SiO₂ Particle Deposition on KCl Initial Deposit Layers

This study presents experiments investigating the influence of an initial layer on particle sticking probability, proving that an initial layer can initiate and enhance the sticking probability of incoming particles. The findings reveal that the deposition of SiO₂ particles is influenced by both the deposit probe temperature (350 and 500 °C) and the morphology of the KCl initial layer. The KCl initial layer is composed of two types of morphology─a fine powdery layer made of submicron particles and a coarse layer made of crystal-like dendrites. The formation of the coarse layer is promoted by a longer KCl exposure time and a higher probe temperature. For thin initial layers with a large powdery fraction, higher probe temperatures during SiO₂ deposition result in a larger amount of deposit, highlighting the significant role of probe temperature in this phase. Additionally, the probe temperature during the KCl initial layer formation affects the deposition behavior, with higher temperatures reducing the deposit mass. Conversely, for thicker initial layers with a higher fraction of crystal-like dendrites, the probe temperature during the KCl initial layer generation becomes more critical, with higher temperatures leading to decreased SiO₂ deposits. The complexity of the deposition process, even in a simple two-component system, is attributed to multiple relevant phenomena, including the softening and melting of the initial layer, sintering, and the energy dissipation potential of the different structures in an initial layer.