| Summary: | The aim of the study is to investigate the influence of Ru additions on the corrosion
behaviour of WC-Co cemented carbides when exposed in corrosive media. The study
involved the characterisation of the microstructures, morphologies and phases present
by using the optical microscopy, SEM, XRD and Raman spectroscopy before and after
corrosion. The corrosion behaviour was investigated using the electrochemical
polarization tests in 1M hydrochloric acid, 1M sodium chloride and synthetic mine
water solutions. Three types of corrosion tests were done on the samples by
electrochemical techniques: potential versus time test, potentiodynamic polarisation
scans and chronoamperometry.
Ruthenium affects c in 1M H2SO4 and synthetic mine water, but not really in NaCl
solution. It was also observed that the passivity range and corrosion resistance decreases
in order of synthetic mine water> sodium chloride> sulphuric acid. It also appears that
Ru is more effective in improving corrosion resistance in all the solutions than a small
vanadium carbide addition. Therefore, ruthenium additions of up to 3 wt% Ru of the
WC-10%Co alloy increased the corrosion resistance of the WC-Co alloys. This is
attributed to the stabilization of the cobalt fcc phase due to ruthenium additions while
hcp phase is obtained when there is no ruthenium additions.
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