Wear behavior of Cr 1− xAl xN PVD-coatings in dry running conditions

Abstract

In the presented investigation magnetron sputtered chromium aluminum nitride (Cr 1− x Al x )N coatings are examined on their tribological characteristics with regard to the aluminum content. Three (Cr 1− x Al x )N coatings with different aluminum contents ( x = 0; 0.23; 1) are compared in dry running conditions. The tests were performed in a ball-on-disc (BoD) tribometer. The ceramics Al 2O 3 and Si 3N 4 were used as counterpart materials. The analysis of tribological contact partners included the determination of friction coefficients, wear rates and wear debris. Laser profilometry, light microscopy and scanning electron microscopy (SEM) were used for examination of the wear tracks. The chemical analyses of wear debris of the coated samples were carried out by energy dispersive X-ray spectroscopy (EDX) and by X-ray photoelectron spectroscopy (XPS). In general Al 2O 3 used as counterpart material leads to lower friction coefficients than Si 3N 4 balls. The counterpart wear for Al 2O 3 was less than for Si 3N 4. On the contrary, the highest wear rates of coated samples were measured for tribological contacts with Al 2O 3. With regard to the coatings, Cr 0.77Al 0.23N showed the lowest wear rates in all cases, though the friction coefficient Cr 0.77Al 0.23N of against Si 3N 4 was the highest.