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TSS
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JTST
HIGHLIGHTS
The
Journal of Thermal Spray Technol-
ogy (JTST),
the official journal of the ASM
Thermal Spray Society, publishes con-
tributions on all aspects—fundamental
and practical—of thermal spray science,
including processes, feedstock manufac-
ture, testing, and characterization. As the
primary vehicle for thermal spray infor-
mation transfer, its mission is to syner-
gize the rapidly advancing thermal spray industry and related
industries by presenting research and development efforts
leading to advancements in implementable engineering appli-
cations of the technology. Articles from the June and August
issues, as selected by
JTST
Editor-in-Chief Armelle Vardelle, are
highlighted here. In addition to the print publication,
JTST
is
available online through springerlink.com. For more informa-
tion, please visit asminternational.org/tss.
NANOSTRUCTUREDANDCONVENTIONAL CR
2
O
3
,
TIO
2
, AND TIO
2
-CR
2
O
3
THERMAL-SPRAYED
COATINGS FOR METAL-SEATED BALL VALVE
APPLICATIONS IN HYDROMETALLURGY
Luc Vernhes, Craig Bekins, Nicolas Lourdel, Dominique
Poirier, Rogerio S. Lima, Duanjie Li, and Jolanta E.
Klemberg-Sapieha
Velan, an international industrial valve designer and
manufacturer, in collaboration with the National Research
Council of Canada, Boucherville, and Polytechnique Montréal
conducted a detailed characterization project to assess the
mechanical and tribological resistances of promising ceramic
coatings for hydrometallurgy applications, including a novel
n
-TiO
2
-Cr
2
O
3
blend. Hardness and shear strength were deter-
mined using microhardness indentation testers and univer-
sal tensile test equipment. Wear resistance of the coatings
under sliding wear, abrasion, and galling conditions were
measured by standard pin-on-disk tests, abrasion tests,
and custom-designed galling tests. The main result is that the
synergy between Cr
2
O
3
and
n
-TiO
2
produces abrasion perfor-
mance exceeding that of the materials alone. An optimized
balance between the hard and brittle Cr
2
O
3
phases and the
soft and ductile
n
-TiO
2
phases results in higher abrasion, slid-
ing, and galling resistance. The novel
n
-TiO
2
-Cr
2
O
3
blend is a
promising evolution of the current TiO
2
-Cr
2
O
3
blend.
A REVIEW OF THERMAL SPRAY METALLIZATION
OF POLYMER-BASED STRUCTURES
R. Gonzalez, H. Ashrafizadeh, A. Lopera, P. Mertiny,
and A. McDonald
A literature review on the thermal spray deposition of
metals onto polymer-based structures is presented. Deposit-
ing metals onto polymer-based structures enhances the ther-
mal and electrical properties of the resulting metal-polymer
material system. Thermal spray metallization processes and
the technologies for polymer-based materials are outlined.
Polymer surface preparation methods and the deposition of
metal bond-coats are also explored. Thermal spray process
parameters that affect the properties of metal deposits on
polymers are described, followed by studies on temperature
distribution within polymer substrates during thermal spray.
The objective of this review is devoted to testing and potential
applications of thermal-spray metal coatings deposited onto
polymer-based substrates. This review aims to summarize the
state-of-the-art contributions to research on the thermal spray
metallization of polymer-based materials, which has gained
recent attention for potential and novel applications.
Fig. 1. —
n
-TiO
2
powder characteristics: SEMmicrographs.
Fig. 2. —
Backscattered scanning electron microscope image of the
cross section of a flame-sprayed Ni-20Cr coating deposited onto a
fiber-reinforced polymer composite substrate.
FABRICATION OF HIGH-TEMPERATURE
HEAT EXCHANGERS BY PLASMA SPRAYING
EXTERIOR SKINS ON NICKEL FOAMS
P. Hafeez, S. Yugeswaran, S. Chandra, J. Mostaghimi, and
T. W. Coyle
Thermal-sprayed heat exchangers were tested at high
temperatures (750°C), and their performance compared to
foam heat exchangers made by brazing Inconel sheets to
their surface. Nickel foil was brazed to the exterior surface of
10-mm-thick layers of 10 and 40 PPI nickel foam. A plasma