Remelting of Flame Spraying Peek Coating Using Lasers

In order to answer of many industrial requirements (economic, ecological, etc), organic coatings became more and more attractive for improving properties of different materials, in particular metallic surfaces. Among those, PEEK (polyétheréthercétone) and PTFE (polytetrafluorethylene) seem to distinguish for their excellent mechanical characteristics (in particular tribological, as low coefficient of friction), their low surface energy and their high working temperature.

Several techniques can be used to realise this type of deposits as serigraphy, flame spraying, liquid way, etc. However, in spite of many efforts made in this area, these processes still have a certain number of limitations, in particular in the quality of the coatings as raised porosity, low interfacial adherence, etc. For that reason a thermal post-processing is often necessary. In the last few years, several experimental researches concerning laser – polymer interaction have been performed.

Then, the objective of this study is to analyse the effects produced during a laser beam heat treatment on morphological structure (compactness) of PEEK coating and their mechanical properties (adherence and tribology). The influence of the laser beam wavelength (by using a Nd:YAG, CO₂ or diode lasers) on the flame sprayed PEEK coating compactness on metallic substrates (304L, Al) was analysed. According to the different laser absorption coefficients, an optimisation of the operational parameters was carried out to induce a melting of the PEEK coating without burning. Nevertheless, whatever the conditions used, the results demonstrated a good influence of the laser treatments inducing both compactness of polymer coating and improvement of the adherence coating substrate at the same time. A tribological characterization has also been implemented on the laser treated organic coatings.