Influence of the microstructure on corrosion induced damage of WC-Co cemented carbides

MÜLLER, C. M.; TARRÉS, E.; FARGAS, G.; TARRAGÓ, J.; LLANES, L.; SOSA, D.; FAIR, J.

POWDER METALLURGY

MANEY PUBLISHING

Año: 2020 p. 1 - 6

0032-5899

The main goal of the present work is to study the influence of the microstructure on the corrosion behavior of cemented carbides WC-Co in two corrosive media: seawater and mine water. Thus,two grades with the same proportion of cobalt as a binder and different grain size: medium and ultrafine were selected. Corrosion kinetics were determined by immersion tests while theelectrochemical evolution of the Surface was analyzed using impedance testing. Damage tolerance to corrosion was evaluated by assessing fracture strength on specimens previouslysubjected to corrosion. Results pointed out that for both grades the corrosion rate was higher in seawater, being more significant for the grade with a medium grain size. The corrosionphenomenon that took place in both media was caused by the oxidation reaction of cobalt. In seawater, the polarization resistance decreased for both grades whereas in mine water increased,due to the formation of a layer of corrosion products, which slowed down the cobalt dissolution process in Surface. In both media, a greater strength loss of the ultrafine grades was evidenced.