The metal dusting resistance of various 2¼ Cr to 20%Cr steels has been tested in flowing CO‐H2‐H2O atmospheres at 525, 560, 600 and 650°C. For the 2¼Cr‐steel immediately a constant rate of metal wastage is reached, for the high alloy steels the approach to this rate where all surface area is attacked, is more or less retarded by an oxide layer. The formation of a protective Cr‐rich oxide layer is favoured by a high Cr‐content of the steels, by the ferritic structure, by a fine‐grained microstructure, by surface working and by high temperatures – these factors hinder or suppress metal dusting, whereas low Cr‐concentration, austenitic structure, coarse‐grained microstructure, removal of surface deformation by etching and a critical temperature of ≤ 600°C accelerate and enhance metal dusting.

Layers of the oxides FeO, Fe30,, Fe203, Cr203 and M,03 were prepared by evaporation of the corresponding metal layers onto a preoxidized Si substrate and oxidation at elevated temperature. The oxidation was conducted under thermodynamically well-dehed conditions so that the pure oxide phases noted were obtained. The oxide layer thickness was calculated from the thickness of the initial metal film, which was determined by chemical analysis and from the frequency change of a quartz crystal upon evaporaton. Auger electron spectroscopy depth profiles of the oxide layers were measured during Ar+ sputtering, and the sputter time necessary to reach the interface oxide/substrate was determined. The determination of this sputter time was not very exact, because the transition from oxide to substrate in the profile was rather gradual, owing to the r o u g h and crystalline chracter of the oxide layers that causes inhomogeneous sputtering. However, from the sputter time, oxide thickness and ion beam current, the sputter rates were obtained for the oxides noted (in nm PA-' cm-2 min-I) and were compared to the sputter rate of amorphous Ta20,, which is generally wed as the sputter reference standard. Considerable differences were found. The results will lead to more reliable determinations of oxide scale thicknesses by sputtering.

Titanium oxynitride (TiN x O y ) thin films were deposited by low-pressure metal±organic CVD (LP-MOCVD) on (100) silicon, sapphire, and polycrystalline alumina substrates. Titanium isopropoxide (TIP) and ammonia were used as precursors. The influence of the growth temperature, ranking from 450 C to 750 C, was investigated by scanning electron microscopy (SEM), and electrical DC measurements. Rutherford back-scattering (RBS) measurements were used to determine the N/O ratio in the films. The surface observations of the deposited films showed two morphological transitions. The resistivity decreased with the growth temperature, while the nitrogen content increased. Moreover, for the highest deposition temperatures, the temperature dependence of the resistivity revealed a transition from a semiconducting to a metallic behavior. Finally, these electrical properties were correlated with the two morphological transitions.

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