The influence of formation of transfer layer on the characteristics of friction and wear mechanism between several coatings and anodized aluminum alloy

The friction coefficients of the coatings increased in order of CrN, TiAlN and TiN. The formation and destruction of the transfer layers that formed on the ceramic-coated surfaces affected the amplitudes of the variations of the friction coefficients, and these variations produced noise and vibration during the tests. Because the coatings were much harder than the anodized aluminum alloy, the anodized aluminum alloy was worn out abrasively by the coatings. Also, the widths of the wear scars on the anodized Al alloy surface increased in order of CrN, TiN, and TiAlN. For TiAlN and CrN coatings, the repetition of formation and destruction of transfer layer was so active that the amplitude of the variation in the friction coefficient was large. However, the TiN coating gave stable friction coefficients, because the formation of the transfer layer was less active than the other coatings.