On-line Analyzer for Ni–An Alloy Electroplating Bath

Abstract

In the production of Ni–Zn alloy electroplated steel sheets, the concentrations of Ni²⁺ and Zn²⁺ ions in the plating bath are necessary to be controlled. An automatic on-line analyzer has been developed for the process control. The on-line analysis system consists of a sampling system and an energy-dispersive X-ray fluorescence analyzer. The plating process solution is continuously supplied to the X-ray fluorescence analyzer through the sampling system form the plating trays. The concentrations of the Ni²⁺ and Zn²⁺ ions are determined from the intensities of Ni, Zn, Fe and S fluorescent lines. The intensities of the S and Fe lines are measured for interelement correction. The intensity of the S line is easily measured after a path in air with the energy-dispersive X-ray spectrometer. The S line is excited by chromium, and the Ni, Zn and Fe lines are by tungsten X-ray source, for obtaining a higher excitation efficiency. The analysis can be completed within 8 min. The analytical accuracies on the production line were 0.77 g/l for Ni²⁺ and 0.48 g/l for Zn²⁺ ion.