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用软陶瓷球制作开孔泡沫铝的一种新方法外文文献翻译、中英文翻译,陶瓷球,制作,泡沫,一种,新方法,外文,文献,翻译,中英文

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外文资料翻译资料来源：Scripta Materialia文章名：A novel method for making open-cell aluminum foams with soft ceramic balls作 者：Kan-Sen Chou , Ming-An Song出版社：文 章 译 名： 用软陶瓷球制作开孔泡沫铝的一种新方法 用软陶瓷球制作开孔泡沫铝的一种新方法阚森筹*，明安松化学工程系，清华大学光复乡道，台湾新竹30013，中华民国2001年8月30日收到；2001年11月21日接受了摘要; 开孔泡沫铝的孔隙率高达90是从使用新工艺可以很容易地被压缩的软瓷球。陶瓷球的成分包括氧化铝颗粒、聚乙烯醇、水和少量的膨润土，要么羧甲基纤维素和羟丙基甲基纤维素。2002 ActaMaterialia公司 由Elsevier科学出版社出版有限公司保留所有权利。关键词：铸造；开孔泡沫铝；软陶瓷球; 引用： 金属泡沫材料得到了广泛的关注，由于其潜在的应用在许多不同的领域，例如隔音、换热器兑换，过滤，和催化剂载体。虽然这些材料已经研究了若干年, 最近还有许多关于这个问题的出版物, 包括新的制备方法和对显微组织和性能的深入研究。 关于制备方法、粉末冶金和铸件采用的是两个主要技术，使金属泡沫材料。利用NaCl最早铸造工艺之一; 粒子形成模具，它可以通过简单的移除溶于水。孔隙率，它可以通过此方法达到然而限于60%70%左右。此外，由于氯化钠颗粒开始的不规则性，由此产生的泡沫金属的结构通常是不太统一。因此，很多变化，这一进程提出了在文学。例如，可以使用聚氨酯泡沫和石膏模，或聚苯乙烯加上高压渗透粒子。 赵和孙使用铝盐粉末的烧结及溶解过程。 在本文中, 我们将报告一种新的方法, 利用软陶瓷球, 以取代硬, 立方形的 NaCl 粒子的开放细胞泡沫铝。由于这些陶瓷球是可变形的, 他们可以被压缩成密集的包装。结果, 铸件的孔隙率将达到90左右。这些陶瓷球能与-站立铸件温度和压力并且容易地去除由自来水。 1359-6462/02/2002美元-看前面的内容朗缪尔公司由Elsevier科学出版社出版有限公司 保留所有权利。PII：S1359-6462(01)01255-6; 2. 实验步骤：软陶瓷球由粗 Al2O3 颗粒、高分子添加剂、少量膨润土为烧结助剂和水制成。膨润土的用量仅为氧化铝的 1.0 (重量), 发现 sucient 为陶瓷球提供必要的强度, 以承受铸件温度下的铸件压力。以聚乙烯醇 (PVA) 为粘结剂, 为绿色强度。PVA 的两种类型是这里测试, 与一个从 Fluka (兆瓦 13万; 指定作为 C) 和另一个从斯格码 (兆瓦 30,00070,000; 指定作为 D)。首先, 氧化铝颗粒与烧结助剂完全混合。添加了含 PVA 的水溶液。alumina:water:PVA 的相对重量维持在100:48:47的实验报告。这种软混合然后被切成立方体的大小 3, 4 或5毫米, 然后放入一个空罐子轧制在球磨机为 120240s。由于它的柔软性, 这些立方体会很快变成球形球。球形形状是可取的, 这些陶瓷球的定期包装模具。这些陶瓷球然后储存在一个密封袋, 以防止任何损失的水分含量。为了提高这些陶瓷球的可压缩性, 我们添加了另一种可以被认为是保水剂的聚合物, 即羧甲基纤维素 (CMC; 指定为 A) 或羟丙基甲基纤维素 (HPMC; 指定为 B).在这项工作中, 他们的数量xed 了2的氧化铝。通过将xed 重量放在其顶部, 观察其高度变化, 研究了各陶瓷球的压缩性。变化的程度, 即 u Dh = h 0, 其中 h0 是测试过的陶瓷球的原始高度。应用的重量范围从5到 70g, 取决于球的柔软度。然后将这些陶瓷球放入一个由不锈钢制成的圆柱形模具, 并以逐层的方式进行。在每一层之间, 这些球被压实以获得高的填料窝, 从而减少填料床的孔隙度。由于陶瓷球是可变形的, 因此有可能达到更高的包装密度比使用坚硬微粒例如盐。 对意大利开胃酒 进行了类似的实验, 用筛分获得的各种尺寸的盐颗粒。为了达到均匀压实, 我们在陶瓷球的顶部放了一个软海绵, 以传递作用力。然后将一xed 重量的不锈钢板放在海绵顶部。另一块不锈钢从修理 高度下降约10cm 被应用来提供必要的力量, 压实。这个动作是重复的1040时间不断压缩这些 陶瓷球 球。聚合物添加剂有助于 保持这些 陶瓷球在 压缩的 过程中开裂。照片是在这出席和分析, 以了解的变化, 这填充床的孔隙度。最后, 通过将铝的预定重量放在该床顶部的圆形形状上进行铸造。整个模具被放入顶开炉, 其温度为740摄氏度, 举行约1.5 小时, 完全融化铝。然后, 用一个小的压力来推动熔融铝循环 通过床。当这个步骤完成后, 模具被从炉子里取出, 在环境中冷却了很短的时间。从模具中取出铸件后, 将其放入水浴中。用超声波振动消除了陶瓷球。因此获得了一种开放细胞的泡沫铝。3. 结果和讨论 第一个图所示。 1是有各种组合的单个球的可压缩性高分子添加剂和dierent荷载作用下。 这里我们可以看到，含陶瓷球添加剂B(i.e。 HPMC)通常比那些更柔软与添加剂A(i.e。CMC)。 因此， 小负荷压缩需要这种类型的陶瓷球。我们的经验表明，有必要保持sucient数量的水球在球内，以避免任何开裂 在压实，这将不可避免地导致在nal产品的缺陷。 添加剂B2C是 其余的报道，实验中使用在这里。; 如图。 1. 在一个单独的压缩负荷Eect各种添加剂的组合陶瓷球奖(BC添加剂B加C；B2C添加剂B加C两次)。; 如图。 3. 代表显示陶瓷球afterrandom包装的图片(原始球大小5毫米)。; 如图。 2. 减少毛孔区域作为一个功能的各种荷载组合的时候敲门(象征467/281表示xed的重量是467克，而敲的重量是281克)。; 如图。 4. 粒子的Eect(球)大小对泡沫铝的孔隙率。Noextra部队被用来包装这些(粒子)球。; 在图2中, 对床的孔隙面积 (从图像分析获得) 的减少作为敲门次数的函数进行了展示。明显地, eect 的重量大于xed 重量的 aecting 孔隙度。当我们增加敲重或敲次数时, 它的孔隙度也会持续降低到非常低的值。这完全是由于这些陶瓷球的变形性质。图3显示了在模具中包装的陶瓷球的 resentative 图片。球尺寸的 eect 下图4所示。在这里, 我们注意到, nal 泡沫的 rosity 将增加轻微时, 球的大小从5降到3毫米。 同时, 还展示了利用盐粒获得的孔隙度。由于使用变形陶瓷球, 孔隙度的增加是相当 signicant 的。当我们按下这些球, 在下降的重量帮助下, 孔隙度可以进一步增加到88.5。结果列于表1。 Scripta Materialia 46 (2002) 379382A novel method for making open-cell aluminum foams with soft ceramic ballsKan-Sen Chou *, Ming-An SongDepartment of Chemical Engineering, National Tsing Hua University, Kuang-Fu Road, Hsinchu, Taiwan 30013, ROCReceived 30 August 2001; accepted 21 November 2001AbstractOpen-cell aluminum foams with porosities up to 90% were made from a novel process using soft ceramic balls that can be compressed easily. Compositions of the ceramic balls include alumina particle, polyvinyl alcohol, water and small amounts of bentonite and either carboxymethyl cellulose or hydroxypropyl-methyl cellulose. 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.Keywords: Casting; Open-cell aluminum foams; Soft ceramic balls1. IntroductionMetallic foams have received broad attention due to their potential applications in many dif- ferent elds, such as sound insulation, heat ex- changers, lters, and catalyst carriers. Although these materials have been studied for some years 1, there are still many recent publications on this subject 29, including both new methods of preparation and in-depth studies of microstructure and properties.With regard to the preparation methods, pow- der metallurgy and casting are two principal techniques adopted for making metallic foams 1. One of the earliest casting process utilized NaCl* Corresponding author. Tel.: +886-035-715131; fax: +886- 035-715408.E-mail address: kschou.tw (K.-S. Chou).particle to form a mold that can be removed by simply dissolving in water. The porosity that can be achieved by this method is however limited to around 6070%. Also, the structure of the result- ing metallic foam is usually not very uniform due to the irregularity of starting NaCl particles. Many variations of this process have thus been proposed in the literature. For example, one can use poly- urethane foam and plaster mold 8, or polystyrene particles coupled with high-pressure inltration 9. Zhao and Sun tried the sintering and dissolu- tion process using Al and NaCl powders 10.In this article, we will report a novel method to make open-cell aluminum foams using soft ce- ramic balls to replace the hard, cubic-shaped NaCl particles. Since these ceramic balls are deformable, they can be compressed into dense packing. As a result, the products porosity after casting will reach around 90%. These ceramic balls can with- stand the casting temperature and pressure and are easily removed by running water.1359-6462/02/$ - see front matter 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved. PII: S 13 5 9 - 6 4 62 ( 01 ) 012 5 5 - 6380K.-S. Chou, M.-A. Song / Scripta Materialia 46 (2002) 3793822. Experimental procedureThe soft ceramic balls were made of coarse a- Al2O3 particles, polymeric additives, small amounts of bentonite as the sintering aid and water. The quantity of bentonite was only 1.0% (weight) of alumina and was found sucient to provide the ceramic balls with necessary strength to withstand the casting pressure at the casting temperature. Polyvinyl alcohol (PVA) was chosen as the binder for the green strength. Two types of PVA were tested here, with one from Fluka (MW 130,000; designated as C) and the other one from Sigma (MW 30,00070,000; designated as D). First the alumina particles were thoroughly mixed with the sintering aid. Then an aqueous solution contain- ing PVA was added. The relative weight of alu- mina:water:PVA was maintained at 100:48:47 for the experiments reported here. This soft mix was then cut into cubes of the size 3, 4 or 5 mm and then put into an empty jar rolled on a ball mill for 120 240s. Due to its softness, these cubes would quickly change into spherical balls. The spherical shape was desirable to the regular packing of these ceramic balls in the mold. These ceramic balls were then stored in a sealed bag to prevent any loss of moisture content.In order to increase the compressibility of these ceramic balls, we added another polymer that might be considered as the water-retaining agent,i.e. either carboxymethyl cellulose (CMC; desig- nated as A) or hydroxypropyl-methyl cellulose (HPMC; designated as B). Their quantities were xed at 2 wt.% of alumina in this work. The com- pressibility of each ceramic ball was investigated by putting a xed weight on top of it and ob- serving its height change. The extent of change, i.e.uDh=h0, where h0 is the original height of thetested ceramic ball. The applied weights range from 5 to 70 g, depending on the softness of the balls. These ceramic balls were then put into a cylindrical mold made of stainless steel in a layer- by-layer manner. Between each layer, these balls were compacted to obtain high packing den- sity, thus decreasing the porosity of the packed bed. Since the ceramic balls are deformable, it is therefore possible to achieve a higher packing density than that using hard particle such as salt.Similar experiments were performed for compari- son using salt particles of various sizes obtained by sieving.To achieve uniform compaction, we placed a soft sponge on top of the ceramic balls to transmit the applied force. A stainless steel plate of xed weight was then put on top of the sponge. Another piece of stainless steel falling from a xed height of about 10 cm was applied to provide the necessary force for compaction. This action was repeated for 1040 times to continuously compress these ce- ramic balls. The polymeric additives help to keep these ceramic balls from cracking during the compaction. Pictures were taken during this pro- cedure and analyzed to understand the changes in porosity of this packed bed.Finally, the casting was carried out by putting a pre-determined weight of aluminum in circular shape on top of this bed. The whole mold was then put into the top-open furnace and its tempera- ture was raised to 740 C, held for about 1.5 h to completely melt the aluminum. Then, a small pressure was applied to push the molten aluminum ow through the bed. When this step was done, the mold was taken out of the furnace and cooled in the ambient for a short while. After removing the cast from the mold, it was then put in a water bath. The ceramic balls were removed with the aid of ultrasonic vibration. An open-cell aluminum foam was therefore obtained.3. Results and discussionFirst shown in Fig. 1 is the compressibility of an individual ball having various combinations of polymeric additives and under dierent loads. Here we can notice that ceramic balls containing additive B (i.e. HPMC) is in general softer than those with additive A (i.e. CMC). As a result, a smaller load was needed to compress this type of ceramic balls. Our experience indicated that it is necessary to keep sucient amount of water within the balls to avoid any cracking of balls during compaction, which would inevitably induce defects in the nal product. Additives B 2C were used throughout the rest of experiments reported here.K.-S. Chou, M.-A. Song / Scripta Materialia 46 (2002) 379382381Fig. 1. Eect of load on the compressibility of an individual ceramic ball for various combinations of additives (B C additive B plus C; B 2C additive B plus two times of C).Fig. 2. Reduction in pore area as a function of knocking time for various combinations of loads (symbol 467/281 means that the xed weight is 467 g, while the knocking weight is 281 g).In Fig. 2, the reduction in pore area (obtained from image analysis) of the bed as a function of knocking times was exhibited. Clearly, the eect of the falling weight is greater than that of the xed weight in aecting the porosity. It also seems that the porosity can be decreased continuously to a very low value when we increased the knocking weight or knocking times. This is totally due to the deformable nature of these ceramic balls. A rep- resentative picture of ceramic balls packed in the mold is shown in Fig. 3. The eect of ball size was shown next in Fig. 4. Here we notice that the po- rosity of the nal foam would increase slightly when the ball size was reduced from 5 to 3 mm.Fig. 3. A representative picture showing ceramic balls after random packing (original ball size 5 mm).Fig. 4. Eect of particle (ball) size on porosity of Al foams. No extra force was used to pack these (particles) balls here.The porosity obtained from using salt particles was also exhibited for comparison. The increase in porosity due to the use of deformable ceramic balls is quite signicant. The porosity can be further increased to 88.5% when we pressed these balls with the help of a falling weight. The results are listed in Table 1. A picture of representativeTable 1Product porosity and applied loadApplied loadProduct porosityBrushing with hand82.3%1600 g 280 g (25 times)84.6%1200 g 400 g (15 times)87.5% 1200 g 400 g (25 times)88.5%Ball size 5 mm; 1600 g/ 280 g (25 times) meaning xed weight of 1600 g, falling weight of 280 g and knock 25 times.382K.-S. Chou, M.-A. Song / Scripta Materialia 46 (2002) 379382Fig. 5. A representative picture of foam produced by this method (size of pore is about 4 mm).open-cell aluminum foam obtained from this work is shown in Fig. 5.4. ConclusionsA novel process was reported here to make open-cell aluminum foams. It utilizes soft ceramic balls to achieve high packing density and hence high porosity of the foams. The porosity of the nal product can be manipulated through either ball size and the load applied during packing.After casting with molten aluminum, these ceramic balls can be easily removed with ultrasonic vibra- tion in water. The porosity of the aluminum foam from this method can be as high as 88.5%.AcknowledgementsThe authors wish to thank both Taiwan Power Company and ACT-RX Technology Corporation for nancial support of this work (contract num- ber P188052).References1 Davies GJ, Zhen S. J Mater Sci 1983;18:1899.2 Andrews E, Sanders W, Gibson LJ. Mater Sci Eng 1999;A270:113.3 Andrews EW, Gibson LJ. Scripta Mater 2001;44:1005.4 Mukai T, Kanahashi H, Yamada Y, Shimojima K, Mabuchi M, Nieh TG, Higashi K. Scripta Mater 1999;41:365.5 Olurin OB, Fleck NA, Ashby MF. Scripta Mater 2000;43:983.6 Calmidi VV, Mahajan RL. Trans ASME 1999;121:466.7 Paek JW, Kang BH, Kim SY, Hyum JM. Int J Thermo- phys 2000;21:453.8 Yamada Y, Shimojima K, Sakaguchi Y, Mabuchi M, Nakamura M, Asahina T, Mukai T, Kanahashi H, HigishiK. J Mater Sci Lett 1999;18:1477.9 Ma L, Song Z, He D. Scripta Mater 1999;41:785.10 Zhao YY, Sun DX. Scripta Mater 2001;44:105.A novel method for making open-cell aluminum foamswith soft ceramic ballsKan-Sen Chou*, Ming-An SongDepartment of Chemical Engineering, National Tsing Hua University, Kuang-Fu Road, Hsinchu, Taiwan 30013, ROCReceived 30 August 2001; accepted 21 November 2001AbstractOpen-cell aluminum foams with porosities up to 90% were made from a novel process using soft ceramic balls thatcan be compressed easily. Compositions of the ceramic balls include alumina particle, polyvinyl alcohol, water andsmall amounts of bentonite and either carboxymethyl cellulose or hydroxypropyl-methyl cellulose. ? 2002 ActaMaterialia Inc. Published by Elsevier Science Ltd. All rights reserved.Keywords: Casting; Open-cell aluminum foams; Soft ceramic balls1. IntroductionMetallic foams have received broad attentiondue to their potential applications in many dif-ferent fields, such as sound insulation, heat ex-changers, filters, and catalyst carriers. Althoughthese materials have been studied for some years1, there are still many recent publications onthis subject 29, including both new methods ofpreparation and in-depth studies of microstructureand properties.With regard to the preparation methods, pow-der metallurgy and casting are two principaltechniques adopted for making metallic foams 1.One of the earliest casting process utilized NaClparticle to form a mold that can be removed bysimply dissolving in water. The porosity that canbe achieved by this method is however limited toaround 6070%. Also, the structure of the result-ing metallic foam is usually not very uniform dueto the irregularity of starting NaCl particles. Manyvariations of this process have thus been proposedin the literature. For example, one can use poly-urethane foam and plaster mold 8, or polystyreneparticles coupled with high-pressure infiltration9. Zhao and Sun tried the sintering and dissolu-tion process using Al and NaCl powders 10.In this article, we will report a novel method tomake open-cell aluminum foams using soft ce-ramic balls to replace the hard, cubic-shaped NaClparticles. Since these ceramic balls are deformable,they can be compressed into dense packing. Asa result, the products porosity after casting willreach around 90%. These ceramic balls can with-stand the casting temperature and pressure and areeasily removed by running water.Scripta Materialia 46 (2002) 379382*Corresponding author. Tel.: +886-035-715131; fax: +886-035-715408.E-mail address: kschou.tw (K.-S. Chou).1359-6462/02/$ - see front matter ? 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.PII: S1359-6462(01)01255-62. Experimental procedureThe soft ceramic balls were made of coarse a-Al2O3particles,polymericadditives,smallamountsof bentonite as the sintering aid and water. Thequantity of bentonite was only 1.0% (weight) ofalumina and was found sufficient to provide theceramic balls with necessary strength to withstandthe casting pressure at the casting temperature.Polyvinyl alcohol (PVA) was chosen as the binderfor the green strength. Two types of PVA weretested here, with one from Fluka (MW ?130,000;designated as C) and the other one from Sigma(MW ?30,00070,000; designated as D). First thealumina particles were thoroughly mixed with thesintering aid. Then an aqueous solution contain-ing PVA was added. The relative weight of alu-mina:water:PVA was maintained at 100:48:47 forthe experiments reported here. This soft mix wasthen cut into cubes of the size 3, 4 or 5 mm and thenput into an empty jar rolled on a ball mill for 120240 s. Due to its softness, these cubes wouldquicklychangeintosphericalballs.Thesphericalshapewasdesirable to the regular packing of these ceramicballs in the mold. These ceramic balls were thenstoredinasealedbagtopreventanylossofmoisturecontent.In order to increase the compressibility of theseceramic balls, we added another polymer thatmight be considered as the water-retaining agent,i.e. either carboxymethyl cellulose (CMC; desig-nated as A) or hydroxypropyl-methyl cellulose(HPMC; designated as B). Their quantities werefixed at 2 wt.% of alumina in this work. The com-pressibility of each ceramic ball was investigatedby putting a fixed weight on top of it and ob-serving its height change. The extent of change, i.e.u Dh=h0, where h0is the original height of thetested ceramic ball. The applied weights rangefrom 5 to 70 g, depending on the softness of theballs. These ceramic balls were then put into acylindrical mold made of stainless steel in a layer-by-layer manner. Between each layer, these ballswere compacted to obtain high packing den-sity, thus decreasing the porosity of the packedbed. Since the ceramic balls are deformable, it istherefore possible to achieve a higher packingdensity than that using hard particle such as salt.Similar experiments were performed for compari-son using salt particles of various sizes obtained bysieving.To achieve uniform compaction, we placed asoft sponge on top of the ceramic balls to transmitthe applied force. A stainless steel plate of fixedweight was then put on top of the sponge. Anotherpiece of stainless steel falling from a fixed height ofabout 10 cm was applied to provide the necessaryforce for compaction. This action was repeated for1040 times to continuously compress these ce-ramic balls. The polymeric additives help to keepthese ceramic balls from cracking during thecompaction. Pictures were taken during this pro-cedure and analyzed to understand the changes inporosity of this packed bed.Finally, the casting was carried out by putting apre-determined weight of aluminum in circularshape on top of this bed. The whole mold was thenput into the top-open furnace and its tempera-ture was raised to 740 ?C, held for about 1.5 h tocompletely melt the aluminum. Then, a smallpressure was applied to push the molten aluminumflow through the bed. When this step was done, themold was taken out of the furnace and cooled inthe ambient for a short while. After removing thecast from the mold, it was then put in a water bath.The ceramic balls were removed with the aid ofultrasonic vibration. An open-cell aluminum foamwas therefore obtained.3. Results and discussionFirst shown in Fig. 1 is the compressibility of anindividual ball having various combinations ofpolymeric additives and under different loads.Here we can notice that ceramic balls containingadditive B (i.e. HPMC) is in general softer thanthose with additive A (i.e. CMC). As a result, asmaller load was needed to compress this typeof ceramic balls. Our experience indicated that itis necessary to keep sufficient amount of waterwithin the balls to avoid any cracking of ballsduring compaction, which would inevitably inducedefects in the final product. Additives B 2C wereused throughout the rest of experiments reportedhere.380K.-S. Chou, M.-A. Song / Scripta Materialia 46 (2002) 379382In Fig. 2, the reduction in pore area (obtainedfrom image analysis) of the bed as a function ofknocking times was exhibited. Clearly, the effect ofthe falling weight is greater than that of the fixedweight in affecting the porosity. It also seems thatthe porosity can be decreased continuously to avery low value when we increased the knockingweight or knocking times. This is totally due to thedeformable nature of these ceramic balls. A rep-resentative picture of ceramic balls packed in themold is shown in Fig. 3. The effect of ball size wasshown next in Fig. 4. Here we notice that the po-rosity of the final foam would increase slightlywhen the ball size was reduced from 5 to 3 mm.The porosity obtained from using salt particleswas also exhibited for comparison. The increase inporosity due to the use of deformable ceramic ballsis quite significant. The porosity can be furtherincreased to 88.5% when we pressed these ballswith the help of a falling weight. The resultsare listed in Table 1. A picture of representativeFig. 1. Effect of load on the compressibility of an individualceramic ball for various com