Electrochemical Dissolution of WC-Co Micro-Tool in Micro-WECM Using an Eco-Friendly Citric Acid Mixed NaNO3 Electrolyte

Abstract

The present study analyzes the efficient electrochemical dissolution of tungsten carbide–cobalt alloy (WC-Co) micro-tools for micromachining operations with an eco-friendly electrolyte. One of the essential factors in efficient anodic dissolution is the selection of appropriate electrolytes. Sulphuric acid (H2SO4) is extensively used in the electrochemical process to dissolve WC-Co due to its higher dissolution rate and efficiency. But toxicity of H2SO4, even at moderate concentration, poses a significant threat to the operator and the environment. Hence in this investigation, an eco-friendly electrolyte has been proposed which is a combination of sodium nitrate (NaNO3) and a complexing agent citric acid (C6H8O7), that not only gives a higher dissolution rate of WC-Co but also gives similar dissolution efficiency that of H2SO4. A detailed experimentation to optimize the concentration of complexing agent in the eco- friendly electrolyte was carried out through micro wire-electrochemical machining (micro-WECM) and was analyzed using yield parameters, topographical and material surface analysis as well as electrochemical analysis. This eco-friendly electrolyte produces higher dissolution rate and better surface finish in different levels of parameters in comparison to H2SO4. Potentiodynamic polarization test through linear sweep voltammetry (LSV) showed maximum current density for WC-Co alloy in the proposed eco-friendly electrolyte.