ICMCTF2002 Session E5/D4-3: Properties and Applications of Diamond, Diamondlike and Related Coatings

Friday, April 26, 2002 9:10 AM in Room California

Friday Morning

Start	Invited?	Item
9:10 AM	Invited	E5/D4-3-3 The Behavior of Me-DLC Coatings in Combined Rolling and Sliding Contact-- Theory and Experiment C.V. Cooper, A.K. Flodin, A.V. Staroselsky (United Technologies Research Center); A.G. Evans, C. Mercer, R. Wang (Princeton University); S. Suresh, M. Dao (Massachusetts Institute of Technology); L.M. Keer, F. Borodich, Y.-W. Chung (Northwestern University); M.A. Taher, H.K. Yoon, D. Hua (Caterpillar Inc.) The behavior of metal-containing, diamond-like-carbon (Me-DLC) coatings in rolling contact is significantly different from their behavior in pure sliding. The former contact type often leads to a coating failure mechanism of brittle fracture in an adhesive and/or cohesive manner, and the latter contact type often leads to an increase in the actual area of contact with sliding distance through shear deformation of the coatings. Moreover, the degradation behavior of Me-DLC coatings depends strongly on both composition and processing. Applications that include both rolling and sliding contact, such as power-transmission gears, exhibit behavior that is intermediate between the two extremes, often acting more similarly to behavior in pure sliding than in pure rolling. The authors have conducted a systematic study to determine the behavior of two types of metal-containing DLC coatings, those containing W and Cr, through experiments that impose pure sliding and both rolling and sliding. Using post-test characterization techniques that include focused-ion-beam (FIB) SEM and atomic force microscopy (AFM), interesting contrasting behavior of the coatings in sliding contact has been observed. Measurements to determine coating residual stress and interfacial fracture energy have enabled the development of a model that describes the observed behavior. In addition, using a first-principles approach, the authors are developing a model to express coating lifetime that includes contributions from chemical interactions, phase transitions, and fracture. The results of this systematic study will be presented and compared to results reported in the literature.
9:50 AM		E5/D4-3-5 Abrasive Wear Testing of DLC Coatings Deposited on Cylindrical Parts T.M. Michler, C.S. Siebert (Balzers Verschleissschutz GmbH, Germany) Testing of mechanical and/or tribological properties of DLC coatings is essential for quality control. A widely used method is testing the wear resistance by high precision calotte grinding. Up to now, this method was only used for flat substrates. A method for calculating the wear volume on cylindrical parts as well as some results are presented.
10:10 AM		E5/D4-3-6 Investigation on the Formation of Metal Carbide Crystallites for Boron and Tungsten Containing Diamond Like Carbon Coatings C. Strondl, G.J. van der Kolk, T. Hurkmans (Hauzer Techno Coating BV, Netherlands); J. Vyskocil (HVM Plasma Ltd); N.M. Carvalho, J.Th.M. de Hosson (University of Groningen) Two different series of metal containing diamond like carbon (Me-DLC) coatings have been produced by unbalanced magnetron sputtering. For the first series of Me-DLC coatings, sputtering from WC targets have been used to form W-C:H coatings. For the second series of Me-DLC coatings, sputtering from B₄C targets have been used to form B-C:H coatings. In each series of Me-DLC coatings, the metal to carbon ratio has been varied to study changes in the metal carbide crystallite size and distribution within the a-C:H matrix. The aim of this investigation has been to determine the difference in the formation of the metal carbide nano crystallites between boron and tungsten containing Me-DLC coatings and also for different B:C respective W:C ratio. The difference in the formation of the metal carbide nano crystallites is then linked to changes in the mechanical and tribological properties of the coatings. Detailed high-resolution cross-section TEM has been carried out to analyze the microstructure of the coatings. The mechanical and tribological properties like coefficient of friction, hardness and E-modulus, wear resistance and adhesion have been investigated.
10:30 AM		E5/D4-3-7 Influence of Coating Architecture on the Tribological Behaviour of DLC-type coatings O.K. Massler, J. Karner, R. Herb, H. Eberle, B. Hanselmann, M. Grischke (Balzers AG, Liechtenstein) For tribological applications on precision components, DLC-type coatings have proved their use to prevent various types of wear mechanisms. Carbon based films for tribological applications coatings are represented by a wide variety of films with a wide range of properties and behaviour. Parameters like the coating composition, film structure and surface morphology determine the performance of the coatings. The hardness, abrasive wear resistance, frictional behaviour can vary to such a degree, that the test results in an application cannot be predicted easily. Since there is no standard for the architecture of the films, there also cannot be a general standard for the film performance. The complexity of tribological systems demands a knowledge of the mechanisms occurring on the surfaces and a detailed understanding the behaviour of the films. The conservative theories of plastic deformation cannot be applied easily on the mostly amorphous films with graded interfaces, multilayer structures and a widely varied mix between metallic and ceramic ingredients. The importance of the basic mechanisms of film behaviour like running-in behaviour, plastic properties of the layers, crack propagation within the films and abrasive wear resistance of the functional coating for the performance of the tribological system is demonstrated on some applied examples.
10:50 AM		E5/D4-3-8 On Tribological Performance of Diamond-like Carbon Films Synthesized by a Hybrid Filter-Arc Evaporation Process K.W. Weng (National Chung Hsing University, Taiwan, ROC) Diamond-like carbon film (DLC) was synthesized successfully using a hybrid PVD process consisting of a filter arc evaporator and a Metal plasma ion implanter (MPII). Density of macroparticles was substantially reduced by a quarter torus plasma duct filter. Graphite targets were used in the cathodic arc evaporation process. Intensive electron and ion energy generated from the plasma duct facilitate the activation of carbon plasma and deposition of high quality DLC films. To enhance the film adhesion and surface properties, DLC films were co-deposited with high-energy carbon ions at 2x1017 atmos/cm² dosage. The ion energy is maintained at 45 KV. The effect of ion mixing at film interface is examined using TEM microscopy. The phase transformation and reduction of residual stress at the film surface are investigated.
11:10 AM		E5/D4-3-9 Tribological Properties of BCN Thin Films Synthesized by Cesium Ion Sputtering E Byon, J.-K. Kim, S.H. Lee, J.-H. Han (Korea Institute of Machinery and Materials, Korea); K. Sugimoto (Tohoku University, Japan) The BCN thin films were synthesized using Cesium Ion Sputtering. Optimum process parameters were developed by the method of Taguchi L9 experiment. Hardness of BCN films was mainly affected by carbon sputtering power, working pressure and boron sputtering power in sequence. At the optimum process condition, the hardness and composition of BCN film were 15-16 GPa and BCxNy(x=2.4-3.2, y=1.0-1.1). From FTIR results, it was found that the characteristics of the films had mixed with sp²-BN, B-C and C-N bonding. The tribological behaviors of BCN films have been investigated by ball-on-disk tribometer. It is found that the friction coefficient is directly related to the film hardness and process parameters.
11:30 AM		E5/D4-3-10 Tribological Behavior of WC/C Nanocomposite S.J. Park (Korea Institute of Science and Technology and Yonsei University, Korea); K.-R. Lee (Korea Institute of Science and Technology, Korea); D.-H. Ko (Yonsei University, Korea); K.Y. Eun (Korea Institute of Science and Technology, Korea) The tribological behavior of WC-C nanocomposite film deposited by a hybrid deposition system of r.f.-PACVD and magnetron sputtering was investigated. W concentration in the film varied from 0 to 13 at.% by changing CH₄ ratio in Ar and CH₄ gas mixture. The tribological behaviors were investigated by using ball-on-disk type tribometer in ambient air of relative humidity ranging from 0 to 50 %. The friction coefficient of the film was decreased with the increase of the tungsten concentration. Any critical difference was not observed between ambient and dry air environment. The wear rate of the film increased with the increase of tungsten concentration in the films. On the other hand, wear rate of steel ball decreased with the W concentration. The analysis of the composition and chemical bond structure of debris showed that the nano-sized WC embedded in hydrogenated amorphous carbon matrix increased the wear rate of the film. Lower friction coefficient at higher W concentration seems to be due to the more graphitic matrix as shown in the previous work. The effect of the graphitic layer and tungsten carbide phase was more significant with increasing tungsten concentration in the film.