Preparation of big size open-cell aluminum foam board using infiltration casting

This paper presents an infiltration casting technique for manufacturing big size open-cell aluminum foam boards. The principle and key technologies of infiltration casting are also analyzed. Based on the previous practice of the small size aluminum foam production, the die for preparing big size aluminum foam boards is designed and manufactured. The experiments on aluminum boards of 300 mm × 300 mm × （20-75） mm, with the pore size ranging from 1.0 to 3.2 mm and average porosity of 60%, have been performed. The experimental results show that a reliable infiltration process depends critically on the pouring temperature of the molten AI-alloy, the preheated temperature of the mould and salt particles and vacuum. Current research explores the possibility of large-scale manufacturing and application of the aluminum foams.     

Effects of heat treatment on dynamic compressive properties and energy absorption characteristics of open-cell aluminum alloy foams

1 Introduction In the past few years, there has been a considerable increase in using metal foams for lightmass structural components and energy absorption parts for their wide plateau in the compressive stress-strain curve[1-3]. It has been shown that, e…     

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。     

Damping capacity and compressive characteristic in some aluminum foams

1　INTRODUCTIONMetallicfoams ,especiallyaluminumalloyfoamsaresuper lightmetalsexhibitingunique propertiessuchashighenergyabsorptionandhighdampingca pacity .So ,theyarebelievedtohavegreatpotentialforapplicationsinmanyaspects ,forexample ,theap plicationinenergyabsorptionandvibrationdamping .Therefore ,theirmechanicalpropertieshaveattractedaconsiderableattentioninrecentyears .Anumberofworksonthecompressivebehavioroffoamedalu minumanditsalloyhaverevealedthatthedeforma tionbehaviorofaluminumf…     

Effects of foaming parameters on microstructure and compressive properties of aluminum foams produced by powder metallurgy method

Semi open-cell aluminum foams having channels between individual cells were produced using low cost CaCO₃ foaming agent and applying the powder compact melting process. To this end, the aluminum and CaCO₃ powder mixtures were cold compacted into dense cylindrical precursors for foaming at specific temperatures under air atmosphere. The effects of several parameters including precursor compaction pressure, foaming agent content as well as temperature and time of the foaming process on the cell microstructure, linear expansion, relative density and compressive properties were investigated. A uniform distribution of cells with sizes less than 100 μm, which form semi open-cell structures with relative densities in the range of 55.4%–84.4%, was obtained. The elevation of compaction pressure between 127–318 MPa and blowing agent up to 15% (mass fraction) led to an increase in the linear expansion, compressive strength and densification strain. By varying the foaming temperature from 800 to 1000 °C, all of the investigated parameters increased except compressive strength and relative density. The results indicated the optimal foaming temperature and time as 900 °C and 10–25 min, respectively.     

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...     

Effect of TiH2 on preparation of closed-cell aluminum foam and its compressive behavior

The vesicant problem during the process of preparing closed-cell aluminum foam by molten body transitional foaming process was discussed and the effect of granularity and addition of TiH2 on porosity of closed-cell aluminum foam was investigated. The static compressive behavior of closed-cell aluminum foam and the influence of porosity on static compressive property of closed-cell aluminum foam were researched as well. The results show that with increasing granularity of TiH2, the porosity of closed-cell aluminum foam firstly increases and then decreases gradually, the granularity should be controlled in the range of 38-74μm which can result in higher porosity. The porosity of closed-cell aluminum foam increases with the increasing addition of TiH2, and the addition of TiH2 should be controlled fi＇om 1.5% to 2.5% which can result in homogeneous cell and moderate strength of closed-cell aluminum foam. The compressive process of closed-cell aluminum foam obviously displays linear elastic phase, plastic collapse phase, and densification phase, and the compressive strength grows with decreasing porosity.     

Sound absorption property of open-pore aluminum foams

This paper presents a study on sound absorption property of aluminum foam by evaluating its sound absorption coefficients using standing wave tube method. Experimental results showed that the average values of sound absorption coefficients (over the test frequency range) are all above 0.4, which indicate very good sound absorption property of the aluminum foams. The sound absorption coefficient is affected by frequency and pore structure, and reaches its maximum value at around 1 000 Hz. With the increase of porosity and decrease of cell diameter, the sound absorption coefficient values increase.     

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。     

泡沫铝的新型渗流法制备及其压缩性能

在热传计算的基础上,采用锌粒子为前驱体、铝熔体为渗流体,通过氩气渗流制备通孔泡沫铝;对泡沫铝的制备、压缩性能及锌残余量进行研究。结果表明:滑石粉隔热层厚度与渗流时间之间的关系为x2=7.35×10-8τ;优化的渗流工艺如下:渗流温度740℃、锌粒子预热温度220℃、锌粒子直径3 mm;平均孔径为3 mm的泡沫铝的屈服强度随孔隙率的增加而减小;孔隙率为63%和67%的泡沫铝的屈服强度都随孔径的增大而提高;泡沫铝孔隙率从60%提高到71%,锌残余量从11.3%降低到4.5%。     

Compressive deformation behavior and energy absorption characteristic of aluminum foam with elastic filler

An open-cell aluminum foam filled with silicate rubber (AFFSR) was fabricated by infiltration of the liquid silicate rubber into the open-cell aluminum foam. The experiments were carried out to investigate the compressive behavior and energy absorption characteristics of the material. It is found that the stress--strain response of the AFFSR exhibits five regions including two plateau regimes, which is quite different from the stress--strain curves of many unfilled metallic foams that usually exhibit three distinct regions. The plastic deformation of the AFFSR is prolonged because of the filled silicate rubber, compared with the aluminum foam without such a filler. The AFFSR also exhibits a higher energy capacity than the aluminum foam without filler. Additionally, for the prolonged plateau region in the stress--strain curve, the energy absorption efficiency of the AFFSR maintains a high level (above 0.6) over a wide strain range from 3% to 60%.     

涂料对消失模铝合金铸件孔隙率的影响

利用HST 2型消失模涂料高温性能测试仪研究了涂料组成、涂层厚度、透气性、温度等对聚苯乙烯热解产物通过消失模涂层的传输特性的影响。结果表明 :增加云母粉、珠光粉加入量及涂层厚度 ,涂层透气性下降 ,热解产物传输曲线的峰值上升 ,传输时间增长。探讨了模样热解产物通过涂层的传输行为对消失模铝铸件孔隙率的影响。研究发现 ,热解产物传输曲线峰值高、传输时间长 ,有利于减少铝件的孔隙率。当热解产物传输曲线的峰值及传输时间分别达到 0 .4 12kPa和 4 8.3s以上时 ,铝铸件的针孔率可达到一级。实验结果表明 ,自制的HW 1涂料的传输性能可与美国Ashland涂料的相当     

Microstructures of electromagnetic casting and direct chill casting LY12 aluminum alloys

1　INTRODUCTIONElectromagneticcasting (EMC)isatechnologydevelopedbythecombinationofmagnetohy drodynamics (MHD )andcastingengineering[13] .TheEMCtechnologydependsontheelectromagneticforcetopreventthemetalfromtouchingthemold .Dependingontheinteractionofeddycurrentsinducedinthemetalandthemagneticfieldoftheinductor ,theliquidmetalcolumniskeptstable[4 6 ] .Thecon tactlesscastingofEMCmayeliminatetheliquidationbuild upsandfeathercrystals ,relievethescalpingop erationbeforethehotrollprocess …     

A study on the effect of coating''s sorption capacity on the porosity in lost foam aluminum alloy casting

Effects of coating constituent, coating density, coating layer thickness and temperature on coating sorption capacity for polystyrene decomposition products have been studied systematically. It has been found that the effect of attapulgite clay on sorption capacity is the largest among coating constituents. The sorption capacity of the coating with 2 %attapulgite clay is elevated by 81%. The relationship between casting porosity and coating sorption capacity has been studied. It has been pointed out that higher coating sorption capacity for polystyrene decomposition products is helpful to decrease the casting porosity. Results also show that the sorption capacity of self- developed HW- 1 coating for polystyrene decomposition products is as good as that of Ashland coating from America.     

Effect of manganese on the ferrum phases of B319 aluminum alloy in lost foam casting

1 .Introduction Lost foam casting (LFC) process represents an important milestone in development of new casting technology, and is called as an innovative technology for tomorrow. At present, many studies on aluminum alloy associated with LFC process mainly concentrate on the casting process itself and its coating, thermal residual transformation,     

铝锭铸造机铝液流量控制器的研究与设计

针对铝锭铸造过程为非线性、时变过程,不容易建立精确的数学模型,基于模糊控制算法设计铝液流量控制器,给出模糊控制器结构、搭建方法及其控制流程图。实践验证,与普通PID控制比较,能快速进入恒液位稳定区,过程超调量很小,控制系统大大改善了响应速度、时滞等性能,为流量是采用浮标直接控制或浮标-杠杆控制铝锭铸造设备改造提供参考。     

高强Al-Ni系铸造铝合金的挤压铸造及强化机制

为了开发新的高强铸造铝合金材料,分别采用3种铸造工艺,砂型铸造、金属型铸造和挤压铸造,制备了一种以Al-Ni共晶体系为基础的AlZn6Ni4Mg2Cu铸造铝合金材料。研究了Ni元素、热处理和铸造工艺对其微观组织、力学性能的影响规律,揭示了其强化机制。结果表明:4%(质量分数)的Ni在该铝合金中形成了大量的共晶组织(α-Al+Al_3Ni),同时改善其力学性能和铸造性能,起到了共晶强化的作用;固溶和时效热处理导致Al_3Ni相的球化和MgZn_2相的时效析出,提高了该铝合金的强度;相比砂型铸造和金属型铸造,挤压铸造时该铝合金的晶粒和Al3Ni相最细小,力学性能最佳,抗拉强度为586 MPa,断后伸长率为3.5%。由此得出:AlZn6Ni4Mg2Cu铸造铝合金的强化机制为η(MgZn_2)相的时效强化和Al_3Ni相的弥散强化,挤压铸造加T6热处理后,该铝合金的力学性能达到最佳值。     

Mechanical properties and energy absorption properties of aluminum foam-filled square tubes

Longitudinal and transverse mechanical properties and energy absorption properties of foam-filled square tubes under quasi-static loading conditions were studied. The foam-filled thin-walled square tube was fabricated with aluminum tube as its shell and closed-cell Al-Mg alloy foam as its core. The results indicated that the plateau region of the load-displacement curve exhibited a marked fluctuant serration which was clearly related to the formation of folds. The longitudinal deforming mode of foam-filled square tube was the same as that of the empty tube, but the fold number of foam-filled square tube was more than that of the empty tube. The longitudinal compression load and energy absorption value of foam-filled square tube were higher than the sum of that of aluminum foam (alone) and empty tube (alone) due to the interaction between tube and filler. In transverse direction, the compression load and energy absorption ability of foam-filled square tubes were significantly lower than those in longitudinal direction.     

原铝铸造优化配铝算法分析与软件开发

对铝电解铸造配料进行了详细分析，研究了配料算法，提出了优化配铝方案．并对此方案的软件实现作了简要介绍。     

Three-point bending behavior of surface composite Al2O3/Ni on bronze substrate produced by vacuum infiltration casting

Al₂O₃/Ni surface infiltrated composite layer is a protective surface layer. It was fabricated on bronze substrate through vacuum infiltration casting technique using Ni-based powder and Al₂O₃ powder with different content as raw materials. With an appropriate choice of processing condition, a compact infiltrated layer is achievable as conformed through SEM observation. The infiltrated layer consists of surface composite layer and transition layer, and the thickness of transition layer decreases with increasing content of Al₂O₃. Metallurgical fusion formed at the interface between the surface infiltrated composite layer and substrate. Three-point bending tests were carried to investigate the mechanical and bonding properties of the surface infiltrated layer. It was found that load-holding circumstance appeared on the load–displacement curve of specimen with surface infiltrated layer comparing with that of the substrate. The peak load reduces with increasing content of Al₂O₃. The fracture extended to the substrate for specimen with Al₂O₃ content less than 20 (wt%). The fracture direction of specimen more than 30% with Al₂O₃ (wt%) is along with the interface of the surface composite and the substrate because of the thinner transition layer.