Investigation Of Mechanical Behavior Of DLC Coating In The Contact Process Between Slider And Disk

The magnetic storage technology has been intensively studied and employedover the past few years due to its economy, safety and capacity. The hard disk,which consists of the slider and the disk, is the most typical application of themagnetic storage technology. In order to increase the storage capacity, the flyingheight between the slider and the disk has decrease to nanoscale, which may lead tothe transient contact between the slider and the disk subjecting to external shocks.During the transient contact, the diamond-like carbon (DLC) coatings of the sliderand the disk, which are employed as protective coatings against wear and corrosion,are brought into a complex contact process, including interference, friction andscratching. The Hertz elastic solution can be used to describe the contact behaviorfor a sphere in contact with a flat. As the dimension decreases to a nanoscale, theeffect of the adhesion cannot be neglected during the indentation process. Besides,a lot of work has been done on investigating the contact behavior by using finiteelement method (FEM), which is not suitable to investigate the mechanical andtribological properties of the DLC films in nanoscale. In this paper, the theoreticalmethod, FEM method, and molecular dynamics method were combined toinvestigate mechanical behavior of DLC coating in the contact process betweenslider and disk. The main content of this paper includes:A theoretical model of the transient contact between the slider and the disk wasdeveloped. This theoretical model modified the traditional Hertz solution by addingthe effect of the layer disk and the adhesion. Besides, a finite element model oftransient contact between the slider and the disk was developed to investigate thedistribution of the force field and thermal field. The simulated results were broughtinto comparison with the calculated results. The effects of the mechanical andtribological properties of the DLC coating on the transient contact process wereinvestigated.The molecular dynamics (MD) simulation was used to simulate the liquidquenching process to model the amorphous carbon. The effect of the selection ofthe empirical potentials and the quenching time on the sp3content and themicrostructure of the DLC films were investigated. The compression and thetension process were simulated by MD method to investigate the mechanicalproperties of the amorphous carbon.A nanoscale friction molecular dynamics model was developed to investigatethe nanotribological properties of DLC films. The effects of the sp3content, microstructure, doped element, and friction condition on the tribological propertieswere investigated. In nanoscale, the adhesive effect was found to be of greatimportance in the friction process. An effective method, i.e., increasing the sp3content and doping hydrogen, was provided to reduce the adhesive effect.