Tungsten Oxide

Tungsten oxide is a kind of tungstic anhydride, which is a tungstate product. Tungsten oxide type includes tungsten trioxide and tungsten dioxide. In actual industrial production, it is rare to have tungsten dioxide. Tungsten dioxide is also known as brown tungsten oxide. The formula WO 2  tungsten dioxide is an intermediate transition state of ammonium paratungstate into tungsten trioxide. Its appearance is tan monoclinic powder crystal, and tungsten dioxide is the most commonly known, the role is to manufacture tungsten powder and tungsten trioxide. Tungsten trioxide, also known as yellow tungsten oxide, chemical formula WO 3 , is the main tungsten oxide product of our country before the eighties. Yellow powder is insoluble in water, soluble in alkali and slightly soluble in acid. Its density is 7.16 g / cm 3 ; The melting point is 1473 ° C; the boiling point is about 1700 ° C. Mainly used in the system of high melting point alloys and cemented carbide, tungsten wire and fire ga...

Ball mill is a fine equipment used in industry and can also be used for mixing. The ball mill is composed of a cylinder and sphere, its working principle is when the cylinder rotates, installed in the cylinder body and the grinding body in grinding by centrifugal force and friction force with the cylinder to rotate to a height, and then automatically fall, the material in the cylinder impact and the grinding and grinding material. The main factors affecting the efficiency of the ball mill are the speed of the ball mill, the quantity of the ball, the amount of water and electrolyte, the time and the loading. The normal milling time is about 24-72 hours, and the length of the ball milling time directly affects the quality of the ball milling product. Generally speaking, coarse grained material is easier to grind to coffee, and the time is shorter. However, the milling time of gal material to cut below is usually prolonged by several times or longer. However, with the prolongation of ball...

Tungsten trioxide (WO 3 ) is a kind of transition metal oxides, it is not only a kind of N type semiconductor material, is also a kind of "d0" oxide, this dual identity so it has many characteristics. The research shows that there is rod, plate and rod plate three kinds of nano tungsten oxide crystal, gas sensing properties of tungsten oxide with different crystal morphology is slightly different, some scholars use tungsten trioxide for four kinds of common harmful gases were tested and concluded. (1) The best working temperature of WO 3  sensor in ethanol, acetone, ammonia and formaldehyde is 350 ℃, 300 ℃, 325 ℃ and 250 ℃, respectively, and the sensitivity reaches the maximum at gas concentration of 1000 ppm. 21.29, 10.82, 24.32 and 9.68 respectively, and the lowest detection concentration of gas sensors for four gases are 100ppm, 50ppm, 25ppm and 100ppm, respectively. (2) The best working temperature of nano-plate WO 3  gas sensor is 350 ℃, 300 ℃, 325 ℃ and 250 ℃, respecti...

Nano tungsten trioxide is a typical N-type semiconductor gas sensing material, which has a large specific surface area, stable chemical properties, a variety of toxic gases have good sensitivity, can effectively improve sensitivity and responsiveness of gas sensors effectively reduce the harmful effects of harmful gases on human health. The preparation of nano tungsten trioxide by hydrothermal method can overcome the problems that the nano rods prepared in the prior art have larger diameters, uneven distribution of rods and other forms of particles.  Using ammonium metatungstate as tungsten source, citric acid as the profile control agent, according to a certain proportion in the mixed solution, adding concentrated hydrochloric acid solution was adjusted by drops in pH magnetic stirring at room temperature is equal to 1.5, half an hour so that the magnetic stirring solution mixing, the mixed solution was transferred to a hydrothermal reaction kettle PTFE capacity of 100 mL in seal...

Tungsten plate is a tungsten material pressed by special process, it is mainly used in electronics and semiconductor industry parts manufacturing, tungsten sputtering target, high temperature furnace with tungsten boat, sapphire long furnace components etc. The conventional thin tungsten plate pressing process uses yellow tungsten oxide , because the size distribution of yellow oxide powder is narrow and the particle size of powder is uniform, the gap of particles is not easy to be filled in the process of pressing, which eventually leads to lower strength of pressing. The physical and mechanical properties of the tungsten plate are closely related to the strength of the compact, the strength of compacts is related to the characteristics of tungsten powder morphology and particle size distribution. There are three types of commonly used tungsten trioxide, yellow tungsten oxide, blue tungsten oxide and purple tungsten oxide, its flagship product is divided into three level: ordinary, fi...

  What kind of tungsten oxide can produce high quality cemented carbide? At present, there are yellow tungsten oxide, blue tungsten oxide and violet tungsten oxide which are available in the market. Which kind of raw material is most suitable for cemented carbide production? Violet Tungsten oxide is the best raw material for producing superfine tungsten powder and nanometer metal tungsten powder. Ultrafine tungsten carbide was prepared by ultrafine or nano tungsten powder, and then cemented carbide was produced, the properties and requirements of cemented carbide are better than those made of ordinary. tungsten powder. The alloy with violet tungsten as the raw material has better quality and stronger adaptability, and the violet tungsten can make the penetration capability of the military armour piercing bullet increase by 20%, and the abrasion resistance of the carbide cemented carbide tool can be increased by 12%, etc. The preparation methods of violet tungsten include hydrogen ...

Scientists discovered that VO 2   has a distinctive phase change function long time ago. When the phase transition temperature is 68°C, it can change reversibly from low temperature monoclinic system to high temperature tetragonal system. The physical properties such as resistivity, optical transmittance, permeability and so on have changed greatly. Doping method is an effective method to change the phase transition temperature of VO 2 . The preparation methods of doped VO 2  films include sol-gel doping method, hydrothermal synthesis doping method, sputtering doping method, metal organic compound vapor deposition doping method, pulse laser deposition process, inorganic sol-gel doping method, and microwave plasma method. We prepare it by microwave plasma method. Another main content of the preparation of doped VO 2  thin film is the selected doping compounds. Weigh a certain amount of pure V 2  O 5  powder and W 2 O 3  into the pot, then stirring, put in th...

  Violet tungsten oxide , abbreviated as VTO, is named after the appearance of purple. It is the best raw material for the preparation of ultrafine or nanometer tungsten powder. It is produced in the process of producing ammonium paratungstate under the condition of precise control of temperature reduction. Violet tungsten oxide is mainly used in the production of tungsten powder and tungsten carbide. Violet tungsten oxide sample color can be divided into purple, dark purple, dark blue, blue, the color of violet tungsten oxide and its oxygen index, particle degree of tightness, the aspect ratio of the needle. Some scholars have invented a way to directly control and detect the quality of violet tungsten oxide. The quality of purple tungsten oxide is determined by the unique color of violet tungsten oxide. This method is called "colorimetric method" in the industry. The color of violet tungsten oxide is related to the oxygen index, the degree of tightness of the particles and ...

Nano tungsten oxide is considered to be one of the most promising new oxides gas sensing materials that detects nitrogen oxides, hydrogen sulfide, and acetone and other harmful gases. The preparation methods of nano tungsten oxide mainly include hydrothermal method, sputtering method, sol gel method and gas phase deposition method. Compared with other synthetic methods, as a new method for composing nano-materials, low heating solid phase chemical reaction has the characteristics of simple operation, friendly environment and mild conditions.  Mix sodium tungstate and sodium sulfate for 30min, the sample was placed in a cone bottle and placed for 24h to obtain the precursor. Then put the precursor calcined at 600°C in the muffle furnace 2h, nano tungsten carbide was obtained.  Based on the product of nano tungsten carbide test, the material in the lower working temperature of low concentration acetone gas showed the performance of fast response, high selectivity and high sensi...

Electrochromic is the phenomenon that the optical properties of materials change stably and reversibly under the action of applied electric field. It can cause light penetration through the electric field, changing color with the environment, and no longer need to curtain. WO 3  thin film is one of the most promising electrochromic materials. WO 3  thin films have been widely used in photochromic, photochromic, filter, dye sensitized solar cells and so on.  With the implantation and extraction of ions, the dissolution and ion residues of WO 3  thin films will occur, and the electrochromic properties will decline obviously, which limits the wide use of electrochromic devices. TiO 2  has excellent stability, and has excellent transmittance in wide waveband. The doping of electrochromic films with TiO 2  composite WO 3  can improve the stability and lifetime of devices.  Pure Ti/WO 3  composite films were prepared by radio frequency sputtering m...

Tungstic acid can be roughly divided into yellow tungstic acid and white tungstic acid. More and more practice has shown that tungstic acid not only has an important use in tungsten chemistry, but also has great value in tungsten metallurgy. Powdery white tungstic acid can compose tungsten niobium and tungsten tantalum Heteropoly salt. Tungsten phosphoric acid and tungstic acid can also be composed. The heteropoly acid prepared from powdered white tungstic acid has better catalytic performance than that prepared with tungstic acid.  The preparation of white tungstic acid is to drop Na 2 WO 4  solution into dilute acid. In the middle of the process, there is no acid anion, so the precipitation rate is high. In the Na 2 WO 4  solution tungsten exists as monomeric WO42-form. The presence of dilute acid immediately results in protonation and formation of tungstic acid precipitation. Generally, the prepared white tungstic acid is a mixture of mono - tungstic acid and poly - t...

Microwave absorbing material is an important stealth form in stealth technology. High temperature absorbing composites with new wave absorbing materials should be a kind of structure and function integrated material, which can replace metal parts and realize dual functions of bearing and stealth. Fullerene is characterized by cage-like structure, hollow in the middle, and the most common fullerene is C 60 . Because of the particularity of inorganic fullerene hollow cage-like structure, it is found that the inorganic fullerene’s structure has excellent resistance to compression and wave absorption. Its maximum compressive resistance is up to 25Gpa, which is the most hard molecular cage structure found recently, and its compressive resistance performance is better than other carbon cage like structures. Even when it under lower pressure, the collapse or transformation to other diamond structures will occur. Therefore, when inorganic fullerene structure is used as wave absorbing material,...

Tungsten disulfide is an excellent solid lubricant material, it has high application value in the field of super solid lubrication. Tungsten disulfide membrane have layered structure, it has lower hardness and better stability under high temperature, it is suitable to be used as a solid lubricant for friction parts in special environment. There are three main methods for preparing tungsten disulfide membrane which include RF sputtering method, reactive magnetron sputtering method, chemical deposition method. The method of RF sputtering crystal growth is the method of using RF sputtering to make the components of the crystal material gasified and then recrystallized to grow the crystal. RF sputtering is a sputtering deposition method suitable for all kinds of metal and nonmetal materials, the frequency range is 5~30MHz, the frequency of 13.56MHz is commonly used internationally. It is mainly used to prepare thin membranes and also to prepare small size crystals. WS2 powder with 99.99% ...

  Solid lubrication is a method of coating or plating on the surface of the friction pairs to form a thin film and reducing friction. The technique of using solid lubricants to lubricate is called solid lubrication.  Tungsten disulfide and molybdenum disulfide are excellent solid lubricating materials, in the field of ultra-solid lubrication has a very high value, this technology is applied to the hard disk drive bearing of computer, such as rotation and sliding in ultra high vacuum system. Molybdenum disulfide has a graphite-like structure, molybdenum and sulfur through the covalent bond to form a hexagonal structure, each molybdenum is surrounded by six sulfur atoms, the molecular layer surface only sulfur atoms, each layer molecular layer thickness of 0.626nm. The thermal stability of MoS 2  is better in the air environment lower than 400 degrees. When the temperature is higher than 400 degrees, MoS 2  will be oxidized to MoS 3  in a short time, MoS 3  i...

The structure of tungsten disulfide is a hexagonal layered structure with excellent electrical properties. In tungsten disulfide, the interaction between the W atoms in the layer and the surrounding S atoms is strong, and the interaction between the tungsten disulfide layer and the layer is weak. The thermal stability of two tungsten sulfide is stronger than that of molybdenum disulfide. The temperature range is wide, and it is not easy to decompose. Oxidation occurs at 539 degrees centigrade. Therefore, tungsten disulfide is an excellent semiconductor material for indirect bandgap semiconductors. When the thickness of tungsten disulfide is reduced to a single layer, it changes into a direct band gap, which means that tungsten disulfide can effectively pass through the bandgap transition absorb or emit photons. The band gap of monolayer tungsten disulfide is about 2eV. This electrical performance characteristic is the main advantage of tungsten disulfide in semiconductor tubes, transi...

Thermal sprayed tungsten carbide / cobalt cermet is widely used in aerospace, metallurgy, machinery and other fields due to its good hardness and toughness. Thermal spraying (spray welding), surfacing and other processes are gradually becoming the commonly used alloy, steel material anti-wear and surface corrosion technology measures. Tungsten carbide / cobalt thermal spraying technology has a simple process compared with other thin film and coating preparation technology, the coating and substrate have a wide range of selection, a large range of coating thickness, high deposition efficiency and easy to form composite coating.  The wear resistance of alloy is a systematic engineering problem. The material is only an important aspect to measure the grindability. In addition, it is also related to the stress state, surface structure, lubrication conditions, environmental temperature and other factors. The characteristics of thermal spraying powder vary with the milling process. The ...

The modification of zinc tungstate by doping rare earth elements is an effective way to improve its luminescent properties. The single crystal of zinc tungstate is rose red, the color makes the luminous efficiency decrease and the decoloration effect is obvious. After annealing for a long time, the ZnWo 4  crystal will disappear gradually, but the annealing of the bulk crystal still has difficulties which can not be overcome. The main problem is that the defect is incomplete and the defects are introduced into the annealing process.  In single doped rare earth crystals, only cerium doped Ce 3+  can recede the color of the crystal, both doped cerium Ce 3+  and lithium li 3+  have obvious decoloration effect on zinc tungstate crystal, especially, the former can obtain colorless crystal by proper doping. The removal mechanism of zinc tungstate may be due to the decomposition of CO 2  in Li 2 CO 3  crystals, CO 2  molecules will be partially retained...

In life, silver-nickel contact materials are widely used in relays, circuit breakers for low current ratings because of their good ductility and low contact resistance. When current levels exceed 20 A, conventional AgNi contact materials exhibit weaker resistance to soldering and erosion, limiting their range of application. However, by adding a small amount of additives, the electrical properties can be improved, thus expanding its application area. Some scholars have studied that adding tungsten or tungsten oxide can improve the performance of AgNi contact materials.  The W or WO 3 , which accounts for 1.5% of the total, was made into silver-nickel contacts (containing 85% of silver content) by powder mixing, isostatic pressing, sintering, extrusion, subsequent wire drawing and riveting. Each contact material was repeated 5 times using the same resistive load in the test. The current and mechanical structure ensured that all tests had comparable arcing energy with supply voltages...