今日更新:Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
In-situ crosslinked polyetherimide/BNNS composites with ultrahigh charged-discharged efficiency at high temperature
Liu Zheng, Wang Tianze, Zhu Lixue, Jiang Zhenhua, Zhang Yunhe
doi:10.1016/j.compositesa.2023.107829
在高温下具有超高充放电效率的原位交联聚醚酰亚胺/BNNS 复合材料
High performance dielectric polymer composites for capacitive energy storage have been a hot topic in recent years. However, dielectric materials tend to breakdown at high temperature, and its charged-discharged efficiency is greatly reduced. Therefore, preparing high-efficient high-temperature dielectric material is the main challenge in this field. In this work, based on the synergistic effect of in-situ composite and controlled thermal cross-linking, the thermal conducting nano filler and crosslinking system composite has ultra-high charged-discharged efficiency at high temperature. It is proved that the addition amount of BNNS for the peak performance of this kind of composite is 10 vol% and the discharge energy density is 4.58 J/cm3 and the charged-discharged efficiency reaches 96 % at 150 °C and 500 MV/m. At 200°C and 300 MV/m, these are 1.76 J/cm3 and astonishing 95 %. It is expected to be a candidate for a new generation of high temperature resistant dielectric materials.
用于电容式储能的高性能介电聚合物复合材料是近年来的热门话题。然而,介电材料在高温下容易发生击穿,其充放电效率会大大降低。因此,制备高效的高温介电材料是这一领域的主要挑战。在这项工作中,基于原位复合和可控热交联的协同效应,导热纳米填料和交联体系复合材料在高温下具有超高的充放电效率。实验证明,这种复合材料达到峰值性能的 BNNS 添加量为 10 Vol%,在 150°C 和 500 MV/m 条件下,放电能量密度为 4.58 J/cm3,充放电效率达到 96%。在 200°C 和 300 MV/m 条件下,放电能量密度为 1.76 J/cm3,放电效率达到惊人的 95%。它有望成为新一代耐高温介电材料的候选材料。
Self-Healing Polyurethane Coating based on Porous Carbon/Ni Hybrids Composites for Electromagnetic Wave Absorption
Han Qiaoqiao, Wang Shuang, Cheng Xu, Du Xiaosheng, Wang Haibo, Du Zongliang
doi:10.1016/j.compositesa.2023.107830
基于多孔碳/镍杂化复合材料的用于电磁波吸收的自愈合聚氨酯涂层
Developing a lightweight, effective, and durable electromagnetic wave (EMW) absorbing coating is still a challenge. Herein, a novel self-repairable polyurethane (PU)-disulfide (SS)/porous carbon (PC)/Ni coating is initially assembled. The heterogeneous PC/Ni filler is derived from inexpensive cation exchange resins. And the texture, porous structure, defect, and electron transport can be adjusted by simply adjusting the carbonization temperature. The PU-SS/PC/Ni-700 °C presents an optimal reflection loss (RL) of −45.8 dB at a low loading (10wt%) in X-band thanks to enhancements in polarization relaxation, magnetic resonance, multiple reflection and scattering, surpassing most reported fillers. Meanwhile, the disulfide and hydrogen bonds in the PU-SS matrix are in charge of repairing the coating’s cracks and EMW adsorption capacity together after damage. Specifically, RL can recover −41.1 dB, after sunlight irradiation for 120 s. In short, this work may offer valuable inspiration for the fabrication of lightweight, efficient, long-life, low-cost, and mass-produced EMW absorption coatings.
开发轻质、有效、耐用的电磁波(EMW)吸收涂层仍是一项挑战。在此,我们初步组装了一种新型的可自我修复聚氨酯(PU)-二硫化物(SS)/多孔碳(PC)/镍涂层。异质 PC/Ni 填料来自廉价的阳离子交换树脂。只需调节碳化温度,就能调整质地、多孔结构、缺陷和电子传输。由于偏振弛豫、磁共振、多重反射和散射的增强,PU-SS/PC/Ni-700 ℃在低负载(10wt%)条件下,X 波段的最佳反射损耗(RL)为 -45.8 dB,超过了大多数已报道的填料。同时,聚氨酯-聚苯硫醚基体中的二硫键和氢键还能修复涂层的裂缝,并在受损后恢复电磁波吸附能力。总之,这项研究为制造轻质、高效、长寿命、低成本和大规模生产的电磁波吸收涂层提供了宝贵的灵感。
Significant reduction of grain size and texture intensity in laser powder bed fusion fabricated nickel-based superalloy by increasing constitutional supercooling
Zhao Yanan, Ma Teng, Gao Zhengjiang, Feng Yiyu, Li Chong, Guo Qianying, Ma Zongqing, Liu Yongchang
doi:10.1016/j.compositesb.2023.111040
通过增加宪法过冷度显著降低激光粉末床熔融制造镍基超合金的晶粒尺寸和纹理强度
Coarse columnar grains are always present in nickel-based superalloys fabricated by laser powder bed fusion (LPBF), which not only causes anisotropy in mechanical properties, but also increases the hot cracking susceptibility of the alloys. Generally, the addition of nucleating agents is a common consideration for grain refinement. However, the intrinsic ultra-high thermal gradient and cooling rate of the LPBF process result in significant differences in grain nucleation and growth compared to conventional casting. The ultra-high thermal gradient of the LPBF process severely inhibits constitutional supercooling, which significantly reduces the heterogeneous nucleation efficiency of nickel-based superalloys. In this work, we introduced Zr into Haynes 230 alloy to improve constitutional supercooling of the LPBF molten pool during solidification and investigated the individual/synergistic effects of nucleating agent (TiC particles) and solute (Zr atoms) addition on the grain refinement of Haynes 230 alloy. It was found that the columnar grain size and texture intensity of LPBF fabricated Haynes 230 alloys were dramatically decreased with Zr and TiC co-addition, which obviously improved the mechanical properties as well as weakened its anisotropy. Our work revealed that inhibition of cell epitaxial growth and promotion of cell nucleation are necessary conditions to refine the grain size of LPBF fabricated nickel-based superalloys. Solutes with high growth restriction factor (Q value), such as Zr in our work, can rapidly generate constitutional supercooling, thereby obviously improving the heterogeneous nucleation efficiency of nucleating agents in nickel-based superalloy during the LPBF process.
通过激光粉末床熔融(LPBF)制造的镍基超合金中总是存在粗大的柱状晶粒,这不仅会导致机械性能的各向异性,还会增加合金的热裂敏感性。一般来说,添加成核剂是晶粒细化的常见考虑因素。然而,LPBF 工艺固有的超高热梯度和冷却速度导致晶粒的成核和生长与传统铸造工艺有很大不同。LPBF 工艺的超高热梯度严重抑制了制宪过冷,从而大大降低了镍基超合金的异质成核效率。在这项工作中,我们在 Haynes 230 合金中引入了 Zr,以改善 LPBF 熔池在凝固过程中的立宪过冷,并研究了成核剂(TiC 粒子)和溶质(Zr 原子)的添加对 Haynes 230 合金晶粒细化的单独/协同效应。研究发现,在 Zr 和 TiC 共同添加的情况下,LPBF 制备的 Haynes 230 合金的柱状晶粒尺寸和纹理强度显著减小,从而明显改善了其机械性能并削弱了其各向异性。我们的研究揭示了抑制细胞外延生长和促进细胞成核是细化 LPBF 制备的镍基超级合金晶粒尺寸的必要条件。具有高生长限制因子(Q 值)的溶质,如我们工作中的 Zr,可迅速产生宪态过冷,从而明显提高 LPBF 过程中成核剂在镍基超合金中的异质成核效率。
Damage evolution model and failure mechanism of continuous carbon fiber-reinforced thermoplastic resin matrix composite materials
Zhu Tianqi, Ren Zhiying, Xu Jian, Shen Liangliang, Xiao Chenglong, Zhang Chao, Zhou Xin, Jian Xigao
doi:10.1016/j.compscitech.2023.110300
连续碳纤维增强热塑性树脂基复合材料的损伤演化模型与失效机理
As a new composite material with high strength, toughness, and heat resistance, the continuous fiber-reinforced polyaryl ether sulfone ketone (PPESK) thermoplastic resin matrix composite (CFRP) has a wide temperature range, which is attributed to the complex temperature sensitivity of the matrix. The failure evolution characteristics under different conditions are not clear yet, which significantly limits its development and application to high-precision equipment. In this work, in order to deeply explore the full three-dimensional (3D) multi-scale multi-physics damage evolution mechanism of the CFRP over a wide temperature range, macroscale cross-temperature stretching/bending experiments, computer tomography (CT) scanning, and microscale scanning electron microscopy (SEM) are performed to effectively capture the overall damage morphology and local fiber/matrix damage failure characteristics of the material. The results show that the reinforcement with continuous fibers increases the tensile strength of the CFRP by 14–45 times and its bending strength by 2–6 times compared to those of the PPESK matrix in the cross-temperature domain. Moreover, the main failure mechanism of the CFRP in the cross-temperature domain is matrix crushing and fiber fracture at room temperature and fiber fretting slip and matrix viscous flow at high temperatures. This further explains the deformation mechanism of the CFRP, which can maintain its stability at high temperatures (low elongation at break: 1%–1.2%). The unique trans-temperature regional energy evolution and continuous fiber reinforcement of the material matrix resin PPESK lay the synergic stability of the high temperature performance and damage morphology of the CFRP. In particular, a cell model is constructed to further reveal the damage evolution characteristics of the matrix, fiber, and interface of the CFRP at the micro-scale. Combined with the failure mode theory and the performance degradation mechanism of composite materials, the temperature influence factor is introduced to formulate a multi-scale full 3D temperature-dependent damage evolution constitutive model of the CFRP over a wide temperature range. The constitutive model of the CFRP is incorporated in finite element software, and the simulation results are compared with the experimental ones for validation. The results show that the model developed in this work can effectively characterize the complex mechanical damage morphology and progressive failure characteristics of the CFRP over a wide temperature range.
连续纤维增强聚芳醚砜酮(PPESK)热塑性树脂基复合材料(CFRP)作为一种具有高强度、韧性和耐热性的新型复合材料,其使用温度范围较宽,这与基体复杂的温度敏感性有关。其在不同条件下的失效演化特性尚不明确,这极大地限制了其在高精密设备上的开发和应用。在这项工作中,为了深入探索 CFRP 在宽温度范围内的全三维(3D)多尺度多物理场损伤演化机理,进行了宏观跨温度拉伸/弯曲实验、计算机断层扫描(CT)和微观扫描电子显微镜(SEM),以有效捕捉材料的整体损伤形态和局部纤维/基体损伤失效特征。结果表明,与跨温域的 PPESK 基体相比,使用连续纤维增强的 CFRP 拉伸强度提高了 14-45 倍,弯曲强度提高了 2-6 倍。此外,跨温域 CFRP 的主要失效机理是常温下基体破碎和纤维断裂,以及高温下纤维咬合滑移和基体粘流。这进一步解释了 CFRP 的变形机理,即它能在高温下保持稳定(低断裂伸长率:1%-1.2%)。材料基体树脂 PPESK 独特的跨温区域能量演化和连续纤维加固奠定了 CFRP 高温性能和损伤形态的协同稳定性。特别是通过构建单元模型,进一步揭示了 CFRP 的基体、纤维和界面在微观尺度上的损伤演化特征。结合失效模式理论和复合材料的性能退化机理,引入温度影响因子,建立了宽温度范围内 CFRP 的多尺度全三维温度依赖性损伤演化构成模型。将 CFRP 的构成模型纳入有限元软件,并将模拟结果与实验结果进行对比验证。结果表明,这项工作中开发的模型可以有效地表征 CFRP 在宽温度范围内复杂的机械损伤形态和渐进失效特征。