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JTST HIGHL IGHTS
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ADVANCED MATERIALS & PROCESSES •
NOVEMBER-DECEMBER 2014
62
and the appearance of coating spallation. Residual stress, thermal
stress, and oxidation of substrate near the substrate/metal layer in-
terface caused coating failure, while oxidation of the substrate near
the substrate/coating interface was the dominant one.
“La
2
Zr
2
O
7
(LZ) Coatings by Liquid
Feedstock Plasma Spraying: The Role of
Precursors”
William Duarte, Sylvie Rossignol, and Michel Vardelle
Solution precursor plasma spray (SPPS) is used to obtain
finely structured coatings from metallic salt solutions. Lan-
thanum and zirconium precursors were studied to understand
their influence on lanthanum zirconate (La
2
Zr
2
O
7
) synthesis by
SPPS. Thermal analysis reveals the nature of the precursor and
solvent affects mixture decomposition by changing the decompo-
sition temperature. The surface tensions of precursor solutions
in various media reveal the influence of the nature of the counter-
cation. Different solutions of precursor mixtures were used to
obtain La
2
Zr
2
O
7
splats on metallic substrates. A decrease in so-
lution surface tension led to an increase in splat size. Coating
mechanisms by SPPS are governed by the nature of the precur-
sors and solvents.
Typical cross-sectional microstructure (a) and corresponding
backscattered image of coating Z20Y125 (b); EDS line scanning
results of the cross-section of the coating (c, d).
Splats obtained by solution precursor plasma spray from
ZrCl-LaNH (a) and ZrCl-LaNEt (27.8 g/L) (b).