Effect of tribofilm formation on the dry sliding friction and wear properties of magnetron sputtered TiAlCrYN coatings

Nano-structured TiAlCrYN coatings, grown by unbalanced magnetron sputtering on various steel substrates, exhibited friction coefficients 0.6–0.8 and wear coefficients 10-16–10-15 m3 N-1 m-1 in dry sliding wear tests. This article reports comprehensive worn surface analyses using SEM, TEM , EDX, EELS and Raman spectroscopy. A *80 nm thick tribofilm formed on the TiAlCrYN worn surface was found to have dense amorphous structure and homogeneous oxide composition of Cr0.39Al0.19Ti0.20Y0.01 O0.21. Viscous flow of the amorphous tribofilmwas dominant in causing the high friction coefficient observed. The coatings showed combined wear mechanisms of tribo-oxidation and nano-scale delamination.