A Study on Electrochemical Machining Method in Ultrapure Water

Increase of Hydroxyl Ion in Ultrapure Water by Catalytic Reaction

Abstract

In order to develop a new ultra-precision and ultra-clean machining method, electrochemical machining in ultrapure water was performed. A new method for increasing OH^- ion in ultrapure water using catalytic reaction that dissociates the water molecules into H⁺ and OH ion was proposed. As examples, ion-exchange membrane and fabric were used. Also first-principles molecular-dynamic simulations of interaction between water molecule and sulfonic acid function of ion-exchange material in order to analyze the mechanism of dissociation process of water molecule were performed. In the case of using sulfonated graft-polymerized polyethylene fabric, over 6A/cm² current density was obtained which suggests that the density of OH ion in ultrapure water increases to about one million times larger than in the case of without using catalytic reaction. As a result of machining experiments, etching were occurred for Cu, Mo and Fe anode under the condition of less than 2A/cm² of current density. Thus the possibility of electrochemical machining in ultrapure water for industrial application was confirmed.