Anti-penetration performance of high entropy alloy-ceramic gradient composites

A high-entropy alloy-ceramic gradient composite of TiC-TiB₂/75vol% Al_0.3CoCrFeNi was successfully prepared by combustion synthesis under an ultra-high gravity field, which is a low-cost method with high efficiency. The ceramic particles were gradient distributed in the Al_0.3CoCrFeNi matrix, and the hardness of the composite material gradually decreased along the thickness direction. The anti-penetration performance of the gradient composites was simulated using the ANSYS/LS-DYNA explicit simulation program. The results demonstrate that the distribution of the ceramic particles strongly affected the mechanical properties and the anti-penetration performance of the composites. With the same total ceramic volume fraction, the gradient composites exhibit better anti-penetration performance than the corresponding ceramic-metal interlayer composites. The more uneven the ceramic distribution, the greater the elastic modulus and yield stress of the surface layer and, thus, the better the anti-penetration performance.     

高重力燃烧合成WC/CoCrFeNiAl0.2高熵合金复合材料

The WC/CoCrFeNiAl_0.2 high-entropy alloy (HEA) composites were prepared through high-gravity combustion synthesis. The preparation method is presented below. First, using a designed suitable multiphase thermite system, the molten CoCrFeNiAl_0.2 HEA was fabricated using low-cost metal oxides. The molten HEA was subsequently infiltrated into the WC layer to fabricate WC/CoCrFeNiAl_0.2 composites in a high-gravity field. The porosity of the WC/CoCrFeNiAl_0.2 composites was down-regulated, and their compressive yield strength was up-regulated when the high-gravity field was increased from 600gto 1500gbecause this infiltration process of a HEA melt into the WC layer is driven by centrifugal force. The WC particles in the composites exhibited a gradient distribution along the direction of the centrifugal force, which was attributed to the combined action of the high-gravity field and the temperature gradient field. The Vickers hardness of the sample was down-regulated from 9.53 to 7.41 GPa along the direction of the centrifugal force.     

Preparation of WC/CoCrFeNiAl_(0.2) high-entropy-alloy composites by high-gravity combustion synthesis

The WC/CoCrFeNiAl_(0.2) high-entropy alloy(HEA) composites were prepared through high-gravity combustion synthesis. The preparation method is presented below. First, using a designed suitable multiphase thermite system, the molten CoCrFeNiAl_(0.2) HEA was fabricated using low-cost metal oxides. The molten HEA was subsequently infiltrated into the WC layer to fabricate WC/CoCrFeNiAl_(0.2) composites in a highgravity field. The porosity of the WC/CoCrFeNiAl_(0.2) composites was down-regulated, and their compressive yield strength was up-regulated when the high-gravity field was increased from 600 g to 1500 g because this infiltration process of a HEA melt into the WC layer is driven by centrifugal force. The WC particles in the composites exhibited a gradient distribution along the direction of the centrifugal force, which was attributed to the combined action of the high-gravity field and the temperature gradient field. The Vickers hardness of the sample was down-regulated from9.53 to 7.41 GPa along the direction of the centrifugal force.     

聚丙烯复合材料老化数据集成学习

聚丙烯复合材料老化实验周期长, 且单次实验采集的数据样本少, 使用传统机器学习方法进行预测的准确度较低. 为了解决聚丙烯复合材料老化数据样本少与预测准确性低的问题, 提出了一种虚拟样本生成(virtual sample generation, VSG)的集成学习预测方法. 首先, 对聚丙烯复合材料老化数据使用高斯混合模型(Gaussian mixed model, GMM)虚拟样本生成方法平滑生成验证有效的虚拟样本; 然后, 使用生成后的数据集建立集成学习预测模型, 该模型包含随机森林(random forest, RF)、极端梯度提升(extreme gradient boosting, XGBoost)算法、轻量级梯度提升机(light gradient boosting machine, LightGBM)算法以及分类梯度提升(categorical boosting, CatBoost)算法. 实验表明: 集成学习模型的 LightGBM 算法与 CatBoost 算法性能最优, 在测试数据上均方误差为 0.001 3 与 0.000 1, 比 RF 算法与 XGBoost 算法分别高出 0.4 与 0.2. 聚丙烯复合材料老化虚拟样本生成与集成学习方法可以有效解决实验周期长、单次实验采集的数据样本少的问题, 并可取得比单一机器学习算法更优的性能.     

石墨烯/弹性体纳米复合材料研究进展

石墨烯材料由于其超薄的纳米片层结构,优良的导热、导电功能特性,在弹性体复合材料领域已经取得了众多的应用,并赋予了橡胶复合材料更强的动静态力学性能以及导电导热等功能性。本文从石墨烯的制备开始,重点综述了石墨烯的制备及表面修饰,石墨烯/弹性体制备方法,以及复合材料的各项性能,并阐述了三者之间的相互关联。最后提出了石墨烯/弹性体纳米复合材料领域未来应关注的科学和技术问题。     

NiTi薄膜对压电陶瓷材料阻尼性能的影响

采用磁控溅射法在压电陶瓷（PZT）基体上沉积形状记忆合金NiTi薄膜,经过600 °C晶化而制备出PZT/NiTi异质复合阻尼材料,采用X射线衍射仪和扫描电子显微镜等观察分析复合阻尼材料的物相组成及异质间的结合状态,并用相位法评价复合材料的阻尼性能.结果表明,PZT/NiTi异质复合阻尼材料的阻尼性能与PZT类似,但在频率为1.1~1.2 kHz时,其内耗曲线中出现了一个稳定平台.     

玻璃纤维丙纶混并纱纬编针织复合材料拉伸性能的研究

在手摇横机上编织了玻璃纤维丙纶平针织物和罗纹织物预制件，将预制件通过热压成型的方法制得复合材料，并且在材料试验机上测试了复合材料的拉伸性能。结果表明平针和罗纹织物复合材料的拉伸性能存在着差异，同一种复合材料在纵横向的拉伸性能也存在着不同。分析了影响拉伸强度和弹性模量的影响因素，为纬编针织物复合材料的设计和生产提供了依据。     

植物结构铝基复合材料的制备及热学性能

为研制新型复合材料,将植物结构引入到金属基复合材料的制备中.该文以柳桉木材为模板,先将其转变为多孔碳,再通过铝合金和硅树脂的浸渍,制备了具有木材结构的Al/C、Al/(SiC+C)两种铝基复合材料,并通过扫面电镜、热膨胀仪和导热仪对复合材料的微观结构、热膨胀性能及导热性能进行了研究,建立了导热模型.结果发现该复合材料的结构由所选模板的结构决定,这与以往结构完全由人为控制的金属基复合材料不同;并且其热膨胀系数明显低于铝合金,导热系数(98.2和95.4 W·m~(-1)·K~(-1))远高于由木材转化的多孔碳(2.22 W·m~(-1)·K~(-1)).     

三维石墨烯/铜基复合材料的制备及耐腐蚀性能研究

在实际应用中,铜基复合材料经常存在腐蚀失效的现象,而石墨烯以其独特的结构显示出卓越的耐腐蚀性能。为了改善铜基复合材料的耐腐蚀性能,设计并烧结制备了三维石墨烯/铜基复合材料。研究表明,在三维石墨烯/铜基复合材料中,石墨烯形成三维互联互通结构,充分发挥了对铜基体的保护作用。与孔隙铜相比,在质量分数为3.5% NaCl溶液中,三维石墨烯/铜基复合材料的腐蚀速率降低了约50%。石墨烯在金属防腐蚀领域将得到更加广阔的应用。通过研究三维石墨烯/铜基复合材料在FeCl₃溶液中的腐蚀行为,进一步揭示了三维石墨烯的耐腐蚀机理。     

网络互穿金属/高分子复合材料的制备方法及性能研究进展

网络互穿金属/高分子复合材料(IMPC)是一种以三维多孔金属以及多孔高分子网络为主要成分的材料.不同于传统的金属纤维或颗粒增强复合材料,其金属相与高分子相在宏观与微观结构上都各自具有拓扑连续性的网络结构,且相互缠结和贯穿.这使得IMPC中的各相材料在保留自身特性的同时还可相互协同,取长补短,从而使复合材料发挥出更大的性能优势.本文主要概述了IMPC的制备方法及其性能的研究进展,指出了多孔结构的金属在增强金属/高分子复合材料中的优势,展望了IMPC在金属/高分子复合材料的发展前景.     

梯度功能材料的制造方法及应用

梯度功能材料是组分和结构呈连续变化的先进材料 ,由于它具有优异的性能和特殊的功能 ,使其填补了合金化材料和复合材料应用领域的空白 ,具有广阔的应用前景。本文详细叙述了梯度功能材料的设计思想和制造方法 ,论述了梯度功能材料的应用领域及其研究现状。     

石墨烯基TiO_2复合材料的表征及其可见光催化活性研究

以氧化石墨烯与石墨烯为碳源,在熔盐介质中与钛粉反应原位生成石墨烯基TiC中间产物,并通过后续控制氧化制得石墨烯基TiO_2复合光催化剂,结合FTIR、XRD、Raman、SEM等手段,对两种石墨烯材料的结构及形貌差异进行表征,并分析了其对所制复合材料结构、形貌及可见光催化活性的影响。结果表明,所制复合材料仍保持碳源的层片状结构,TiC和TiO_2颗粒均匀包覆在碳源表面;以石墨烯为碳源更有利于表面原位生成TiC晶粒的生长,其晶体结构更为完善;两种结构的石墨烯基TiO_2复合材料均对目标污染物亚甲基蓝有较强的吸附能力和可见光降解能力。     

Impact Performance of 3D Integrated Cellular Woven Composite Panel

This paper studied the impact resistance of 3D integrated cellular woven composite panel under persudo-static impact, comprised the test result with property of typical 3D woven composites, analyzed some parameters that maybe affect composites＇ impact resistance and at last used SEM to observe the damage process and mechanism of samples. The result shows that the impact resistance of 3D integrated cellular woven composites is much better than the performance of typical 3D woven composites; it is an active method to improve the impact resistance of composites that developing preform with cellular on the basis of typical 3D woven structure; for different 3D integrated cellular woven structure, the value of absorbed-energy is increasing with the hollow percentage; tiny deformatlen will not emerge on samples until the acting force gets to 85% of the maximum; similar with typical 3D woven composites, the delaminated phenomenon of 3D integrated cellular woven composites is also unapparent during impact process.     

结构参数变化下梯度结构混凝土的抗压性能

为了分析梯度结构混凝土的保护层厚度、界面取向性及施工工艺对其抗压强度、破坏形式的影响规律, 进行了多组梯度结构混凝土试件的抗压强度试验。试验结果表明: 梯度结构混凝土抗压强度随保护层厚度的增加而增大; 与串联形式的梯度结构试件相比, 并联形式的抗压强度较小, 且失效始发于界面处;在界面处插捣可提高抗压强度, 并改变其破坏形式, 然而插捣过多及插捣时间延滞时, 提高幅度会降低。最后基于试验数据拟合,建立了保护层厚度与抗压性能之间的表达式,并从机理上解释界面处适当插捣增强层间结合的有效性。     

SMA智能复合材料结构的弯曲振动方程

介绍了形状记忆合金智能复合材料结构的基本概念、结构类型、振动分析建模，并按照SMA纤维和基体的不同复合方式，详细总结了近年来关于形状记忆合金智能复合材料结构的弯曲振动方程．     

O'-Sialon-ZrO2-SiC复合材料的合成热力学分析及其制备

在分析、绘制Ｓｉ－Ｏ－Ｎ三维立体参数状态图基础上,采用纯原料合成了Ｏ’－Ｓｉａｌｏｎ－ＺｒＯ２－ＳｉＣ复合材料．对实验结果用ＸＲＤ、ＴＥＭ进行分析,验证热力学分析的可靠性．结果表明,Ｏ’－Ｓｉａ－ｌｏｎ－ＺｒＯ２－ＳｉＣ复合材料中,主晶相Ｏ’－Ｓｉａｌｏｎ彼此之间构成网络状结构,ＺｒＯ２和ＳｉＣ颗粒弥散于编织状结构的孔隙中,起强化作用     

多层机织物增强结构的设计

纺织结构在纤维增强复合材料的成型中占有越来越重要的地位．增强纤维加工成纺织结构可以方便复合材料的加工,提高复合材料的韧性和损伤容限,使材料不宜分层．本文主要介绍了各层经纬密度不同的多层机织物的设计方法     

原位聚合-热膨胀制备聚苯胺/膨胀石墨复合物及导电性能研究

以-100目(孔径0.254 mm)低温可膨胀石墨为石墨固体膨胀剂,采用原位聚合-热膨胀技术制备了聚苯胺/膨胀石墨复合物,并对聚苯胺/膨胀石墨复合物进行了形貌和结构表征.同时,对聚苯胺/膨胀石墨复合物的导电性能进行了研究.结果显示,聚苯胺/膨胀石墨复合物颗粒具有蠕虫状形貌和聚苯胺包覆在膨胀石墨上的结构,其膨胀体积为10.0 mL/g;实验结果表明,反应时间和反应温度对聚苯胺/膨胀石墨复合物的导电率有影响.     

Nb_2O_5-TiO_2复合氧化物结构与光催化性能研究

采用共沉淀法制备Nb2O5-TiO2复合氧化物,通过XRD、LRS和UV-vis DRS等方法考察Nb/Ti原子比和焙烧温度对Nb2O5-TiO2复合氧化物结构的影响,以水体中苯酚的降解为探针反应考察复合氧化物的光催化活性.结果表明,Nb2O5-TiO2复合氧化物结构与Nb/Ti原子比和制备温度有关.随着Nb5+进入TiO2晶格,在可见光区域形成一新的吸收带,该吸收带强度随Nb/Ti原子比和焙烧温度变化,当焙烧温度高于973 K时,可见光区域吸收带消失.低Nb/Ti原子比下,Nb5+对TiO2由锐钛矿相向金红石相转变具有抑制作用,而高的Nb/Ti原子比下Ti4+对Nb2O5晶相结构具有导向作用.复合物对水体中苯酚的光催化降解活性随着Nb/Ti原子比增加而降低.     

Microst ructure andflexural properties of carbon/ca rbon composite with in-situ grown carbon nanotube as secondary reinforcement

Carbon nanotubes (CNTs) were in-situ grown in carbon felts using ferric chloride as catalyst and natural gas as carbon precursor via thermal gradient chemical vapor infiltration (TGCVI). Subsequently, the carbon felts were densified to obtain CNT reinforced carbon/carbon (C/C) composites in the same furnace. Effects of CNTs on the microstructure and flexural property of C/C composites were investigated by polarized light microscopy, Raman spectroscopy, scanning electron microscopy and universal mechanical testing machine. The results of PLM observation and Raman analysis showed that CNTs have two-sided effects on the microstructure of pyrocarbon: the pyrocarbons in the region without CNTs show medium texture; while, in the region full of CNTs, the microstructure was low-textured or even isotropic though the TGCVD conditions would lead to the deposition of pure low texture pyrocarbons. Analysis based on stress-strain curves demonstrated that the flexural strength increased first and then decreased with the CNT content increasing. When the CNT content was 5.23 wt%, the flexural strength was maximum and had a nearly 35% improvement compared with pure C/C composite. Besides, after adding CNTs, the flexural modulus of the composites decreased and the ductility increased obviously, indicating CNTs can toughen C/C composites.