Electrolytic Process and Weakened Surface Layer of Cemented Carbide

Abstract

In electrolytic abrasive machining surface layer of cemented carbide is weakened by preferential dissolution of binder phase. The weakened layer increases mechanical removal but it may badly influence on the character of the finished work.
Generating mechanism of the weakened surface layer was experimentally investigated by an electrolytic cell. Experiments were performed with the several sorts of carbide alloy and its components WC, TiC, and Co.
The results obtained are as follows:
1) The first peak of a current-potential characteristic curve is caused by the decobaltizing process of cemented carbide. The second peak features to fall off the anodic film.
2) High cobalt alloy containing 24% Co and 76% WC cracks by a low potential electrolysis in which dissolves binder cobalt only. Common carbide alloys (5-8% Co) are weakened in surface layer in any anodic potential.
3) The depth of the decobaltized layer calculated from the electrolytic current in the low potential electrolysis is nearly equal to the depth measured by the asland superfinishing.
4) Comparatively high hardness and porosity of the decobaltized layer of low cobalt alloy suggest a possibility to utilize it as an anti friction material.