Large-Scale Manufacturing of Nanoscale Multilayered Hard Coatings Deposited by Cathodic Arc/Unbalanced Magnetron Sputter
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Large-Scale
Manufacturing of Nanoscale Multilayered Hard Coatings Deposited by Cathodic Arc/ Unbalanced Magnetron Sputtering W.-D. Münz
Abstract
period, as published by researchers at Linköping University and the University of Illinois.1 Magnetron sputtering has been found to be the most appropriate deposition technology,2–6 although some attempts have also been made to deposit such coatings by cathodic arc technology.7 Table I shows that the sliding-wear coefficient of nanoscale-architectured multilayers is in a range three orders of magnitude lower than that of electroplated hard chromium and up to two orders of magnitude lower than that of monolithically grown TiN and CrN. Low sliding-wear coefficients are achieved if one succeeds in keeping the coefficient of friction low, as shown for TiAlN/VN, where a coefficient of friction of 0.4 may be achieved, compared with 0.65 for TiAlN-based coatings without a VN component. A drawback of nanoscale multilayered coatings is their very high compressive residual stress values, which range up to 7 GPa. These stress values demand extraordinarily high adhesion qualities, which can be achieved by applying the arc bond sputter (ABS) technique8— a combination of cathodic arc evaporation and unbalanced magnetron sputtering, which we will discuss later. Figure 2 describes the family of superlattice coatings developed at Sheffield Hallam University (SHU) in England. A nanoscale multilayered coating consisting of TiAlCr0.03N and TiAlYN with a bilayer thickness of 1.7 nm has been developed to satisfy high-temperature (950C) applications such as dry high-speed cutting of die steel.9,10 TiAlN/VN is also designed for cutting operations. However, the incorporation of VN in the coating introduces a
Nanoscale multilayered (superlattice) hard coatings can be manufactured in a plastic hardness range (HP) between 25 GPa and 55 GPa by a combination of cathodic arc evaporation and unbalanced magnetron sputtering (arc bond sputter technology). Using large-scale industrial physical vapor deposition (PVD) equipment and a sufficiently high pumping speed, multilayered coatings can be deposited by simultaneously operating cathodes without special shutter and shielding facilities in a common reactive-gas atmosphere. The efficiency of the process is in many cases identical to that of TiN and CrN. Temperature-resistant, wear-resistant, and corrosion-resistant coatings of various compositions have been produced under industrial conditions. So far, the main applications concentrate on metal-forming and on cutting die steel, Inconel, stainless steel, and titanium. Applications have also been found in the chemical, textile, medical, and automotive industries. Keywords: anticorrosion properties, cathodic arc/unbalanced magnetron (CA/UBM) sputtering, friction reduction, nanoscale multilayers, physical vapor deposition (PVD), superhard coating materials, superlattices, wear resistance.
Introduction Since the discovery of enhanced hardness in nanoscale multilayers (superlattices) with typical bilayer th
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