Tungsten Oxide

Tungsten oxide hydrogen reduction process is generally carried out in a multiple tube furnace, in the tubular reduction furnace, the most used in China are the thirteen tube reduction furnace and the four tube reduction furnace. Four tube reduction furnace is commonly used as a tungsten oxide hydrogen reduction unit, the furnace shell is welded by ordinary steel plates, and the four tubes are placed at the same level on the same hearth. Compared with the old four tube muffle furnace up and down the structure, the temperature uniformity is much better. The automation level of the four tube reduction furnace is higher than the thirteen tube reduction furnace, and it is easier to realize mechanization and electrification, in addition, the capacity of the four tube reduction furnace is large, but the unit energy consumption is lower than the thirteen tube reduction furnace. The furnace temperature of the four tube reduction furnace is between 600 °C and 1000 °C centigra...

Self Propagating High Temperature Synthesis (SHS) is a new technology which uses the high reaction heat produced between reactants and synthesis of materials in a short time. In 1967, Soviet scientists began to study the SHS technology system and apply it to industry. Self propagating high temperature synthesis is the reaction with certain gases in vacuum or filled (N 2 , H 2 , Ar 2  etc.) combustion reaction container, then the combustion products were crushed and grinded by different specifications of powder technology. The technological process is as follows: material preparation, briquetting, preheating, ignition, self propagating, high temperature synthesis, mechanical fragmentation, product performance test. The process of preparing tungsten powder by SHS is carried out in a home-made reactor and argon atmosphere, and tungsten filament parallel to the surface of the sample is used as the ignition source. After combustion, the product was soaked i...

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...

The thermal degradation method is a process for the preparation of ammonium metatungstate based on ammonium paratungstate (APT). This method is also the mainstream process of preparing ammonium metatungstate (AMT). At present, China's industrial use of pyrolysis equipment is mainly rotary calciner, at the same time, there are a number of applications in other countries for AMT patented pyrolysis equipment, microwave heating furnace is one of them. Because the microwave energy level is close to the vibrational level of the water molecule, the hydrous material can dehydrate rapidly under the microwave field, which is also the working principle of the microwave heating furnace. Microwave heating furnace operating characteristics are: 1. Uniform and fast, which is the main characteristics of microwave drying. As the microwave has a large penetration capacity, heating can be generated directly within the medium heat, and the drying speed; 2. Selective, microwave heating...