Development of a Thermodynamic Model for Chromates, Molybdates, Tungstates, and Vanadates Involved in the Corrosion of Steels (Fe, Cr, Ni, Mo, W, and V) at High Temperatures in Atmospheres Containing O–H–S–C–Cl and Alkaline Salts

This research work falls under the generic theme of modeling high-temperature processes, during energy conversion, flaking, and corrosion phenomenon, for systems converting mainly organic matter into energy. Energy conversion facilities are made of a metal alloy of the type Fe–Cr–Ni–V–Mo–W and are exposed to gaseous species from combustion, or from the flying of ashes. Under certain conditions, highly corrosive molten salts may be formed, causing the protective oxide layer of the steel to be transformed into either chromates, molybdates, tungstates or vanadates, or their mixture. This is called “catastrophic” corrosion. The presence of ash deposits limits the maximum operating temperature and the energy efficiency of the process. Thus, this research aims to develop a thermodynamic model including chromates, molybdates, tungstates, and vanadates that may form in environments containing O–H–S–C–Cl and alkaline salts, to predict the limiting conditions at which ash deposition and corrosion can occur.