Abstract:
In the present study, in-depth characterization of
the high-velocity oxy-fuel (HVOF)-spray WC-Co-Cr and
CoNiCrAlY coatings deposited on CA6NM turbine steel
was done using scanning electron microscope (SEM), x-ray
diffraction (XRD), roughness tester, microhardness tester,
and optical image analyzer. Further, these coatings were
tested under accelerated slurry erosion conditions using a
high-speed erosion test rig. The effects of three different
parameters related to actual operating conditions, namely
erodent velocity relative to target surface, average erodent
particle size, and slurry concentration on erosion behavior
of these coatings, were investigated. SEM images on the
specimen surface taken before and after erosion tests were
carefully examined to understand the possible erosion
mechanism. The study revealed that HVOF-sprayed WCCo-
Cr coating was found to impart higher erosion resistance
in comparison with CoNiCrAlY coating under all the
slurry erosion conditions. The reason for this behavior may
be attributed to the higher hardness of HVOF-sprayed WC-
10Co-4Cr coating in comparison with CoNiCrAlY coating.
