Tribology of CrAg7N coatings deposited on Vanadis 6 ledeburitic tool steel
Tribologija prevlek CrAg7N na ledeburitnem orodnem jeklu Vanadis 6

english

2014

volume 48, issue 5

ledeburitic steels   PVD    chromium nitride    pin-on-disc   friction coefficient 

Inštitut za kovinske materiale in tehnologije
(Obvezni izvod spletne publikacije)

Samples made from Vanadis 6 PM ledeburitic tool steel were surface machined, ground and mirror polished. Prior to the deposition, they were heat treated to a hardness of 60 HRC. The CrAg7N coating was deposited with the magnetron-sputtering technique, using pure-Cr and Ag targets in a composite low-pressure nitrogen/argon atmosphere and at a temperature of 500 °C in the Hauzer Flexicoat 850 device. Tribological testing using a pin-on-disc apparatus was carried out at ambient and elevated temperatures: (300, 400 and 500) °C, respectively. Al2O3, 100Cr6 and CuZn balls were used as the counterparts. The wear tracks after the pin-on-disc testing were analyzed with scanning electron microscopy and a microanalysis. The experiments have shown a strong dependence of tribological parameters on the temperature. The friction coefficient of CrN-Ag against the 100Cr6 ball at ambient temperature was mi = 0.56. Tribological sliding tests of this coating system against the alumina balls indicate a decrease in the friction coefficient due to the increasing temperature. At ambient temperature mi = 0.68 and its minimum occurred at the temperature of 400 °C, mi = 0.24. This is attributed to the diffusion of Ag particles to the sliding top surface at elevated temperature. The testing against the CuZn brass ball generally gave a lower friction coefficient at ambient temperature, mi = 0.39. In contrast, the friction coefficient slightly increased with the increasing temperature and was practically constant at elevated temperatures, ranging between mi = 0.43-0.48.

06.11.2015