查找使用阿拉丁产品的科研文献

Synergistic enhancement of mechanical and thermal properties in AlN ceramics via laminated distribution of Sm2O3 and Y2O3 sintering additives

Shuang Ou,Zhifeng Huang,Tang Tang,Binhua Xiang,Guangyi Liu,Yizhen Chu,Qinggang Li,Guanchao Yin,Qiang Shen,Fei Chen

AlN ceramics are widely used in integrated circuit thermal management and packaging materials due to their excellent thermal conductivity, insulating properties, and thermal expansion coefficient similar to silicon. However, traditional hot-press sintering processes often struggle to produce homogeneous AlN ceramics that combine high thermal conductivity with excellent flexural strength. Furthermore, different sintering additives used in AlN ceramics have varying effects on their mechanical and thermal properties. Therefore, this study first conduct a preliminary screening of five different sintering additives and select two specific sintering additives for the laminate design. The Sm 2 O 3 additive demonstrates the highest flexural strength while the Y 2 O 3 additive showcases the highest thermal conductivity. Subsequently, laminated AlN ceramics with Sm 2 O 3 additive in the surface and Y 2 O 3 additive in the intermediate layer are fabricated to synergistically improve the strength and thermal conductivity. The laminated AlN ceramic exhibits a thermal conductivity of 150 W m −1  K −1 and a flexural strength of 458 MPa. These improvements are attributed to enhanced fine-grain strengthening coupled with its dense structure and isolated secondary phase distribution. This work provides a feasible strategy for synergistic enhancement of mechanical and thermal properties in AlN Ceramics via laminated distribution of sintering additives.

Novel PRSi/AlN aerogel composites enabled synergistic thermal insulation and microwave absorption by sealing enhancement strategy and spontaneous ceramization

You Qi,Zhao Yiqi,Zhong Ya,Xu Fuhao,Zhang Xuanfeng,Cui Sheng

The rapid advances in aerospace technology have intensified challenges related to extreme thermal and electromagnetic environments. The excellent thermal conductivity and low dielectric loss of AlN limit its use in applications requiring thermal insulation and microwave absorption. Herein, a sealing enhancement strategy (SES) was designed to fabricate silane-modified phenolic resin-reinforced AlN (PRSi/AlN) aerogel composites that combine high strength with spontaneous high-temperature ceramization. The directional pore channels of the AlN/C aerogel are filled with continuous silane-modified phenolic resin (PRSiO 2 ) aerogels, forming a unique sealed structure. Impressively, the composites achieve a compressive strength 492 times that of the AlN/C skeleton, coupled with a low axial thermal conductivity of 0.0382 W·m − 1 ·K − 1 . The oxidation of AlN is followed by spontaneous mullitization with SiO 2 during thermal exposure, leading to the formation of a stable mullite phase. Under a short-duration oxyacetylene flame (1.2 MW·m − 2 ), the composites maintained a backside temperature between 53.4 °C and 68.4 °C, with a linear ablation rate of 0.071 mm·s − 1 . Furthermore, the excellent microwave absorption results from synergistic effects within the carbonized layer, where interfacial polarization, dipole polarization, and conduction loss collectively enhance electromagnetic wave (EMW) dissipation. Both composites show excellent performance: PRSi1.0/AlN has a minimum reflection loss (RL min ) of -61.84 dB and an effective absorption bandwidth (EAB) of 5.83 GHz, while PRSi2.0/AlN achieves an even broader EAB of 7.06 GHz. This SES effectively strengthens PRSi/AlN composites by harnessing the advantages of both the reinforcement phase and skeleton, offering a novel paradigm for fabricating thermal protection composites.

Modulation of optical performances of YAG:Ce glass-ceramics for laser-driven lighting through doping with high thermal conductivity AlN

Xiaolong Zhang,Kailong Ma,Shuo Wang,Pengchong Zhang,Lei Wu,Pengfei Li,Jinsheng Li,Xiwei Qi

The inadequate dissipation of heat and the suboptimal color quality of phosphor converters have been identified as critical constraints in the implementation of laser-driven lighting technology. In recent years, laser lighting has attracted significant attention as a pivotal direction for next-generation illumination systems. However, the thermal quenching effect induced by high-power blue laser sources significantly reduces the emission efficiency of phosphors, presenting a critical challenge that demands urgent resolution. In this study, we successfully fabricated AlN-YAG:Ce composite amorphous spheres by using the non-container solidification technique. The theoretical thermal conductivity of the glass-ceramic with 15 wt% AlN added was 23.13 W/(m∙K). Addressing the inherent limitation of weak luminescent properties in amorphous materials, crystallization treatment was implemented while preserving their advantageous characteristics. The amorphous crystallization treatment was found to be a successful method of achieving controllable optimization of high-efficiency luminescent performance. This objective was achieved through significantly enhancing emission efficiency via localized crystallization (formation of nanocrystalline or microcrystalline structures) in amorphous materials. Through systematic optimization and evaluation, the 15% AlN-YAG:Ce crystallized at 951 °Cglass-ceramic sample with an optimized thickness of 1 mm exhibited exceptional performance: under 1 W/mm 2 blue laser excitation, it achieved a luminous efficacy of 335.3 lm/W with a blue light absorptivity of 89.7% and a low correlated color temperature of 4405.4 K. The technology employed for the composite glass-ceramic's preparation offers a novel solution for the advancement of laser lighting technology.

Nano-BN encapsulated micro-AlN as fillers for epoxy composites with high thermal conductivity and sufficient dielectric breakdown strength

Tong Yao,Ke Chen,Tao Shao,Cheng Zhang,Chuyan Zhang,Ying Yang

Targeting cooling for YAG:Ce3+-based laser-driven lighting device by blending high thermal conductivity AlN in phosphor-sapphire composite

Lei Jin,Shuting Liu,Shuaichen Si,Xikun Zou,Haoran Zhang,Yingliang Liu,Wei Li,Mingtao Zheng,Jianle Zhuang,Chaofan Hu,Xuejie Zhang,Bingfu Lei

Thermal stability and heat dissipation of all-inorganic color convertors are the key obstacles for high-power laser-driven lighting devices. Herein, we proposed an efficient heat dissipation approach to solve these issues by blending high thermal conductivity AlN in a YAG:Ce 3+ -based phosphor-sapphire composite (abbreviated as PSC) plate. Notably, the most elevated surface working temperature of the AlN-filled PSC (AlN-PSC) is dramatically decreased by 266.9 °C at a blue laser power density of 10.99 W/mm 2 compared with that of without AlN-filled PSC (AlN-Free-PSC), implying that the AlN particles effectively acted as heat transfer channels to dissipate the accumulated heat to ambient air and sapphire substrate. Benefitting from the AlN particles also act as scattering centers, a transmissive mode solid-state laser lighting device was fabricated using 10 wt% AlN-PSC and 442 nm blue laser, which maintains a luminous efficacy of 133 lm/W and a luminous flux of 1000 lm without sacrificing the optical performance in comparison with AlN-Free-PSC based white LDs. The proposed method aims at enhancing the heat removal in phosphor glass films and may lead to the development of adding other new reinforcing fillers with high thermal conductivity in heat-conducting PSC.

Understanding high-temperature corrosion behavior of an AlN/Mo functionally graded material exposed to Li/LiF-LiCl-LiBr vapor

Mingyong Jia,Fei Chen,Xipeng Tan,Yaling He,Yueqi Wu,Qiang Shen

The high-temperature corrosion behavior of an AlN/Mo functionally graded material (FGM) under the Li/LiF-LiCl-LiBr vapor has been investigated. It is suggested that the Li vapor diffuses along the AlN and AlN/Mo grain boundaries and enters the interior of adjacent AlN grains, leading to the disintegration of AlN grains and subsequent failures. The 3D Mo networks are barely corroded, thus preventing cracking that may occur due to the inconsistent deformation inside the FGM. This work unravels the high-temperature corrosion mechanisms for the AlN/Mo FGM. Meanwhile, the operating temperature threshold for the liquid metal batteries employing Mo/AlN/Mo seals is determined to be ∼ 600 °C.

Study on the composition, microstructure and mechanical properties of PCBN composites synthesized by TiN–AlN–Ti combined with cBN

Mo Peicheng,Chen Jiarong,Chen Chao,Hu Qiaofan,Pan Xiaoyi,Xiao Leyin,Lin Feng

Polycrystalline cubic boron nitride (PCBN) was synthesized at high temperature and ultra-high pressure, using cBN, TiN, AlN and Ti as starting materials. The effects of CBN content (48–63 wt%) and sintering temperature (1300–1600 °C) on the composition, microstructure and mechanical properties of PCBN materials were studied. X-ray diffraction and scanning electron microscope were used to analyze the phase composition, microstructure and surface crack morphology of PCBN. At the same time, the compactness, microhardness, fracture toughness and flexural strength of PCBN were tested. Research shows that the phase components of PCBN samples are mainly composed of BN, TiB 2 , TiN and AlN. Almost all Ti reacts with cBN during the sintering process to form TiN and TiB 2 phases. When the sintering temperature is 1500 °C, the reaction has been fully completed. When the cBN content increases from 48 to 63 wt%, the relative density, flexural strength and hardness of PCBN increase with the increase in cBN content. When sintered at 1500 °C and the cBN content is 63 wt%, the relative density, flexural strength, fracture toughness and microhardness of the composite are 99%, 820.8 MPa, 6.6 MPa.m 1/2 and 3362 Hv, respectively.

Two-dimension Al2O3-AlN heterogeneous nanosheets as bifunctional host materials for kinetics-accelerated and dendrite-free lithium-sulfur batteries

Xinran Hou,Lin Li,Shuaichong Wei,Jingde Li,Feichao Wu

The polysulfides shuttle and the uncontrolled dendrite growth remain the biggest roadblocks to the extensive application of lithium-sulfur batteries (LSBs). Herein, we propose heterogeneous Al 2 O 3 -AlN nanosheets that rooted on carbon nanofiber film as bifunctional hosts for these troubles, which are prepared by the facile ammonification of two-dimension metal-organic framework MIL-101(Al). As the sulfur host, the Al 2 O 3 -AlN nanosheets exhibit a strong synergistic effect of physicochemical anchoring and outstanding electrocatalysis on polysulfides, which is strengthened by the superiorities of heterostructure. In the meantime, the excellent conductivity and fully exposed Al, N lithiophilic sites guarantee a fast and homogeneous Li deposition, thus suppressing the dendritic growth. Accordingly, with the assistance of these distinctive heterogeneous nanosheets, LSBs provide a striking capacity of 730 mAh g −1 and an outstanding cycling stability with a narrow decay of 0.025% per cycle for 1000 cycles under 5 C, and also excellent cycle and rate properties at high sulfur loadings with a reduced electrolyte. This work offers new viewpoints of heterostructures as both cathode and anode materials for advanced LSBs.

Oriented Three-Dimensional Skeletons Assembled by Si3N4 Nanowires/AlN Particles as Fillers for Improving Thermal Conductivity of Epoxy Composites

Baokai Wang,Shiqin Wan,Mengyang Niu,Mengyi Li,Chang Yu,Zheng Zhao,Weiwei Xuan,Ming Yue,Wenbin Cao,Qi Wang

With the miniaturization of current electronic products, ceramic/polymer composites with excellent thermal conductivity have become of increasing interest. Traditionally, higher filler fractions are required to obtain a high thermal conductivity, but this leads to a decrease in the mechanical properties of the composites and increases the cost. In this study, silicon nitride nanowires (Si3N4NWs) with high aspect ratios were successfully prepared by a modified carbothermal reduction method, which was further combined with AlN particles to prepare the epoxy-based composites. The results showed that the Si3N4NWs were beneficial for constructing a continuous thermal conductive pathway as a connecting bridge. On this basis, an aligned three-dimensional skeleton was constructed by the ice template method, which further favored improving the thermal conductivity of the composites. When the mass fraction of Si3N4NWs added was 1.5 wt% and the mass fraction of AlN was 65 wt%, the composites prepared by ice templates reached a thermal conductivity of 1.64 W·m−1·K−1, which was ~ 720% of the thermal conductivity of the pure EP (0.2 W·m−1·K−1). The enhancement effect of Si3N4NWs and directional filler skeletons on the composite thermal conductivity were further demonstrated through the actual heat transfer process and finite element simulations. Furthermore, the thermal stability and mechanical properties of the composites were also improved by the introduction of Si3N4NWs, suggesting that prepared composites exhibit broad prospects in the field of thermal management.Keywords:silicon nitride nanowires;thermal interface materials;ice template method;thermal conductivity

Rectangular cross-sectional Nd3+/Yb3+ co-doped AlN nanorods with strong up-conversion emission for high-sensitivity optical thermometry

Jiaqi Wang,Xin Ding,Tongtong Gao,Huiling Zheng,Xuejiao Wang,Qiushi Wang,Cailong Liu

Due to the characteristics of non-contact, high sensitivity and spatial resolution, nanoscale optical thermometry is necessary in many applications such as micro/nano electronics, integrated optics and biomedicine. Herein, we report the synthesis of Nd 3+ /Yb 3+ co-doped AlN (AlN:Nd 3+ /Yb 3+ ) nanorods using an arc discharge method and investigate their phase, composition and morphology using XRD, Raman, XPS, EDS, ICP, SEM and TEM. The nanorods with rectangular cross-section are highly single crystalline and have a uniform smooth surface. Upon excitation at 980 nm, AlN:Nd 3+ /Yb 3+ nanorods exhibit up-conversion (UC) visible emission bands (around 544, 595 and 667 nm) and near-infrared emission bands (around 755 and 806 nm), which correspond to intra-4f electron transitions of the Nd 3+ ions. Later, the temperature dependence of UC luminescence behavior was systemically studied using luminescence intensity ratio (LIR) technique. It was verified that LIRs with non-thermally coupled levels ( 4 G 7/2 / 4 F 5/2 or 4 G 7/2 / 4 F 7/2 ) are suitable for temperature sensing. The maximum relative sensitivity based on 4 G 7/2 / 4 F 7/2 is 4.63% K −1 at 298 K, which is one of the highest values reported for optical thermometers. This work provides an efficient method for synthesizing wide-band gap semiconductors with doped size-mismatched functional atoms that can be used for high-sensitivity optical thermometry.

Synergistic enhancement of thermal conductivity, dielectric properties, and flexural strength in AlN ceramics via Y₂O₃–LiF sintering and annealing

Deyin Liang,Xiaoqiang Li,Wenlong Yin,Chaoyang Zhang,Bo You,Shengquan Yu

The effects of Y₂O₃–LiF sintering additives on the microstructure, thermal conductivity, flexural strength, and dielectric properties of AlN-based ceramics were systematically investigated. Six different compositions were prepared via ball milling, hot-press sintering, and annealing. XRD and Rietveld refinement confirmed a hexagonal structure for all samples, with changes in the Al–N bond length along the C-axis. SEM analysis revealed that the Y₂O₃–LiF additives modified the morphology of the secondary phase while maintaining a high bulk density. Moreover, annealing resulted in grain boundary purification. As LiF content increased, the second-phase morphology evolved from oval to strip-like, and annealing reduced this phase, improving overall performance. Raman spectroscopy indicated lattice expansion and a blue shift with increasing LiF content. Dielectric analysis of the 2 wt% LiF–Y₂O₃ sample revealed a dielectric constant of 8.56, a dissipation factor of 2.1 × 10⁻⁴, and a high activation energy of 1.38 eV.

Heat transfer characteristics of AlN porous ceramic skeleton/molten salt composite phase change materials for mid-temperature thermal energy storage

Mingjin Xin,Yuliang Huang,Huan Wang,Ziyuan Li,Wandong Cheng,Limei Tian,Liyan Wu,Jianfeng Lu

A 3D-Ct porous ceramic skeleton was fabricated using photocuring 3D Printing. • The porous ceramic skeleton can accommodate up to 90% molten salt. • The maximum thermal conductivity of the composite PCMs is 2.23 W·m −1 ·K −1 . • The heat storage rate of the composite PCMs can be increased by up to 45.48%. Porous ceramic skeletons exhibit excellent performance in enhancing the heat transfer capacity of molten salt phase change materials (PCMs). However, the low connectivity and structural uncontrollability of their pore struts have limited further improvements in molten salt heat transfer performance. In this study, a three-dimensional continuous Topological (3D-Ct) porous ceramic skeleton with a topological structure was proposed and fabricated by 3D printing coupled with liquid-phase silicon infiltration reaction sintering. The 3D-Ct porous ceramic skeleton/molten salt composite PCMs were prepared using a melt-impregnation method, and their heat transfer performance was investigated both experimentally and numerically. The results showed that the 3D-Ct porous ceramic skeleton provides outstanding heat transfer performance. Compared with pure molten salt PCMs, the 3D-Ct porous ceramic skeleton/molten salt composite PCMs exhibits a 35.31% higher melting rate, a 45.48% increase in heat storage rate, and a 45.50% increase in Nusselt number ( Nu ). In addition, the maximum temperature difference among the measurement points was reduced by 14.3 °C. The numerical simulation results indicate that the 3D-Ct porous ceramic skeleton suppresses heat convection during the phase change of the PCMs, while accelerating PCMs melting and yielding a more uniform overall velocity field. This work proposes a novel structural design strategy for porous ceramic skeletons, overcoming the bottlenecks of low connectivity and poor structural controllability in their pore struts. It also lays a foundation and provides a theoretical basis for the structural design and development of heat energy storage devices.