Interphase in composite materials

Abstract

Interphase is an essential part of a composite material. It can provide optimal interfacial properties to allow debonding between the fibre and the ceramic matrix so as to improve the toughness of ceramics. It can act as a diffusion barrier to stop or retard the chemical reaction between the reinforcement and the metal matrix at service temperatures so that property degradation can be minimised. It can improve the bonding between the filler and the polymer matrix to achieve desired mechanical properties. Therefore, it is paramount that we have a knowledge of the interphase and its influence on properties of the composite. However, due to problems associated with the investigation into interfacial phenomena, lack of information about the interphase prevails for many widely used composites. In this paper, results obtained from interfacial investigations using electron microscopy and energy dispersive X-ray spectroscopy on three categories of composites, namely, ceramic matrix composite (Nicalon fibre/silicon carbide), metal matrix composite (carbon fibre/aluminium alloy), and polymer matrix composite (hydroxyapatite particle/high density polyethylene), are correlated with their mechanical properties. In this way, it is shown that the interfacial condition has a strong influence on mechanical properties of the composite.