Analysis of FeTi hydride alloys by thermal analysis, small angle neutron scattering and positron annihilation

The application of small angle scattering techniques to porosity characterization in carbons

“…Hall et al have applied contrast matching small angle neutron scattering (CM-SANS) to investigate ''closed'' porosity in a variety of materials, including polymer resins [30], coal char [31,32], and vapor-deposited metal alloys [33]. The technique consists of performing SANS on ''dry'' samples where the total scattering is from all the porosity; i.e., both ''open'' and ''closed'' pores.…”

Characterization of Metallurgical Chars by Small Angle Neutron Scattering

“…As noted in the previous section, immersing a given powder sample in various solvents will allow the neutron contrast to be controlled and hence give information on the proportion of closed versus open pores. Here, our approach was very simple and preliminary: details on the technique as applied to carbonaceous substances are given by, for example, Hall and co-workers. − …”

“…Here, our approach was very simple and preliminary: details on the technique as applied to carbonaceous substances are given by, for example, Hall and co-workers. [4][5][6][7][8] To a first approximation char, corresponds to pure carbon and has a typical carbon scattering length density of 5.7 × 10 10 cm -2 and thus would be contrasted out by immersing in deuterated toluene which also has a scattering length density of 5.7 × 10 10 cm -2 . For the matching experiments, we selected samples B, D, and F as representatives of the groups discussed later, and for each given sample made up pastes with toluene, deuterated toluene, and a mixture of toluene and deuterated toluene.…”

“…Porosity is traditionally determined by BET gas adsorption, but it is known that BET results are not always reliable: the adsorption characteristics are influenced by specific surface affinities of the probe gas molecules as well as the inability of the technique to access the enclosed pores that become increasingly available as combustion and/or gasification proceeds. It is, however, also well-known that Small Angle Neutron Scattering (SANS) is an alternative technique to characterize the pore structure of materials since a combination of SANS and the contrast matching experiments has the unique ability to distinguish between open and closed porosity. − SANS data, however, need to be interpreted with caution since they often cannot yield the structural properties of a porous solid, such as surface area, without the use of models or specific supplementary experimental data. The overall goal of this work was to explore the combined use of this SANS capability with BET measurements in order to characterize metallurgical chars.…”

“…It is, however, also well-known that Small Angle Neutron Scattering (SANS) is an alternative technique to characterize the pore structure of materials 3 since a combination of SANS and the contrast matching experiments has the unique ability to distinguish between open and closed porosity. [4][5][6][7][8] SANS data, however, need to be interpreted with caution since they often cannot yield the structural properties of a porous solid, such as surface area, without the use of models or specific supplementary experimental data. The overall goal of this work was to explore the combined use of this SANS capability with BET measurements in order to characterize metallurgical chars.…”