Structure, mechanical properties and tribocorrosion behaviours of superhard TiSiCN nanocomposite coatings

Superhard coatings are no longer very difficult to obtain, but the direct observation and prediction of their failure are still a challenge. 3D tomography of the microcracks in coating failure offers lots of new information on the geometric shape, size, and spatial structure relationship of microcracks which was not available up to now. Hence, in this work, cross-scale visualization analysis of the microcrack network in superhard yet toughness TiSiCN coatings around indentations was achieved through advanced 3D tomography combined with HRTEM characterization. TiSiCN nanocomposite coatings were deposited by high-power pulsed magnetron sputtering. Superhard TiSiCN coatings exhibit a simultaneous superhardness of 48 ± 6.99 GPa and favorable toughness due to fully dense microstructure and smooth surface morphology. Due to the excellent crack initiation resistance and super-high hardness, superhard TiSiCN coatings show enhanced tribocorrosion performance in 3.5 wt% NaCl aqueous solution, with a low coefficient of friction of 0.11 and low specific wear rates of 3.23 × 10⁻⁶ mm⁻³N⁻¹m⁻¹.