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.
SUBSTRATE
COATINGS
140 MXC
Fe 25Cr 5B 6Mo 15W
3Mg 4C 12Nb 2Si
530 AS
Fe 0.15C 0.8Mn
0.2Si
560 AS
Fe 13Cr 1Mn 1Si
0.3C
4340 STEEL
Fe 1.65Ni 0.7Cr 0.2Mo 0.4C 0.6Mn
Abrasive wear
Corrosion
Corrosion
1045 STEEL
Fe 0.45C 0.3Si0.8Mn Corrosion Abrasive wear
Corrosion
316L STEEL
Fe 0.03C 13Ni 2.3Mo 17.5Cr
Abrasive wear
Corrosion
1020 STEEL
Fe 0.2C 0.6Mn 0.04 P 0.05S "ermal Barrier
A Knoop microhardness test was conducted over
the three coatings, with a 50-g load; using a Leco
M-400-G2 hardness tester. Measurements were
made with a depth pro#le from the surface of the
coating into the substrate.