Molecular dynamics simulation of friction coefficient of Fe-Al during lubrication

Abstract

Reducing wear and friction coefficient in the process of metal plate processing can save energy. In this work, the quantum chemical parameters of n-hexadecane, tetradecyl alcohol, triphenyl thiophosphate (T309) and dialkyl dithiophosphate (EAK) and the adsorption process on Al (111) plane were calculated based on density functional theory. The confined shear process of the lubricant system mixed with the above four molecules in Fe-Al system was simulated by molecular dynamics method, and the friction coefficient of the lubricant was calculated. The friction coefficients of lubricants were measured by reciprocating friction and wear test. The results show that T309 has the strongest reactivity and the most stable adsorption, and its adsorption energy on Al (111) plane is −12.08 eV. Shear force will affect the adsorption morphology of molecules, and long chain molecules will have a certain degree of crimp. When the pressure was 0.5 GPa, the minimum friction coefficient of lubricant was 0.24, mainly because the molecules would gather and adsorb to the metal wall during the shear process. With the increase of pressure perpendicular to the shear plane, the lubricant molecules on the metal wall would gather less, and the distribution of lubricant molecules between the metal walls was gradually uniform. The tested minimum friction coefficient (∼0.12) of the compound lubricant is attributed to synergistic friction reduction among molecules. Based on molecular dynamics simulation, the friction coefficient of aluminum lubricants can be predicted, and the simulated data are accurate and reliable.