Mechanical properties of gradient and multilayered TiAlSiN hard coatings

Multicomponent coatings based on different metallic and non-metallic elements possess the combined benefit of individual components leading to further improvement of coating properties. In this study, monolayered Ti–Al–N, multilayered Ti–Al–N/TiN, gradient Ti–Al–Si–N, and multilayered Ti–Al–Si–N/TiN coatings were synthesized by using a cathodic-arc evaporation (CAE) system. In addition to Ti, Ti33Al67 and Al88Si12 cathodes were used for the deposition of Ti–Al–N, and Ti–Al–Si–N coatings, respectively. The gradient Ti0.50Al0.43Si0.07N, and multilayered Ti0.50Al0.43Si0.07N/TiN with nanograins separated by disordered grain boundaries possessed lower residual stress (− 2.8 ~ − 4.8 GPa) than that of monolayered Ti–Al–N (− 6.8 GPa) and multilayered Ti–Al–N/TiN coatings (− 5.7 GPa). The highest hardness was obtained for the gradient Ti0.50Al0.43Si0.07N (38 ± 2 GPa) with Ti/(Ti + Al + Si) content ratio being 0.5. On the contrary, the multilayered Ti0.50Al0.43Si0.07N/TiN possessed the highest H3/E⁎2 ratio of 0.182 ± 0.003 GPa, indicating the best resistance to plastic deformation, among the studied coatings.