CN113336203A - Small-particle-size boron nitride aggregate particles and preparation method thereof - Google Patents
Small-particle-size boron nitride aggregate particles and preparation method thereof Download PDFInfo
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Abstract
The invention discloses small-particle-size boron nitride aggregate particles, which are spherical-like, have particle sizes of 30-50 microns, and are formed by assembling thin slices with diameters of about 3-5 microns in a microstructure. A preparation method of small-particle-size boron nitride aggregate particles comprises the following steps: 1) preparing agglomerated particles formed by nano to submicron boron nitride point particles to obtain boron nitride agglomerates; 2) and filling the boron nitride aggregate into a sintering furnace, and treating at high temperature to obtain small-particle-size boron nitride aggregate particles with the particle size of about 30-50 microns. The small-particle-size boron nitride aggregate provided by the invention has high particle yield and good shape, meanwhile, briquetting equipment, centrifugal granulation equipment or complex spray drying equipment can be omitted in the process route, and the equipment cost can be obviously reduced.
Description
Technical Field
The invention relates to the technical field of material preparation, in particular to small-particle-size boron nitride aggregate particles and a preparation method thereof.
Background
In recent years, as the power density of electronic products is increased, the amount of heat generated per unit volume is rapidly increased, and the heat dissipation performance has become an important factor affecting the stability and design life of electronic products. Electronic products generally use heat dissipation devices such as an additional heat dissipation substrate and a heat sink to transfer internal heat, and interface heat transfer exists between a heating device and the heat dissipation device in the process. The existing method is to use a high-performance thermal interface material, use resin as a base material, provide the largest contact area with a heating device and a heat dissipation device by utilizing the fluidity of the resin, and add high-thermal-conductivity filler into the resin to prepare a thermal-conductivity coating, a prepreg and the like, so as to rapidly guide the heat of an electronic device into the heat dissipation device.
Boron nitride is an important heat-conducting filler and has the advantages of good heat conductivity, low density, insulation and the like, but the boron nitride is usually in a sheet shape, the heat conductivity coefficient has obvious directionality, and the sheet-shaped object can be oriented in the process of mixing into resin, so that the obtained coating and prepreg have good heat conductivity in the parallel direction, but the heat conductivity in the vertical direction is not satisfactory. To solve this problem, the boron nitride flakes are generally processed to produce agglomerated boron nitride particles having different orientations of the boron nitride flakes. For example, in the patent CN201710822820 of shanghai encyclopedia technology and the patent CN200710004476 of saint gobibo ceramics, boron nitride and additives are prepared into slurry, spray granulation is carried out, and the boron nitride particles with the particle size of 100-200 micrometers are obtained after sintering and other steps. CN201680035455 is a method for producing boron nitride particles, which comprises cold pressing boron nitride powder into a block, crushing the block, and sieving to obtain boron nitride particles with a median particle size of 80-200 μm. In patent CN201910437359, a centrifugal granulation technology is used, boron nitride and a binder are granulated in a centrifugal granulator, and spherical-like boron nitride particles with adjustable particle size of 100-400 microns are obtained through high-temperature sintering.
With the increasing requirements of the electronic industry, the thickness of the thermal interface material is lower and lower, and the requirements on the size of boron nitride particles are smaller and smaller. For the boron nitride industry, the lower limit of the particle size of agglomerated particles which can be achieved by the current method is about 80 microns, when the particle size is lower than the lower limit, the problems of reduced agglomeration rate and difficult particle forming can occur in a spray granulation method and a centrifugal granulation method, and the problems of increased powder, reduced yield and the like can occur in a process of firstly briquetting and then crushing.
Disclosure of Invention
In view of the above, the present invention discloses a small particle size boron nitride aggregate particle and a preparation method thereof, so as to solve the problems of low yield and poor shape when preparing boron nitride aggregates with the particle size range in the prior art;
in one aspect, the invention provides small-particle-size boron nitride aggregate particles, wherein the boron nitride aggregate particles are spherical-like, the particle size is 30-50 microns, and the microstructure is formed by assembling thin slices with the diameter of about 3-5 microns.
On the other hand, the invention provides a preparation method of the boron nitride aggregate particles with small particle size, which comprises the following steps:
1) preparing agglomerated particles formed by nano to submicron boron nitride point particles to obtain boron nitride agglomerates;
2) and filling the boron nitride aggregate into a sintering furnace, and treating at high temperature to obtain small-particle-size boron nitride aggregate particles with the particle size of about 30-50 microns.
Preferably, the step 1) of preparing the boron nitride agglomerates specifically comprises the following steps:
a. mixing materials: mixing a boron source, a nitrogen source and a fluxing agent; wherein the boron source, the nitrogen source and the fluxing agent respectively pass through a 40-mesh sieve;
b. pre-dewatering: b, feeding the mixed raw materials in the step a into an oven, and drying the moisture in the raw materials to obtain a hardened material;
c. heating and reacting: filling the pre-dehydrated material into a sintering furnace, and heating and reacting to obtain a sintered product;
d. and (3) post-treatment: and (3) washing, filtering and drying the sintered product in sequence to obtain the boron nitride aggregate consisting of nano to submicron boron nitride particles.
More preferably, the boron source is a compound mainly containing boron and oxygen; the nitrogen source is a solid compound mainly containing carbon and nitrogen elements; the fluxing agent is an alkali metal halide or an alkali metal boride.
Preferably, in the step a, the mass ratio of the boron source, the nitrogen source and the fluxing agent is 2.0-3.5: 1: 0.05 to 0.5.
Further preferably, the pre-dehydration temperature of step b is from 125 ℃ to 300 ℃ or not more than the melting or decomposition temperature of the nitrogen source.
Further preferably, the temperature rise speed of the sintering furnace in the step c is 250-.
More preferably, in the step d post-treatment step, the frit is firstly crushed into several millimeters of frit, the crushed frit is put into water which is heated to 90 ℃ in advance, and the water is washed under the stirring of a stirring paddle, wherein the washing water amount is 10-20 times of the mass of the put frit, and the obtained filter cake is dried at the temperature of 100-.
Preferably, the temperature of the high-temperature treatment in the step 2) is 1700-2100 ℃, the sintering atmosphere is a neutral gas atmosphere, and the heat preservation time is 2-12 h.
The small-particle-size boron nitride aggregate particles provided by the invention are high in yield and good in shape, meanwhile, briquetting equipment, centrifugal granulation equipment or complex spray drying equipment can be omitted in the process route, and the equipment cost can be obviously reduced. The process route provided by the invention omits a granulation step, so the preparation time is shorter than that of a briquetting-crushing flow, a centrifugal granulation method and a spray granulation method.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a flow chart of a method for preparing boron nitride agglomerate particles with small particle size according to an embodiment of the disclosure;
FIG. 2 is a scanning electron microscope image of boron nitride agglomerates composed of nano-to submicron boron nitride particles according to an embodiment of the disclosure;
FIG. 3 is a scanning electron microscope image of a boron nitride agglomerate product having a particle size of about 30-50 microns provided by a disclosed embodiment of the invention;
fig. 4 is a scanning electron micrograph of a single boron nitride agglomerate particle, and at a local magnification, provided by a disclosed embodiment of the invention.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of systems consistent with certain aspects of the invention, as detailed in the appended claims.
In the prior art, the method of constructing the boron nitride large agglomerated particles by using flaky boron nitride primary particles is difficult to prepare the boron nitride agglomerated particles with small particle sizes; in the process method adopted by the embodiment, firstly, the flaky boron nitride primary particles are not selected to be prepared, but the agglomerate particles formed by nanometer to submicron boron nitride point-shaped particles with poor crystallinity are obtained firstly, and then the agglomerate particles formed by the flaky boron nitride primary particles with high crystallinity are obtained through secondary sintering, wherein the agglomerate particles are spherical-like, the particle size is about 30-50 micrometers, and the microstructure is formed by assembling sheets with the diameter of about 3-5 micrometers.
In this embodiment, a method for preparing boron nitride agglomerate particles having a particle size of 30 to 50 micrometers, as shown in fig. 1, includes the following steps:
1) preparing boron nitride agglomerates composed of nano to submicron boron nitride particles.
2) High-temperature treatment of the boron nitride agglomerates: and (3) filling the aggregate into a sintering furnace again, and treating at high temperature to obtain the boron nitride aggregate product with the particle size of about 30-50 microns.
Preferably, step 1 specifically comprises:
a. mixing materials: mixing a boron source, a nitrogen source and a fluxing agent (all passing through a 40-mesh sieve);
the boron source used in this embodiment is a compound based on boron and oxygen, including but not limited to boron oxide, boric acid, ammonium borate, sodium tetraborate, and the like. The nitrogen source used in the present invention is a solid compound mainly containing carbon and nitrogen elements, including but not limited to melamine, urea, ammonium carbonate, etc. The fluxing agent of the present invention is an alkali metal halide or an alkali metal boride, including but not limited to sodium fluoride, potassium chloride, sodium metaborate, and the like.
The mass ratio range of the boron source, the nitrogen source and the fluxing agent in the embodiment is limited to 2.0-3.5: 1: 0.05 to 0.5. Under the condition that the quality of a nitrogen source is fixed, the boron oxide in the system is insufficient due to insufficient boron source, and further, the boron nitride or excessive impurities mixed in the boron nitride are difficult to form; too much boron source will form too small boron nitride primary particles that will more readily grow into larger platelet-shaped boron nitrides rather than agglomerates in subsequent high temperature processing. The viscosity of the boron oxide liquid phase is too high due to no addition of a fluxing agent, the mass transfer effect in a system is poor, and the aggregate is larger; the addition of too much flux leads to difficulty in agglomeration of the boron nitride primary particles.
The mixing apparatus is not particularly limited in this embodiment.
b. Pre-dewatering: feeding the mixed raw materials into an oven, and drying out moisture in the raw materials to obtain a hardened material;
since the nitrogen source is relatively easily melted or decomposed with respect to the boron source, the pre-dehydration temperature range of the present embodiment is from 125 ℃ or more to 300 ℃ or not more than the melting or decomposition temperature of the nitrogen source. For example, the pre-dehydration temperature range is 125-300 ℃ when melamine is used, and the pre-dehydration temperature range is 125-150 ℃ when urea is used.
c. Heating and reacting: filling the pre-dehydrated material into a sintering furnace, and heating and reacting to obtain a sintered product;
the requirements of the sintering furnace required for the heating reaction in the present embodiment are: the sintering furnace has the following temperature rise capacity: at least 1300 ℃, and is capable of being atmospherically protected.
The temperature rise rate of the heating reaction in the embodiment is preferably 250-. The heating speed in the reaction stage should reach above 500 ℃ as soon as possible, at this temperature, the ammonia and boron oxide released by the decomposition of the nitrogen source are most comprehensive, the too slow heating speed will cause the reduction of the utilization rate of the nitrogen source, and the too fast heating speed has higher requirements on equipment. The constant temperature during sintering is preferably 750-1300 ℃, more preferably 900-1250 ℃, and most preferably 950-1100 ℃. The constant temperature time is preferably 2-8h, more preferably 3-6h, and most preferably 4-5 h. The requirement of the invention on the protective atmosphere of the reaction system is to use nitrogen for protection.
d. And (3) post-treatment: and (3) washing, filtering and drying the sintered product in sequence to obtain the boron nitride aggregate consisting of nano to submicron boron nitride particles.
The embodiment has no requirement on the cooling speed of the reaction system, and the mixed product, the by-product, the fluxing agent and the glass-state boron oxide frit are obtained after cooling; the post-processing step is then entered.
The post-treatment step first crushes the frit into small pieces of several millimeters, and there is no particular limitation on the crushing apparatus. And putting the crushed clinker into water heated to 90 ℃ in advance, and washing with water under stirring of a stirring paddle, wherein the washing water amount is 10-20 times of the mass of the clinker, and the washing efficiency and the heating energy consumption are both considered. The solid-liquid separation is then carried out, and the present invention is not particularly limited to the solid-liquid separation apparatus. Drying the filter cake at 100-200 ℃ to obtain the boron nitride aggregate formed by the agglomeration of submicron-grade boron nitride primary particles. The present invention is not particularly limited to the drying apparatus.
In the high-temperature treatment process of the present embodiment, submicron boron nitride constituting the boron nitride agglomerates undergoes crystal form transformation from granular to plate-like, but the particle size of the agglomerates is substantially unchanged, and boron nitride agglomerate particles composed of primary particles of plate-like boron nitride having high crystallinity are obtained. The temperature requirement of the invention for high-temperature treatment is preferably 1700-2100 ℃, more preferably 1800-2000 ℃, and most preferably 1900-1950 ℃. The sintering atmosphere is neutral gas atmosphere such as nitrogen and argon, and the heat preservation time is preferably 2-12h, more preferably 3-8 h, and most preferably 5-6 h. And cooling the product along with the furnace after the high-temperature treatment is finished to obtain the product. The product may contain occasional larger aggregates which are removed by a 40 mesh screen, i.e. boron nitride aggregate particles consisting of high crystallinity flaky boron nitride primary particles, with particle size of about 30-50 microns.
The mechanism applied by the method is as follows: in this embodiment, the boron source and the nitrogen source undergo a complex reaction at a temperature below about 800 ℃ to produce a boron-carbon-nitrogen-oxygen compound, and excess boron and oxygen combine to form boron oxide; further heating, liquefying boron oxide, forming a liquid phase under the action of a fluxing agent, transferring carbon elements and oxygen elements of the boron-carbon-nitrogen-oxygen compound in the liquid phase to combine into a gas to be separated from a reaction system, and combining the boron elements and the nitrogen elements to generate boron nitride primary particles of dozens of to hundreds of nanometers. By adjusting the formula and reaction parameters, the viscosity of the liquid phase, the growth rate of the primary particles and the agglomeration degree of the primary particles can be controlled, and boron nitride agglomerates composed of nano-to submicron-sized boron nitride primary particles are obtained, as shown in figure 2. Since the degree of crystallinity of the agglomerate is not good, the agglomerate needs to be further subjected to a high-temperature treatment to promote recrystallization of the primary particles. Since the flux causes excessive crystal growth during high temperature treatment, it is necessary to wash off excess boron oxide and flux by water before sintering. And in the water washing step, acid washing is not used, so that trace boron oxide can be reserved, and the strength of the aggregate after high-temperature treatment is improved. After high-temperature treatment, a boron nitride aggregate product which is composed of flaky boron nitride primary particles with high crystallinity and has the particle size of about 30-50 microns can be obtained, and the product is shown in figure 3. The present embodiment produces boron nitride agglomerate particles composed of flaky boron nitride primary particles having high crystallinity.
The invention will now be further illustrated with reference to specific examples, which are not intended to limit the scope of the invention.
Example 1
100kg of boric acid, 50kg of melamine and 7kg of sodium fluoride, which had been previously agglomerated by a 40-mesh sieve, were mixed in a double cone mixer for 1 hour. The mixed raw materials are sent into an oven and are kept for 12 hours at 220 ℃ for pre-dehydration, and a hardened material is obtained. Crushing the materials by a jaw crusher with a 5mm screen, loading into a cast iron trough, sending into a sintering furnace, heating to 1100 ℃ at a speed of 400 ℃/h under the protection of nitrogen, and preserving heat for 8 h. Naturally cooling to obtain the fusion cake.
Sending the fusion cake into a jaw crusher, crushing the fusion cake into small blocks, sieving the small blocks by a 2mm sieve, putting the small blocks into a water washing kettle, adding hot water with the temperature of 800 liters and the temperature of 90 ℃, and stirring the mixture for 1 hour. And filtering the mixture by a plate frame to obtain a wet filter cake, and drying the wet filter cake in an oven at 120 ℃ to obtain the agglomerated boron nitride aggregate.
Crushing the agglomerated aggregate into powder by a double-roller crusher, filling the powder into a graphite crucible, heating to 1950 ℃ at a heating rate of 400 ℃/h, and keeping the temperature for 2 hours. And naturally cooling to obtain loose white powder, namely the boron nitride aggregate product with the particle size of about 30-50 microns.
Example 2
150kg of boric acid, 50kg of melamine and 12kg of sodium fluoride, which had been previously agglomerated using a 40-mesh sieve, were mixed in a double cone mixer for 1 hour. The mixed raw materials are sent into an oven and are kept for 12 hours at 220 ℃ for pre-dehydration, and a hardened material is obtained. Crushing the materials by a jaw crusher with a 5mm screen, loading into a cast iron trough, sending into a sintering furnace, heating to 1200 ℃ at a speed of 400 ℃/h under the protection of nitrogen, and preserving heat for 8 h. Naturally cooling to obtain the fusion cake.
Sending the fusion cake into a jaw crusher, crushing the fusion cake into small blocks, sieving the small blocks by a 2mm sieve, putting the small blocks into a washing kettle, adding hot water with the temperature of 900 ℃ and the temperature of 90 ℃, and stirring the mixture for 1 hour. And filtering the mixture by a plate frame to obtain a wet filter cake, and drying the wet filter cake in an oven at 120 ℃ to obtain the agglomerated boron nitride aggregate.
Crushing the agglomerated aggregate into powder by using a double-roller crusher, filling the powder into a graphite crucible, heating to 1900 ℃ at the heating rate of 600 ℃/h, and keeping the temperature for 2 hours. And naturally cooling to obtain loose white powder, namely the boron nitride aggregate product with the particle size of about 30-50 microns.
Example 3
100kg of boric acid, 50kg of melamine, 50kg of sodium tetraborate and 15kg of sodium carbonate which are previously subjected to lump removal by using a 40-mesh sieve are mixed in a double-cone mixer for 1 hour. The mixed raw materials are sent into an oven and are kept for 12 hours at 220 ℃ for pre-dehydration, and a hardened material is obtained. Crushing the materials by a jaw crusher with a 5mm screen, loading into a cast iron trough, sending into a sintering furnace, heating to 1300 ℃ at a speed of 400 ℃/h under the protection of nitrogen, and preserving heat for 8 h. Naturally cooling to obtain the fusion cake.
Sending the fusion cake into a jaw crusher, crushing the fusion cake into small blocks, sieving the small blocks by a 2mm sieve, putting the small blocks into a water washing kettle, adding hot water with the temperature of 800 liters and the temperature of 90 ℃, and stirring the mixture for 1 hour. And filtering the mixture by a plate frame to obtain a wet filter cake, and drying the wet filter cake in an oven at 120 ℃ to obtain the agglomerated boron nitride aggregate.
Crushing the agglomerated aggregate into powder by a double-roller crusher, filling the powder into a graphite crucible, heating to 1950 ℃ at a heating rate of 400 ℃/h, and keeping the temperature for 6 hours. And naturally cooling to obtain loose white powder, namely the boron nitride aggregate product with the particle size of about 30-50 microns.
Example 4
175kg of sodium tetraborate, 50kg of melamine and 20kg of sodium metaborate which are previously sieved out by using a 40-mesh sieve are mixed in a double-cone mixer for 1 hour. The mixed raw materials are sent into an oven and are kept for 12 hours at 220 ℃ for pre-dehydration, and a hardened material is obtained. Crushing the materials by a jaw crusher with a 5mm screen, loading into a cast iron trough, sending into a sintering furnace, heating to 1000 ℃ at the speed of 300 ℃/h under the protection of nitrogen, and preserving heat for 8 h. Naturally cooling to obtain the fusion cake.
Sending the fusion cake into a jaw crusher, crushing the fusion cake into small blocks, sieving the small blocks by a 2mm sieve, putting the small blocks into a water washing kettle, adding hot water with the temperature of 800 liters and the temperature of 90 ℃, and stirring the mixture for 1 hour. And filtering the mixture by a plate frame to obtain a wet filter cake, and drying the wet filter cake in an oven at 120 ℃ to obtain the agglomerated boron nitride aggregate.
Crushing the agglomerated aggregate into powder by using a double-roller crusher, filling the powder into a graphite crucible, heating to 1850 ℃ at a heating rate of 600 ℃/h, and preserving the heat for 2 hours. And naturally cooling to obtain loose white powder, namely the boron nitride aggregate product with the particle size of about 30-50 microns.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
Claims (9)
1. The boron nitride aggregate particles with small particle sizes are characterized in that the boron nitride aggregate particles are spherical-like, the particle sizes are 30-50 micrometers, and microstructures are formed by assembling thin slices with the diameters of about 3-5 micrometers.
2. The preparation method of the small-particle-size boron nitride aggregate particles is characterized by comprising the following steps of:
1) preparing agglomerated particles formed by nano to submicron boron nitride point particles to obtain boron nitride agglomerates;
2) and filling the boron nitride aggregate into a sintering furnace, and treating at high temperature to obtain small-particle-size boron nitride aggregate particles with the particle size of about 30-50 microns.
3. The method for preparing boron nitride agglomerate particles with small particle size according to claim 2, wherein the step 1) of preparing boron nitride agglomerates specifically comprises the following steps:
a. mixing materials: mixing a boron source, a nitrogen source and a fluxing agent; wherein the boron source, the nitrogen source and the fluxing agent respectively pass through a 40-mesh sieve;
b. pre-dewatering: b, feeding the mixed raw materials in the step a into an oven, and drying the moisture in the raw materials to obtain a hardened material;
c. heating and reacting: filling the pre-dehydrated material into a sintering furnace, and heating and reacting to obtain a sintered product;
d. and (3) post-treatment: and (3) washing, filtering and drying the sintered product in sequence to obtain the boron nitride aggregate consisting of nano to submicron boron nitride particles.
4. The method for preparing boron nitride agglomerate particles with small particle size according to claim 3, wherein the boron source is a compound mainly containing boron and oxygen; the nitrogen source is a solid compound mainly containing carbon and nitrogen elements; the fluxing agent is an alkali metal halide or an alkali metal boride.
5. The method for preparing small-particle-size boron nitride agglomerate particles according to claim 3, wherein in the step a, the mass ratio of the boron source, the nitrogen source and the fluxing agent is in the range of 2.0-3.5: 1: 0.05 to 0.5.
6. The method for preparing boron nitride agglomerate particles with small particle size according to claim 3, wherein the pre-dehydration temperature in step b is 125-300 ℃ or not more than the melting or decomposition temperature of nitrogen source.
7. The method for preparing boron nitride agglomerate particles with small particle size as claimed in claim 3, wherein the temperature rise speed of the sintering furnace in the step c is 250-600 ℃/h, the constant temperature during sintering is 750-1300 ℃, the constant temperature time is 2-8h, and the protective atmosphere for the reaction system is nitrogen.
8. The method of claim 3, wherein the boron nitride agglomerate particle with small particle size is prepared by the following steps,
in the post-treatment step of the step d, firstly, the frit is crushed into the frit with the size of several millimeters, the crushed frit is put into water which is preheated to 90 ℃, the water washing is carried out under the stirring of a stirring paddle, the water washing amount is 10-20 times of the mass of the put frit, and the obtained filter cake is dried at the temperature of 100 ℃ and 200 ℃.
9. The method for preparing boron nitride agglomerate particles with small particle size as claimed in claim 2, wherein the temperature of the high temperature treatment in step 2) is 1700-2100 ℃, the sintering atmosphere is neutral gas atmosphere, and the holding time is 2-12 h.
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| US20060127422A1 (en) * | 1999-08-31 | 2006-06-15 | General Electric Company | Boron nitride particles of spherical geometry and process for making thereof |
| CN107253704A (en) * | 2010-11-10 | 2017-10-17 | 3M创新有限公司 | Boron nitride aggregate, its production method and application thereof |
| US20160340191A1 (en) * | 2014-02-05 | 2016-11-24 | Mitsubishi Chemical Corporation | Agglomerated boron nitride particles, production method for agglomerated boron nitride particles, resin composition including agglomerated boron nitride particles, moulded body, and sheet |
| CN107848801A (en) * | 2015-09-03 | 2018-03-27 | 昭和电工株式会社 | Hexagonal boron powder, its manufacture method, resin combination and resin sheet |
| JP2017165609A (en) * | 2016-03-15 | 2017-09-21 | デンカ株式会社 | Primary particle aggregate of hexagonal boron nitride, resin composition and application of the same |
| CN110041080A (en) * | 2019-05-24 | 2019-07-23 | 丹东市化工研究所有限责任公司 | A method of preparing near-spherical hexagonal boron nitride agglomerated particle |
| CN111777047A (en) * | 2020-07-13 | 2020-10-16 | 丹东市化工研究所有限责任公司 | Preparation method of nano-submicron sphere-like boron nitride |
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