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.

Adhesion and Pull-Off Forces for Polysilicon MEMS Surfaces Using the Sub-Boundary Lubrication Model

2002 ◽  
Vol 125 (1) ◽  
pp. 193-199 ◽  
Author(s):  
Allison Y. Suh ◽  
Andreas A. Polycarpou
Keyword(s):  
Surface Roughness ◽  
Boundary Lubrication ◽  
Intermolecular Forces ◽  
Contact Forces ◽  
Root Mean Square Roughness ◽  
Magnetic Storage ◽  
Smooth Surfaces ◽  
Adhesion Forces ◽  
Disk Interface ◽  
Adhesion Model

Miniature devices including MEMS and the head disk interface in magnetic storage often include very smooth surfaces, typically having root-mean-square roughness, σ of the order of 10 nm or less. When such smooth surfaces contact, or come into proximity of each other, either in dry or wet environments, then strong intermolecular (adhesive) forces may arise. Such strong intermolecular forces may result in unacceptable and possibly catastrophic adhesion, stiction, friction and wear. In the present paper, a model termed sub-boundary lubrication (SBL) adhesion model is used to calculate the adhesion forces, and an elastic-plastic model is used to calculate the contact forces at typical MEMS interfaces. Several levels of surface roughness are investigated representing polished and as-deposited polysilicon films that are typically found in MEMS. The SBL adhesion model reveals the significance of the surface roughness on the adhesion and pull-off forces as the surfaces become smoother. The validity of using the SBL adhesion model to estimate the pull-off forces in miniature systems is further supported by direct comparison with experimental pull-off force measurements performed on silicon and gold interfaces. Finally, the significance of the interfacial forces as relate to the reliability of MEMS interfaces is discussed.

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.

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.

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

2005 ◽  
Vol 127 (2) ◽  
pp. 365-375 ◽  
Author(s):  
Kyosuke Ono ◽  
Satoshi Ohara
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 approach and rebound processes, based on 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 3 nm lubricant thickness. The dynamic adhesion force with a 3 nm lubricant thickness is significantly higher, probably because of squeeze damping effect.

The Study of Nanostructured Interfacial Coatings on SiC Fibers by Atomic Force Microscopy

2010 ◽  
Vol 434-435 ◽  
pp. 542-545 ◽  
Author(s):  
Natalia I. Baklanova ◽  
B.N. Zaitsev
Keyword(s):  
Atomic Force Microscopy ◽  
Adhesion Force ◽  
Fiber Surface ◽  
Ceramic Matrix Composites ◽  
Surface Heterogeneity ◽  
Matrix Composites ◽  
Force Measurements ◽  
Force Microscopy ◽  
Atomic Force ◽  
Adhesive Forces

Adhesion force measurements by atomic force microscopy (AFM) have been carried out to investigate the adhesion between the Si3N4 cantilever tip and the surface of the initial SiC-based Hi-Nicalon, Hi-Nicalon S, and Tyranno-SA fibers, as well as the ZrO2-coated and oxidized coated fibers. It was shown that the application of coating resulted in a change of the roughness parameters and a decrease of the adhesive forces between the Si3N4 cantilever tip and the fiber surface. Surface heterogeneity at the nanoscale could be responsible for the dispersion of adhesive forces. The results open the possibility of transferring nano mechanical information to meso or macro mechanical properties of ceramic matrix composites.

Interaction Forces of a Supported DOPC Bilayer in the Presence of the General Anaesthetic Halothane — An Atomic Force Microscopy Study

2006 ◽  
Vol 59 (6) ◽  
pp. 386 ◽  
Author(s):  
Leanne G. Shamrakov ◽  
Zoya V. Leonenko ◽  
Eric Finot ◽  
David T. Cramb
Keyword(s):  
Atomic Force Microscopy ◽  
Microscopy Study ◽  
General Anaesthetic ◽  
Force Measurements ◽  
Atomic Force Microscopy Study ◽  
Adhesion Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Initial Decrease ◽  
Adhesive Forces

In this study atomic force microscopy (AFM) was used to study the effect of halothane on a supported dioleoylphosphatidylcholine (DOPC) bilayer under conditions of high anaesthetic loading. In a previous study we demonstrated that bilayer restructuring occurs as a result of halothane incorporation. Force measurements using AFM indicate an initial decrease in adhesive forces and compressibility between the bilayer and AFM tip, followed by an increase in adhesion properties as a function of incubation time. This effect is attributed to the location and dynamic redistribution of halothane within the bilayer.

Textured Sliders as Means to Reduce Adhesion in Ultra Low Flying Head Disk Interfaces

2002 ◽  
Author(s):  
Allison Y. Suh ◽  
Sung-Chang Lee ◽  
Andreas A. Polycarpou
Keyword(s):  
Air Bearing ◽  
Negative Consequences ◽  
Magnetic Media ◽  
Adhesion Forces ◽  
Roughness Parameters ◽  
Original Surface ◽  
Atomic Force ◽  
High Adhesion ◽  
Slider Air Bearing ◽  
Adhesion Model

A means of avoiding the negative consequences of ultra low flying super smooth Head/Disk Interfaces (HDIs) is to use textured sliders while still maintaining super smooth magnetic media. In this paper, the effect of preferential texturing (roughening) of slider air-bearing surfaces (ABS) on the intermolecular/adhesion forces at HDIs is investigated using a quasi-dynamic adhesion model. Super smooth (untextured), preferentially textured and rough sliders were investigated in this study. First, they were measured using an Atomic Force Microscope (AFM) and subsequently roughness parameters were extracted and used in the modeling. Preferential texturing provides a unique roughening of the ABS, where parts of the original surface are not affected, thus maintaining the initial roughness, with other parts of the surface being removed. This texturing has the net effect of reducing the effective or nominal area of contact between the slider and media surfaces, which plays an important role in the adhesion forces at the HDI. The simulation results indicate that preferential texturing can alleviate the problem of high adhesion forces in ultra-low flying HDI’s.

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