Aluminum Nitride Particles Research Articles

Enhanced Electrocaloric Effect of PVDF-based Polymer Composite with Surface Modified AlN.

Poly(vinylidenefluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) relaxor ferroelectric polymer exhibits a modest electrocaloric effect (ECE) at a low electric field near room temperature and a low thermal conductivity. The low thermal conductivity causes poor heat transfer when the terpolymer is used as a cooling device, even when the ECE of the polymer is substantial. By incorporating aluminum nitride (AlN) nanoparticles, which possess high thermal conductivity and good electrical insulation properties, into polymer matrices, we can enhance both the thermal conductivity and the ECE. However, weak bonding at the AlN-polymer interface can lead to a reduced breakdown electric field. Therefore, surface modification of AlN nanoparticles is performed to strengthen the chemical bonding between AlN and the terpolymer, thereby increasing the breakdown electric field. Following the addition of surface-modified nanoparticles, the breakdown electric field of the composite films remained around 240 MV/m, which is comparable to that of the pristine polymer film. Furthermore, the ECE and thermal conductivity were improved by 44% and 55%, respectively. We found three factors influencing the ECE, including the interface effect, the change in ferroelectric-paraelectric phase transition behavior, and the Joule heating effect. To assess the interfacial effect on the ECE, composite films with AlN particles of four different sizes were prepared. It was found that as the size of the nanoparticles increased, which resulted in a decreased interface area, the ECE decreased correspondingly. This finding further confirms the significant impact of the interface area in the composites on the ECE.

Cu/AlN composite and functionally graded materials with high strength and high electrical- and thermal-conductivity fabricated by spark plasma sintering

In this study, Cu/AlN composites and functionally graded materials (FGMs) were fabricated with the spark plasma sintering method. It was observed that a two-step sintering process, involving sintering under low pressure as the initial stage to remove adsorbed chemicals on the powder, was an effective method for producing sintering objects with high relative density. The hardness of the composites significantly increased with higher volume fraction of aluminum nitride (AlN) particles, while electrical- and thermal-conductivity decreased. Nevertheless, the advanse impact of AlN on thermal-conductivity was found to be minimal. Additionally during compression test, a crack was noted at the interface between Cu and Cu-5 vol%AlN region in two-layered FGMs after, whereas no such crack was observed in the three-layered FGMs. Therefore, it is confirmed that the concept of FGMs is useful in overcoming the shortcomings of mutually exclusiveness among high strength, high electrical- and high thermal-conductively.

Morphology engineering of low-temperature-synthesized aluminum nitride

We have developed an aluminum nitride (AlN) manufacturing method that operates below the melting point of aluminum. To examine the nucleation and growth mechanisms of AlN during the synthesis process, we used a variety of characterization techniques, including high-resolution transmission electron microscopy and rapid Fourier transform, which highlighted the development of its single-crystal and polycrystalline forms. The microstructural investigation showed that nitridation began with forming AlN shells on the surface of aluminum particles. Subsequently, volume nitridation occurred by transforming a single aluminum particle into either polycrystalline AlN with a columnar structure or single-crystal AlN. In addition, various interesting morphologies were observed during the microstructural investigation of low-temperature synthesized AlN, including truncated dodecahedrons, nanowires, particles, pillars, plates, and other polyhedral shapes. The study's microstructural findings provide crucial data on the AlN particle formation process, offering valuable insights expected to deepen understanding and expand the applications of AlN. Therefore, the consequence of this study is expected to make a meaningful contribution to understanding the formation mechanism of the particle type of AlN.

Effect of aluminium nitride (AlN) particles addition on mechanical and tribological properties of aluminium matrix composites

Aluminum matrix composites (AMCs) are the most popular materials for use in a variety of industries, including the aerospace, automotive, and military sectors due to its advantageous features. In this study, the influence of AlN particles insertion on the morphology and mechanical properties were reported.Stir casting method was engaged to manufacture the AA2017 based composites reinforced with x wt.% of AlN particles (x = 0, 5, 10 and 15 wt%).The developed composites were undergone to conduct the tensile test, compression test, and hardness test as per ASTM standard. Microstructure of the proposed composites clearlyexposedthe homogeneous circulation of AlN particles and also no agglomeration formed within the matrix. The results showed the tensile strength (TS) compressive strength (CS)and hardness have drastically improved with insertion of AlN content in the base matrix. As a result, the better properties can be achieved in 15 wt% of AlN particles reinforced AA2017 matrix composite.

Effect of AlN on the Mechanical and Electrochemical Properties of Aluminum Metal Matrix Composites.

In the present investigation, aluminum metal matrix composites (AMMs) reinforced with aluminum nitride (AlN) nanoparticulates at different volumetric ratios of (0, 0.5, 1, 1.5, and 2 vol.%) were manufactured via a microwave-assisted powder metallurgy technique. The morphological, physical, mechanical, and electrochemical properties of the produced billets were examined to reflect the impact of the successive addition of AlN into the aluminum (Al) matrix. The morphological analysis revealed the high crystalline patterns of the formation of the Al-AlN composites. The microstructural analysis confirmed the presence of the elemental constituents of Al and AlN particles in the fabricated composites, showing an enhanced degree of agglomeration in conjunction with the additional amount of AlN. Positive behavior exhibited by the micro- and nanohardness was noticeable in the Al-AlN composites, especially at the ultimate concentration of AlN in the Al matrix of a 2 vol.%, where it reached 669.4 ± 28.1 MPa and 659.1 ± 11 MPa compared to the pure Al metal at 441.2 ± 20 MPa and 437.5 ± 11 MPa, respectively. A declining trend in the compressive strength was recorded in the reinforced Al samples. The corrosion resistance of the AlN-reinforced Al metal matrix was estimated at 3.5 wt.% NaCl using electrochemical impedance spectroscopy and potentiodynamic polarization. The results reveal that the inclusion of 2.0 vol.%AlN led to the lowest corrosion rate.

Production of AlN/CNT reinforced PVA nanofibers as a thermal conductive net for thermal interface applications

The amount of heat generated by electronic components is increasing daily, in line with their growing power and performance. Consequently, there is a heightened demand for thermal interface materials for enhanced cooling of electronics. This study employs a novel approach to fabricate a nano composite thermal interface material on copper substrates to address this challenge. The thermal interface coatings, consisting of carbon nanotubes (CNT) and aluminum nitride (AlN)-reinforced polyvinyl alcohol (PVA) nanofibers with and without an epoxy resin matrix, are fabricated using the electrospinning technique. The findings demonstrate the successful fabrication of a 2.5 µm-thick CNT/AlN-PVA nanocomposite fiber mat coating with an average fiber diameter of 318 nm onto copper substrates. Scanning electron microscope (SEM) images revealed that the AlN particles and CNTs penetrated the fibers. The successful incorporation of AlN particles into PVA fibers was also verified by the Fourier-transform infrared spectroscopy (FT-IR) spectrum of CNT/AlN-PVA nanofibers. No major weight loss was observed in the thermogravimetric (TG) analysis curves up to 200 °C, indicating the thermal stability of coatings. The thermal diffusivity of the copper substrate coated with the CNT/AlN-PVA nanocomposite fiber mat was measured at 36.6 mm2/s. Moreover, the developed CNT/AlN-PVA nanocomposite fiber mat was also applied on top of the fire-retardant epoxy resin-coated copper substrate, which is conventionally used in electronic devices to provide electrical insulation. SEM images revealed that the existence of an epoxy layer on top of copper substrates did not alter the fiber formation during the electrospinning process, and an approximately 2.5 µm-thick CNT/AlN-PVA nanofiber mat was effectively embedded in the epoxy layer after a 1-hour electrospinning process. The thermal diffusivity of the resulting epoxy matrix CNT/AlN-PVA nanofiber reinforced nanocomposite coating is determined to be 7.792 mm2/s, which is 30-fold higher compared to the thermal diffusivity of neat epoxy resin coatings (0.254 mm2/s).

Construction of AlN oriented skeletons using in-situ reaction strategy and their enhancement effect on the thermal conductivity of epoxy composites

The development of electronic devices towards miniaturization and integration has put forward higher requirements for polymer-based composites with high thermal conductivity (TC). Aluminum nitride (AlN) is one of the most promising fillers thanks to its high TC (∼320 W m−1 K−1) and outstanding physicochemical properties. However, the traditional composites filled with randomly dispersed AlN particles generally require extremely high filling fraction to enhance the TC, leading to increased production cost and degraded mechanical performance. To address this issue, an innovative strategy combining freezing casting and in-situ reaction process was proposed to directly construct vertically aligned AlN skeletons, which was further used as reinforcements to enhance the TC of epoxy (EP) composites. The close arrangement of AlN particles along the vertical direction was not only beneficial for enhancing the TC, but also improving the mechanical strength. The AlN/EP composites achieved an extremely high TC of ∼8.25 W m−1 K−1 at the AlN filling fraction of 56.2 vol%, which was 45.83 times higher than that of pure EP. The actual thermal management applications and finite element simulations also demonstrated the oriented AlN skeletons exhibited a more significant TC enhancement than that of randomly arranged AlN. Furthermore, the as-prepared AlN/EP composites also exhibited superior thermal stability and dielectric properties, presenting a broad application prospect as thermal management materials for the next-generation electronic devices.

Enhancing the Thermal Conductivity of CNT/AlN/Silicone Rubber Composites by Using CNTs Directly Grown on AlN to Achieve a Reduced Filler Filling Ratio.

Achieving the thermal conductivity required for efficient heat management in semiconductors and other devices requires the integration of thermally conductive ceramic fillers at concentrations of 60 vol% or higher. However, an increased filler content often negatively affects the mechanical properties of the composite matrix, limiting its practical applicability. To address this issue, in this paper, we present a new strategy to reduce the required ceramic filler content: the use of a thermally conductive ceramic composite filler with carbon nanotubes (CNTs) grown on aluminum nitride (AlN). We combined catalyst coating technology with vacuum filtration to ensure that the catalyst was uniformly applied to micrometer-sized AlN particles, followed by the efficient and uniform synthesis of CNTs using a water-assisted process in a vertical furnace. By carefully controlling the number of vacuum filtration cycles and the growth time of the CNTs, we achieved precise control over the number and length of the CNT layers, thereby adjusting the properties of the composite to the intended specifications. When AlN/CNT hybrid fillers are incorporated into silicone rubber, while maintaining the mechanical properties of rubber, the thermal diffusivity achieved at reduced filler levels exceeds that of composites using AlN-only or simultaneous AlN and CNTs formulations. This demonstrates the critical influence of CNTs on AlN surfaces. Our study represents a significant advancement in the design of thermally conductive materials, with potential implications for a wide range of applications.

Effect of Graphene Coating by Mechanical Treatment on Water Resistance of Aluminum Nitride Particles

Effect of Graphene Coating by Mechanical Treatment on Water Resistance of Aluminum Nitride Particles

Dendrite‐Free Lithium Metal Batteries Enabled by Coordination Chemistry in Polymer‐Ceramic Modified Separators

AbstractIssues with lithium dendrite growth and dead lithium formation limit the practical application of lithium metal batteries, especially under high current conditions where uneven temperature distribution leads to serious safety concerns. Herein, In situ assembly of polydopamine (PDA) and aluminum nitride (AlN) coatings on polypropylene (PP) separator is introduced to address these challenges. The AlN particles are encapsulated by PDA, and the functional groups in PDA form Al‐O coordination bonds with Al3+, which promote uniform Li+ flux and reduce the migration barrier of Li+, thereby enabling dendrite‐free lithium deposition. In addition, the designed PDA@AlN@PP separator exhibits excellent electrolyte wettability, enhanced mechanical performance, and stable thermal resistance, providing a uniform thermal distribution and serving as a robust barrier against dendrite penetration. As a result, symmetric Li||Li cells (over 1800 h at 1 mA cm−2 and 1 mAh cm−2) and Li||Cu cells (over 600 cycles at 0.5 mA cm−2 and 0.5 mAh cm−2, coulombic efficiency over 98%) demonstrate outstanding long cycle performance and high coulombic efficiency. Moreover, the corresponding Li||LiFePO4 cells exhibit a high specific capacity of 91.3 mAh g−1 at 5 C. This work provides a new approach for designing functionalized separators for high‐performance lithium metal batteries.

Significantly Enhanced Conformal Contact by the Functional Layers on a Copper Film for Thermal Interface Materials

Low‐cost thermal interface materials with high thermal conductivity (κ) and low total thermal resistance (Rt) receive considerable attention for thermal management. A copper film (CuFilm) is an excellent candidate due to the high κ (364 Wm−1 K−1) it possesses. However, the practical implementation is hindered by its high elastic modulus (Es = 70.8 GPa), inducing a high contact thermal resistance (Rc = 91.6 mm2 K W−1). Herein, the selective construction of electrically conducting or insulating layers on CuFilm to dramatically decrease Es, Rc, and Rt is reported. The highly electrically and thermally conducting layer is synthesized by incorporating in situ reduced copper nanoparticles (CuNPs, 35 vol%) and multiwalled carbon nanotubes embellished with CuNPs (1.5 vol%) in polyethylene glycol. The high effective κ (92.7 Wm−1 K−1) still maintains a low specimen thermal resistance (Rs = 4.9 mm2 K W−1), while the dramatically softened surface (Es = 5.7 GPa) decreases Rc (8.3 mm2 K W−1), resulting in a very small Rt (13.2 mm2 K W−1). Alternatively, the electrically insulating but thermally conducting layer is constructed using aluminum nitride particles. The κ is still high (72.1 Wm−1 K−1) with a small Rt (47.5 mm2 K W−1). The facile fabrication based on a CuFilm enables cost‐effective thermal interface materials with tunable electrical and thermal properties.

The Influence of Pristine and Aminoacetic Acid-Treated Aluminum Nitride on the Structure, Curing Processes, and Properties of Epoxy Nanocomposites

This article describes the preparation of aluminum nitride (AlN) functionalized with amino groups by chemically modifying the surface of AlN with aminoacetic acid and their dispersion in the epoxy composition. As a result of the studies, it was found that the functionalization of AlN particles with aminoacetic acid ensured their better chemical compatibility with the epoxy composition, which facilitated the dispersibility of AlN particles; it was also found that the functionalization of the nanofiller has a significant effect on the structure, curing kinetics, physicochemical and mechanical properties of epoxy nanocomposites. The optimal concentration of the functionalizing agent (aminoacetic acid) has been determined, which is necessary for the chemical binding of the functional groups of aminoacetic acid, the epoxy oligomer and AlN, which best affects the dispersion and the size distribution of AlN particles, and also ensures maximum strength characteristics of epoxy composites containing AlN treated with aminoacetic acid: bending stress and bending modulus increase by 35% and 80%, respectively, while tensile strength and tensile elastic modulus increase by 74% and 36%, respectively. Furthermore, the impact strength shows a remarkable boost of 133% compared to plasticized epoxy composite without AlN.

AIN particles/BN whiskers co-doped epoxy composites modified with polydopamine with high thermal conductivity

In this work, aluminum nitride particles (AlN) and boron nitride whiskers (BNw) were surface-functionalized by polydopamine, and then novel composites were prepared by co-doping. By observing with transmission electron microscopy, we clearly saw that the surfaces of AlN and BNw were successfully coated with a thin polydopamine coating. This is beneficial to enhance the filler-matrix interface interaction and the filler dispersion. The co-doping of the two thermally conductive fillers increases the chance of contact between the filler and the filler, and reduces the interfacial thermal resistance, thereby forming a thermal conduction network more efficiently. The results show that at a frequency of 1 MHz at room temperature, the dielectric constant of 30 wt%AlN@PDA/6 wt%BNw@PDA/EP composites is 4.74 and the dielectric loss tangent is 0.0171. Its thermal conductivity is 0.40 W/(m·K), the glass transition temperature reaches 250.2°C, the impact strength reaches 6.89 kJ m−2, and the breakdown field is 10.93 kV/mm.

Effect of particle size on rheology, curing kinetics, and corresponding mechanical and thermal properties of aluminum nitride (AlN) ceramic by digital light processing (DLP)-based vat photopolymerization

In this work, the influence of AlN particle size (250 nm, 1.2 µm, and 5 µm) on the curing behavior, stability and viscosity of ceramic suspensions was evaluated. It was revealed that an increase in the particle size of AlN powders reduced the stability and viscosity of the suspension. For curing behavior, the ceramic suspension prepared with 250 nm AlN powder exhibited the smallest curing depth and excess width, whereas the 5-μm ceramic suspension had the largest curing depth. The analysis of the scattering length revealed that a decrease in AlN powder particle size reduced the scattering length. After sintering, both the 250-nm and 1.2-μm samples could be sintered densely at temperatures more than 1800 °C with the relative density greater than 99%. Finally, following a 5 h sintering at 1850 °C, the 250-nm and 1.2-μm samples obtained thermal conductivities of 171 and 174 W/mK, respectively.

Balancing thermal conductivity and strength of hot-pressed AlN ceramics via pre-sintering and annealing process

The heat dissipation requirements of the new generation of semiconductors are placing higher demands on the overall performance of aluminum nitride (AlN) ceramics. This has led to an increasing emphasis on AlN ceramics that combine thermal conductivity and strength. AlN ceramics are often strengthened by hot-press sintering, but their thermal conductivity is typically modest. In this study, pre-sintering and annealing processes are introduced to optimize the thermal conductivity of hot-pressed AlN ceramics to avoid the detrimental effects of oxygen impurities in the AlN lattice. The effect of the oxide layer on the surface of commercial AlN particles is investigated, including density, phase composition, microstructure, and fracture behavior. The effect of annealing on the improvement of thermal conductivity and flexural strength is also verified. Electron paramagnetic resonance (EPR) analysis is performed to examine the concentration of intercrystalline defects under various conditions. Finally, AlN ceramics with a thermal conductivity of 204 W m−1 K−1 and a flexural strength of 376 MPa are obtained.

AlSi10Mg/AlN Interface Grain Structure after Laser Powder Bed Fusion

Details and features of the grain structure near the interface region between the AlN ceramic phase and AlSi10Mg matrix after the laser powder bed fusion (LPBF) were investigated. Aluminum nitride particles were obtained through self-propagating high-temperature synthesis and mechanically mixed with aluminum matrix powder. Optimization of the LPBF process parameters resulted in synthesized material free of pores and other defects. Optical microscopy analysis of etched cross-section and more detailed EBSD analysis revealed regions with relatively coarse grains at melting pool boundaries and fine grains in the melt pool core and near the AlN particles. Moreover, a pronounced orientation of fine elongated matrix grains towards the center of the ceramic particle was obtained. The such formed microstructure is attributed to directional heat sink during crystallization due to the higher thermal conductivity of aluminum nitride compared to the AlSi10Mg matrix. On the contrary, poor wettability of AlN by melt partly prevented the formation of such features, thus a combination of these factors determines the final microstructure of the interface in the resulting material.

Influence of AlN reinforcement on properties of AA5083 matrix composite

The material properties of metal matrix are progressively enhancing by the accumulation of aluminium nitride (AlN). It has high temperature resistance. In current scenario, aluminium composite is playing a vital role in industrial applications. AlN reinforced AA5083 is synthesized by stir casting route. The material properties of AA5083 composite are evaluated with and without AlN. The great enhancement of substance properties such as tensile strength, hardness and impact strength are achieved by the presence of AlN. Taguchi approach is used to optimize the stir casting factors. The aim of the research work is to increase the performance of AA5083 composite. Tensile strength has been increased from 355 MPa to 400 MPa by the addition of AlN particles.

Different Types of Particle Effects in Creep Tests of CoCrFeNiMn High-Entropy Alloy.

Compressive creep tests were performed on a CoCrFeNiMn equiatomic alloy with the dispersion of (i) aluminum nitride or (ii) boron nitride at temperatures of 973 K and 1073 K. The results are compared with previously published creep rates of the unreinforced matrix alloy and the alloy when strengthened by yttrium + titanium oxides. The comparison reveals that the creep rate is essentially unchanged by the presence of aluminum nitride particles, whereas it is reduced by the presence of oxide particles. Boron nitride particles do not influence the creep rate at low stresses but reduce it substantially at high stresses.

Aluminium nitride dispersion strengthened steel

Abstract Development of nanosized nitride particles in the ferrite matrix of steels is known to drastically enhance the mechanical properties. In the present work an attempt is made to utilize an unconventional method to produce the dispersion strengthened material. The gaseous nitriding treatment of Fe-4.6 at.% Al alloy powder was carried at 580 °C to realize the dispersion of aluminium nitride particles in the ferrite matrix of powders. Such nitrided powders were consolidated using spark plasma sintering. Powders and the sintered compacts were characterized using various techniques. Nitrided powders contained iron nitrides as matrix with AlN as dispersed precipitates. Annealing treatment of nitrided powders in Ar atmosphere led to the reduction of the iron nitrides to ferrite while AlN precipitates were still retained. The sintering behavior of nitrided and Ar annealed nitrided powders was studied and discussed with thermodynamic stability of iron nitrides and aluminium nitrides in ferritic matrix.

Mechanism for the hydrolysis resistance of aluminum nitride powder modified by boric acid

Aluminum nitride (AlN) ceramics are becoming cutting-edge materials for electronic information and communication. However, raw AlN hydrolyzed rapidly, and the high storage costs of this material prevent widespread application. In this study, raw AlN was modified by boric acid (H3BO3) at 30 °C to enhance hydrolysis resistance. Transmission electron microscope (TEM), X-ray diffraction (XRD), the magic angle spinning nuclear magnetic resonance (27Al-MAS-NMR and 11B-MAS-NMR), and the fourier transform infrared spectrometer (FTIR) were used to characterize the powder before and after treatment, and the mechanism of hydrolysis resistance was determined. Modification with 0.1 M boric acid did not change the crystal phase of the AlN particles. The modified powder did not hydrolyse at 90% humidity and 70° Celsius. In the presence of boric acid, a network structure of B–O–B linkages ([BOn], n = 3 or 4) formed that was connected to the AlN core via chemical bonds of B–N–Al and B–O–Al. The protective 6 – 10 nm-thick layer that formed on the surface of the AlN crystal, prevented attack by water molecules and hindered the hydrolysis of aluminium nitride. This study provides an alternative means of preparing anti-hydrolysis AlN powders.