Perovskite nanocrystal@aluminum-based composite luminescent material and high-temperature preparation method thereof

Abstract

The application discloses a perovskite nanocrystal-aluminum-based composite luminescent material and a high-temperature preparation method thereof, characterized in that: raw material powder is used to prepare perovskite nanocrystals through in-situ reaction; the perovskite nanocrystal additive phase is mixed with an aluminum alloy matrix material through ball milling, cold pressing and forming, and hot-press sintering process; under sintering conditions of a heating temperature of 400-600 DEG C, a holding time of 30-120 min and a pressure of 10-50 MPa, a perovskite nanocrystal-aluminum-based composite luminescent material block is prepared; and the composite luminescent material can be prepared into a required size and structure through subsequent heat treatment and mechanical processing process. The perovskite nanocrystal-aluminum-based composite luminescent material can regulate the types of perovskite nanocrystals and matrix metal alloys, accurately control the proportion of perovskite nanocrystals in the composite material, realize the adjustment of fluorescent wavelength, and prepare aluminum-based composite luminescent materials with different functional properties, high temperature resistance and high stability. The perovskite nanocrystal-aluminum-based composite luminescent material has good application prospects in the fields of online detection of metal structure cracks, ray flaw detection and anti-counterfeiting encryption.

Description

Technical Field

[0001] This invention belongs to the technical field of metal composite luminescent materials, and relates to a high-temperature resistant and highly stable perovskite nanocrystal@aluminum-based composite luminescent material and its high-temperature preparation method. Background Technology

[0002] Luminescent materials are materials that, when excited by a certain amount of external energy, release energy in the form of photons as their ground-state electrons transition to an excited state and then return to the ground state. Common luminescent metallic materials include metal (gold, silver, platinum, copper) nanoclusters, rare-earth nanoluminescent materials, and metal-organic framework luminescent materials. Unlike these luminescent materials, composite luminescent materials, which combine two or more solid-phase materials, retain the original physical and chemical properties of each component while leveraging the material's advantages through a "synergistic effect." This results in multifunctional composite materials with optical, electrical, and magnetic properties, thereby expanding their applications.

[0003] Perovskite nanocrystals possess advantages such as long carrier lifetime, high carrier mobility, tunable bandgap, high fluorescence quantum efficiency, low cost, and ease of synthesis, making them one of the most competitive new optoelectronic materials currently available. However, the low formation energy and ionic properties of perovskite nanocrystals make them highly sensitive to temperature, oxygen, and humidity. This poor structural and environmental stability is a major obstacle limiting their further development. Therefore, combining or encapsulating perovskite with other materials to improve its stability is crucial.

[0004] Currently, the encapsulation matrix materials used to improve the stability of perovskite nanocrystals mainly include polymer matrices and transparent glass inorganic matrices. Inkjet printing technology can be used to directly spray perovskite precursors or inks into liquid polyvinylpyrrolidone (PVP) or polydimethylsiloxane (PDMS) polymer matrices to prepare perovskite@polymer matrix composites, forming high-resolution perovskite patterns embedded in different polymer matrices. These patterns are used to create anti-counterfeiting labels, painted designs, and large-area fluorescent billboards. (Yang Liu, et.al., ACS Nano, 2019,13,2042-2049; Zhenkun Gu, et.al.,ACS Appl. Mater. Interfaces, 2020,12, 22157-22162) Furthermore, Huang et al. used femtosecond lasers to micro-process transparent materials, such as glass or single crystals, to print three-dimensional perovskite patterns. (Xiongjian Huang, et.al., ACS Nano, 2020, 14, 3150-3158) Thanks to the sealing function of transparent glass, patterned perovskite@glass matrix composites exhibit excellent moisture resistance, light resistance, and chemical resistance to various solvents, showing potential application prospects in fields such as 3D display, information storage, information encryption and decryption.

[0005] While perovskite@polymer matrix composites exhibit excellent water resistance, they suffer from poor thermal stability. At relatively high temperatures, the polymer matrix degrades, leading to fluorescence quenching. Transparent glass inorganic matrices possess strong mechanical strength and high heat resistance, but are typically brittle and easily broken. In contrast, metallic materials generally possess high strength, heat resistance, and good toughness. Combining perovskite nanocrystals with a metallic matrix to prepare luminescent metallic composites possesses both the photoluminescence properties of perovskite and retains the high-temperature resistance and good strength and toughness of the metallic matrix. This has potential applications in areas such as crack propagation detection in fluorescent metallic composite structures, flaw detection in medical metal implants, and embedding anti-counterfeiting tracking codes in important metal components. Summary of the Invention

[0006] The purpose of this application is to provide a perovskite nanocrystal@aluminum-based composite luminescent material and its high-temperature preparation method, which can achieve good luminescence effect and stability, and has good processability.

[0007] This invention generates metal halide perovskite nanocrystals via an in-situ reaction method and prepares uniformly dispersed perovskite nanocrystal@aluminum-based composite luminescent functional materials using powder metallurgy. This metal-based composite material exhibits photofluorescence under infrared or ultraviolet light irradiation. The protective composite structure significantly improves the fluorescence stability of the metal halide perovskite under high temperature and atmospheric conditions. By adjusting the elemental composition of the perovskite material, the emission wavelength range can be expanded to cover the ultraviolet, visible, and near-infrared regions. The prepared metal halide perovskite nanocrystal@aluminum-based composite luminescent material can be used to embed colored anti-counterfeiting tracking codes or fluorescent patterns on metal surfaces, enabling real-time monitoring of internal cracks and defects in in-service metal components, or for flaw detection of medical metal implants.

[0008] To achieve the above objectives, the technical solution proposed by this invention is as follows: A perovskite nanocrystal@aluminum-based composite luminescent material and its high-temperature preparation method include the following steps: S1: Composition design and formulation of metal halide perovskite precursor powder and aluminum alloy powder; S2: Ball milling and pretreatment process for metal halide perovskite nanocrystals@aluminum-based composite powder; S3: Cold pressing process for metal halide perovskite nanocrystals@aluminum-based composite powder. S4: Hot pressing sintering technology for metal halide perovskite nanocrystals@aluminum matrix composites; S5: For aluminum alloy matrix materials of the 3, 6 and 7 series that can be strengthened by heat treatment through solution quenching and aging, the sintered specimens are subjected to solution aging heat treatment to improve the mechanical properties of the composite material structure.

[0009] Further, in step S1, the additive for the functional aluminum-based composite material is a metal halide perovskite ABX3, where A is cesium (Cs), B is lead (Pb) or tin (Sn), and X is chlorine (Cl), bromine (Br), or iodine (I). The metal halide perovskite is generated by subsequently ball milling and mixing the corresponding raw material powders, cold pressing, and then reacting in situ under heat and pressure in a hot pressing sintering furnace.

[0010] Furthermore, in step S1, when the additive used is CsPbBr3 perovskite, according to the reaction equation Cs2CO3+2PbBr2+2NaBr→2CsPbBr3+Na2CO3, the molar mass ratio of the raw material powder is 1:2:2-1:4:4 of Cs2CO3, PbBr2, and NaBr, or according to the reaction equation CsBr+PbBr2→CsPbBr3, the molar mass ratio of the raw material powder is 1:1-1:4 of CsBr and PbBr2.

[0011] Furthermore, in step S1, the aluminum alloy matrix powder includes 1-series to 7-series aluminum alloy powders with a particle size of 5-100 μm.

[0012] Furthermore, in step S1, the content of metal halide perovskite additives in the aluminum matrix alloy is 1-20% by mass.

[0013] Furthermore, in step S2, after mixing the metal halide perovskite raw material powder and aluminum alloy powder in a predetermined ratio, in order to prevent the aluminum alloy from sticking together and the composite powder from sticking to the wall of the ball milling jar, 1-5% by mass of stearic acid is added as a process control agent, placed in the ball milling jar, vacuumed, and then filled with argon gas for ball milling.

[0014] Furthermore, in step S2, the grinding balls are stainless steel balls with a diameter of 1-10mm, the filling coefficient of the ball mill is 0.4-0.5, the ball-to-material ratio during ball milling ranges from 1:1 to 20:1, the rotation speed of the ball mill cylinder is 100-500rpm, and the ball milling time is 4-24 hours.

[0015] Furthermore, in step S2, after ball milling, the composite powder is placed in a vacuum furnace, vacuumed, heated to 100-200°C, and dried for 1-5 hours.

[0016] Furthermore, in step S3, the ball-milled metal halide perovskite-added aluminum alloy composite powder is pressed in a steel die of a hydraulic press by a die punch. The pressing pressure is 5-20 MPa, and the pressing time is 5-30 min. After depressurization, the compact is taken out from the female die.

[0017] Further, in step S4, the metal halide perovskite precursor powder and aluminum alloy powder are cold-pressed into a part, which is then covered with carbon paper, placed in a graphite mold, and placed in a hot-pressing sintering furnace. After evacuation, argon gas is introduced for hot-pressing sintering. The argon protective gas flow rate is 5-20 L / min.

[0018] Furthermore, in step S4, the sintering process is characterized by a heating rate of 5-20°C / min, a heating temperature of 400-600°C, a holding time of 30-120min, a pressure of 10-50MPa, and furnace cooling to room temperature after sintering.

[0019] Furthermore, in step S5, after grinding the metal halide perovskite-added aluminum matrix composite sample, it is placed in a vacuum heat treatment resistance furnace for solution aging treatment.

[0020] Furthermore, in step S5, the solution aging process is as follows: the solution treatment heating temperature range is 500-600°C, the holding time is 30-120 min, after quenching, the aging temperature range is 100-200°C, the holding time is 5-20 h, and then air-cooled to room temperature.

[0021] Compared with the prior art, the advantages of the present invention are as follows: (1) The present invention prepares a fluorescent functional aluminum-based composite material by uniformly dispersing perovskite nanocrystals in an aluminum alloy matrix, which is suitable for processing into metal bulk light-emitting structural components of different sizes and shapes.

[0022] (2) The perovskite nanocrystal@aluminum-based composite luminescent material prepared by the present invention has the advantages of high strength, good toughness and high temperature resistance of aluminum alloy matrix compared with resin matrix and glass matrix, while maintaining the good fluorescence characteristics of perovskite nanocrystal. The synergistic composite effect of the two materials gives the perovskite nanocrystal encapsulated in aluminum alloy matrix good high temperature resistance, which can withstand high temperatures below 600°C. The perovskite nanocrystal@aluminum-based composite bulk structure is not prone to fluorescence quenching when stored in air for a long time, and is suitable for metal parts that require both fluorescence and structural functions.

[0023] (3) The raw materials do not contain precious metals, rare metals, or rare earth elements, resulting in low cost. The preparation process, which combines in-situ reaction with powder metallurgy technology, is simple and easy to implement, and the prepared composite material has a uniform structure and stable properties. The preparation method is reproducible and reliable, has universality, and can be extended to other perovskite and metal matrix components.

[0024] (4) By changing the elemental composition of perovskite ABX3, its fluorescence wavelength can be covered in the full band from ultraviolet to infrared. It can be combined with different metal materials to prepare metal matrix composites with different properties. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention.

[0026] Figure 1 The macroscopic sample morphology of the 10wt.% CsPbBr3@6061Al composite material in Example 1 of this invention under white light and ultraviolet light irradiation. Figure 2 The macroscopic morphology of the 6061Al alloy sample under white light and ultraviolet light irradiation in Comparative Example 1 of this invention is shown below. Figure 3 This is a transmission electron microscope (TEM) image of the 10 wt.% CsPbBr3@6061Al composite material in Example 1 of this invention. Figure 4 These are X-ray diffraction (XRD) comparison curves of the 10wt.% CsPbBr3@6061Al composite material and 6061Al alloy sample in Example 1 and Comparative Example 1 of this invention. Figure 5 These are the fluorescence (PL) spectra of the 10 wt.% CsPbBr3@6061Al composite material and 6061Al alloy sample in Example 1 and Comparative Example 1 of this invention. Figure 6 These are comparative curves of the microhardness properties of the 10wt.% CsPbBr3@6061Al composite material and the 6061Al alloy sample in Example 1 and Comparative Example 1 of this invention. Figure 7 Transmission electron microscopy (TEM) images of CsPbBr3 nanocrystals prepared by solution method in Comparative Example 2 Figure 8 XRD composition curves of CsPbBr3 nanocrystals prepared by solution method in Comparative Example 2 Figure 9 Metallographic images of the 10wt.% CsPbBr3@6061Al composite materials prepared in Comparative Example 3 and Example 1. Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0028] Example 1 In a specific embodiment 1, the present invention prepared a CsPbBr3@6061 functional aluminum-based composite luminescent material with a mass percentage of 10%, and provided a method for its preparation, including the following steps: (1) Using Cs2CO3, PbBr2, and NaBr in a molar ratio of 1:2:2 as raw material powders, CsPbBr3 perovskite nanocrystals were generated through in-situ reaction according to the equation Cs2CO3 + 2PbBr2 + 2NaBr = 2CsPbBr3 + Na2CO3. In the experiment, 19.08g of Cs2CO3, 31.65g of PbBr2, and 8.8g of NaBr were weighed using an electronic balance. Subsequently, the mixture was ball-milled, cold-pressed, and placed in a hot-pressing sintering furnace for in-situ reaction, which produced 50g of CsPbBr3 perovskite.

[0029] (2) The aluminum alloy matrix powder is 450g of 6061 aluminum alloy powder with a particle size of 5-45μm.

[0030] (3) The amount of metal halide perovskite nanocrystals added to the aluminum matrix powder is 10% by mass.

[0031] (4) The experiment adopted the ball milling powder mixing process. 19.08g of CsPbBr3 metal halide perovskite precursor powder, 31.65g of Cs2CO3, 8.8g of PbBr2, and 450g of 6061 aluminum alloy powder were mixed with 1% stearic acid by mass, placed in a ball mill jar, evacuated, and then filled with argon gas for ball milling. The grinding balls were made of stainless steel, the ball-to-material ratio was 3:1, the rotation speed was 250 rpm, the ball milling time was 24 hours, the grinding balls were stainless steel balls with a diameter of 8mm, and the filling coefficient of the ball mill was 0.5.

[0032] (5) After ball milling, place the composite powder in a vacuum furnace, heat it to 120°C, and dry it for 1 hour.

[0033] (6) The mixed metal halide perovskite-aluminum-based composite powder is placed into a dry pressing mold and pressed into tablets using a hydraulic press. The pressing pressure is 12 MPa, and the pressure holding time is 5 min. After depressurization, the pressed tablet is removed from the die.

[0034] (7) After the CsPbBr3 metal halide perovskite aluminum-based composite material is covered with carbon paper, it is placed in a graphite mold, vacuumed, and then argon is introduced as a protective gas with a flow rate of 20 L / min. Hot pressing sintering is carried out in an inert atmosphere. The sintering process is as follows: heating rate 5°C / min, heating temperature 540°C, holding time 60 min, pressure 30 MPa. After sintering, the furnace is cooled to room temperature.

[0035] Comparative Example 1 To better illustrate the technical solution of the present invention, a comparative example of the present invention provides a powder metallurgy preparation method for 6061Al alloy, comprising the following steps: (1) 500g of 6061 aluminum alloy powder with a particle size of 5-45μm was mixed with 1% stearic acid by ball milling in a ball mill jar. After vacuuming, argon gas was introduced for ball milling. The grinding balls were made of stainless steel. The ball-to-material ratio was 3:1, the rotation speed was 250rpm, and the ball milling time was 24 hours. The grinding balls were stainless steel balls with a diameter of 8mm, and the filling coefficient of the ball mill was 0.5.

[0036] (2) After ball milling, place the aluminum alloy powder in a vacuum furnace, heat it to 120°C, and dry it for 1 hour.

[0037] (3) Place the aluminum alloy powder into a dry pressing mold and press it into sheets using a hydraulic press. The pressing pressure is 12 MPa, and the pressure holding time is 5 min. After depressurization, the pressed blank is removed from the female mold.

[0038] (4) Place the 6061 aluminum alloy material sheet into a graphite mold, evacuate the vacuum, and then purge with argon as a protective gas. The protective gas flow rate is 20L / min. Hot pressing sintering is carried out in an inert atmosphere. The sintering process is: heating rate 5°C / min, heating temperature 540°C, holding time 60min, pressure 30MPa. After sintering, the furnace is cooled to room temperature.

[0039] To better illustrate the characteristics of the perovskite nanocrystal@aluminum-based composite luminescent material provided in the embodiments of the present invention, the samples provided in Example 1 and Comparative Example 1 were tested below. The macroscopic morphology and fluorescence characteristics of the test samples under white light and ultraviolet light irradiation, and the perovskite nanostructure under transmission electron microscopy (TEM) were observed; the composition and phase composition of the samples were measured using X-ray diffraction (XRD); and the fluorescence characteristics and mechanical properties of the samples were measured using fluorescence spectroscopy (PL) and a microhardness tester. The results are as follows: (1) Figure 1 The macroscopic morphology of the functional 6061Al composite material sample with a mass fraction of 10% CsPbBr3 perovskite added, obtained by in-situ reaction combined with powder metallurgy sintering in Example 1, is shown under white light and 365nm ultraviolet light irradiation. Comparative Example 1 shows the macroscopic morphology of the 6061Al matrix sample under the same preparation process conditions under white light and 365nm ultraviolet light irradiation, with reference to... Figure 2 Both samples exhibited a silvery metallic luster under white light irradiation. However, under ultraviolet light irradiation, the 10wt.%CsPbBr3@6061Al composite material produced bright green fluorescence, indicating that uniformly and diffusely distributed CsPbBr3 perovskite fluorescent nanocrystals had formed in situ in the 6061Al alloy matrix under the experimental conditions of Example 1, while the 6061Al matrix sample did not produce fluorescence under ultraviolet light irradiation.

[0040] (2) Figure 3 The image shows the morphology and diffraction pattern of the 10wt.% CsPbBr3@6061Al composite material under a transmission electron microscope in Example 1 of this invention. It can be seen that there are a large number of bright white particles with a size of less than 20nm in the composite material under the transmission electron microscope. Through high-resolution and diffraction pattern analysis, it can be determined that the material is CsPbBr3 perovskite nanocrystals, which confirms the formation of CsPbBr3 perovskite nanocrystals in the aluminum-based composite material under the conditions of Example 1.

[0041] (3) Figure 4The XRD comparison curves of the 10wt.% CsPbBr3@6061Al composite material and the 6061Al alloy in Example 1 and Comparative Example 1 are shown. XRD data analysis reveals that the main phase composition in both materials is α-Al solid solution. Furthermore, the 10wt.% CsPbBr3@6061Al composite material also contains elemental lead and trace amounts of reactive phases such as CsPbBr3, Cs4PbBr6, and CsPb2Br5, further confirming that a mixed phase of cesium, lead, and bromine is formed in the aluminum matrix through in-situ reaction of the precursor components.

[0042] (4) Figure 5 The figures show the photoluminescence spectra of the 10wt.%CsPbBr3@6061Al composite material and the 6061Al alloy obtained in Example 1 and Comparative Example 1. As shown, the 6061Al matrix sample exhibits no photoluminescence, but due to the strong metallic luster and reflectivity of the aluminum alloy, the curve shows some fluctuations and is not entirely horizontal. The 10wt.%CsPbBr3@6061Al composite material sample, however, shows a sharp green fluorescence emission peak at 520 nm with an emission half-slit width of 25 nm. This is mainly due to the photoluminescence effect of the CsPbBr3 perovskite material in the aluminum alloy matrix, demonstrating that the 10wt.%CsPbBr3@6061Al composite material bulk structure prepared by the method in Example 1 can emit fluorescence on its surface under ultraviolet excitation.

[0043] (5) Figure 6 The figure shows the microhardness curves of the 10wt.% CsPbBr3@6061Al composite material and the 6061Al alloy obtained in Example 1 and Comparative Example 1. As can be seen from the figure, the microhardness fluctuation range of the 6061Al alloy at the ten test points is 46.1-50.9 HV. 0.1 Its average microhardness is 46.9 HV. 0.1 The microhardness of the 10wt.% CsPbBr3@6061Al composite material ranges from 46.3 to 134.6 HV due to the presence of cesium lead bromine nanocrystals. 0.1 The values ​​fluctuate considerably, with an average microhardness of 76.1 HV. 0.1 The microhardness of the 6061Al alloy obtained in Comparative Example 1 is 62.3% higher.

[0044] The experimental results show that this invention synthesizes uniformly dispersed cesium lead bromine calcium titanium nanocrystals at high temperature using an in-situ reaction method combined with powder metallurgy technology, and then encapsulates them in a 6061 aluminum alloy matrix to prepare a functional aluminum-based composite luminescent material. Compared with 6061 aluminum alloy, the 10wt.%CsPbBr3@6061Al composite material exhibits significant photoluminescence properties, showing a fluorescence emission peak at a wavelength of 520nm under ultraviolet light irradiation, exhibiting green fluorescence. The prepared fluorescent functional metal matrix composite material has potential applications in fields such as metal anti-counterfeiting codes, fluorescent displays, and X-ray flaw detection.

[0045] Comparative Example 2 To better illustrate the technical solution of the present invention, Comparative Example 2 of the present invention provides a commonly used method for preparing perovskite nanocrystals and thin films, and prepares CsPbBr3@6061Al composite material by mixing the perovskite nanocrystals obtained by the solution method with 6061Al alloy powder by an external addition method, including the following steps: (1) The preparation method of perovskite nanocrystals is as follows: a) Dissolve 0.367 g of PbBr2 in 0.5 ml of octadecene (ODE), 1 ml of oleic acid (OA) and 1.5 ml of oleylamine (OAM) solution, and keep at 120 °C for one hour until PbBr2 is completely dissolved; b) Dissolve 0.16 g of CsCo3 in 1 ml of OA and 16 ml of ODE solution, and keep at 120 °C for one hour until CsCo3 is completely dissolved; c) Mix the two fully dissolved solutions, stir magnetically at 1000 rpm, transfer to a cold water bath to cool, and centrifuge the cooled solution at 6000 rpm for 15 minutes; d) Disperse the precipitate in 20 ml of cyclohexane, sonicate for 15 minutes, and after sonication, dilute with cyclohexane at a ratio of 1:4 to obtain a 0.001 mol Cs4PbBr6 solution. A diluted Cs4PbBr6 cyclohexane solution was mixed with water at a ratio of 1:0.2 and magnetically stirred at 1000 rpm to obtain a CsPbBr3 cyclohexane solution. The solution was then placed in a vacuum drying oven and dried under vacuum at 100°C for 8 hours to obtain approximately 0.58 g of CsPbBr3 perovskite nanocrystal powder. The above steps were repeated to obtain a total of approximately 5 g of CsPbBr3 perovskite nanocrystals. (2) Ball milling and mixing of perovskite nanocrystals and aluminum powder. The perovskite nanocrystals prepared by the above method were dissolved in toluene and uniformly sprayed into 45g of aluminum powder, accounting for approximately 10% by mass. The mixture was then vacuum dried at 120℃ for 12h to allow the toluene to completely evaporate. 1% stearic acid was added for dry ball milling. The ball mill jar was evacuated and then purged with argon gas. The mass ratio of powder to ball was 1:1, the ball mill speed was 300rpm, the ball milling time was 10min followed by a 15min interval, and the total ball milling time was 4h.

[0046] (3) The composite powder of CsPbBr3 and 6061Al was placed in a crucible and heated in an inert gas furnace at 540°C for 5 seconds. The protective gas was argon with a flow rate of 20 L / min.

[0047] The sample provided in Comparative Example 2 was analyzed. The transmission electron microscopy morphology and XRD composition of the perovskite nanocrystals prepared by the solution method were examined. The fluorescence behavior of the prepared CsPbBr3 / 6061Al composite powder was observed after and after heating under ultraviolet light. The conclusions are as follows: (1) Figure 7 The image shows the microstructure of CsPbBr3 nanocrystals prepared by solution method in Example 2 under a transmission electron microscope. It can be seen that the CsPbBr3 nanocrystals are mostly regular blocky grains with a size between 10-40 nm. Combined with... Figure 8 XRD compositional analysis showed that the composition of the bulk grains matched well with that of CsPbBr3 perovskite. This indicates that the experimental conditions of Example 2 can yield good CsPbBr3 nanocrystals.

[0048] (2) After mixing CsPbBr3 nanocrystals with 6061Al powder by external addition, the fluorescence characteristics of the composite powder before and after heating in a heat treatment furnace were observed under ultraviolet light. The mixed powder had good green fluorescence characteristics before heating, but the fluorescence characteristics of the composite powder were quenched after only 5s of heating at 540℃.

[0049] The above test results show that it is not feasible to prepare CsPbBr3 nanocrystals@6061Al composite material by preparing perovskite nanocrystal powder or film by traditional solution method and then mixing it with aluminum alloy powder by external method. The main problems are as follows: (a) Compared with the in-situ reaction method for preparing CsPbBr3 nanocrystals proposed in this patent, the solution method for preparing CsPbBr3 nanocrystals is complicated and the content prepared in a single batch is small. It takes about 100 days to prepare the 50g of CsPbBr3 nanocrystals required for the experiment; (b) The composite powder obtained by mixing CsPbBr3 nanocrystals with 6061Al by external method has poor protection effect. The composite powder undergoes fluorescence quenching phenomenon in a short time under high temperature, and it is impossible to obtain luminescent composite material. The original method proposed in this patent is a reaction-combined powder metallurgy method, which involves mixing CsPbBr3 raw material powder with aluminum alloy powder. During the sintering process, Cs2CO3, PbBr2, and NaBr raw material powders react in situ within the sintered and dense aluminum alloy matrix to generate CsPbBr3 nanocrystals. The CsPbBr3 nanocrystals are encapsulated within the aluminum alloy matrix, preventing oxidation and volatilization. This method yields a CsPbBr3@6061Al composite luminescent material in which CsPbBr3 nanocrystals are uniformly dispersed within the aluminum matrix.

[0050] Comparative Example 3 To better illustrate the technical solution of the present invention, Comparative Example 3 of the present invention provides a process for preparing a composite material by mixing perovskite raw material powder with 6061Al alloy powder and then using an in-situ reaction combined with melting method, including the following steps: (1) The raw material powders Cs2CO3, PbBr2, and NaBr are mixed in a molar ratio of 1:2:2. According to the reaction equation Cs2CO3 + 2PbBr2 + 2NaBr = 2CsPbBr3 + Na2CO3, when 19.08g of Cs2CO3, 31.65g of PbBr2, and 8.8g of NaBr are used, 50g of CsPbBr3 nanocrystals can be generated through in-situ reaction. The aluminum alloy matrix powder is 450g of 6061 aluminum alloy powder with a particle size of 5-45μm. The amount of metal halide perovskite added to the aluminum matrix powder is 10% by mass.

[0051] (2) The experiment used ball milling to mix the powders. CsPbBr3 metal halide perovskite precursor powder was mixed with aluminum alloy powder, and then 1% stearic acid was added. The mixture was placed in a ball mill jar, evacuated, and then filled with argon gas for ball milling. The grinding balls were made of stainless steel, and the ball-to-material ratio was 1:3, the rotation speed was 250 rpm, and the ball milling time was 24 hours. The mixed metal halide perovskite-aluminum-based composite powder was placed in a dry pressing mold and pressed into tablets using a hydraulic press.

[0052] (3) Preparation process of CsPbBr3 metal halide perovskite aluminum-based composite powder by melting. The inert atmosphere protected melting method is adopted. The pressed metal halide perovskite aluminum-based composite powder is placed in a quartz crucible and placed in an inert atmosphere protected tube furnace. The protective gas is argon with a flow rate of 20 L / min. The furnace is heated to 800°C, held for 60 minutes, and then removed and air-cooled to room temperature.

[0053] The samples prepared by the smelting method in Comparative Example 3 and the samples prepared by the powder metallurgy method in Example 1 were cut, inlaid, ground, and polished to obtain metallographic photographs as shown below. Figure 9As shown in the metallographic photographs of the CsPbBr3@6061Al composite material prepared by the melting method, the 6061Al alloy powder retains its original spherical particle morphology. Due to the coating effect of the oxide film on the surface of the aluminum alloy powder, heating alone cannot break the oxide film. The 6061Al alloy coated with the oxide film only undergoes high-temperature melting and maintains its original morphology during cooling. After high-temperature melting, the 6061Al alloy powder simply piles together without achieving effective bonding. The cooled sample is brittle and easily breaks. When prepared by powder metallurgy, under ball milling conditions, the CsPbBr3 raw material powder can be fully mixed and uniformly dispersed in the aluminum powder. Under the combined action of high temperature and pressure, the oxide film on the surface of the 6061Al alloy powder particles is crushed. Under long-term heat preservation conditions, the broken oxide film diffuses into the matrix. Through long-term grain boundary migration and grain recrystallization, diffusion bonding occurs between the composite powder particles, finally obtaining a dense CsPbBr3@6061Al composite material sample with good strength and toughness.

[0054] The above description is only a preferred embodiment of the present invention and related comparative examples, and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature preparation method for a perovskite nanocrystal@aluminum-based composite luminescent material, characterized in that, Includes the following steps: S1: Composition design and proportioning of metal halide perovskite precursor powder and aluminum alloy powder. When the metal halide perovskite precursor powder used is CsPbBr3 perovskite, according to the reaction equation Cs2CO3+2PbBr2+2NaBr→2CsPbBr3+Na2CO3, the molar mass ratio of raw material powders is 1:2:2-1:4:4 of Cs2CO3, PbBr2, and NaBr, or according to the reaction equation CsBr+PbBr2→CsPbBr3, the molar mass ratio of raw material powders is 1:1-1:4 of CsBr and PbBr2. The aluminum alloy matrix powder includes 1-series to 7-series aluminum alloy powders with a particle size of 5-100 μm; the content of metal halide perovskite precursor powder in the aluminum matrix alloy is 1-20% by mass. S2: Ball milling and pretreatment process for metal halide perovskite nanocrystals@aluminum-based composite powder; S3: Cold pressing process for metal halide perovskite nanocrystals@aluminum-based composite powder. S4: Hot pressing sintering technology for metal halide perovskite nanocrystals@aluminum matrix composites; S5: For some heat-treatable aluminum alloy matrix materials, solution aging heat treatment is performed on sintered specimens to improve the mechanical properties of composite material structures.

2. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S1, metal halide perovskite is generated by mixing the corresponding raw material powders through ball milling, cold pressing, and in-situ reaction under heat and pressure in a hot pressing sintering furnace.

3. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S2, metal halide perovskite raw material powder and aluminum alloy powder are mixed in a predetermined ratio. To prevent the aluminum alloy from sticking together and the composite powder from sticking to the wall of the ball milling jar, 1-5% stearic acid by mass is added as a process control agent. The mixture is placed in the ball milling jar, evacuated, and then filled with argon gas for ball milling.

4. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S2, the grinding balls are stainless steel balls with a diameter of 1-10mm, the filling coefficient of the ball mill is 0.4-0.5, the ball-to-material ratio during ball milling ranges from 1:1 to 20:1, the rotation speed of the ball mill cylinder is 100-500rpm, and the ball milling time is 4-24 hours.

5. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S2, after ball milling, the composite powder is placed in a vacuum furnace, vacuumed, heated to 100-200℃, and dried for 1-5 hours.

6. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S3, the ball-milled metal halide perovskite-aluminum alloy composite powder is pressed in a steel die of a hydraulic press by a die punch. The pressing pressure is 5-20 MPa, and the pressing time is 5-30 min. After the pressure is released, the compact is taken out from the female die.

7. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S4, metal halide perovskite precursor powder and aluminum alloy powder are cold-pressed into parts, which are then covered with carbon paper, placed in a graphite mold, placed in a hot-pressing sintering furnace, evacuated, and filled with argon gas for hot-pressing sintering.

8. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S4, the flow rate of argon protective gas is 5-20 L / min.

9. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S4, the sintering process is as follows: heating rate 5-20℃ / min, heating temperature 400-600℃, holding time 30-120min, pressure 10-50MPa, and furnace cooling to room temperature after sintering.

10. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S5, after grinding the metal halide perovskite nanocrystal @ aluminum matrix composite material sample, it was placed in a vacuum heat treatment resistance furnace for solution aging treatment.

11. The high-temperature preparation method of the perovskite nanocrystal@aluminum-based composite luminescent material as described in claim 1, characterized in that... In S5, the solution aging process is as follows: the solution treatment heating temperature range is 500-600℃, the holding time is 30-120min, after quenching, the aging temperature range is 100-200℃, the holding time is 5-20h, and then air-cooled to room temperature.

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