Self-reinforced ceramics

Toughening of the ceramic matrix (A) by controlling the micromorphology of the matrix itself (self-reinforced ceramics). The process requires that an initial composition (A) form a liquid or solid solution (A ) from which phases with different morphologies than those existing in A and A1 are grown ... 

F. Yu, K.W. White, Relationship between Microstructure and Mechanical Performance of a 70% Silicon Nitride - 30% Barium Aluminum Silicate Self-Reinforced Ceramic Composite, /. Am. Ceram. Soc., 84 [1] 5-12 (2001)... 

Y. Fang, F. Yu and K. W. White, Microstmctural Modification to Improve Mechanical Propertiesofa70%Si3N4-30%BAS Self-Reinforced Ceramic Conposite, 7. Mat. Sci. 37, 4411-4417 (2002). 

Presently the 2 sources of AI2O3, 3 sources of SijN,-, and 2 sources of Y2O3 powders used for processing both AI2O3 and SijN matrix composites are being analyzed for their flocculation/dispersion behavior as functions of pH, time and temperature. The results of this task should be of benefit to processing of monolithic ceramics, self-reinforcing ceramics, and whisker reinforced ceramics. 

Self-reinforced Ceramic. A ceramic reinforced by in-situ growth of whisker-... 

BN is used for reinforcing ceramics and alloys to reduce wear and friction and thus obtain self-lubricating parts [109-111]. 

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. 

Again, the above crack kinking and branching criteria are limited to isotropic homogeneous material, which for all practical purposes will include particulate/whisker-filled ceramic matrix composites. No equivalent criterion exists for orthotropic/inhomogeneous material. Limited experimental results show that self-similar crack extension is a rare phenomenon in fracture of fiber-reinforced ceramic matrix composites and thus the kinking and branching criterion, if developed, must necessarily be a three-dimensional one. 

A. J. Pyzik, D. F. Carroll, C. J. Hwang, and A. R. Prunier, Self-Reinforced Silicon Nitride—A New Microengineered Ceramic, in 4th International Symposium on Ceramic Materials and Components for Engines, eds. R. Carlsson, T. Johansson and L. Kahlman, Elsevier Science Publishers, Barking, U.K., 1992, pp. 585-593. 

P. F. Becher, G S. Painter, E.Y. Sun, C. H. Hsueh, M. J. Lance, The importance of amorphous intergranular films in self-reinforced Si3N4 ceramics, Acta Mater., 48,4493-99 (2000). 

Q. Wei, et al., "Microstructural Changes Due to Heat-Treatment of Annealing and Their Effect on the Creep Behavior of Self-Reinforced Silicon Nitride Ceramics", A/a/. Sci. and Eng., A299,141-151 poi)... 

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