五种有趣的材料舞钢

五种有趣的材料

五种有趣的材料 2011年12月10日 来源： solidot的中文简译：《新科学家》列出了几种有非常独特的物质，它们都具有非常奇特的属性。这些东西我们可能都有所耳闻，因此提供的视频更值得观看（地震损坏光缆原因，部分图片视频速度很慢）。" 1.Dilatants，这种液体受压之后会变得坚硬，你可以在上面行走，但是停下来的话，你就会陷进去。视频1，2.2.Auxetic materials，与我们的直觉相反，这种物质被拉伸的时候不会变细而是变粗，视频。 字串43.超流体，流动的时候不会产生摩擦力，它可以向上流动，视频（不能很好的反应物质的特性）4.磁流体，可以轻易的向我们展示磁场分布，视频 5.干冰，比较有趣的是它能够在瞬间产生很多泡泡，因此如果再混杂上其它物质如水，肥皂会产生很多奇特的现象。视频1，2，3，4，5。" 上面几种种材料，也许能给我们制造带来不少独到的用处，欢迎大家充分发挥想象……相关补充：Dilatants：胀塑性流体。这类流体在流动时，表观粘度随剪切速率的增大而增大。某些湿沙，含有硅酸钾、阿拉伯树胶等的水溶液均属于胀塑性流体。auxetic materials：细胞增大材料，其特性是当拉伸时变宽而挤压时变窄，也就是说，它们具备负的泊松比。这些材料还具备其他一些有用的性能，包括：高断裂韧度、抗压缩和能量吸收等。因此，它们在许多领域存在着潜在的应用，如：防弹衣或头盔，以及抗冲击产品等等。　　一些常用的合成聚合物是细胞增大材料。现在，细胞增大泡沫(auxeticfoams)已经研制成功，细胞增大纤维也将很快投入市场。英文原文：To keep you amused over the Christmas and New Year break, we've compiled a short list of fun materials - stuff that behaves a little bit outside the norm. Here's what we came up with. 字串9 1. Dilatants - fluids that get more solid when stressed. The classic example is a mixture of cornflour and water - it's runny until you hit it when it becomes solid.This video shows how that it possible to run across an apparently liquid pool of the stuff because your footfalls solidify it. If you stop, you sink.I like this video better though - it shows how sound waves from a subwoofer produce interesting shapes in a dilatant. If you want to have a go yourself, try this recipe.2. Auxetic materials - materials that get thicker when stretched. Pull them in one direction and they expand in another. 字串3

This video (.mov format) from Bolton University, UK, shows an auxetic foam in action. I like these because they are totally counter-intuitive - you just expect things to get thinner when stretched. Read more about them in a feature here or on this research page.3. Superfluids - liquids that flow without friction. They can effortlessly flow through the tiniest of cracks and will even flow up the walls of a beaker and out the top. It's possible because all the atoms in a superfluid are in the same quantum state, so they all have the same momentum and move together. To make a superfluid you must cool helium down to a couple of a degrees below zero - not one to try at home. They can be used to make super-sensitive gyroscopes to test theories about gravity. 字串1

Sadly I couldn't find any spectacular videos of supefluids in action. Here's a not-too-exciting one of superfluid helium drops (mpg format). Read more here.4. Ferrofluids - magnetic fluids that can look spectacular. They're made from nanoscale magnetic particles suspended in a liquid. The spectacular sculpture in the video below is made using a ferrofluid and electromagnets.Ferrofluids can be used to drive speakers or make shock absorbers that vary their stiffness in milliseconds. This guide shows you how to make your own ferrofluid at home. 字串6 5. Dry ice. Carbon dioxide freezes at -78.5 °C and it's fun and versatile stuff. These videos show how it can produce massive amounts of bubbles when mixed with soap and water, drive a simple cannon , transform your swimming pool, produce pretty patterns when dropped onto water in small chunks and spice up the all-too-familiar Diet Coke and Mentoes reaction. You can even freeze soap bubbles hard and pick them up, if you follow this guide. A block of dry ic

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