CN103145129B

CN103145129B - Method for preparing silicon carbide nano-fibre

Info

Publication number: CN103145129B
Application number: CN201310104789.0A
Authority: CN
Inventors: 秦明礼; 储爱民; 曲选辉; 曹知勤; 吴昊阳
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2013-03-28
Filing date: 2013-03-28
Publication date: 2015-04-01
Anticipated expiration: 2033-03-28
Also published as: CN103145129A

Abstract

The invention relates to a method for preparing silicon carbide nano-fibre, which is characterized by being formed by improving a raw material mixing method and raw materials; a uniformly mixed precursor with controllable morphology and size and high reaction activity can be obtained; silicon carbide nano-fibre with high purity, controllable morphology and size and better dispersibility can be synthesized from the precursor through carbon thermal reduction reaction at lower temperature; a silicon source is silica sol; a carbon source is glucose; additives are urea, PAM (Polyacrylamide) and nitric acid; the mol ratio (Si:C) of silica sol to glucose is 1:(4-12); the mol ratio of nitric acid (N) to urea (U) is 1:(0.5-2); and the mass ratio of PAM to silica sol is (0.5-3):1. The silicon source and the carbon source in the precursor are tiny in granularity and uniform to mix; and the method disclosed by the invention is capable of reducing carbon thermal reduction reaction temperature, increasing reaction rate and preparing silicon carbide nano-fibre with good dispersing performance and has the advantages of being good in reaction activity, wide in raw material source, low in cost and production cost and high in yield.

Description

A kind of method preparing SiC nano fiber

Technical field

The invention belongs to ceramic materials preparation technology field, particularly a kind of method preparing SiC nano fiber.

Background technology

Silicon carbide (SiC) has many premium propertiess, as good physical strength, chemical stability, higher heat conduction and conductivity etc., has a wide range of applications in pottery, metal composite, high-abrasive material and catalysis etc.One dimension silicon carbide nano material then causes the great interest of various countries investigator with the physicals such as optical, electrical and mechanical of its uniqueness.As important functional materials, one dimension silicon carbide nano material has huge potential using value at the electronics of high temperature, high frequency, large-power semiconductor device and nanoscale and optoelectronic areas.In addition, because it has very high intensity and toughness, the toughener of pottery, metal and polymeric matrix composite material can be also widely used in.The method preparing one dimension silicon carbide nano material has chemical Vapor deposition process, sol-gel carbothermic method, carbon nanotube template, arc discharge, laser ablation method etc.At present, investigators have applied these methods and have successfully prepared the one dimension silicon carbide nano material of various pattern, and as nano wire, nano belt, nano-cable, nanometer rod etc., its performance and possible applied research are also constantly being carried out.In these preparation methods, carbothermic method is a comparatively easy method, and compared with additive method, SiC nano fiber purity prepared by the method is high, good dispersity, pattern, controlled diameter; Carbothermic method suitability for scale production, is widely applied aborning.Conventional carbon hot reducing method adopts organosilicon source as raw material usually, prepares SiC nano fiber by sol-gel carbothermic reduction.Because the sol-gel method preparation feedback precursor production cycle is long, operating procedure is complicated; In addition, adopt organosilicon source cost high.Therefore, the method remains to be further improved.

Summary of the invention

The object of the invention is to provide a kind of carbothermic method to prepare the novel method of SiC nano fiber, solves long reaction time, operating procedure complexity and high in cost of production problem that traditional sol-gel carbothermic method causes for raw material with organosilicon source.

A kind of method preparing SiC nano fiber, it is characterized in that by improving method for mixing raw materials and raw material composition, conveniently obtain pattern and size is controlled and the Homogeneous phase mixing precursor of high reaction activity, shorten reaction time, reduce preparation cost, make precursor under lower temperature conditions by carbothermic reduction reaction synthesis pattern with size is controlled, high purity and the good SiC nano fiber of dispersiveness.

The present invention is realized by following steps:

1. raw material and proportioning: the silicon source adopted is silicon sol; Carbon source is glucose; Additive is urea, nitric acid, polyacrylamide (PAM).Silicon source and carbon source are according to mol ratio Si:C=1:(4 ~ 12) proportioning; Nitric acid (N) and urea (U) are according to mol ratio N:U=1:(0.5 ~ 2) proportioning; PAM and silicon sol are according to mass ratio (0.5 ~ 3): the proportioning of 1.

2. the preparation of precursor: first silicon sol, glucose, urea, nitric acid, PAM are dissolved in deionized water, get a uniform mixture, heated at 200 ~ 400 DEG C of temperature by mixing solutions, heating rate is 3 ~ 10 DEG C/min, obtains precursor after solution reacts again.In the preparation process of precursor, by the amount of PAM, nitric acid and urea in the heating rate of regulator solution and initial soln, obtain the precursor of different-shape and size.

3. the carbothermic reduction reaction of precursor.Different-shape step 2 obtained and size precursor carbothermic reduction reaction 2 ~ 8h in the flowing argon gas atmosphere of 1300 ~ 1500 DEG C, argon flow amount is 0.5 ~ 2L/min, and temperature rise rate is 5 ~ 20 DEG C/min.In carbothermic reduction process, by by reasonably combined for the precursor of different-shape and size temperature of reaction, gas flow and temperature rise rate, obtain the carbothermic reduction product of different-shape and size.Reduzate obtains high purity and the good SiC nano fiber of dispersiveness after calcining 2h removal carbon residue at 650 DEG C in air.

In precursor of the present invention silicon source and carbon source granularity tiny, mix, reactive behavior is good, can reduce carbothermic reduction reaction temperature, improve speed of reaction, prepare the SiC nano fiber of good dispersion property; Raw material sources is extensive, and cheap, production cost is low, and productive rate is high, the SiC nano fiber stable performance of preparation, pattern and size controlled, production technique is simple, convenient and swift, can realize producing in enormous quantities.

Accompanying drawing explanation

Fig. 1 is the SEM figure of the precursor adding the preparation of different PAM amount:

As shown in Figure 1, PAM consumption is the precursor of 8 grams is the block comparatively loosened, and particle surface has occurred that a large amount of fibrous objects (Fig. 1 a); PAM consumption is the bulk that the precursor powder particle of 12 grams shows as porous, and a large amount of spicule (Fig. 1 b) has appearred in the surface of particle.

Fig. 2 is the XRD figure spectrum of the SiC nanofiber adding the preparation of different PAM amount:

As shown in Figure 2, two kinds of calcinates all show five main diffraction peak 2 θ=35.6, and 41.2,60.2,72.1,75.5 °, (111) of the corresponding β-SiC of difference, (200), (220), (311), (222) crystal face (JCPDS card 29-1129).Another one more low intensive diffraction peak 2 θ=33.6 ° (being designated as SF) are the overlay errors due to diffraction peak, do not find arch peak, show that two products are purer SiC fiber in XRD figure spectrum.

Fig. 3 is the FESEM figure of the SiC nanofiber adding the preparation of different PAM amount:

As shown in Figure 3, adding PAM be product prepared by 8g is 50 ~ 100nm by diameter, and length is that (Fig. 3 a) for the linear macrofiber composition of tens microns.The staple fibre that by diameter, to add PAM be the product prepared of 12g is that the spheroidal particle of about 100nm and diameter are 50 ~ 200nm, length is less than 1 μm forms (Fig. 3 b).

Fig. 4 is the TEM figure of the SiC nanofiber adding the preparation of different PAM amount:

From Fig. 4 a, adding PAM be SiC prepared by 8g is linear macrofiber, and diameter is about 50nm, and (Fig. 3 a) conforms to substantially to scheme the result of observing with FESEM.From Fig. 4 b, interpolation PAM is SiC staple fibre shape prepared by 12g is slightly irregular bar-shaped, and the result (Fig. 3 b) of scheming to observe with FESEM conforms to substantially.The SAED figure of two kinds of SiC fibers is made up of the point diffraction of regular distribution, and these points correspond to the SiC of cubic structure, and showing to add PAM be sample prepared by 8g and 12g is SiC single crystal fiber.

Embodiment

Embodiment 1:

Take glucose 0.1mol, silicon sol 0.1mol, urea 0.1mol, nitric acid 0.2mol, PAM 4g.Above-mentioned various raw material is dissolved in deionized water and obtains mixing solutions.Temperature controllable electric furnace mixing solutions being placed in 300 DEG C heats, and heating rate is 5 DEG C/min, and solution obtains precursor after a series of processes such as experience volatilization, concentrated, bubbling.By precursor 1400 DEG C, temperature rise rate is 5 DEG C/min, argon flow amount reacts 8h under being the condition of 1L/min, obtains reaction product.Product obtains SiC nano fiber through follow-up carbon removal treatment.

Embodiment 2:

Take glucose 0.1mol, silicon sol 0.1mol, urea 0.2mol, nitric acid 0.2mol, PAM 12g.Above-mentioned various raw material is dissolved in deionized water and obtains mixing solutions.Temperature controllable electric furnace mixing solutions being placed in 400 DEG C heats, and heating rate is 8 DEG C/min, and solution obtains precursor after a series of processes such as experience volatilization, concentrated, bubbling.By precursor 1500 DEG C, temperature rise rate is 15 DEG C/min, argon flow amount reacts 4h under being the condition of 1L/min, obtains reaction product.Product obtains SiC nano fiber through follow-up carbon removal treatment.

Embodiment 3:

Take glucose 0.15mol, silicon sol 0.1mol, urea 0.1mol, nitric acid 0.2mol, PAM 8g.Above-mentioned various raw material is dissolved in deionized water and obtains mixing solutions.Temperature controllable electric furnace mixing solutions being placed in 300 DEG C heats, and heating rate is 10 DEG C/min, and solution obtains precursor after a series of processes such as experience volatilization, concentrated, bubbling.By precursor 1300 DEG C, temperature rise rate is 20 DEG C/min, argon flow amount reacts 8h under being the condition of 2L/min, obtains reaction product.Product obtains SiC nano fiber through follow-up carbon removal treatment.

Embodiment 4:

Take glucose 0.1mol, silicon sol 0.1mol, urea 0.15mol, nitric acid 0.2mol, PAM 6g.Above-mentioned various raw material is dissolved in deionized water and obtains mixing solutions.Temperature controllable electric furnace mixing solutions being placed in 200 DEG C heats, and heating rate is 3 DEG C/min, and solution obtains precursor after a series of processes such as experience volatilization, concentrated, bubbling.By precursor 1400 DEG C, temperature rise rate is 10 DEG C/min, argon flow amount reacts 6h under being the condition of 1l/min, obtains reaction product.Product obtains SiC nano fiber through follow-up carbon removal treatment.

Embodiment 5:

Take glucose 0.1mol, silicon sol 0.1mol, urea 0.2mol, nitric acid 0.2mol, PAM 10g.Above-mentioned various raw material is dissolved in deionized water and obtains mixing solutions.Temperature controllable electric furnace mixing solutions being placed in 300 DEG C heats, and heating rate is 8 DEG C/min, and solution obtains precursor after a series of processes such as experience volatilization, concentrated, bubbling.By precursor 1400 DEG C, temperature rise rate is 5 DEG C/min, argon flow amount reacts 4h under being the condition of 1L/min, obtains reaction product.Product obtains SiC nano fiber through follow-up carbon removal treatment.

Embodiment 6:

Take glucose 0.15mol, silicon sol 0.1mol, urea 0.15mol, nitric acid 0.2mol, PAM 8g.Above-mentioned various raw material is dissolved in deionized water and obtains mixing solutions.Temperature controllable electric furnace mixing solutions being placed in 300 DEG C heats, and heating rate is 10 DEG C/min, and solution obtains precursor after a series of processes such as experience volatilization, concentrated, bubbling.By precursor 1500 DEG C, temperature rise rate is 20 DEG C/min, argon flow amount reacts 3h under being the condition of 2L/min, obtains reaction product.Product obtains SiC nano fiber through follow-up carbon removal treatment.

Claims

1. prepare a method for SiC nano fiber, it is characterized in that preparation process is as follows:

A. raw material and proportioning: the silicon source adopted is silicon sol; Carbon source is glucose; Additive is urea, nitric acid, polyacrylamide, and silicon source and carbon source are according to mol ratio Si:C=1:(4 ~ 12) proportioning; The mol ratio of nitric acid and urea is 1:(0.5 ~ 2); Polyacrylamide and silicon sol are according to mass ratio (0.5 ~ 3): the proportioning of 1;

B. the preparation of precursor: first silicon sol, glucose, urea, nitric acid, polyacrylamide are dissolved in deionized water, get a uniform mixture, heated at 200 ~ 400 DEG C of temperature by solution, heating rate is 3 ~ 10 DEG C/min, obtains precursor after solution reacts again; In the preparation process of precursor, by the amount of polyacrylamide, nitric acid and urea in the heating rate of regulator solution and initial soln, obtain the precursor of different-shape and size;

C. the carbothermic reduction reaction of precursor: the different-shape that step b is obtained and the precursor of size carbothermic reduction reaction 2 ~ 8h in the flowing argon gas atmosphere of 1300 ~ 1500 DEG C, argon flow amount is 0.5 ~ 2L/min, and temperature rise rate is 5 ~ 20 DEG C/min; In carbothermic reduction process, by by reasonably combined for the precursor of different-shape and size temperature of reaction, reaction times, gas flow and temperature rise rate, obtain pattern and the controlled carbothermic reduction product of size; Carbothermic reduction product obtains high purity and the good SiC nano fiber of dispersiveness after calcining 2h removal carbon residue at 650 DEG C in air.