Film atomization processes

In gas atomization via film or sheet breakup (Table 4.16), the mean droplet size is proportional to liquid density, liquid viscosity, liquid velocity, and film or sheet thickness, and inversely proportional to gas density and gas velocity, with different proportional power indices denoting the significance of each factor. In recent experimental studies on liquid sheet and film atomization processes using a close-coupled atomizer, Hespel et al. 32X concluded that the... 

Ion implantation (qv) has a large (10 K/s) effective quench rate (64). This surface treatment technique allows a wide variety of atomic species to be introduced into the surface. Sputtering and evaporation methods are other very slow approaches to making amorphous films, atom by atom. The processes involve deposition of a vapor onto a cold substrate. The buildup rate (20 p.m/h) is also sensitive to deposition conditions, including the presence of impurity atoms which can faciUtate the formation of an amorphous stmcture. An approach used for metal—metalloid amorphous alloys is chemical deposition and electro deposition. 

Once a number of nuclei ai e formed on the surface of the substi ate, the next stage of dre film formation process involves the U ansport of nuclei or their constituent atoms across the surface in order to cover the ai ea available to form the complete film. It is clear from the relationship between the Gibbs energy... 

The different growth modes discussed above have been exemplified also from structural studies. Froment and Lincot [247] used structural characterization methods, such as TEM and HRTEM, to determine the formation mechanisms and habits of chemically deposited CdS, ZnS, and CdSe thin film at the atomic level. These authors formulated reaction schemes for the different deposition mechanisms and considered that these should be distinguished to (a) atom-by-atom process, providing autoregulation in normal systems (b) aggregation of colloids (precipitation) ... 

Droplet Formation in Centrifugal Atomization. The mechanisms of centrifugal atomization of liquid metals are quite similar to those for normal liquids. Three atomization modes have been identified in rotating electrode atomization process, i.e., (I) Direct Droplet Formation, (2) Ligament Disintegration, and (3) Film/Sheet Disintegration.1[189][32°] are aiso applicable to the centrifugal atomiza-... 

The most spectacular success of the theory in its quasistatic limit is to show how to film atomic motions during a physicochemical process. As is widely known, photographing atomic positions in a liquid can be achieved in static problems by Fourier sine transforming the X-ray diffraction pattern [22]. The situation is particularly simple in atomic liquids, where the well-known Zernicke-Prins formula provides g(r) directly. Can this procedure be transfered to the quasistatic case The answer is yes, although some precautions are necessary. The theoretical recipe is as follows (1) Build the quantity F q)q AS q,x), where F q) = is the sharpening factor ... 

Immersion of fatty acid films into solutions of metal ions, as already indicated, results in an intercalation of the metal ions into the planes formed by the carboxylate head groups of the fatty acids. This can be accomplished in M-FA films where the FA has been regenerated by exposure to H2S [Eq. (4)] or in FA films deposited without any metal ions. Subsequent exposure of the films to H2S has been shown to result in the formation of the metal sulfide. This intercalation/sulfidation (i/s) cycle can be repeated several times to increase the concentration of the metal sulfide in the film. This process has been investigated forCdS (34,39,42,43), PbS (39,43,44), ZnS (39,43), and HgS (45) produced in M-FA films, using Fourier-transform infrared (FTIR) and UV/visible spectroscopies, QCM gravimetry, and atomic force microscopy (AFM). 

Figure 7-2. a) Atomic processes during the oxidation reaction Me + y02 = MeO, thick film regime and b) its equivalent electrical circuit [W. Jost (1937)]. 

Fig. 1 Schematic representation of the film formation process for an aqueous polymeric dispersion (A) atomization of the polymeric dispersion (B) deposition of the polymeric dispersion on the substrate surface (C) packing of the polymer spheres with water filling the void spaces (D) formation of continuous polymeric film.

Sneh, O. Clark-Phelps, R.B. Londergan, A.R. Winkler, J. Seidel, T.E. Thin film atomic layer deposition equipment for semiconductor processing. Thin Solid Films 2002, 402 (1-2), 248-261. 

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