Lubricants for the Disk Drive Industry

Karis, T.

doi:10.1201/9781420059656-c22

Cited by 10 publications

(7 citation statements)

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“…A mechanism which could give rise to this observation is described in the following. For bulk Ztetraol 2000, the viscoelastic shear loss tangent at 10 9 Hz and 20°C is 1.22 9 10 -5 [26], so that the strain energy stored in the asperity contact is almost fully recovered. Only 0.00122% is immediately lost to viscous dissipation.…”

Section: Frictional Energy Dissipationmentioning

confidence: 95%

“…Dispersion force operates on a time scale (10 16 -10 14 rad/sec), which is much shorter than the lifetime of the transient bridges. Only dispersion force contributions to the tensile strength are included in the following, because the high velocity between the slider and disk asperities does not allow time for dipole orientation [26], and there are relatively few polar end groups per unit area of disk surface [39]. The interaction free energy per unit area between two material surfaces separated by a planar gap is [40,41]:…”

Section: Adhesion Stressmentioning

confidence: 99%

“…Hence the meniscus model is subject to the same constraint of viscoelasticity as a shear flow for molecularly thin and highly bonded liquid films. It is not physically meaningful to invoke shear flow within asperity contacts lubricated by molecularly thin and highly bonded lubricant films because our process time scale of 1=_ c ¼ 1:8 Â 10 À10 sec for the shear is much less than the 10 -5 s characteristic viscoelastic relaxation time for PFPE lubricant chains [26]. We show that a molecular adhesion model derived from dispersion force interaction through the Liftshitz theory is more appropriate at the time and length scales of asperity interactions in the bridged state.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics in the Bridged State of a Magnetic Recording Slider

2008

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A novel region of tribological interaction is explored by inducing near contact between the magnetic recording slider and disk. In this study, we performed frictional measurements over a wide range of subambient air pressure and disk rotation rate. Since the slider is supported over the disk by an air bearing, it has been found that cycling from ambient to subambient and then back up to ambient pressure over several minutes of time forms a frictional hysteresis loop. The high-friction branch of the loop, referred to as the bridged state, is characterized by an average frictional displacement and resonant vibration of the suspension mount assembly. The bridged state is currently employed for accelerated wear testing of magnetic slider/disk/lubricant systems. Future magnetic recording systems designed to operate at increasingly lower physical spacing will need to take into account these frictional forces which accompany the incipient contact between the lubricated disk and slider with finite surface roughness. A single degree of freedom model is solved to determine the equivalent dynamic friction force on the slider as an impulse series with random impulse frequency and amplitude from the measured frictional displacement in the bridged state. The mean slider-disk spacing in the bridged state is derived from the experimental friction force, the spacing probability density function, and the adhesion stress from the Lifshitz model for dispersion interaction energy.

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Section: Frictional Energy Dissipationmentioning

confidence: 95%

Section: Adhesion Stressmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamics in the Bridged State of a Magnetic Recording Slider

2008

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“…At present, Z-DOL series lubricants with a chemical structure of HOCH 2 (OCF 2 CF 2 ) m (OCF 2 ) n OCH 2 OH (Scheme 1) are widely used in the industry. 4,5 They have good physical properties such as good thermal stability, low surface tension, good structural flexibility and good surface mobility, but are sticky to tip and have lubricant loss problems. 6 If more polar groups such as hydroxy groups or even amine groups are attached at the end of the PFPE chain, e.g.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and properties of cyclotriphosphazene and perfluoropolyether‐based lubricant with polar functional groups

Wang

Tan

Cho

et al. 2016

Lubrication Science

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A novel hard disk lubricant IDL2 was synthesised by reacting sodium 4‐((2,2‐dimethyl‐1,3‐dioxolan‐4‐yl)methoxy)phenoate with hexachlorocyclotriphosphazene, followed by treatment with 1H,1H‐perfluoro‐3,6,9‐trioxatridecan‐1‐ol in the presence of sodium hydride and subsequent hydrolysis using sulfuric acid. The chemical structure of IDL2 was confirmed by proton nuclear magnetic resonance (1H NMR), phosphorus‐31 (31P) NMR spectroscopy and mass spectrometer. The thermal property of IDL2 was analysed using thermal gravimetric analysis (TGA) and it shows better thermal stability than two commercial lubricants Z‐DOL and Z‐Tetraol with two and four terminal hydroxy groups, respectively. IDL2 was found to have comparable hydrophobicity to commercial lubricants Z‐DOL, A20H and Z‐Tetraol with water contact angles in the range of 78 – 85°, revealing that IDL2 has analogous surface energy to these commercial lubricants. IDL2 exhibits comparable friction coefficient to A20H and Z‐Tetraol, but much lower than Z‐DOL. More interestingly, it has a much high bonding ratio when compared with commonly used commercial lubricants under the same testing conditions due to the presence of two polar hydroxy groups, which enhance the interaction between lubricant and substrate. These promising properties of IDL2 show that it would be very potential for real application as a hard disk drive lubricant. Copyright © 2016 John Wiley & Sons, Ltd.

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“…In lubrication design, this property is very useful, because it provides information about the tendency of vaporization of the different oils or other lubricants and, thus, the potential of contamination from evaporative loss: the lower the vapor pressure, the better the lubricant, especially in the case of many space applications and lubricants for the disk drive industry. 6,7 In the case of engines, there is a direct association between oil volatility and oil consumption rates. 1 Because of the great difficulty in measuring low vapor pressures, the usual techniques in the lubrication field are based on weight loss due to evaporation: the Knudsen effusion method, thermogravimetric analysis (TGA), and nonequilibrium weight loss measurements under vacuum.…”

Section: Introductionmentioning

confidence: 99%

Vapor-Pressure Measurements and Modeling of Dipentaerythritol Ester Lubricants

Garcı́a

Naccoul

Fernández

et al. 2011

Ind. Eng. Chem. Res.

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The aim of this work is to present new vapor-pressure measurements and provide a good description of the volumetric and phase behavior of dipentaerythritol ester (DiPEs) lubricants, using the Statistical Associating Fluid Theory (SAFT) model (PC-SAFT and SAFT-VR versions). Characteristic parameters of these versions were optimized for dipentaerythritol hexapentanoate (DiPEC5), dipentaerythritol hexaheptanoate (DiPEC7), and dipentaerythritol isononanoate (DiPEiC9), using experimental vapor pressures and densities. With these parameters, compressed densities were predicted. Experimental vapor pressures, determined by a gas saturation apparatus, range between 2 × 10−5 Pa and 16 Pa, whereas the absolute deviations obtained in the correlations for both versions of the model (PC-SAFT and SAFT-VR) are between 10−6 Pa and 1 Pa. In the case of saturated densities, the average absolute deviation (AAD) values, for both models, range from 0.2% to 1.3%, except for DiPEC7, where the AAD is 4.4% when using the SAFT-VR model. The SAFT-VR version gives slightly better correlations, although we must note that this version has four parameters, whereas the PC-SAFT version has three.

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Lubricants for the Disk Drive Industry

Cited by 10 publications

References 0 publications

Dynamics in the Bridged State of a Magnetic Recording Slider

Dynamics in the Bridged State of a Magnetic Recording Slider

Synthesis and properties of cyclotriphosphazene and perfluoropolyether‐based lubricant with polar functional groups

Vapor-Pressure Measurements and Modeling of Dipentaerythritol Ester Lubricants

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