Surface morphology analysis of oxide layers formed on 10CrMo9-10 steel used in the power industry

Abstract

The knowledge about high-temperature corrosion of steels operating at elevated temperatures is important due to the durability of power equipment. The paper demonstrated the fractal analysis of oxide layers formed on 10CrMo9-10 steel under the operating temperature of 545 °C for 200 000 h employed in the power industry. The studies were carried out on elements taken from the inner and outer surface of the tube wall on the outlet both on the fire and counter-fire side of the tube wall surface. Thorough examinations of the oxide layer comprised microscopic examinations using scanning electron microscopy and atomic force microscopy. The fractal geometry of oxidized surfaces was characterized by providing the fractal dimension D. Using the methods of numerical analysis of the surface, the texture anisotropy ratio Str was also determined. The corner frequency τ and grain size dg were also determined. The obtained results of performed fractal analysis showed that the studied surface on the tube wall outside was more developed as compared with the inside. In addition it was shown that directly on the flue gas inflow side (the fire side) the oxides/deposits layer was built of densely arranged spherical deposits, which formed an unfavourable barrier between the component (tube) and the atmosphere surrounding it.