Master’s Thesis from TAU- Helmi, Eero (2024)

Atmospheric icing is detrimental to a multitude of industrial sectors, decreasing the efficiency and lifetime of many man-made structures. The current solutions for these issues range from active anti-icing and de-icing systems to passive icephobic coatings. However, the former often demands high energy consumption and the latter is insufficiently reliable in ever-complex icing conditions. Neither approach thus offers a reliable, energy efficient solution on its own that would be commercially viable for large industrial applications.

In order to study the possibility of combining these two approaches, a composite coating consisting of piezoelectric barium titanate particles within a low density polyethylene matrix was manufactured using flame spraying. A premixed feedstock of a polymer powder with fine ceramic particles was used for the one-step coating process on aluminium substrates. The inclusion of barium titanate significantly alters the spraying process compared to the spraying of pure polymer powder and thus a preliminary research on different powder pretreatments and spraying parameters was conducted.

The poor flowability of the fine ceramic particles necessitated their treatment in order to be usable in the flame spraying process. High temperature heat treatment and surface functionalization proved as viable options for improving the sprayability of the powder mixture. The role of a bondlayer, flame temperature and stand-of-distance were tested with feedstocks containing 40 vol.% of ceramic particles, to better understand the coating phenomena. A significant reduction in deposition efficiency and highly uneven morphologies, were encountered when the heat flow was decreased either via lower flame temperature or closer stand-of-distance, indicating a significant increase in thermal resistivity brought by the barium titanate particles.