Corrosion, together with scaling, is one of the main threats to the lifetime and efficiency of geothermal
heat exchangers as they are in contact with. Geothermal fluids, containing non-condensable gases, ions,
and cycling temperature conditions. Coatings provide a means of mitigating corrosion by acting as a
barrier. Ceramic coatings are preferred due to their better resistance to corrosion, oxidation and wear at
higher temperatures. Besides, these coatings can be altered to exhibit better compressive strength and
hardness than metallic and organic coatings. Suspension plasma spray is a thermal spray technique
used as coating method that has been successfully employed to deposit ceramic materials from liquid
feedstock. In this study, different coatings of TiO2, CuO and Fe3O4 were developed on carbon steel using
the suspension plasma spray method for single-phase heat transfer application in geothermal heat
exchangers. All suspensions contained 5 wt.% of solid phase dispersed into water. The torch-to-substrate
standoff distance was varied to optimize the coating properties, as it plays a vital role in determining the
coating microstructure. The deposited coatings were analysed for microstructure and morphology by
using SEM/EDX and for surface wetting characteristics by contact angle measurements. Results showed
that due to the surface roughness CuO and Fe3O4 were hydrophobic.