Microstructure–permeability relation of porous β-Si3N4 ceramics

Permeability and mechanical integrity of porous biomorphic SiC ceramics for application as hot-gas filters

“…In previous works, Ergun equations agreed reasonably well with k 1 , but these overestimated the inertial term [1,28]. Since Ergun's model normally did not provide an overall agreement with experimental data because it was developed for granular beds, and this is not suitable for cellular materials, many researchers have considered these equations modifiable and have already proposed different numerical constants and empirical parameters related to the microstructure of each cellular material [26,43].…”

“…Based on previous studies of cellular materials, d p can be replaced by an equivalent pore diameter, d [28,43]. When the grains of the samples are spherical, the following relationship between particle size and pore size is proposed [1]:…”

“…Due to the difficulty of determining a representative pore size in complex porous media, Ruth and Ma proposed an alternative model in order to assess the flow regime [49], where relative contributions of viscous and inertial effects on total pressure drop when a gas is flowing through a porous medium could be determined by the dimensionless Forchheimer's number [28]. It was defined as a function of the permeability constants according to Eq.…”

“…These parameters have been demonstrated to depend on volume fraction of porosity as a first approximation, but also on pore size and connectivity [27]. If the permeability is known as a function of the microstructure, then the pressure drop can be predicted under a given flow rate and the microstructure can be improved by tailoring pore characteristics [28]. However, high values of porosity cause lower mechanical strength and stability [22][23][24], despite the high permeability [29], and thus finding the balance between the two parameters is one of the main challenges in making a suitable material for filtering applications.…”

Preparation of nasal cavity-like SiC–Si3N4 foams with a hierarchical pore architecture

“…[33][34][35][36][37][38][39][40][41][42][43] Gas permeability is mainly controlled by the structural parameters such as pore characteristics (pore amount, pore size and distribution, pore shape), specic surface area and tortuosity. 41 Different approaches have been developed to improve pore size and porosity. [37][38][39][40]43 However, few studies are concerned about the high-temperature permeability that is crucial for the ltra-tion of smoke dusts from steel/power plants that usually has a temperature higher than 600 C.…”