ICMCTF2001 Session B1-3: Arc Technologies

Wednesday, May 2, 2001 1:30 PM in Room Golden West
Wednesday Afternoon

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Start Invited? Item
1:30 PM B1-3-1 A Simple Cathodic Arc Macroparticle Filter
J.R. Treglio (Cutting Edge Products, Inc.)
For many applications, the droplets, or macroparticles, produced by the cathodic arc are unacceptable. Various schemes have bee developed to filter the macroparticles out of the arc, the most commonly used involves a bent solenoidal magnetic field1. However, these methods are generally very complex, expensive, and much of the arc plasma is lost in transit. A new arc filter system has been developed that is substantially simpler than other systems. The plasma transition efficiency has been measured to be greater than 35%. Films produced by the method are almost 100% free of macroparticles. It has been used to deposit a variety of coatings, including Cr2N, CrN, TiN, and ZrN, as well as pure Ti coatings.


1I. I. Aksenov, V. A. Belous, V. G. Padalka, V. M. Khoroshikh, Sov. J. Plasma Phys. 4(4) (1978) 425.

1:50 PM Invited B1-3-2 Laser-Arc - Laser-Induced, Pulsed Vacuum Arc Deposition: Process, Technology and Applications
H.-J. Scheibe, C.-F. Meyer, B. Schultrich, P. Siemroth (Fraunhofer Institute for Materials and Beam Technology, Germany)
Vacuum arc deposition (VAD) is established for plasma-assisted thin film deposition. VAD is characterized by a high energy efficiency for the production of a fully ionized plasma with high kinetic ion energy. Therefore, dense, hard coatings with good adherence to the substrate may be produced on industrial scale with high throughput. VAD has been mainly performed in the d.c. mode using permanently burning arcs. The random movement of the cathode spots of such more or less freely burning arcs leads to instabilities of the discharge, unequal erosion of the cathode surface and random overheating. Consequently droplets are ejected from the cathode that may deteriorate the quality of the growing film. To overcome these drawbacks of conventional arc technique, the method of laser-induced, pulsed vacuum arc deposition was been developed with the aim to get a very controlled arc deposition process. At the Laser-Arc process the arc discharge is guided on the cathode surface in a highly controlled manner by the position of the igniting laser pulses. A very regular erosion of the cathode material is achieved by linear scanning of the laser beam and rotation of the cylindrical formed cathode made from graphite or other conducting material. An overview will be given on the development of the Laser-Arc technique from the basic process in the laboratory scale to the industrial applicable deposition source. For the retrofit of industrial standard deposition devices a Laser-Arc module (LAM) will be presented. A newly developed filter arrangement will be discussed, which can be integrated into the basic Laser-Arc technology for a nearly completely separation of particles from the plasma. Representative examples of Laser-Arc films , especially of superhard amorphous carbon films (Diamor® ) will be presented. Their potential for industrial applications is discussed.
2:30 PM B1-3-4 Preparation of Ti Targets with Different Grain Size for the Arc Ion Plating Method
A. Kimura, T. Suzuki (Keio University, Japan)

Novel ceramics films has been tried to synthesize by the arc ion plating method by changing raw materials, so called targets. In this method, atoms or clusters evaporated from surface of targets by arc-discharge were ionized, reacted with process gases and reach substrates as films. However, effects of microstructures of targets on properties of synthesized films have not been fully understood so far. Keeping this fact in mind, we sintered Ti targets with different microstructures to synthesize TiN films and investigate the effects of microstructures of targets.

Ti powders with different particle size of ~ 40, ~ 80 and ~120 µm were hot-pressed with 15 MPa in vacuum at 1100 °C, respectively. Three Ti targets with density of all ~ 4.5 g/cm3 were arc-discharged with 100 A under nitrogen plasma circumstance at 3.3 Pa. The TiN films were deposited on cemented carbide and Si substrates which were biased at -20 V and ~ 500 °C. Both Ti targets and TiN films were analyzed on particle size, hardness and composition by optical microscopy, scanning electron microscopy, micro-Vickers hardness test and X-ray diffraction method. Further, microstructures of TiN films were observed in detail through transmission electron microscopy.

2:50 PM B1-3-5 Calculation and Measurement of the Time Dependend Erosion Rate of Electromagnetically Steered Rectangular Arc Cathodes
Otmar Zimmer (Fraunhofer Institute for Material and Beam Technology, Germany); J. Vetter (Metaplas Ionon GmbH, Germany); N. Rackwitz, P. Siemroth (Fraunhofer Institute for Material and Beam Technology, Germany)
ProArc is a system for programable electromagnetic controlling of the arc spot motion on large area flat cathodes in devices for vacuum arc evaporation. By using this system predefined erosion and deposition profiles can be adjusted and the lifetime of the cathodes can be increased. For various run-modes the arc spot traces and erosion-profiles where calculated. The calculation enables an estimation of the local erosion rates in dependence both on time and magnetic field strength. The used computer program contains a model for the arc spot behavior under influence of outer magnetic fields. This calculations where compared with measured erosion profiles.
3:10 PM B1-3-6 Simulation of Vacuum Arc Deposition in Industrial Coaters
B. Schultrich (Fraunhofer Institute for Materials and Beam Technology, Germany); N. Rackwitz (Fraunhofer Institute for Material and Beam Technology, Germany); S. Voellmar (Fraunhofer Institute for Materials and Beam Technology, Germany)
Vacuum arc deposition is now well established for the deposition of wear protecting coatings in industry. Based on the high degree of ionization and the high kinetic energy of the film forming particles, very hard films from conventional titanium nitride up to tetrahedral bonded carbon can be produced. The resulting film structure depends (apart from particle energy) markedly on geometric factors such as angle of incidence and the relative position to the arc sources and on the surface temperature. But these parameters are continously changing due to the rotations of the parts and the more or less controlled motion of the arc spots. For support in construction and application of industrial vacuum arc coaters a simulation sofrtware package is under development. It models the film formation on real parts in real machines. The input and output routines are adapted to different levels of the personal. Its modular architecture allows the stepwise extension with additional features. In the first step the influence of geometry and kinematics has been considered. The more complex processes of plasma formation and propagation are determined by experimental investigation and represent input parameters. The program has been sucessfully applied for the depositon of tetrahedral bonded carbon films by the laser controlled pulsed vacuum arc technique (Laser-Arc). The carbon films react very sensitively on the variations of incidence direction of the impinging particles. As a result of the periodical motions nanolayered film strucutres are predicted in quantitative accordance with TEM and X-ray investigations. In the next step the energy fluxes are included for evaluation of the temporal development of the mean temperature of the parts and of the local surface temperature as well.
3:30 PM B1-3-7 Properties of Super Hard Metal Nitride Coatings Deposited by Plasma Enhanced Arc-Cathode
K. Yamamoto, T. Sato, K. Takahara, K. Hanaguri (Kobe Steel Ltd., Japan)
Super hard metal nitrides were synthesized by cathodic arc ion plating process with a new type of plasma enhanced arc evaporation source. The improvement of the new arc-cathode was so achieved by the optimization of the magnetic field geometry using computer aided magnetic field analysis that augment the spot motion on the cathode surface and ionization of the gaseous reactants in the plasma. One of the characteristics of the coatings obtained by the plasma enhanced cathode was improvement in surface roughness. In case of TiN coating, the surface roughness was drastically improved from 0.2 to below 0.1 microns of average surface roughness (Ra) by the implementation of plasma enhanced cathode. Ternary systems of metal nitride for cutting tool applications were developed for the plasma enhanced cathode and their structural and mechanical properties were investigated. These coatings were deposited from ternary alloy targets under nitrogen atmosphere (PN2=2.66 Pa) and substrate biases between -50 and -200 V were applied. The operating arc current was typically 100 A. The results on hardness measurements showed that the hardness of the new ternary coating reached approximately HV 3500, which is promising for the cutting applications, whereas hardness below HV 2500 was realized in the case of coatings deposited by the conventional arc-cathode. The surface roughness, which is one of the important issues for the cutting tool, was drastically improved when the new arc-cathode was implemented. The other properties, like thermal stability and adhesion strength will be presented. Also primary results of plasma diagnostics will be shown.
3:50 PM B1-3-8 Characterisation and Performance of Partially Filtered Arc TiAlN Coatings
A.C. Vlasveld, S.G. Harris, E.D. Doyle (Swinburne University of Technology, Australia); D.B. Lewis, W.-D. Münz (Sheffield Hallam University, United Kingdom)
The arc evaporation method used in the deposition of thin, hard coatings is a well recognized and successful deposition technique. However, it is also well documented that the arc method inherently produces copious amounts of unwanted droplets or macroparticles of the cathode material which are included into the deposited coating. This can lead to poor adhesion, low density and increased surface roughness. Also, another inherent property of arc deposited coatings is the increased residual stress that is observed. Although high residual stresses can be related to increased coating hardness, which can be beneficial in some tribological applications, such stresses can also affect the coatings adhesion to the underlying substrate. In this paper we present results obtained from an analysis of TiAlN coatings deposited using a dual source filtered arc system. This system utilizes axial filters to reduce the amount of included macroparticles. Coatings were deposited as a function of bias voltage and arc currents. Residual stresses were examined using Glancing Angle Xray Diffraction (GAXRD) and surface roughness by laser surface profilimetry and Scanning Electron Microscopy (SEM). Adhesion and friction coefficients were also determined using CSEM scratch adhesion and pin on disk testers respectively. Substrates coated included M2 tool steel, 316 stainless steel and WC coupons and the effect of substrate on residual stress was investigated. The performance of the deposited coatings was analyzed using accelerated drilling and milling tests in quenched and tempered P20 mold steel. The effect of residual stress and deposition parameters on the resulting tool life is also reported. .
4:10 PM B1-3-9 Properties of Coatings Deposited Using a Filtered Vacuum Arc Carbon Plasma Source
V.N. Zhitomirsky, O. Zarchin (Tel-Aviv University, Israel); L. Rapoport (Holon Academic Institute of Technology, Israel); R.L. Boxman, S. Goldsmith (Tel-Aviv University, Israel)

A filtered vacuum arc plasma source with an adjustable cathode-anode gap was used to produce a carbon plasma for deposition of coatings on various substrates. The deposition apparatus consisted of a plasma gun, a toroidal plasma duct, a deposition chamber, and a cooled substrate holder. The plasma gun consisted of a cylindrical graphite cathode, an annular graphite anode, and a mechanism providing axial movement of the cathode to the anode. The arc was ignited in vacuum of 3-8 mPa by momentarily contacting the cathode with the anode, while applying a d.c. current of 50-250 A between the cathode and the anode, and then withdrawing the cathode away from the anode in the axial direction, forming a cathode-anode gap of 2-18 mm. A carbon plasma jet passed through the anode into the toroidal duct and then to the substrate. A d.c. focusing magnetic field was applied in the vicinity of the cathode-anode gap, and a d.c. guiding field was generally parallel to the duct axis, while an a.c. magnetic field was applied to sweep the beam across the substrate. The substrates were stainless steel and polycarbonate coupons, and silicon wafers.

The adhesion and the structure of the coatings deposited on stainless steel substrates depended on the negative bias voltage (Vb) applied to the substrate relative to the grounded anode. With Vb=0, the coatings were not adherent, at Vb=-10 V the coatings were porous, but the pore density decreased with increasing negative Vb. At Vb=-15-30 V the adhesion of the coating was good, and dense, hard (HV~50 GPa) coatings were formed. At Vb=-15-30 V, the coating deposition rate measured for an arc current of 100 A, and an inter-electrode gap length of 12 mm was 100-250 nm/min, depending on the guiding magnetic field strength. Coatings deposited on polycarbonate surfaces were adherent without applying bias. However, the substrate surface was damaged after a deposition duration which depended on the magnetic field strengths. Coating microstructure, scratch adhesion, microhardness, electrical resistivity and transparency will be presented and discussed.

4:30 PM B1-3-10 Low Temperature Cathodic Arc Deposition
M.F. Becker, M. Arndt, T. Schuelke (Fraunhofer USA - Center for Surface and Laser Processing)

Higher substrate temperatures (>400°C ) are typically required to prepare a clean substrate surface prior to physical vapor deposition (PVD) processes, which is essential to achieve good film adhesion. Nevertheless, heating implies at least two major drawbacks: Firstly, heating of the substrates means additional processing time, which can take up to 50% of the entire coating process, subsequently resulting in higher costs. Secondly, in many cases such high temperatures limit the application of PVD processes. For example, previously heat-treated parts and components should not experience a temperature rise in a coating process exceeding the prior heat-treatment temperature to avoid critical material changes that could lead to unexpected failures. Temperature limits of 180°C are common. However, to deposit thin films at substrate temperatures below 180°C is a challenge to overcome utilizing cathodic arc physical vapor deposition (PVD). A typical process introduces heat to the substrates during several phases: infrared radiation substrate heating, in-situ glow-discharge cleaning, and the actual deposition process.

The paper analyzes each one of these steps regarding the introduced substrate heat loads and derives conclusions to obtain better temperature control by modifying parameters such as residual gas pressure, processing step time, substrate bias voltage, and arc current. The results were then applied to develop a low temperature deposition process on sample parts, achieving good film properties in terms of adhesion and wear performance.

4:50 PM B1-3-11 Deposition and Characterization of Sub-Stoichiometric Titanium Carbide Film by Filtered Cathodic Vacuum Arc Technique
X.Z. Ding (Nanyang Technological University, Singapore)
A sub-stoichiometric TiCx (x<1) thin film with a thickness of about 100 nm was deposited on Si(100) substrate by a filtered cathodic vacuum arc technique. The internal stress in the film was determined to be 7.7±0.3 GPa by the radius-of-curvature technique, and the hardness of the film was measured to be about 25.6±0.6 GPa by nanoindentation with a continuous stiffness mode. The microstructure of the film was characterized by Rutherford backscattering spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and optical microscopy and atomic force microscopy experiments. The as-deposited film was demonstrated to be composed of polycrystalline cubic TiCx crystallites with an average grain size of about 10 nm and a little amount of amorphous carbon clusters. It was shown that oxygen and/or nitrogen atoms were incorporated in the film. The film morphology was characterized by a very smooth, homogenous, and dense surface with a low microroughness of about 0.168 nm.
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