Microstructures whiskers

Rossignol, F., Goursat, P. and Besson, J.L. Microstructure and mechanical behaviour of self-reinforced Si3N4 and Si3N4-SiC whisker composites , J. Eur. Ceram. Soc., 13 (1994) 299-312. 

Unlike fibre- or whisker-reinforced composites, particulate composites have the advantage of being compatible with conventional powder processing, and in many cases can be pressurelessly sintered. As with other ceramic microstructures, a myriad of other ingenious fabrication routes have also been reported, but these are too numerous and system-specific to describe here. This section merely outlines the main points of powder processing where the production of composites in chemically compatible systems (i.e. those in which the components do not react chemically with one another) differs from that of monolithic ceramics. 

The attraction of reinforcing ceramic matrices with particles or whiskers is that, with appropriate microstructural design and property tailoring, materials with property combinations not possible in monolithic ceramics can be obtained. In addition, the materials remain effectively isotropic and can be manufactured by well-established techniques already in use for the manufacture of monolithic ceramics (Hansson and Warren, 2000). 

Zhao, Z., Johnson, M., Shen, Z. (2002), Microstructure and mechanical properties of titanium carbonitride whisker reinforced P-sialon composites , Materials Research Bulletin, 37, 1175-1187. 

More, K.L., Koester, D.A. and Davis, R.F., (1991), Microstructural characterization of a creep-deformed SiC whisker-reinforced Si3N4 Ultramicroscopy, 31, 263-278. 

Chen, I.W. and Rosenflanz, A., (1997), A tough SiAlON ceramic based on alpha-Si3N4 with a whisker-like microstructure , Nature, 389, 701-704. 

R. Ruh, K. S. Mazdiyasni, and M. G. Mendiratta, Mechanical and Microstructure Characterization of Mullite and Mullite-SiC-Whisker and Zr02-Toughened-Mullite-SiC-Whisker Composites, J. Am. Ceram. Soc., 71[6], 503-512 (1988). 

M. C. Shaw and K. T. Faber, Temperature-Dependent Toughening in Whisker-Reinforced Ceramics, in Ceramic Microstructures 86 Role of Interfaces, Vol. 21, Materials Science Research Series, Plenum Press, New York, NY, 1987, pp. 929-938. 

T. N. Tiegs, P. F. Becher, and P. Angelini, Microstructures and Properties of SiC Whisker-Reinforced Mullite Composites, in Mullite and Mullite Matrix Composites, Ceramic Transactions, Vol. 6, eds. S. Somiya, R. F. Davis, and J. A. Pask, American Ceramic Society, Westerville, OH, 1990, pp. 463-472. 

Fig. 7.7 (a) Transmission electron micrograph of the as-received, untested microstructure of AI2O3/33 vol.% SiC whisker composite, (b-d) Transmission electron micrographs of the fatigue crack tip region in the composite in 1400°C air (R = 0.1S and vc = 0.1 Hz) showing the nudeation of interfacial cavities. Part (e) shows the development of a diffuse cavitation zone ahead of the fatigue crack tip. From Ref. 25. 

R. Chaim, L. Baum, and D. G. Brandon, Mechanical Properties and Microstructure of Whisker-Reinforced Alumina-30 vol% Glass Matrix Composite, J. Am. Ceram. Soc., 72[9], 1636-1642 (1989). 

---