Glass microstructure

SACE technology can be used for flexible glass microstructuring. Channel-like microstructures and microholes can be obtained. Two examples are illustrated in Fig. 1.4. The channel microstructure was machined with a cylindrical 90 pm... 

Can glass be described by equilibrium phase diagrams The question refers to the fact that glass is not itself in equilibrium. We can, however, describe some aspects of the glass microstructure in terms of phase diagrams, especially that of liquid immiscibility, which leads to the phenomenon of phase separation as illustrated in Figure 8.24. 

Keywords Silicon nitride, liquid phase sintering, SiAIONs, a-phase, P-phase, grain boundary glass, oxynitride glasses, microstructural engineering, microstructure-property relationships. 

Inspecting Figs. 14.3, 14.4 14.5 and Table 14.1 shows that, as stated earlier for Bi -doped alkali or alkali-earth borate binary glasses, the excitation peak regularly shifts red and the emission peak shifts blue with increasing concentration of alkali or alkali-earth elements. As a result, the Stokes shift decreases. How does all this happen To elucidate it, information on glass microstructural changes is helpful. 

Figure11.34 (a) Reactor made by assembly of the glass microstructures, (b) Production bank with four identical reactors and distribution system.

As a further consequence microstructured glass components caimot be used at T exceeding T j. Micron-sized holes and channels, sharp edges or walls will deform by viscous flowing of the glass. Microstructured alkali alkaline earth silicate glasses can be safely used up to temperatures of about 350° C (see also Fig. 1.27, it shows the temperatures of the annealing point... 

Prom a practical point of view, only processes operating at constant pressure are of interest for glass microstructuring. Therefore, we should not use the term energy to describe energetic phenomena in the glassy network. It is better to use enthalpy (2.1) ... 

Slides Microstructures of GFRP, glass-filled polymer, cermet, wood sectioned piece of cord-reinforced automobile tyre. 

Sol-gel techniques have been widely used to prepare ceramic or glass materials with controlled microstructures. Applications of the sol-gel method in fabrication of high-temperature fuel cells are steadily reported. Modification of electrodes, electrolytes or electrolyte/electrode interface of the fuel cell has been also performed to produce components with improved microstructures. Recently, the sol-gel method has expanded into inorganic-organic hybrid membranes for low-temperature fuel cells. This paper presents an overview concerning current applications of sol-gel techniques in fabrication of fuel cell components. 

Wood Hill (1991b) induced phase-separation in the clear glasses by heating them at temperatures above their transition temperatures. They found evidence for amorphous phase-separation (APS) prior to the formation of crystallites. Below the first exotherm, APS appeared to take place by spinodal decomposition so that the glass had an intercoimected structure (Cahn, 1961). At higher temperatures the microstructure consisted of distinct droplets in a matrix phase. 

Figure 5.14 The microstructure of the set cement is clearly revealed by Nomarski reflectance optical microscopy. Glass particles are distinguished from the matrix by the presence of etched circular areas at the site of the phase-separated droplets (Barry, Clinton Wilson, 1979).

The picture of cement microstructure that now emerges is of particles of partially degraded glass embedded in a matrix of calcium and aluminium polyalkenoates and sheathed in a layer of siliceous gel probably formed just outside the particle boundary. This structure (shown in Figure 5.17) was first proposed by Wilson Prosser (1982, 1984) and has since been confirmed by recent electron microscopic studies by Swift Dogan (1990) and Hatton Brook (1992). The latter used transmission electron microscopy with high resolution to confirm this model without ambiguity. 

Brune, D. Smith, D. (1982). Microstructure and strength properties of silicate and glass-ionomer cements. Acta Odontologica Scandinavica, 40, 389-96. 

This simple reactor concept is based on a microstructured silicon chip (Figure 3.18) covered by a Pyrex-glass plate by anodic bonding [73, 74]. The silicon microstructure comprises, in addition to inlet and outlet structures, a multi-channel array. Only the Pyrex-glass plate acts as cover and inlet and outlet streams interface the silicon chip from the rear. 

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