采用新型发泡剂制备泡沫铝

研究了一种在泡沫铝制备过程中可替代TiH2及ZrH2类发泡剂的新型发泡粉末的热分解行为,探讨该新型发泡剂加入量及发泡温度等因素对泡沫铝孔隙率的影响。研究表明:该新型发泡材料具有分解温度范围宽及分解过程缓慢的特点。当采用该发泡剂时,泡沫铝制备过程无需额外加入金属Ca类增粘剂;随发泡温度的升高,泡沫铝的孔隙率先升高后下降;随发泡剂量的增多,发泡体中的无泡层逐渐减少,当发泡剂的加入量在1.40%以上时,发泡体中的无泡层消失;在发泡温度740℃、发泡剂加入量1.40%~2.20%、搅拌时间3min、保温发泡时间5min的条件下,可以制备出孔径2~5mm,孔隙率60%~80%,孔隙基本均匀且无实心体的泡沫铝。     

半固态法泡沫铝材料制备工艺研究

采用半固态法制备泡沫铝,并对制备工艺进行了初步探索。研究了熔体浇注温度、发泡剂TiH_2添加量对Al-Si合金熔体发泡孔隙率和平均孔径的影响。研究表明,利用Al-Si合金在半固态区的自增粘作用,可以得到孔隙率为20%~50%、孔径为2~4 mm的泡沫铝;浇注温度在650~670℃时,随浇注温度的升高,Al-Si合金泡沫铝试样孔隙率增加,更高的浇注温度使孔隙率减少;发泡剂TiH_2添加量在1%~3%时,随发泡剂添加量的增加,孔隙率和孔径均增加,发泡剂过多反而使孔隙率和孔径减小。浇注温度为670℃、TiH_2添加量3%时,Al-Si熔体发泡效果最优,孔隙率可达48%。     

大孔径高孔隙率泡沫铝的制备

采用熔体发泡工艺,用纯铝作原料,氢化钛为发泡剂,金属钙粉为增粘剂,制备出孔结构均匀,孔隙率大于80%,孔径大于4.2mm的闭孔泡沫铝,整个工艺过程控制平稳。探讨了发泡温度、金属钙粉和氢化钛加入量及搅拌时间对泡沫铝结构的影响。结果表明,增粘剂钙粉的加入量为1.5%～2.0%,增粘温度850～860℃,搅拌时间为2.0～2.5 min,发泡剂TiH_2的加入量为1.5%～2.0%,发泡温度为680～690℃,发泡搅拌速度和时间分别为860 rpm和2.0～2.5 min,保温时间4.5～6.0 min时为最佳工艺。     

碳酸镁发泡剂制备泡沫铝的研究

选用ZL102合金为主体原料,钙为增粘剂,碳酸镁为发泡剂,对用熔体直接发泡法制备泡沫铝进行了研究.结果表明,采用碳酸镁作为发泡剂,钙作为增粘剂,可以制备出低密度、高孔隙率的泡沫铝;随着碳酸镁或钙加入量的增加,泡沫铝的密度逐渐减小;但当碳酸镁或钙加入量超过1%时,泡沫铝的密度有所增加;泡沫铝平均孔隙率的变化规律与密度的变化规律相反.     

泡沫铝芯填充合金的制造工艺技术研究

介绍了熔体发泡法制备泡沫铝的工艺方法,分析了增粘剂加入量、TiH2加入量和保温发泡时间对泡沫孔结构的影响.得出了制备具有均匀孔结构泡沫铝的工艺参数.     

Ca增粘熔体发泡法制备闭孔泡沫铝的研究

研究了熔体发泡法制备闭孔泡沫铝过程中,金属钙对熔体的增粘机理以及不同钙加入量对闭孔泡沫铝孔隙率的影响。发现加入金属Ca并搅拌均匀后,主要生成金属间化合物CaAl4和CaAl2,在熔体中弥散存在,且CaAl4熔点(697℃)高于制备泡沫铝的试验温度(680℃),处于半熔化状态,因此增加了铝熔体粘度。试验近一步证实,纯铝中金属钙的加入量对闭孔泡沫铝孔隙率有很大影响,当加入量为2.5%制备所得的泡沫铝的孔隙率最高。     

氢化锆熔体发泡法制备小孔径泡沫铝

以ZrH_2为发泡剂,采用熔体发泡法制备铝基小孔径泡沫铝,分析其制备过程及影响孔结构的因素;优化实验室制备泡沫铝的工艺条件;借助图形分析方法表征泡沫铝的孔径分布,并与TiH_2制备的泡沫铝进行了对比;采用改进座滴装置研究铝合金与氢化物的润湿行为.结果表明:ZrH_2较适合制备小孔径泡沫铝;优化工艺条件为:Al 650 g,增粘剂Ca 的加入量2.5%,发泡剂ZrH_2的加入量1.0%,发泡温度680 ℃,搅拌时间1.5 min,保温时间2.5 min;制备的泡沫铝孔径均匀,平均孔径小于1.5 mm;ZrH_2在铝合金中的润湿特点是导致泡沫铝孔径较小的主要原因.     

ZL101泡沫铝合金制备技术研究

以ZL101为基体材料,利用熔体发泡法制备泡沫铝合金,通过控制增粘温度、增粘物质和发泡物质的加入方式、发泡温度等关键参数获得稳定的制备工艺参数.实验结果表明,在660℃增粘效果要好于在700℃以上增粘;TiH2采用铝箔包裹方式加入可以有效减少加入过程的烧损量;加入发泡剂过程中使用带有下旋压力的双层折叶搅拌浆有利于将TiH2快速分散均匀和减小泡沫铝底部实心层;发泡温度为645℃时可以获得孔径较均匀的泡沫铝合金.     

SiO2包覆CaCO3在无保护气氛下制备闭孔泡沫镁（英文）

在熔体发泡法工艺中,发泡剂的分解速度和浸润性直接影响泡沫金属的孔结构和孔隙率。为减缓泡沫镁发泡剂CaCO3的发泡速度并提高与镁熔体的浸润性,采用非均匀形核法,以硅酸钠为原料,盐酸为酸化剂,在CaCO3表面包覆SiO2钝化膜。采用TGA-DTA、XRD、SEM等方法对包覆后CaCO3的热稳定性和包覆层的微观结构进行分析。结果表明:包覆后的CaCO3分解温度提高;包覆层中的SiO2为无定形态;在CaCO3颗粒表面形成网络状结构。对比实验表明:包覆后的CaCO3发泡速度平稳。同时,采用合金化阻燃工艺在无气体保护条件下制备出较大尺寸的泡沫镁试样,并且试样孔径细小,孔结构均匀,孔隙率在60%-70%。     

粉末冶金泡沫铝制备工艺及相关参数研究

本文在采用粉末冶金发泡法制备泡沫铝的基础上,研究相关参数对制备泡沫铝的影响。通过分析可知,Ti H2的分解峰值温度为640℃,与铝的熔点十分接近,是一种制备泡沫铝更好的发泡剂;纯铝发泡合适温度为700℃到750℃之间,发泡时间宜选择在900s左右;铝粉表面氧化膜对泡沫铝产生影响,氧化膜含量在9.8%左右时,孔隙率达到最大。     

粉末冶金法制备SiC_p/2024Al泡沫复合材料的表征(英文)

为了丰富泡沫材料制备工艺、推动其快速发展与广泛应用,以CaCO3为发泡剂采用粉末冶金法制备SiCp/2024Al泡沫复合材料。采用SEM和Magiscan-2A图像分析仪研究了CaCO3发泡剂和SiC颗粒的含量对发泡行为的影响,并且通过Gleeble 1500热模拟机分析了SiC颗粒的含量对压缩性能的影响。结果表明:随着发泡剂的增多,孔隙率和孔径先增加后减小。随着增强体含量的增加,孔隙率和孔径都减小。压缩曲线揭示加入增强体可以改善压缩屈服强度和吸能能力。SiCp/2024Al泡沫复合材料显示为脆性泡沫材料。     

以ZrH_2为发泡剂的泡沫铝制备和表征

使用氢化锆为发泡剂,通过熔体发泡法制备泡沫铝并研究其影响因素。制备工艺为：添加0.6%-1.4%的发泡剂,1.5%-3.0%Ca（质量分数）作为增粘剂,发泡温度933-1013K,搅拌时间为0.5-2.5min和保温时间为1.5-4.0min。利用XRD和SEM对泡沫铝样品进行表征,测试其力学性能。结果表明,在合适的工艺参数下能制备出孔径均匀的泡沫铝,采用氢化锆为发泡剂可以制备出平均孔径为1mm左右的泡沫铝。金属间化合物和Al2O3的存在影响熔体的粘度。泡沫铝的力学性能经历线弹性区、平台区和致密化区并表现出较高的能量吸收效率。     

Effect of Semi-Solid Isothermal Heat Treatment on Microstructure of ZL104 Aluminum Alloy

The feasibility of fabricating ZL104 aluminum alloy with non-dendritic microstructure by semi-solid isothermal heat treatment process and the effects of holding temperature and time on the semi-solid isothermal heat-treated microstructure of the alloy, are investigated. The research results indicate that it is possible to produce ZL104 alloy with non-dendritic microstructure by a suitable semi-solid isothermal heat treatment. After treated at 580 ℃ for 120 min, the ZL104 alloy can obtain a non-dendritic mic...     

Development of Iron-based Closed-Cell Foams by Powder Forging and Rolling

In the present investigation, an attempt has been made to develop in situ sandwich Fe-based foams using powder forging and rolling. Several metal carbonates are first studied by thermo gravimetric analysis to find out their suitability to be used as foaming agent for iron-based foams. Barium carbonate is found to be the most promising foaming agent among other suitable options studied such as SrCO₃, CaCO₃, MgCO₃, etc. The effects of process parameters such as precursor composition, sintering temperature, foaming temperature and time, and content of foaming agent have been studied. The microstructural characteristics of the sintered precursor have been studied by means of optical and scanning electron microscopy. It was found that a good pore structure can be obtained using 2-3% C in Fe and 3% BaCO₃ as foaming agent and by foaming at around 1350 °C for 3-6 min.     

应变率和相对密度对泡沫SiCp/ZL104压缩性能的影响

对采用熔体发泡法制备的泡沫5%(体积分数,下同)SiCp/ZL104复合材料进行了准静态和动态压缩性能的测试和分析.结果表明:无论是动态下压缩还是准静态下压缩,泡沫5%SiCp/ZL104复合材料的应力-应变曲线都呈现出典型的3个阶段:线弹性段、平台段和致密段;屈服应力对应变率很敏感,使得应变率增加时,屈服应力增加,且有应变硬化现象发生;随着相对密度的增大,泡沫5%SiCp/ZL104复合材料的动态屈服应力和流动应力与准静态载荷相比显著增加.     

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.     

Preparation and characterization of SiCp/2024Al composite foams by powder metallurgy

SiC_p/2024Al composite foams were manufactured by powder metallurgical methods using foaming agent CaCO₃ in order to enrich the foam fabrication process and promote its development and extensive application. The effects of CaCO₃ and SiC volume fractions on the foaming behaviours were investigated by means of SEM and Magiscan-2A image analysis technique. The influence of SiC content on the compressive behaviour was analyzed using Gleeble 1500 thermal simulation testing machine. The experimental results show that with increasing the foaming agent, the porosity and pore dimension increase first and decrease later. With increasing the reinforcement content, the porosity and pore dimension decrease. The compressive curves reveal that the introduction of SiC particles can improve compressive yield strength and energy absorption capacity. Meanwhile, it is found that SiC_p/2024Al composite foams are the brittle foam materials.     

Solidification of metal foams

Expansion and contraction phenomena during solidification of liquid metal foams were studied. Such foams were processed by mixing metal powders with TiH₂ powder and compacting the resulting blends, after which the compacted powders were melted. The subsequent foaming process was monitored in situ by X-ray radioscopy. An intermediate expansion stage during solidification was observed. This solidification expansion (SE) could be linked to phase transformations in the alloy. SE was found to depend mainly on the time spent at the foaming temperature before cooling (holding time), the cooling rate and the alloy composition. The interplay between gas shrinkage, solidification shrinkage, gas production by the blowing agent and gas losses due to out-diffusion was identified as the main reason for SE. While the blowing agent had a major influence on SE, gas dissolved in the metal also played a role, since some SE was observed in foams blown without TiH₂ by pure pressure manipulation.     

SiC颗粒和芯部材料厚度对泡沫SiCp/ZL104层合板弯曲性能的影响

用泡沫SiCp/ZL104复合材料作为芯部材料制备了泡沫SiCp/ZL104层合板,测试和分析了该类层合板的三点弯曲性能。结果发现,在相对密度相同的情况下,泡沫5%SiCp/ZL104(体积分数,下同)层合板的弯曲刚度随SiC粒度的减小以及芯部材料厚度的增加而增大;由于环氧树脂的填充,使得层合板刚度P/δ的实验值比计算值略高;SiC颗粒体积分数的增加致使泡沫SiCp/ZL104层合板的抗弯曲刚度增大;弯曲过程中的主要破坏模式是芯部剪切和局部凹陷,但随着芯部材料厚度的增加,层合板的破坏方式由芯部剪切向表面屈服和芯部凹陷过渡。     

THE STRUCTURE CONTROL OF ALUMINUM FOAMS PRODUCED BY POWDER COMPACTED FOAMING PROCESS

A new technique, powder compact foaming process for the production of aluminum foams has been studied in this article. According to this method, the aluminum powder is mixed with a powder foaming agent (Till2). Subsequent to mixing, the powder blend is hot compacted to obtain a dense semi-finished product. Upon heating to temperatures within the range of the melting point, the foaming agent decomposes to evolve gas and the semi-finished product expands into a porous cellular aluminum. Foaming process is the key in this method. Based on experiments, the foaming characteristics were mainly analyzed and discussed. Experiments show that the aluminum-foam with closed pores and a uniform cell structure of high porosity can be obtained using this method by adjusting the foaming parameters: the content of foaming agent and foaming temperature.