Research And Application Of Controlling Formation Of Dielectric Particle Chains In Non-uniform Electric Field

In gas-solid two-phase system, dielectric particles would aggregate together under external electric field. For electrostatic collection, fine particles mainly aggregates into coarse clusters to be collected easily and some forms chain structures which prove that the formation of particle chain control is feasible. There will be important applications if the particles can be controlled to form chain aggregation.This article mainly studied of the aggregation morphology of dielectric particle in non-uniform electric field based on gas-solid two-phase system. Meanwhile, the formation and deposition of particle chains in electrostatic field were analyzed and discussed. Also, we conducted applied some research and presented a new processing approach for the fabrication of porous ceramic membrane three-dimensional network structure.Firstly, this article provided in-depth study related with the particle chain formation mechanism. By comparing different methods for electric field around dielectric particles, we found the coupled dipoles method would cause significant errors. So we had to employ re-expansion method to calculate the electric field and potential distribution of two spherical particles and three spherical particles system. Results showed that the electric field and electric potential distribution of polarized particles were similar to that of dipoles. Also, the electric field strength increased in particle binding sites which promoted the formation of particle chains.Furthermore, in order to provide the sources of particles in experiments, we designed a particle dispersion system. The liquid bridge force between particles was destroyed by using drying method and the van der Waals force was eliminated by high speed Nitrogen flow. Also the electrostatic force was removed by static eliminator. Then, the particles were fully dispersed.Moreover, experiments were carried out to research the formation condition of dielectric particle chains. Experimental results demonstrated that the existence of dipole and non-uniform gradient field was the necessary formation condition of dielectric particle chains. Due to combined effects of the external non-uniform field without free charge and the local non-uniform field of dipoles, dielectric particles would aggregate into chains. The deposition structure of particle chains was dependent upon the electric field strength. The strength of electric field was greater, the structure was more compact.At the same time, porous ceramic membrane was prepared by sintering Al2O3 fine powders which aggregated into chain structures. Due to non-uniform electric field, the dispersed adjacent particles in gas phase aggregated to particle chains, deposited on the substrate surface and formed three-dimensional network structure of porous adhesion layer. After sintering, particle chains became into tiny ceramic fibers which constituted porous ceramic membranes on the substrate surface.At last, the electrostatic field of electrostatic deposition space was analyzed by using Ansoft Maxwell electrostatic field analysis module. Vector distribution of electric potential and electric filed intensity of deposition space was simulated; meanwhile the variation rule of the distribution was described in this article. That provided an effective analytical approach for further exploring the particle chains deposition mechanisms in different types of deposition space.