scholarly journals Tribological and Thermophysical Properties of Environmentally-Friendly Lubricants Based on Trimethylolpropane Trioleate with Hexagonal Boron Nitride Nanoparticles as an Additive

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 509 ◽  
Author(s):  
José M. Liñeira del Río ◽  
María J. G. Guimarey ◽  
María J. P. Comuñas ◽  
Enriqueta R. López ◽  
Jose I. Prado ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Normal Load ◽  
Confocal Raman Microscopy ◽  
Base Oil ◽  
Shear Rates ◽  
The Stability ◽  
Scar Width ◽  
Ester Base ◽  
Newtonian Behavior

Dispersions based on hexagonal boron nitride, h-BN, nanoparticles, at 0.50, 0.75 and 1.0 wt.% mass concentrations, in an ester base oil composed mainly of trimethylolpropane trioleate, were investigated as potential nanolubricants. The stability of the dispersions was assessed to determine the reliability of the tribological, thermophysical and rheological measurements. Density and viscosity were measured from 278.15 to 373.15 K, while rheological behavior was analyzed at shear rates from 1 to 1000 s−1 at 283.15 K. Newtonian behavior was exhibited by all nanolubricants at the explored conditions, with the exception of the highest concentration at the lowest shear rates, where possible non-Newtonian behavior was observed. Tribological tests were performed under a normal load of 2.5 N. Wear was evaluated by means of a 3D profiler, scanning electron microscopy and confocal Raman microscopy. The best tribological performance was achieved by the 0.75 wt.% nanolubricant, with reductions of 25% in the friction coefficient, 9% in the scar width, 14% in the scar depth, and 22% of the transversal area, all with respect to the neat oil. It was observed that physical protective tribofilms are created between rubbing surfaces.

scholarly journals Examination of lubricity properties of mineral base oil, containing nanoparticles of hexagonal boron nitride, and evaluation of the influence of surfactants on their sedimentation

2020 ◽  
Vol 69 (4) ◽  
pp. 15-41
Author(s):  
Arkadiusz Chodkiewicz ◽  
Tadeusz Kałdoński
Keyword(s):  
Particle Size ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Wear Test ◽  
Solid Particles ◽  
Wear Scar ◽  
Wear Scar Diameter ◽  
Load Curve ◽  
Base Oil ◽  
Mineral Base

The article presents the results of tests on the lubricity properties of SN150 base oil containing hexagonal boron nitride (h-BN) of different granulation. The boron nitride with a particle size below 100 nm and the second one with a particle size below 25 μm were used. The lubricity tests were carried out on a four-ball apparatus. The methodology of these tests was determined on the basis of the normative document PN-EN ISO 20623: 2018-02, which contains the following parameters characterising the lubricity: initial seizure load ISL [N], weld load WL [N], load-wear index LWI [N], mean wear scar diameter MWSD [mm] obtained in a long duration wear test under a specified load; wear-load curve, i.e., the dependence of the mean wear scar diameter on the load, was also performed. Tests were also carried out to check the influence of selected surfactants on the sedimentation process of hexagonal boron nitride in the SN150 mineral base oil. Based on the conducted research and their analysis, it was found that hexagonal boron nitride has a positive effect on the lubricating properties of the base oil; better results were obtained for the boron nano-nitride with a particle size below 100 nm. It was also found that the problem of sedimentation of the solid particles of hexagonal boron nitride was solved by the addition of succinimide dispersant. Keywords: tribology, lubricity, boron nitride, surfactants, sedimentation

scholarly journals Electron correlation decides the stability of cubic versus hexagonal boron nitride

2011 ◽  
Vol 83 (3) ◽  
Author(s):  
Migen Halo ◽  
Cesare Pisani ◽  
Lorenzo Maschio ◽  
Silvia Casassa ◽  
Martin Schütz ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Electron Correlation ◽  
Hexagonal Boron Nitride ◽  
The Stability

scholarly journals Nanodiamond Particles as Secondary Additive for Polyalphaolefin Oil Lubrication of Steel–Aluminium Contact

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1438
Author(s):  
Ankush Raina ◽  
Mir Irfan Ul Haq ◽  
Ankush Anand ◽  
Sanjay Mohan ◽  
Rajiv Kumar ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Hexagonal Boron Nitride ◽  
Normal Load ◽  
Lubricant Additive ◽  
Oil Lubrication ◽  
Volumetric Wear ◽  
Base Oil ◽  
Applied Normal Load ◽  
Lubrication Performance ◽  
The Coefficient Of Friction

Nanodiamond (ND) particles are effective lubricant additives. Attention of research has shifted towards investigating the particles as secondary additives. ND particles provide more benefits as secondary additives than as the sole lubricant additive for steel–steel contacts. In this work, the influence of ND particles as secondary additives on oil lubrication of steel–aluminium tribopair (hard–soft contact) was examined. AISI 52100 steel balls were slid against AA2024 aluminium alloy discs, in the presence of polyalphaolefin (PAO) base oil, in boundary lubrication regime (applied normal load: 10 N to 50 N). Primary additives were copper oxide (CuO) and hexagonal boron nitride (h-BN) nanoparticles. The addition of ND particles to PAO, with CuO and h-BN as primary additives, at the lowest applied normal load of 10 N: (i) decreased the volumetric wear of the aluminium discs by 28% and 63%, respectively, and (ii) decreased the coefficient of friction by 15% and 33%, respectively. At the highest applied normal load of 50 N, it: (i) decreased the volumetric wear of the aluminium discs by 20% and 38%, respectively, and (ii) decreased the coefficient of friction by 5.4% and 8%, respectively. ND particles as secondary additives significantly reduce energy loss and power loss as a consequence of an effective reduction in friction during sliding. Unique characteristics of ND particles—such as their (a) physicochemical and thermal properties, (b) ball bearing and polishing effects and (c) synergistic interaction with primary additives to form stable tribofilms—enhance the lubrication performance of steel–aluminium contact. ND particles in combination with h-BN nanoparticles showed the best performance, due to better synergy between the primary additive and the secondary additive. Results from the investigation indicate that ND particles taken as secondary additives in small amount (0.2 wt%) can improve oil lubrication performance of hard–soft contacts in engineering systems.

scholarly journals Noble metal supported hexagonal boron nitride for the oxygen reduction reaction: a DFT study

2019 ◽  
Vol 1 (1) ◽  
pp. 132-139 ◽  
Author(s):  
Seoin Back ◽  
Samira Siahrostami
Keyword(s):  
Boron Nitride ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Density Functional Theory Calculations ◽  
Cost Effective ◽  
Reduction Reaction ◽  
Functional Theory ◽  
The Stability

Discovering active, stable and cost-effective catalysts for the oxygen reduction reaction (ORR) is of utmost interest for commercialization of fuel cells. Herein, we use density functional theory calculations to systematically study metal supported hexagonal boron nitride as ORR catalysts. Our results indicate that this strategy is a promising to increase the stability against CO poisoning as well as to activate inert h-BN toward the ORR.

Ab initio study of the structures and hydrogen storage capacity of (H2)nCH4 compound

2015 ◽  
Vol 29 (13) ◽  
pp. 1550062 ◽  
Author(s):  
Minghui Wang ◽  
Xinlu Cheng ◽  
Dahua Ren ◽  
Hong Zhang ◽  
Yongjian Tang
Keyword(s):  
Boron Nitride ◽  
Hydrogen Storage ◽  
Ab Initio ◽  
Density Functional ◽  
Storage Capacity ◽  
Hexagonal Boron Nitride ◽  
Boron Nitride Nanotubes ◽  
Hydrogen Storage Capacity ◽  
Practical Applications ◽  
The Stability

The hydrogen-rich compound ( H 2)n CH 4 (for n = 1, 2, 3, 4) or for short ( H 2)n M is one of the most promising hydrogen storage materials. The ( H 2)4 M molecule is the best hydrogen-rich compound among the ( H 2)n M structures and it can reach the hydrogen storage capacity of 50.2 wt.%. However, the ( H 2)n M always requires a certain pressure to remain stable. In this work, we first investigated the binding energy of the different structures in ( H 2)n M and energy barrier of H 2 rotation under different pressures at ambient temperature, applying ab initio methods based on van der Waals density functional (vdW-DF). It was found that at 0 GPa, the ( H 2)n M is not stable, while at 5.8 GPa, the stability of ( H 2)n M strongly depends on its structure. We further investigate the Raman spectra of ( H 2)n M structures at 5.8 GPa and found the results were consistent with experiments. Excitingly, we found that boron nitride nanotubes (BNNTs) and graphite and hexagonal boron nitride ( h - BN ) can be used to store ( H 2)4 M , which give insights into hydrogen storage practical applications.

Stability and electronic properties of hexagonal boron nitride monolayer with irregular graphene domains embedded

2014 ◽  
Vol 28 (18) ◽  
pp. 1450144 ◽  
Author(s):  
Meiyan Ni ◽  
Yancong Wang ◽  
Qiang Yang ◽  
Weiqi Zhu ◽  
Qiong Tang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Spin Splitting ◽  
Energy Band Gap ◽  
Functional Theory ◽  
Magnetic Heterostructures ◽  
The Difference ◽  
The Stability ◽  
Gap States

Using density functional theory, we investigated the stability, magnetism and band structures of hexagonal boron nitride ( h - BN ) monolayer with graphene domains ( h - BNC heterostructure). The number of the carbon atoms in the graphene domain is fixed with shapes and locations in the h- BN monolayer different. We found that these h - BNC heterostructures exhibit different stability, magnetism and energy band gap. Our results show that the stability of the system is related to the number of C – C / C – N / C – B bonds and unpaired sublattices in the graphene domains. Some h - BNC heterostructures are magnetic with the magnetic moment equal to the difference of the nonequivalent sublattices in graphene domains, which obeys Lieb's theorem. Because of the spin splitting of the mid-gap states, the band gaps of the magnetic heterostructures are smaller than that of the nonmagnetic ones.

scholarly journals Long-Term Stabilization of Two-Dimensional Perovskites by Encapsulation with Hexagonal Boron Nitride

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1120 ◽  
Author(s):  
Michael Seitz ◽  
Patricia Gant ◽  
Andres Castellanos-Gomez ◽  
Ferry Prins
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Spectroscopic Studies ◽  
Environmental Stability ◽  
Two Dimensional ◽  
Ambient Conditions ◽  
Lead Iodide ◽  
Long Term Stability ◽  
The Stability

Metal halide perovskites are known to suffer from rapid degradation, limiting their direct applicability. Here, the degradation of phenethylammonium lead iodide (PEA2PbI4) two-dimensional perovskites under ambient conditions was studied using fluorescence, absorbance, and fluorescence lifetime measurements. It was demonstrated that the long-term stability of two-dimensional perovskites could be achieved through the encapsulation with hexagonal boron nitride. While un-encapsulated perovskite flakes degraded within hours, the encapsulated perovskites were stable for at least three months. In addition, encapsulation considerably improved the stability under laser irradiation. The environmental stability, combined with the improved durability under illumination, is a critical ingredient for thorough spectroscopic studies of the intrinsic optoelectronic properties of this material platform.

STRONGLY AND WEAKLY INTERACTING CONFIGURATIONS OF HEXAGONAL BORON NITRIDE ON NICKEL

2015 ◽  
Vol 22 (06) ◽  
pp. 1550078 ◽  
Author(s):  
ABBAS EBNONNASIR ◽  
SUNEEL KODAMBAKA ◽  
CRISTIAN V. CIOBANU
Keyword(s):  
Density Functional Theory ◽  
Boron Nitride ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Density Functional Theory Calculations ◽  
Stable Configuration ◽  
Weakly Bound ◽  
Functional Theory ◽  
The Stability ◽  
Insulating Properties

Using density functional theory calculations with van der Waals corrections, we have investigated the stability and electronic properties of monolayer hexagonal boron nitride (hBN) on the Ni (111) surface. We have found that hBN can bind either strongly (chemisorption) or weakly to the substrate with metallic or insulating properties, respectively. While the more stable configuration is the chemisorbed structure, many weakly bound (physisorbed) states can be realized via growth around an hBN nucleus trapped in an off-registry position. This finding provides an explanation for seemingly contradictory sets of reports on the configuration of hBN on Ni (111).

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