Multi-scale modelling of the degradation of metals

Abstract

An evolving holistic model of the atmospheric corrosion of metals is currently most fully developed for the case where marine aerosols are the major promoter of corrosion. The model is based on integrating modules that define processes that control corrosion over a range of geographic scales. Processes include: marine aerosol production by oceans and breaking surf, transportation of marine aerosols across landscapes, deposition of aerosols onto structures, cleaning of surfaces by wind and rain, and the wetting and drying of surfaces throughout surface temperature and relative humidity cycles. The integration of these modules into a software framework enables the user to extract accurate estimates of surface conditions for structures located at any geographical location in Australia. Current research is aimed at developing a more fundamental approach to estimating corrosion based on the response of a metal to its environment. Research has defined the nature and rate of oxide development on surfaces exposed to fine saline drops, and the properties of oxides in terms of stability and surface chemistry. The dynamic chemistry within these fine drops has also been defined. This paper presents a strategy to integrate surface response into the model, and hence extend the existing modelling framework from a microclimate model to a true fundamentally based corrosion model.