Preparation method of yag nano-transparent ceramic and application of yag nano-transparent material

Abstract

The present application relates to the technical field of transparent ceramic preparation, and specifically discloses a preparation method of YAG nano transparent ceramic. The preparation method comprises the following steps: S1, extruding YAG nano powder to obtain a green body; S2, high pressure treatment is performed on the green body, and the pressure of the high pressure treatment is greater than or equal to 2 GPa. The present application innovatively introduces a high pressure treatment process, and high-density nano transparent ceramic can be obtained at room temperature (~ 20 DEG C). In addition, the present application also relates to the application of the ceramic prepared by the preparation method. The transparent ceramic prepared by the preparation method has good transparent performance and high mechanical performance, and is a wave-transparent material suitable for optical lens materials, transparent armor, scintillators and laser gain media.

Description

Technical Field

[0001] This invention relates to the field of transparent ceramics preparation technology, specifically to a method for preparing YAG nano-transparent ceramics. Furthermore, this invention also relates to the application of the YAG nano-transparent ceramics prepared by this method. Background Technology

[0002] Traditional ceramics, due to their high brittleness and low transparency, have limited applications in optics and optoelectronics. However, with breakthroughs in the preparation of high-purity powders and the development of transparent ceramics, researchers have achieved transparency in ceramic materials by optimizing the microstructure and adjusting the composition ratio. These advancements have not only propelled the industrialization of transparent ceramics but also provided new material support for innovation in many high-tech fields. Currently, the preparation of transparent ceramics generally involves three stages: powder preparation, material forming, and sintering, with sintering being a crucial stage affecting material properties. Existing sintering technologies commonly use vacuum sintering, spark plasma sintering, hot pressing, or hot isostatic pressing to prepare yttrium aluminum garnet (YAG) transparent ceramic materials. However, these sintering techniques generally suffer from problems such as the addition of extra sintering aids, long sintering times, high sintering temperatures, and the rapid growth of nanoscale powders into submicron or even micron-sized particles under prolonged high-temperature conditions. These problems significantly reduce the mechanical and optical properties of transparent ceramic materials, severely restricting the large-scale application of YAG transparent ceramics in high-end optical devices.

[0003] Therefore, developing a method for preparing YAG nano-transparent ceramics that requires no sintering aids, operates at low temperatures and short time, and can suppress grain coarsening has become a technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0004] The purpose of this invention is to address the problems in existing YAG nano-transparent ceramic preparation technologies, such as abnormal grain growth and residual second-phase at grain boundaries, which affect the mechanical and transparency properties of YAG ceramics. This invention provides a method for preparing YAG nano-transparent ceramics and the applications of YAG nano-transparent materials. This method requires no sintering aids, has a low forming temperature, short cycle time, and low energy consumption. The prepared YAG ceramics possess both excellent optical transmittance and high mechanical strength, overcoming the performance bottlenecks of traditional processes.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for preparing YAG nano-transparent ceramics, the method comprising the following steps:

[0006] S1. YAG nanopowder is extruded to obtain a green blank;

[0007] S2. The green blank is subjected to high pressure treatment, wherein the pressure of the high pressure treatment is greater than or equal to 2 GPa.

[0008] Preferably, the pressure of the high-pressure treatment is 2-15 GPa.

[0009] Preferably, in step S2, the high-pressure treatment includes a first pressure boosting treatment, a second pressure boosting treatment, and a pressure depressurization treatment performed sequentially. The pressure of the first pressure boosting treatment is less than the pressure of the second pressure boosting treatment, and the pressure of the first pressure depressurization treatment is less than the pressure of the second pressure boosting treatment but greater than the pressure of the first pressure boosting treatment.

[0010] More preferably, the conditions for the first pressurization process include: a pressure of 2-8 GPa and a time of 40-80 s;

[0011] The conditions for the second pressurization process include: a pressure of 3-10 GPa and a time of 0.5-80 min;

[0012] The conditions for the pressure reduction treatment include: a pressure of 2.5-8.5 GPa and a time of 100-150 s.

[0013] More preferably, the conditions for the first pressurization process include: a pressure of 4-5 GPa and a time of 50-70 s;

[0014] The conditions for the second pressurization include: a pressure of 5-7.7 GPa and a time of 0.5-3 min;

[0015] The conditions for the pressure reduction treatment include: a pressure of 4.5-6.5 GPa and a time of 110-130 s.

[0016] Preferably, in step S2, the compression process is carried out in a six-sided top press.

[0017] Preferably, in step S1, the extrusion molding conditions include: a pressure of 4-6 MPa and a time of 3-8 min.

[0018] Preferably, the preparation steps of the YAG nanopowder include:

[0019] A solution containing a precipitant was titrated with a mixture of aluminum and yttrium salts. The titration was stopped and the precipitate was collected once the pH of the mixture reached the preset pH.

[0020] More preferably, the preset pH value is 7.9-8.1.

[0021] More preferably, the precipitant is ammonia and / or ammonium bicarbonate.

[0022] Preferably, the mixture containing aluminum salt and yttrium salt further contains a dispersant.

[0023] More preferably, the dispersant is ammonium sulfate.

[0024] Preferably, the preparation steps of the YAG nanopowder further include: allowing the mixture to stand for 3-24 hours after the titration is completed.

[0025] Preferably, the preparation steps of the YAG nanopowder further include: washing, drying, crushing and then calcining the precipitate.

[0026] Preferably, the calcination conditions include: a temperature of 900-1100℃ and a time of 2-8 hours.

[0027] The second aspect of this invention provides the application of the YAG transparent ceramic prepared by the above preparation method in optical lens materials, transparent armor, scintillator materials, and laser gain media.

[0028] The preparation method provided by this invention, through high-pressure densification at pressures exceeding 2 GPa, prepares transparent YAG ceramics without requiring sintering of the YAG nanopowder or the addition of extra sintering aids. The resulting transparent YAG ceramics exhibit good transparency and high mechanical properties. Furthermore, the entire method has a short preparation time, significantly reducing energy consumption. It provides a new approach for preparing transparent ceramics and has the potential for mass production, contributing to the achievement of low-carbon or even zero-carbon goals. Attached Figure Description

[0029] Figure 1 This is a flowchart of the preparation of YAG nano-transparent ceramics provided in a specific embodiment of the present invention;

[0030] Figure 2 The images are XRD patterns of the YAG precursor prepared in Example 1, the YAG nanopowder prepared in Example 1, the YAG nanopowder prepared in Example 8, and the YAG nanopowder prepared in Example 9. Among them, (a) is the XRD pattern of the YAG precursor prepared in Example 1, (b) is the XRD pattern of the YAG nanopowder prepared in Example 1, (c) is the XRD pattern of the YAG nanopowder prepared in Example 8, and (d) is the XRD pattern of the YAG nanopowder prepared in Example 9.

[0031] Figure 3 These are SEM images of the YAG precursor prepared in Example 1, the YAG nanopowder prepared in Example 1, the YAG nanopowder prepared in Example 8, and the YAG nanopowder prepared in Example 9. Among them, (a) is the SEM image of the YAG precursor prepared in Example 1, (b) is the SEM image of the YAG nanopowder prepared in Example 1, (c) is the SEM image of the YAG nanopowder prepared in Example 8, and (d) is the SEM image of the YAG nanopowder prepared in Example 9.

[0032] Figure 4 This is a schematic diagram of the assembly structure used in high-pressure processing;

[0033] Figure 5 This is a high-pressure processing diagram;

[0034] Figure 6 The above are YAG nano-transparent ceramics obtained in Examples 1-4 and Comparative Example 1, wherein (a) is the YAG nano-transparent ceramic prepared in Comparative Example 1, (b) is the YAG nano-transparent ceramic prepared in Example 1, (c) is the YAG nano-transparent ceramic prepared in Example 2, (d) is the YAG nano-transparent ceramic prepared in Example 3, and (e) is the YAG nano-transparent ceramic prepared in Example 4.

[0035] Figure 7 These are the UV-Vis spectra of the YAG nano-transparent ceramics obtained in Examples 4-6 and Comparative Example 1.

[0036] Figure 8 This is a SEM image of the YAG nano-transparent ceramic obtained in Example 4. Detailed Implementation

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0038] The first aspect of this invention provides a method for preparing YAG nano-transparent ceramics, the method comprising the following steps:

[0039] S1. YAG nanopowder is extruded to obtain a green blank;

[0040] S2. The green blank is subjected to high pressure treatment, wherein the pressure of the high pressure treatment is greater than or equal to 2 GPa.

[0041] During their research, the inventors discovered that the preparation method provided by this invention, which prepares YAG nano-transparent ceramics through high-pressure compression exceeding 2 GPa, eliminates the need for sintering of the YAG nanopowder or the addition of extra sintering aids. Furthermore, the prepared YAG nano-transparent ceramics exhibit excellent transparency and high mechanical properties. Atomic-level diffusion bonding of YAG nanopowder is achieved, successfully preparing YAG nano-transparent ceramics with both high optical quality and excellent mechanical properties. Moreover, the entire method has a short preparation time, significantly reducing energy consumption. It provides a new approach for preparing nano-transparent ceramics and has the potential for mass production, contributing to the achievement of low-carbon or even zero-carbon goals.

[0042] According to the present invention, preferably, the pressure of the high-pressure treatment is 2-15 GPa, which can be 2 GPa, 4 GPa, 6 GPa, 8 GPa, 10 GPa, 12 GPa, 14 GPa, 15 GPa, or any value within any two of these ranges. More preferably, the pressure of the high-pressure treatment is 2-10 GPa.

[0043] Preferably, in step S2, the high-pressure treatment includes a first pressurization treatment, a second pressurization treatment, and a depressurization treatment performed sequentially. The pressure of the first pressurization treatment is lower than the pressure of the second pressurization treatment, and the pressure of the depressurization treatment is lower than the pressure of the second pressurization treatment but higher than the pressure of the first pressurization treatment. Limiting the pressure of the first pressurization treatment to be lower than the pressure of the second pressurization treatment, and limiting the pressure of the depressurization treatment to be higher than the pressure of the first pressurization treatment but lower than the pressure of the second pressurization treatment, can further improve the transparency and mechanical properties of the prepared ceramic. To further improve the transparency and mechanical properties of the prepared ceramics, the conditions for the first pressurization treatment are preferably as follows: a pressure of 2-8 GPa, which can be 2 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa, 7 GPa, 8 GPa, or any value within any two of these ranges; and a time of 40-80 s, which can be 40 s, 45 s, 50 s, 55 s, 60 s, 65 s, 70 s, 75 s, 80 s, or any value within any two of these ranges; the conditions for the second pressurization treatment are as follows: a pressure of 3-10 GPa, which can be 3 GPa, 4 GPa, 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, 10 GPa, or any value within any two of these ranges; and a time of 40-80 s. The time interval is 0.5-80 min, which can be 0.5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, or any value within any two of these ranges; the conditions for the pressure reduction treatment include: pressure of 2.5-8.5 GPa, which can be 2.5 GPa, 3.5 GPa, 4.5 GPa, 5.5 GPa, 6.5 GPa, 7.5 GPa, 8.5 GPa, or any value within any two of these ranges; and time of 100-150 s, which can be 100 s, 105 s, 110 s, 115 s, 120 s, 125 s, 130 s, 135 s, 140 s, 145 s, 150 s, or any value within any two of these ranges. More preferably, the conditions for the first pressurization process include: a pressure of 4-5 GPa and a time of 50-70 s; the conditions for the second pressurization process include: a pressure of 5-7.7 GPa and a time of 0.5-3 min; and the conditions for the depressurization process include: a pressure of 4.5-6.5 GPa and a time of 110-130 s.

[0044] Preferably, in step S2, the compression process is performed in a six-sided press. This allows for uniform pressure to be applied to all six sides of the green body, thereby further improving the transparency and mechanical properties of the ceramic.

[0045] In step S1, the extrusion molding can be performed using the YAG extrusion molding method disclosed in the prior art. In order to further improve the molding effect, preferably, in step S1, the extrusion molding conditions include: pressure of 4-6 MPa, which can be 4 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa, 5 MPa, 5.2 MPa, 5.4 MPa, 5.6 MPa, 5.8 MPa, 6 MPa, or any value within any two of these ranges; and time of 3-8 min, which can be 3 min, 3.5 min, 4 min, 4.5 min, 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, or any value within any two of these ranges.

[0046] Preferably, the preparation steps of the YAG nanopowder include: titrating a solution containing a precipitant with a mixture containing aluminum salt and yttrium salt, ending the titration and collecting the precipitate after the pH of the mixture reaches a preset pH.

[0047] Preferably, the preset pH value is 7.9-8.1, which can be 7.9, 7.92, 7.94, 7.96, 7.98, 8, 8.02, 8.04, 8.06, 8.08, 8.1, or any value within any two of these values.

[0048] Preferably, the precipitant is ammonia and / or ammonium bicarbonate. These precipitants can better control the pH of the mixture containing aluminum and yttrium salts, thereby enabling the preparation of YAG precursor materials.

[0049] Preferably, the mixture containing aluminum salt and yttrium salt further contains a dispersant, which can improve the dispersion effect of aluminum salt and yttrium salt. More preferably, the dispersant is ammonium sulfate.

[0050] Preferably, the preparation step of the YAG nanopowder further includes: allowing the mixture to stand for 3-24 hours after titration. This allows as much solid as possible to precipitate to the bottom, thereby collecting as much precipitate as possible.

[0051] To prevent sintering agglomeration that could affect subsequent pressing, the preparation step of the YAG nanopowder preferably further includes: washing, drying, crushing, and then calcining the precipitate. Preferably, the calcination conditions include: a temperature of 900-1100℃, which can be 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃, 1020℃, 1040℃, 1060℃, 1080℃, 1100℃, or any value within any two of these ranges; and a time of 2-8h, which can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, or any value within any two of these ranges.

[0052] Preferably, the aluminum salt is selected from at least one of Al(NO3)3·9H2O, AlCl3, and Al(OH)3, and the yttrium salt is Y(NO3)3·6H2O and / or YCl3. More preferably, the aluminum salt is Al(NO3)3·9H2O, and the yttrium salt is Y(NO3)3·6H2O.

[0053] Preferably, the molar ratio of aluminum salt (calculated as aluminum) to yttrium salt (calculated as yttrium) is 1:0.5-0.7.

[0054] Preferably, the solvent for the solution containing aluminum salt and yttrium salt is a mixture of water and ethanol. More preferably, the volume ratio of water to ethanol in the mixture is 4-6:1.

[0055] Preferably, during the compression process, the container holding the preform needs to be pre-assembled, and its assembly structure is as follows: Figure 4 As shown. The ultra-high pressure assembly structure includes pyrophyllite, a dolomite ring, a dolomite tube, a conductive plug, a molybdenum cup containing the sample, a hollow graphite structure, a magnesium oxide layer disposed inside the hollow graphite structure, and molybdenum sheets disposed at both ends of the hollow graphite structure. The internal cavity of the hollow graphite structure serves as a heating chamber. A conductive plug is disposed on the molybdenum sheet, and a dolomite tube is disposed outside the conductive plug. Hexahedral pyrophyllite blocks are disposed outside the hollow graphite structure and the molybdenum cup. The hollow graphite structure includes a graphite tube, graphite sheets wrapped around the sides of the graphite tube, and a graphite column disposed between the graphite tube and the molybdenum sheet. The diameter of the graphite column is smaller than the diameter of the graphite tube. A dolomite ring is disposed in the area between the graphite tube and the molybdenum sheet, excluding the graphite column. The magnesium oxide layer includes a magnesium oxide tube and at least two magnesium oxide sheets and two cemented carbide sheets disposed inside the magnesium oxide tube. In actual use, the molybdenum cup containing the sample is placed between the two cemented carbide sheets.

[0056] A second aspect of this invention provides the application of the YAG nano-transparent ceramics prepared by the above-described method in optical lens materials, transparent armor, scintillator materials, laser gain media, or other applications. The YAG nano-transparent ceramics obtained by the above methods possess good transparency and high mechanical properties, and have good applications in the aforementioned fields.

[0057] According to a particularly preferred embodiment of the present invention, a method for preparing YAG nano-transparent ceramics is provided, such as... Figure 1 As shown, it includes the following steps:

[0058] (1) Dissolve aluminum salt Al(NO3)3·9H2O and yttrium salt Y(NO3)3·6H2O in a mixture of deionized water and ethanol, add ammonium sulfate as a dispersant to obtain a mixed salt solution; dissolve ammonium bicarbonate in deionized water to prepare a sodium bicarbonate precipitant solution; dilute with chemically pure ammonia water as a pH adjuster for the precipitant solution;

[0059] The molar ratio of aluminum salts to yttrium salts, calculated as aluminum, is 5:3;

[0060] (2) The pH of the precipitant solution was stabilized at 7.9-8.1 by adjusting the ammonia water. The mixed salt solution was added dropwise to the precipitant solution, and the pH of the mixed solution was monitored in real time with a high-precision pH meter. The diluted ammonia water solution was added dropwise to stabilize the pH of the mixed solution at around 8.0.

[0061] (3) After titration, continue stirring for 20-40 min, then turn off the stirrer and age and precipitate for 3-24 h to obtain supernatant and precipitate. Remove the supernatant and wash the remaining solution containing precipitate with deionized water and ethanol, then sonicate and centrifuge. Repeat the process 3-6 times. Then dry in a drying oven at 60-80℃ for 16-32 h to obtain YAG precursor powder material.

[0062] (4) Crush the YAG precursor with a mortar and sieve it through a 200-mesh and a 100-mesh sieve in sequence. Then calcine it in a high-temperature furnace at a temperature of 900-1100℃, a heating rate of 1-20℃ / min, and a holding time of 2-8h. Then cool it with the furnace to obtain YAG nanopowder.

[0063] (5) Pour YAG nanopowder into a molybdenum cup and place it in an extrusion mold. Apply a force of 4-6 MPa and hold for 3-8 minutes. Then remove the molybdenum cup.

[0064] (6) Place the pre-pressed molybdenum cup according to... Figure 4 Assemble the parts and then place them in a six-sided press, such as... Figure 5As shown, without additional heating at room temperature, the pressure was first increased to 2-8 GPa and held for 40-80 seconds, then increased to 3-10 GPa and held for 0.5-80 minutes. The pressure was then reduced to 2.5-8.5 GPa and held for 100-150 seconds (the first pressure was lower than the second, and the pressure after depressurization was lower than the second but higher than the first). Finally, the pressure was reduced to atmospheric pressure. After the experiment, the molybdenum cup containing the sample was removed, cut, and polished to obtain the final ceramic sample.

[0065] The YAG nano-transparent ceramics prepared by the method provided in this invention exhibit good transparency and high mechanical properties, making them promising for applications in optical lens materials, transparent armor, scintillator materials, and laser gain media. Furthermore, the entire preparation method is quick, significantly reducing energy consumption, providing a new approach to the preparation of transparent ceramics, and possessing the potential for mass production, thus contributing to the achievement of low-carbon or even zero-carbon goals.

[0066] The present invention will be described in detail below through examples. In the following examples, the phase changes and morphological characteristics of the materials were measured using XRD (X-ray diffractometer, Dandong Tongda Technology Co., Ltd., TD-3500) and SEM (ZEISS Sigma 360, Germany); the transmittance was measured using a UV-Vis-NIR spectrophotometer (Shimadzu UV-3600iPlus, Japan); the Vickers hardness was measured according to ASTM C1327; and the compressive strength was measured according to ASTM C1424. Al(NO3)3·9H2O (99.99%, A110784), Y(NO3)3·6H2O (99.99%, Y118878), ammonium bicarbonate (chemically pure, A110536), ammonium sulfate (99.99%, A112105), ammonia (chemically pure), and ethanol (chemically pure) were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0067] Example 1

[0068] Preparation of S1 and YAG nanopowders

[0069] (1) Under normal pressure (0.1 MPa) and room temperature (~20℃), 0.05 mol aluminum salt Al(NO3)3·9H2O and 0.03 mol yttrium salt Y(NO3)3·6H2O were dissolved in 100 mL of deionized water and ethanol (volume ratio of deionized water to ethanol 5:1), and 1.0 mol ammonium sulfate was added as a dispersant to obtain a mixed salt solution; ammonium bicarbonate was dissolved in 200 mL of deionized water to prepare a sodium bicarbonate precipitant solution with a concentration of 0.25 mol / L; chemically pure ammonia water was diluted to a concentration of 1 mol / L as a pH adjuster for the precipitant solution;

[0070] (2) The pH of the precipitant solution is maintained at 7.9-8.1 by adjusting the ammonia water. The mixed salt solution is added to the precipitant solution at a dropping rate of 20 mL / min. The reaction is continuously stirred with a magnetic stirrer, and the pH of the mixed solution is monitored in real time with a high-precision pH meter to stabilize the pH of the mixed solution at around 8.0.

[0071] (3) After titration, continue stirring for 30 min, then turn off the stirrer and age and precipitate for 3 h. The solution is separated into supernatant and precipitate. Remove the supernatant and wash the remaining solution containing precipitate with deionized water and ethanol, then sonicate and centrifuge. Repeat the process 4 times. Then dry it in a drying oven at 70℃ for 24 h to obtain YAG precursor powder material.

[0072] (4) The YAG precursor was crushed in a mortar and sieved through a 200-mesh and a 100-mesh sieve in sequence. Then it was placed in a high-temperature furnace for calcination at a temperature of 900℃, a heating rate of 10℃ / min, and a holding time of 6h. Then it was cooled with the furnace to obtain YAG nanopowder.

[0073] S2, Green body forming process

[0074] YAG nanopowder was poured into a molybdenum cup and placed in an extrusion mold. A force of 5 MPa was applied and held for 5 minutes. Then the molybdenum cup was removed.

[0075] S3, Ceramic Forming Process

[0076] The pre-pressed molybdenum cup is prepared according to... Figure 4 Assemble the parts and then place them in a six-sided press, such as... Figure 5 As shown, without additional heating at room temperature, the pressure was initially increased to 2.0 GPa and held for 1 min, then increased to 3.0 GPa and held for 60 min, then decreased to 2.5 GPa and held for 2 min, and finally reduced to atmospheric pressure. After the experiment, the molybdenum cup containing the sample was removed, cut, and polished to obtain the ceramic sample.

[0077] Example 2

[0078] The ceramic was prepared according to the method of Example 1, except that during the ceramic forming process, the pressure was first increased to 3.0 GPa and held for 1 min, then increased to 4.0 GPa and held for 10 min, and then decreased to 3.5 GPa and held for 2 min.

[0079] Example 3

[0080] The ceramic was prepared according to the method of Example 1, except that during the ceramic forming process, the pressure was first increased to 4.0 GPa and held for 1 min, then increased to 5.0 GPa and held for 3 min, and then decreased to 4.5 GPa and held for 2 min.

[0081] Example 4

[0082] The ceramic was prepared according to the method of Example 1, except that during the ceramic forming process, the pressure was first increased to 5.0 GPa and held for 1 min, then increased to 7.7 GPa and held for 30 s, and then decreased to 6.5 GPa and held for 2 min.

[0083] Example 5

[0084] The ceramic was prepared according to the method of Example 1, except that during the ceramic forming process, the pressure was first increased to 6.0 GPa and held for 1 min, then increased to 8.5 GPa and held for 30 s, and then decreased to 7.0 GPa and held for 2 min.

[0085] Example 6

[0086] The ceramic was prepared according to the method of Example 1, except that during the ceramic forming process, the pressure was first increased to 7.0 GPa and held for 1 min, then increased to 9.0 GPa and held for 30 s, and then decreased to 7.5 GPa and held for 2 min.

[0087] Example 7

[0088] The ceramic was prepared according to the method of Example 1, except that during the ceramic forming process, the pressure was first increased to 2.0 GPa and held for 1 min, then increased to 2.5 GPa and held for 80 min, and then decreased to 2.3 GPa and held for 2 min.

[0089] Example 8

[0090] The ceramics were prepared according to the method of Example 1, except that...

[0091] In the preparation of YAG nanopowder, the calcination temperature is 1000℃, the heating rate is 5℃ / min, and the holding time is 8h.

[0092] During the green body forming process, the applied pressure is 4 MPa and the holding time is 8 min;

[0093] During the ceramic forming process, the pressure is first increased to 2.0 GPa and held for 40 seconds, then increased to 3.0 GPa and held for 40 minutes, and then decreased to 2.5 GPa and held for 150 seconds.

[0094] Example 9

[0095] The ceramics were prepared according to the method of Example 1, except that...

[0096] In the preparation of YAG nanopowder, the calcination temperature was 1100℃, the heating rate was 20℃ / min, and the holding time was 2h.

[0097] During the green body forming process, the applied pressure is 6 MPa and the holding time is 3 min;

[0098] During the ceramic forming process, the pressure is first increased to 2.0 GPa and held for 80 seconds, then increased to 3.0 GPa and held for 80 minutes, and then decreased to 2.5 GPa and held for 100 seconds.

[0099] Example 10

[0100] The ceramic was prepared according to the method of Example 1, except that during the ceramic forming process, the pressure was first increased to 2.0 GPa and held for 1 min, then increased to 3.0 GPa and held for 60 min, and then reduced to atmospheric pressure.

[0101] Example 11

[0102] The ceramic was prepared according to the method of Example 1, except that during the ceramic forming process, the pressure was increased to 3.0 GPa, held for 60 min, then decreased to 2.5 GPa, held for 2 min, and finally reduced to atmospheric pressure.

[0103] Comparative Example 1

[0104] The ceramics were prepared according to the method of the embodiment, except that in the ceramic preparation process, the pressure was first increased to 1.0 GPa and held for 1 min, then increased to 2.0 GPa and held for 120 min, and then decreased to 1.5 GPa and held for 2 min.

[0105] The physical and chemical properties of the obtained ceramics are shown in Table 1.

[0106] Table 1

[0107]

[0108] As can be seen from the results in Table 1, the compressive strength, Vickers hardness, and light transmittance of the embodiments of the present invention are all higher than those of the comparative example, indicating that the method provided by the present invention can effectively improve the Vickers hardness, compressive strength, and light transmittance of YAG nanoceramics.

[0109] Figure 2 These are the XRD patterns of the YAG nanopowders prepared in Examples 1, 8, and 9. Figure 3 These are scanning electron microscope (SEM) images of the YAG nanopowders prepared in Examples 1, 8, and 9. Figure 2 and Figure 3 It can be seen that the prepared YAG precursor powder is an amorphous material. The corresponding SEM image shows that it is a mixture of multiphase materials. The calcination temperature of 900-1100℃ is a pure YAG cubic phase, which is consistent with the standard card PDF#71-0255. The SEM image shows that in the range of 900-1100℃, the YAG single phase exhibits a nanoscale crystal morphology.

[0110] Figure 6 These are photographs of ceramics prepared in Examples 1-4 and Comparative Example 1, by... Figure 6 It can be seen that the ceramics prepared in Examples 3-4 have better transparency, while the ceramics prepared in Comparative Example 1 are basically opaque. Figure 7 The images show the UV-Vis spectra of the ceramics prepared in Comparative Example 1, Example 4, Example 5, and Example 6. As shown in Figure 7, the light transmittance of the ceramics obtained in Examples 4-6 is significantly higher than that of the ceramics obtained in the comparative examples. Figure 8 This is a SEM image of the nanoceramics prepared in Example 4. Figure 8 It can be seen that the particle size of YAG transparent ceramics prepared under high pressure and room temperature is at the nanoscale.

[0111] Studies have found that as the pressure of the first and second pressurization treatments increases, the compressive strength and light transmittance of the resulting material also increase. However, after the pressure of the second pressurization treatment exceeds 7.7 GPa, the change in compressive strength and light transmittance with further pressure increases becomes limited. Furthermore, increased pressure can lead to cracking in the ceramics and wear and tear on the instrument, affecting the subsequent use of the ceramics, reducing the instrument's lifespan, and increasing manufacturing costs.

[0112] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing YAG nano-transparent ceramics, characterized in that, The preparation method includes the following steps: S1. YAG nanopowder is extruded to obtain a green blank; S2. The green blank is subjected to high-pressure treatment; In step S2, the high-pressure treatment includes a first pressure boosting treatment, a second pressure boosting treatment, and a pressure depressurization treatment performed sequentially. The pressure of the first pressure boosting treatment is less than the pressure of the second pressure boosting treatment, and the pressure of the pressure depressurization treatment is less than the pressure of the second pressure boosting treatment but greater than the pressure of the first pressure boosting treatment. The conditions for the first pressurization treatment include: a pressure of 2-8 GPa and a time of 40-80 s; the conditions for the second pressurization treatment include: a pressure of 3-10 GPa and a time of 0.5-80 min; the conditions for the depressurization treatment include: a pressure of 2.5-8.5 GPa and a time of 100-150 s; sintering of the YAG nanopowder is not required, nor is it necessary to add additional sintering aids.

2. The preparation method according to claim 1, characterized in that, The conditions for the first pressurization process include: a pressure of 4-5 GPa and a time of 50-70 s; The conditions for the second pressurization process include: a pressure of 5-7.7 GPa and a time of 0.5-3 min; The conditions for the pressure reduction treatment include: a pressure of 4.5-6.5 GPa and a time of 110-130 s.

3. The preparation method according to claim 1 or 2, characterized in that, In step S2, the high-pressure treatment is carried out in a six-sided top press.

4. The preparation method according to claim 1 or 2, characterized in that, In step S1, the extrusion molding conditions include: a pressure of 4-6 MPa and a time of 3-8 min.

5. The preparation method according to claim 1 or 2, characterized in that, The preparation steps of the YAG nanopowder include: A solution containing a precipitant was titrated with a mixture of aluminum and yttrium salts. The titration was stopped and the precipitate was collected once the pH of the mixture reached the preset pH value.

6. The preparation method according to claim 5, characterized in that, The preset pH value is 7.9-8.

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7. The preparation method according to claim 6, characterized in that, The precipitant is ammonia and / or ammonium bicarbonate.

8. The preparation method according to claim 5, characterized in that, The mixture containing aluminum salt and yttrium salt also contains a dispersant.

9. The preparation method according to claim 8, characterized in that, The dispersant is ammonium sulfate.

10. The preparation method according to claim 5, characterized in that, The preparation steps of the YAG nanopowder also include: allowing the mixture to stand for 3-24 hours after the titration is completed.

11. The preparation method according to claim 10, characterized in that, The preparation steps of the YAG nanopowder also include: washing, drying, crushing and then calcining the precipitate.

12. The preparation method according to claim 11, characterized in that, The calcination conditions include a temperature of 900-1100℃ and a time of 2-8 hours.

13. The application of YAG nano-transparent ceramics prepared by the preparation method according to any one of claims 1 to 12 in optical lens materials, transparent armor, scintillator materials or laser gain media.

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