Deterioration of materials in geothermal fields in Mexico

摘要

Mexico is the third world producer of geothermal electricity. The power generation infrastructure installed for the exploitation of geothermal steam, includes a wide variety of materials for fabrication of equipment and structures exposed to a very aggressive, geothermal environment. In the geothermal fields of Mexico there are several microorganisms causing corrosion of carbon steel (CS) and stainless steel (SS) and biodeterioration of composite materials: fibre-glass reinforced polyester (FGRP) and steel reinforced concrete (RC). These microorganisms were isolated from natural geothermal environments, identified and utilised in simulated corrosion and deterioration laboratory investigations. Metallographic analysis and SEM were performed to determine the morphology of microbiological attack on SS. Electrochemical corrosion tests showed that the bacteria induced corrosion on UNS S31600, preferentially at grain boundaries. The composite materials underwent physico-chemical deterioration processes promoted by the harsh environmental field conditions, involving microorganisms.