Preparation Of Tungsten Oxide Hydrate Material

Liquid crystals prepared as in ancient China's oldest crystal preparation, ancient people extracted salt from seawater process is instantiated crystal growth under conditions of liquid system. Production practice long time, and now liquid phase has been subdivided into a number of specific technical solutions use different types of crystal growth, and these technologies are still constantly evolving. Hydrothermal process is carried in an aqueous system, by changing the solubility of the crystal, the crystal growth system for liquid phase growth method.

(1) Reaction conditions: hydrothermal method commonly used water is mixed with other salts forming solvent (or become a mineralizer), and therefore during the reaction, such a system can be difficult to dissolve the material at ambient conditions (high melting point oxides, etc.) to improve their solubility, to promote the reaction under the reaction conditions usually higher at relatively mild conditions.

(2) the reaction environment: Hydrothermal reaction is controlled during the growth process of the crystal particles by controlling the reaction temperature and pressure. The growth process is usually carried out in a closed system environment, the. The closed environment is often used to maintain the autoclave, due to higher temperature, higher pressure such that the reaction system is very corrosive to steel to material, so more memory polytetrafluoroethylene material as the reactor lining material.

(3) reaction: with various other liquid phase method, a hydrothermal reaction process, the reactor is generally vertically disposed, and therefore part of the kettle liquid and vapor phases due to the presence of vertical temperature gradient distribution. The temperature gradient causes the liquid and gas phases inside the reactor intense convection occurs in the course of the reaction, the liquid moved by the high-temperature region to migrate to lower temperature, and phase transition accompanied by changes in local excessive solution saturation at low temperature District because the solution becomes supersaturated solute precipitates to form a precipitate, gasified liquid back into a cold solution of the liquid phase, repeated cycles of convection, the solute precipitates will eventually grow to form crystals.

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