Molecular Dynamics Simulation Of Wettability Of Alkane And Fatty Acid Ester Nano-droplets On Solid Surface

The wettability of the solid-liquid interface is a basic scientific issue in the fields of energy,chemical,biological and other fields.It plays an important role in the research of applied technology in printing,refrigeration,agriculture,machinery and other industries.For all kinds of mechanical equipment containing moving parts,the use of lubricating oil can minimize the wear of the moving mechanism and prolong the service life of the equipment.At present,lubricating oil has been widely used in various mechanical equipment such as engines,gears,bearings,etc.Research on the mechanism of lubricating oil can provide support for its engineering application.The performance of lubricating oil is determined by its viscosity,flash point,viscosity-temperature performance,wettability and other properties.Among them,solid-liquid wettability is the basis of lubrication mechanism research and is currently one of the hot spots in lubricating oil research.Lubricating oil is mainly composed of base oil and additives,base oil is the main component of lubricating oil and determines its basic properties.The base oils mainly include mineral base oils,synthetic base oils,and vegetable base oils,considering that these systems are all complex mixtures,this article selects normal alkanes,isoparaffins and fatty acid lipids as substitutes,and uses molecular dynamics simulations.The research method is to study the wetting characteristics of these substitute lubricant molecules at the solid interface of aluminum and iron.It mainly includes the following research contents:1.The wetting characteristics of three n-alkane nanodroplets of n-dodecane,n-tetradecane and n-hexadecane on the surface of aluminum substrate were studied.It is found that the average one-dimensional density of the three droplets is basically consistent with the literature value;the contact angles of the three nano-droplets on the smooth and rough surfaces of the aluminum substrate are obtained,and the law of the contact angle changes with the roughness factor r and the surface fraction f of the rough surface is analyzed.2.Three isoalkane lubricating oil systems of 2-methyloctadecane,2-methyldocosane and 2,6,10,15,19,23-hexamethyltetradecane are studied in iron Wetting properties of the substrate.It is found that as the temperature increases,the contact angles of the three nano-droplets on smooth and rough surfaces show a decreasing trend;the Cassie or Wenzel wetting modes of three nano-droplets on the rough surface with different energy potential parameters εs are obtained.3.The infiltration characteristics of three vegetable lubricating base oil systems,ethyl myristate,ethyl palmitate,and ethyl oleate,on the surface of iron substrates were studied.The law of contact angle,spreading radius,position of center of mass,and solid-liquid interaction energy of smooth and rough surfaces over time was obtained.