Tungsten Oxide

  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 ...

  With the development of high and new technology, the requirement of pure tungsten and its alloy material is higher and higher. There are many methods to prepare   tungsten powder , and spray drying is one of the most important methods. The spray drying method or chemical synthesis method, it is a method of physical and chemical solution atomization obtain ultrafine particles through physical means of combining the process, including the original solution was prepared with solution blending, mixing, spray drying and subsequent processing.  In recent years, the influence of nozzle structure, spray drying speed and temperature on particle size has attracted extensive attention. It is found that the concentration of precursor solution plays an important role in the morphology and particle size of ultrafine tungsten powder during ultrasonic spray drying. In order to prove this theory, some scholars have used 2 different concentrations of ammonium tungstate solution to spray ...

Ultrafine tungsten powder is superior to common coarse grain material in mechanical, therefore, the mechanical properties, physical properties and chemical properties are better than those of ordinary coarse-grained materials.  However, the preparation of ultrafine tungsten powder is more stringent than ordinary tungsten powder, not only have better quality raw materials, but also more suitable methods and equipment are required. Since 1950s, a great deal of research work has been done on tungsten smelting industry both at home and abroad, and many years of systematic research have been carried out on the preparation of ultrafine tungsten powder, and some effective methods have been developed. Hydrogen reduction is the main method of preparing ultrafine tungsten powder. It is simple, advanced, reasonable, stable and reliable, low cost and so on. With the development of tungsten powder manufacturing, great progress has been made in the selection of tungsten oxide ...

Hydrogen reduction is the main method for preparing ultrafine tungsten powder. It is a rather complicated physical and chemical process, including chemical transformation, phase change process, solid phase diffusion and chemical vapor transfer. In W-O-H there are 6 solidification phase, which are: tungsten trioxide (WO 3 ), beta tungsten oxide (WO 2.9 , W 20 O 58 , blue tungsten) gamma tungsten oxide (WO 2.72 , W 18 O 49 , Purple Tungsten) two tungsten oxide (WO 2 ), -W alpha and beta -W. Therefore, the process of hydrogen reduction reaction of tungsten oxide is complex, and different reduction processes will occur with the change of temperature and humidity: In a high temperature and a humid reducing atmosphere, the reduction proceeds in distinct stages ( WO 3  → WO 2.9  → WO 2.72  → WO 2 → W ); In low temperature and dry hydrogen, it is possible to reduce tungsten oxide to tungsten powder directly from high valence tungsten oxide ( WO 2...

The hydrogen reduction process of tungsten oxide, is a very complex physical and chemical processes, including chemical conversion, phase transformation, solid diffusion and so on. The process generally is: tungsten oxide, hydrogen reduction, sifting, blending, tungsten powder. Different tungsten oxide reduction process of reaction pathways, the reaction speed is different, in general, the reduction reaction pathway and to avoid the simple single reaction generated in the process of WO 2  is beneficial to preparing fine tungsten powder uniformly. That is to say, the tungsten powder obtained by route WO 2.9  → W or WO 2.72  → W would be more satisfactory. Hydrogen reduction of tungsten oxide is usually carried out in a multiple tube furnace or a rotary furnace. Multiple tube reduction furnace has 3 to 5 containers used for loading, use artificial way in accordance with the order of loading and unloading material, excessive hydrogen or against the tungst...

In an inert gas of a certain pressure (<1.013x10--5Pa), it is heated by resistance, laser heating, electron heating, arc heating, high-frequency heating, etc.  This method is the most effective way to prepare ultrafine particles with a particle size less than 100nm by melting and evaporating materials and condensing them into ultrafine particles. Gas evaporation was first proposed by the Japanese in 1963. In the process of studying the process of preparing nanometer tungsten powder by gas evaporation, Chinese scholars evacuated the vacuum chamber to 2.5 * 10 - 5Pa and filled the high-purity argon with purity of 99.99% to 100~500Pa, heating to make the purity of 99. 9%, diameter of 1mm tungsten wire evaporation. The vaporized gas atoms, W, collide with an inert gas atom, lose energy, agglomerate into nanometer sized clusters, and then condense in a sample grid cooled by liquid nitrogen. The nano tungsten powder structure as the body centered cu...

High energy ball milling method is used in low temperature, in the protective atmosphere, by using the rotation or vibration of the ball mill. The hard sphere is subjected to strong impact, grinding and stirring, and the metal is crushed into nanometer particles. At present, high energy ball milling mainly uses vibrating ball mill, planetary ball mill and stirred ball mill to prepare nanometer powder. In the nano structure formation mechanism study, that high energy ball milling is a process in which the particle circulation shear deformation, in this process, a large number of lattice defects ever produced within the great grain particles, leading to the re-combination of particles in the grain boundary. In the system of cells, the formation of nanocrystals is only the evolution of structures under mechanical driving. In the multivariate system, low temperature solid state reaction components will occurred during ball milling grinding, crushing, col...

The hydrogen reduction method of tungsten oxide , is a very complex physical and chemical processes, including chemical conversion, phase transformation, solid diffusion and so on. The process generally is: tungsten oxide, hydrogen reduction, sifting, blending, tungsten powder. The reaction pathway of tungsten oxide reduction process is different, and the reaction rate is different. However, in order to obtain the best indicators, WO 2  should be avoided in the reaction process to achieve the direct reduction of ultrafine tungsten powder from blue tungsten or purple tungsten. Although the quality of blue tungsten or purple tungsten is very important, other details should not be neglected. The key to obtain the desired effect is to master the key parameters such as temperature, humidity, operation and impurities. 1. Temperature is the key factor to determine the preparation of ultrafine tungsten powder. The production has proved that, when the temperature is...

Plasma is considered to be the fourth basic form of solid, liquid, gas and other substances.  It is a collection of charged particles and neutral particles that are freely moving and interact with each other. Macroscopically, it is electrically neutral. When there is enough energy added to the gas, the gas molecules and high-energy electrons will occur between the collision or absorption of electromagnetic control and ionization process occurred, and then the formation of plasma state. The basic principle of plasma preparation of ultrafine tungsten powder is in an inert atmosphere or reactive atmosphere, the DC discharge (or otherwise) to produce high temperature gas ionization plasma, so that the molten metal evaporation, metal vapor, quenching or chemical reaction to form ultrafine particles. At present, the main methods to obtain plasma are thermal ionization method, shock wave method, photoionization method, ray radiation method, and DC, low-frequency, radio fr...

Tungsten powder is the main raw material for processing powder metallurgy tungsten products and tungsten alloys. With the rapid development of science and technology and extensive and deep research on nanometer technology, ultrafine tungsten powder has been developed and applied widely. Ultrafine tungsten powder in the field of materials, through nanoparticles and a variety of ultra-fine structural modules, led to the emergence of many new materials with excellent properties and new applications. Ultrafine tungsten powder is superior to common coarse grain material in mechanical, physical and chemical properties because of its ultrafine grain and large amount of atoms on the grain boundary. Ultrafine tungsten powder can be divided into three grades according to particle size: submicron tungsten powder (<1 um), ultrafine tungsten powder (<0.5 um) and nano tungsten powder (<100 nm). The most widely used tungsten powder is nanometer grade tungsten powder. U...