上压渗流铸造法制备泡沫铝

采用上压渗流铸造法,利用盐粒和陶瓷网作为预制体,制备了开孔泡沫铝和闭孔泡沫铝,并对其孔隙率、透气性和显微硬度等性能进行了测试、分析．研究结果表明,上压渗流铸造法可制备出孔隙率高、透气性好的泡沫铝,且开孔泡沫铝的孔隙率都大于闭孔泡沫铝,而闭孔泡沫铝的硬度高于开孔泡沫铝．通过分析制备工艺参数发现,模具和预制体的预热温度在400～500℃、浇注温度在750—780℃、充型压力不超过0．5MPa时,可制备出性能良好、结构完整的泡沫铝．     

粉体致密化法(PCF)制备泡沫铁的研究

采用粉末致密化发泡(PCF)工艺制备泡沫铁,研究了各工艺参数对泡沫铁制备及其孔隙率的影响规律,得出了实验条件下的优化工艺参数配置,对制备过程及影响孔隙率的因素进行了分析,获得了泡沫铁的优化制备工艺及各工艺参数对孔隙率的影响规律,对泡沫铁的研究与开发具有显著意义.     

大孔径高比表面积介孔硅泡沫的制备和表征

以P123作为模板剂,正硅酸乙酯为硅源,苯为微乳剂,采用溶胶-凝胶水热合成法制备了大孔径高比表面积介孔硅泡沫材料,采用小角X-射线衍射、透射电镜、扫描电镜以及N2物理吸附等表征手段进行表征,考察了苯的加入量对介孔硅泡沫孔结构的影响。结果表明,苯的引入可以使有序介孔硅的孔结构从SBA-15的二维六方形向介孔硅泡沫的三维泡沫状结构转变,加大苯的含量可以增大介孔硅泡沫的孔径和孔容。当苯与P123的质量比为2.0时为最佳值,此时得到的介孔硅泡沫材料泡沫状结构最规整、比表面积高且孔径孔容较大,其中表面积可达641.3cm2/g,球形孔孔径可以达到43.8nm,孔容2.41cm3/g,过量苯会导致三维泡沫状结构的破坏。     

泡沫铝合金在气压传动排气消声器中的应用

泡沫铝合金是一种新型的功能结构材料，具有机械强度高、孔隙率可调节、耐高温、不燃烧、重量轻、价格低廉和制造工艺简单等特点。在气压传动排气消声的测试中，与铜粉末烧结件相比具有更好的排气性能和消声性能。用泡沫铝合金制成的消声器对于4000Hz以下噪声可降低10－15dB，对于4000Hz以上的噪声可降低30dB，对于废气中残存的一些铅、汞等重金属具有沉淀作用。将其作为排气消声器的消声材料，对于改善大气环境、防治污染将发挥巨大的作用。     

铝泡沫和石墨泡沫强化石蜡相变传热的数值模拟

针对有机相变材料石蜡导热系数低的问题,通过添加多孔介质的方法以强化石蜡相变传热,并运用CFD软件对石蜡相变传热系统进行二维数值模拟.模拟结果表明:铝泡沫和石墨泡沫都能有效提高相变材料传热速率,铝泡沫的强化传热效果明显高于石墨泡沫的传热效果.随着孔隙率减小,多孔介质/石蜡复合材料的有效导热系数增大,传热速率加快,凝固需要的时间缩短.并且,孔隙率越小,经过相同凝固时间,装置内对应点温度越低.     

发泡温度对泡沫铝孔结构的影响及机理分析

实验研究了物体发泡法泡沫铝制备过程中，发泡温度对泡沫铝孔结构的影响，并对其影响机理进行了分析。     

泡沫混凝土孔结构与导热性能的关系研究

采用光学显微镜及图像处理与分析软件相结合和导热系数测定仪对泡沫混凝土的孔结构与导热性能的关系进行了实验研究。结果表明,泡沫混凝土导热系数随着干密度的减小而降低,存在着k=e3.93-35 601.21/(φ+4 810.97)的关系;泡沫混凝土的导热系数随着孔隙率的增大而降低,有着k=e-23.33+20 395.74/(φ+916.1)的关系;泡沫混凝土内部的连通孔与不规则球体孔导致实际的导热系数高于理论值;随着发泡剂掺量的增大,泡沫混凝土平均孔径逐渐增大;平均孔径的增大会消弱孔隙率对导热系数的影响,但由于孔隙率的影响占主导作用,导热系数依然呈下降趋势。因此对于泡沫混凝土在分析孔径对导热系数的影响时应同时考虑孔隙率的影响。     

净化软磁合金用碳化硅质泡沫陶瓷过滤器的研制

制备了一种应用于软磁合金生产过程中的泡沫陶瓷过滤器.该过滤器以碳化硅、粘土、氧化铝粉为原料,采用有机泡沫浸渍工艺制备.分别用SEM和XRD分析断面显微结构和晶相组成.结果显示,断面显微结构致密均匀,晶相组成为碳化硅相、莫来石相和方石英相.该种泡沫陶瓷过滤器的抗热振性可达8次.现场应用表明,氧、氮、铝含量的去除率分别达到33.15%,22.79%和41.62%,过滤效果良好.     

渗流铸造泡沫铝合金的试验研究

泡沫铝合金是一种新型的多用途金属材料。采用正交实验法,选择三种不同粒径的填料,系统研究了粒子预热温度、金属液浇注温度和充型压力对渗流铸造泡沫铝合金成型工艺的影响。其中以粒子预热温度的影响为大。     

高吸油性三聚氰胺泡沫的制备与性能研究

为提供一种成本低廉、吸附能力强、制作简单的吸附材料,利用乙醇焰的高温快速-还原吸附在三聚氰胺上的氧化石墨烯,制备还原氧化石墨烯包覆的三聚氰胺泡沫(MF-G)。采用接触角、光电子能谱、扫描电子显微镜、万能试验机和吸附试验等研究手段,探讨MF-G泡沫的表面性质、孔结构、力学性质和吸附性能。结果表明:MF-G泡沫不仅具有高孔隙率和机械稳定性,而且还表现出超疏水性质,水在泡沫表面的接触角可达到148°;MF-G泡沫对油和有机溶剂具有优异的吸附能力,利用其对油和水显著的吸附差异,还可以高效率进行油水分离。MF-G泡沫具有的制备方法简单、高吸油性和有效的油水分离性使其有望在水处理领域实现广泛的应用。     

半固态挤压成型的研究现状

半固态挤压成型是集半固态加工与挤压成型为一体,利用半固态合金浆料的流变性能进行充型,并在压力作用下凝固成型的一种材料加工新技术。介绍了半固态挤压成型的原理及特点,阐述了半固态挤压成型在挤压合金方面的研究现状及其发展前景。     

聚乙烯/聚丙烃反应器合金的制备

采用负载型球形催化剂催化乙烯、丙烯两段淤浆聚合，得到了高孔隙率的球形PE／PP反应器合金．用光学显微镜、扫描电镜（SEM）和缸外光谱（FTIR）等方法对所得聚合物的颗粒形貌、孔隙率、粒径分布和组成等进行了袁征．实验表明，合金粒子的粒径分布较窄、形貌规则、孔隙率高．第二段聚合生成的聚丙烯有部分填充入聚乙烯粒子的细孔隙内，合金粒子的孔隙率低于聚乙烯粒子．DSC分析合金热行为和偏光显微镜观察结晶形貌表明，PE与PP两相部分相容．力学性能测试表明，PE／PP合金兼有高韧性和高刚性．材料的冲击断面具有韧性断裂特征，PE与PP两相间有较强的相互作用。     

Pore structure of ore granular media by computerized tomography image processing

The pore structure images of ore particles located at different heights of leaching column were scanned with X-ray computerized tomography （CT） scanner, the porosity and pore size distribution were calculated and the geometrical shape and connectivity of pores were analyzed based on image process method, and the three dimensional reconstruction of pore structure images was realized. The results show that the porosity of ore particles bed in leaching column is 42.92%, 41.72%, 39.34% at top, middle and bottom zone, respectively. Obviously it has spatial variability and decreases appreciably along the height of the column. The overall average porosity obtained by image processing is 41.33% while the porosity gotten from general measurement method in laboratory is 42.77% showing the results of both methods are consistent well. The pore structure of ore granular media is characterized as a dynamical space network composed of interconnected pore bodies and pore throats. The ratio of throats with equivalent diameter less than 1.91 mm to the total pores is 29.31%, and that of the large pores with equivalent diameter more than 5.73 mm is 2.90%.     

多辊下压式柔性拉形工艺及其数值模拟

研究了一种新型的柔性拉形工艺--多辊下压式柔性拉形(MRPFSF).采用动态显式有限元软件,对2024-O铝合金板材使用传统拉形工艺和MRPFSF工艺时成形球面件的过程进行了仿真,对比分析拉形过程中板材的应力、应变和板材厚度变化.仿真结果表明,与传统拉形工艺相比,使用MRPFSF工艺时得到的拉形件应力应变分布均匀,成形...     

铜薄膜作中间层的镁铝扩散焊接

采用磁控溅射技术在变形镁合金表面沉积铜薄膜,将其作为中间层对变形镁合金和硬铝合金进行了低温扩散焊接研究.利用超声波显微镜、X射线衍射、扫描电镜、电子探针等对焊接接头界面区域的显微结构及物相等进行了研究.研究结果表明,在镁合金基体上沉积的Cu薄膜主要以(111)、(200)晶向上生长,薄膜表面平整、均匀、致密;在扩散焊接工艺条件焊接温度T=455℃、保温时间t=90 min、压力P=3 MPa下获得了质量较好的Mg/Al焊接接头.焊接接头界面区域由铝镁原子比分别为3∶2,1∶1,12∶17三层镁铝系金属间化合物构成,接头断裂破坏发生在镁铝系化合物层,断口呈现明显的脆性断裂特征.     

泡沫铝的孔隙结构及透流特性

研究了加压渗流法制备的泡沫铝的孔隙结构特征，测定了泡沫铝试件在一定流量下的过滤效率、过滤阻力及渗透系数，分析了孔隙结构（孔径，孔隙率）及试样厚度对泡沫铝透流性能的影响；证明所研制的泡沫铝具有过滤效率高、过滤阻力小及渗透系数大的特点，其透流性能优良。     

The Combustion Synthesis Process of Al-Ti-C System in an Elevated-temperature Al-melt

One of the main disadvantages of combustion synthesis of ceramic/metal composite materials is the relatively high level of porosity present in the products. To synthesize TiC/ Al composites with a dense structure, this paper proposes a novel application of an elevated-temperature Al-melt to directly ignite and simultaneously in-filtrate Al-Ti-C preform dipped in the melt. The emphasis was placed on the combustion synthesis process and mi-crostructural evolution of the preform in the melt, by a liquid quenching test combined with the measurtment of the temperatwe history of the dipped preform. The results show that the combustion synthesis process of the preform in the elevated-temperature melt involves a series of reactions, and that higher temperature of the melt is favourable for the formation of TiC. The synthesized TiC / Al composites exhibit a dense strucame, which is attributed to the infiltration of the melt into the preform.     

烘烤对重铬酸盐封闭膜形貌和腐蚀行为的影响

铝合金阳极氧化后需进行封孔处理,烘烤极大的影响铝合金氧化膜的形貌和耐蚀性。本实验对2024铝合金阳极氧化经过重铬酸钾封孔处理后的膜进行烘烤研究。对烘烤过的试片与未烘烤的试片做电子显微镜表面形貌、激光共聚焦显微镜三维形貌及膜层的表面轮廓、膜的孔隙分布测试,且比较烘烤前后膜层的极化曲线。结果如下:铝合金阳极氧化重铬酸钾封闭后未烘烤膜的表面轮廓有很多非常深(深达18μm)、窄而细的孔,孔隙分布广而且密集;烘烤后封孔膜的孔隙深度降低,多孔层收缩变薄,孔隙分布稀疏。烘烤降低了重铬酸钾封闭膜的粗糙度且膜表面的凹坑有一定程度减少。从极化曲线看,烘烤后重铬酸钾封孔阳极钝化电流比未烘烤时低了几个数量级,说明烘烤提高了重铬酸钾封孔的铝合金的耐蚀能力。     

Pore structure characterization and seepage analysis of ionic rare earth orebodies based on computed tomography images

Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage. The ore body structure, pore distribution, pore and throat size, and pore network characteristics of topsoil, weathered, and semiweathered layers of ionic rare earth ore in southern Jiangxi Province were explored in this study. The effect of leaching operation on the pore structure was investigated, and main factors affecting the seepage were analyzed. Results showed that the semiweathered layer presents a dense structure and a small number of unconnected pores. Pores of topsoil and weathered layers are mainly long and narrow column openings with some planar fractures. Even pore distribution and large size span were observed. Compared with the weathered layer, the topsoil layer demonstrates larger voids, smaller average pore volume and equivalent radius, and fewer coordination throats; however, the average equivalent radius of the throat in the topsoil layer is larger and large-scale channels exist through ore body vertically. Hence, permeability of the topsoil layer is significantly higher than that of the weathered layer. Colloidal clay minerals migrate easily and the occurrence of silting in the small porosity blocks the throat and significantly decreases the permeability of the ore body in the leaching process. The equivalent radius of the throat is the key to the seepage. Reducing the migration of fine particles is an effective measure to protect the throat and shorten the leaching period.     

Thermodynamic Stability of the Molding Materials for Casting Ti-6Al-4V Alloy

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