Open Access Conference Proceedings

Surface treatments of metals are important areas of mechanical engineering. Galvanizing, which is a zinc coating on the steel base material by electrolytic deposition, belongs among the wide range of methods. Zn layer protects anodically the base material (usually unalloyed or low-alloy steel) against corrosion. In the final phase of the galvanic process final finish is performed - yellow or blue chromate surface coating. For correct function of the Zn layer it is important to abide the prescribed thickness. In the electroplating plants the thickness of Zn layer is usually measured by magnetic-inductive method. This method is fast, simple and non-destructive. The aim of this work is to verify the accuracy of this method using optical microscopy. Optical microscopy is here understood as the reference method, because this method is accurate and correct.While dealing with the given problems the statistical tests shown, that the differences between the results of the two methods are statistically significant. Therefore results of magnetic-inductive method must be corrected using the calculated conversion factor. After conversion of the measured values the magnetic-inductive method can be recommended to operating measurement of the Zn layer thickness on unalloyed and low-alloyed steels. Furthermore, it was found that the type of final surface treatment (chromate surface coating) does not affect accuracy of measurement of Zn layer.

Keywords: Galvanizing; Zinc layer; Optical microscopy; Magnetic-inductive method

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