The field of industrial colloids and lubricants

Typical fully formulated lubricating oil is composed of a combination of mineral or synthetic base oils and specialized dispersed additives designed to improve long-term stability and enhance performance in aggressive environments. Any commercial lubricant can be viewed as a nonaqueous highly resistive polymeric colloid with low, primarily ionic electrical conductivity. This system is composed of nonpolar base oil ( continuous phase ) and suspended 

The AC impedance technique is compatible with both conventional and microfabrication technologies, allowing production of rugged devices for applications in the harsh, highly resistive, chemically complex, and often aggressive media of industrial lubricants and colloids [25]. EIS presents an opportunity to resolve complicated nonaqueous colloidal system both spatially and chemically, and can be applied to monitoring lubricant s degradation process. 

This chapter presents a summary of the systematic EIS modeling of industrial and automotive lubricants. Initially EIS data interpretation for fresh lubricant, influenced by the effects of the chemical composition, temperature, electrochemical potential, AC frequency, and electrode geometry, is presented. Another important practical aspect is determination of changes in the lubricant s bulk and interfacial impedance model parameters as a result of its degradation by time-dependent oxidation and contamination with soot, fuel, and water at different stages in the exploitation cycle. 

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