A deterministic interfacial cyclic oxidation spalling model Original Research Article

A series summation has been developed to model the iterative scale growth and spalling process of cyclic oxidation. Parabolic scale growth has been assumed. Interfacial spallation of a constant area fraction was stipulated to occur only at the thickest portions. Inputs are the parabolic growth rate constant, spall area fraction, oxide stoichiometry, and cycle duration. Outputs include the net weight change, amount of oxygen and metal consumed, and amount of oxide spalled. Classic weight change curves are produced with an initial maximum and final linear weight loss rate. This simplicity allowed for representation by explicit algebraic functions for all outputs and characteristic features. The maximum in weight change varies directly with the parabolic rate constant and cycle duration and inversely with the spall fraction, all to the 1/2 power. The ratio of the number of cycles to reach maximum and zero weight change is exactly 1:3, and these vary only with the inverse of the spall fraction. Many similarities to and some differences with previous cyclic models are identified.