BN Content Research Articles

Synthesis, Microstructural Investigation, and Mechanical Behavior of AA5083/Boron Nitride Nanocomposite

The as‐received aluminum alloy (AA5083) powders (44 μm) and hexagonal boron nitride (BN) nanoparticles (65–75 nm) are used to fabricate AA5083‐BN nanocomposites with varying BN content (0, 3, 6, 9, and 12 wt%). A powder metallurgy solid‐state method is employed, involving ball milling for 20 h at 100 rpm with a ball‐to‐powder mass ratio of 10:1. The processed powders are then consolidated through forging–sintering at 550 °C for 30 min, followed by hot forging at 225 MPa. The microstructure is examined using X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray, transmission electron microscopy, and electron backscatter diffraction to understand the effect of processing variables. The compaction behavior is investigated both experimentally and empirically, revealing a relative green density exceeding 88% at 500 MPa. The empirical models display coefficients of determination (R2 values) exceeding 99% for predicting the compaction behavior. Compression tests on bulk samples show that BN reinforcement significantly enhances ultimate compressive strength, with values reaching 473.256 ± 5.54, 536.374 ± 2.87, 567.694 ± 4.22, and 601.911 ± 6.54 MPa for TRB‐3, TRB‐6, TRB‐9, and TRB‐12, respectively. The developed composites achieve relative densities greater than 97%, indicating promising applications in the aerospace, automotive, and marine industries.

Investigation of the absorption properties of multilayer composites based on ABS-plastic with boron nitride

Modeling of absorption capabilities of different plastics, including those with different content of boron nitride for ABS-plastic was performed. Modeling was carried out using the PHITS software package. The paper compares the results of modeling the absorption capacity of plastic with experimental data. The case of practical application of ABS-plastic as neutron-absorbing shutters of a diaphragm is considered.

Polyvinyl alcohol/boron nitride aerogels for radiative cooling

AbstractDaytime radiative cooling material provides a low‐energy way of cooling because it can reflect sunlight and radiate heat without consuming any energy. However, there are still great difficulties in manufacturing low‐cost, high‐efficiency, sustainable, and biodegradable daytime radiative cooling materials. In this paper, poly (vinyl alcohol)/boron nitride (PVA/BN) composite aerogels were prepared by freeze‐drying technology. By adjusting the PVA concentration and BN content, the aerogel can achieve high sunlight reflectivity (96%), high mid‐infrared emissivity (96%) and good thermal insulation performance. Therefore, the temperature of the aerogel can be reduced to 12.5°C lower than the ambient temperature at night, and 5.5°C lower than the ambient temperature under the direct sunlight of 900 W/m2. This aerogel opens an environmentally sustainable pathway for radiative cooling applications.

Effect of Surface Treatment and BN Content on the Mechanical Properties of Aluminum Laminates Reinforced with Glass Fiber and Epoxy Resin

Effect of Surface Treatment and BN Content on the Mechanical Properties of Aluminum Laminates Reinforced with Glass Fiber and Epoxy Resin

Combustion synthesis of tunable‐aspect‐ratio β‐Si3N4/BN composite ceramic materials

AbstractHigh thermally conductive β‐Si3N4 is a new type of filler for thermally conductive materials. Tailoring its aspect ratio is crucial to optimize the preparation process and performance of polymer‐based thermal conductive materials. In this work, β‐Si3N4/BN thermally conductive hybrid fillers were prepared by combustion synthesis in a nitrogen atmosphere using low‐cost Si, B2O3 powders as raw materials, and the aspect ratio of β‐Si3N4 crystals were regulated according to the inhibiting growth strategy of second phase BN generated by in situ reaction. With the increase of B2O3, the content of BN increased slightly, while that of β‐Si3N4 decreased slightly. The aspect ratio of β‐Si3N4 decreased from 6.3 ± 1.9 to 1.9 ± 0.6, which might be ascribed to the inhibiting effect of BN sheets on the axial growth of rod‐like β‐Si3N4. Low‐aspect‐ratio β‐Si3N4/BN/epoxy composite exhibited high thermal conductivity of 1.04 W·m‐1·K‐1at the solid content of 50 wt%, which was 372.7% and 30.0% higher than that of neat epoxy and 40 wt% high‐aspect‐ratio β‐Si3N4/epoxy composite, respectively. In addition, β‐Si3N4/BN/epoxy composite also had good mechanical properties.

Enhanced thermal conductivity and mechanical properties of boron nitride@polymethylacrylimide/epoxy composites with self-assembled stable three-dimensional network

Constructing a three-dimensional (3D) network of fillers with high thermal conductivity is considered to be an effective strategy to obtain ideal thermal management materials (TMM). However, 3D filler network is often disrupted by the subsequent processing and forming processes , and it is difficult to incorporate high levels of fillers into lyophilized aerogels, which is a key factor limiting their widespread use. In this work, boron nitride@polymethylacrylimide/epoxy (BN@PMI/EP) composites with a stable 3D BN network were prepared by freeze-drying and hot-pressing. A water-soluble copolymer quaternary ammonium salt has been synthesized by the solution polymerization. BN@PMI aerogel was obtained by the freeze-drying of ammonium salt and BN solution, and thermal imidization. BN@PMI aerogel has a six-membered imine ring structure that can be loaded with a high content of BN, which ensures the stability of the 3D BN network structure and facilitates the subsequent impregnation of EP in vacuum, which is one of the innovations of this work.The stable and complete 3D BN network leads to the enhancement of thermal conductivity, and the out-of-plane and in-plane thermal conductivities of BN@PMI/EP reach 1.21 W·m–1·K–1 and 2.76 W·m–1·K–1 at BN loading of 40% (mass), respectively. Meanwhile, the excellent mechanical properties and results of finite element simulation and actual experiments confirm that BN@PMI/EP is a potential TMM.

Enhanced thermal energy storage of polyethylene glycol composite with high thermal conductive reaction-bonded BN aerogel

Organic solid-liquid phase change materials (PCMs) achieve thermal energy storage through solid-liquid phase change and are widely used for heat dissipation in electronic devices. However, organic solid-liquid PCMs have low thermal conductivity and leakage issues during phase transition. Therefore, BN aerogels were made through supramolecular self-assembly, freeze-drying, and heat treatment. By adjusting the proportion of raw materials and heating rate, thermal conductive BN aerogel with reaction-bonded fibers was obtained, which can stabilize the shape and enhance the thermal conductivity of polyethylene glycol (PEG) through the thermal conductive 3D framework. The BN/PEG PCMs showed excellent phase change enthalpy of 183.07 g J−1 (retained 97 % of PEG), superb shape stability, and high thermal conductivity of 0.89 W m−1 K−1 at 2.8 vol% BN content. The BN/PEG PCMs have enhanced thermal energy storage ability for heat dissipation, especially in the electronic field that requires electrical insulation.

Enhancing Thermal Conductivity in Polymer Composites through Molding-Assisted Orientation of Boron Nitride.

Incrementing thermal conductivity in polymer composites through the incorporation of inorganic thermally conductive fillers is typically constrained by the requirement of high filler content. This necessity often complicates processing and adversely affects mechanical properties. This study presents the fabrication of a polystyrene (PS)/boron nitride (BN) composite exhibiting elevated thermal conductivity with a modest 10 wt% BN content, achieved through optimized compression molding. Adjustments to molding parameters, including molding-cycle numbers, temperature, and pressure, were explored. The molding process, conducted above the glass transition temperature of PS, facilitated orientational alignment of BN within the PS matrix predominantly in the in-plane direction. This orientation, achieved at low filler loading, resulted in a threefold enhancement of thermal conductivity following a single molding time. Furthermore, the in-plane alignment of BN within the PS matrix was found to intensify with increased molding time and pressure, markedly boosting the in-plane thermal conductivity of the PS/BN molded composites. Within the range of molding parameters examined, the highest thermal conductivity (1.6 W/m·K) was observed in PS/BN composites subjected to five molding cycles at 140 °C and 10 MPa, without compromising mechanical properties. This study suggests that compression molding, which allows low filler content and straightforward operation, offers a viable approach for the mass production of polymer composites with superior thermal conductivity.

Stable self-crosslinking phase change composites with vertically aligned boron nitride for high thermal conductivity thermal interface materials

Thermal interface materials (TIMs) must have a high through-plane thermal conductivity in order to efficiently transfer the heat generated by electronic components to heat sinks. Nevertheless, the achievement of high through-plane thermal conductivity is still a great challenge due to the inadequate thermal conductivity network as well as the lack of thermal response from the polymer matrix. Herein, we have developed a solid-solid phase change polymer matrix achieved through self-crosslinking polyethylene glycol (SCPEG). Subsequently, high-performance TIMs based on the SCPEG matrix and vertically aligned boron nitride (BN) nanosheets are obtained by bidirectional freezing, hot pressing, and longitudinal slicing. The prepared BN/SCPEG composites (BN content of 80 vol%) with a vertically oriented network achieved a through-plane thermal conductivity of 23.03 W m-1 K-1. More importantly, the vertically aligned BN nanosheets improve the thermal conductivity of composites, while the SCPEG matrix can reduce the hardness of composites by absorbing the heat, thus decreasing the contact thermal resistance.

Preparation of environmental-benign castor oil-derived polyurethane thermal conductive structural adhesives with superior strength

Thermal conductive structural adhesives offer a robust solution for injection into the battery core of power battery packs in new energy vehicles, effectively providing filling, protecting, and facilitating timely heat dissipation. In this work, a series of castor oil (CO)-based polyurethane prepolymers with different isocyanate (NCO) contents were synthesized by a solvent-free method, which designated as Component B (curing agent) for the CO-based polyurethane (CIPU) adhesives. Polyaspartic acid ester (PAE) resin compounded with poly (tetramethylene ether glycol) (PTMG) of different molecular weights, constituted Component A of the CIPU adhesives. The effect of mass ratio of PAE to PTMG (M value) on mechanical performance of the CIPU adhesives under different curing agent conditions was investigated. The results indicated optimal overall performance for the CIPU adhesive with an M value of 3, exhibiting a tensile strength of 10.25 MPa, an elongation at break of 107.14%, and a steel-steel tensile shear strength of 4.7 MPa. Subsequently, a series of CIPU thermal conductive structural adhesives were prepared by introducing thermal conductive fillers into the optimized CIPU adhesive formula. The introduction of a 35% Boron nitride content yielded a CIPU thermal conductive structural adhesive with a thermal conductivity of 0.64 W/m·K, and a steel-steel tensile shear strength of 6.97 MPa. These innovative CIPU thermal conductive structural adhesives prepared herein are expected to be applied in the new energy automotive and electronics industries.

Nano boron nitride laminated poly(ethyl methacrylate)/poly(vinyl alcohol) composite films imprinted with silver nanoparticles as gas barrier and bacteria resistant packaging materials

AbstractHerein, nano boron nitride (BN) laminated poly(ethyl methacrylate) (PEMA)/poly(vinyl alcohol) (PVA) nanocomposite films are fabricated by using a simple in situ polymerization technique with incorporation of silver nanoparticles (Ag NPs). Structural investigations of PEMA/PVA/Ag@BN nanocomposite thin films are carried out by Fourier‐transform infrared spectroscopy, dynamic light scattering, X‐ray diffraction analysis, 1H nuclear magnetic resonance, 13C nuclear magnetic resonance, and mass spectrometry. The change in morphology of PEMA/PVA matrix due to the reinforcement of BN platelets are identified by electron microscopic studies. The unique tortuous paths are achieved by the dispersion of BN platelets by which gas penetration is restricted with enhancing the barrier properties of the material by 6.5 folds at 5 wt% BN content as compared with neat PEMA/PVA. Acid and alkali resistant along with biodegradability behavior of as‐synthesized nanocomposites are studied. From limiting oxygen index (LOI) results, it is found that the prepared materials are fire retardant in nature owing to effective reinforcement of BN layers. Antibacterial activities of PEMA/PVA/Ag@BN nanocomposite are studied by Xanthomonas citri or axonopodis pv. Citri, Escherichia coli, and Xanthomonas oryzae pv. Oryzae because of Ag NPs reinforcement. The substantial improvements in gas barrier, fire retardant, and antibacterial properties enable the materials for packaging application.

Fluid-assisted fused deposition modeling 3D printing of anisotropically thermally conductive polymer composites with precisely tunable heat transfer pathways

A fluid-assisted fused deposition modeling (FA-FDM) 3D printing technique was proposed and employed to create anisotropically thermally conductive polymer composites (aniso-TCPCs). These composites have precisely controllable heat conduction pathways achieved by spraying boron nitride (BN) on both sides of the FDM 3D printed POE/PP materials. At the same BN content (cBN), the thermal conductivity (λ) of the aniso-TCPCs is higher than that of the isotropic composites. When cBN = 60 wt%, the λ of the aniso-TCPCs could reach 1.43 W m−1 K−1, improved over 510 % as compared to the POE/PP matrix. Both experimental and simulation results show that the design of the anisotropically thermally conductive pathways can significantly improve the thermal conductivity of the polymer composites for efficient heat dispersion. Overall, the present study would provide a point of reference for the rational design of effective heat dissipation materials with highly and precisely tunable heat transfer pathways.

Molecular simulation study on the influence mechanism of thermal and mechanical properties of boron nitride filled epoxy resin

Epoxy resin (EP) is used in electric power equipment due to its superior mechanical and insulating qualities. However, as power equipment advances towards high voltage and high frequency, the drawbacks of epoxy resin’s poor thermal conductivity become more apparent. This study studied the thermal and mechanical properties of an EP composite when the concentration of hydroxylated boron nitride (BN) was increased. The findings demonstrate that as BN content is increased, epoxy resin’s thermal conductivity also increases. When BN concentration reaches 40%, the heat conduction network is constructed. The mechanical characteristics of epoxy resin rapidly deteriorate and BN agglomeration occurs when the concentration exceeds this threshold. Better dispersion of the hydroxylated BN is made possible by the hydrogen bond formed between BN and epoxy resin, which regulates the mechanical properties of the EP.

Effects of hexagonal boron nitride content on forming quality and performance of laser powder bed fusion manufactured nickel-based hastelloy X composites

Regulating the composition of nickel-based composites, especially those containing crack-sensitive Hastelloy X (HX) matrix, significantly influences the forming quality and performance of parts manufactured using laser powder bed fusion (LPBF). Ray tracing and temperature field simulations were conducted to analyze the non-equilibrium solidification mechanism of the laser processed hexagonal boron nitride (h-BN)-HX system, resulting in an optimized h-BN content range. The optimized composition, with 0.2 wt% h-BN in HX, showcased the best forming quality and performance. It displayed negligible cracks or unmelted particles, minimal surface roughness of 9.29 μm, and superior tensile properties with a tensile strength of 1246.49 MPa and an elongation of 18.67 %. Furthermore, the samples showcased increased hardness (371.21 HV5) and reduced friction coefficient (0.54). Interestingly, with a further increase in h-BN content, a gradual improvement in strength and hardness was observed, accompanied by a reduction in the friction coefficient. Nevertheless, the ductility of the samples noticeably decreased. The 1 wt% h-BN/HX sample exhibited a tensile strength of 1503.14 MPa, hardness of 502.13 HV5, and friction coefficient of 0.48 while displaying an elongation of only 3.76 %. These findings emphasize the significance of optimizing the composition of Ni-based composites to enhance the forming quality and performance of parts manufactured through LPBF, particularly in aerospace and engineering applications.

Highly thermally conductive and soft thermal interface materials based on vertically oriented boron nitride film

Thermal interface materials (TIMs) with high through-plane thermal conductivity (TC), softness, and electrical insulation are highly desired for modern electronics. However, it is challenging to simultaneously achieve these properties. Boron nitride (BN)-based polymer composites are promising candidates for advanced TIMs owing to the high TC and great electrical insulation of BN. However, previous works perform either low TC (< 8 W m−1 K−1) or high stiffness. The ultimate properties of BN-based TIMs remain largely unclear and unrealized. Here, we fabricate BN film-filled silicone rubber composites by a facile stacking-cutting method, which maintains the high degree of orientation the BN film, so that a record-high though-plane TC of 19.1 W m−1 K−1 and a low compressive modulus of 5.42 MPa are achieved. The low BN content (37 vol%) ensures the softness and resilience of the as-prepared TIMs. This work presents a highly efficient strategy to enhance the performance of BN based TIMs, promoting their large-scale manufacturing and practical applications.

Effect of BN or B4C content on physical and tribological properties of copper‐clad laminates reinforced with carbon fiber and epoxy resin

AbstractPlasma treatment was used to improve the surface roughness of copper foil. The copper‐clad laminates reinforced with carbon fiber, boron nitride (BN), or boron carbide (B4C), and epoxy resin were prepared by hot pressing. The effect of BN or B4C content on the physical properties and tribological properties of copper‐clad laminates reinforced with carbon fiber and epoxy resin were studied. The resulting copper‐clad laminate exhibited desirable properties, such as dielectric constant, peel strength, oxygen index, and arc resistance, which were influenced by the concentration of BN or B4C particles. Additionally, the wear and friction properties of the laminate were evaluated, revealing the effects of load, sliding speed, and particle content on weight loss, specific wear rate, and coefficient of friction. SEM analysis of worn surfaces provided insight into the stages of wear, highlighting the importance of an oxide layer in reducing wear and protecting the copper surface.

In-situ synthesized multi-component particle reinforced TiAl composite with excellent mechanical properties

In order to overcome the inherent trade-off between strength and ductility of TiAl alloys, the BN nanosheets were added in Ti-48Al-2Cr-2Nb alloy. Ti-48Al-2Cr-2Nb-xBN (x = 0, 0.1, 0.5, 1, 2 wt%) alloys were prepared by vacuum arc melting (VAR), and the microstructures displayed a fully lamellar structure accompanied by simultaneous precipitation of Ti2AlN and TiB2 phases. The reaction of BN nanosheets with the Ti and Al elements resulted in formation of Ti2AlN and TiB2 phases. The lamellar colony size of TiAl composites was refined from 276.7 to 29.4 µm with BN content increasing from 0 to 2 wt%. While the lamellar spacing displayed an initial decrease followed by an increase, which was attributed to the synergistic effect of Ti2AlN and TiB2. Room temperature compression results showed that the compressive strength surged from 1653 to 2272 MPa as BN content rose from 0 to 0.5 wt%, with the highest compression strain of 34.7 % at 0.5 wt% BN. The high temperature compression results showed that the compressive strength increased from 887 to 1399 MPa as the BN content increasing from 0 to 1 wt%. Crack extension took the form of both trans-granular and inter-granular modes. The strengthening effect of TiAl composites was attributed to grain refinement strengthening and secondary phase strengthening via Ti2AlN and TiB2.

Upconversion nanoparticles incorporated with three-dimensional graphene composites for electrochemical sensing of baicalin from natural plants.

Chinese medicine has been widely studied owing to its many advantages. Baicalin (Bn), extracted from natural plants, has been shown to have significant anti-inflammatory and anticancer activity. Therefore, it is of great significance to develop a suitable method to detect the content of Bn in traditional Chinese medicine. Herein, we report an electrochemical sensor for the sensitive detection of Bn in Scutellaria root samples through a synergistic effect between upconversion nanoparticles (UCNPs) and three-dimensional macroporous graphene (3DG). The prepared UCNP-3DG composite was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectroscopy (XRD). This proposed sensor exhibited a low detection limit of 3.8 × 10-8 M (S/N = 3). Importantly, the established method possesses good stability and selectivity and can successfully detect Bn in Scutellaria root samples. It provides a suitable strategy for the determination of Bn and has potential application prospects in the assay of traditional Chinese medicine.

Study on the effects of incremental curing on the thermal conductivity, insulation, and mechanical properties of thermal conductive silicone rubber

With the development of fields such as electronics and telecommunications, electronic devices are becoming more integrated and powerful. Therefore, there is an increasing demand for high thermal conductive and insulating flexible materials. Silicone rubber (SR), as an excellent flexible substrate, is often combined with various thermal conductive fillers to enhance its thermal conductivity (TC). Carbon materials are commonly used as thermally conductive fillers. To improve the insulation performance while maintaining the TC of the material, uncured SR filled with boron nitride (BN) is used as an insulating layer on the same substrate. The TC of the once-cured BN/SR composite and the incremental cured BN/SR composite as a coating are 0.492 W/(mK) and 0.484 W/(mK), respectively, with a BN content of 10 vol%. The TC of carbon fiber (CF)/SR composites before and after surface treatment with BN/SR are 1.760 W/(mK) and 1.682 W/(mK), respectively, with a CF content of 20 vol%. The volume resistivity of the former is less than 104 Ω cm, while the latter is greater than 1014 Ω cm.

Preparation of continuous PBO fiber-filled silicone rubber with high thermal conductivity through simple Wrapping

With the development of the electronics, the demand for flexible thermal materials with high thermal conductivity continues to rise. Here, we report a type of thermally conductive silicone rubber (SR) prepared using continuous poly (p-phenylene benzobisoxazole) fiber (PBO). Through a process consistent with the layer stacking principle, continuous fibers are first immersed with SR or boron nitride (BN)/SR and then wound layer by layer onto a mold. Then, PBO/SR and PBO/BN/SR composites were prepared in the laboratory. In these composites, PBO fibers can directly form numerous thermal paths. Additionally, due to the traction and compression between fibers during the winding process, BN is distributed along the fibers. It allows BN to better form independent thermal paths and, together with PBO fibers, create a thermal network in SR. The thermal conductivity of PBO/SR and PBO/BN/SR composites can reach 5.656 W m−1 K−1 and 7.853 W m−1 K−1, respectively, with PBO and BN contents of 20 vol% and 10 vol%, respectively.