Effects of electrolytic jet plasma oxidation (EJPO) coatings on thermal behavior of engine cylinders

Aluminum engine blocks with ceramic-coated cylinder bores can effectively reduce the self-weight and largely improve the wear resistance. However, the presence of coatings to some extent also affects the heat transfer of internal combustion (IC) engine between the cylinder and the coolant due to their low thermal conductivities. In this paper, electrolytic jet plasma oxidation (EJPO) coatings were adopted to deposit on the engine cylinder bores. A three-dimensional transient finite element analysis (FEA) thermal model was developed to investigate the thermal behavior of EJPO-coated cylinders. It was found that both coating thickness and thermal conductivity could significantly influence the bore surface temperature and temperature fluctuation behaviors at the different crank angles. A possible selection of the parameter combination of coating thickness and thermal conductivity would provide a newly promising opportunity in the design of a high-quality coating for the cylinder bores to improve IC engine efficiency.