Abstract:

Consecutive growth stages of corrosion film on unloaded surface of electrical contact materials are described by the mathematical models. They include, diffusion phenomena of substrate metal and environmental gas in corrosion film, growth of corrosion film in a defect sire, and creep and thickening of corrosion film on the surface of noble metal. The effect of diffusion processes of substrate metal on the growth of corrosion film, growth of corrosion film has been studied. The kinetic modeling shows that the corrosion process of electrical contact materials is strongly affected by the diffusion coefficients, concentration gradient of substrate metal in the corrosion film, defect size of noble metal, temperature and exposure time to the environment. The susceptibility of environmental gas concentration or pressure will affect the growth of corrosion products by increasing or decreasing the diffusion flux of substrate metal in corrosion products. The kinetic modeling also make it possible to predict corrosion process for the new type of electrical contacts.

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