The corrosion behaviour of WC-VC-Co hardmetals in acidic media

• Published in: Corrosion science Vol. 52; no. 9; pp. 3118 - 3125
• Main Authors: Konadu, D.S., Merwe, J. van der, Potgieter, J.H., Potgieter-Vermaak, S., Machio, C.N.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-09-2010; Elsevier
• Subjects: A. WC-Co; A. WC-VC-Co; Applied sciences; B. Polarization; B. Raman spectroscopy; B. XRD; C. Passivity; Cemented carbides; Cobalt; Corrosion; Corrosion effects; Corrosion environments; Current density; Exact sciences and technology; Hydrochloric acid; Metals. Metallurgy; Open circuit potential; Sulfates; Tungsten oxides; A. WC-VC-Co; B. Raman spectroscopy; B. XRD; C. Passivity; A. WC-Co; B. Polarization; Tungsten carbide; Hard metals; Cobalt; Passivity; Hard material; Corrosion; Cermet; Cemented carbides; Raman spectrometry; Acid medium; Passivation
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2010.05.033

The effect of increasing vanadium carbide (VC) content on the corrosion behaviour of tungsten carbide – 10 wt% cobalt hardmetals was investigated in 1
M hydrochloric (HCl), and sulphuric (H
2SO
4) acids solutions. Increasing VC content makes the open circuit potential (OCP) in the test solutions more negative than the base alloy. Specimens exhibited pseudo passivation in all the test solutions. Increasing VC led to decreasing corrosion current density. However, the corrosion current densities during chronoamperometric tests were lower for 0 wt% VC. XRD and Raman spectroscopy showed that hydrated WO
3 formed in the surface films of all specimens in hydrochloric acid (HCl), while hydrated vanadyl sulphate also formed for higher VC content specimens in sulphuric acid (H
2SO
4).