ABSTRACT
An important aspect of minimizing the effects of high temperature corrosion involves understanding the mechanisms of degradation. The development of this understanding involves the ability to reproduce the corrosion morphologies found in service by conducting well controlled laboratory experiments. This paper describes experiments in which this has been attempted. The results of morphological studies of the oxidation and hot corrosion of uncoated superalloys as well as diffusion aluminide, CoCrAlY overlay, and zirconia thermal-barrier coatings are presented. The influence of Pt additions on the cyclic oxidation and hot corrosion behavior of diffusion aluminides is described in detail. It will be shown that the composition of the substrate has a substantial influence on the corrosion rates and morphologies. The development of the hot corrosion morphologies of CoCrAlY coatings on Ni-base superalloys is described and the use of transmission electron microscopy in characterizing the fine details of these morphologies discussed. Finally, the development of the hot corrosion morphologies of stabilized zirconia thermal-barrier materials is described.
