Deposition of nanoscale multilayer CrN/NbN physical vapor deposition coatings by high power impulse magnetron sputtering

Abstract

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

Substrate Finishing and Niobium Content Effects on the High-Temperature Corrosion Resistance in Steam Atmosphere of CrN/NbN Superlattice Coatings Deposited by PVD-HIPIMS

“…As-deposited coatings resistance as compared to monolithic coatings [13,23]. The thickness of consecutive layers of CrN and NbN is defined as the bi-layer thickness.…”

“…The capability of CrN/NbN coatings with droplet defects produced by arc etching followed by unbalanced magnetron sputtered (UBM) deposition in resisting oxidation [24], and that of coatings with superior microstructure produced by combined HIPIMS-UBM technique in resisting room temperature wet corrosion and tribo-corrosion has been documented earlier [23,24]. The main objective of this work was the evaluation of the oxidation behaviour of defect free (droplet free and dense structures) CrN/NbN coatings produced by HIPIMS technique on P92 steel at high temperature and wet corrosive conditions.…”

“…For example, during arc evaporation deposition or during arc etching in arc bond sputtering (ABS) process, spherical droplets (macro-defects) are produced which compromise the coating effectiveness generating a galvanic couple between the defect and the coating matrix or stresses accumulation at the droplet-coating interface [20]. Also porosity and under-dense structures, which have been reported to be present in coatings deposited by sputtering techniques, can compromise mechanical and corrosion properties to a large extent [20][21][22][23]. CrN/NbN coatings deposited by high power impulse magnetron sputtering (HIPIMS) technique have shown to overcome all these drawbacks, retaining the good adhesion produced by arc techniques, as well as the smooth dense structures produced by sputtering techniques [21][22][23].…”

Effect of chamber pressure on defect generation and their influence on corrosion and tribological properties of HIPIMS deposited CrN/NbN coatings

“…Both the corrosion and tribological performances of CrN/NbN coatings (deposited by Arc or conventional magnetron sputtering techniques) have already been investigated [21,22,31,32]. The benefits of using HIPIMS over conventional PVD to deposit CrN/NbN have been also demonstrated [16,33,34]. However, the impact of defects on the coating performance of HIPIMS deposited CrN/NbN was understudied and so far, very little attention was given towards the coatings defects associated with HIPIMS.…”

“…Previous studies have suggested that the corrosion properties of multilayer PVD coatings depend on their chemical composition, stress level, porosity and thickness as well as on the morphological defects of the coatings [7,16,[20][21][22]34]. To study the effect of the defects on corrosion performance of CrN/NbN nano-scale multilayer coatings, electrochemical corrosion tests were conducted.…”