Solid microstructure

Acknowledgement This work was financially supported by the Science Foundation of Chinese Post-doctoral Programs, the National Key Laboratory of Solid Microstructure of Nanjing University and the Natural Science Foundation of Hunan Province, China. 

Connection between Transport Processes and Solid Microstructure. The formation of cellular and dendritic patterns in the microstructure of binary crystals grown by directional solidification results from interactions of the temperature and concentration fields with the shape of the melt-crystal interface. Tiller et al. (21) first described the mechanism for constitutional supercooling or the microscale instability of a planar melt-crystal interface toward the formation of cells and dendrites. They described a simple system with a constant-temperature gradient G (in Kelvins per centimeter) and a melt that moves only to account for the solidification rate Vg. If the bulk composition of solute is c0 and the solidification is at steady state, then the exponential diffusion layer forms in front of the interface. The elevated concentration (assuming k < 1) in this layer corresponds to the melt that solidifies at a lower temperature, which is given by the phase diagram (Figure 5) as... 

In the example given above, the formation of a material microstructure was seen to take place as a result of the deposition of atoms on a substrate. Another, equally important, route to solid microstructures is via the solidification process. During the solidification process, the baseline microstructure, which will have a significant impact on both the material s properties as well as its subsequent microstructural evolution, is created as the liquid is superseded by a solid. The nature of the microstructure in the resulting solid can be quite diverse, ranging from featureless equiaxed polycrystals, to microstructures riddled with dendrites. 

Hessel, V., Angeli, P., Gavriilidis, A., Lowe, H. (2005). Gas-liquid and gas-liquid-solid microstructured reactors Contacting principles and applications. Industrial and Engineering Chemistry Research, 44, 9750-9769. 

Lowe, H. (2005) Gas-liquid and gas-liquid-solid microstructured reactors contacting principles and applica- 50-... 

Different types of gas-hquid-solid microstructured reactors (MSR) have been developed, using different gas-liquid contacting principles [4]. These principles can be classified as... 

There are both gas and solids aspects to the microstructure of a CFB. The gas can be characterised by the local velocity vector and the turbulent structure. The solids microstructure is characterised by the local solids velocity and concentration, and by their variation with time. Here we focus on the instantaneous measurement of local solids density and the interpretation of those results. Other quantities are discussed in less detail. 

Mukhopadhyay, A., Basu, B. (2(X)7). Con-solidation-Microstructure-PropertiesofBulk Nanoceramics and Ceramic Nanocomposites Areview. International Materials Reviews, 52, 257-288. doi 10.1179/174328007X160281. 

Another possibility is to use a cryomicroscope. In this case the sample (e.g. cement paste) is frozen in liquid nitrogen. The frozen sample is then fractured and inserted into the microscope chamber still in the frozen state. The frozen water is sublimated from the surface to reveal the solid microstructure beneath. 

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