Oxidations behaviour of austenitic stainless steel at high temperature in thermosolar plants

摘要

Austenitic stainless steels (SS) are suitable materials for use in energy system solar components. The oxide layer formed on the surface plays the role of protection against corrosion. However, the resistance of the passive layer (Cr_2O_3) depends on the environmental conditions, the alloy composition and the operating temperature. This protective layer is maintained under mildly oxidizing conditions and its growth kinetics is approximating a parabolic relationship. At high temperatures (>500 °C), a fast increase of scale growth may occur, this is known as breakdown. Specific components in solar plants are exposed to thermal cycles during day and night. Oxide layer surface can be damage due to the microstructural defects and spallation process during operation of the plants decreasing the passivity of stainless steel. Therefore, the aim of the present work was to study the effect of protective oxide layer resistance for different austenitic stainless steels types at high temperature using thermogravimetric techniques. Oxide morphology was characterized by Auger Spectroscopy, SEM/EDX analysis and profilometry.