High temperature corrosion issues in energy-related systems

Abstract

The large majority of electric power that is generated world-wide involves heat engines of one kind or another. The significant exceptions are hydroelectric generation; wind; and photovoltaics. The thermal sources for the heat engines include: fossil fuels, nuclear fission, biomass, geothermal sources, and solar radiation. There has been a progressive move to higher overall cycle efficiencies for at least one hundred years, and in the case of fossil fuels this has accelerated recently in part because of concerns about greenhouse gas emissions, notably CO2. For a heat engine, the overall efficiency is closely related to the difference between the highest temperature in the cycle and the lowest temperature. In most cases, this has resulted in an increase in the high temperature, and this in turn has led to increasing demands on the materials of construction used in the high temperature end of the systems. One of the issues is the chemical degradation because of reactions between the materials of construction and the environments to which they are exposed: this is high temperature corrosion. This paper will describe the issues for a range of current heat engines

Effect of Pack Cementation Coating on Hot Corrosion Resistance of Low Alloy Steel

“…Then the heating cycle can be started. Figure (1) illustrates the pack cementation system. The heating cycle for one step pack cementation process was started for diffusion when the argon gas was flowing to the retort group to keep argon atmosphere during the entire time of diffusion coating process.…”

“…Without exception, they are oxidizing at temperature below that at which wustite, FeO, is stable for plain carbon steels this is 570 o C, The oxide formed in air has an inner layer of magnetite, Fe 2 O 3 , Generally, the thickness of the magnetite layer is considerably larger than that of the hematite. [1]. Hot Corrosion / Sulfidation is sometimes defined as an accelerated corrosion because of the presence salt contaminants such as NaCl , Na 2 SO 4 and V 2 O 5 that combine to form molten deposits which damage the protective surface oxides [2].…”