Method for determining particle velocity during aerosol deposition by impact pressure of the particles

Understanding coating by aerosol deposition requires knowledge of the kinetic energy of particles colliding with the substrate. In this study, the velocity of α-Al2O3 particles in a He or N2 carrier gas was derived from the maximum impact pressure on the substrate by the Rankine–Hugoniot relations, referred to as the impact-pressure method. The impact pressure distribution was measured using a pressure-sensitive film to provide the two-dimensional particle velocity. From the pressure distribution, it was found that the particle in the gas flow from the center of the nozzle and from near the edge of the nozzle have almost the same impact velocity. A correction factor was required to determine the correct impact pressure from the pressure-sensitive film. The correction factor, determined based on the Knudsen number and the measured impact pressure, was in the range between 1.9 and 4.0.