Characterisation of Carbon Fibre Kaolin Matrix Composites

Abstract

Although structural kaolin based ceramics are attractive and useful materials, having good mechanical characteristics, low density, good corrosion and high temperature resistance, their use is restricted by their brittle behaviour. In order to improve their properties and mainly strength, toughness and high temperature performance, fibre composite ceramics have been developed. In the present work a series of kaolin-short random dispersed Grafil carbon fibre composites were produced and sintered in an inert atmosphere of Argon at 1000oC and 1300oC and characterised using various techniques. XRD analysis of the kaolin matrix at 1000oC showed that the crystalline phases were decomposed without the formation of mullite a fact which also reconfirmed by SEM examination. However at 1300oC mullite formation was well evidenced. XRD analysis of the fibres in “as received” showed that they have graphite structure which was also retained, as SEM examination revealed, after sintering. Examination of the Grafil fibres showed that they were quite uniform in length and diameter and retained their integrity after sintering at the examined temperatures. Examination the fractured composite surfaces showed only a weak bond between fibres and matrix and at the pull out areas the fibres were replicated in the matrix.

Physical Properties of Porous Clay Ceramic-Ware

“…4. Equation may be reformulated as (23) where the magnitude of the coefficients of V 1 confirms that volume fraction of sawdust is the major variable influencing the development of fracture toughness K Ic in T specimens. The model illustrated in Eq.…”

“…1 show the direction of transport of the wet clay-sawdust suspension during forming. This plastic flow may align the sieved sawdust fibers along the direction of flow [23]. Rapid changes occur in the microstructures (basically chemical transformation, pore formation or densification) during liquid phase sintering due to the rapid material transport through the fluid [24].…”

“…To further validate the proposed models in Eqs. (8), (23), and (25), they were applied to the data of Monteiro et al [44]. These data are from clay ceramics containing coal fly ash as the additive instead of sawdust.…”