FP6 priority
1.1.3   Nanotechnologies and Nanosciences, Knowledge-based Multifunctional Materials and New Production Processes and Devices
Title of the proposal

Metal matrix composites for waste heat removing

Institute of Materials and Machine Mechanics of the Slovak Academy of Sciences,
Racianska 75, 831 02 Bratislava, Slovak Republic
+421 2 49268218

Research subject for a potential FP6 project

Metal matrix composites are of interests for applications in many parts of industry where waste heat is generated. In extreme operation conditions (temperature, irradiation, etc.) metals with high melting temperature and high thermal conductivity will be recommended. Copper is a candidate material for these applications due to excellent thermal conductivity and nonreactivity with some ceramic fibres. But its thermal expansion is high and has insufficient mechanical properties. The ceramic fibres (carbide, oxide or carbon) can decrease the thermal expansion, the density of composites and increase mechanical properties. One group of ceramic fibres is produced in tow form, which consists of several hundred individual fibres with diameter from 6-to 15 m. This form provides preparing the composite of complex shape with fibre orientation of expected thermal end mechanical exposition. Adhesion between copper and many ceramic fibres is very poor and some problems during composite preparation and applications can occur.
Proposed collaboration can be concentrate on the following areas:
Composite samples preparation by:
- vacuum diffusion bonding of copper coated ceramic fibres
- infiltration of liquid copper into the fibrous preform in high-pressure autoclave.
Measuring of important properties of composite materials:
- thermal conductivity and thermal expansion (CTE) after thermal cycling between 20 – 600 °C,
- microstructure of fiber alignment, interfacial characteristics (adhesion of coating, interfacial reaction, formation of the joints) before and after thermal exposure.
Modelling of the dependence of thermal conductivity on fiber volume fraction, fiber distribution and alignment of composite layers and their comparison with experimental results.
Joining parameters (wetting of brazing metals, temperature, time, etc.) to prepare good joint between composite and base material will also be studied. To decrease great strain between materials with different CTE the composite interlayer may be applied.

Recent international cooperation of the research team

Austrian Research Centre, Seibersdorf, Austria; Frauenhoffer Institute for Applied Material Research, Dresden, Germany; Institute of Electronic Materials Technolgy, Warsaw, Poland

Proposerīs relevant publications related to the research subject

KORAB, J., STEFANIK, P., KAVECKY, S., SEBO, P., KORB, G.: Thermal conductivity of unidirectional copper-matrix carbon fibre composites. Composites A (in press).
KORAB, J., STEFANIK, P., KAVECKY, S., SEBO, P., KORB, G.: Thermal expansion of cross-ply and woven carbon fibre copper matrix composites. Composites A 33 (2002) 133-136.
STEFANIK, P., KAVECKY, S., KORB,G., GROBOTH, G., SEBO, P.: Thermal expansion of copper matrix composite with spiral arrangement of carbon fibres. J. Mater. Sci. Lett.16, 1997, 392-394.
STEFANIK, P., SEBO, P.: Thermal expansion of copper-carbon fibre composites. Theor. Appl. Fract. Mech. 20, 1994, 41-45.