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Journal Article

Investigation into Mixed and Hydrodynamic Frictions of PEO Coatings and Cast Iron

A linerless aluminum (Al) engine block has potential to reduce the weight of an automotive engine and improve the fuel economy. However, the Al cylinder surface of an aluminum engine block is not usually strong enough to withstand the sliding wear against piston rings. A few surface processing technologies are used to protect the surface of cylinders. Among them, a thermal spraying coating, such as plasma transferred wire arc (PTWA) is already popular. Plasma electrolytic oxidation (PEO) coating is also proposed for increasing the wear resistance of aluminum-silicon (Al-Si) alloys and reducing the friction between the cylinder and piston. In this work, two different PEO coatings with a thickness of around 23 μm were prepared on an Al-Si alloy A356, and a high speed pin-on-disc tribometer was used to study the tribological behavior of the coatings at oil lubricant conditions. A cast iron sample was also used to do similar tribological tests for comparison.
Technical Paper

Outside-Engine Wear Study of Ceramic Coated Cylinder Wall Tribo-System

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.
Journal Article

Fusion Welding of Vacuum High Pressure Die Cast Aluminum Alloy A356 and Wrought Alloy 6061

Recently, joining of cast aluminum components with wrought and/or cast similar metals becomes an urgent task for the auto industry to develop light-weight complex and large-scale chassis and body structures for further reduction in vehicle weight. In this study, fusion-joining of vacuum high pressure die cast (VHPDC) alloy A356 subjected to T5 heat treatment and wrought alloy 6061 with the Gas Metal Arc Welding (GMAW-MIG) process was experimented in an effort to understand the effect of the MIG process on the microstructure development and tensile behaviors of the base alloys (T5 A356 and 6061), Heat Affected Zone (HAZ) and Fusion Zone (filler metal ER4043). The results of tensile testing indicated that the ultimate tensile strength (UTS), yield strength (YS) and elongation (Ef) of VHPDC T5 A356 were relatively high, compared to both wrought alloy 6061 and the filler metal (ER 4043).
Technical Paper

Vehicle Recycling, Reuse, and Recovery: Material Disposition from Current End-of-Life Vehicles

The goal of this research was to determine and quantify today's actual end-of-life vehicle disposition rates based on their age and material content. The current facts and status of today's automotive recycling industry were sought. Disposition rates and material trends were projected using adjusted ELV age data from Duranceau and Linden's 1999 research and average materials content data from open-sources. End-of-life vehicle age and population data adjustments were used to estimate representative material compositions for the US and Canadian ELV fleet. The disposition rates were broken down by percentages of (1) part weight reused, (2) part weight remanufactured, (3) part weight recycled pre-shredder, (4) weight of recovered fluids, and (5) weight of metals recycled post shredder. The 86.3% percent material recovery established in this study was compared to the 84% reported in Paul's 2001.
Technical Paper

Steel Reinforced Pultruded GFRP Vehicle Chassis Structure

A finite element model was developed to assess the mechanical behaviour of pultruded glass fibre reinforced polymer (GFRP) box sections with embedded steel rods; the performance of these virtual specimens was compared with that of extruded aluminium sections with comparable dimensions. All specimens were tested in transverse loading and in torsion. A parametric study was carried out in order to optimize the stiffness of the GFRP-steel hybrid specimens. It was found that the modes of deformation exhibited by the GFRP-steel hybrid specimens were highly tunable. The hybrid members had sufficient bending stiffness when compared with equivalent extruded aluminium members; however, the technology will likely require further development to ensure adequate shear stiffness.
Journal Article

Wear Protection of Al383/SiO2 Metal Matrix Composites by Plasma Electrolytic Oxidation (PEO) Process

Al383/SiO₂ metal matrix composites (MMC) were designed to increase the wear properties of the Al alloy. However, the soft Al matrix was subject to large plastic deformation under high normal load during lubricated sliding wear tests, causing detachment of the reinforced particles. To further increase the wear resistance of the MMC, in this research, Plasma Electrolytic Oxidation (PEO) process was used to form oxide coatings on the MMC. The hard and wear-resistant oxide coatings protected the metal matrix during the wear tests, reducing the wear rate of MMC. The effect of both oxide coating thickness and volume content of SiO₂ particles on the wear behavior of MMC was investigated. It was found that with a proper combination of the volume content of SiO₂ and coating thickness, the MMC exhibited high wear resistance and low friction coefficient.
Journal Article

An Experimental Study Investigating the Influence of the Number of Blades in a Cutter Used in Axial Cutting of AA6061-T6 and T4 Round Tubes

Quasi-static axial cutting of AA6061-T6 and T4 round extrusions were completed using a specially designed cutter with multiple blades. The round specimens had a length of 200 mm, a nominal outer diameter of 50.8 mm, and a wall thickness of 3.175 mm or 1.587 mm. Four different cutters, constructed from heat-treated 4140 steel, having 3, 4, 5 and 6 blades on each cutter with a nominal tip width of 1.0 mm were used to penetrate through the round extrusions. A clean cutting mode was observed for the AA6061-T6 and T4 extrusions with wall thickness of 3.175 mm with an almost constant steady state cutting force. A braided cutting mode was observed for extrusions with both tempers with wall thickness of 1.587 mm, which resulted in a slightly oscillating steady state cutting force. For all extrusions with a wall thickness of 3.175 mm, the steady state cutting force increased with an increase in the number of cutter blades.
Technical Paper

Development of Hybrid Magnesium-based Composites

In the past decade, magnesium (aluminum) alloy use in the automotive industry has increased in order to reduce vehicle weight and fuel consumption. However, their applications are usually limited to temperatures of up to 120°C. Improvements in the high-temperature mechanical properties of magnesium alloys would greatly expand their industrial applications. As compared to the unreinforced monolithic metal, metal matrix composites have been recognized to possess superior mechanical properties, such as high elastic modulus and strengths as well as enhanced wear resistance. In this study, a novel approach of making hybrid preforms with two or more types reinforcements, i.e., different size particles and fibers, for magnesium-based composites was developed. An advanced and affordable technique of fabricating hybrid magnesium-based composites called the preform-squeeze casting was employed successfully.
Technical Paper

Microstructure Influence on the Corrosion of Permanent Mould Cast Magnesium Alloy AJ62 in Engine Coolant

Powertrain applications of alloy AJ62 arose from its comparative resistance to high temperature deformation among magnesium alloys. In this research, AJ62 permanent-mould cast in different section thicknesses was subjected to immersion corrosion in commercially-available engine coolant. The objective was to determine corrosion behaviour variation among casting thicknesses. Corrosion product accumulation suggests passive film formation, and unlike in other media, the film exhibits certain stability. Extreme thicknesses were used to generate polarization curves for their respective microstructures in engine coolant. Variation with casting section thickness was observed in the curves. These preliminary results indicate coarsened microstructures reduce corrosion resistance of the permanent mold cast AJ62 alloy.