Characterization of particle rebound phenomena in the erosion of turbomachinery

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77337/1/AIAA-44864-924.pd

Erosion-corrosion and wear

The basic processes of wear, erosion and erosion-corrosion are reviewed. It is shown that oxide debris can accelerate wear when it is present as particulates, or protect and reduce friction when it is present as a glaze. Erosion-corrosion processes can be understood and organized in a series of regimes that represent a sequence of change in the relative intensities of erosive and corrosive processes. Types of mechanism expected to feature in oxide spallation and in the erosion-corrosion of alloys are described and, finally, the areas that require serious study in order to achieve further understanding of this subject are indicated

Oxidation behavior of titanium aluminides

Results from an ongoing study of the high temperature oxidation of intermetallic compounds in the Ti-Al system are presented. The oxidation behavior of alloys based on TiAl (γ) has been found to be extremely complex depending on temperature and atmosphere composition. Protective alumina scales are formed in pure O2 up to a critical temperature above which a mixed TiO2/Al2O3 scale forms and grows at rates which are orders-of-magnitude faster than that of alumina. This phenomenon is believed to result from the formation of Al-containing internal oxides which coupled with the closeness in stability of alumina and the titanium oxides, prevents the alumina from becoming continuous. Continuous alumina scales were not observed, even at temperatures below 1000 °C, when N2 was present in the oxidizing gas. The effect of the N2 has been shown to be involved with the initial development of the reaction products