S. K. Bose

Improvement in the oxidation behavior of austenitic stainless steels by superficially applied, cerium oxide coatings

The influence of superficially applied CeO2 coatings on the isothermal-oxidation behavior, preceded by nonisothermal heating, as well as cyclic-oxidation behavior of three grades of austenitic stainless steel (AISI-316, −321, and −304), in dry air is reported. The superficial coating had a thickness of 2.1 μm. The linear heating rate employed was 6 K min−1 up to a maximum temperature of 1423 K, and the isothermal holding temperature was 1273 K. The results clearly depict that CeO2 coatings not only reduced the rates of scale growth for all three varieties of steel but also imparted improved scale adhesion to the respective alloy substrates, as evident from the fact that the coated steels could withstand a number of thermal cycles without scale rupture. In the bare condition, 321-grade steel exhibited the best performance. However, in the presence of the coating, the improved performances of 316 and 321 grades were almost identical, whereas the 304 variety showed improvement only in the first cycle of exposure. The kinetics results have been substantiated by postoxidation analyses of the alloy/scale combinations by SEM, EDS, EPMA, and XRD techniques to reveal the role of rare-earthoxide coatings on the observed behavior.

Influence of superficial coating of CeO2 on the oxidation behavior of AISI 304 stainless steel

The effect of a superficially-applied, cerium-oxide coating on the non-isothermal oxidation behavior of AISI 304 stainless steel in dry air has been investigated. The heating rate employed was 3 K/min up to a final temperature of 1423 K. The reactive oxide coating not only reduced the reaction rate but also facilitated scale adhesion to the alloy substrate. Post-oxidation analyses of the alloy/scale combination using optical microscopy, SEM, EDAX, and XRD provide evidence for a changeover in the mechanism of oxide growth from the scale/gas interface to the alloy/scale interface for the coated steel.

Pressure dependencies of copper oxidation for low- and high-temperature parabolic laws

AbstractStudies of the oxidation kinetics of copper have been conducted in the thin-film range at temperatures of 383–398 K and in the oxygen pressure range of 0.278–21.27 kPa; whereas in the thick-film regime at 1123 K, studies have been conducted in the oxygen pressure range of 2.53–21.27 kPa. Furthermore, the effect of continuously impressed direct current with oxygen pressure variation in Wagners parabolic range has been studied also in order to have a better understanding of the effective charge on the migrating species. In the low-temperature range, the rate constant, kP ∝

Hole conductivity estimation in lead iodide film through kinetic study of tarnishing reaction

P_{O_2 }^{1/4}

Influence of an Externally-Applied Static Charge on the Oxidation Kinetics of Copper

, suggesting that the migration of neutral vacancies in the growing film predominates. At high temperature, 1123 K, in the Wagnerian regime, the observed approximate pressure dependencies of the parabolic rate constants are the following:

A superficial coating to improve high-temperature-oxidation resistance of a plain-carbon steel under nonisothermal conditions

\begin{gathered} {\text{k}}_{\text{p}} (normal oxidation) \propto \sim {\text{P}}_{{\text{O}}_{\text{2}} }^{{\text{1/7}}} \hfill \\ {\text{k}}_{\text{p}} (sample cathodic) \propto \sim {\text{P}}_{{\text{O}}_{\text{2}} }^{{\text{1/5}}} \hfill \\ \end{gathered}