The Decomposition Mechanisms and Thermal Stability of ZDOL Lubricant on Hydrogenated Carbon Overcoats

Chen, Chao-Yuan; Wei, Jingxuan; Fong, Walton; Bogy, David B.; Bhatia, Charanjit S.

doi:10.1115/1.555382

Cited by 12 publications

(5 citation statements)

References 17 publications

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“…Chen et al [12] demonstrated that the catalytic degradation process of Zdol in the presence of Lewis acid occurs most readily at the acetal units (O-CF 2 -O) within the internal backbones (CF 2 O and CF 2 CF 2 O) instead of the end group functionals. During the sliding at the carboncoated slider/Zdol lubricated CH disk interface, frictional heating is the primary decomposition mechanism of Zdol [13]. Wei et al [14] studied the decomposition mechanisms of a PFPE Zdol at the head/disk interface under sliding conditions using an ultrahigh vacuum tribometer equipped with a mass spectrometer.…”

Section: Introductionmentioning

confidence: 99%

Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

Nath

Wong

2014

Journal of Nanotechnology

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Perfluoropolyethers (PFPEs) are widely used as hard disk lubricants for protecting carbon overcoat reducing friction between the hard disk interface and the head during the movement of head during reading and writing data in the hard disk. Due to temperature rise of PFPE Zdol lubricant molecules on a DLC surface, how polar end groups are detached from lubricant molecules during coating is described considering the effect of temperatures on the bond/break density of PFPE Zdol using the coarse-grained bead spring model based on finitely extensible nonlinear elastic potential. As PFPE Z contains no polar end groups, effects of temperature on the bond/break density (number of broken bonds/total number of bonds) are not so significant like PFPE Zdol. Effects of temperature on the bond/break density of PFPE Z on DLC surface are also discussed with the help of graphical results. How bond/break phenomenonaffects the end bead density of PFPE Z and PFPE Zdol on DLC surface is discussed elaborately. How the overall bond length of PFPE Zdol increases with the increase of temperature which is responsible for its decomposition is discussed with the help of graphical results. At HAMR condition, as PFPE Z and PFPE Zdol are not suitable lubricant on a hard disk surface, it needs more investigations to obtain suitable lubricant. We study the effect of breaking of bonds of nonfunctional lubricant PFPE Z, functional lubricants such as PFPE Zdol and PFPE Ztetrao, and multidented functional lubricants such as ARJ-DS, ARJ-DD, and OHJ-DS on a DLC substrate with the increase of temperature when heating of all of the lubricants on a DLC substrate is carried out isothermally using the coarse-grained bead spring model by molecular dynamics simulations and suitable lubricant is selected which is suitable on a DLC substrate at high temperature.

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Section: Introductionmentioning

confidence: 99%

Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

Nath

Wong

2014

Journal of Nanotechnology

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“…The oxide radical will rapidly unzip the residual chain, producing CF O. Although this unzipping process has been claimed to be less likely [12], the CF O fragment was in fact detected by mass spectroscopy in a separate study [13]. The fluorocarbon radical can also degrade intact PFPE molecules by removal of a fluorine atom, thus generating a new radical [14].…”

Section: E Free Radical Degradation Mechanismmentioning

confidence: 96%

Catalytic decomposition of perfluoropolyether lubricants

2003

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With the ongoing decrease in magnetic spacing, the chemical durability of the lubricant film on magnetic recording media becomes a major factor in the reliability of the head-disk interface. There are several reports in the literature that have attributed deterioration of lubricant film to catalytic decomposition, and a reaction mechanism has been proposed by Kasai involving chain scission of the lubricant mainchain promoted by Lewis acids. In this work, an alternative mechanism is proposed, wherein perfluoropolyether (PFPE) lubricants are catalytically decomposed via a free radical degradation loop. The catalytic decomposition of Fomblin Zdol in the presence of the Lewis acid Al 2 O 3 was studied using thermogravimetric analysis (TGA). We show that various types of antioxidants can retard PFPE catalytic decomposition to different degrees, which we attribute to their different roles in breaking the free radical degradation loop. These data provide useful guidance in the development of new lubricants that are resistant to free radical initiated decomposition.

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“…We must note that the effect of the difference in the thermal expansion coefficients of the DLC film and the Si substrate on the destruction will be small in comparison to that of the chemical reaction. Chen et al described in their paper that the observed decomposition temperature for a 2000 MW PFPE is 429 K with a 0.2 K/s heating rate 17) . The 4000 MW PFPE without fractional treatment is used in this study, therefore, the used PFPE molecules will have a wide MW range due to the normal distribution.…”

Section: Discussionmentioning

confidence: 99%

Effect of Heat Treatment Temperature on PFPE Molecules Bonded on DLC Surface

et al. 2008

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Based on the demand of extremely increased area density for magnetic data storage, the contact recording systems have been proposed, in which stronger and thinner hard coatings and lubricant films for the head disk interface (HDI) are desired. In this study, two lubrication methods, i.e., the vacuum vapor deposition and dip-coating methods are evaluated and compared in order to satisfy the demands from the HDI development. Perfluoropolyether (PFPE) is applied to the diamond-like carbon (DLC) surface. The advantage of the vacuum vapor deposition is to prevent contamination of the DLC surface from the atmosphere because of no exposed samples to the atmosphere. In contrast, the advantage of dip-coating method is to thicken the bonded layer of the PFPE by heat treatment. We discuss the adsorption mechanism between the PFPE molecules and DLC surface for each method. In addition, a simple reaction model based on the Arrhenius equation is developed and compared to the experimental results. We concluded that the reaction will be dominated by covalent bonds and hydrogen bonding. Furthermore, the reaction model can well express the experimental results. The remarkable destruction of the DLC film by the heat treatment are not seen in the samples heat treated at a temperature from 353 to 423 K while the remarkable destruction are seen in the samples treated from 423 to 473 K.

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The Decomposition Mechanisms and Thermal Stability of ZDOL Lubricant on Hydrogenated Carbon Overcoats

Cited by 12 publications

References 17 publications

Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

Catalytic decomposition of perfluoropolyether lubricants

Effect of Heat Treatment Temperature on PFPE Molecules Bonded on DLC Surface

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