An Investigation of the Microstructure and Oil Retention of Electrolyte Jet Plasma Oxidation (EJPO) Coating

Next-generation automotive engines demand new materials and technologies to meet efficiency mandates regarding energy conservation and emission reduction. Replacing heavy ferrous metals with lightweight aluminum (Al) alloys can considerably improve fuel efficiencies in the transportation sector. However, most Al alloys suffer from poor tribological characteristics, which urged original equipment manufacturers to develop advanced materials for high friction applications like cylinder blocks. Recently, there has been a growing trend to produce coatings with high-temperatureHigh-Temperature material strength and wear resistance. These coatings are deposited on an Al substrate of linerless engine blocks using various technologies, including Electrolytic Jet Plasma Oxidation (EJPO). The present study investigates the coating’s microstructure, surfaceSurface modification and coating roughness, and oil retention and compares the latter with the oil retention of the Plasma Transferred Wire Arc (PTWA) coating which is currently used in cylinder block applications. The results revealed higher roughness (Ra = 0.86 µm) and oil retention (V0 = 0.356 μm3/μm2) of the EJPO coating than the PTWA one (Ra = 0.34 µm, V0 = 0.041 μm3/μm2).