Nucleation with concurrent growth

The apparent cause for such eflFective removal of the finely divided salt particles dp = 0.01 to 1.0/u.m) and the residual ash particles is the process of nucleation that occurs when excess water in the gas condenses on the solids during the cooling operation. This process allows the soluble particles to be dissolved in the scrubbing liquid and the insoluble ones to be enlarged for easier capture. Theoretically, the ash particles could serve as condensation nuclei for the salt particles the ash particles then could be wetted by dissolution of the adhering salts and could cause eflFective size growth in the insoluble solids with concurrent ease of removal. 

Before seeking a morphological model, it is possible to direct research in a certain number of cases. The problem arises primarily for the transformations producing a new solid phase in which it is interesting to know whether a one-process model with only nucleation or growth or a two-process model with concurrent nucleation and growth will be necessary as a morphological model. We have for that a test that is still based on the switch method. 

The theory of the kinetics of concurrent nucleation and growth reactions has a rich history that includes work by Kolmogorov [1], Johnson and Mehl [2], Avrami [3-5], Jackson [6], and Cahn [7]. Cahn s time-cone method for treating a class of these problems is the most general of these, with the most transparent assumptions, and is presented here. The method of Johnson, Mehl, and Avrami is covered in Section 4 of Christian s text [8]. 

It is of most intrigue that unlike previous nucleation models, this model assumes a formation of diamond nuclei or nucleation sites inside the P-SiC layer, while the p-SiC layer concurrently plays a role of basal lattice for diamond epitaxial growth like in the precedent models. The second point of intrigue is the fact that the exposure and survival of the diamond nuclei or nucleation sites are made possible by a subtle balance of etching rates of Si, P-SiC, diamond, and other forms of carbon. This is consistent with the fact that HOD films can be formed only when the substrate was pretreated by proper BEN conditions. 

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