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Chemical inhomogeneity

Chemical Inhomogenities or Compositional Separation. Compositional separation at the grain boundaries influences the magnetic interactions of the individual grains. Deposition parameters such as temperature, substrate material, and the use of a seed layer play an important role. [Pg.181]

Because the time at high temperature is much less, austenite is produced, which is chemically inhomogeneous especially with undissolved carbides, and has a fine grain crystal size. The formation of the hard martensite requites more rapid cooling than for conventional hardening. Thus case hardening by heat treatment intrinsically requites that the surface region to be hardened be relatively thin and cooled rapidly. [Pg.211]

The role of reactive centers is performed here by free radicals or ions whose reaction with double bonds in monomer molecules leads to the growth of a polymer chain. The time of its formation may be either essentially less than that of monomer consumption or comparable with it. The first case takes place in the processes of free-radical polymerization whereas the second one is peculiar to the processes of living anionic polymerization. The distinction between these two cases is the most greatly pronounced under copolymerization of two and more monomers when the change in their concentrations over the course of the synthesis induces chemical inhomogeneity of the products formed not only for size but for composition as well. [Pg.175]

Each copolymer chain is chemically inhomogeneous along its length. [Pg.184]

Bohacek P (1977a) Chemical inhomogeneity of materials and its determination. Compact materials. Coll Czechoslov Chem Commun 4 2982... [Pg.64]

As pointed out in the foregoing, there are two specific peculiarities qualitatively distinguishing these systems from the classical ones. These peculiarities are intramolecular chemical inhomogeneity of polymer chains and the dependence of the composition of macromolecules X on their length l. Experimental data for several nonclassical systems indicate that at a fixed monomer mixture composition x° and temperature such dependence of X on l is of universal character for any concentration of initiator and chain transfer agent [63,72,76]. This function X(l), within the context of the theory proposed here, is obtainable from the solution of kinetic equations (Eq. 62), supplemented by thermodynamic equations (Eq. 63). For heavily swollen globules, when vector-function F(X) can be presented in explicit analytical form... [Pg.178]

The main drawback in this type of thermometry is the presence of spurious thermoelectric powers due to chemical inhomogeneity, stress in conductors, contact effects in switches if present, etc. [Pg.217]

Although microwave synthesis dramatically decreases reaction time, it does not solve the problem of chemical inhomogeneity, and temperatures in the reaction are high. It does have some other advantages, however. One advantage is that less problems occur with cracking because the heating is from inside, and not absorbed from outside. [Pg.159]

This is a form of Fick s law for a chemically inhomogeneous material where the intrinsic diffusivity, designated by >1, measures the flux in the local C-frame. A similar procedure for component 2 yields an analogous Fick s-law expression, J2 = -D2dc2/dx. [Pg.47]

The self-diffusivity of species 1 in a chemically homogeneous solution of concentration ci, corresponding to D in Eq. 3.5, can be compared with the intrinsic diffusivity of the same species in a chemically inhomogeneous solution at the same concentration, corresponding to D in Eq. 3.12. Typically, in addition to the approximation of a concentration-independent average site volume (fi), it is reasonable to assume that the coupling (off-diagonal) terms, 12/02 and Lm/c- in Eqs. 3.5 and 3.12, are small compared with the direct term L fc. In this approximation,... [Pg.47]

Four different types of diffusivities are summarized in Table 3.1. These include the self-diffusivity in a pure material, D the self-diffusivity of solute i in a binary system, Df, the intrinsic diffusivity of component i in a chemically inhomogeneous system, Dand the interdiffusivity, D, in a chemically inhomogeneous system. These diffusivities are applicable only in certain reference frames which are also listed in Table 3.1. In the remainder of this book, the type of diffusivity under discussion will be identified by these symbols when this information is relevant. When a diffusivity is identified in this manner, it may be assumed that the diffusion under consideration is being described in the proper corresponding frame. [Pg.53]

Di is the composition-dependent intrinsic diffusivity of component i in a chemically inhomogeneous system. In a binary system, it relates the flux of component i to its corresponding concentration gradient via Fick s law in a local C-frame (which is fixed with respect to the local bulk material of the diffusing system) and is moving with a velocity v with respect to the corresponding V-frame. The Di are related to D as indicated. [Pg.54]

D is the composition-dependent interdiffusivity in a chemically inhomogeneous system. In a binary system, it relates the flux of either component 1 or 2 to its corresponding concentration gradient via Fick s law in a V-frame. [Pg.54]

The micromagnetic structure is directly related to the microstructure and chemical inhomogenities in the layer. The materials used and the deposition technology as well as the parameters play an important role. Thin-film growth, nudeation processes in relation to the deposition parameters, are very important for understanding the thin film microstructure. The relationships between sfd and recording properties are not necessarily valid for media with perpendicular anisotropy as the demagnetizing field can be more important than sfd. [Pg.172]

Most solid surface are also chemically inhomogeneous. Cassie considered a smooth but chemically patchwise heterogeneous surface. If there are two different kinds of region with... [Pg.130]

Tran, C. D., Cui, Y., and Smirnov, S. (1998) Simultaneous multispectral imaging in the visible and near infrared region applications in document authentication and determination of chemical inhomogeneity of copolymers. Anal. Chem. 70, 4701-08. [Pg.53]


See other pages where Chemical inhomogeneity is mentioned: [Pg.342]    [Pg.172]    [Pg.279]    [Pg.55]    [Pg.353]    [Pg.839]    [Pg.129]    [Pg.185]    [Pg.62]    [Pg.156]    [Pg.156]    [Pg.157]    [Pg.326]    [Pg.63]    [Pg.27]    [Pg.35]    [Pg.46]    [Pg.568]    [Pg.570]    [Pg.578]    [Pg.390]    [Pg.342]    [Pg.416]    [Pg.559]    [Pg.183]    [Pg.117]    [Pg.310]    [Pg.16]    [Pg.38]    [Pg.43]   
See also in sourсe #XX -- [ Pg.114 ]




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Chemical inhomogeneities, measurements with

Inhomogeneity

Inhomogenities

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