A GENERALIZED DESCRIPTION OF THE SIMULTANEOUS PROCESSES OF SCALE GROWTH BY HIGH-TEMPERATURE OXIDATION AND REMOVAL BY EROSIVE IMPACT

An approach is proposed for describing the rate of loss from a metal s urface subjected to the simultaneous action of high-temperature oxidat ion and mechanical erosion, in terms that involve the major parameters that determine the oxidation behavior of the alloy and the ''erosion potential'' of the environment. Different regimes are identified where oxidation or erosion is dominant, and where the two processes act tog ether. It is shown that under conditions where exfoliation of the oxid e scale (or of an adherent deposit) can occur, surface loss by erosion -oxidation is a strong function of the metal temperature and the erode nt flux. Some simplifying assumptions are made to provide a workable f ramework for incorporating the parameters in a way that is consistent with the observed modes of material loss. The effects of erodent impac ts on scale spallation are statistical in nature, and an initial attem pt to address this issue is illustrated.