Understanding the effect of surface topography on the formation of aerosol-deposited coatings

Aerosol deposition (AD) has attracted attention in the ceramic coating field as it can produce dense nanocrystalline ceramic films at room temperature. Research in the AD field has focused on coating formation on flat surfaces, with limited exploration of deposition on patterned substrates. In this work, we describe the microstructure of a dense alumina coating deposited by AD on micropillar-patterned silicon substrates through SEM and TEM analyses. To understand the coating formation mechanism on the micro-patterned substrate, interfacial analysis has been performed using high-resolution TEM. Pressure-induced amorphous Si regions are observed at the coating-substrate interfaces, indicating severe particle impacts during deposition that contribute to the strong adhesive bonding in AD. The interfaces at different locations, including the peaks, sidewalls, and valleys of the pillars, showed distinct characteristics that demonstrated how substrate topography in AD affected interfacial bonding and particle impact behaviors. • Alumina films were fabricated on patterned Si substrates by aerosol deposition. • The coatings deposited between the pillars show high density without microcracks. • Thick amorphous Si layer is seen at coating-substrate interfaces near pillar peaks. • The particle impact behaviours are explained through HRTEM analysis.