查找使用阿拉丁产品的科研文献

Mechanical behavior of AlN/Mo functionally graded materials with various compositional structures

Fei Chen,Mingyong Jia,Yulong She,Yueqi Wu,Qiang Shen,Lianmeng Zhang

In this paper, aluminum nitride (AlN) and molybdenum (Mo) were used for fabrication of AlN/Mo functionally graded materials by spark plasma sintering (SPS). In order to study the influence of microstructure on mechanical properties in AlN/Mo FGMs, the FGMs with different composition exponent p value were analyzed by indentation and bending test . The results showed that the specimens with p  < 1 exhibited a metal-rich graded structure comparing to specimens with p  ≥ 1. The radial bending and shear strength of AlN/Mo FGMs reached maximum when p  < 1, which are 369.78 MPa and 48.01 MPa respectively. Moreover, comparing with the porosity and the ceramic/metal interface, the distribution of the two components is the most important factor for improvement of bending and shear strength. The more the hard metal network content in the graded layer, the higher the bending and shear strength of AlN/Mo FGMs.

High sphericity AlN powder carbothermal reduced from spray granulated Al2O3/C precursor

Shengyuan Chen,Kailei Lu,Xiaolan Zhou,Zehua Zhouchen,Xu Huang,Jianqi Qi,Tiecheng Lu

In this work, a simple, safe, and low-cost two-step route for preparing spherical AlN powders was developed. Specifically, pure AlN spherical powder can be obtained by using water as the solvent, ammonium polyacrylate as the dispersant, carbon powder and alumina powder as the raw materials, spraying and granulating into a spherical precursor, and then sintering at high temperature under a nitrogen atmosphere. The results demonstrate that the average size and the associated distribution of the precursor can be adjusted by regulating the solid or dispersant content of the slurry, which is beneficial for governing the size of the AlN powder. The average particle size of the sintered spherical AlN powders is approximately 33.5 μm, presenting high sphericity (greater than 0.9) and excellent flowability. This approach developed for preparing spherical AlN powder is of great significance for promoting the widespread application of AlN powder in the field of high-performance fillers.

Transparent AlN ceramics sintered from nanopowders produced by the wet chemical method

Ming XIANG,Youfu ZHOU,Wentao XU,Xiaoqiang LI,Kun WANG,Wei PAN

Study on Preparation, Thermal Conductivity, and Electrical Insulation Properties of Epoxy/AlN

Shaotao Dai,Teng Zhang,Siming Mo,Yuan Cai,Wen Yuan,Tao Ma,Lei Hu,Bangzhu Wang

Thermal conductivity of epoxy adhesive enhanced by hybrid graphene oxide/AlN particles

Wenhui Yuan,Qiangqiang Xiao,Li Li,Tao Xu

This study aims to improve the heat dispersion of electronic equipment by utilization of thermal conductive adhesive composed of epoxy matrix and filler. AlN particles with different size, graphite, graphene oxide (GO) were used alone or in a synergistic manner to prepare thermal conductive adhesives. The structure of prepared GO was characterized by XRD, FT-IR, Raman spectra and AFM. The analysis indicates that most of prepared GO is in single layer structure. The thermal conductivity and viscosity of adhesive were measured by thermal constants analyzer and rotational viscometer respectively. The results show adhesives filled with larger AIN particles possess higher thermal conductivity than that filled with smaller particles at the given filling content. GO is better than graphite as the filler to improve the thermal conductivity of the epoxy resin. When 8   wt% GO or 70   wt% 5   μm-AlN particles was added, the thermal conductivities of adhesives were about 6.42 times and 11.8 times that of pure epoxy respectively. To further improve the thermal conductivity, 50   wt% 5   μm-AlN particles and 6   wt% GO hybrid filler were proposed, and the final thermal conductivity reached up to 2.77   W/m   k, that was 14.6 times of that of neat epoxy. In addition, Agari equation as a systematic theoretical modelling was cited to analyze the effect of each filler on improvement of thermal conductivity of adhesive.

Preparation of high performance AlN/Hydantion composite by gelcasting and infiltration processes

Chao Jiang,Dou Zhang,Xueping Gan,Rui Xie,Fuqiang Zhang,Kechao Zhou

A new processing technique was proposed for preparing aluminum nitride (AlN)/Hydantion interpenetrating network composites. The technique comprised gelcasting AlN green bodies, degreasing, and infiltrating Hydantion epoxy resin and hardener into the AlN skeleton under a vacuum condition. The effects of AlN contents on the viscosities of AlN slurries and the flexural strength , thermal conductivity , dielectric constant of the AlN/Hydantion composites were evaluated. The highest thermal conductivity and flexural strength of the AlN/Hydantion composites reached 3.56   W/mK and 101.3   MPa, respectively. The fracture surface of the composite revealed that an interpenetrating polymer network in the AlN ceramic skeleton was formed. The AlN/Hydantion composite exhibited the dielectric constant of 7.3 at 1   MHz.

Translucent red-emitting AlN: Mn phosphor ceramics with high luminescence thermal stability

Yanbin Li,Chaoyang Ma,Wanggui Ye,Chuandong Zuo,Yuzhen Wang,Xiaofei Shen,Zhanglin Chen,Chen Chang,Xuanyi Yuan,Yongge Cao

Developing new phosphor ceramics with higher thermal conductivity is a matter of priority for high power solid-state lighting. Herein, translucent red-emitting AlN : Mn phosphor ceramic with high thermal conductivity (72.37 W m −1  K −1 at 25 °C) and high luminescence thermal stability are successfully fabricated by pressureless sintering at 1800 °C for 3 h. Preparation process, photoluminescence , afterglow and electronic compensation mechanisms were discussed in detail. TEM analysis showed that the tiny grain boundaries are composed of disordered Al 2 O 3 phases. The EPR and TL spectra were used to reveal the O-related trap distribution. The AlN: Mn phosphor ceramics have brightly red afterglow with the longest afterglow time of 88 s and possess high luminescence thermal stability, that is to say, the luminescence intensity at 250 °C preserves 93.7% of that at room temperature . The encapsulated AlN: Mn LED device has a very bright red emission peak at 598 nm with a color purity of about 99%, indicating great application potential in solid-state lighting.

Enhanced mechanical and thermal properties of AlN ceramics via a chemical precipitation process

Guanglin Nie,Pengfei Sheng,Yehua Li,Fei Zuo,Yiwang Bao,Shanghua Wu

A uniform dispersion of sintering additives is crucial to improve the thermal and mechanical properties of AlN ceramics. In this study, the Y 2 O 3 -coated AlN composite powder was successfully prepared by the chemical precipitation (CP) process, thereby improving the homogenization of Y 2 O 3 in AlN green compacts. The precipitation coating behavior of Y 2 O 3 precursor was investigated by FTIR and TG-DSC, and the corresponding reaction equation was proposed. The results of TEM, XRD, and XPS for the CP processed AlN powder indicated that a uniform amorphous Y 2 O 3 layer was fully wrapped on the surface of AlN powder. The microstructures and phases of the sintered AlN samples prepared via the CP and conventional ball-milling (BM) processes, respectively, were compared. The CP process can result in decreasing oxygen content in AlN grains, facilitating the formation of the desirable isolated second phases, and strengthening the grain and grain boundary of AlN ceramic. As a result, the thermal conductivity, bending strength and fracture toughness of the CP processed AlN ceramic are 9.43%, 10.56%, and 18.50% higher than those of the BM processed sample, respectively, illustrating the CP process is a pretty effective way to simultaneously improve the thermal and mechanical properties of AlN ceramics.

Anisotropic epoxy composites with enhanced thermal conductivity via constructing unidirectional porous AlN reinforcements

Zhilei Wei,Huiyu Qi,Yinuo Ma,Wenqi Xie,Lei Zhao,Bo Wang,Zhenxia Yuan,Zhongqi Shi

The ongoing miniaturization and increasing integration density of modern microelectronic devices have made thermal management a critical challenge for sustained performance advancement. While polymer/ceramic composites are commonly used as thermal management materials, their effectiveness is fundamentally limited by discontinuous thermal conductive pathways, resulting in unsatisfied thermal conductivity (TC). Although increasing filler loading can enhance TC, it typically compromises processability and mechanical properties of the composites. To address these limitations, unidirectional porous (UP) AlN ceramics were innovatively fabricated via freeze casting followed by combustion synthesis, which were subsequently incorporated into epoxy matrices. At a AlN loading of 47.5 vol%, the composites achieved the TC ∥ (parallel to the channels) of 10.30 W·m -1 ·K -1 and TC ⊥ (perpendicular to the channels) of 6.03 W·m -1 ·K -1 , respectively. Comprehensive evaluations through both experimental CPU cooling tests and finite element simulations verified their superior thermal dissipation capability. The UP AlN reinforcement further enhanced the mechanical properties of the composites and facilitated their long service life. This work presents a scalable and cost-effective material solution for advanced thermal management in high-power microelectronics.

Pressure-induced transparency of MgO, Al2O3, AlN, and cBN ceramics at room temperature

Yuzhu Su,Junpu Wang,Xin Li,Qiqi Tang,Jing Yang,Li Lei,Yi Tian,Zhiwei Wang,Duanwei He

The in situ axial X-ray diffraction patterns of four ceramic powder samples (MgO, Al 2 O 3 , AlN , and cBN) that were compressed in a diamond anvil cell under uniaxial non-hydrostatic conditions were recorded. The microscopic deviatoric stress as a function of the pressure was determined from the X-ray diffraction peak broadening analysis: the curves increased approximately linearly with the pressure at the initial compression stage and then levelled off under further compression. Pressure-induced transparency was observed in all of the samples under compression, and the pressure at the turning point on the curves of the microscopic deviatoric stress versus pressure corresponded to the pressure at which the samples became transparent. Analysis of the microstructural features of the pressure-induced transparent samples indicated that the compression caused the grains to fracture, and the broken grains bonded with each other. We demonstrated that the ceramics’ pressure-induced transparency was a process during which the grains were squeezed and broken, the pores were close between the grains, and the broken grains were re-bonded under compression.

Micro-nano hierarchical SPBID/AlN composites breaking the thermal conductivity-insulation trade-off

Xiaoxiao Chen,Wenxia Sima,Potao Sun,Ninglong Fu,Tao Yuan,Ming Yang,Zhaoping Li,Wenlong Pang

Nanoporous structures have demonstrated remarkable potential for enhancing breakdown strength by suppressing internal gas ionization, enabling the development of ultra-insulating materials. However, their inherent gas-solid interfaces induce severe phonon scattering, posing a challenge for the simultaneous improvement of electrical insulation and thermal conductivity. Herein, we report a cross-scale structural design strategy that integrates multiple functions, a starch-based polyorganosiloxane biocomposite insulating dielectric/aluminum nitride (SPBID/AlN) composites is fabricated, featuring a micro–nano scale nested architecture. The microscale AlN framework provides thermal conductivity while the nanoscale SPBID ensures superior electrical insulation, effectively resolving the trade-off between high breakdown strength and high thermal conductivity. SPBID/AlN exhibits lightweight, high mechanical strength, low relative permittivity, and biodegradability, especially, promising potential for combining with atmospheric CO 2 to form high-performance and carbon-sequestering insulating material. Specifically, when SPBID/AlN integrates with insulating gases (CO 2 , SF 6 ), the breakdown strength is significantly enhanced by 711.91 % and 270.42 % compared to the pure gases, respectively. Furthermore, SPBID/AlN achieves high thermal conductivity (2.51 W/(m·K)), representing 15.68-fold and 75.06-fold improvements compared to epoxy (0.16 W/(m·K)) and nanoporous SPBID (0.033 W/(m·K)), respectively. The continuous thermal pathways in AlN facilitate efficient heat transport. Overall, this study presents a novel strategy for the development of future high-performance, lightweight, and eco-friendly power equipment and electronic devices.

Up-conversion luminescence and optical thermometry of Yb3+/Tm3+ co-doped AlN nanowires

Minghan Zhou,Tongtong Gao,Shuanglong Chen,Xuejiao Wang,Qiushi Wang,Cailong Liu

Due to its unique advantages including non-contact operation, high sensitivity, and exceptional spatial resolution, nanoscale optical thermometry has become an indispensable technique with widespread applications in micro/nanoelectronics, integrated photonic systems, and biomedical engineering. Here, Yb 3+ /Tm 3+ co-doped AlN nanowires were successfully synthesized via an arc-discharge method. The nanowires, characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy, exhibit lengths of several micrometers and uniform diameters ranging from 10 to 20 nm, yielding a high aspect ratio. Under 980 nm excitation, the nanowires display distinct up-conversion (UC) luminescence, with emission bands at 544 nm (green), 654 nm and 691 nm (red), and 795 nm (near-infrared), corresponding to Tm 3+ ion transitions. The AlN:Yb 3+ /Tm 3+ nanowires show excellent optical thermometry performance, achieving a maximum relative sensitivity ( S r ) of 3.32 % K −1 at 298 K and a temperature resolution ( δT ) of 0.009 K. These results underscore the potential of AlN:Yb 3+ /Tm 3+ nanowires for advanced optical temperature sensing in nanotechnology, biomedical applications, and high-resolution thermal imaging.