Checking the coating structure

Surface coatings specially optimized for the respective practical requirements are of decisive importance for the function, durability and decorative appearance of technical products. The spectrum ranges from hot-dip galvanizing and multi-layer coating systems to complex thin-film systems that are used as optical coatings on glass.
The function of the coating depends, among other things, on the layer sequence, the layer thicknesses and the chemical composition of the individual layers and interfaces. Depth profile analyses, e.g. using the SNMS or GDOS method, provide essential information on the layer parameters mentioned. The coating is continuously removed by ion bombardment and the element composition is recorded as a function of the coating depth.

Example: Stainless steel trim panels are chrome-plated in two different processes for decorative reasons. As part of quality assurance, the aim is to check whether the layer structure and composition of the current batches correspond to the reference samples previously analyzed as a quality standard.
GDOS depth profile analyses show (see figure above):
1. sample 1 is a simple chromium plating layer.
In sample 2, an additional nickel intermediate layer was deposited between the steel and the chrome layer. The total layer thicknesses are approx. 500 and 300 nm.
2. no interfering foreign element enrichments are found in the entire layer structure.
3. the base material is a Cr/Ni steel with approx. 20% Cr and 8% Ni.
Overall, the coating parameters are within the tolerance values. Based on the analyses, the coatings are expected to function perfectly in practical use.