CN101804981A - Method for preparing hollow silicon carbide nano material - Google Patents

Abstract

The invention relates to a method for preparing hollow silicon carbide nano material. Phenolic resin is dissolved in anhydrous ethanol, nitrate is added and stirred until the nitrate is dissolved, dry product is obtained after the natural volatilization of the ethanol and drying, and is ground into powder, the dry powder is added into sodium silicate, and is constantly stirred to form gel, and the gel is then dried, so that xerogel is obtained; under the argon atmosphere, the xerogel is heated to 1200 DEG C to 1400 DEG C, reacts under the constant temperature for 3 to 20 hours, and is naturally cooled to the room temperature, so that primary reaction product is obtained; the primary reaction product is oxidated in the air, unreacted carbon is removed, and the primary reaction product is then washed by mixed acid, and is finally washed by water, filtered and dried, so that hollow silicon carbide particles and nano tubes are obtained. The invention has the advantages of simple technique, low cost, high product purity and mass production.

Description

A kind of preparation method of hollow structure silicon carbide nano material

Technical field

The present invention relates to the preparation method of a kind of silicon carbide hollow particle and nanotube, relate in particular to a kind of method by collosol and gel and carbothermic reduction technology synthesizing silicon carbide hollow particle and Sic nanotube.

Background technology

Since carbon nanotube in 1991 is found, because its particular structure feature and excellent mechanics, electricity, optical characteristics, caused countries in the world scientists' extensive concern, the researchist also constantly explores the synthetic method and the preparation technology of this one dimension tubular material.Silicon carbide nano material is except having characteristics such as high rigidity, anti-oxidant, resistance to chemical attack, thermal conductivity height, again since characteristics such as its unique light, electricity and machinery can be widely used in high temperature, high frequency, less energy-consumption and the powerful device.Sic nanotube has except that most of characteristic of carbon nanotube and application, also may potential nano electron device, catalysis, absorption, energy storage, stealthy, the prepare composite that is applied under the high-temperature severe environment.Therefore, it is very important to develop a kind of technology of low-cost mass preparation hollow structure silicon carbide nano material.

At present, the preparation method of silicon carbide hollow ball mainly contains the template synthesis method, the preparation method of Sic nanotube mainly contains carbon nanotube chemical conversion method, template etc., chemical Vapor deposition process also can be prepared Sic nanotube, but selects for use the document of collosol and gel and the synthetic hollow structure silicon carbide nano material of carbothermic method to yet there are no report.People such as Liu Zhen-Yu are that template and silicon monoxide gas pass through gas-solid reaction synthesizing silicon carbide hollow ball [referring to J.Phys.Chem.C, 111,12517 (2007)] with the carbon ball.People such as H.H.Nersisyan adopt silica flour and carbon black as raw material, and Potcrate and MAGNESIUM METAL are as exothermic additive, by combustion method synthesizing silicon carbide hollow microsphere [referring to Microporous Mesoporous Mater, 117,368 (2009)].It is template that people such as Sun Xu-Hui adopt multi-walled carbon nano-tubes, reacts many walls SiC nanotube [referring to J.Am.Chem.Soc., 124,14464 (2002)] of preparing the about 0.35-0.45nm of interlamellar spacing in 40 minutes with the SiO powder at 1250 ℃.It is template that people such as T.Taguchi adopt carbon nanotube, synthesizes single-phase Sic nanotube [referring to Physica E, 28,431 (2005)] with the Si powder in 100 hours 1200 ℃ of reactions.Chinese patent (Granted publication number: CN 100515942C) disclose and adopt template to prepare the method for high-ratio surface silicon carbide nano tube; select for use porous alumina to be immersed in the mixing solutions of hydrogen methyl-silicone oil and vinyl polysiloxane as template; above-mentioned alumina formwork was placed 1-10 hour under 50-600 ℃ of temperature in retort furnace; remove the presoma that alumina formwork obtains the polysiloxane nanotube with acid; again presoma is placed high temperature process furnances speed with 2-10 ℃/min under protection of inert gas to be warmed up to 1000-1700 ℃, obtained Sic nanotube then in constant temperature 0.5-10 hour.Chinese patent (Granted publication number: CN 100424011C) disclose a kind of chemical gas-phase deposition process for preparing of Sic nanotube, it is substrate that this method is chosen pure graphite flake, with iron, the organometallics of cobalt or nickel is a catalyzer, organic compounds containing sulfur is a promotor, purified graphite flake substrate put in the catalyst solution soaked at least 24 hours, taking-up is dried naturally, carry out chemical vapour deposition then, the source of the gas compound is for containing Si-C key and gasifiable low-molecular-weight organic compound, carrier gas is nitrogen or hydrogen or ammonia or at least two kinds gas mixture wherein, the mol ratio of carrier gas/source of the gas compound is 4.5-7.0, the vapour deposition temperature is 800-1100 ℃, depositing time 0.8-1.5 hour, pickling was carried out purification process and can be got Sic nanotube again.

The employing carbon nanotube chemical conversion method of announcing, template synthesis method etc. prepare silicon carbide hollow ball and nanotubes at present, the shape of institute's preparing silicon carbide, size and the dispersed factors such as shape, size and dispersiveness thereof that depend on template thereof.In addition, complex process equipment, raw material template cost height, reaction process is restive, be difficult for realizing scale operation, so these technologies of preparing is subjected to certain limitation in application process.

Summary of the invention

The method of the silicon carbide nano material that the object of the present invention is to provide that a kind of technology is simple, with low cost, product purity is high and can the mass preparation hollow structure.

The present invention realizes by following method:

(1), the resol of 1 weight part is dissolved in the dehydrated alcohol of 1-6 weight part, add the nitrate of 0.01-1 weight part, stir and make it dissolving, treat that ethanol volatilized afterwards naturally at 70-100 ℃ of dry 6-48 hour, obtained desciccate;

(2), desciccate is ground into powder below 20 orders, the desciccate powder that takes by weighing 1 weight part then joins in the water glass of 2-5 weight part, is forming gel under constantly stirring; Or the desciccate powder that takes by weighing 1 weight part joins in the water glass of 6-10 weight part, adds the 1-20wt% solidifying agent of water glass amount simultaneously, forming gel under constantly stirring, and with gel under 60-110 ℃ of condition dry 6-48 hour, obtains xerogel again;

(3), under argon gas atmosphere, xerogel is warming up to 1200-1400 ℃, treat isothermal reaction 3-20 hour after, naturally cool to room temperature, obtain the primary reaction product;

(4), with the primary reaction product under 600-800 ℃, in the air oxidation 1-5 hour, remove unreacted carbon, it is 1 with volume ratio again: the nitration mixture washing of the hydrochloric acid of 1-5 and hydrofluoric acid, nitric acid and hydrofluoric acid 12-48 hour, after washing, filter, oven dry, can obtain silicon carbide hollow particle and nanotube.

Characteristics of the present invention are to adopt a kind of simple collosol and gel and carbothermic reduction technology, prepare silicon carbide hollow nano particle and Sic nanotube.In this technology, resol and water glass are raw material, and nitrate is catalyzer, and raw material sources are abundant and with low cost, operating procedure is simple, production cost is low, temperature of reaction is lower, product purity is high, easy realization of large-scale production.

Description of drawings

Fig. 1: the XRD spectra of the relevant embodiment product of the present invention;

Fig. 2: the TEM photo of the relevant embodiment product of the present invention.

As shown in the figure, in the XRD spectra of Fig. 12 θ of five main diffraction peaks respectively at 35.6 °, 41.5 °, 60.0 °, 71.8 °, 75.5 °, corresponding (111) of cubic β-SiC, (200), (220), (311) and (222) crystal face.Among Fig. 21 is silicon carbide hollow nano particle, and 2 is Sic nanotube.

Embodiment 1

1, takes by weighing 6 gram resol, be dissolved in 12 milliliters of dehydrated alcohols, add 0.25 gram iron nitrate then, stir and to make it dissolving, treat that ethanol volatilization back was 70 ℃ of dryings 36 hours.

2, desciccate is ground, obtain 20 purpose powders, join then in the service water glass of 13 grams, constantly forming gel under the stirring action, the gained gel was 60 ℃ of dryings 30 hours.

3, xerogel is put into tube type high-temperature furnace, under argon gas atmosphere, be warming up to 1200 ℃, isothermal reaction naturally cooled to room temperature after 10 hours.

4, gained reaction product oxidation 2 hours in 800 ℃ of air is that 1: 1.5 the hydrochloric acid and the mixing acid of hydrofluoric acid soaked 12 hours with volume ratio again, after washing, filter, oven dry, can get silicon carbide hollow nano particle and nanotube.

Embodiment 2

1, takes by weighing 10 gram resol, be dissolved in 25 milliliters of dehydrated alcohols, add 2 gram nickelous nitrates then, stir and to make it dissolving, treat that ethanol volatilization back was 80 ℃ of dryings 24 hours.

2, desciccate is ground, obtain 50 purpose powders, join then in the service water glass of 35 grams, constantly forming gel under the stirring action, the gained gel was 70 ℃ of dryings 24 hours.

3, xerogel is put into tube type high-temperature furnace, under argon gas atmosphere, be warming up to 1250 ℃, isothermal reaction naturally cooled to room temperature after 8 hours.

4, gained reaction product oxidation 5 hours in 600 ℃ of air is that 1: 2 the nitric acid and the mixing acid of hydrofluoric acid soaked 15 hours with volume ratio again, after washing, filter, oven dry, can get silicon carbide hollow nano particle and nanotube.

Embodiment 3

1, takes by weighing 15 gram resol, be dissolved in 55 milliliters of dehydrated alcohols, add 9 gram Xiao Suangus then, stir and to make it dissolving, treat that ethanol volatilization back was 90 ℃ of dryings 10 hours.

2, desciccate is ground, obtain 80 purpose powders, join then in the service water glass of 90 grams, constantly forming gel under the stirring action, the gained gel was 80 ℃ of dryings 24 hours.

3, xerogel is put into tube type high-temperature furnace, under argon gas atmosphere, be warming up to 1300 ℃, isothermal reaction naturally cooled to room temperature after 7 hours.

4, gained reaction product oxidation 3 hours in 700 ℃ of air is that 1: 3 the hydrochloric acid and the mixing acid of hydrofluoric acid soaked 20 hours with volume ratio again, after washing, filter, oven dry, can get silicon carbide hollow nano particle and nanotube.

Embodiment 4

1, takes by weighing 20 gram resol, be dissolved in 100 milliliters of dehydrated alcohols, add 8 gram iron nitrates then, stir and to make it dissolving, treat that ethanol volatilization back was 100 ℃ of dryings 6 hours.

2, desciccate is ground, obtain 100 purpose powders, join then in the service water glass of 170 grams, constantly adding 8 gram phosphoric acid under the stirring action, form gel, the gained gel was 90 ℃ of dryings 12 hours.

3, xerogel is put into tube type high-temperature furnace, under argon gas atmosphere, be warming up to 1300 ℃, isothermal reaction naturally cooled to room temperature after 10 hours.

4, gained reaction product oxidation 3 hours in 800 ℃ of air is that 1: 4 the nitric acid and the mixing acid of hydrofluoric acid soaked 30 hours with volume ratio again, after washing, filter, oven dry, can get silicon carbide hollow nano particle and nanotube.

Embodiment 5

1, takes by weighing 30 gram resol, be dissolved in 120 milliliters of dehydrated alcohols, add 2 gram nickelous nitrates then, stir and to make it dissolving, treat that ethanol volatilization back was 80 ℃ of dryings 24 hours.

2, desciccate is ground, obtain 200 purpose powders, join then in the service water glass of 250 grams, constantly adding 38 gram Sodium Silicofluorides under the stirring action, form gel, the gained gel was 100 ℃ of dryings 10 hours.

3, xerogel is put into tube type high-temperature furnace, under argon gas atmosphere, be warming up to 1350 ℃, isothermal reaction naturally cooled to room temperature after 7 hours.

4, gained reaction product oxidation 4 hours in 700 ℃ of air is that 1: 5 the hydrochloric acid and the mixing acid of hydrofluoric acid soaked 36 hours with volume ratio again, after washing, filter, oven dry, can get silicon carbide hollow nano particle and nanotube.

Claims (1)

1. the preparation method of a hollow structure silicon carbide nano material is characterized in that comprising the steps:

(1), the resol of 1 weight part is dissolved in the dehydrated alcohol of 1-6 weight part, add the nitrate of 0.01-1 weight part, stir and make it dissolving, treat that ethanol volatilized afterwards naturally at 70-100 ℃ of dry 6-48 hour, obtained desciccate;

(2), desciccate is ground into powder below 20 orders, the desciccate powder that takes by weighing 1 weight part then joins in the water glass of 2-5 weight part, is forming gel under constantly stirring; Or the desciccate powder that takes by weighing 1 weight part joins in the water glass of 6-10 weight part, adds the 1-20wt% solidifying agent of water glass amount simultaneously, forming gel under constantly stirring, and with gel under 60-110 ℃ of condition dry 6-48 hour, obtains xerogel again;

(3), under argon gas atmosphere, xerogel is warming up to 1200-1400 ℃, treat isothermal reaction 3-20 hour after, naturally cool to room temperature, obtain the primary reaction product;

(4), with the primary reaction product under 600-800 ℃, in the air oxidation 1-5 hour, remove unreacted carbon, it is 1 with volume ratio again: the nitration mixture washing of the hydrochloric acid of 1-5 and hydrofluoric acid, nitric acid and hydrofluoric acid 12-48 hour, after washing, filter, oven dry, can obtain silicon carbide hollow particle and nanotube.

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