Development of thin films on metallic surface for friction reduction in fuel injection system.
Thin films, DLC, MoS2, magnetron sputtering, biodiesel S-10, tribology.
In a large part of the mechanical equipment, there is a relative movement between its components which induces plastic deformation, that may occur as a result of the frictional forces generated during the operation of the equipment. This work aims to study thin film coating, investigating the application of molybdenum disulphide (MoS2) and DLC on metal substrate surface, SAE 1045 steel discs, looking for it as a possible alternative for the application of these films in automotive components limited by liquid lubricant, biodiesel, I which there is a need for a combination of high wear resistance and low coefficient of friction. The application of the films was performed with the aid of the plasma deposition, through the magnetron sputering technique, in three different combinations, based on the multilayer technique, intercalating the MoS2 with the DLC, maintaining the composition of the target and substrate. To evaluate the performance of these treatments, a tribological work bench was developed, a cylinder-on-disk tribometer, in which the objects of study were in contact with a camshaft, immersed in a fluid (S-10 biodiesel), analogously to what occurs during operation of some elements of the common rail injection system. Besides to the bench tests, morphological aspects were evaluated in an evolutionary scale, through MEV, EDS and mass loss, roughness, AFM, microhardness and uniformity, as a function of the deposition of combined films of MoS2 and DLC, contained on the surface of the discs during the tests. Along the experiments, the physicochemical aspects of fuel lubrication, such as sulfur content, acidity index, FTIR, FRX and LECA, were characterized.