CN100506690C - Preparation method of hexagonal boron nitride and produced hexagonal boron nitride multi-crystal powder - Google Patents
Preparation method of hexagonal boron nitride and produced hexagonal boron nitride multi-crystal powder Download PDFInfo
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Abstract
A process for preparing the flaky powder of hexagonal boron nitride polycrystal includes such steps as proportional reaction between the B source chosen from NaBH4, KBH4 and NaBF4 and the N source (NaNH2) at 500-600 deg.C, washing, filtering and drying. Said product can have various forms and uniform size (nano class or submicron class).
Description
Technical field:
The present invention relates to the nanometer and the micron sheet hexagonal boron nitride polycrystalline body powder of the method for synthetic hexagonal boron nitride and preparation thus.
Background technology:
That hexagonal boron nitride has is high temperature resistant, high thermal conductivity, radiation hardness, corrosion-resistant, and high temperature lubricating and good dielectric, insulating property especially have preferably in aerospace, national defence, electronics and nuclear industry in every field and to use.Nanometer and submicron order sheet hexagonal boron nitride polycrystalline body powder all have great application prospect at aspects such as preparation high heat-conducting ceramic device, high heat conduction speciality coating, heat conductive insulating polymer composites, the saturating wave device of high strength solar heat protection high-frequency insulation, heat-resisting solid lubricant and lubricating oil and grease additives.
Known synthetic hexagonal boron nitride has several different methods, comprises carbothermal reduction-nitridation such as borax, boric acid, pyroboric acid, boron oxide or ammonia is separated or to prepare the self-propagating combustion of boron nitride synthetic with urea reaction, laser method gas-phase reaction method, precursor pyrolysis method etc.Also developed liquid phase preparation process in recent years, such as benzene heat and Hydrothermal Preparation boron nitride.Before the present invention, the existing a lot of patent reports of synthetic and preparation method about hexagonal boron nitride, such as, publication number is that the Chinese invention patent application of CN1073658 discloses a kind of novel method and thus obtained boron nitride for preparing boron nitride, and it can generate boron nitride after adopting the borazine using pyrolysis.Publication number is that the Chinese invention patent application of CN1323738 and CN1539729 discloses with organic solvent liquid phase chemical prepared in reaction nanometer boron nitride micro powder, or the like.Publication number is that the Chinese invention patent application of CN1227531 discloses a kind of oval plate-like or discoid hexagonal boron nitride polycrystalline body and preparation method who is made up of the crystallite of nano-scale, but the reaction scheme that the present invention relates to is all fully different with it with the product form.
There is report to use NaNH
2With NaBF
4In benzene in 260 ℃ of following prepared in reaction t-BN, NaNH
2, NH
4Cl and BBr
3At 400-450 ℃ of following prepared in reaction soccerballene type boron nitride, NaNH
2With BBr
3Prepared in reaction boron nitride hollow bead at room temperature, NaNH
2With NH
4BF
4At 320 ℃ of following prepared in reaction t-BN powder, KBH
4With NH
4Cl is prepared in reaction whisker shape nm-class boron nitride under 320 ℃ of conditions, KBH
4With NH
4BF
4And NaN
3Prepared in reaction boron nitride nano-tube under 450-600 ℃ of condition, KBH
4With NH
4BF
4With zinc powder hollow pearl boron nitride of prepared in reaction under 600 ℃ of conditions, KBH
4With [Co (NH
3)
6] Cl
3Prepared in reaction boron nitride composition metal cobalt under 500-1000 ℃ of condition, electric arc fuses LaB
6Powder prepares nanotube-shaped and the taper boron nitride, MgB
2With NH
4Cl or NH
4Cl-NaN
3Reaction prepares needle-like and hollow pearl boron nitride etc. respectively, and it is all different with the present invention that these are reported in synthetic method, reaction scheme and target product aspect.
Because boron nitride fusing point height (2075 ℃), it is to carry out in silicon melt (greater than 1850 ℃), metallic nickel melt (about 1000 ℃) or sodium Metal 99.5 melt (700-800 ℃) that its crystal growth of report was arranged in the past.
Summary of the invention:
The preparation method and the hexagonal boron nitride polycrystalline body powder obtained by this method that the purpose of this invention is to provide a kind of hexagonal boron nitride, this preparation method's reaction conditions gentleness, preparation process is simple, prepared hexagonal boron nitride polycrystalline body is different-shapes such as trilateral sheet, hexagon sheet, sub-elliptical sheet, irregular sheet, the product crystallization degree is good, the purity height, size and pattern are even.
For reaching above-mentioned purpose, the preparation method of hexagonal boron nitride of the present invention is: with alkali metal borohydride, alkali metal fluosilicate borate or metal boride is the boron source, with NaNH
2, Li
3N, Mg
3N
2Or NaN
3Be nitrogenous source, the reaction kettle for reaction of 500-700 ℃ of lower seal 5～48 hours, product by washing, filter and dry, promptly get nanometer and submicron sheet hexagonal boron nitride polycrystalline body powder.
Described alkali metal borohydride or alkali metal fluosilicate borate are NaBH
4, KBH
4, NaBF
4, or KBF
4Deng, described metal boride CaB
6, LaB
6, MgB
2, SrB
6Or BaB
6Deng.
Consider production cost and production security, the preferred NaNH of described nitrogenous source
2
In order to save NaNH
2Consumption, also add sodium Metal 99.5 in the described reactant.
As a kind of preferred version, described reactant is 12～24 hours in the reaction kettle for reaction time of sealing.
As another preferred version, in described reactor, heat up again behind the rare gas elementes such as adding nitrogen or argon gas and react.
In order to realize the present invention preferably, after described reaction is finished, make it to naturally cool to about 25～50 ℃, open kettle cover and add dehydrated alcohol, soaked 12～24 hours, collect product and, remove solubility by product and impurity with distilled water wash and centrifugation, in vacuum drying oven in 80 ℃ dry 24 hours down.
When being the boron source, after dehydrated alcohol is handled and distilled washing, also soak, in order to remove metallic product wherein with dilute acid soln with the metal boride.Described acid is hydrochloric acid or nitric acid, and concentration is 0.1-1M.
By the nanometer and the submicron sheet hexagonal boron nitride polycrystalline body powder of above-mentioned preparation method's gained, be the nanometer and the submicron hexagonal boron nitride polycrystalline body powder of different-shapes such as approximate equilateral triangle sheet, approximate regular hexagon sheet, oval sheet, irregular sheet; The above particle of 80wt.% is included in median size ± 20% scope; The approximate flaky length of side L of equilateral triangle, thickness d satisfy 400nm≤L≤500nm, 10nm≤d≤55nm; Approximate regular hexagon sheet length of side L, thickness d satisfy 320nm≤L≤350nm, 30nm≤d≤80nm; Oval flaky mean sizes is that minor axis L1, longitudinal axis L 2 and thickness t satisfy 50nm ≦ L1 ≦ L2 ≦ 250nm, 20nm ≦ t ≦ 40nm; The mean sizes of irregular sheet boron nitride particle is that minor axis L1, major diameter L2 and thickness t satisfy 400nm ≦ L1 ≦ L2 ≦ 1.2 μ m, 4nm ≦ t ≦ 10nm, 0.6 ≦ L1/L2 ≦ 1.0.
With the sodium amide is that nitrogenous source is an example, and the main chemical reactions equation that the present invention relates to is expressed as:
M
1BH
4+NaNH
2＝BN+M
1+Na+3H
2(M
1＝Na、K) (1)
M
1BF
4+n?NaNH
2+(3-n)Na＝BN+M
1F+3NaF+0.5(n-1)N
2+n?H
2(M
1＝Na、K；1≦n≦3) (2)
M
2B
6+ 6NaNH
2=6BN+M
2+ 6Na+6H
2(M
2=Ca, La etc.) (3)
Shown in above-mentioned reaction equation, NaBH
4, KBH
4Or NaBF
4, KBF
4500 ℃ of following decomposes, produce
BH
3Or BF
3, these boracic intermediate product and NaNH
2Reaction, thus hexagonal boron nitride generated.With respect to sodium Metal 99.5, sodium amide is the higher low melting point solid nitrogenous source of a kind of price, in reaction equation (2), uses sodium Metal 99.5 to replace fluorine in sodium amide and the balanced reaction system for reducing its consumption.Na/NH with suitable proportion
4Cl also can realize corresponding preparation as nitrogenous source.But because NH
4Cl decomposes generation HCl gas in reaction, can cause reactor corrosion, and cause product to contain impurity.Sodium Metal 99.5 fusing point low (97.82 ℃), not only change chemical reaction and relax reaction as reactant and heat absorbent, simultaneously also as boron nitride nanometer and submicron sheet hexagonal boron nitride polycrystalline bulk-growth media, not only realized gentle reaction conditions, preparation process is also fairly simple, and can obtain pure, the uniform sheet hexagonal boron nitride polycrystalline body of different appearances.
The CaB that the present invention is used
6, LaB
6, NaNH
2, NaN
3With metal Na etc. all be chemically pure reagent.Sodium amide is kept in the toluene, the first using in 50 ℃ of vacuum dry 2 hours, removes the organism on surface.Metal Na is taken out from kerosene, blots with filter paper, is cut into small pieces.NaN
3Before use without special processing.All the other reagent are analytical pure.Weighing is also calculated productive rate, the product boron nitride with respect to the yield of boracic reactant feed all more than 95%.
Temperature of reaction and time are found to be lower than 500 ℃ condition to the influence of product, and product hexagonal boron nitride polycrystalline bodily form looks are tending towards irregular, and the sheet grain is very thin, and thickness is generally less than 10nm.Temperature be higher than 650 ℃ help polycrystalline grain sheet grow up and long thick, form and mostly be micron-sized platy shaped particle.Reaction times is not obvious to the product influence, generally more than 12 hours, reacts not only complete, and all can obtain repeatability target product preferably.
MSAL-XD2 type X-light powder diffractometer (40kV, 20mA, λ=1.5406 are used in the analysis of products therefrom sample X-ray diffraction
2 θ are 10-80 ° of scope.With Technai-10 type and JEM-2010HR type transmission electron microscope observation product pattern (tem analysis),, analyze its composition with electron scattering power spectrum (EDS), X-photoelectron spectrum (XPS) with the microstructure of electron diffraction (SAED) research material.The method for making sample that electron microscopy observation, electron diffraction and EDS analyze, be with the product powder by ultrasonic dispersing in dehydrated alcohol, drop in then on the special-purpose carbon film copper mesh of TEM and observe.The product sample also uses JSM-6330F type field emission scanning electron microscope (SEM) to observe pattern and uses EDS to analyze its composition, and its method for making sample is directly to adopt the product powder distribution on the double faced adhesive tape and be bonded on the sample copper platform and observe behind the metal spraying.FTIR analyzes and adopts BRUKEREQUINOX55 type infrared spectrometer, and the product powder uses the sample preparation of KBr compressing tablet.ESCALAB 250 model (Thermao Electron Corp.) X-gamma spectrometer is adopted in the analysis of X-ray energy spectrum, is excitation light source with the K α line of aluminium, and carbon (bound energy C1s 285.5eV) is interior mark.
Description of drawings:
Fig. 1. product hexagonal boron nitride XRD spectra: among the figure, (a) NaBH
4/ NaNH
2, 500 ℃-12 hours; (b) KBH
4/ NaNH
2, 600 ℃-48 hours.
Fig. 2. be product hexagonal boron nitride TEM (left side) and SEM (right side) figure, (a) and (b): NaBH
4/ NaNH
2, 500 ℃-12 hours; (c), (d): KBH
4/ NaNH
2, 600 ℃-48 hours.Scale length: (a) 100nm; (b) 5 μ m; (c) 100nm; (d) 1 μ m.
Fig. 3. product hexagonal boron nitride FTIR spectrogram, (a) NaBH among the figure
4/ NaNH
2, 500 ℃-12 hours; (b) KBH
4/ NaNH
2, 600 ℃-48 hours.
Fig. 4. product hexagonal boron nitride XRD spectra: (a) NaBF among the figure
4/ NaNH
2, 600 ℃-12 hours; (b) KBH
4/ NaNH
2, 600 ℃-24 hours.
Fig. 5. product hexagonal boron nitride TEM (left side)/SEM (right side) figure, (a) and (b): NaBF
4/ NaNH
2, 600 ℃-12 hours; (c), (d): KBF
4/ NaNH
2, 600 ℃-24 hours.Scale length is all represented 1 μ m.
Fig. 6. product hexagonal boron nitride FTIR spectrogram, (a) NaBF among the figure
4/ NaNH
2, 600 ℃-12 hours; (b) KBH
4/ NaNH
2, 600 ℃-24 hours.
Fig. 7. product hexagonal boron nitride XRD spectra: (a) CaB among the figure
6/ NaNH
2, 600 ℃-24 hours; (b) LaB
6/ NaNH
2, 600 ℃-24 hours.
Fig. 8. product hexagonal boron nitride TEM (left side)/SEM (right side) figure, (a) and (b): CaB
6/ NaNH
2, 600 ℃-24 hours; (c), (d): LaB
6/ NaNH
2, 600 ℃-24 hours.Scale length: (a) 500nm; (b): 2 μ m; (c) 1 μ m; (d) 2 μ m.
Fig. 9. product hexagonal boron nitride FTIR spectrogram, (a) CaB among the figure
6/ NaNH
2, 600 ℃-24 hours; (b) LaB
6/ NaNH
2, 600 ℃-24 hours.
Figure 10. product X-ray energy spectrum figure: (a) LaB among the figure
6/ NaNH
2, 600 ℃-24 hours; (b) KBH
4/ NaNH
2, 600 ℃-48 hours; (c) LaB
6/ NaNH
2, 600 ℃-24 hours; B1s that inserts among the figure and N1s power spectrum are corresponding to sample (b).
Fig. 1-3 has showed respectively M1BH
4/NaNH
2(M
1=Na, K) reaction system is at 500-600 ℃ React XRD, TEM/SEM and the FTIR data of the product hexagonal boron nitride that obtained in 12-48 hour. XRD spectra among Fig. 1 can index turn to hexagonal boron nitride, with JCPDS card# No. The data of 85-1068 conform to. Fig. 2 shows product hexagonal boron nitride pattern and size, wherein with NaBH4For raw material preparation be random sheet polycrystal, with KBH4For the raw material preparation is ellipse The disc-shaped polycrystal. According to statistics with calculate, random sheet polycrystal average-size be minor axis L1, Major diameter L2 and thickness t satisfy 400nm=L1＜=L2=1.2 μ m, 4nm＜=t＜=10nm, 0.6＜=L1/L2＜=1.0 are included in average grain diameter ± 20% more than the hexagonal boron nitride polycrystalline body grain sheet 80wt% In the scope; Oval sheet polycrystal average-size is that minor axis L1, longitudinal axis L 2 and thickness t satisfy 50 Nm=L1＜=L2=250nm, 20nm＜=t＜=40nm, 0.2＜=L1/L2＜=1.0,80wt% with On the grain sheet be included in average grain diameter ± 20% scope. Fig. 3 is product hexagonal boron nitride FTIR spectrum Figure is wherein at 1383cm-1Absworption peak is owing to stretching vibration in the face of B-N key in the hexagonal boron nitride causes, at 810.9cm-1Absworption peak is owing to B-N keyboard outside sweep vibration in the hexagonal boron nitride is drawn Rise, the absorption that this two place is strong shows that product is hexagonal boron nitride. 1075cm-1The faint suction at place Be to receive the B-N key that comes from the cubic boron nitride to absorb, illustrate that cubic boron nitride is few in the product, Be difficult to be detected, this is consistent with XRD result. 1635cm-1The absorption at place illustrates that corresponding to the N-H key product surface may be with-NH2Group, and 3439cm-1Absorption, come from sample The moisture that product absorb is corresponding to the energy absorption of the O-H key of water.
Accompanying drawing 4-6 has showed respectively MBF4/NaNH
2(M=Na, K) reaction system is 600 ℃ of reactions XRD, TEM/SEM and the FTIR data of the product hexagonal boron nitride that obtained in 12-24 hour. Figure XRD analysis in 4 shows that product is hexagonal boron nitride, with JCPDS card# No.85-1068 phase Meet. Fig. 5 shows product pattern and size, wherein with NaBF4The boron nitride polycrystalline body for preparing for raw material is the triangle sheet, with KBF4For the raw material preparation is the hexagon sheet. The triangle sheet is many Crystal is similar to the equilateral triangle sheet, and its average-size is that length of side L and thickness d satisfy L=500nm, 30nm＜=d＜=55nm. The hexagon sheet is similar to regular hexagon, and its average-size is the length of side L and thickness d satisfy L=350nm, 30nm＜=d＜=60nm. Triangle sheet and hexagon Be included in average grain diameter ± 20% scope more than the multicrystal grain of the sheet sheet 80wt%. Fig. 6 Be product hexagonal boron nitride FTIR spectrogram, wherein B-N key absworption peak is 1382cm-1With 799.2 cm-1，1062cm
-1The Weak Absorption at place may come from the B-N key in the cubic boron nitride, 1637 cm-1Corresponding to N-H key, 3439cm-1The moisture that comes from absorption of sample.
Fig. 7-9 has showed respectively M2B
6/NaNH
2(M
2=Ca, La) reaction system is 600 ℃ of reactions XRD, TEM/SEM and the FTIR data of the product hexagonal boron nitride that obtained in 24 hours. Fig. 7 In XRD result show that product is hexagonal boron nitride, with JCPDS card# No.85-1068 phase Meet. Fig. 8 (a), Fig. 8 (b), Fig. 8 (c), Fig. 8 (d) have showed product pattern and chi Very little, wherein with CaB6The product for preparing for raw material is similar to equilateral triangle sheet polycrystal, with LaB6For the raw material preparation is to be similar to regular hexagon sheet polycrystal. Its average-size is the equilateral triangle sheet Length of side L and thickness d satisfy L=400nm, 10nm＜=d＜=50nm. The regular hexagon sheet Average-size is that length of side L and the thickness d of sheet satisfies L=320nm, 50nm＜=d＜=80nm. The above grain sheet of triangle sheet and the multicrystal 80wt% of hexagon sheet is included in average particle Directly ± 20% in the scope. Fig. 9 is the FTIR spectrogram of product hexagonal boron nitride, and wherein the B-N key absorbs The peak is 1387cm-1And 809.4cm-1，1109cm
-1Place's Weak Absorption may come from the B-N key in the cubic boron nitride, 1633-1641cm-1Corresponding to N-H key, 3422-3423cm-1The moisture that comes from absorption of sample, the acromion 3168-3183cm that it is faint-1Corresponding to the N-H key.
Figure 10 provides the X-radial energy spectrogram of product sample, as seen from the figure, sample surfaces contain B, N and a small amount of C, O, wherein C is the interior mark of analyzing, O is due to sample surfaces adsorbs. In conjunction with Can be in B1s, the N1s at 189.72eV and 397.5eV place and hexagonal boron nitride the knot of boron and nitrogen Close and to be consistent, show that product is hexagonal boron nitride. And according to quantitative analysis, the B:N atomic ratio all Close to 1:1. In addition, in product being done TEM, SEM research, the product hexagonal boron nitride is received Rice and the multicrystal domain structure of sub-micron and composition analysis, its SAED, EDS also prove product Thing is hexagonal boron nitride.
Embodiment:
Embodiment 1
Get 3.880 gram NaBH
4With 4.2 gram NaNH
2Adding volume is the 60ml stainless steel cauldron, operates in the glove box that charges into dry argon gas at ambient temperature and carries out.Reactor is built, put into well formula crucible oven after the sealing, in 500 ℃ of isothermal reactions 12 hours, make it naturally cooling then, drive still and add dehydrated alcohol, soaked 24 hours, collect product and use distilled water wash and centrifugation, remove solubility by product and impurity, in vacuum drying oven,, obtain 2.445 gram white powders in 80 ℃ times dry 24 hours.Through structure, microstructure, composition and morphology analysis, prove that product is purified random sheet hexagonal boron nitride polycrystalline body powder, with respect to NaBH
4Yield is 96.1%, and its pattern and size are seen Fig. 2 (a) and Fig. 2 (b).
Embodiment 2
Get 3.544 gram NaBH
4, 5 the gram NH
4Cl and 4.3 gram sodium Metal 99.5s add the previous reaction still.In well formula crucible oven in 600 ℃ of isothermal reactions 12 hours, naturally cooling, drive still and add dehydrated alcohol, soak 24 hours in order to remove sodium Metal 99.5, the centrifugation solid also soaked 12 hours with concentrated hydrochloric acid, used distilled water wash and centrifugation again, removed water-soluble by product and impurity, in vacuum drying oven,, obtain 2.255 gram pale powders in 80 ℃ times dry 24 hours.Prove that by analysis product is a hexagonal boron nitride polycrystalline body powder, with respect to NaBH
4Yield is 97.0%, and its appearance and size is similar with accompanying drawing 2 (b) to accompanying drawing 2 (a).
Embodiment 3
Get 5.530 gram KBH
4, 4.2 the gram NaNH
2, add the previous reaction still.In well formula crucible oven,, make it naturally cooling then in 600 ℃ of isothermal reactions 48 hours.Add dehydrated alcohol after driving still, soak 24 hours so that remove the sodium Metal 99.5 potassium-sodium alloy.Reaction back is with distilled water wash and centrifugation, eccysis by product and impurity, in vacuum drying oven in 80 ℃ dry 24 hours down, obtain 2.50 gram white powders.Prove that by analysis product is purified oval sheet hexagonal boron nitride polycrystalline body powder, with respect to KBH
4Yield is 98.2%, its appearance and size Fig. 2 (c) and Fig. 2 (d).
Embodiment 4
Get 5.630 gram NaBF
4, 2.5 the gram NaNH
2With 2.36 gram sodium Metal 99.5s, add the previous reaction still.In well formula crucible oven,, naturally cooling, open behind the still and added soaked in absolute ethyl alcohol 24 hours in 600 ℃ of isothermal reactions 12 hours.With distilled water wash and centrifugation, eccysis by product and impurity, in vacuum drying oven,, obtain 1.213 gram white powders in 80 ℃ times dry 24 hours.Prove that by analysis product is purified hexagonal boron nitride polycrystalline body powder, with respect to NaBF
4Yield is 95.2%, and it is similar to equilateral triangle sheet pattern and size is seen Fig. 5 (a) and Fig. 2 (b).
Embodiment 5
Get 6.45 gram KBF
4, 2.5 the gram NaNH
2With 2.36 gram sodium Metal 99.5s, add the previous reaction still, in well formula crucible oven in 600 ℃ of isothermal reactions 24 hours, drive still behind the naturally cooling, product is used alcohol immersion 24 hours, with distilled water wash and centrifugation, eccysis by product and impurity, in vacuum drying oven,, obtain 1.209 gram white powders in 80 ℃ times dry 24 hours.Prove that by analysis product is purified hexagonal boron nitride polycrystalline body powder, with respect to KBF
4Yield is 95.1%, and it is similar to regular hexagon sheet pattern and size is seen Fig. 5 (c) and Fig. 5 (d).
Embodiment 6
Get 4.22 gram NaBF
4, 2.53 the gram NaN
3With 1.77 gram sodium Metal 99.5s, add the previous reaction still, in 500 ℃ of isothermal reactions 10 hours, drive still behind the naturally cooling, product is used alcohol immersion 24 hours, with distilled water wash and centrifugation, solid product in 80 ℃ times dry 24 hours, obtains 0.908 gram white powder in vacuum drying oven.Prove that by analysis product is purified hexagonal boron nitride sheet nulti-crystal powder, with respect to KBF
4Yield is 95.2%, and its appearance and size is similar with Fig. 5 (d) to Fig. 5 (c).
Embodiment 7
Get 2.017 gram CaB
6, 5.5 the gram NaNH
2Add the previous reaction still, the sealing and in 600 ℃ of isothermal reactions 24 hours, drive still behind the naturally cooling, product is used soaked in absolute ethyl alcohol 24 hours, uses 1M salt acid soak 12 hours again, use distilled water wash and centrifugation then, eccysis by product and impurity, solid product in 80 ℃ times dry 24 hours, obtain 2.821 gram white powders in vacuum drying oven.Be purified hexagonal boron nitride sheet nulti-crystal powder by analysis, with respect to CaB6
4Yield is 98.5%, and its appearance and size is seen Fig. 8 (a) and Fig. 8 (b).
Embodiment 8
Get 2.612 gram LaB
6With 4 gram NaNH
2Add previous reaction, the sealing and in 600 ℃ of isothermal reactions 24 hours, drive still behind the naturally cooling, product is used soaked in absolute ethyl alcohol 24 hours, used the 0.5M nitric acid dousing again 12 hours, and used distilled water wash and centrifugation then, eccysis by product and impurity, in vacuum drying oven,, obtain 1.863 gram white powders in 80 ℃ times dry 24 hours.Prove purified hexagonal boron nitride polycrystalline body powder by analysis, with respect to LaB
6Yield is 97.6%, and its appearance and size is seen Fig. 8 (c) and Fig. 8 (d).
Claims (9)
1, a kind of preparation method of hexagonal boron nitride is characterized in that: with alkali metal borohydride, alkali metal fluosilicate borate or metal boride is the boron source, with NaNH
2, Li
3N, Mg
3N
2Or NaN
3Be nitrogenous source, reacted 5～48 hours down that product promptly gets nanometer and submicron sheet hexagonal boron nitride polycrystalline body powder by washing, filtration and dry at 500-700 ℃.
2, preparation method according to claim 1 is characterized in that: described alkali metal borohydride or alkali metal fluosilicate borate are NaBH
4, KBH
4, NaBF
4, or KBF
4, described metal boride CaB
6, LaB
6, MgB
2, SrB
6Or BaB
6
3, preparation method according to claim 1 is characterized in that: described nitrogenous source is NaNH
2
4, preparation method according to claim 1 is characterized in that: also add sodium Metal 99.5 in reaction.
5, preparation method according to claim 1 is characterized in that: described reactant is 12～24 hours in the reaction kettle for reaction time of sealing.
6, preparation method according to claim 1 is characterized in that: heat up behind the adding rare gas element in described reactor again and react.
7, preparation method according to claim 1, it is characterized in that: after described reaction is finished, make it to naturally cool to 25～50 ℃, open kettle cover and add dehydrated alcohol, soaked 12～24 hours, collect product and, remove solubility by product and impurity with distilled water wash and centrifugation, in vacuum drying oven in 80 ℃ dry 24 hours down.
8, preparation method according to claim 7, it is characterized in that: when being the boron source, after dehydrated alcohol is handled and distilled washing, also embathe with 0.1-1M dilute suplhuric acid solution with the metal boride, remove metallic product wherein, use distilled water wash, filtration and drying again.
9, by the nanometer and the submicron sheet hexagonal boron nitride polycrystalline body powder of each described preparation method's gained in the claim 1 to 8, the polycrystal particle is approximate equilateral triangle sheet, approximate regular hexagon sheet, oval sheet or irregular flaky nanometer and submicron hexagonal boron nitride polycrystalline body; The above particle of 80wt.% is included in median size ± 20% scope; The approximate flaky length of side L of equilateral triangle, thickness d satisfy 400nm≤L≤500nm, 10nm≤d≤55nm; Approximate regular hexagon sheet length of side L, thickness d satisfy 320nm≤L≤350nm, 30nm≤d≤80nm; Oval flaky mean sizes is that minor axis L1, longitudinal axis L 2 and thickness t satisfy 50nm ≦ L1 ≦ L2 ≦ 250nm, 20nm ≦ t ≦ 40nm; The mean sizes of irregular sheet boron nitride particle is that minor axis L1, major diameter L2 and thickness t satisfy 400nm ≦ L1 ≦ L2 ≦ 1.2 μ m, 4nm ≦ t ≦ 10nm, 0.6 ≦ L1/L2 ≦ 1.0.
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| CN101318636B (en) * | 2008-05-12 | 2011-04-13 | 中国科学院上海硅酸盐研究所 | Method for in situ preparing hexagonal boron nitride containing composite material with nitridation |
| WO2010006080A2 (en) * | 2008-07-08 | 2010-01-14 | Chien-Min Sung | Graphene and hexagonal boron nitride planes and associated methods |
| CN102502535B (en) * | 2011-11-28 | 2013-06-26 | 镇江中孚复合材料有限公司 | Method for preparing carbon coated hexagonal boron nitride |
| CN102757025B (en) * | 2012-05-08 | 2014-07-02 | 辽宁科技大学 | Method for synthesizing high-density hexagonal boron nitride in high-temperature and self-propagating way |
| WO2015080899A1 (en) | 2013-11-27 | 2015-06-04 | Board Of Trustees Of Northern Illinois University | Boron nitride and method of producing boron nitride |
| CN104528670B (en) * | 2015-01-16 | 2017-01-11 | 福州大学 | Preparation methods of graphite-phase boron nitride nano wafer and colloid thereof |
| CN107217332A (en) * | 2017-03-28 | 2017-09-29 | 深圳新宙邦科技股份有限公司 | A kind of nitrogen/boron/fluorine ternary codope carbon fiber and preparation method thereof |
| CN115180957B (en) * | 2022-07-11 | 2023-03-31 | 哈尔滨工业大学 | Preparation method of hexagonal boron nitride ceramic with excellent thermal wave transmission performance |
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