cross-sectioned, mounted in resin, ground using a series of SiC papers
(400, 600, 800, 1000 and 1200 grit) and finally polished with 1 μm
alumina particles. Microstructure and composition of the polished
cross-sections of the deposited coatings were studied using SEM and
EDS analysis. Phase characterization was also performed using the XRD
technique. Hardness was measured on the cross-sectioned surface using
Vickers hardness tester (Wolpert W Group instrument) at a 300 g load
and 15 s dwell time. Average percentage of porosity and oxide content
were evaluated using optical micrographs of the cross-sections with the
image J program.
Sliding wear rate and friction coefficient of the coatings were
investigated at room temperature using a pin-on-disk (ISC-200
Tribometer) apparatus following ASTM standard G99-90. Samples to
be tested were ground by SiC papers and polished to 1 μm finish,
ultrasonically cleaned and dried before wear test. Details of sliding wear
test condition are given in Table 2. The test was done at 150 g load for
various sliding distances. After testing, the track width observed by an
optical microscope was measured and the values were used for
calculation of wear rates based on the following Archard wear equation,