02-05-2011, 10:16 AM
PRESENTED BY:
NIDHIN EAPEN MATHEW
[attachment=13191]
CARBON NANOTUBES IN MANUFACTURING INDUSTRY
Abstract
Carbon nanotubes (CNTs) have many unique physical, mechanical, and electronic properties. These distinct properties may be exploited such that they can be used for numerous applications ranging from sensors and actuators to composites. As a result, in a very short duration, CNTs appear to have drawn the attention of both the industry and the academia. However, there are certain challenges that need proper attention before the CNT based devices can be realized on a large scale in the commercial market. This report describes the distinct physical, electronic, and mechanical properties of nanotubes. The basics of synthesis and purification of CNTs are also reviewed. The challenges associated with CNTs, which remain to be fully addressed for their maximum utilization in current and future application had been discussed.
1 INTRODUCTION
Over the past 15 years, Carbon Nanotubes have evolved into one of the most important study material in this decade. Carbon Nanotubes are cylindrical shape carbon molecules found from the allotrope of carbon. Because of its cylindrical shape, carbon molecules have good novel properties that make them potentially useful in a wide variety of applications. CNT also exhibits extraordinary strength and unique electrical properties, and are efficient conductors of heat.
The term nanotube is normally used to refer to the carbon nanotube. A nanotube is a member of the fullerene structural family with a diameter of few nanometers and length up to several millimeters. It is named according to its size, a nanotube is in cylindrical form with at least one end typically capped with a hemisphere of the buckyball structure. There are two main types of nanotubes, classified according to its structure: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).
The process of manufacturing a nanotube is based on applied quantum chemistry. The process is depending on orbital hybridization, in which entire nanotube molecules aligned themselves into "ropes" structure under Van Der Waals forces acting inside the nanotubes. It is due to the sp2 bonds inside the molecules. The presence sp2 bonds in the nanotube providing a unique strength to the structure.
1.1 Aim:
To evaluate and appraise the use of new and emerging technologies and their impact on the design, production, manufacturing and also justification for the implementation of the component
1.2 Objective:
The main objectives to be covered are as follows
• Explaining the material properties, related to chemical and physical structures
• Design considerations
• Production of the material
• Current and future applications
• Issues of costing
• Justification for the implementation
2 Theory
2.1 WHAT IS CARBON NANOTUBE
An important scientific discovery was made in carbon nanochemistry came in 1991 that Iijima and Coworkers found single walled nanotubes known as Buckytubes. Which are completely hollow molecules that are crafted from pure carbon and are bonded together in a hexagon pattern (Connell, 2006). This material became known as carbon nanotubes. Carbon nanotubes are wires of pure carbon with only a few nanometers (billionths of a meter) in diameter lengths of many microns. It consist of a single layer sheet of graphite rolled into a tube like structure in which both the ends are closed with C60 fullerene hemispheres.
Figure 1: Bent nanotubes. Courtesy of A. Rochefort, Nano-CERCA,University of Montreal, Canada
The discovery that carbon could form stable, ordered structures other than graphite and diamond stimulated researchers worldwide to search for other new forms of carbon. The search was given new impetus when it was shown in 1990 that C60 could be produced in a simple arc-evaporation apparatus readily available in all laboratories. It was using such an evaporator that the Japanese scientist Iijima discovered fullerene-related carbon nanotubes in 1991. The tubes contained at least two layers, often many more, and ranged in outer diameter from about 3 nm to 30 nm, which is invariably closed at both ends (Connell, 2006). There are two basic types of carbon nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Multi walled tubes (MWNTs) resembling many pipes nested within each other whereas single walled tubes (SWNTs) resemble a single pipe that is potentially closed at each end. The properties of both single walled and multi walled tubes are generally the same, although single walled tubes are believed to have superior mechanical strength and good thermal and electrical conductivity.
Figure 2: Schematic representation of rolling graphite to create a carbon nanotube. Source: image gallery Nanotechnology Team, NASA.
These are the stars of the nanotube world, and somewhat reclusive ones at that, being much harder to make than the multi-walled variety. A single-walled carbon nanotube (SWNT) is in the form of a single atomic layer of thick sheet of graphite (called graphene) rolled into a seamless tube and capped by half a fullerene (figure 2). The carbon atoms inside the SWNT structure are sp2 hybridized. According to the diameter and the chirality, SWNTs are classified. The single-wall carbon nanotubes that are using now days is produced by the process of pulsed laser vaporization method and vapor liquid solid catalyzed growth in case of large production. The physical properties of SWNTs have made them an extremely attractive material for the manufacturing of nano devices.
Figure 3: Structure Some SWNTs with different chirality. The difference in structure is shown at the open end of the tubes.
a) armchair structure b) zigzag structure c) chiral structure
Multi Walled Nanotubes (MWNT) is considered as a collection of concentric SWNTs with different diameters. The length and diameter of these structures differ a lot from those of SWNTs and their properties are different. Multi walled carbon nanotubes (MWNTs) range from double walled NTs, through many-walled NTs to carbon nanofibers, it consist of several concentric nanotube shells. SWNTs are more pliable than their multi-walled counter parts and can be twisted, flattened and bent into small circles or around sharp bends without breaking. By studying the electronic properties of the graphene sheets helps to understand the electronic properties of carbon nanotubes. However, when graphene is rolled up to make the nanotube, a special direction is selected, the direction along the axis of the nanotube. They can be conducting like metal such nanotubes are often referred to as metallic nanotubes or semiconducting, which means that the flow of current through them can be stepped up or down by varying an electrical field. Because of this, metals and semiconductors can make from the same all-carbon system. Many of the nanotube applications now considered or put into practice that involve multi-walled nanotubes, because they are easier to produce in large quantities at a reasonable price and have been available in decent amounts for much longer than SWNTs.
NIDHIN EAPEN MATHEW
[attachment=13191]
CARBON NANOTUBES IN MANUFACTURING INDUSTRY
Abstract
Carbon nanotubes (CNTs) have many unique physical, mechanical, and electronic properties. These distinct properties may be exploited such that they can be used for numerous applications ranging from sensors and actuators to composites. As a result, in a very short duration, CNTs appear to have drawn the attention of both the industry and the academia. However, there are certain challenges that need proper attention before the CNT based devices can be realized on a large scale in the commercial market. This report describes the distinct physical, electronic, and mechanical properties of nanotubes. The basics of synthesis and purification of CNTs are also reviewed. The challenges associated with CNTs, which remain to be fully addressed for their maximum utilization in current and future application had been discussed.
1 INTRODUCTION
Over the past 15 years, Carbon Nanotubes have evolved into one of the most important study material in this decade. Carbon Nanotubes are cylindrical shape carbon molecules found from the allotrope of carbon. Because of its cylindrical shape, carbon molecules have good novel properties that make them potentially useful in a wide variety of applications. CNT also exhibits extraordinary strength and unique electrical properties, and are efficient conductors of heat.
The term nanotube is normally used to refer to the carbon nanotube. A nanotube is a member of the fullerene structural family with a diameter of few nanometers and length up to several millimeters. It is named according to its size, a nanotube is in cylindrical form with at least one end typically capped with a hemisphere of the buckyball structure. There are two main types of nanotubes, classified according to its structure: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).
The process of manufacturing a nanotube is based on applied quantum chemistry. The process is depending on orbital hybridization, in which entire nanotube molecules aligned themselves into "ropes" structure under Van Der Waals forces acting inside the nanotubes. It is due to the sp2 bonds inside the molecules. The presence sp2 bonds in the nanotube providing a unique strength to the structure.
1.1 Aim:
To evaluate and appraise the use of new and emerging technologies and their impact on the design, production, manufacturing and also justification for the implementation of the component
1.2 Objective:
The main objectives to be covered are as follows
• Explaining the material properties, related to chemical and physical structures
• Design considerations
• Production of the material
• Current and future applications
• Issues of costing
• Justification for the implementation
2 Theory
2.1 WHAT IS CARBON NANOTUBE
An important scientific discovery was made in carbon nanochemistry came in 1991 that Iijima and Coworkers found single walled nanotubes known as Buckytubes. Which are completely hollow molecules that are crafted from pure carbon and are bonded together in a hexagon pattern (Connell, 2006). This material became known as carbon nanotubes. Carbon nanotubes are wires of pure carbon with only a few nanometers (billionths of a meter) in diameter lengths of many microns. It consist of a single layer sheet of graphite rolled into a tube like structure in which both the ends are closed with C60 fullerene hemispheres.
Figure 1: Bent nanotubes. Courtesy of A. Rochefort, Nano-CERCA,University of Montreal, Canada
The discovery that carbon could form stable, ordered structures other than graphite and diamond stimulated researchers worldwide to search for other new forms of carbon. The search was given new impetus when it was shown in 1990 that C60 could be produced in a simple arc-evaporation apparatus readily available in all laboratories. It was using such an evaporator that the Japanese scientist Iijima discovered fullerene-related carbon nanotubes in 1991. The tubes contained at least two layers, often many more, and ranged in outer diameter from about 3 nm to 30 nm, which is invariably closed at both ends (Connell, 2006). There are two basic types of carbon nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Multi walled tubes (MWNTs) resembling many pipes nested within each other whereas single walled tubes (SWNTs) resemble a single pipe that is potentially closed at each end. The properties of both single walled and multi walled tubes are generally the same, although single walled tubes are believed to have superior mechanical strength and good thermal and electrical conductivity.
Figure 2: Schematic representation of rolling graphite to create a carbon nanotube. Source: image gallery Nanotechnology Team, NASA.
These are the stars of the nanotube world, and somewhat reclusive ones at that, being much harder to make than the multi-walled variety. A single-walled carbon nanotube (SWNT) is in the form of a single atomic layer of thick sheet of graphite (called graphene) rolled into a seamless tube and capped by half a fullerene (figure 2). The carbon atoms inside the SWNT structure are sp2 hybridized. According to the diameter and the chirality, SWNTs are classified. The single-wall carbon nanotubes that are using now days is produced by the process of pulsed laser vaporization method and vapor liquid solid catalyzed growth in case of large production. The physical properties of SWNTs have made them an extremely attractive material for the manufacturing of nano devices.
Figure 3: Structure Some SWNTs with different chirality. The difference in structure is shown at the open end of the tubes.
a) armchair structure b) zigzag structure c) chiral structure
Multi Walled Nanotubes (MWNT) is considered as a collection of concentric SWNTs with different diameters. The length and diameter of these structures differ a lot from those of SWNTs and their properties are different. Multi walled carbon nanotubes (MWNTs) range from double walled NTs, through many-walled NTs to carbon nanofibers, it consist of several concentric nanotube shells. SWNTs are more pliable than their multi-walled counter parts and can be twisted, flattened and bent into small circles or around sharp bends without breaking. By studying the electronic properties of the graphene sheets helps to understand the electronic properties of carbon nanotubes. However, when graphene is rolled up to make the nanotube, a special direction is selected, the direction along the axis of the nanotube. They can be conducting like metal such nanotubes are often referred to as metallic nanotubes or semiconducting, which means that the flow of current through them can be stepped up or down by varying an electrical field. Because of this, metals and semiconductors can make from the same all-carbon system. Many of the nanotube applications now considered or put into practice that involve multi-walled nanotubes, because they are easier to produce in large quantities at a reasonable price and have been available in decent amounts for much longer than SWNTs.
