Wear-reducing nickel-phosphorus and graphene oxide-based composite coatings: Microstructure and corrosion behavior in high temperature geothermal environment

Polymer coating modified with graphene oxide (GO) and duplex electroless Nickel-Phosphorus (Ni-P) with polytetrafluoroethylene (PTFE) coating were investigated for their corrosion behavior in simulated hightemperature geothermal environments with/without H2S and CO2 gases for geothermal applications. The polymer coating with added GO nanosheets demonstrated low wetting ability and suppressed corrosion effects of the substrate at 120 degrees C. The Ni-P/PTFE duplex coating with the lowest P content was suitable in an H2O liquid environment at 120 degrees C while high P was more promising in the two-phase CO2/H2S environment. Nevertheless, all the coatings were unprotective and allowed substrate corrosion at 250 degrees C in the H2S/CO2 environment.