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Alumina coating on dense tungsten powder by fluidized bed metal organic chemical vapour deposition

Rodriguez, Philippe and Caussat, Brigitte and Ablitzer, Carine and Iltis, Xavière and Brothier, Meryl Alumina coating on dense tungsten powder by fluidized bed metal organic chemical vapour deposition. (2011) Journal of Nanoscience and Nanotechnology (JNN), vol. 11 (n° 9). pp. 8063-8088. ISSN 1533-4880

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Official URL: http://dx.doi.org/10.1166/jnn.2011.5097

Abstract

In order to study the feasibility of coating very dense powders by alumina using Fluidized Bed Metal Organic Chemical Vapour Deposition (FB-MOCVD), experiments were performed on a commercial tungsten powder, 75 nanometers in median volume diameter and 19,300 kg/m3 in grain density. The first part of the work was dedicated to the experimental study of the tungsten powder fluidization using argon as carrier gas at room temperature and at 400 °C. Due to the very high density of the tungsten powder, leading to low initial fixed bed heights and low bed expansions, different weights of powder were tested in order to reach satisfactory temperature profiles along the fluidized bed. Then, using argon as a fluidized bed former and aluminium acetylacetonate Al(C5O2H7)3 as a single source precursor, alumina thin films were deposited on tungsten particles at a low temperature range (e.g., 370–420 °C) by FB-MOCVD. The influence of the weight of powder, bed temperature and run duration was studied. Characterizations of the obtained samples were performed by various techniques including scanning electron microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS) analyses, Field Emission Gun SEM (FEG-SEM) and Fourier Transform InfraRed (FT-IR) spectroscopy. The different analyses indicated that tungsten particles were uniformly coated by a continuous alumina thin film. The thickness of the film ranged between 25 and 80 nm, depending on the coating conditions. The alumina thin films were amorphous and contained carbon contamination. This latter may correspond to the adsorption of species resulting from incomplete decomposition of the precursor at so low deposition temperature

Item Type:Article
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Commissariat à l'Energie Atomique et aux énergies alternatives - CEA
French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Laboratory name:
Laboratoire de Génie Chimique - LGC (Toulouse, France) - Génie des Interfaces & Milieux Divisés (GIMD) - CVD
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Deposited By: Brigitte CAUSSAT-BONNANS

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