[nanoPost] Carbon Cones

As their name suggests, carbon cones are hollow structures exclusively made of carbon and having a conical shape.

Apart from their geometry, these materials are very similar in structure to multi-wall carbon nanotubes. Their walls can be described as a stacking of conical carbon layers with a graphite-like structure.

Carbon cones have well defined angles. Only five different types of cones - with angles close to 19.2, 38.9, 60, 84,6 and 112,9 degrees - are indeed theoretically possible. All are present in the company's samples.

The carbon cones marketed by the company have characteristics halfway between the micrometer and the nanometer scale. Their length ranges from 300 to 800 nm while the thickness of the walls typically varies from 20 to 50 nm. The maximum base diameter is around 1-2 microns

As produced, carbon cones are mixed with other carbon materials: carbon discs. With diameters ranging from 0.8 to 3 microns and a thickness around 20–50 nm, they can be considered as quasi 2D-materials. As such, carbon discs have also to be regarded as a material with high potential in terms of applications.

The unique composition and structure of the carbon cone/carbon disc material will very likely result in unprecedented electronic, chemical and mechanical properties and open up unique applications in various areas

Production Method

Carbon cones are produced by pyrolysis of hydrocarbons using an exclusive torch plasma process patented by a partner company.

Applications of carbon cones

The unique composition and structure of the carbon cone/carbon disc material will very likely result in unprecedented electronic, chemical and mechanical properties and open up unique applications in various areas

Experiments conducted by the company have already demonstrated the potential of carbon cones as additives for conductive plastics.

Structure

Carbon tubes can be described as graphitic sheets rolled up into a tubular form. They come in two varieties:

- single-wall nanotubes (SWNT) which consists of a single cylindrical sheet

- multi-wall nanotubes (MWNT) which are made up of several concentric sheets (from two to several tens).

The nanotubes produced by the company are exclusively multi–wall nanotubes generated by the arc method which gives the highest quality material. Their diameter ranges from 5 to 50 nanometers (average ca. 20 nm) – around 10 000 times thinner than a human hair.

Physical Properties

Carbon nanotubes are the strongest material known – about 10 times stronger than steel at one sixth the weight.

Due to their structure, carbon nanotubes not only can withstand very high mechanical stress but also show remarkable flexibility. They can withstand elongations corresponding to 20-30 % of their initial length and can be bent through large angles without damage.

Production Method

The company has chosen the arc-discharge method because it allows the production of carbon nanotubes with the best mechanical and transport properties.

Applications of carbon nanotubes

Composite materials

The unique combination of properties observed in carbon nanotubes offer great potential for the development of new classes of composite materials with unprecedented mechanical, electrical and thermal properties.

Below are listed some of the potential fields of applications:

High-strength / High-modulus composite materials

With a tensile strength of 60 GPa and an elastic modulus of 1.25 TPa, carbon nanotubes can be considered as the ultimate reinforcement fiber. They have the potential of significantly improving the mechanical properties of polymers in which they are incorporated, expanding the use of these lightweight materials in structural applications usually restricted to more robust materials.

Potential applications are in the field of aerospace, automotive, telecommunication, medical and sporting goods industries.

Conductive plastics – EMI/ESD shielding

This heading covers a wide range of applications including antistatic, electrostatic dissipative (ESD) and electromagnetic shielding (EMI).

Polymers and plastics are intrinsically insulators. For some applications, additives are used to create conductive pathways in polymers in order to make them conductive. The disadvantage of the additives currently used is that relatively high loadings are required to provide the desired level of conductivity, which can result in important degradation of the mechanical properties of the polymer.

Due to their high aspect ratio (length/diameter) and excellent electrical conduction characteristics, much lower loadings are required with carbon nanotubes. As a result, it is now possible to get high levels of conductivity while preserving the properties of the polymers.

Thermal management

Due to the miniaturization and increasing power of microelectronics, there is a growing demand for materials for thermal management. The requirement is not just high thermal conductivity but low coefficient of thermal expansion (CTE) as well. It is indeed important that the different components of the thermal management system expand at the same rate as their support and the components they are cooling down.

With low CTE and good thermal conductivity, nanotube-based polymers offer an attractive option to current materials

Multi-functional composites

Versatility is the word best describing the properties of carbon nanotubes. Incorporation of carbon nanotubes is an efficient way to improve simultaneously the mechanical, electrical and thermal properties of a material without resorting to several additives.

Other applications:

Carbon nanotubes have prompted intense research in a wide variety of disciplines ranging from biology to physics. A complete enumeration of all possible applications would go beyond the scope of this website. The list below is only a sample of promising applications:

Energy storage

Nanotubes have the intrinsic characteristics desired in material used as electrodes in batteries and capacitors: high surface area and good electrical conductivity.

Catalyst support

Carbon materials already represent an important class of catalyst supports used in a number of industrial processes. Nanotubes are a promising option to the existing support material. Their properties may be exploited in the search for new catalysts and catalytic behavior.

Flat-screen displays

The ability of nanotubes to emit electrons when exposed to an electric field make them particularly suitable for building a new generation of flat-screen displays known as Field Emission Displays (FED). The main difference with conventional displays is that each single pixel is illuminated by its own electron source, made of thousands of nanotubes. Such displays can be paper thin.

Molecular electronics

Their geometry and electrical conductivity make carbon nanotubes the ideal candidates for the connections in molecular electronics. In addition, their potential as building blocks for nanoscale devices such as transistors has already been demonstrated.

Nanoprobes and sensors

Nanotube-based sensors are a rapidly growing field of research. Applications include biological and chemical sensors for precision analysis or detection, medical diagnostic kits and so on.

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