46 results about "Elemental chlorine free" patented technology

According to the SiC polycrystal powder and the preparation method and device, the gaseous carbon source and the gaseous silicon source which do not contain chlorine serve as the unique carbon source and the unique silicon source, and introduction of the chlorine element is completely eradicated from the source; by accurately controlling the temperature gradient, the gas ratio and the flow velocity of the high-temperature pyrolysis zone and the sub-high-temperature reaction zone, the gaseous carbon source and the gaseous silicon source are subjected to instantaneous thermal decomposition to form pyrolysis mixed gas containing active silicon, carbon atoms and free radicals, and then nucleation and growth are carried out in a thermodynamically stable hexagonal crystal phase under the condition of no solid carrier to form SiC polycrystal powder. In the application, the reaction byproducts are only hydrogen, unreacted carrier gas and trace undecomposed gaseous carbon source and gaseous silicon source, and do not contain HCl, tar or toxic chlorosilane, and the tail gas can be directly discharged or simply recovered, so that the environment-friendly treatment cost is greatly reduced. The preparation method is clean, high in efficiency, high in product purity, single in crystal phase and suitable for large-scale preparation of the high-quality hexagonal crystal phase SiC powder.