Precision Engineering 28 (2004) 16–30 Nanotechnology and nanostructured materials: trends in carbon nanotubes A.G. Mamalis a,∗ , L.O.G. Vogtländer b , A. Markopoulos a a Department of Mechanical Engineering, Manufacturing Technology Division, National Technical University of Athens, 9 Iroon Polytechniou Avenue, Athens 15780, Greece b Department of Mechanical Engineering, Production Technology and Organisation Division, Delft University of Technology, Delft, The Netherlands Received 13 June 2002; received in revised form 25 October 2002; accepted 20 November 2002 Abstract Carbon nanotubes have attracted the attention of many researchers since their discovery last decade. These carbon molecules are tiny tubes with diameters down to 0.4nm, while their lengths can grow up to a million times their diameter. Using their remarkable electrical properties, simple electronic logic circuits have been built. These structures are promising for the semiconductor industry which is leading the search for miniaturisation. They are not only very good conductors, but they also appear to be the yet found material with the biggest specific stiffness, having half the density of aluminium. This paper is written to give a consolidated view of the synthesis, the properties and applications of carbon nanotubes, with the aim of drawing attention to useful available information and to enhancing interest in this new highly advanced technological field for the researcher and the manufacturing engineer. © 2003 Elsevier Inc. All rights reserved. Keywords: Nanotechnology; Nanostructured materials; Carbon nanotubes 1. Introduction Nanotechnology is considered to be the technology of the future, it is perhaps today’s most advanced manufacturing technology and has been called “extreme technology”, be- cause it reaches the theoretical limit of accuracy which is the size of a molecule or atom. In manufacturing industry, two interrelated trends are clearly seen: the trend towards minia- turisation and the trend towards ultra-precision processing. Both trends are moving in the direction of nanotechnology, because both are tending to dimensions which lie in the range of several nanometres. Nanotechnology deals with materials and systems having the following key properties [1]: • they have at least one dimension of about 1–100 nm; • they are designed through processes that exhibit funda- mental control over the physical and chemical attributes of molecular-scale structures; • they can be combined to form larger structures. ∗ Corresponding author. Tel.: +30-1-772-3688; fax: +30-1-772-3689. E-mail address: mamalis@central.ntua.gr (A.G. Mamalis). Taniguchi introduced the term ‘nanotechnology’ in 1974 to describe the manufacturing of products with tolerances less than 1 m [2]. However, Feynman, who won the No- bel prize in 1965, claimed in his talk “There’s plenty of room at the bottom” in 1959, that “... almost any chemi- cally stable structure, that can be specified, can in fact be built ... ” [3]. He introduced the concept of building with molecules, “bottom-up” manufacturing, in contrast with the “top-down” manufacturing, we are familiar with. The pi- oneering work of Drexler in molecular nanotechnology is important here; in his popular books “Engines of creation” (1986) and “Nanosystems” (1992) he described nanoscale “assembler”-robots which build structures molecule by molecule and even replicate themselves [4,5]. To image these tiny structures, special microscopes are needed. Scanning electron microscopes image structures by analysing the scattered electrons on a substrate by computer. Scanning probe microscopes use extremely sharp probes with tips of radius about 10 nm to scan the surface. The scanning tunnelling microscope measures a tunnelling current which occurs when the tip is about 1 nm above the surface and a volt- age is applied; the current is held constant by moving the tip vertically while scanning the surface. The restriction that the substrate has to be an electrical conductor, led to the inven- 0141-6359/$ – see front matter © 2003 Elsevier Inc. All rights reserved. doi:10.1016/j.precisioneng.2002.11.002