Flame-Chemical Vapor Condensation Process

Combustion Flame-Chemical Vapor Condensation Process 

The CF-CVC (combustion flame-chemical vapor condensation) process developed by Kear and co-workers (Skandan et al., 1996 Tompa et al., 1999) is a continuous process using the equipment shown in Fig. 1. The starting materials are metal complexes that can be vaporized and fed into a flat flame, which immediately converts the compounds to nanostructured metal oxides. The particle dilution is controlled to prevent agglomeration in a hot state 

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Rapid solidification and devitrification of amorphous metals and metallic glasses Combustion-flame chemical vapor condensation processes (Kear) Induction-heating chemical vapor condensation processes DC and RF magnetron sputtering, inclusive of the method of thermalization Laser ablation methods Supercritical fluid processing... 

Combustion-flame chemical vapor condensation processes (Kear)... 

B. Combustion Flame-Chemical Vapor Condensation Process... 

B.K. Kim, G.G. Lee, H.M. Park, N.J. Kim, Characteristics of nanostructured Ti02 powders s3mthesized by combustion flame-chemical vapor condensation process , Nanostructured Materials, 12, 637-640, (1999). 

Building on our experience with IGC and CVC, we have replaced the heat source by a flame in the Combustion Flame - Chemical Vapor Condensation (CF-CVC) technique. This technique offers several advantages over previous methods and has the potential to continuously generate non-agglomerated powders at high rates typical for industrial processes. These advantages have been exploited in other research and commercial flame synthesis processes for the production of diamond, carbon black, other particulates, and a variety of thin films, but not to date for the large scale production of nanoscale powders. 

Another process involves molecular aggregation by means of direct chemical reactions akin to polymerization. The best known example of this is the process of carbon particles in a premixed acetylene-oxygen flame. Evidently particle formation in this case does not involve condensation from a supersaturated vapor, but proceeds directly through the pyrolysis of the acetylene, forming in the process unstable polyacetylenes as intermediates in the flame. 

High-temperature thermal treatment of hazardous waste offers a reduction in volume as well as a conversion of toxic organic constituents to harmless or less harmful forms [1]. However, hazardous metals can neither be generated nor destroyed in the waste thermal process, but they can be transformed both chemically and physically [2]. There is therefore a potential for hazardous metals to emit if they vaporize at high temperatures [3]. Many matals and their salts will form vapors at temperatures reached by flame and post-flame zones of a combustion chamber. When the vapors cool, they condense to form submicron particles, which tend to be relatively difficult to capture in air polution control equipments. These emissions of submicron metallic particles have been identified as one of the greatest health risks associated with waste incineration [4]. 

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