Micron-sized spherical boron carbide ceramic and preparation method thereof

Abstract

The present invention relates to the technical field of boron carbide ceramics, specifically a micron-sized spherical boron carbide ceramic and a preparation method thereof. A micron-sized spherical boron carbide ceramic comprises 100 parts of a mixed powder and 90 parts of a mixed solution, wherein the mixed powder comprises 89-92 parts of boron carbide micropowder, 3 parts of silicon carbide micropowder, 2 parts of zirconium oxide micropowder, 2-5 parts of diamond micropowder and 1 part of titanium boride micropowder. The preparation method comprises the following steps: S1. batching; S2. mixing; S3. microsphere molding; S4. screening; S5. sintering. The micron-sized spherical boron carbide of the present application has a narrow particle size distribution and uniform particles, which is conducive to the dispersion and sliding of the micro-ceramic in the application system, can form a relatively dense stacking, obtain the characteristics of high filling and low viscosity, and can reduce the wear rate of equipment such as mixers and molding machines.

Description

Technical Field

[0001] The present invention relates to the technical field of boron carbide ceramics, in particular to a micron-sized spherical boron carbide ceramic and a preparation method thereof. Background Art

[0002] Boron carbide, with its high hardness, high thermal conductivity, and high-temperature heat resistance, is commonly used as grinding wheels, high-thermal conductivity fillers in organic polymers, and components for semiconductor manufacturing equipment. Micron-sized spherical boron carbide ceramics, with their high specific surface area, controllable monodispersity, and adjustable porosity, have further expanded their potential for application in inertial confinement fusion targets, nuclear reactor moderators, and catalyst supports.

[0003] Boron carbide particles prepared by the general process route have irregular shapes with sharp edges in their untreated crushed state after pulverization, and such powders have poor fluidity and filling capacity. For thermally conductive composite materials, increasing the filling capacity can produce composite materials with higher thermal conductivity. Among various powder morphologies, spherical and quasi-spherical powders have better fluidity, which can effectively reduce the effect of fillers on the viscosity of the filling system, thereby achieving a higher filling capacity. Micron-sized spherical boron carbide ceramics, as fillers in thermal conductive adhesives, can significantly improve the thermal conductivity of the mixture, reduce the expansion coefficient, and increase the strength of the adhesive after curing. The spherical shape is conducive to the dispersion and sliding of the ceramic particles in the system, and forms a relatively dense stacking, resulting in a highly filled, low-viscosity, and highly thermally conductive mixture.

[0004] Based on the above technical status, the present application provides a micron-sized spherical boron carbide ceramic and a preparation method thereof, which are used to prepare micron-sized spherical boron carbide ceramics with uniform particle size and stronger fluidity. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a micron-sized spherical boron carbide ceramic and a preparation method thereof.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a micron-sized spherical boron carbide ceramic, the raw material components are composed of the following in parts by weight:

[0007] The method comprises 100 parts of a mixed powder and 90 parts of a mixed solution, wherein the mixed powder comprises 89-92 parts of boron carbide micropowder, 3 parts of silicon carbide micropowder, 2 parts of zirconium oxide micropowder, 2-5 parts of diamond micropowder and 1 part of titanium boride micropowder;

[0008] The mixed solution includes 75 parts of deionized water, 4 parts of liquid carbon black, 2 parts of polyvinyl alcohol, 8 parts of phenolic resin and 1 part of n-octanol.

[0009] As an optimization, the particle size D50 value of the boron carbide micropowder is in the range of 0.5-2 μm; the particle size D50 value of the silicon carbide micropowder is in the range of 1-2 μm; the particle size D50 value of the zirconium oxide micropowder is in the range of 1-2 μm; the particle size D50 value of the diamond micropowder is in the range of 0.5-1 μm; and the particle size D50 value of the titanium boride is in the range of 1-5 μm.

[0010] As an optimization, the boron carbide powder is a boron carbide material with a boron-11 enrichment of 99%.

[0011] As an optimization, the solid content of the liquid carbon black is 20%.

[0012] A method for preparing micron-sized spherical boron carbide ceramics, used for any of the above-mentioned micron-sized spherical boron carbide ceramics, comprises the following steps:

[0013] S1 Ingredients: According to the ratio of 89-92 parts of boron carbide powder, 3 parts of silicon carbide powder, 2 parts of zirconium oxide powder, 2-5 parts of diamond powder and 1 part of titanium boride powder, and the powders are thoroughly mixed to obtain 100 parts by mass of a mixed powder;

[0014] Prepare a mixed solution in the proportion of 75 parts deionized water, 4 parts liquid carbon black, 2 parts polyvinyl alcohol, 8 parts phenolic resin and 1 part n-octanol, and set aside;

[0015] S2 mixing: The mixed powder and mixed solution obtained in step S1 were added to the inside of a conical mixer, and 200 parts by mass of boron carbide grinding balls were added to the inside of the conical mixer and mixed thoroughly for 24h to obtain a uniformly mixed slurry;

[0016] S3 microsphere forming: The slurry obtained in step S2 is put into a spray granulation device for spray granulation to obtain unsintered micron-sized boron carbide spherical particles;

[0017] S4 screening: using a multi-layer vibrating screen to sieve the unsintered micron-sized boron carbide spherical particles obtained in step S3 to obtain unsintered micron-sized boron carbide spherical particles of suitable size;

[0018] S5. Sintering: The unsintered micron-sized boron carbide spherical particles obtained by screening in step S4 are dispersed and placed in a customized graphite holder, and then placed in a vacuum sintering furnace for pressureless sintering.

[0019] As an optimization, during the sintering process of step S5, the vacuum sintering furnace is evacuated during the initial heating process of sintering, and the vacuum degree is maintained at <20Pa; after the temperature in the vacuum sintering furnace is raised to 1000°C, argon gas is filled into the vacuum sintering furnace for protection, and the temperature is continued to be raised to 1750-1900°C and kept warm for 3-4 hours. After the insulation is completed, the vacuum sintering furnace is naturally cooled to room temperature, and after being taken out, micron-sized spherical boron carbide ceramics with an average particle size of <50μm are obtained.

[0020] As an optimization, in step S2, the boron carbide grinding balls are cylindrical balls with a boron carbide content greater than 95% and a size of φ12 mm.

[0021] As an optimization, in step S3, the air inlet temperature of the spray granulation equipment is 240-260° C., and the atomizer speed is 170-200 r / min.

[0022] As an optimization, the surface of the customized mold is uniformly provided with hemispherical grooves with a diameter of r≤100 μm, and the center points of adjacent hemispherical grooves are spaced 150 μm apart.

[0023] As an optimization, a vibration device is provided inside the vacuum sintering furnace. The vibration device is connected to the customized mold and is used to vibrate the vibration mold so that the micron-sized boron carbide spherical particles are in a vibrating state during the sintering process.

[0024] This solution provides a micron-sized spherical boron carbide ceramic and a preparation method thereof, which has the following advantages:

[0025] The micron-sized spherical boron carbide of the present application has a narrow particle size distribution and uniform particles, which is conducive to the dispersion and sliding of the micro-ceramic in the application system, can form a relatively dense stacking, obtain high filling and low viscosity characteristics, and can reduce the wear rate of equipment such as mixing machines and molding machines;

[0026] This product's micron-sized spherical boron carbide ceramics use boron carbide-11 with a boron-11 enrichment of 99%, which can effectively increase the material density and improve the densification of boron carbide ceramics during the sintering process, which is conducive to the production of microspheres;

[0027] Adding artificial diamond powder can effectively improve the electrical conductivity, thermal conductivity and material strength of micron-sized spherical boron carbide ceramics;

[0028] The preparation method of the present application uses a vacuum sintering furnace equipped with a vibration device and a customized mold, which can keep the customized mold in a vibrating state during the sintering process, effectively avoiding the occurrence of adhesion, burrs and other phenomena in the micron-sized spherical boron carbide ceramics during the sintering process, and effectively improving the particle size concentration and fluidity of the micron-sized spherical boron carbide ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the micron-sized spherical boron carbide ceramic of Example 2 under a scanning electron microscope of the present invention.

[0030] Figure 2 Schematic diagram of the micron-sized spherical boron carbide ceramic of Example 3 under a scanning electron microscope of the present invention.

[0031] Figure 3 Schematic diagram of the axial side of the customized graphite bracket for the present invention.

[0032] Figure 4 A schematic front view of a custom graphite bracket according to the present invention. DETAILED DESCRIPTION

[0033] A micron-sized spherical boron carbide ceramic, characterized in that the raw material components are composed of the following in parts by weight:

[0034] The method comprises 100 parts of a mixed powder and 90 parts of a mixed solution, wherein the mixed powder comprises 89-92 parts of boron carbide micropowder, 3 parts of silicon carbide micropowder, 2 parts of zirconium oxide micropowder, 2-5 parts of diamond micropowder and 1 part of titanium boride micropowder;

[0035] The mixed solution includes 75 parts of deionized water, 4 parts of liquid carbon black, 2 parts of polyvinyl alcohol, 8 parts of phenolic resin and 1 part of n-octanol.

[0036] The particle size D50 value of the boron carbide micropowder is in the range of 0.5-2 μm; the particle size D50 value of the silicon carbide micropowder is in the range of 1-2 μm; the particle size D50 value of the zirconium oxide micropowder is in the range of 1-2 μm; the particle size D50 value of the diamond micropowder is in the range of 0.5-1 μm; and the particle size D50 value of the titanium boride is in the range of 1-5 μm.

[0037] The boron carbide powder is a boron carbide material with a boron-11 enrichment of 99%.

[0038] The solid content of the liquid carbon black is 20%.

[0039] A method for preparing micron-sized spherical boron carbide ceramics comprises the following steps:

[0040] S1 Ingredients: According to the ratio of 89-92 parts of boron carbide powder, 3 parts of silicon carbide powder, 2 parts of zirconium oxide powder, 2-5 parts of diamond powder and 1 part of titanium boride powder, and the powders are thoroughly mixed to obtain 100 parts by mass of a mixed powder;

[0041] Prepare a mixed solution in the proportion of 75 parts deionized water, 4 parts liquid carbon black, 2 parts polyvinyl alcohol, 8 parts phenolic resin and 1 part n-octanol, and set aside;

[0042] S2 mixing: The mixed powder and mixed solution obtained in step S1 were added to the inside of a conical mixer, and 200 parts by mass of boron carbide grinding balls were added to the inside of the conical mixer and mixed thoroughly for 24h to obtain a uniformly mixed slurry;

[0043] The boron carbide grinding balls are cylindrical balls with a boron carbide content of more than 95% and a size of φ12mm;

[0044] S3 microsphere forming: The slurry obtained in step S2 was put into a spray granulation device for spray granulation, the spray granulation equipment inlet temperature was 240-260 ° C, the atomizer speed was 170-200r / min, to obtain unsintered micron-sized boron carbide spherical particles;

[0045] S4 screening: using a multi-layer vibrating screen to sieve the unsintered micron-sized boron carbide spherical particles obtained in step S3 to obtain unsintered micron-sized boron carbide spherical particles of suitable size;

[0046] Using a multi-layer vibrating screen to remove undersized and oversized unsintered micron-sized boron carbide spherical particles can also yield ceramic spheres of varying sizes. This process also facilitates the separation of slightly adhered unsintered spherical particles through vibration, reducing the likelihood of clumping in the ceramic microsphere product. Depending on the desired micron-sized boron carbide spherical particle size, multi-layer vibrating screens of varying sizes can be used for screening. The specific selection process is based on experience and will not be detailed here.

[0047] S5 sintering: The unsintered micron-sized boron carbide spherical particles obtained by screening in step S4 are dispersed and placed in a custom graphite holder and added to a vacuum sintering furnace for pressureless sintering;

[0048] The pressureless sintering heating process is as follows: when the furnace temperature starts at -1000°C, the heating rate is 10-20°C / min; then the temperature is kept at this temperature for 1 hour; when the temperature continues to rise to 1000-1900°C, the heating rate is 4-7°C / min, and the temperature is kept at this temperature for 3-4 hours. The furnace body is then slowly cooled to room temperature. When the furnace temperature is below 1000°C, the furnace is in a vacuum state with a vacuum degree of less than 20kPa. When the furnace temperature is above 1000°C, argon gas is filled for protection and the furnace is at normal pressure.

[0049] During the initial heating process of sintering, the vacuum sintering furnace is evacuated to maintain a vacuum degree of less than 20 Pa; after the temperature in the vacuum sintering furnace is raised to 1000°C, argon gas is filled into the vacuum sintering furnace for protection, and the temperature is further raised to 1750-1900°C and kept at this temperature for 3-4 hours. After the heat preservation is completed, the vacuum sintering furnace is naturally cooled to room temperature, and micron-sized spherical boron carbide ceramics with an average particle size of less than 50 μm are obtained after being taken out;

[0050] The vacuum sintering furnace is equipped with a vibration device inside, which is connected to the customized mold and is used to vibrate the vibration mold to keep the micron-sized boron carbide spherical particles in a vibrating state during the sintering process;

[0051] The surface of the customized graphite bracket is evenly provided with hemispherical grooves with a diameter of r≤100 μm, and the center points of adjacent hemispherical grooves are spaced 150 μm apart.

[0052] The groove diameter of the customized graphite bracket can be manufactured and selected according to actual production requirements. In the embodiment of the present application, a customized graphite bracket with r=100 μm is used. Example 1:

[0053] A micron-sized spherical boron carbide ceramic, the raw materials of which include 89 parts of boron carbide micropowder, 3 parts of silicon carbide micropowder, 2 parts of zirconium oxide micropowder, 5 parts of diamond micropowder and 1 part of titanium boride micropowder; 75 parts of deionized water, 4 parts of liquid carbon black, 2 parts of polyvinyl alcohol, 8 parts of phenolic resin and 1 part of n-octanol.

[0054] A method for preparing micron-sized spherical boron carbide ceramics comprises the following steps:

[0055] S1 Ingredients: Prepared in accordance with the above ratio to obtain 100 parts by mass of a mixed powder and 90 parts by mass of a mixed solution, set aside;

[0056] S2 mixing: The mixed powder and mixed solution obtained in step S1 were added to the inside of a conical mixer, and 200 parts by mass of boron carbide grinding balls were added to the inside of the conical mixer and mixed thoroughly for 24h to obtain a uniformly mixed slurry;

[0057] The boron carbide grinding balls are cylindrical balls with a boron carbide content of 97% and a size of φ12mm;

[0058] S3 microsphere forming: The slurry obtained in step S2 was put into a spray granulation device for spray granulation, the spray granulation equipment inlet temperature was 240 ° C, the atomizer speed was 170r / min; to obtain unsintered micron-sized boron carbide spherical particles;

[0059] S4 screening: using a multi-layer vibrating screen with a pore size of 100μm, the unsintered micron-sized boron carbide spherical particles obtained in step S3 were sieved to obtain unsintered micron-sized boron carbide spherical particles;

[0060] S5 sintering: The unsintered micron-sized boron carbide spherical particles obtained by screening in step S4 are dispersed and placed in a custom graphite holder and added to a vacuum sintering furnace for pressureless sintering;

[0061] The pressureless sintering heating process is as follows: starting at -1000°C, the furnace temperature is increased at a rate of 11°C / min; then held at this temperature for 1 hour; the temperature continues to rise to 1000-1900°C at a rate of 4.2°C / min, and finally held at this temperature for 3 hours, after which the furnace is slowly cooled to room temperature. When the furnace temperature is below 1000°C, the furnace is in a vacuum state with a vacuum degree of 19.1 kPa. When the furnace temperature is above 1000°C, argon gas is filled for protection and the furnace is at atmospheric pressure.

[0062] During the initial heating process of sintering, the vacuum sintering furnace is evacuated to maintain a vacuum degree of <20Pa; after the temperature in the vacuum sintering furnace is raised to 1000°C, argon gas is filled into the vacuum sintering furnace for protection, and the temperature is further raised to 1750-1900°C and kept warm for 3 hours. After the heat preservation is completed, the vacuum sintering furnace is naturally cooled to room temperature, and micron-sized spherical boron carbide ceramics are obtained after being taken out;

[0063] During the sintering process, the vibration mold is vibrated by a vibration device, so that the micron-sized boron carbide spherical particles are in a vibrating state during the sintering process. Example 2:

[0064] A micron-sized spherical boron carbide ceramic, the raw materials of which include 90.5 parts of boron carbide micropowder, 3 parts of silicon carbide micropowder, 2 parts of zirconium oxide micropowder, 3.5 parts of diamond micropowder and 1 part of titanium boride micropowder; 75 parts of deionized water, 4 parts of liquid carbon black, 2 parts of polyvinyl alcohol, 8 parts of phenolic resin and 1 part of n-octanol.

[0065] A method for preparing micron-sized spherical boron carbide ceramics comprises the following steps:

[0066] S1 Ingredients: Prepared in accordance with the above ratio to obtain 100 parts by mass of a mixed powder and 90 parts by mass of a mixed solution, set aside;

[0067] S2 mixing: The mixed powder and mixed solution obtained in step S1 were added to the inside of a conical mixer, and 200 parts by mass of boron carbide grinding balls were added to the inside of the conical mixer and mixed thoroughly for 24h to obtain a uniformly mixed slurry;

[0068] The boron carbide grinding balls are cylindrical balls with a boron carbide content of 97% and a size of φ12mm;

[0069] S3 microsphere forming: The slurry obtained in step S2 was put into a spray granulation device for spray granulation, the spray granulation equipment inlet air temperature was 260 ° C, the atomizer speed was 200r / min; to obtain unsintered micron-sized boron carbide spherical particles;

[0070] S4 screening: using a multi-layer vibrating screen to sieve the unsintered micron-sized boron carbide spherical particles obtained in step S3 to obtain unsintered micron-sized boron carbide spherical particles of suitable size;

[0071] S5 sintering: The unsintered micron-sized boron carbide spherical particles obtained by screening in step S4 are dispersed and placed in a custom graphite holder and added to a vacuum sintering furnace for pressureless sintering;

[0072] The pressureless sintering heating process is as follows: starting at -1000°C, the furnace temperature is increased at a rate of 19.4°C / min; then held at this temperature for 1 hour; continuing to increase the temperature between 1000-1900°C at a rate of 6.7°C / min, and finally held at this temperature for 4 hours, after which the furnace is slowly cooled to room temperature. When the furnace temperature is below 1000°C, the furnace is in a vacuum state with a vacuum degree of 19.2 kPa. When the furnace temperature is above 1000°C, argon gas is filled for protection and the furnace is at atmospheric pressure.

[0073] During the initial heating process of sintering, the vacuum sintering furnace is evacuated to maintain a vacuum degree of <20Pa; after the temperature in the vacuum sintering furnace is raised to 1000°C, argon gas is filled into the vacuum sintering furnace for protection, and the temperature is further raised to 1750-1900°C and kept warm for 4 hours. After the insulation is completed, the vacuum sintering furnace is naturally cooled to room temperature, and micron-sized spherical boron carbide ceramics are obtained after being taken out;

[0074] The vibration mold is vibrated by a vibration device, so that the micron-sized boron carbide spherical particles are in a vibrating state during the sintering process. Example 3:

[0075] A micron-sized spherical boron carbide ceramic, the raw materials of which include 92 parts of boron carbide micropowder, 3 parts of silicon carbide micropowder, 2 parts of zirconium oxide micropowder, 2 parts of diamond micropowder and 1 part of titanium boride micropowder; 75 parts of deionized water, 4 parts of liquid carbon black, 2 parts of polyvinyl alcohol, 8 parts of phenolic resin and 1 part of n-octanol.

[0076] A method for preparing micron-sized spherical boron carbide ceramics comprises the following steps:

[0077] S1 Ingredients: Prepared in accordance with the above ratio to obtain 100 parts by mass of a mixed powder and 90 parts by mass of a mixed solution, set aside;

[0078] S2 mixing: The mixed powder and mixed solution obtained in step S1 were added to the inside of a conical mixer, and 200 parts by mass of boron carbide grinding balls were added to the inside of the conical mixer and mixed thoroughly for 24h to obtain a uniformly mixed slurry;

[0079] The boron carbide grinding balls are cylindrical balls with a boron carbide content of 97% and a size of φ12mm;

[0080] S3 microsphere forming: The slurry obtained in step S2 was put into a spray granulation device for spray granulation, the spray granulation equipment inlet temperature was 250 ° C, the atomizer speed was 185r / min; to obtain unsintered micron-sized boron carbide spherical particles;

[0081] S4 screening: using a multi-layer vibrating screen to sieve the unsintered micron-sized boron carbide spherical particles obtained in step S3 to obtain unsintered micron-sized boron carbide spherical particles of suitable size;

[0082] S5 sintering: The unsintered micron-sized boron carbide spherical particles obtained by screening in step S4 are dispersed and placed in a custom graphite holder and added to a vacuum sintering furnace for pressureless sintering;

[0083] The pressureless sintering heating process is as follows: when the furnace temperature starts at -1000°C, the heating rate is 15.1°C / min; then the temperature is maintained for 1 hour; when the temperature continues to rise to 1000-1900°C, the heating rate is 5.3°C / min, and the temperature is maintained for 3.5 hours. The furnace body is then slowly cooled to room temperature. When the furnace temperature is below 1000°C, the furnace is in a vacuum state with a vacuum degree of 19.6kPa. When the furnace temperature is above 1000°C, argon gas is filled for protection and the furnace is at normal pressure.

[0084] During the initial heating process of sintering, the vacuum sintering furnace is evacuated to maintain a vacuum degree of <20Pa; after the temperature in the vacuum sintering furnace is raised to 1000°C, argon gas is filled into the vacuum sintering furnace for protection, and the temperature is further raised to 1750-1900°C and kept warm for 3.5 hours. After the insulation is completed, the vacuum sintering furnace is naturally cooled to room temperature, and micron-sized spherical boron carbide ceramics are obtained after being taken out;

[0085] The vibration mold is vibrated by a vibration device, so that the micron-sized boron carbide spherical particles are in a vibrating state during the sintering process.

[0086] Comparative Example 1: Ordinary boron carbide was used, and the remaining raw material ratios and process parameters were the same as those in Example 1.

[0087] Comparative Example 2: The raw material ratio and process parameters of Example 1 were adopted, a flat graphite holder was used, and no customized graphite holder was used.

[0088] Comparative Example 3: The raw material ratio and process parameters of Example 1 were adopted, but no vibration device was used.

[0089] Comparative Example 4: The raw material ratio and process parameters of Example 1 were adopted, but the customized graphite holder and vibration device were not used.

[0090] Examples 1-3 and Comparative Examples 1 and 3 all used customized graphite holders with r=100 μm, Comparative Example 2 used a common flat graphite holder, and Comparative Example 4 used a common flat graphite holder. The mold was in a stationary state during the sintering process.

[0091] Table 1. Experimental index data table of micron-sized spherical boron carbide ceramics obtained in Examples 1-3 and Comparative Examples 1-4.

[0092]

[0093] According to the above table, compared with Example 3, adding more diamonds within a reasonable mass fraction range is beneficial to improving the density and thermal conductivity of the product.

[0094] Compared with Comparative Example 1, Example 1 has a higher density of micron-sized spherical boron carbide, and its specific gravity data is more suitable for use as a filler in thermal conductive adhesive, and it has relatively excellent density parameters.

[0095] Comparison between Example 1 and Comparative Examples 2-4 shows that the spherical boron carbide ceramics prepared by the method for preparing micron-sized spherical boron carbide ceramics of the present application minimize the adhesion between microspheres and the burrs generated after adhesion and breakage, can achieve a finer particle size, and have a high spheroidization rate. Its fluidity performance is also better.

[0096] Combine Figure 1 and Figure 2 It can be seen that the micron-sized spherical boron carbide ceramics prepared by the preparation method of the micron-sized spherical boron carbide ceramics of the present application have the characteristics of high spheroidization rate, can basically achieve round or nearly round, with few surface burrs, high dispersion, and little adhesion, so that it has high fluidity, high filling properties, etc. The spherical shape is conducive to the dispersion and sliding of the micro-ceramic particles in the system, and forms a relatively dense stacking, thereby obtaining a mixture with high filling, low viscosity, and high thermal conductivity; the mixture can greatly reduce the wear of equipment such as mixers, molding machines and molds, and can extend the service life of the equipment.

[0097] At the same time, this product has the advantages of high fluidity and high thermal conductivity. When used as a filler for thermal conductive adhesive, it can significantly improve the thermal conductivity of the mixture, reduce the expansion coefficient, and increase the strength of the adhesive after curing.

[0098] The above-mentioned specific embodiments are only specific cases of the present invention. The patent protection scope of the present invention includes but is not limited to the product form and style of the above-mentioned specific embodiments. Any micron-sized spherical boron carbide ceramic and its preparation method that conform to the claims of the present invention and any appropriate changes or modifications made thereto by ordinary technicians in the corresponding technical field shall fall within the patent protection scope of the present invention.

Claims

1. A method for preparing micron-sized spherical boron carbide ceramics, characterized by: The steps include: S1 Ingredients: According to the ratio of 89-92 parts of boron carbide powder, 3 parts of silicon carbide powder, 2 parts of zirconium oxide powder, 2-5 parts of diamond powder and 1 part of titanium boride powder, and the powders are thoroughly mixed to obtain 100 parts by mass of a mixed powder; Prepare a mixed solution in the proportion of 75 parts deionized water, 4 parts liquid carbon black, 2 parts polyvinyl alcohol, 8 parts phenolic resin and 1 part n-octanol, and set aside; S2 mixing: The mixed powder and mixed solution obtained in step S1 were added to the inside of a conical mixer, and 200 parts by mass of boron carbide grinding balls were added to the inside of the conical mixer and mixed thoroughly for 24h to obtain a uniformly mixed slurry; S3 microsphere forming: The slurry obtained in step S2 is put into a spray granulation device for spray granulation to obtain unsintered micron-sized boron carbide spherical particles; S4 screening: using a multi-layer vibrating screen to sieve the unsintered micron-sized boron carbide spherical particles obtained in step S3 to obtain unsintered micron-sized boron carbide spherical particles of suitable size; S5 sintering: The unsintered micron-sized boron carbide spherical particles obtained by screening in step S4 are dispersed and placed in a custom graphite holder and added to a vacuum sintering furnace for pressureless sintering; The boron carbide powder is a boron carbide material with a boron-11 enrichment of 99%; The vacuum sintering furnace is equipped with a vibration device, which is connected to a customized graphite holder and is used to vibrate the vibration mold, so that the micron-sized boron carbide spherical particles are in a vibrating state during the sintering process; During the sintering process in step S5, the vacuum sintering furnace is evacuated during the initial heating process of sintering, and the vacuum degree is maintained at <20Pa; after the temperature in the vacuum sintering furnace is raised to 1000°C, argon gas is filled into the vacuum sintering furnace for protection, and the temperature is continued to be raised to 1750-1900°C and kept warm for 3-4 hours. After the insulation is completed, the vacuum sintering furnace is naturally cooled to room temperature, and after being taken out, micron-sized spherical boron carbide ceramics with an average particle size of <50μm are obtained.

2. The method for preparing micron-sized spherical boron carbide ceramics according to claim 1, wherein: In step S2, the boron carbide grinding balls are cylindrical balls with a boron carbide content greater than 95% and a size of φ12 mm.

3. The method for preparing micron-sized spherical boron carbide ceramics according to claim 1, wherein: In step S3, the air inlet temperature of the spray granulation equipment is 240-260° C., and the atomizer speed is 170-200 r / min.

4. The method for preparing micron-sized spherical boron carbide ceramics according to claim 1, wherein: The surface of the customized graphite bracket is evenly provided with hemispherical grooves with a diameter of r≤100 μm, and the center points of adjacent hemispherical grooves are spaced 150 μm apart.

5. A micron-sized spherical boron carbide ceramic prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The components of the raw materials are composed as follows according to weight parts: The method comprises 100 parts of a mixed powder and 90 parts of a mixed solution, wherein the mixed powder comprises 89-92 parts of boron carbide micropowder, 3 parts of silicon carbide micropowder, 2 parts of zirconium oxide micropowder, 2-5 parts of diamond micropowder and 1 part of titanium boride micropowder; The mixed solution includes 75 parts of deionized water, 4 parts of liquid carbon black, 2 parts of polyvinyl alcohol, 8 parts of phenolic resin and 1 part of n-octanol.

6. The micron-sized spherical boron carbide ceramic according to claim 5, characterized in that: The particle size D50 value of the boron carbide micropowder is in the range of 0.5-2 μm; the particle size D50 value of the silicon carbide micropowder is in the range of 1-2 μm; the particle size D50 value of the zirconium oxide micropowder is in the range of 1-2 μm; the particle size D50 value of the diamond micropowder is in the range of 0.5-1 μm; and the particle size D50 value of the titanium boride is in the range of 1-5 μm.

7. The micron-sized spherical boron carbide ceramic according to claim 6, characterized in that: The solid content of the liquid carbon black is 20%.

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