复合泡沫材料及其应用

随着人们对深海技术的不断探索,迫切需要一种轻质、高抗静水压材料在深海中为各类潜器提供稳定、可靠的浮力,高强度空心微球填料的出现将这变成了现实。由空心微球填料和连续相基体构成的材料被称为复合泡沫材料,它不使用发泡剂,密度和强度决定于所使用的空心填料。根据复合泡沫材料具有的特征,分别从海洋工程、航空航天等领域介绍了它的主要应用方向。其中详细介绍了作为水下装备固体浮力材料的发展历程以及国内外现状。     

复合树脂/空心微珠耐高温浮力材料的制备及性能

本工作针对环氧树脂基固体浮力材料热稳定性差的问题,提出选用耐温性能优良的酚醛树脂和甲基硅树脂与环氧树脂形成耐高温复合基体,从而提高整体浮力材料的耐温特性.通过密度测试和准静态单轴压缩实验,研究了不同温度下树脂含量对固体浮力材料压缩强度、体积密度、弹性模量、比强度的影响,并测试了浮力材料的吸水性能和耐高温性能.研究结果表明:酚醛树脂的加入可以提升浮力材料的耐高温性能.环氧树脂中环氧基通过开环反应与硅树脂中硅氧烷发生共聚反应,形成复合树脂基体,从而增强基体的耐高温性能.硅树脂含量为40％的试样性能最好,200℃热处理后压缩强度、体积密度、弹性模量、比强度分别为39 MPa、0.652 g/cm3、4.02 GPa、59.82 MPa/(g/cm3).300℃热处理后浮力材料抗压强度仍能维持在30 MPa以上.不同温度热处理后浮力材料的吸水率不超过0.5％.     

树脂基深水浮力材料压缩性能研究

为探究空心微珠填充量对树脂基深水浮力材料压缩性能的影响以及材料压缩破坏机理,基于Mori-Tanaka及Turesanyi方法对空心微珠填充环氧树脂基深水浮力材料的有效弹性模量及压缩强度进行了理论预测.制备了空心微珠填充环氧树脂基深水浮力材料,对不同空心微珠填充比的材料体系进行了单轴压缩试验,并通过扫描电镜观察了材料断裂面微观形貌.结果表明:随着空心微珠填充量增加,材料体系耐压强度降低,模量上升,且实验结果与理论预测吻合情况较好;空心微珠破损是深水浮力材料破坏的根本因素.     

超低密度全海深固体浮力材料的制备及性能研究

用双酚A型环氧树脂、环氧稀释剂、酸酐固化剂及改性空心玻璃微珠，采用真空复合浇注工艺，制备出了超低密度、高强度的全海深固体浮力材料。通过密度测试、耐全方位静水压测试和力学性能测试等手段对浮力材料进行了表征。结果表明：制备的全海深浮力材料密度为0.638g/cm³,116MPa、24h全方位静水压下的吸水率为0.125%,单轴压缩强度为105.2MPa,剪切强度为35.7MPa,拉伸强度为33.4MPa,破坏强度141MPa,综合性能优异，已成功应用到上海交通大学研制的全海深无人潜水器上。     

装甲车体内饰用三维深角联机织复合材料力学性能研究

以2400tex的玻璃纤维为原料,在三维织机(SGA598型)上,采用深角联结构制备了一种三维五层深角联机织物。将环氧树脂E51和固化剂聚醚胺WHR-H023以质量比3∶1的比例组成树脂体系,并将配制好的树脂体系与深角联机织物以质量比为1∶1的比例进行手糊复合成型。借助万能材料试验机对材料的拉伸及弯曲性能进行测试;并通过扫描电子显微镜观察材料的断裂界面,以研究材料的破坏机理。结果表明:复合材料具有优良的力学性能,且材料的纬向力学性能明显好于经向;材料的破坏模式主要为脆性破坏,具体表现为树脂基体的碎裂,以及纤维的抽拔及断裂。     

深海高强浮力材料的研究现状

深海开发迫切需要高强轻质浮力材料。概述了深海浮力材料的国内外研究现状、固体浮力材料的类别及应用;结合新型高强浮力材料的开发,具体介绍了以环氧树脂为基体、填充空心玻璃微珠的轻质浮力材料的研究历程、制备工艺及常见理化性能的测试方法,分析了今后重点研究的方向。     

环氧树脂复合泡沫材料的压缩力学性能

对空心玻璃微珠填充环氧树脂复合泡沫材料进行了准静态压缩实验, 研究了材料的宏观压缩力学性能, 并提出了弹性模量和屈服强度的预测公式。此外, 对压缩试件的断口进行了宏、细观观察, 研究了材料的压缩破坏机理。结果表明, 复合泡沫材料在压缩过程中, 具有普通泡沫材料的应力-应变曲线的典型特征, 在应变为2 %左右时材料发生屈服, 在应变大于30 %后发生破坏。此外, 材料的杨氏模量和强度均随密度的减小而下降, 预测公式给出的结果与实验值基本一致。压缩试件断口的宏、细观观察表明, 复合泡沫材料主要的破坏形式为剪切引起的弹塑性破坏。      

自然老化对空心玻璃微珠/环氧树脂及泡沫铝-空心玻璃微珠/环氧树脂力学性能的影响

制备了空心玻璃微珠(HGM)/环氧树脂复合泡沫材料、泡沫铝-HGM/环氧树脂两类环氧树脂基复合材料,测量了其在北方室内环境中自然老化前后的密度.通过一系列准静态压缩实验研究了HGM/环氧树脂和泡沫铝-HGM/环氧树脂两类复合材料的有效弹性模量、屈服极限等力学性能,分析了其破坏形貌与材料结构的关系及力学性能改变的原因.研究表明:环氧树脂老化后屈服极限有所降低,但HGM/环氧树脂复合泡沫材料的力学性能随着HGM填充量的增加呈先增加后降低的趋势.泡沫铝/环氧树脂复合材料老化后的力学性能出现明显降低,但添加HGM体积比高于20％的泡沫铝-HGM/环氧树脂复合材料的力学性能则有所增加.     

自然老化对空心玻璃微珠/环氧树脂及泡沫铝-空心玻璃微珠/环氧树脂力学性能的影响

制备了空心玻璃微珠(HGM)/环氧树脂复合泡沫材料、泡沫铝-HGM/环氧树脂两类环氧树脂基复合材料, 测量了其在北方室内环境中自然老化前后的密度。通过一系列准静态压缩实验研究了HGM/环氧树脂和泡沫铝-HGM/环氧树脂两类复合材料的有效弹性模量、屈服极限等力学性能, 分析了其破坏形貌与材料结构的关系及力学性能改变的原因。研究表明: 环氧树脂老化后屈服极限有所降低, 但HGM/环氧树脂复合泡沫材料的力学性能随着HGM填充量的增加呈先增加后降低的趋势。泡沫铝/环氧树脂复合材料老化后的力学性能出现明显降低, 但添加HGM体积比高于20%的泡沫铝-HGM/环氧树脂复合材料的力学性能则有所增加。     

织物—树脂复合材料层压板的准静态侵彻机理

本文利用MTS得到芳纶和高强维纶织物复合材料层压板受压头侵彻体穿孔的准静态侵彻曲线，比较和分析了不同类型纤维集合体与热固体树脂和热塑性树脂复合材料的破坏模式，并考察了芳纶织物复合材料层压板侵彻的逐步破坏过程，揭示了复合支压板的准静态侵彻机理。     

空心微珠/金属基复合泡沫制备方法与吸能性能的研究进展

金属基复合泡沫是由空心微珠和金属基体复合而成的一种新型结构功能多孔复合材料。它具有许多优异的性能,如轻质、高比强度、高比刚度、高吸能能力、隔热、吸声隔音及电磁屏蔽等,高吸能能力是金属基复合泡沫的突出特点,在防撞、减振、缓冲及防爆抗振的汽车、航空航天、军事装备及船舶等领域具有广阔的应用前景。本文对金属基复合泡沫的基体材料、空心微珠填充材料、影响金属基复合泡沫压缩吸能性能的因素及压缩吸能机制进行了概述,重点报道了金属基复合泡沫常用的制备工艺及近年来铝基、镁基、锌基及钢基复合泡沫吸能性能的研究进展,分析了当前研究中存在的一些问题,并对金属基复合泡沫的应用现状作了阐述,最后展望了金属基复合泡沫的研究发展趋势。      

Quasi-static and high strain rate response of aluminum matrix syntactic foams under compression

Aluminum alloy matrix syntactic foams were produced by inert gas pressure infiltration. Four different alloys and ceramic hollow spheres were applied as matrix and filler material, respectively. The effects of the chemical composition of the matrix and the different heat-treatments are reported at different strain-rates and in compressive loadings. The higher strain rates were performed in a Split-Hopkinson pressure bar system. The results show that, the characteristic properties of the materials strongly depends on the chemical composition of the matrix and its heat-treatment condition. The compressive strength of the investigated foams showed a limited sensitivity to the strain rate, its effect was more pronounced in the case of the structural stiffness and fracture strain. The failure modes of the foams have explicit differences showing barreling and shearing in the case of quasi-static and high strain rate compression respectively.     

Characterisation of aluminium matrix syntactic foams under drop weight impact

It is a challenging task to develop a lightweight, and at the same time, strong material with high energy absorption for applications in military vehicles, which are able to withstand impact and blast with minimum injury to occupants. This paper presents a study on aluminium matrix syntactic foams as a possible core material for a protection system on military vehicles. Experimental work was first carried out which covers sample preparation through pressure infiltration and impact tests on aluminium matrix syntactic foams manufactured. Numerical models were then developed using commercial finite element code ABAQUS/Explicit to simulate the dynamic behaviour of the foam. The effect of strain rate on their compressive behaviour was investigated as these properties are vital in terms of the applications of these materials. Characterisation of the foam behaviour under low velocity impact loading and an identification of the underlying failure mechanisms were also carried out to evaluate the effective mechanical performance. It was found that samples subjected to drop weight impact offered a 20–30% higher plateau stresses than those of the samples subjected to quasi-static compression loading. The degree of correlation between the numerical simulations and the experimental results has been shown to be reasonably good.     

碳纳米管增强开孔铝基复合泡沫的疲劳性能

采用原位化学气相沉积、短时球磨和填加造孔剂法相结合的工艺制备了碳纳米管(CNTs)/Al复合泡沫,研究了其在压缩-压缩循环载荷下的力学性能及失效机制。结果表明,CNTs/Al复合泡沫的应变-循环次数曲线经历线弹性、应变硬化及应变快速增长三个阶段。不同于泡沫铝的逐层坍塌变形失效模式,CNTs/Al复合泡沫疲劳失效的主要原因是大量剪切变形带的形成,试样出现快速的塑性变形。此外,CNTs含量为2.5wt%、孔隙率为60%的复合泡沫试样的疲劳强度相比于泡沫铝提高了92%。CNTs的均匀分布及增强相与基体材料之间良好的界面结合性保证了疲劳载荷能够以剪切力的形式从基体传递到CNTs上,使其充分发挥自身高强度、高韧性的特点,进而提高了疲劳性能。      

原位合成钛基复合材料的研究现状与展望

原位合成钛基复合材料以其高比强度、高比模量引起了人们的广泛关注,尤其是如何提高其高温性能更成为近年研究的热点.综述了原位合成钛基复合材料的主要制备方法、增强体与钛基体的选择、反应体系以及复合材料的显微组织与力学性能,提出了当前存在的主要问题和今后的发展方向.     

Mechanical behavior of pure Al and Al–Mg syntactic foam composites containing glass cenospheres

Glass cenospheres were used as space holders for making aluminum matrix syntactic foams by pressure infiltration technique. The mechanical properties and failure behavior of cenospheres/Al syntactic foams with pure Al and Al–Mg alloys were investigated in the present work. The failure behavior of cenospheres in two syntactic foams was similar. However, the mechanical behavior of these two syntactic foams was different. Under compression process, the cenospheres/pure Al showed discontinuous shear band and drum shape, while cenospheres/Al–Mg exhibited continuous shear band and was divided by main shear zone. At the tensile state, the cenospheres in pure Al matrix syntactic foam debonded from the matrix, while the cenospheres in Al–Mg matrix syntactic foam was well-bonded and appeared to lamellar tearing. It is suggested that the difference of mechanical deformation behavior could be attributed to the matrix ductility and the forming of interfacial reaction product MgAl₂O₄ coatings.     

Review of recent studies in magnesium matrix composites

In this paper, recent progress in magnesium matrix composite technologies is reviewed. The conventional and new processes for the fabrication of magnesium matrix composites are summarized. The composite microstructure is subsequently discussed with respect to grain refinement, reinforcement distribution, and interfacial characteristics. The mechanical properties of the magnesium matrix composites are also reported.     

On the Mechanical Properties of Aluminum Matrix Syntactic Foams

Metal matrix syntactic foams (MMSFs, often referred as composite metal foams (CMFs)) are lightweight materials with high specific strength. MMSFs are on the borderline between metal matrix composites and metal foams. On one hand MMSFs are composites, because they are filled by hollow particles and the particles may add strength to the material. On the other hand, they are foams, because the hollow particles ensure porosity to the material. Among metallic foams, MMSFs exhibit outstanding specific mechanical properties due to the hollow inclusions that are typically made from ceramics or high strength alloys, therefore they can be applied as structural materials. The goal of this paper is to summarize the available data on the mechanical properties of MMSFs with aluminum matrix in order to give a strong support to the design engineers. Since the foams are most frequently loaded in compression, the main part of this paper is organized around the available standard related to the compressive properties of porous materials and metallic foams. The quasi‐static results are complemented by properties measured at higher strain rates. Besides this, some insight into the basic fatigue properties as well as into the toughness of MMSFs is also provided.

     

球磨对碳纳米管增强泡沫铝基复合材料压缩与吸能性能的影响

因碳纳米管（CNTs）具有优异的性能,被认为是金属基复合材料理想的增强体,因此如何制备得到CNTs增强体均匀分散的金属基复合材料一直是本领域的研究热点。本文通过原位化学气相沉积（CVD）、短时球磨和填加造孔剂的工艺成功制备了CNTs增强的泡沫铝基复合材料,着重研究了球磨过程对复合泡沫铝的微观形貌、压缩性能和吸能性能的影响规律。结果表明,随着球磨时间的延长,CNTs的分散性提高并逐步嵌入铝基体中,使复合泡沫铝的组织均匀性得到改善。相对于未球磨的含CNTs 3.0wt%的复合泡沫材料,当球磨时间增加至90 min时,复合泡沫铝的孔壁硬度、屈服强度和吸能能力分别提高了67%、126%和343%。     

高应变率加载下复合泡沫塑料的吸能特性及失效机理研究

通过SHPB冲击实验装置对空心玻璃微球填充聚氨酯复合泡沫塑料进行了动态压缩实验,获得了不同密度复合泡沫塑料在高应变率加载条件下的应力-应变曲线,研究了材料的动态力学性能。基于所获得的应力-应变曲线,进一步分析和讨论了复合泡沫塑料的能量吸收特性,发现材料最佳吸能点的包络线是同一直线。此外,通过动态变形试件的扫描电镜分析,还研究了这类新材料的动态失效问题。