Hydrogen microstructure

Examples of the unique insights obtained by solid state NMR applications to materials science include the Si/Al distribution in zeolites, the hydrogen microstructure in amorphous films of hydrogenated silicon, and the mechanism for the zeolite-catalyzed oligomerization of olefins. ... 

Characterization and understanding of the microstructure become important after hydrogenation and hydroformylation of the nitrile rubber since the amount and distribution of the residual double bonds influence the properties of modified rubber. The conventional analytical tools have been used to characterize the elastomers. Spectroscopy is the most useful technique for determination of the degree of hydrogenation in nitrile rubber. 

On a more positive note, it seems clear that steels can be made more resistant to the effects of hydrogen by incorporating as many strong, finely dispersed traps in the microstructure as is possible, while ensuring that there are no continuous trap sites (such as embrittled grain boundaries). 

Similarly it seems that retained austenite may be beneficial in certain circumstances , probably because the austenite acts as a barrier to the diffusion of hydrogen, although in high concentrations (such as those obtained in duplex stainless steels) the austenite can also act as a crack stopper (i.e. a ductile region in the microstructure which blunts and stops the brittle crack). 

Concern about hydrogen damage has lead to much debate regarding limits for protection potentials of high-alloy steels. However, it is thought that under normal seawater service and cathodic protection conditions, these materials will not be adversely affected provided that the microstructure has at least 40% austenite present . This latter point is of particular importance to welds and their heat affected zone where careful control of heat input is necessary to maintain a favourable microstructure. 

Gorke, O., Peeieer, P., Schubert, K., Determination of kinetic data in the isothermal microstructure reactor based on the example of catalyzed oxidation of hydrogen, in Proceedings of the 6th International Conference on Microreaction Technology, IMRET 6, pp. 262-274 (11-14 March 2002),... 

Yeong, K. K., Gavriilidis, A., Zape, R., Hessel, V., Catalyst preparation and deactivation issues for nitrobenzene hydrogenation in a microstructured falling film reactor, Catal. Today 81, 4 (2003) 641-651. 

In order to distinguish between isolated silicon-hydrogen bonds in a dense network and other bonding configurations, such as clustered monohydride and dihydride bonds, bonds on internal void surfaces, and isolated dihydride bonds, Mahan et al. [60] have defined the microstructure factor R as... 

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