A high thermal conductivity and high strength red fluorescent glass ceramic material and its preparation method

Abstract

The present invention discloses a high-thermal-conductivity, high-strength red fluorescent glass-ceramic material and a preparation method thereof. The red fluorescent glass-ceramic material is prepared from a composite powder. The composite powder composition is xSiO2-yAl2O3-zP2O5-pTiO2-qRE, wherein RE is at least one of MnCO3, Eu2O3, Er2O3, Sm2O3, Fe2O3, Cr2O3, Pr2O3, Nd2O3, Tm2O3, Yb2O3, Ho2O3, and Ni2O3, with 28% ≤ x ≤ 38%, 54% ≤ y ≤ 64%, 2% ≤ z ≤ 6%, 1% ≤ p ≤ 2%, x + y + z + p = 100%, and q accounting for 0.03-0.09% of the total mass of the composite powder. When excited by a blue LED chip with a wavelength of 450-470 nm, the red fluorescent glass-ceramic material of the present invention emits broadband red light near 610 nm. The thermal conductivity of the material is greater than 6.8 W·m ‑1 ·K ‑1 , Vickers hardness is greater than 12GPa.

Description

Technical Field

[0001] The present invention relates to the technical field of glass ceramic materials, and in particular to a high-thermal-conductivity and high-intensity red fluorescent glass ceramic material and a preparation method thereof. Background Art

[0002] Phosphor-converted white light-emitting diodes (WLEDs) have attracted widespread attention as a new generation of lighting sources and have been widely used in our daily lives. Commercial WLEDs consist of a blue chip and YAG:Ce phosphor in an organic resin or silicone. However, due to low stability, the organic photoconverter inevitably turns yellow, which ultimately leads to a decrease in the luminous intensity and chromaticity drift of the WLED. At the same time, due to the lack of red emission components, this packaging method will result in a low color rendering index of the light-emitting device, limiting its use in full-spectrum lighting. Luminescent ion-activated glass-ceramics (GCs) with high stability and transparency are considered to be ideal photoconverters in WLEDs, especially for providing red components. Unlike rare earth ions with narrow emission peaks and dominated by inherent 4f-4f forbidden transitions, Mn 2+ The ion is considered a candidate for a light converter for WLEDs due to its broad red emission. The cheap and readily available manganese raw material is also beneficial for its practical application.

[0003] In recent years, people have developed new Mn 2+ Great efforts have been made to dope GC. 2+ :Zn2GeO4crystallitesprecipitated in transparent GeO2-B2O3-ZnO glass-ceramics.Sci Technol AdvMater.2016;6(5):431-4.) Mn was prepared by infrared femtosecond laser pulse 2+ activated GeO2-B2O3-ZnO GCs and studied different Mn 2+Long-lasting luminescence performance at low concentrations. Reference 2 (Omri K, Lahouli R, El MirL. Microstructure and electrical properties of silica-Zn2SiO4-Mn glass-ceramicsas composite for optoelectronic devices. Results Phys. 2019; 12: 2141-5.) proposed a sol-gel route to prepare SiO2-Zn2SiO4-Mn GC, which has potential application prospects in optoelectronic devices due to its good conductivity. Although Mn 2+ ions are stable in lower redox states at high dopant concentrations, but these new preparation methods sacrifice the strong mechanical properties of GC. How to control the valence state of the dopant while maintaining high stability and transparency remains a key issue in obtaining luminescent Mn with efficient red light emission. 2+ The big challenge of activating GC. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-thermal-conductivity and high-strength red fluorescent glass-ceramic material, which has the characteristics of high thermal conductivity and high mechanical strength.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned high thermal conductivity and high strength red fluorescent glass-ceramic material, which has a simple process and can be industrially produced.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, the present invention provides a high thermal conductivity and high strength red fluorescent glass ceramic material, which is prepared from a composite powder. The composition of the composite powder is xSiO2-yAl2O3-zP2O5-pTiO2-qRE, wherein RE is at least one of MnCO3, Eu2O3, Er2O3, Sm2O3, Fe2O3, Cr2O3, Pr2O3, Nd2O3, Tm2O3, Yb2O3, Ho2O3, and Ni2O3, wherein 28%≤x≤38%, 54%≤y≤64%, 2%≤z≤6%, 1%≤p≤2%, x+y+z+p=100%, and q accounts for 0.03~0.09% of the total mass of the composite powder.

[0008] Preferably, the composition of the red fluorescent glass ceramic material is 33% SiO2-61% Al2O3-4% P2O5-2% TiO2-0.06wt% MnCO3.

[0009] The red fluorescent glass-ceramic material described in this invention comprises an amorphous glass phase and a mullite phase. By controlling the formation and growth of mullite nanocrystals, the doping of red light ions into the mullite nanocrystals becomes increasingly significant. The needle-shaped mullite nanocrystals form a thermally conductive network, thereby improving thermal conductivity. Furthermore, the nanocrystals enhance the material's mechanical properties, minimizing the impact on the glass-ceramic's strength at high temperatures.

[0010] Preferably, the red fluorescent glass ceramic material emits broadband red light around 610nm when excited by a blue LED chip with a wavelength of 450nm to 470nm. The thermal conductivity of the material is greater than 6.8W·m -1 ·K -1 , Vickers hardness is greater than 12GPa.

[0011] On the other hand, the present invention also provides a method for preparing the above-mentioned high thermal conductivity and high strength red fluorescent glass-ceramic material, comprising the following steps:

[0012] (1) According to the stoichiometric ratio of each element in xSiO2-yAl2O3-zP2O5-pTiO2-qRE, SiO2, Al2O3, P2O5, TiO2, and RE powder raw materials of AR purity are weighed respectively, wherein RE is at least one of MnCO3, Eu2O3, Er2O3, Sm2O3, Fe2O3, Cr2O3, Pr2O3, Nd2O3, Tm2O3, Yb2O3, Ho2O3, and Ni2O3, 28%≤x≤38%, 54%≤y≤64%, 2%≤z≤6%, 1%≤p≤2%, x+y+z+p=100%, and q accounts for 0.03-0.09% of the total mass of the raw materials, the powders are placed in an agate mortar for wet grinding, and dried to obtain a raw material mixed powder;

[0013] (2) pouring the raw material mixed powder obtained in step (1) into a platinum crucible, compacting it, and placing it in a lifting furnace, gradually heating it in an air atmosphere until the raw material mixed powder is completely melted, and stirring it evenly;

[0014] (3) pouring the molten glass obtained in step (2) into water for water quenching, drying, and grinding to obtain precursor glass powder;

[0015] (4) The precursor glass powder obtained in step (3) is sequentially subjected to screening, dry pressing and cold isostatic pressing processes to form a green body;

[0016] (5) The green body obtained in step (4) is bonded, sintered, and crystallized to obtain microcrystalline glass.

[0017] Preferably, in step (1), the medium for wet grinding is ethanol, the mass ratio of the total mass of the raw material powder to ethanol is 0.5 to 1, and the grinding time is 1 to 2 hours.

[0018] Preferably, in step (2), the heating rate is 4 to 10° C. / min, the melting temperature is 1500 to 1650° C., and the insulation and stirring time is 4 to 6 hours.

[0019] Preferably, in step (3), the grinding time is 1 to 3 hours.

[0020] Preferably, in step (4), the mesh size of the sieve is 100-200 meshes; the dry pressing pressure is 6-8 MPa, and the holding time is 10-30 s; the cold isostatic pressing pressure is 100-200 MPa, and the holding time is 6-10 min.

[0021] Preferably, in step (5), the bonding sintering temperature is 660-680° C., and the sintering time is 60-120 min.

[0022] Preferably, in step (5), the crystallization temperature is 750-780° C., and the crystallization time is 6-12 minutes.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The special network structure of glass provides a relatively vacuum environment, which effectively promotes the reduction of rare earth ions, reduces production costs and the risks caused by the introduction of inert gas.

[0025] 2. Low temperature crystallization, relatively uniform crystal growth, reduces impurity inclusion and defect formation, thereby improving product quality and yield.

[0026] 3. The small size of needle-shaped mullite nanocrystals can form a heat conduction network and improve the thermal conductivity, which can reach up to 9.8W·m -1 ·K -1 At the same time, nanocrystals can effectively improve the mechanical properties of glass ceramics, and the Vickers hardness can reach 12.3GPa; in addition, nanocrystals can act as the second phase of glass and introduce Rayleigh scattering, thereby improving light conversion efficiency and emission intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The X-ray diffraction patterns of the red fluorescent glass-ceramics prepared in Examples 1, 4, 6, and 8 of the present invention are shown;

[0028] Figure 2 This is a SEM image of the red fluorescent glass-ceramic prepared in Example 1 of the present invention;

[0029] Figure 3 The emission spectra of the red fluorescent glass-ceramics prepared in Examples 1, 4, 6, and 8 of the present invention under excitation at a wavelength of 460 nm are shown;

[0030] Figure 4 Graphs showing the thermal conductivity of the red fluorescent glass-ceramics prepared in Examples 1-8 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The components of a high thermal conductivity and high strength red fluorescent glass ceramic material provided by the present invention are shown in Table 1:

[0033] Table 1 Distribution ratio of each group of Examples 1-8 (by mass percentage)

[0034] <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[P2O5]]> <![CDATA[TiO2]]> <![CDATA[MnCO3]]> Example 1 28％ 64％ 6％ 2％ 0.03％ Example 2 28％ 64％ 6％ 2％ 0.06％ Example 3 28％ 64％ 6％ 2％ 0.09％ Example 4 33％ 59％ 6％ 2％ 0.06％ Example 5 38％ 54％ 6％ 2％ 0.06％ Example 6 33％ 61％ 4％ 2％ 0.06％ Example 7 33％ 63％ 2％ 2％ 0.06％ Example 8 33％ 64％ 2％ 1％ 0.06％

[0035] Example 1:

[0036] The components of this embodiment are weighed according to Example 1 in Table 1, and the total mass of the raw powder is 10g. The mass ratio of the total mass of the raw powder to the solvent ethanol is 0.5. After being fully ground for 1 hour, it is placed in an oven for drying. The dried mixed powder is poured into a platinum crucible and compacted. The platinum crucible is placed in a lifting furnace, heated at a rate of 4°C / min, kept warm at 1500°C and stirred for 4 hours to mix the molten glass evenly and reduce the generation of bubbles. The molten glass is then water quenched and fully ground in an agate grinding mortar for 1 hour before being sieved with 100 mesh. The sieved powder is dry-pressed at a pressure of 6MPa, maintained at pressure for 10s, and then cold isostatically pressed at a pressure of 100MPa, maintained at pressure for 6min; the obtained blank is bonded and sintered at 660°C for 60min, and finally crystallized at 750°C for 6min, and cooled in the furnace to obtain glass ceramics.

[0037] The red fluorescent glass ceramics obtained in Example 1 were subjected to XRD testing. The results showed that the prepared material consisted of mullite phase with a crystallinity of 67.1%. Figure 1 The thermal conductive network formed by the needle-shaped mullite particles can effectively increase the thermal conductivity of glass ceramics, thereby improving the optical properties. Figure 2 The red fluorescent glass ceramic obtained in this embodiment can emit high-intensity broadband red light with a main peak near 612nm under the excitation of 460nm wavelength. Figure 3 The thermal conductivity of the red fluorescent glass ceramic obtained in Example 1 is 6.8 W·m -1 ·K -1 , Vickers hardness is 9.2GPa, such as Figure 4 .

[0038] Example 2:

[0039] The components of this example were weighed according to Example 2 in Table 1, and the total mass of the raw material powder was 10 g. The specific preparation method was the same as that of Example 1.

[0040] The thermal conductivity of the red fluorescent glass ceramic obtained in Example 2 is 7.3 W·m -1 ·K -1 The Vickers hardness is 9.8GPa, such as Figure 4 .

[0041] Example 3:

[0042] The components of this example were weighed according to Example 3 in Table 1, and the total mass of the raw material powder was 10 g. The specific preparation method was the same as that of Example 1.

[0043] The thermal conductivity of the red fluorescent glass ceramic obtained in Example 3 is 7.6 W·m -1 ·K -1 , Vickers hardness is 9.9GPa, such as Figure 4 .

[0044] Example 4:

[0045] The components of this embodiment were weighed according to Example 4 in Table 1, and the total mass of the raw powder was 10 g. The mass ratio of the total mass of the raw powder to the solvent ethanol was 0.5. After being fully ground for 1.5 hours, the powder was placed in an oven for drying. The dried mixed powder was poured into a platinum crucible and compacted. The platinum crucible was placed in a lifting furnace, heated at a rate of 6°C / min, kept warm at 1550°C and stirred for 4 hours to mix the molten glass evenly and reduce the generation of bubbles. The molten glass was then water quenched and fully ground in an agate grinding mortar for 2 hours before being sieved with 140 mesh. The sieved powder was dry-pressed at a pressure of 6 MPa, holding the pressure for 20 seconds, and then cold isostatically pressed at a pressure of 140 MPa, holding the pressure for 8 minutes. The resulting blank was bonded and sintered at 670°C for 80 minutes, and finally crystallized at 760°C for 8 minutes. It was cooled in the furnace to obtain glass ceramics.

[0046] The XRD test of the red fluorescent glass ceramic obtained in Example 4 shows that the prepared material is composed of mullite phase with a crystallinity of 72.8%. Figure 1 The red fluorescent glass ceramics obtained in Example 4 can emit high-intensity broadband red light with a main peak near 618nm under the excitation of 460nm wavelength. The emission intensity is improved to a certain extent compared with Example 1. Figure 3 The thermal conductivity of the red fluorescent glass ceramic obtained in Example 4 is 8 W·m -1 ·K -1 , Vickers hardness is 11.2GPa respectively, such as Figure 4 .

[0047] Example 5:

[0048] The components of this example were weighed according to Example 5 in Table 1, and the total mass of the raw material powder was 10 g. The specific preparation method was the same as that of Example 4.

[0049] The thermal conductivity of the red fluorescent glass ceramic obtained in Example 5 is 8.9 W·m -1 ·K -1 , Vickers hardness is 11.6GPa, such as Figure 4 .

[0050] Example 6:

[0051] The components of this embodiment are weighed according to Example 6 in Table 1, and the total mass of the raw powder is 10g. The mass ratio of the total mass of the raw powder to the solvent ethanol is 1. After being fully ground for 2 hours, it is placed in an oven for drying. The dried mixed powder is poured into a platinum crucible and compacted. The platinum crucible is placed in a lifting furnace, heated at a rate of 8°C / min, kept warm and stirred at 1600°C for 6 hours to mix the molten glass evenly and reduce the generation of bubbles. The molten glass is then water quenched and fully ground in an agate grinding mortar for 3 hours before being sieved with 180 mesh. The sieved powder is dry-pressed at a pressure of 8MPa, holding the pressure for 30s, and then cold isostatically pressed at a pressure of 180MPa, holding the pressure for 10min. The obtained blank is bonded and sintered at 680°C for 100min, and finally crystallized at 770°C for 10min. It is cooled in the furnace to obtain glass ceramics.

[0052] The XRD test of the red fluorescent glass ceramic obtained in Example 6 shows that the prepared material is composed of mullite phase with a crystallinity of 78.6%. Figure 1 The red fluorescent glass ceramic obtained in Example 4 can emit high-intensity broadband red light with a main peak near 598nm under the excitation of 460nm wavelength. The emission intensity reaches the optimal value, which is 1.9 times that of Example 1. Figure 3 The thermal conductivity of the red fluorescent glass ceramic obtained in Example 6 is 9.8 W·m -1 ·K -1 , the Vickers hardness is 12.3GPa, such as Figure 4 .

[0053] Example 7:

[0054] The components of this example were weighed according to Example 7 in Table 1, and the total mass of the raw material powder was 10 g. The specific preparation method was the same as that of Example 6.

[0055] The thermal conductivity of the red fluorescent glass ceramic obtained in Example 7 is 9.6 W·m -1 ·K -1 , Vickers hardness is 12.0GPa, such as Figure 4 .

[0056] Example 8:

[0057] The components of this embodiment were weighed according to Example 8 in Table 1, and the total mass of the raw powder was 10 g. The mass ratio of the total mass of the raw powder to the solvent ethanol was 1. After being fully ground for 2 hours, the mixed powder was placed in an oven for drying. The dried mixed powder was poured into a platinum crucible and compacted. The platinum crucible was placed in a lifting furnace, heated at a rate of 10°C / min, and kept at 1650°C and stirred for 6 hours to ensure that the molten glass was evenly mixed and reduce the generation of bubbles. The molten glass was then water quenched and fully ground in an agate grinding mortar for 3 hours before being sieved through 200 mesh. The sieved powder was dry-pressed at a pressure of 8 MPa, holding the pressure for 30 seconds, and then cold isostatically pressed at a pressure of 200 MPa, holding the pressure for 10 minutes. The resulting blank was bonded and sintered at 680°C for 120 minutes, and finally crystallized at 780°C for 12 minutes. It was then cooled in the furnace to obtain glass ceramics.

[0058] The XRD test of the red fluorescent glass ceramic obtained in Example 8 shows that the prepared material is composed of mullite phase with a crystallinity of 86.2%. Figure 1 The red fluorescent glass ceramic obtained in Example 8 can emit high-intensity broadband red light with a main peak near 615nm under the excitation of 460nm wavelength. Figure 3 The thermal conductivity of the red fluorescent glass ceramic obtained in Example 8 is 9.1 W·m -1 ·K -1 , Vickers hardness is 11.2GPa, such as Figure 4 .

[0059] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A high thermal conductivity and high strength red fluorescent glass ceramic material, characterized in that: The red fluorescent glass-ceramic material includes an amorphous glass phase and a mullite phase, wherein the mullite phase is needle-shaped mullite nanocrystals. The red fluorescent glass-ceramic material is prepared from a composite powder. The composition of the composite powder is xSiO2-yAl2O3-zP2O5-pTiO2-qRE, wherein RE is at least one of MnCO3, Eu2O3, Er2O3, Sm2O3, Fe2O3, Cr2O3, Pr2O3, Nd2O3, Tm2O3, Yb2O3, Ho2O3, and Ni2O3, wherein 28%≤x≤38%, 54%≤y≤64%, 2%≤z≤6%, 1%≤p≤2%, x+y+z+p=100%, and q accounts for 0.03-0.09% of the total mass of the composite powder.

2. The high thermal conductivity and high strength red fluorescent glass ceramic material according to claim 1, characterized in that: The composition of the red fluorescent glass ceramic material is 33% SiO2-61% Al2O3-4% P2O5-2% TiO2-0.06wt% MnCO3.

3. A method for preparing the high thermal conductivity and high strength red fluorescent glass ceramic material according to claim 1 or 2, characterized in that: The steps include: (1) According to the stoichiometric ratio of each element in xSiO2-yAl2O3-zP2O5-pTiO2-qRE, SiO2, Al2O3, P2O5, TiO2, and RE powder raw materials of AR purity are weighed respectively, wherein RE is at least one of MnCO3, Eu2O3, Er2O3, Sm2O3, Fe2O3, Cr2O3, Pr2O3, Nd2O3, Tm2O3, Yb2O3, Ho2O3, and Ni2O3, 28%≤x≤38%, 54%≤y≤64%, 2%≤z≤6%, 1%≤p≤2%, x+y+z+p=100%, and q accounts for 0.03-0.09% of the total mass of the raw materials. The powders are placed in an agate mortar for wet grinding and dried to obtain a raw material mixed powder; (2) Pour the raw material mixed powder obtained in step (1) into a platinum crucible, compact it, and place it in a lifting furnace. Gradually heat it in an air atmosphere until the raw material mixed powder is completely melted, and stir it evenly; (3) pouring the molten glass obtained in step (2) into water for water quenching, drying, and grinding to obtain precursor glass powder; (4) The precursor glass powder obtained in step (3) is subjected to screening, dry pressing and cold isostatic pressing processes in sequence to form a green body; (5) The green body obtained in step (4) is bonded, sintered, and crystallized to obtain glass-ceramics.

4. The method for preparing the high thermal conductivity and high strength red fluorescent glass ceramic material according to claim 3, characterized in that: In step (1), the medium for wet grinding is ethanol, the mass ratio of the total mass of the raw material powder to ethanol is 0.5-1, and the grinding time is 1-2 h.

5. The method for preparing the high thermal conductivity and high strength red fluorescent glass ceramic material according to claim 3, characterized in that: In step (2), the heating rate is 4-10°C / min, the melting temperature is 1500-1650°C, and the insulation and stirring time is 4-6h.

6. The method for preparing the high thermal conductivity and high strength red fluorescent glass ceramic material according to claim 3, characterized in that: In step (3), the grinding time is 1 to 3 hours.

7. The method for preparing the high thermal conductivity and high strength red fluorescent glass ceramic material according to claim 3, characterized in that: In step (4), the mesh size of the sieve is 100-200 meshes; the dry pressing pressure is 6-8 MPa, and the holding time is 10-30 s; the cold isostatic pressing pressure is 100-200 MPa, and the holding time is 6-10 min.

8. The method for preparing the high thermal conductivity and high strength red fluorescent glass ceramic material according to claim 3, characterized in that: In step (5), the bonding sintering temperature is 660-680°C, and the sintering time is 60-120 minutes.

9. The method for preparing the high thermal conductivity and high strength red fluorescent glass ceramic material according to claim 3, characterized in that: In step (5), the crystallization temperature is 750-780° C., and the crystallization time is 6-12 minutes.

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