CN114573867A - Carbon nanotube-boron nitride spherical heat-conducting filler and preparation method and application thereof - Google Patents
Carbon nanotube-boron nitride spherical heat-conducting filler and preparation method and application thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of heat-conducting composite materials, and particularly relates to a carbon nanotube-boron nitride spherical heat-conducting filler as well as a preparation method and application thereof. According to the invention, in the spray drying process, polyvinyl alcohol is used as a binder, and boron nitride and the carbon nano tube are bonded in the slurry atomization and volatilization processes to form the spherical heat-conducting filler, so that not only can the tight contact between the boron nitride and the boron nitride in the sphere and between the boron nitride and the carbon nano tube be ensured, but also the contact sites between the sphere and the sphere of the spherical heat-conducting filler can be increased, the contact tightness of the spherical heat-conducting filler in a geometric space is effectively improved, meanwhile, the contact thermal resistance between the spheres can be reduced, more heat-conducting passages are formed, and the heat-conducting performance of the composite material is improved.
Description
Technical Field
The invention belongs to the technical field of heat-conducting composite materials. More particularly, relates to a carbon nanotube-boron nitride spherical heat-conducting filler, a preparation method and an application thereof.
Background
The electronic products have serious heat generation in use due to the integration and high-performance development of electronic components. The circuit board, the protective housing and the like in the existing electronic product are mostly made of high polymer materials with poor heat conductivity, so that heat generated in use is difficult to diffuse, the internal temperature is rapidly increased, the high-temperature condition is not favorable for normal operation of electronic equipment, and the service life of the equipment can be shortened or potential safety hazards can be caused. Therefore, it is necessary to develop a material having good thermal conductivity to solve the above problems.
Compounding heat-conducting fillers with carbon nanotubes is a common method for preparing materials with excellent heat-conducting property. Boron nitride is a common heat-conducting filler, has the advantages of good insulation, high breakdown strength, high heat conductivity coefficient, stable physical and chemical properties and the like, and is widely researched and used for preparing heat-conducting materials. However, most of the existing methods for preparing the boron nitride-carbon nanotube heat-conducting filler are simple melt blending, the contact sites between boron nitride and carbon nanotubes in the material obtained by the method are limited, and the effect of improving the heat-conducting property is poor. For example, the chinese patent application discloses a method of using one-dimensional carbon nanotubes and two-dimensional boron nitride as a heat conductive filler together to form a composite material with a three-dimensional structure in space to improve the heat conductivity of the material, but the method adopted is a melt blending method, the two are simply cross-compounded in a geometric space, and a large number of gaps exist between heat conductive components, which is not favorable for heat transfer.
Disclosure of Invention
The invention aims to solve the technical problems of the existing boron nitride-carbon nano tube heat-conducting filler that the contact sites between boron nitride and boron nitride, between boron nitride and carbon nano tube are few and the heat transfer capability is poor, and provides a preparation method of a carbon nano tube-boron nitride spherical heat-conducting filler which can prepare the filler that the contact sites between boron nitride and boron nitride, between boron nitride and carbon nano tube are many and the heat transfer capability is good.
The invention aims to provide a carbon nano tube-boron nitride spherical heat-conducting filler.
The invention also aims to provide application of the carbon nanotube-boron nitride spherical heat-conducting filler in preparing high-heat-conducting circuit boards and protective shells.
The above object of the present invention is achieved by the following technical solutions:
a preparation method of a carbon nanotube-boron nitride spherical heat-conducting filler comprises the following steps:
s1, dissolving boron nitride and carbon nano tubes in water to obtain slurry, and adding PVA (polyvinyl alcohol) and uniformly mixing to obtain slurry;
and S2, sequentially carrying out spray drying granulation, presintering and sintering on the slurry obtained in the step S1 to obtain the material.
In the preparation process of the spherical heat-conducting filler, the flexible carbon nano tubes are selected, so that the contact sites among the spherical heat-conducting fillers are effectively increased, and the heat conduction is enhanced; the polyvinyl alcohol has a large amount of hydroxyl groups, can form hydrogen bonds with the hydroxyl groups on the surface of the boron nitride, has certain adhesion, and in the spray drying process, the polyvinyl alcohol is used as a binder to bind the boron nitride with the carbon nano tubes in the slurry atomization and volatilization processes to form the spherical heat-conducting filler, so that the close contact between the boron nitride inside the sphere and the boron nitride and between the boron nitride and the carbon nano tubes can be ensured, the contact sites between the sphere and the sphere of the spherical heat-conducting filler can be increased, the contact compactness of the spherical heat-conducting filler in a geometric space is effectively improved, meanwhile, the contact thermal resistance between the spheres can be reduced, more heat-conducting passages are formed, and the heat-conducting performance of the spherical heat-conducting filler is improved.
Preferably, in step S1, the addition amount of the carbon nanotubes is 0.2 to 1% of the total mass of the slurry.
Preferably, in step S1, the mass ratio of the boron nitride to the carbon nanotubes is (10-30): 1.
Preferably, in step S1, the PVA is added in an amount of 0.5 to 1.5% by mass based on the total mass of the slurry.
Preferably, in step S2, the temperature of the spray drying granulation is 100 to 300 ℃.
More preferably, the temperature of the spray drying granulation is 150-260 ℃.
Preferably, in step S2, the pre-sintering temperature is 300-1000 ℃.
More preferably, the temperature of the pre-sintering is 500-800 ℃.
Preferably, in step S2, the pre-sintering time is 0.5-3 h.
More preferably, the pre-sintering time is 1 h.
Preferably, in step S2, the sintering temperature is 1200-2500 ℃.
More preferably, the sintering temperature is 1500-2000 ℃.
Preferably, in step S2, the sintering time is 0.5-3 h.
More preferably, the sintering time is 2 h.
Preferably, in step S1, the water includes deionized water and ultrapure water.
More preferably, the water is deionized water.
The invention further provides a carbon nano tube-boron nitride spherical heat-conducting filler, which is prepared by the preparation method.
The spherical heat-conducting filler prepared by the invention has good stability, can keep the close combination between the spheres after being compounded with the polymer PVA, and reduces the interface thermal resistance between the fillers to the maximum extent; after the spherical heat-conducting filler is prepared, the original shape can be still kept, so that the heat conductivity coefficient of the composite material is improved.
The invention further protects the application of the carbon nano tube-boron nitride spherical heat-conducting filler in the preparation of heat-conducting circuit boards and protective shells.
Preferably, the heat conducting circuit board and the protective shell are cooled by heat conducting silica gel.
The invention has the following beneficial effects:
according to the invention, in the spray drying process, polyvinyl alcohol is used as a binder, and boron nitride and the carbon nano tube are bonded in the slurry atomization and volatilization processes to form the spherical heat-conducting filler, so that not only can the tight contact between the boron nitride and the boron nitride in the sphere and between the boron nitride and the carbon nano tube be ensured, but also the contact sites between the sphere and the sphere of the spherical heat-conducting filler can be increased, the contact tightness of the spherical heat-conducting filler in a geometric space is effectively improved, meanwhile, the contact thermal resistance between the spheres can be reduced, more heat-conducting passages are formed, and the heat-conducting performance of the composite material is improved.
Drawings
Fig. 1 is a particle size distribution curve diagram of a carbon nanotube-boron nitride spherical heat-conducting filler prepared from carbon nanotubes and boron nitride in different proportions.
FIG. 2 is a scanning electron microscope image of carbon nanotube-boron nitride spherical thermal conductive filler prepared from carbon nanotubes and boron nitride at different proportions, (2a)10: 1; (2b)15: 1; (2c)20: 1; (2d)25: 1; (2e)30: 1.
Fig. 3 is a scanning electron microscope topography of the thermally conductive filler obtained in comparative example 2.
FIG. 4 is a scanning electron microscope topography of the spherical thermal conductive filler obtained in comparative example 3.
FIG. 5 is a scanning electron microscope topography of the spherical thermal conductive filler obtained in comparative example 4.
Fig. 6 is a transmission electron microscope image of the carbon nanotube-boron nitride spherical thermal conductive filler prepared in example 5.
FIG. 7 is a scanning electron microscope image of a thermally conductive silica gel prepared from the carbon nanotube-boron nitride spherical thermally conductive filler obtained in example 5.
Fig. 8 is a graph of thermal conductivity data for the carbon nanotube-boron nitride sphere-type thermal conductive filler obtained in example 5.
Fig. 9 is a graph of viscosity data of the thermal conductive silica gel prepared from the carbon nanotube-boron nitride spherical thermal conductive filler obtained in example 5.
Detailed Description
The invention is further described with reference to the drawings and the following detailed description, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.
Unless otherwise indicated, reagents and materials used in the following examples are commercially available.
Example 1 preparation of carbon nanotube-boron nitride spherical thermal conductive Filler
S1, weighing 5.0g of boron nitride, 0.5g of carbon nano tube and 49.5g of deionized water, uniformly mixing to obtain slurry, adding 0.55g of PVA, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain the slurry. Namely, the total mass of the boron nitride and the carbon nano tubes in the slurry is 10 percent of the total mass of the slurry, and the mass ratio of the boron nitride to the carbon nano tubes is 10: 1.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the carbon nano tube-boron nitride composite filler, pre-sintering the carbon nano tube-boron nitride composite filler in the air at the temperature of 600 ℃ for 1 hour, removing the organic additive, transferring the carbon nano tube-boron nitride composite filler into a vacuum furnace, and sintering the carbon nano tube-boron nitride composite filler at the temperature of 1800 ℃ for 2 hours to obtain the carbon nano tube-boron nitride spherical heat-conducting filler.
Example 2 preparation of carbon nanotube-boron nitride spherical thermal conductive Filler
S1, weighing 5.16g of boron nitride, 0.34g of carbon nano tube and 49.5g of deionized water, adding 0.55g of PVA, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain slurry. Namely, the total mass of the boron nitride and the carbon nano tubes in the slurry is 10 percent of the total mass of the slurry, and the mass ratio of the boron nitride to the carbon nano tubes is 15: 1.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the carbon nano tube-boron nitride composite filler, pre-sintering the carbon nano tube-boron nitride composite filler in the air at the temperature of 600 ℃ for 1 hour, removing the organic additive, transferring the carbon nano tube-boron nitride composite filler into a vacuum furnace, and sintering the carbon nano tube-boron nitride composite filler at the temperature of 1800 ℃ for 2 hours to obtain the carbon nano tube-boron nitride spherical heat-conducting filler.
Example 3 preparation of carbon nanotube-boron nitride spherical thermal conductive Filler
S1, weighing 5.24g of boron nitride, 0.26g of carbon nano tube and 49.5g of deionized water, adding 0.55g of PVA, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain slurry. Namely, the total mass of the boron nitride and the carbon nano tube in the slurry is 10 percent of the total mass of the slurry, and the mass ratio of the boron nitride to the carbon nano tube is 20: 1.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the carbon nano tube-boron nitride composite filler, pre-sintering the carbon nano tube-boron nitride composite filler in the air at the temperature of 600 ℃ for 1 hour, removing the organic additive, transferring the carbon nano tube-boron nitride composite filler into a vacuum furnace, and sintering the carbon nano tube-boron nitride composite filler at the temperature of 1800 ℃ for 2 hours to obtain the carbon nano tube-boron nitride spherical heat-conducting filler.
Example 4 preparation of carbon nanotube-boron nitride spherical thermal conductive Filler
S1, weighing 5.29g of boron nitride, 0.21g of carbon nano tube and 49.5g of deionized water, adding 0.55g of PVA, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain slurry. Namely, the total mass of the boron nitride and the carbon nano tubes in the slurry is 10 percent of the total mass of the slurry, and the mass ratio of the boron nitride to the carbon nano tubes is 25: 1.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the carbon nano tube-boron nitride composite filler, pre-sintering the carbon nano tube-boron nitride composite filler in the air at the temperature of 600 ℃ for 1 hour, removing the organic additive, transferring the carbon nano tube-boron nitride composite filler into a vacuum furnace, and sintering the carbon nano tube-boron nitride composite filler at the temperature of 1800 ℃ for 2 hours to obtain the carbon nano tube-boron nitride spherical heat-conducting filler.
Example 5 preparation of carbon nanotube-boron nitride spherical thermal conductive Filler
S1, weighing 5.32g of boron nitride, 0.18g of carbon nano tube and 49.5g of deionized water, uniformly mixing to obtain slurry, adding 0.55g of PVA, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain the slurry. Namely, the total mass of the boron nitride and the carbon nano tubes in the slurry is 10 percent of the total mass of the slurry, and the mass ratio of the boron nitride to the carbon nano tubes is 30: 1.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the carbon nano tube-boron nitride composite filler, pre-sintering the carbon nano tube-boron nitride composite filler in the air at the temperature of 600 ℃ for 1 hour, removing the organic additive, transferring the carbon nano tube-boron nitride composite filler into a vacuum furnace, and sintering the carbon nano tube-boron nitride composite filler at the temperature of 1800 ℃ for 2 hours to obtain the carbon nano tube-boron nitride spherical heat-conducting filler.
Comparative example 1 preparation of boron nitride spherical Heat-conducting Filler
S1, weighing 5.32g of boron nitride and 49.5g of deionized water, uniformly mixing to obtain slurry, adding 0.55g of PVA, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain slurry.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the boron nitride filler, pre-sintering the boron nitride filler in the air at 600 ℃ for 1 hour, removing the organic additive, transferring the boron nitride filler to a vacuum furnace, and sintering the boron nitride filler at 1800 ℃ for 2 hours to obtain the boron nitride heat-conducting filler.
The difference from example 5 is that: the conditions and reagents for the remaining steps were the same as in example 5 except that no carbon nanotubes were added in step S1.
Comparative example 2 preparation of silicon carbide whisker-boron nitride composite thermal conductive filler
S1, weighing 5.32g of boron nitride, 0.18g of silicon carbide whisker and 49.5g of deionized water, uniformly mixing to obtain slurry, adding 0.55g of PVA, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain the slurry. Namely, the total mass of the boron nitride and the silicon carbide whisker in the slurry is 10 percent of the total mass of the slurry, and the mass ratio of the boron nitride to the silicon carbide whisker is 30: 1.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the silicon carbide whisker-boron nitride composite filler, pre-sintering the silicon carbide whisker-boron nitride composite filler in air at 600 ℃ for 1 hour, removing the organic additive, transferring the silicon carbide whisker-boron nitride composite filler into a vacuum furnace, and sintering the silicon carbide whisker-boron nitride composite filler at the temperature of 1800 ℃ for 2 hours to obtain the silicon carbide whisker-boron nitride heat-conducting filler.
The difference from example 5 is that: the carbon nanotubes in step S1 were replaced with silicon carbide whiskers, and the conditions and reagents of the remaining steps were the same as those of example 5.
Comparative example 3 preparation of carbon nanotube-boron nitride spherical Heat-conducting Filler
S1, weighing 5.32g of boron nitride, 0.18g of carbon nano tube and 49.5g of deionized water, uniformly mixing to obtain slurry, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain the slurry. Namely, the total mass of the boron nitride and the carbon nano tubes in the slurry is 10 percent of the total mass of the slurry, and the mass ratio of the boron nitride to the carbon nano tubes is 30: 1.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the carbon nano tube-boron nitride composite filler, pre-sintering the carbon nano tube-boron nitride composite filler in the air at the temperature of 600 ℃ for 1 hour, removing the organic additive, transferring the carbon nano tube-boron nitride composite filler into a vacuum furnace, and sintering the carbon nano tube-boron nitride composite filler at the temperature of 1800 ℃ for 2 hours to obtain the carbon nano tube-boron nitride spherical heat-conducting filler.
The difference from example 5 is that: in step S1, PVA was not added, and the conditions and reagents in the remaining steps were the same as in example 5.
Comparative example 4 preparation of carbon nanotube-boron nitride spherical Heat-conducting Filler
S1, weighing 5.32g of boron nitride, 0.18g of carbon nano tube and 49.5g of deionized water, uniformly mixing to obtain slurry, adding 0.55g of dopamine, adjusting the pH value of the slurry to 8.5 through tris buffer solution, and stirring in an ultrasonic stirrer (the rotating speed is 500 revolutions per minute) for 2 hours to obtain slurry. Namely, the total mass of the boron nitride and the carbon nano tubes in the slurry is 10 percent of the total mass of the slurry, and the mass ratio of the boron nitride to the carbon nano tubes is 30: 1.
S2, immediately taking out the slurry obtained in the step S1, performing spray drying granulation (the inlet temperature of a spray dryer is set to be 180 ℃) to obtain the carbon nano tube-boron nitride composite filler, pre-sintering the carbon nano tube-boron nitride composite filler in the air at the temperature of 600 ℃ for 1 hour, removing the organic additive, transferring the carbon nano tube-boron nitride composite filler into a vacuum furnace, and sintering the carbon nano tube-boron nitride composite filler at the temperature of 1800 ℃ for 2 hours to obtain the carbon nano tube-boron nitride spherical heat-conducting filler.
The difference from example 5 is that: PVA in step S1 was replaced with 0.55g dopamine, and the pH of the slurry was adjusted to 8.5 by tris buffer solution, and the conditions and reagents for the remaining steps were the same as in example 5.
The dopamine has viscosity after being treated by tris buffer solution and can be used as a binder.
Experimental example 1 particle size distribution test of carbon nanotube-boron nitride spherical thermal conductive filler
1. The test method comprises the following steps: the carbon nanotube-boron nitride spherical heat conductive filler obtained in example 1 to 5 was placed on a sample stage of a laser particle sizer (Mastersize,3000E) and tested.
2. And (3) testing results: as can be seen from FIG. 1, the particle size distribution range of the carbon nanotube-boron nitride spherical heat conductive filler is 1.5-200 μm, most of the carbon nanotube-boron nitride spherical heat conductive filler is concentrated between 5.0-20 μm, and the particle size reaches the peak value near 10 μm.
Experimental example 2 morphology test of carbon nanotube-boron nitride spherical heat-conductive filler
And (3) testing a scanning electron microscope:
1. the test method comprises the following steps: the carbon nanotube-boron nitride spherical heat-conducting filler obtained in examples 1 to 5, the silicon carbide whisker-boron nitride heat-conducting filler obtained in comparative example 2, and the carbon nanotube-boron nitride spherical heat-conducting filler obtained in comparative example 3 were uniformly adhered to a conductive adhesive, placed in an ion sputtering apparatus for gold spraying, and then placed on a sample stage of a scanning electron microscope (Hitachi, S-4800) for testing.
2. And (3) testing results: as can be seen from fig. 2, fig. 2a to 2e are scanning electron micrographs of the carbon nanotube, boron nitride (10: 1), 15:1, 20:1, 25:1, and 30:1 prepared carbon nanotube-boron nitride spherical thermal conductive filler in sequence. At the ratio of 30:1, the product had a better spherical structure and the particle size distribution was uniform. The close connection between the boron nitride sheets can be seen by magnifying observation. With the increase of the proportion of the carbon nano tube, the spherical structure is gradually deteriorated, and the phenomena of irregular shape and large size difference appear.
As can be seen from fig. 3, the silicon carbide whisker-boron nitride thermal conductive filler prepared in comparative example 2 has poor morphology and obvious gaps because the silicon carbide whisker has a large size and hinders the boron nitride from agglomerating during the spray drying process, and therefore, the silicon carbide whisker does not meet the requirement for preparing the spherical thermal conductive filler.
As can be seen from fig. 4, the carbon nanotube-boron nitride spherical heat conductive filler prepared in comparative example 3 cannot obtain an ideal spherical morphology. The reason is that polyvinyl alcohol is not added, the spray drying process only plays a role in drying and removing water, hydroxyl on the surface of boron nitride cannot form hydrogen bonds, and the adhesion of the boron nitride is poor.
As can be seen from fig. 5, in the carbon nanotube-boron nitride spherical thermal conductive filler prepared in comparative example 4, polydopamine cannot act on all boron nitride and carbon nanotubes in the rapid spray drying process, and the bonding effect is not good.
And (3) transmission electron microscope testing:
1. the test method comprises the following steps: the carbon nanotube-boron nitride spherical thermal conductive filler obtained in example 5 was placed on a sample stage of a transmission electron microscope (JEOL, JEM-2100F) for testing.
2. And (3) testing results: as can be seen from fig. 6, the left drawing is an overall drawing of the carbon nanotube-boron nitride spherical heat-conducting filler, and the one-dimensional carbon nanotubes penetrate through the boron nitride and are uniformly dispersed among the boron nitride, and are uniformly compounded with the boron nitride sheet; the right figure is a partial enlarged view of the edge of the carbon nanotube-boron nitride spherical heat-conducting filler, and it can be seen that the carbon nanotube with the protruded edge can increase effective contact sites between boron nitride and boron nitride in the spherical body of the spherical heat-conducting filler, between boron nitride and the carbon nanotube and between the spherical body and the spherical body, thereby being beneficial to the heat transportation of the spherical heat-conducting filler and enhancing the heat-conducting property of the spherical heat-conducting filler.
Experimental example 3 Performance test of Heat-conductive silica gel prepared from carbon nanotube-boron nitride spherical Heat-conductive Filler
1. The preparation method of the heat-conducting silica gel comprises the following steps:
carbon nanotube-containing heat conductive silica gel:
mixing dimethyl siloxane and a curing agent according to a mass ratio of 10:1 to obtain pre-cured silicone oil, then adding 5%, 10%, 15% and 20% of the carbon nanotube-boron nitride spherical heat-conducting filler obtained in the example 5 into the pre-cured silicone oil, stirring for 6min in a vacuum stirrer at a rotating speed of 2000rpm at room temperature, casting the well-dispersed carbon nanotube-boron nitride spherical heat-conducting filler/pre-cured silicone oil into a polytetrafluoroethylene mold, and curing for 2 hours at 80 ℃ to obtain the CNTs-SBN heat-conducting silica gel.
Thermally conductive silica gel without carbon nanotubes:
mixing dimethyl siloxane and a curing agent according to the mass ratio of 10:1 to obtain pre-cured silicone oil, then adding the boron nitride heat-conducting filler with the volume fractions of 5%, 10%, 15% and 20% obtained in the comparative example 1 into the pre-cured silicone oil, stirring for 6min in a vacuum stirrer at the rotating speed of 2000rpm at room temperature, casting the well-dispersed carbon nano tube-boron nitride heat-conducting filler/pre-cured silicone oil into a polytetrafluoroethylene mold, and curing for 2 hours at the temperature of 80 ℃ to obtain the SBN heat-conducting silica gel.
2. The test method comprises the following steps:
and (3) morphology testing:
the heat-conducting silica gel is uniformly adhered on the conductive adhesive, placed in an ion sputtering instrument for gold spraying, and then placed on a sample platform of a scanning electron microscope (Hitachi, S-4800) for testing.
And (3) testing the heat conductivity coefficient:
the transient method thermal conductivity tester (xi' an xiaxi, TC3000) used for the test. And taking two pieces of completely cured heat-conducting silica gel, and clamping the test probe up and down to test.
Viscosity test of the heat-conducting silica gel:
the spherical heat conductive filler prepared in example 5 and the original flaky boron nitride-filled silicone oil were measured by a rotational viscometer at volume fractions of 5%, 15%, and 20%, respectively.
3. And (3) testing results:
as can be seen from fig. 7, the heat conductive silica gel prepared from the carbon nanotube-boron nitride spherical heat conductive filler in embodiment 5 of the present invention can maintain the close combination between the spheres of the spherical heat conductive filler, and reduce the interface thermal resistance between the spherical heat conductive fillers to the maximum extent, so as to improve the heat conductivity coefficient of the heat conductive silica gel.
As can be seen from fig. 8, under the same addition amount, the thermal conductivity of the thermal conductive silica gel containing carbon nanotubes in example 5 is higher than that of the thermal conductive silica gel containing no carbon nanotubes in comparative example 1, which indicates that the presence of carbon nanotubes can provide more contact sites for the spherical thermal conductive filler, so that boron nitride in the spherical thermal conductive filler is more tightly bonded with the carbon nanotubes, thereby reducing the thermal contact resistance between spheres.
As can be seen from fig. 9, under the three filling amounts of 5%, 15% and 20%, the degree of viscosity increase of the CNTs-SBN thermal conductive silica gel prepared by the spherical thermal conductive filler in example 5 to the system is lower than that of the SBN thermal conductive silica gel prepared by the sheet-shaped thermal conductive filler, that is, under the same addition amount, the thermal conductive silica gel prepared by the spherical filler has better fluidity and operability.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. A preparation method of a carbon nanotube-boron nitride spherical heat-conducting filler is characterized by comprising the following steps:
s1, dissolving boron nitride and carbon nanotubes in water to obtain slurry, and adding PVA (polyvinyl alcohol) and uniformly mixing to obtain slurry;
and S2, sequentially carrying out spray drying granulation, presintering and sintering on the slurry obtained in the step S1 to obtain the material.
2. The method according to claim 1, wherein in step S1, the carbon nanotubes are added in an amount of 0.2 to 1% by mass based on the total mass of the slurry.
3. The method according to claim 1, wherein in step S1, the mass ratio of boron nitride to carbon nanotubes is (10-30): 1.
4. The method according to claim 1, wherein in step S1, the PVA is added in an amount of 0.5 to 1.5% by mass based on the total mass of the slurry.
5. The method according to claim 1, wherein the temperature of the spray-dried granules in step S2 is 100 to 300 ℃.
6. The method according to claim 1, wherein the pre-sintering temperature is 300 to 1000 ℃ in step S2.
7. The method according to claim 1, wherein in step S2, the sintering temperature is 1200-2500 ℃.
8. The method as claimed in claim 1, wherein in step S1, the water comprises deionized water and ultrapure water.
9. A carbon nanotube-boron nitride spherical heat-conducting filler, which is characterized by being prepared by the preparation method of any one of claims 1 to 8.
10. The use of the carbon nanotube-boron nitride sphere-type thermal conductive filler of claim 9 in the preparation of a thermally conductive circuit board and a protective case.
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| CN114989608A (en) * | 2022-07-01 | 2022-09-02 | 宁夏清研高分子新材料有限公司 | Heat-conducting polysulfone composite material and preparation method thereof |
| CN114989608B (en) * | 2022-07-01 | 2024-01-30 | 宁夏清研高分子新材料有限公司 | Heat-conducting polysulfone composite material and preparation method thereof |
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