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RESEARCH SPOTLIGHT
deformation of thin substrates, e.g., compressive stresses of
400 MPa were measured in 1-mm-thick 304L substrate after
grit-blasting[3]. Thus, the technique could not be used for this
application if the shape of the parts to be covered cannot be
altered. Three plasma technologies could be used to depos-
it the ceramic coating—conventional atmospheric plasma
spraying (APS) using powder, suspension plasma spraying
(SPS), and solution plasma spraying.
APS spraying of the 0.5-mm-thick ceramic coating on
the as-received substrate after solvent cleaning to remove
potential surface contaminants made it impossible to form a
coating with good adhesion to the substrate, regardless of the
spraying conditions and temperature of the substrate. Also,
deposition of a 0.5-mm-thick ceramic coating by suspension
spraying took too long. Therefore, to circumvent this adhesion
problem, a specific procedure had to be developed. Thismeth-
od consists of deposition of a duplex thermal barrier coating
made of (i) a thin layer of yttria-stabilized zirconia (YSZ) by SPS
on the as-received and cleaned alloy and (ii) a thick layer of
YSZ by conventional APS. The SPS layer creates an increased
surface area for mechanical bonding of the APS coating and
provides the adhesion of the duplex coating to the Haynes
230 alloy. iTSSe
For more information: Armelle Vardelle is a professor at the
University of Limoges, France, . Por-
tions of this article have been adapted from a full length feature
in the Journal of Thermal Spray Technology 21 (2012): 1128-
1134, DOI 10.1007/s11666-012-9798-2. © ASM International.
References
1. A Technology Roadmap for Generation IV Nuclear Energy
Systems, US DOE Nuclear Energy Research Advisory Com-
mittee and the Generation IV International Forum, Decem-
ber 2002.
2. R. Stainsby, et al., Gas Cooled Fast Reactor Research and
Development in the European Union, Sci. Technol. Nucl.
Install., Article ID 238624, 2009.
3. H. Liao, et al., Determination of Residual Stress Distribu-
tion from In Situ Curvature Measurements for Thermally
Sprayed WC-Co Coatings, J. Therm. Spray Technol., Vol 6(2),
p 235-241, 1997.
High-resolution TEM image of the ceramic/metal interface.
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