Laboratory Automatic Titration of Chromium Plating and Electropolishing Solutions

摘要

Two increasingly important issues for the metal finishing industry are product quality and productivity. This industry is constantly looking for better methods to monitor key chemical components in its metal finishing solutions. The analytical chemistry literature lacks an adequate automatic titration method for the monitoring of chromic acid in chromium plating solutions and the monitoring of phosphoric and sulfuric acids in electropolishing solutions. Automatic titration methods for each of these applications are given here based on previous manual titration methods. The identical experiment was conducted at three different companies who sell this type of instrument and included calibration, standardization and analysis. Although this work has a specific objective related to chromium plating and electropolishing solutions, the general method is applicable to most other types of metal finishing solution titrations. The optimum operating range of chromic acid in these chromium plating solutions is 240-260 g/l while the optimum respective operating ranges of phosphoric and sulfuric acids are 640-730 g/l and 795 - 895 g/l. The resulting automatic titration precisions for each application equal the present manual titration precisions from which these methods were derived.