Low-temperature rapid preparation method of MgAlON transparent ceramic with high infrared transmittance

Abstract

The invention relates to a low-temperature rapid preparation method of MgAlON transparent ceramic with high infrared transmittance, and belongs to the field of ceramic preparation. The method comprises the following steps: designing the chemical composition of MgAlON according to an Al2O3-AlN-MgO phase diagram, synthesizing pure-phase MgAlON powder by using 76-77 wt.% of gamma-Al2O3, 13-14 wt.% of AlN and 9-9.6 wt.% of MgAl2O4 as raw materials through a high-temperature solid-phase method, adding a sintering aid, carrying out ball milling, drying to obtain MgAlON / sintering aid mixed powder, carrying out dry-pressing molding to prepare a blank, heating the blank to 1780-1900 DEG C at a speed of 10-40 DEG C / min in a nitrogen atmosphere, carrying out heat preservation for 30-180 minutes, carrying out heat preservation for 20-30 minutes at a speed of 10-40 DEG C / min, carrying out heat preservation for 20-30 minutes at a speed of 20-30 DEG C / min, and the MgAlON transparent ceramic is prepared. The method has the characteristics of controllable chemical composition, simple sintering equipment, low sintering temperature, short heat preservation time, high infrared transmittance of the prepared MgAlON ceramic and the like, and is good in energy-saving effect, high in efficiency, low in cost, suitable for preparation of large-size and complex-shape sample pieces and easy to realize industrialization.

Description

Technical Field

[0001] The invention relates to a low-temperature rapid preparation method of MgAlON transparent ceramics with high infrared transmittance, belonging to the field of ceramic preparation. Background Art

[0002] MgAlON transparent ceramic material not only has excellent optical properties, but also has high mechanical strength and hardness. It also has the advantages of light weight and stable thermodynamic properties. It is one of the preferred materials for high-speed aircraft windows and covers, and has broad application prospects in both military and civilian fields.

[0003] As a spinel quaternary disordered solid solution, MgAlON has a complex chemical composition and multiple coordination environments, which gives it a wide range of performance control space and rich performance combinations. The non-stoichiometric composition of MgAlON makes its chemical composition and the ceramic properties that depend on it more designable.

[0004] The main way to prepare MgAlON transparent ceramics is to first synthesize MgAlON powder and then sinter it. Generally speaking, the chemical composition of MgAlON powder combined with the particle size distribution jointly determine its sintering performance and the performance of the prepared ceramics. Therefore, synthesizing MgAlON powder with high purity and high sintering performance is a crucial step in preparing MgAlON ceramics with excellent optical properties under low temperature conditions and in a short time. Among the MgAlON powder synthesis processes such as high-temperature solid-phase reaction method, carbon thermal reduction nitridation method and aluminothermic reduction nitridation method, the high-temperature solid-phase reaction method often uses Al2O3, MgO and AlN powders as the main raw materials to synthesize powders in a high-temperature nitrogen environment. It has the advantages of controllable chemical composition, simple process and suitability for large-scale production. It is an ideal method to achieve mass production of MgAlON powder with high sintering performance.

[0005] Transparent ceramic sintering based on MgAlON powder currently mostly adopts the technical approach of first preparing a pre-burnt body by pressureless sintering and then hot isostatic pressing sintering. This method uses MgAlON powder as raw material, first prepares a pre-burnt body by pressureless sintering at 1825-1850℃ for 2-10h, and then uses hot isostatic pressing sintering method to keep it at 1880℃ for 2-5h to obtain high-density and high-transmittance MgAlON ceramics (Ma BY, et al., Optical Materials, 2018, 84: 714-721; Zong X, et al., Journal of the American Ceramic Society, 2019, 102(11): 6507-6516; Zong X, et al. Scripta Materialia, 2020, 178: 428-432). However, from the perspective of industrial production, pressureless sintering is the preferred method for sintering MgAlON transparent ceramics because of its easy availability of equipment, low cost, and suitability for sintering preparation of large-sized and special-shaped components. In recent years, MgAlON ceramics with high light transmittance have been prepared by using MgAlON powders with different chemical compositions and pressureless sintering technology. However, the product preparation still generally has problems of high sintering temperature and long insulation time. Generally, it is necessary to keep the temperature at 1850-1875℃ for 20-24h to achieve densification sintering and obtain high light transmittance (Liu X, et al., Journal of the American Ceramic Society, 2014, 97(1): 63-66; Ma BY, et al., Journal of Alloys and Compounds, 2018, 745: 617-623; Liu X, et al., Materials, 2017, 10(7): 792; Chen QY, et al., Journal of Alloys and Compounds, 2019, 791: 856-863). It can be seen that the sintering performance of MgAlON powder needs to be improved urgently, and the difficulty of the pressureless sintering process of high-transmittance MgAlON ceramics needs to be reduced urgently. Therefore, by designing the chemical composition of MgAlON, first preparing high-purity MgAlON powder, and then adjusting the particle size distribution of the powder, adding appropriate sintering aids to improve its sintering performance, it is expected to achieve low-temperature rapid pressureless sintering of MgAlON transparent ceramics to meet the industrialization needs of energy saving, environmental protection, low cost, and high efficiency. Summary of the invention

[0006] In order to solve the problems of high sintering temperature and long heat preservation time in the process of pressureless sintering preparation of MgAlON transparent ceramics, the present invention provides a low-temperature rapid preparation method of MgAlON transparent ceramics with high infrared transmittance. The method designs the chemical composition of MgAlON, uses γ-Al2O3, AlN and MgAl2O4 powders as raw materials, synthesizes MgAlON powder by high-temperature solid phase method, and finally prepares MgAlON transparent ceramics by pressureless sintering process. The method has the characteristics of controllable chemical composition of MgAlON ceramics, simple sintering equipment, low temperature and short heat preservation time of pressureless sintering ceramics, high infrared transmittance of the prepared ceramics, good energy-saving effect, high efficiency, low cost, suitable for the preparation of large-size and complex-shaped samples, and easy to realize industrialization.

[0007] A low-temperature rapid preparation method of MgAlON transparent ceramics with high infrared transmittance comprises the following steps:

[0008] Step 1: 76-77wt.% γ-Al2O3, 13-14wt.% AlN and 9-9.6wt.% MgAl2O4 raw material powders are ball-milled and mixed, and then dried and granulated to obtain γ-Al2O3 / AlN / MgAl2O4 mixed powder, which is then subjected to a high temperature solid phase reaction method in a nitrogen atmosphere to obtain pure phase MgAlON powder;

[0009] Step 2: Add a sintering aid to the pure phase MgAlON powder, ball mill and dry to obtain a MgAlON / sintering aid mixed powder, dry press to prepare a green body, then heat the green body to 1780-1900°C at 10-40°C / min in a nitrogen atmosphere and keep it at that temperature for 30-180min, and then cool it in the furnace to obtain MgAlON transparent ceramics.

[0010] In the method of the present invention, in the step 1, the amount of the γ-Al2O3, AlN, and MgAl2O4 raw material powders is determined by designing the chemical composition of MgAlON based on the Al2O3-AlN-MgO phase diagram (the atomic ratio of Mg, Al, O, and N is 1:28-31:36-38:4-6), and then the amount of the γ-Al2O3, AlN, and MgAl2O4 raw material powders is calculated to be 76-77wt.%, 13-14wt.%, and 9-9.6wt.% based on the above chemical composition.

[0011] Preferably, in step 1, the chemical composition of the MgAlON is Mg 0.058 Al 1.708 O 2.182 N 0.292 The specific amounts of γ-Al2O3, AlN and MgAl2O4 raw material powders were calculated to be 76.64wt.%, 13.84wt.% and 9.52wt.%.

[0012] Preferably, in step 2, the green body is heated to 1790° C. at a rate of 15° C. / min in a nitrogen atmosphere and kept at that temperature for 30 min, and then cooled in the furnace to obtain MgAlON transparent ceramics.

[0013] In the method of the present invention, in step 2, the sintering aid is Y2O3 or CaCO3, and the dosage is 0.4-0.6wt.%.

[0014] Preferably, the sintering aid is CaCO3, and the dosage is 0.5wt.%.

[0015] In the method of the present invention, in step 2, the particle size of the MgAlON / sintering aid mixed powder is bimodal, and the peak positions of the two peaks are respectively in the range of 0.4-0.7 μm and 1-2 μm, and D 50 The particle size is 0.8-1.0μm, and the particle size distribution range is 0.05-5.00μm.

[0016] Preferably, the MgAlON / sintering aid mixed powder is a MgAlON / CaCO3 mixed powder, and its particle size is bimodal distribution, with peak positions of 0.45 and 1.72 μm, respectively. 50 The particle size is 0.9 μm and the particle size distribution range is 0.07-4.55 μm.

[0017] In the method of the present invention, in step 1, the average particle size of the γ-Al2O3 powder is ≤40nm; the average particle size of the AlN powder is ≤1.5μm.

[0018] Preferably, the average particle size of the γ-Al2O3 powder is 20 nm, and the average particle size of the AlN powder is 1.18 μm.

[0019] In the method of the present invention, in step 1, the average particle size of the MgAl2O4 powder is ≤200nm, and it is prepared by a high-temperature solid-phase reaction method of γ-Al2O3 and MgO, with a reaction temperature of ≤1300°C and a holding time of ≤120min.

[0020] Preferably, the average particle size of the MgAl2O4 powder is 100 nm.

[0021] Preferably, the MgAl2O4 powder is prepared by heating 71.83wt.% γ-Al2O3 and 28.17wt.% MgO at 1250°C in air for 60 minutes.

[0022] In the method described in the present invention, in step 1, the specific steps of the high-temperature solid-phase reaction method are: loading the γ-Al2O3 / AlN / MgAl2O4 mixed powder into a graphite mold, heating it to 1520-1620°C at a rate of 10-30°C / min in a nitrogen atmosphere and keeping it warm for 15-45min, then continuing to heat it to 1600-1700°C and keeping it warm for 30-60min, cooling it with the furnace, and obtaining a pure phase MgAlON powder.

[0023] Preferably, the γ-Al2O3 / AlN / MgAl2O4 mixed powder is loaded into a graphite mold, heated to 1550°C at 20°C / min in a nitrogen atmosphere, kept warm for 30 minutes, then continued to heat to 1700°C and kept warm for 60 minutes, and cooled with the furnace to obtain MgAlON powder.

[0024] In the method of the present invention, in step 1, the raw material powders of γ-Al2O3, AlN and MgAl2O4 are ball-milled in anhydrous ethanol using silicon nitride balls at 160-210 rpm for 20-30 hours.

[0025] In the method described in the present invention, in step 2, the pure phase MgAlON powder and the sintering aid are ball-milled in anhydrous ethanol at 200-230rpm using silicon nitride balls for 10-15h, wherein the diameters of the silicon nitride balls are 2, 5, and 8mm, respectively, the mass ratio is 1.5-1.7:2-3:1, the ball-to-material ratio is 12-16:1, and the material-liquid ratio is 1:3-5.

[0026] Preferably, in step 1, the raw material powders of γ-Al2O3, AlN and MgAl2O4 are ball-milled in anhydrous ethanol with silicon nitride balls at 170 rpm for 24 h.

[0027] Preferably, in step 2, the pure phase MgAlON powder and the sintering aid are ball-milled in anhydrous ethanol at 210 rpm using silicon nitride balls for 12 hours, wherein the diameters of the silicon nitride balls are 2, 5, and 8 mm, respectively, the mass ratio is 1.6:3:1, the ball-to-material ratio is 14:1, and the material-liquid ratio is 1:4.7.

[0028] The ball milling operations of the present invention are all carried out in a ball milling device provided by the prior art, preferably a planetary ball mill.

[0029] In the method of the present invention, in step 2, the MgAlON / sintering aid mixed powder is preformed by unidirectional pressing at 30-60 MPa, and then cold isostatic pressing at 100-180 MPa is performed to obtain a green body.

[0030] Preferably, the MgAlON / sintering aid mixed powder is preformed by uniaxial pressing at 50 MPa, and then cold isostatically pressed at 120 MPa to obtain a green body.

[0031] Furthermore, the method also includes the steps of grinding and polishing the MgAlON transparent ceramic obtained by sintering.

[0032] Another object of the present invention is to provide a MgAlON transparent ceramic with high infrared transmittance which is rapidly prepared at low temperature by the above method.

[0033] The relative density of the MgAlON transparent ceramic of the present invention is ≥99.38%, and further, the infrared transmittance is 81.0-87.7%, and the hardness is 15-17 GPa.

[0034] Furthermore, the obtained MgAlON transparent ceramic preferably has a relative density of 99.45%, an infrared transmittance of 81.9%, and a hardness of 16.46±0.13 GPa.

[0035] The beneficial effects of the present invention are as follows: the chemical composition of MgAlON is designed based on the Al2O3-AlN-MgO phase diagram, and MgAlON powder is first prepared by a high-temperature solid phase reaction method under the premise of controllable composition, and then the particle size of the MgAlON powder is regulated by ball milling and a sintering aid is added to improve its sintering performance, thereby achieving pressureless sintering of only 30 minutes under a heat preservation condition as low as 1790°C, and obtaining a high-transmittance MgAlON ceramic with a density of up to 99.45% and a transmittance of 81.9%. The chemical composition of this method is controllable, and the prepared MgAlON powder has the characteristics of high purity and good sintering performance, and the process is simple, the equipment is easy to obtain, the cost is low, and the efficiency is high. The high-density sintering of MgAlON is achieved only by pressureless sintering under a relatively low temperature condition and a relatively short heat preservation time, which has a good energy-saving effect and is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the XRD spectrum of the MgAlON powder in Example 1.

[0037] Figure 2 This is the SEM image of the MgAlON powder after ball milling in Example 1.

[0038] Figure 3 This is the particle size distribution diagram of the MgAlON powder after ball milling in Example 1.

[0039] Figure 4 SEM images of the fracture morphology of the MgAlON transparent ceramics prepared in Examples 1 and 2.

[0040] Figure 5 The transmittance curves and sample photos of the MgAlON transparent ceramics prepared in Examples 1 and 2.

[0041] Figure 6This is the SEM image of the fracture morphology of the MgAlON transparent ceramic prepared in Example 3-5.

[0042] Figure 7 The transmittance curve and sample photos of the MgAlON transparent ceramics prepared in Examples 3-5.

[0043] Figure 8 SEM images of the fracture morphology of MgAlON transparent ceramics prepared in Examples 6 and 7.

[0044] Fig. 9 The transmittance curves and sample photos of the MgAlON transparent ceramics prepared in Examples 6 and 7. DETAILED DESCRIPTION

[0045] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0046] The test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0047] One of the specific implementations:

[0048] A low-temperature rapid preparation method of MgAlON transparent ceramics with high infrared transmittance comprises the following steps:

[0049] (1) Designing the chemical composition of MgAlON based on the Al2O3-AlN-MgO phase diagram so that the atomic ratio of Mg, Al, O, and N is 1:28-31:36-38:4-6;

[0050] (2) Using γ-Al2O3, AlN and MgAl2O4 as raw materials, the raw material dosage is calculated according to the chemical composition of the above MgAlON, and the raw material powders are weighed according to 76-77wt.% γ-Al2O3, 13-14wt.% AlN and 9-9.6wt.% MgAl2O4, and silicon nitride balls are used as grinding media and anhydrous ethanol is used as liquid phase. The raw material powders are ball milled at 160-210rpm for 20-30h to obtain slurry, and after drying and granulation, γ-Al2O3 / AlN / MgAl2O4 mixed powders are obtained. Among them, the average particle size of γ-Al2O3 powder is ≤40nm; the average particle size of AlN powder is ≤1.5μm; the average particle size of MgAl2O4 powder is ≤200nm, and it is prepared by high-temperature solid phase reaction of γ-Al2O3 and MgO, the reaction temperature is ≤1300℃, and the insulation time is ≤120min;

[0051] (3) The obtained γ-Al2O3 / AlN / MgAl2O4 mixed powder is loaded into a graphite mold, placed in a carbon furnace, heated to 1520-1620°C at 10-30°C / min in a nitrogen atmosphere, kept warm for 15-45min, then continued to heat to 1600-1700°C and kept warm for 30-60min, and then cooled in the furnace to obtain MgAlON powder;

[0052] (4) adding 0.4-0.6wt.% Y2O3 or CaCO3 as a sintering aid to the MgAlON powder, and ball milling with silicon nitride balls in anhydrous ethanol, wherein the diameters of the silicon nitride balls are 2, 5, and 8 mm, respectively, the mass ratio is 1.5-1.7:2-3:1, the ball-to-material ratio is 12-16:1, the material-liquid ratio is 1:3-5, the rotation speed of the planetary ball mill is 200-230rpm, the ball milling time is 10-15h, and a slurry is obtained, and after drying and granulation, a MgAlON / sintering aid mixed powder is obtained;

[0053] (5) preforming the MgAlON / sintering aid mixed powder under uniaxial pressure at 30-60 MPa, and then cold isostatically pressing at 100-180 MPa to obtain a green body;

[0054] (6) placing the green body in a carbon furnace, heating it to 1780-1900° C. at a rate of 10-40° C. / min in a nitrogen atmosphere, maintaining the temperature for 30-180 min, and cooling the green body in the furnace to obtain MgAlON ceramics;

[0055] (7) The obtained MgAlON ceramic is ground and polished to obtain MgAlON transparent ceramic.

[0056] Example 1

[0057] The chemical composition of MgAlON is designed according to the Al2O3-AlN-MgO phase diagram, making its chemical composition Mg 0.058 Al 1.708 O 2.182 N 0.292 γ-Al2O3, AlN and MgAl2O4 were used as raw materials. The mass contents of the raw material powders were calculated based on the chemical composition to be 76.64%, 13.84% and 9.52% respectively. γ-Al2O3 powder (purity 99.99%, D 50 20nm), AlN powder (purity 97%, D 50 1.18μm) and MgAl2O4 powder (purity 99.99%, D 50The particle size of the MgO / γ-Al2O3 / AlN / MgAl2O4 powder was 100nm and was prepared by keeping 71.83wt.% γ-Al2O3 and 28.17wt.% MgO in air at 1250℃ for 60min. The slurry was obtained by ball milling at 170rpm on a planetary ball mill with silicon nitride balls as grinding media and anhydrous ethanol as liquid phase for 24h. After drying and granulation, a γ-Al2O3 / AlN / MgAl2O4 mixed powder was obtained.

[0058] The γ-Al2O3 / AlN / MgAl2O4 mixed powder was loaded into a graphite mold, placed in a carbon furnace, heated to 1550°C at 20°C / min in a nitrogen atmosphere, kept warm for 30 minutes, then continued to heat to 1700°C and kept warm for 60 minutes, cooled with the furnace, and MgAlON powder was obtained. Figure 1 is the XRD spectrum of the synthesized MgAlON powder, indicating that pure phase MgAlON powder was obtained.

[0059] Add 0.5wt.% CaCO3 to MgAlON powder, use silicon nitride balls with diameters of 2, 5 and 8mm and a mass ratio of 1.6:3:1 as grinding media, use anhydrous ethanol as liquid phase, control the ball-to-material ratio to be 14:1, and the material-liquid ratio to be 1:4.7, and ball mill at 210rpm on a planetary ball mill for 12h. Then dry and granulate the resulting slurry to obtain MgAlON / CaCO3 mixed powder. Figure 2 and Figure 3 The SEM images and particle size distribution diagrams of the ball-milled MgAlON powders are shown in Figure 2. It can be seen that the ball-milled MgAlON powders have good dispersibility and a bimodal particle size distribution. 50 The particle size distribution range is 0.07-4.55 μm.

[0060] The ball-milled MgAlON powder was preformed at 50MPa and then cold isostatically pressed at 120MPa to obtain a green body. The green body was placed in a graphite mold and placed in a high-temperature sintering furnace. The temperature was raised to 1880℃ at 15℃ / min in a nitrogen atmosphere and kept for 150min. After cooling in the furnace, MgAlON ceramics were obtained. After double-sided grinding and polishing, MgAlON transparent ceramics were obtained. The relative density of the prepared MgAlON transparent ceramics is 99.79%, and its fracture morphology is shown in Figure 2. Figure 4 , transmittance curve and sample photos see Figure 5 It can be seen that: there is no obvious pore in the fracture, the ceramic has good light transmittance, and the maximum transmittance is 87.7%. At the same time, the hardness of the transparent ceramic is relatively high, HV = 16.94 ± 0.35 GPa.

[0061] Example 2

[0062] The difference between Example 2 and Example 1 is that the sintering aid for preparing MgAlON transparent ceramics is Y2O3. The relative density of the prepared MgAlON transparent ceramics is 99.40%, and its fracture morphology is shown in FIG. Figure 4 , transmittance curve and sample photos see Figure 5 It can be seen that: there is no obvious pore in the fracture, the ceramic has good light transmittance, and the maximum transmittance is 83.6%. At the same time, the hardness of the transparent ceramic is relatively high, HV = 15.73 ± 0.40 GPa.

[0063] Example 3

[0064] The difference between Example 3 and Example 1 is that the sintering temperature of the MgAlON transparent ceramic is 1850°C. The relative density of the prepared MgAlON transparent ceramic is 99.67%, and its fracture morphology is shown in FIG. Figure 6 , transmittance curve and sample photos see Figure 7 It can be seen that: there is no obvious pore in the fracture, the ceramic has good light transmittance, and the maximum transmittance is 85.4%. At the same time, the hardness of the transparent ceramic is relatively high, HV = 16.76 ± 0.25 GPa.

[0065] Example 4

[0066] The difference between Example 4 and Example 1 is that the sintering temperature of the MgAlON transparent ceramic is 1820°C. The relative density of the prepared MgAlON transparent ceramic is 99.61%, and its fracture morphology is shown in FIG. Figure 6 , transmittance curve and sample photos see Figure 7 It can be seen that: there is no obvious pore in the fracture, the ceramic has good light transmittance, and the maximum transmittance is 83.0%. At the same time, the hardness of the transparent ceramic is relatively high, HV = 16.77 ± 0.39 GPa.

[0067] Example 5

[0068] The difference between Example 5 and Example 1 is that the sintering temperature of the MgAlON transparent ceramic is 1790°C. The relative density of the prepared MgAlON transparent ceramic is 99.38%, and its fracture morphology is shown in FIG. Figure 6 , transmittance curve and sample photos see Figure 7 It can be seen that: there is no obvious pore in the fracture, the ceramic has good light transmittance, and the maximum transmittance is 81.0%. At the same time, the hardness of the transparent ceramic is relatively high, HV = 16.85 ± 0.10 GPa.

[0069] Example 6

[0070] The difference between Example 6 and Example 1 is that the sintering temperature of the MgAlON transparent ceramic is 1790°C and the holding time is 90 minutes. The relative density of the prepared MgAlON transparent ceramic is 99.65%, and its fracture morphology is shown in FIG. Figure 8 , transmittance curve and sample photos see Fig. 9 It can be seen that: there is no obvious pore in the fracture, the ceramic has good light transmittance, and the maximum transmittance is 84.5%. At the same time, the hardness of the transparent ceramic is relatively high, HV = 16.50 ± 0.12GPa.

[0071] Example 7

[0072] The difference between Example 7 and Example 1 is that the sintering temperature of the MgAlON transparent ceramic is 1790°C and the holding time is 30 minutes. The relative density of the prepared MgAlON transparent ceramic is 99.45%, and its fracture morphology is shown in FIG. Figure 8 , transmittance curve and sample photos see Fig. 9 It can be seen that: there is no obvious pore in the fracture, the ceramic has good light transmittance, and the maximum transmittance is 81.9%. At the same time, the hardness of the transparent ceramic is relatively high, HV = 16.46 ± 0.13 GPa.

Claims

1. A low-temperature rapid preparation method for MgAlON transparent ceramics with high infrared transmittance, characterized in that: The steps include: Step 1: 76-77wt.% γ-Al2O3, 13-14wt.% AlN and 9-9.6wt.% MgAl2O4 raw material powders are ball-milled and mixed, and then dried and granulated to obtain γ-Al2O3 / AlN / MgAl2O4 mixed powder, which is then subjected to a high temperature solid phase reaction method under a nitrogen atmosphere to obtain pure phase MgAlON powder; Step 2: Add a sintering aid to the pure phase MgAlON powder, ball mill and dry to obtain a MgAlON / sintering aid mixed powder, dry press to prepare a green body, then heat the green body to 1780-1900°C at 10-40°C / min in a nitrogen atmosphere and keep it at that temperature for 30-180min, and then cool it in the furnace to obtain MgAlON transparent ceramics.

2. The method according to claim 1, characterized in that: In step 1, the specific usage of the γ-Al2O3, AlN and MgAl2O4 raw material powders is 76.64wt.%, 13.84wt.% and 9.52wt.%.

3. The method according to claim 1, characterized in that: In step 2, the sintering aid is Y2O3 or CaCO3, and the dosage is 0.4-0.6wt.%.

4. The method according to claim 1, characterized in that: In step 2, the particle size of the MgAlON / sintering aid mixed powder is bimodal, with the two peaks being in the range of 0.4-0.7 μm and 1-2 μm, respectively. 50 The particle size is 0.8-1.0μm, and the particle size distribution range is 0.05-5.00μm.

5. The method according to claim 1, characterized in that: In step 1, the average particle size of the γ-Al2O3 powder is ≤40nm; the average particle size of the AlN powder is ≤1.5μm; the average particle size of the MgAl2O4 powder is ≤200nm, and it is prepared by a high-temperature solid phase reaction method of γ-Al2O3 and MgO, with a reaction temperature of ≤1300°C and a holding time of ≤120min.

6. The method according to claim 1, characterized in that: In step 1, the high temperature solid phase reaction method specifically comprises the following steps: loading the γ-Al2O3 / AlN / MgAl2O4 mixed powder into a graphite mold, heating the mixture to 1520-1620°C at a rate of 10-30°C / min in a nitrogen atmosphere and keeping the temperature for 15-45min, then heating the mixture to 1600-1700°C and keeping the temperature for 30-60min, and cooling the mixture with the furnace to obtain pure phase MgAlON powder.

7. The method according to claim 1, characterized in that: In the step 1, the raw material powders of γ-Al2O3, AlN and MgAl2O4 are ball-milled in anhydrous ethanol at 160-210 rpm using silicon nitride balls for 20-30 hours; in the step 2, the pure phase MgAlON powder and the sintering aid are ball-milled in anhydrous ethanol at 200-230 rpm using silicon nitride balls for 10-15 hours, wherein the diameters of the silicon nitride balls are 2, 5, and 8 mm, respectively, the mass ratio is 1.5-1.7:2-3:1, the ball-to-material ratio is 12-16:1, and the material-liquid ratio is 1:3-5.

8. The method according to claim 1, characterized in that: In the step 2, the MgAlON / sintering aid mixed powder is preformed by uniaxial pressing at 30-60 MPa, and then cold isostatic pressing at 100-180 MPa is performed to obtain a green body.

9. The method according to claim 1, characterized in that: The method comprises a post-processing step of grinding and polishing the obtained MgAlON transparent ceramic.

10. The MgAlON ceramic with high infrared transmittance prepared by the method according to any one of claims 1 to 9, characterized in that: The relative density of the MgAlON transparent ceramic is ≥99.38%, the infrared transmittance is 81.0-87.7%, and the hardness is 15-17 GPa.

Images