Me1d02 Products and Materials in Modern Society with English Writing Requirements

...

- Thermal Properties

Carbon nanotube have been a good heat conductor, because of its small size and the low-temperature specific heat and thermal conductivity show direct evidence of 1-D quantization of the phonon band structure. At room temperature, the thermal conductivity of carbon nanotube is larger than graphite; it is over 200 W/m K for the samples of SWNT and over 3000 W/m K for a MWNT. It has been shown that the carbon nanotube may be useful for a thermal management application. Also, it can endure about over than 2000K.

- Electrical Properties [pic 6]

Since carbon is a non-metal conductor, the carbon nanotube might become a good electrical conductor. A band gap of carbon nanotube is between 0.5 and 3.5 eV. The band gap varies inversely with the diameter of the nanotube, such as a nanotube with 1nm diameter; the band gap is about 1 eV. In addition, a Carbon nanotube contain numerous electrons, it can provide enough energy for the electrons pass though the band gaps.

For a band gap is less than 1.8 eV it may contain a full absorption of light. Also the band gap is enough for absorb the microwave, and the visible light.

- Chemical Properties

Regarding the structure of carbon nanotube, it not only have a giant covalent bond, but also the nanotube may form a cap or cone sharp at the end of the tube, so that there are no any dangling bonds in the nanotube, and give a high steady chemical properties. Compared with other nanoparticle, carbon nanotube is more difficult to sintering or Atomic migration.

- Other Properties and short summary of properties

According to the article [4], With regard to the carbon nanotube, it is a safe material, because the size of the gap is constraining the virus pass though. In addition, as a stable chemical material, can reduce the chemical reaction with other material, if it is not a stable chemical material, it may appear a lot of negative effect or disaster, and such as the calcium being added in the water may cause an explosion.

According the above properties, it is found that carbon nanotube is a close to a prefect material in the world. This is because it can provide a high tensile strength, high ability to withstand heat, good electrical conductor and so on.

As a high tensile strength material, it may not be easy deformed. As for the manufacturing process, there is no need to add more hardening process on the material, so that can reduce the price in the hardening and repair cost.

For a good electrical conductor, it can provide a small area of electrical circuit; because the carbon nanotube is very tiny, that can be reduce the wrapping on the wire.

Development and Current Application

- Carbon nanotube apply on Composite material

Carbon nanotubes provide high mechanical properties such as high tensile strength, low density and high stability with other material. When a composite material is producing, a fine crack usually appears on the material. The crack may affect the lifetime of that material. [pic 7]

Therefore, materials that have a carbon nanotube treatment can provide high mechanical properties. This is because the carbon nanotube can have equilibrium distribution in the material. Also carbon nanotubes provide a high surface area, so that each particle construct closely with each other.

Carbon nanotube also can become the material for an electromagnetic shield and microwave absorption material. The Electromagnetic shield is using in blocking the radiate waste produced by the mobile phone, Radio tower and so on. This is because carbon nanotube contains high electrical properties that mentioned before. Also the properties can apply on the military technology, such as Stealth fighter.

- Carbon nanotube apply on energy storage

Carbon nanotube may apply in storing the energy; the carbon nanotube can be a hydrogen storage material. Since hydrogen is one of dangerous and unstable element, so that it should have a safe method for storing the hydrogen, so that using a stable material likes the carbon nanotube. The carbon nanotube also provide a high strength for inventing a high-pressure environment for storing hydrogen.[2]

In addition, the carbon nanotube can be upgrading the performance of a lithium battery, no matter whether it is storing capacity or charging speed. For the structure of lithium battery, a lithium layer as anode and other electrical conducting material as cathode layer, as the Figure 4. If the distance of separation between each lithium layer is small and without contact, it may provide more energy, the separation is depended on the thickness of the cathode layer. The thickness of Carbon nanotube is 0.347nm. Also, Graphite is the major material that marking cathode layer of Lithium battery that we currently use. However, graphite is an irregular structure material. As the carbon nanotube has a formatted structure that is an advantage for embedding into lithium atom, also to reduce the flaking of cathode layer.[pic 8]

- Carbon nanotube apply on electrical component

Carbon nanotube can provide a high sensitivity pressure sensor. Since the carbon nanotubes have high reformation ability, after an external force act on the nanotube, it may affect the current flow in the nanotube. After the force is release, the nanotube may reformat instantaneously and the current flow becomes normal again. In this process, it can make a high sensitivity sensor; the sensor can apply in the spacecraft, or security area.

Moreover, carbon nanotube can improve the electrical microscope probe for scan the human body or product. For the original microscope probes are blunt, different to check the slit on the surface of sample and easy to damage the sample. Therefore, the carbon nanotubes have a short diameter, which can travel the narrow slit smoothly. When the probe contact with the surface of sample, the carbon nanotube can bend and would not damage the surface and the probe itself.

- Carbon nanotube apply on Military

Some research found that, when Carbon nanotube place on Vinyl alcohol, it can have a light blocking ability. So that, the carbon nanotube can make some better optical sensor, also can be a material for heat emitter. In these optical properties, the carbon nanotube can become a stealth material. For example, we can use carbon nanotube paint on the surface of Stealth Fighters. [pic