This study reports the influence of CVD-graphene on the tribological performance of gray cast iron (GCI) from the internal combustion engine (ICE) cylinder liners by performing a ball-on-disk friction tests. The graphene-coated specimen exhibited a significant reduction (∼53%) of friction as compared to that of the uncoated specimen, whereas wear resistance increased by 2- and 5-fold regarding the wear of specimen and ball, respectively. Extremely low shear strength and highly lubricating nature of graphene contribute to the formation of a lubricative film between the sliding surfaces and decreases the interaction between surfaces in the dry environment. Under the applied load, a uniform film of iron oxides such as FeO, FeO, and FeOOH is found to be formed between the surfaces. It is proposed that the graphene encapsulation with the metal debris and oxides formed between the specimens increases the lubricity and decreases the shear force. The transformation of graphene/graphite into nanocrystalline graphites across the contact interfaces following the amorphization trajectory further increases the lubricity of the film that ultimately reduces friction and wear of the material.
Dimples with various pitches and densities were produced using laser surface texturing (LST) to improve the friction and wear behavior of graphite cast iron. The objective of this study is to investigate the effectiveness of dimples on the friction and wear behavior of an internal combustion engine (ICE) cylinder. The specimens with a dimple pitch of 150 μm and a dimple density of 13% exhibited the lowest friction coefficient among the specimens, while the specimens with a dimple pitch of 200 μm and a density of 7% exhibited the highest resistance to wear.
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