Relationship between impact velocity of Al₂O₃ particles and deposition efficiency in aerosol deposition method

Aerosol deposition method (ADM) is a technique to form dense films by impacting solid particles to a substrate at room temperature. To improve the deposition efficiency in ADM, the relationship between the impact velocity of Al₂O₃ particles and the deposition efficiency was investigated in this study. Relative difference in impact particle velocity was evaluated by the increment percentage of the substrate surface area after deposition (ΔS). It is thought that the increase of ΔS means the increase of the impact particle velocity. When ΔS was lower than 10 %, the deposition efficiency increased from 0.082 to 0.104 % as ΔS increased from 3.46 to 9.25 %. Increasing impact particle velocity could promote the bonding between the particles themselves. On the other hand, when ΔS was higher than 10 %, the erosion of the film was observed and the deposition efficiency decreased to about 0.02 % as ΔS increased to about 40 %. SEM observation revealed that cracks parallel to the film surface were propagated. There is a possibility that this tendency of the deposition efficiency toward the impact particle velocity is common among the methods for forming ceramic films by impacting solid ceramic particles.