THE OXIDATION OF DUPLEX STAINLESS STEEL AT MODERATELY ELEVATED TEMPERATURES

The different techniques were used to produce thin oxide layers on polished and sputter-cleaned duplex stainless-steel samples. These samples were exposed to a 10(-5) mbar pressure of pure oxygen inside the vacuum chamber and oxidized with air oxygen plasma from room temperature up to 300 degrees C. The experiments were made with the alloy after a controlled oxidation with oxygen atoms created in an inductively coupled plasma. The experiments were performed in the temperature interval front room temperature up to 300 degrees C. The compositions of the modified oxidized surfaces were determined from the XPS survey scans, and the chemistry of selected elements from the higher-energy-resolution scans of the appropriate peaks. Various Fe/Cr oxidized layers and various oxide thicknesses were observed and correlated with the temperature. It was found that all the techniques produced oxide layers with various traces of metallic components and with the maximum concentration of chromium oxide and iron oxide in layers close to the oxide-layer-bulk-metal interface.