Zirconium-free, radioactivity-free and acid and alkali-resistant optical porcelain plate

Abstract

The invention belongs to the technical field of ceramic materials, and discloses a zirconium-free, radioactivity-free and acid and alkali-resistant optical porcelain plate. The aluminum nitride quantum dot / graphene composite material is prepared from the following raw materials in parts by mass: 1.2 to 1.5 parts of polyethylene glycol octylphenol ether, 100 parts of aluminum nitride powder, 80 to 100 parts of boron-doped aluminum nitride quantum dot dispersion liquid, 0.3 to 0.8 part of modified graphene oxide, 5 to 6 parts of yttrium oxide, 3 to 5 parts of spodumene, 0.3 to 0.4 part of oleic acid, 2 to 3 parts of polyvinyl butyral and 2 to 3 parts of dibutyl phthalate. The modified graphene oxide is graphene oxide modified by polysilazane. The introduction of the boron-doped aluminum nitride quantum dots, the modified graphene oxide, the yttrium oxide and other components effectively improves the optical properties, acid and alkali resistance, thermal conductivity and bending strength of the zirconium-free and radioactivity-free optical porcelain plate. Therefore, the method has a wider application prospect.

Description

Technical Field

[0001] This invention belongs to the field of ceramic materials technology, specifically relating to an optical ceramic plate that is zirconium-free, non-radioactive, and resistant to acids and alkalis. Background Technology

[0002] As an optical window material, transparent ceramics offer higher operating temperatures, longer service life, superior observation and detection accuracy, and better cost-effectiveness. Protective windows made from them have significant advantages: they are less prone to scratches under harsh conditions, ensuring surface integrity; and they significantly enhance protective capabilities at the same thickness, making them suitable for complex environments. Therefore, they are widely used in observation windows for high-temperature and high-pressure equipment, gas detector windows, high-temperature boiler level gauges, product barcode scanner windows, downhole detection sensors, and various protective lenses. Zirconium-free and non-radioactive optical ceramic plates, by avoiding the high cost of zirconium raw materials and the safety risks of radioactive impurities, are also used in observation windows for medical high-temperature sterilization equipment and high-temperature monitoring windows for food production lines, further expanding the application range of transparent ceramics.

[0003] However, in practical applications, zirconium-free and non-radioactive optical ceramic plates still have several performance shortcomings: First, their optical performance is poor and lacks stability. At room temperature, their transmittance is insufficient to meet high-precision requirements, and their optical performance deteriorates significantly at high temperatures. Simultaneously, high haze values ​​lead to blurred observation images, affecting detection accuracy. Second, their acid and alkali resistance is weak. In corrosive environments containing acid and alkali media, such as chemical plants and underground mines, the surface is prone to chemical corrosion, which exacerbates optical performance degradation, shortens service life, and increases maintenance costs. Third, their thermal conductivity is poor. During high-temperature equipment operation, temperature gradients easily form within the material, potentially causing stress cracking, compromising structural stability, and interfering with the equipment's temperature field balance, indirectly reducing reliability. Furthermore, various performance characteristics are coupled and constrained. For example, optimizing the process to improve transmittance often results in a decrease in bending strength; single improvements cannot simultaneously address multiple indicators, increasing the technical difficulty of comprehensively improving performance. Therefore, the optical performance, acid and alkali resistance, thermal conductivity, and bending strength of existing zirconium-free and non-radioactive optical ceramic plates still need improvement. Summary of the Invention

[0004] To address the shortcomings mentioned in the background section, the present invention aims to provide a zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate, thereby solving the following technical problems: Existing zirconium-free and non-radioactive optical ceramic plates still suffer from poor optical properties, acid and alkali resistance, thermal conductivity, and bending strength.

[0005] The objective of this invention can be achieved through the following technical solutions: A zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate comprises the following raw materials in parts by weight: 1.2-1.5 parts polyethylene glycol octylphenyl ether, 100 parts aluminum nitride powder, 80-100 parts boron-doped aluminum nitride quantum dot dispersion, 0.3-0.8 parts modified graphene oxide, 5-6 parts yttrium oxide, 3-5 parts spodumene, 0.3-0.4 parts oleic acid, 2-3 parts polyvinyl butyral, and 2-3 parts dibutyl phthalate; The boron-doped aluminum nitride quantum dot dispersion is a precursor sol made of aluminum nitrate and boric acid, which is prepared by drying and calcination under an ammonia atmosphere. The modified graphene oxide is graphene oxide modified with polysilazane.

[0006] Preferably, the preparation method of the boron-doped aluminum nitride quantum dot dispersion is as follows: A1: Add aluminum nitrate to anhydrous ethanol and stir at 40°C for 60-70 min. Then add boric acid and stir at 40°C for 60-80 min. Next, add polyethylene glycol and stir for 30-40 min. Adjust the pH to 5.5-6 with triethylamine and stir at 150 r / min at 40°C for 2-2.5 h. Seal and let stand for 12-15 h to obtain the precursor sol. A2: Pour the precursor sol into a polytetrafluoroethylene mold and dry it at 45℃ and 30%-40% relative humidity for 24-30h. After grinding, spread it in a boron nitride crucible for calcination. Then add it to anhydrous ethanol and ultrasonically disperse it for 30-50min. Then centrifuge it at 8000r / min for 15min to remove the precipitate. Centrifuge it at 10000r / min for 10min. Take the supernatant and concentrate it to a concentration of 10mg / mL at 40℃ and vacuum degree -0.09MPa to obtain boron-doped aluminum nitride quantum dot dispersion.

[0007] Preferably, the ratio of anhydrous ethanol, aluminum nitrate, boric acid, and polyethylene glycol in A1 is 90-100 mL: 5 g: 0.12 g: 0.2 g.

[0008] Preferably, the calcination treatment described in A2 is as follows: first, purge with high-purity ammonia gas at a flow rate of 150 mL / min for 30-40 min, then raise the temperature to 300℃ at a rate of 5℃ / min and hold for 2-2.5 h, then raise the temperature to 800℃ at a rate of 8℃ / min and hold for 3-3.5 h, then raise the temperature to 1200-1300℃ at a rate of 10℃ / min and hold for 4-6 h, and continue purging with ammonia gas until the furnace temperature naturally cools to room temperature.

[0009] Preferably, the modified graphene oxide is prepared by the following method: Polysilazane was added to anhydrous tetrahydrofuran and stirred for 30-50 min. Then it was dropped into an anhydrous tetrahydrofuran dispersion of graphene oxide. The mixture was heated to 50-55℃ and stirred for 9-10 h under a nitrogen atmosphere. After cooling to room temperature, it was centrifuged and the precipitate was washed 2-3 times with anhydrous tetrahydrofuran and then 2-3 times with anhydrous ethanol. After vacuum drying at 55℃ and -0.095 MPa for 12-15 h, it was ground to obtain modified graphene oxide.

[0010] Preferably, the ratio of the anhydrous tetrahydrofuran, polysilazane, and graphene oxide anhydrous tetrahydrofuran dispersion is 10-12 mL: 2 g: 50 mL. The concentration of the anhydrous tetrahydrofuran dispersion of graphene oxide is 0.5 mg / mL.

[0011] Preferably, the method for preparing the zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate is as follows: S1: Add N-methylpyrrolidone to anhydrous ethanol and stir until homogeneous. Then add polyethylene glycol octylphenyl ether and stir for 30-40 min. Next, add aluminum nitride powder and stir for 30-40 min. Then add boron-doped aluminum nitride quantum dot dispersion, modified graphene oxide, yttrium oxide, and spodumene and stir for 60-90 min. Finally, add oleic acid and mill with a ball-to-particle ratio of 5-6:1, using boron nitride balls with a diameter of 5 mm as the milling media, and a rotation speed of 300-350 r / min. The ball milling process involves 12-16 hours of ball milling, with a stop every 4 hours for ultrasonic dispersion for 20-30 minutes. After passing through a 300-350 mesh sieve, polyvinyl butyral is added and stirred for 60-70 minutes. Finally, dibutyl phthalate is added and stirred for 2-2.5 hours. Under a vacuum of -0.095 MPa, the mixture is stirred and degassed at 20-30 r / min for 60-90 minutes. The viscosity is then adjusted to 400-600 mPa·s to obtain the slurry. S2: Pour the slurry into the casting machine trough and cast it at a speed of 5-8 cm / min to form a continuous green film with a thickness of 80-120 μm on the PET film. Then, dry it at 30℃ for 1-1.5 h and then at 60℃ for 2-3 h. After cutting the green film with a laser cutter, put it into a high-purity alumina crucible for pre-firing treatment to obtain a pre-fired green film. S3: Place the pre-fired green body into a graphite mold, line the inner wall of the mold with a boron nitride coating, and lay graphite paper on the top and bottom of the green body for heat conduction. Then, perform sintering treatment, and then mechanically grind it with diamond polishing paste until the surface particle size is 0.5μm. Then, polish it with colloidal silica polishing liquid at a polishing pressure of 0.15MPa and a rotation speed of 80r / min for 30-40min. Ultrasonic cleaning with anhydrous ethanol for 15-20min, vacuum drying at 80℃ for 2-3h, and trim the edges of the ceramic plate with a laser cutting machine to obtain a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate.

[0012] Preferably, the ratio of anhydrous ethanol, N-methylpyrrolidone, polyethylene glycol octylphenyl ether, aluminum nitride powder, boron-doped aluminum nitride quantum dot dispersion, modified graphene oxide, yttrium oxide, spodumene, oleic acid, polyvinyl butyral, and dibutyl phthalate in S1 is 30mL:20mL:1.2-1.5g:100g:80-100g:0.3-0.8g:5-6g:3-5g:0.3-0.4g:2-3g:2-3g.

[0013] Preferably, the pre-calcination treatment in S2 is as follows: under a nitrogen atmosphere with a flow rate of 100 mL / min, the temperature is first raised to 350°C at a heating rate of 5°C / min and held for 1 hour, then raised to 450°C at a heating rate of 3°C / min and held for 2-2.5 hours, and finally cooled to room temperature with the furnace.

[0014] Preferably, the sintering process described in S3 is as follows: first, the temperature is increased to 800°C at a flow rate of 10°C / min under a nitrogen atmosphere with a flow rate of 200 mL / min and a furnace pressure of 0.1 MPa; then, the temperature is increased to 1600°C at a pressure of 15 MPa at a flow rate of 5°C / min; then, the temperature is increased to 1850°C at a flow rate of 3°C / min while the pressure is gradually increased to 40-50 MPa; the temperature is held at 1850°C and 40-50 MPa for 30-40 min; then, the temperature is decreased to 800°C at a flow rate of 120°C / min; and finally, the furnace is cooled.

[0015] The beneficial effects of this invention are: This invention provides a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate. The invention effectively improves the light transmittance, refractive index stability, acid and alkali resistance, thermal conductivity, and bending strength of the zirconium-free and non-radioactive optical ceramic plate through the following methods, and reduces its haze.

[0016] (1) The boron-doped aluminum nitride quantum dots of the present invention can improve performance through dispersion strengthening and crack deflection mechanisms, effectively pinning dislocations and preventing crack propagation; when a crack encounters a quantum dot, the path will be deflected, consuming more energy, thereby improving the bending strength of the ceramic plate. Boron doping can adjust the band structure of aluminum nitride, reduce light absorption caused by impurity energy levels, and thus improve light transmittance. The boron-doped aluminum nitride quantum dots have a high lattice matching degree with the aluminum nitride matrix and a small difference in thermal expansion coefficient. When the temperature changes, the volume shrinkage and expansion trends of the two are consistent, which can reduce the refractive index fluctuation caused by interfacial stress, thereby improving the temperature stability of refractive index. A small amount of hydroxyl or organic ligands may remain on the surface of the quantum dots, which can form a dense interfacial layer with the matrix, hindering the penetration of hydrogen ions and hydroxide ions in acid and alkali solutions; at the same time, boron doping can fill the lattice defects of aluminum nitride, reduce the reaction sites of corrosive media, and thus enhance acid and alkali resistance. Boron-doped aluminum nitride quantum dots have a high lattice matching degree with the aluminum nitride matrix, which can act as a thermally conductive link to reduce interfacial phonon scattering; at the same time, the dispersed distribution of quantum dots can fill the micropores in the matrix, and in conjunction with the high thermal conductivity of the aluminum nitride matrix itself, further improve the overall thermal conductivity of the ceramic plate.

[0017] (2) The two-dimensional sheet structure of the modified graphene oxide of this invention can form a skeleton support in the ceramic matrix, transfer stress through interfacial covalent bonds, and prevent crack propagation; at the same time, the flexible characteristics of the sheets can absorb impact energy, reduce brittle fracture, and significantly improve bending strength. After the graphene oxide sheets are modified with polysilazane, the difference in refractive index between them and the aluminum nitride matrix is ​​reduced, and they are uniformly dispersed at low dosages, which can reduce interfacial scattering and maintain the light transmittance at a high level. The modified graphene oxide has a low coefficient of thermal expansion, and the silicon nitrogen groups enhance the interfacial bonding force, which can reduce interfacial stress and microcracks during temperature changes, thereby reducing the fluctuation range of refractive index with temperature and improving the temperature stability of refractive index. The sheets of modified graphene oxide can form a physical barrier to prevent the penetration of acid and alkali solutions; at the same time, the surface silicon nitrogen groups react with aluminum nitride to form a dense Si-Al-ON composite layer, which reduces grain boundary defects, inhibits the erosion of the matrix by acids and alkalis, and significantly improves acid and alkali resistance. Graphene has extremely high thermal conductivity. Uniformly dispersed modified graphene oxide can form thermally conductive pathways in an aluminum nitride matrix, promoting phonon transfer and improving thermal conductivity.

[0018] (3) The yttrium oxide of this invention can react with the oxide layer on the surface of aluminum nitride to form a low-melting-point yttrium aluminum oxide glass phase, which fills the interparticle gaps during sintering, promotes diffusion sintering, and significantly reduces the porosity of the ceramic. The reduction in porosity can reduce stress concentration points and improve flexural strength. An appropriate amount of yttrium oxide can significantly improve light transmittance by eliminating porosity. The thermal expansion coefficients of the solid solution formed by yttrium oxide and aluminum nitride and the yttrium aluminum oxide glass phase are more compatible with those of aluminum nitride, which can reduce microstructure fluctuations caused by thermal stress during temperature changes. At the same time, the glass phase can inhibit abnormal growth of aluminum nitride grains, reduce the inhomogeneity of refractive index caused by grain size differences, and significantly reduce the amplitude of refractive index fluctuations in a wide temperature range. Aluminum nitride itself is prone to react with strong acids and strong bases, while the yttrium aluminum oxide phase formed by the reaction of yttrium oxide has higher chemical stability and can form a protective layer on the surface of aluminum nitride grains, hindering the penetration of corrosive media. At the same time, densification reduces the pore channels for the diffusion of corrosive media, thus improving acid and alkali resistance. Yttrium oxide can remove oxygen impurities from the aluminum nitride lattice and promote densification, significantly improving the thermal conductivity of the ceramic plate. After densification is promoted by yttrium oxide, the internal porosity of the ceramic is greatly reduced, and the uniformly distributed yttrium aluminum oxide phase particles are small in size, which weakens the scattering of visible light and reduces haze.

[0019] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, the following information pertains to some of the raw materials used in the following embodiments and comparative examples of this invention: Polyethylene glycol (PEG-2000) was purchased from Shanghai Huzheng Biotechnology Co., Ltd., item number: Hhzy-2461; polysilazane was purchased from Shanghai Yuanye Biotechnology Co., Ltd., item number: T21989-10g; polyethylene glycol octylphenyl ether was purchased from Shanghai Lianmai Bioengineering Co., Ltd., item number: LM80089C; polyvinyl butyral was purchased from Shanghai Yuanye Biotechnology Co., Ltd., item number: S30198-500g.

[0022] Example 1: A method for preparing a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate is as follows: S1: Add 5g of aluminum nitrate to 90mL of anhydrous ethanol and stir at 40℃ for 60min. Then add 0.12g of boric acid and stir at 40℃ for 60min. Then add 0.2g of polyethylene glycol and stir for 30min. Adjust the pH to 5.5 with triethylamine and stir at 150r / min at 40℃ for 2h. Seal and let stand for 12h to obtain the precursor sol. S2: The precursor sol was poured into a polytetrafluoroethylene mold and dried at 45°C and 30% relative humidity for 24 hours. After grinding, it was spread in a boron nitride crucible and placed in a tube furnace. It was purged with high-purity ammonia gas (99.999% purity) at a flow rate of 150 mL / min for 30 minutes. Then, the temperature was increased to 300°C at a rate of 5°C / min and held for 2 hours. Next, the temperature was increased to 800°C at a rate of 8°C / min and held for 3 hours. Finally, the temperature was increased to 10°C / min. The temperature was raised to 1200℃ and held for 6 hours. Ammonia gas was purged until the furnace temperature naturally cooled to room temperature. Finally, the mixture was added to 20 mL of anhydrous ethanol and ultrasonically dispersed for 30 min. Then, it was centrifuged at 8000 r / min for 15 min to remove the precipitate. After centrifugation at 10000 r / min for 10 min, the supernatant was taken and concentrated to a concentration of 10 mg / mL under 40℃ and vacuum of -0.09 MPa to obtain boron-doped aluminum nitride quantum dot dispersion. S3: Add 2g of polysilazane to 10mL of anhydrous tetrahydrofuran and stir for 30min. Then drop it into 50mL of anhydrous tetrahydrofuran dispersion of graphene oxide with a concentration of 0.5mg / mL and heat to 50℃ under nitrogen atmosphere and stir for 9h. After cooling to room temperature, centrifuge and wash the precipitate twice with anhydrous tetrahydrofuran and then twice with anhydrous ethanol. After vacuum drying at 55℃ and -0.095MPa for 12h, grind to obtain modified graphene oxide. S4: Add 20 mL of anhydrous ethanol to 30 mL of anhydrous ethanol. N-methylpyrrolidone was stirred until homogeneous. Then, 1.2g of polyethylene glycol octylphenyl ether was added and stirred for 30min. Next, 100g of aluminum nitride powder was added and stirred for 30min. Then, 80mL of boron-doped aluminum nitride quantum dot dispersion, 0.3g of modified graphene oxide, 5g of yttrium oxide, and 3g of spodumene were added and stirred for 60min. Subsequently, 0.3g of oleic acid was added and ball milling was performed with a ball-to-material ratio of 5:1, using boron nitride balls with a diameter of 5mm, a rotation speed of 300r / min, and a ball milling time of 12h, with a stop every 4h for ultrasonic dispersion for 20min. After passing through a 300-mesh sieve, 2g of polyvinyl butyral was added and stirred for 60min. Finally, 2g of dibutyl phthalate was added and stirred for 2h. Under vacuum of -0.095MPa, the mixture was stirred and degassed at 20r / min for 60min and the viscosity was adjusted to 400mPa·s to obtain the slurry. S5: Pour the slurry into the casting machine trough and cast it at a speed of 8 cm / min to form a continuous green film with a thickness of 80 μm on the PET film. Then, dry it at 30℃ for 1 h and then at 60℃ for 2 h. After cutting the green film with a laser cutter, place it in a high-purity alumina crucible. Separate the green films with boron nitride sheets. In a nitrogen atmosphere (purity of 99.999%) with a flow rate of 100 mL / min, first heat the film to 350℃ at a heating rate of 5℃ / min and hold it for 1 h, then heat it to 450℃ at a heating rate of 3℃ / min and hold it for 2 h. Let it cool naturally to room temperature to obtain the pre-fired green film. S6: Place the pre-fired green body into a graphite mold. The inner wall of the mold is lined with a boron nitride coating. Graphite paper is laid on top and bottom of the green body for heat conduction. Then, under a nitrogen atmosphere (99.999% purity) with a flow rate of 200 mL / min and an internal pressure of 0.1 MPa, the temperature is increased to 800℃ at 10℃ / min. Next, the temperature is increased to 1600℃ at 5℃ / min under a pressure of 15 MPa. Then, the temperature is increased to 1850℃ while gradually increasing the pressure to 40 MPa at 3℃ / min. After holding at 40 MPa for 30 min, the temperature was lowered to 800℃ at 120℃ / min. Finally, the plate was cooled in the furnace, mechanically ground with diamond polishing paste to a particle size of 0.5 μm, polished with colloidal silica polishing liquid at a polishing pressure of 0.15 MPa and a rotation speed of 80 r / min for 30 min, ultrasonically cleaned in anhydrous ethanol for 15 min, vacuum dried at 80℃ for 2 h, and the edges of the ceramic plate were trimmed with a laser cutting machine to obtain a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate.

[0023] Example 2: A method for preparing a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate is as follows: S1: Add 5g of aluminum nitrate to 95mL of anhydrous ethanol and stir at 40℃ for 65min. Then add 0.12g of boric acid and stir at 40℃ for 70min. Then add 0.2g of polyethylene glycol and stir for 35min. Adjust the pH to 5.8 with triethylamine and stir at 150r / min at 40℃ for 2.2h. Seal and let stand for 14h to obtain the precursor sol. S2: The precursor sol was poured into a polytetrafluoroethylene mold and dried at 45°C and 35% relative humidity for 27 hours. After grinding, it was spread in a boron nitride crucible and placed in a tube furnace. It was purged with high-purity ammonia gas (99.999% purity) at a flow rate of 150 mL / min for 35 minutes. Then, the temperature was increased to 300°C at a rate of 5°C / min and held for 2.2 hours. Then, the temperature was increased to 800°C at a rate of 8°C / min and held for 3.2 hours. Finally, the temperature was increased at a rate of 10°C / min. The temperature was raised to 1250℃ and held for 5 hours. Ammonia gas was used to purge the furnace until the temperature naturally cooled to room temperature. Finally, the mixture was added to 25 mL of anhydrous ethanol and ultrasonically dispersed for 40 min. Then, it was centrifuged at 8000 r / min for 15 min to remove the precipitate. After centrifugation at 10000 r / min for 10 min, the supernatant was collected and concentrated to a concentration of 10 mg / mL at 40℃ and a vacuum of -0.09 MPa to obtain a boron-doped aluminum nitride quantum dot dispersion. S3: Add 2g of polysilazane to 11mL of anhydrous tetrahydrofuran and stir for 40min. Then drop it into 50mL of anhydrous tetrahydrofuran dispersion of graphene oxide with a concentration of 0.5mg / mL and heat to 53℃ under nitrogen atmosphere and stir for 9.5h. After cooling to room temperature, centrifuge and wash the precipitate three times with anhydrous tetrahydrofuran and then three times with anhydrous ethanol. After vacuum drying at 55℃ and -0.095MPa for 14h, grind to obtain modified graphene oxide. S4: Add 20 mL of anhydrous ethanol to 30 mL of anhydrous ethanol. N-methylpyrrolidone was stirred until homogeneous. Then, 1.4 g of polyethylene glycol octylphenyl ether was added and stirred for 35 min. Next, 100 g of aluminum nitride powder was added and stirred for 35 min. Then, 90 mL of boron-doped aluminum nitride quantum dot dispersion, 0.5 g of modified graphene oxide, 5.5 g of yttrium oxide, and 4 g of spodumene were added and stirred for 75 min. Subsequently, 0.35 g of oleic acid was added and ball milling was performed with a ball-to-material ratio of 6:1, using boron nitride balls with a diameter of 5 mm as the milling medium, a rotation speed of 330 r / min, and a milling time of 14 h, with ultrasonic dispersion for 25 min every 4 h during the process. After passing through a 325 mesh sieve, 2.5 g of polyvinyl butyral was added and stirred for 65 min. Finally, 2.5 g of dibutyl phthalate was added and stirred for 2.2 h. The mixture was then stirred and degassed at 25 r / min for 75 min under a vacuum of -0.095 MPa and the viscosity was adjusted to 500 mPa·s to obtain the slurry. S5: Pour the slurry into the casting machine trough and cast at a speed of 7 cm / min to form a continuous green film with a thickness of 100 μm on the PET film. Then, dry it at 30℃ for 1.2 h and then at 60℃ for 2.5 h. After cutting the green film with a laser cutter, place it in a high-purity alumina crucible. Separate the green films with boron nitride sheets. In a nitrogen atmosphere (purity of 99.999%) with a flow rate of 100 mL / min, first heat the film to 350℃ at a heating rate of 5℃ / min and hold it for 1 h, then heat it to 450℃ at a heating rate of 3℃ / min and hold it for 2.2 h. Let it cool naturally to room temperature to obtain the pre-fired green film. S6: Place the pre-fired green body into a graphite mold. The inner wall of the mold is lined with a boron nitride coating. Graphite paper is laid on top and bottom of the green body for heat conduction. Then, under a nitrogen atmosphere (purity 99.999%) with a flow rate of 200 mL / min and an internal pressure of 0.1 MPa, the temperature is increased to 800℃ at a rate of 10℃ / min. Then, under a pressure of 15 MPa, the temperature is increased to 1600℃ at a rate of 5℃ / min. Then, while increasing the temperature to 1850℃ at a rate of 3℃ / min, the pressure is gradually increased to 45 MPa. At 1850℃... After holding at 45 MPa for 35 min, the temperature was lowered to 800℃ at 120℃ / min. Finally, the plate was cooled in the furnace and mechanically ground with diamond polishing paste to a particle size of 0.5 μm. It was then polished with colloidal silica polishing slurry at a polishing pressure of 0.15 MPa and a rotation speed of 80 r / min for 35 min. After ultrasonic cleaning in anhydrous ethanol for 18 min, the plate was vacuum dried at 80℃ for 2.5 h. Finally, the edges of the ceramic plate were trimmed with a laser cutting machine to obtain a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate.

[0024] Example 3: A method for preparing a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate is as follows: S1: Add 5g of aluminum nitrate to 100mL of anhydrous ethanol and stir at 40℃ for 70min. Then add 0.12g of boric acid and stir at 40℃ for 80min. Then add 0.2g of polyethylene glycol and stir for 40min. Adjust the pH to 6 with triethylamine and stir at 150r / min at 40℃ for 2.5h. Seal and let stand for 15h to obtain the precursor sol. S2: The precursor sol was poured into a polytetrafluoroethylene mold and dried at 45°C and 40% relative humidity for 30 hours. After grinding, it was spread in a boron nitride crucible and placed in a tube furnace. It was purged with high-purity ammonia gas (99.999% purity) at a flow rate of 150 mL / min for 40 minutes. Then, the temperature was increased to 300°C at a rate of 5°C / min and held for 2.5 hours. Next, the temperature was increased to 800°C at a rate of 8°C / min and held for 3.5 hours. Finally, the temperature was increased at a rate of 10°C / min. The temperature was raised to 1300℃ and held for 4 hours. Ammonia gas was used to purge the furnace until the temperature naturally cooled to room temperature. Finally, the mixture was added to 30 mL of anhydrous ethanol and ultrasonically dispersed for 50 min. Then, it was centrifuged at 8000 r / min for 15 min to remove the precipitate. After centrifugation at 10000 r / min for 10 min, the supernatant was collected and concentrated to a concentration of 10 mg / mL at 40℃ and a vacuum of -0.09 MPa to obtain a boron-doped aluminum nitride quantum dot dispersion. S3: Add 2g of polysilazane to 12mL of anhydrous tetrahydrofuran and stir for 50min. Then drop it into 50mL of anhydrous tetrahydrofuran dispersion of graphene oxide with a concentration of 0.5mg / mL and heat to 55℃ under nitrogen atmosphere and stir for 10h. After cooling to room temperature, centrifuge and wash the precipitate three times with anhydrous tetrahydrofuran and then three times with anhydrous ethanol. After vacuum drying at 55℃ and -0.095MPa for 15h, grind to obtain modified graphene oxide. S4: Add 20 mL of anhydrous ethanol to 30 mL of anhydrous ethanol. N-methylpyrrolidone was stirred until homogeneous. Then, 1.5g of polyethylene glycol octylphenyl ether was added and stirred for 40 min. Next, 100g of aluminum nitride powder was added and stirred for 40 min. Then, 100mL of boron-doped aluminum nitride quantum dot dispersion, 0.8g of modified graphene oxide, 6g of yttrium oxide, and 5g of spodumene were added and stirred for 90 min. Subsequently, 0.4g of oleic acid was added and ball milling was performed with a ball-to-material ratio of 6:1, using boron nitride balls with a diameter of 5mm as the milling medium, a rotation speed of 350r / min, and a milling time of 16h, with ultrasonic dispersion for 30 min every 4h. After passing through a 350-mesh sieve, 3g of polyvinyl butyral was added and stirred for 70 min. Finally, 3g of dibutyl phthalate was added and stirred for 2.5h. Under vacuum of -0.095MPa, the mixture was stirred and degassed at 30r / min for 90 min, and the viscosity was adjusted to 600mPa·s to obtain the slurry. S5: Pour the slurry into the casting machine trough and cast it at a speed of 5 cm / min to form a continuous green film with a thickness of 120 μm on the PET film. Then, dry it at 30℃ for 1.5 h and then at 60℃ for 3 h. After cutting the green film with a laser cutter, place it in a high-purity alumina crucible. Separate the green films with boron nitride sheets. In a nitrogen atmosphere (purity of 99.999%) with a flow rate of 100 mL / min, first heat the film to 350℃ at a heating rate of 5℃ / min and hold it for 1 h, then heat it to 450℃ at a heating rate of 3℃ / min and hold it for 2.5 h. Let it cool naturally to room temperature to obtain the pre-fired green film. S6: Place the pre-fired green body into a graphite mold. The inner wall of the mold is lined with a boron nitride coating. Graphite paper is laid on top and bottom of the green body for heat conduction. Then, under a nitrogen atmosphere (99.999% purity) with a flow rate of 200 mL / min and an internal pressure of 0.1 MPa, the temperature is increased to 800℃ at 10℃ / min. Then, under a pressure of 15 MPa, the temperature is increased to 1600℃ at 5℃ / min. Then, while increasing the temperature to 1850℃ at 3℃ / min, the pressure is gradually increased to 50 MPa. At 1850℃... After holding at 50 MPa for 40 minutes, the temperature was lowered to 800℃ at 120℃ / min. Finally, the plate was cooled in the furnace, mechanically ground with diamond polishing paste to a particle size of 0.5μm, polished with colloidal silica polishing slurry at a polishing pressure of 0.15MPa and a rotation speed of 80r / min for 40 minutes, ultrasonically cleaned in anhydrous ethanol for 20 minutes, vacuum dried at 80℃ for 3 hours, and the edges of the ceramic plate were trimmed with a laser cutting machine to obtain a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate.

[0025] Comparative Example 1: Compared with Example 1, this comparative example only omits the addition of "boron-doped aluminum nitride quantum dot dispersion" during the preparation process of S4. All other steps and parameters are the same, and will not be repeated here. The final product is a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate.

[0026] Comparative Example 2: Compared with Example 1, this comparative example only did not add "modified graphene oxide" in the preparation process of S4. All other steps and parameters were the same, and will not be repeated here. The final product is an optical ceramic plate that is zirconium-free, non-radioactive, and resistant to acids and alkalis.

[0027] Comparative Example 3: Compared with Example 1, this comparative example only did not add "yttrium oxide" in the preparation process of S4. All other steps and parameters were the same, and will not be repeated here. The final product is an optical ceramic plate that is zirconium-free, non-radioactive, and resistant to acids and alkalis.

[0028] Performance testing: Measurement of radioactivity: The radioactivity of the zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plates prepared in Examples 1-3 and Comparative Examples 1-3 of this invention was measured, and the test results showed that all optical ceramic plates were non-radioactive.

[0029] Measurement of transmittance: The transmittance (%) of the zirconium-free, non-radioactive, and acid-alkali-resistant optical ceramic plates prepared in Examples 1-3 and Comparative Examples 1-3 of this invention was measured using a UV-Vis spectrophotometer at a wavelength range of 550 nm and an incident angle of 0°. The test results are shown in Table 1.

[0030] Measurement of haze: The haze (%) of the zirconium-free, non-radioactive, acid and alkali-resistant optical ceramic plates prepared in Examples 1-3 and Comparative Examples 1-3 of this invention was measured using a haze meter. The test results are shown in Table 1.

[0031] Stability determination: The refractive index change rate ( / ℃) of the zirconium-free, non-radioactive, acid and alkali-resistant optical ceramic plates prepared in Examples 1-3 and Comparative Examples 1-3 of this invention in the range of -50℃ to 200℃ was measured using an Abbe refractometer. The test results are shown in Table 1.

[0032] Determination of acid and alkali resistance: The mass loss rate (%) of the zirconium-free, non-radioactive, acid and alkali-resistant optical ceramic plates prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention was determined after immersion in a 5% hydrochloric acid or sodium hydroxide solution at room temperature for 24 hours. The test results are shown in Table 1.

[0033] Determination of thermal conductivity: Referring to GB / T 22588-2008 standard, the thermal conductivity (W / m·K) of the zirconium-free, non-radioactive, acid and alkali-resistant optical ceramic plates prepared in Examples 1-3 and Comparative Examples 1-3 of this invention was measured using a laser flare apparatus. The test results are shown in Table 1.

[0034] Determination of flexural strength: Referring to GB / T 6569-2006 standard, the flexural strength (MPa) of the zirconium-free, non-radioactive, acid and alkali-resistant optical ceramic plates prepared in Examples 1-3 and Comparative Examples 1-3 of this invention was determined using a universal testing machine at a loading rate of 0.5 mm / min. The test results are shown in Table 1.

[0035] Table 1: Basic performance test results of Examples 1-3 and Comparative Examples 1-3

[0036] Data Analysis: As can be seen from Table 1, the zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plates prepared in the embodiments of the present invention not only have zirconium-free and non-radioactive properties, but also have excellent light transmittance, refractive index stability, acid and alkali resistance, thermal conductivity, bending strength, and extremely low haze.

[0037] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A zirconium-free, non-radioactive, acid and alkali-resistant optical ceramic plate, characterized in that, The raw materials include the following parts by weight: 1.2-1.5 parts polyethylene glycol octylphenyl ether, 100 parts aluminum nitride powder, 80-100 parts boron-doped aluminum nitride quantum dot dispersion, 0.3-0.8 parts modified graphene oxide, 5-6 parts yttrium oxide, 3-5 parts spodumene, 0.3-0.4 parts oleic acid, 2-3 parts polyvinyl butyral, and 2-3 parts dibutyl phthalate; The boron-doped aluminum nitride quantum dot dispersion is a precursor sol made of aluminum nitrate and boric acid, which is prepared by drying and calcination under an ammonia atmosphere. The modified graphene oxide is graphene oxide modified with polysilazane.

2. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 1, characterized in that, The preparation method of the boron-doped aluminum nitride quantum dot dispersion is as follows: A1: Add aluminum nitrate to anhydrous ethanol and stir at 40°C for 60-70 min. Then add boric acid and stir at 40°C for 60-80 min. Next, add polyethylene glycol and stir for 30-40 min. Adjust the pH to 5.5-6 and stir at 40°C for 2-2.5 h. Seal and let stand for 12-15 h to obtain the precursor sol. A2: The precursor sol was poured into a polytetrafluoroethylene mold and dried. After grinding, it was spread in a boron nitride crucible and calcined. Then it was added to anhydrous ethanol and ultrasonically dispersed. The supernatant was then collected by centrifugation and concentrated to a concentration of 10 mg / mL to obtain a boron-doped aluminum nitride quantum dot dispersion.

3. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 2, characterized in that, The ratio of anhydrous ethanol, aluminum nitrate, boric acid, and polyethylene glycol in A1 is 90-100 mL: 5 g: 0.12 g: 0.2 g.

4. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 2, characterized in that, The calcination process described in A2 is as follows: first, purge with high-purity ammonia gas at a flow rate of 150 mL / min for 30-40 min, then raise the temperature to 300℃ at a rate of 5℃ / min and hold for 2-2.5 h, then raise the temperature to 800℃ at a rate of 8℃ / min and hold for 3-3.5 h, then raise the temperature to 1200-1300℃ at a rate of 10℃ / min and hold for 4-6 h, and finally maintain the ammonia purging cooling.

5. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 1, characterized in that, The modified graphene oxide is prepared as follows: Polysilazane was added to anhydrous tetrahydrofuran and stirred for 30-50 min. Then it was dropped into anhydrous tetrahydrofuran dispersion of graphene oxide and heated to 50-55℃ under nitrogen atmosphere and stirred for 9-10 h. After cooling, the mixture was centrifuged, the precipitate was washed, vacuum dried, and ground to obtain modified graphene oxide.

6. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 5, characterized in that, The ratio of the anhydrous tetrahydrofuran, polysilazane, and graphene oxide anhydrous tetrahydrofuran dispersion is 10-12 mL: 2 g: 50 mL. The concentration of the anhydrous tetrahydrofuran dispersion of graphene oxide is 0.5 mg / mL.

7. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 1, characterized in that, The method for preparing the zirconium-free, non-radioactive, acid and alkali-resistant optical ceramic plate is as follows: S1: Add N-methylpyrrolidone to anhydrous ethanol and stir well. Then add polyethylene glycol octylphenyl ether and stir for 30-40 min. Next, add aluminum nitride powder and stir for 30-40 min. Then add boron-doped aluminum nitride quantum dot dispersion, modified graphene oxide, yttrium oxide, and spodumene and stir for 60-90 min. Then add oleic acid and ball mill for 12-16 h. After sieving, add polyvinyl butyral and stir for 60-70 min. Finally, add dibutyl phthalate and stir for 2-2.5 h. After degassing under vacuum for 60-90 min, adjust the viscosity to obtain the slurry. S2: Pour the slurry into the casting machine trough for casting to form a continuous green film with a thickness of 80-120μm. Then dry, cut and trim the film, and then place it in a high-purity alumina crucible for pre-firing to obtain a pre-fired green film. S3: The pre-fired green body is placed into a mold for sintering, then ground, polished, cleaned, vacuum dried and trimmed to obtain a zirconium-free, non-radioactive, acid and alkali resistant optical ceramic plate.

8. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 7, characterized in that, The ratio of anhydrous ethanol, N-methylpyrrolidone, polyethylene glycol octylphenyl ether, aluminum nitride powder, boron-doped aluminum nitride quantum dot dispersion, modified graphene oxide, yttrium oxide, spodumene, oleic acid, polyvinyl butyral, and dibutyl phthalate in S1 is 30mL:20mL:1.2-1.5g:100g:80-100g:0.3-0.8g:5-6g:3-5g:0.3-0.4g:2-3g:2-3g.

9. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 7, characterized in that, The pre-firing process described in S2 is as follows: under a nitrogen atmosphere, the temperature is first raised to 350°C at a heating rate of 5°C / min and held for 1 hour, then raised to 450°C at a heating rate of 3°C / min and held for 2-2.5 hours, and finally cooled with the furnace.

10. The zirconium-free, non-radioactive, and acid- and alkali-resistant optical ceramic plate according to claim 7, characterized in that, The sintering process described in S3 is as follows: First, the temperature is raised to 800℃ at a flow rate of 10℃ / min under a nitrogen atmosphere with a flow rate of 200mL / min and a furnace pressure of 0.1MPa. Then, the temperature is raised to 1600℃ at a pressure of 15MPa at a flow rate of 5℃ / min. Next, the temperature is raised to 1850℃ at a flow rate of 3℃ / min while the pressure is gradually increased to 40-50MPa. The temperature is held at 1850℃ and 40-50MPa for 30-40 minutes, and then the temperature is lowered to 800℃ at a flow rate of 120℃ / min. Finally, the furnace is cooled.

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