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This paper evaluated the break-up and bounce of iron oxides and copper agglomerates during inertial impaction. The results were compared with data acquired earlier with TiO 2 agglomerates. It was found that the total mass-based bounce fraction of the iron oxide agglomerates did not increase monotonically with the impaction velocity. The reason behind this appeared to be the transition from non-fragmentation to fragmentation as the impaction velocity increased. The copper agglomerates were found to de-agglomerate but not bounce in these experiments. Different impaction surface materials were also examined to determine their effect on the impaction process, but only small variations were found in the bounce fractions or the size of the particles after bounce and deagglomeration.

Monodisperse, fine aerosols are needed in many applications: filter testing, experiments for testing models, and aerosol instrument calibration, among others. Usually, monodisperse fine aerosols are generated in very low concentrations, or mass flow rates, in the laboratory scale. In this work, we needed to generate aerosols with higher mass flow rate than typically available by the laboratory-scale methods, such as atomizers, nebulizers, ultrasonic generators, vibrating orifice generators, and condensation generators. Therefore, we constructed a fluidized bed aerosol generator to achieve particle mass flow rates in the range of 15–100 g/h. Monodisperse, spherical SiO2 particles of two sizes with geometrical diameters of 1.0 and 2.6 µm were used in the aerosol generator. The aerosol generator was used at both atmospheric pressure, and at high pressures up to 5 bar (abs). The particle size, mass concentration and the net average particle charge were measured after mixing the aerosol with nitrogen. The particle size distributions with both particle sizes were monodisperse, and no particle agglomerates were entrained from the fluidized bed. The behavior of the fluidized bed generator was found to be markedly different with the two particle sizes in regard to particle concentration, presumably due to different particle charging inside the generator. After determining the net average charge of the particles, an ion source Kr-85 was used to reduce the charge of the particles. This was found to be effective in neutralizing the particles.