Production and characterization of thermally sprayed polyethylene terephthalate coatings

Thermally sprayed polymer coatings are increasing in importance as protection against corrosion and wear. In this work, polyethylene terephthalate (PET) powder was deposited on 1020 steel by low-velocity flame spray technology. A potential application of this coating is to provide protection against corrosion in automobile fuel tanks, which are nowadays made of lead–tin-coated steel. In spite of the good properties presented by the lead–tin coatings, environmental cost restrictions have limited the use of heavy metals, encouraging research in new materials to substitute them. PET powder was obtained from post-consumer beverage bottles. Concerning the coating process, the following parameters were investigated: substrate pre-heating temperature, oxygen/propane flow rate ratio and spray distance. It was observed that the temperature attained by the PET during the deposition significantly affects the characteristics and properties of the coating. Chemical and structural changes of PET due to the thermal spray processing were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry and intrinsic viscosity analysis. The corrosion resistance of the coating was evaluated by total and partial immersion tests in gasoline, diesel oil and alcohol. No coating damage was detected.