Tribological properties of nanostructured TiAlN/W2N multilayer coating produced by PVD

Abstract

TiAlN/W2N multilayer coatings with various modulation periods from 140 to 680 nm were deposited on AISI 304 L SS by multi-arc ion plating and DC magnetron sputtering. The phase structures and chemical compositions of the as-prepared TiAlN/W2N multilayer coatings were investigated by a grazing incidence X-ray diffraction (GIXRD) and an energy dispersive spectrometer (EDS), respectively. The cross-sectional morphology, adhesion strength, hardness, and friction and wear behavior of the resulting TiAlN/W2N multilayer coatings were evaluated in detail. The results show that the as-prepared TiAlN/W2N coatings with different modulation periods are featured with a face-centered cubic (fcc) structure and have a dense and compact multilayer structure. The adhesion strengths of the TiAlN/W2N multilayer coating decrease gradually with the decreasing of the modulation periods from 680 to 140 nm, which results from more residual stress accumulated with the increasing numbers of the coating layers. The multilayered coating with the modulation period of 373 nm exhibits the maximum hardness of 1757 kgf·mm−2 and the lowest wear rate of 2.52 × 10−6 mm3(Nm)−1 among all samples. In addition, the TiAlN/W2N multilayer coating presents better tribological properties under high temperature than under room temperature due to a large number of oxide mixture (WO3, Al2O3, TiO2) produced on the wear surface during the rubbing process. The produced WO3 has a self-lubrication effect because of its special layered structure and high ionic potential, and other dense oxide mixture can prevent further oxidation of the multilayered coating.