ICMCTF2002 Session SS-1: Surface Engineering: Needs and Research Opportunities

Tuesday, April 23, 2002 1:30 PM in Room Golden West

Tuesday Afternoon

Start	Invited?	Item
1:30 PM		SS-1-1 Some Technology Transfer Issues in Surface Engineering for Corrosion and Tribology J. Larsen-Basse (National Science Foundation); P. Kodali (Exxon Mobil Research and Engineering Company) The field of surface engineering has developed rapidly during the past decade or two, especially at the research level. Many new developments that currently are at the laboratory stage have the potential to make significant contributions to the technologies of the future. However, the transfer of technology from laboratory to industrial application remains quite slow, typically taking 10+ years. The reasons include both technical and human-based issues. On the technical side are problems of the relatively slow development of process controls, testing techniques and standards for a whole new set of problem areas, as well as development of reliable design data for the performance of the combined bulk-surface material; problems at the human level include the education of new engineers in new science and technology, and gaining the trust of current, often by necessity risk-adverse, design engineers. In this paper we trace the barriers that were overcome in the evolution of a few selected coatings for corrosion and wear applications and point to some possible ways to lower the barriers and shorten the technology transfer times. We also outline some issues that in our opinion deserve more joint attention from the two communities - the university bench engineering scientists and their colleagues in industrial design and production.
1:50 PM		SS-1-2 Opportunities for Surface Engineering in Aerospace Systems J.S. Zabinski (Air Force Research Laboratory) There are many needs and opportunities within the aerospace community for surface engineered components and improved methodologies for modifying surfaces. The opportunities range from those requiring near term solutions, such as the support of fielded systems, to those where the engineer or scientist envisions new technology that offers significant enhancing or enabling capabilities. The latter usually requires "tech-push" since the user community may want the technology but perceives it as too distant to fund in the present. Opportunities for surface engineering in the aerospace community will be discussed along with examples of successful and unsuccessful efforts. Some lessons learned that may help permit research to translate to a surface engineered product will also
2:10 PM		SS-1-3 Aerospace Coating Needs in the 21st Century -- From a Boeing Perspective S.P. Gaydos (The Boeing Company) This presentation will describe some of the primary metal plating and coating systems that are currently used on Boeing aerospace vehicles and list the concerns that these coatings are causing the aerospace industry in terms of application, use, and maintenance. A list of requirements will then be discussed on what is needed to replace these coatings. The requirements shall include coating performance, repair, life cycle cost, environmental control and disposal issues. Candidate coatings that are currently being tested, and replacement coatings that have been successfully implemented will be briefly described. The presentation will conclude with suggestions on where the coating industry should direct their R&D efforts in order to support the needs of the aerospace industry in the 21st century.
2:30 PM		SS-1-4 One Terabit per Square Inch: a Thin Film Perspective J.K. Howard (Seagate Technologies, Inc.) Areal densities in storage products have grown at a rate of nearly 100% per annum. Recent demonstrations at 100 Gbits per square inch have been reported and continued progress is expected. However, physical limits such as the superparamagnetic limit (thermal stability) in the magnetic medium could limit the increase in storage density. The superparamagnetic limit refers to a critical grain size in the recording medium. Grains or magnetic switching units below this limit are unstable causing magnetic properties to degrade in time spans less than a few years. Several scaling models have been developed to estimate materials parameters that will be required to produce thermally stable media with acceptable signal to media noise for 1Terabit per square inch recording. These scaling models have a significant effect on the thin film technology required to fabricate the head and media (disk) components. This presentation will explore the effect of these scaling models on thin film properties such as microstructure and thickness. To meet the new requirements, new materials will need to be developed with both magnetics (head and disk) and corrosion resistance goals in mind. For example, the protective overcoat used in current disk technology is a complex mixture of Carbon-Hydrogen-Nitrogen in the 4-5 nm thickness range. These overcoats have been reported to be discontinuous below 2 nm. The Terabit overcoat will need to be 1 nm in thickness and protect the Co alloy medium from head-media contact and corrosion. Other effects of Terabit scaling on the thin films used in both head and disk will be discussed. Recording densities beyond 1 Terabit per square inch may require technologies still in the research phase such as SOMA (self organized magnetic arrays).
2:50 PM		SS-1-5 Modelling Thermal Spray Coating Processes: A Powerful Tool in Design & Optimization J. Mostaghimi (University of Toronto, Canada) Widespread adoption of thermal spray technology requires the ability to apply a variety of coating materials, suited to each new application. Introduction of new coating materials is however, time-consuming and costly. To date, thermal spray parameters have been optimized on the basis of trial and error from which empirical relationships are derived. Since a very large number of parameters are involved (e.g., powder size distribution, velocity, temperature and degree of solidification; substrate material and temperature) this approach is laborious and expensive, and must be repeated for different materials being sprayed. Development of theoretical/computational models which can predict microstructure of coatings can potentially reduce the cost of the development of new coatings considerably. Ideally, these models will allow us to tailor coating properties to meet the requirements of individual applications, without having to do extensive experimentation. The models will also allow us to improve and optimize the design of existing spraying guns. In this presentation, a complete model of the High Velocity Oxy-Fuel spray coating process will be presented. We define a complete model as one that predicts coating microstructure, e.g., porosity, residual stress, surface roughness, as a function of the spraying parameters. The model is comprised of several complementary parts: a) modeling gas flow and temperature b) particle heating and acceleration c) impact, spread, and solidification of particles on the substrate d) heat transfer within the coating and substrate e) agglomeration of splats and formation of porosity The presentation will highlight and identify directions for new research in thermal spray technology that will provide researchers and end users some new tools for informed selection of process and materials parameters, for intelligent manufacturing practices.
3:10 PM		SS-1-6 Special Surface Modification Needs in the Heavy Equipment Industry G. Revankar (John Deere and Company) The wear and corrosion problems in the agricultural, industrial and mining machinery tend to be more severe than those encountered in other types of industrial equipment such automobiles or household type machines. Many parts of these off-highway equipment come in contact with abrasive soil, gravel, rocks or other hard media, mostly under load, which produce severe wear . Frequently the machinery parts also come in contact with chemicals which produce chemical or galvanic corrosion. The synergistic effect of severe wear and corrosion results in accelerated surface material loss which is unique for heavy equipment industry. The surface modification needs of this industry continue to be only partly satisfied by applying conventional methods such as carburizing, nitriding, chrome plating and others, and have not been addressed adequately by the recent surface engineering techniques such as thermal spray, PVD, or CVD. The paper describes some of the wear problems in the agricultural and industrial equipment and presents a few potential solutions developed to counter them.
3:30 PM		SS-1-7 Surface Engineering for Metal Cutting Applications A. Inspektor, P. Mehrotra (Kennametal Inc.) Strong functional surface is the first line of defense of the cutting tool and thus vital to the performance and to the reliability of the tool. This paper will present and critically review principles of surface engineering for cutting tools, with an emphasis on current practices and future needs in the design and preparation of the cutting edge. The presented concepts will be illustrated by case studies in modern cutting tools, in superhard-coated tools and in nano-structured films.
3:50 PM		SS-1-8 Component Coating Providers - Design Partners or Mere Sub-suppliers? O. Wänstrand, D. Quinto, M. Hans (Balzers Inc.) The machine components of the global automotive industry are understandably a prime application target for vapor deposited coatings. To improve performance, R&D of surface coatings can be coupled with lubricant additives, substrate material and optimal component design, but the question is, are these being done in the most intelligent way? This scenario is illustrated by a couple of examples. Unlike cutting tool customers who are well aware of coatings and that they add value to their product, precision component customers are still in the stage of feasibility testing, with concerns on the expense and quality issues a new technology brings. From the standpoint of the surface technology provider the main problem has been that, in most component applications, the full advantage of the vapor deposited coating has not been utilized. The major reason is that the coating option is introduced in the design process at a far too late stage. Integration of the technology provider in the entire design process, rather than seeking a supplier of one limited feature of the final product, will result in better technical and cost-optimized solutions. Ideally, a coating should be considered as an option to solve tribological problems already at the initial stage of the development of a new machine or engine. Only in this way can the full potential of the coating be exploited.
4:10 PM		SS-1-9 Surface Engineering of Machine Components L. Seitzman (Caterpillar, Inc.) Tribological components in modern machines are being subjected to ever more extreme operating conditions, including elevated loads and stresses, higher speed operation and extended maintenance intervals. At the same time, machine users are demanding longer life and lower costs. To satisfy these conflicting demands, machine designers are looking to advanced surface engineering processes, such as metallurgical coatings. There is sufficient evidence that metallurgical coatings can help provide friction and wear control in many tribological applications. But which coating is right for which application? Several advanced coating processes, including thermal spray, physical vapor deposition, chemical vapor deposition and laser cladding, are commercially feasible. Each of these processes has multiple variations, leading to a surface engineering menu that contains an extensive combination of coating chemistries and architectures. New coatings are created in the lab almost everyday. The vast number of coating choices is almost paralyzing. We will examine the process of selecting metallurgical coatings for wear or friction control on machine components. We will identify selection tools available today and discuss tools that are needed to improve the process. We will address the question of how the community can put the "engineering" into Surface Engineering.
4:30 PM		SS-1-10 Needs and Opportunities for Standardized Test Methods for Ceramic Coatings in Vehicular and Stationary Power Engines S.T. Gonczy (Gateway Materials Technology) Wear-resistant, durable, and insulating ceramic coatings [applied by physical vapor deposition (PVD), chemical vapor deposition(CVD), and thermal spray methods] are a promising technology for improving the durability, reliability, and efficiency of diesel and turbine engines for automotive and industrial power applications. Currently, there are very few widely accepted test standards for evaluating the baseline properties of ceramic coatings for engine applications. The commercialization of ceramic coatings in the engine community is hindered by that shortfall. Recognizing that barrier, the U.S. Dept. of Energy Heavy Vehicle Propulsion Materials Project funded Gateway Materials Technology to conduct a survey on the need for standardized tests for ceramic coatings tests for engine applications. The objectives of the survey were to -- 1) Determine the current or developing needs for standardized test methods for ceramic coatings. 2) Learn what properties, characteristics, and methods are currently appropriate and suitable for test method standardization. 3) Identify interested volunteers for a steering committee for standard tests for ceramic coatings. The survey was sent to over 230 individuals in the engine, ceramic coatings, and research communities in the summer of 2001. With a 10% reply rate, the survey responses covered a wide range of engine components and conditions -- fuel injectors, piston rings, valves, engine heads, gears, wristpins, cylinders, rockers arms, rings, seals, turbine shrouds, fuel & oil environments, injector components, turbine blades, nozzles, shrouds, vanes, & combustion components. Oxides, nitride/carbides, and diamond-like carbon (DLC) were the ceramic compositions of primary interest. The survey results and recommendations are being coordinated with ASTM committees C28, B13, and G02, and additional input is being collected from the engine and coatings community. The steering committee has been established to develop an implementation plan with goals, tasks, priorities, resources, volunteers, and schedules for developing test standards for ceramic coatings. The great majority (80%) of the respondents felt strongly that test standards were needed for ceramic coatings. The primary benefits of those standards would be comparability and accelerated commercialization. The principal challenges and barriers to the development of standards are the complexity of coatings, proprietary issues, and correlations between tests and real performance. The "TOP FOUR" tests that the respondents felt should have priority for standardization are -- adhesion, wear, thermal conductivity, and microstructural analysis. These areas provide a research opportunity for the coatings community to develop and evaluate reliable, universally acceptable coating test methods and guidelines.paragaph * Funded by the Dept. of Energy Heavy Vehicle Propulsion Materials Project