High Temperature Oxidation Group

The long-term viability of machine components operating at high temperatures in an oxidising environment often relies on the integrity of a thin, protective layer of oxide, typically chromia, alumina or silica. Understanding the mechanisms of the formation of such a protective layer and the processes which affect its mechanical integrity, particularly during temperature changes, are major challenges tackled by this research group as well as to the larger oxidation community.

The compositions of commercial alloys are generally optimised to produce such protective oxide layers but in some applications such as gas turbines, where components may be highly stressed, good oxidation resistance is incompatible with the need for high creep strength. In these cases, oxidation-resistant coatings can be applied. An area of activity within the Group is the design and testing of new coatings. A particularly exciting development has been the creation of a number of coatings that can respond in a pseudo-intelligent manner to its local temperature to form an appropriate type of protective oxide.

Another area of activity is the improvement of oxidation resistance of alloys by controlled heat treatments by, for example, controlling the oxidising environment to low partial pressures, or heating rates.

These experimental studies are complemented by extensive theoretical studies, both of the mechanical stability of the oxide layer, and the subsurface depletion of the oxidising element. For the latter, the group developed a 2D interdiffusion/oxidation model capable of simulating solute depletion in arbitrary specimen geometries.