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November 13-14, 2017 Paris, France
5th International Conference on
PLASMA CHEMISTRY AND
PLASMA PROCESSING
Journal of Biotechnology and Phytochemistry
Volume 1, Issue 2 Plasma Chemistry 2017
Inductively coupled thermal plasma - a versatile tool
for the processing of powders
Marc Leparoux
Empa - Swiss Federal Laboratories for Materials Science and Technology,
Switzerland
Among the thermal plasmas, the inductively coupled ones
present the advantage of large vol-ume and moderate
velocity making this technique well suitable for the controlled
evaporation or melting of large quantities of particulate materials.
Thus, ICP is industrially used for the synthesis of nanoparticles,
or for the spheroidisation and densification of microscale
powders. The nanoparticle synthesis involves the formation of
a supersaturated phase and its subsequent rapid condensation.
A high flexibility is provided by this technique regarding the
feedstock. A most common production route is the evaporation
of commercially available and easy to handle microscale particles,
but liquid and even gases can also be used as starting materials.
The control of the thermal history of these precursors is of prime
importance for guaranteeing the quality of the product. Indeed,
strong temperature gradients in the plasma may lead to different
evaporation rates, particle sizes or even different compositions.
An in-situ diagnostic is then required for understanding and
controlling the process. Due to the dusty and high-temperature
environment, optical techniques are an interesting approach
giving valuable information about the plasma state, the
particle-plasma interaction and even about some na-noparticle
properties. Additionally, the injection of a secondary material
allows the function-alization of the produced nanoparticles in-
situ and in-flight offer new potentials for ICP pro-cessing. More
recently the fast growing of additive manufacturing induced a
specific interest in powder spheroidisation for making powders
more flowable. Indeed, in the powder bed ap-proach, a powder
layer is deposited before the laser or the electron beam is writing
a structure. A defect in the powder layer arrangement may induce
a defect in the additive manufactured the part. Therefore, highly
flowable powders are required. By adapting the inductive plasma
process parameters, a full melting of the starting powder without
extensive evaporation can be achieved. The melt particles form
then dense spheres with improved flowability upon cooling.
Empa is investigating thermal plasmas and especially ICP since
more than 15 years. A short review of the activities will be
presented here.
Biography
Marc Leparoux is head of the group of nanoparticles and nanocomposites
at the laboratory for advanced materials processing at Empa. He received
his Magistère in materials science and a DEA in solid chemistry in 1992 at
University of Rennes. He completed his PhD in physical chemistry in 1995
from University of Orléans in France. He then worked on high temperature
process monitoring at Fraunhofer institute for material and beam technology
(IWS) in Dresden, Germany. He joined Empa in 2001 where he developed
the activities on thermal plasma synthesis of nanoparticles. Particularly, his
interest is in gas phase process un-derstanding and improvement based on
in-situ characterization using various optical methods, among them emission
and absorption spectroscopy as well as high speed imaging. These techniques
are presently also used in other plasma induced processes as for instance in
laser metal welding and more recently in laser metal deposition an additive
manufacturing process.
Marc Leparoux, J Biot Phyt 2017