CN102557032A

CN102557032A - Preparation method of high-purity silicon carbide nano fibers

Info

Publication number: CN102557032A
Application number: CN2012100624769A
Authority: CN
Inventors: 罗鲲; 李正方
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2012-03-09
Filing date: 2012-03-09
Publication date: 2012-07-11

Abstract

The invention discloses a preparation method of high-purity silicon carbide nano fibers. The method comprises the following steps of: (1) performing hydrophilic surface treatment to a carbon nano tube; (2) enabling the carbon nano tube modified hydrophilically to carry out sol-gel process, so as to prepare uniform mixture of the carbon nano tube and SiO2 gel; and (3) heating the mixture to be 500-700 DEG C and maintaining the temperature for 1-3 hours, raising the temperature to be 1350-1650 DEG C and maintaining the temperature for 1-4 hours, thereby obtaining the high-purity silicon carbide nano fibers. The silicon carbide nano fibers prepared by adopting the method have high purity, simple process and low cost, any catalyst does not need to be introduced during reaction, and batch production is easy to realize.

Description

A kind of preparation method of high-purity nano silicon carbide fiber

Technical field

The present invention relates to a kind of carbon nanotube and sol-gel method silicon-dioxide pyroreaction utilized; The method for preparing the high-purity carborundum nanofiber; It is characterized in that the silicon-dioxide with the sol-gel technology preparation is the silicon source; With the carbon nanotube is carbon source, under argon shield, processes the high-purity carborundum nanofiber through rational heating process.

Background technology

Excellent properties such as silit (SiC) nanofiber has HS, high-modulus, high temperature resistant, anticorrosive, anti-oxidant, low density, resistivity is adjustable; Be mainly used in aspects such as refractory ceramics based composites, metal-base composites, electromagnetic wave absorbent material, in industry such as metallurgy, electronics, weapons, aerospace, extensive use arranged.Utilizing silicon-dioxide and carbon to carry out the pyrocarbon thermal reduction is the domestic method that preparation SiC is gone up in industry.As, glass sand and coke or refinery coke are produced the SiC powder in resistance furnace, also have with resol pyrolysis charcoal to prepare the SiC powder as alternative charcoal source.Compare with crystal form silicon-dioxide; Silica dioxide gel has high reaction activity and high; And the preparation method is easy, and raw material is easy to get, therefore carbon sources such as silica dioxide gel and resol are carried out ground and mixed after; Can under relatively low temperature, carry out carbothermic reduction reaction, obtain the SiC nanofiber.In addition, the halogenide of silicon (gas phase) and hydrocarbon polymer (gas) and a certain amount of hydrogen carry out High Temperature Gas phase reaction (1200-1800 ℃) and also can obtain SiC; And pyrolysis in inert atmosphere such as some precursor such as Polycarbosilane also can obtain the SiC fiber of high-specific surface area.

The present invention proposes a kind of carbon nanotube and sol-gel method SiO of utilizing ₂Carry out pyroreaction, prepare the method for high-purity carborundum nanofiber.The SiO that promptly prepares with sol-gel technology ₂Gel is the silicon source, is carbon source with the carbon nanotube, under argon shield, control through reasonably heating up, acquisition high purity SiC nanofiber (with

Be main).This method is not also appeared in the newspapers at present.

Summary of the invention

The invention provides a kind of novel method of utilizing carbon nanotube and silica dioxide gel to prepare high-purity nano SiC fiber.

Concrete steps are:

(1) the 3-5g carbon nanotube is added in the beaker of 50ml, adds the ultrasonic concussion of 30-40ml zero(ppm) water after 5-15 minute, add the 0.8-1.6g X 2073 again, continue ultrasonic concussion 4-6 hour; Adding distil water is diluted to 500-600ml, carries out spinning with the rotating speed of 10000-12000r/min, removes supernatant; To precipitate with baking oven and take out after 4-8 hour, pulverize, obtain hydrophilic carbon nanotube 75-95 ℃ of oven dry;

(2) with the 50-55ml volume percent be ammoniacal liquor and the mixing of 100ml zero(ppm) water of 25-28%; Add the 160-175ml absolute ethyl alcohol again; The normal temperature lower magnetic force stirred after 3-10 minute; Add the hydrophilic carbon nanotube that 2.8-3.2g step (1) makes, restir 2-5 minute, obtain the homodisperse liquid of carbon nanotube;

(3) in step (2) gained carbon nanotube dispersion liquid, dropwise add the tetraethoxy of 18-22ml, the beginning sol gel reaction continues to stir 40-48 hour, and temperature is controlled between 15-30 ℃, obtains to contain the suspension-s of carbon nanotube and silica dioxide gel; Product takes out after 20-30 hour 75-85 ℃ of oven dry, pulverizes;

(4) get the powder 1-3g that step (3) prepares, put into alumina crucible, be warming up to 500-700 ℃ of insulation 1-3 hour under the argon shield, be warming up to 1350-1650 ℃ again, be incubated 1-4 hour postcooling to normal temperature; The inner product of alumina crucible is the high-purity carborundum nanofiber.

Characteristics of the present invention:

(1) carbon nanotube is carried out surface-treated and can make itself and sol-gel method SiO ₂Uniform mixing helps improving carbon thermal response efficient, improves the productive rate of SiC nano fiber;

(2) to carbon nanotube and sol-gel method SiO ₂The mixture control that reasonably heats up;

(3) can directly receive high purity SiC nanofiber, need not to carry out subsequent disposal;

(4) need not to introduce any catalyzer in the reaction process.

The SiC nano fiber purity of the present invention's preparation is high, technology is simple, cost is low, need not to introduce any catalyzer in the reaction process, is easy to realize producing in batches.

Embodiment

Embodiment:

(1) the 4g carbon nanotube is added in the beaker of 50ml, adds the ultrasonic concussion of 35ml zero(ppm) water after 10 minutes, add the 1.2g X 2073 again, continue ultrasonic concussion 5 hours; Adding distil water is diluted to 550ml, carries out spinning with the rotating speed of 11000r/min, removes supernatant; To precipitate with baking oven and take out after 6 hours, pulverize, obtain hydrophilic carbon nanotube 90 ℃ of oven dry;

(2) with the 50ml volume percent be ammoniacal liquor and the mixing of 100ml zero(ppm) water of 25-28%; Add the 165ml absolute ethyl alcohol again, the normal temperature lower magnetic force stirred after 5 minutes, added the hydrophilic carbon nanotube that 3g step (1) makes; Restir 5 minutes obtains the homodisperse liquid of carbon nanotube;

(3) in step (2) gained carbon nanotube dispersion liquid, dropwise add the tetraethoxy of 20ml, the beginning sol gel reaction continues to stir 48 hours, and temperature is controlled at 30 ℃, obtains to contain the suspension-s of carbon nanotube and silica dioxide gel; Product takes out after 25 hours 85 ℃ of oven dry, pulverizes;

(4) get the powder 1.5g that step (3) prepares, put into alumina crucible, be warming up to 650 ℃ of insulations 2 hours under the argon shield, be warming up to 1500 ℃ again, be incubated 3 hours postcooling to normal temperature; The inner product of alumina crucible is high-purity carborundum nanofiber (β-SiC content＞90%).

Claims

1. the preparation method of a silicon carbide fiber is characterized in that concrete steps are:

(4) get the powder 1-3g that step (3) prepares, put into alumina crucible, be warming up to 500-700 ℃ of insulation 1-3 hour under the argon shield, be warming up to 1350-1650 ℃ again, be incubated 1-4 hour postcooling to normal temperature; The inner product of alumina crucible is silicon carbide fiber.