Method for preparing nano tungsten-based powder material by doping yttrium oxide in liquid-liquid manner
Technical Field
The invention belongs to the technical field of powder metallurgy, and particularly relates to a method for preparing a nano tungsten-based powder material by doping yttrium oxide in liquid.
Background
The melting point of the metal tungsten is higher than 3410 ℃, the metal tungsten is located at the head of all metals, and the high-temperature performance is excellent. The tungsten is determined to be the best material used under the conditions of high temperature and ultrahigh temperature, so that the tungsten can be widely applied to the fields of national defense and military industry, aerospace and aviation, electronic information industry, energy, metallurgy and the like. The production of cemented carbide is a major use of metallic tungsten, about 60% of which is used to produce tungsten carbide based cemented carbides. With the continuous development of electronic information technology and modern production, higher requirements on the performance, precision and service life of the hard alloy are provided. Research shows that the comprehensive performance of the alloy can be obviously improved by refining the grains and adding a proper amount of rare earth elements, and the requirements of IT industry, electronic technology, medical appliances and other precision manufacturing industries can be met.
At present, most of rare earth elements are added by mixing rare earth oxide and hard alloy powder after proportioning, and the solid-solid phase mixing cannot achieve complete mixing like two fluids, and only has integral uniformity but no local uniformity. This leads to inconsistent properties of the sintered cemented carbide at each location, which results in a reduction in the overall properties of the alloy.
The invention patent with application publication number CN103173641A discloses a preparation method of a nano yttrium oxide dispersion strengthening tungsten alloy, which adopts a mechanical ball milling mode to mix yttrium nitrate and ammonium paratungstate, is easy to introduce other impurities, and is difficult to ensure the service life of the alloy. This patent, step 3, is calcined in an air atmosphere in order to decompose ammonium paratungstate into tungsten trioxide without producing purple tungsten. And the patent prepares an alloy, unlike the nano tungsten powder herein.
The invention patent with application publication number CN107282938A discloses a rare earth doped tungsten powder and a preparation method thereof, the tungsten powder prepared by the method is uniform, no impurity is introduced, and high-quality tungsten powder is obtained to a certain extent, but the yield of the precursor powder prepared by the hydrothermal reaction is low, the whole process is relatively complex, and the cost is high.
The invention patent of application publication No. CN106564927A discloses a preparation method of superfine yttrium oxide doped tungsten composite precursor powder, the method achieves the purpose of dispersion by adding a surfactant into the precursor through a chemical method, and the technical process is relatively complex; in addition, the added surfactant (such as sodium dodecyl sulfate and the like) is difficult to completely remove, and the existence of sodium in the powder can reduce the performance of the alloy produced subsequently.
Reportedly, when tungsten powder prepared by hydrogen reduction of a purple tungsten raw material is adopted, the tungsten powder with complete crystallization and dispersed particles can be obtained without adding a surfactant. The shape of the product tungsten powder has a genetic relationship with the raw material purple tungsten, and the thinner the diameter and the larger the length-diameter ratio of the purple tungsten, the thinner the granularity of the obtained tungsten powder. The invention patent with application publication number CN103570020A discloses a submicron narrow particle size distribution tungsten powder and tungsten carbide powder and a preparation method thereof, although the tungsten powder goes through the purple tungsten stage, the method cannot regulate the rod diameter of the purple tungsten, and the prepared tungsten powder has a relatively large particle size of 0.29 micron. Therefore, a new method for preparing rare earth-doped tungsten powder is required to be developed.
Disclosure of Invention
The invention aims to provide a method for preparing a nano tungsten-based powder material by liquid-liquid doping yttrium oxide. The shape and size of the nano tungsten powder are controlled by regulating and controlling the diameter of the purple tungsten rod by the yttrium oxide with different contents. The method has simple and feasible process, and the prepared W-Y2O3The powder has fine particlesSmall size, good dispersibility, uniform distribution of yttrium oxide, narrow particle size distribution and the like.
In order to solve the technical problems, the technical scheme adopted by the invention is that the method for preparing the nano tungsten-based powder material by doping yttrium oxide in liquid is carried out according to the following steps:
step S1, dissolving the weighed and proportioned yttrium salt and ammonium metatungstate in distilled water to form uniform, colorless and transparent clear solution;
step S2, drying the obtained clear solution to obtain white solid powder;
step S3, the white solid powder is slightly reduced to obtain purple tungsten powder WO2.72;
Step S4, the purple tungsten powder WO2.72Further hydrogen reduction is carried out to obtain nano tungsten-based powder, namely W-Y2O3And (3) nano powder.
Further, in step S1, the yttrium salt is any one of water-soluble yttrium nitrate, yttrium sulfate, or yttrium chloride.
Further, in the step S1, the mass ratio of the yttrium salt to the ammonium metatungstate is (1.27-7.78): (100-1000).
Further, in the step S2, the clear solution is dried in a spray dryer.
Further, in step S2, the drying conditions in the spray dryer are as follows: the temperature of an air inlet is 180-250 ℃, and the liquid inlet speed is 1-10L/h.
Further, in the step S3, the white solid powder is placed in a tube furnace for light reduction.
Further, in the step S3, the mild reduction temperature is 615-800 ℃, and the heat preservation time is 30-200 min.
Further, in the step S4, the hydrogen reduction temperature is 800-1000 ℃, and the temperature is maintained for 30-120 min.
The invention has the beneficial effects that:
(1) the rare earth yttrium oxide is doped into the tungsten-based material in a liquid-liquid mixing mode to regulate and control the rod diameter of the purple tungsten, so that the material is uniform in phase distribution and stable in overall performance.
(2) The method comprises the steps of firstly preparing high-activity purple tungsten by a staged reduction method, then reducing the purple tungsten into tungsten powder, and regulating the morphology of purple tungsten particles by utilizing rare earth yttrium oxide so as to realize the controllable preparation of the tungsten powder. The method has simple process, and the W-Y is finally obtained2O3The powder particles have good dispersibility, fine particle size, uniform element distribution and narrow particle size distribution, and are beneficial to improving the performance of the final tungsten product. The method has high market value and economic value and good industrial prospect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is an SEM image of a slightly reduced product of example 6.
FIG. 2 is an SEM image of the hydrogen reduction product of example 6.
Figure 3 is the XRD analysis of the hydrogen reduction product of example 6.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The method for preparing the nano tungsten-based powder material by doping yttrium oxide in liquid and liquid comprises the following steps:
and step S1, dissolving the weighed and proportioned yttrium salt and ammonium metatungstate in distilled water to form a uniform, colorless and transparent clear solution.
Wherein, the yttrium salt is any one of water-soluble yttrium nitrate, yttrium sulfate or yttrium chloride; i.e. the formed clear solutionThe liquid is AMT-Y (NO)3)3、AMT-Y2(SO4)3Or AMT-YCl3The solution was mixed.
Ammonium metatungstate and yttrium salt are referenced to final Y2O3The mass fraction of the nano tungsten-based powder is 0.1-3 wt.%. Specifically, the mass ratio of yttrium salt to ammonium metatungstate is: (1.27-7.78): (100-1000) of the total weight of the composition,
the concentration of the prepared clear solution affects the drying efficiency and the wall thickness of the dried spheres, and the parameters of different types of dryers are different, and can be adjusted by a person skilled in the art in a routine manner.
Step S2, the resulting clear solution was dried in a spray dryer to give a white solid powder.
Wherein the spray drying condition is that the temperature of an air inlet is 180-250 ℃, and the liquid inlet speed is 1-10L/h. The drying time is mainly controlled by the liquid inlet speed, the liquid inlet speed ranges of different types of dryers are different, and the drying time can be adjusted correspondingly according to the liquid inlet speed by a person skilled in the art.
Step S3, placing the white solid powder in a tube furnace for mild reduction to obtain purple tungsten powder WO2.72。
Wherein the mild reduction temperature is 615-800 ℃, and the heat preservation time is 30-200 min.
Step S4, further hydrogen reducing the purple tungsten powder to obtain nano tungsten-based powder, namely W-Y2O3And (3) nano powder.
Wherein the hydrogen reduction temperature is 800-1000 ℃, and the temperature is kept for 30-120 min.
The purpose of using the water-soluble yttrium salt and the tungsten salt in the step S1 is to mix tungsten and yttrium at a molecular level by liquid-liquid mixing, so that the prepared tungsten-based material has stable overall performance.
Calculating the mixture ratio of the raw materials of ammonium metatungstate and soluble yttrium salt according to the molar ratio of tungsten to yttrium, and adding Y2O3The mass fraction of (B) is controlled in the range of 0.1 to 3 wt.%. The addition of the rare earth yttrium oxide is beneficial to forming more purple tungsten crystal nuclei in the initial stage of mild reduction, so that the prepared purple tungsten has larger length-diameter ratio and smaller diameter. The other partyFlour, small amount of Y2O3Dislocations generated uniformly distributed inside the W particles may improve the strength and ductility of the finally obtained alloy, but the excess Y2O3But can lead to the reduction of the comprehensive performance of the alloy.
And S2, the temperature of an air inlet of spray drying is 180-250 ℃, and the liquid inlet speed is 1-10L/h. The temperature of the air inlet is too low, so that the solvent cannot be completely evaporated to cause the wall sticking phenomenon in order to reach the boiling point of the solution; too high an inlet temperature increases energy consumption cost and causes waste of resources. The liquid inlet speed is too low, the efficiency is low, and the time cost is increased; and the liquid inlet speed is too high, the diameter of the fog drops is large, the moisture content is too high, wall adhesion is easy to cause, and the powder yield is reduced.
The purpose of the mild reduction of step S3 is to obtain highly active purple tungsten. The purple tungsten has a unique needle-shaped or rod-shaped crystal morphological structure, which is beneficial to the entry of hydrogen and the escape of water vapor in the hydrogen reduction process, so that the reaction starts not only from the active center on the surface of the powder particles, but also from the interior of the powder particles. Therefore, the reduction speed of the purple tungsten hydrogen is high, water vapor rapidly escapes to inhibit tungsten particles from growing up through volatilization-deposition, and the obtained tungsten powder is fine in particle size and narrow in distribution. The mild reduction temperature range is selected from 615-800 ℃ according to the following criteria: when the temperature is lower than 615 ℃, the tungsten oxide is reduced without WO calculated by a tungsten oxide reduction thermodynamic equilibrium diagram3→WO2.72In the process, the target product purple tungsten cannot be obtained; in addition, when the temperature is too high, the powder particles are easily coarsened and excessively reduced.
Step S4, the hydrogen reduction temperature is 800-; the crystal grains are coarsened due to overhigh temperature, and the proper temperature is favorable for preparing the tungsten powder with small grain diameter.
Example 1
A liquid-liquid yttrium oxide-doped nano tungsten-based powder material comprises the following components in percentage by weight: 0.1% of yttrium oxide, and the balance being W. The preparation method comprises the following steps:
step S1, weighing yttrium nitrate and ammonium metatungstate according to the mass ratio of 2.52:1000, and dissolving into distilled water to obtainHomogeneous, colorless transparent AMT-Y (NO)3)3Mixing the solution;
step S2, carrying out spray drying on the mixed solution, wherein the temperature of a spray drying air inlet is 180 ℃, and the liquid inlet speed is 1L/h, so as to obtain precursor powder;
s3, slightly reducing the precursor powder at 615 ℃ for 200min to obtain the purple tungsten with the average rod diameter of 100 nm; then reducing with hydrogen at 800 deg.C for 120min to obtain W-0.1Y with average particle diameter of 114nm2O3And (3) nano powder.
Example 2
A liquid-liquid yttrium oxide-doped nano tungsten-based powder material comprises the following components in percentage by weight: 0.6% of yttrium oxide, and the balance being W. The preparation method comprises the following steps:
step S1, weighing yttrium chloride and ammonium metatungstate according to the mass ratio of 7.75:1000, and dissolving into distilled water to obtain uniform, colorless and transparent AMT-YCl3Mixing the solution;
step S2, carrying out spray drying on the mixed solution, wherein the temperature of a spray drying air inlet is 200 ℃, and the liquid inlet speed is 3L/h, so as to obtain precursor powder;
step S3, slightly reducing the precursor powder at 700 ℃ for 50min to obtain the purple tungsten with the average rod diameter of 65 nm; then reducing with hydrogen at 900 deg.C for 60min to obtain W-0.6Y with average particle diameter of 80nm2O3And (3) nano powder.
Example 3
A liquid-liquid yttrium oxide-doped nano tungsten-based powder material comprises the following components in percentage by weight: 1.5% of yttrium oxide, and the balance being W. The preparation method comprises the following steps:
step S1, weighing yttrium nitrate and ammonium metatungstate according to the mass ratio of 3.83:100, and dissolving into distilled water to obtain uniform, colorless and transparent AMT-Y (NO)3)3Mixing the solution;
step S2, carrying out spray drying on the mixed solution, wherein the temperature of a spray drying air inlet is 215 ℃, and the liquid inlet speed is 8L/h, so as to obtain precursor powder;
step S3, slightly reducing the precursor powder at 800 ℃ for 30min to obtain the purple tungsten with the average rod diameter of 120 nm; then at 10Reducing with hydrogen at 00 deg.C for 120min to obtain W-1.5Y with average particle diameter of 160nm2O3And (3) nano powder.
Example 4
A liquid-liquid yttrium oxide-doped nano tungsten-based powder material comprises the following components in percentage by weight: 2% of yttrium oxide, and the balance being W. The preparation method comprises the following steps:
step S1, weighing yttrium sulfate and ammonium metatungstate according to the mass ratio of 3.12:100, and dissolving into distilled water to obtain uniform, colorless and transparent AMT-Y2(SO4)3Mixing the solution;
step S2, carrying out spray drying on the mixed solution, wherein the temperature of a spray drying air inlet is 230 ℃, and the liquid inlet speed is 5L/h, so as to obtain precursor powder;
step S3, slightly reducing the precursor powder at 650 ℃ for 100min to obtain the purple tungsten with the average rod diameter of 80 nm; then reducing with hydrogen at 750 deg.C for 90min to obtain W-2Y with average particle diameter of 95nm2O3And (3) nano powder.
Example 5
A liquid-liquid yttrium oxide-doped nano tungsten-based powder material comprises the following components in percentage by weight: 3% of yttrium oxide, and the balance being W. The preparation method comprises the following steps:
step S1, weighing yttrium nitrate and ammonium metatungstate according to the mass ratio of 7.78:100, and dissolving into distilled water to obtain uniform, colorless and transparent AMT-Y (NO)3)3Mixing the solution;
step S2, carrying out spray drying on the mixed solution, wherein the temperature of a spray drying air inlet is 250 ℃, and the liquid inlet speed is 10L/h, so as to obtain precursor powder;
step S3, slightly reducing the precursor powder at 700 ℃ for 30min to obtain the purple tungsten with the average rod diameter of 90 nm; then reducing with hydrogen at 850 deg.C for 75min to obtain W-3Y with average particle diameter of 105nm2O3And (3) nano powder.
Example 6
A liquid-liquid yttrium oxide-doped nano tungsten-based powder material comprises the following components in percentage by weight: 1% of yttrium oxide, and the balance being W. The preparation method comprises the following steps:
step S1, weighing yttrium nitrate and ammonium metatungstate according to the mass ratio of 2.54:100, and dissolving into distilled water to obtain uniform, colorless and transparent AMT-Y (NO)3)3Mixing the solution;
step S2, carrying out spray drying on the mixed solution, wherein the temperature of a spray drying air inlet is 210 ℃, and the liquid inlet speed is 2L/h, so as to obtain precursor powder;
s3, slightly reducing the precursor powder at 615 ℃ for 50min to obtain the purple tungsten with the average rod diameter of 60 nm; then reducing with hydrogen at 800 deg.C for 30min to obtain W-1Y with average particle diameter of 70nm2O3And (3) nano powder.
Example 7
A liquid-liquid yttrium oxide-doped nano tungsten-based powder material comprises the following components in percentage by weight: 0.5% of yttrium oxide, and the balance being W. The preparation method comprises the following steps:
step S1, weighing yttrium sulfate and ammonium metatungstate according to the mass ratio of 7.69:1000, and dissolving into distilled water to obtain uniform, colorless and transparent AMT-Y2(SO4)3Mixing the solution;
step S2, carrying out spray drying on the mixed solution, wherein the temperature of a spray drying air inlet is 230 ℃, and the liquid inlet speed is 5L/h, so as to obtain precursor powder;
step S3, slightly reducing the precursor powder at 650 ℃ for 100min to obtain the purple tungsten with the average rod diameter of 110 nm; then reducing with hydrogen at 850 deg.C for 90min to obtain W-0.5Y with average particle diameter of 130nm2O3And (3) nano powder.
Example 8
A liquid-liquid yttrium oxide-doped nano tungsten-based powder material comprises the following components in percentage by weight: 1% of yttrium oxide, and the balance being W. The preparation method comprises the following steps:
step S1, weighing yttrium sulfate and ammonium metatungstate according to the mass ratio of 1.27:100, and dissolving into distilled water to obtain uniform, colorless and transparent AMT-Y2(SO4)3Mixing the solution;
step S2, carrying out spray drying on the mixed solution, wherein the temperature of a spray drying air inlet is 230 ℃, and the liquid inlet speed is 5L/h, so as to obtain precursor powder;
step S3, slightly reducing the precursor powder at 650 ℃ for 100min to obtain the purple tungsten with the average rod diameter of 90 nm; then reducing with hydrogen at 750 deg.C for 90min to obtain W-1Y with average particle diameter of 110nm2O3And (3) nano powder.
FIG. 1 shows the purple tungsten powder WO obtained in example 62.72In the SEM image, the obtained purple tungsten rod is small in diameter, large in length-diameter ratio and very loose in powder, hydrogen can enter the powder particles and escape from water vapor during hydrogen reduction, and the nano tungsten powder is obtained through rapid reduction.
FIG. 2 is an SEM photograph of a nano tungsten-based powder obtained in example 6, and FIG. 3 is a result of XRD analysis thereof. The obtained nano tungsten powder is uniform in size, and shows better dispersibility compared with the attached drawings 1 and 2 of the patent of application publication No. CN 106564927B; figures 2, 3 and 4 of the patent of the comparative application publication CN107282938A show smaller particle sizes; the diffraction peak of tungsten detected in the XRD spectrum is very sharp, which indicates that the purple tungsten is completely reduced, and the obtained tungsten powder has good crystallinity.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.