Wear behavior of Cr1−xAlxN PVD-coatings in dry running conditions

In the presented investigation magnetron sputtered chromium aluminum nitride (Cr1−xAlx)N coatings are examined on their tribological characteristics with regard to the aluminum content. Three (Cr1−xAlx)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 Al2O3 and Si3N4 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 Al2O3 used as counterpart material leads to lower friction coefficients than Si3N4 balls. The counterpart wear for Al2O3 was less than for Si3N4. On the contrary, the highest wear rates of coated samples were measured for tribological contacts with Al2O3. With regard to the coatings, Cr0.77Al0.23N showed the lowest wear rates in all cases, though the friction coefficient Cr0.77Al0.23N of against Si3N4 was the highest.