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).

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.

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.

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