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ADVANCED MATERIALS & PROCESSES •
MAY 2014
53
JTST HIGHL IGHTS
The
Journal of Thermal Spray
Technology (JTST),
the official
journal of the ASM Thermal
Spray Society, publishes contribu-
tions on all aspects—fundamental
and practical—of thermal spray
science, including processes, feed-
stock manufacture, testing, and
characterization. As the primary
vehicle for thermal spray informa-
tion transfer, its mission is to syn-
ergize the rapidly advancing thermal spray industry and related
industries by presenting research and development efforts lead-
ing to advancements in implementable engineering applica-
tions of the technology. In addition to the print publication,
JTST
is available online through
www.springerlink.com. For
more information, visit
asminternational.org/tss.Articles from
the February and April issues, as selected by
JTST
Editor-
in-Chief Christian Moreau, are highlighted here.
L
u
2
O
3
-SiO
2
-ZrO
2
Coatings for
Environmental Barrier Application by
Solution Precursor Plasma Spraying and
Influence of Precursor Chemistry
Émilien Darthout, Aurélie Quet, Nadi Braidy,
and François Gitzhofer
Environmental barrier coatings are subjected to thermal stress
in gas turbine engines introducing a secondary phase as zircon
(ZrSiO
4
). This is likely to increase the stress resistance of Lu
2
Si2O
7
coatings made by induction plasma spray
using liquid precursors. Precursor chemistry
effect is investigated synthesizing ZrO
2
-SiO
2
nanopowders using an induction plasma
nanopowder synthesis technique. Tetraethyl
orthosilicate (TEOS) as silicon precursor and
zirconium oxynitrate and zirconium ethox-
ide as zirconium precursors are mixed in
ethanol and produce a mixture of tetragonal
zirconia and amorphous silica nanoparticles.
Zirconium ethoxide uses precursor results in
zirconia particles with diameters below 50
nm because of exothermic thermal decom-
position of the ethoxide and its high boiling
point with respect to solvent, while larger
particles are formed when zirconium oxyni-
trate is employed. Coatings are synthesized
in the Lu
2
O
3
-ZrO
2
-SiO
2
system. After heat
treatment, the doping effect of lutetium on zirconia grains inhibits
zircon formation. Dense coatings are obtained using zirconium
ethoxide because denser particles with a homogeneous diameter
distribution create the coatings.
Microstructures and Dielectric Properties
of PZT Coatings Prepared by Supersonic
Plasma Spraying
Guolu Li, Linsong Gu, Haidou Wang,
Zhiguo Xing, and Lina Zhu
The microstructures and dielectric properties of PZT coatings
prepared by supersonic plasma spraying were studied. Samples
Selected area electron
diffraction pattern of
nanopowders produced
from Zr oxynitrate +TEOS
mixture (left) and Zr
ethoxide +TEOS mixture
(right). The Miller index of
tetragonal zirconia is
marked for the
corresponding rings of the
Debye Scherrer pattern.