Nanostructure of interlayers in different Nicalon fibre/glass matrix composites and their effect on mechanical properties

Abstract

Key words. Nicalon fibre-reinforced borosilicate glass, interlayer structure, transmission electron microscopy, in situ deformation. Summaryestablish the relationship between the structure of the Interlayer phenomena, revealed by high-voltage electron microscopy (HVEM) and high-resolution electron microscopy (HREM), are presented as they occur in various SiC(Nica1on) fibre-reinforced Duran glass composites (differing in the specific sol-gel supported production processes). Their dependence on the production parameters and their influence on the materials properties are discussed, taking into account the results of scanning electron microscope (SEM) in situ tensile tests. Besides graphitic carbon, textured to a variable degree and influencing the tensile behaviour, oxycarbide formation is indicated.A reactive matrix additive, such as, e.g. Ti02, resulted in a decrease in strength and a brittle behaviour, while the addition of ZrOz markedly improves the mechanical properties.

Microstructure and creep characteristics of experimental SiCf–YMAS composites

“…However, a transition layer is also observed in SiC f -YMAS composites. A similar transition layer has also been found in SiC f -LAS Ponthieu et al, 1994) and in SiC f -Duran composites (Lewis et al, 1993;Hähnel et al, 1994). The present study has shown that the transition layer is a diffusion zone for matrix elements except yttrium in SiC f -YMAS composites.…”

ELNES across interlayers in SiC(Nicalon) fibre-reinforced Duran glass

“…For SiC(Nicalon) fibres in Duran glass the dependences of layer formation as well as of morphology and microchemistry on the processing conditions, particularly on the temperature ranging from about 1100 to 1340 • C and on the duration of hot pressing of typically 5 min to 4 h (cf [3,4]) were studied in detail. On the basis of these investigations and respective thermodynamic treatments a model was developed which divides the different chemical reactions into three steps leading to carbon-rich interlayers [5].…”

Phase identification in composite materials by EELS fine‐structure analysis

“…For SiC (Nicalon)-fibre-reinforced Duran glasses the morphology of fibre/matrix interlayers, the generation of these reaction layers as a function of the processing parameters (mainly time and temperature of hot-pressing) and the effect of such layers on the mechanical composite properties have been investigated in detail (Hähnel, 1995;Hähnel et al, 1995;Pippel et al, 1995). The influence of glassy phases on the mechanical behaviour, possibly occurring inside the reaction layers, will be focused on in the discussion below.…”