October 24, 2008

Electropolishing Bath

As have known that electropolishing is the fast and effective way on preparing the metals before anodized or electroplating process applied. This process also become a key on getting a best result, because if you do in careless way on this process you will difficult to get a best result or even no metal is stick to the product.

The most common used in electropolishing bath are based on sulfuric and phosphoric acids in about 50/50 weight proportion at about 54 to 105oC for ferrous alloys, 85% phosphoric acid for copper at about 43 to 60oC; and phosphoric acid with about 5 to 7% chromic anhydride (CrO3) at about 60oC for brass.

Current density of practical electropolishing range from 5 to 40 A/dm2, depending on the metal being finished, type of bath, and temperature. The time required usually is 2 to 7 min for current densities of 15 to 30 A/dm2 and temperature of 54 to 82oC.

Electroplating bath are less subject than electroplating bath to contamination and are easily controlled to maintain optimum result. Except for the perchloric acid – acetic acid type of bath, safe operation is easily maintained. Perchloric acid-acetic bath require failsafe temperature controls and strict avoidance of contamination with easily oxidizable materials.

No comments: