Influence of Ru additions on the corrosion behaviour of WC–Co cemented carbide alloys in sulphuric acid

• Published in: International journal of refractory metals & hard materials Vol. 29; no. 4; pp. 478 - 487
• Main Authors: Potgieter, J.H., Thanjekwayo, N., Olubambi, P., Maledi, N., Potgieter-Vermaak, S.S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-07-2011
• Subjects: Alloys; Cemented carbides; Cobalt; Corrosion; Corrosion resistance; Corrosion tests; Ruthenium; Sulphuric acid; Surface films; Tungsten carbide; Tungsten carbides; Ruthenium; Surface films; Corrosion; Tungsten carbides; Sulphuric acid
• ISSN: 0263-4368; 2213-3917
• DOI: 10.1016/j.ijrmhm.2011.02.007

The aim of the study is to investigate the influence of ruthenium (Ru) additions on the corrosion behaviour of WC–Co cemented carbides when exposed in a reducing acid medium. The study involved the characterization 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 and chronoamperometry. Ruthenium affects the cathodic Tafel constant (β
c) in 1
M H
2SO
4, which indicates that it influences the cathodic part of the corrosion reaction. It also appears that Ru is more effective in improving corrosion resistance than a small vanadium carbide addition. Therefore, ruthenium additions of up to 3
wt.% Ru increased the corrosion resistance of the WC–Co alloys.
► Ru additions up to 2%(m/m) increased the corrosion resistance of WC-10%Co alloys. ► Ru additions to WC-10%Co alloys inhibit anodic dissolution and lower hydrogen evolution. ► Oxide layers on the alloys consist of a mixture of Co and W-oxides.