High-performance and continuous zeolite MFI membranes have been successfully fabricated, using in situ hydrothermal synthetic method, on α-Al2O3 hollow ceramic fifibers (HCFs). The CO2 separation properties of the as-prepared MFI membrane are studied by single gas permeation and binary gas permeation of CO2/N2 and CO2/CH4. The separation results show that the membrane exhibits high CO2 selectivity with separation factors of 9.2 and 6.0 for CO2/N2 and CO2/CH4, respectively. A preferred permeance for CO2 in the binary gas mixtures is about 3 × 10−7mol/(m2 s Pa). Furthermore, the supported MFI membrane possesses high mechanical strength, strong thermal stability, and high reproducibility, which are expected to have potential applications in industrial CO2 recycling.

A new technology to coat open-celled foams homogeneously by using a vertical centrifuge and shear-thinning slurries is presented. The technology is exemplified by a complex multilayer-coated foam for catalytic applications (Fig. 3). Furthermore, a new calculation model for the estimation of coating thickness and for quality assessment is introduced and proved by comparing the calculated and experimental data. Based on these results, various material combinations are shown, e.g., layers made of rough particles, zeolites, activated carbon, γ-Al2O3, perovskites, mullite, and yttria–alumina–garnet on SiC–, Al2O3–, or cordierite foams. Theses “functionalized foams” can be used for a wide variety of practical applications, e.g., as adsorbents and catalysts in environmental engineering, as preforms for metal matrix composites, and for special purpose applications that require corrosion and oxidation resistance.

We determine the nonequilibrium grain size distribution (GSD) during the crystallization of a solid in d-dimensions under fixed thermodynamic conditions, for the random nucleation and growth model, and in the absence of grain coalescence. Two distinct generalizations of the theory established earlier are considered. A closed analytic expression of the GSD useful for experimental studies is derived for anisotropic growth rates. The main difference from the isotropic growth case is the appearance of a constant prefactor in the distribution. The second generalization considers a Gaussian source term: nuclei are stable when their volume is within a finite range determined by the thermodynamics of the crystallization process. The numerical results show that this generalization does not change the qualitative picture of our previous study. The generalization only affects quantitatively the early stage of crystallization when nucleation is dominant. The remarkable result of these major generalizations is that the nonequilibrium GSD is robust against anisotropic growth of grains and fluctuations of nuclei sizes.

The microstructure evolution and diffusion of silicon during heat-treatment and plastic deformation process were studied on the clad plates of Al–Mn/Al–Si aluminum composite fabricated by continuous casting. The results show that when the clad slab is homogenized and hot rolled, silicon diffuses across the interface from the Al–Si alloy (4004) side to the Al–Mn alloy (3003) side and dissolves into the 3003 matrix forming a solid solution. However, after deformation by cold-rolling, the increased driving force for precipitation of the solute elements in the core alloy side along with the abundant defects introduced by the severe deformation promotes the precipitation. Some Mg2Si particles precipitate from the solid solutions to form a transition region close to the interface of the two components. The presented transition area not only benefits the microstructure of the clad sheet but also improves the distribution of the microhardness across the interface, a tendency of gradient transition.

During the advance of the nuclear fission reaction, fission products accumulate and form pores (gas bubbles) that decrease the thermal conductivity of the nuclear fuel, potentially leading to overheating of the fuel element. To investigate this important phenomenon, a finite-element method is used to simulate the effect of 3-dimensional (3D) distributions of pores on the thermal transport in a nuclear fuel element consisting of uranium oxide (UO2) nuclear fuel pellet and Zircaloy cladding. Spherical pores ranging in size from 70 to 172 µm are introduced to create up to 30 vol% total porosity. The simulations demonstrate that the centerline temperature increases with the total porosity and the increase is nonlinear. The results also show that the centerline temperature, at fixed total porosity, weakly depends on the pore size distribution. This method can provide useful information regarding the effect of high porosity levels that may occur in off-normal operation conditions.

This article provides an overview of the key concepts and recent theoretical developments in computational modeling of complex metal hydrides with a focus on applications in hydrogen storage. Density functional theory based first-principles calculations have played an important role in understanding the structural and thermodynamic properties of these materials. Methods for predicting crystal structures and hydrogen positions in complex hydrides have been developed to complement experimental synthesis and characterization. Together with an efficient formalism for determining multinary phase diagrams under variable temperature and hydrogen pressure (the grand-canonical linear programming method), they constitute a complete first-principles framework for designing new hydrogen storage reactions. We also review the progress in modeling reaction kinetics in a prototypical complex hydride (i.e., a transition metal catalyzed sodium alanate [NaAlH4]). While many aspects of titanium-doped NaAlH4 remain hotly disputed, we discuss areas where satisfactory quantitative understanding has been achieved: diffusive metal mass transport, bulk substitution of Ti, and hydrogen dissociation.