Direct silicon nitride preparing fluidized bed apparatus and process

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.