scholarly journals Evaluation of the influence of granulation of hexagonal boron nitride on the lubricity properties of the base grease

2020 ◽  
Vol 69 (1) ◽  
pp. 109-128
Author(s):  
Szymon Senyk ◽  
Tadeusz Kałdoński
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Grease Lubrication ◽  
Two Parameters ◽  
Lubricating Properties ◽  
Base Grease ◽  
Grain Diameter

The paper presents the tests results of lubricity properties of base greases, containing hexagonal boron nitride (h-BN). To conduct the required tests, a four ball machine was used. This device is commonly used when assessing lubricity properties of oils and greases. The following normative lubricity parameters were defined: welding point Pz [daN], the value of last non-seizing load Pn [daN], seizing at smoothy growing load Pt [daN], as well as the wear limiting capacity load Goz [daN/mm2]. Furthermore, several non-normative tests were completed that covered indication of two parameters making it possible to complete an assessment of lubricity properties of oils. Based on the conducted research, it was found that hexagonal boron nitride is an additive that improves the lubricating properties of the base grease. The best effects of the improvement, taking into account the adopted tribological criteria, were noted for a sample containing 10% (m/m) hexagonal boron nitride with an average grain diameter of 65÷75 nm. It was found that the lower granulation of the additive (h-BN) positively influences the efficiency of the grease lubrication of the base, under the conditions of tests on a four-ball model apparatus. Keywords: tribology, lubricity, boron nitride, greases

scholarly journals Research on lubricity of oils containing the hexagonal boron nitride

2019 ◽  
Vol 68 (1) ◽  
pp. 131-151
Author(s):  
Szymon Senyk ◽  
Maciej Perehubka ◽  
Tadeusz Kałdoński
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Test Results ◽  
Negative Effects ◽  
Hydraulic Oil ◽  
Base Oils ◽  
Gear Oil ◽  
Two Parameters

The paper presents the test results of lubricity properties of Hydrol L-HL 32 hydraulic oil, Mobilube 1 SHC 75w-90 gear oil, and two base oils: SN-150 and SN-650, containing hexagonal boron nitride. To conduct the required tests, a four ball machine was used. This device is commonly used when assessing lubricity properties of oils and greases. The following normative lubricity parameters were defined: the value of welding point Pz [daN], the value of last non-seizing load Pn [daN], the value of seizing at smoothy growing load Pt [daN], as well as the wear limiting capacity load Goz [daN/mm2]. Furthermore, several non-normative tests were completed that covered indication of two parameters making it possible to complete an assessment of lubricity properties of oils. Based on the tests, it was determined that hexagonal boron nitride is a good additive that improves lubricity properties. Improvement in the above properties was recorded both in the case of hydraulic oil and gear oil, as well as oil bases. Relatively better improvement results were obtained in the case of oil bases, where the improvement in the results after using boron nitride, was more visible than in the case of hydraulic and gear oil. The best improvement results for hydraulic oil were obtained after adding 4% h-BN, whereas in the case of the SN-150 oil base, this value was 2% h-BN. The best improvement results for gear oil and SN-650 oil base were also obtained after adding 4% h-BN. The possibility of using the values of h-BN bigger than 4% was excluded. It was determined that bigger content of h-BN in oil generates negative effects (under four ball conditions). Keywords: tribology, lubricity, boron nitride.

Marcus-Hush Theory Revealed by Electron Tunneling Through Hexagonal Boron Nitride

2019 ◽  
Author(s):  
Matěj Velický ◽  
Sheng Hu ◽  
Colin R. Woods ◽  
Peter S. Toth ◽  
Viktor Zólyomi ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Boron Nitride ◽  
Electron Tunneling ◽  
Hexagonal Boron Nitride ◽  
Large Body ◽  
Liquid Solution ◽  
Limiting Current ◽  
Electron Transfer Rate Constant ◽  
Electrochemical Parameters ◽  
Voltammetric Measurements

Marcus-Hush theory of electron transfer is one of the pillars of modern electrochemistry with a large body of supporting experimental evidence presented to date. However, some predictions, such as the electrochemical behavior at microdisk electrodes, remain unverified. Herein, we present a study of electron tunneling across a hexagonal boron nitride barrier between a graphite electrode and redox levels in a liquid solution. This was achieved by the fabrication of microdisk electrodes with a typical diameter of 5 µm. Analysis of voltammetric measurements, using two common redox mediators, yielded several electrochemical parameters, including the electron transfer rate constant, limiting current, and transfer coefficient. They show a significant departure from the Butler-Volmer behavior in a clear manifestation of the Marcus-Hush theory of electron transfer. In addition, our system provides a novel experimental platform, which could be applied to address a number of scientific problems such as identification of reaction mechanisms, surface modification, or long-range electron transfer.

scholarly journals Self-Sensitization and Photo-Polymerization of Diacetylene Molecules Self-Assembled on a Hexagonal-Boron Nitride Nanosheet

Polymers ◽  
2018 ◽  
Vol 10 (2) ◽  
pp. 206 ◽  
Author(s):  
Elisseos Verveniotis ◽  
Yuji Okawa ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
Takaaki Taniguchi ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Photo Polymerization ◽  
Boron Nitride Nanosheet ◽  
Self Assembled

scholarly journals First-Principles Identification of Single Photon Emitters Based on Carbon Clusters in Hexagonal Boron Nitride

2021 ◽  
Vol 125 (6) ◽  
pp. 1325-1335 ◽  
Author(s):  
Cesar Jara ◽  
Tomáš Rauch ◽  
Silvana Botti ◽  
Miguel A. L. Marques ◽  
Ariel Norambuena ◽  
...  
Keyword(s):  
Boron Nitride ◽  
First Principles ◽  
Single Photon ◽  
Hexagonal Boron Nitride ◽  
Carbon Clusters ◽  
Single Photon Emitters

scholarly journals Stimulated Emission Depletion Microscopy with Color Centers in Hexagonal Boron Nitride

ACS Photonics ◽  
2021 ◽  
Author(s):  
Prince Khatri ◽  
Ralph Nicholas Edward Malein ◽  
Andrew J. Ramsay ◽  
Isaac J. Luxmoore
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Stimulated Emission ◽  
Color Centers ◽  
Stimulated Emission Depletion

scholarly journals Creation of Negatively Charged Boron Vacancies in Hexagonal Boron Nitride Crystal by Electron Irradiation and Mechanism of Inhomogeneous Broadening of Boron Vacancy-Related Spin Resonance Lines

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1373
Author(s):  
Fadis F. Murzakhanov ◽  
Boris V. Yavkin ◽  
Georgiy V. Mamin ◽  
Sergei B. Orlinskii ◽  
Ivan E. Mumdzhi ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Electron Irradiation ◽  
Near Infrared ◽  
Hexagonal Boron Nitride ◽  
Optical Excitation ◽  
High Energy ◽  
Infrared Range ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Spin Resonance

Optically addressable high-spin states (S ≥ 1) of defects in semiconductors are the basis for the development of solid-state quantum technologies. Recently, one such defect has been found in hexagonal boron nitride (hBN) and identified as a negatively charged boron vacancy (VB−). To explore and utilize the properties of this defect, one needs to design a robust way for its creation in an hBN crystal. We investigate the possibility of creating VB− centers in an hBN single crystal by means of irradiation with a high-energy (E = 2 MeV) electron flux. Optical excitation of the irradiated sample induces fluorescence in the near-infrared range together with the electron spin resonance (ESR) spectrum of the triplet centers with a zero-field splitting value of D = 3.6 GHz, manifesting an optically induced population inversion of the ground state spin sublevels. These observations are the signatures of the VB− centers and demonstrate that electron irradiation can be reliably used to create these centers in hBN. Exploration of the VB− spin resonance line shape allowed us to establish the source of the line broadening, which occurs due to the slight deviation in orientation of the two-dimensional B-N atomic plains being exactly parallel relative to each other. The results of the analysis of the broadening mechanism can be used for the crystalline quality control of the 2D materials, using the VB− spin embedded in the hBN as a probe.

Sign in / Sign up

Export Citation Format

Share Document