Anodic dissolution of cemented carbides of the type [(WC, M); M  Co, Ni OR Fe] in sulphuric acid solution. Electrochemical impedance spectroscopy

✍ Scribed by Henryk Scholl; Bożenna Hofman; Janusz Kupis; Krzysztof Polański

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 489 KB
• Volume: 39
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(94)85017-8

✦ Synopsis

Stationary electrodes prepared from the sintered tungsten carbide (WC, M) containing 10 ~01% of M = Co, Ni or Fe binder, with Vickers hardness > 1200 kg mm-', have been investigated in 0.5 M H,SO, using the Scanning Electron Microscopy (SEM) and the Electrochemical Impedance Spectroscopy (EIS) methods. The EIS were carried out at the polished electrode surfaces at the E,, E, and E, polarization potentials. The investigated electrode materials undergo a selective anodic dissolution in which the grains of the carbides play the role of microcathodes in relation to anodic parts of the iron group metal binders. On the basis of the obtained results the respective simulated equivalent circuits (EQC) have been calculated. The presence of Warburg impedance suggests the ions migration in/through the porous oxide layer.