Spherical Silicon Nitride Powder via Fluidized Bed Mixing

The patent replaces conventional mechanical ball milling with a fluidized bed mixing system. Silicon dioxide powder and carbon black are introduced into a fluidized bed where they are uniformly mixed by gas flow, eliminating the need for complex mechanical milling equipment while achieving superior mixing uniformity. This substitution resolves the contradiction by using a simpler fluid dynamic system instead of complex mechanical systems.

The patent changes the physical state parameters of the mixing process by using fluidized bed technology. The gas flow rate, particle size distribution, and temperature are optimized to achieve complete fluidization and uniform mixing. By controlling these parameters, the system achieves excellent mixing uniformity without requiring complex mechanical intervention, thus resolving the contradiction between mixing precision and process complexity.

The patent performs preliminary uniform mixing of silicon dioxide powder and carbon black in a fluidized bed before the carbothermal reduction process. This preliminary action ensures that all silicon dioxide particles are evenly coated with carbon black, preventing incomplete nitridation and oxygen incorporation during subsequent heating. By addressing the mixing issue beforehand, the patent achieves high powder purity without requiring complex process modifications, thus resolving the contradiction between purity and manufacturing ease.

The fluidized bed acts as an intermediary system that facilitates uniform distribution of carbon black on silicon dioxide particles. This intermediary mixing step ensures proper contact between reactants before the main reduction process, preventing unwanted side reactions that would increase oxygen content. The intermediary action resolves the contradiction by enabling complete nitridation while maintaining process simplicity.

The patent combines the mixing and granulation processes into a single fluidized bed operation. As silicon dioxide powder and carbon black are mixed in the fluidized bed, the gas flow and particle collisions naturally form spherical granules. This merging of operations achieves both uniform mixing and spherical morphology without requiring separate granulation equipment, thus resolving the contradiction between powder fluidity and process complexity.

The fluidized bed system allows particles to self-organize into spherical shapes through gas flow patterns and particle collisions. The system uses the kinetic energy of fluidized particles to naturally form spheres without external intervention or complex shaping equipment. This self-service mechanism achieves excellent powder fluidity and bulk compactness while keeping the process simple, resolving the contradiction between operational ease and device complexity.