图片来自NYT 美国最近开展了一组实验，使用玻璃碳纤维复合材料作为桥梁和铁路的骨架支撑体，而不是传统的使用钢筋骨架。公开的视频介绍了这种新型的骨架结构建设过程：先是玻璃碳纤维做成布袋状，然后充气鼓起，弯成所需要的特殊形状，表面注入树脂固化成空心的骨架管，形状颇似各地乡镇经济开发区门口的充气彩虹。这种骨架管由于是碳材料为主，所以运输装载很方便，节省了大量的重型机械作业成本。空心复合玻璃碳纤维管立住以后，便开始往管内填塞混凝土，实际使用时主要的强度还是由混凝土提供，但是这种碳复合材料使用以后能进一步延长骨架的使用寿命，断裂韧性也增强，相比于传统钢筋填充来说更重要一点是耐氧化和耐腐蚀能力大为提高，这对于建筑寿命有很大影响。在冬天路面需要利用除冰盐的情况，腐蚀是一个很大的破坏因素。工程师对于纤维管填充混凝土结构的力学测试也几乎和以往结构相当。从美国其他的新闻链接来看，在铁路铺设桥梁上也做了相同的实验。由于美国很多交通路面和桥梁都面临着更新，所以这项新技术很有可能大规模地利用到下一代地面设施中。中国是不是也在考虑这样的建设？ ------------------------------- News of New York Times: http://www.nytimes.com/2009/10/13/science/13bridge.html?_r=1 October 13, 2009 Building a Bridge of (and to) the Future By HENRY FOUNTAIN PITTSFIELD, Me. The Neal Bridge is barely a bump in the road for motorists roaring down Route 100 south of this central Maine town. Its a modest bit of the nations infrastructure two lanes wide and 34 feet long, enough to span a small stream. The bridge is newer than most, as suggested by the still-black asphalt and the fresh galvanized gleam of the guardrails. But its what is underneath that really makes the bridge stand out. Rather than steel or concrete beams, the structure consists of 23 graceful arches of carbon- and glass-fiber fabric. These are 12-inch-diameter tubes that have been inflated, bent to the proper shape and stiffened with a plastic resin, then installed side by side and stuffed with concrete, like giant manicotti. Covered with composite decking and compacted soil, the arches support a standard gravel-and-asphalt roadway. The bridge is the first of what its designers, about 50 miles up the road at the University of Maine in Orono, hope will be many of its type, combining composite materials with more conventional ones like concrete. With an estimated 160,000 of the nations 600,000 road bridges in need of repair or replacement, if it or other hybrid designs catch on, they could mark a breakthrough in the use of fiber-reinforced plastics, known as F.R.P., on highways. This was an experiment for us, said Habib J. Dagher, director of the universitys Advanced Structures and Composites Center , where the design was developed over seven years. It was time to get out of the lab and see if it really works. The bridge, built last November for about $600,000, is being monitored with deflection sensors and other instruments, and so far is holding up under the daily onslaught of traffic. It went amazingly well, Dr. Dagher said. We learned a lot. It turned out to be $170,000 less expensive than a precast bridge. It worked so well, in fact, that it attracted the attention of the Obama administration; Transportation Secretary Ray LaHood toured the center in August. And a second, similar bridge was completed in late summer, farther north, in Anson. The fiber-arch design was the lowest of seven bids. Long the stuff of surfboards and pleasure boats, and more recently used in aircraft wings and other components, plastic polymers reinforced with fibers were first researched for use in bridges in the 1980s. Civil engineers were attracted to them for the same reasons other designers were their strength, light weight and corrosion resistance. But the materials have not exactly revolutionized highway infrastructure. F.R.P. strips and sheets have been used to repair concrete or steel on existing bridges, or to strengthen structures against earthquakes. Glass-fiber rods have replaced steel in some reinforced concrete work, because corrosion of steel rebar from road de-icing chemicals destroys concrete. When it comes to larger-scale structural components, however, fiber-reinforced plastics have had less of an impact. They have mostly been used in bridge decking, where corrosion resistance is critical and the lighter weight allows for a higher live load of vehicles. Only a handful of bridges have major support beams made from them. One reason F.R.P. components havent caught on, experts say, is that engineers and contractors have little experience with the materials, and full standards guiding their use in highway construction have not been developed. Engineers have to deal with life-safety issues, said John P. Busel, director of the composites growth initiative of the American Composites Manufacturers Association . They have a desire to understand how materials fully develop and how they fully last before they specify them. The materials also do not always interact well with others. One problem with F.R.P. bridge decks, for example, is that the road surface asphalt or concrete, applied as an overlay can wear out quickly, said Lijuan Cheng, an assistant professor of engineering at the University of California, Davis . But the main argument against using fiber-reinforced plastics has been economic. No. 1 is the upfront cost issue, said Paul Ziehl, an associate professor of engineering at the University of South Carolina . Thats a tough one to get around. Dr. Ziehl, who helped design and test F.R.P. beams used on a small bridge in Texas, said the problem was that no two projects were the same. If youre going to design things that really make sense from an optimized engineering standpoint, they are going to be one-of-a-kind items at first, until economies of scale kick in, he said. The beams for the Texas bridge, for example, were custom designed and built using a labor-intensive method. The construction industry is very persnickety about cost, Mr. Busel said. With F.R.P. decks, he added, were more expensive, sometimes twice as expensive, as conventional ones. What contractors need to understand, he said, is that there are transportation, labor and equipment savings from using lighter components, and potential maintenance savings, too. Such savings were all part of the goal for the University of Maines design, Dr. Dagher said. Little costly F.R.P. material is used it serves largely as a shell for the concrete, which is cheaper. The tubes help protect the concrete from de-icing chemicals, potentially reducing maintenance costs, and no internal rebar is needed. Its exoskeleton reinforcement, Dr. Dagher said. The arches are not the only hybrid design in use. John Hillman, an engineer and president of HC Bridge Company in Wilmette, Ill., has developed straight beams that combine polymers with concrete and steel. The basic beam consists of a rectangular F.R.P. tube with an arch-shaped conduit formed inside it. The conduit is filled with concrete, which provides compressive strength, and steel rods along the bottom of the tube provide tensile strength. The beams have been used on a test railroad bridge in Colorado and several road bridges in Illinois and New Jersey. Everything about the beam is designed to be compatible with conventional means of construction, said Mr. Hillman, who has been working on the design for 14 years. Were very close right now to parity with concrete and steel on an installed-cost basis. Mr. Hillmans beams still have to be delivered by truck, although they are light enough that several can be carried on one flatbed. The University of Maine arches, on the other hand, can be fabricated on site the fabric inflated, bent around a simple form and infused with resin using a vacuum pump. Before they are filled with concrete they are light enough to be installed quickly, without the need for large cranes or other heavy-duty equipment. The second bridge was built in nine working days, Dr. Dagher said. A spinoff company is working on more plans, including an 800-foot project that consists of multiple short spans. We see single 300-foot spans in the future, Dr. Dagher said. Were excited about taking this to the next level.
密苏里大学出了一个简报，该校的Kwon J. W.教授在物理应用快报上报道了最新的关于微型核电池的结果，这种新型的二次电池概念在能源领域研究比较少，但是由于能量密度比一般锂电池高几个数量级，所以在某些特殊环境下应用很有希望，如纳米卫星。核电池的提法比较吓人，但并不是我们通常所想的发生核裂变的链式反应输出能量，而是利用被辐射后的高能同位素衰变时逐步释放出的能量。Kwon在这个新工作中主要贡献在于利用金属硒作为能量接受体，避免了固体半导体材料在高能辐射下因为晶格发生畸变而失效。具体的工作原理是同位素硫35释放出高能beta射线激发半导体硒中处于价带的电子，造成电荷分离，半导体硒和金属电极形成肖特基势垒促进了电子和空穴的分离，当外电路加上载荷时，电子就会经由外加载荷奔向空穴结婚，灯亮了。Kwon目前得到的能量转换效率仅有1.2%，功率在nW级。 这种利用核辐射来制备电池是不是为核废料处理提供了一种能源回收的策略？ MU Researchers Create Smaller and More Efficient Nuclear Battery Mizzou scientist develops a powerful nuclear battery that uses a liquid semiconductor Oct. 07, 2009 Story Contact(s) : Kelsey Jackson, JacksonKN@missouri.edu , (573) 882-8353 COLUMBIA, Mo. Batteries can power anything from small sensors to large systems. While scientists are finding ways to make them smaller but even more powerful, problems can arise when these batteries are much larger and heavier than the devices themselves. University of Missouri researchers are developing a nuclear energy source that is smaller, lighter and more efficient. To provide enough power, we need certain methods with high energy density, said Jae Kwon, assistant professor of electrical and computer engineering at MU. The radioisotope battery can provide power density that is six orders of magnitude higher than chemical batteries. Kwon and his research team have been working on building a small nuclear battery, currently the size and thickness of a penny, intended to power various micro/nanoelectromechanical systems (M/NEMS). Although nuclear batteries can pose concerns, Kwon said they are safe. People hear the word nuclear and think of something very dangerous, he said. However, nuclear power sources have already been safely powering a variety of devices, such as pace-makers, space satellites and underwater systems. His innovation is not only in the batterys size, but also in its semiconductor. Kwons battery uses a liquid semiconductor rather than a solid semiconductor. The critical part of using a radioactive battery is that when you harvest the energy, part of the radiation energy can damage the lattice structure of the solid semiconductor, Kwon said. By using a liquid semiconductor, we believe we can minimize that problem. Kwon has been collaborating with J. David Robertson, chemistry professor and associate director of the MU Research Reactor , and is working to build and test the battery at the facility. In the future, they hope to increase the batterys power, shrink its size and try with various other materials. Kwon said that the battery could be thinner than the thickness of human hair. Theyve also applied for a provisional patent. Kwons research has been published in the Journal of Applied Physics Letters and Journal of Radioanalytical and Nuclear Chemistry . In addition, last June, he received an outstanding paper award for his research on nuclear batteries at the IEEE International Conference on Solid-State Sensors, Actuators and Microsystems in Denver (Transducers 2009). (谁找到第二篇文章和我说一声)
读到一个新闻，其实就是一个公司的枪手广告，不过里面游戏信息可以拾取。该公司大概在研发碳纳米管在聚合物及金属复合材料中的应用，特别强调了风力发电机桨片。中国准备在内陆和沿海大力发展风力发电，如果能提高桨片的剪切强度和弯曲强度，那么就能够加大臂长，提高风能利用率。碳纳米管复合材料如果能够很好地控制工艺流程，还是比较有希望挤入这个巨大的市场。 另外一方面，碳纳米管和金属复合一直是一个梦想，金属成型比陶瓷需要更温和的温度，所以能够保护碳纳米管的结构和强度。这个公司提带指出碳纳米管能够有效增强金属铝的强度，达到钢的强度，这是很好地结果，对于军事和民用轻型高比强材料的应用有巨大的潜力。但是一个很大的问题是金属如何和碳纳米管均匀分散：金属颗粒密度大，表面没有基团，在一般溶剂中无法形成悬浮液或者胶体。物理性质和化学性质的不同直接导致了碳纳米管在这个材料领域的应用，而对于陶瓷和有机聚合物来说解决的手段已经比较成熟。如果检索有关文献，金属科学研究者普遍采用了球磨的方法。这种方法具有原始粗旷的美，然而碳纳米管不可避免地被扭曲，剪切，弯折，摩擦，导致结构巨大的破坏。 最近我和朋友无意发现了一个简单方法，通过对金属表面适当地处理，居然成功获得碳纳米管的复合粉体。有很多细节工作还需要做，偏巧院里电镜出问题，相当于抛了一盆凉水。 晚上散步遇到一对台湾夫妇，说他们老大9个月就站起来走路，后来发现长大了平衡能力不够。到医院一问，医生直接说：是不是小时候爬的时间短？爱因斯坦好像小时候说话较晚，是不是和高智商有关？ Bayer MaterialScience Showcases Its Baytubes Carbon Nanotubes at Rusnanotech '09 ( Nanowerk News ) The extraordinary properties of Baytubes carbon nanotubes (CNTs) have sparked new and highly promising lightweight design concepts that improve both energy efficiency and mechanical strength. Such concepts are the focus of Bayer MaterialScience AGs presentation at the RusNanoTech trade show at the German stand, Pavilion 3, at Moscows Expocentre from October 6 to 8, 2009. This is the second time the company has showcased technical innovations based on Baytubes carbon nanotubes at this major forum in Russia. Possible CNT applications are far from limited to lightweight designs, however. CNTs are also suitable for many different applications, for example in mechanical engineering and the chemical, electrical and electronics, and sports goods industries, observes Dr. Raul Pires, who is in charge of global activities for nanotubes and nanotechnology products at Bayer MaterialScience, in a presentation at the accompanying conference on October 8. One prime example of enhanced energy efficiency is the use of Baytubes in wind turbines. The length of rotor blades was previously limited to around 60 meters in order to ensure reliable operation even in very windy conditions. The nanotubes enormous strength makes the rotor blades very stiff, which also enables longer blades to be designed, explains Dr. Pires. Whats more, the lightweight design of the nanotubes - and thus of the hybrid materials in which they are incorporated - boosts the efficiency of the wind-to-power conversion process. Baytubes do not just improve the properties of plastics and other polymer materials, however. CNT additives can also make metals much harder. For example, adding Baytubes to aluminum processed using powder metallurgy enables tensile strengths to be achieved that almost match those of steel. Previously, it has only been possible to assign mechanical properties of this kind to aluminum by adding rare and expensive metals in a complex alloying process, explains Professor Dr. Horst Adams, vice president future materials at Bayer MaterialScience. google_protectAndRun("ads_core.google_render_ad", google_handleError, google_render_ad); The impact strength and thermal conductivity of aluminum can also be improved by adding nanotubes. This enables the weight of components to be reduced still further, which increases their energy efficiency, for example in the automotive and aircraft industries. Bayer MaterialScience is working with Zoz GmbH on the development of customized CNT-reinforced aluminum materials. This German company headquartered in Wenden is a global supplier of innovative systems and equipment, in particular for the manufacture of nanostructured materials. It has extensive experience in areas such as the high-energy grinding and mechanical alloying of these materials. Thanks to the development of an innovative, in-house production process, Bayer MaterialScience is one of the few companies in the world capable of producing carbon nanotubes of the required purity on an industrial scale. As early as 2007, the company started operations at a pilot plant in Laufenburg, Germany, that can produce 60 metric tons/year. An additional pilot facility with an annual capacity of 200 metric tons is currently under construction at CHEMPARK Leverkusen. About Bayer MaterialScience With 2008 sales of EUR 9.7 billion, Bayer MaterialScience is among the worlds largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction and the sports and leisure industries. At the end of 2008, Bayer MaterialScience had 30 production sites and employed approximately 15,100 people around the globe. Bayer MaterialScience is a Bayer Group company.
图片来源： http://ceramics.org/ceramictechtoday/wp-content/uploads/2009/09/valvo_batt.png 美国新闻报道Volvo C30已经集成锂电池充电系统，有些参数和性能值得注目： Recharging the C30s EnerDel battery pack via a household supply at 230V, 16A would take about eight hours. Thats connection comparable to what would be required for a laundry dryer or mid-sized window air conditioner. The C30 BEV is limited to a top speed of about 130 km/h (80 mph)more than sufficient, Volvo says, for a city car application. Acceleration from 0 to 100 km/h (62 mph) will take less than 11 seconds. The car would have a range of up to 150 kilometers (93 miles)longer than the distance 90% of all Europes motorists drive per day and surely covers a wide swath of U.S. motorists as well. 这个应该作为城内用车已经足够了，城际交通用的话充电时间有点长，如果能做成可拆换型的更具有吸引力。 最近一段时间在基础科学上对于锂电池研究也有了一些新的概念，其中碳包裹正负极功能材料屡屡被证明有很好的效果。我粗浅读了几篇文章，从材料制备角度上来看都没有很高的难度，但是是不是都很好地技术转移到实际电池系统中还需要艰辛的努力。 感兴趣的同学可参考 1, Angew. Chem. Int. Ed. 2008, 47, 1-6 2, Angew. Chem. Int. Ed. 2009, 48, 6485-9 以及最近刚出来的一片综述： 3, 'Research on Advanced Materials for Lithium-ion Battery' Adv. Mater. 2009, 21, 1-15 今天又看到PNNL上一个简明新闻引起了大家的广泛兴趣： A splash of graphene improves battery materials Thin carbon sheets enhance titanium dioxide-based batteries Researchers would like to develop lithium-ion batteries using titanium dioxide, an inexpensive material. But titanium dioxide on its own doesn't perform well enough to replace the expensive, rare-earth metals or fire-prone carbon-based materials used in today's lithium-ion batteries. To test whether graphene, a good conductor on its own, can help, PNNL's Gary Yang and colleagues added graphene, sheets made up of single carbon atoms, to titanium dioxide. When they compared how well the new combination of electrode materials charged and discharged electric current, the electrodes containing graphene outperformed the standard titanium dioxide by up to three times. Graphene also performed better as an additive than carbon nanotubes. Yang discussed this work and provided an overview of the field of electrical storage materials. (Contact Mary Beckman , 509-375-3688) This research was funded by PNNL. Reference: Jun Liu, Multifunctional materials from self-assembly for energy storage , Tuesday, Sept. 22,2009 Micro Nano Breakthrough Conference, Portland, Ore. NOTE: Gary Yang spoke in place of Jun Liu. 我的感觉是一年后笔记本电脑无源使用8小时应该不成问题，两年后电动汽车应该会比较流行。感谢材料科技的进展。
发发老兄是个朴素思想家，他能从生活中琢磨一些常人忽略掉的思考，这一点科学网上的大部分教授们没有比得过他的，我的意思是说发发兄在科学网上给大教授们在开课，大家都听得很认真。比如这篇《 了如指掌？ 》 我也听得认真，因为科学研究中确实有很多被我们忽略了的却左右了结果的现象，即便是现在我也不敢保证有几个人能少走弯路。比如说在99年一篇发表在NANOSTRUCTURED MATERIALS一篇文章中，作者明确指出了合成的氧化钛粉末经过醇洗会对材料的晶型和尺寸产生显著的影响，但是我读到很多文章依然是不加辨别地用乙醇来最后洗粉。没有人会仔细研究一下自己的纳米粉体合成出来以后会不会在乙醇中发生变化，因为大家都知道乙醇是一种惰性溶剂，一般不会在常温下参与反应。但是这篇文章的作者Hague D. C.用了心思，研究了一下不用醇洗的产物。结果发现锐钛矿型的氧化钛在醇里洗了以后变成无定型态，至少在纳米颗粒的表面已经发生了这种相转变。这种相转变对于光催化性能显然不是好的过程，对于陶瓷烧结来说增加了团聚程度更加不易于获得致密的烧结体。氧化钛是一个很热门的研究材料，大家不知道是不是都考察了这个过程？ 材料工艺的稳定性要求每一道工序都必须可靠，如果想当然的话很有可能造成品质问题，而且还浪费了大量的不恰当消耗。 在最近的研究过程中，我发现碳管的处理也存在着这种想当然的现象，比如说热处理过程。一般我们都认为碳管在500度以下是稳定的，即便在空气中煅烧也不会有太大的损失，然而事情并没有这么简单，对于单壁碳纳米管来说，经过硝酸的处理，碳管的结构已经被硝酸分子撑开或者表面严重氧化，即便是在400度下，处理后的碳管损失也会相当巨大。如果以后要批量化生产复合材料，这样的处理工艺就不能想当然，而是需要专门的研究来获得合适的处理条件。 所以，不要轻信经验，也不要想当然。要成为真正的了如指掌，还得好好研究一下研究的脉络再说。 reference: 1,D.C. Hague and M.J. Mayo. J. Am. Ceram. Soc. 77 (1994), pp. 19571960. 2, D. C. Hague, Ph.D. Thesis, The Pennsylvania State University (1995). 3, Mayo M. J., Seidensticker J. R., Hague D. C., Carim A. H., Nanostructured Materials, 1999, 11, 271-82.
科学网上报道了一个科研进展新闻，说是日本科学家用中子源轰击的方法得到了小晶体颗粒金刚石，新闻见《 用石墨合成小晶体颗粒金刚石 》。我一直很佩服科学网网站一些负责编译的编辑们，因为他们辛勤的工作使得我们能了解一些错过了的科研进展。我第一眼看到这个新闻的时候就吃了一惊，因为现在也在和同事旁门左道地做一些相关的实验，也都是用高能粒子束去轰击碳材料。如果你读了这篇文章的前言，你会了解更多科学家为什么要研究这个东西。从材料角度来讲，用高能粒子束轰击石墨有两个启示，一个是产生大量的表面缺陷；第二个是研究作为防辐射材料吸收粒子束的效率。当然这两者都是相关的。读了文章以后知道了文章得到的并不是纳米尺度的金刚石，而只是无定型的金刚石。无定型金刚石用非科学的定义来说就是从埃米尺度来看单碳原子确实是金刚石特征价键结构，但是当在纳米尺度以上来观察的话这些碳原子群的价键取向排布并不是有序的。 实际上前一段时间已经有一个相关的工作提供了另一个角度来看待粒子束轰击的问题，也就是表面缺陷能够成为分离碳材料的焊接源，从而提高载荷在相邻碳材料之间的传递作用。更加明白地说这种碳材料就是碳纳米管。但是在这一篇物理评论快报文中，作者使用了高取向的石墨材料，在高能字束轰击以后，石墨表面和内部产生了大量的福仑克尔缺陷(frenkel)和瓦格勒(wigner)缺陷：某些碳原子在获得高能量以后脱离原来晶格位置进入相邻的间隙位中，同时留下空穴位。这种空穴位为进一步拓扑缺陷的形成提供了物质空间。另一方面，层状石墨材料在层间是以sp2杂化轨道存在的，当缺陷形成以后，大量的孤电子非稳态价键形成，碳原子的电子排布重新组合，层间碳原子有很大地几率以sp3杂化电子轨道结合。当作者进一步使用高速冲击并淬冷的方法处理被轰击石墨后，发现石墨结构发生了深刻的变化。这和移形大法很相似，可以想象成不同层间的碳原子和拓扑空位相互结合。而金刚石结构就是碳原子由纯粹sp3杂化键形成，作者把这种材料叫做无定型金刚石材料。这篇文章读起来没有什么很多的收获，除了作者使用高能中子束使人羡慕以外，就科学内容来说并没有更多的可读之处。我觉得这样的工作能在物理评论快报上发表是近十来年物理界对于材料科学诸多发现的一种信仰和迷信，作者更应该把类似的工作投到Journal of material research或者CARBON这样更专业的期刊上。就材料的本身分析而言，作者甚至只用了raman这一种表征手段，而Raman结果本身并不能提供很完整的信息，如果谱以XRD，EELS, TEM来提供更多的晶体结构信息、化学键信息和形貌表征的话，这个故事讲起来会更令人信服一些。 关于无定型态金刚石，有什么更新颖的性能和应用，我们可以等待这个小组进一步的研究结果。 我想起另一篇工作，利用碳纳米管表面氟化处理以后形成悬键，通过陶瓷科学中常用的烧结技术，结果得到了高强度的块体材料。PRL这个工作可能可以用在这个思路中，不过中子束轰击不要太猛。 references 1， Pathway for the Transformation from Highly Oriented Pyrolytic Graphite into Amorphous Diamond 2， Super-Robust, Lightweight, Conducting Carbon Nanotube Blocks Cross-Linked by De-fluorination
标签: 加州笔记
