HIGH-TEMPERATURE OXIDATION TECHNIQUE BY IN SITU CHARACTERIZATION OF OXIDE-GROWTH

A new experimental technique is proposed that should allow the joint study Of Kinetics and oxide structure during high-temperature oxidation of metal surfaces. X-Ray Absorption Spectroscopy (XAS) measurements were carried out in the fluorescence mode at the cation or anion K-edges. Oxygen is allowed to pass over the sample surface through a solid-state electrochemical pump allowing low and tunable values of oxygen flux. Preliminary data on K-edge measurements are presented after in situ oxidation at ca. 700-degrees-C and 10 Pa oxygen partial pressure of nickel and cobalt microfoils (6-mu-m). Preliminary results provide information on the thickness detection limit at the cation K-edge. These results show the technique to be a powerful tool for studying basic and technological aspects of the hot corrosion of oxide films too thick for common surface spectroscopy (Auger, ESCA) and too thin for the thermogravimetric technique