K. Izdinsky, P. Stefanik, F. Simancik, N. Beronska, T. Dvorak, S. Kudela, J. Korab

The role of interfacial bonding on thermal conductivity and thermal expansion of particulate and short fibre reinforced composites is decisive. Metal matrix composites reinforced with continuous C fibres represent a specific case where this is not always critical.
Al, Mg and Cu based matrices yield composites with various degree of reaction with C fibres. Pure copper and magnesium do not react with carbon fibres, and there is a lack of wetting and chemical affinity between matrix metal and C fibres in these systems. This problem can be overcome by application of matrix alloys that contain some carbide forming element (Cr, Ti, B, Al) that enhances the fibre matrix reaction. On the other hand reaction between aluminium and carbon is very extensive. Product of Al-C reaction is hygroscopic Al4C3 carbide what means that corrosion of these composites in aqueous medium can be severe. Here the extensive fibre – matrix reaction needs to be hindered either by the use of aluminium alloy (for example Al-Mg, Al-Si) or via optimisation of infiltration parameters towards lower temperatures and shorter infiltration times.
Composites with various Al, Mg and Cu based matrices were prepared via gas pressure infiltration. Thermal diffusivity and thermal expansion measurements were performed in both longitudinal and transverse directions with respect to fibre orientation. The effect of weak and strong interfaces on thermophysical properties was investigated.

The effect of strong and weak interfaces

Download complete paper