Dependence of ceramic fracture properties on porosity

Enhanced mechanical properties of nanocrystalline boron carbide by nanoporosity and interface phases

“…Traditionally, porosity and weak interface phases are considered to be detrimental, especially in brittle ceramics, as both of them can initiate catastrophic failure at low stress levels 33,34 . However, our study is the first to demonstrate that the interplay between nanopores and weak interface phases in nanocrystalline ceramics can enhance the fracture toughness, engineering strength and even ductility of brittle B 4 C. As the nanopores are much smaller than the critical crack size (~3-5 µm) of brittle B 4 C, even they have a sharp corner, they would not serve as the crack sources and instead increase, rather than decrease, fracture strength when the initiated microcracks are blunted by the nanopore-mediated GB sliding, which is lubricated by the interface amorphous carbon.…”

Porous Particle-Polymer Composites

“…This is often expressed by including a numerical exponent such as is shown in Equation 7, (Brown et al 1964) and refer to Phani et al (1988), Maitra and Phani (1994) and Wagh et al (1993). The elastic modulus can also be expressed as being a product of the composite elastic modulus and ℮ m , Equations 8 and 9, (Rice 1977, Knudsen 1959.…”

“…Generally, non-linear models are found to be more accurate. Phani et al (1988), Maitra and Phani (1994) and Wagh et al (1993) have suggested the use of the following relationship, Equation 6, which is essentially an exponential modification of the linear expression (Equation 5). In this equation, a and b are constants, or, fitting parameters.…”

The structure-property relationships of powder processed Fe-Al-Si alloys

“…However, the grain size developed at 1200°C was 26 pm compared to 76 pm developed at 1300°C. Typically, an increased porosity level reduces the fracture toughness of a structure member [50]. The immediate effect is to reduce the cross-sectional area supporting the load.…”