Application of a factorial design to study a chromate-conversion process

Chromate conversion coatings are commonly deposited on plated zinc to improve the corrosion resistance of the substrates, and to increase the adherence of painted films. The coatings’ properties depend on the composition and the structure of the conversion films as well as on the process parameters. A fractional factorial design was implemented to optimize the experimental conditions of the chromating process (bath composition, rinses composition, draining, treatment time). Surface analytical techniques such as scanning electron microscopy, glow discharge optical spectroscopy, and atomic absorption spectrometry were used to characterize the chromate conversion coatings.