Matrix microcracking

Matrix microcracking may also impose a significant limitation on the engineering use of ceramic composites through its effect on strength at... 

A coefficient of thermal expansion (CTE) mismatch is present between the Nicalon fibers (4.0 x 10 /°C between 0 and 900°C) and aluminum oxide matrix (8 x 10 /°C between RT and 1000"C). This mismatch leads to the development ofresidual tensile stresses in the matrix on cool down from matrix growth temperatures. In 2-D woven composites, relatively larger areas of unreinforced matrix are likely to occur between fabric plies. Hence, for 2-D Nicalon /AI2O3 composites, these unreinforced regions are likely to develop residual tensile stresses. In some cases, the residual tensile stresses are high enough to cause matrix microcracking. The presence of these microcracks is apparent in Fig. 2. 

SiC monofilaments have been used in borosilicate and aluminoslicate glass matrices for the fabrication of model composites [80], including composites with a transparent matrix [81]. These were conveniently used to investigate the development of matrix microcracking under flexure stresses since the formation of the microcracking pattern in the transparent glass matrix could be observed in-situ. 

R. G. lacocca and D. J. Duquette, The Effects of Matrix Microcracking on the Oxidation Behaviour ofCarbon Fibre/Glass Matrix Composites, J. Mat. Sci. 28, 4749 761 (1993). 

A. R. Boccaccini, C. B. Ponton and K. K. Chawla, Development and Healing of Matrix Microcracks in Fibre Reinforced Glass Matrix Composites Assessment by Internal Friction, Mat. Sci. Eng. A 241, 142-150 (1998). 

Matrix microcracking, which can shield a sub-critical crack. 

Roberts S. J., Evans J. T., Gibson A. G. and Frost S. R. (2003) The effect of matrix microcracks on the stress-strain relationship in fibre composite tubes. Journal of... 

Nairn JA. Matrix microcracking in composites. Comprehensive Compos Mater 2000 2 403 32. 

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