ICMCTF2009 Session B2-2: Arc and E-Beam Coatings and Technologies

Monday, April 27, 2009 1:30 PM in Room Golden West

Monday Afternoon

Start	Invited?	Item
1:30 PM	Invited	B2-2-1 Trends and Applications of Cathodic Arc Evaporation O. Zimmer (Fraunhofer Institute for Materiasl and Beam Technology, Germany); V. Weihnacht, H.-J. Scheibe (Fraunhofer Institute for Materials and Beam Technology, Germany) Cathodic vacuum arc evaporation (CVAE) is in industrial use since about 30 years. The main fields of applications are the cost effective deposition of hard protective coatings for tools and components as well as decorative coatings for faucets or plastic parts for example. Other fields are coatings with highest demands on film structure and mechanical properties for applications in micro technology. The different applications require different growth conditions to get the coating quality and to realize a sufficient productivity. These requirements can only be full filled by using optimized arc sources and advanced plasma cleaning processes. High rate processes for machine elements and high precision processes for micro applications demand different source concepts. Recent developments in evaporator technology enable the high rate deposition of advanced nano composite hard coatings for high end cutting applications. Also possible is the deposition of thicker films due to innovations in film structure. Cylindrical or rectangular cathodes with new concepts of weak and stronger magnetic fields are used to achieve highest plasma activation and low particle quantity. The using of pulsed arc sources is the preferable way for the deposition of hard amorphous carbon coatings (ta-C) in an industrial environment. At least plasma filtering is an additional tool to adjust film properties and opens the door for a lot of new applications. In the paper current developments in the area of arc evaporators, plasma filters, pulsed processes and film properties are discussed concerning technical aspects and applications.
2:10 PM		B2-2-3 Zirconium and Aluminum Arc Behavior and Ion Current Generation During Metal and Oxide Deposition I. Zukerman (Tel Aviv University / NRC-Negev, Israel); V.N. Zhitomirsky (Tel Aviv University, Isreal); A. Raveh (NRC-Negev, Israel); R.L. Boxman (Tel Aviv University, Israel); S.K. Kim (University of Ulsan, Korea) The operation of a vacuum arc plasma gun with Zr and Al truncated cone cathodes was studied. The arc operation and the cathode spot motion was studied in vacuum and in a 0.2-1 Pa oxygen background. The process parameters (arc current and voltage, and background gas pressure) as well as the ion current at the substrate, were continuously recorded during arcing. The influence of the deposition parameters arc current (25-175 A), axial magnetic field strength (0-10 mT), and oxygen pressure, on the arc behavior, electrode poisoning, ion flux and deposition rate was studied. It was found that the number of the cathode spots on the truncated cone-shaped cathodes in a confining magnetic field increased with the arc current Ia. However, with increasing Ia the spots tended to operate on the cathode conical periphery rather than on the cathode working base. Also, the ion current, and thus coating deposition rate increased as the arc current increased to 75 and 100 A for Al and Zr cathodes, respectively, and then sharply decreased. The deposition rate in the centers of the plasma beams estimated from the saturation ion current was 1.2 and 2.8 µm/min for Al (Ia=75 A) and Zr (100 A), respectively. During operation in oxygen, the arc behavior and the ion current changed with time. For the Zr arc at oxygen pressure ≥ 0.5 Pa, the ion current at the substrate decreased with time and the arc voltage increased, probably, due to the electrode poisoning.
2:30 PM		B2-2-4 Phase Formation in Oxide Layers Synthesized by Pulsed Arc Evaporation M. Doebeli (Ion Beam Physics, Paul Scherrer Institut and ETH Zuerich, Switzerland); A. Dommann (Centre Suisse d’Electronique et de Microtechnique Neuchâtel, Switzerland); J. Herrán (Centre Suisse d’Electronique et de Microtechnique Neuchâtel, Switzerlandand CEIT and Tecnun San Sebastian, Spain); E. Kalchbrenner (OC Oerlikon Balzers AG, Liechtenstein); A. Neels (University of Neuchâtel, Switzerland); J. Ramm, H. Rudigier (OC Oerlikon Balzers AG, Liechtenstein); J. Thomas (IFW Dresden, Germany); B. Widrig (OC Oerlikon Balzers AG, Liechtenstein) Pulsed arc evaporation (P3eTM) has been proven to synthesize a number of metallic oxides in a stable and reliable industrial deposition process. In previous reports, it was also shown, that this process allows the deposition of oxides which consist mainly of high temperature phases, e.g. the corundum-type structure for the solid solutions of Al-Cr-O. The formation process of high temperature phases in the Al-Cr-O material system has been investigated in more detail for the metallic interface consisting of Cr and Al-Cr. Investigations by transmission electron microscopy indicate a quasi-epitaxial interface between the Cr and the Al-Cr layers and an abrupt and sharp interface to the oxide layer. According to the analysis, the corundum-type structure in the Al-Cr-O layer is stabilized already in the vicinity of the interface. The crystallite size of the corundum-type structure, however, can be tailored by the process parameters and the oxygen partial pressure during the ar c evaporation process. X-ray diffraction analysis in combination with electron diffraction suggests oxide layers with a single phase besides minor metallic constituents in form of droplets. The analysis results are compared with the ternary Al-Cr-O phase diagram and possible phase formation mechanism are discussed.
2:50 PM		B2-2-5 Influence of Bias Pulsing on Structure and Properties of Arc-Evaporated (Al_1-xCr_x)₂O₃ Hard Coatings M. Pohler, G.A. Fontalvo, R. Franz (University of Leoben, Austria); D. Kurapov (OC Oerlikon Balzers AG, Liechtenstein); C. Polzer (PLANSEE Composite Materials GmbH, Austria); C. Mitterer (University of Leoben, Austria) Thermodynamically stable α-Al₂O₃ coatings produced by chemical vapor deposition are widely used on tools for high performance cutting operations due to their outstanding chemical inertness and high temperature resistance. During the last years, crystalline α-Al₂O₃ was successfully synthesized by physical vapor deposition techniques which allow a reduction of deposition temperature from ~1000 °C to ~600°C. Recent studies using cathodic arc evaporation showed that the addition of Cr is beneficial for the synthesis of a crystalline α-phase. These α-(Al_1-xCr_x)₂O₃ coatings are deposited at temperatures below 600°C using pulsed bias voltage. The aim of this work was to investigate the effect of varying the duty cycle of the pulsed bias on structure and properties of (Al_1-xCr_x)₂O₃ coatings. All coatings were deposited in an industrial scale cathodic arc evapor ation system using powder metallurgically produced targets with the composition Al₅₀Cr₅₀ and Al₇₀Cr₃₀. Synthesis was done in pure oxygen atmosphere at a substrate temperature of 550°C. An increase of the duty cycle of the symmetric bipolar pulsed bias from 70 % to 90 % increased the crystallinity of the coatings, as analyzed by X-ray diffraction. The grain size of, e.g., (Al_0.5Cr_0.5)₂O₃ increased from ~60 nm to ~110 nm. This results in an increase of the hardness from ~20 to ~33 Gpa, as measured by nanoindentation. In summary, the variation of the duty cycle presents a feasible way to improve the properties of (Al_1-xCr_x)₂O₃ coatings.
3:10 PM		B2-2-6 Deposition of ZrO₂/Al₂O₃ Thin Films by Cathodic Arc Plasma Deposition S.K. Kim, V.V. Le (University of Ulsan, Korea); J.W. Lee (KAIST, Korea); V.N. Zhitomirsky, R.L. Boxman (Tel Aviv University, Israel) Thin films of ZrO₂/Al₂O₃ thin films were deposited on SKD 11 tool steel substrate using Zr and Al cathodes by a cathodic arc plasma deposition system. The substrates were mounted on a rotating holder which alternatively exposed them to plasma from the two cathodes. The influence of the Zr and Al cathode arc currents and the substrate bias on the mechanical and the structural properties of the films were investigated. The hardness of the film decreased with the increase of Zr cathode current from 60 A to 80 A. The hardness of the film increased with the increase of bias voltage up to -200 V and then decreased with further increase of the negative bias. The film structure was elucidated by HRTEM microscopy.
3:50 PM		B2-2-9 Synthesis and Mechanical Properties of CrN_x Coatings Deposited by Arc Ion Plating M. Zhang, K.H. Kim (Pusan National University, Korea); G. Lin (School of Physics and Optoelectronic Technology, China); C. Dong (School of Material Science and Engineering, China) Compositional gradient CrN_x coatings were fabricated using arc ion plating by varying N₂ flow rate from 0 to 120 SCCM. The effects of negative substrate bias and deposition temperature on the coating growth and properties were systematically investigated with XRD, GDOES, SEM, TEM, Nanoindention, stress, adhesion and wear tests. The results showed that gradient CrN_x coatings mainly crystallized in fcc rocket-salt NaCl structure. Along the thickness direction of gradient CrN_x coatings, the content of ceramic phase increases and that of metal phase decreases gradually. By increasing substrate bias, the microstructure of the coatings evolved from an apparent columnar structure to equiaxed one. The coatings deposited at 150°C completed this evolution at a bias of -100V; while -200V in the case of 300 °C. The maximum hardness of 33GPa was obtained from the coatings deposited at a bias of -50V with a residual stress of -3.1GPa. It was also found that the adhesion strength and the wear resistance of gradient CrN_x coatings were better than that of homogeneous CrN coatings.
4:10 PM		B2-2-10 Characterization of Worn Ti-Si Cathodes used for Reactive Cathodic Arc Evaporation J. Zhu, A. Eriksson, N. Ghafoor (Linköping University, Sweden); M. Johansson (SECO Tools AB, Sweden); F. Giuliani (Linköping University, Sweden); J. Sjölén (SECO Tools AB, Sweden); L. Hultmann, J. Rosén, M. Odén (Linköping University, Sweden) Cathodic Arc Evaporation (CAE) is a common PVD technique to deposit hard coatings. As the source material for the coatings, the cathode is one of the key factors for this technique. It is widely acknowledged that a compound layer, which influences the plasma composition and charge state but also the erosion rate, forms on the cathode surface when used in a reactive gas. Up to now, there are only a limited numbers of reports on this layer. We have used SEM, XRD, FIB and TEM-EDX/EELS, to investigate the evolving microstructure and composition of the surface compound layer of the worn Ti1-xSix cathodes (x=0, 0.1, 0.2), which are employed to produce commercial TiSiN hard coatings. Virgin Ti_1-xSi_x cathodes, powder metallurgical fabricated, contain a hexagonal solid solution between Ti and Si. The cathode containing 20% Si has a two-phase structure with hexagonally shaped Ti₅Si₃ grains surrounded by fine Ti/Ti₅Si₃ eutectic microstructure. After arcing at a current of 60A and in a pure N2 atmosphere in an industrial-scale CAE system, the cathode is covered with a 4-10 µm thick compound layer on the surface. This compound layer consists of two distinctly different microstructures: (i) nanocrystalline equiaxed grains which are either Ti or Si rich, and on top of these (ii) columnar grains where the grain boundaries are depleted of Si. The nitrogen present in this layer and its role in forming new compounds is discussed. The arc erosion is observed to occur preferentially from Ti₅Si₃ grains over the eutectic, which results in a higher roughness of the cathode surface. The influence of the preferential erosion on the chemical composition in the plasma is also addressed.
4:30 PM		B2-2-11 Structure and Composition of Arc Deposited (Ti_1-xSi_x)(C_1-yN_y)_z Coatings A. Eriksson, J. Zhu, M. Odén (Linköping University, Sweden); M. Johansson, J. Sjölén (SECO Tools AB, Sweden); L. Hultman, J. Rosén (Linköping University, Sweden) The Ti-Si-C-N system is a promising candidate for wear resistant coatings. An increased understanding of the material as well as of the arc evaporation process is of importance for future applications and process development. Coatings in the quaternary Ti-Si-C-N system have been deposited using industrial scale cathodic arc evaporation. Two strategies were followed: (i) reactive arcing from conventional Ti-Si targets in mixtures of gaseous CH₄ and N₂, and (ii) reactive arcing from ternary Ti-Si-C targets, including Ti₃SiC₂ (Maxthal 312^TM) compound target, in N₂-atmosphere at various pressures. The as-deposited coatings resulting from the two methods are compared with respect to composition, microstructure and mechanical properties as determined by XRD, SEM, TEM, ERDA and nano-indentation. When arcing from ternary cathodes, nanocrystalline coatings were obtained, with Si and C concentrations of up to 12 and 27 at%, respectively. Microstructure and composition were found to be highly dependent on N₂-pressure. For the binary target approach, similar phase structures were obtained, but with generally lower level of C and N incorporation.