A kind of preparation method of nano vanadium carbide powder
Technical field
The invention provides a kind of preparation method of nano vanadium carbide powder, belong to nanometer scale ceramics powdered preparation field.
Background technology
Vanadium carbide is a kind of important vanadium alloy additive.It is that vanadium forms the refractoriness carbide with carbon that vanadium is used for Iron And Steel Industry, and these compounds can play precipitation hardening and grain refining in steel.Vanadium carbide can be used in structure iron, tool steel, pipe line steel, reinforcing bar, common engineering steel and the cast iron.
In addition, vanadium carbide is as the ultra-fine cemented carbide grain inhibitor, high-temperature coatings, and in industry, obtained using widely as carbon source diamond synthesis etc.What need in the industrial application is the single vanadium carbide powder of fine size, phase composite, for example when the preparation ultra-fine cemented carbide, the particle diameter of WC powder is less than 200nm, will adopt the HIP sintering technology of high pressure low temperature during sintering, also will add the VC grain growth inhibitor in addition.If adopting powder size is that 2~5 μ m vanadium carbides are as grain growth inhibitor, then can be little owing to the thick VC specific surface area of particle, surface active can be low, atomic migration speed is slow, and be difficult to suppress the grain growth of WC, thereby cause the performance of ultra-fine cemented carbide to be difficult to be further enhanced.Therefore, field such as high-performance ultra-fine cemented carbide presses for nano vanadium carbide powder.
But the method for preparing vanadium carbide powder at present mainly contains two kinds: the one, adopt V
2O
5With carbon black mixing high temperature reduction carborization, the 2nd, the conventional ceramic technique of vapour phase reduction/vanadium carbide.These two kinds of methods all adopt the oxide compound of vanadium, and cost of material is higher, and temperature of reaction is also higher, cause production cost higher.In addition, the reaction product granularity is thicker, generally all between 2~5 μ m, and free carbon content height in the powder, can not satisfy the application of vanadium carbide powder in modern industry.
In addition, people such as Zhou Zongquan were " producing the vanadium carbide experimental study " in 1994, " steel vanadium titanium ", 1994, Vol.15, in the No.1 document, the preparation method of vanadium carbide has been proposed: earlier with the poly ammonium vanadate at loft drier freeze-day with constant temperature 4~8h, join with the good powdered carbon of mill and to mix 15~20min in the tapered rod grinding machine, add dextrin solution again to stir, after compression moulding on the self-control briquetting press, stand-by at 105 ℃ of following freeze-day with constant temperature 4~8h.The piece material that drying is good is packed into and is made by oneself in the shaft furnace, is warmed up to 1200~1550 ℃, and constant temperature 3~9h feeds argon shield simultaneously, and argon flow amount is 0.5~5.5L/min, and naturally cooling is come out of the stove, and obtains the vanadium carbide product.This preparation method's main drawback is the temperature of reaction height, and the reaction times is longer, and production cost is higher.
The preparation method of the nano level superfine vanadium carbide powder that people such as Wu Cheng Yi in 2005 propose in patent CN1569624A is: the ammonium meta-vanadate powder is dissolved in distilled water preparation ammonium metavanadate aqueous solution, this solution is sprayed under 120~130 ℃ of conditions be converted to V then
2O
5Precursor powder is again with V
2O
5Precursor powder roasting in 450~550 ℃ of air makes it to be transformed into exsiccant nano level V
2O
5Microcrystal powder, and then shear and to join carbon, oven dry, mixing and anticipate carbon, carbonization, shearing-crushing, vacuum drying and just can obtain nano vanadium carbide powder.The subject matter that this preparation method exists is that technology is complicated, causes production cost higher.
The prosperous preparation method who waits the people in patent CN1607175A, to propose vanadium carbide powder of 2005 Wu's grace: at first with V
2O
5Be dissolved in the organic acid soln, heat while stirring, obtain the solution of clear in the time of 60~80 ℃, strength of solution is 10%~40%; Then with this powder in protective atmosphere, 500~600 ℃ are carried out roasting, obtain V
2O
3With the free mixed uniformly powder of C of atomic level; Again under 850~1000 ℃, H
2Or H
2/ CH
4Carbonization 40~90 minutes, making powder mean particle sizes is 0.1 micron, grain-size is the ultra-fine vanadium carbide powder of 20~60 nanometers.This method has lot of advantages, as lower temperature of reaction, short reaction times etc.; But also there are some shortcomings, as adopting V
2O
5Be raw material, price is higher, adopts H
2Or H
2/ CH
4Carbonization has increased production cost.
U.S. combinating carbide company begins to produce vanadium carbide as far back as the sixties, issued patents again adopts hydrocarbon to be no more than the gas of 3 carbon atoms subsequently.Is 1060 ℃ under to produce the vanadium carbide that contain vanadium 80%, carbon containing 15%~16% as raw material in (normal pressure) temperature with Vanadium Pentoxide in FLAKES.
The people such as R.K.Sadangi of U.S. Rutger university utilize (spraying drying reduction decomposition gas carburization) prepared granularity be the V of 0.5 μ m
8C
7Powder (referring to R.K.Sadangi, L.E.McCandlish, B.H.Kear, P.Seegopaul.Advancesin powder Metallurgy ﹠amp; Particulate Materials.Part 1. (1998): 9-15).Its technological process is: at first preparation contains the precursor solution of V, carries out spraying drying then, more spray-dired powder is carried out pyrolysis, with the product CH after the pyrolysis
4/ H
2Mixed gas carries out gas carburization.By carbon potential in the atmosphere and oxygen partial pressure are determined process and the kinetics that reaction is carried out.
The subject matter that above-mentioned two kinds of methods exist is that the granularity of the vanadium carbide powder that makes is bigger than normal, can not satisfy the application of vanadium carbide powder in modern industry.
Therefore, for save energy, reduce production costs, be necessary to explore the preparation method of a kind of low cost, the simple nano vanadium carbide powder of technology, so that satisfy the application of vanadium carbide powder better in fields such as ultra-fine cemented carbide, special steel material, high-temperature coatings.
Summary of the invention
The object of the present invention is to provide a kind of preparation method of nano vanadium carbide powder, thereby satisfy the application of vanadium carbide powder in fields such as ultra-fine cemented carbide, special steel material, high-temperature coatings.
Embodiment of the present invention are: with the powdery ammonium vanadate; carbonaceous reducing agent and trace catalyst are raw material; wherein catalyzer is a Calcium Fluoride (Fluorspan); rare earth simple substance; rare earth compound or their mixture; above-mentioned raw materials is dissolved in deionized water or the distilled water according to a certain ratio; and stir; make solution; then with this solution heating; dry; obtain containing the precursor powder of vanadium source and carbon source at last; precursor powder is placed high temperature reaction stove; vacuum; under argon gas or the hydrogen atmosphere protective condition; in 800~950 ℃; carbonization obtains median size<100nm under 30~60min condition, the vanadium carbide powder of even particle size distribution.
Further be that described powdery ammonium vanadate is ammonium meta-vanadate, poly ammonium vanadate or their mixture.
Further be that described carbonaceous reducing agent is nanometer carbon black, nano active charcoal, glucose or sucrose.
Further be that described catalyzer addition is 0.01%~2%.
Further be, described being dissolved in deionized water or the distilled water, temperature is 50 ℃~100 ℃.
Further be, described Heating temperature is 100 ℃~300 ℃ with this solution heating, drying, and the time is 1~2h, and drying temperature is 50 ℃~100 ℃, and the time is 1~5h.
Further be that described high temperature reaction stove is carbon tube furnace, tube furnace, induction furnace, microwave agglomerating furnace, rotary kiln, shaft furnace, grate, pushed bat kiln or tunnel furnace.
Compare with the existing method for preparing vanadium carbide powder, the invention has the advantages that:
(1) abundant raw material, cheap.The present invention is a raw material with ammonium vanadate and carbonaceous reducing agent, and the source is abundant, and is cheap, saves cost.
(2) temperature of reaction is low, and the reaction times is short, save energy.The present invention adopts first and adds Calcium Fluoride (Fluorspan) or rare earth catalyst, greatly reduces temperature of reaction, has shortened the reaction times, can save the energy greatly at preparation nano vanadium carbide powder under 800~950 ℃, 30~60min condition.
(3) technology is simple.The present invention can finish in a carbonization, has avoided ammonium vanadate prereduction is become the suboxide of vanadium, carries out carbonization again, has removed a lot of technologies from, and is easy to operate, is fit to suitability for industrialized production.
(4) composition is single, epigranular, tiny.Vanadium carbide powder granularity<100nm that reaction generates, particle size distribution range is narrower, and foreign matter content is few.
Therefore can satisfy the application of vanadium carbide powder in fields such as ultra-fine cemented carbide, special steel material, high-temperature coatings.
Embodiment
Embodiment 1:
Catalyzer (CaF with 7.2g powdery ammonium meta-vanadate, 2.8g nanometer carbon black and 0.01%~2%
2, LaCl
3Or CeCl
3) be dissolved in the 50ml deionized water (50 ℃~100 ℃), obtain the solution that mixes after the stirring, solution is placed loft drier, heat 1~2h under 100~300 ℃ of conditions, dry 1~5h under 50~100 ℃ of conditions obtains containing the precursor powder of vanadium source and carbon source at last.Precursor powder is placed high temperature reaction stove, and under vacuum condition, insulation 30~60min in the time of 600 ℃ under 800~950 ℃, 30~60min condition, makes the nano vanadium carbide powder of median size<100nm, even particle size distribution.
Embodiment 2:
Catalyzer (CaF with 7.2g powdery ammonium meta-vanadate, 2.8g nanometer carbon black and 0.01%~2%
2, YCl
3Or NdCl
3) be dissolved in the 50ml distilled water (50 ℃~100 ℃), obtain the solution that mixes after the stirring, solution is placed loft drier, heat 1~2h under 100~300 ℃ of conditions, dry 1~5h under 50~100 ℃ of conditions obtains containing the precursor powder of vanadium source and carbon source at last.Precursor powder is placed high temperature reaction stove, and under argon gas or hydrogen shield condition, insulation 30~60min in the time of 600 ℃ under 800~950 ℃, 30~60min condition, makes the nano vanadium carbide powder of median size<100nm, even particle size distribution.
Embodiment 3:.
Catalyzer (CaF with 6.4g powdery ammonium meta-vanadate, 10.0g powdery glucose and 0.01%~2%
2, LaCl
3Or CeCl
3) be dissolved in the 50ml deionized water (50 ℃~100 ℃), obtain the solution that mixes after the stirring, solution is placed loft drier, heat 1~2h under 100~300 ℃ of conditions, dry 1~5h under 50~100 ℃ of conditions obtains containing the precursor powder of vanadium source and carbon source at last.Precursor powder is placed high temperature reaction stove, and under vacuum condition, insulation 30~60min in the time of 600 ℃ under 800~900 ℃, 30~60min condition, makes the nano vanadium carbide powder of median size<100nm, even particle size distribution.
Embodiment 4:
Catalyzer (CaF with 6.4g powdery ammonium meta-vanadate, 10.0g powdery glucose and 0.01%~2%
2, YCl
3Or NdCl
3) be dissolved in the 50ml distilled water (50 ℃~100 ℃), obtain the solution that mixes after the stirring, solution is placed loft drier, heat 1~2h under 100~300 ℃ of conditions, dry 1~5h under 50~100 ℃ of conditions obtains containing the precursor powder of vanadium source and carbon source at last.Precursor powder is placed high temperature reaction stove, and under argon gas or hydrogen shield condition, insulation 30~60min in the time of 600 ℃ under 800~900 ℃, 30~60min condition, makes the nano vanadium carbide powder of median size<100nm, even particle size distribution.