Fundamentals of Materials Science and Engineering: An Integrated Approach, 3e

P1: PBU/OVY P2: PBU/OVY QC: PBU/OVY T1: PBU Printer: Yet to Come
GTBL042-01 GTBL042-Callister-v2 July 24, 2007 22:10

8 • Chapter 1 / Introduction

Electrical Conductivity (in units of reciprocal

ohm-meters) (logarithmic scale)

108

104

1

10 –12

10 –8

10 –4

10 –16

10 –20

Ceramics Polymers

Semiconductors

Figure 1.7 Metals

Bar-chart of

room-temperature

electrical

conductivity ranges

for metals, ceramics,

polymers, and

semiconducting

materials.

to fracture (Figure 1.6). These materials are typically insulative to the passage of

heat and electricity (i.e., have low electrical conductivities, Figure 1.7), and are more

resistant to high temperatures and harsh environments than metals and polymers.

With regard to optical characteristics, ceramics may be transparent, translucent, or

opaque (Figure 1.2), and some of the oxide ceramics (e.g., Fe 3 O 4 ) exhibit magnetic

behavior.

Several common ceramic objects are shown in the photograph of Figure 1.9. The

characteristics, types, and applications of this class of materials are also discussed in

Chapter 13.

Polymers

Polymers include the familiar plastic and rubber materials. Many of them are organic

compounds that are chemically based on carbon, hydrogen, and other nonmetallic

elements (viz. O, N, and Si). Furthermore, they have very large molecular structures,

often chain-like in nature with a backbone of carbon atoms. Some of the common

Figure 1.8 Familiar

objects that are

made of metals and

metal alloys (from

left to right):

silverware (fork and

knife), scissors,

coins, a gear, a

wedding ring, and a

nut and bolt.

(Photography by S.

Tanner.)