High reflectivity alumina ceramic substrate and preparation method and application thereof

Abstract

The application discloses a high-reflectivity alumina ceramic substrate and a preparation method and application thereof, and relates to the technical field of ceramic materials.The high-reflectivity alumina ceramic substrate comprises an alumina ceramic substrate and a zirconia nano-porous film structure formed on the surface of the substrate, the porosity of the zirconia nano-porous film structure is 4-10%, and the pore size is 100nm-1000nm.The high-reflectivity alumina ceramic substrate of the application prepares the zirconia nano-porous film structure on the dense alumina ceramic substrate, thereby significantly improving the light reflectivity of the alumina ceramic substrate and ensuring a certain bending strength.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and more specifically, to a high-reflectivity alumina ceramic substrate, its preparation method, and its application. Background Technology

[0002] Alumina ceramic substrates possess excellent corrosion resistance, chemical stability, high fracture toughness, and flexural strength, and are widely used in the luminescent materials industry, as well as in advanced industrial fields such as high-power electric vehicles, aerospace, and military applications. However, for the same luminous flux, a low light reflectivity of the alumina ceramic substrate necessitates mounting more LED chips. More chips not only increase LED production costs but also lead to significant heat loss, placing higher demands on the substrate's heat dissipation and hindering the manufacture of high-performance LED circuit boards. Therefore, reducing the absorption of light into heat and minimizing light refraction that becomes ineffective through the substrate, thereby improving the light reflectivity of the alumina ceramic substrate and ultimately enhancing the overall luminous efficacy of LEDs, is a pressing issue that needs to be addressed.

[0003] Existing technology discloses a high-reflectivity alumina ceramic substrate, wherein the alumina ceramic substrate comprises a core-shell structure of doped zirconium oxide@sintering aid; the core-shell structure of zirconium oxide@sintering aid forms a grain boundary complex phase of the alumina ceramic, the grain boundary complex phase comprising a core layer and a shell layer enclosing the core layer. This existing technology increases the light reflectivity of the substrate by doping alumina with a zirconium oxide@sintering aid core-shell structure to form a grain boundary complex phase with a core-shell structure, utilizing the refractive index difference between the alumina, the core, and the shell. However, its final reflectivity can only reach 96.5%, and the effect of improving reflectivity is limited. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and deficiencies of existing alumina ceramic substrates, such as low light reflectivity and low overall LED luminous efficiency, and to provide a high-reflectivity alumina ceramic substrate. By forming a special nanoporous film on the substrate material, the light reflectivity of the alumina ceramic substrate is significantly improved. Moreover, the nanoporous film improves the surface condition of the ceramic substrate, thereby ensuring the bending strength of the alumina ceramic substrate and avoiding the problem of substrate fragility during assembly.

[0005] Another object of the present invention is to provide a method for preparing a high-reflectivity alumina ceramic substrate.

[0006] Another object of the present invention is to provide an application of a high-reflectivity alumina ceramic substrate in the preparation of a luminescent material encapsulation structure.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution:

[0008] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface.

[0009] The porosity of the zirconia nanoporous film structure is 4-10%, and the pore size is 100-1000 nm.

[0010] It should be noted that:

[0011] The alumina ceramic substrate of the present invention is preferably alumina with a purity of 96% and a density of 3.82-3.85 g / cm³. 3 The thickness is a conventional thickness in this field, for example, it can be 1 mm.

[0012] In specific embodiments, the porosity of the zirconia nanoporous film structure of the present invention can be, for example, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0013] Preferably, the porosity of the zirconia nanoporous film structure is 4.9–9.2%.

[0014] Preferably, the pore size of the zirconia nanoporous film structure is 100-500 nm.

[0015] In the high-reflectivity alumina ceramic substrate of the present invention:

[0016] ①Nanoporous films increase the effective interface on the surface. The large difference in refractive index at the air-film interface helps to improve reflection.

[0017] ② The scattering effect caused by the zirconia nanostructure in the zirconia nanoporous film structure can increase diffuse reflection and improve the amount of reflection;

[0018] ③ The porous nanostructure increases the optical path, and the light undergoes multiple reflections between the layers, which can increase the reflection probability;

[0019] ④ Zirconia nanoporous film structure has a low dielectric constant (the dielectric constant of dense structure is between 9 and 11, while the dielectric constant of porous structure is about 6 to 8. The dielectric constant characterizes the charge storage capacity. Light and electricity have many similar characteristics. The weak charge storage capacity can be interpreted as the weak light storage capacity of porous structure), which is beneficial for suppressing reflection loss.

[0020] Therefore, preparing nanoporous thin film structures on dense alumina ceramic substrates helps to improve reflectivity, thereby improving the luminous efficiency of COB-encapsulated light sources on ceramic substrates.

[0021] The alumina ceramic substrate comes out of the sintering furnace without surface processing, and its surface is relatively rough. The zirconium oxide nanoporous film is applied to the alumina ceramic substrate, which is equivalent to the zirconium oxide filling the pits or microcracks on the surface of the alumina ceramic substrate, reducing the surface defects of the alumina ceramic substrate. Under external force, it helps to block the propagation of cracks and improve its mechanical strength. The nanopores of the film layer can effectively absorb fracture energy, thereby improving the mechanical strength of the ceramic and effectively improving the phenomenon of easy breakage during packaging and assembly.

[0022] In a specific embodiment, preferably, the thickness of the zirconia nanoporous film structure is 50-200 nm. For example, it can be 50 nm, 100 nm, 150 nm, and 200 nm.

[0023] Increasing the thickness of the zirconia nanoporous film structure is beneficial for improving porosity and thus reflectivity. However, it can also reduce the strength of the high-reflectivity alumina ceramic substrate. This invention controls the thickness of the nanoporous film between 50-200 nm, which helps control the overall defects of the high-reflectivity alumina ceramic substrate, inhibits crack propagation, and thus ensures the strength of the ceramic substrate while simultaneously improving reflectivity.

[0024] In a specific embodiment, preferably, the refractive index of the zirconium oxide nanoporous film structure is 2.2 to 2.5.

[0025] Zirconia thin films prepared at room temperature have zirconia grain sizes between 100-500 nm and 80-400 nm after phase transformation. The ZrO2 in the porous film is a nanostructure (refractive index of about 2.25).

[0026] Furthermore, when the precursor used to deposit the monoclinic zirconia film contains yttrium, the resulting Y₂O₃-doped ZrO₂ zirconia (refractive index 2.28) is obtained. The ZrO₂ nanostructure or the Y₂O₃-doped ZrO₂ nanostructure helps to improve the light reflectivity of the alumina ceramic substrate.

[0027] ZrO2 nanocrystals are deposited on a plane to form a thin film. The refractive index of the film is influenced not only by the properties of the ZrO2 nanocrystals themselves (which have a relatively small impact, as the refractive index of ZrO2 nanocrystals is around 2.2), but also primarily by the pore structure formed between the ZrO2 nanocrystals. This pore structure includes both pore size and shape. The ZrO2 nanoporous thin film prepared in this invention has a pore size between 100-1000 nm, and its shape is mostly composed of sharp-angled zigzag lines. These zigzag lines facilitate the reflection of light in the same direction, and its refractive index is between 2.2 and 2.5.

[0028] In a specific embodiment, the zirconium oxide nanoporous film structure of the present invention can preferably be formed by the following method:

[0029] A monoclinic zirconia thin film is deposited on an alumina ceramic substrate. The zirconia thin film is then subjected to high-temperature treatment to transform the zirconia from the monoclinic phase to the tetragonal or cubic phase. The distance between the zirconia particles increases to form nanopores, resulting in a zirconia nanoporous thin film structure.

[0030] It should be noted that:

[0031] In the above-mentioned formation method, the zirconium oxide film can undergo a phase transformation by high-temperature treatment, changing from a monoclinic phase to a tetragonal or cubic phase. The reduction in the cell volume leads to grain shrinkage, resulting in volume shrinkage. The zirconium oxide grains in the zirconium oxide film tend to be single or a small number of particles, i.e., the particles detach from each other to form "islands". Since the substrate material restricts the shrinkage of the zirconium oxide film, the shrinkage process is constrained by the substrate. The distance between the particles increases to form nanopores, thereby forming a zirconium oxide nanoporous film structure.

[0032] In a specific embodiment, preferably, the precursor for depositing the monoclinic zirconia thin film contains yttrium, and a yttrium-doped zirconia thin film is deposited.

[0033] Precursors can also include yttrium precursors, such as Y(OH)CO3-doped yttrium oxide. On the one hand, the high refractive index of Y2O3-doped ZrO2 is utilized to improve the overall light reflectivity of the substrate. On the other hand, Y2O3 helps to stabilize the phase of ZrO2, so that ZrO2 can be maintained for a long time after it changes from the monoclinic phase to the tetragonal or cubic phase, thus extending the effective service life of the ceramic substrate.

[0034] Stable tetragonal zirconia has a birefringent structure, meaning it has multiple refractive indices, which can scatter and deflect light multiple times, thereby improving light reflectivity. In contrast, stable cubic zirconia has a symmetrical structure, which allows light to pass through more easily and is not conducive to improving light reflectivity. In this case, the light reflectivity is mainly improved by relying on the pore structure.

[0035] In a specific embodiment, the doping situation is that the yttrium-doped zirconium oxide is doped with 5-10 cycles of yttrium oxide every 100-200 cycles of zirconium oxide on the zirconium oxide nanoporous film structure.

[0036] In a specific embodiment, preferably, the thickness of the zirconium oxide film is 50-200 nm.

[0037] This invention also specifically protects a method for preparing a high-reflectivity alumina ceramic substrate, comprising the following steps:

[0038] S1. Surface treatment of alumina ceramic substrate material to remove surface contaminants;

[0039] S2. Monoclinic zirconia thin film deposition: Zirconia thin films are formed by physical or chemical deposition.

[0040] S3. Zirconia films are subjected to high-temperature treatment at 1100–1200℃ to form zirconia nanoporous film structures.

[0041] It should be noted that:

[0042] Temperature control during the high-temperature treatment in S3 can control the degree of phase transformation of zirconia from monoclinic to tetragonal or cubic phase. Within the scope of this invention, higher temperature promotes more phase transformations, increases the proportion of tetragonal phase, and increases the strength of high-reflectivity alumina ceramic substrate. However, increasing temperature also reduces porosity, thereby reducing light reflectivity.

[0043] In a specific implementation, the removal of contaminants from the surface of the alumina ceramic substrate material in S1 can be achieved using the following methods:

[0044] The substrate is ultrasonically cleaned using organic solvents (acetone, ethanol, etc.) to remove surface grease and other organic contaminants. It is then dried by heating at 80-110°C to remove residual moisture and organic solvents from the surface.

[0045] In a specific implementation, the high-temperature treatment described in S3 can be performed using laser radiation.

[0046] In specific embodiments, the physical methods for forming zirconium oxide thin films of the present invention may include atomic layer deposition and magnetron sputtering at room temperature deposition, etc.

[0047] The specific steps for preparing zirconium oxide (ZrO2) thin films at room temperature using atomic layer deposition (ALD) technology are as follows:

[0048] 1. Zirconium tetrachloride and water are used as the precursor gas source;

[0049] 2. Zirconium tetrachloride vapor is pulsed into the reaction chamber and undergoes chemisorption on the exposed alumina substrate surface; the pulse duration is 1-3 seconds, and the carrier gas flow rate is 30-50 sccm (1 cubic centimeter per minute).

[0050] 3. Use a cleaning gas (high-purity nitrogen or argon) to carry away the unreacted zirconium tetrachloride vapor and the reaction byproduct HCl from the reaction chamber; pulse time 3-5s, carrier gas flow rate 100-150sccm;

[0051] 4. Water vapor is pulsed into the reaction chamber and continues to react chemically with the surface where the zirconium tetrachloride precursor is adsorbed; pulse duration is 1-3 seconds, and carrier gas flow rate is 30-50 sccm.

[0052] 5. The cleaning gas carries away excess water vapor and the reaction byproduct HCl from the reaction chamber; the pulse time is 3-5 seconds, and the carrier gas flow rate is 100-150 sccm.

[0053] 6. Repeat the above steps multiple times until the desired zirconium oxide film thickness is achieved.

[0054] When a yttrium oxide layer is spaced on a zirconia thin film, the yttrium oxide deposition process is as follows:

[0055] Y(thd)3 (trihydroxy-2,4-pentanedione yttrium) and water were used as precursor gas sources;

[0056] Y(thd)3 vapor is pulsed into the reaction chamber and undergoes chemisorption on the surface of the deposited ZrO2 film; the pulse duration is 1-3s and the carrier gas flow rate is 20-30sccm.

[0057] Use a cleaning gas (high-purity nitrogen or argon) to remove unreacted Y(thd)3 vapor and reaction byproduct methane from the reaction chamber; pulse time 3-5s, carrier gas flow rate 100-150sccm.

[0058] Water vapor is pulsed into the reaction chamber and continues to react chemically with the surface adsorbed by Y(thd)3; the pulse duration is 1-3 seconds and the carrier gas flow rate is 20-30 sccm.

[0059] The cleaning gas carries away excess water vapor and the reaction byproduct methane from the reaction chamber; the pulse time is 3-5 seconds, and the carrier gas flow rate is 100-150 sccm.

[0060] Atomic layer deposition (ALD) can precisely tailor crystal and pore structures. By controlling pulse time and pulse size, the aperture design of nanopores can be achieved, further improving light reflectivity for incident light of specific wavelengths.

[0061] By controlling the porosity of nanopores (uniform grain size and morphology, uniform gaps formed by phase transition shrinkage, i.e., uniform pore size and consistent pore morphology, and pore structure porosity in long-range ordered structures), diffraction effects can be generated, thereby enhancing reflection at specific wavelengths.

[0062] By adjusting the aperture of the aperture, diffraction control in the visible light band can be achieved (the aperture d can cause diffraction of light of a specific wavelength λ), producing a structured optical effect. The diffracted light can interfere with the reflected light, resulting in enhanced reflection.

[0063] Specifically, the wavelength of red light is about 650 nm, corresponding to an aperture d of about 300-350 nm;

[0064] Orange light has a wavelength of approximately 600 nm, corresponding to an aperture d of approximately 250-320 nm;

[0065] Yellow light has a wavelength of approximately 550 nm, corresponding to an aperture d of approximately 220-290 nm.

[0066] Green light has a wavelength of approximately 500 nm, corresponding to an aperture d of approximately 200-260 nm;

[0067] Blue light has a wavelength of approximately 450 nm, corresponding to an aperture d of approximately 160-230 nm.

[0068] Indigo light has a wavelength of approximately 400 nm, corresponding to an aperture d of approximately 140-200 nm;

[0069] The wavelength of violet light is about 350nm, which corresponds to an aperture d of about 110-180nm.

[0070] In specific embodiments, the chemical method for forming the zirconium oxide film of the present invention may include the sol-gel method, specifically: using an organic compound and a ligand compound of zirconium to coat and sinter to obtain a zirconium oxide film.

[0071] in,

[0072] Organic compounds include one of the following: zirconium butanol polymer Zr(OC4H9)4, zirconium isopropanol polymer Zr(OC3H5)4, zirconium n-propanol polymer Zr(OC3H6)4, zirconium acetate Zr(CH3COO)4, zirconium ether polymer Zr(OCH2CH2O)4, etc.

[0073] Ligand compounds: zirconium nitrate Zr(NO3)4, zirconium chloride ZrCl4, etc.

[0074] for example:

[0075] Zr(OCH2CH2O)4 and zirconium nitrate Zr(NO3)4, with a molar ratio of 1:1, are dissolved in an ethanol solution (80-95% ethanol solution). After stirring and mixing thoroughly, the molar concentration of the solution is c(Zr). 4+ The concentration of NO in Zr(NO3)4 is 1-2 mol / L. 3- The zirconium complex gel containing ether ligands is generated by substitution of the ether group in Zr(OCH2CH2O)4.

[0076] Ethanol solution causes partial hydrolysis of Zr(NO3)4 to form zirconium oxide, which is a network structure oxide.

[0077] Zr(OCH2CH2O)4 hydrolyzes relatively slowly; the reactions between the two precursors and their respective hydrolysis reactions are synergistic, resulting in a ZrO2 gel with uniform composition and a loose structure (the network structure of zirconium oxide makes the zirconium complex structure loose), with a reaction time of 3-6 hours.

[0078] Oxygen-containing organic salts are not easily hydrolyzed, while inorganic salts have a higher hydrolysis rate, yielding zirconium oxide, a hydrolysis product with a network structure. This network structure is used as a support to carry zirconium complex gels containing ether-based ligands, overcoming the problem of severe gel aggregation.

[0079] Sintering heat treatment to obtain ZrO2 thin films with pure composition and dense structure:

[0080] Pre-sintering is carried out at 300-400℃ to burn off some organic matter and solvent;

[0081] Keep warm at 400-600℃ for 3 hours to ensure complete burning of organic matter;

[0082] Holding at 600-700℃ for 2 hours promotes component flow and polymerization, eliminates non-uniformity of components or structures that may exist during sintering, promotes microstructure rearrangement, and obtains a thin film.

[0083] The ether ligand of the zirconium complex is easily removed to form amorphous zirconium oxide; after heating at 500-700℃, amorphous ZrO2 (amorphous ZrO2 is transformed into monoclinic phase at 500-700℃) is transformed into monoclinic phase.

[0084] The ZrO2 gel contains organic matter, organic ligands, residual reactants, and solvents. When heated, solvents such as ethanol evaporate and escape from the film system. When the temperature is high enough, organic matter and organic ligands are decomposed and oxidized into CO, CO2, and H2O, which are then discharged. During sintering, the already formed zirconia crystals continue to rearrange and grow, forming zirconia with a stable crystal structure. The discharge of gases generated during sintering and the component flow and phase transitions help purify the components of the zirconia film and also facilitate the obtaining of a dense and uniform microstructure.

[0085] The dual solubility and weak hydrolysis of ethanol make the reaction easy to control, which is beneficial for obtaining pure products.

[0086] ① It can dissolve two zirconium precursors, ensuring that the two zirconium precursors are fully and uniformly mixed;

[0087] ② Ethanol is a hydroxyl solvent, and the hydroxyl group reacts with Zr(OCH2CH2O)4. 4+ It undergoes coordination reactions (which can regulate the hydrolytic polymerization behavior of organozirconium compounds to some extent); it also causes ZrCl4 to undergo partial hydrolysis (the role of a mild hydrolytic agent can control the hydrolysis rate of ZrCl4 and help stabilize the reaction solution).

[0088] Polyol solvents (such as ethylene glycol, propylene glycol, glycerol, etc.) can also be used. A higher hydroxyl content can increase the hydrolysis rate, but it may lead to insufficient gel formation and is not suitable for adjusting the hydrolysis rate.

[0089] Citric acid is preferred because it is a carboxylic acid compound and contains hydroxyl groups. The hydroxyl groups promote hydrolysis, while the acid radicals inhibit hydrolysis. The sol-gel reaction in the solution is in dynamic equilibrium, resulting in finer gel particles and a more uniform distribution of the product.

[0090] Preferably, the high-temperature treatment temperature in S3 is 1140–1160°C.

[0091] This invention also specifically protects the application of a high-reflectivity alumina ceramic substrate in the preparation of luminescent materials and encapsulation structures.

[0092] In specific embodiments, the packaging structure can be a high-power packaging structure for fields such as high-power electric vehicles, aerospace, and military industries.

[0093] Compared with the prior art, the beneficial effects of the present invention are:

[0094] The high-reflectivity alumina ceramic substrate of the present invention significantly improves the light reflectivity of the alumina ceramic substrate by preparing a zirconia nanoporous film structure on a dense alumina ceramic substrate, while ensuring a certain bending strength.

[0095] The light reflectance of the high-reflectivity alumina ceramic substrate of the present invention can reach more than 99.4%, and can reach up to 106.7%. Attached Figure Description

[0096] Figure 1 This is a schematic diagram of the optical path for measuring light reflectance. Detailed Implementation

[0097] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0098] Example 1

[0099] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0100] The porosity of the zirconia nanoporous film structure is 8.6%, and the pore size is 100 nm.

[0101] The thickness of the zirconia nanoporous film structure is 50 nm.

[0102] The preparation method of the high-reflectivity alumina ceramic substrate in Example 1 above can be referred to as follows:

[0103] S1. Surface treatment of alumina ceramic substrate material to remove surface contaminants:

[0104] The substrate is ultrasonically cleaned using organic solvents (acetone, ethanol, etc.) to remove surface grease and other organic contaminants. Then, it is dried by heating at 80-110°C to remove residual moisture and organic solvents from the surface.

[0105] S2. Monoclinic zirconia thin film deposition:

[0106] Zirconium tetrachloride and water were used as the precursor gas source. Zirconium tetrachloride vapor was pulsed into the reaction chamber and chemically adsorbed on the exposed alumina substrate surface. The pulse duration was 3 s and the carrier gas flow rate was 30 sccm. High-purity nitrogen gas was used as a cleaning gas to remove unreacted zirconium tetrachloride vapor and the reaction byproduct HCl from the reaction chamber. The pulse duration was 5 s and the carrier gas flow rate was 150 sccm. Water vapor was pulsed into the reaction chamber and continued to chemically react with the surface adsorbed with the zirconium tetrachloride precursor. The pulse duration was 3 s and the carrier gas flow rate was 50 sccm. High-purity nitrogen gas was used as a cleaning gas to remove excess water vapor and the reaction byproduct HCl from the reaction chamber. The pulse duration was 5 s and the carrier gas flow rate was 150 sccm. The above steps were repeated multiple times until the thickness of the zirconium oxide film reached 50 nm.

[0107] S3. Zirconia films are subjected to high-temperature treatment at 1100℃ to form zirconia nanoporous film structures.

[0108] Example 2

[0109] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface.

[0110] The porosity of the zirconia nanoporous film structure is 4.6%, and the pore size is 100 nm.

[0111] The thickness of the zirconia nanoporous film structure is 50 nm.

[0112] The preparation method of the high reflectivity alumina ceramic substrate in Example 2 is basically the same as that in Example 1, except that the high temperature treatment temperature in S3 is 1150℃.

[0113] Example 3

[0114] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0115] The porosity of the zirconia nanoporous film structure is 9.1%, and the pore size is 300 nm.

[0116] The thickness of the zirconia nanoporous film structure is 100 nm.

[0117] The preparation method of the high reflectivity alumina ceramic substrate in Example 3 is basically the same as that in Example 1, except that the high temperature treatment temperature in S3 is 1100℃.

[0118] Example 4

[0119] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0120] The porosity of the zirconia nanoporous film structure is 4.9%, and the pore size is 300 nm.

[0121] The thickness of the zirconia nanoporous film structure is 100 nm.

[0122] The preparation method of the high reflectivity alumina ceramic substrate in Example 4 is basically the same as that in Example 1, except that the high temperature treatment temperature in S3 is 1150℃.

[0123] S2. Preparation of monoclinic zirconia thin films:

[0124] Zr(OCH2CH2O)4 and zirconium nitrate Zr(NO3)4, with a molar ratio of 1:1, are dissolved in an ethanol solution (80-95% ethanol solution). After stirring and mixing thoroughly, the molar concentration of the solution is c(Zr). 4+ The concentration of the catalyst was 1-2 mol / L, the reaction time was 6 hours, the pre-sintering was carried out at 400℃, the temperature was held at 600℃ for 3 hours, the sintering was carried out at 700℃, and the temperature was held at 700℃ for 2 hours to obtain the film.

[0125] Example 5

[0126] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0127] The porosity of the zirconia nanoporous film structure is 9.2%, and the pore size is 300 nm.

[0128] The thickness of the zirconia nanoporous film structure is 150 nm.

[0129] The preparation method of the high reflectivity alumina ceramic substrate in Example 5 is basically the same as that in Example 1, except that the high temperature treatment temperature in S3 is 1100℃.

[0130] Example 6

[0131] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0132] The porosity of the zirconia nanoporous film structure is 5.7%, and the pore size is 400 nm.

[0133] The thickness of the zirconia nanoporous film structure is 150 nm.

[0134] The preparation method of the high reflectivity alumina ceramic substrate in Example 6 is basically the same as that in Example 1, except that the high temperature treatment temperature in S3 is 1150℃.

[0135] Example 7

[0136] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0137] The porosity of the zirconia nanoporous film structure is 4.3%, and the pore size is 500 nm.

[0138] The thickness of the zirconia nanoporous film structure is 150 nm.

[0139] The preparation method of the high reflectivity alumina ceramic substrate in Embodiment 7 is basically the same as that in Embodiment 1, except that the high temperature treatment temperature in S3 is 1200℃.

[0140] Example 8

[0141] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0142] The porosity of the zirconia nanoporous film structure is 9.4%, and the pore size is 100 nm.

[0143] The thickness of the zirconia nanoporous film structure is 200 nm.

[0144] The preparation method of the high reflectivity alumina ceramic substrate in Example 8 is basically the same as that in Example 1, except that the high temperature treatment temperature in S3 is 1100℃.

[0145] Example 9

[0146] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0147] The porosity of the zirconia nanoporous film structure is 6.5%, and the pore size is 300 nm.

[0148] The thickness of the zirconia nanoporous film structure is 200 nm.

[0149] The preparation method of the high reflectivity alumina ceramic substrate in Example 9 is basically the same as that in Example 1, except that the high temperature treatment temperature in S3 is 1150℃.

[0150] Example 10

[0151] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0152] The porosity of the zirconia nanoporous film structure is 4.7%, and the pore size is 500 nm.

[0153] The thickness of the zirconia nanoporous film structure is 200 nm.

[0154] The preparation method of the high reflectivity alumina ceramic substrate in Example 10 is basically the same as that in Example 1, except that the high temperature treatment temperature in S3 is 1200℃.

[0155] Example 11

[0156] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconia nanoporous film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm, the zirconia nanoporous film structure has a porosity of 5.2%, a pore size of 300 nm, and a thickness of 200 nm.

[0157] The main difference from Example 1 is:

[0158] The precursor for depositing monoclinic zirconia thin films contains yttrium, and yttrium-doped zirconia thin films are deposited. The yttrium-doped zirconia is formed by doping 10 cycles of yttrium oxide every 200 cycles of zirconia in a zirconia nanoporous film structure.

[0159] Example 12

[0160] A high-reflectivity alumina ceramic substrate includes an alumina ceramic substrate and a zirconia nanoporous film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm, and the zirconia nanoporous film structure has a porosity of 4.9% and a pore size of 200 nm. The thickness of the zirconia nanoporous film structure is 200 nm.

[0161] The main difference from Example 1 is:

[0162] The precursor for depositing monoclinic zirconia thin films contains yttrium, and yttrium-doped zirconia thin films are deposited. The yttrium-doped zirconia is formed by doping 5 cycles of yttrium oxide every 100 cycles of zirconia in a zirconia nanoporous film structure.

[0163] Comparative Example 1

[0164] An alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0165] The porosity of the zirconia nanoporous film structure is 3.5%, and the pore size is 100 nm.

[0166] The thickness of the zirconia nanoporous film structure is 50 nm.

[0167] The preparation method of the alumina ceramic substrate in Comparative Example 1 is basically the same as that in Example 1, except that the high temperature treatment temperature of S3 is 1200℃.

[0168] Comparative Example 2

[0169] An alumina ceramic substrate includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The alumina ceramic substrate has a thickness of 1 mm.

[0170] The porosity of the zirconia nanoporous film structure is 3.9%, and the pore size is 300 nm.

[0171] The thickness of the zirconia nanoporous film structure is 100 nm.

[0172] The preparation method of the alumina ceramic substrate in Comparative Example 1 is basically the same as that in Example 1, except that the high temperature treatment temperature of S3 is 1200℃.

[0173] Comparative Example 3

[0174] An alumina ceramic substrate includes the same alumina ceramic substrate as in Example 1, but without surface treatment.

[0175] Result detection

[0176] 1. Porosity (assuming the alumina ceramic substrate is completely dense, the porosity measured is the porosity of the thin film)

[0177] The nitrogen adsorption-desorption (BET) method utilizes the physical adsorption and desorption principles of nitrogen gas to calculate the porosity by measuring the specific surface area of ​​the thin film.

[0178] 2. Light reflectivity

[0179] Working principle:

[0180] This instrument consists of a probe, main unit, standard plates (two black and two white), and working ceramic plates (two black and two white). The probe uses the principle of 0° illumination and 45° reception. When the reflected light from the sample acts on the surface of the photovoltaic cell, an electrical signal is generated, which is amplified by a DC amplifier and displayed as a reading (see Optical Path Principle for details). Figure 1 The instrument reading is directly proportional to the intensity of light reflected from the surface being measured.

[0181] Reflectance = Reflectance measured on black substrate / Reflectance measured on white substrate

[0182] 3 Bending strength

[0183] The ceramic substrate was processed into a three-point bending specimen with dimensions of 60mm x 8mm x 0.625mm, where 60mm x 8mm is the stress-bearing surface.

[0184] The tests were conducted using the Instron 3369 material mechanical testing machine from the USA.

[0185] The bending strength of the material was tested using the three-point bending method. The upper indenter of the fixture had a diameter of 6 mm, and the two lower indenters each had a diameter of 4 mm, resulting in a span-to-thickness ratio of 10:1. The descent speed of the upper indenter was 1.5 mm / min. The span between the support points was 40.0 mm, and the loading speed was 2.0 mm / min. The bending load-displacement curve was recorded. The bending strength was calculated using the following formula:

[0186]

[0187] In the formula: σ f P represents the flexural strength (MPa). max 1 is the maximum load at which the specimen breaks (KN); L is the span between the two indenters (40mm); h is the height of the specimen (mm); b is the width of the specimen (mm).

[0188] The test results are shown in Table 1 below:

[0189] Table 1

[0190] Serial Number Zirconia nanoporous film thickness nm Aperture nm Porosity % Reflectivity % Flexural strength (MPa) Example 1 50 100 8.6 102.1 425 Example 2 50 100 4.6 100.2 451 Example 3 100 300 9.1 102.9 407 Example 4 100 300 4.9 100.9 453 Example 5 150 300 9.2 103.2 401 Example 6 150 400 5.7 101.5 445 Example 7 150 500 4.3 99.4 456 Example 8 200 100 9.4 101.5 389 Example 9 200 300 6.5 105.1 427 Example 10 200 500 4.7 99.8 445 Example 11 200 300 5.2 106.7 465 Example 12 200 200 4.9 102.7 462 Comparative Example 1 50 100 3.5 98.8 475 Comparative Example 2 100 300 3.9 99.1 462 Comparative Example 3 / / / 97 350

[0191] As can be seen from the data in Table 1 above, the high-reflectivity alumina ceramic substrate of the present invention can achieve a reflectivity of over 99.8%, with a maximum of 106.7%, demonstrating high reflectivity. Furthermore, the high-reflectivity alumina ceramic substrate of the present invention has a relatively rough surface after exiting the sintering furnace without surface processing. The zirconia nanoporous film deposited on the alumina ceramic substrate is equivalent to the zirconia filling the pits or microcracks on the surface of the alumina ceramic substrate, reducing surface defects. Under external force, this helps to inhibit the propagation of fractures, improving its mechanical strength. Moreover, the nanopores in the film layer can effectively absorb fracture energy, further improving the mechanical strength of the ceramic, with a bending strength exceeding 389 MPa, effectively mitigating the tendency to break during packaging and assembly.

[0192] Examples 11 and 12 are yttrium-doped zirconium oxide, and it can be seen that yttrium doping is more beneficial for improving the light reflectivity of the substrate. Among them, Example 12 has a higher reflectivity than Example 11. Although the ratio is 20:1, the yttrium oxide in Example 12 is more uniformly distributed throughout the film, and the yttrium oxide has a better stabilizing effect on zirconium oxide. Moreover, the refractive index of yttrium oxide itself is higher than that of air and zirconium oxide.

[0193] The porosity of the zirconia nanoporous film structure on the alumina ceramic substrate in Comparative Examples 1 and 2 is not within the scope of protection of this invention, being less than 4%. Although the ceramic can achieve good mechanical properties due to its low porosity, its reflectivity is significantly reduced and cannot reach the high reflectivity of this invention.

[0194] As can be seen from Comparative Example 3, the alumina ceramic substrate of the present invention, without any treatment, has a reflectivity of only 97% and a bending strength of only 350 MPa, which is obviously far inferior to the high reflectivity alumina ceramic substrate of the present invention in terms of reflectivity and mechanical properties.

[0195] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A high-reflectivity alumina ceramic substrate, characterized in that, This includes an alumina ceramic substrate and a zirconium oxide nanoporous thin film structure formed on the substrate surface. The porosity of the zirconium oxide nanoporous film structure is 4-10%, and the pore size is 100nm-1000nm; The thickness of the zirconium oxide nanoporous film structure is 50-200 nm. The refractive index of the zirconia nanoporous film structure is 2.2~2.5; the zirconia nanoporous film structure is formed in the following manner: S1. Surface treatment of alumina ceramic substrate material to remove surface contaminants; S2. Monoclinic zirconia thin film deposition: Zirconia thin films are formed by physical or chemical deposition methods; S3. Zirconia films are subjected to high-temperature treatment at 1000~1200℃ to form zirconia nanoporous film structures.

2. The high-reflectivity alumina ceramic substrate as described in claim 1, characterized in that, The precursor for depositing the monoclinic zirconia thin film contains yttrium, and yttrium-doped zirconia thin film is deposited.

3. The high-reflectivity alumina ceramic substrate as described in claim 2, characterized in that, The yttrium-doped zirconium oxide is formed by doping 5-10 cycles of yttrium oxide every 100-200 cycles of zirconium oxide on a zirconium oxide nanoporous film structure.

4. The high-reflectivity alumina ceramic substrate as described in claim 1, characterized in that, The thickness of the zirconium oxide film is 500-1000 nm.

5. A method for preparing a high-reflectivity alumina ceramic substrate according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Surface treatment of alumina ceramic substrate material to remove surface contaminants; S2. Monoclinic zirconia thin film deposition: Zirconia thin films are formed by physical or chemical deposition. S3. Zirconia films are subjected to high-temperature treatment at 1000~1200℃ to form zirconia nanoporous film structures.

6. The method for preparing a high-reflectivity alumina ceramic substrate as described in claim 5, characterized in that, The high-temperature processing temperature in S3 is 1100~1200℃.

7. The application of the high-reflectivity alumina ceramic substrate according to any one of claims 1 to 4 in the preparation of a luminescent material encapsulation structure.

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