A porous beryllium oxide ceramic and a method of making the same

Abstract

The present application relates to a kind of porous beryllium oxide ceramic and its preparation method, belong to porous ceramic technical field, to solve the problem at least one of the low porosity, low strength of porous beryllium oxide ceramic prepared by existing method, and sintering process is difficult, sintering is easy to cause powder aggregation, forming poor etc.For example, the present application is combined by specific proportion of nano beryllium oxide, nano magnesium oxide, nano aluminium silicate, polyvinyl butyral, sesbania powder and anhydrous ethanol, each substance is improved by synergistic effect, the porosity, strength etc.Performance of porous beryllium oxide ceramic.The present application realizes the comprehensive promotion of the performance of porous beryllium oxide ceramic by carefully designed component combination and synergistic mechanism, and opens up a broader prospect for the research and application of ceramic materials.

Description

Technical Field

[0001] This invention relates to the field of porous ceramics technology, and in particular to a porous beryllium oxide ceramic and its preparation method. Background Technology

[0002] Beryllium oxide ceramics have always been important components for electronic devices. Due to their high thermal conductivity, good insulation, thermal shock resistance, low loss, and good chemical stability, beryllium oxide ceramics are widely used for heat dissipation in high-power devices such as aerospace equipment, and have been extensively adopted in electronic vacuum devices, high-power module thick-film circuits, packaged devices, and optoelectronic devices.

[0003] Methods for preparing porous ceramic powders include gelation, emulsion, and emulsion precipitation methods. These methods all require the use of organic materials as pore-forming agents. The porous powder needs drying during preparation, and the pore-forming agent achieves pore formation through thermal decomposition, combustion decomposition, and sublimation during drying. The introduction and removal of the pore-forming agent affect the sintering process; simultaneously, the distribution of the pore-forming agent during preparation also affects the porosity, pore size, strength, and grain size of the porous ceramic.

[0004] Most beryllium oxide porous ceramics currently used achieve their porous nature by controlling the amount of paraffin added and sintering at low temperatures to create a certain porosity. However, these porous ceramics suffer from low strength due to their low sintering temperature, making them difficult to process later, and they also exhibit low porosity and poor formability. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a porous beryllium oxide ceramic and its preparation method, in order to solve at least one of the following problems in porous beryllium oxide ceramics prepared by existing methods: low porosity, low strength, difficult sintering process, easy powder agglomeration and poor forming.

[0006] In a first aspect, the present invention provides a porous beryllium oxide ceramic, which is made from the following raw materials in parts by weight: nano-beryllium oxide: 65-85 parts, nano-magnesium oxide: 0.33-0.43 parts, nano-aluminum silicate: 0.33-0.43 parts, polyvinyl butyral: 4-8 parts, guar gum powder: 1-4 parts, and anhydrous ethanol: 12-30 parts.

[0007] Furthermore, the particle size of the nano-beryllium oxide is 100-200 nm, the particle size of the nano-magnesium oxide is 50-150 nm, and the particle size of the nano-aluminum silicate is 50-150 nm.

[0008] Furthermore, the particle size of the guar gum powder is 15-25 μm.

[0009] Furthermore, the porous beryllium oxide ceramic has a porosity of 22-28%, a room temperature flexural strength ≥140MPa, and a grain size ≤20μm.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned porous beryllium oxide ceramic, comprising the following steps:

[0011] (1) Weigh out each raw material according to its weight percentage and set aside;

[0012] (2) Dissolve polyvinyl butyral in anhydrous ethanol to obtain solution A;

[0013] (3) Dissolve the guar gum powder in water to obtain solution B. Mix solution A and solution B to obtain a mixed solution.

[0014] (4) Add nano-beryllium oxide, nano-magnesium oxide and nano-aluminum silicate to the mixed solution, disperse evenly, spray granulate, dry to obtain powder;

[0015] (5) The powder is cold isostatically pressed and sintered at high temperature to obtain the porous beryllium oxide ceramic.

[0016] Furthermore, in step (2), the dissolution is carried out under ultrasound, with an ultrasound power of 1000-1200W and an ultrasound time of 30-40min.

[0017] Furthermore, in step (3), the mass fraction of the guar gum powder in solution B is 10-15%.

[0018] Furthermore, in step (4), the dispersion is carried out under ultrasonic conditions, with the ultrasonic power being 1400-1800W and the ultrasonic time being 2-4h.

[0019] Furthermore, in step (5), the pressure of cold isostatic pressing is 120-150 MPa, and the holding time is 1-2 min.

[0020] Furthermore, in step (5), the high-temperature sintering temperature is 1600-1700℃.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] (1) This invention combines nano-beryllium oxide, nano-magnesium oxide, nano-aluminum silicate, polyvinyl butyral, guar gum powder, and anhydrous ethanol in a specific ratio. Through synergistic effects, these substances improve the porosity, strength, and other properties of porous beryllium oxide ceramics. Among them, magnesium oxide acts as a sintering aid, which can lower the sintering temperature, reduce energy consumption, activate the crystal lattice, and improve the thermal shock resistance of the ceramics; polyvinyl butyral acts as a binder, pore-forming agent, and shaper; anhydrous ethanol has shaping and lubricating effects; guar gum powder improves the sintering performance of porous beryllium oxide ceramics, promotes diffusion and bonding between ceramic particles, accelerates the sintering process, lowers the sintering temperature, increases strength, increases porosity, and facilitates shaping during cold isostatic pressing.

[0023] (2) Through extensive experiments, this invention has found that polyvinyl butyral and guar gum powder exhibit good complementarity in the preparation of porous beryllium oxide. Polyvinyl butyral mainly provides bonding and molding properties, while guar gum powder mainly plays a role in thickening and pore structure regulation. During the preparation of porous beryllium oxide, the two interact, thereby enhancing the bonding force between beryllium oxide particles and stabilizing the pore structure. Through synergistic effects, polyvinyl butyral and guar gum powder can significantly improve the porosity and molding properties of porous beryllium oxide. The increase in porosity helps to increase the specific surface area and adsorption capacity of the material, while the good molding properties make the porous beryllium oxide more stable and reliable in the preparation and application process. Through the carefully designed combination of components and synergistic mechanism, the synergistic effect of each substance enables the porous beryllium oxide to achieve good sintering at high temperatures, realizing a comprehensive improvement in the performance of porous beryllium oxide ceramics and opening up a broader prospect for the research and development and application of ceramic materials.

[0024] (3) The method of the present invention first dissolves polyvinyl butyral in anhydrous ethanol, then dissolves guar gum powder in water, and then mixes and adds nano-beryllium oxide, nano-magnesium oxide, and nano-aluminum silicate. The resulting powder has good formability and can be cold isostatically pressed. The porous beryllium oxide ceramics prepared by the cold isostatic pressing method of the present invention have small grain size and high strength, solving the forming and sintering problems of porous beryllium oxide ceramics.

[0025] (4) The porous beryllium oxide ceramic of the present invention has a porosity of 26.5 to 28.0%, a room temperature flexural strength of 150 to 168 MPa, and a grain size of 8.1 to 11.8 μm.

[0026] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description. Detailed Implementation

[0027] A specific embodiment of the present invention discloses a porous beryllium oxide ceramic, which is made from the following raw materials in parts by weight:

[0028] Nano-beryllium oxide: 65-85 parts, for example, 65 parts, 67 parts, 69 parts, 71 parts, 73 parts, 75 parts, 77 parts, 79 parts, 81 parts, 83 parts, 85 parts;

[0029] Nano magnesium oxide: 0.33-0.43 parts, for example, 0.33 parts, 0.34 parts, 0.35 parts, 0.36 parts, 0.37 parts, 0.38 parts, 0.39 parts, 0.40 parts, 0.41 parts, 0.42 parts, 0.43 parts;

[0030] Nano-aluminum silicate: 0.33-0.43 parts, for example, 0.33 parts, 0.34 parts, 0.35 parts, 0.36 parts, 0.37 parts, 0.38 parts, 0.39 parts, 0.40 parts, 0.41 parts, 0.42 parts, 0.43 parts;

[0031] Polyvinyl butyral: 4-8 parts, for example, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts;

[0032] Guisena powder: 1-4 parts, for example, 1 part, 2 parts, 3 parts, 4 parts;

[0033] Anhydrous ethanol: 12-30 parts, for example, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts.

[0034] This invention utilizes a specific ratio of nano-beryllium oxide, nano-magnesium oxide, nano-aluminum silicate, polyvinyl butyral, guar gum powder, and anhydrous ethanol. Through synergistic effects, these substances improve the porosity, strength, and other properties of porous beryllium oxide ceramics. Magnesium oxide acts as a sintering aid, lowering the sintering temperature and reducing energy consumption. It also activates the crystal lattice, improving the ceramic's thermal shock resistance. Polyvinyl butyral acts as a binder, pore-forming agent, and shaper; anhydrous ethanol provides shaping and lubrication; and guar gum powder improves the sintering performance of porous beryllium oxide ceramics, promoting diffusion and bonding between ceramic particles, accelerating the sintering process, lowering the sintering temperature, increasing strength, and increasing porosity, facilitating shaping during cold isostatic pressing.

[0035] This invention, through extensive experimentation, has discovered that polyvinyl butyral and guar gum powder exhibit excellent complementarity in the preparation of porous beryllium oxide. Polyvinyl butyral primarily provides bonding and molding properties, while guar gum powder mainly functions as a thickener and regulates pore structure. During the preparation of porous beryllium oxide, the two interact, thereby enhancing the bonding force between beryllium oxide particles and stabilizing the pore structure. Through synergistic effects, polyvinyl butyral and guar gum powder can significantly improve the porosity and molding properties of porous beryllium oxide. Increased porosity helps increase the specific surface area and adsorption capacity of the material, while good molding properties make porous beryllium oxide more stable and reliable in preparation and application. Through carefully designed component combinations and synergistic mechanisms, this invention enables porous beryllium oxide to achieve good sintering at high temperatures, realizing a comprehensive improvement in the performance of porous beryllium oxide ceramics and opening up broader prospects for the research and application of ceramic materials.

[0036] In one specific embodiment, the nano-beryllium oxide has a particle size of 100–200 nm, for example, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm; the nano-magnesium oxide has a particle size of 50–150 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm; and the nano-aluminum silicate has a particle size of 50–150 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm.

[0037] It should be noted that, through extensive experimentation, the inventors discovered that porous beryllium oxide ceramic materials prepared with the aforementioned particle size exhibit higher strength.

[0038] In one specific embodiment, the particle size of the guar gum powder is 15-25μm, for example, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm.

[0039] Using the above-mentioned particle size, guar gum powder can significantly improve the strength and porosity of ceramic materials. If the particle size is too high or too low, both strength and porosity will decrease.

[0040] In one specific embodiment, the porous beryllium oxide ceramic has a porosity of 22-28%, for example, 22%, 23%, 24%, 25%, 26%, 27%, or 28%, a room temperature flexural strength ≥140 MPa, for example, 140-160 MPa, and a grain size ≤20 μm, for example, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm.

[0041] Another specific embodiment of the present invention discloses a method for preparing porous beryllium oxide ceramics as described above, comprising the following steps:

[0042] (1) Weigh out each raw material according to its weight percentage and set aside;

[0043] (2) Dissolve polyvinyl butyral in anhydrous ethanol to obtain solution A;

[0044] (3) Dissolve the guar gum powder in water to obtain solution B. Mix solution A and solution B to obtain a mixed solution.

[0045] (4) Add nano-beryllium oxide, nano-magnesium oxide and nano-aluminum silicate to the mixed solution, disperse evenly, spray granulate, dry to obtain powder;

[0046] (5) The powder is cold isostatically pressed and sintered at high temperature to obtain the porous beryllium oxide ceramic.

[0047] It should be noted that the method of the present invention first dissolves polyvinyl butyral in anhydrous ethanol. After dissolving guar gum powder in water, nano-beryllium oxide, nano-magnesium oxide, and nano-aluminum silicate are added. The resulting powder has good formability and can be cold isostatically pressed. The porous beryllium oxide ceramics prepared using the cold isostatic pressing method and raw materials of the present invention have small grain size and high strength, solving the forming and sintering problems of porous beryllium oxide ceramics.

[0048] In one specific embodiment, in step (2), the dissolution is performed under ultrasound, with an ultrasound power of 1000-1200W, for example, 1000W, 1020W, 1040W, 1060W, 1080W, 1100W, 1120W, 1140W, 1160W, 1180W, 1200W, and an ultrasound duration of 30-40min, for example, 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min, 40min.

[0049] In one specific embodiment, in step (3), the mass fraction of the guar gum powder in solution B is 10-15%, for example, 10%, 11%, 12%, 13%, 14%, or 15%.

[0050] It should be noted that when the guar gum powder is at the above-mentioned mass fraction, the resulting powder has good formability.

[0051] In one specific implementation, in step (4), the dispersion is carried out under ultrasonic conditions, the power of which is 1400-1800W, for example, 1400W, 1450W, 1500W, 1550W, 1600W, 1650W, 1700W, 1750W, 1800W, and the ultrasonic time is 2-4h, for example, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3.0h, 3.2h, 3.4h, 3.6h, 3.8h, 4.0h.

[0052] In one specific embodiment, in step (5), the pressure of cold isostatic pressing is 120-150 MPa, for example, 120 MPa, 125 MPa, 130 MPa, 135 MPa, 140 MPa, 145 MPa, 150 MPa, and the holding time is 1-2 min, for example, 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min, 2 min.

[0053] It should be noted that the temperature of cold isostatic pressing is room temperature. Through a large number of experiments, it has been found that the porous ceramics prepared by the above pressure and time have high strength and small grain size.

[0054] In one specific implementation, in step (5), the high-temperature sintering temperature is 1600-1700℃, for example, 1600℃, 1610℃, 1620℃, 1630℃, 1640℃, 1650℃, 1660℃, 1670℃, 1680℃, 1690℃, 1700℃.

[0055] The technical solution of the present invention will be further explained below with reference to specific embodiments.

[0056] Example 1

[0057] This embodiment of a porous beryllium oxide ceramic comprises, by weight, the following raw materials: 65 parts nano-beryllium oxide, 0.33 parts nano-magnesium oxide, 0.33 parts nano-aluminum silicate, 4 parts polyvinyl butyral, 4 parts guar gum powder, and 12 parts anhydrous ethanol. The nano-beryllium oxide has a particle size of 100 nm, the nano-magnesium oxide has a particle size of 50 nm, the nano-aluminum silicate has a particle size of 50 nm, and the guar gum powder has a particle size of 15 μm.

[0058] The preparation method of porous beryllium oxide ceramics in this embodiment includes the following steps:

[0059] (1) Weigh out each raw material according to its weight percentage and set aside;

[0060] (2) Polyvinyl butyral was dissolved in anhydrous ethanol under ultrasound. The power of the ultrasound was 1000W and the ultrasound time was 40min to obtain solution A.

[0061] (3) Dissolve the guar gum powder in water to obtain solution B, wherein the mass fraction of the guar gum powder in solution B is 10%. Mix solution A and solution B to obtain a mixed solution.

[0062] (4) Add nano-beryllium oxide, nano-magnesium oxide and nano-aluminum silicate to the mixed solution, disperse evenly under ultrasound, the power of ultrasound is 1400W, the ultrasound time is 4h, spray granulation, dry to obtain powder;

[0063] (5) The powder is cold isostatically pressed and sintered at high temperature, wherein the pressure of cold isostatic pressing is 120 MPa, the holding time is 2 min, and the high temperature sintering temperature is 1600℃, to obtain the porous beryllium oxide ceramic.

[0064] Example 2

[0065] This embodiment of a porous beryllium oxide ceramic comprises, by weight, the following raw materials: 75 parts nano-beryllium oxide, 0.38 parts nano-magnesium oxide, 0.38 parts nano-aluminum silicate, 6 parts polyvinyl butyral, 2.5 parts guar gum powder, and 21 parts anhydrous ethanol. The nano-beryllium oxide has a particle size of 150 nm, the nano-magnesium oxide has a particle size of 100 nm, the nano-aluminum silicate has a particle size of 100 nm, and the guar gum powder has a particle size of 20 μm.

[0066] The preparation method of porous beryllium oxide ceramics in this embodiment includes the following steps:

[0067] (1) Weigh out each raw material according to its weight percentage and set aside;

[0068] (2) Polyvinyl butyral was added to anhydrous ethanol and dissolved under ultrasound. The power of the ultrasound was 1100W and the ultrasound time was 35min to obtain solution A.

[0069] (3) Dissolve the guar gum powder in water to obtain solution B, wherein the mass fraction of the guar gum powder in solution B is 12.5%. Mix solution A and solution B to obtain a mixed solution.

[0070] (4) Add nano-beryllium oxide, nano-magnesium oxide and nano-aluminum silicate to the mixed solution, disperse evenly under ultrasound, the power of ultrasound is 1600W, the ultrasound time is 3h, spray granulation, dry to obtain powder;

[0071] (5) The powder is cold isostatically pressed and sintered at high temperature, wherein the pressure of cold isostatic pressing is 135 MPa, the holding time is 1.5 min, and the high temperature sintering temperature is 1650 °C, to obtain the porous beryllium oxide ceramic.

[0072] Example 3

[0073] This embodiment of a porous beryllium oxide ceramic comprises, by weight, the following raw materials: 85 parts of nano-beryllium oxide, 0.43 parts of nano-magnesium oxide, 0.43 parts of nano-aluminum silicate, 8 parts of polyvinyl butyral, 1 part of guar gum powder, and 30 parts of anhydrous ethanol. The nano-beryllium oxide has a particle size of 200 nm, the nano-magnesium oxide has a particle size of 150 nm, the nano-aluminum silicate has a particle size of 150 nm, and the guar gum powder has a particle size of 25 μm.

[0074] The preparation method of porous beryllium oxide ceramics in this embodiment includes the following steps:

[0075] (1) Weigh out each raw material according to its weight percentage and set aside;

[0076] (2) Polyvinyl butyral was added to anhydrous ethanol and dissolved under ultrasound. The power of the ultrasound was 1200W and the ultrasound time was 30min to obtain solution A.

[0077] (3) Dissolve the guar gum powder in water to obtain solution B, wherein the mass fraction of the guar gum powder in solution B is 15%. Mix solution A and solution B to obtain a mixed solution.

[0078] (4) Add nano-beryllium oxide, nano-magnesium oxide and nano-aluminum silicate to the mixed solution, disperse evenly under ultrasound, the power of ultrasound is 1800W, the ultrasound time is 2h, spray granulation, dry to obtain powder;

[0079] (5) The powder is cold isostatically pressed and sintered at high temperature, wherein the pressure of cold isostatic pressing is 150 MPa, the holding time is 1 min, and the high temperature sintering temperature is 1700℃, to obtain the porous beryllium oxide ceramic.

[0080] Example 4

[0081] This embodiment of a porous beryllium oxide ceramic comprises, by weight, the following raw materials: 70 parts nano-beryllium oxide, 0.40 parts nano-magnesium oxide, 0.40 parts nano-aluminum silicate, 5 parts polyvinyl butyral, 2 parts guar gum powder, and 20 parts anhydrous ethanol. The nano-beryllium oxide has a particle size of 180 nm, the nano-magnesium oxide has a particle size of 120 nm, the nano-aluminum silicate has a particle size of 120 nm, and the guar gum powder has a particle size of 22 μm.

[0082] The preparation method of porous beryllium oxide ceramics in this embodiment includes the following steps:

[0083] (1) Weigh out each raw material according to its weight percentage and set aside;

[0084] (2) Polyvinyl butyral was dissolved in anhydrous ethanol under ultrasound. The power of the ultrasound was 1050W and the ultrasound time was 38min to obtain solution A.

[0085] (3) Dissolve the guar gum powder in water to obtain solution B, wherein the mass fraction of the guar gum powder in solution B is 14%. Mix solution A and solution B to obtain a mixed solution.

[0086] (4) Add nano-beryllium oxide, nano-magnesium oxide and nano-aluminum silicate to the mixed solution, disperse evenly under ultrasound, the power of ultrasound is 1500W, the ultrasound time is 3h, spray granulation, dry to obtain powder;

[0087] (5) The powder is cold isostatically pressed and sintered at high temperature, wherein the pressure of cold isostatic pressing is 145 MPa, the holding time is 1.8 min, and the high temperature sintering temperature is 1680℃, to obtain the porous beryllium oxide ceramic.

[0088] Comparative Example 1

[0089] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the particle size of the nano-beryllium oxide is 300 nm, the particle size of the nano-magnesium oxide is 180 nm, and the particle size of the nano-aluminum silicate is 180 nm.

[0090] Comparative Example 1-1

[0091] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the particle size of the nano-beryllium oxide is 80 nm, the particle size of the nano-magnesium oxide is 40 nm, and the particle size of the nano-aluminum silicate is 40 nm.

[0092] Comparative Example 2

[0093] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the particle size of the guar gum powder is 10 μm.

[0094] Comparative Example 2-1

[0095] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the particle size of the guar gum powder is 30 μm.

[0096] Comparative Example 3

[0097] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the mass fraction of guar gum powder in step (3) is 8%.

[0098] Experiments revealed that powders treated with cold isostatic pressing could not be molded.

[0099] Comparative Example 3-1

[0100] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the mass fraction of guar gum powder in step (3) is 18%.

[0101] Experiments revealed that powders treated with cold isostatic pressing could not be molded.

[0102] Comparative Example 4

[0103] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2. The difference is that in step (3), the pressure of cold isostatic pressing is 110 MPa and the holding time is 3 min.

[0104] Comparative Example 4-1

[0105] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2. The difference is that in step (3), the pressure of cold isostatic pressing is 160 MPa and the holding time is 0.5 min.

[0106] Comparative Example 5

[0107] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2. The difference is that steps (2) and (3) are removed in the preparation method. In step (4), the raw materials are directly mixed and dispersed evenly, and then dried to obtain powder.

[0108] Experiments revealed that powders treated with cold isostatic pressing could not be molded.

[0109] Comparative Example 6

[0110] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2. The difference is that nano-magnesium oxide is replaced with nano-silica in the raw materials, and the total mass is kept constant by changing the amount of nano-beryllium oxide added.

[0111] Comparative Example 7

[0112] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2. The difference is that the guar gum powder is removed from the raw materials, and the total mass is kept constant by changing the amount of nano-beryllium oxide added.

[0113] Comparative Example 8

[0114] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the amount of nano-beryllium oxide is 60 parts and the amount of polyvinyl butyral is 16 parts.

[0115] Comparative Example 9

[0116] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2. The difference is that nano-alumina silicate is removed from the raw materials, and the total mass is kept constant by changing the amount of nano-beryllium oxide added.

[0117] Comparative Example 10

[0118] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2. The difference is that polyvinyl butyral is removed from the raw materials, and the total mass is kept constant by changing the amount of nano-beryllium oxide added.

[0119] Comparative Example 11

[0120] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the sintering temperature in step (5) of the preparation method is 1550℃.

[0121] Comparative Example 12

[0122] The raw materials and preparation method of the porous beryllium oxide ceramic in this comparative example are the same as those in Example 2, except that the sintering temperature in step (5) of the preparation method is 1750℃.

[0123] Experimental Example 1

[0124] The properties of the porous beryllium oxide ceramics prepared in Examples 1-4 and Comparative Examples 1-9 were tested respectively, and the results are shown in Table 1.

[0125] Table 1

[0126] Group Porosity (%) Flexural strength at room temperature (MPa) Grain size (μm) Example 1 26.8 150 11.8 Example 2 28.0 168 8.1 Example 3 27.1 162 9.2 Example 4 26.5 159 8.6 Comparative Example 1 22.3 141 12.3 Comparative Example 1-1 21.5 143 12.9 Comparative Example 2 20.4 142 13.2 Comparative Example 2-1 21.6 139 14.5 Comparative Example 3 -- -- -- Comparative Example 3-1 -- -- -- Comparative Example 4 20.1 138 20.9 Comparative Example 4-1 19.8 136 21.6 Comparative Example 5 -- -- -- Comparative Example 6 18.3 137 21.4 Comparative Example 7 17.9 136 24.1 Comparative Example 8 19.4 143 22.6 Comparative Example 9 18.1 134 23.5 Comparative Example 10 17.1 129 26.8 Comparative Example 11 19.8 139 23.6 Comparative Example 12 21.3 128 25.6

[0127] Compared with Example 2, Comparative Examples 1 and 1-1 show that the particle size of nano-beryllium oxide and nano-magnesium oxide is not within the range defined by the present invention, resulting in porous beryllium oxide ceramics with lower porosity, lower room temperature flexural strength, and larger grain size.

[0128] Compared with Example 2, Comparative Examples 2 and 2-1 show that the particle size of the guar powder is not within the range defined by the present invention, resulting in porous beryllium oxide ceramics with lower porosity, lower room temperature flexural strength, and larger grain size.

[0129] Compared with Example 2, Comparative Examples 3 and 3-1 show that the mass fraction of guar gum powder is outside the range defined by the present invention, and the powder cannot be formed by cold isostatic pressing.

[0130] Compared with Example 2, Comparative Examples 4 and 4-1 have cold isostatic pressing pressure and holding time that are not within the range defined by the present invention, resulting in porous beryllium oxide ceramics with lower porosity, lower room temperature flexural strength, and larger grain size.

[0131] Compared with Example 2, Comparative Example 5 directly mixes the raw materials without using the method of the present invention, and the powder cannot be formed after cold isostatic pressing.

[0132] Compared to Example 2, Comparative Examples 6-7 and 9-10, by replacing nano-magnesium oxide with nano-silica, or by removing guar gum powder, nano-aluminate silica, or polyvinyl butyral from the raw materials, resulted in porous beryllium oxide ceramics with lower porosity, lower room temperature flexural strength, and larger grain size. This demonstrates that the high porosity, high strength, and small grain size of the porous beryllium oxide ceramics of this application can only be obtained through the synergistic effect of the raw materials used in this invention.

[0133] Compared with Example 2, the porous beryllium oxide ceramic obtained by Comparative Example 8, which is not in the proportions specified in this application, has lower porosity, lower room temperature flexural strength, and larger grain size.

[0134] Compared with Example 2, the porous beryllium oxide ceramics prepared in Comparative Examples 11-12, which are not sintered at the temperature specified in this invention, have lower porosity, lower room temperature flexural strength, and larger grain size.

[0135] The inventors also conducted the above-mentioned experiments on other embodiments, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0136] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A porous beryllium oxide ceramic, characterized in that, It is made from the following raw materials in parts by weight: nano beryllium oxide: 65-85 parts, nano magnesium oxide: 0.33-0.43 parts, nano aluminum silicate: 0.33-0.43 parts, polyvinyl butyral: 4-8 parts, guar gum powder: 1-4 parts and anhydrous ethanol: 12-30 parts.

2. The porous beryllium oxide ceramic according to claim 1, characterized in that, The nano-beryllium oxide has a particle size of 100-200 nm, the nano-magnesium oxide has a particle size of 50-150 nm, and the nano-aluminum silicate has a particle size of 50-150 nm.

3. A porous beryllium oxide ceramic according to claim 1 or 2, characterized in that, The particle size of the guar gum powder is 15-25 μm.

4. A porous beryllium oxide ceramic according to claim 1 or 2, characterized in that, The porous beryllium oxide ceramic has a porosity of 22-28%, a room temperature flexural strength ≥140MPa, and a grain size ≤20μm.

5. A method for preparing porous beryllium oxide ceramic according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Weigh out each raw material according to its weight percentage and set aside; (2) Dissolve polyvinyl butyral in anhydrous ethanol to obtain solution A; (3) Dissolve the guar gum powder in water to obtain solution B. Mix solution A and solution B to obtain a mixed solution. (4) Add nano-beryllium oxide, nano-magnesium oxide and nano-aluminum silicate to the mixed solution, disperse evenly, spray granulate, dry to obtain powder; (5) The powder is cold isostatically pressed and sintered at high temperature to obtain the porous beryllium oxide ceramic.

6. The preparation method according to claim 5, characterized in that, In step (2), the dissolution is carried out under ultrasound, with an ultrasound power of 1000-1200W and an ultrasound time of 30-40min.

7. The preparation method according to claim 5, characterized in that, In step (3), the mass fraction of the guar gum powder in solution B is 10-15%.

8. The preparation method according to claim 5, characterized in that, In step (4), the dispersion is carried out under ultrasonic conditions, with the ultrasonic power being 1400-1800W and the ultrasonic time being 2-4h.

9. The preparation method according to claim 5, characterized in that, In step (5), the pressure of cold isostatic pressing is 120-150 MPa, and the holding time is 1-2 min.

10. The preparation method according to claim 5, characterized in that, In step (5), the high-temperature sintering temperature is 1600-1700℃.