Apparatus for direct preparing silicon nitride by fluidized bed and process

Abstract

The present invention is fluidized bed apparatus and process for preparing silicon nitride directly. The fluidized bed has the features of strong gas-solid reaction, high heat transfer and mass transfer effect and homogeneous temperature. In a high temperature fluidized bed at 1000-1650 deg.c, silicon powder is nitrided directly to produce silicon nitride powder. The reacted silicon powder of diameter before sintering smaller than 10 micron and average diameter after sintering in 300-500 micron is fed to the fluidized bed directly. The fluidized bed gas consists of nitrogen in 10-100 vol%, hydrogen in 0-60 vol% and Ar in the balanced amount. The silicon powder fluidizing bed is fluidized in sound forced mode. The present invention can produce homogeneous silicon nitride powder of high quality in high efficiency, and has wide industrial application foreground.

Description

technical field [0001] The invention relates to an inorganic non-metallic powder material preparation device and a method thereof, in particular to a device and a method for directly preparing silicon nitride in a fluidized bed. Background technique [0002] Silicon nitride has excellent high-temperature mechanical properties and is the material of choice for manufacturing high-temperature components. The excellent performance of silicon nitride has special use value for the working environment of high temperature, high speed, strong corrosive medium and high wear often encountered in modern technology. Its outstanding advantages include high mechanical strength, good thermal stability, good thermal shock resistance and stable chemical properties. Silicon nitride has a wide range of industrial applications, and can be used in metallurgy, machinery, energy, chemical industry, semiconductor, aerospace, automobile industry, nuclear power engineering and medical engineering. It...

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Problems solved by technology

[0009] "Method for Synthesizing Silicon Nitride Powder by Normal Pressure Combustion" (Chinese Patent Publication No. CN 1657404A) invented by Li Jiangtao, Institute of Physical and Chemical Technology, Chinese Academy of Sciences, puts silicon powder, catalyst and silicon nitride powder into a high temperature resistant reactor for reaction The continuous generation of silicon nitride is complicated in actual operation. At the same time, it is roughly mentioned in the patent that continuous nitriding can be achieved through the high-temperature field of the suspension calciner in a fluidized manner. The nitriding reaction in the chemical bed is different

This method does not explain how to realize the fluidization process, whether it is fluidized at room temperature or at high temperature, and how to realize the continuous feeding process.

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