Corrosion behavior of alternative binders in WC-Co hardmetals
authors A.M. Ferro Rocha, A.C. Bastos, J.P. Cardoso, C.M. Fernandes, F. Rodrigues, E. Soares, J. Sacramento, M.G.S. Ferreira, A.M.R. Senos
nationality International
abstract Cemented carbides and, more specifically, WC-Co are commonly used as drilling and cutting tools, in applications that require remarkable mechanical properties, i.e., outstanding hardness, fracture toughness and wear resistance, in different engineering fields such as the mining, oil and gas extraction. For a long time, cobalt (Co) has been used as a binder for these carbides due to its well-known relationship with the WC, given by its good wettability and ductility, resulting on hard metal composites with enhanced mechanical properties, which are difficult to be achieved with other binders. However, the price of Co has been continuously increasing with its rareness which led to the pursuance of different binder substitutes that could attain similar mechanical properties and processability. Another relevant problem is the corrosion of Co in some service environments which leads to the deterioration of the WC-Co composite and consequently to an early failure of the technical products. The aim of this study is to assess different binders systems, in terms of their electrochemical behaviour and corrosion resistance in different corrosive media when compared with the common WC-Co system. For this purpose, an electrochemical study was conducted using different techniques, namely measurements of the open circuit potential (OCP), in parallel with polarization curves (PC) and electrochemical impedance spectroscopy (EIS).
year published 2017

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