Tungsten Oxide

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 in 10% HCl (excess 3

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 cubic (B.C.C) structure an

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, cold welding effect an

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 greater than