67 results about "Tungsten acid" patented technology

The invention belongs to the technical field of scattered metal recovery, and particularly relates to a recycling method of tungsten-rhenium alloy waste. The tungsten-rhenium alloy is a solid solution strengthened alloy which takes tungsten element as a matrix and consists of the tungsten element and rhenium element, and has the characteristics of high melting point, high strength and high hardness. As the price is high, it is very necessary to comprehensively utilize the tungsten-rhenium alloy waste. The invention discloses a recycling method of tungsten-rhenium alloy waste. Firstly, tungsten-rhenium alloy waste is cleaned, dried and smashed, and waste powder is formed; then dispersing the waste material powder into water dissolved with ammonium metatungstate and a surfactant; then, carrying out spray drying to form mixed powder; and finally, the mixed powder is subjected to roasting and hydrogen reduction, and tungsten-rhenium alloy powder with the metal rhenium content lower than the metal rhenium content in the tungsten-rhenium alloy waste is formed. Compared with an existing tungsten-rhenium alloy waste recycling method, the recycling method has the advantages of being simple in process, low in energy consumption, small in loss and good in uniformity.

The invention belongs to the technical field of functional materials, and particularly relates to ultra-thick tabular tungsten oxide and a preparation method thereof.The preparation method of the ultra-thick tabular tungsten oxide comprises the following steps that S1, ammonium tungstate is added into deionized water and stirred to be dissolved at the temperature of 70-90 DEG C, and a clarified ammonium tungstate solution is obtained; s2, cooling the clarified ammonium tungstate solution to normal temperature at a cooling rate of 0.5-2 DEG C / h, and then carrying out suction filtration to obtain plate-shaped ammonium tungstate crystals; s3, calcining the tabular ammonium tungstate crystal to obtain ultra-thick tabular tungsten oxide; ammonium tungstate is adopted as a raw material, controllability is high, tungsten oxide which is uniform in particle size and complete in plate shape is obtained through optimized crystallization and calcination, the purity is larger than or equal to 99%, the problems that traditional tungsten oxide is agglomerated and disordered in shape are solved, functional adaptability is high, the plate-shaped structure can be directionally oriented, the dielectric performance, the breakdown performance and other performance are improved, and the method is suitable for multiple high-end scenes; parameters are easy to control, and operation is simple, green and safe.

The invention belongs to the technical field of tungsten and tungsten products, and particularly relates to a doped tungsten oxide composite material and a preparation method and application thereof. The invention provides a method for preparing doped tungsten oxide by a chemical precipitation method, which comprises the following steps: dispersing two aqueous solutions in the form of tiny liquid drops in an atomization manner, and carrying out chemical reaction at the moment of contact and mixing, so that rare earth element cations are rapidly combined with hydroxyl anions in an alkaline environment; the preparation method comprises the following steps: adding ammonium paratungstate into an ammonium paratungstate precursor, quickly drying at high temperature, nucleating to obtain the doped ammonium paratungstate precursor, realizing uniform distribution of rare earth elements, and calcining at high temperature to obtain the doped tungsten oxide composite material with uniform particle size. The invention aims to provide a preparation method of a short-process doped composite material powder which can be efficiently industrialized and is uniform in nanoscale particle size.

The application belongs to the technical field of metallurgy, and particularly relates to medium-granularity tungsten carbide powder and a preparation method and application thereof. The preparation method comprises the following steps: S1, obtaining high-purity ammonium paratungstate, and calcining the high-purity ammonium paratungstate to obtain tungsten oxide, wherein K in the high-purity ammonium paratungstate is less than or equal to 1 ppm, Na in the high-purity ammonium paratungstate is less than or equal to 1 ppm, and the specific surface area of the tungsten oxide is 0.3-1.0 m 2 / g; S2, first hydrogen reduction, second hydrogen reduction and third hydrogen reduction are performed on the tungsten oxide to obtain tungsten powder; S3, the tungsten powder is sieved and carbon is added to obtain a tungsten-carbon mixture, carbonization, crushing and sieving are performed on the tungsten-carbon mixture to obtain medium-granularity tungsten carbide powder. The application selects high-purity ammonium paratungstate with less than 1 ppm of impurity elements such as potassium and sodium as raw material, which can effectively reduce abnormal growth of tungsten powder particles caused by impurity elements in the reduction process, tungsten powder particles are developed completely by adopting three-stage hydrogen reduction, the powder activity is low, and the particle size increase is small in the subsequent carbonization process.

The invention belongs to the technical field of tungsten and tungsten products, and particularly relates to a preparation method and application of a rare earth oxide doped tungsten composite material. A tungsten salt solution and a rare earth metal salt solution are dispersed and distributed in a high-temperature environment in a tiny suspension form in an atomization manner and are mixed with each other. Then, at a high temperature, liquid drops formed by mixing are rapidly dried and are subjected to pyrolytic reaction to form tungsten oxide and nano rare earth oxide. In the subsequent reduction reaction, tungsten oxide is reduced into tungsten powder, and the rare earth oxide retains the original components and structure and is uniformly distributed. The invention provides the method capable of efficiently and industrially preparing the uniform rare earth doped tungsten powder in a short process, ammonium paratungstate does not need to be produced, the influence of the genetic effect of ammonium paratungstate is reduced, the process steps are reduced, and the energy utilization rate is increased; the rare earth and the tungsten element are uniformly mixed in a liquid-liquid mixing mode, the tungsten powder uniformly doped with the rare earth is obtained through high-temperature rapid oxidation, and no waste liquid is generated in the production process.

The invention discloses a dressing and smelting combined treatment method for tungsten-tin bulk concentrate, and belongs to the technical field of mineral processing. The method comprises the steps that tungsten-tin bulk concentrate obtained through flotation of a metal ion-hydroximic acid complex collecting agent from tungsten-tin polymetallic ore under the low-alkalinity condition is directly subjected to size mixing, flotation is conducted under the high-alkalinity condition, and bulk concentrate of wolframite and cassiterite and scheelite concentrate are obtained; leaching the scheelite concentrate by using mixed acid to obtain a tungstate-containing acid leaching solution and gypsum; bulk concentrate of wolframite and cassiterite is decomposed through alkaline process autoclaving to obtain tungsten-containing alkaline leaching liquid and tin-rich slag, and cassiterite is recycled from the tin-rich slag through centrifugation. According to the method, OH <-> is used for precisely regulating and controlling the coordination structures of the collecting agents, and efficient separation of scheelite, wolframite and cassiterite is achieved by means of the adsorption characteristic difference of the collecting agents of different coordination structures on the wolframite and the scheelite. And then wet metallurgy is combined to achieve clean and efficient utilization of tungsten resources in the tungsten-tin bulk concentrate and comprehensive recovery of tin resources, and huge economic and environmental benefits are achieved.

This invention provides nano-tungsten carbide and its preparation method. The preparation method includes: providing ammonium paratungstate; calcining the ammonium paratungstate to form purple tungsten; oxidizing the purple tungsten in pure oxygen to form yellow tungsten; ball milling the yellow tungsten with carbon, then isostatically pressing it into a block, followed by carbon reduction to obtain a tungsten-carbon mixed block; carbonizing the tungsten-carbon mixed block, and then crushing it to obtain nano-tungsten carbide powder. This invention can reduce the manufacturing cost of nano-tungsten carbide and is beneficial for preparing finer tungsten carbide powder.

The application relates to the technical field of tungsten-rhenium alloy, and discloses a tungsten-rhenium alloy stir head material for friction stir welding, which is characterized in that the tungsten-rhenium alloy stir head material is prepared by reducing and sintering tungsten-rhenium precursors, the tungsten-rhenium precursors are prepared by using ammonium metatungstate, ammonium rhenate and oxalic acid as raw materials, and the application further discloses a preparation method of the tungsten-rhenium alloy stir head material, which comprises the following steps: S1, tungsten-rhenium precursor preparation: after ammonium metatungstate, ammonium rhenate and oxalic acid are dissolved, stirred and heated to react, spray drying is carried out to obtain tungsten-rhenium precursor powder; and S2, tungsten-rhenium precursor powder reduction: tungsten-rhenium precursor powder is heated and reduced in a hydrogen environment to obtain tungsten-rhenium alloy powder. The preparation process is simple, fast, low in cost and convenient for batch industrial production; the prepared single-phase tungsten-rhenium alloy is high in hardness and density and uniform in composition; the relative density of the tungsten-rhenium alloy after sintering reaches 99.6%, the microhardness value is 585+ / -5 Hv, and the grain size is 1-2 mu m.

The invention discloses an amorphous electrochromic film inlaid with Cs-doped tungsten trioxide quantum dots as well as a preparation method and application of the amorphous electrochromic film. The preparation method comprises the following steps: S1, adding hydrochloric acid into a sodium tungstate dihydrate aqueous solution to obtain a precipitate; washing the precipitate until the pH value of the supernate is greater than 3, and then drying the precipitate to obtain hydrated tungstic acid powder; dissolving hydrated tungstic acid powder in a hydrogen peroxide solution to obtain a peroxy tungstic acid solution, and then adding a substance containing a Cs element to obtain a Cs-peroxy tungstic acid solution; the molar ratio of Cs ions to W ions in the Cs-peroxotungstic acid solution is not less than 1: 100 and less than 5: 100; s2, heating, evaporating and concentrating the Cs-peroxy tungstic acid solution to obtain a precursor solution containing a bimetal oxygen cluster; and transferring the precursor solution containing the bimetal oxygen clusters to a substrate by adopting a film coating process, and annealing to obtain the amorphous tungsten trioxide electrochromic film inlaid with the Cs-doped tungsten trioxide quantum dots.

The invention belongs to the technical field of recycling of rare and noble metal secondary resources, and discloses a method for preparing a tungsten compound and chloroplatinate from a waste catalyst and application of the method. The method comprises the following steps: (1) firing and crushing the waste catalyst, (2) reacting the waste catalyst with acid, (3) filtering and discarding filtrate, (4) reacting the precipitate with ammonia water, filtering to obtain an ammonium tungstate solution, and retaining filter residues; (5) concentrating the ammonium tungstate solution, crystallizing, separating and drying to obtain an ammonium paratungstate finished product; and (6) reacting the filter residues retained in the step (4) with aqua regia to prepare chloroplatinate. And (7) firing the ammonium paratungstate at a high temperature to obtain tungsten trioxide. According to the method, tungsten and platinum can be effectively separated from the carrier, and the recovery rate of rare and precious metals is increased.

The invention relates to the technical field of high-grade alkylphenol preparation, in particular to a method for preparing high-grade alkylphenol from lignin oil. The method comprises the following steps: mixing lignin oil, a tungsten acid catalyst and a reaction solvent, and carrying out a catalytic reaction to obtain a reaction solution; and then separating the reaction liquid to obtain the higher alkylphenol, wherein the reaction solvent is selected from one or more of tetrahydrofuran, tetrahydropyran, dioxane and isopropyl alcohol. The method provided by the invention is carried out in the specific reaction solvent, the application of a noble metal catalyst can be avoided, the reaction condition is mild, the side reaction is less, the conversion rate of monomer phenolic substances in the lignin oil by the catalyst is more than 70%, the selectivity of higher alkylphenol is more than 25%, and the added value of the lignin oil can be obviously improved.

This invention belongs to the field of cathode materials, and provides a ternary cathode material, its preparation method, and a battery. The tungsten content of the ternary cathode material provided by this invention gradually decreases along a direction perpendicular to the surface of the ternary cathode material towards the interior, and the tungsten element in the ternary cathode material is mainly distributed within a depth range of 100 nm. The tungsten element material on the outer surface of the ternary active material includes tungsten oxide and lithium tungstate. The formed lithium tungstate consumes the residual lithium on the surface of the ternary active material, reducing the residual lithium content on the surface of the ternary cathode material. In the preparation method of the ternary cathode material provided by this invention, tungsten chloride with a low melting point is deposited on the surface of the ternary active material, and then the tungsten chloride is oxidized to tungsten oxide using an oxidation reaction to obtain the ternary cathode material. This reduces heat consumption while ensuring that the tungsten element is uniformly distributed on the surface of the ternary cathode material, thereby obtaining a ternary cathode material with high compressive strength, low surface residual lithium content, and good cycle performance.

The utility model relates to the technical field of tungsten smelting equipment, and provides an ammonia-free tungsten smelting drying device which comprises a first support, a drying cylinder is fixedly connected to the first support, an air inlet, a feeding port, a vacuumizing port and an air outlet are formed in the upper end of the drying cylinder, a discharging port is formed in the lower end of the drying cylinder, and a stirring shaft is arranged in the drying cylinder. The stirring shaft is used for stirring materials in the drying cylinder, and a driving mechanism is arranged on the left side of the drying cylinder and used for driving the stirring shaft to rotate. The middle parts of the connecting rods are fixedly connected with the stirring shaft, and the two ends of the connecting rods are fixedly connected with buckets. When the device is used for drying the tungstic acid, the tungstic acid can be greatly stirred, the heating is more uniform, the water vapor emission is more sufficient, and the drying quality and efficiency are improved; the hot air making contact with tungstic acid is conveyed to the dehumidifier, water vapor in the hot air is removed, then the dried hot air is conveyed into the drying cylinder again through the circulating fan, and energy waste is avoided.

This invention relates to a method for preparing and applying a ternary heterostructure nanosheet of tungsten diselenide / tin diselenide / tin monoselenide, belonging to the field of gas sensor technology. The invention discloses a ternary heterostructure nanosheet of tungsten diselenide / tin diselenide / tin monoselenide and its application as a sensing material in a highly selective and sensitive flexible NO2 gas sensor. The invention utilizes a liquid-phase growth method, using SnSe2 nanosheets, ammonium tungstate, and diphenyldiselenoether as raw materials, and varying reaction conditions such as temperature, reaction time, and raw material content to prepare the ternary heterostructure nanosheet of tungsten diselenide / tin diselenide / tin monoselenide. Subsequently, these nanosheets are sprayed onto interdigitated electrodes and dried to form a film, thus preparing a chemielectric resistive gas sensor capable of detecting low concentrations of nitrogen dioxide gas at room temperature. It not only possesses high sensitivity and selectivity but can also be applied to flexible NO2 gas sensing.

The invention belongs to the technical field of metallurgy, and particularly relates to medium-particle tungsten carbide powder and a preparation method and application thereof.The preparation method comprises the following steps that S1, high-purity ammonium paratungstate is obtained, the high-purity ammonium paratungstate is calcined to obtain tungsten oxide, K in the high-purity ammonium paratungstate is smaller than or equal to 1 ppm, Na in the high-purity ammonium paratungstate is smaller than or equal to 1 ppm, N is smaller than or equal to 1 ppm, and N is smaller than or equal to 1 ppm; the specific surface area of the tungsten oxide is 0.3-1.0 m < 2 > / g; s2, the tungsten oxide is subjected to first hydrogen reduction, second hydrogen reduction and third hydrogen reduction, and tungsten powder is obtained; and S3, the tungsten powder is sieved, a tungsten-carbon mixture is obtained after carbon is added, the tungsten-carbon mixture is carbonized, crushed and sieved, and the medium-particle tungsten carbide powder is obtained. According to the method, high-purity ammonium paratungstate with the content of impurity elements such as potassium and sodium smaller than 1 ppm is selected as the raw material, abnormal growth of tungsten powder particles caused by the impurity elements in the reduction process can be effectively reduced, three-section hydrogen reduction is adopted, the tungsten powder particles are developed completely, the powder activity is low, and the particle size increase in the subsequent carbonization process is small.

The invention belongs to the technical field of tungsten material manufacturing, and particularly relates to a tungsten-cerium alloy wire and a preparation method thereof.The preparation method comprises the steps that a cerium-containing solution and ammonium paratungstate are mixed through a spray mixing method and dried, and a mixture is obtained; the mixture is calcined at the temperature lower than or equal to 900 DEG C and reduced in the hydrogen atmosphere at the temperature of 800-1050 DEG C, and cerium-containing tungsten powder is obtained; the cerium-containing tungsten powder is subjected to isostatic pressing forming, sintered for 1-1.5 h at the temperature of 1500-1600 DEG C in the hydrogen atmosphere and then sintered for 5-8 h at the temperature of 2300-2450 DEG C, and a tungsten rod is obtained; and the tungsten rod is subjected to rolling, electric pulse treatment, forging and wire drawing treatment, and the tungsten-cerium alloy wire with the diameter being 20-28 microns is obtained. The cerium element is uniformly distributed in the alloy wire through solid-liquid cerium doping; through the two-stage sintering process, the compactness and the mechanical property of the tungsten rod are improved; the prepared tungsten-cerium alloy wire has excellent tensile strength, high elongation and excellent fatigue resistance, and shows low edge breakage rate, low wire breakage rate and long service life in silicon nitride ceramic substrate cutting.

The application belongs to the technical field of nanometer material preparation, and particularly relates to a kind of spherical-like nanometer tungsten oxide and a preparation method thereof, wherein the preparation method of the spherical-like nanometer tungsten oxide comprises the following steps: S1, obtaining an ammonium tungstate solution; S2, adding liquid nitrogen dropwise into the ammonium tungstate solution to obtain spherical-like nanometer crystals; and S3, calcining the spherical-like nanometer crystals to obtain spherical-like nanometer tungsten oxide; the application has simple process, strong controllability, easy-to-adjust parameters, simple raw materials, is suitable for large-scale industrial production, introduces liquid nitrogen quenching process, uses ultra-low temperature environment to make solution reach high supersaturation instantaneously and generate a large number of fine crystal nuclei, at the same time, the tiny nitrogen bubbles formed by liquid nitrogen vaporization effectively inhibit the collision and agglomeration between the newly generated crystal nuclei, thereby ensuring good dispersity of the product.

The invention discloses a tungsten carbide silver contact material and a preparation method thereof, and the preparation method comprises the following steps: adding a silver nitrate solution into a sodium tungstate solution, stirring at a constant temperature, standing and aging to obtain an Ag2WO4.nH2O colloidal precipitate, carrying out suction filtration and washing, dispersing and dissolving, and carrying out ultrasonic oscillation to obtain an Ag2WO4.nH2O sol; wC powder is added into the Ag2WO4.nH2O sol, first-time ball milling is carried out, two-phase mixed slurry is obtained, silver powder and a dispersing agent are added into the two-phase mixed slurry, second-time ball milling is carried out, three-phase mixed slurry is obtained, granulation and vacuum drying treatment are carried out, and composite feed is obtained; pressing the composite feed to obtain a green body; the green body is placed in a sintering furnace to be subjected to three-section heating gradient sintering treatment, the tungsten carbide silver contact material is obtained, the tungsten carbide silver contact material is composed of, by mass, 35%-80% of WC, 15%-60% of Ag and 1%-5% of Ag4WOx, and the tungsten carbide silver contact material has high density, high hardness, high conductivity and good fusion welding resistance.

This invention relates to the field of metal powder preparation technology, and discloses a high-pressure compact strength tungsten powder, its preparation method, and its applications. Using ammonium paratungstate as raw material, a purple tungsten oxide precursor is prepared by nitrogen calcination. Then, a unique multi-temperature gradient reduction process is employed. Under the synergistic effect of low-temperature nucleation, medium-temperature high-flow-rate gas-induced growth, and high-temperature curing and shaping, a tungsten powder coarse material with abundant micro-burrs and a porous framework is constructed. Finally, the finished product is obtained through air-jet milling, shaping, and passivation. The prepared tungsten powder has a Fisher particle size of 2.8–3.8 μm, a bulk density of 2.5–3.0 g / cm³, a specific surface area of ​​0.40–0.60 m² / g, and a compact strength of 11.5–12.70 MPa at 200 MPa pressure, significantly superior to conventional tungsten powder. This tungsten powder possesses high purity, high mechanical interlocking force, and good processing fluidity, greatly reducing the molding difficulty and breakage rate of irregularly shaped or thin-walled tungsten products.

The invention discloses a vanadium-tungsten bimetallic oxide electrochromic film and a preparation method thereof.The preparation method comprises the steps that S1, ammonium paratungstate hydrate, ammonium metavanadate and oxalic acid dihydrate are dissolved in deionized water, and a hydrothermal reaction precursor solution is obtained after stirring; and S2, carrying out hydrothermal reaction on the conductive glass to obtain the conductive glass. Controllable synthesis of the vanadium-tungsten bimetallic oxide film is realized by controlling the molar ratio of vanadium to tungsten in the precursor solution. The invention also discloses the vanadium-tungsten bimetallic oxide electrochromic film prepared by the method, and an electrochromic device comprising the film. The vanadium-tungsten oxide thin film prepared by the method has a unique nano hexagonal star-shaped structure, has a high specific surface area and excellent structural stability, not only can improve abundant electrochemical reaction active sites and remarkably improve the area capacitance of a thin film material, but also can improve the cycling stability; and meanwhile, the light modulation amplitude and the coloring efficiency are relatively high.

The invention provides rare earth oxide doped tungsten powder and a preparation method and application thereof, and belongs to the field of powder metallurgy, and the preparation method of the rare earth oxide doped tungsten powder comprises the following steps that ammonium paratungstate is subjected to pre-calcination treatment to obtain a porous precursor; preparing rare earth nitrate into a rare earth nitrate solution, mixing the porous precursor with the rare earth nitrate solution, carrying out ball milling treatment, and drying to obtain a mixed material; and the mixed material is subjected to hydrogen reduction treatment, reduction is conducted in a low-temperature area of 500-650 DEG C firstly, then the temperature is increased to a high-temperature area of 700-950 DEG C for reduction, and the rare earth oxide doped tungsten powder is obtained. When the obtained tungsten powder is applied to tungsten filament preparation, the higher drawing yield is shown, and the mechanical property of tungsten filaments is remarkably improved.

The application discloses a method for efficiently recycling molybdenum-removed residue in tungsten smelting, the molybdenum-removed residue containing tungsten, molybdenum and copper, comprising the following steps: using ammonia and manganese dioxide to perform first high-temperature leaching treatment on the molybdenum-removed residue to obtain a tungsten-copper-containing residue and an ammonium molybdate solution; and using ammonia and manganese dioxide to perform second high-temperature leaching treatment on the molybdenum-removed residue to obtain a copper ammonia solution; and using the obtained copper ammonia solution as a molybdenum removal reagent to perform molybdenum removal treatment on a molybdenum-containing ammonium tungstate solution. According to the method for efficiently recycling molybdenum-removed residue in tungsten smelting, effective separation of tungsten and molybdenum can be realized, the recycling efficiency of tungsten and molybdenum is high, copper can be recycled, the cost of the molybdenum removal reagent is reduced, the risk of environmental pollution is reduced, and the purpose of efficiently recycling the molybdenum-removed residue is achieved.

The application provides a preparation method of photo / electro dual-modulation variable color fabric, which comprises the following steps: carrying out surface decontamination treatment on the fabric, drying the fabric for standby, preparing a sodium tungstate solution, adding oxalic acid, adding hydrochloric acid to adjust the pH value, stirring, then adding rare earth elements, continuously stirring in a light-shielded environment to obtain a mixed solution, putting the fabric and the mixed solution into a reaction kettle, taking out the fabric after hydrothermal reaction, cleaning and drying the fabric, and obtaining the photo / electro dual-modulation variable color fabric. The application adopts a hydrothermal method to synthesize variable color materials on the surface of the fabric, so that a film with photochromic and electrochromic capabilities is formed on the surface of the fabric, tungsten trioxide is used as a main electrochromic material, and the photochromic and electrochromic dual-modulation performance of the variable color fabric is realized by doping rare earth elements Nd and Eu. The variable color fabric prepared by the application has good flexibility and stable photo / electro dual-modulation performance, the flexible substrate makes the variable color fabric have potential wearable performance, and the variable color fabric can be used for future smart clothes and implantable display applications.

The present application relates to a kind of hexagonal phase tungsten oxide electrochromic film and its preparation method and its application, above-mentioned preparation method includes the following steps: ammonium tungstate, ammonium sulfate and oxalic acid are dissolved according to certain proportion, and WO3 precursor sol is formed by reaction configuration;WO3 precursor sol is coated on conductive substrate, and the conductive substrate containing WO3 seed on surface is obtained;Ammonium tungstate, ammonium sulfate and oxalic acid are dissolved in deionized water according to certain proportion, precursor mixed solution is obtained, and precursor mixed solution is transferred to hydrothermal reactor;Again, the conductive substrate containing WO3 seed is vertically placed in hydrothermal reactor, the reactor is sealed in oven and reacted for a period of time, then the conductive substrate is taken out, cleaned, dried, and the film is removed, a kind of hexagonal phase WO3 electrochromic film can be obtained.The WO3 electrochromic film synthesized by the above method has better optical modulation capacity.

The invention relates to the technical field of rare earth metal electrolysis cathode protection coatings, in particular to an in-situ generated rare earth oxide diffusion barrier layer on the surface of a tungsten cathode. According to the method, fused salt electrodeposition and sol chemical deposition are combined, and a composite diffusion barrier layer of an yttrium tungstate binding layer / yttrium oxyfluoride barrier layer is constructed on the surface of a tungsten cathode in situ; the method comprises the following steps: firstly, enabling sodium tungstate to react with yttrium fluoride in fused salt through electro-deposition, and generating a compact and firmly combined yttrium tungstate layer on a tungsten substrate in situ; and then a compact surface layer of multiple yttrium oxyfluoride layers is constructed on the surface of the tungsten cathode by adopting a sol-gel method, strong interface bonding is realized by utilizing an in-situ reaction, surface hole sealing is realized by utilizing the densification characteristic of yttrium oxyfluoride, finally, a composite protection structure is formed, and the high-temperature oxidation resistance and molten salt corrosion resistance of the tungsten cathode are remarkably improved.

Disclosed in the present invention are the preparation and use of a supported photo-Fenton catalyst. The preparation method comprises: I, formulating a sodium tungstate solution and a potassium oxalate solution, adjusting the pH until acidic, and performing a hydrothermal reaction and calcination to obtain a tungsten trioxide composite material; II, formulating a sodium tungstate solution and an ammonium ferrous sulfate solution; III, ultrasonically dispersing the tungsten trioxide composite material in the ammonium ferrous sulfate solution to obtain a suspension; and IV, under continuous stirring, adding the sodium tungstate solution into the suspension in a dropwise manner, stirring same, performing a hydrothermal reaction, and washing and drying same to obtain a tungsten trioxide / iron tungstate nano material. In the present invention, an FeWO4 / WO3 heterojunction is formed by using a hydrothermal synthesis method, which improves the separation efficiency of carriers and the photo-Fenton catalyst activity of the tungsten trioxide / iron tungstate nano material, thereby increasing the catalytic efficiency thereof. The catalyst is suitable for the degradation treatment of photocatalyst wastewater or dye methylene blue and methyl violet, and the preparation process is simple and easy to implement, and has low pollution.

This invention belongs to the field of tungsten-based alloy powder preparation technology, specifically relating to a spherical tungsten-rhenium alloy powder and its preparation method. The preparation method includes the following steps: mixing ammonium tungstate, ammonium rhenium oxide, yttrium hafnium oxide, and a forming agent in water, followed by spray drying to obtain a mixed crystalline powder; subjecting the mixed crystalline powder to reduction treatment in a hydrogen atmosphere to obtain tungsten-rhenium alloy powder; and subjecting the tungsten-rhenium alloy powder to plasma spheroidization treatment under argon conditions to obtain the spherical tungsten-rhenium alloy powder. This invention significantly improves the density of the sintered blank and enhances the room-temperature and high-temperature mechanical properties of the tungsten-rhenium alloy by adding yttrium hafnium oxide and a forming agent composed of polyethylene glycol, polyvinyl alcohol, and molybdenum disulfide to the tungsten-rhenium alloy powder.

The application discloses a vanadium-tungsten bimetal oxide electrochromic film and a preparation method thereof, and the preparation method comprises the following steps: S1, dissolving ammonium paratungstate hydrate, ammonium metavanadate and oxalic acid dihydrate in deionized water to obtain a hydrothermal reaction precursor solution after stirring; and S2, performing a hydrothermal reaction on conductive glass, and thus the vanadium-tungsten bimetal oxide electrochromic film is obtained. The controllable synthesis of the vanadium-tungsten bimetal oxide film is realized by controlling the molar ratio of vanadium and tungsten in the precursor solution. The application further discloses a vanadium-tungsten bimetal oxide electrochromic film prepared by the method and an electrochromic device comprising the film. The vanadium-tungsten oxide film prepared by the application has a unique nano hexagonal star structure, high specific surface area and excellent structural stability, can not only improve the rich electrochemical reaction active sites and significantly improve the area capacitance of the film material, but also improve the cycle stability, and has a high light modulation amplitude and a high coloring efficiency.

The present application belongs to the technical field of hydrometallurgy of tungsten, and particularly relates to a method for improving the crystallization rate of ammonium paratungstate, comprising the following steps: S1, obtaining an ammonium tungstate solution, wherein the ammonium tungstate solution comprises metatungstate ions; S2, adding a supersaturation regulator to the ammonium tungstate solution, wherein the supersaturation regulator comprises hydrogen peroxide and ammonia; S3, heating the ammonium tungstate solution to a first temperature, and then adding superfine ammonium paratungstate; S4, heating the ammonium tungstate solution to a second temperature, and keeping the solution at the second temperature and continuously stirring to obtain ammonium paratungstate crystals; by adjusting the temperature, pH value, solvent type and concentration, etc., the crystallization conditions of the metatungstate ions and the ammonium paratungstate are optimized, the crystallization rate is improved, by controlling the supersaturation of the solution, the uneven crystal growth caused by the too fast crystallization rate is avoided, the crystallization rate is affected, and the supersaturation can be controlled by adjusting the solution concentration, temperature and other parameters.