Abstract View
Ultrasonic Aerosolization of Powder Phase Materials to Generate High Concentration Aerosol
Rayhan Ahmed, Vikram Suresh, Li Li, RANGANATHAN GOPALAKRISHNAN, The University of Memphis
Abstract Number: 612
Working Group: Instrumentation and Methods
Abstract
A continuous supply of high concentration aerosol is needed for many aerosol-based additive manufacturing technologies. Dispersion of powder phase materials as aerosol is attractive due to its relative simplicity to solvent based techniques and lower costs. However, generation of steady high concentration aerosol from powders is challenging due to particle-particle and particle-surface adhesion forces. Building on our prior work on using ultrasonic aerosolization to disperse dry powders (Pokharel et al. (2019). Aerosol Sci. Tech. 53(3): 321-331), we describe here improvements to increase the concentration output, stability and tunability of the device. The improved ultrasonic aerosol generator is capable of generating number concentrations >107 cm-3 from commercially available TiO2 powder. Moreover, the aerosol generation method is scalable and could potentially be scaled by increasing the number of ultrasonic transducers which also increase the stability and concentration of the aerosol output. Using three ultrasonic transducers, we generate aerosol concentrations in the range of ~107 cm-3 from raw TiO2 powder of mean primary particle size ~225 nm. Milling and heat treatment of the raw powder seem to improve the dispersibility considerably. The mass concentration of particles >0.3μm is of the order of ~ 500 mg/m3. It is hypothesized that the superior dispersibility of the milled powder compared to raw powder is due to the coating of ultrafine particles on the surface of fine and coarse powder particles. The conclusions derived herein are supported with upper bound estimates of number concentration and size distribution of aerosols. Altogether, the described improvements may be used to the generation of high concentration aerosol (107 – 108 cm-3) in the size range of ~0.3 – 2 μm using off the shelf parts that may cost <$3000 to assemble.
Published as Ahmed, R., V. Suresh, L. Li and R. Gopalakrishnan (2020). "Scalable generation of high concentration aerosol in the size range of 0.1–10 μm from commercial powders using ultrasonic dispersion." Powder Technology 376: 52-59.