The characteristics of lubricant film at head/disk interface （HDI） are essential to the stability of hard disk drives. In this study, the theoretical models of the lubricant flow and depletion are deduced based on N...The characteristics of lubricant film at head/disk interface （HDI） are essential to the stability of hard disk drives. In this study, the theoretical models of the lubricant flow and depletion are deduced based on Navier-Stokes （NS） and continuity equations. The air bearing pressure on the surface of the lubrication film is solved by the modified Reynolds equation based on Fukui and Kaneko （FK） model. Then the lubricant film deformations for a plane slider and double-track slider are obtained. The equation of lubricant film thickness is deduced with the consideration of van der Waals force, the air bearing pressure, the surface tension, and the external stresses. The lubricant depletion under heat source is simulated and the effects of different working conditions including initial thickness, flying height and the speed of the disk on lubricant depletion are discussed. The main factors that cause the lubricant flow and depletion are analyzed and the ways to reduce the film thickness deformation are proposed. The simulation results indicate that the shearing stress is the most important factor that causes the thickness deformation and other terms listed in the equation have little influence. The thickness deformation is dependent on the working parameter, and the thermal condition evaporation is the most important factor.展开更多
The microhardness and modulus changes of the interface between U-0.75Ti alloy and TiC before andafter heat treatment were studied by SEM and Nano Indenter II, and the results show that the hardness and modulusof the i...The microhardness and modulus changes of the interface between U-0.75Ti alloy and TiC before andafter heat treatment were studied by SEM and Nano Indenter II, and the results show that the hardness and modulusof the interface are greatly increased after 820℃, 2 h water quenching and 450℃, 6 h aging. This result probablycomes from much more U2Ti and U6Ni precipitates along the interface.展开更多
This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engin...This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engineering appilcations of these technologies in magnetic disk drives.展开更多
Stable lubrication is essential to slider/disk interface of computer hard disk drive. Inert lubricant perfluoropolyether (PFPE) on magnetic hard disk in computer is still prone to catalytic decomposition by Al_2O_3, w...Stable lubrication is essential to slider/disk interface of computer hard disk drive. Inert lubricant perfluoropolyether (PFPE) on magnetic hard disk in computer is still prone to catalytic decomposition by Al_2O_3, which is one of the materials in slider. A partial fluorinated hexaphenoxy cyclotriphosphazene chemical, X-1 P, was analyzed to research on its function to reduce the cata- lytic decomposition of lubricant. The surface free energy of X-1 P coated on head surface was also investigated. Contact start-stop (CSS) tester was employed to investigate the reflow effective of X-1 P on lubricant PFPE. Results indicate that thermal stability and reflow of lubricant will be im- proved in the presence of X-1 P on the slider.展开更多
Lubricant transfer and distribution at the head/disk interface in air-helium gas mixtures is investigated using a developed model that combines an air-bearing model with a molecular dynamics model. The pressure distri...Lubricant transfer and distribution at the head/disk interface in air-helium gas mixtures is investigated using a developed model that combines an air-bearing model with a molecular dynamics model. The pressure distribution is calculated by the air-bearing model at the head/disk interface with respect to the helium content and the pressure obtained is then input to the molecular dynamics model to understand the lubricant transfer mechanism. Finally, the effects of pressure at the boundary condition and disk velocity on lubricant transfer are discussed in relation to the helium fraction within the air-helium gas mixtures. Results show there is a decrease in the pressure difference with an increase in the helium percentage, which leads to a decrease in the volume of the lubricant transferred. The results also suggest that the lubricant is not easily to transfer in gas mixtures with a high percentage of helium, even when both higher disk velocities and pressure boundary conditions are applied.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51275124)
文摘The characteristics of lubricant film at head/disk interface （HDI） are essential to the stability of hard disk drives. In this study, the theoretical models of the lubricant flow and depletion are deduced based on Navier-Stokes （NS） and continuity equations. The air bearing pressure on the surface of the lubrication film is solved by the modified Reynolds equation based on Fukui and Kaneko （FK） model. Then the lubricant film deformations for a plane slider and double-track slider are obtained. The equation of lubricant film thickness is deduced with the consideration of van der Waals force, the air bearing pressure, the surface tension, and the external stresses. The lubricant depletion under heat source is simulated and the effects of different working conditions including initial thickness, flying height and the speed of the disk on lubricant depletion are discussed. The main factors that cause the lubricant flow and depletion are analyzed and the ways to reduce the film thickness deformation are proposed. The simulation results indicate that the shearing stress is the most important factor that causes the thickness deformation and other terms listed in the equation have little influence. The thickness deformation is dependent on the working parameter, and the thermal condition evaporation is the most important factor.
文摘The microhardness and modulus changes of the interface between U-0.75Ti alloy and TiC before andafter heat treatment were studied by SEM and Nano Indenter II, and the results show that the hardness and modulusof the interface are greatly increased after 820℃, 2 h water quenching and 450℃, 6 h aging. This result probablycomes from much more U2Ti and U6Ni precipitates along the interface.
文摘This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engineering appilcations of these technologies in magnetic disk drives.
文摘Stable lubrication is essential to slider/disk interface of computer hard disk drive. Inert lubricant perfluoropolyether (PFPE) on magnetic hard disk in computer is still prone to catalytic decomposition by Al_2O_3, which is one of the materials in slider. A partial fluorinated hexaphenoxy cyclotriphosphazene chemical, X-1 P, was analyzed to research on its function to reduce the cata- lytic decomposition of lubricant. The surface free energy of X-1 P coated on head surface was also investigated. Contact start-stop (CSS) tester was employed to investigate the reflow effective of X-1 P on lubricant PFPE. Results indicate that thermal stability and reflow of lubricant will be im- proved in the presence of X-1 P on the slider.
基金supported by the National Natural Science Foundation of China (51505093, 51605113)the Young Talents Project of Education Department of Guizhou Province (KY[2016]116)+1 种基金the Science and Technology Project of Guizhou Province ([2016]1035)the Science and Technology Innovation Project for Overseas Scholars of Guizhou Province
文摘Lubricant transfer and distribution at the head/disk interface in air-helium gas mixtures is investigated using a developed model that combines an air-bearing model with a molecular dynamics model. The pressure distribution is calculated by the air-bearing model at the head/disk interface with respect to the helium content and the pressure obtained is then input to the molecular dynamics model to understand the lubricant transfer mechanism. Finally, the effects of pressure at the boundary condition and disk velocity on lubricant transfer are discussed in relation to the helium fraction within the air-helium gas mixtures. Results show there is a decrease in the pressure difference with an increase in the helium percentage, which leads to a decrease in the volume of the lubricant transferred. The results also suggest that the lubricant is not easily to transfer in gas mixtures with a high percentage of helium, even when both higher disk velocities and pressure boundary conditions are applied.
