Search Results (163)

The aim of the present study is to investigate the influence of Nickel–Hexagonal Boron Nitride (Ni-hBN) nanocomposite coatings, deposited using the pulse reverse current electrodeposition technique. This experimental study focuses on assessing the tribological and corrosion properties of the produced coatings on the SS304 substrate. The microhardness of the as-deposited (AD) sample and heat-treated (HT) sample were 49% and 83.8% higher compared to the control sample. The HT sample exhibited a grain size which was approximately 9.7% larger than the AD sample owing to the expansion–contraction mechanism of grains during heat treatment and sudden quenching. Surface roughness reduced after coating, where the Ni-hBN-coated sample measured a roughness of 0.43 µm compared to 0.48 µm for the bare surface. The average coefficient of friction for the AD sample was 42.4% lower than the bare surface owing to the self-lubricating properties of nano hBN. In particular, the corrosion rate of the AD sample was found to be 0.062 mm/year, which was lower than values reported in other studies. As such, findings from the present study can be particularly beneficial for applications in the automotive and aerospace industries, where enhanced wear resistance, reduced friction, and superior corrosion protection are critical for components such as engine parts, gears, bearings and shafts. Full article

Thermal conductive composite materials have excellent electrical insulation properties, low cost, and are lightweight, making them a promising alternative to traditional electronic packaging materials and enhancing the heat dissipation of integrated circuits. Due to the differences in specific surface area and volume, thermal conductive fillers have poor interface connections between the polymer and/or thermal conductive filler, thereby increasing phonon scattering and affecting thermal conductivity. This article uses bismaleimide resin as the matrix and h-BN as the thermal conductive filler. The evolution laws of thermal conductivity and dielectric properties of thermal conductive composite materials were systematically characterized through multi-scale filler control and gradient filling design. Among them, h-BN with a diameter of 10 μm has the most significant improvement in thermal conductivity. When the filling amount is 40 wt%, the thermal conductivity reaches 1.31 W/(m·K). Full article

Ni–P–WC–BN(h) nanocomposite coatings were fabricated on 20CrMnTi substrates using ultrasonic-assisted pulsed electrodeposition. 20CrMnTi is a low-carbon steel that is commonly used in the manufacturing gears and shaft components. To enhance the wear resistance and extend the service life of such mechanical parts, ultrasonic-assisted pulsed electrodeposition was employed as an effective surface modification technique. The microhardness, phase structure, surface morphology, and wear behavior of the coating were also characterized. An orthogonal experimental design was employed to examine the effects of current density, bath temperature, ultrasonic power, and pulse duty cycle on the microhardness and wear behavior of the coatings, aiming to optimize the deposition parameters. The optimal process combination was identified as a current density of 3 A·dm⁻², a bath temperature of 55 °C, an ultrasonic power of 210 W, and a duty cycle of 0.7. Under these conditions, the coatings exhibited enhanced hardness and wear resistance. Based on the optimized parameters, additional tribological tests were conducted under various operating conditions to further evaluate wear performance. The results showed that the dominant wear mechanisms were chemical wear and adhesive wear. This study offers new insights into the fabrication of high-performance nanocomposite coatings and expands the application scope of ultrasonic-assisted pulsed electrodeposition in multiphase composite systems. Full article

Broad lateral size and thickness distributions impede the application of hexagonal boron nitride nanosheets (BNNSs) as friction modifiers in base oil, although they possess remarkable potential for lubrication performance promotion. In this work, a cascade centrifugation-assisted liquid-phase exfoliation approach was presented to prepare BNNSs from hexagonal boron nitride (h-BN) efficiently and scalably. Subsequently, they were ultrasonically dispersed into gas-to-liquid (GTL) base oil, and their lubrication performance promotion was evaluated by a four-ball tribotester. Tribological tests demonstrated that BNNS possesses excellent friction-reducing and anti-wear properties in GTL. Furthermore, the findings indicate that at a BNNS content of 0.8 wt.%, the system displayed the lowest COF and WSD. Particularly, with an addition of 0.8 wt.% BNNS into GTL, the AFC and WSD are reduced significantly by 40.1% and 35.4% compared to pure base oil, respectively, and the surface roughness, wear depth, and wear volume were effectively reduced by 91.0%, 68.5%, and 76.8% compared to GTL base oil, respectively. Raman, SEM-EDS, and XPS results proved that the outstanding friction-reducing and anti-wear properties of BNNS can mainly be ascribed to the presence of physical adsorption film and tribo-chemical film, which were composed of FeOOH, FeO, Fe₃O₄, and B₂O₃. Full article

h-BN spherical nanoparticles, known as white graphene, have good anti-wear properties, long service life, chemical inertness, and stability, which provide superior lubricating performance as a solid additive item to nanofluids. However, the poor dispersion stability of h-BN nanoparticles in nanofluids is a bottleneck that restricts their application. Currently, to prepare h-BN nanofluids with good dispersion stability, a cold plasma (CP) modification of h-BN nanoparticles is proposed in this study. In this research, h-BN nanofluid with added surfactant (SNL), CP-modified h-BN nanofluid with N₂ as the working gas (CP(N₂)NL), and CP-modified h-BN nanofluid with O₂ as the working gas (CP(O₂)NL) were prepared, separately. The mechanism of the dispersion stability of CP-modified h-BN nanofluid was analyzed using X-ray photoelectron spectroscopy (XPS), and the performance of CP-modified nanofluid was analyzed based on static observation of nanofluid, kinematic viscosity, and heat transfer properties. Finally, friction and wear experiments were conducted to further analyze the tribological performance of h-BN nanofluids based on the coefficient of friction, 3D surface morphology, surface roughness (Sa), scratches, and micro-morphology. The results show that CP-modified h-BN nanofluid has excellent dispersed suspension stability and can be statically placed for more than 336 h. The CP-modified h-BN nanofluid showed stable friction-reducing, anti-wear, and heat transfer performance, in which the coefficient of friction of h-BN nanofluid was about 0.66 before and after 24 h of settling. The Sa value of the sample was reduced by 31.6–49.2% in comparison with pure cottonseed oil (CO). Full article

This study investigates the influence of hexagonal boron nitride (h-BN) particle size and concentration on the tribological performance of lithium and calcium greases. Formulations containing h-BN nanoparticles and microparticles at 1%, 3%, 5%, and 10% by weight were evaluated in ball-on-flat reciprocating tests under three load conditions. The tests were conducted using a steel ball and a steel plate. The most favorable results were obtained for greases with 3% h-BN, characterized by an average particle size of 130 nm and the highest nanoparticle content. In lithium grease, this formulation reduced friction by up to 9.7% and wear by up to 69.2% compared to the base grease. In calcium grease, the same additive concentration led to reductions of up to 18.2% in friction and 70.2% in wear. Tribological performance was significantly influenced by the type of base grease, which affected the dispersion of the additive and its ability to form protective surface layers. SEM/EDS analysis of the surfaces after testing revealed that the dominant lubrication mechanisms included shearing-sliding and surface-mending effects. This study confirms that h-BN—especially in nanoparticle form—is an effective additive for improving the performance of greases. Full article

Pharmaceutical contamination of water sources has become a critical environmental challenge. Bentonite (BN), a natural clay mineral, has gained attention due to its high surface area, cation exchange capacity, and cost-effectiveness, making it a promising adsorbent for removing contaminants. This study explores the potential of BN and its acid-treated form (BA1) as effective adsorbents for the removal of tetracycline hydrochloride (TC) from aqueous solutions. Comprehensive characterization was performed using analytical techniques, including XRF, XRD, SEM/TEM, XPS, TG/DTG, and CO₂ and N₂ adsorption–desorption isotherms. The results indicate that BA1 is a mesoporous material with a surface area exceeding 165 m²·g⁻¹. The adsorption process was fitted to a pseudo-second-order kinetic model. BA1 achieved a maximum adsorption capacity of 40.98 mg·g⁻¹ and removal efficiency of up to 99% within only 30 min at an optimal pH of 5. Equilibrium isotherm calculations for BA1 show the best fit for the Freundlich model R² > 0.9923, indicating a favorable adsorption process. The material was reused over seven consecutive cycles to evaluate the regeneration capacity of the clay mineral materials. BN stands out for its effectiveness, cost-effectiveness, and environmental sustainability as a promising material for water treatment applications. Full article

To significantly improve the tribological performance of epoxy resin (EP), a novel h-BN/MoS₂ composite was successfully synthesized using spherical MoS₂ particles with lamellar self-assembly generated through the calcination method, followed by utilizing the “bridging effect” of a silane coupling agent to achieve a uniform and vertically oriented decoration of hexagonal boron nitride (h-BN) nanosheets on the MoS₂ surface. The chemical composition and microstructure of the h-BN/MoS₂ composite were systematically investigated. Furthermore, the enhancement effect of composites with various contents on the frictional properties of epoxy coatings was studied, and the mechanism was elucidated. The results demonstrate that the uniform decoration of h-BN enhances the chemical stability of MoS₂ in friction tests, and the MoS₂ prevents oxidation and maintains its self-lubricating properties. Consequently, due to the protective effect of h-BN and the synergistic interaction between h-BN and MoS₂, the 5 wt % h-BN/MoS₂ composite exhibited the best friction and wear resistance when incorporated into EP. Compared to pure EP coatings, its average friction coefficient and specific wear rate (0.026 and 1.5 × 10⁻⁶ mm³ N⁻¹ m⁻¹, respectively) were significantly reduced. Specifically, the average friction coefficient decreased by 88% and the specific wear rate decreased by 99%, highlighting the superior performance of the h-BN/MoS₂-enhanced epoxy composite coating. Full article

Ultraviolet (UV) photodetectors play a crucial role in various applications, ranging from environmental monitoring to biomedical diagnostics. This paper presents the fabrication and characterization of a high-performance UV photodetector using hexagonal boron nitride (hBN) decorated with gold nanoparticles (AuNPs). The hBN flakes were mechanically exfoliated onto SiO₂ substrates, and AuNPs were formed via thermal evaporation, resulting in the creation of a plasmonically active surface that enhanced light absorption and carrier dynamics. Raman spectroscopy, transmission electron microscopy, and electrical measurements were performed to comprehensively analyze the device structure and performance. The photodetector exhibited significantly improved photocurrent and responsivity under UV-B (306 nm) and UV-C (254 nm) illumination, with the responsivity reaching an increase of nearly two orders of magnitude compared to that of the pristine hBN device. These improvements are attributed to the synergistic effects of the wide bandgap of hBN and the localized surface plasmon resonance of the AuNPs. These findings demonstrate the potential of AuNP-decorated hBN for advanced UV photodetection applications and provide a pathway toward more efficient and miniaturized optoelectronic devices. Full article

Green sustainable solvents have emerged as promising alternatives to petroleum-derived options, such as toluene. This study demonstrates the use of cyrene as an effective exfoliation medium for graphene nanoplatelets (GNPs) and hexagonal boron nitride (hBN) and molybdenum disulfide (MoS₂) particles. The incorporation of polyvinylpyrrolidone (PVP) attenuates the shear-thinning behavior of GNP and hBN suspensions, maintaining a constant shear viscosity over a wide range of shear rates regardless of PVP molecular weight. Despite the presence of polymer, elasticity is hindered by inertia effects, making it impossible to accurately measure the extensional relaxation time in the capillary breakup extensional rheometer (CaBER). Assuming the weak elasticity of the formulations has a negligible impact on the breakup mechanism, we estimated droplet sizes for drop-on-demand (DoD) inkjet printing and electrohydrodynamic (EHD) jet printing based on fluid properties, i.e., viscosity, surface tension and density, and nozzle inner diameter ($D_{nozzle}$). Results indicate that the droplet size ratio ($D_{drop}/D_{nozzle}$) in DoD printing can be up to two orders of magnitude higher than the one predicted for EHD jet printing at the same flow rate. This work highlights the potential of cyrene-based 2D inks as eco-friendly alternatives for advanced printing technologies. Full article

The stacking of two-dimensional atomic-level thickness materials onto hexagonal boron nitride (h-BN) and graphene (Gr) not only significantly enhances their properties, but also exhibits a multitude of exceptional characteristics, promising widespread applications across various fields. Clay minerals hold profound significance in scientific research not only because of their abundance but also because of their application in geology, environmental science, materials science, and biotechnology. We present a study that uses density functional theory (DFT) to analyze the effect on the mechanical properties of lizardite slab-reinforced Gr or h-BN monolayers. In addition to the reference lizardite slab (Liza-2D), six composites were studied: a monolayer of Gr (h-BN) over the octahedral face of a pristine lizardite slab (Liza-Gr1 (Liza-BN1)), a monolayer of Gr (h-BN) under the tetrahedral face of a pristine lizardite slab (Liza-Gr2(Liza-BN2)), and a pristine lizardite slab sandwiched between two Gr (h-BN) monolayers (Liza-Gr3(Liza-BN3)). We observed that reinforcement by Gr or h-BN significantly increased the bulk, Young’s and shear moduli of the composites. Taking into account that the Gr and h-BN sheets interact weakly by van der Waals interactions with the lizardite slab surface, we estimated the Young’s and shear moduli of the composites by the Rule of Mixtures and obtained a reasonable agreement with those from DFT calculations. Full article

The escalating challenge of high-salinity organic wastewater has prompted the development of persulfate-based advanced oxidation processes (AOPs) for the effective degradation of pollutants. This study presents the synthesis and application of a carbon-doped hexagonal boron nitride (C-hBN) catalyst, which is designed to activate peroxymonosulfate (PMS) efficiently under high-salinity conditions. The C-hBN catalyst is prepared through a two-step process using dopamine as the carbon source, resulting in a uniform doping of carbon and the formation of B-N-C bonds. The catalyst exhibits a significantly enhanced specific surface area and superior catalytic performance towards phenol degradation, with a rate constant of 0.74 min⁻¹. Under high-salinity conditions, the C-hBN catalyst demonstrates robust resilience against common ions, maintaining high catalytic activity. The degradation process is primarily driven by a non-radical pathway, with singlet oxygen (¹O₂) identified as the key reactive species. This work provides valuable insights into the development of metal-free catalysts for environmental remediation and offers a promising strategy for the treatment of organic pollutants in high-salinity wastewater. Full article

Composite materials based on diatomite (DT) with the addition of biochar (BC), dolomite (DL), and bentonite (BN) were developed. The effect of chemical modification on the chemical structure of the resulting composites was investigated, and their influence on heavy metal immobilization and the ecotoxicity of post-flotation sediments was evaluated. It was demonstrated that the chemical modifications resulted in notable alterations to the chemical properties of the composites compared to pure DT and mixtures of DT with BC, DL, and BN. An increase in negative charge was observed in all variants. The addition of BC introduced valuable chemically and thermally resistant organic components into the composite. Among the chemical modifications, composites with the addition of perlite exhibited the lowest values of negative surface charge, which was attributed to the dissolution and transformation of silicon compounds and traces of kaolinite during their initial etching with sodium hydroxide. The materials exhibited varying efficiencies in metal immobilization, which is determined by both the type of DT additive and the type of chemical modification applied. The greatest efficacy in reducing the mobility of heavy metals was observed in the PFS with the addition of DT and BC without modification and with the addition of DT and BC after the modification of H₂SO₄ and H₂O₂: Cd 8% and 6%; Cr 71% and 69%; Cu 12% and 14%; Ni 10% and Zn 15%; and 4% and 5%. In addition, for Zn and Pb, good efficacy in reducing the content of mobile forms of these elements was observed for DT and DL without appropriate modification: 4% and 20%. The highest reduction in ecotoxicity was observed in the PFS with the addition of DT and BC, followed by BN and DL, which demonstrated comparable efficacy to materials with DT and BN. Full article

To improve the adhesion strength of polymer functional films, corona treatment is required. Corona rollers are key components for corona treatment, which are used in high-voltage electric fields for a long time. In this work, in order to improve electrical insulation, arc resistance, wear resistance, and chemical stability, a coating is usually sprayed on the surface of the corona roller. Al₂O₃/h-BN composite coatings are prepared on the surface substrate of a corona roller (20 steel) by atmospheric plasma spraying (APS) technology. Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis showed that the Al₂O₃/h-BN composite coating had a layered structure and compactness. Two kinds of Al₂O₃/h-BN composite coatings are prepared under different APS process parameters; the porosities of A coating and B coating are 6.04% and 4.75%, the microhardnesses are 781 ± 0.5 Hv and 840.5 ± 0.5 Hv, and the adhesion strengths are 22.0 MPa and 22.3 MPa, respectively. The A and B volume resistivity of the coatings are 9.29 × 10¹⁰ Ω·cm and 3.55 × 10¹⁰ Ω·cm, respectively. The volume resistivity and porosity of the coatings are negatively correlated, and they decrease with the increase in spraying current. But for both coatings, volume resistivity is greater than 1 × 10¹⁰ Ω cm. These results indicate that the Al₂O₃/h-BN composite coatings, as a new type of electrode roller coating, satisfy the use requirement. Al₂O₃/h-BN composite coatings can become the potential for ceramic coatings that have good mechanics and insulation performance. Full article

In the present research, hexagonal boron nitride (h-BN) films were deposited by reactive high-power impulse magnetron sputtering (HiPIMS) of the pure boron target. Nitrogen was used as both a sputtering gas and a reactive gas. It was shown that, using only nitrogen gas, hexagonal-boron-phase thin films were synthesized successfully. The deposition temperature, time, and nitrogen gas flow effects were studied. It was found that an increase in deposition temperature resulted in hydrogen desorption, less intensive hydrogen-bond-related luminescence features in the Raman spectra of the films, and increased h-BN crystallite size. Increases in deposition time affect crystallites, which form larger conglomerates, with size decreases. The conglomerates’ size and surface roughness increase with increases in both time and temperature. An increase in the nitrogen flow was beneficial for a significant reduction in the carbon amount in the h-BN films and the appearance of the h-BN-related features in the lateral force microscopy images. Full article