ICMCTF2005 Session TS2-2: Coatings and Automotive Applications

Wednesday, May 4, 2005 1:30 PM in Room Sunset

Wednesday Afternoon

Start	Invited?	Item
1:30 PM		TS2-2-1 Friction Properties of Ta-C and a-C:H Coatings Under High Vacuum C. Meunier (FEMTO-ST/CREST, France); P. Alers (Vacotec SA, Switzerland); J. Stauffer (CAFI, Centre Analyses par Faisceau Ionique, Switzerland); N. Randall (CSM-Instruments Inc.); S. Mikhailov (CAFI, Centre Analyses par Faisceau Ionique, Switzerland) The tribological behaviour of ta-C and a-C:H carbon films was analysed by pin-disc tests under ultra high vacuum (<10^-5 mbar). The tests were executed on a commercial High Vacuum Tribometer (CSM-Instruments) and compared with results obtained under controlled atmospheric pressure conditions. In this work, we present the comparison of the friction coefficients under high vacuum and under controlled atmosphere conditions of two sets of carbon films, one prepared by FCVA (giving rise to hydrogen free carbon), the other by PECVD (leading to hydrogenated carbon). The structure of these films was analysed by Raman and RBS-ERD spectroscopy as well as by XR reflectometry. We will demonstrate that under vacuum, FCVA carbon layers do not slide ( µ = 0,5-0,7) but PECVD carbon films have a good sliding behaviour (µ = 0,1-0,3). An inverse behaviour was observed under controlled atmospheric conditions. These first results indicate a predominant role of the structure of the films, as analysed by Raman and RBS-ERD spectroscopy as well as by XR reflectometry, on the tribological characteristics of the carbon films. In particular the influence of hydrogen concentration seems to be directly linked to the Vacuum tribological behaviour of the coatings.
1:50 PM		TS2-2-2 Tribological Reactions between Oil Additives and DLC Coatings for Automotive Applications B. Podgornik (University of Ljubljana, Slovenia) In the past, the development of modern engines and transmissions would have been impossible without advanced lubricant additive chemistry and proper lubricant formulation. In order to meet demanding durability and performance requirements engine and transmission oils contain a wide range of additives. Especially anti-wear (AW) and extreme-pressure (EP) additives are crucial in minimizing friction and wear and protecting contact surfaces under severe contact conditions. It is described in detail that the mechanism by which AW and EP additives reduce friction and wear of metallic surfaces under boundary lubrication is due to formation of tribofilms, activated by tribochemical reaction between additive molecules and metallic surface. Introduction of DLC coatings opens further possibilities in improving performance of automotive components, which can not longer be achieved only by lubricant design. Although DLC coatings show low friction and wear under dry sliding conditions the majority of automotive components will remain lubricated, at least for the near future. Therefore, for successful application of coated components aimed for further performance enhancement in automotive industry (lower friction and fuel consumption, higher load bearing capacity,...) coatings will have to perform adequately also under oil-lubricated conditions. Investigations so far indicate that in certain cases DLC coated surfaces may show improved tribological properties when lubricated by additivated oil. However, the mechanism responsible is not yet fully understood. With the aim to add some further understanding to this important area and to be able to fulfill future automotive requirements, the paper will focus on describing reactions of EP and AW additives with DLC coatings aimed for automotive components. Results from investigations on doped and un-doped DLC coatings tested under boundary lubricated conditions will be presented and compared to uncoated steel surfaces.
2:10 PM	Invited	TS2-2-3 Equipment Design Aspects of Large Scale Automotive Applications. R. Tietema, T. Krug, C. Strondl (Hauzer Techno Coating BV, Netherlands) Special know-how and engineering efforts are needed for upscaling PVD processes from laboratory to industrial scale. These processes should run reliable and with a high availability in order to guarantee high performance with respect to quality and performance. Safety as well as environmental issues have to be taken in account as well. At the end minor issues can play a major role of importance in the production of PVD coatings. This makes it particularly difficult to accomplish the required system quality issues for the PVD process system under all possible conditions. Besides the specification issues mentioned above, being normally already regarded as issues to be met above any doubt within the defined limits, the system productivity plays the major role for these systems with regard to the cost price of the coating per coated piece. In this presentation will be shown how technical and organizational issues must be tackled to produce well designed systems with a high quality performance.
2:50 PM	Invited	TS2-2-5 Advanced Thermal Spray Technology and Coating for Lighweight Engine Blocks for the Automotive Industry G. Barbezat (Sulzer Metco AG, Switzerland) New advanced thermal spray technology allows providing wear resistant coatings on the cylinder surface on Aluminum or Magnesium engines. The obtained special surface topography after the finishing allows to decrease significantly the coefficient of friction and to decrease the fuel consumption of an amount of 2 to 4 percents. Engine tests on diesel and gasoline engines have confirmed the value of this technology regarding the aspect of energy saving. This coating technology is introduced since four years in Europe by the manufacturing of high power diesel respectively gasoline engines. The combination of different MMC coating materials allows the development of new specific solutions for each types of engine. Coatings with improved corrosion resistance and abrasion resistance were also developed and are available now. A brief overview on other applications of thermal spraying in the automotive industry will be given also.
3:30 PM	Invited	TS2-2-7 Future Demands for Coatings in Gasoline and Diesel Fuel Systems T. Bordewyk (Delphi Automotive Systems)
4:30 PM		TS2-2-10 Sputter Coatings for Bearing Applications W. Gärtner (Del West)
4:50 PM		TS2-2-11 Corrosion Properties of Anodic Oxide Coatings on an Al-Si Alloy X. Li, D.O. Northwood, L. Wang, X. Nie (University of Windsor, Canada) Metallic bipolar plates for polymer electrolyte membrane fuel cells (PEMFC) are currently being investigated because of their potential to reduce costs and enhance power density. In this research, two types of steel, 316L stainless steel (SS) and 1020 carbon steel (CS), were selected as the base material for bipolar plates (BP). Some samples were treated by a plasma electrolytic nitriding (PEN) technique. Corrosion tests were conducted in both a 3.5wt.% NaCl solution and a simulated PEMFC operating environment. The surface morphology and composition of both nitrided and un-nitrided samples before and after corrosion were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The interfacial contact resistance (ICR) was measured as a function of the contact force. By comparing the properties of nitrided and un-nitrided samples, the most promising candidate for low-cost metallic BP material can be identified. Keywords: Bipolar plates, steel, nitriding, corrosion, fuel cell.