The real structure of the interlayer between fibre and matrix and its influence on the properties of ceramic composites

The mechanical functions of the fibre/matrix interlayer as well as its quantitative parameter dependencies and their influence on the properties of the composite system are discussed, with the theoretical model being considered under realistic conditions such as, e.g., residual stresses, transverse contraction, and particulars of the interface real structure. Corresponding to that a number of interface structure phenomena of some advanced composite materials, revealed by HVEM and HREM are discussed with respect to their relevance to the control of composite properties, including complex interlayer systems, which are produced by fibre coating as well as by chemical solid state transport and exchange reactions. The effects of texturing, hooking-together, binding, internal microcracking, and sublayer formation are demonstrated, and in some cases correlated with the mechanical behaviour of the materials.