Carbon fibre composites with ceramic and glass matrices

Fibre reinforced glasses and glass-ceramics

“…Further evidence for the ability to achieve improved composite toughness for carbon fibre reinforced borosilicate glass, glass-ceramic, MgO and Al20 3 was demonstrated for discontinuous fibres. However, only in the cases where fibres were carefully aligned or where they were continuous could composite strength exceed that of the matrix (Sambell et al, 1972a(Sambell et al, , 1972bPhillips et al, 1972). The improved toughness was, in major part, attributed to low fibre-matrix interface strength which prevented matrix cracks from propagating from the matrix into the carbon fibres.…”

The influence of reinforcing fibres on the growth of cracks in brittle matrix composites

“…Glass fibre reinforced plaster, another example of a brittle matrix composite, is in extensive commerical use. Most of the systems studied incorporate random fibre arrays, but experimental data on unidirectionally reinforced carbon fibre borosilicate glass (pyrex) is available [1][2][3][4][5]. These studies have dealt with a wide range of fibre volume fractions and an attempt is made below to compare those experimental observations with the predictions of the theory outlined above.…”

“…[1] assume a matrix work-of-fracture of 3 J m -2. The effective work-of-fracture of the matrix in the composite will depend on the degree of irregularity of the matrix fracture surface, which from Sambell et al [1] appears to be appreciable, and in the degree of localized multiple cracking which might be expected as a consequence of the matrix porosity and the presence of fibres. Hence, there is a measure of uncertainty in the value to ascribe to the matrix work-of-fracture.…”

“…Experiments by Sambell et aL [1,2], Phillips et al [3] and more recently by Prewo and Bacon [4] on the use of carbon fibres to reinforce a number of different types of glass matrix have clearly demonstrated the effectiveness of such materials, e.g. the workof-fracture can be increased from 10 to 103 Jm -2.…”

An investigation into the formation of second-phase crystals in amorphous Pyrex glass

“…The use of glass as a structural material has, however, always been limited by its susceptibility to brittle failure due to small cracks or flaws acting as stress concentrators. One approach to reduce the detrimental effects of these flaws is to reinforce the glass with fibres so as to produce a glass-matrix composite (GMC) and work in the early 1970s at the Atomic Energy Research Establishment, Harwell, UK, on several glass matrices reinforced in this way with carbon fibres [1,2] showed significant improvements in mechanical properties compared with those of the unreinforced matrix. Pyrex, in particular, produced composites with good properties which led to further work being carried out on this system [3,4], but due to the poor oxidation resistance of the carbon fibres, more recent attention has focused on the use of Nicalon (silicon carbide-based) fibres [5,6] as reinforcement.…”