ICMCTF1998 Session EP: E - Posters

Wednesday, April 29, 1998 5:00 PM in Room Atlas Foyer
Wednesday Posters

Time Period WeP Sessions | Topic E Sessions | Time Periods | Topics | ICMCTF1998 Schedule

EP-1 Friction Characteristics of Al-Si-O Ceramic Coatings Produced by Micro-arc Discharge Oxidising of Aluminium Alloys
A.L. Yerokhin (Tula State University, Russia); A. Matthews (University of Hull, United Kingdom); J.M. Schneider (Linköping University, Sweden); W. Lyubimov (Tula State University, Russia)

Oxide ceramic coatings produced by micro-arc discharge treatment can provide a considerable increase in the wear life of components made from aluminium alloys 1. To use these coatings in tribological applications, it is necessary to understand their friction behaviour in contact with different materials under a wide range of loading conditions. In this paper the friction characteristics of Al-Si-O coatings formed on A16.3Cu and A14.3Cu1.5Mg0.6Mn substrates are studied under continuous and reciprocating sliding contacts against steel and WC balls. The tests are performed under ambient atmosphere conditions with the loading varied from 0.2 to 20 N. Relations between the friction behaviour and mechanical properties, structure and phase composition of the coatings are discussed to explain the results obtained.

It is found that at least two factors (the relationship between the ball and coating mechanical properties and their ability for adhesive interaction) are responsible for the tribological behaviour of the friction pair. A minimum friction coefficient is reached when the hardness of the coating Al2O3 matrix corresponds to the hardness of the ball material. The friction coefficients here are caused by the adhesive interaction and amount to 0.10-0.16 and 0.20-0.28 sliding against WC and steel respectively. For the softer coatings the friction coefficient rises to 0.8-1.0 with increases in the loading, and for the harder ones it rises to 0.5-0.7 independently of the loading. Both the raising of the abrasive component of the wear and changing of the contact area due to substrate strain are discussed as possible reasons for the friction variation.

1 A A Voevodin, A L Yerokhin, V V Lyubimov, M S Donley and J S Zabinski, Surface and Coatings Technology, 86-87 (1996) 516-520.

EP-2 Laser Cladding and Alloying for Improving Tribological Properties of Machine Parts
M. Riabkina-Fishman, J. Zahavi (Israel Institute of Metals, Technion, Israel)
A technique for improving tribological properties of machine parts by surface laser alloying or laser cladding has been developed. The technique is especially suitable for refurbishing worn machine parts because it allows not only to replace the worn material but to obtain surface having better characteristics than the original part. Infrared continuous CO2 laser with a maximum power 8kW and direct powder injection method have been used; the treatment was performed on SAE steel 4340 using cobalt-base Stellite powder for either alloying or cladding. Coating as thick as 5 mm were obtained with uniform cobalt content within the coating; iron content was as low as one per cent. A very good bonding between the coating and the substrate was achieved because a melting of a thin surface layer at the substrate surface takes place at the initial stage of laser treatment.
EP-3 Atomic Oxygen Resistant Inorganic Materials for LEO Applications
E. Poiré (Canadian Space Agency, Canada); B.G. Sellars (ORTECH Corporation, Canada); D. Nguyen (Datco Technology Limited, Canada)

Conventional dimethylsiloxane polymers (silicones) have a high erosion rate in atomic oxygen which make them unsuitable for long term exposure in the Low Earth Orbit (LEO) environment. Advanced silicon-oxygen backbone polymers can exhibit much lower atomic oxygen with vacuum ultraviolet (AO/VUV) erosion rates. However, there is currently a lack of space-qualified polymer coating systems available that can withstand the requirements of 30-35 years exposure in LEO. There is a need for flexible coatings stable in the LEO environment.

This presentation describes the performance of proprietary non-dimethylsiloxane inorganic polymers as a coating system resistant to AO/VUV. These coatings may be suitable for the protection of organic materials and composites in LEO. The inorganic polymer is soluble in common organic solvents and can be applied onto a variety of substrates by inexpensive spinning, spraying, or dip coating techniques. Kapton was the primary substrate used in this program, although other materials such as graphite epoxy composite can also be coated.

Performance data of the proprietary coating will be presented including the erosion rate in terrestrial AO/VUV tests, coating adhesion before and after thermal cycling and surface morphology by SEM before and after AO/VUV exposure. The potential application of this coating as an AO/VUV resistant varnish as well as a binder for flexible thermal control paints will be discussed.

EP-4 Influence of Epitaxy and Ordering on the Mechanical Behaviour of an Oxide Layer on a Metallic Substrate
N. Vallino (University of Technology of Compiegne, France); L. Lahoche, V.L. Lorman (University of Picardie Jules Verne, France); S.B. Rochal, J.M. Roeland (University of Technology of Compiegne, France)

In order to prevent the damage or the spallation of an oxide thin film during an oxidation process, it is important to delineate the effects of the different origins of stresses1 which usually take place at the metal/oxide interface undergoing transformation. We have developped a general model which allows us to study the influence of the metallic ion ordering in a three-dimensional interface, which is strongly related to the epitaxial relationship. We have shown that a phase transition can lead to a mechanism of low-temperature relaxation of microstresses due to modification of the interface. The model is applied to the case of both simple and more complex epitaxial systems such as (001)Fe//(001)FeO, (001)Ni//(001)NiO and (111)Ni//(001)NiO. The numerical calculation of the growth and the residual stresses in the metal/oxide system has been performed taking into account the microstructural morphology of the interface and also the growth deformation due to the interfacial ordering that has been detected by LEED analysis2.

1C. Liu, A.M. Huntz and J.L. Lebrun, Materials Science and Engineering, A160, 113 (193) 2T.M. Christiansen, C. Raoul and J.M. Blakely, Appl. Surf. Science, 26, 408 (1986)

EP-5 Friction and Wear Processes of Aluminium in Magnetic Field
Z.H Zaidi, P.D Paulmier (National Polytechnics Institute of Lorraine, France); B.A Bouchoucha (Universite de Constantine, Algeria); E.M.M El Mansouri (National polytechnics Institute of Lorraine, France)

This paper describes an investigation on the combined influence of environment and applied magnetic field on the friction and wear processes of aluminium. Experiments are carried in ambiant air on aluminium/steel couple. Applied magnetic field modifies the size and the behaviour of third body in sliding contact and increases the rubbing surface microhardness.

The aim of this paper is to present the experimental study of friction and wear behaviour of aluminium and their variations induced by applied magnetic field.

EP-6 Tribological Study of Metal-Doped MoS2 Coatings
D.Y. Wang, Z.Y. Chen (National Chung Hsing University, Taiwan, ROC); C.L. Chang (National Chung Hsing University); W.Y. Ho, J. Chang (Surftech Corp., Taiwan, ROC)
Sputtered MoS2 thin films provided superior lubrication and wear improvements for vacuum and space applications. When exposed to humid environments, however, MoS2 was prone to rapid deterioration by oxidation. Additional modification was required to stabilize the MoS2 phase structure if atmospheric applications were anticipated. In this study, highly densified MoS2 thin films were deposited by the unbalanced magnetron (UBM) sputtering process, which eliminated the columnar structure by its high-ion-current plasma. The advent of UBM technology has provided sufficient ion bombardment to the growing film. Significant improvement in the interfacial strength and film adhesion was demonstrated. Various metal ions were incorporated into the MoS2 matrix by co-sputtering from auxiliary metal targets. The oxygen affinity of metal inclusions provided a protection mechanism to shield MoS2 from oxidation. The capability of oxygen stabilization by Al and Ti ions was compared and discussed by GDS, XPS, and DTA/TGA. The combination of effective ion bombardment from UBM process and the phase stabilization by metal inclusions rendered the metal-doped MoS2 thin film highly promising for atmospheric applications.
EP-7 Properties of the WC Coatings Deposited on Various Substrates by Cathodic Arc Plasma Deposition
S. S. KIM, J.G. Han (Sung Kyun Kwan University, KOREA); S.Y. Lee (Hankuk Aviation University, KOREA)
It is generally recognized that the a high degree of ionization could be achieved using cathodic arc plasma deposition (CAPD) process. In this study tungsten-carbide coatings on various substrates, such as Si-wafer, steel, and WC-Co were made using CAPD process. Properties of WC films as a function of total gas pressure and substrate bias during the CAPD process were characterized. The structural variation were studied by X-ray diffraction and X-ray photoelectron spectroscopy and the coating rate and the fracture morphologies of WC films were investigated using scanning electron spectroscopy. Preliminary results indicated that the structural properties of the WC films were strongly dependent upon the substrate bias as well as gas pressure. As the bias voltage increased, the tendency for the crystallization of WC films increased even without the additional annealing. The micro-hardness of the deposited WC films were higher than that of the bulk WC-Co. Detailed results on experiments on progress will be presented.
EP-8 Corrosion of a Zn-Al-Cu Alloy Coated with TiN/Ti films
M. Flores (Universidad de Guadalajara, Mexico); S. Muhl, M.C. Piña, J.L. Heiras (UNAM, Mexico)
TiN and Ti coatings were deposited by magnetron sputtering on a Zn-Al-Cu alloy. The coatings were deposited at relative low temperature, about 423 K. The pure titanium interlayer was used to improve the adhesion and corrosion resistance of the titanium nitride films. The corrosion behavior of samples in NaCl solutions was studied using polarization curves. Scanning electron microscopy was used to study both microstructure of the TiN/Ti coatings in cross-section and the samples damaged by corrosion. It was found that corrosion resistance of coated alloy was higher than the substrate resistance. The corrosion resistance is mainly controlled by the presence of different types of defects.
EP-9 Fatigue-Corrosion Behavior of an Annealed AISI 1045 Carbon Steel Coated with Ni-P Electroless
A. Pertuz (Central University of Venezuela, Venezula); J.A. Chitty, M.H. Staia, H.E. Hintermann, E.S. Puchi (Central University of Venezuela, Venezuela)
Fatiuge-corrosion tests under rotatory bending conditions have been conducted on Ni electroless coated and uncoated samples of an annealed AISI 1045 carbon steel in three different corrosive environments. The Ni-P coating of approximately 20 μm was obtained employing a solution of NiSo4 as a source of Ni ions and sodiumhypophosphite as a reducing agent in an acid medium. The fatigue-corrosion tests were conducted at 50 Hz, employing solutins of 3% and 5% NaCl, and distilled water as corrosive environment. Three stress levels were chosen corresponding approximately to 70, 80 and 90% of the yield stress of the material. The results obtained indicate that in the coated samples the deposit increases the fatigue-corrosion life of the substrate and that this increment is more marked at the lowest stress level. The fatigue-corrosion behavior observed for the coated and uncoated samples tested in the two NaCl solutions was very similar which indicates that the NaCl concentration in this interval does not affect the performance of the Ni-P coating. In distilled water the fatigue corrosinbehavior was observed in comparison the NaCl solutions.
EP-10 Tribological and Mechanical Properties of Plasma and Pulse Plasma Nitrided AISI 4140 Steel
B. Podgornik, J. Vizintin (University of Ljublijana, Slovenia)

Plasma nitriding is usually used for ferrous materials to improve the surface properties of these materials. Knowledge about properties of thin surface layers is essential for designing engineering components with optimal wear performance.

In our study, we have investigated and compared the microstructural, mechanical and tribological properties of plasma and pulse plasma nitrided AISI 4140 steel. The influence of nitriding case depth as well as the presence of compound layer on tribological behaviour was also examined. Plasma and pulse plasm nitriding was carried out using commercial nitriding processes. Nitrided samples were fully characterised, using metallographic, SEM microscopy, microhardness and profilometry techniques, before and after wear testing. Wear tests were performed on pin-on-disc wear testing machine in which nitrided pins were mated to hardened ball bearing steel discs. The wear tests were carried out under dry conditions where hardened samples were used as a reference. The resulting wear loss as well as the coefficient of friction was monitored as a function of load, sliding speed and test time. Several microscopy techniques were used to analyse the worn surfaces and wear debris in order to determine the dominant friction and wear characteristics.

EP-11 Deposition of Ni-P-BN(h) Composite Autocatalytic Coatings
O.A. León (UNEXPO, Venezuela); M.H. Staia (Central University of Venezuela, Venezuela); H.E. Hintermann (Swiss National Science Foundation, Switzerland)
Experiments were performed in order to study the autocatalytic deposition of Ni-P-BN(h) composite coatings on 316L stainless steel. Particles of Bn of an average of 7.39 μm have been suspended in the nickel chloride-sodium hypophosphite solution by argon enhanced agitation. The effect of processing parameters as: particles volume percent and the dispersant percentage added to the plating solution on the microstructure and the chemical composition of the as deposited coatings properties have been assesed by using scanning electron microscopy, X-ray diffraction and thickness measurements. Comparison between the sliding wear behaviour and friciton coefficients between the free particles electroless nickel and composite deposits are also reported.
EP-12 Mechanical Behavior of an AISI 1045 Carbon Steel Coated with Ni-P Electroless
J.A. Berr@aa I@os, E.C. Hernández, M.H. Staia, H.E. Hintermann, E.S. Puchi (Central University of Venezuela, Venezuela)
Fatigue tests under rotatory bending conditions have been conducted on Ni electroless coated and uncaoted samples of an annealed AISI 1045 carbon steel. The coating was determined to have approximately 9% P and thicknesses ranging between 7 and 37 um. Two post-yeat treatments applied to the coating were also investigated: 200 OC for 60 minutes (PTT-1) and 200 OC for 60 min. Followed by a second stage at 400OC for 60 min. (PTT-2). The two post-heat treatments gave rise to surface hardness of approximately 600 and 1044 KHN respectively. For the monotonic tensile tests conducted in the coated samples a slight reduction of the yield and tensile stress was observed, whereas the ductility and the fracture stress decrease significnatly as the coating thickness increases for both post-heat treatments. The results of the fatigue tests indicate that in the coating of 7 μm with PTT-1 there is a slight increase int eh fatigue life and that as the coating thickness increases a significant decrease in the fatigue life takes place. The decrease in the fatigue life for the deposits with PTT-2 is more pronounced than that observed for the deposits with PTT-1. However, this effect is less marked as the coating thickness increases.
EP-13 Bonding and Sliding Wear Behavior of Diamondlike Carbon Coating on Fiber Reinforced Aluminum
A. Dorner (University of Chemnitz, Germany)
Carbon fiber reinforced aluminum offers a widespread range of advanced properties in comparison with unreinforced aluminum. However, little effort has been carried out in terms of improving the functionality of the composites surface. The presence of carbon fibers in the aluminum increases the supporting effect of the substrate. Therefore, reinforced aluminum can be used under higher wear loads than the ductile unreinforced aluminum. The following studies are addressed to assess the bonding of the diamondlike carbon (DLC) coatings on the reinforced aluminum and to characterize the wear behavior of the coated and the uncoated metal matrix composites (MMCs). It was found that the composites with perpendicularly orientated fibers are significantly more wear resistant than MMCs with longitudinal fiber orientation. The deposition of the DLC coatings leads to a further remarkable increase of the sliding wear resistance. Results from the scanning electron microscopy and the scratch test confirm good bonding between the DLC coating and the MMC substrates. However, the early cohesive failure of the DLC coatings has to be prevented. Future research aims to use suitable internal coatings and to vary the deposition parameters.
EP-14 Fretting Wear Behavior of AISI 430 SS Against TiN Coated HSS Steels
A. Osma, A.S. Arcelik, K. Kazmanli, E.S. Kayali, M. Urgen (Istanbul Technical University, Turkey)
The fretting wear behavior of AISI 430 SS against TiN caoted HSS steel was investigated depending on the frequency and load. Tangential force - displacement characteristics for all the fretting conditions were determined. The effects of these parameters on wear mode namely; partial and gross slip were evaluated by regime indicator, and by optical and electron microscopical investigation of the wear scar on TiN coated HSS. The relationship between the frequency-load and wear mode is plotted thus, wear maps were created.
EP-15 The Role of The Transferred Layers in Friction and Wear of Magnetized Dry Frictional Applications.
M. EL Mansori, M Schmitt, D. Paulmier (National Polytechnics Institute of Lorraine, France)

Dry rubbing of the steel XC48/graphite couple has been studied in the presence of a magnetic field and the results are compared with those obtained from similar experiments without magnetic field.

In this study, employing a combination of scanning electron microscopy and energy dispersive X-ray spectroscopy, the authors explored the properties of the wear particles and the friction tracks of steel/graphite couple and described their friction and wear mechanisms in open air of 20-30% relative humidity at room temperature, under reduced pressure (3.10-3 Pa) conditions and in a pure argon (purity, 99.95%).

The results of the tribological tests indicated that the friction coefficient decreased about 30% with the presence of a magnetic field applied through the contact in open air. However, in vacuum or in argon, magnetic field increased the friction coefficient respectively about 33% and 70%.

The wear rates of graphite disc were lower in air than under inert environment.

The wear is very low when the transferred carbon films present a good adhesion on metal surface of the counterface. This adhesion depends on the cohesion of solid particles within the film, itself depending on the chemical properties of the transfer layer. Then, thin graphite films have a longer life than thick mixed films.

The results of the surface and the wear debris analytical studies, obtained on graphite/steel magnetized sliding contact, have suggested a correlation between the transferred layers and its tribological behaviour

EP-16 Wear Behavior of DLC/Metal Carbides Multilayers
M.P. Delplancke-Ogletree (Université Libre de Bruxelles, Belgium); O.R. Monteiro (Lawrence Berkeley National Laboratory)
We have prepared multilayers of DLC/TiCx and DLC/WCx by filtered cathodic vacuum arc, investigated and compared their wear properties at room temperature. The films were deposited on polished oil hardened AISI 01 tool steel substrates. The number and thickness of the layers constituting the films were varied. The total thickness was similar from film to film, but the number of constituting layers changed. In all films the layer in immediate contact with the steel and the topmost layer were DLC. Friction coefficient and wear were determined as a function of the atmosphere and load in a ball-on-disk test. The tests were performed in dry nitrogen and in air with relative humidity of 50%. Initial Hertzian contact pressures in the range of 0.1 to 5 GPa were used with alumina balls. The failure mechanism in each case and the wear volume were deduced based on scanning electron microscopy and profilometry.
EP-17 Evaluation of TiN, CrN, and TiCrN Coatings Under Sliding and Rolling Contact
J.H. Sanders, J.S. Zabinski (Air Force Research Laboratory)
TiN, CrN, and TiCrN were evaluated in sliding and rolling contact to determine their relative properties for use in high contact stress applications. Sliding contact was evaluated using a ball-on-flat tribometer in ambient air and nitrogen environments. Rolling contact was evaluated using coated M-50 rods in a rolling contact fatigue test apparatus at 5.5 GPa total load. Mechanical properties investigated included microhardness, crack propagation resistance, and coating/substrate adhesion. Results demonstrate that most all the TiCrN properties fall within the values determined for TiN and CrN. However, rolling contact fatigue results reveal that TiCrN has a longer fatigue life (higher L50) and more predictable service life (steeper slope) than both TiN and CrN. This investigation demonstrates the potential for multi-component coatings in rolling contact applications.
EP-18 Friction and Wear Behaviour of Crystallized Carbon Thin Films
Z.H Zaidi (Université De Poitiers, Faculté des Science, France); D. Paulmier, T. Le Huu (National Polytechnic Institute of Lorraine, France)
This report is about the fundamental and specific friction and wear mechanisms of hard carbon coatings: Diamond coatings, Diamond-like carbon (DLC), Amorphous hydrogenated carbon films (a-C:H), Amorphous diamond like carbon film (a:DLC), Amorphic carbon (a-C) and Amorphic diamond film (a-D). Tribological studies of hard carbon coatings move with the carbon films deposition technique development. Friction coefficient u and can be varied by 50 factor (u - 0.02 - 1) and the wear rate by 102 to 104 factor following the hard carbon film nature, the tribocontact gas environment and the sliding contact temperature. A compilation of published studies since ten years ago concerning the mechanical and tribological behaviour of different hard carboncoating will be presented and discussed in view to specify each film behaviour according to its nature and its mechanical properties. The transition phenomena from mild wear to dust wear is investigated for each rubbing surface.
EP-19 Mechanical and Tribological Proberties of Hard Multilayer Carbon Films Prepared by the Laser-arc Technique
H. Ziegele, H.-J. Scheibe, S. Schaedlich (Fraunhofer Institute - IWS, Germany); C. Rebholz, A. Matthews (University of Hull, United Kingdom)
The method of laser-induced vacuum arc (Laser-Arc) combines the good controllability of pulsed laser deposition with the high efficiency of a vacuum arc technique. One advantage of this technique is the reduction of droplets, allowing the deposition of high quality amorphous carbon films. These hydrogen-free films with very high hardness (up to the superhard range) exhibit excellent wear resistance and low friction. Multilayer films consisting of aluminium and carbon were deposited on a metallic substrate (90MnV8). A Rockwell C tester and an impact-tester were used to assess the mechanical properties and the adhesion of the coatings to the substrate. The Youngs moduli were measured by the non-destructive ultrasonic surface wave method (US-SAW). The coefficient of friction was investigated by using two different fretting wear tests with the same load but different frequencies and stroke lengths.
EP-20 Three Body Wear Test of TiN Coatings
M.H. Staia, E.S. Puchi, E. Hernandez (Central University of Venezuela, Venezuela)
The present paper reports the results of the evaluation of the abrasive wear resistance of TiN CVD and PVD coatings on 316L stainless steel by using the modified ball cratering technique proposed by Staia et al.. A standard ball cratering equipment was modified in order to deliver the abrasive media, based on diamond particles of 1 um, at a constant rate of 2.5 ml/h. A ball bearing RB38.1/G100P3 is rotated against the sample by means of a V shaped shaft with a linear velocity of 1.11 m/s. The applied load was of 1N and its calculation wa performed without taking into account the presence of the friction forces between the ball and the sample and the ball and the V shaped shaft. Reproducible results were obtained fro the wear constants of the coatings and the substrate, which were determined by using the theory proposed by Kassman et al. The abrasion wear resistance of the analyzed coatings has been related to the nature of the deposition process and the physical and mechanical properties of the coatings.
EP-21 Local Yield Map and Elastic-Plastic Deformation Map of Hard Coating with Lubricative Particles Under Sliding
D. Diao, K. Ito (Shizuoka University, Japan)
The design of anti-friction coating able to perform well in different wear conditions without lubricants requires a combination of a low friction coefficient and a low wear rate. Recently introduced hard coating with lubricative particles can be a major step towards the achievement of the combination. However, the trouble of such coatings in practical usage is their high failure and spalling tendency caused by the initiation and propagation of micro-cracks at the interface between coating and lubricative particles or at the interface between coating and substrate. Therefore, the inhibiting factors in using these coatings for anti-friction application are our limited knowledge on the critical stress distribution for the plastic deformation or the fracture. In this paper, the von Mises stress distribution in the coating with particles under sliding were analyzed by the finite element method. An elliptical distribution of normal and traction contact pressure was assumed for the analysis of von Mises stress for various combinations of the coating thickness, yield strength and the friction coefficient. The positions of yield were found with the calculated result and the local yield map was introduced in relation to the yield strength ratio of lubricative particle to coating and the ratio of coating thickness to half-contact width. The local yield maps show that the position of yield depends strongly on the yield strength of coating, particle and substrate. When the yield strength ratios of particle to coating and coating to substrate are low, yield in the particle is most general case in wide range of contact condition. Contrariwise, the yield occurs on the surface or at the interface, which depends the friction coefficient and the ratio of coating thickness to half contact width.
EP-22 Combining Scanning Force Microscopy with Nanoindentation for More Complete Characterisation of Bulk and Coated Materials
N.X. Randall, C Julia-Schmutz (CSEM Instruments, Switzerland); J.M. Soro (URA CNRS, France)
The mechanical properties of thin films as well as bulk materials can be measured by a variety of different techniques, with nanoindentation being one of the most recent developments in this growing field. By using a depth-sensing indentation method it is possible to obtain quantitative values for the hardness and modulus, and thus gain better insight into the response of a material to controlled deformation of such small scales. However, the calculation of such values from conventional load-displacement curves can prove inaccurate owing to the effects of pile-up and sink-in which invariably occur during the indentation of many types of material and which seriously affect the calculation of residual contact area. This paper addresses the problem and suggests the use of scanning force microscopy (SFM) as a complimentary tool which allows the true residual contact area to be measured. In addition, some experimental results are presented for a variety of bulk and coated materials, these confirming the use of the SFM for obtaining significant additional information concerning the true response of a material to instrumented indentation at a nanometric scale, e.g., elastic/plastic deformation, crackling, phase transformation, pile-up/sink-in effects, etc.
Time Period WeP Sessions | Topic E Sessions | Time Periods | Topics | ICMCTF1998 Schedule