bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Porous Inorganic Membranes
Authors: Tsapatsis Michael , Gavalas George R. 
Published: August 2016

Here we will attempt a brief overview of recent synthetic efforts for micropore and lower-end mesopore membranes. We will not address the very important classes of nonporous membranes, such as dense metals and solid electrolytes with applications in H2 and O2 separations, or meso- and macroporous membranes, which find applications in food processing and water treatment. Microporous materials provide high permselectivities for molecules encountered in the chemical-processing industry but suffer from low intrinsic permeabilities. Therefore, in order to bring microporous membrane materials to commercial applications, functional composites with small effective thicknesses (in the micron or submicron range) must be developed. For example, to achieve economical membrane-reactor sizes, fluxes as high as 0.1 mol/(m2 s) are desirable. Approaches to microporous membranes include modification of mesoporous membranes by sol-gel and chemical-vapor-deposition (CVD) techniques, carbonization of polymers to form molecular-sieve carbon, and polycrystalline-film growth of zeolites and other molecular sieves.Microporous carbon is widely used for liquid or gas purification because of its strong adsorptive properties and high surface area. It is also used for air separation by pressure swing adsorption (PSA), relying on its adsorptive and molecular-sieving properties. From the standpoint of applications, microporous carbons are classified into activated carbons with pore size 0.8–2 nm, and ultramicroporous carbons or carbon molecular sieves with pores 0.3–0.6 nm. Activated carbons are used because of their strong adsorption properties, while carbon molecular sieves are useful on account of their molecular-sieving as well as adsorption properties.
Characterization of the Pore Structure of Membranes
Authors: Ramsay John D.F. 
Published: August 2016

A better understanding of membrane microstructure and its role in the mechanisms of different separation processes is important in the development of new and more complex types of membranes. This understanding is particularly significant in the case of inorganic membranes because the permeation and separation properties are determined by the porous properties of this microstructure, which in turn is controlled by the synthesis route. This review will cover three topics: first, the origin and development of porosity in inorganic materials; second, the general definitions and terminology used to describe porous media; and third, a brief description of several techniques that can provide pore-structure characteristics of membranes.A distinction will be made between two techniques: static and dynamic methods. Dynamic methods are based on membrane permeation characteristics and are used routinely to assess membrane performance. This review, however, will be restricted to static methods, which can provide details of porous microstructure directly. These include the following: stereology (microscopic techniques such as scanning electron microscopy [SEM]); intrusive methods (e.g., mercury porosimetry, physisorption of gases, calorimetrie methods, and nuclear magnetic resonance [NMR] analysis); and nonintrusive methods (e.g., radiation scattering with neutrons and x-rays, wave propagation, ion-beam analysis, and positron lifetime spectroscopy). Finally, the suitability of these techniques in the characterization of membrane pore structure will be discussed.Porous materials can be formed in several ways, although the following three are most important in the synthesis of membrane structures.
The Application of CALPHAD Techniques in the Development of a New Gas-Turbine Disk Alloy
Authors: Small C.J. , Saunders N. 
Published: August 2016

The development of a new nickel based superalloy for use in the high-pressure turbine disk of a modern gas turbine is one of the most expensive and protracted exercises undertaken by gasturbine manufacturers. A typical complete development cycle can take more than 10 years. This delay arises not only because of the extensive mechanical testing and Validation required to ensure the safety of the critical part, but also because of the difficulty of finding a material chemistry that provides the correct degree of balance between mechanical properties and long-term material stability. The conventional approach to this latter problem is to use a combination of experience, empirical wisdom, and a few basic calculation tools based on electron-valency theory (PHACOMP). There is thus an urgent need to develop a tool that reliably summarizes the known body of knowledge about the stability of Ni-based superalloys and provides a method that can quickly and reliably guide the alloy developer through the initial alloy-chemistry selection phase of development.Calculation of phase equilibria using calculated phase-diagram (CALPHAD) techniques has now matured to the point where it is possible for the alloy developer to quickly and reliably calculate phase equilibrium in a matter of minutes without an in-depth knowledge of thermodynamics. There thus exists a tool that enables the definition of alloy chemistries so that specific assumptions can be tested and the final chemistry selected without having to carry out the traditional manufacturing, processing, testing, and examination of a large raft of experimental chemistries. This article aims to show how such a tool has been used and high lights the success of this approach in the field of Ni-based superalloy development.