ICMCTF2006 Session TS1-2: Coatings for Automotive Applications

Tuesday, May 2, 2006 8:50 AM in Room Sunset

Tuesday Morning

Start	Invited?	Item
8:50 AM		TS1-2-2 Development of Multifunctional Nanocomposite Coatings with Extreme Resistance to Wear and Scuffing Under Boundary Lubricated Sliding Conditions A. Erdemir, O. Eryilmaz, O. Ajayi (Argonne National Laboratory); M. Urgen, M.K. Kazmanli (Istanbul Technical University, Turkey) Using the general principles of a crystal chemical model [1], we have recently formulated a series of novel nanocomposite coatings that can provide very low friction and extreme resistance to wear and scuffing under sever boundary lubricated sliding conditions. These coatings essentially consist of a soft metallic and a hard nitride phase; both of which are strategically formulated to react favorably with some of the additives in engine oils and hence to result in very protective, low-shear boundary films. The kinds of boundary films that form on the sliding surfaces of these nanocomposite films are extremely resistant to wear and scuffing. In a series of scuffing tests, we were unable to scuff these nanocomposite films under sever contact pressures that caused significant plastic flow in substrate steels. The results of this study suggest that these novel nanocomposite coatings have the potential to meet the increasingly stringent application conditions of future engine systems including ring and liner assembly, gears, tappets, bearings, and other power and drivetrain components. In this paper, we will introduce the main characteristics of these novel nanocomposite coatings and present the fundamental tribological mechanisms that control their superior friction, wear, and scuffing behavior under severe boundary lubricated sliding conditions. Principles of crystal chemical model that was used as a guide in the formulation of these nanocomposite films are also presented. This model provides a scientific means to better design and formulate future tribological coatings that provide not only low friction but also extreme resistance to wear and scuffing. ¹A. Erdemir, A Crystal Chemical Approach To the Formulation of Self-Lubricating Nanocomposite Coatings, Surface and Coatings Technology, in press 2005.
9:10 AM	Invited	TS1-2-3 Coating Applications Applied in Caterpillar Products C. Dam (Caterpillar Inc.) Surface coatings are being applied at Caterpillar for variety of engineering purposes. Caterpillar produces engine components such as fuel injector and wrist pin to bull dozer and off highway machines, which have many contacting surfaces for wear and corrosion challenges. Coatings that have been applied on Caterpillar components are CrN, metal DLC, a-DLC, as well as various metal and ceramic thermal spray coatings. This talk will address selections of coatings based on their properties such as wear, corrosion, thermal resistance as well as friction coefficient. The base material of the component often reduces and dictates the coating choices. Choosing the coating thickness for each application also has an important functional and economical factor. Specific applications for track bushing, fuel injector and engine applications will be discussed to illustrate the method for selecting coatings.
9:50 AM		TS1-2-5 Application of Novel PVD Coatings on Wear Components: An Overview R. Aharonov, R. Fontana, H.O. Gekonde (IonBond, LLC) In recent years with growth of coatings portfolios many wear components applications have been identified in the automotive, earth moving, aerospace, and medical industries. The use of cheap substrate materials with inferior properties has made coatings attractive from the standpoint of the total component price reduction offered by coatings. In order to utilize the price advantage of coatings, sophisticated coating fixtures are being developed to maximize coating load sizes and minimize cost. Coating specifications for components are put in place and the integral properties tested to ensure high coating quality and consistency. Examples of such applications are presented in the current paper.
10:10 AM	Invited	TS1-2-6 Corrosion Reduction, the Next Coating Requirement for Automotive Applications G. van der Kolk (IonBond Europe, Switzerland) PVD and PACVD coatings in automotive applications have so far been mainly used for low wear applications. The good frictional behaviour has been a key asset. Applications utilizing this property are still increasing. The trend in coatings applied is converging. It is believed that the coating applications will further broaden in automotive, if PVD-PACVD coatings can bring a proper corrosion performance. Unlike low friction coatings the technical solutions are still widely diverging. An overview will be given of present development of corrosion inhibitors. Furthermore a number of practical examples will be given, of parts being coated, with one of the main requirements a proper corrosion protection.
10:50 AM		TS1-2-8 Boronization of Nickel and Nickel Clad Materials K.S. Weil, Z.G. Yang, G.-G. Xia, J.Y. Kim (Pacific Northwest National Laboratory) The bipolar plate is the most bulky component in the PEMFC stack (in both weight and volume) and one of the most expensive to manufacture. It serves not only as the electrical junction between serially connected cells, but also performs several other key functions in the device, including: (1) distribute the fuel and oxidant uniformly over the active areas of the cells, (2) facilitate water management of the membrane to keep it humidified, yet mitigate flooding, (3) act as an impermeable barrier between the fuel and oxidant streams (particularly H₂) to maintain the hydrogen gradient across the membrane necessary for high power output, (4) provide some measure of structural support for the stack, and (5) remove heat from the active areas of the cells. The use of metal-based bipolar plates in PEMFC stacks potentially offers a number advantages particularly for transportation applications including: low-cost, mass-production via stamping or embossing of sheet product; fabrication in very thin form (< 200µm) to reduce weight and volume in the overall stack; impermeability to fuel, oxidant and water vapor; and in general, excellent thermal conduction properties and good mechanical robustness, even as a thin stamped foil. The primary challenge with metal interconnects is surface corrosion, and the current drive to increase the operating temperature of the stack will only exacerbate this problem. Corrosion of the bipolar plate leads to a release of metal ions that can contaminate the electrolyte membrane and poison the electrode catalysts. In addition, the formation of a passivating oxide or oxyhydroxide layer on the surface of the metal will increase the contact resistance between the bipolar plate and the adjacent graphite electrode backing layer by many orders of magnitude. Both conditions can significantly degrade stack performance. Here we discuss the use of passivated clad metals as potential PEMFC bipolar plate materials.
11:10 AM		TS1-2-9 Plasma Spraying Technology for Engine Components G. Barbezat, P. Meyer (Sulzer Metco, Switzerland) The deposition of plasma sprayed coating allows a reduction of the friction in the boundaries condition of lubrication. A reduction of fuel consumption of 2 to 3 percents was measured on different types of gazoline and diesel engines. The material aspect respectively metallurgical consideration are discussed in details. Further this technology presents several advantages for the EGR diesel engines.The abrasion resistance of the coating is increased by addition of suitable oxide ceramics.