Nitrogen flux effect on the mechanical properties of AlCrTiN Nanostructured coatings obtained by R. F. magnetron sputtering

AlCrTiN coatings were obtained by radio frequency magnetron sputtering and deposited on aluminum-silicon alloy substrates (A4032). The microstructure, morphology and chemical composition of the coatings were analyzed by X-ray diffraction, Transmission Electron Microscopy, Scanning Electron Microscopy, Energy Dispersive X-ray spectroscopy, and X-ray Photoelectron Spectroscopy. The effect of nitrogen flow on hardness, wear resistance, and adhesion was investigated and correlated with the microstructure of the samples. The coatings crystallized in a hexagonal Wurtzite structure with preferential growth on the (002) direction. With increasing nitrogen flow, a decrease of the crystallite size is observed. The mechanical properties of AlCrTiN coatings on an aluminum-silicon alloy showed characteristics of interest for industrial applications: the coated substrates showed better hardness (around of 10.5 GPa), improved wear resistance (COF similar to 0.3) and increased fracture toughness (H-3/E-2 around 0.23), compared to the uncoated substrate (1.41 GPa, 0.42, and 0.0014, respectively).