Analysis and Optimization of Electrolytic Jet Plasma Oxidation (EJPO) Coating for Manufacturing of High-Efficiency Automotive Engines

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This partnership, between Ford Canada and the University of British Columbia Okanagan, aims to improve the efficiency and performance of the next generation of automotive engines. The successful completion of this project could help the automotive industry meet the strict governmentally enforced fuel economy target of 54.5 MPG by 2025. To accomplish this goal, it is necessary to investigate new methods of lightweighting the engine and/or developing new manufacturing processes to eliminate known issues that lower or restrict the thermal efficiency of the engine. During the manufacturing process of aluminum (Al) engine blocks, differences in material properties cause a number of harmful issues to develop, including but not limited to the generation of residual stress (i.e. stress that is locked in the material without an external load). These issues weaken the material and are primarily caused by the presence of the iron (Fe) liners that are used in engine blocks to protect the softer Al base material from wear. To alleviate the drawbacks of the Fe liners, manufacturers have begun using wear-resistant coatings instead. Ford was one of the early pioneers to implement a coating process known as plasma transferred wire arc (PTWA). Although it proved its robustness in the 2011 Mustang GT, our pilot study confirmed that the rapid heat transfer that occurs during the PTWA process still leads to the generation of the tensile residual stress of up to 100MPa. Moreover, the poor thermal conductivity of the relatively thick coating results in larger peak cylinder temperatures which lead to a decrease in engine efficiency. Thus, a newer method, electrolytic jet plasma oxidation (EJPO), was developed which has the potential of lowering the accumulation of residual stress by minimizing the thermal gradients produced during its application. Thus, this study aims to characterize the effects that the coating processes have on the residual stress in Ford's new V8 engine block. Moreover, the surface nano-porosity, oil retention, and wear resistance of the new EJPO coating will be examined to determine the feasibility of using EJPO coating for mass production of the new engine.