Page 172 - Fiber Fracture

Fiber Fracture
M. Elices and J. Llorca (Editors)
0 2002 Elsevier Science Ltd. All rights reserved

FRACTURE OF CARBON FIBERS

J.G. Lavin

Carbon Nanotechnologies Inc., 16200 Park Row, Houston, TX 77084, USA

Introduction ..................................... 158
Physical Properties ................................. 159
PAN-Based Carbon Fibers ............................. 163
Pitch-Based Carbon Fibers ............................. 166
General Purpose Pitch-Based Carbon Fiber .................. 166
High-Performance Pitch-Based Carbon Fibers ................. 167
A Paradox ................................... 169
Fiber Formation ................................ 169
Vapor-Grown Carbon Fibers ............................ 173
Failure Mechanisms ................................. I74
Tensile Failure ................................. 174
Compressive Failure .............................. I75
Concluding Remarks ................................ 178
References ...................................... 178

Abstract

Carbon fibers are made from many different feedstocks. The most important com-
mercial fiber is made from polyacrylonitrile (PAN). It is four times stronger than steel,
the same modulus or higher, and does not fail in creep or fatigue. These properties made
the fiber attractive for aerospace applications initially, and later for sporting and indus-
trial applications. Another important feedstock is pitch from refinery or steel-making
operations, which leads to fibers with very high modulus and thermal and electrical con-
ductivities. Properties of the fibers, and critical steps in their manufacture are described,
together with structural characteristics and failure mechanisms.

Keywords

Carbon; PAN; Mesophase pitch; Electrical conductivity; Thermal conductivity; SEM;
TEM