Comparative Study of the PVD Coatings on the Plasma Nitrided Steel

In the current study, the cracking, impact and sliding wear resistance of the PVD single layer TiN (I generation), multilayer (Ti,Al)N-ML (II generation), gradient (Al,Ti)N-G and multilayer nanocomposite FiVIc (both – III generation) coatings on the nitrided low alloy steel 42CrMo4 are analysed. The cyclic indentation test (normal load 50 N, 10 000 cycles) was carried out to determine the cracking resistance of the coatings. Impact wear test was performed at the normal load 16 N, strokes’ frequency 25 Hz, 104 – 107 strokes. Sliding wear test was applied, using the block-on-plate scheme, 10 mm Al2O3 ball as the counterbody, at the normal load of 10 N, the frequency 5 Hz, the amplitude 10 mm and the test duration 10 min. Best resistance to cracks’ formation is demonstrated by the gradient (Al,Ti)N-G coating, showing medium radial cracks’ formation, whereas delamination of the coating can be observed in other cases. 1.6 – 1.7 times higher impact wear resistance is shown by the TiN coating in comparison with the other coatings. The FiVIc coating demonstrates lightly better resistance to sliding wear in comparison with the TiN and (Ti,Al)N-ML coatings due to a lower coefficient of friction. The worst sliding wear resistance is observed in the case of the (Al,Ti)N-G coating due to a high affinity of the coating’s and counterbody’s materials. DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1339