CN1053638C - Manufacture of carbon tubes in nanon size - Google Patents

Abstract

The present invention relates to a technology for preparing nanometer carbon tubes, which is characterized in that infusible metastable noncrystalline SiCxNyHz solid reaction materials are used for generating the nanometer carbon tubes in situ in an ordinary thermolysis mode under the conditions of nitrogen atmosphere, 0.5 to 2.0 atmospheric pressure and 1300 to 2000 DEG C of the thermolysis temperature for 0.5 to 5 hours, wherein x meets the requirement of 0.39<=x<=1, y meets the requirement of 0.39<=y<=1.34, and z meets the requirement of 0.5<=z<=3.0. The present invention has the advantage of simple process, and products have the advantages of high yield, high purity and high dispersivity.

Description

A kind of technology of preparing of CNT (carbon nano-tube)

The present invention relates to the preparation of functional materials, a kind of technology of preparing of CNT (carbon nano-tube) is provided especially.

CNT (carbon nano-tube) is the C that continues ₆₀The new texture form of the another kind of carbon of finding the beginning of the nineties is single or multiple lift carbon tube pincers cover afterwards, and interior sky, diameter are the 1-dimention nano carbon structure of several nanometers or tens nanometers.Theoretical and experiment all shows, the 1-dimention nano hollow structure of this uniqueness of carbon has various new physical chemistry and the mechanical properties that are different from the conventional graphite material, as high radially bending resistance and longitudinal tensile strength, metal or compound melt capillary adsorption effect, the most advanced and sophisticated electric microfield emission of nanotube, anisotropic magnetic performance, one dimension conductor or characteristic of semiconductor, therefore be considered to the potential application prospect is arranged, be described as " One-dimensional Quantum line " as structured material, functional materials.Carbon nanotube is that the high explanation of employing Electronic Speculum in 1991 finds that in observing the arc-over product after this arc-over is for preparing the main method of CNT (carbon nano-tube).Its principle is done electrode for adopting graphite, in inert atmospheres such as argon or nitrogen, under the high temperature that electric arc produces, gasify, form carbon nanotube under certain condition in the cathodic discharge product, growth that it is generally acknowledged carbon nanotube is that discharge forms freeization of graphite carbon at the negative electrode one-dimensional growth under electric field and gas atom directive action.SYNTHESIS OF CARBON NANOTUBES BY ELECTRIC ARC METHOD has many shortcomings: (1) complex process; (2) pyroprocess; Arc-over graphite gasification temperature needs to cause the serious sintering of CNT (carbon nano-tube) thus up to 2500～3700 ℃; (3) process instability: once stable arc-over can only continue several seconds, is interrupted discharge and causes the inhomogeneous and carbon particles of carbon nanotube structure to mix; (4) productive rate is low, only is daily output gram level.Main preparation research work at present concentrates on the adjustment and the improvement of electric arc synthetic technology technology, comprises that employing adds evaporation of hydrogen activated carbon gas and stabilization process in the environment nitrogen atmosphere; In Graphite Electrodes, add metal alloy, adopt graphite---iron, graphite--nickel or graphite---cobalt mixed electrods catalytic growth etc.But all to be the electric arc synthesis technique characteristics decision of above-mentioned shortcoming own, can not tackle the problem at its root.The vapour-phase pyrolysis carbonaceous gas of employing such as ethene C are also arranged in the recent period ₂H ₂, benzene C ₆H ₆Deng vapour-phase pyrolysis under catalysis such as metal Fe or Ni, the research report of preparation carbon nanotube.The shortcoming one of this method is that efficient is lower, and technology need add metal catalyst, will inevitably pollution products, also can add inert gas as carrier gas, and total gas pressure requires between 1.0～2.0 normal atmosphere.

The object of the present invention is to provide a kind of technology simple, product yield height, purity height, the preparation method of the carbon nanotube of good dispersity.

The invention provides a kind of technology of preparing of CNT (carbon nano-tube), it is characterized in that: with the metastable carbon silicon of infusibility nitrogen hydrogen SiC _xN _yH _zAmorphous is a solid-phase reactant, wherein 0.39≤x≤1.34,0.39≤y≤1.34,0.5≤z≤3.0; Under nitrogen atmosphere, air pressure is at 0.5～2.0 normal atmosphere; Adopt common pyrolysis way, pyrolysis temperature is 1300～2000 ℃, and the time is 0.5～5 hour, and original position generates CNT (carbon nano-tube).

Also can add inert gas among the present invention as carrier gas, total gas pressure requires between 1.0～2.0 normal atmosphere.Preferable pyrolysis temperature is between 1400～1700 ℃.

Raw material SiC used herein _xN _yH _zMetastable non-crystalline flour can obtain by the method for Chinese patent 94110393.5 " organic silane laser gas phase synthesis of silica-base micro powder ", and concrete preparation process is:

---with the organosilane is the main body reactant, and its structural formula is: (R _a ¹R _b ²Si) ₂NR ³, R wherein _a ¹, R _b ², R ³Be alkyl or hydrogen, a, b are the number of alkyl or hydrogen, a+b=3;

---with hydrogen and/or ammonia is addition reaction gas, and the mol ratio of gas reactant and addition reaction gas is 1: 1～10;

The laser Gaseous of---under following processing condition is synthesized metastable state SiC _xN _yH _zAmorphous,

Laser power density: 500～6000W/cm ²

Reaction pressure: 0.2～1 normal atmosphere;

Reaction general gas flow: 1200～6000cm ³/ min;

Reaction times: 0.6～2.4ms;

Temperature of reaction: 500～1100 ℃.

Adopting simple substance graphite in existing arc process is reactant, because its fusing point is high, saturated vapor pressure is lower, only could evaporate under very high temperature, and this also is to adopt arc process to obtain carbon nanotube to need the very reason place of high-temperature.On the contrary, if adopting common carbon containing organic polymer is that raw material carries out pyrolysis, because carbon gas saturated pressure is too low at a lower temperature, be not enough to take place " Gu gas-" the reaction carbon nano-tube, and when temperature of reaction is higher, (be higher than its decomposition temperature), uncontrollable decomposition (or burning) process will take place, thereby can not obtain carbon nanotube, can only obtain carbon black usually.The present invention adopts the metastable carbide of solid phase pyrolysis infusibility to prepare and why selects the metastable carbon silicon of solid phase nitrogen hydride for use in the new technology of carbon nanotube is reaction raw materials, is because it just can discharge carbon containing micro-molecular gas C under lower Heating temperature _xH _z, this carbon atmosphere is SiC _xN _yH _zUnder high-temperature condition, emit in the Stability Analysis of Structures process, be the controlled dispose procedure of kinetics.Under suitable pyrolysis temperature and phase concentrations condition, carbonaceous gas generates carbon nanotube at the directed one-dimensional growth of nanoparticle surface.Advantage of the present invention is as follows:

1. do not need high temperature discharge, no electric field action, process is very stable, the CNT (carbon nano-tube) even structure of preparation, number of plies narrow distribution range, about 15～20 layers.

2. synthesis temperature is low, does not need the allocatalysis agent, the carbon nanotube good dispersity that makes, purity height.

3. process stabilization is controlled: by choosing that raw material mix is formed, the control of pyrolysis temperature, atmosphere and growth time can be controlled the structure of carbon nanotube.

4. technology is very simple, and carbon nanotube generates in pyrolysis product place " original position " simultaneously, amplifies easily, can become the Perfected process that the mass preparation carbon nanotube is come at the end.

Below by embodiment in detail the present invention is described in detail

Accompanying drawing 1 solid phase pyrolysis synthesizing carbon nanotubes principle schematic;

The transmission electron microscope pattern of accompanying drawing 2 CNT (carbon nano-tube);

The height explanation structure of accompanying drawing 3 carbon nanotubes

Embodiment 1

Raw material adopts metastable amorphous carbon nitrogen hydrogen silica flour, and its chemical constitution is SiN _0.63C _1.0H _1.1By laser Gaseous pyrolysis hexamethyl second silicon amine alkane ((CH ₃) Si) ₂NH) make at 1200 ℃.The 10g raw material powder put into put into the graphite body of heater, system pump down (10 after the BN crucible is added a cover ^-3Torr), charge into 1atm nitrogen, system is airtight, and heating up then is heated to 1400 ℃, is incubated 60 minutes, and the outage stove is chilled to room temperature.

Prepare carbon nanotube in order to the top method, transformation efficiency 5%, diameter 10～25nm, long 0.1～1.0 μ m (Fig. 2).The CNT (carbon nano-tube) that high explanation structure observation makes is interior hollow diameter 1.02～3.28nm, closed end, the CNT (carbon nano-tube) that the concentric graphite linings that the number of plies is 15～20 layers constitutes, characteristic feature such as Fig. 3.

Raw material is formed and pyrolytical condition can be controlled carbon nanotube by changing, and the carbon pipe number of plies is 5～10 layers when being 15 minutes as growth time, when the time extends to 1 hour number of plies and increases to 15～20 layers.

Embodiment 2

When atmosphere is flow state, flow is 200sccm, and pyrolysis temperature is 1900 ℃, when other condition and embodiment 1 are identical, can obtain the result identical with example 1.

Embodiment 3

It is SiN that raw material adopts chemical constitution _0.45C _1.20H _2.0Metastable amorphous carbon nitrogen hydrogen silica flour, other condition is with embodiment 1, can obtain with the same CNT (carbon nano-tube) of example 1, transformation efficiency is 6%.

Claims (5)

1. the technology of preparing of a CNT (carbon nano-tube) is characterized in that: with the metastable carbon silicon of infusibility nitrogen hydrogen SiC _xN _yH _zAmorphous is a solid-phase reactant, wherein 0.39≤x≤1.34,0.39≤y≤1.34,0.5≤z≤3.0; Under nitrogen atmosphere, air pressure is at 0.5～2.0 normal atmosphere; Adopt common pyrolysis way, pyrolysis temperature is 1300～2000 ℃, and the time is 0.5～5 hour, and original position generates CNT (carbon nano-tube).

2. by the technology of preparing of the described CNT (carbon nano-tube) of claim 1, it is characterized in that: also can add inert gas as carrier gas, total gas pressure requires between 1.0～2.0 normal atmosphere.

3. by claim 1, the technology of preparing of 2 described CNT (carbon nano-tube) is characterized in that: preferable pyrolysis temperature is between 1400～1700 ℃.

4. by claim 1, the technology of preparing of 2 described CNT (carbon nano-tube) is characterized in that SiC _xN _yH _zPreparation process be:

---with the organosilane is the main body reactant, and its structural formula is: (R _a ¹R _b ²Si) ₂NR ³, R wherein _a ¹, R _b ², R ³Be alkyl or hydrogen, a, b are the number of alkyl or hydrogen, a+b=3;

---with hydrogen and/or ammonia is addition reaction gas, and the mol ratio of gas reactant and addition reaction gas is 1: 1～10;

The laser Gaseous of---under following processing condition is synthesized metastable state SiC _xN _yH _zAmorphous,

Laser power density: 500～6000W/cm ²

Reaction pressure: 0.2～1 normal atmosphere;

Reaction general gas flow: 1200～6000cm ³/ min;

Reaction times: 0.6～2.4ms;

Temperature of reaction: 500～1100 ℃.

5. by the technology of preparing of the described CNT (carbon nano-tube) of claim 3, it is characterized in that SiC _xN _yH _zPreparation process be:

---with the organosilane is the main body reactant, and its structural formula is: (R _a ¹R _b ²Si) ₂NR ³, R wherein _a ¹, R _b ², R ³Be alkyl or hydrogen, a, b are the number of alkyl or hydrogen, a+b=3;

---with hydrogen and/or ammonia is addition reaction gas, and the mol ratio of gas reactant and addition reaction gas is 1: 1～10;

The laser Gaseous of---under following processing condition is synthesized metastable state SiC _xN _yH _zAmorphous,

Laser power density: 500～6000W/cm ²

Reaction pressure: 0.2～1 normal atmosphere;

Reaction general gas flow: 1200～6000cm ³/ min;

Reaction times: 0.6～2.4ms;

Temperature of reaction: 500～1100 ℃.

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