Particle coalescence, growth

We discuss here two major processes, the absorption growth process where particle nuclei grow up with absorption of metal atoms, and the coalescence growth process where particles grow up by collision of particle nuclei or clusters (2). The combination of these processes leads to two well-known distributions, the normal-like distribution and the lognormal distribution, depending on the growth condition. These distributions are frequently found for the size distribution of small particles. The... 

The process by which vapor-deposited material forms two-dimensional arrays of spherical particles just beneath the substrate surface has been studied in detail. A model has been proposed in which the numbers and sizes of particles are determined by the coupled processes of particle growth (by capture of diffusing molecules) together with particle coalescence. Expressions have been derived for particle size and number density as functions of deposition parameters. Experimental evidence is presented in support of the model for the case of selenium physically vapor-deposited onto a heated thermoplastic substrate. Finally, the technological application of the deposit morphology as dry microfilm is reviewed. 

Contrary to tumble/growth agglomeration, where individual particles or clusters of particles coalesce with each other and successively build a structure by material addition on the surface of a growing mass, in pressure agglomeration, a defined volume of loose, sometimes pre-processed feed material is introduced into a more-or-less closed or closing die and mechanically compressed by external forces that are caused by the... 

Gontrolled, forced agglomeration provides conditions that are favorable for particle coalescence and/or size enlargement by growth. These methods yield instant products since most powders achieve that characteristic by mere agglomerate growth. 

Feeney, et al. [94] found that the narrowest particle size distribution was obtained with Aerosol MA despite the duration of Interval I being longest with this emulsifier. They concluded that polydispersity decreased with increasing entry rate of radicals into latex particles which minimizes variation in growth rate between particles. However, at the concentrations used. Aerosol MA was close to its cmc and produced fewer particles, whereas the other emulsifiers were well above their erne s so that particle coalescence evidently proceeded further with Aerosol MA. 

The time evolution of / is is influenced by chemical and physical processes like particle growth, particle coalescence, particle nucleation, the effect of additional substances (e.g. catalyzers and emulsifiers) and the reaction conditions. For the more chemical and physical side of the quite complicated interplay of all these factors we refer to the papers mentioned in the introduction. 

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