Delamination of Metallic Coatings

 

Surface analytical methods are often used to shed light on delamination problems. In the following example, a two component metallic coating showed poor adhesion to the underlying substrate. The sample was embedded in epoxy and cross sectioned. This exposed the interface between the coating and the substrate. By means of Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) fatty acid residues were identified as the cause of the adhesive failure. The analytical results help guide improvements in the pre-cleaning procedure.

 

Coating Component A
Fatty acid residue
Coating Component B

Instead of cross sectioning the sample, as shown here, less cost intensive preparation methods can be used in cases of pronounced delamination. Layers can be separated using adhesive tape and a cross cut or by simple mechanic lifting with a surgical blade. Subsequently the backside of the delaminated layer and the exposed substrate surface can be chemically characterized to detect the possible presence of adhesion reducing compounds (e.g. mineral oil, etc.).