Search

Copyright of Transactions of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ball bearings face numerous challenges under harsh operating conditions of elevated pressure between the balls and other contacting parts of the bearing like drop in tribological properties. To address these challenges, this paper presents the first successful experimental investigation of incorporating an innovative hexagonal boron nitride (h-BN) into Aluminum-Carbon nanotube (Al-0.6 wt% CNTs) nanocomposites. This was achieved using electroless chemical deposition technique to coat the materials with silver (Ag) and nickel (Ni), improving the wettability and dispersion between the matrix and reinforcement. Various h-BN ratios (2, 4, 6, 8 and 10 wt%) are incorporated and consolidated through high-energy ball milling and hot compaction techniques. The produced samples were tested and analyzed physically, mechanically, tribologically, and microstructurally. X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses were used to explore the new morphologies and structures. The study delves into density, hardness, and wear resistance. The optimal h-BN content is determined to be 8 wt%, enhancing wettability and dispersion within the Al-CNTs matrix. Thus, the properties of hardness, compressive strength, wear rate, and COF at 8 wt% of h-BN content were enhanced by 105%, 60%, 74.5%, and 78.5%, respectively, compared to pure Al. This is due to the uniform scattering of h-BN nanoparticles across the entire surface, despite a significant decrease in relative density. In conclusion, the combination of mechanical alloying, electroless deposition, and hot compaction techniques proves to be effective in producing Al-CNTs/h-BN nanocomposites coated with Ag and Ni nanoparticles. [ABSTRACT FROM AUTHOR]

Purpose: Concerns over the pollution caused by internal combustion vehicles have increased owing to population and industrialization increment. Addressing the confrontations, the demand for electric vehicles (EVs) as a combustion engine substitute became necessary in responding to environmental worries from internal combustion. The development of bio lubricant in lubricating the sliding parts of EVs is required to maintain the sustainability idea and to improve the system performance, which this research tends to explore. Design/methodology/approach: In this research, the enhancement of base Jatropha oil was done using polytetrafluoroethylene (PTFE) and hexagonal boron nitrate (h-BN) as additives. Different characterization was conducted on the new formulation to ascertain its anticorrosion tendency. The wear and friction behavior of the formulations on the tribo-pairs surfaces in contact were investigated using ball on flat tribometer to determine their tribological responsiveness as mineral lubricant alternative. To explore the surface topography, surface profilometer, scanning electron microscope and energy dispersive X-ray investigations were PTFE, lubrication and EV carried out. Findings: The test's input parameters were EVs' usual load and sliding speed, and the addition concentrations for PTFE were 0.3 Wt.%, 0.4 Wt.%, 0.5 Wt.% and 0.6 Wt.%, whereas h-BN were 0.4 Wt.%, 0.8 Wt.% and 1.2 Wt.%, respectively. The study on corrosion demonstrated resistance when applied PTFE and h-BN additives in Jatropha oil. The analysis revealed that 0.5 Wt.% PTFE + 0.8 Wt.% h-BN concentrations significantly improved the tribological characteristics when compared to the base Jatropha oil. The application of formulations yielded percentage reduction of 8.67%, 10.98%, 7.34% and 7.35%, respectively, for 0.5% poly + 0.5% h-BN, 0.5% poly + 0.6% h-BN, 0.5% poly + 0.7% h-BN, 0.5% poly + 0.8% h-BN against base Jatropha oil under 20 N. Originality/value: The formulation of PTFE and h-BN for electric transmission with wear and friction effects was accomplished in this paper. The mechanism of particle diffusing at the sliding contact on tribological behavior could be examined based on the created model of operation. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2023-0235/ [ABSTRACT FROM AUTHOR]

The h-BN/diamond mix-dimensional heterostructure has broad application prospects in the fields of optoelectronic devices and power electronic devices. In this paper, the electronic properties and band offsets of hexagonal boron nitride (h-BN)/(H, O, F, OH)-diamond (111) heterostructures were studied by first-principles calculations under biaxial strain. The results show that different terminals could significantly affect the interface binding energy and charge transfer of h-BN/diamond heterostructure. All heterostructures exhibited semiconductor properties. The h-BN/(H, F)-diamond systems were indirect bandgap, while h-BN/(O, OH)-diamond systems were direct bandgap. In addition, the four systems all formed type-II heterostructures, among which h-BN/H-diamond had the largest band offset, indicating that the system was more conducive to the separation of electrons and holes. Under biaxial strain the bandgap values of the h-BN/H-diamond system decreased, and the band type occurred direct–indirect transition. The bandgap of h-BN/(O, F, OH)-diamond system increased linearly in whole range, and the band type only transformed under large strain. On the other hand, biaxial strain could significantly change the band offset of h-BN/diamond heterostructure and promote the application of this heterostructure in different fields. Our work provides theoretical guidance for the regulation of the electrical properties of h-BN/diamond heterostructures by biaxial strain. [ABSTRACT FROM AUTHOR]

Materials that exhibit both strong covalent and weak van der Waals interactions pose a considerable challenge to many computational methods, such as DFT. This makes assessing the accuracy of calculated properties, such as exfoliation energies in layered materials like hexagonal boron nitride (h‐BN) problematic, when experimental data are not available. In this paper, we investigate the accuracy of equilibrium lattice constants and exfoliation energy calculation for various DFT‐based computational approaches in bulk h‐BN. We contrast these results with available experiments and reference fixed‐node diffusion quantum Monte Carlo (QMC) results. From our reference QMC calculation, we obtained an exfoliation energy of −33±2 meV/atom (‐0.38±0.02 J/m2). [ABSTRACT FROM AUTHOR]

The AlN/BN composite ceramic, fabricated via hot-press sintering, exhibits obvious anisotropy due to the establishment of directional alignment of h-BN. However, the variation and influence mechanisms of bending strength (σ) and thermal conductivity (λ) are remain unclear in different directions, which greatly limit the application of AlN/BN composite ceramics. In this paper, the effects of h-BN content on phase composition, microstructure and anisotropy of AlN/BN composite ceramics are discussed in detail. The results reveal that AlN/BN composite ceramics have three directions: perpendicular (⊥), longitudinal parallel (∥), and lateral parallel (≡) to the hot-pressing direction. The content of h-BN is a crucial factor affecting the anisotropy of AlN/BN composite ceramics. h-BN enhances the thermal conductivity in the ∥ and hinders the thermal conductivity in the ⊥. With the increase in h-BN amount, λ ∥ rises gradually, while λ ⊥ gradually falls. When the mass percentage of h-BN and AlN is 25 % (AB25), the λ ∥ is as high as 90 W m−1 K−1, which is about 2.25 times that of λ ⊥. In terms of mechanical properties, σ ≡ and σ ⊥ first increase and then decrease, while σ ∥ only decreases. This is attributable to h-BN being effective in enhancing mechanical properties by inhibiting crack propagation in the ⊥ and ≡ direction, while the promotion of crack propagation leads to a decrease in mechanical properties in the ∥ direction. σ ≡ reaches the highest values (σ ≡ = 460.2 MPa) at an h-BN amount of 10 % (AB10), which is about 1.19 and 2.04 times that of σ ⊥ and σ ∥ , respectively, and 22.1 % higher than that of AB0. [ABSTRACT FROM AUTHOR]

In order to improve the performance of polymer-derived ceramics and expand its application field, the formulation of the photosensitive resin was further optimized and on the basis of modification, the two-dimensional filler h -BN was introduced in this paper. It was found that both the content of PVSA in the photosensitive resin and the introduction of h -BN had remarkable impacts on the properties of the polymer-derived ceramics. When the h -BN content in the PVSA photosensitive resin was 1 wt%, the bending strength and fracture toughness of the ceramic sample after pyrolysis reached 252.4 ± 12.2 MPa and 2.7 ± 0.2 MPa·m1/2, respectively. With the increase of h -BN content, the thermal conductivity of the composite ceramics increased from 0.44 W·m−1·K−1 to 5.34 W·m−1·K−1. It is concluded that the thermal, electrical, and mechanical properties of precursor ceramics are improved by the introduction of two-dimensional fillers of h -BN. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an ideal dielectric substrate and protective packaging material for two-dimensional (2D) materials, high-quality hexagonal boron nitride (h-BN) films have attracted much attention. Previous studies have achieved high-quality h-BN on a Ni substrate due to its catalytic activity and B solubility. In this paper, a Ni-B alloy was utilized as a catalytic substrate and B source in the h-BN growth procedure. The growth of h-BN on a sapphire surface was achieved by a two-step growth–transfer method. The thickness of h-BN thin films is controlled by changing the growth time. Raman spectra show that the full width at half-maximum of E2g mode is 8.91 cm−1, which is much lower than most other chemical vapor deposition-grown h-BN. This provides a method for preparing high-quality h-BN and other layered 2D materials on an insulating substrate. [ABSTRACT FROM AUTHOR]

Two-dimensional hexagonal boron nitride (h-BN) materials have garnered increasing attention due to its ability of hosting intrinsic quantum point defects. This paper presents a photoluminescence (PL) mapping study related to sub-bandgap-level emission in bulk-like multilayer h-BN films. Spatial PL intensity distributions were carefully analyzed with 500 nm spatial resolution in terms of zero phonon line (ZPL) and phonon sideband (PSB) emission-peaks and their linewidths, thereby identifying the potential quantum point defects within the films. Two types of ZPL and PSB emissions were confirmed from the point defects located at the non-edge and edge of the films. Our statistical PL data from the non-edge- and edge-areas of the sample consistently reveal broad and narrow emissions, respectively. The measured optical properties of these defects and the associated ZPL peak shift and line broadening as a function of temperature between 77° and 300° K are qualitatively and quantitatively explained. Moreover, an enhancement of the photostable PL emission by at least a factor of ×3 is observed when our pristine h-BN was irradiated with a 532 nm laser. [ABSTRACT FROM AUTHOR]

In the paper, we have theoretically studied the adsorption of a hydrogen molecule on hexagonal boron nitride (h-BN), boron-rich h-BN, and the h-BN/graphene heterostructure by using standard GGA PBE as well as dispersion-corrected PBE-D3 and B3LYP-D3 density functionals. The coronene molecule (C24H12) has been adopted as a graphene model system. As the h-BN structure we use B12N12H12 model. As the boron rich models, we involve B13N11H12, B14N10H12, and B15N9H12. For the h-BN/graphene heterostructure we use the C18B3N3H12 model. It has been founded that the dispersion interactions make an important contribution to the hydrogen adsorption energy (Ea). For h-BN, the step-by-step substitution of nitrogen with boron atoms modifies Ea values. However, these changes are rather moderate. All three methods used predict the considerable increase in Ea for the h-BN/graphene heterostructure, especially when the horizontal configuration is considered. The results of this work indicate that the introduction of the small amount of atoms with different electronegativities in one adsorbent structure may substantially increase Ea, but the increment is strongly dependent on the configuration of the interacting species. We believe that some of the considerations, derived in our work, will contribute to a deeper insight into hydrogen adsorption phenomena and development of new materials for hydrogen storage. [ABSTRACT FROM AUTHOR]

Synaptic device is an important component in artificial neural networks. Electrically‐controlled long‐term depression (LTD) is demonstrated in three‐terminal photonic synaptic devices, which is useful for improving the efficiency of artificial neural networks. The mechanism of the three‐terminal photonic synaptic device is similar to that of the photo‐induced doping effect. Photo‐assisted carrier transport and recombination are expected to accelerate the LTD process. However, the effects of photon illumination on LTD are not investigated. Here, the effects of electrical stimulation and photo‐stimulation on the long‐term plasticity (LTP) and LTD process of photonic synaptic devices based on MoS2/h‐BN field‐effect transistors (FETs) are systemically investigated. The influences of gate dielectric layer on the photo‐induced doping are explored. The non‐volatile and electrically‐erasable properties of photo‐induced doping in MoS2/h‐BN FETs are due to the van der Waals energy barrier at the MoS2/h‐BN interface. The synaptic functions of LTP and LTD can be mimicked by the photo‐induced doping effect. The LTD process will be accelerated with the applications of positive gate voltage and laser illumination, which improves the speed of information processing. These results presented in this paper are useful for realizing high‐performance synaptic devices based on the photo‐induced doping effect. [ABSTRACT FROM AUTHOR]

The objective of this paper is to propose constructing a 2D ordinal fillers structure to improve the breakdown strength of BN/ER. By loading ferrite on the fillers and applying a rotating magnetic field during curing process, epoxy composites with tiled structure of plate-type BN are obtained. Considering the side effect of ferrite on the insulation properties, its minimum load under the premise of implementing the tiled structure is determined, accordingly the composite materials with breakdown strength about 30% higher than that of traditional BN/ER is obtained. Furthermore, the technological parameters of magnetic treatment is analyzed quantitatively, and a meso-scopic finite element model of BN/ER is built to further discuss the enhancing mechanism of breakdown strength brought by the filler tiled structure. [ABSTRACT FROM AUTHOR]

• Coaxial powder feeding laser cladding was applied for the fabrication of 316L stainless steel/h-BN composite coating. • The incorporation of h-BN enhances grain refinement, leading to a significant increase in microhardness. • The wear surfaces of 316L/BN composite coating display smooth appearance, demonstrating milder abrasive and adhesive wear. • The h-BN nanoparticles serve as effective solid lubricants, significantly reducing wear and enhancing coating performance. This paper presents the fabrication and characterization of self-lubricating, anti-wear 316L stainless steel composite coatings on a Q235 substrate using 316L stainless steel powders and nanoscale hexagonal boron nitride (h-BN) ceramic particles via coaxial powder feeding laser cladding. The influence of process parameters on cladding quality and geometry, and the impact of h-BN contents (2 wt% and 5 wt%) on the microstructure and mechanical properties of the coatings were studied. Optimal process parameters for 316L/5wt%BN coatings were identified: a powder feeding rate of 3–4 rpm, a laser power of 2200–2400 W, a scanning speed of 4–5 mm/s, and an overlapping rate of 40 %. Microstructural analysis showed a smooth surface without cracks or pores. X-ray diffraction revealed intermetallic compounds such as CrB, Cr 2 N, Fe 3 N, BN, and γ-(Fe, Ni). The inclusion of h-BN nanoparticles enhanced grain refinement, significantly increasing microhardness. Coatings with 5 wt% h-BN achieved an average microhardness of 438.8 HV10, 2.5 times higher than the substrate and the 316L stainless steel. Additionally, h-BN reduced friction coefficients, leading to substantial wear reduction. The 316L/5 wt% h-BN sample experienced only 4.2 mg of wear, 45.16 % of the substrate's wear. These findings highlight the beneficial effects of h-BN nanoparticles on 316L stainless steel coatings, enhancing wear resistance, hardness, and overall performance. [ABSTRACT FROM AUTHOR]

Thermal interface materials (TIMs) are prerequisite components of micro- and nano-electronics, as well as advanced semiconductor applications. A bisphenol-A epoxy-based thermal adhesive amalgamated graphene oxide (GO), reduced graphene oxide (rGO), and modified hexagonal boron nitride (h-BN/mh-BN) are fabricated. The advantages of adhesive TIMs compared to other TIMs encompass lower cost, process savings, reduced component weight, and prevention of vibration loosening the high-end electronics. Additionally, some parts are not suitable for soldering, as they may lack "legs" that go through holes in the PCBs, and adhesive TIMs help prevent short circuits. The thermal conductivity (TC) is measured at 1.653 ± 0.057 W/mK when incorporating 44.5 wt% mh-BN hybrid rGO into the epoxy matrix. However, substituting rGO with GO reduced the TC to 0.81 ± 0.0289 W/mK due to the lower phonon transfer of GO compared to rGO. The binding strength, in terms of lap shear, of the utmost TC composite adhesive was within the range of 6.26 ± 0.48 MPa, which is acceptable for effective end applications. The thermal stability of both optimized composites (mh-BN/rGO and mh-BN/GO) has demonstrated better results beyond 280 °C. The highest TC epoxy nanocomposite, termed mh-BN/rGO4/epoxy, also revealed electrical insulation properties. [ABSTRACT FROM AUTHOR]

Cobalt-based self-lubricating coatings with the addition of NbC and h-BN were prepared by means of laser cladding on a die steel (Cr12MoV) substrates, aiming at their implementation in metal forming applications involving demanding friction reduction and anti-wear. The effect of different amounts of h-BN with constant content NbC (30 wt%) on the microstructure of the laser-clad Stellite 6 alloy was probed through measures of XRD, SEM, EDS and EBSD. Microhardness, wear properties, and antifriction mechanism of the self-lubricating coatings were also discussed as well. The results proved that with an increase in h-BN content, in addition to NbC phase with polygonal shape observed in the h-BN-free Stellite 6/NbC coating, Nb(C, B) interstitial compounds having multiple grain orientations were formed in inter equiaxed crystal regions. Following the microstructural characterization, the tribological behavior and micro-hardness were analyzed. The results exhibit considerably better anti-friction properties of Stellite 6/NbC/h-BN coating compared to subtract and its excellent tribological performance could be reflected by data of friction test. The lubrication effect of h-BN is proved by the reduction in coefficient of friction. Meantime, the addition of NbC helps in improving micro-hardness and anti-wear. The NbC solidification-growth was detailly discussed in the paper. • In paper, Stellite 6/NbC/h-BN composite coatings on Cr12MoV were fabricated by laser cladding. • The solidification-growth process of Nb(C, B) interstitial compounds is discussed in detail. • h-BN, Nb(C, B) and Cr 23 C 6 contribute to improve wear resistance and reduce friction coefficient. • The coating (Stellite 6 + 30% NbC + 10% h-BN) exhibits extremely microhardness with 752 HV 0.2. [ABSTRACT FROM AUTHOR]

This paper presents improved performance of Double Gate Graphene Nanomesh Field Effect Transistor (DG-GNMFET) with h-BN as substrate and gate oxide material. The DC characteristics of 0.95m and 5nm channel length devices are studied for SiO2 and h-BN substrate and oxide material. For analyzing the ballistic behavior of electron for 5nm channel length, von Neumann boundary condition is considered near source and drain contact region. The simulated results show improved saturation current for h-BN encapsulated structure with two times higher on current value (0.375 for SiO2 and 0.621 for h-BN) as compared to SiO2 encapsulated structure. The obtained result shows h-BN to be a better substrate and oxide material for graphene electronics with improved device characteristics. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN), as a two-dimensional lamellar material, has been paid more and more attention in the field of corrosion protection because of its excellent thermal stability, chemical stability and insulation. In order to solve the problem that h-BN is difficult to disperse in resin, inspired by the adhesion ability of mussel secretions, the surface of h-BN was modified with polydopamine (PDA) to improve the dispersion of the fillers in epoxy resin, and the prepared corrosion inhibition CeO 2 nanoparticles were loaded on the surface. A functional filler CeO 2 &PDA/h-BN with corrosion inhibition effect was prepared. The surface morphology, chemical structure and thermal stability of functional fillers were analyzed by SEM, FTIR, XRD and thermogravimetric analysis. The test results show that after 40 days of testing, the low-frequency impedance modulus of the epoxy composite coating is 15 times that of the pure epoxy resin, and the wear resistance properties also significantly improved. The anti-corrosion mechanism of the composite coating is analyzed, and the synergistic effect of h-BN's barrier ability and CeO 2 's corrosion inhibition ability is revealed. This paper provides an idea for the preparation of multifunctional h-BN composite anticorrosive filler. [Display omitted] • The nanoscale corrosion inhibitor CeO 2 was synthesized successfully. • Prepared anti-corrosion filler CeO 2 &PDA/h-BN was by biomimetic material. • The corrosion inhibition capacity of the filler is as high as 73.20 %. • The composite coating showed excellent anti-corrosion effect. [ABSTRACT FROM AUTHOR]

Previous work that studied hexagonal boron nitride (h‐BN) memristor DC resistive‐switching characteristics is extended to include an experimental understanding of their dynamic behavior upon programming or synaptic weight update. The focus is on the temporal resistive switching response to driving stimulus (programming voltage pulses) effecting conductance updates during training in neural network crossbar implementations. Test arrays are fabricated at the wafer level, enabled by the transfer of CVD‐grown few‐layer (8 layer) or multi‐layer (18 layer) h‐BN films. A comprehensive study of their temporal response under various conditions–voltage pulse amplitude, edge rate (pulse rise/fall times), and temperature–provides new insights into the resistive switching process toward optimized devices and improvements in their implementation of artificial neural networks. The h‐BN memristors can achieve multi‐state operation through ultrafast pulsed switching (< 25 ns) with high energy efficiency (≈10 pJ pulse−1). [ABSTRACT FROM AUTHOR]

The layered van derWaals (vdW) heterostructure, assembled from monolayer graphene, hexagonal boron nitride (h-BN) and other atomic crystals in various combinations, is emerging as a new paradigm with which to attain desired electronic and optical properties. In this paper, we study theoretically the mid-infrared optical properties of the vdW heterostructure based on the graphene-h-BN system. The light-matter interaction of this heterostructure system is described by the hyperbolic phonon-plasmon polaritons which originate from the coupling modes of surface plasmon polaritons (SPPs) in graphene with hyperbolic phonon polaritons (HPPs) in h-BN. By numerical simulation, we find that the coupling modes are governed by the Fermi level of monolayer graphene, the thickness of the h-BN slab and the mode excitation sequence of SPPs and HPPs. Moreover, the response of the coupling modes of the graphene-h-BN heterostructure on a noble metal layer is also proposed in this paper. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) has a typical two-dimensional flake structure, so the anisotropy of h-BN grains caused by directional arrangement cannot be ignored when studying the thermal vibration resistance of materials under thermal cycling. In this paper, h-BN-matrix textured ceramics prepared with different holding time were selected, and the effects of thermal vibration temperature difference and thermal cycles on the phase and thermal vibration resistance of h-BN-matrix textured ceramics were studied. The results show that under the condition of high-frequency thermal cycling, the residual strength ratio (RSR) of BN-based textured ceramics is closely related to the holding time and showing obvious anisotropy. At the same time, there is a thermal vibration temperature range in which the internal stress will change from relief to re-accumulation. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Micro-arc oxidation (MAO) coatings of aluminum alloy have great potential applications due to their high hardness and wear resistance. However, the micro-pores and defects formed in the discharge channels during the MAO process limit its application in the corrosion field. This study delves into the impact of h-BN nanoparticles into MAO coatings on their structure, corrosion resistance, phase composition, and tribological properties. The results show that the incorporation of h-BN particles reduces the porosity and surface roughness of the coating while enhancing its hardness and wear resistance. The best corrosion resistance is obtained at a concentration of 2 g/L h-BN. An analysis of worn surface morphology, corrosion resistance, and friction coefficient change was conducted to evaluate the performance of this coating. This method provides a new approach to enhance the surface hardness and wear resistance of aluminum alloys, which is significant for expanding the application of aluminum alloys in corrosion environments. [ABSTRACT FROM AUTHOR]

In this paper, we prepared and characterized nanocomposites of polyether ether ketone (PEEK) containing hexagonal boron nitride (h-BN) nanofiller from 1 to 5 wt%. Using various techniques, we studied the friction and wear properties, thermal conductivity, morphology, and mechanical and thermomechanical properties of the nanocomposites. Adding h-BN nanoparticles to the PEEK improved the properties of the resulting nanocomposites. At 5 wt% h-BN content, it exhibited optimum improvement of friction and wear properties, thermal conductivity, hardness, and storage modulus. Thus, we demonstrated that PEEK nanocomposites reinforced with h-BN have a great potential as multifunctional materials for future industrial applications. [ABSTRACT FROM AUTHOR]

Hyperbolic materials can be used to excite hyperbolic phonon polaritons in specific frequency bands, which causes abrupt interfaces with fluctuations of permittivity and different transmission characteristics at different incident wavelengths. Using the quasi-static approximation, the filtering characteristics of hexagonal Boron nitride (h-BN) and the transmission characteristics of phonon polaritons waves on a dielectric-h-BN-dielectric structure were studied in the paper. The results show that a smaller relative permittivity of the materials above and below h-BN and a thicker h-BN (ε1 = 1 (air), ε2 = 3.9 (SiO2), d = 100 nm) will lead to better filtering characteristics for different wavenumbers' incident waves (propagation length from 0.0028 μm to 1.9756 μm). Simulation results in COMSOL validated the previous theoretical calculations. Moreover, the transmissivity and 3dB bandwidth of the type-II band were calculated with different structure widths. The maximum transmissivity of ~99% appears at a width of 100 nm, and the minimum 3dB bandwidth reaches 86.35 cm−1 at a structure width of 1300 nm. When the structure width meets or exceeds 1700 nm, the 3dB bandwidth is equal to 0, and its structure length is the limit for the filter application. These characteristics reveal the excellent filtering characteristics of the dielectric-h-BN-dielectric structure, and reveal the great potential of using the dielectric-h-BN-dielectric structure to design optical filter devices with excellent performance in mid-infrared bands. [ABSTRACT FROM AUTHOR]

The paper investigates the effect of hexagonal boron nitride (h-BN) nanoparticles on the tribological and rheological properties of the API-Group I lubricants i.e. Solvent neutral (SN)-500, Bright Stock (BS)-270, and thirdly a mixture of SN-500 and BS-270. The tribological properties of the base oils and the nanolubricants are studied using a four-ball tester and the experiments are carried out as per ASTM D4172 standard. It is observed that the addition of 0.25 wt.% h-BN nanoparticles improves the tribological properties of base oils. The wear scar diameter reduces by 2.51%, 19.78% and 3.17% for SN-500, BS-270, and BS+SN at 0.25 wt% h-BN nanoparticles concentration respectively. The rheological properties of the lubricants are measured on Anton Paar’s MCR 102. BS-270 depicts the maximum viscosity among the Group I oils equal to 289.14 mPa.s at 40 °C. Further, all the oils depict an increase in the dynamic viscosity with an increase in the concentration of nanoparticles. [ABSTRACT FROM AUTHOR]

This paper aims to study the impacts of h-BN additive on the microstructural features and sintering behavior of TiB 2. For this objective, two different samples of monolithic TiB 2 and TiB 2 -5 wt% h-BN were fabricated using spark plasma sintering (SPS) technique at 1900 °C. An external pressure of 40 MPa was exerted to the specimens during the sintering, and they were maintained at the maximum sintering temperature for 7 min. The characterization of as-fabricated ceramics was carried out using thermodynamical investigations, field emission SEM, and X-ray diffractometer. The thermodynamical and XRD studies revealed that the sintering process was non-reactive for both samples. However, introducing h-BN noticeably promoted the sinterability of TiB 2 through activating the liquid phase sintering mechanism, and a near-fully dense composite was attained. The fractographical assessment manifested that the intergranular fracture was the dominant type in both monolithic and h-BN doped specimens. Finally, the quantitative image analysis indicated the role of h-BN in refining the microstructure of the doped TiB 2 ceramic. [ABSTRACT FROM AUTHOR]

The dispersion of hexagonal boron nitride (h-BN) in resin to prepare anti-corrosion coating has only a single physical shielding function, and does not inhibit the electrochemical reaction process, which significantly reduces the durability of anti-corrosion coating. In this paper, polyaniline with anodic passivating function was synthesized on the surface of h-BN by in-situ polymerization, and Ce3+ cation with corrosion inhibition was loaded into polyaniline/h-BN. Thus, a triple functional anti-corrosion filler Ce3+&PANI/h-BN with physical shielding - anode passivation - cathode corrosion inhibition was prepared. The microstructure, crystal form, element distribution, thermal stability and corrosion inhibition ability of the composite filler were characterized. The anti-corrosion, anti-friction and adhesion properties of EP/Ce3+&PANI/h-BN composite coating was investigated. EIS and Tafel test results show that the corrosion inhibition efficiency of Ce3+&PANI/h-BN is 55.5% and 89.67%, respectively. The low-frequency impedance modulus of the composite coating after 40 days of exposure is 13 times that of the pure EP coating, up to 9.79 × 109 ·cm2. The results of salt spray test also show that the barrier ability and anti-corrosion effect of the composite coating are significantly improved compared with the pure EP coating. The wear mass loss of the composite coating is reduced by 43.69% compared with the pure EP coating. This research provides a way to prepare multi-functional, high shielding, wear resistance anti-corrosion fillers to achieve long-term protection of coatings. [Display omitted] • A triple functional anti-corrosion filler was prepared by h-BN, PANI and Ce3+. • The corrosion inhibition capacity of the filler is as high as 55.5%. • Ce3+ ions in the filler are released, inhibiting the cathode reaction. • The triple functional composite coating showed excellent anti-corrosion effect. [ABSTRACT FROM AUTHOR]

The total-ionizing-dose response of few layer MoS2 transistors with ZrO2 or h-BN gate dielectrics is investigated under various bias conditions. Defects in MoS2 and surrounding dielectric layers significantly affect radiation-induced trapping. For devices with ZrO2 dielectrics, much larger negative Vth shifts and peak transconductance degradation are observed for irradiation under negative and ground bias than under positive bias. The h-BN devices exhibit positive threshold voltage shifts under negative-bias irradiation. For both ZrO2 and h-BN passivated devices, the peak transconductance degradation results from charge trapping at the surface of the MoS2 or in nearby oxides. Changes in defect energy distributions of MoS2 FETs during X-ray irradiation are characterized via temperature-dependent low-frequency noise measurements. Density functional theory calculations are performed to provide insight into the pertinent defects. [ABSTRACT FROM AUTHOR]

In this study, we present a fractional factorial design approach for exploring the effects and interactions of key synthesis and electrochemical transfer parameters on the roughness and wettability of hexagonal boron nitride (h-BN) coatings, due to their essential role in biofilm formation. The studied parameters for the synthesis process include precursor mass, growth time, and substrate conditioning, whereas for the transfer process, applied voltage and aqueous medium concentration were studied. Through this polynomial model, we confirmed the strong influence of precursor mass and medium concentration parameters on h-BN surface roughness and its resulting antibiofilm properties. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) is a new type of anti-corrosion coating. However, a large number of studies have shown that defects can significantly reduce the barrier property of h-BN. So how to repair the defect of h-BN is a problem to be solved. In this study, we used the density functional theory of the first principle to calculate the barrier properties of perfect h-BN and the h-BN with various vacancies. The study showed that monolayer h-BN has impermeability to all gas molecules, and vacancies can greatly reduce the barrier ability of h-BN to oxygen molecules. Fortunately, atomic oxygen can block the vacancy site of h-BN by chemical adsorption, thereby reducing the impact of vacancies on h-BN. Compared to the situation before the vacancy repaired, the barrier ability of h-BN to oxygen molecules was greatly increased after being repaired. In addition, the electron cloud density at vacancies after the repair (with) atomic oxygen was also greatly increased. Therefore, atomic oxygen can repair vacancies of h-BN and enhance the barrier ability of the defective h-BN. The research in this paper is of some significance. It is helpful to repair h-BN and evaluate corrosion resistance of h-BN in oxygen-rich or atomic-oxygen-rich environment. [ABSTRACT FROM AUTHOR]

PEEK is being used increasingly often in seals, bushings, bearings, and other moving parts due to its excellent mechanical and tribological properties. Herein, PEEK-based composites were prepared using PI as the organic filler and h-BN and nano-SiO2 particles as the inorganic fillers. There was significant improvement in the tribological properties of PEEK at conditions above the glass transition temperature; the coefficient of friction of +20P/4B/4Si was stabilized at 0.06 at 200 °C and the wear rate was reduced by 60% compared to PEEK. The role played by the thermal conductivity of h-BN and the promotion of friction transfer film by nano-SiO2 in improving the tribological properties of PEEK is illustrated. The modified composites exhibited stable mechanical and tribological properties over a wide temperature range, which is instructive for instrumentation and testing applications in harsh environments. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h‐BN) has received considerable attention, due to its high thermal conductivity and electrical insulation. However, the intrinsic platelike structure with the strong anisotropic property restricts its applications, and it is necessary to synthesize isotropic spherical h‐BN particles (SP‐BNs) with submicron size. Till now, methods to prepare (SP‐BN) still exist problems, such as high oxygen impurities and pollution, generated by the ammonia and pyrolysis of precursors. Here, a relatively green reaction between the restricted template of carbon nanospheres and boron trioxide (B2O3) under elevated temperature is conducted, and the SP‐BNs with an average diameter of 200–300 nm (named Nano‐BN‐s) have been successfully synthesized. Comprehensive scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction characterizations confirm the obtained products are spherical boron nitride. With the analysis of X‐ray photoelectron spectroscopy and Fourier transform infrared, the reaction mechanism is briefly discussed. These results indicate the reaction occurs on the restricted template of carbon nanospheres, and the C atoms are substituted by B and N atoms as the reaction progress, forming the Nano‐BN‐s. What is more, the restricted template method plays a key role in the design and improves h‐BN‐based materials in the future and may also be extended to form other novel materials. [ABSTRACT FROM AUTHOR]

Supercapacitors are regarded as reliable energy storage devices to alleviate the energy crisis and environmental pollution. However, the relatively low capacitance and low energy density limit the practical application of supercapacitors. In this context, boron carbon nitride (BCN) nanomaterials have been extensively studied in the past decade due to their chemical and thermal stability, high mechanical strength, as well as tunable bandgap. The specific capacitance and energy density of supercapacitors can be significantly improved by fabricating nanostructured BCN-based electrode materials. In this review, the recent advances in the application of BCN-based materials in supercapacitors is presented. Strategies such as structure design, porosity/defect engineering, and hybrid nanostructure construction to boost the electrochemical performance of BCN-based materials are provided and, finally, promising research directions for novel energy storage materials are proposed. [ABSTRACT FROM AUTHOR]

The frictional coefficient of LCCS with MIL-PRF-23699 grade lubricant was high, which led to an increase in heat generation and temperature rise of the lubricant in aircraft parts such as the accessory gearbox and engine gearbox. To overcome this, the present study proposed the use of h-BN nanoparticles as an additive with MIL-PRF-23699 grade lubricant. To improve the stability and suspension of the h-BN nanoparticles in the NL, the NL was prepared with h-BN nanoparticles and various surfactants. The properties were evaluated for both BL and NL. The tribological experiments were carried out using a four-ball tester, a shear stability tester, and a Reichert tester. The h-BN NL resulted in a 16% reduction in WSD when compared with the BL. The LWI of h-BN NL was increased by 7.44% compared with BL. In the shear stability test, h-BN NL showed 93% better shear stability than the BL. The CoF was reduced by 13% with the h-BN NL in the Reichert test. The experimental results indicated that the h-BN nanoparticles with MIL-PRF-23699 grade lubricant had better tribological properties for aerospace applications. [ABSTRACT FROM AUTHOR]

In this paper, we investigate stacked 2D graphene layers on hexagonal boron nitride (h-BN). The graphene is obtained by high-quality chemical vapor deposition (CVD) and transferred to the h-BN substrate. We focus our attention on annealing effect at 1040 °C on single graphene layer (SGL) and bilayer graphene (BLG) on h-BN substrate using Raman spectroscopy. Our results show, before annealing, a twist angle θ = 0.63 ° between the SGL and the h-BN substrate and a twist angle 3 ° < θ G 1 G 2 < 8 ° between the two graphene layers of the BLG. After annealing, the analysis of the graphene G and 2D bands show a rotational reorientation of the graphene layer with respect to the h-BN substrate. Raman mapping also shows that the rotational reorientation is spatially dependent. [ABSTRACT FROM AUTHOR]

Fluorescent organic dyes photobleach under intense light. Graphene has been shown to improve the photo-stability of organic dyes. In this paper, we investigated the Raman spectroscopy and photo-bleaching kinetics of dyes in the absence/presence of chemical vapor deposition (CVD)-grown graphene. We show that graphene enhances the Raman signal of a wide range of dyes. The photo-bleaching of the dyes was reduced when the dyes were in contact with graphene. In contrast, monolayer hexagonal boron nitride (h-BN) was much less effective in reducing the photo-bleaching rate of the dyes. We attribute the suppression of photo-bleaching to the energy or electron transfer from dye to graphene. The results highlight the potential of CVD graphene as a substrate for protecting and enhancing Raman response of organic dyes. [ABSTRACT FROM AUTHOR]

Analysis of dense Potassium Sodium Niobate (KNN) ceramic obtained by hot pressing (HP) method at 1100 °C are presented in this paper. The synthesis of KNN-based piezoelectrics meets the following challenges—low density of material, uncontrolled K/Na ratio, multiphase composition and formation of different KNN structures. The classical hot pressing approach results in contamination by carbon originating from graphite molds. The proposed hexagonal Boron Carbide (h-BN) layer between green sample and graphite mold could protect samples from carbon contamination. Additionally, the presence of h-BN may decrease the formation of oxygen vacancies, which allows us to maintain the semiconductor features of the KNN structure. Remaining issues were addressed with the addition of excess Na and Er2O3 doping. The results showed that excess Na addition allowed us to compensate evaporation of sodium during the synthesis and sintering. Er2O3 was added as sintering aid to limit abnormal grain growth caused by h–BN addition. The modification of amount of Na and Er2O3 addition resulted in high purity KNN samples with tetragonal structure and apparent density higher than 97%. Finally, piezoelectric features of prepared dense samples were measured and presented. [ABSTRACT FROM AUTHOR]