Structural response of alkali metal borates at Fe2O3 sliding interface: The effect of alkali cations

Ta, Huong T. T.; Zhu, Hong Tao; Yu, Haibo; Tran, Nam V.; Le, Ha M.; Ta, Thi D.

doi:10.1016/j.commatsci.2020.109930

Cited by 4 publications

(13 citation statements)

References 48 publications

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“…Moreover, the energy barrier of sodium borate with 33% Na 2 O was close to potassium, but the confined systems with a higher concentration of Na showed much smaller energy barriers than those using K and Li elements [36]. Among the considered alkali elements, Li provided the highest energies barriers at low and high applied pressures [36]; this unveiled that friction in this system could be higher than in the others. The calculation of the number of bonds between Fe and O in borate molecules showed that this number is under five for systems with Na 2 O concentrations larger than 33%, whilst values larger than six were found for Li and K systems [36].…”

Section: The Roles Of Na In Glass Lubricantsmentioning

confidence: 87%

“…When this O nb joined the polymerization process, the modification role of Na + cations was inevitably reduced, so they were attracted to surface oxygen to create a Na-rich layer. In shearing conditions, the higher concentration of sodium oxide resulted in smaller energy barriers, which indicated that lower friction could be obtained because of this Na-rich layer [36]. Moreover, the energy barrier of sodium borate with 33% Na 2 O was close to potassium, but the confined systems with a higher concentration of Na showed much smaller energy barriers than those using K and Li elements [36].…”

Section: The Roles Of Na In Glass Lubricantsmentioning

confidence: 98%

“…It is important to investigate the chemical mechanism of how a glassy lubricant works when it is applied in practice at high temperature and pressure in metal forming. We have carried out some theoretical investigations of the adsorption and thin film lubrication of Na4P2O7 and Na5P3O10 [31][32][33][34], sodium tetraborate (Na2B4O7), and boron oxide (B2O3) molecules [25,35,36], as well as sodium…”

Section: Theoretical Simulationsmentioning

confidence: 99%

“…It is important to investigate the chemical mechanism of how a glassy lubricant works when it is applied in practice at high temperature and pressure in metal forming. We have carried out some theoretical investigations of the adsorption and thin film lubrication of Na [25,35,36], as well as sodium silicate, Na 6 Si 2 O 7 , on iron and iron oxide surfaces [37,38]. These studies have overcome the drawbacks of previous experiments and provided a deep insight into the chemical reactions in the tribofilm.…”

Section: Theoretical Simulationsmentioning

confidence: 99%

“…In shearing conditions, the higher concentration of sodium oxide resulted in smaller energy barriers, which indicated that lower friction could be obtained because of this Na-rich layer [36]. Moreover, the energy barrier of sodium borate with 33% Na 2 O was close to potassium, but the confined systems with a higher concentration of Na showed much smaller energy barriers than those using K and Li elements [36]. Among the considered alkali elements, Li provided the highest energies barriers at low and high applied pressures [36]; this unveiled that friction in this system could be higher than in the others.…”

Section: The Roles Of Na In Glass Lubricantsmentioning

confidence: 99%

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Tribochemistry and Lubrication of Alkaline Glass Lubricants in Hot Steel Manufacturing

Tran

2020

Lubricants

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Nowadays, the increasing demand to reduce energy consumption and improve process reliability requires an alternative lubricant with an effective tribological performance and environmentally friendly properties to replace traditional lubricants in hot steel manufacturing. The current work reviews recent comprehensive experimental and theoretical investigations in a new generation of alkaline-based glass lubricants, with phosphate, borate, and silicate being intensively researched. This class of lubricants showed an outstanding friction reduction, anti-wear, and anti-oxidation performance on coupled steel pairs over a wide range of temperatures (from 650 °C to 1000 °C). Each type had different tribochemical reactions within itself and with oxidized steel surfaces, which were largely determined by their chemical nature. In addition, the critical role of each structural component was also determined and corroborated by computational simulation. The theoretical studies at quantum and atomic levels reinforced our experimental findings by providing insights into the reaction mechanism using the static and dynamic simulations of the adsorption of lubricant molecules onto iron oxide surfaces. Additionally, the new reactive molecular dynamics (MD) model developed for alkali phosphate will need to be extended further to consider the realistic operating conditions of these lubricants at the atomic scale.

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Section: The Roles Of Na In Glass Lubricantsmentioning

confidence: 87%

Section: The Roles Of Na In Glass Lubricantsmentioning

confidence: 98%

Section: Theoretical Simulationsmentioning

confidence: 99%

“…It is important to investigate the chemical mechanism of how a glassy lubricant works when it is applied in practice at high temperature and pressure in metal forming. We have carried out some theoretical investigations of the adsorption and thin film lubrication of Na [25,35,36], as well as sodium silicate, Na 6 Si 2 O 7 , on iron and iron oxide surfaces [37,38]. These studies have overcome the drawbacks of previous experiments and provided a deep insight into the chemical reactions in the tribofilm.…”

Section: Theoretical Simulationsmentioning

confidence: 99%

Section: The Roles Of Na In Glass Lubricantsmentioning

confidence: 99%

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Tribochemistry and Lubrication of Alkaline Glass Lubricants in Hot Steel Manufacturing

Tran

2020

Lubricants

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A First-Principles Study of Impurity-Enhanced Adhesion and Lubricity of Graphene on Iron Oxide Surface

Tieu

Zhu

et al. 2021

J. Phys. Chem. C

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Graphene is well-known as one of the best solid lubricants for its superlubricity and high mechanical strength. Weak adhesion leading to low interfacial compatibility is a significant challenge of the use of graphene in harsh conditions. In this work, guided by density functional theory (DFT) calculations, we propose a method to improve graphene compatibility on Fe2O3 by substituting B, P, S, and Si to some carbon sites. The results of binding energy and potential energy surface (PES) show that the selection of suitable elements with a reasonable concentration not only greatly improves graphene adhesion but also provides a better frictional property than that with pure graphene. The doped-graphene chemically binds on the surface through the formation of covalent bonds between the dopant atoms and iron of the surface. Bader charge analyses suggest that the doping of B and P causes a severe charge alteration at the nearest carbon C1, and a strong repulsion at the C1–C1 stacking sites at the sliding interface, leading to a reduction in corrugation energies and thus nanoscale friction. Furthermore, first-principles molecular dynamics (FPMD) simulations at high temperature reveal that thanks to well-adhered behavior, the doped-graphene shows a significant reduction in the structural deformation, especially the out-of-plane component, which is essential to maintain graphene’s ultralow friction regime under harsh conditions. The current results shed light on further improved graphene performance without affecting its superlubricity.

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Computational Tribochemistry: A Review from Classical and Quantum Mechanics Studies

Tran

Zhu

et al. 2021

J. Phys. Chem. C

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Recent years have witnessed the acceleration of research on tribochemical reactions in the tribology area. Together with new experimental findings, atomic modeling has increasingly contributed to the understanding of mechanistic insights and interpretation of tribochemical reactions and related frictional outcomes. Apart from showing agreement with experiments, efforts have been paid to develop simulation codes and models to bring simulations closer to practical tribotests with a reasonable computational expense. By simulations and modeling, tribochemical reactions and physical/chemical interactions between lubricants, surface−lubricant, contacting interfaces, and surface/ lubricant−environmental agents have been investigated. This work provides an up-to-date review of studies on physical/chemical interactions and tribochemical reactions in tribosystems using atomic computational simulations such as reactive force fields, quantum mechanics, and quantum mechanics/molecular dynamics. On the basis of the current development, we outline future prospects for the simulation and modeling section in the field of tribochemistry.

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Structural response of alkali metal borates at Fe2O3 sliding interface: The effect of alkali cations

Cited by 4 publications

References 48 publications

Tribochemistry and Lubrication of Alkaline Glass Lubricants in Hot Steel Manufacturing

Tribochemistry and Lubrication of Alkaline Glass Lubricants in Hot Steel Manufacturing

A First-Principles Study of Impurity-Enhanced Adhesion and Lubricity of Graphene on Iron Oxide Surface

Computational Tribochemistry: A Review from Classical and Quantum Mechanics Studies

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