The effect of gas phase polydimethylsiloxane surface treatment of metallic aluminum particles: Surface characterization and flow behavior--颗粒学报PARTICUOLOGY

Ludwig, B., & Gray, J. L. (2017). The effect of gas phase polydimethylsiloxane surface treatment of metallic aluminum particles: Surface characterization and flow behavior. Particuology, 30, 92-101. https://doi.org/10.1016/j.partic.2016.05.010

The effect of gas phase polydimethylsiloxane surface treatment of metallic aluminum particles: Surface characterization and flow behavior

Bellamarie Ludwig ^a *, Jennifer L. Gray ^b

a Applied Research Laboratory, The Pennsylvania State University, North Atherton Street, State College, PA 16801, USA
b Materials Research Institute, The Pennsylvania State University, USA

10.1016/j.partic.2016.05.010

Volume 30, February 2017, Pages 92-101

Received 23 March 2016, Revised 3 May 2016, Accepted 18 May 2016, Available online 22 September 2016, Version of Record 27 January 2017.

E-mail: bxb234@psu.edu

Highlights

• Polydimethylsiloxane was successfully deposited on metallic aluminum particles.

• Improved flow properties were observed through reduced cohesion.

• Fluidization behavior was improved as shown through aeration testing.

Abstract

Aluminum particles were exposed to gaseous polydimethylsiloxane (PDMS) to produce a hydrophobic surface coating for enhanced flow and fluidity. Surface retention of the intact PDMS was confirmed through infrared and X-ray photoelectron spectroscopy. Transmission electron microscopy was used to image cross-sections of the treated particles and energy dispersive spectroscopy element maps demonstrated the presence of a surface layer consisting of silicon and oxygen. Density measurements provided evidence for improvements in the Hausner ratio and Carr index of the PDMS-treated aluminum, indicating a reduction in inter-particulate cohesion through increased bulk density. Stability, compressibility, shear, aeration, and permeability of the particles were assessed by powder rheometer. The compressibility was reduced by approximately 32% following surface treatment, revealing a reduction in void space, while Mohr’s circle analysis and shear testing determined that the extrapolated cohesion value was reduced by approximately 53% and the flow factor at 6 kPa was doubled. Aeration testing showed that the air velocity required to obtain a fluidized bed was on the order of 0.35 mm/s for the treated powder, whereas the raw powder could not be uniformly fluidized. PDMS may be a viable option for the large-scale treatment of aluminum powder for flow applications.

Graphical abstract

Keywords

Aluminum powder; Polydimethylsiloxane; X-ray photoelectron spectroscopy; Diffuse reflectance infrared Fourier transform spectroscopy; Flowability; FT4 powder rheometer

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