Nanoscale multilayer CrN/NbN PVD coatings are gaining reputation for their high corrosion and wear resistance. However the CrN/NbN films deposited by ABS TM (Arc Bond Sputtering) technology have some limitations such as macro droplets, porosity and less dense structures.The novel HIPIMS (High Power Impulse Magnetron Sputtering) technique produces macroparticle free, highly ionised metal plasma which brings advantages in both surface pretreatment and coating deposition stages of the PVD process.In this study, nanoscale multilayer CrN/NbN PVD coatings were pre-treated and deposited with HIPIMS technology and compared with those deposited by HIPIMS-UBM and by the 2 ABS TM technique. In all cases Cr + etching was utilised to enhance adhesion by low energy ion implantation. The coatings were deposited at 400° C with substrate biased (U b ) at -75 V.During coating deposition, HIPIMS produced significantly high activation of Nitrogen compared to the UBM as observed with mass spectroscopy.HIPIMS-deposited coatings revealed a bi-layer period of 4.1 nm (total thickness-2.9 µm) and hardness of 3025 HK 0.025 . TEM results revealed droplet free, denser microstructure with

Performance of HIPIMS deposited CrN/NbN nanostructured coatings exposed to 650°C in pure steam environment. Materials chemistry and physics, 179, 110-119.

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TiN films were deposited using High Power Impulse Magnetron Sputtering (HIPIMS) enabled four cathode industrial size coating system equipped with HIPIMS power supplies. The standard version of this system allows control over the ion bombardment during coating growth by varying the strength of the electromagnetic field of the unbalancing coils and bias voltage applied to the substrate. The coatings were produced in different coating growth conditions achieved in combined HIPIMS-direct current (DC) unbalanced magnetron sputtering (HIPIMS/UBM) processes where HIPIMS was used as an additional tool to manipulate the ionisation degree in the plasma. Four cathode combinations were explored with increasing contribution of HIPIMS namely 4UBM (pure UBM), 1HIPIMS+ 3UBM, 2HIPIMS+2UBM and 2HIPIMS (pure HIPIMS) to deposit TiN coatings. Optical emission spectroscopy (OES) measurements were carried out to examine the plasma generated by the various combinations of HIPIMS and UBM cathodes. The micro-structural study was done by scanning electron microscopy (SEM). X-ray diffraction (XRD) technique was used to calculate the residual stress and texture parameter. It has been revealed that the residual stress can be controlled in a wide range from-0.22 GPa to-11.67 GPa by intelligent selection of the degree of HIPIMS utilisation, strength of the electromagnetic field of the unbalancing coils and the bias voltage applied to the substrate while maintaining the stoichiometry of the coatings. The effect of the degree of HIPIMS utilisation on the microstructure, texture and residual stress is discussed. Combining HIPIMS with dc-UBM sputtering is also seen as an effective tool for improving the productivity of the deposition process.

Zirconium nitride (ZrN) coatings were deposited on 1 μm finish high speed steel and 316L stainless steel test coupons. Cathodic Arc (CA) and High Power Impulse Magnetron Sputtering (HIPIMS) + Unbalanced Magnetron Sputtering (UBM) techniques were utilized to deposit coatings. CA plasmas are known to be rich in metal and gas ions of the depositing species as well as macroparticles (droplets) emitted from the arc sports. Combining HIPIMS technique with UBM in the same deposition process facilitated increased ion bombardment on the depositing species during coating growth maintaining high deposition rate. Prior to coating deposition, substrates were pretreated with Zr+ rich plasma, for both arc deposited and HIPIMS deposited coatings, which led to a very high scratch adhesion value (LC2) of 100 N. Characterization results revealed the overall thickness of the coatings in the range of 2.5 μm with hardness in the range of 30–40 GPa depending on the deposition technique. Cross-sectional transmission electron microscopy and tribological experiments such as dry sliding wear tests and corrosion studies have been utilized to study the effects of ion bombardment on the structure and properties of these coatings. In all the cases, HIPIMS assisted UBM deposited coating fared equal or better than the arc deposited coatings, the reasons being discussed in this paper. Thus H+U coatings provide a good alternative to arc deposited where smooth, dense coatings are required and macrodroplets cannot be tolerated.