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Characterisation of aluminium substrates

A customer asked us to determine the surface cleanliness of three different aluminium substrates to compare various degreasing methods.

“Several samples – both degreased and non-degreased – were provided for analysis by OCAS”, explains Philippe Legros, Research Engineer Surfaces. “We compared the remaining amount of oil residues, so the best degreasing method could be identified.”

GDOES depth profiles showing carbon residue before and after degreasing

“We first used Glow Discharge Optical Emission Spectroscopy (GD-OES) to measure the presence of carbon, which is an indicator for oil residues. We analysed the samples to compare the amount of carbon left at the surface after degreasing. Of each sample, a depth profile was made and the carbon-integral measured. In parallel, we carried out roughness measurements to visualise whether the degreasing techniques had a physical effect on the sample surface.”

Contact angle measurement to investigate the wetting

Combining different techniques

“To obtain the maximum amount of information, we also did contact angle analysis to evaluate the wetting of the aluminium substrates after degreasing. Contact angle measurements indicate if the wetting of a surface is favourable or not, with regard to paint application.”

“We go the extra mile to provide the customer with all the answers. In this case, it was crucial for our customer to fully understand the surface condition in order to improve for example wetting before painting. That is why we used three different analytical techniques (GD-OES, roughness and contact angle measurements). Thanks to this approach and its results, the customer could choose the most appropriate degreasing method for his production line.”