Boron Nitride Particles Research Articles

Electrophoretic Deposition of Hexagonal Boron Nitride Particles from Low Conductivity Suspension

Given that hexagonal boron nitride (hBN) particles are extremely stable in colloidal suspensions due to their low density, they are difficult to deposit via electrophoretic deposition (EPD). Poly (diallyldimethylammonium chloride) (PDDA) is widely used as a polyelectrolyte for ceramic particles because of its strong electrophoretic response. Nevertheless, studies on PDDA as a functionalising agent of hBN particles for EPD remain elusive. Here, hBN particles were functionalised with different amounts of PDDA to investigate effects on suspension stability and EPD yield. Deionised (DI)-water-based hBN particle suspensions with PDDA contents that varied from 0.3 wt% and 0.6 wt% (of hBN basis) were prepared using washed as-received hBN particles. Then, washed and nonwashed PDDA-functionalised hBN particle groups were prepared by subjecting only the former to water washing. Washing, which involved the repeated particle dispersion in DI water and vacuum filtration, successfully reduced the conductivity of the aqueous hBN suspension to 2 µS/cm, which was significantly lower than the conductivities of 180 and 25 µS/cm shown by the as-received particle suspension and PDDA-functionalised particles before washing. This result indicated that washing eliminated the interference of free ions on the suspension stability of hBN particles and EPD yield. In contrast to that of the nonwashed group, the suspension stability of the washed group decreased as the PDDA content was increased. Nevertheless, at 0.3 wt% and 0.6 wt% PDDA, the EPD yields of the washed group were 183% to 31% higher than those of the nonwashed group. This study provided new insight into the EPD of hBN particles using low-cost aqueous suspensions with sustainable ultralow ion conductivity.

Uniform Lithium Deposition Induced by Double Lithiophobic Sandwich Structure for Stable Lithium Metal Anode

AbstractThe uncontrollable dendrite growth and complex interfacial reactions are still challenging issues hindering the practical applications of lithium (Li) metal anode. A variety of materials are widely studied to regulate the surface properties of Li metal anode except for the lithiophobic materials. This study shows that a double lithiophobic sandwich structure can induce uniform Li deposition to suppress Li dendrite growth at the nucleating stage. A hexagonal boron nitride (h‐BN) particle layer on Cu foil (h‐BN@Cu) is prepared as the research target to intensely explore the fundamental role of the lithiophobic h‐BN layer on the diffusion and nucleation behavior of Li on the Cu surface. The h‐BN layer makes the h‐BN@Cu interface possess lower adsorption energy and more substantial charge transfer, leading to the “h‐BN‐Li‐Cu” sandwich deposition mode. Theoretical calculations, in situ monitoring, and experimental tests confirm the relevance between uniform Li deposition and the h‐BN@Cu interface structure. The h‐BN@Cu anode enables a significantly improved lifespan (over 550 h) compared to the Cu anode and enhanced cycling stability when assembled in whole cells with LiFePO4 (LFP) cathode. This discovery provides a new insight into h‐BN and other lithiophobic materials as a protective layer to improve the Li deposition behavior.

Moringa oil with graphite and hexagonal boron nitride particles as additives for lubrication

Tribological behaviour of bio-lubricants is constantly evolving to be improved. Vegetable and synthetic oils owing the increasing interest of the environmental impact constitute a suitable alternative for lubrication. The addition of particles as additive show a great potential to improve the tribological properties of bio-lubricants. This paper overviewed the effect of graphite and hexagonal boron nitride (hBN) particles as additives on the tribological properties of different lubricating base oils such as mineral oil (dodecane), vegetable oil (moringa oil) and vegetable/dodecane blends. The addition of particles (0.5 and 1 w%) has indicated an improvement of the mineral base oil. At the addition of small amounts of moringa oil (MO), a reduction of about 55% of friction and wear performances of dodecane. We showed that the more promising results were obtained for the blend containing 3 w% of MO with hBN particles. These new formulations lubricant represent an excellent alternation for lubrication environmentally friendly.

Numerical Analysis of Multi-Angle Precision Microcutting of a Single-Crystal Copper Surface Based on Molecular Dynamics.

The molecular dynamics method was used to study the removal mechanism of boron nitride particles by multi-angle microcutting of single-crystal copper from the microscopic point of view. The mechanical properties and energy conversion characteristics of single-crystal copper during microcutting were analyzed and the atomic displacement and dislocation formation in the microcutting process are discussed. The research results showed that during the energy transfer between atoms during the microcutting process of boron nitride particles, the crystal lattice of the single-crystal copper atom in the cutting extrusion region was deformed and displaced, the atomic temperature and thermal motion in the contact area between boron nitride particles and Newtonian layer of workpiece increased, the single-crystal copper atom lattice was defective, and the atomic arrangement structure was destroyed and recombined. The interface of different crystal structures formed a dislocation structure and produced plastic deformation. With the increase of the impact cutting angle, the dislocation density inside the crystal increased, the defect structure increased and the surface quality of the workpiece decreased. To protect the internal structure of the workpiece and improve the material removal rate, a smaller cutting angle should be selected for the abrasive flow microcutting function, which can reduce the formation of an internal defect structure and effectively improve the quality of abrasive flow precision machining. The research conclusions can provide a theoretical basis and technical support for the development of precision abrasive flow processing technology.

Radiation Shielding Tests of Crosslinked Polystyrene-b-Polyethyleneglycol Block Copolymers Blended with Nanostructured Selenium Dioxide and Boron Nitride Particles.

In this work, gamma-ray shielding features of crosslinked polystyrene-b-polyethyleneglycol block copolymers (PS-b-PEG) blended with nanostructured selenium dioxide (SeO2) and boron nitride (BN) particles were studied. This research details several radiation shielding factors i.e., mass attenuation coefficient (), linear attenuation coefficient (), radiation protection efficiency (RPE), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP). The irradiation properties of our nanocomposites were investigated with rays from the 152Eu source (in the energy intervals from 121.780 keV to 1408.010 keV) in a high-purity germanium (HPGe) detector system, and analyzed with GammaVision software. Moreover, all radiation shielding factors were determined by theoretical calculus and compared with the experimental results. In addition, the morphological and thermal characterization of all nanocomposites was surveyed with various techniques i.e., nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). Acceptable compatibility was revealed and observed in all nanocomposites between the experimental and theoretical results. The PS-b-PEG copolymer and nanostructured SeO2 and BN particles exerted a significant effect in enhancing the resistance of the nanocomposites, and the samples with high additive rates exhibited better resistance than the other nanocomposites. From the achieved outcomes, it can be deduced that our polymer-based nanocomposites can be utilized as a good choice in the gamma-irradiation-shielding discipline.

Сравнительный анализ горения частиц бора, карбида бора, нитрида бора и углерода в воздухе

Combustion models of main components of condensed combustion products (CCP) of boron-containing solid propellants: boron, boron carbide, boron nitride, and carbon are analyzed. Using the known experimental data, the parameters of the combustion model of boron carbide and boron nitride particles are determined. Using the models of combustion of boron, B4C, BN and carbon particles, parametric calculations of the combustion of both individual abovementioned particles and their mixture, which simulates the composition of the CCP of boron-containing solid propellant, have been carried out. Calculations have shown that combustion of BN has the least effect on the completeness of CCP combustion. This is due to its low calorific value and low content in CCP. Ceteris paribus, carbon particles burn the fastest; however, their contribution to the completeness of CCP combustion is less than that of boron and boron carbide due to their lower calorific value.

Optimization and Wear Properties for the Composites of Metal Matrix AA8011/Boron Nitride Using Taguchi Method

In automotive and aircraft design, a new emerging material known as AA8011 metal matrix composite has earned a place for the reason that it is extremely durable and extremely hard. Newer composite variants were created and selected because of the demand for improved tribological performance. This study’s objective is to find out how an AA8011‐Boron Nitride metal matrix composite (MMC) wears out under different loads and sliding speeds. AMMC fortified with Boron Nitride particles are created using the powder metallurgy route and contain weight fractions ranging from 10% to 15% of the AA8011 and 37 μm Boron Nitride particles. The material is made in an electric melting furnace through a stir casting procedure. Next, the materials are tested to see how long they will last in a tribotester set up like this: a block on a roller. With a controlled experimentation strategy, wear data can be collected using the L27 Taguchi method. Dry sliding wear of composites is controlled by four parameters: Boron Nitride substance, load‐bearing capacity, slid speed, and sliding time. An analysis of variance is used to determine their effects. Sliding speed, friction, and normal load all have an effect on how much dry sliding wear occurs. In addition, the least amount of wear is obtained by combining the four controlling parameters optimally.

Investigation of electrical resistance and dielectric constant of Boron Nitride and Banana fiber reinforced epoxy polymer matrix composite

Nowadays, high thermal conductive and good electrical insulating materials gain attention for compact and sustainable design in power electronics instruments like transformers, switches, cables. To cater for these needs, Boron Nitride (BN)/Banana Fiber (BF)/Epoxy based polymer composite is proposed which exhibits good electrical resistance and low dielectric constant. Banana fiber is chosen as it contains few lumens among the fillers and offers good mechanical strength. Boron Nitride and Banana fiber are reinforced with epoxy resin to form highly insulating polymer matrix composite material. Various samples are fabricated, containing 1/3/5 μm BN particle size, 1/3/5 wt % of BN and 0/2/4 wt % of BF derived from Response surface methodology based Box Behnken Design model using design of experiments approach. Further, Analysis of Variance is performed to obtain optimized levels of parameters using regression equation in MINITAB software. Also, experimental results and optimized results are compared leading to error analysis. High resistance of 346.68 Giga-ohms (86.67 ×109 Ω-m resistivity) and minimum dielectric constant of 1.143 are obtained for combination of 3 wt % of BN, 2 wt % of BF and particle size of 3 μm which is considerable for good insulation purpose.

Physical and mechanical properties of AA2219/BN composites

The main purpose of this paper is to compare the impacts of multiple Boron Nitride particle weight percentages of micro-sized particles and nano-sized particles on the AA2219 hybrid nanocomposite produced via sintering and hot extrusion procedures. The finalized materials are structurally and metallurgically characterized. To conduct a comparative analysis, the weight percentages of Boron Nitride-reinforced particles are varied. When compared to the other samples, the yield strength (270 MPa) and ultimate tensile strength (UTS) of the AA2219 hybrid composite sample-3 (S3) are greatly enhanced.

Boron Nitride Reinforced Flexible Poly(L-lactide)-b-polyethylene glycol-b-poly(L-lactide) Bioplastic: Evaluation of Thermal, Morphological and Mechanical Properties

Poly(L-lactide)-b-polyethylene glycol-b-poly(L-lactide) triblock copolymer (PLLA-PEG-PLLA)/exfoliated boron nitride (BN) composite films with different boron nitride contents (1, 2, 4 and 6 wt.%) were prepared by a solution-suspension casting method. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffractrometry (XRD) and tensile testing were carried out to characterize the thermal, morphological and mechanical properties of composite films. The DSC and XRD analyses showed the increasing crystallinity-content of composite films was obtained and their thermal stability as assessed by thermogravimetric analysis was improved when the boron nitride content was increased until 2 wt.%. Aggregation of boron nitride particles in composite films occurred when the boron nitride contents were higher than 2 wt.% as observed from SEM. The tensile stress of PLLA-PEG-PLLA film (25.0 MPa) increased up to 31.6 MPa while strain at break decreased from 76% to 64% when the 2 wt.% boron nitride was blended. Thus, PLLA-PEG-PLLA/BN composite films have potential to be used as flexible bioplastics.

Comparison of Boron Nitride (BN) reinforced sintered and extruded AA2219 nano-hybrid composite particle size effects on mechanical and metallurgical characteristics

Aluminum metal matrix composites (AMMCs) exhibit extravagant characteristics that have sparked interest in developing new nanocomposite materials among the scientific world. In this paper analysis the effects of BN particle wt% micro and nano sized particles on the properties of the AA2219 hybrid nanocomposite produced via sintering and hot extrusion procedures. In comparison to sintered composite S3, the extruded composite S3 (340 MPa) has 1.234 times the compressive strength.

A Novel Method to Prepare Transparent, Flexible and Thermally Conductive Polyethylene/Boron Nitride Films.

The high thermal conductivity and good insulating properties of boron nitride (BN) make it a promising filler for high-performance polymer-based thermal management materials. An easy way to prepare BN-polymer composites is to directly mix BN particles with polymer matrix. However, a high concentration of fillers usually leads to a huge reduction of mechanical strength and optical transmission. Here, we propose a novel method to prepare polyethylene/boron nitride nanoplates (PE/BNNPs) composites through the combination of electrostatic self-assembly and hot pressing. Through this method, the thermal conductivity of the PE/BNNPs composites reach 0.47 W/mK, which gets a 14.6% improvement compared to pure polyethylene film. Thanks to the tight bonding of polyethylene with BNNPs, the tensile strength of the composite film reaches 1.82 MPa, an increase of 173.58% compared to that of pure polyethylene film (0.66 MPa). The fracture stress was also highly enhanced, with an increase of 148.44% compared to pure polyethylene film. Moreover, the addition of BNNPs in PE does not highly reduce its good transmittance, which is preferred for thermal management in devices like light-emitting diodes. This work gives an insight into the preparation strategy of transparent and flexible thermal management materials with high thermal conductivity.

The impact of boron nitride (BN) on tribological behaviour of AZ84 magnesium matrix composites

In this experimental work, evaluate the effect of BN on AZ84 Magnesium alloy composite. The results of testing exposed the higher tribological properties of the composites compared to the unreinforced alloy due to the enhanced BN particle. The BN particulate concentration increased, the wear resistance of composites increased, and wear rate decreased significantly compared to material matrix alloys. On a mechanical insulation layer which prevents metal contact the surface has a mechanically mixed oxygen and iron layer. With an increased BN content the coefficient of friction is decreased and reached minimum at its 9 vol% BN.

Aging Assessment of Corona-Exposed HTV-SiR/EPDM Blends Loaded With Nanofillers

Exposure of insulating systems to strong electric field and other environmental stresses may cause loss of their desired properties. In high-voltage applications, phenomena, such as corona discharges and unexpected flashovers, may deteriorate the surface as well as bulk conditions of an insulating material and thereby affect its lifetime. In this article, several types of corona-exposed HTV-SiR/ethylene propylene diene monomer (EPDM) blends filled with different concentrations of nano-sized boron nitride and silicon carbide particles are evaluated and the induced modifications of their properties are presented and discussed. The diagnosis is based on measured data of surface partial discharge (PD) and volume current. For the latter, experiments were performed at different levels of electric field between 0.5 and 4 kV/mm and ambient temperature ranging from 22 °C to 70 °C. Results of the conducted experiments revealed the degradation of surface properties through an increase in the PD magnitude. It was also observed that corona aging of the samples decreases the threshold electric field particularly at elevated temperatures, above which space charge effect in the materials may become significant. Moreover, it was observed that the blend compositions loaded with nanofillers retard surface PD and bulk deterioration.

Effects of TiAl Alloy as a Binder on Cubic Boron Nitride Composites.

Owing to their extreme hardness, cubic boron nitride (cBN) composites are widely used in cutting applications. The performance of cBN composites is closely related to the characteristics of the binder. Therefore, novel binders must be developed to improve the performance of cBN composites. In the present work, TiAl intermetallics were used as binders to fabricate cBN composites by employing a high-temperature and high-pressure sintering method. The phase transformation, sintering reaction mechanism, thermal stability, and mechanical properties of the resultant cBN composites were investigated. It was found that during the sintering process, Ti atoms preferentially reacted with boron nitride particles, whereas Al atoms enriched and transformed into TiAl3 phases and formed cBN/AlN, AlB2/TiN, and TiB2/TiAl3-layered structures eventually. The composites maintained good oxidation resistance at 1200 °C. A decrease in the particle size of the TiAl binder improved the uniformity of particle size distribution and increased the flexural strength of the composites.

Boron nitride with high zeta potential via plasma processing in solution for preparation of polyrotaxane composite

Plasma processing in solution is effective for the preparation of composites. To optimize the plasma processing in solution, a method that can be used to sufficiently evaluate the surface modifications is necessary. In this study, to identify such a method, hexagonal boron nitride (hBN) particles modified by plasma processing in solution and exhibiting different zeta potentials were used to prepare a polyrotaxane composite. Plasma processing in a hydroquinone solution yielded hBN particles with a high zeta potential, named HQpBN, and x-ray computed tomography showed a uniform dispersion of the HQpBN/polyrotaxane composite. The tensile strength and elongation of the HQpBN/polyrotaxane composite were twice as high as those of an unmodified hBN/polyrotaxane composite, in which hBN particles aggregated. These results demonstrate that the zeta potential of the modified particles can be used as an indicator to guide optimal surface modification during plasma processing in solution for the preparation of homogeneous composites.

Enhanced thermal conductivity and wear resistance of polytetrafluoroethylene via incorporating hexagonal boron nitride and alumina particles

AbstractPolytetrafluoroethylene (PTFE) receives wide attention in electronic packaging materials due to its excellent dielectric properties, friction properties and thermal stability. However, its extremely low thermal conductivity limits its further application. In this work, hexagonal boron nitride (h‐BN) platelets are added into PTFE matrix to improve the thermal conductivity as the expense of largely deteriorated friction property. To make up the loss of friction property, alumina particles (AO) are also added and the effects of filler ratio between h‐BN and alumina on the thermal conductivity and tribological performance of PTFE composites are investigated. It is interesting to find that when the filler ratio of h‐BN and alumina is fixed at 2:1, the through‐plane and in‐plane thermal conductivity of PTFE composite filled with 30 vol% hybrid filler can be increased to 1.544 Wm−1 K−1 and 2.029 Wm−1 K−1 (5.5 and 5.7 times that of PTFE), respectively. Furthermore, the coefficient of friction of PTFE composites only increases by 21.32% and the wear rate decreased by 48.09%, compared with that of PTFE. Our work demonstrates a facile method to achieve much improved thermal conductivity of PTFE while maintaining its excellent dielectric properties and friction properties by using hybrid filler of h‐BN and AO.

Numerical Simulation on Charge Transport and DC Breakdown in Polyethylene-Based Micro-h-BN/Nano-SiO2 with Filler Orientation Dependent Trap Energy

In order to improve the thermal conductivity and the insulation properties of polyethylene (PE) used as cable insulation under DC stress, hexagonal boron nitride (h-BN) and inorganic particles have been considered as micro-filler and nano-filler, respectively. As a 2D material, the orientation of h-BN possibly affects the insulation properties of the polymer. It is important to understand the influence of the filler orientation on the insulation performance of the polymer. In this work, a numerical simulation has been performed to investigate the effect of orientation of micro-h-BN on charge transport and DC breakdown of PE-based micro/nano-composites and a comparison between the simulation result and previous literature data has been conducted. The h-BN was designated to be parallel, perpendicular to the normal sample surface vector (the direction of electric field in this work) or randomly distributed in the matrix, and the charge transport behavior and DC breakdown strength in the samples were discussed by using the bipolar charge transport (BCT) model. The results indicated that when the h-BN was perpendicular to the normal vector, the density of trapped charge was the largest and the DC breakdown strength was the highest among the three cases studied. It is suggested that the charge trapping/de-trapping processes and the electric field in the sample vary with the orientation of h-BN through tailoring the trap characteristics of the material.

A Concurrent Enhancement of Both In‐Plane and Through‐Plane Thermal Conductivity of Injection Molded Polycarbonate/Boron Nitride/Alumina Composites by Constructing a Dense Filler Packing Structure

AbstractIn this work, a facile strategy is proposed to concurrently enhance both in‐plane and through‐plane thermal conductivity of injection molded polycarbonate (PC)‐based composites by constructing a dense filler packing structure with planar boron nitride (BN) and spherical alumina (Al2O3) particles. The state of orientation of BN platelets is altered with the presence of Al2O3, which is favorable for improving both in‐plane and through‐plane thermal conductivity of subsequent moldings. Rheological analysis showed that the formation of intact thermal conductive pathways is crucial to the overall enhancement of thermal conductivity. Both in‐plane and through‐plane thermal conductivity of PC/BN(20 wt%)/Al2O3(40 wt%) composites reached as high as 1.52 and 1.09 W mK−1, which are 485% and 474% higher than that of pure PC counterparts, respectively. Furthermore, the prepared samples demonstrated excellent electrical insulation and dielectric properties which show potential application in electronic and automotive industries.

Smoothed Particle Hydrodynamics and Discrete Element Method Coupling for Influence of Hexagonal Boron Nitride Lubricant Particle on Friction of Elastic Coarse-Grained Micronscale Iron

Abstract The present study uses the smoothed particle hydrodynamics (SPH) and discrete element method (DEM) coupling to investigate influence of the hexagonal boron nitride (hBN) particles on friction of the elastic coarse-grained micronscale iron. The hBN lubricant particles significantly improve the friction performance of iron in various simulation behaviors. The particle size, the air/water background containing the particles, and its temperature result in reduction of the friction coefficient. The surface mending, the protective film, and the energy dissipation are the main mechanisms related to the friction reduction. Additionally, it is worthy to note that the static friction and the kinetic friction can be clearly observed by this elastic coarse-graining.