JEC COMPOSITES MAGAZINE - Issue #147 - September/October 2022 - 52

52
TECHNOLOGY ceramic
Cerapreg - a new concept for
cost-effective reinforced ceramic composites
CHRISTOPH HOFER, Senior Business Development Manager
KATHARINA SLANAR, Group Marketing
DR. PETER WAGNER, Senior Technology Manager
KONSTANTIN HOREJSI, Vice President Technology
Isovolta AG
For several decades now, fi bre-reinforced composites have
established themselves as a lightweight, easily mouldable
alternative to metallic designs. Especially when used in prepreg form,
fi bre-reinforced composites combine repeatable quality, remarkable
stiffness-to-weight ratios and a high degree of design freedom with
highly cost-effective tooling, which makes them a clear choice for
performance-oriented, small-series production industries such as
aircraft, space technology and high-end cars.
C
onventional polymer-based composites have a major drawback limiting
their application: standard thermoset composites (based on
phenolics and epoxy resins) usually fail at around 250°C and more
niche high-temperature products (such as PEEK and cyanate esters)
provide continuous-use temperature stability up to 350°C, but involve
a signifi cant cost increase. Ceramic composites are available for specifi c
ultra-high-performance applications such as brake discs and space heat
shields, but they usually provide temperature stability in the 1000°C+
range at a signifi cant cost premium, leaving the temperature range from
~350°C to ~1000°C almost exclusively to metallic substrates. Th is paper
presents a new development for a cost-eff ective ceramic prepreg, directly
targeting current metallic solutions at elevated temperatures.
Advantages and limitations
of ceramic-matrix composites
A cost-eff ective ceramic prepreg is rather challenging to create since the
raw materials are more expensive than their metallic counterparts. While
some economic benefi t can be lift ed from lower processing and tooling
costs, the main concern still exists.
Raw materials
Oxide-ceramic matrix substrates are usually created as a blend between
aluminium oxide (AL2
O3) and silicon dioxide (SiO2
). While aluminium
oxide provides higher mechanical values and higher temperature resistance,
it is unfortunately a more expensive raw material. It also needs to
sinter at temperatures above 1100°C, making the process more expensive
and damaging the fi bre reinforcements. Silicon-based matrix systems allow
for relatively low-cost systems, which are also robust during the subsequent
processing and moulding steps, but have low mechanical stiff ness.
Fibres
Silica and aluminium fi bres are the common standard, while carbon fi -
bre reinforcements are used in niche applications. Silica fi bres are cost
eff ective and easier to impregnate, as they are closely related to standCeramic
Cerapreg
- a new concept for
cost-effective reinforced ceramic composites
Comparison of several key
parameters for different fi bre
reinforcements
52
jec composites magazine / N°
147 September - October 2022
TECHNOLOGY
JEC COMPOSITES MAGAZINE - Issue #147 - September/October 2022

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