Ceramic and Glass Materials

J.F. Shackelford and R.H. Doremus (eds.), Ceramic and Glass Materials: 1

Structure, Properties and Processing.

© Springer 2008

Chapter 1

Alumina

Robert H. Doremus

The uses, processing, structure, and properties of alumina are summarized in this arti-

cle. Various polymorphs of alumina and its phase relations with other oxides are

described. The following properties are discussed: mechanical, thermal, thermody-

namic, electrical, diffusional, chemical, and optical. Quantitative values for these

properties are given in tables. The usefulness of alumina results from its high strength,

melting temperature, abrasion resistance, optical transparency, and electrical resistiv-

ity. Traditional uses of alumina because of these properties are furnace components,

cutting tools, bearings, and gem stones; more recent applications include catalyst

substrates, tubes for arc lamps, and laser hosts. Possible new uses of alumina are in

electronic circuits, optical components, and biomaterials. Alumina fibers for compos-

ites and optics must be pure, defect free, and cheap.

1 Introduction

Alumina (Al 2 O 3 ) is one of the most important ceramic materials, both pure and as a
ceramic and glass component. Some uses of alumina are given in Table 1; an exhaustive
and detailed description of many of these uses is given in [1]. There are also extensive dis-
cussions of uses of alumina in [2]. Processing of alumina is discussed in both these refer-
ences, and [2] has a summary of some properties of alumina. In writing this review, I have
relied on material from these references. Anyone interested in more details of processing
and properties of alumina should obtain [2] from the American Ceramic Society. Reference
[1] is also available from the Society and has additional information on processing and
uses of alumina. More recently, there have been two issues of the Journal of the American
Ceramic Society devoted to alumina [3, 4]; these issues concentrate on defects and inter-
faces, especially grain boundaries [3], grain growth, and diffusion in alumina [4].
The usefulness of alumina derives from a variety of its properties. It has a high
melting temperature of 2,054°C, and is chemically very stable and unreactive,
leading to applications as high-temperature components, catalyst substrates, and
biomedical implants. The hardness, strength, and abrasion resistance of alumina
are among the highest for oxides, making it useful for abrasive materials, bearings,