Materials Science and Engineering of Carbon: Fundamentals

Michio Inagaki, Feiyu Kang

• Publisher: Butterworth-Heinemann
• Year: 2014
• Print ISBN: 9780128008584
• eBook ISBN: 9780128011522
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Materials Science and Engineering of Carbon: Fundamentals provides a comprehensive introduction to carbon, the fourth most abundant element in the universe. The contents are organized into two main parts. Following a brief introduction on the history of carbon materials, Part 1 focuses on the fundamental science on the preparation and characterization of various carbon materials, and Part 2 concentrates on their engineering and applications, including hot areas like energy storage and environmental remediation. The book also includes up-to-date advanced information on such newer carbon-based materials as carbon nanotubes and nanofibers, fullerenes and graphenes.- Through review on fundamental science, engineering and applications of carbon materials- Overview on a wide variety of carbon materials (diamond, graphite, fullerene, carbon nanotubes, graphene, etc.) based on structure and nanotexture- Description on the preparation and applications of various carbon materials, in the relation to their basic structure and properties

Chapter 1

Introduction

The concept of carbon materials is presented by explaining a brief history of carbon materials through the classification into classic carbons, new carbons and nanocarbons. Construction and purposes of the present book is explained.

Keywords

Carbon materials; classic carbons; new carbons; nanocarbons

1.1 Carbon materials

Carbon C is one of the abundant elements on the Earth, because almost all organics are composed from carbon networks, and it is very familiar in our daily lives, for example, ink for newspapers, lead for pencils, activated carbons in refrigerators, etc. Carbon materials, which consist mainly of carbon atoms, have been used since prehistoric era as charcoal. In Japan, a large amount of charcoal (about 800 tons) was reported to be used for casting a great image of Buddha in Nara from 747–750. Soft graphite has been used for a long time as lead and carbon blacks as black inks. Diamond crystals are fascinating for all human beings not only as jewels but also the hardest materials were found to consist of carbon atoms, the same atoms as lubricating soft graphite in 1799. Nowadays various carbon materials are used in our daily lives, though many of them are inconspicuous; activated carbon produced from coconut shells for a filter of tobacco, carbon fibers for reinforcement of rackets and fishing rods, leads for automatic pencils, activated carbons for deodorization in refrigerators, membrane switches composed of graphite flakes for keyboards of computers and various instruments, etc. Charcoal may be the first carbon material used practically, as it has been used since the pre-historic age. Carbon materials started to be used as electrodes for batteries around 1800. Since 1878, large-sized carbon rods were used as electrodes for iron refining, which were industrially produced by heat treatment at high temperatures (as high as 3000°C) and called graphite electrodes because crystalline graphite structure was well developed in most of them. Later on, various carbon materials having graphitic structure for various applications were developed, which were called graphite materials, even though the development of graphitic structure is not complete. At the same time, carbon materials without noticeable graphite structure, such as charcoal, were also developed and opened new applications.

There was no clear definition and no clear-cut classification on what graphite materials are and what carbon materials are. In the present book, however, we will use the term ‘carbon materials’ for materials composed predominantly of carbon element, irrespective of their structure, so including fullerenes and carbon nanotubes, and also the terms either ‘carbon materials’ or ‘carbons’ for the materials without three-dimensional graphite structure. On the other hand, ‘graphite materials’ and sometimes ‘graphites’ were used for the materials which have three-dimensional graphite structure, even partly. In industry, the term ‘graphite’ and ‘graphitized’ are often used, even though graphite structure is not developed appreciably; for example PAN-based carbon fibers heat-treated at a high temperature used to be called ‘graphite fibers’, even though almost no graphite structure was developed, as will be explained later in detail.

Polycrystalline graphite materials have been used in various fields of industries using their different properties. Their characteristics can be summarized as follows; (1) high thermal resistance in non-oxidizing atmosphere, (2) high chemical stability, (3) high electrical and thermal conductivities, (4) small thermal expansion coefficient and, as a consequence, high thermal shock resistance, (5) very light weight, (6) high mechanical strength at high temperatures, (7) high lubricity, (8) highly reductive at high temperatures and easily dissolved into iron, (9) non-toxic, (10) radiation resistance, and (11) low absorption cross-section and high moderating efficiency for neutron.

Since all polycrystalline graphite materials consist of parallel stacking of carbon hexagonal layers, like graphite, which are called crystallites, their properties of a bulk material are strongly governed by different factors, such as how large the crystallites are, how these anisotropic crystallites orient in the bulk, to what temperature they were heat-treated, etc. The preferred orientation of crystallites in bulk graphitic materials depends strongly on the condition of forming process and the heat treatment temperature governs the size and perfection of the structure. Therefore, most of the properties of carbon materials distribute in a wide range. In Fig. 1.1, electrical conductivity, bulk density, thermal expansion coefficient (expansivity), and tensile strength are compared for different carbon materials, including natural graphite, various fibrous carbon materials, and graphite intercalation compounds (GICs).

Figure 1.1 Range of various properties of carbon materials.

Polycrystalline graphite is a good electric conductor, but its electrical conductivity of roughly 2×10⁵ S/m is inferior to metals. By intercalation of different species into the interlayer spaces of graphite, however, electrical conductivity is much improved and becomes even higher than that of metallic copper. Thermal expansion coefficient of graphite single crystal is very high along the c-axis (perpendicular to the graphite layer plane), but negative (i.e., shrinkage) along the a-axis (parallel to the layer). In polycrystalline graphite materials, this anisotropy in thermal expansion is spaciously averaged, depending strongly on the size and arrangement of crystallites (i.e., structure and texture). In fibrous carbons, it is mainly governed by expansion along the layer planes and so rather small values. In most of physical properties, such as electrical and thermal characteristics, the highest and the lowest values are realized in the directions perpendicular and parallel, respectively, to graphite layers, as shown on the electrical conductivity and thermal expansion coefficient in Fig. 1.1. Mechanical properties, such as tensile strength, and bulk density are texture-sensitive characteristics and so they show a wide range of values, in general. The practical values for various carbon materials including polycrystalline graphite materials (high-density isotropic graphite and graphite electrodes) are inferior to the theoretical values for graphite single crystal, because of their polycrystalline nature.

1.2 Short history o...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Acknowledgments
• Chapter 1. Introduction
• Chapter 2. Fundamental Science of Carbon Materials
• Chapter 3. Engineering and Applications of Carbon Materials
• Index