Layer Analysis

From the depth profile alone it is not possible to distinguish whether the profile shape is a result of diffusion of elements or of geometric effects. This example demonstrates the capacity of 3D SIMS to improve the information content of depth profiles. 

Steel alloyed with 1% A1 is more resistant to oxidation at high temperatures. The macro- and microscopic homogeneity of the distribution of all elements is better for powder metallurgical, hot isostatically pressed steels. Combining these advantages should result in better performance of high-speed steels. 

The steel particles are covered with an AI2O3 layer before hot isostatic pressing [3.58]. 

3D SIMS measurements (Fig. 3.29) show that this layer is still present in the compacted material. Carbonitrides are precipitated in small particles with a diameter of 30 nm inside the particles. The distribution of Ca ions is shown as an example of a trace element with a concentration in the ppm range. 

Surface and Thin Film Analysis Principles, Instrumentation, Applications 

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Further laminar boundaiy layer analysis is given by Crane (Z. Angew. Math. Phys., 23, 201-212 [1972]). 

LAYER-BY-LAYER ANALYSIS OF THE ICE CORE FROM BELUKHA GLACIER... 

Tong, L. S., 1968b, Boundary Layer Analysis of the Flow Boiling Crisis, Int. J. Heat Mass Transfer 77 1208—1211.(5)... 

The stagnant layer analysis offers a pedagogical framework for presenting the essence of diffusive burning. For the most part the one-dimensional stagnant layer approximated a two-dimensional boundary layer in which 6 = <5(x), with x the flow direction. For a convective boundary layer, the heat transfer coefficient, hc, is defined as... 

Goodness-of-fit analysis applied to release data showed that the release mechanism was described by the Higuchi diffusion-controlled model. Confirmation of the diffusion process is provided by the logarithmic form of an empirical equation (Mt/ M=ktn) given by Peppas. Positive deviations from the Higuchi equation might be due to air entrapped in the matrix and for hydrophilic matrices due to the erosion of the gel layer. Analysis of in vitro release indicated that the most suitable matrices were methylcellulose and glycerol palmitostearate. 

Secondary ion mass spectrometry (SIMS) and sputtered neutral mass spectrometry (SNMS) are today the most important mass spectrometric techniques for surface analysis, especially for thin layer analysis, for depth profiling, for the determination of contaminations and element distribution on a solid sample surface. 

The pressure term has been retained in the thermal-energy equation, although in low-speed flow there is very little energy content in this term. Indeed, the term is very often neglected in boundary-layer analysis. For high-speed flow (i.e., Ma > 0.3), however, the thermal energy can be substantially affected by pressure variations. 

The details of the transitions and the vortex behavior depend on the actual channel dimensions and wall-temperature distributions. In general, however, for an application like a horizontal-channel chemical-vapor-deposition reactor, the system is designed to avoid these complex flows. Thus the ideal boundary-layer analysis discussed here is applicable. Nevertheless, one must exercise caution to be sure that the underlying assumptions of one s model are valid. 

Techniques from boundary layer analysis can be used to construct a series solution to equations 29 and 30 of the form... 

The multicellular structure of laminar convection in small-scale crystal growth systems complicates the interpretation of the boundary layer analysis,... 

Analysis of Nuclear Backscattering," p. 163 in "Ion Beam Surface Layer Analysis," ed. by 0. Meyer, G. Linker, and F. Kappeler Plenum Press New York, NY, 1976. 

In flow situations, empirical analogies between mass and heat transfer are usually employed. For single-particle mass transfer, the boundary layer analysis for mass transfer is similar to that for heat transfer and thus is used for typical applications such as sublimation of a solid (e.g., naphthalene ball) or evaporation of a liquid drop falling in air. For a single sphere of diameter dp moving in a fluid, in terms of a boundary layer analysis analogous... 

The detailed layer-by-layer analysis of the electrolytic products on both of the electrodes has revealed that the fine structure of carbon spectra changes depending on the depth of Ar ion etching. This may testify that carbon is in different electronic states across the depth of the film, i.e. carbon forms chemical bonds. In analysis of the cathodic product, the change is most evident (Fig. 4, a, b) although this may be due to the recharge of carbon atoms under the action of the Ar ion beam in etching. 

Figure 3 summarizes the results obtained when the contribution of London forces In the transport rate is negligible. When the boundary-layer analysis of Levich and Lighthill is valid (Case la) the Sherwood number is given by... 

Hull and Kitchener (2) measured the rate of deposition of 0.3- an-diameter polystyrene latex particles onto a rotating disk coated with a film of polyvinyl formaldehyde. In electrolytes of high ionic strength (where the double-layer repulsion is negligible), they found close agreement between experiments and the prediction of Levich s boundary-layer analysis (Eq. 3]), indicating that a diffusion boundary layer exists and that its thickness is large compared to the domain of van der Waais and hydrodynamic interactions. These are neces-... 

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