for protection, reducing the competitive reaction between zirconium ions and aluminum ions. After adding the zirconium precursor solution, the zirconium particles are coated with the dispersant in the early stage of formation, avoiding direct contact and agglomeration between zirconium particles and achieving excellent dispersion effect. In addition, in the aluminum-rich environment, the crystallization of zirconium is inhibited, which is conducive to the formation of more amorphous structures, so that the ZTA powder is partially amorphized in the subsequent calcination. At the same time, Al2O3 and ZrO2 undergo orderly crystal growth during sintering, resulting in ZTA ceramic powder with uniform particle size, good dispersibility and regular morphology.

[0009] Specifically, the partial amorphization of ZrO2 powder enables the powder to be in a metastable state, possessing higher free energy and surface activity. This facilitates atomic diffusion and particle rearrangement during sintering, achieving low-temperature densification. Furthermore, the presence of the amorphous phase introduces oxygen vacancies, further accelerating mass transport and preventing excessive grain growth at high temperatures. Simultaneously, the amorphous phase more readily forms intracrystalline structures, with ZrO2 particles acting as crystal nuclei, growing alongside the Al2O3 matrix. This differs from using fully crystalline powder, where ZrO2 is primarily distributed at grain boundaries, resulting in fewer intracrystalline structures. The partially amorphous powder can also precipitate uniformly dispersed ultrafine nanoparticles during sintering, altering the fracture mode from intergranular to transgranular, thus improving the overall uniformity and mechanical properties of the material.

[0010] In some embodiments, the polyether alcohol dispersant is polyethylene glycol with an average molecular weight of 200-600 Da; the amount of the polyether alcohol dispersant is 3-6 wt% of the weight of the aluminum alkoxide, preferably 4-5 wt%.

[0011] In some embodiments, a crystallization inhibitor is further added to the aluminum precursor solution and / or zirconium precursor solution, the concentration of which is 0.1-0.5 g / mL.

[0012] Preferably, the crystallization inhibitor is citric acid.

[0013] In some embodiments, the zirconium precursor solution is added to the zirconium precursor solution aluminum precursor solution at a rate of 1.3-2.6 mL / min.

[0014] In some embodiments, in step S4, the hydrolysis reaction is carried out at a temperature of 70-80°C, a pH of 2.8-3.2, and a reaction time of 3-5 hours.

[0015] In some embodiments, in step S4, the molar ratio of water to metal (aluminum / zirconium) alkoxide in the hydrolysis reaction is (2-3):1, preferably 2.5:1.

[0016] In some embodiments, in step S4, the calcination is carried out in stages; the stage calcination conditions are as follows: first stage calcination: temperature 300-500℃, holding time 0.5-2h; second stage calcination: temperature 700-750℃, holding time 2.5-4h; third stage calcination: temperature 800-850℃, holding time 0.5-2h.

[0017] This invention protects a ZTA ceramic powder, which is prepared by the method described above.

[0018] In some embodiments, the D50 particle size of the ZTA ceramic powder is 30-120 nm, preferably 50-100 nm.

[0019] This invention protects a ZTA ceramic substrate, the raw materials of which include the following components by weight: 100 parts ZTA ceramic powder, 1-3 parts dispersant, 3-5 parts binder, 1-4 parts plasticizer, and 50-65 parts solvent.

[0020] Optionally, the adhesive is polyvinyl butyral (PVB); the plasticizer is dibutyl phthalate (DBP) and / or dioctyl phthalate (DOP).

[0021] Optionally, the solvent comprises 30-35 parts toluene, 15-20 parts ethanol and 5-8 parts methyl ethyl ketone; preferably, the solvent further comprises 1.0-1.5 parts polyethyleneimine (PEI) dispersant.

[0022] Preferably, the dispersant is a main dispersant and / or a multifunctional modified dispersant, wherein the multifunctional modified dispersant is formed by grafting the main dispersant with trimethyl phosphate and amino acids; the reaction conditions are: temperature 60-80℃, alkaline environment system.

[0023] Preferably, the amino acid is selected from histidine and / or arginine.

[0024] Preferably, the mass ratio of the main dispersant, trimethyl phosphate, and amino acids is 100:(0.5-2):(3-7).

[0025] Preferably, the primary dispersant is selected from polyamine compound dispersants and / or polyether compounds; polyamine compound dispersants include, but are not limited to, polyethyleneimine (PEI) or polyamide amine (PAMAM); polyether compounds include, but are not limited to, polyethylene glycol (PEG), polypropylene glycol (PPG), or their salt derivatives.

[0026] This invention protects a method for preparing a ZTA ceramic substrate, comprising the following steps: S201, the raw material components of the formula are distributed to prepare the casting paste; S202, the casting slurry is cast into a film, dried by gradient temperature increase, and degreased to obtain a cast film sheet; S203, the cast film is sintered at 1550-1690°C to obtain the ZTA ceramic substrate.

[0027] In some embodiments, the solid content of the cast slurry is 65-72%, and the viscosity at 25°C is 6000-7000 mPa·s.

[0028] In some embodiments, step S202, gradient temperature drying includes: first stage: top and bottom heating, temperature 30-50℃, negative pressure -2pa to +2pa; second stage: top and bottom heating, temperature 45-60℃, negative pressure -10pa to +2pa; third stage: hot air heating, temperature 60-100℃, negative pressure -5pa to +2pa; fourth stage: hot air heating, temperature 100-140℃, negative pressure -2pa to +5pa.

[0029] In some embodiments, the thickness of the cast film is 0.3-2.0 mm, and the casting speed is 0.1-0.8 mm / min.

[0030] In some embodiments, step S203 includes: heating the cast film to 500-600°C at a heating rate of 0.5-3°C / min, heating it to 1200-1400°C at a heating rate of 3-5°C / min, heating it to 1550-1690°C at a heating rate of 1-3°C / min and holding it at that temperature for 3-10 hours, cooling it to 500-800°C at a cooling rate of 5-10°C / min, and then cooling it in the furnace.

[0031] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a method for preparing ZTA ceramic powder. A stable dispersion network is formed by mixing aluminum alkoxide and polyether alcohol dispersant in an aluminum precursor solution. Upon addition of a zirconium precursor solution, the zirconium particles are coated with the dispersant in the early stages of formation, avoiding direct contact and agglomeration between zirconium particles and achieving excellent dispersion. Furthermore, in an aluminum-rich environment, zirconium crystallization is inhibited, which is conducive to the formation of more amorphous structures, enabling partial amorphization of the ZTA powder during subsequent calcination. Simultaneously, Al2O3 and ZrO2 undergo ordered crystal growth during sintering, resulting in ZTA ceramic powder with uniform particle size, good dispersibility, and regular morphology. Attached Figure Description

[0032] Figure 1 This is a SEM image of the powder obtained by a ZTA ceramic powder preparation method according to Example 1 of the present invention.

[0033] Figure 2 For the present invention Figure 1 SEM images at high magnification. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way.

[0035] Example 1 A method for preparing ZTA ceramic powder includes the following steps: S1, Dissolve 10.2g of aluminum isopropoxide in 100ml of anhydrous ethanol. Pre-dissolve 0.408g of polyether alcohol dispersant (PEG-400) in 10ml of ethanol and add it to the solution. Stir for 20min to ensure uniform mixing. Add 0.3g of citric acid and stir until uniform. Adjust the pH to 3.0±0.2 with dilute nitric acid to obtain the aluminum precursor solution. S2, dissolve 1.35g of zirconium n-butoxide in 50ml of anhydrous ethanol, stir well, add 0.1g of citric acid and continue stirring until well mixed to obtain a zirconium precursor solution. S3, under continuous stirring, the zirconium precursor solution from step S2 is added dropwise to the aluminum precursor solution from step S1. The dropwise addition time is 30 min, the temperature is 25℃, and the stirring speed is 300 rpm. After the dropwise addition is completed, stirring is continued for 15 min to obtain an aluminum-zirconium mixture. S4, the aluminum-zirconium mixture is heated to 75°C, and deionized water is added stepwise to carry out the hydrolysis reaction, controlling the pH value at 3.0±0.2, and the reaction time is 4 hours. The stepwise addition of deionized water is as follows: First time, 15 ml is added, and the dropping time is 45 min; second time, 20 ml is added, and the dropping time is 60 min; third time, 15 ml is added, and the dropping time is 45 min.

[0036] S5, after the reaction is complete, cool to 60℃ and continue stirring for 2 hours until a transparent gel is formed. Aging at room temperature for 24 hours. Freeze the gel at -50℃ for 4 hours, freeze-dry under vacuum for 48 hours (pressure <10Pa), heat to room temperature at a rate of 2℃ / h, and calcine in stages under air atmosphere.

[0037] The segmented calcination process specifically involves: heating to 450℃ and holding for 1 hour at a heating rate of 3℃ / min to remove residual organic matter; heating to 700℃ and holding for 3 hours at a heating rate of 5℃ / min to control the degree of crystallization; heating to 850℃ and holding for 1 hour at a heating rate of 2℃ / min to improve the crystal structure; and then naturally cooling to room temperature.

[0038] S6, Dispersion treatment: The calcined powder was added to 100 ml of anhydrous ethanol, and 0.1 g of polyacrylic acid (PAA) was added as a dispersant. The mixture was ultrasonically dispersed for 30 minutes (power 200 W, frequency 40 kHz), stirred at high speed for 1 hour (speed 1000 rpm), sieved (400 mesh) to remove large agglomerates, and ethanol was removed by rotary evaporation (40℃, reduced pressure). The mixture was then vacuum dried for 12 hours (60℃, pressure <100 Pa). The powder was then classified by airflow to obtain ZTA powder with a D50 particle size of 65 nm.

[0039] Example 2 A method for preparing ZTA ceramic powder includes the following steps: S1. Dissolve 8.7g of aluminum isopropoxide in 100ml of anhydrous ethanol. Pre-dissolve 0.408g of polyether alcohol dispersant (PEG-400) in 10ml of ethanol and add it to the solution. Stir for 20min to ensure uniform mixing. Add 0.2g of citric acid and stir until uniform. Adjust the pH to 3.0±0.2 with dilute nitric acid to obtain the aluminum precursor solution. S2, dissolve 2.02g of zirconium n-butoxide in 50ml of anhydrous ethanol, stir well, add 0.1g of citric acid and continue stirring until well mixed to obtain a zirconium precursor solution; S3, under continuous stirring, the zirconium precursor solution from step S2 is added dropwise to the aluminum precursor solution from step S1. The dropwise addition time is 30 min, the temperature is 25℃, and the stirring speed is 300 rpm. After the dropwise addition is completed, stirring is continued for 15 min to obtain an aluminum-zirconium mixture. S4, the aluminum-zirconium mixture is heated to 75°C, and deionized water is added stepwise to carry out the hydrolysis reaction, controlling the pH value at 3.0±0.2, and the reaction time is 4 hours. The stepwise addition of deionized water is as follows: First time, 15 ml is added, and the dropping time is 45 min; second time, 20 ml is added, and the dropping time is 60 min; third time, 15 ml is added, and the dropping time is 45 min.

[0040] S5, after the reaction is complete, cool to 60℃ and continue stirring for 2 hours until a transparent gel is formed. Aging at room temperature for 24 hours. Freeze the gel at -50℃ for 4 hours, freeze-dry under vacuum for 48 hours (pressure <10Pa), heat to room temperature at a rate of 2℃ / h, and calcine in stages under air atmosphere.

[0041] The segmented calcination process specifically involves: heating to 450℃ and holding for 1 hour at a heating rate of 3℃ / min to remove residual organic matter; heating to 750℃ and holding for 3 hours at a heating rate of 5℃ / min to control the degree of crystallization; heating to 800℃ and holding for 1 hour at a heating rate of 2℃ / min to improve the crystal structure; and then naturally cooling to room temperature.

[0042] S6, Dispersion treatment: The calcined powder was added to 100 ml of anhydrous ethanol, and 0.1 g of polyacrylic acid (PAA) was added as a dispersant. The mixture was ultrasonically dispersed for 30 minutes (power 200 W, frequency 40 kHz), stirred at high speed for 1 hour (speed 1000 rpm), sieved (200 mesh) to remove large agglomerates, and ethanol was removed by rotary evaporation (40℃, reduced pressure). The mixture was then vacuum dried for 12 hours (60℃, pressure <100 Pa). The powder was then classified by airflow to obtain ZTA powder with a D50 particle size of 100 nm.

[0043] Example 3 A method for preparing ZTA ceramic powder includes the following steps: S1, Dissolve 10.2g of aluminum isopropoxide in 100ml of anhydrous ethanol. Pre-dissolve 0.408g of polyether alcohol dispersant (PEG-400) in 10ml of ethanol and add it to the solution. Stir for 20min to ensure uniform mixing. Add 0.3g of citric acid and stir until uniform. Adjust the pH to 3.0±0.2 with dilute nitric acid to obtain the aluminum precursor solution. S2, dissolve 1.35g of zirconium n-butoxide in 50ml of anhydrous ethanol, stir well, add 0.1g of citric acid and continue stirring until well mixed to obtain a zirconium precursor solution. S3, under continuous stirring, the zirconium precursor solution from step S2 is added dropwise to the aluminum precursor solution from step S1. The dropwise addition time is 30 min, the temperature is 25℃, and the stirring speed is 300 rpm. After the dropwise addition is completed, stirring is continued for 15 min to obtain an aluminum-zirconium mixture. S4, the aluminum-zirconium mixture is heated to 70°C, and deionized water is added stepwise to carry out the hydrolysis reaction, controlling the pH value at 3.0±0.2, and the reaction time is 4 hours. The stepwise addition of deionized water is as follows: First time, 15 ml is added, and the dropping time is 45 min; second time, 20 ml is added, and the dropping time is 60 min; third time, 15 ml is added, and the dropping time is 45 min.

[0044] S5, after the reaction is complete, cool to 60℃ and continue stirring for 2 hours until a transparent gel is formed. Aging at room temperature for 24 hours. Freeze the gel at -65℃ for 4 hours, freeze-dry under vacuum for 48 hours (pressure <10Pa), heat to room temperature at a rate of 2℃ / h, and calcine in stages under air atmosphere.

[0045] The segmented calcination process specifically involves: heating to 450℃ and holding for 1 hour at a heating rate of 3℃ / min to remove residual organic matter; heating to 720℃ and holding for 3 hours at a heating rate of 5℃ / min to control the degree of crystallization; heating to 850℃ and holding for 1 hour at a heating rate of 2℃ / min to improve the crystal structure; and then naturally cooling to room temperature.

[0046] S6, Dispersion treatment: The calcined powder was added to 100 ml of anhydrous ethanol, and 0.1 g of polyacrylic acid (PAA) was added as a dispersant. The mixture was ultrasonically dispersed for 30 minutes (power 200 W, frequency 40 kHz), stirred at high speed for 1 hour (speed 1000 rpm), sieved (200 mesh) to remove large agglomerates, and ethanol was removed by rotary evaporation (40℃, reduced pressure). The mixture was then vacuum dried for 12 hours (60℃, pressure <100 Pa). The powder was then classified by airflow to obtain ZTA powder with a D50 particle size of 50 nm.

[0047] Example 4 A method for preparing ZTA ceramic powder includes the following steps: S1, Dissolve 10.2g of aluminum isopropoxide in 100ml of anhydrous ethanol. Pre-dissolve 0.408g of polyether alcohol dispersant (PEG-400) in 10ml of ethanol and add it to the solution. Stir for 20min to ensure uniform mixing. Add 0.3g of citric acid and stir until uniform. Adjust the pH to 3.0±0.2 with dilute nitric acid to obtain the aluminum precursor solution. S2, dissolve 1.35g of zirconium n-butoxide in 50ml of anhydrous ethanol, stir well, add 0.1g of citric acid and continue stirring until well mixed to obtain a zirconium precursor solution. S3, under continuous stirring, the zirconium precursor solution from step S2 is added dropwise to the aluminum precursor solution from step S1. The dropwise addition time is 30 min, the temperature is 25℃, and the stirring speed is 300 rpm. After the dropwise addition is completed, stirring is continued for 15 min to obtain an aluminum-zirconium mixture. S4, the aluminum-zirconium mixture is heated to 80°C, and deionized water is added stepwise to carry out the hydrolysis reaction, controlling the pH value at 3.0±0.2, and the reaction time is 4 hours. The stepwise addition of deionized water is as follows: First time, 15 ml is added, and the dropping time is 45 min; second time, 20 ml is added, and the dropping time is 60 min; third time, 15 ml is added, and the dropping time is 45 min.

[0048] S5, after the reaction is complete, cool to 60℃ and continue stirring for 2 hours until a transparent gel is formed. Aging at room temperature for 24 hours. Place the gel at -80℃ for 4 hours, freeze-dry under vacuum for 48 hours (pressure <10Pa), heat to room temperature at a heating rate of 2℃ / h, and calcine in stages under air atmosphere.

[0049] The segmented calcination process specifically involves: heating to 450℃ and holding for 1 hour at a heating rate of 3℃ / min to remove residual organic matter; heating to 700℃ and holding for 3 hours at a heating rate of 5℃ / min to control the degree of crystallization; heating to 825℃ and holding for 1 hour at a heating rate of 2℃ / min to improve the crystal structure; and then naturally cooling to room temperature.

[0050] S6, Dispersion treatment: The calcined powder was added to 100 ml of anhydrous ethanol, and 0.1 g of polyacrylic acid (PAA) was added as a dispersant. The mixture was ultrasonically dispersed for 30 minutes (power 200 W, frequency 40 kHz), stirred at high speed for 1 hour (speed 1000 rpm), sieved (300 mesh) to remove large agglomerates, and ethanol was removed by rotary evaporation (40℃, reduced pressure). The mixture was then vacuum dried for 12 hours (60℃, pressure <100 Pa). The powder was then classified by airflow to obtain ZTA powder with a D50 particle size of 80 nm.

[0051] Example 5 A method for preparing ZTA ceramic powder includes the following steps: S1. Dissolve 10.2g of aluminum isopropoxide in 100ml of anhydrous ethanol. Pre-dissolve 0.51g of polyether alcohol dispersant (PEG-400) in 10ml of ethanol and add it to the solution. Stir for 20min to ensure uniform mixing. Add 0.2g of citric acid and stir until uniform. Adjust the pH to 3.0±0.2 with dilute nitric acid to obtain the aluminum precursor solution. S2, dissolve 1.35g of zirconium n-butoxide in 50ml of anhydrous ethanol, stir well, add 0.1g of citric acid and continue stirring until well mixed to obtain a zirconium precursor solution. S3, under continuous stirring, the zirconium precursor solution from step S2 is added dropwise to the aluminum precursor solution from step S1. The dropwise addition time is 30 min, the temperature is 25℃, and the stirring speed is 300 rpm. After the dropwise addition is completed, stirring is continued for 15 min to obtain an aluminum-zirconium mixture. S4, the aluminum-zirconium mixture is heated to 75°C, and deionized water is added stepwise to carry out the hydrolysis reaction, controlling the pH value at 3.0±0.2, and the reaction time is 4 hours. The stepwise addition of deionized water is as follows: First time, 15 ml is added, and the dropping time is 45 min; second time, 20 ml is added, and the dropping time is 60 min; third time, 15 ml is added, and the dropping time is 45 min.

[0052] S5, after the reaction is complete, cool to 60℃ and continue stirring for 2 hours until a transparent gel is formed. Aging at room temperature for 24 hours. Freeze the gel at -50℃ for 4 hours, freeze-dry under vacuum for 48 hours (pressure <10Pa), heat to room temperature at a rate of 2℃ / h, and calcine in stages under air atmosphere.

[0053] The segmented calcination process specifically involves: heating to 450℃ and holding for 1 hour at a heating rate of 3℃ / min to remove residual organic matter; heating to 700℃ and holding for 3 hours at a heating rate of 5℃ / min to control the degree of crystallization; heating to 850℃ and holding for 1 hour at a heating rate of 2℃ / min to improve the crystal structure; and then naturally cooling to room temperature.

[0054] S6, Dispersion treatment: The calcined powder was added to 100 ml of anhydrous ethanol, and 0.1 g of polyacrylic acid (PAA) was added as a dispersant. The mixture was ultrasonically dispersed for 30 minutes (power 200 W, frequency 40 kHz), stirred at high speed for 1 hour (speed 1000 rpm), sieved (400 mesh) to remove large agglomerates, and ethanol was removed by rotary evaporation (40℃, reduced pressure). The mixture was then vacuum dried for 12 hours (60℃, pressure <100 Pa). The powder was then classified by airflow to obtain ZTA powder with a D50 particle size of 65 nm.

[0055] Example 6 A ZTA ceramic substrate, wherein the casting slurry comprises the following components in parts by weight: 100 parts ZTA ceramic powder, 0.6 parts sintering aid, 1 part dispersant, 8 parts binder, 2 parts plasticizer, and 55 parts solvent.

[0056] The ZTA ceramic powder was prepared by the method of Example 1. The sintering aids include: 0.3 parts Y2O3, 0.2 parts MgO, and 0.1 parts SiO2; The solvent used is 30 parts toluene, 20 parts ethanol and 5 parts methyl ethyl ketone; The dispersant is polyethyleneimine.

[0057] The adhesive is PVB; the plasticizer is DBP.

[0058] The method for preparing the ZTA ceramic substrate includes the following steps: S1, prepare casting slurry; mix toluene, ethanol and methyl ethyl ketone, and add dispersant and stir to dissolve to obtain pretreated solvent; add ZTA ceramic powder and sintering aid to pretreated solvent, disperse at high speed (3000 rpm, 30 min), control solid content at 72 wt%, and ball mill for 5 h.

[0059] Dissolve the adhesive PVB in an equal mass of toluene (60°C, stirring for 2 hours), add the plasticizer DBP, continue stirring for 1 hour, and cool to room temperature.

[0060] The PVB solution was slowly added to the ball-milled powder slurry, stirred at low speed (200 rpm) for 2 hours, and then degassed under vacuum (vacuum degree -0.08 MPa) for 30 minutes to obtain the casting slurry.

[0061] S2, the casting slurry is cast into a film, dried by gradient temperature increase, and degreased to obtain a cast film sheet; The specific steps of casting film formation include: producing the cast film using a casting machine, controlling solvent evaporation through multi-stage slow heating (40℃-60℃-80℃-100℃-120℃), with no ventilation below 60℃, simultaneous heating and evaporation from both top and bottom, and hot air circulation after 60℃. This segmented temperature control and hot air circulation significantly reduces defects in the cast film caused by solvent evaporation.

[0062] The specific steps of gradient temperature drying include: First stage: top and bottom heating, temperature 45℃, negative pressure (-2pa to +2pa); Second stage: top and bottom heating, temperature 50℃, negative pressure (-10pa to +2pa); Third stage: hot air heating, temperature 80℃, negative pressure (-5pa to +2pa); Fourth stage: hot air heating, temperature 100℃, negative pressure (-2pa to +5pa).

[0063] The specific steps of degreasing are as follows: Stage 1: Room temperature → 200℃, heating rate 0.5℃ / min; atmosphere: air, flow rate 100mL / min; purpose is to evaporate residual solvent; Phase 2: 200→350℃, heating rate: 0.3℃ / min, hold at 350℃ for 2 hours; the purpose is to decompose and volatilize the dispersant. Stage 3: 350→500℃, heating rate: 0.5℃ / min, hold at 500℃ for 3 hours; the purpose is to decompose the PVB backbone. Stage 4: 500→600℃, heating rate: 1℃ / min, hold at 600℃ for 2 hours; the purpose is to completely remove organic matter.

[0064] S3, the cast film is sintered to obtain the ZTA ceramic substrate.

[0065] The sintering process is as follows: Pre-sintering stage: Heating from 600℃ to 1200℃ at a rate of 3℃ / min in air atmosphere; thereby densifying the film in the early stage and maintaining its shape. Main sintering stage: The temperature is increased to sintering temperature of 1480±5℃ at a heating rate of 2℃ / min, held for 4 hours, and then cooled with the furnace; nitrogen atmosphere.

[0066] Example 7 A ZTA ceramic substrate differs from Example 6 in that the casting slurry of this example comprises the following components by weight: 100 parts ZTA ceramic powder, 0.6 parts sintering aid, 1 part dispersant, 10 parts binder, 2 parts plasticizer, and 55 parts solvent.

[0067] The ZTA ceramic powder was prepared by the method in Example 2. The method for preparing the ZTA ceramic substrate includes the following steps: S1, Prepare casting slurry; add the ZTA ceramic powder and sintering aid of the above formula to the solvent of the dissolving and dispersing agent, disperse at high speed (3000 rpm, 30 min), control the solid content to 72 wt%, and ball mill for 5 h.

[0068] Dissolve the adhesive PVB in an equal mass of toluene (60°C, stirring for 2 hours), add the plasticizer DBP, continue stirring for 1 hour, and cool to room temperature.

[0069] The PVB solution was slowly added to the ball-milled powder slurry, stirred at low speed (200 rpm) for 2 hours, and then degassed under vacuum (vacuum degree -0.08 MPa) for 30 minutes to obtain the casting slurry.

[0070] S2, the casting slurry is cast into a film, dried by gradient temperature increase, and degreased to obtain a cast film sheet; The specific steps of casting film formation include: producing the cast film using a casting machine, controlling solvent evaporation through multi-stage slow heating (40℃-60℃-80℃-100℃-120℃), with no ventilation below 60℃, simultaneous heating and evaporation from both top and bottom, and hot air circulation after 60℃. This segmented temperature control and hot air circulation significantly reduces defects in the cast film caused by solvent evaporation.

[0071] The specific steps of gradient temperature drying include: First stage: top and bottom heating, temperature 40℃, negative pressure (-2pa to +2pa); Second stage: top and bottom heating, temperature 55℃, negative pressure (-10pa to +2pa); Third stage: hot air heating, temperature 80℃, negative pressure (-5pa to +2pa); Fourth stage: hot air heating, temperature 105℃, negative pressure (-2pa to +5pa).

[0072] The specific steps of degreasing are as follows: Stage 1: Room temperature → 200℃, heating rate 0.5℃ / min; atmosphere: air, flow rate 100mL / min; purpose is to evaporate residual solvent; Phase 2: 200→350℃, heating rate: 0.3℃ / min, hold at 350℃ for 2 hours; the purpose is to decompose and volatilize the dispersant. Stage 3: 350→500℃, heating rate: 0.5℃ / min, hold at 500℃ for 3 hours; the purpose is to decompose the PVB backbone. Stage 4: 500→600℃, heating rate: 1℃ / min, hold at 600℃ for 2 hours; the purpose is to completely remove organic matter.

[0073] S3, the cast film is sintered to obtain the ZTA ceramic substrate.

[0074] The sintering process is as follows: Pre-sintering stage: Heating from 600℃ to 1200℃ at a rate of 3℃ / min in air atmosphere; thereby densifying the film in the early stage and maintaining its shape. Main sintering stage: Heating at a rate of 2℃ / min, holding at 1450℃ for 1 hour, heating at 1480℃ for 3 hours, and then cooling with the furnace; nitrogen atmosphere.

[0075] Example 8 A ZTA ceramic substrate differs from Example 6 in that the casting slurry of this example comprises the following components by weight: 100 parts ZTA ceramic powder, 0.6 parts sintering aid, 1 part dispersant, 8 parts binder, 2 parts plasticizer, and 55 parts solvent.

[0076] The ZTA ceramic powder was prepared by the method described in Example 3. The method for preparing the ZTA ceramic substrate includes the following steps: S1, Prepare casting slurry; add the ZTA ceramic powder and sintering aid of the above formula to the solvent of the dissolving and dispersing agent, disperse at high speed (3000 rpm, 30 min), control the solid content to 72 wt%, and ball mill for 5 h.

[0077] Dissolve PVB in an equal mass of toluene (60°C, stirring for 2 hours), add plasticizer DBP, continue stirring for 1 hour, and cool to room temperature.

[0078] The PVB solution was slowly added to the ball-milled powder slurry, stirred at low speed (200 rpm) for 2 hours, and then degassed under vacuum (vacuum degree -0.08 MPa) for 30 minutes to obtain the casting slurry.

[0079] S2, the casting slurry is cast into a film, dried by gradient temperature increase, and degreased to obtain a cast film sheet; The specific steps of casting film formation include: producing the cast film using a casting machine, controlling solvent evaporation through multi-stage slow heating (40℃-60℃-80℃-100℃-120℃), with no ventilation below 60℃, simultaneous heating and evaporation from both top and bottom, and hot air circulation after 60℃. This segmented temperature control and hot air circulation significantly reduces defects in the cast film caused by solvent evaporation.

[0080] The specific steps of gradient temperature drying include: First stage: top and bottom heating, temperature 45℃, negative pressure (-2pa to +2pa); Second stage: top and bottom heating, temperature 50℃, negative pressure (-10pa to +2pa); Third stage: hot air heating, temperature 85℃, negative pressure (-5pa to +2pa); Fourth stage: hot air heating, temperature 100℃, negative pressure (-2pa to +5pa).

[0081] The specific steps of degreasing are as follows: Stage 1: Room temperature → 200℃, heating rate 0.5℃ / min; atmosphere: air, flow rate 100mL / min; purpose is to evaporate residual solvent; Phase 2: 200→350℃, heating rate: 0.3℃ / min, hold at 350℃ for 2 hours; the purpose is to decompose and volatilize the dispersant. Stage 3: 350→500℃, heating rate: 0.5℃ / min, hold at 500℃ for 3 hours; the purpose is to decompose the PVB backbone. Stage 4: 500→600℃, heating rate: 1℃ / min, hold at 600℃ for 2 hours; the purpose is to completely remove organic matter.

[0082] S3, the cast film is sintered to obtain the ZTA ceramic substrate.

[0083] The sintering process is as follows: Pre-sintering stage: Heating from 600℃ to 1200℃ at a rate of 3℃ / min in air atmosphere; thereby densifying the film in the early stage and maintaining its shape. Main sintering stage: heating from 1200℃ to 1400℃ at a rate of 2℃ / min to promote grain growth; heating from 1400℃ to 1500℃ at a rate of 1℃ / min for morphology regularization; holding at 1480℃ for 3 hours, followed by furnace cooling; nitrogen atmosphere.

[0084] Example 9 A ZTA ceramic substrate differs from Example 6 in that the casting slurry of this example comprises the following components by weight: 100 parts ZTA ceramic powder, 0.6 parts sintering aid, 1 part dispersant, 12 parts binder, 2 parts plasticizer, and 55 parts solvent.

[0085] The ZTA ceramic powder was prepared by the method described in Example 4. The method for preparing the ZTA ceramic substrate includes the following steps: S1, Prepare casting slurry; add the ZTA ceramic powder and sintering aid of the above formula to the solvent of the dissolving and dispersing agent, disperse at high speed (3000 rpm, 30 min), control the solid content to 72 wt%, and ball mill for 5 h.

[0086] Dissolve PVB in an equal mass of toluene (60°C, stirring for 2 hours), add plasticizer DBP, continue stirring for 1 hour, and cool to room temperature.

[0087] The PVB solution was slowly added to the ball-milled powder slurry, stirred at low speed (200 rpm) for 2 hours, and then degassed under vacuum (vacuum degree -0.08 MPa) for 30 minutes to obtain the casting slurry.

[0088] S2, the casting slurry is cast into a film, dried by gradient temperature increase, and degreased to obtain a cast film sheet; The specific steps of casting film formation include: producing the cast film using a casting machine, controlling solvent evaporation through multi-stage slow heating (40℃-60℃-80℃-100℃-120℃), with no ventilation below 60℃, simultaneous heating and evaporation from both top and bottom, and hot air circulation after 60℃. This segmented temperature control and hot air circulation significantly reduces defects in the cast film caused by solvent evaporation.

[0089] The specific steps of gradient temperature drying include: First stage: top and bottom heating, temperature 45℃, negative pressure (-2pa to +2pa); Second stage: top and bottom heating, temperature 50℃, negative pressure (-10pa to +2pa); Third stage: hot air heating, temperature 80℃, negative pressure (-5pa to +2pa); Fourth stage: hot air heating, temperature 100℃, negative pressure (-2pa to +5pa).

[0090] The specific steps of degreasing are as follows: Stage 1: Room temperature → 200℃, heating rate 0.5℃ / min; Atmosphere: air, flow rate 100mL / min; The purpose is to evaporate residual solvent. Phase 2: 200→350℃, heating rate: 0.3℃ / min, hold at 350℃ for 2 hours; the purpose is to decompose and volatilize the dispersant. Stage 3: 350→500℃, heating rate: 0.5℃ / min, hold at 500℃ for 3 hours; the purpose is to decompose the PVB backbone. Stage 4: 500→600℃, heating rate: 1℃ / min, hold at 600℃ for 2 hours; the purpose is to completely remove organic matter.

[0091] S3, the cast film is sintered to obtain the ZTA ceramic substrate.

[0092] The sintering process is as follows: Pre-sintering stage: Heating from 600℃ to 1200℃ at a rate of 3℃ / min in air atmosphere; thereby densifying the film in the early stage and maintaining its shape. Main sintering stage: When the temperature is raised from 1200℃ to 1400℃, the heating rate is 2℃ / min, which is the grain growth period; when the temperature is raised from 1400℃ to 1500℃, the heating rate is 1℃ / min, and the temperature is held at 1450℃ for 1 hour and at 1480℃ for 3 hours, which is the morphology regularization period, and the furnace is cooled; nitrogen atmosphere.

[0093] Example 10 A ZTA ceramic substrate differs from Example 6 in that the casting slurry of this example comprises the following components by weight: 100 parts ZTA ceramic powder, 0.6 parts sintering aid, 1 part dispersant, 10 parts binder, 2 parts plasticizer, and 55 parts solvent.

[0094] The ZTA ceramic powder was prepared by the method in Example 5. The method for preparing the ZTA ceramic substrate includes the following steps: S1, Prepare casting slurry; add the ZTA ceramic powder and sintering aid of the above formula to the solvent of the dissolving and dispersing agent, disperse at high speed (3000 rpm, 30 min), control the solid content to 72 wt%, and ball mill for 5 h.

[0095] The remaining steps are the same as in Example 6, and will not be repeated here.

[0096] Example 11 A ZTA ceramic substrate differs from Example 6 in that the casting slurry of this example comprises the following components by weight: 100 parts ZTA ceramic powder, 0.6 parts sintering aid, 1 part dispersant, 5 parts binder, 2 parts plasticizer, and 55 parts solvent.

[0097] The dispersant was modified as follows: 10 ml of trimethyl phosphate and 15 ml of arginine were added to 500 ml of polyethylene glycol dispersant, and the mixture was allowed to react fully at 70°C and pH 10. The product solution was then placed in a dialysis bag with a molecular weight cutoff (MWCO) of 100-150 g / mol. Deionized water was used as the dialysis solution, and the dialysis bag containing the sample was placed in the dialysis solution, ensuring that the bag was completely submerged. Dialysis was performed at room temperature for 4 hours to remove any ungrafted trimethyl phosphate from the product solution. HCl gas was then introduced into the product solution to precipitate the amino acids as hydrochloride. After filtering the precipitated particles through a sieve, a high-purity modified dispersant was obtained.

[0098] This embodiment uses a slurry with a highly efficient modified dispersant. Its numerous end-group functional groups interact effectively with the particles, preventing particle aggregation. Simultaneously, the localized rigid network constructed by the dispersant inhibits particle displacement and reduces the initiation of microcracks in the early drying stage. A stable three-dimensional network structure can be built with relatively low binder content, and the cast film exhibits excellent film-forming properties. Furthermore, reducing the amount of binder significantly increases the drying speed of the cast film and substantially reduces subsequent debinding time, thereby improving density.

[0099] The results showed that the green drying crack rate of ZTA ceramic substrates from one kiln (200 pieces) was 0%, and the density of randomly selected samples reached 99.85%.

[0100] Comparative Example 1 A ZTA ceramic substrate differs from Example 9 in that the order in which the aluminum precursor solution and the zirconium precursor solution are added is different in the preparation method of the ZTA ceramic powder in this comparative example. Specifically, the preparation method of the ZTA ceramic powder in this comparative example includes the following steps: S1, Dissolve 10.2g of aluminum isopropoxide in 100ml of anhydrous ethanol. Pre-dissolve 0.408g of polyether alcohol dispersant (PEG-400) in 10ml of ethanol and add it to the solution. Stir for 20min to ensure uniform mixing. Add 0.3g of citric acid and stir until uniform. Adjust the pH to 3.0±0.2 with dilute nitric acid to obtain the aluminum precursor solution. S2, dissolve 1.35g of zirconium n-butoxide in 50ml of anhydrous ethanol, stir well, add 0.1g of citric acid and continue stirring until well mixed to obtain a zirconium precursor solution. S3, under continuous stirring, the aluminum precursor solution from step S1 is added dropwise to the zirconium precursor solution from step S2. The dropwise addition time is 30 min, the temperature is 25℃, the stirring speed is 300 rpm, and after the dropwise addition is completed, stirring is continued for 15 min to obtain an aluminum-zirconium mixture. The remaining steps are the same as the preparation method of ZTA ceramic powder in Example 9, and will not be repeated here.

[0101] Comparative Example 2 A ZTA ceramic substrate differs from Example 9 in that the step of adding a polyether alcohol dispersant in the preparation method of the ZTA ceramic powder in this comparative example is different. Specifically, the preparation method of the ZTA ceramic powder in this comparative example includes the following steps: S1, Dissolve 10.2g of aluminum isopropoxide in 100ml of anhydrous ethanol, add 0.3g of citric acid and stir well, adjust the pH to 3.0±0.2 with dilute nitric acid to obtain an aluminum precursor solution; S2, dissolve 1.35g of zirconium n-butoxide in 50ml of anhydrous ethanol, stir well, add 0.1g of citric acid and continue stirring until well mixed to obtain a zirconium precursor solution. S3, under continuous stirring, the zirconium precursor solution from step S2 is added dropwise to the aluminum precursor solution from step S1. The dropwise addition time is 30 min, the temperature is 25℃, and the stirring speed is 300 rpm. After the dropwise addition is completed, stirring is continued for 15 min. Separately, 0.408 g of polyether alcohol dispersant (PEG-400) is pre-dissolved in 10 ml of ethanol and then added to the mixed solution after dropwise addition. The mixture is stirred for 20 min to ensure uniform stirring, thus obtaining an aluminum-zirconium mixture. The remaining steps are the same as the preparation method of ZTA ceramic powder in Example 9, and will not be repeated here.

[0102] Comparative Example 3 A ZTA ceramic substrate differs from Example 9 in that: in the preparation method of the ZTA ceramic powder in this comparative example, conventional oven drying (100°C, 44h) is used instead of freeze drying.

[0103] Performance testing 1. Morphological characterization of ZTA ceramic powder SEM image of ZTA ceramic powder prepared in Example 1 is shown below. Figure 1 and Figure 2As shown, its microstructure exhibits polygonal or hexagonal grains, indicating that Al2O3 and ZrO2 underwent ordered crystal growth during sintering, with grain boundary energy tending to be minimized (the principle of minimum energy), consistent with the symmetry of the hexagonal crystal system (space group R-3c) of α-Al2O3 or the tetragonal crystal system of t-ZrO2. This is beneficial for improving grain boundary strength and hardness, and the uniform grain boundaries can reduce stress concentration. At the same time, the uniform distribution of ZrO2 within the grains can enhance phase transformation toughening. In addition, the grain symmetry reduces thermal expansion mismatch and improves thermal stability, thereby further enhancing the performance of the ZTA substrate.

[0104] 2. Performance testing of ZTA ceramic substrates The ZTA ceramic substrates of Examples 6-11 and Comparative Examples 1-3 were subjected to the following performance tests, and the results are shown in Table 1.

[0105] 1. Density test method: The density is calculated by measuring the weight of the sample in air and when immersed in a liquid using Archimedes' method. 2. Test method for three-point bending strength: The test is conducted using a universal testing machine in accordance with the method of standard GB / T 6569-2006. The lower support span of the three-point bending fixture is 30mm.

[0106] 3. Thermal conductivity: The thermal diffusivity is measured by laser flare method, and then the thermal conductivity is calculated. Test temperature: room temperature.

[0107] 4. Insulation strength: Tested using a withstand voltage tester.

[0108] 5. Hardness: Tested using a Vickers hardness tester.

[0109] Table 1

[0110] The results show that the density of the ZTA ceramic substrate of the present invention reaches 3.97 g / cm³. 3 The above specifications include a three-point bending strength of 758 MPa or higher, a thermal conductivity of 27.1 W / (mK) or higher, an insulation strength of 35 kV / mm or higher, and a Vickers hardness of 17 GPa or higher.

[0111] Compared to Example 9, in Comparative Example 1, the aluminum precursor solution was added dropwise to the zirconium precursor solution, resulting in limited crystal growth and a decrease in the density, three-point bending strength, thermal conductivity, insulation strength, and Vickers hardness of the ZTA ceramic substrate. In Comparative Example 2, the two precursor solutions were mixed before a dispersant was added, resulting in uniform particle size and poor dispersibility. Consequently, the strength, thermal conductivity, and insulation strength of the prepared ZTA ceramic substrate were significantly reduced.

[0112] Compared to Comparative Example 3, which was dried in a conventional oven (100°C, 44h), the ZTA ceramic substrate of Example 9, which was freeze-dried, exhibited higher density, three-point bending strength, thermal conductivity, insulation strength, and Vickers hardness. The results indicate that freeze-drying avoids particle collapse or cracking caused by capillary forces in conventional hot drying; it also allows the Al(OH)3 and Zr(OH)4 precursors in the ZTA sol to form spherical or polyhedral particles with smooth surfaces, which is beneficial for obtaining polygonal grains during subsequent sintering. Furthermore, low-temperature freezing (-50°C) inhibits the early transformation of hydroxyl compounds in the sol to the crystalline phase, and the sublimation process avoids high-temperature induced crystallization, thus preserving the amorphous structure. The amorphous state provides the driving force for phase transformation during sintering, improving the intracrystalline ZrO2 distribution.

[0113] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing ZTA ceramic powder, characterized in that, Includes the following steps: S1, dissolve aluminum alkoxide in an organic solvent, add polyether alcohol dispersant and stir until homogeneous, adjust pH to 2.8-3.2 to obtain aluminum precursor solution; S2, dissolve zirconium alkoxide in an organic solvent to prepare a zirconium precursor solution; S3, the zirconium precursor solution from step S2 is added dropwise to the aluminum precursor solution from step S1, wherein the molar ratio of Al and Zr in the aluminum precursor and zirconium precursor is (5-20):1, to obtain an aluminum-zirconium mixture. S4, add water to the aluminum-zirconium mixture, heat to carry out hydrolysis reaction, cool and stir to form a gel, freeze dry, calcine to obtain the ZTA ceramic powder.

2. The method for preparing ZTA ceramic powder according to claim 1, characterized in that, In step S1, the polyether alcohol dispersant is polyethylene glycol with an average molecular weight of 200-600 Da; the weight of the polyether alcohol dispersant accounts for 3-6 wt% of the weight of the aluminum alkoxide.

3. The method for preparing ZTA ceramic powder according to claim 1, characterized in that, A crystallization inhibitor is also added to the aluminum precursor solution and / or zirconium precursor solution, and the concentration of the crystallization inhibitor is 0.1-0.5 g / mL.

4. The method for preparing ZTA ceramic powder according to claim 1, characterized in that, In step S3, the dropping rate of the zirconium precursor solution into the zirconium precursor solution aluminum precursor solution is 1.3-2.6 mL / min.

5. The method for preparing ZTA ceramic powder according to claim 1, characterized in that, In step S4, the hydrolysis reaction is carried out at a temperature of 70-80℃, a pH value of 2.8-3.2, and a reaction time of 3-5 hours.

6. The method for preparing ZTA ceramic powder according to claim 1, characterized in that, In step S4, the calcination is carried out in stages. The stage calcination conditions are as follows: first stage calcination: temperature 300-500℃, holding time 0.5-2h; second stage calcination: temperature 700-750℃, holding time 2.5-4h; third stage calcination: temperature 800-850℃, holding time 0.5-2h.

7. A ZTA ceramic powder, characterized in that, It is prepared by the method for preparing ZTA ceramic powder according to any one of claims 1-6.

8. The ZTA ceramic powder according to claim 7, characterized in that, The D50 particle size of the ZTA ceramic powder is 30-120 nm.

9. A ZTA ceramic substrate, characterized in that, The raw materials include the following components by weight: 100 parts ZTA ceramic powder, 1-3 parts dispersant, 3-12 parts binder, 1-4 parts plasticizer, and 50-65 parts solvent; the ZTA ceramic powder is as described in claim 7.

10. The ZTA ceramic substrate according to claim 9, characterized in that, The dispersant is formed by the grafting reaction of the main dispersant with trimethyl phosphate and amino acids.

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