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This research focuses on study of feasibility of using ceramic oxide coatings on the cylinder wall of hypoeutectic aluminum silicon alloy engine blocks. Coatings are achieved in an aqueous electrolytic bath and composed of both alpha and gamma phases of Al2O3 and have shown promising wear resistance. Composition and acidity level of the electrolyte creates a variation of surface roughness, coating hardness and thickness which has direct influence on the wear behavior of the sliding surfaces. The effect of load bearing and coating morphology on coefficient of friction was studied. SEM images of the substrate showed no predominant wear behavior or delamination. Coefficient of friction and wear rate were also measured. This study shows the importance of surface structure on oil retention and wear rate. Coarser coatings can be desirable under starved oil condition since they show lower coefficient of friction.

An extremely tough alumina based ceramic coating produced by a modified anodizing process developed at Moscow Aviation Institute has been evaluated for light weight, wear resistant component applications in automotive powertrain. The process details and test results from comparative evaluation of friction and wear properties for cylinder bore application, referenced to cast iron baseline, are presented and discussed.

Application process, and performance in engine dynamometer and high mileage vehicle fleet durability tests of Plasmaspray coated bore aluminum block engines are discussed. Fuel economy, oil consumption, power and wear data for Ford 4.6L-V8 aluminum block engines utilizing very low cost iron/iron oxide base coatings, and stainless steel/BN solid film lubricant Plasmasprayed coatings are presented. Test results from Ford's 100 hour Piston & Gasket Engine Dynamometer Durability Tests, and Fleet Vehicle Durability Tests show ring/bore wear reductions of more than 40% relative to production cast iron bore systems with Oil Economy averaging more than 13,600 km/l (8000 mi/qt).

The semantic differential (SD) method was used to characterize the size and shape of burrs created under various cutting conditions, drill size, tool geometry and coatings. Human subjects visually rated the burr using a SD evaluation form. Significant differences were found in tool type and feed rate. A high performance drill with titanium-nitride coating and a high depth/diameter ratio, yielded minimum burr. A lower feed rate resulted in less burr formation in the majority of the cases. Three primary factors emerged, and accounted for 83% of the variances. Factor scores were mapped into the SD space to show the effect of treatments.

The recent inclusion of painted plastic fascias/bumpers into automotive applications has necessitated the evaluation of potential in-service damagability. One failure mode that has been identified, that of friction-induced paint/substrate damage, has been simulated in a laboratory environment. Our goal was to evaluate the effects of coating attributes, both thermal and mechanical, on subsequent performance of painted thermoplastic olefin (TPO) materials. It was determined that the most significant parameters in the paint which contributed to damage were the glass transition temperature, the secant modulus at break, and the static coefficient of friction. This paper will discuss techniques and results used to reach these findings.

Painting is the most difficult, the most costly, and the most polluting step in manufacturing vehicles. When low weathering performance paints are used, the results are dissatisfied customers, and huge warranty costs. It would obviously be wise to fully characterize the weathering performance of new coatings systems before they are used. Unfortunately this is not always practical. Coating formulations are changing rapidly in the States to comply with solvent emission regulations, the introduction of plastic substrates, and customer tastes. There is rarely enough time to wait ten years for outdoors exposure tests to reveal the "true" weathering performance of coatings before marketing vehicles. As a result, accelerated tests are often used to guide decisions. However, the results of such tests can be misleading because the harsh exposure conditions used can distort the chemistry of degradation.

This report presents results of experiments to determine the effect of elevated temperature exposures on the mechanical properties of aluminum alloy materials. The two alloys studied, 5754 and 6111, are of the types which would be used in a stamped automobile structure and exterior panels. Yield strength, tensile strength, and total elongation are reported for a variety of test conditions. The material temperature exposures simulated a broad range of conditions which might be experienced during manufacturing operations such as adhesive curing and vehicle paint bake cycles. In addition, tests were conducted at temperatures to resemble in-service under-hood and under body (near the exhaust system) conditions. Materials were prestrained various amounts prior to temperature exposure to simulate metal forming processes. Results show that both materials react to temperature and aging times differently.

The presence of a foreign substance on or within a polymer often affects the mechanical, chemical and thermal properties of the material. The change in strength and rigidity of a polymer resulting from the plasticizing action of a sorbed chemical or due to the withdrawal of an added plasticizer by the leaching operation can seriously affect the useful life of the material. In the real engineering world, incompatible chemicals and lubricants get onto various plastic components unexpectedly through design, manufacturing processes, customers services and repairs. This paper presents a number of case-studies which illustrate how undesirable chemicals found on plastic parts can affect product performance and cause damage to the parts.

Erosion damage to automotive car bodies caused by stones and small sand particles and road debris significantly affects the appearance of paint. Painted engineering plastics as well as precoated sheet steel are affected by erosion phenomenon. Erosion of painted plastic substrates results in cosmetic concerns while that on metal substrates results in cosmetic to perforation corrosion. This work describes a laboratory simulation of erosion of painted plastic substrates by small particles on various paint and substrate types. Gloss loss was used to quantitatively evaluate erosion of painted surfaces. Wear behavior of painted plastic substrates to slag sand impact was evaluated as a function of several variables including paint type (one-component melamine crosslinked (1K) vs. two-component isocyanate crosslinked (2K)), thermal history, and coating modulus. The effect of slag sand type (particle size and chemical composition) was studied.

A hydrocarbon trapping system for cold start emissions was constructed and tested using two types of carbonaceous adsorbents provided by Corning, Inc. One was made by combining activated carbon with an organic binder and extruding it into a honeycomb, and the other by depositing a carbon coating on a ceramic monolith. The tests were carried out on an engine in a dynamometer laboratory to characterize the performance of the carbon elements under transient cold start conditions. Performance was evaluated by continuously measuring exhaust gas hydrocarbon concentrations upstream and downstream of the trap, using conventional emissions consoles. Samples were also collected for off-line analysis of individual hydrocarbon species using gas chromatography to examine differences in adsorption of individual species. The speciated hydrocarbon data were used to distinguish between the mass trapping efficiency and a reactivity-based trapping efficiency of the adsorbant traps.

A 1.8L turbocharged diesel engine valvetrain friction was investigated, and the effectiveness of using a solid film lubricant (SFL) coating in reducing friction was determined throughout the operable speed range. This valvetrain design features direct acting mechanical bucket valve lifters. Camshaft journal bearing surfaces and all camshaft rubbing surfaces except lobe tips were coated. The direct acting bucket shims were etched with a cross hatch pattern to a depth sufficient to sustain a SFL film coating on the shim rubbing surfaces subjected to high surface loads. The SFL coated valvetrain torque was evaluated and compared with uncoated baseline torque. Coating the cam bearing journal surfaces alone with II-25D SFL reduced valvetrain friction losses 8 to 17% for 250 to 2000 rpm cam speed range (i.e. 500 - 4000 rpm engine speed). When bucket tappet and shims were also coated with the SFL, further significant reductions in coated valvetrain friction were observed.

For an automotive exhaust system, analytical evaluation of coatings, dual wall, multiwall, and blanket insulation methods indicated that the blanket insulation provided the best method for heat containment. An experimental vehicle was tested with and without a blanket insulation on the exhaust system over a demanding heat protection cycle. The exhaust gas, pipe wall, surrounding air, and adjacent component temperatures at 25 locations along the pipe are reported indicating reduced outer wall temperatures and good containment of the heat. A comparison of the heat lost through the exhaust system walls is presented.

Serious pitfalls exist in assuming that aluminum can be reliably resistance spot welded in the “as received” mill finish or even in the chemically cleaned condition. A commercially feasible surface abrading process was developed to promote reliability with existing tooling even 90 days afterwards. A weld reliability procedure was developed to evaluate process variables, various surface treatments, electrode materials and geometry. Comparative merits of AC and DC power were investigated. With the advent of abraded surfaces, aluminum can now be resistance spot welded with confidence and the dreaded fast electrode fauling condition associated with mill finish surfaces can be substantially alleviated.

PROPER protection of metal parts operating as bearing surfaces, or in contact under relatively heavy loads, during the break-in period often means the difference between successful operation and failure. Various surface coatings have been investigated to discover which ones will give this protection. The authors discuss here three types of surface treatment for cast-iron and steel that do give superior wear and scuff resistance.