Fracture toughness glass-ceramic matrix composites

TABLE 2. Overview of fibre-reinforced glass and glass-ceramic matrix composites (a ultimate fracture strength, fracture toughness, 2-D 2 dimensional reinforcement) [6]... 

Chlup, Z., Dlouhy, I., Boccaccini, A.R. (2001), Fracture toughness of thermally shocked SiC-fibre reinforced glass matrix composite , in Krenkel, W., Naslain, R., Schneider, H. (editors), High Temperature Ceramic Matrix Composites, Wiley, 463-468. 

The incorporation of a ceramic dispersion phase in a glass matrix leads to an increase in the effective hardness in comparison with that of the unreinforced matrix. On the other hand, metallic inclusions will usually have the opposite effect. The simultaneous modification of hardness (H) and fracture toughness (K c) in composite materials results in variations in the brittleness of the material, which can be quantified by the brittleness index (B), with B = HIKic [138],... 

As it is well-known, the ultimate objective in the development of ceramic and glass matrix composites is to increase the fracture toughness of the brittle matrix. In order to analyse the toughening achieved, most researchers have used conventional measurement of fracture toughness by indentation. The fracture toughness (Kic) from the micro-hardness indentation method can be calculated by means of the following equation [73] ... 

The ceramic phase can be the reinforcing material, the matrix material or both. The incorporation of high strength fibers increases the mechanical strength of the composites while maintaining the bioactivity of the material. In the case of glass doped materials, the fracture toughness of the material increases dramatically and renders materials suitable for dental implantation and hip replacement... 

Several types of continuous ceramic fibres are used here. Fibres made of -type glass s ( 2. Tradition continued. The silica tradition) in composites used for constmction of boats, carbon fibres (Fig. 3.12) in composites used for aviation and sports equipment. Materials other than the continuous fibres can also be applied. Namely, particles where at least one dimension is <100 nm, like clay minerals ( 2. The tradition continued. The clay tradition), carbon nanombes and graphenes (—> 5. Unusual ceramic dielectrics and conductors). Due to a high ratio of length to thickness such fillers are in contact with the polymer matrix over a large area. Therefore, their effect on strength and fracture toughness—can be observed even with a low-volume fractions of fillers (firom 0.5 to 15 %wt). Due to the dimensions of these fillers, these composites are often referred to as nanocomposites. 

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