Electrochemical Dissolution of WC-Co Micro-Tool in Micro-WECM Using an Eco-Friendly Citric Acid Mixed NaNO ₃ 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 (H 2 SO 4 ) is extensively used in the electrochemical process to dissolve WC-Co due to its higher dissolution rate and efficiency. But toxicity of H 2 SO 4 , 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 (NaNO 3 ) and a complexing agent citric acid (C 6 H 8 O 7 ), that not only gives a higher dissolution rate of WC-Co but also gives similar dissolution efficiency that of H 2 SO 4 . 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 H 2 SO 4 . Potentiodynamic polarization test through linear sweep voltammetry (LSV) showed maximum current density for WC-Co alloy in the proposed eco-friendly electrolyte.