PROCESSING OF CERAMIC COMPOSITES

Ceramic composite toughening mechanisms are briefly reviewed pertinent 

Toughening in fiber composites can involve the above mechanisms for particulate composites, especially microcracking, crack deflection, and crack branching. Load transfer can also be important, however, it appears to be less essential for ceramic composites than most other composites The one factor that has now been quite well established as central to the 

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There are myriad issues associated with the processing of ceramic composites. The task of infiltrating and consolidating ceramics in the presence of constraining fibers without also damaging the fibers is problematic by its very nature. This topic will be surveyed in section VI. 

G. H. Cullum, Sol-Gel Processing of Ceramic Composites, in Ceramics and Ceramic Matrix Composites, S. R. Levine, Ed., American Society of Mechanical Engineers, New York, (1992). p. 139-150. 

The shape of the particles also has an effect on the viscosity. Most advanced ceramics are fabricated using nearly equiaxial particles, but the effect of shape would be important, for example, in the colloidal processing of ceramic composites reinforced with whiskers (short single crystal fibers) or platelets. Figure 4.43 shows the results of theoretical calculations for the intrinsic viscosity [i)] as a function of the axial ratio for particles with the shape of prolate ellipsoids. For an axial ratio of 15-20, which may be relevant to the use of whiskers or platelets in ceramic composites, the results show that [t ] has a value of —4.5 compared to 2.5 for spherical particles. 

Agarwal DK, Cheng J, Fang Y, Roy R. Microwave processing of ceramics, composites and metallic materials. In Clark DE, Folz DC, Folgar CE, Mahmoud MM, editors. Microwave solutions for ceramic engineers. Ohio The American Ceramic Society 2005. p. 205-28. 

The major use of CVD is, of course, to produce powders which are used widely for paint pigments, as well as for ceramic processing. There have also recently been some successful uses of chemical vapor deposition to produce composite powders for processing of ceramic composites, e.g. 4120 -Ti02 and especially Al202-Zr02, as discussed earlier . ... 

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