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Fluorocarbon coatings deposited on micron-sized particles by atmospheric PECVD

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Author: Abadjieva, E. · Heijden, A.E.D.M. van der · Creyghton, Y.L.M. · Ommen, J.R. van
Type:article
Date:2012
Source:Plasma Processes and Polymers, 2, 9
Identifier: 446767
doi: doi:10.1002/ppap.201100044
Keywords: Atmospheric pressure · Fuidzed bed · Fuorocarbon coating · Prticles · Plasma-enhanced chemical vapor deposition (PE-CVD) · Defence, Safety and Security · Fluid Mechanics Chemistry & Energetics · EM - Energetic Materials · TS - Technical Sciences

Abstract

Fluorocarbon coatings have been deposited on micron-sized silica particles by means of atmospheric pressure plasma-enhanced chemical vapor deposition (PECVD). The silica particles have a diameter in the range between 40 and 70 ?m. They are fluidized at atmospheric pressure in a circulating fluidized bed combined with a dielectric barrier discharge (DBD) reactor. Four coatings have been produced with four different precursors, respectively, octafluorocyclobutane (C 4F 8), hexafluoropropylene (C 3F 6), trifluorethanol (C 2H 3OF 3) and hexafluoro-2-propanol (C 3H 2OF 6). The Ar filamentary discharges are sustained with a plasma power of 150 W at 25 kHz. The chemical and morphological features of the coatings are investigated by means of scanning electron microscopy (SEM), X-ray microanalysis, and X-ray photoelectron spectroscopy (XPS). All coatings have a flake-like morphology and variable thickness. The F/C ratio, also called "Teflon" parameter, has the following values: 1.37, 1.09, 0.30 and 1.45 for each of the four precursors, respectively. The coating produced with trifluorethanol is highly cross-linked, but has relatively poor fluorinated surface. The highest surface fluorination is achieved, when octafluorocyclobutane is used as a precursor. The presented results enable the comparison and selection of precursors, so that particle surface functionality may be developed for improved blast performance and sensitivity of advanced energetic materials. The XPS C 1s peak of the coating deposited in filamentary Ar/C 3F 6 discharge can be fitted with five peaks. The chemical nature of the coating is characterized by nearly equal contribution of the CF, CF 2 and CF 3 bonds. The F/C ratio, also called Teflon character, is 1.09. The coating, with a thickness up to few microns, is deposited on micron-sized particles using PECVD in a fluidized bed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.