Papers

ICMCTF2005 Session B2-2: Arc and E-Beam Coatings and Technologies

Tuesday, May 3, 2005 1:30 PM in Room Sunset

Tuesday Afternoon

Start	Invited?	Item
1:30 PM		B2-2-1 High Current Pulsed Arc for Nano-Materials Applications: Developments in Electronic Discharge Triggering, Cathode Spot Control and Multilayer Deposition L. Ryves, R.N. Tarrant (University of Sydney, Australia); T.W.H. Oates (Forschungszentrum Rossendorf, Germany); M.M.M Bilek, D.R. McKenzie (University of Sydney, Australia) We have developed a filtered, multiple source, high current pulsed arc system to deposit nanometre scale multilayered composite coatings. The deposition rate of DC cathodic arcs suffers from large fluctuations due to the random motion of a small number of spots over the surface of the cathode. In contrast, a high current (1 to 3kA) mode of operation produces a large number of arc spots. By initiating these spots in the centre of the cathode and terminating the current pulse a short time later (<1ms), cathode spot motion can be effectively controlled for optimum consistency in depositing flux. The material to be fired is selected by triggering the arc on one cathode (or the other) via an electronic discharge across the surface of an insulator. The reliability of the triggering system has been studied as a function of pulse current, voltage and length for different cathode materials. Initial experiments showed a non-uniform cathode wear profile after more than 50,000 pulses. An arc current waveform during the pulse has been developed to optimise pulse to pulse repeatability and cathode material use. Alloying or deposition of multilayer coatings requires a method of alternating between different cathode materials. We use two cathodes inside parallel cylindrical anodes, with both beams of plasma filtered through a common magnetic duct to remove neutral particles. Despite using two separate entry points to the magnetic field, it is possible to have the deposition profiles from both cathodes largely overlapping at the substrate, which is necessary for multilayer deposition. The ion flux was maximised by adjusting the magnetic field amplitude and profile, giving deposition rates of up to 0.2 and 0.34 Angstrom per pulse for carbon and titanium respectively. Pulsed 10 times per second, our system has a mean deposition rate comparable with DC cathodic arc and other PVD technologies. Examples of the deposition capability of the system will be presented.
1:50 PM		B2-2-2 Influence of Background Gas Pressure on Copper Film Deposition and Ion Current in a Hot Refractory Anode Vacuum Arc I.I. Beilis, A. Shashurin, R.L. Boxman, S. Goldsmith (Tel-Aviv University, Israel) The Hot Refractory Anode Vacuum Arc (HRAVA) is a metallic plasma source that can deposit films with strongly reduced macroparticle contamination in comparison with conventional vacuum arcs. In the HRAVA, plasma expands radially to deposit upon substrates circumferentially disposed around the electrode axis. In the present work, the angular film distribution and the influence of different background gases on the ion current and films were studied. The arc was sustained between a cylindrical Cu cathode of 30 mm diameter and molybdenum anode of 32 mm diameter and 30 mm height. The experiments were conducted with arc currents of I_arc=200A, inter-electrode distance about 1cm. The gas (He, N₂ and Ar) was entered into the chamber through an electrically controlled needle valve. Films were deposited onto glass microscope slide substrates. Two types of experiments were conducted: (1) four slides (26x76 mm) were placed on the inside chamber wall evenly spaced around the electrode axis at a distance of L=8 cm and deposited for times t_dep=15, 30, 45, 60, 90, 120, and 150 s in vacuo. (2) 15x25mm² slides were placed at L=11 cm and deposited in different gases and it pressures for time t_dep = 60 s. The film thickness was measured by profilometry. The ion current was measured by a circular flat probe of 1 cm diameter biased at -50V with respect to the anode and placed at the same distance from the electrode axis as (2) with an arc duration of 100 s. Experiment (1) showed that film thickness was uniform with azimuthal angle within approximately 10%, for all t_dep. The film thickness was about 0.9 µm within a band with a width of about 1 cm for t_dep = 60 s. In Experiment (2) the film thickness was 0.35 µm`, independent of gas pressure p, below some critical value p_cr. For p>p_cr, the film thickness decreased with p, eventually reaching 0. The value of p_cr was less for gases with larger molecular weight - 100, 10 and 1 mTorr for He, N₂ and Ar respectively. The ion current in vacuo increased with time and reached a saturation value of approximately 6 mA after about 60 s from arc ignition. The ion flux fraction in the total deposition mass flux was estimated to be about 80% (t_dep=60 s). The steady-state ion current was depended on gas pressure in a similar way as the deposited film thickness.
2:10 PM		B2-2-3 Current Issues in Arc Deposition Technology: An Industry Perspective L. Karlsson (SECO Tools AB, Sweden); L. Hultman (Linköping University, Sweden) About 90% of all indexable inserts for metal cutting, based on cemented carbide substrates, are coated for wear protection by CVD or PVD techniques, whereof PVD stands for ~20-30%. For a full range cutting tool supplier both the CVD- and the PVD-technology are necessary in order to be able to optimise a product for a given application area. The important issue for the future is not which deposition technology used, instead what properties can be achieved to what production cost. (Ti,Al)N coatings became common in the middle of 1990s and still show significant development potential. Arc evaporation has during the last decade grown to become the most important deposition technology for Al containing nitrides. The drive has been towards an increased Al content in the coatings and as high as Ti_0.3Al_0.7N is now often used. This presentation will give an industrialists perspective on the trends of coating material and deposition process development, and some likely developments in the future in this expanding field. Examples will be provided from our resent studies and on analysis of different coating material systems and their applications. (1)Coating material development of today focus on four different routes: (2)ncreasing the oxidation resistance by using different alloying of (Al,Ti,Me)(N,O) where Me is one or several of Si, Cr and Y. (3)Increasing the thermal stability by fine-tuning the composition and deposition condition. (4)Micro- and nanostructural optimisation. Here, the importance of sample fixture rotation and variation of coating flux by angular position on microstructural development has attracted attention. We believe that future opportunities for improved performance will be based on: (1)Increased understanding of the wear mechanisms dominating in different cutting applications in combination with fundamental mapping of existing and new coating materials. (2)New combinations of layers will give optimised coatings based on demands of specific applications. (3)Application of age hardening schemes by secondary phase transformations in metastable multinary systems. Two possibilities exist, self-organization during deposition or self-adaptation during service. (4)Computations in materials science today can be used for both making precise predictions and offering explanations to phenomena in materials processing and properties, e.g., ab initio calculations applied to the phase stability of several ternary nitride systems. In addition, the single most important factor, which slows down the development of new arc evaporated coatings, is actually related to difficulties finding high quality targets alloyed to your demand at a reasonable price. Also, simple things such that the PVD-system suppliers all develop their own arc sources, using different target dimensions, limits a faster development due to lack of standardisation. Finally, in many aspects Alumina is still the preferred coating material for many application areas. As a tool supplier, the important question is when we can expect PVD-Al₂O₃ to be on the market, if ever?
2:50 PM		B2-2-5 Effect of Ion Energy on Structure and Composition of Cathodic Arc Deposited Alumina Thin Films J. Rosen (RWTH Aachen, Germany); S. Mraz (RWTH-Aachen, Germany); U. Kreissig (Research Center Rossendorf, Germany); D. Music, J.M. Schneider (RWTH-Aachen, Germany) The effect of ion energy and substrate temperature on the film composition and microstructure has been investigated for cathodic arc deposited alumina thin films. At a substrate bias potential of -50 V, the films were amorphous or weakly crystalline, with an understoichiometric O/Al ratio for the growth temperatures below 500°C. Correspondingly, a substrate bias potential below -100 V resulted in stoichiometric crystalline films; a mixture of the α- and γ-phase above 700°C, and clearly γ-phase dominated films at temperatures as low as 200°C. The grain size of all films was < 10 nm. Combined constitution and grain size data is consistent with previous work stating that γ-alumina is thermodynamically stable at grain sizes < 12 nm. To correlate phase formation with synthesis conditions, the plasma chemistry and ion energy distribution was measured at conditions employed for thin film growth. Due to charge dependent acceleration when using a substrate bias potential, -100 V was shown to result in a total ion energy distribution with energies up to 400 eV. These results contribute towards understanding of the evolution of film composition and microstructure, and is illustrating a pathway to γ-alumina growth at temperatures as low as 200°C. This may be technologically important for the deposition on heat sensitive substrate materials.
3:10 PM		B2-2-6 Combination of Ion Plating and Metal Ion Implantation for Low- Temperature Coating on Rapid Prototyping Materials P.K. Singh, A.N. Panckow (Otto-von-Guericke University, Germany) The transition metal nitrides TiN and CrN are well known compounds displaying a rather high hardness, resistance against wear and corrosion, thus enabling their use as wear resistant hard coatings. On the basis of the elements titanium, chromium and nitrogen, series of coatings were prepared using a combination of vacuum arc ion-plating and metal plasma ion implantation. Hybrid ion-plating techniques by applying an electromagnetic enhanced arc source and a d.c. magnetron sputtering source were used for the deposition of the coatings. The applied metal vapor vacuum arc (MEVVA) ion source was equipped with either a Cr or a Ti-cathode, a low-frequency ignition system and high voltage supplies for the ion acceleration and plasma shielding. A low-temperature PVD technique was developed by combining the deposition process with a metal plasma ion implantation (MPII). The substrate temperature was kept below 50°C for polymers and 150°C for metal parts by applying pulsed bias voltage during the surface refinement of the thermal sensible rapid- prototyping (RP) materials. Polished cemented carbide inserts with simple geometry were used as samples for the physical characterization of the coatings. Electron microscopy techniques (SEM, TEM, EDX) and nanoindentation methods were performed for the characterization of the microstructural and physical properties (hardness, elastic modulus, wear, adhesion) of the surface refined RP-parts respectively. It will be shown that the physical properties of the coatings were clearly influenced by the special parameters of the combined low-temperature PVD process. Especially, the effect of the metal ion implantation into the surface region of the RP materials before and during the deposition will be discussed.
3:30 PM		B2-2-7 Changes in Microstructural and Mechanical Properties of TiAlN/Metal Nitride Multilayers by Thermal Annealing K. Ichijo, T. Yamamoto, H. Hasegawa (Keio University, Japan); K. Yamamoto (Kobe Steel Ltd., Japan); T. Suzuki (Keio University, Japan) Recently, hybrid coating system has been developed [1] which can synthesize TiAlN based nano-composite coatings and nano-multilayers from both arc and sputter sources. TiAlN/metal nitride nano-multilayers such as TiAlN/WN and TiAlN/MoN were synthesized by the combination of AIP (arc ion plating) and UBM (unbalanced magnetron sputter) method. Ti_0.5-Al_0.5 alloy and metal targets such as W and Mo were evaporated by the AIP and UBM sputter source, respectively with different sputter powers from 0 to 2.5kW under Ar-N₂ atmosphere. The lattice parameter of TiAlN/WN and TiAlN/MoN increased from 0.414 nm to 0.420 nm at W and Mo content of 20 at %. The thickness of each layer was approximately 20nm at substrate rotation speed of 5 rpm. In this study, structural changes and thermal stability of TiAlN/MoN and TiAlN/WN films at annealing temperature between 800 and 1000 °C were investigated. Changes in structural and mechanical properties are discussed based on the analysis by the X-ray diffraction method, transmission electron microscopy and the nano- indentation measurement. [1] K. Yamamoto et al. presented at ICMCTF 2004, Sandiego B8-1-4.
3:50 PM		B2-2-8 Deposition of Yttria-Stablized Zirconia Films using Arc Ion Plating J.T. Chang, C.H. Yeh, J.L. He, K.C. Chen (Feng Chia University, Taiwan); A. Matthews, A. Leyland (The University of Sheffield, United Kingdom) Arc ion plating is known to be capable of producing crystalline ceramic films at low deposition temperatures and may possibly be applied to the production of functional zirconia films which are commonly used in thermal barrier coatings, fuel cells and gas sensors. In this study, yttria-stablized zirconia (YSZ) films were deposited on Alloy 600 nickel-based superalloy by an arc ion plating system utilizing a single 84Zr-16Y alloy cathode. The working pressure, substrate bias voltage and substrate-to-cathode distance were varied systematically in order to reveal their effects on the growth behavior and microstructure of the YSZ films, which is important when considering future applications. Experimental results show that the arc motion can be stabilized on the cathode at working pressures below 4.0 Pa and provide enhanced film quality at 0.6 Pa. Our results show that yttria-stablized zirconia films with a mixed crystalline cubic and tetragonal structure can be synthesized at a temperature about 400 Celsius degree without in-situ substrate heating. Film growth rates ranged from 11 to 18 micrometer/h for all deposition conditions. Regardless of the substrate-to-cathode distance, the film growth rate increases with negative substrate bias voltage below 400 V, and at negative bias levels above this it decreases, reflecting the competition between the arriving ion flux and the resputtering effect. By taking account of process parameter effects such as these, it was possible to optimize the film quality for specific requirements.
4:10 PM		B2-2-9 Erosion Resistance Coatings Base on the TiN, Produced by Modification of Vacuum Arc Deposition V.A. Zavaleyev, V.T. Tolok, A.A. Romanov (Kharkov National University, Ukraine); V.I. Farenik (Scientific Physics and Technics Center, Ukraine); I.M. Neklyudov, V.V. Kunchenko, Y.V. Kunchenko (National Scientific Center, Kharkov Physics and Technology Institute, Ukraine) It is shown that monolayer monoplane (TiN_x) columnar structures and micro layer composites TiN_x, Ti with different setting rations of layers can be produced on dependence of parameters impulse high energy Ti ions (Ion Energy about 2 or 3 KeV) bombardment in process of vacuum-arc deposition (condensation with low-temperature, CILT method). Regularity of changing the produced coatings erosion resistance depending on their structure was determined. Possibility to produce coatings on the base of micro layer composition TiN_x,Ti ensuring multiple (up 100 times) to increase coefficient of erosion resistance compared with not coated BT-8 alloy was shown. Complex method of cavitations erosion coating express test in water-sand suspension was developed.