Preparation And Tribological Performance Of Graphene@Ferrocene With Microscopic Bionic Non-Smooth Surface

An engine is the heart of an automobile,playing a crucial role in a car,and usually requires engine oil for its normal operation.Thus,the lubrication performance of engine oil is important to the life and efficiency of an engine.In recent years,engine oil additives have been widely used as an effective measure to improve the lubrication afforded by engine oil and engines' efficiency.To date,there are various kinds of engine oil additives reported,but most of them contain phosphorus or sulfur.An engine oil additive of high lubrication and environment-friendliness is still rare.Non-smooth surface,also called textured surface,is common in nature.Indeed,many global researchers and engineers have investigated the characteristics of typical non-smooth surfaces observed in animals and plants.A simple description of the concept of bionic non-smooth surface is a bulk smooth surface functionalized with at least one factor that can cause non-smooth effect.It has been demonstrated at macroscopic level that products with bionic non-smooth surface,such as bionic non-smooth plough,bionic non-smooth cylinder,etc.,can reduce friction and wearing,thus leading to higher efficiency.Yet,the fabrication and application of bionic non-smooth surface at microscopic level is still lacking.Based on previous research of macroscopic bionic non-smooth surface,a microscopic bionic non-smooth surface at nanoscale has been designed in this work,which is composed of graphene and ferrocene.Graphene is a special two-dimensional nanosheet material with high mechanical strength and good thermal conductivity,which is also the structural unit of carbon-based solid lubricants.Ferrocene,one of the first discovered sandwich complexes,has a molecular structure with an iron atom sandwiched between two parallel cyclopentadiene rings.It has been envisioned that the ?-? stacking interaction between graphene and ferrocene can anchor ferrocene onto graphene nanosheets to yield the nanocomposite of graphene@ferrocene(G@Fc).The introduction of ferrocene can presumably decrease the contact area of graphene nanosheets at micro-level during rubbing,thus reducing fiction and enhancing lubrication.In this thesis,the nanocomposite of G@Fc has been prepared by sonication and characterized by a series of measurements,including scanning electron microscopy,infrared spectrum,Raman spectrum,ultraviolet visible spectrum,X-ray photoelectron spectroscopy,and X-ray diffraction.Then the as-prepared G@Fc nanocomposite has been added to engine oil and compared in pin-on-disc experiments together with three control samples,i.e.ferrocene alone,graphene alone,and graphene physically mixed with ferrocene.It is found that G@Fc results in better frictional properties than control groups under lubricated condition.Subsequently,the effects of the weight percentage of ferrocene in G@Fc and the supplemental amount of the nanocomposite in engine oil on lubrication performance have been investigated.Given the fixed amount of graphene added,the optimal weight percentage of ferrocene in G@Fc is determined as 20 wt%,whereas the ideal supplemental amount of G@Fc is estimated as 0.4 g/L in engine oil.In order to test the additives under a condition close to real working condition,two devices have been designed and set up: a platform to test engine performance and a device to measure gasoline consumption.The testing platform of engine performance can assess the durability,power output,torque,temperature and other parameters of an engine under different loads.The measurement device is able to determine the gasoline consumption in a quick and low-cost manner with a system error less than 5%.Last,the nanocomposite of G@Fc has been tested in an experiment conducted with the above two devices,which indicates that the G@Fc additive with microscopic bionic non-smooth surface can reduce gasoline consumption to a certain extent.The work presented herein affords a new approach base on microscopic bionic non-smooth surface to the development of engine oil additives of high lubrication and environment-friendliness.