Modern analytical techniques in high temperature oxidation and corrosion

While the spatial resolution of AES, XPS and SIMS continues to improve, atomic scale analysis can only be obtained by transmission electron microscopy (TEM), combined with energy dispersive X-ray spectroscopy (EDX) or electron energy loss spectroscopy (EELS). EDX detects X-rays characteristic of the elements present and EELS probes electrons which lose energy due to their interaction with the specimen. The energy losses are characteristic of both the elements present and their chemistry. Reflection high-energy electron diffraction (RHEED) provides information on surface slmcture and crystallinity. Further details of the principles of AES, XPS, SIMS and other techniques can be found in a recent publication [1]. This chapter includes the use of AES, XPS, SIMS, RHEED and TEM to study the composition of oxides on nickel, chromia and alumina formers, silicon, gallium arsenide, indium phosphide and indium aluminum phosphide. Details of the instrumentation can be found in previous reviews [2-4]. 

This section considers the growth of oxide on nickel and chromium, chromia and alumina forming alloys and intermetaUics. 

in combination with X-ray emission analysis (XRE), has been used to study the initial stages of oxidation of nickel at low temperatures (e.g. room temperature to 200°C) [5,6]. The RHEED/XRE facility developed at NRC yields structural information comparable to the LEED (low energy electron diffraction) technique and elemental and chemical information about the surface similar to AES. Eor nickel single crystals the rates of oxidation vary considerably with substrate orientation, but three stages of oxidation, viz. chemisorption, nucleation and lateral growth, and oxide thickening, are always observed. 

2 Oxygen uptake by electropolished (100), (111), (112) and polycrystalline nickel at 600°C. As seen by RHEED, oxidation of (112) nickel produces a singly oriented growth whereas a polycrystalline oxide is propagated on (100) nickel. (From Graham et al. [7].) 

3 Oxygen uptake by (100) chromium as a function of time at a pressure of 4.7 x 10 torr oxygen at 350, 500 and 700°C. Indicated on the kinetic curves are the temperature/mass regions over which the various oxide phases are observed. The RHEED patterns correspond to (a) fee (1) oxide, (b) fee (2) oxide, (c) tetragonai oxide and (d) a-Cr203. (From Ariow et al. [9].) 

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Modern analytical techniques in high temperature oxidation and corrosion... 

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