Porosity phase

Model Parameters. Table I lists the model parameters, 18 in all. Those applicable to standard, two-phase flow are shown to the left. They include the absolute rock permeability and porosity, phase viscosities, and Corey exponents and scaling constants for the continuous relative permeabilities. Information on the Boise core, including the relative permeabilities of nitrogen and water, is available from the experiments of Persoff et al. (61). Equations 10 and 11 are fit to those independently measured relative permeabilities. 

Degree of agglomeration Surface area Density and porosity Phase composition ... 

A degrading semi-crystalline polymer can be considered as a two-phase material made of a polymer phase and a porosity phase. Using Equation [8.41] in Section 8.5, the diffusion coefQcient D can be related to porosity Epo,e through... 

Microstructurc. Crystal size, porosity, and impurity phases play a major role in fixing the fracture characteristics and toughness of an abrasive grain. As an example, rapidly cooled fused aluminum oxide has a microcrystalline stmcture promoting toughness for heavy-duty grinding appHcations, whereas the same composition cooled slowly has a macrocrystalline stmcture more suitable for medium-duty grinding. 

The commercial sintered spinel and M-type ferrites have a porosity of 2—15 vol % and a grain size in the range of 1—10 ]lni. In addition, these materials usually contain up to about 1 wt % of a second phase, eg, CaO + Si02 on grain boundaries, originating from impurities or sinter aids. 

Besides the chemical composition, porosity is another property of stone which has great influence on its preservation. An increased porosity increases the exposed surface and pores allow movement of materials such as water and its solutes through the stones. If the pores are blocked or reduced in diameter such substances may be trapped within resulting in increased local interior damage. Exposure to the climatic elements is one important source of decay. Freeze-thaw cycles, in particular, result in pressures on the pore walls of the stone s interior from changes in volume during the phase transition... 

Suspension polymerization of VDE in water are batch processes in autoclaves designed to limit scale formation (91). Most systems operate from 30 to 100°C and are initiated with monomer-soluble organic free-radical initiators such as diisopropyl peroxydicarbonate (92—96), tert-huty peroxypivalate (97), or / fZ-amyl peroxypivalate (98). Usually water-soluble polymers, eg, cellulose derivatives or poly(vinyl alcohol), are used as suspending agents to reduce coalescence of polymer particles. Organic solvents that may act as a reaction accelerator or chain-transfer agent are often employed. The reactor product is a slurry of suspended polymer particles, usually spheres of 30—100 pm in diameter they are separated from the water phase thoroughly washed and dried. Size and internal stmcture of beads, ie, porosity, and dispersant residues affect how the resin performs in appHcations. 

Material Pyrometer cone equivalent Main crystalline phases Bulk Tme Apparent porosity, %... 

The properties and performance of cemented carbide tools depend not only on the type and amount of carbide but also on carbide grain size and the amount of biader metal. Information on porosity, grain size and distribution of WC, soHd solution cubic carbides, and the metallic biader phase is obtained from metaHographicaHy poHshed samples. Optical microscopy and scanning and transmission electron microscopy are employed for microstmctural evaluation. Typical microstmctures of cemented carbides are shown ia Figure 3. 

The phases and their proportions present ia hardened amalgam are controlled by many factors. The composition of the alloy the size, shape, and size distribution of the particles the thermal history of the cast ingot and the comminuted alloy and the surface treatment of the particles are some of the factors for which the manufacturer is responsible. The tooth cavity preparation and the mixing, compacting, and finishing techniques of the dentist can make the difference between satisfactory and unsatisfactory restorations, even with the best of alloys. A minimal amount of residual mercury and porosity are needed to obtain the most serviceable restorations (138). 

For isotropic homogeneous porous media (uniform permeability and porosity), the pressure for creeping incompressible single phase-flow may be shown to satisfy the LaPlace equation ... 

Truly porous, synthetic ion exchangers are also available. These materials retain their porosity even after removal of the solvent and have measurable surface areas and pore size. The term macroreticular is commonly used for resins prepared from a phase separation technique, where the polymer matrix is prepared with the addition of a hq-uid that is a good solvent for the monomers, but in which the polymer is insoluble. Matrices prepared in this way usually have the appearance of a conglomerate of gel-type microspheres held together to... 

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