Utilization of ion chromatography and statistics to determine important acids in chromium plating and electropolishing solutions

Abstract

Inadequate monitoring of sulfuric and chromic acids in chromium plating solutions and phosphoric and sulfuric acids in electropolishing solutions is a serious problem for the industry resulting in poor quality products and wasted resources. This is especially true for the narrow tolerances required to chromium plate cannon systems. Current online and offline instrumental analysis methods either do not result in acceptable precision or are time consuming. Two similar methods, which are improvements on existing ion chromatographic methods, are presented here that provides acceptable analysis and monitoring of these acids in this chromium plating process coupled with an extensive statistical evaluation of the experimental data. For chromium plating solutions, the resultant means and precisions are 2.50 ± 0. 11 g/l sulfuric acid and 250 ± 5 g/l chromic acid. For electropolishing solutions, these values are 685 ± 4 g/l phosphoric acid and 845 ± 5 g/l sulfuric acid.