Molecular Dynamics Simulation for Lubricant Shear Properties During Heating

This paper discusses the shear properties of ultra-thin lubricant film on hard disk media during heating. A molecular dynamics method is used on four different types of lubricant to better understand the phenomena on the atomic scale. We investigate the shear mobility of lubricant for each temperature between 30°C and 300°C, assuming there is an air shear-induced migration on a carbon overcoat. The simulation results show that a thick lubricant film has a mobile and restricted layer, while a thin film which thickness is less than 1 nm , increases the slippage at lubricant/overcoat interface. At a high temperature, a lubricant with a flexible main chain tends to have a higher level of mobility. The difference in lubricant shear property is closely related to the flexibility of main chain and the amount of functional groups of lubricant which can affect the shear viscosity and adhesion to the carbon overcoat.