Effects of Benzotriazole on nano-mechanical properties of zirconia–alumina–Benzotriazole nanocomposite coating deposited on Al 2024 by the sol–gel method

Abstract

The concentration of Benzotriazole plays an important role in the mechanical properties of ceramic coatings. In this work, hybrid nano-composite zirconia–alumina–Benzotriazole coatings with 1.2, 2.4, 3.6 and 4.8% of Benzotriazole are deposited on the Al 2024 substrate by the sol–gel technique. The phase, structure, and morphology are determined by grazing-incidence X-ray diffraction, Fourier-transform infrared spectroscopy, and field-emission scanning electron microscopy and the nano-mechanical properties are assessed by atomic force microscopy at loads of 50 and 60 µN. Uniform and homogenous amorphous coatings are deposited at 150 °C and the thicknesses of the zirconia–alumina and zirconia–alumina–Benzotriazole coatings with 1.2%, 2.4%, 3.6%, and 4.8% Benzotriazole are 670, 560, 750, 790, and 1040 nm, respectively. The surface roughness of the coatings decreases by 3.5 and 8 times after introducing 1.2% and 3.6% Benzotriazole to the coatings, respectively, but further increasing the Benzotriazole concentration from 3.6 to 4.8% decreases the hardness, strength, and maximum shear tension. The optimal concentration of Benzotriazole depends on the Hertzian pressure and the hardness and strength of the zirconia–alumina–3.6% Benzotriazole under a load of 60 µN are 23 and 46 times higher than those of the zirconia–alumina coating. The smallest friction coefficient of 0.11 is observed at a load of 60 µN and abrasive wear and shear are dominant.