Ceramic Matrix Composites (CMCs) represent a relatively new class of quasiductile
ceramic materials. They are characterized by carbon or ceramic fi bers embedded
in ceramic matrices (oxide or non - oxide) with comparatively low bonding
forces between the fi bers and the matrix. These weak intefaces, in combination
with a porous and/or microcracked matrix, result in composite materials which
differ from all other structural materials or composites and show some outstanding
properties. Their strain - to - failure is up to one order of magnitude higher than
in monolithic ceramics and their low densities result in mass - specifi c properties
which are unsurpassed by any other structural material beyond 1000 ° C.
From their research beginnings about 40 years ago, the demands of space technology
played the decisive role in the development of CMCs. Hot structures of
limited lifetime (e.g. thermal protection systems, nozzles) in aerospace and military
applications have been developed in different countries. In recent years, civil
and terrestrial requirements became the driving forces and properties and manufacturing
processes were consistently improved to transfer CMCs from niche
applications to broader markets. Due to their high thermal stability and good corrosion
and wear resistance, these composite materials are of increasing interest
for long - term applications and damage - tolerant structures in different industrial
sectors like ground transportation (e.g. brake and clutch systems), mechanical
engineering (e.g. bearings, ballistic protections), and power generation (e.g.
burners, heat exchangers).
The goals of further research and development are focused on improvements
in the thermal and oxidative stability of the reinforcing fi bers and on a considerable
reduction of the processing costs. Reasonable costs for series productions are
expected by using innovative continuously operated furnaces as they already exist
for other structural (monolithic) ceramics. Also, new forming processes for the
manufacture of green bodies and new hybrid processes of high reliability are necessary.
Beside these fabrication approaches, novel precursors for cheaper ceramic
fi bers and improvements in the thermomechanical properties of short - fi ber reinforced
CMCs are key factors to develop CMC materials for wider application.