Coating deposition
Table 1 summarizes the coatings applied over each
substrate, their chemical composition, and the
characterization studies performed. For wear and
corrosion tests, 20x20x5-mm size samples were
used, except for the 316L steel where samples were
20x20x2 mm in size. To study thermal properties,
23.8-mm diameter and 2-mm thickness samples
were used. For these studies, the substrate surface
was #rst prepared by using an abrasive wheel. "e
coatings were then immediately deposited to prevent
oxidation of the sample surface. Subsequently, a
95Ni5Al base coating was deposited, providing
adequate surface roughness to improve adhesion of
the system.Finally, the coatings were deposited by using
the following parameters: primary air pressure
at 50 psi, voltage at 29 V, current at 220 A and
projection distance at 200 mm perpendicular to
the sample surface. All coatings were applied by
using a EuTronic Arc Spray 4 system.
"ermal spray coatings were structurally studied
by using X-ray di!raction (XRD) with Pro
Panalytical X-pert equipment, operating at 45 kV
and 40 mA. "e measurement of thickness and
qualitative porosity was carried out with a Leco
convex lens optical microscope via cross-section
metallography. "e coatings were studied at the
surface by using a scanning electron microscopy
(SEM) FEI QUANTA 200 system, in a highvacuum
environment at 30 kV. Chemical analysis
was performed before and after electrochemical
tests with the same SEM equipment in EDS mode
at 20 kV.