Influence of Zr and O on the structure and properties of TiC(N) coatings deposited by magnetron sputtering of composite TiC 0.5 + ZrO 2 and (Ti, Zr)C 0.5 + ZrO 2 targets

Abstract

The effect of Zr and O incorporation on the structure and properties of TiC(N) coatings deposited by DC magnetron sputtering of composite TiC 0.5 + xZrO 2 ( x = 10 and 20 wt.%) and (Ti,Zr)C 0.5 + 10%ZrO 2 targets in an argon atmosphere or reactively in a gaseous mixture of Ar + N 2 is presented. The structure, elemental and phase composition of the coatings were studied by means of X-ray diffraction, scanning electron microscopy, and glow discharge optical emission spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, and elastic recovery using the load–depth-sensing nanoindentation method. Tribological properties were investigated using ball-on-disk tests against cemented carbide at 25 °C and alumina in the temperature range of 25–500 °C. To evaluate the oxidation resistance, the coatings were annealed in air at 400, 550, and 600 °C for 1 h. The obtained results show that the TiZrCO(N) coatings exhibit a peak hardness versus nitrogen partial pressure. The coatings with maximum hardness tested at room temperature against WC + Co and Al 2O 3 counterparts showed low friction coefficients below 0.25. At higher temperatures 300–500 °C, the friction coefficient against an Al 2O 3 ball was recorded to be 0.6. The tribological tests of the coatings demonstrated their high wear resistance at moderate temperatures 25–300 °C (wear rate, k ~ 10 − 6 mm 3N − 1 m − 1 ). Moreover, the coatings with high Zr content were the most wear resistant. The oxidation resistance of the Zr-doped TiCON coatings was not as high as expected and restricted by 600 °C. The combination of high hardness about 40 GPa with low friction coefficient and superior wear resistance makes the TiZrCON coatings promising candidates for various dry tribological applications.