ANALYSIS OF ALLOY LAYERS ON METAL-COATED STEEL WITH GLOW-DISCHARGE OPTICAL-EMISSION SPECTROMETRY

Glow Discharge Optical Emission Spectrometry (GDOES) is a rapid depth-profiling technique ideally suited to the analysis of alloy layers and interfaces. It can detect all elements in the Periodic Table, with detection limits in bulk analysis typically 1-10 ppm. Depth resolution is about 15% of depth, so that the depth resolution at interfaces can be improved by first polishing or etching the sample until close to the interface. Results are presented for a range of hot dipped metallic coatings on steel with special emphasis on the alloy layer between the coating and the steel. The ability of GDOES to analyse for H, O and C, there, is of particular interest in relating the alloy layer composition to steel cleanliness. Also, results are presented on the effect on the alloy chemistry of minor element additions to the melt.