CN105293499B - A kind of preparation method of B, N codope nanometer silicon carbide absorbing material - Google Patents
A kind of preparation method of B, N codope nanometer silicon carbide absorbing material Download PDFInfo
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Abstract
A kind of preparation method of B, N codope nanometer silicon carbide absorbing material disclosed by the invention, be specially：1) silica flour weighed, carbon powder, amorphous boron powder, silicon nitride powder and polytetrafluoroethylene powder ball milling mixing are prepared into mixed powder A；2) mixed powder A is crossed into 200 mesh sieves and obtains the mixed powder B that average grain diameter is less than 74 μm；3) mixed powder B is placed in vacuum atmosphere hot pressing sinter furnace, N is filled with after first carrying out vacuumize process2Gas, reaction obtains the 3C SiC principal crystalline phase nano-powders of B, N codope；4) the 3C SiC principal crystalline phase nano-powders of B, N codope are positioned in chamber type electric resistance furnace, the high-purity 3C SiC nano-powder absorbing materials of B, N codope are prepared in heat treatment in air atmosphere.The preparation method of B, N codope nanometer silicon carbide absorbing material of the present invention, prepares crystal formation and dielectric loss SiC nano-powders absorbing material of good performance, and its dielectric constant size is controllable.
Description
Technical field
The invention belongs to absorbing material preparation method technical field, and in particular to a kind of B, N codope nanometer silicon carbide is inhaled
The preparation method of wave material.
Background technology
Absorbing material refers to the electromagnetic energy of incident electromagnetic wave by material properties such as directric relaxation, vortex or magnetic hystersis losses
Change into thermal energy consumption to dissipate, to reach the material of electromagnetic wave absorption purpose.According to microwave hydrothermal synthesis, absorbing material is broadly divided into
Dielectric type and the major class of electromagnetic wave absorbing material two.
In this two major classes material, electromagnetic wave absorbing material, such as：Ferrite, carbonyl iron dust etc. are limited by Curie temperature,
Its magnetic can decay rapidly at relatively high temperatures, lose absorbing property, and larger density also governs their application.Cause
This, can be applied to the dielectric type absorbing material of high-temperature field, such as：SiC, h-BN and LaMnO3Etc. receiving much attention.Inhaled in dielectric type
In wave material, SiC is the main candidate material for making multiband absorbing material, if reasonable in design, it becomes possible to realize lightweight, thin
Layer, broadband and multiband absorb.
One of important directions of application exactly absorbing material is studied SiC by the states such as the U.S., Germany, Japan.But, conventional system
Standby SiC does not possess absorbing property, it is necessary to which it is further processed, and makes it have absorbing property.At present, effective approach
Mainly there are following two methods：(1) SiC purity is improved；(2) SiC is controlledly adulterated.Wherein, high-purity is prepared
There is high pure raw material and be difficult to obtain and prepare the problem of cost is high in SiC；By contrast, can also possess SiC by doping approach
Good absorbing property, i.e., carry out n-type to SiC or p-type adulterated, the electric conductivity of adjustment material obtains high dielectric loss
Energy.In addition, by adjusting dopant species and content SiC microwave permittivity size can be made controllable, electromagnetic wave incident is realized
Ripple or effectiveness are inhaled in the preferable impedance matching in interface, lifting.
As IV-IV race's semi-conducting material, SiC can respectively be mixed with the race's element of the group Ⅴ elements such as N, P and B, Al etc. III,
Alms giver is played or by main effect, so as to change its electric conductivity.In these doped chemicals, N, Al doping pair are had been realized at present
The raising of SiC material lossy microwave performance, and B doping raising SiC material lossy microwave performances do not have big breakthrough yet so far.Through
Research shows：B adulterates or addition contributes to the crystallization process of SiC crystal；And can be regulated and controled by having B, N codope by SiC nanometers
The theoretical report of pipe electrical property.Therefore, if the codope of B and N atom pair SiC crystal rational proportions can be realized, it is expected to obtain
Crystallization and the good SiC absorbing materials of absorbing property, and by controlling doping ratio, make the big I of its microwave permittivity
Control, realizes preferable impedance matching.
For the foregoing reasons, it is highly desirable to find the preparation method of the codoping modified SiC absorbing materials of a kind of B, N, energy
Crystal formation and dielectric loss SiC nano-powders absorbing material of good performance are prepared, and its dielectric constant size is controllable.
The content of the invention
It is an object of the invention to provide a kind of preparation method of B, N codope nanometer silicon carbide absorbing material, prepare
Crystal formation and dielectric loss SiC nano-powders absorbing material of good performance, and its dielectric constant size is controllable.
The technical solution adopted in the present invention is that a kind of preparation method of B, N codope nanometer silicon carbide absorbing material has
Body is implemented according to following steps：
Step 1, silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si are weighed respectively3N4And polytetrafluoroethylene powder
PTFE, and take silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si by what is weighed3N4And polytetrafluoroethylene powder PTFE balls
Mill mixing, prepares mixed powder A；
Step 2, the mixed powder A that step 1 is obtained crossed into 200 mesh sieves, to abolish aggregate, obtain average grain diameter for 74 μm
Following mixed powder B；
Step 3, the mixed powder B obtained through step 2 is positioned in vacuum-atmosphere hot pressing sintering stove, first carries out taking out true
Vacancy is managed, and is then charged with N2Gas, carries out self-propagating high-temperature reaction to mixed powder B, prepares the 3C-SiC master of B, N codope
Crystalline phase nano-powder；
Step 4, the 3C-SiC principal crystalline phase nano-powders of B, N codope obtained through step 3 are positioned over chamber type electric resistance furnace
In in air atmosphere be heat-treated, prepare the high-purity 3C-SiC nano-powder absorbing materials of B, N codope.
The features of the present invention is also resided in：
Step 1 is specifically implemented according to following steps：
Step 1.1, elder generation are n in molar ratioSi：nC：nB：nN=0.85~0.95：0.85~0.95：0.05~0.15：0.05
~0.15 weighs silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si respectively3N4；
Polytetrafluoroethylene powder PTFE is weighed afterwards, and polytetrafluoroethylene powder PTFE quality is silica flour Si, carbon powder C, without fixed
Shape boron powder B, silicon nitride powder Si3N4The 10%~20% of quality summation；
Step 1.2, by the silica flour Si weighed in step 1.1, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4And it is poly-
Tetrafluoroethene powder PTFE is mixed, and makes mixture A；
Step 1.3, obtained mixture A will be prepared through step 1.2 pour into planetary ball mill ball grinder, then to ball milling
Absolute ethyl alcohol is added in tank, using absolute ethyl alcohol as ball-milling medium, the mixture A per g will add the anhydrous of 1.0ml~1.5ml
Ethanol, opens planetary ball mill, with 250r/min~350r/min speed ball milling 6h~12h mixture A, obtains mixture
B；
The mixture B that step 1.4, taking-up are obtained through step 1.3, and mixture B is positioned in drying box up to drying,
Drying temperature is 55 DEG C~65 DEG C, finally gives mixed powder A.
Silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4Mol ratio be preferably nSi：nC：nB：nN=
0.95：0.85：0.05：0.15；
The preferred mass of polytetrafluoroethylene PTFE is：Silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4Matter
Measure the 20% of summation.
Silica flour Si average grain diameter is 10 μm~30 μm；Carbon powder C average grain diameter is 20nm~40nm；Amorphous boron powder
B average grain diameter is 45 μm~75 μm；Silicon nitride powder Si3N4Average grain diameter be 45 μm~75 μm；Polytetrafluoroethylene powder PTFE's
Average grain diameter is 60 μm~75 μm.
Step 3 is specifically implemented according to following steps：
Step 3.1, the mixed powder B obtained through step 2 is placed in crucible；
Step 3.2, it will be put into step 3.1 equipped with mixed powder B crucible in vacuum-atmosphere hot pressing sintering stove, and it is right
Vacuum-atmosphere hot pressing sintering stove carries out vacuumize process；
Step 3.3, through step 3.2, treat that the vacuum in vacuum-atmosphere hot pressing sintering stove reaches below 0.01Pa, Xiang Zhen
0.05MPa~0.1MPa high-purity N is filled with sky-atmosphere hot pressing sintering stove2Gas, makes mixed powder B be burnt in vacuum-atmosphere hot pressing
Self-propagating high-temperature reaction is carried out in freezing of a furnace, the 3C-SiC principal crystalline phase nano-powders of B, N codope are prepared.
The crucible used in step 3 is graphite crucible.
The detailed process of step 3.3 high temperature self-propagating reaction is as follows：
First with 10 DEG C/min~20 DEG C/min speed by the temperature in vacuum-atmosphere hot pressing sintering stove rise to 850 DEG C~
950℃；Again with 10 DEG C/min~15 DEG C/min speed by the temperature in vacuum-atmosphere hot pressing sintering stove rise to 1350 DEG C~
1450℃；Then under 1350 DEG C~1450 DEG C temperature conditionss, 10min~20min's is carried out to vacuum-atmosphere hot pressing sintering stove
Isothermal holding, most relief vacuum-atmosphere hot pressing sintering stove naturally cool to room temperature, that is, complete in vacuum-atmosphere hot pressing sintering stove
The interior self-propagating high-temperature to mixed powder B reacts.
Step 4 is specifically implemented according to following steps：
Step 4.1, the 3C-SiC principal crystalline phase nano-powders of B, N codope obtained through step 3 are placed in crucible；
Step 4.2, the crucible for the 3C-SiC principal crystalline phase nano-powders that B, N codope will be housed in step 4.1 are put into box
Heat treatment is carried out in resistance furnace and removes carbon, the high-purity 3C-SiC nano-powder absorbing materials that B, N are co-doped with are prepared.
The crucible used in step 4 is corundum crucible.
It is heat-treated in step 4.2 except the process of carbon is specific as follows：
The temperature in chamber type electric resistance furnace is first risen to 550 DEG C~650 DEG C with 5 DEG C/min~15 DEG C/min speed；Then
It is incubated 60min~150min；Most relief chamber type electric resistance furnace naturally cools to room temperature.
The beneficial effects of the present invention are：
(1) in a kind of preparation method of B, N codope nanometer silicon carbide absorbing material of the invention, low cost is employed
Si powder and carbon black effectively reduce preparation cost as raw material, and whole preparation flow is relatively simple in addition, and yield is high, be easy to
Manipulation, repeatability are strong.
(2) the SiC absorbing materials prepared using the preparation method of the present invention are the 3C-SiC nano powders of high-purity beta phase
Body, the nano-powder is in spherical pattern, and particle size distribution range is narrow, and average grain diameter is minimum up to 25nm or so.
(3) the SiC nano-powders absorbing material prepared using the preparation method of the present invention can be by adjusting B, N doping ratio
Example, realizes its adjustable target of microwave permittivity size, can meet absorbing material and electromagnetic shielding material matter under hot environment
Amount is light, thickness of thin, absorption band are wide etc. requires, and can be applied to prepare high intensity, good oxidation resistance or semiconduction SiC blocks
The high high-quality powder material of body ceramics and coating etc., with great economic results in society.
Brief description of the drawings
Fig. 1 is to obtain B, N codope SiC nano-powders absorbing material the first embodiment using the preparation method of the present invention
Field emission scanning electron microscope picture；
Fig. 2 is to obtain B, N codope SiC nano-powders second of embodiment of absorbing material using the preparation method of the present invention
Field emission scanning electron microscope picture；
Fig. 3 is to obtain B, N codope SiC nano-powders absorbing material the third embodiment using the preparation method of the present invention
Field emission scanning electron microscope picture；
Fig. 4 is to utilize B, N the codope SiC nano-powder dielectric loss angle tangents obtained in preparation method of the invention
Change curves of the tan δ in 8.2~12.4GHz frequency ranges.
Embodiment
The present invention is described in detail with reference to the accompanying drawings and detailed description.
A kind of preparation method of B, N codope nanometer silicon carbide absorbing material of the present invention, specifically implements according to following steps：
Step 1, silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si are weighed respectively3N4And polytetrafluoroethylene powder
PTFE, and take silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si by what is weighed3N4And polytetrafluoroethylene powder PTFE balls
Mill mixing, prepares mixed powder A, specifically implements according to following steps：
Step 1.1, elder generation are n in molar ratioSi：nC：nB：nN=0.85~0.95：0.85~0.95：0.05~0.15：0.05
~0.15 weighs silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si respectively3N4；
Polytetrafluoroethylene powder PTFE is weighed afterwards, and polytetrafluoroethylene powder PTFE quality is silica flour Si, carbon powder C, without fixed
Shape boron powder B, silicon nitride powder Si3N4The 10%~20% of quality summation；
Step 1.2, by the silica flour Si weighed in step 1.1, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4And it is poly-
Tetrafluoroethene powder PTFE is mixed, and makes mixture A；
Step 1.3, obtained mixture A will be prepared through step 1.2 pour into planetary ball mill ball grinder, then to ball milling
Absolute ethyl alcohol is added in tank, using absolute ethyl alcohol as ball-milling medium, the mixture A per g will add the anhydrous of 1.0ml~1.5ml
Ethanol, opens planetary ball mill, with 250r/min~350r/min speed ball milling 6h~12h mixture A, obtains mixture
B；
The mixture B that step 1.4, taking-up are obtained through step 1.3, and mixture B is positioned in drying box up to drying,
Drying temperature is 55 DEG C~65 DEG C, finally gives mixed powder A.
Silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4Mol ratio be preferably nSi：nC：nB：nN=
0.95：0.85：0.05：0.15；
The preferred mass of polytetrafluoroethylene PTFE is：Silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4Matter
Measure the 20% of summation.
Silica flour Si average grain diameter is 10 μm~30 μm；Carbon powder C average grain diameter is 20nm~40nm；Amorphous boron powder
B average grain diameter is 45 μm~75 μm；Silicon nitride powder Si3N4Average grain diameter be 45 μm~75 μm；Polytetrafluoroethylene powder PTFE's
Average grain diameter is 60 μm~75 μm.
Step 2, the mixed powder A that step 1 is obtained crossed into 200 mesh sieves, to abolish aggregate, obtain average grain diameter for 74 μm
Following mixed powder B；
Step 3, the mixed powder B obtained through step 2 is positioned in vacuum-atmosphere hot pressing sintering stove, first carries out taking out true
Vacancy is managed, and is then charged with N2Gas, carries out self-propagating high-temperature reaction to mixed powder B, prepares the 3C-SiC master of B, N codope
Crystalline phase nano-powder, specifically implements according to following steps：
Step 3.1, the mixed powder B obtained through step 2 is placed in crucible；
The crucible uses high purity graphite crucible；
Step 3.2, it will be put into step 3.1 equipped with mixed powder B crucible in vacuum-atmosphere hot pressing sintering stove, and it is right
Vacuum-atmosphere hot pressing sintering stove carries out vacuumize process；
Step 3.3, through step 3.2, treat that the vacuum in vacuum-atmosphere hot pressing sintering stove reaches below 0.01Pa, Xiang Zhen
0.05MPa~0.1MPa high-purity N is filled with sky-atmosphere hot pressing sintering stove2Gas, makes mixed powder B be burnt in vacuum-atmosphere hot pressing
Self-propagating high-temperature reaction is carried out in freezing of a furnace, the 3C-SiC principal crystalline phase nano-powders of B, N codope are prepared, self-propagating high-temperature is anti-
The detailed process answered is as follows：
First with 10 DEG C/min~20 DEG C/min speed by the temperature in vacuum-atmosphere hot pressing sintering stove rise to 850 DEG C~
950℃；Again with 10 DEG C/min~15 DEG C/min speed by the temperature in vacuum-atmosphere hot pressing sintering stove rise to 1350 DEG C~
1450℃；Then under 1350 DEG C~1450 DEG C temperature conditionss, 10min~20min's is carried out to vacuum-atmosphere hot pressing sintering stove
Isothermal holding, most relief vacuum-atmosphere hot pressing sintering stove naturally cool to room temperature, that is, complete in vacuum-atmosphere hot pressing sintering stove
The interior self-propagating high-temperature to mixed powder B reacts.
Step 4, the 3C-SiC principal crystalline phase nano-powders of B, N codope obtained through step 3 are positioned over chamber type electric resistance furnace
In in air atmosphere be heat-treated, prepare the high-purity 3C-SiC nano-powder absorbing materials of B, N codope, specifically according to
Lower step is implemented：
Step 4.1, the 3C-SiC principal crystalline phase nano-powders of B, N codope obtained through step 3 are placed in crucible；
The crucible uses corundum crucible.
Step 4.2, the crucible for the 3C-SiC principal crystalline phase nano-powders being co-doped with step 4.1 equipped with B, N is put into box electricity
Hinder and heat treatment is carried out in stove except carbon, prepare the high-purity 3C-SiC nano-powder absorbing materials that B, N are co-doped with, wherein heat treatment is removed
The process of carbon is specific as follows：
The temperature in chamber type electric resistance furnace is first risen to 550 DEG C~650 DEG C with 5 DEG C/min~15 DEG C/min speed；Then
It is incubated 60min~150min；Most relief chamber type electric resistance furnace naturally cools to room temperature.
Embodiment 1
It is first n in molar ratioSi：nC：nB：nN=0.95：0.95：0.05：0.05 weighs silica flour Si, carbon powder C, nothing respectively
Shape boron powder B, silicon nitride powder Si3N4, polytetrafluoroethylene powder PTFE is weighed afterwards, and polytetrafluoroethylene powder PTFE quality is silica flour
Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4The 10% of quality summation；Wherein silica flour Si average grain diameter is 10 μm,
Carbon powder C average grain diameter is 20nm, and amorphous boron powder B average grain diameter is 45 μm, silicon nitride powder Si3N4Average grain diameter be
45 μm, polytetrafluoroethylene powder PTFE average grain diameter is 60 μm；By the silica flour Si weighed, carbon powder C, amorphous boron powder B, nitridation
Silica flour Si3N4And polytetrafluoroethylene powder PTFE is mixed, mixture A is made；Mixture A is poured into planetary ball mill
In ball grinder, then absolute ethyl alcohol is added into ball grinder, using absolute ethyl alcohol as ball-milling medium, the mixture A per g will be added
1.0ml absolute ethyl alcohol, opens planetary ball mill, with 250r/min speed ball milling 6h mixture A, obtains mixture B；Take
Go out mixture B, and mixture B is positioned in drying box until drying, drying temperature is 55 DEG C, finally gives mixed powder A；
Mixed powder A is crossed into 200 mesh sieves, to abolish aggregate, the mixed powder B that average grain diameter is less than 74 μm is obtained；
Mixed powder B is placed in high purity graphite crucible；Will be equipped with mixed powder B high purity graphite crucible be put into vacuum-
In atmosphere hot pressing sintering stove, and vacuumize process is carried out to vacuum-atmosphere hot pressing sintering stove；Treat vacuum-atmosphere hot pressing sintering stove
Interior vacuum reaches below 0.01Pa, and 0.05MPa high-purity N is filled with into vacuum-atmosphere hot pressing sintering stove2Gas, makes mixing
Powder B carries out self-propagating high-temperature reaction in vacuum-atmosphere hot pressing sintering stove, prepares the 3C-SiC oikocrysts of B, N codope
The detailed process of phase nano-powder, wherein self-propagating high-temperature reaction is as follows：
The temperature in vacuum-atmosphere hot pressing sintering stove is first risen to 850 DEG C with 10 DEG C/min speed；Again with 10 DEG C/min
Speed the temperature in vacuum-atmosphere hot pressing sintering stove is risen to 1350 DEG C；In under 1350 DEG C of temperature conditionss, to vacuum-atmosphere
Hot-pressed sintering furnace carries out 10min isothermal holding, and most relief vacuum-atmosphere hot pressing sintering stove naturally cools to room temperature, that is, completed
Mixed powder B self-propagating high-temperature is reacted in vacuum-atmosphere hot pressing sintering stove；
The 3C-SiC principal crystalline phase nano-powders of B, N codope are placed in corundum crucible；It will be equipped with the 3C- of B, N codope
The corundum crucible of SiC principal crystalline phase nano-powders is put into chamber type electric resistance furnace, is carried out heat treatment and is removed carbon；Heat treatment has except the process of carbon
Body is as follows：
The temperature in chamber type electric resistance furnace is first risen to 550 DEG C with 5 DEG C/min speed；Then it is incubated 60min；Most relief case
Formula resistance furnace naturally cools to room temperature.
As shown in figure 1,3C-SiC powders prepared by embodiment 1 are nano particle, average grain diameter is about 40nm, grain diameter
Narrow distribution range, in spherical pattern.
Embodiment 2
It is first n in molar ratioSi：nC：nB：nN=0.95：0.90：0.05：0.10 weighs silica flour Si, carbon powder C, nothing respectively
Shape boron powder B, silicon nitride powder Si3N4, polytetrafluoroethylene powder PTFE is weighed afterwards, and polytetrafluoroethylene powder PTFE quality is silica flour
Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4The 20% of quality summation；Wherein silica flour Si average grain diameter is 20 μm,
Carbon powder C average grain diameter is 30nm, and amorphous boron powder B average grain diameter is 60 μm, silicon nitride powder Si3N4Average grain diameter be
60 μm, polytetrafluoroethylene powder PTFE average grain diameter is 70 μm；By the silica flour Si weighed, carbon powder C, amorphous boron powder B, nitridation
Silica flour Si3N4And polytetrafluoroethylene powder PTFE is mixed, mixture A is made；Mixture A is poured into planetary ball mill
In ball grinder, then absolute ethyl alcohol is added into ball grinder, using absolute ethyl alcohol as ball-milling medium, the mixture A per g will be added
1.25ml absolute ethyl alcohol, opens planetary ball mill, with 300r/min speed ball milling 9h mixture A, obtains mixture B；
Mixture B is taken out, and mixture B is positioned in drying box until drying, drying temperature is 60 DEG C, finally gives mixed powder
A；
Mixed powder A is crossed into 200 mesh sieves, to abolish aggregate, the mixed powder B that average grain diameter is less than 74 μm is obtained；
Mixed powder B is placed in high purity graphite crucible；Will be equipped with mixed powder B high purity graphite crucible be put into vacuum-
In atmosphere hot pressing sintering stove, and vacuumize process is carried out to vacuum-atmosphere hot pressing sintering stove；Treat vacuum-atmosphere hot pressing sintering stove
Interior vacuum reaches below 0.01Pa, and 0.08MPa high-purity N is filled with into vacuum-atmosphere hot pressing sintering stove2Gas, makes mixing
Powder B carries out self-propagating high-temperature reaction in vacuum-atmosphere hot pressing sintering stove, prepares the 3C-SiC oikocrysts of B, N codope
The detailed process of phase nano-powder, wherein self-propagating high-temperature reaction is as follows：
The temperature in vacuum-atmosphere hot pressing sintering stove is first risen to 900 DEG C with 15 DEG C/min speed；Again with 12 DEG C/min
Speed the temperature in vacuum-atmosphere hot pressing sintering stove is risen to 1400 DEG C；In under 1400 DEG C of temperature conditionss, to vacuum-atmosphere
Hot-pressed sintering furnace carries out 15min isothermal holding, and most relief vacuum-atmosphere hot pressing sintering stove naturally cools to room temperature, that is, completed
Mixed powder B self-propagating high-temperature is reacted in vacuum-atmosphere hot pressing sintering stove；
The 3C-SiC principal crystalline phase nano-powders of B, N codope are placed in corundum crucible；It will be equipped with the 3C- of B, N codope
The corundum crucible of SiC principal crystalline phase nano-powders is put into chamber type electric resistance furnace, is carried out heat treatment and is removed carbon；Heat treatment has except the process of carbon
Body is as follows：
The temperature in chamber type electric resistance furnace is first risen to 600 DEG C with 10 DEG C/min speed；Then it is incubated 100min；Most relief
Chamber type electric resistance furnace naturally cools to room temperature.
As shown in Fig. 2 3C-SiC powders prepared by embodiment 2 are nano particle, average grain diameter is about 30nm, grain diameter
Narrow distribution range, in spherical pattern.
Embodiment 3
It is first n in molar ratioSi：nC：nB：nN=0.95：0.85：0.05：0.15 weighs silica flour Si, carbon powder C, nothing respectively
Shape boron powder B, silicon nitride powder Si3N4, polytetrafluoroethylene powder PTFE is weighed afterwards, and polytetrafluoroethylene powder PTFE quality is silica flour
Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4The 15% of quality summation；Wherein silica flour Si average grain diameter is 30 μm,
Carbon powder C average grain diameter is 40nm, and amorphous boron powder B average grain diameter is 75 μm, silicon nitride powder Si3N4Average grain diameter be
75 μm, polytetrafluoroethylene powder PTFE average grain diameter is 75 μm；By the silica flour Si weighed, carbon powder C, amorphous boron powder B, nitridation
Silica flour Si3N4And polytetrafluoroethylene powder PTFE is mixed, mixture A is made；Mixture A is poured into planetary ball mill
In ball grinder, then absolute ethyl alcohol is added into ball grinder, using absolute ethyl alcohol as ball-milling medium, the mixture A per g will be added
1.5ml absolute ethyl alcohol, opens planetary ball mill, with 350r/min speed ball milling 12h mixture A, obtains mixture B；
Mixture B is taken out, and mixture B is positioned in drying box until drying, drying temperature is 65 DEG C, finally gives mixed powder
A；
Mixed powder A is crossed into 200 mesh sieves, to abolish aggregate, the mixed powder B that average grain diameter is less than 74 μm is obtained；
Mixed powder B is placed in high purity graphite crucible；Will be equipped with mixed powder B high purity graphite crucible be put into vacuum-
In atmosphere hot pressing sintering stove, and vacuumize process is carried out to vacuum-atmosphere hot pressing sintering stove；Treat vacuum-atmosphere hot pressing sintering stove
Interior vacuum reaches below 0.01Pa, and 0.1MPa high-purity N is filled with into vacuum-atmosphere hot pressing sintering stove2Gas, makes mixed powder
Body B carries out self-propagating high-temperature reaction in vacuum-atmosphere hot pressing sintering stove, prepares the 3C-SiC principal crystalline phases of B, N codope
The detailed process of nano-powder, wherein self-propagating high-temperature reaction is as follows：
The temperature in vacuum-atmosphere hot pressing sintering stove is first risen to 950 DEG C with 20 DEG C/min speed；Again with 15 DEG C/min
Speed the temperature in vacuum-atmosphere hot pressing sintering stove is risen to 1450 DEG C；In under 1450 DEG C of temperature conditionss, to vacuum-atmosphere
Hot-pressed sintering furnace carries out 20min isothermal holding, and most relief vacuum-atmosphere hot pressing sintering stove naturally cools to room temperature, that is, completed
Mixed powder B self-propagating high-temperature is reacted in vacuum-atmosphere hot pressing sintering stove；
The 3C-SiC principal crystalline phase nano-powders of B, N codope are placed in corundum crucible；It will be equipped with the 3C- of B, N codope
The corundum crucible of SiC principal crystalline phase nano-powders is put into chamber type electric resistance furnace, is carried out heat treatment and is removed carbon；Heat treatment has except the process of carbon
Body is as follows：
The temperature in chamber type electric resistance furnace is first risen to 650 DEG C with 15 DEG C/min speed；Then it is incubated 150min；Most relief
Chamber type electric resistance furnace naturally cools to room temperature.
As shown in figure 3,3C-SiC powders prepared by embodiment 3 are nano particle, average grain diameter is about 25nm, grain diameter
Narrow distribution range, in spherical pattern.
As shown in figure 4,3C-SiC micro-wave dielectric can be made using different B, N doping ratios and preparation technology parameter change
Losstangenttanδ value size is adjustable, and it can be more than 0.2 in the average of 8.2GHz~12.4GHz frequency ranges.
A kind of preparation method of B, N codope nanometer silicon carbide absorbing material of the present invention employs the Si powder and charcoal of low cost
It is black as raw material, effectively reduce preparation cost, whole preparation flow is relatively simple and is easily manipulated；In addition, the system of the present invention
In Preparation Method, by adjusting B, N doping ratio, so that it may realize its adjustable target of microwave permittivity size, high temperature can be met
Absorbing material and electromagnetic shielding material light weight, thickness of thin, absorption band are wide etc. requires under environment, and can be applied to prepare high
The high high-quality powder material of intensity, good oxidation resistance or semiconduction SiC block ceramics and coating etc., with great society's warp
Ji benefit.
The SiC absorbing materials prepared using the preparation method of the present invention are the 3C-SiC nano-powders of high-purity beta phase, should
Nano-powder is in spherical pattern, and particle size distribution range is narrow, and average grain diameter is minimum up to 25nm or so.
Claims (1)
1. a kind of preparation method of B, N codope nanometer silicon carbide absorbing material, it is characterised in that specific real according to following steps
Apply：
Step 1, silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si are weighed respectively3N4And polytetrafluoroethylene powder PTFE,
And by the silica flour Si weighed, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4And polytetrafluoroethylene powder PTFE ball milling mixings,
Mixed powder A is prepared, is specifically implemented according to following steps：
Step 1.1, elder generation are n in molar ratioSi：nC：nB：nN=0.95：0.85：0.05：0.15 weighs silica flour Si, carbon powder respectively
C, amorphous boron powder B, silicon nitride powder Si3N4；Polytetrafluoroethylene powder PTFE is weighed afterwards, and polytetrafluoroethylene powder PTFE quality is
Silica flour Si, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4The 20% of quality summation；
The average grain diameter of the silica flour Si is 10 μm~30 μm；Carbon powder C average grain diameter is 20nm~40nm；Amorphous boron powder
B average grain diameter is 45 μm~75 μm；Silicon nitride powder Si3N4Average grain diameter be 45 μm~75 μm；Polytetrafluoroethylene powder PTFE's
Average grain diameter is 60~75 μm；
Step 1.2, by the silica flour Si weighed in step 1.1, carbon powder C, amorphous boron powder B, silicon nitride powder Si3N4And polytetrafluoro
Ethene powder PTFE is mixed, and makes mixture A；
Step 1.3, the mixture A that will be obtained through step 1.2 preparation are poured into planetary ball mill ball grinder, then into ball grinder
Absolute ethyl alcohol is added, using absolute ethyl alcohol as ball-milling medium, the mixture A per g will add 1.0ml~1.5ml absolute ethyl alcohol,
Planetary ball mill is opened, with 250r/min~350r/min speed ball milling 6h~12h mixture A, mixture B is obtained；
The mixture B that step 1.4, taking-up are obtained through step 1.3, and mixture B is positioned in drying box until drying, drying
Temperature is 55 DEG C or 65 DEG C, finally gives mixed powder A；
Step 2, the mixed powder A that step 1 is obtained crossed into 200 mesh sieves, to abolish aggregate, obtain average grain diameter for less than 74 μm
Mixed powder B；
Step 3, the mixed powder B obtained through step 2 is positioned in vacuum-atmosphere hot pressing sintering stove, first carries out vacuumizing place
Reason, is then charged with N2Gas, carries out self-propagating high-temperature reaction to mixed powder B, prepares the 3C-SiC principal crystalline phases of B, N codope
Nano-powder, specifically implements according to following steps：
Step 3.1, the mixed powder B obtained through step 2 is placed in crucible, the crucible is high purity graphite crucible；
Step 3.2, will be put into step 3.1 equipped with mixed powder B crucible in vacuum-atmosphere hot pressing sintering stove, and to vacuum-
Atmosphere hot pressing sintering stove carries out vacuumize process；
Step 3.3, through step 3.2, treat that the vacuum in vacuum-atmosphere hot pressing sintering stove reaches below 0.01Pa, to vacuum-gas
0.05MPa~0.1MPa high-purity N is filled with atmosphere hot-pressed sintering furnace2Gas, makes mixed powder B in vacuum-atmosphere hot pressing sintering stove
Interior progress self-propagating high-temperature reaction, prepares the 3C-SiC principal crystalline phase nano-powders of B, N codope；
The detailed process of the self-propagating high-temperature reaction is as follows：
The temperature in vacuum-atmosphere hot pressing sintering stove is first risen to 850 DEG C~950 with 10 DEG C/min~20 DEG C/min speed
℃；The temperature in vacuum-atmosphere hot pressing sintering stove is risen to 1400 DEG C~1450 with 10 DEG C/min~15 DEG C/min speed again
℃；Then under 1400 DEG C~1450 DEG C temperature conditionss, 10min~20min insulation is carried out to vacuum-atmosphere hot pressing sintering stove
Processing, most relief vacuum-atmosphere hot pressing sintering stove naturally cools to room temperature, that is, completes right in vacuum-atmosphere hot pressing sintering stove
Mixed powder B self-propagating high-temperature reaction；
Step 4, the 3C-SiC principal crystalline phase nano-powders of B, N codope obtained through step 3 are positioned in chamber type electric resistance furnace
It is heat-treated in air atmosphere, the high-purity 3C-SiC nano-powder absorbing materials of B, N codope is prepared, specifically according to following step
It is rapid to implement：
Step 4.1, the 3C-SiC principal crystalline phase nano-powders of B, N codope obtained through step 3 are placed in crucible, the crucible
It is corundum crucible；
Step 4.2, the crucible for the 3C-SiC principal crystalline phase nano-powders that B, N codope will be housed in step 4.1 are put into box resistance
Heat treatment is carried out in stove and removes carbon, the high-purity 3C-SiC nano-powder absorbing materials of B, N codope are prepared；
The heat treatment is specific as follows except the process of carbon：
The temperature in chamber type electric resistance furnace is first risen to 550 DEG C~600 DEG C with 5 DEG C/min~15 DEG C/min speed；Then it is incubated
60min~150min；Most relief chamber type electric resistance furnace naturally cools to room temperature.
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