Applications of Mechanical Properties of Nanomaterials
Tougher and harder cutting tools .Cutting tools made of nanomaterials, such as tungsten carbide, tantalum carbide, and titanium carbide, are much harder, much more wear-resistant, erosion-resistant, and last longer than their conventional (large-grained) counterparts. Also, for the miniaturization of microelectronic circuits, the industry needs micro drills (drill bits with diameter less than the thickness of an average human hair or 100 µm) with enhanced edge retention and far better wear resistance. Since nanocrystalline carbides are much stronger, harder, and wear-resistant, they are currently being used in these micro drills.
Automobiles with greater fuel efficiency . In automobiles, since nanomaterials are stronger, harder, and much more wear-resistant and erosion-resistant, they are envisioned to be used in spark plugs. Also, automobiles waste significant amounts of energy by losing the thermal energy generated by the engine. So, the engine cylinders are envisioned to be coated with nanocrystalline ceramics, such as zirconia and alumina, which retain heat much more efficiently that result in complete and efficient combustion of the fuel.
Aerospace components with enhanced performance characteristics. One of the key properties required of the aircraft components is the fatigue strength, which decreases with the component’s age. The fatigue strength increases with a reduction in the grain size of the material. Nanomaterials provide such a significant reduction in the grain size over conventional materials that the fatigue life is increased by an average of 200-300%. In spacecrafts, elevated-temperature strength of the material is crucial because the components (such as rocket engines, thrusters, and vectoring nozzles) operate at much higher temperatures than aircrafts and higher speeds. Nanomaterials are perfect candidates for spacecraft applications, as well.
Ductile ceramics. Ceramics are very hard, brittle, and hard to machine even at high temperatures. However, with a reduction in grain size, their properties change drastically. Nanocrystalline ceramics can be pressed and sintered into various shapes at significantly lower temperatures. Zirconia, for example, is a hard, brittle ceramic, has even been rendered superplastic. However, these ceramics must possess nanocrystalline grains to be superplastic. Ceramics based on silicon nitride (Si3N4) and silicon carbide (SiC), have been used in automotive applications as high-strength springs, ball bearings, and valve lifters, and because they possess good formability and machinabilty combined with excellent physical, chemical, and mechanical properties. They are also used as components in high-temperature furnaces.
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Better insulation materials. Aerogels are nanocrystalline porous and extremely lightweight materials and can withstand 100 times their weight. They are currently being used for insulation in offices, homes, etc. They are also being used as materials for "smart” windows, which darken when the sun is too bright and they lighten themselves otherwise.
Exercise 5. Read the text about NanoRobotics. Tell about Robotics, NanoRobotics, and Nanomanipulator. Pick up as much devices mentioned in the text as possible (about 15).
Mind the gap - nanotechnology robotics vision versus lab reality
Science fiction style robots like Star Wars' R2-D2 or the NS-5 model in “I, Robot” firmly belong into the realm of Hollywood – and so do "nanobots" à la Michael Crichton's Prey. Staying with both feet firmly on scientific ground, robotics can be defined as the theory and application of robots, a completely self-contained electronic, electric, or mechanical device, to such activities as manufacturing. Scale that robot down to a few billionth of a meter and you are talking nanotechnology robotics; nanorobotics in short. The field of nanorobotics brings together several disciplines, including nanofabrication processes used for producing nanoscale robots, nanoactuators, nanosensors, and physical modeling at nanoscales. Nanorobotic manipulation technologies, including the assembly of nanometer-sized parts, the manipulation of biological cells or molecules, and the types of robots used to perform these tasks also form a component of nanorobotics. One day automated and self-contained molecular assemblers will be not only capable of building complex molecules but build copies of themselves – "self-replication" – or even complete everyday products.
Nanotechnology robots are NEMS (nanoelectromechanical systems) and raise all the important issues that must be addressed in NEMS design: sensing, actuation, control, communications, power, and interfacing across spatial scales and between organic and inorganic materials. Due to their size, comparable to biological cells, nanorobots have a vast array of potential appplications in fields such as environmental monitoring or medicine.
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The positioning of nanorobots and nanorobotic manipulators depends largely on nanoactuators, i.e. nanoscale devices that create mechanical motion by converting various forms of energy to rotating or linear mechanical energy.
Atomic Force Microscopes, Scanning Tunnelling Microscopes as well as other Scanning Probe Microscopes and optical and magnetic tweezers are now used extensively for positional and force control at the nanoscale. This process is called nanomanipulation. A nanomanipulation system generally includes nanomanipulators as the positioning device, microscopes as 'eyes', various end-effectors including probes and tweezers among others as its 'fingers', and types of sensors (force, displacement, tactile, strain, etc.) to facilitate the manipulation and to determine the properties of the objects.
Three basic types of nanomanipulation processes are performed: Lateral non-contact nanomanipulation (sliding); lateral contact nanomanipulation (pushing/pulling); and vertical nanomanipulation (picking and placing). The choice of which process to use is dependant on the environment (air, liquid, vacuum), the properties and size of the objects and the observation methods.
Exercise 6. Translate the sentences using the words of this lesson.
1. Нанороботы размером всего 1-2 микрон, оснащенные бортовыми механокомпьютерами и источниками энергии, будут полностью автономны и смогут выполнять разнообразные функции, даже самокопирование. 2. На основе нанотрубок уже сейчас создают детали наномашин – подшипники, передачи. 3. Создание наномоторов на основе АТФ (универсального аккумулятора и переносчика энергии во всех биологических системах) позволит приводить в движение нанороботов, а развитие беспроводной лазерной связи позволит управлять ими и служить “энергопроводом”. 4. Меняя длину и порядок цепочек-полимеров, можно изменять прочность и эластичность пластмасс. Если добавить еще одно звено или ввести небольшое количество примесей, то у полимера появляются новые свойства. 5. Одни пластмассы по прочности сравнимы с самой лучшей сталью, другие эластичнее резины, третьи прозрачны, как хрусталь, но не разбиваются. 6. Одни пластмассы быстро разрушаются под действием тепла, другие способны выдерживать очень высокую температуру. 7. Зная все это, ученые на сегодняшний день создали сотни тысяч различных синтетических полимеров. 8. Автомобили будущего станут более комфортными и интеллектуальными, основанными на легких и прочных материалах, миниатюризации и новых энергетических установках. 9. Практически каждая деталь автомобиля может быть усовершенствована при помощи нанотехнологий. 10. Антифрикционные и противоизносные покрытия продлевают срок службы отдельных деталей. 11. Стекла с управляемыми оптическими свойствами регулируют освещенность салона автомобиля. 12. Toyota оснащает свои автомобили легким и прочным бампером с добавлением нанотрубок, а машины Kia и Hyundai ездят на экологичном водороде. 13. Пластиковые детали станут огнеупорными. 14. Умные, сверхмягкие рессоры сглаживают любые неровности дороги. 15. Благодаря нанотехнологиям мы получим самовосстанавливающиеся покрытия, искусственный интеллект – автопилот и краска с программируемым цветом.
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Exercise 7. Get ready to discuss the topic “Future nanorobot”.
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