Interfacial flaws

Flaws, interfacial (adhesion) Flaws in the interfacial material, such as cracks and voids, that concentrate stress and provide initiation points for fracture. Their presence lowers the fracture toughness of the interfacial material. See also Flaws, surface. 

The concept sounds attractive, but there is a flaw in the explanation. Assuming an equilibrium situation between the two bulk phases and the interphase, complex formation at the interfacial region requires the same complexes are formed also in the bulk phases. Consequently, in order to produce a considerable amount of the mixed species MA, xBx in the liquid-liquid boundary layer some B must be dissolved in the aqueous, as weU as some A in the organic phase. Since by definition this condition is not met, the relative amount of M present at the interphase region as MAn xBx must be negligible. However, now the metal ion will be distributed between MA in the aqueous phase and MBp in the organic layer (n and p are the... 

Some disadvantages include the following. When carbamates react with acidic substances, carbon dioxide is released. This could result in the formation of bubbles (flaws) at an interface and concomitant weakening of the interfacial bond. The insolubility of a carbamate salt in organic media could retard coupling reactions. The stability of the carbamate salt under nonacidic conditions could retard or inhibit coupling reactions. 

Critical flaw size predicted to cause a crack to kink out of the BN interphase, plotted against the ratio of the interfacial fracture resistance to the fracture resistance of Si3N4 (adapted from ref. [30]). 

S. Suresh and J. R. Breckenbrough, A Theory for Creep by Interfacial Flaw Growth in Ceramics and Ceramic Composites, Acta Metall. Mater., 38[1], 55-68 (1990). 

In this work, we show that small amounts of water vapor dramatically lower the lateral force required to fiacture the salt-glass bond as the SFM tip is drawn across the particle. We model this decrease in terms of the effect of water vapor on tiie interfticial surfiice energy. Particle size also affects the interfticial shear strength, presumably due to variations in the size of interfacial flaws relative to the total interftice area. 

The alumina scale shown in Figs. 7c and d failed certainly by the buckling mechanism. Within the spalled regions on the specimen surface, large interfacial voids were detected which represent interfacial flaws where the scale buckles during scale loading. A mechanical stability analysis yields the critical equi-biaxial stress, orh. when buckling occurs [7]... 

Furthermore, the absorption of water by the interphasal polymer can reduce its yield strength below the interfacial bond strength. Thus, the apparent interfacial shear strength will be reduced, and a yield front, rather than a debond, will propagate along the fibre interface modifying the stress transfer micromechanics at a fibre break. A consequence is that the stress concentrations in adj acent fibres to the fibre break will be reduced, and the probability of the formation of a flaw of critical dimensions is also reduced. The number of interacting fibre breaks associated with a flaw of critical dimensions will increase. 

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