Advanced Characterisation of Nanocomposite Coatings

Nanocomposite coatings are systems comprised of two or more phases. Such multiphase coatings are becoming increasingly important as they offer the possibility of tailoring the coating architecture and achieving exciting new properties. An understanding of the coating nanostructure is important to complete the classic processing-structure-properties relationship and expedite the development of novel systems. However, comprehensive structural and chemical characterisation of such nanostructured coatings remains a considerable challenge. In this paper, results on three nanocomposite coating systems are presented (Ti-Al-B-N, Ti-B-C and Cr-Cu-N). The use of XRD, TEM and XPS for phase identification, determination of the relative phase fraction, grain size and structural defects are described. The accordance (or not) of the phase composition and relative phase fraction with the equilibrium phase diagram for these systems is examined. Specific interesting features of the spectra and micrographs are interpreted and their nanostructural significance discussed. Correlations are made between the nanostructure and mechanical properties.