Molecular Dynamics Simulation Of Lubricant Transfer Between Slider And Bit Patterned Media Disk

With the rapid increase in amount of information and data in daily life and work,hard disk drive,as the main storage device for information and data,has increased its storage capacity increasingly.Mutually separated magnetic islands,as magnetic recording bits,were used in bit patterned media(BPM),which can reduce the magnetic interference between neighboring bits effectively and increase the areal density of magnetic disk greatly.The minimum flying height of slider has been decreased to less than 2 nm in the head/BPM disk interface.In this case,the lubricant on BPM disk will inevitably transfer to the slider,which will affect head flight stability and read/write accuracy.Therefore,investigating the transfer behavior of lubricant in head/BPM disk interface will provide optimized parameters for the design of BPM hard disk drive and increase its reliability and service life.In this study,molecular dynamics simulation method was used to systematically investigate the lubricant transfer behavior and its influencing factors in the head/BPM disk interface.The lubricant transfer law in the head/BPM disk interface was studied by analyzing the transfer amount and distribution of lubricant in non-contact and contact collision of slider and BPM disk respectively.According to the surface topography of BPM disk,the model of Z-Dol PFPF lubricant on the BPM disks was built using the modeling principle of coarse-grained bead spring model.With consideration of the interaction between lubricant and DLC layer and the air bearing pressure distribution characteristics in head/BPM disk interface,the lubricant transfer model in the head/BPM disk interface was established.The microscopic transfer process and distribution changes of lubricant were analyzed using the lubricant transfer model.In non-contact of slider and BPM disk,the law of lubricant transfer and distribution change with chamfer angle of slider,ratio of functional groups in the DLC layer,distance between neighboring bits,type of lubricant molecular,lubricant film thickness,lubricant fragments was revealed.Flying disturbances may occur when the head reads or writes data,the effect of flying height,local air bearing pressure,slider pitch on lubricant transfer and distribution were studied.Contact collision between slider and BPM disk occurs when flying disturbances is severe.Therefore,the lubricant transfer model in contact collision of slider and BPM disk was established,which was used to analyze the lubricant transfer process during the contact collision of slider and BPM disk.In addition,the effect of chamfer angle of slider,type of lubricant molecular,BPM disk parameters,slider pitch on the amount of lubricant transfer were investigated.The result indicated that the impact of contact collision of slider and BPM disk on lubricant transfer and distribution is significant.The effect of chamfer angle of head,type of lubricant molecular,slider pitch on the amount of lubricant transfer is different in the case of non-contact and contact collisions of head and BPM disk.