Environmental Engineering Reference
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Fig. 3 Manufacturing steps for ceramic fibers employing the preceramic polymer route. Reprinted
with permission from Flores et al. 2014 . Copyright 2014, John Wiley and Sons
production conditions. An important requirement key for the production of a
polymer-derived ceramic
fiber is a homogeneous and defect-free microstructure,
which allows high tensile strength. Their creep resistance and thermal resistance are
primarily determined by the stoichiometry and, speci
cally, the oxygen content.
Generally, polymer-derived ceramic
fibers with lower oxygen content have better
high temperature stability and creep resistance.
2.1.2 Polymer-Derived SiC Fibers
Over the course of the last 50 years, research in the
field of polymer-derived
ceramic
fibers has led to the development of three generations of high-performance
ceramic SiC
fibers with diameters <30
µ
m based on organometallic polymers.
Although the base of these
fibers is SiC, typical properties of crystalline SiC, such
as Young
'
s modulus of about 400 GPa and oxidation resistance up to 1,600
°
C,
were not realized in the
bers.
Continued research and development have led to the commercialization of two
more generations of SiC
first generation of commercialized ceramic SiC
fibers, with the most advanced third-generation
bers
showing thermal properties approaching those of crystalline SiC.
In the
first generation,
the SiC
fibers achieved suf
cient
tensile strengths
(>2 GPa) to reinforce matrices, but both Young
'
s modulus (
200 GPa) and thermal
*
stability were signi
cantly lower than in crystalline SiC ceramics due to the
formation of an amorphous Si
O
C phase in the
fiber at the typical pyrolysis
-
-
temperature of about 1,200
°
C. The
first company to introduce continuous polymer-
derived ceramic SiC
fibers in the market was Nippon Carbon Corporation Ltd,
Japan. Based on the work done by Yajima in the development of organosilicon
polymers, Nippon launched the trade name Nicalon, which is the family name of
three grades (Nicalon, Hi-Nicalon, and Hi-Nicalon Type S) of SiC
fibers. First-
generation Nicalon TM
fibers are produced from melt spinnable polycarbosilane
(PCS). Polymeric
fibers are spun from the polycarbosilane (PCS) melt at 350
°
C
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