Effect of interparticle forces on the coagulation of ultrafine SiO2 particles

The mechanism of ultrafine (<100 nm) SiO₂ particle production under thermal arc plasma conditions is studied by modelling. Two cases of the process are considered in the model: (i) when it is determined as a pure free-molecular coagulation; (ii) when the coagulation is influenced by the interparticle forces. The Hamaker formula is used to present the van der Waals forces between the particles. Particle size distribution functions (PSDF) are calculated for both cases. It is shown that inclusion of the interparticle interactions does not affect the self-preservation of the PSDF. The mean particle sizes are obtained from the PSDF and compared. Higher values are observed in the case that includes van der Waals forces. Comparison between experimental and calculated PSDF shows better agreement in the case considering interparticle forces.