Oxidation of the Alloy Based on the Intermetallic Phase FeAl in the Temperature Range of 700-1000 °C in Air and Possibilities of Practical Application.

The paper presents the results of oxidation tests on the alloy based on the intermetallic phase, Fe40Al5Cr0.2TiB, in the air at 700-1000 °C temperature. The kinetics of corrosion processes were determined, the surface condition after oxidation was assessed, and the type and morphology of the oxides formed were determined. In addition, the paper presents the possibility of applying the technology of surfacing Fe40Al5Cr0.2TiB alloy on the surface of steel grade S235JR as a protective coating that is resistant to high temperatures. The process was carried out using the TIG method by direct current (DC). After the surfacing, the structure of the surfacing weld made of the tested material on the base of structural steel grade S235JR was determined. It was found that a protective AlO oxide layer is formed on the surface of the oxidized alloy based on the intermetallic phase from the FeAl system, and the oxidation kinetics have a parabolic course. Moreover, it was found that the morphology of the oxides formed on the surface varies depending on the oxidation temperature, which clearly indicates a different mechanism of oxide layer formation. The formation of a stable α-AlO oxide variety on the surface of the Fe40Al5Cr0.2TiB alloy protects the material from further corrosion, which favors the application of this alloy on structures and fittings operating at elevated temperatures. The aim of the research was to use the Fe40Al5Cr0.2TiB alloy with very good oxidation resistance as a layer overlay on ordinary quality S235JR steel. In this way, conditions were created that fundamentally changed the surface condition (structure and physicochemical properties) of the system: steel as a substrate-intermetallic phase Fe40Al5Cr0.2TiB as a surfacing layer, in order to increase resistance to high-temperature corrosion and erosion (in the environment of gases and solid impurities in gases) often occurring in corrosive environments, especially in the power industry (boilers, pipes, installation elbows) and the chemical industry (fittings). At the same time, the surfacing method used is one of the cheapest methods of changing the surface properties of the material and regenerating or repairing the native material with a material with better properties, especially for applications in high-temperature corrosion conditions.