Theory Research On Sliders And Disks Contact Collision Process On The Microscale

Extremely smooth surface, ultra-low flying heights and high density will be the future hard disk development trend with the rapid development of computer technology. The high density disk gap will drop to 5nm below, even will develop the touch head-disk system. It can't be neglected that interface forces and surface roughness affect the head-disk systems on the microscale.The amended Hamaker constant is adopted and the molecular interaction formula in the head/disk interface is derived in this paper. Then, taking a double-track slider and an advanced step slider (ASS) as examples, numerical integration method is adopted to study the effect of lubricating layer on intermolecular forces. Finally, the finite volume method is used to calculate the air bearing force for the wedge-type slider. The relationship of total air bearing force including intermolecular force considering lubricating layer and minimum flying height is studied. It is found that the lubricating layer can significantly reduce the intermolecular force when the thickness of the lubricating layer is less than 1nm. The reduction of intermolecular force is slow by continuing to increase the lubricating layer thickness when lubricating layer is thicker than 2nm. It is found that the total air bearing force is greatly affected by lubricating layer thickness when the slider flying height is less than 2nm.When the collision happen between slider and disk, surface roughness have a certain effect on its contact collision characteristics, so based on statistical contact models, the rough surface heights follow a Weibull distribution or a Guass distribution. First, following KE model, the interface forces corresponded to above two distributions including the contact force, adhesion force and maximum static friction force have been calculated. Second, through calculation interface forces of different cases rough surfaces, it has found that the effect of the roughness on interface forces is significant. Finally, It has discussed that the effect of the skewness, plasticity index and energy of adhesion on static friction coefficient, It has been found that the static friction coefficient corresponding to positive skewness is small than that of negative skewness with the same applied force. The more plasticity index, the smaller static friction coefficient. More cleaner interfaces have higher energy of adhesion, and its static friction coefficient has a higher values.Additionally, the simplified collision model between slider and disk has been proposed in the present paper, discussed the assumption that the collision model have to follow conditions, and stress of the model is analyzed and calculated. First of all, it is researched that the variation of the slider's maximum displacement, maximum contact radius and maximum contact stress with sphere radius and the impact velocity, it is found that the higher impact velocity and the smaller sphere radius, the interface has became more easily failure. Second, based on the magnetic thin-film disk configuration, the effect of the disk layer thickness on impact variables has been studied, it is found that its effect is modest. However, the collision characteristics is mainly affected by the influence of disk substrate. Ultimately, a single non-dimensional parameter has been introduced to gauge the influence of surface roughness on the impact. It is found that when the roughness becomes larger, the impact influence is larger. Before the surface plastic deformation, roughness can effectively slowed contact collision severity.