WO2021000343A1 - Light-storage-type multi-phase ceramic material having ultra-high brightness and preparation method therefor - Google Patents

Abstract

Disclosed are a light-storage-type multi-phase ceramic material having ultra-high brightness and a preparation method therefor. The method involves homogenizing a long afterglow phosphor powder, a quartz ceramic powder, and a pore-forming agent to formulate a slurry, subjecting same to casting molding and drying, and sintering same to form a multi-phase structure having "pore + light-storage ceramic". There are micropores inside the ceramic material, the pores have a high degree of sphericity and a diameter size in the range of 100-1000 nm, and satisfy conditions under which Mie scattering of fluorescence occurs inside the ceramic, so that the propagation path of the fluorescence is changed and the total reflection effect is weakened. Compared with existing multi-phase light-storage ceramic materials, the front light extraction efficiency is remarkably increased by 10-30%, and the preparation process is simple and rapid, uses a low sintering temperature, and easily achieves batch production.

Description

Light-storing composite phase ceramic material with ultra-high brightness and preparation method thereof Technical field

The invention belongs to the field of preparation of inorganic non-metallic materials, and relates to a light-storing ceramic material, in particular to a light-storing composite ceramic material with ultra-high brightness and a preparation method thereof.

Background technique

Europium and dysprosium co-doped strontium aluminate long afterglow phosphor is a yellow-green long afterglow luminescent material with stable chemical properties, which can be widely used in architectural indication and emergency lighting, disaster relief and fire escape, gardening and landscape art design.

At present, the long-lasting luminescence indicator products in practical applications are sintered long-lasting phosphors that are coated on clay or polyvinyl chloride plastic (PVC) substrates by a secondary spin coating method. This preparation method has a cumbersome process and requires two-step sintering (phosphor sintering + substrate sintering) and post-spin coating, which has low efficiency and high energy consumption in actual production. In addition, the long afterglow powder is only coated on the surface of the substrate, and the outermost part is only protected by a layer of glaze. When used under special conditions (such as fire, underwater), the long afterglow powder and the substrate material itself are easily decomposed , Which greatly shortens its service life, and ultimately limits the application range of long afterglow luminescent materials for fire escape and underwater landscape. Therefore, researchers have developed a "one-piece" light-storing composite ceramic. Among them, quartz ceramics are selected as the matrix phase due to their high acid and alkali corrosion resistance and thermal shock resistance, in addition to the advantages of low thermal expansion coefficient and good volume stability. The "one-piece" light-storing composite ceramic is prepared by weighing, mixing, forming, drying and sintering the long-lasting light-storing powder and quartz ceramic raw material powder.

However, due to the large refractive index difference between light-storing ceramics (refractive index of 1.45-1.56) and air (refractive index of 1.0), the total emission effect will be generated when fluorescence is emitted from the upper surface of the ceramic after being excited by external energy. The critical angle of total reflection is calculated to be 44°, that is, only 24.4% of the fluorescence can be emitted from the upper surface of the ceramic to achieve the extraction of front light. The remaining fluorescence is limited by the total reflection effect and will be transmitted inside the ceramic as a waveguide effect until Complete loss. Therefore, in order to realize the wider application of "integrated" light-storing ceramics in the fields of fire protection instructions, gardening and landscape, there is an urgent need for a simple and effective method to improve the front light extraction rate of multiphase light-storing ceramics.

Chinese patent application CN109467453A discloses a fluorescent ceramic with a characteristic microstructure. In the fluorescent ceramic for solid-state lighting, diffusely distributed pores are introduced as the second phase, which effectively changes the microstructure of the ceramic, increases the utilization rate of incident light, and improves the emission brightness. This patent application uses Y _3-xyz Ce _x Lu _y Gd _z Al _5-a Ga _a O ₁₂ phosphor as the fluorescent crystal particles, which are introduced into the ceramic by adding pore formers (such as starch, polyvinyl alcohol, dextrin, etc.) Air holes improve the brightness of the output. The decomposition temperature of this type of pore former is far from the ceramic firing temperature, which is not conducive to the formation of round pores. After the fluorescence is incident on the pores, it is easy to refraction, so that the fluorescence spreads in the ceramic in the form of scattering or reflection.

Summary of the invention

One of the objectives of the present invention is to provide a method for preparing a light-storing composite ceramic material with ultra-high brightness.

The second object of the present invention is to provide a light-storing composite ceramic material with super high brightness prepared by the above preparation method.

In order to achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for preparing a light-storing multiphase ceramic material with ultra-high brightness, the specific steps are as follows:

(1) Weighing: Based on the total mass of the raw material powder as 100%, weigh 50% to 55% of the 10-30 mesh quartz raw material, 25% to 29% 50-100 mesh quartz raw material, 6 %～15% of 150～250 mesh quartz raw material, the rest is raw material powder for preparing Europium and Dysprosium co-doped strontium aluminate long afterglow phosphor; then weigh 0.5%～1.5% of the total mass of raw material powder to make holes The pore former is a mixture of ammonium bicarbonate and starch in a mass ratio of 1:3 to 6;

(2) Mixing: Put the powder raw materials weighed in step (1) in a ball milling tank, and at the same time add a mill ball and deionized water for ball milling and mixing;

(3) Forming: the slurry after ball milling in step (2) is subjected to vacuum defoaming treatment, and then the defoamed slurry is injected into a mold to form a green body;

(4) Drying: the blank obtained in step (3) is allowed to stand for 7-12 hours, then demolded, and then placed in a drying box for drying;

(5) Sintering: calcining the dried green body in step (4) in a reducing atmosphere at a high temperature, the calcination temperature is 800-1200℃, the holding time is 3-6h, and then it is cooled to room temperature with the furnace to obtain a super high Bright light-storing composite ceramic material.

In step (1), the raw material powders for preparing the europium and dysprosium co-doped strontium aluminate long afterglow phosphor are SrCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ and Dy ₂ O ₃ , according to the chemical formula SrAl ₂ O ₄ : The stoichiometric ratio of each element in Eu ²⁺ and Dy ³⁺ is weighed.

In step (2), the mass ratio of the grinding ball to the total mass of the raw material powder is 1.5-3:1, and the addition amount of the deionized water is 12%-17% of the total mass of the raw powder.

In step (2), the rotation speed of the ball mill is 160-300 r/min, and the ball milling time is 20-25 h.

In step (3), the vacuum degree of the vacuum defoaming is -10～-30kpa, and the defoaming time is 30～50min.

In step (4), the drying temperature is 60-100°C, and the drying time is 15-24 hours.

The present invention also provides a light-storing composite ceramic material with ultra-high brightness prepared by the above preparation method. The ceramic material is rich in micropores, has high pore sphericity, and has a size in the range of 100-1000nm, and has "pores". +Light storage ceramic "multiphase structure.

In the present invention, the mixture of ammonium bicarbonate and starch is used as the pore-forming agent, and the ratio of the two is reasonably controlled, so that the pore-forming agent can be decomposed within the melting temperature range of the light-storing ceramics, and the surface tension inside the ceramics during ball formation is reduced. Keep the stomata better spherical.

Compared with the prior art, the present invention has the following beneficial effects:

1. The ultra-high-brightness self-luminous quartz ceramic material provided by the present invention can achieve 720min of continuous luminescence after 20min of light storage. The initial 1min intensity is >4000mcd/m ² ; 60min, >30mcd/m ² . (Outdoor direct sunlight for 20min, fluorescent lamp for 30min, ultraviolet light for 5min, room temperature 25℃ test).

2. The self-luminous quartz ceramic material with ultra-high brightness provided by the present invention has a significantly improved front light extraction efficiency by 10-30% compared with the existing multi-phase light-storing ceramic material.

3. The method for improving the efficiency of the light-storing ceramic material provided by the present invention is simple and effective, the process is controllable, the experiment period is short, and the product stability is good.

Description of the drawings

Fig. 1 is an X-ray powder diffraction pattern of a light-storing composite ceramic material with ultra-high brightness prepared in Example 1. The abscissa is the incident angle of the x-ray, and the ordinate is the diffraction intensity;

Figure 2 is a scanning electron microscope image (SEM) of the ultra-high brightness light-storing composite ceramic material prepared in Example 1;

3 is a diagram showing the distribution of EDS element content in micro-area of the ultra-high brightness light-storing composite ceramic material prepared in Example 1;

Figure 4 is a graph showing the luminescence intensity attenuation changes of the light-storing multiphase material with ultra-high brightness prepared in Example 1 and the sample without adding a pore former;

Fig. 5 is a light path model diagram of the front light extraction rate caused by scattering from the inside of the quartz ceramic material of the light-storing composite ceramic material with ultra-high brightness.

Detailed ways

The present invention will be further described in detail below with reference to the drawings and specific embodiments.

To prepare 100g of the target product, the raw material powders were weighed separately. The purity of each raw material powder was analytically pure and above. See Table 1 for the ingredient list.

Table 1 Example ingredients list

Numbering	1 #	2 #	3 #
Quartz (10～30 mesh)	55g	53g	50g
Quartz (50～100 mesh)	25g	27g	29g
Quartz (150～250 mesh)	15g	10g	6g
Pore former	0.5g	1g	1.5g
Phosphor powder addition	5wt.%	10wt.%	15wt.%
SrCO 3	2.756g	5.512g	8.268g
Al 2 O 3	2.025g	4.050g	6.075g
Eu 2 O 3	0.070g	0.140g	0.210g
Dy 2 O 3	0.148g	0.296g	0.345g
Deionized water	12g	15g	17g

Example 1

(1) Weighing: According to 1 ^# in Table 1, weigh the raw material powders of quartz, SrCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ , and Dy ₂ O ₃ and pore formers of different particle sizes;

(2) Mixing: Place the powder weighed in step (1) in a ball mill tank containing 150g of high-purity alumina balls, and at the same time add 12g of deionized water for ball milling and mixing. The ball milling speed is 160r/min. Time is 20h;

(3) Molding: the slurry obtained in step (2) is subjected to vacuum defoaming treatment, and defoaming for 30 minutes under a vacuum environment of -15kpa; then the defoamed slurry is injected into a gypsum mold to form a green body;

(4) Drying: the blank obtained in step (3) is allowed to stand for 7 hours and then demolded. After demolding, it is placed in a drying oven for 20 hours and the drying temperature is 60°C;

(5) Sintering: The dried green body in step (4) is calcined at a high temperature in a reducing atmosphere, the calcining temperature is 800°C, the heating rate is 3°C/min, and the holding time is 3 hours, and then it is cooled to room temperature with the furnace. The light-storing complex phase ceramic material with ultra-high brightness is obtained.

See Figure 1, the X-ray diffraction pattern of the sample prepared in this example. XRD test results show that the X-ray diffraction peak of the prepared sample is consistent with the standard card of strontium aluminate (JCPDS(#34-0379)) . In addition, the XRD pattern showed a very obvious bun peak in the diffraction angle range of 20-40, which proved the existence of amorphous silica.

See FIG. 2, the scanning electron microscope image of the cross section of the sample prepared in this embodiment. The SEM test result shows that there are pores in the prepared sample, and the presence of long-lasting phosphor is also found.

See FIG. 3, the element types and contents of different micro-regions of the samples prepared in this embodiment are analyzed, and the EDS test results show that both quartz glass and strontium aluminate long-lasting phosphor are present in the prepared samples.

See Figure 4, the ceramic luminescence and afterglow time of the sample prepared in this embodiment and the sample without the pore former are compared. The test results show that the initial intensity of the luminescence of the sample with the pore former is increased by 26.3%.

See Figure 5, which is a schematic diagram of the optical path of the internal fluorescence propagation of the sample prepared in this embodiment. It can be seen from the figure that the introduction of stomatal scattering points can effectively change the propagation path of fluorescence, increase the utilization rate of excitation light and weaken the total reflection effect.

Example 2

(1) Weighing: Weigh the raw material powders and pore formers of quartz, SrCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ , and Dy ₂ O ₃ with different particle sizes as shown in 2 ^# in Table 1.

(2) Mixing: Put the powder weighed in step (1) in a ball mill tank containing 200g of high-purity alumina balls, and add 15g of deionized water for ball milling and mixing. The ball milling speed is 180r/min. The time is 22h;

(3) Forming: the slurry obtained in step (2) is subjected to vacuum defoaming treatment, and the foam is defoamed for 40 minutes under a vacuum environment of -10kpa; then the defoamed slurry is injected into a gypsum mold to form a green body;

(4) Drying: the blank obtained in step (3) is allowed to stand for 9 hours and then demolded. After demolding, it is placed in a drying oven for 22 hours and the drying temperature is 70°C;

(5) Sintering: The green body of step (4) is calcined at a high temperature in a reducing atmosphere, the calcining temperature is 1000°C, the heating rate is 4°C/min, the holding time is 4.5h, and then it is cooled to room temperature with the furnace to obtain The self-luminous quartz ceramic.

Through observation, the main structural properties of the self-luminous quartz ceramic material prepared in Example 2 and the mechanical luminescence spectrum are similar to those of Example 1.

Example 3

(1) Weighing: Weigh the raw material powders and pore formers of quartz, SrCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ , and Dy ₂ O ₃ of different particle sizes as shown in ^# 3 in Table 1.

(2) Mixing: Put the powder weighed in step (2) in a ball mill tank containing 300g of high-purity alumina balls, and at the same time add 17g of deionized water for ball milling and mixing. The ball milling speed is 300r/min. The time is 25h;

(3) Forming: the slurry obtained in step (2) is subjected to vacuum defoaming treatment, and defoaming for 50 minutes under a vacuum environment of -30kpa; then the defoamed slurry is injected into a gypsum mold to form a green body;

(4) Drying: the blank obtained in step (3) is allowed to stand for 12 hours and then demolded. After demolding, it is placed in a drying oven for 24 hours and the drying temperature is 100°C;

(5) Sintering: The green body of step (4) is calcined at a high temperature in a reducing atmosphere at a calcination temperature of 1200°C, a heating rate of 4°C/min, and a holding time of 6 hours, and then the furnace is cooled to room temperature to obtain the result The self-luminous quartz ceramics.

Through observation, the main structural properties and mechanical luminescence spectrum of the self-luminous quartz ceramic material prepared in Example 3 are similar to those of Example 1.

Claims (7)

1. A method for preparing a light-storing composite ceramic material with ultra-high brightness, which is characterized in that the specific steps are as follows:

   (1) Weighing: Based on the total mass of the raw material powder as 100%, weigh 50% to 55% of the 10-30 mesh quartz raw material, 25% to 29% 50-100 mesh quartz raw material, 6 %～15% of 150～250 mesh quartz raw material, the rest is raw material powder for preparing Europium and Dysprosium co-doped strontium aluminate long afterglow phosphor; then weigh 0.5%～1.5% of the total mass of raw material powder to make holes The pore former is a mixture of ammonium bicarbonate and starch in a mass ratio of 1:3 to 6;

   (2) Mixing: Put the powder raw materials weighed in step (1) in a ball milling tank, and at the same time add a mill ball and deionized water for ball milling and mixing;

   (3) Forming: the slurry after ball milling in step (2) is subjected to vacuum defoaming treatment, and then the defoamed slurry is injected into a mold to form a green body;

   (4) Drying: the blank obtained in step (3) is allowed to stand for 7-12 hours, then demolded, and then placed in a drying box for drying;

   (5) Sintering: calcining the dried green body in step (4) in a reducing atmosphere at a high temperature, the calcination temperature is 800-1200℃, the holding time is 3-6h, and then it is cooled to room temperature with the furnace to obtain a super high Bright light-storing composite ceramic material.
2. The method for preparing a light-storing multi-phase ceramic material with ultra-high brightness according to claim 1, wherein in step (1), the raw material for preparing europium and dysprosium co-doped strontium aluminate long-lasting phosphor The powders are SrCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ and Dy ₂ O ₃ , which are obtained by weighing according to the chemical formula SrAl ₂ O ₄ :Eu ²⁺ and the stoichiometric ratio of each element in Dy ³⁺ .
3. The method for preparing a light-storing multi-phase ceramic material with ultra-high brightness according to claim 1, wherein in step (2), the mass ratio of the grinding ball to the total mass of the raw material powder is 1.5-3: 1. The addition amount of the deionized water is 12%-17% of the total mass of the raw material powder.
4. The method for preparing a light-storing multi-phase ceramic material with ultra-high brightness according to claim 1, wherein in step (2), the rotation speed of the ball mill is 160-300 r/min, and the ball milling time is 20-25 h .
5. The method for preparing a light-storing multi-phase ceramic material with ultra-high brightness according to claim 1, wherein in step (3), the vacuum degree of the vacuum defoaming is -10～-30kpa, and the defoaming time It is 30-50min.
6. The method for preparing a light-storing multi-phase ceramic material with ultra-high brightness according to claim 1, wherein in step (4), the drying temperature is 60-100°C, and the drying time is 15-24h.
7. The light-storing multi-phase ceramic material with ultra-high brightness prepared by the preparation method of any one of claims 1 to 6, characterized in that the ceramic material is rich in micropores, has high pore sphericity, and has a size of Within the range of 100-1000nm.

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