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Chromium nitride coatings were prepared by reactive DC-superimposed high-power-impulse magnetron sputtering (HiPIMS) system. The influence of substrate bias on the microstructure and mechanical properties of CrN coatings was investigated. XRD and cross-sectional SEM were utilized to characterize the film structures. Mechanical properties were characterized by nanoindentation and Vickers indentation test. The results revealed that the microstructure and mechanical properties of CrN coatings were affected by bias voltage. The CrN coatings exhibited dense and fine columnar grain structure with the hardness of about 18.7 GPa. The fracture toughness of CrN coatings was around 3.16 MPa ⋅ m${}^{1/2}$. However, further increase of the bias voltage from −250 V to −300 V led to the degradation of coating properties.

In the present study, TiN coatings have been deposited on D2 tool steel substrates by using cathodic arc physical vapor deposition technique. The objective of this research work is to determine the usefulness of TiN coatings in order to improve the micro-Vickers hardness and friction coefficient of TiN coating deposited on D2 tool steel, which is widely used in tooling applications. A Pin-on-Disc test was carried out to study the coefficient of friction versus sliding distance of TiN coating deposited at various substrate biases. The standard deviation parameter during tribo-test result showed that the coating deposited at substrate bias of -75 V was the most stable coating. A significant increase in micro-Vickers hardness was recorded, when substrate bias was reduced from -150 V to zero. Scratch tester was used to compare the critical loads for coatings deposited at different bias voltages and the adhesion achievable was demonstrated with relevance to the various modes, scratch macroscopic analysis, critical load, acoustic emission and penetration depth. A considerable improvement in TiN coatings was observed as a function of various substrate bias voltages.

RF magnetron-sputtered CrCuN coatings with ultra-low Cu content (0.53–2.1 at.%) were deposited using Cr${}_{97}$Cu₃ target (at.%) by changing the substrate negative bias from 0V to $-$200V. The CrNiN coatings with different nickel contents (0, 2.92 and 8.79 at.%) were sputtered by different-component Cr–Ni alloy targets (Cr, Cr${}_{95}$Ni₅ and Cr${}_{80}$Ni${}_{20}$, in at.%). The effect of bias and alloying element content on coating toughness was investigated by nanoindentation. The results show that all the coatings have unsatisfied toughness because of $H$/$E^{*}<0.1$. With increasing bias, the toughness of CrN and CrCuN coatings improves basically due to grain refinement caused by high bias effect. Under the same bias, although CrCuN coatings have finer grains, their toughness is still lower than that of CrN coatings because of inadequate copper coverage degree as a result of ultra-low copper content. On the contrary, once there is an appropriate alloying element content of 2.92 at.% Ni, the toughness of CrNiN coatings increases with the nickel content due to relatively higher Ni coverage degree.

The primary problem of large intrinsic compressive stress induced during the deposition of amorphous carbon (a-C) films prepared by Filtered Cathodic Vacuum Arc (FCVA) technique has been overcome by preparing the films in conjuction with high substrate pulse biasing. However, it has been observed that the stress reduction is achieved by sacrificing the mechanical properties such as hardness and Young's modulus of the films. Hence the mechanical properties of the films were studied as a function of substrate bias voltage. In addition, to demostrate these low stress films, one-micron thick, a-C membranes were fabricated by photolithography technique together with deep reactive ion etching (deep RIE) and wet KOH etching.