开孔泡沫铝导电性的研究

本文采用加压渗流方法制备开孔结构的泡沫铝,并通过调整工艺参数改变泡沫铝的孔径和相对密度.采用“直流四端电极”法测量了不同参数泡沫铝的电阻,研究开孔泡沫铝的导电性随其相对密度和孔径的变化规律.实验结果表明：随着相对密度的提高,开孔泡沫铝的电导率增大,且电导率随相对密度的改变呈指数关系变化;当相对密度参数基本相同时,随着泡沫铝孔径的减小,由于在制备过程中产生的结构缺陷增多,其电导性下降.     

添加造孔剂法制备开孔泡沫铝及其性能研究

以球形尿素颗粒为造孔剂,采用传统的粉末冶金工艺制备开孔泡沫铝并研究了其性能.结果表明,添加造孔剂法制备的泡沫铝可以任意控制孔隙率及孔径的大小,且孔结构良好,保持了造孔剂的形状;高的烧结温度使泡沫铝的压缩强度提高,但过高的温度将导致孔壁熔化.本试验制成的泡沫铝其压缩曲线和泡沫金属典型压缩曲线相似,且抗压强度和经典理论计算结果一致.     

泡沫铝合金显微组织和压缩力学性能的研究

采用Si、Mg及Cu元素进行合金化处理，制备了几种不同力学性能的开孔泡沫铝，并通过准静态压缩实验，研究合金化对泡沫铝压缩力学行为与吸能特征的影响。实验结果表明：采用Si、Mg及Cu元素合金化处理显著改变了泡沫铝的应力-应变行为与吸能特征，使泡沫铝的屈服强度提高，吸能性大幅度上升。另外，还研究了渗流法制备工艺对泡沫铝微观组织和性能的影响，结果显示由于渗流法制备过程特殊的凝固条件，使得泡沫铝的微观组织比相同成分的铸造铝合金的组织明显粗大。     

Compressive properties of aluminum foams by gas injection method

The compressive properties of aluminum foams by gas injection method are investigated under both quasi-static and dynamic compressive loads in this paper.The experimental results indicate that the defo...     

泡沫金属的尺寸效应和约束条件下的压缩性能

通过准静态单轴压缩和径向约束轴向压缩实验,研究了闭孔泡沫铝的尺寸效应,分析了试件尺寸(直径和高度)和密度对泡沫材料力学性能的影响。结果表明：单轴压缩时闭孔泡沫铝力学性能具有较为明显的尺寸效应,而径向约束轴向压缩时闭孔泡沫铝的尺寸效应不明显。两种加载情况下,密度都对闭孔泡沫铝的力学性能有着明显的影响。与单轴压缩相比,径向约束轴向压缩时闭孔泡沫铝的屈服应力和平台应力随密度的变化更为显著。     

闭孔泡沫铝的电磁屏蔽性能

采用粉末冶金发泡法制备闭孔泡沫铝,通过调整发泡剂含量、发泡温度、粘度、保温时间等手段,制得孔隙率可调、孔洞分布均匀的闭孔泡沫铝样品,并测试了不同孔隙率、孔径泡沫铝样品的电磁屏蔽性能.结果表明:在100～1000MHz内,泡沫铝的电磁屏蔽性能在60～90dB之间,且随着孔隙率、孔径的增加,泡沫铝的电磁屏蔽性能下降.     

泡沫铝及泡沫铝夹心板的制备方法

泡沫铝因其低密度、高比刚度、缓冲抗震等优良特性,越来越受到人们关注,逐渐将在汽车、航空等领域得到运用.本文介绍了泡沫铝及泡沫铝夹心板的几种主要制备工艺,并对其优缺点进行了阐述性分析.     

Novel strengthening method of closed-cell aluminum foams through surface treatment by resin

Aluminum foams are focused on as a lightweight structural material because of their excellent energy absorbing capacity. However, compressive strength of aluminum foams is much lower than that of dense aluminum. This is due to local buckling of the inhomogeneous cell structure. The authors carried out infiltration of open surface pores with polyester resin because buckling starts at the open surface pores. Compressive tests using commercial aluminum foams show significant increases in compressive strength and absorbed energy. Since the density of resin is not high, the specific compressive strength and specific absorbed energy are also increased.     

石膏型渗流法制备的开孔泡沫铝的压缩行为研究

本文采用可溶石膏型预制块,通过加压渗流的方法制备了泡沫纯铝、泡沫ZL101合金和泡沫ZL102合金,并通过准静态压缩实验研究了3种不同基体材料的泡沫铝的压缩行为及吸能性能.结果表明:通过石膏型渗流法制备的开孔泡沫铝合金的孔隙率可以达到85％～93.5％;泡沫铝基体材料的力学性能对泡沫铝压缩力学性能有重要影响;泡沫ZL1...     

泡沫铝的制备方法及应用进展

概述了泡沫铝的各种制备方法研究进展。根据制备过程中铝的状态可以将制备方法分为三类：固相法、液相法、电沉积法。液态铝能够通过直接注入气体、加入发泡剂或生成过饱和固一气共晶体的方法制得泡沫铝,间接方法包括熔模铸造法和渗流铸造法。如果往铝粉末压块中加入发泡剂,通过加热使发泡剂分解同样能得到泡沫铝。类似的方法还包括粉浆烧结法、散粉烧结法等。最后描述了泡沫铝的结构和优良性能,并对泡沫铝在各领域的应用进行了概括和展望。     

二元孔结构对开孔泡沫铝力学性能的影响

采用有限元模拟了不同孔径比和体积比的二元孔径结构对开孔泡沫铝力学性能的影响,并取得了相应参数.用渗流法制备出相应孔参数的泡沫铝,并对其进行压缩试验加以验证.模拟和实验结果均表明,当泡沫铝的孔结构由大、小孔按一定的尺寸比和体积比组成时,泡沫铝的强度和刚度显著提高,孔径尺寸比和体积比分别为0.40～0.45和0.07～0.12是最优的.     

采用反重力渗流法制备开孔泡沫铝(英文)

采用一套新颖的反重力渗流装置制备开孔泡沫铝。研究表明,采用反重力渗流法所制备的泡沫铝,表现出优良的力学性能且几乎没有渗流不足与渗流过度的缺陷;泡沫铝中的空隙度对其力学性能的影响很大,泡沫铝的屈服应力与平台应力均随孔隙度的降低而升高;升高预热温度与保压压强可有效降低泡沫铝中的空隙度。     

穿孔法改进泡沫铝的吸声性能

利用熔体发泡技术制备不同孔径和气孔率的泡沫铝,对不同气孔率的原始状态泡沫铝以及孔径为1.1 mm的穿孔泡沫铝的吸声性能进行研究。结果表明:未设置背腔时,原始状态泡沫铝的吸声性能不高,设置背腔后,由于泡沫铝中所含通透结构的作用,泡沫铝的吸声性能明显提高;穿孔泡沫铝的穿孔率在0.5%～1.0%范围,设置60～80 mm背腔时可使降噪系数超过0.42,比原始状态泡沫铝不设置背腔时的降噪系数高2倍左右;穿孔泡沫铝设置背腔后的吸声特性符合Helmholtz共振吸声的规律,但受到穿孔结构、泡沫铝原本存在的缺陷组成的通透结构和气泡孔在穿孔过程中被打开的小开口等因素的影响。     

合金化对泡沫铝压缩力学行为的影响

采用Si、Mg及Cu元素进行合金化处理，制备了几种不同力学性能的开孔泡沫铝，通过准静态压缩实验研究了合金化对泡沫铝压缩力学性能与吸能特征的影响。实验结果表明，Si、Mg及Cu元素合金化处理能显著改变泡沫铝的应力-应变行为与吸能特征，使泡沫铝的屈服强度提高，吸能性大幅度上升。     

Fabrication and compressive behavior of open-cell aluminum foams via infiltration casting using spherical CaCl2 space-holders

The infiltration casting fabrication process based on spherical CaCl₂ space-holders and the compressive behavior including the mechanical performance and energy absorption capacity of open-cell aluminum foams were investigated.Open-cell aluminum foams with different porosities in the range of 63.1%to 87.3%can be fabricated by adjusting compression ratios of CaCl₂ preforms prepared by precision hot-pressing.The compression tests show that a strain-hardening phenomenon always occurs especially for open-cell aluminum foam with low porosity,resulting in the inclining stress-strain curve in the plateau region.The energy absorption capacity of open-cell aluminum foam decreases with increasing porosity when compared at the same strain.However,when compared at a given stress,each foam can absorb the maximal energy among the five foams in a special stress range.Additionally,open-cell aluminum foam possesses the maximum energy absorption efficiency at its optimum operating stress.At this stress condition,the foam can absorb the highest energy compared with other foams at the same stress point.The optimum operating stress and the corresponding maximal energy absorption decrease with increasing the porosity.The optimum operating stress for energy absorption can also be determined similarly when taking into consideration of the lightweight extent of foams.     

Alternative starting materials for the production of aluminum foam by the powder metallurgical process

In the past it has already been proven that aluminum foam is a construction material appropriate for numerous applications. Especially in domains such as machine tool manufacturing and vehicle construction the combination of lightweight design and vibration damping is of great importance and aluminum foam can unfold its full potential. The widespread use of aluminum foam is still hampered by the high production costs resulting from the expensive production process and starting materials. The present work focuses on studies of alternative, cheaper starting materials. The results of current investigations follow the idea that aluminum chips may be successfully used as base material instead of atomized powders, without negatively influencing the macroscopic foam structure. It could also be proven that good foaming rates can be achieved with calcium carbonate as foaming agent for aluminum. That's why already in the near future, it will be possible to use recycling materials like aluminum chips in the series production of aluminum foams by the powder metallurgical process (PM process). Since sorted aluminum chips cost less than 1 €/kg, and calcium carbonate costs only a fraction of titanium hydride, a distinct price reduction for aluminum foam, and the lowering of the inhibition threshold for its application should be possible. Further studies are required to examine the static and dynamic properties of the foams and to compare them with conventional aluminum foams.     

吹气法制备泡沫铝的性能

基于吹气法制备A356基泡沫铝工艺,采用高速搅拌并分批连续加入粉末的方式,避免熔体中颗粒分布不均匀的问题;采用静置吹气头通入压缩空气发泡,通过设计和控制气路,制备出不同孔径、不同壁厚、稳定的泡沫铝.结果表明A356基泡沫铝是一种典型的塑性泡沫材料,泡孔呈十四面体形状,泡壁较薄,厚度小于150μm,可控的泡孔平均直径范围很宽,为10～25mm;泡沫铝在致密化阶段的塑性变形量可达70%以上;不作任何预处理的泡沫铝在高频率声波下的吸声系数可达0.9以上;在泡沫样品后设置0～70mm空腔,其在低频率声波下的吸声性能显著提高;所制备的泡沫铝具有较好的声学性能和力学性能.     

石膏型渗流制备泡沫铝填充圆管压缩行为研究

采用石膏型渗流制备开孔泡沫铝并填充到薄壁圆管,制成泡沫铝夹心管。通过准静态压缩试验研究了泡沫铝夹心管的压缩行为。结果表明：采用石膏型渗流法制备的泡沫铝孔隙率在85%左右,其压缩变形阶段可分为弹性段、塑性平台段和致密化段;空心圆管的压缩行为与其本身的结构参数有关;泡沫铝夹心管的力学性能与吸能能力比空心圆管和泡沫铝有了一定的提高,且石膏型渗流法所制泡沫铝夹心管质量较轻。     

爆炸荷载下泡沫铝复合材料数值模拟

随着武器科技的发展,冲击波对掩体内部人员的伤害已经不能忽视。研发了新型自制泡沫铝复合材料,并通过实验得出泡沫铝复合材料的应力-应变曲线,采用数值模拟,对泡沫铝复合材料在爆炸荷载下,其抗冲击缓冲特性进行研究。结果表明,冲击波在泡沫铝复合材料中传播时,显示出明显的衰减特性和良好的吸能性。泡沫铝复合材料可作为新型抗冲击缓冲材料和结构简化。     

原料配比对热爆式燃烧合成反应制备泡沫铝的影响

利用基于Al—Ti—B4c系热爆式燃烧合成反应制备了泡沫铝。调整原料摩尔配比,研究原料配比对燃烧合成反应的影响。通过对燃烧产物进行孔结构分析,发现Al、n及B。c原料摩尔配比为18：4：1及23：4：1时,孔隙率大且燃烧温度较高;对燃烧产物进行SEM分析,发现热爆式燃烧合成反应制备的泡沫铝中存在大量微孔。该体系热爆式燃烧合成反应制备泡沫铝的试验研究,为下一步利用该体系自蔓延式燃烧合成反应制备泡沫铝奠定了实验依据。