Design and Operation of Testing Facility for Investigation of Novel Corrosion Resistant Coatings for High Temperature Geothermal Applications

Abstract

The rapid corrosive damage of the equipment operating in the aggressive geothermal environment requires the development of novel cost-effective corrosion resistant coatings with design to increase the service life of the materials. In this work, a developed laboratory facility for simulating a two-phase geothermal environment (i.e., gas/liquid) to investigate the corrosion resistant coatings for high temperature geothermal applications is presented. Using the developed facility, the simulated geothermal environment with a pH of 4 at T=185 °C and P=7 bar, consisting of a gas phase (i.e., vapor) and H2S and CO2 gases, was established as experimental conditions. For the trial high temperature corrosion testing, high entropy alloy (HEA) coatings of CoCrFeNiMo and Al0.5CrFeNiCo were developed. The duration of the trial high temperature corrosion tests in a flow-through reactor was 96 hours. After testing, using EDS analysis, deposited sulfur was found in both the tested coatings. Using the microstructure SEM analysis, localized corrosion in the tested CoCrFeNiMo coating was detected, whereas the surface of Al0.5CrFeNiCo coating was more corrosion resistant to simulated geothermal environment.