Study on Failure Process of Silicon-Doped Amorphous Carbon by ReaxFF Molecular Dynamics Simulation for HAMR

Liu, Qingkang; Li, Longqiu; Zhang, Guangyu; Shuai, Cijun

doi:10.1109/tmag.2019.2950258

Cited by 12 publications

(5 citation statements)

References 26 publications

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“…We calculated the distributions of bond length and bond angle of sp 3 -carbon (sp 3 (C)) in the a-C:Si films prepared by the liquid quenching procedure (Figure S1). The average bond length between sp 3 (C) ranged from 1.54 to 1.6 Å, and the average bond angle was 109°, consistent with the simulated results. ,,− In addition, we also calculated the ratio of sp 2 (C) and sp 3 (C) of five different Si content films (Figure S3). The results were consistent with the hybridization ratio range (sp 3 (C): 55.3–70 at%, sp 2 (C): 20–40 at%) ,, of a-C or a-C:Si films with densities around 3.0 g/cm 3 .…”

Section: Simulation Methods and Characterizationsupporting

confidence: 82%

“…The friction pair consisted of two a-C:Si films of size 42 × 42 × 20 Å 3 with different Si doping contents (Figure ). We prepared five kinds of a-C:Si films with Si contents of 0, 4, 7.2, 15, and 20 at% by replacing a certain percentage of the C atoms and an initial density of 3.0 g/cm, ,− which was confirmed as the density of the most stable a-C structure selected. The highest Si content of a-C:Si films prepared experimentally was 35.6 at%, among which the 1–20 at% Si content was selected as the majority. ,,,, A liquid quenching method , was used to model the a-C:Si films.…”

Section: Simulation Methods and Characterizationmentioning

confidence: 98%

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Changing of the Interfacial Contacts and Shear Behaviors between a-C Films Caused by Si Doping

Duan

2023

Langmuir

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We used reactive molecular dynamics (ReaxFF-MD) to simulate the friction and shear behavior of a-C:Si films with varying Si content (0−20 at %). We found that the optimal doping content was 7.2 at%, which had similar friction to the undoped film but had smaller wear and running-in time (40 and 60% of the undoped film, respectively). Compared with the undoped film, the proper amount of Si doping significantly inhibited the formation of all-C bridging chains at the interface and prevented the formation of a large number of all-C and Si-involved bridging chains caused by surface dangling bonds at higher Si contents. Our study revealed the atomic scale mechanism of Si doping on the tribological properties of a-C films.

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Section: Simulation Methods and Characterizationsupporting

confidence: 82%

Section: Simulation Methods and Characterizationmentioning

confidence: 98%

Changing of the Interfacial Contacts and Shear Behaviors between a-C Films Caused by Si Doping

Duan

2023

Langmuir

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“…The ReaxFF method has been successfully applied to the study of some molecular reactive dynamics simulations. The application systems include hydrocarbon organic small molecule systems [23], polymer systems [24][25] and organic mixture systems [26][27]. The gap between quantum mechanics (QM) and empirical methods in the simulation range could be bridged with the help of ReaxFF.…”

Section: Molecular Dynamics Simulation Principle Basedmentioning

confidence: 99%

Micro-mechanism study on different antioxidants protective effect of vegetable oil by ReaxFF molecular dynamics

Cong

Pan

et al. 2021

CSEE JPES

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The aging problem of vegetable oil has severely restricted the popularization and application of vegetable oil transformers. Adding antioxidants is the most recommended solution. At present, there is insufficient research on the micro-mechanism of the protective effect of antioxidants on vegetable oil. In this paper, multiple vegetable oil models with different types and concentrations of antioxidants were established. Then the molecular dynamics simulation based on ReaxFF was carried out at different temperatures and oxygen content. Results show that the protective mechanism of antioxidants is to release H and combine with free radicals generated by the decomposition of unsaturated fatty acids (UFA) in the oil. In addition, the protective effects of four antioxidants are different. The stronger ones are tert-butyl hydroquinone (TBHQ) and butylated hydroxytoluene (BHT), while the weaker ones are butylated hydroxyanisole (BHA) and propyl gallate (PG). TBHQ has a better protective effect at low concentration, but the decomposition of UFA is promoted at high concentration. When the temperature rises, the decomposition of UFA would be promoted. With the addition of oxygen, small molecular compounds are easily oxidized, and the decomposition of UFA is accelerated. The above research could reveal the microscopic mechanism of antioxidant protection on vegetable oil, providing theoretical reference for further exploration of effective vegetable oil aging protection technology.

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“…SiO 2 nanoparticles are often used as lubricant additives to improve tribological properties, such as a reduced coefficient of friction, wear volume, and corrosion [6][7][8][9][10]. However, under a nanocontact condition, such as in a HDD, accumulation in the form of either siloxane or SiO 2 can increase the head slider's mechanical instability and surface contamination by physical HDI contact, which can cause a critical reading and writing failure due to the low HMS [2][3][4][11][12][13]. Another undesirable contaminant in HDI is water molecules, because they are readily adsorbed into the thin perfluoropolyether (PFPE) lubricant on a recording medium.…”

Section: Introductionmentioning

confidence: 99%

Mechano-Chemical Properties and Tribological Performance of Thin Perfluoropolyether (PFPE) Lubricant Film under Environmental Contaminants

Jung

Yeo

2023

Lubricants

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Through molecular dynamics (MD) simulations with ReaxFF potential, the effects of chemical contaminants on the mechano-chemical properties and tribological performance of perfluoropolyether (PFPE) lubricants were investigated. For the two types of contaminants, i.e., silicon dioxide (SiO2) nanoparticles and water (H2O), their molecular interactions with the two different PFPE lubricants, i.e., Ztetraol and ZTMD, were evaluated at the two different temperatures, i.e., 300 K and 700 K. Contaminants were adsorbed onto the PFPE lubricants at a controlled temperature. Then, air shear simulations were conducted to examine the mechano-chemical behaviors of the contaminated lubricants. Sliding contact simulations were performed to further investigate the tribological performance of the contaminated lubricants, from which the resulting friction and surface contamination were quantified. Lastly, chemical reactions between PFPE lubricants and contaminants were studied to investigate the degradation of PFPE lubricants. It was observed that SiO2 nanoparticles stiffened the PFPE lubricant, which decreased its shear displacement and increased friction. In the case of the H2O contaminant, it weakened and decreased the PFPE lubricant’s viscosity, increasing its shear displacement and lowering friction. However, the decreased viscosity by H2O contaminants can weaken the lubricity of the PFPE lubricant, leading to a higher chance of direct solid-to-solid contact under high contact force conditions.

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Study on Failure Process of Silicon-Doped Amorphous Carbon by ReaxFF Molecular Dynamics Simulation for HAMR

Cited by 12 publications

References 26 publications

Changing of the Interfacial Contacts and Shear Behaviors between a-C Films Caused by Si Doping

Changing of the Interfacial Contacts and Shear Behaviors between a-C Films Caused by Si Doping

Micro-mechanism study on different antioxidants protective effect of vegetable oil by ReaxFF molecular dynamics

Mechano-Chemical Properties and Tribological Performance of Thin Perfluoropolyether (PFPE) Lubricant Film under Environmental Contaminants

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