Fundamental study on corrosion of cemented carbide during wire EDM

In this paper, a study on the corrosion of a workpiece of cemented carbide submerged in a dielectric of water for a lengthy time during wire EDM is described. When the cemented carbide is submerged in water for a long time, the surface of the cemented carbide becomes brittle, because the cobalt which is the binder of cemented carbide is dissolved in the water. This occurs even if an AC power generator is used during the wire EDM. This paper describes the following: (a) a method to estimate the corrosion state on the cemented carbide, (b) the corroded state of cemented carbide machined by an AC power generator and by a DC power generator, (c) a method which uses a zinc plate as a sacrifice metal, and a method which uses an external power supply to prevent the corrosion of the cemented carbide, (d) corrosion caused by a wire close to the work piece, and (e) corrosion test of corrosion-resistant cemented carbide materials, a binder-less type and a nickel binder type material.