ICMCTF2004 Session EP: Symposium E Poster Session

Thursday, April 22, 2004 5:00 PM in Room San Diego

Thursday Afternoon

Time Period ThP Sessions | Topic E Sessions | Time Periods | Topics | ICMCTF2004 Schedule

EP-1 Tribological Properties of DLC Films on Polymers
T. Hashizume (Oiles Corporation, Japan); S. Miyake, S. Watanabe (Nippon Institute of Technology, Japan); M. Sato (Oiles Corporation, Japan)
Since the polymer material has the outstanding tribological characteristic, it is used in various fields such as tribo-material. However, with the constant demand for the improved performance such as hardness, heat resistance and wear resistance, development and application of the latest technology is the must. Our research is focused on studying and investigating the tribological characteristics of various DLC film coated polymer materials and their influences on the improvement of requested performance. This report deals with the deposition of DLC films on various polymer substrates in vacuum by magnetron radio frequency (RF; 13.56MHz) sputtering method with using argon plasma and graphite, titanium target. RF electric power was exerted on both substrate and target sides. The deposition parameters are basic pressure 5.0E-5Pa, working pressure 10Pa, substrate RF power 0-80W, target RF power 100-300W. Polyamide(PA), polyethylene(PE), polyoxymethylene(POM), polyimide(PI), polyphenylenesulfide(PPS), liquid crystal polymer(LCP) were used as substrate. The properties of friction and wear are measured using a ball-on-disk wear-testing machine. From the measurements of friction coefficient and the amount of wear by observing the sliding motion and visually inspecting wear traces, the results as following are clarified. The mechanical properties of DLC films were evaluated by nanoindentation. The properties of friction and wear have been remarkably improved by DLC coating. Moreover the composition of DLC films has been analyzed by using auger electron spectroscopy(AES). The wear rate of titanium-containing DLC film is lower than that of no-metal-containing DLC film. The above-mentioned advanced properties have been obtained because adhesive work between substrate and DLC films has been increased though reducing internal-stress. And internal-stress decrease with increasing the amount of titanium-containing.
EP-2 Deposition and Tribology of Carbon Nitride Thin Films
S. Watanabe, S. Miyake, M. Murakawa (Nippon Institute of Technology, Japan)
Recently, it has been reported that carbon nitride film has showed a unique property, such as a high elastic recovery compared with DLC film, even if a structure of this film was amorphous. In this study, carbon nitride films have been deposited by means of the magnetically enhanced plasma ion-plating equipment. The following two methods of the deposition were investigated. One is the reactive ion-plating which is a reactive evaporation between carbon vapor and nitrogen plasma. The second is a method of an ionized evaporation caused by mixed gas plasma using hydrocarbon and nitrogen gases. Wear performance and deformation energy evaluation of the films were examined by the micro-wear and nano-indentation tests using AFM device having a peculiar transformer head added to the measuring units. Moreover, crystal structure and chemical composition of the film have been analyzed using FT-IR and XPS, respectively. The film formed with the ionized evaporation using C2H2-Ar-N2 gas plasma showed that the hardness becomes harder than that of the film formed with the reactive ion-plating, due to the confirmation of C-N bonding structure from the result of FT-IR and XPS. When the film is formed with CH4-N2 gas plasma, it has been observed that no micro-wear of the film was occurred, resulting in showing good wear resistance. This is understood that the film shows large elastic recovery from the result of the deformation energy evaluation.
EP-3 DLC Anti-cold Welding Lubricat Film on Ti6Al4 Alloy for Spatial Applications
L.V. Santos (INPE/MCT-Instituto Nacional de Pesquisas Espaciais and ITA/CTA - Instituto Tecnolagoico de Aeronautica, Brazil); V.J. Trava-Airoldi, E.J. Corat, N.F. Leite (INPE/MCT-Instituto Nacional de Pesquisas Espaciais, Brazil); J. Nogqueira (Fibraforte Engenharia Ind e Com Ltda, Brazil)
In this work the DLC film is used as a protective coating on roughened Ti6Al4V surface device. High roughness Ti6Al4V surface is necessary for mechanical engagement of movable parts in satellite systems. DLC film will play the role of anti-cold welding protective coating if this rough surface is under great effort in high vacuum environment. This kind of application require very high adherence between the substrate and DLC film. The DLC depositions were performed either on smooth or on laser textured Ti6Al4V surfaces. Smooth surfaces have been used to measure friction coefficient in nanometric scale and the textured surfaces have been used to test mechanical engagement without cold welding in vacuum environment. A very thin silicon interlayer was used to improve the DLC adherence to the Ti6Al4V substrates. Both Silicon and DLC films were prepared by RF magnetron sputtering with argon as the buffer gas and with an additional DC bias. The quality characterization of the DLC films and silicon interlayer have been performed by Raman scattering spectroscopy, the morphology and roughness has been evaluated by SEM and AFM; the LFM has been used to measure the friction coefficient in nanoscale and, micro indentation technique has been used for evaluating the film hardness. Also, results on anti-cold welding tests of textured DLC surfaces on high vacuum environment will be discussed.
EP-4 Structure and High Temperature Tribological Behaviour of Ti-Si-C Nanocomposite Thin Film Coatings
W. Gulbinski, T. Suszko, A. Gilewicz, B. Warcholi@aa n@ski, Z Kuklinski (Technical University of Koszalin, Poland)
Multiphase, thin Ti-Si-C films have been deposited from elemental targets by pulsed, double source, reactive magnetron sputtering in argon-acetylene atmosphere on steel and alumina substrates. Optical emission plasma spectroscopy was used to control deposition conditions. The composition of coatings was determined by Electron Microprobe in Wave Dispersive Spectroscopy (WDS) mode, based on reference samples analysed by Rutherford Backscattering Spectroscopy (RBS). XRD analysis, revealed the coexistence of TiC, Ti5Si3Cx, TiSi2 and SiC phases, dependent on nominal composition of the coating. The presence of lamellar Ti3SiC2 phase can not be excluded in samples deposited at 700°C where grain size reached micrometer range. Low temperature (<300°C) deposits transform from nanocrystalline to amorphous with an increasing silicon content. Microhardnes and adhesion of 2 µm thick deposits on 440C steel substrates have been tested by means of Vickers indentation and scratch-test, respectively. Tribological behaviour during dry friction in air of normal humidity was studied in the wide temperature range (20 to 600°C) using ball-on-disc configuration. Results are discussed in terms of chemical and phase composition of studied films.
EP-5 Tribological Behavior of Multilayered WC-Ti1-xAlxN Coatings Deposited by Cathodic Arc Deposition Method on AISI D2 Steel
S.H. Ahn, H.G. Kim, J.H. Lee, J.G. Kim, C.W. Cho, Y.Z. Lee (SungKyunKwan University, South Korea)
Recently, many of the current development in surface modification engineering are focused on multilayered coatings. Multilayered coatings have the potential to improve the tribological properties. Four different multiplayer coatings were deposited on AISI D2 steel. The prepared samples are designed as WC-Ti0.6Al0.4N, WC-Ti0.53Al0.47N, WC-Ti0.5Al0.5N and WC-Ti0.43Al0.57N. The multilayer coatings were investigated with respect to coating surface and cross-section morphology, roughness, adhesion, hardness, porosity and tribological behavior. Especially, wear tests of four multiplayer coatings were performed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/s, 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball (HR = 66) having a diameter of 11 mm. The surface morphology and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Also, wear mechanism was determined by using SEM coupled with EDS. Results have showed an improved wear resistance of the WC-Ti1-xAlxN coatings with increasing of Al concentration. Especially, the best resistance of WC-Ti0.43Al0.57N to wear is due to its low surface roughness, adhesion and a low porosity.
EP-6 Friction Properties of WS2/MoS2 Multilayer Films under Vacuum Environment
J. Noshiro, S. Miyake, S. Watanabe (Nippon Institute of Technology, Japan)
We fabricated WS2/MoS2 nanometer-scale multilayer films (superlattice structured multilayer film) having dry lubricating characteristics using multi-targets RF sputtering. Superlattice structures are obtained by layering two or more materials in a regular periodic structure at a thickness of several or several tens of atoms. This results in a rapid increase in internal energy, with elastic modulus, hardness and other mechanical properties changing to produce performance and characteristics improved compared to those of the individual single-layer materials. In the previous ICMCTF2003, we demonstrated this WS2/MoS2 multilayer film showed significantly improved tribological performance in ambient air compared to the single-layer MoS2 or WS2 films. In order to clarify the tribological properties of this multilayer further, sliding friction experiments have been conducted with WS2/ MoS2 films formed on silicon substrates in contact with 440°C stainless-steel balls under vacuum at room temperature and at a high temperature of 523 K. The obtained results showed it was clear that friction characteristics and friction endurance of this multilayer films were more excellent under a vacuum of 10-5 Pa order than those under atmospheric conditions.
EP-7 A Topographic Analysis of the Crater Wear in Coated Cemented Carbide Tools: Plastic Deformation by a Shear Mechanism
C. Godoy, R.F. Avila, A.M. Abrão (Universidade Federal de Minas Gerais, Brazil); J.C. Avelar-Batista (Tecvac Ltd. Buckingway Business Park, Brazil)
The occurrence of plastic deformation in the crater wear by a shear mechanism on the rake face of tungsten carbide-cobalt tools does not appear to have been reported yet. In this present investigation, three-dimensional profilometry was used to monitor the crater wear on tungsten carbide-cobalt-coated cutting tools. (Ti,Al)N, Ti(C,N) and TiN coatings were deposited by PAPVD. Three-dimensional evaluation of the crater wear was performed as a function of cutting time. Nanoindentation results revealed that the (Ti,Al)N coating had the highest hardness, followed by Ti(C,N), TiN and WC-Co substrate. Topographic images obtained by 3D-profilometry clearly indicated two adjacent regions to the crater wear having high amplitude. The removal of material from the crater wear could be attributed to a plastic deformation mechanism promoted by shear. The cumulative volume of material displaced into these adjacent regions was assessed using the Mountains software. The results indicated that the uncoated tool showed the largest crater wear volume, which could be directly related to a larger volume of sheared material displaced to the crater edges. The best performance was achieved by the Ti(C,N)-coated tool, followed by the TiN-coated one, whilst the worst performance was exhibited by the (Ti,Al)N-coated tool. It was concluded that an abrasive wear mechanism was the major mechanism operating in Ti(C, N) and TiN-coated tools. In this situation, high hardness and H/E values ensured a high resistance to abrasive wear, since plastic deformation was the dominant wear mechanism. However, the (Ti,Al)N coating, having the highest hardness, exhibited the largest volume of removed material. For this coated tool, a wear mechanism by brittle fracture probably occurred. The (Ti,Al)N coating displayed a fcc crystalline phase and a AlN phase. This non-homogeneous phase structure seemed to promote a reduction in the coating toughness and make it prone to wear by a brittle fracture mechanism.
EP-8 High Temperature Tribological Characterization of Commercial TiAlN and WC-C Based Coatings
M. D'Alessandria (Central University of Venezuela); A. Roman (Université de Franche-Comté, France); D.T. Quinto (Balzers Inc.); M.H. Staia (Universidad Central de Venezuela)
This study was conducted to determine the tribological behavior at high temperature of 4 hard coating types commercially deposited (by Balzers Inc.) on WC inserts. The TiAlN-based coatings contained varying Ti/Al atomic ratios of 7/3 to 2/3. The nano-layered TiAlN, multi-layered TiAlN/TiN, and double layered TiAlN/WC-C coatings were deposited by the PVD cathodic arc process, or combined with a magnetron sputtered source for the latter coating. The coatings were subsequently characterized from mechanical and microstructural points of view. Composite Vickers microhardness values for each coating/substrate system are also reported. Single pass scratch tests were used to characterize adhesion and ball-on-disc testing was employed to determine friction coefficients and wear rates, respectively. The tribological tests were carried out at 25, 500 and 700°C against a 6 mm alumina ball with 5N normal load. It was determined that the TiAlN/WC-C coating presented the smallest friction coefficient of 0.22 at 25°C and a wear resistance which was 14 times higher than the other coatings. With the increase in the test temperature the wear resistance of this coating decreased achieving a decrease of nearly 50% at 700°C. However, for all the TiAlN based coatings as the test temperature increased to 500°C, the wear volume was similar for all coatings and nearly one order of magnitude smaller than the values determined at room temperature. At the test temperature of 700°C, the wear volumes reported are similar to those found at room temperature. Ranking of the coatings is presented for each temperature and the wear mechanism is discussed as function of the morphological characteristics determined by SEM and EDX analysis.
EP-9 Adhesion of Unbalanced Magnetron Sputtering Ion Plating TiNx on 7075-T6 Aluminum Alloy
M.H. Staia, R. Prieto, Y. Santana, Z. Marcano (Universidad Central de Venezuela)
Aluminum alloys series 7XXX are widely used for miscellaneous structural applications as well as in the aircraft industry, due to their good combination of mechanical properties and low density at temperature up to 1500°C. However, their poor tribological properties, have limited their use in highly loaded application involving sliding or rolling contacts. In the last decade, the deposition technologies have been modified for temperature-sensitive materials in order to produce denser coatings and to improve their wear resistance, without impairment of their mechanical properties. The aim of this paper is to characterize the TiNX on 7075-T6 aluminum alloy coated industrially (Teer Coatings Ltd.) by using the closed field unbalanced magnetron sputtering ion plating (CFUBMSIP) deposition technique. Coating characteristics such as morphology, thickness, compositional variation with thickness, residuals stress, composite microhardness and absolute hardness are also presented. Conventional scratching test was conducted by using the scratch tester (Revetest, CSEM). The adhesion results were correlated with the Hertzian stress distribution of the coating-substrate system, calculated using ELASTICA, a commercial software package. The results are indicated that the scratch adhesion test it is not adequate to evaluate the adhesion of a thin hard coating on a soft substrate.
EP-10 Design and Evaluation of a Rolling Contact Fatigue Test Machine for Ball Bearing Components with Nanostructured Coatings
Y. Yang (Yanshan University, PR China); A. Matthews (University of Sheffield, United Kingdom)
The paper reviews and discusses the current evaluation techniques for the rolling contact fatigue behaviour of coated components. A model of the mechanism of rolling contact fatigue is presented. A new test machine for rolling contact fatigue for coated ball bearing components has been designed and developed. Evaluation experiments on the rolling contact fatigue performance of nanostructured coatings on bearing raceways, applying the new test machine, have been performed. These experiments confirm the suitability of the machine to evaluate the rolling contact fatigue resistance of coated raceways. The measurement system of the test machine can detect and diagnose the initial fatigue cracks of the raceways with nanostructured coatings applied. The control and transmission system of the fatigue test machine can quickly stop its operation, to maintain the initial state of the fatigue cracks, and thereby provide a revealing insight into coating behaviour under rolling contact conditions. The initial fatigue cracks occur near the surface of the substrate below the coating. Then the initial fatigue crack spreads to the surface through the coating layer, and intermeshing cracks appear on the surface of the coated raceway.
EP-11 Tribological Properties of AlN Protective Layer for Automotive Aluminum Alloy Parts
P.V. Visuttipitukul, T. Aizawa (University of Tokyo, Japan); H. Kuwahara (Research Institute for Advanced Sciences, Japan)
Aiming at the practical protective layer of automotive aluminum alloy parts, new plasma nitriding method has been developed. Aluminum nitride or AlN is one of the most promising coating layers to protect the aluminum alloys from severe wear and friction. Using the precipitate-accommodated inner plasma nitriding, AlN-layered specimens were fabricated for systematic evaluation on their tribological data. The pin-on-disc method was employed to investigate the wearing mode and friction coefficient under dry condition. Three specimens were prepared for comparison: Al-Si alloy with A356), Al-6Cu alloy without AlN layers and AlN-layered Al-6Cu alloy (A356) was also utilized as a counter material. The normal load is constant, 20 N with the threading velocity of 0. 25 m/s. Without AlN layers, Al-6Cu alloy suffers from high adhesive wearing with the friction coefficient of 0.44. In case of the wear test between A356 alloys, the wearing takes place with the mixed mode of abrasive and adhesive wears. The friction coefficient is still high, 0.33. While, in the case of AlN-layered Al-6Cu alloy specimen, the wear mode becomes abrasive and the friction coefficient is lowered to be 0.29. This reveals that AlN layer formation is effective to reduce the wear volume and friction coefficient for automotive aluminum alloy parts.
EP-12 Surface Morphology and Hardness of Titanium Aluminum Nitride Coating on Tungsten Carbide Substrate
P.J. Peng, S.K. Tien, F.B. Wu, G.T. Liu (National Tsing Hua University, Taiwan, R.O.C.); Y.I. Chen (E-Pin Optical Industry Co., Ltd., Taiwan, R.O.C.); J.G. Duh (National Tsing Hua University, Taiwan, R.O.C.)
Titanium aluminum nitride (TiAlN) coating was deposited onto the novel tungsten carbide (WC) molding substrate to modify the surface properties. The TiAlN coating was fabricated by reactively RF magnetron sputtering technique with a thickness in submicron range. To simulate the hot pressing molding environment, the thermal cycling test from room temperature upto 550°C within a nitrogen purged chamber was performed on the TiAlN coating assembly. The influence on surface roughness and morphology of the coating assembly was discussed in terms of the thermal cycling process. Mechanical properties, including surface hardness, Young's modulus, and indentation behavior, were investigated by continuous stiffness measurement (CSM). Intensive study on adhesion strength and scratch behavior of the TiAlN was also conducted and discussed.
EP-13 Effects of Co, Co/Ti, Ti Interlayers and Post Anealing on the Adhesion Property Between TiN Coatings and WC-Co Substrate
S.Y. Yoon, D.K. Lee (Pusan National University, South Korea)
In order to improve the adhesion between TiN coatings and WC-Co substrate, three kinds of interlayers of Co, Ti, Co/Ti were pre-deposited before starting TiN coating process. Thickness and post-annealing effects of each interlayer on the adhesion property were investigated in this work. WC-Co substrate with WC particle size of 1µm and Co content of 10 wt.% was polished to have the average surface roughness of 7 nm. Each interlayer was deposited onto WC-Co substrate with variety of thickness and followed by TiN coatings. The post annealing of samples were carried out in temperature range from from 100°C to 600°C. Adhesion strength and failure behavior of the samples were studied using a conventional scratch test. The adhesion properties of TiN coatings were influenced on thickness of Ti and Co/Ti interlayer, particularly the minute change of thickness of Co interlayer resulted in remarkable change of adhesion properties. Moreover, with increase of annealing temperature up to 200°C, the adhesion properties were largely improved.
EP-14 High Performance Chromium Aluminum Nitride PVD-coatings on Roller Bearings
P.W. Gold, M. Kuhn, E. Lugscheider, K. Bobzin, M. Maes (RWTH-Aachen, Germany)
Cylindrical roller thrust bearings belong to the most highly stressed tribological systems used nowadays. Mixed lubrication, high loads (80kN) and low revolutions (7min-1) often lead to extensive wear on uncoated bearings, which was the motivation for applying wear resistant PVD coatings. The challenge in coating development is given by the annealing temperature of the machine part. Low deposition temperatures are needed to avoid annealing as well as distortion of the machine part. Pulsed magnetron deposition can lower the deposition temperature substantially, without harming the adhesion or structure of the coatings. In this paper differences in wear behavior were investigated by varying the location of the chromium aluminum nitride PVD coating within the bearings' components. Differences in friction and wear behavior were investigated in dependence of coating design as well as deposition temperature. The outcome of the results was then compared to pin on disc tests.
EP-15 Nanoindentation Analysis of the Influence of Coating Morphology on the Measured Mechanical Properties of Nitride Coatings
A. Toppo, B. Burdet, M. Jobin, E. Bergmann (Geneva School of Engineering, Switzerland); M. Morstein, T. Cselle (Platit AG, Switzerland); A. Schuetze, V.H. Derflinger (Balzers AG, Liechtenstein)
Low load nanoindentation with topography selection was used to analyse the mechanical properties of ion plated hard coatings and their constituents. Load/depth analysis was carried out on selected features of the coating surface like dimples, ridges and and pins. The observed mechanical properties reflect the elastic and plastic deformation and cracking of the features. The analysis was repeated in cross sections, which were ion etched to reveal the columnar or multilayer structure.Indentations of different loads were performed in column centres , between columns and at the interface of multilayers. Plastic deformation and cracking was observed in the load curves and in the AFM pictures of the indents. The results indicate, that the fine columns of these coatings can easily be broken leading to low appearent hardness measurements.
EP-16 Nano Mechanical Properties Evaluation of Chromium Nitride Films by Nanoindentation and Nano Wear Techniques
J.W. Lee (Tung Nan Institute of Technology, Taiwan); J.G. Duh (National Tsing Hua University, Taiwan, R.O.C.); Y.C. Chen (Tung Nan Institute of Technology)
Nano mechanical properties studies are needed to develop fundamental understanding of surface and interfacial phenomena on a small scale, such as the micro/nanostructures used in micro-electromechanical systems (MEMS), nano-electromechanical systems (NEMS) and other industrial applications. Nanoindentation and nano wear methods were employed to characterize nano mechanical properties of reactive R. F. magnetron sputtered and cathodic arc plasma deposited chromium nitride films. The surface morphologies and surface roughness of CrN films on nano scale were explored with an atomic force microscope. The nano hardness and elastic modulus of two CrN films were evaluated by nanoindenter. Coefficients of friction of two CrN films were also calculated based on the nano scratch tests. Reciprocating wear tests under 300, 400 and 500 µN loads on two CrN films were conducted with nanoindenter. The residual wear depths of CrN films were examined by atomic force microscope. It's found that CrN films exhibited similar nano hardness and elastic modulus. The residual wear depths of CrN films after reciprocating wear tests ranged from 4 to 7 nm. The cathodic arc plasma deposited CrN film provided more wear resistance than the other. Nevertheless, both CrN thin films demonstrated rather promising tribological application potential in MEMS and NEMS.
EP-17 Wear Behavior of Pulsed Plasma Ion Nitrided 304 AISI Stainless Steel Containing the S-Phase
L. Agudo, C. Sanchez (Universidad Central de Venezuela); J.N. Feugeas, L. Nosei, M. Avalos (Instituto de Física de Rosario (IFIR), Argentina); M.H. Staia (Universidad Central de Venezuela)
304 stainless steel samples were ion nitrided for 30 and 40 minutes respectively, at 400°C in a reactor using pulsed glow discharge operated at 400V and at a frequency of 100Hz, in a gas mixture composed of 80% nitrogen and 20% hydrogen. The 30 minutes nitriding time formed at the steel surface an expanded austenite phase (S-phase), in which Cr, Fe and N are bonded in a quasi-crystalline structure with Ni participation in a metallic state. Higher nitriding time produced, besides the S phase, enrichment in Cr of the near surface region with the presence of small amounts of CrN and of Fe4N, which are characteristic of the formation of an incipient white layer. A nitriding depth of 24 microns approximately was determined by using scanning electron microscopy technique (SEM), and this measurement was corroborated when determining the Knoop microhardness profiles. The nitriding depth was the same for all samples irrespective to the processing time. A microhardness of 1500 HK 0.025 for the S-phase was obtained. The tribological behavior was assessed by conducting sliding experiments at room temperature, when using a tribometer under the ball- on- disc configuration. Balls of alumina of 6mm diameter were employed as counterpart, and the tests were performed at a sliding velocity of 0.1m.s-1 and a normal load of 5N. An average friction coefficient around 0.7 was found for the nitrided samples/alumina ball pairs, where an abrasive wear mechanism was identified in all cases. The wear volumes calculations indicated that the highest improvement in the wear resistance was found for the samples treated for 40 minutes, where an increase of nearly 4600% was achieved when compared to the untreated steel. The results were explained through the microstructural characteristics of the samples produced during the ion nitriding process.
EP-18 The Properties and Performance of Cr Based Multilayer Nitride Hard Coatings using Unbalanced Magnetron Sputtering and Element Metal Targets
S. Yang (Teer Coatings Ltd., United Kingdom); E. Wiemann (Technical University Berlin, Germany); D.G. Teer (Teer Coatings Ltd., United Kingdom)
Cr based multilayer hard coatings were produced by unbalanced magnetron sputtering techniques using elemental metal materials. Cr, Ti, Mo, V and Al targets were used for the metal sources whilst nitrogen was introduced at the same time to produce multilayer nitride hard coatings. The deposition process was controlled using a metal plasma optical monitor with closed loop feedback to piezoelectric valve to form stoichiometric coatings. Physical properties of the coatings were investigated using microhardness, scratch, and Rockwell indentation measurements. Wear properties of the coatings were studied using pin-on-disc tests. The coatings were also deposited onto hard metal carbide cutting inserts. The practical cutting performance was tested on a range of difficult to machine materials using a CNC-lathe VDF180-C machine. The cutting was carried out by continuous turning as well as interrupt cutting and the results were compared with those obtained using an advanced commercially available TiAlN coating.
EP-19 High Aluminum Content AlCrN-coatings in Modern Machining Applications
V.H. Derflinger, C. Gey (Balzers AG, Liechtenstein); A. Reiter (Balzers Ltd., Liechtenstein); M. Gabathuler, D. De Gregorio, W. Kalss (Balzers AG, Liechtenstein)
Today, modern wear resistant PVD hard coatings are used for machining applications in a very broad range. Due to their properties mainly Ti- and TiAl-based nitrides and carbonitrides are used. These coatings are favorable because of their high hardness and good resistance against wear and oxidation. But these type of coatings are limited to application temperatures of 900°C. At higher temperatures the coatings start to dissolve and form porous titanium oxides or aluminum oxides at the surface. By changing the ternary system from Ti-Al-N to Cr-Al-N interesting effects with respect to wear and oxidation resistance were observed. In this paper the properties of AlCrN coatings will be compared to state of the art TiAlN coatings. The coatings under investigation had a cubic structure with a high aluminum content. Beside mechanical, physical and thermal properties also results of metalcutting tests will be discussed.
EP-20 AFM Analysis of Wear Marks of Coated Inserts
M. Jobin, A. Toppo, E. Bergmann (Geneva School of Engineering, Switzerland); A. Santana (Federal Institute of Technology, Switzerland); A. Schuetze, V.H. Derflinger (Balzers AG, Liechtenstein)
The wear marks on the rake face of coated milling inserts, that had undergone standard cutting tests were cleaned to remove any built up material. The worn coating surfaces were then analysed by AFM. The results show, that under the chosen test conditions the wear mode is dominated by the morphological structure. In particular any columnar structure of the coating is prone to intercolumnar cracks, that show up very clearly in the AFM.
EP-21 Tribological Properties of Novel High-performance PVD Coatings
O. Coddet, M. Morstein, T. Cselle (Platit AG, Switzerland); B. Torp (Platit Scandinavia, Denmark); P. Holubar, M. Jilek (PIVOT, Czech Republic); J. Antifakos (ETH Zürich, Switzerland)

A large fraction of tools and a steadily increasing number of tribological components are currently coated by various methods. The main optimization focus in high-performance metal cutting applications has so far been on coating hardness and toughness. But just as well, the friction between workpiece and coated tool needs to be controlled to further minimize adhesive and chemical tool wear.

Ceramic-ceramic nanocomposites have recently been introduced to the industrial coating market by the Platit LARCR PVD technology. The nACoR two-phase materials consist of embedded Al1-xTixN nanocrystalline grains in a thin, amorphous matrix of a second material, Si3N4, in which they are insoluble. This concept provides excellent wear resistance, even under conditions of extreme usage.

As little is known about the frictional properties of this and other more recent coating types, the tribological behavior of the coatings nc-Al1-xTixN/a-Si3N4, nanolayered TiAlN and AlTiN, TiN, and CBC (carbon-based coating) was compared. Pin-on-disc tests in dry atmosphere were used to explore the frictional characteristics of these materials against different technically important alloy pins. The resulting wear tracks were analyzed by electron microscopy and surface analytical methods in order to obtain information on the wear mechanisms. Results will be presented on the structure and properties of these coatings and their application in high-performance machining.

EP-22 Tribological Performance of 7075-T6 Aluminum Alloy Coated with Electroless Ni-P
K.L. Silva, Y. Santana (Universidad Central de Venezuela); J. Lesage, D. Chicot (URA CNRS, France); G. Mesmacque (IUT A, France); M.H. Staia (Universidad Central de Venezuela)
To improve the superficial properties of the aluminum alloys they can be covered with a wear resistance protective layer. The electroless Ni-P coating could be an excellent candidate, since presents good corrosion and wear resistance as well as uniform coating thickness. In the present work, the dry sliding wear behavior of samples of 7075-T6 aluminum alloy coated with high phosphorus electroless nickel was studied. The amorphous coatings were deposited industrially (Reliable Plating Inc., USA). The as-deposited coatings characteristics such as morphology, thickness, the compositional variation of the elements with thickness as well as their structure and microhardness were evaluated. The effects of the as-deposited electroless Ni-P coatings on the tribological properties of the substrate were investigated using a ball-on-disc tribometer and AISI 52100 balls (6mm diameter) were used as counterpart. Sliding velocities of 0.15, 0.10 and 0.05 m/s and two normal loads (5 and 10 N) were employed. For comparison, the wear behavior of the uncoated alloy was also reported. The results showed that the tribological performance of 7075-T6 aluminum alloy was improved when coated with the electroless Ni-P alloy. It was found, for the most severe condition of wear studied (10 N, 0.05 m/s), that the uncoated aluminum alloy achieved a wear constant value of nearly 48% higher when compared to the wear constant value for the as-deposited coating.
EP-23 Influence of the Deposition Parameters on the Tribological Performance of ZrN Magnetron Sputtered Coatings
M. D'Alessandria, M.R. Cruz (Central University of Venezuela); A. Roman, D. Pilloud, J.F. Pierson (Université de Franche-Comté, France); J. Lesage, D. Chicot (URA CNRS, France); M.H. Staia (Universidad Central de Venezuela)
The effect of the substrate bias voltage on the wear behavior of ZrN coatings was studied in the present work. The coatings were deposited on AISI H 13 steel by magnetron sputtering of a zirconium target in reactive Ar-N2 mixture. The bias potential was varied between 0-180 V. After deposition, the coatings were characterized using X-ray diffraction techniques, nanoindentation, Vickers microhardness, adhesion tests and SEM/EDS analysis. The study of wear behavior was determined by ball- on-disc wear test at a sliding distance of 0.1 m s-1, normal load of 5 N and sliding distance of 1000 m. The tests were carried out in air and without lubrication. It was shown that an increase in the value of the bias voltage produced an increase in the coating thickness. The friction coefficient varied according to the wear mechanism present in the tribocontact. The values of friction coefficients for the samples that presented an adhesive wear type mechanism oscillated between 0.44-0.58 meanwhile for the other samples, which presented an abrasive type of wear, the friction coefficient reached higher values which varied between 0.77-0.87. The later response was associated to a higher worn volume, which increased with the increase in the substrate bias voltage. All the coating/substrate systems presented wear coefficients values that were higher than those corresponding to the uncoated substrate against sapphire ball under the same testing conditions. The wear performance of coatings was discussed on the basis of the results obtained from the coating microstructural and mechanical characterization.
EP-24 Fatigue Properties of an AA6063-T6 Aluminum Alloy Coated with an Electroless Ni-P Deposit
A. Piñeiro, C.J. Villalobos-Gutiérrez (Universidad Central de Venezuela); G. Mesmacque (IUT A, France); E.S. Puchi-Cabrera (Universidad Central de Venezuela)
The present investigation has been conducted in order to study the fatigue behavior of an AA6063-T6 aluminum alloy both in air and in a NaCl solution, and to compare such a behavior with that shown by the same alloy when this has been coated with an autocatalytic electroless Ni-P deposit of approximately 40 µm in thickness and a high phosphorous content. The coated specimens were tested with the coating in the as-deposited condition, that is to say, without any additional post heat treatment. The static mechanical properties of the uncoated and coated substrate were evaluated by means of tensile tests. Such evaluation indicated that the presence of the coating gives rise to a slight increase in both the yield and tensile strength of the material. The fatigue tests were conducted under rotating bending conditions at maximum alternating stresses that were calculated as a function of the yield strength of the substrate-coating system, and were in the range of 96-172 MPa. It has been determined that the application of this coating to the aluminum substrate gives rise to a decrease in the fatigue and corrosion-fatigue performance. When the tests were conducted in air, at maximum alternating stresses of the order of 96 MPa, the decrease in fatigue life was about 54%, whereas in the NaCl solution it was of approximately 34%. At maximum alternating stresses of 172 MPa, in air the reduction in fatigue life was of about 71% and in NaCl it achieved nearly 65%. SEM observations were conducted on both fracture surfaces and sections normal to such surfaces of selected specimens in order to analyze the fatigue fracture process and the role of the coating in the decrease of fatigue life of the coated specimens.
EP-25 Durability and Friction Characterization of Thin Coatings
N.V. Gitis, M. Vinogradov, J. Xiao (Center for Tribology, Inc.)
Durability of coatings from 1 nm to 0.1 mm was successfully evaluated for such criteria as scratch-resistance, adhesion and delamination, multi-cycle abrasive and adhesive wear. The highly reproducible and repeatable results were obtained by simultaneous monitoring of normal load and friction force, as well as high-frequency contact acoustic emission and electrical contact resistance. Interesting differences were observed and explained at different test temperatures, from 20C to 800C. Stable frictional characteristics of thin coatings were obtained at very low loads and found to be very sensitive to contamination and environmental conditions.
EP-26 Post Oxidizing Treatments of the Compound Layer on the SCM 435 Steel Produced by Plasma Nitrocarburizing
I. Lee (Dongeui University, South Korea)
Plasma nitrocarburizing and post oxidation were performed on SCM 435 steel by a pulsed plasma ion nitriding system. Plasma oxidation resulted in the formation of a very thin 1-2 mm ferritic oxide layer on top of a 15-25 mm Fe2-3(N,C) nitrocarburized layer. The growth rate of oxide layer increased with the treatment temperature and time. However, the oxide layer was easily split from the compound layer either for oxidation temperatures above 450°C, or for oxidation time more than 2 hours at oxidation temperature of 400°C. It was confirmed that the relative amount of Fe2O3, compared with Fe3O4, increased rapidly with the oxidation temperature. The amounts of Fe4(N,C) and Fe3C, generated from dissociation of Fe2-3(N,C) phase during O2 plasma sputtering, were also increased with the oxidation temperature.
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