The Analysis of Galvanizing Preflux Solutions for Zinc by Flow Injection-Flame Atomic Absorption Spectrometry

Abstract

A direct flow injection flame atomic absorption spectrometry method of determining zinc salt solutions with concentrations of 100's g dm^?3 is reported. It was shown that high concentrations of KCl, NaCl and NH₄Cl do not significantly interfere with the determination of zinc in both the mg dm^?3 and g dm^?3 concentration ranges. Where g dm^?3 concentrations were determined a secondary spectral line at 307.6 nm was found satisfactory. Galvanizing preflux solutions were analyzed both after dilution to the mg dm^?3 range at 213.9 nm and directly injected at 307.6 nm. Precisions of better than 6.6% rsd were observed by the direct method compared with better than 4.8 by dilution techniques. Concentrations up to 110 g dm^?3 in zinc were determined the total salt content being greater than 300 g dm^?3.     

Semi‐supervised kernel partial least squares fault detection and identification approach with application to HGPWLTP

In this paper, fault detection and identification methods based on semi‐supervised Laplacian regularization kernel partial least squares (LRKPLS) are proposed. In Laplacian regularization learning framework, unlabeled and labeled samples are used to improve estimate of data manifold so that one can establish a more robust data model. We show that LRKPLS can avoid the over‐fitting problem which may be caused by sample insufficient and outliers present. Moreover, the proposed LRKPLS approach has no special restriction on data distribution, in other words, it can be used in the case of nonlinear or non‐Gaussian data. On the basis of LRKPLS, corresponding fault detection and identification methods are proposed. Those methods are used to monitor a numerical example and Hot Galvanizing Pickling Waste Liquor Treatment Process (HGPWLTP), and the cases study show effeteness of the proposed approaches. Copyright © 2016 John Wiley & Sons, Ltd.     

Improvement of hot-dip zinc coating by enriching the inner layers with iron oxide

The performance of hot-dip galvanic coating formed on steel not only depends on the alloy composition of the superficial layer but also significantly, on the composition of the inner alloy layers at the coating/substrate interface. Further, the presence of barrier oxide layers, if any can also improve the performance of galvanic coating. In the present work, the effect of inner iron oxide barrier layer formed prior to hot-dip galvanization was investigated. A continuous and adherent iron oxide layer was formed on steel by anodic oxidation of the steel substrate. Although the wettability of oxide surface by liquid zinc was initially poor, the increase in dipping time and the transition of the oxide layer to unstable form due to the presence of Cl⁻ ion in the flux facilitated localized growth of Fe-Zn alloy phases. The inhibitive nature of the oxide layer was temporary, since the presence of Cl⁻ induces micro cracks on the oxide surface thereby facilitating better zinc diffusion. The modification of the substrate structure during galvanization was found to influence the galvanizing process significantly. The present study predicts scope for application of this process for protection of rusted steel specimens too.