To the issue of the modeling of oxide film fracture during aluminum particle ignition

Aluminum particles are coated with a protective oxide film. It is known that the oxide film condition controls the aluminum oxidation kinetics. The fracture of the film induces the intensification of oxidation. This feature encourages authors to simulate the film condition after fraction caused by thermomechanical stress. The static strength of the film is a well-studied issue, while the fracture dynamics is still a relevant problem. In this paper, two coefficients describing the film condition after fraction are proposed. The first is based on the ratio of activation rates of critical flaws at the fracture initiation and in a hypothetical case without oxide film relaxation. The second represents the ratio of total times of the activated flaw growth during fracture and under specific reference conditions. Both coefficients are shown to produce adequate results with regard to predicting of more sufficient fractures at higher stress rates. It is assumed that the aluminum particle surface, which is exposed to an oxidizer after film fracture, is proportional to the proposed coefficients. With this assumption, the particle ignition is simulated. It is shown that higher rates of particle heating during ignition induce considerable fractures of the oxide film and the following intense oxidation.