Simultaneous measurement of pin wear and change in lubricant thickness on thin-film magnetic disks

1997 ◽  
Vol 33 (6) ◽  
pp. 4560-4565 ◽  
Author(s):  
M. Ishii ◽  
Y. Kawakubo
Keyword(s):  
Thin Film ◽  
Simultaneous Measurement ◽  
Lubricant Thickness ◽  
Magnetic Disks

Tribological implications of solvents in dip-coating lubrication of thin film magnetic disks

1996 ◽  
Vol 32 (5) ◽  
pp. 3699-3701 ◽  
Author(s):  
C. Gao ◽  
Y.C. Lee ◽  
J. Chao ◽  
M. Russak
Keyword(s):  
Thin Film ◽  
Dip Coating ◽  
Magnetic Disks

Dynamic Indentation Characteristics of Spherical Sliders Colliding With Stationary Magnetic Disks With a Thin Lubricant Layer

2007 ◽  
Author(s):  
Kyosuke Ono ◽  
Kenji Nakagawa
Keyword(s):  
Adhesion Force ◽  
Flying Height ◽  
Lubricant Layer ◽  
Lubricant Thickness ◽  
Dynamic Indentation ◽  
Magnetic Disks ◽  
Strong Adhesion ◽  
The Relationship ◽  
Acting Force ◽  
Interfacial Force

We measured the dynamic adhesion force when spherical sliders with a radius of 1 and 2 mm collided with smooth magnetic disks with lubricant layers of zero, 1, 2, and 3 nm thickness to clarify the dynamic interfacial force between a slider and disk in the nanometer region of flying height. From the measured slider velocity, we calculated the relationship between acceleration (acting force) and displacement. We found that a strong adhesion force observed at zero lubricant vanishes when 1-nm thick lubricant with UV is applied. As the mobile lubricant thickness was increased, we observed a clear dynamic adhesion force at the instant of separation. These results indicate that adhesion force is most likely to result from meniscus formation.

Depletion of Moleculary Thin Lubricant Under Flying Head in Hard Disk Drives

2007 ◽  
Author(s):  
Kenji Yanagisawa ◽  
Youichi Kawakubo ◽  
Masato Yoshino
Keyword(s):  
Thin Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Lubricant Film ◽  
Simulation Program ◽  
Disk Drives ◽  
Lubricant Thickness ◽  
Magnetic Disk ◽  
Lubricant Depletion ◽  
Lubricant Films

In Hard Disk Drives, lubricants are very important materials to reduce head and disk wear. Therefore, it is necessary to know the lubricant depletion under flying heads. Lubricant depletion due to flying heads has been studied experimentally. We developed simulation program to calculate numerically the change in lubricant thickness under a flying head on a thin-film magnetic disk from 10nm thick lubricant film. In recent HDDs, the lubricants thickness has become molecularly thin and polar lubricants have been used. In this paper, we took account of thickness-dependent lubricants diffusion and viscosity in our simulations to calculate a 1.2 nm thick polar lubricant film used in recent HDDs. The simulated results considering the thickness-dependent diffusion and viscosity showed that depletion was small in molecularly thin lubricant films. We considered it necessary to include thickness-dependent diffusion and viscosity in lubricant depletion simulation.

Experimental Identification of Elastic, Damping and Adhesion Forces in Collision of Spherical Sliders With Stationary Magnetic Disks

2004 ◽  
Author(s):  
Kyosuke Ono ◽  
Satoshi Oohara
Keyword(s):  
Adhesion Force ◽  
Contact Theory ◽  
Force Model ◽  
Adhesion Forces ◽  
Lubricant Thickness ◽  
Damping Force ◽  
Magnetic Disks ◽  
Magnetic Disk ◽  
Damping Effect ◽  
Experimental Identification

This paper deals with the experimental identification of elastic, damping and adhesion forces in the dynamic collision of a spherical slider with a stationary magnetic disk. We used rough Al2O3TiC and smooth glass spherical sliders with a radius of 1 mm, and magnetic disks with four different lubricant film thicknesses of 0, 1, 2, and 3 nm. We found that the Al2O3TiC slider shows ordinary approach and rebound processes, whereas the glass slider showed a velocity drop at the end of the rebound process when the lubricant thickness was 1, 2 and 3 nm. We identified the elastic force factors in the approaching and rebound processes, based on the Herztian contact theory, and the damping force factors based on a damping force model that is proportional to slider velocity and penetration depth (contact area). From the drop in velocity when the slider and disk separated, we found that the dynamic adhesion force is almost equal to the static pull-off force, except for with a 3nm lubricant thickness. The dynamic adhesion force with 3 nm lubricant thickness is significantly higher probably because of squeeze damping effect.

Effect of Sputtering Process Conditions on Microstructure and Mechanical Properties of Pt-Fe Nano Film

2011 ◽  
Vol 675-677 ◽  
pp. 655-658 ◽  
Author(s):  
S. Ishiguro ◽  
R. Ogatsu ◽  
T. Inami ◽  
T. Nakano ◽  
Dong Ying Ju ◽  
...  
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Hard Disk Drive ◽  
Disk Drive ◽  
Process Conditions ◽  
Next Generation ◽  
Recording Medium ◽  
Micro Structure ◽  
Magnetic Disks ◽  
High Density Magnetic Recording

One of the vertical magnetic recordings medium materials of the hard disk drive (HDD) is a Pt-Fe thin film. The development of ultra-high density magnetic recording medium in next generation is expected the magnetic disks such as HDD with capacity enlargement of the data. In order to study effectiveness of the proposed sputtering method, we evaluated micro structure, magnetic and the mechanical properties of a Pt-Fe thin film by some sputtering process conditions. From research results, effect sputtering conditions on micro-structure and mechanical properties of Pt-Fe nano film are verified.

Adhesion Forces for Sub-10 nm Flying-Height Magnetic Storage Head Disk Interfaces

2004 ◽  
Vol 126 (2) ◽  
pp. 334-341 ◽  
Author(s):  
Sung-Chang Lee ◽  
Andreas A. Polycarpou
Keyword(s):  
Flying Height ◽  
Magnetic Storage ◽  
Adhesion Forces ◽  
Force Measurements ◽  
Lubricant Thickness ◽  
Magnetic Disks ◽  
Atomic Force ◽  
Adhesion Model ◽  
Different Levels ◽  
Adhesive Forces

A quasi-dynamic adhesion model is used to calculate the intermolecular adhesion forces present in ultra low flying Head Disk Interfaces (HDI’s). The model is a continuum-based micromechanics model that accounts for realistic surfaces with roughness, molecularly thin lubricants, and is valid under both static and dynamic sliding conditions. Several different levels of surface roughness are investigated ranging from extremely smooth surfaces having a standard deviation of surface heights σ=2 Å to rougher interfaces with several nanometer roughness. It is found that when the flying-height is greater than 5 nm, there are no significant adhesive forces, whereas for flying-heights less than 5 nm, adhesion forces increase sharply, which can be catastrophic to the reliability of low flying HDI’s. In addition to roughness, the apparent area of contact between the flying recording slider and the magnetic disk is also found to significantly affect the magnitude of the adhesion forces. The adhesion model is validated by direct comparisons with adhesion “pull-off” force measurements performed using an Atomic Force Microscope with controlled probe tip areas and magnetic disks having different lubricant thickness.

Transparent Pin Wear Test on Thin-Film Magnetic Disk

1995 ◽  
Vol 117 (2) ◽  
pp. 297-301 ◽  
Author(s):  
Youichi Kawakubo ◽  
Yotsuo Yahisa
Keyword(s):  
Thin Film ◽  
Wear Debris ◽  
Wear Test ◽  
Video Camera ◽  
Video Monitoring ◽  
Friction Measurement ◽  
Magnetic Disks ◽  
Bulk Hardness ◽  
Pin On Disk ◽  
Wear Tests

Pin-on-disk wear tests on thin-film magnetic disks were performed using transparent materials. Quartz glass (QG), transparent zirconia (TZ), sapphire (SA), and synthesized diamond (DI) were used as pin materials. In addition to friction, sliding condition and pin wear were continuously monitored with video camera. Simultaneous friction measurement and video monitoring showed that friction dropped when wear debris intruded between pin and disk surfaces. Pin wear, from the measured diameter of wear scar on spherical pins, increased in the order of DI, SA, QG, and TZ. This order of pin wear does not coincide with that of the pin bulk hardness. Disk lifetime increased in the order of TZ, QG, SA, and DI, and the smaller the pin wear, the longer the disk lifetime.

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