ISSN:
1572-8986
Keywords:
RF plasma
;
thermal decomposition
;
chromium and chromic oxide
;
modelling and experiments
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Technology
Notes:
Abstract Vapor-phase thermal decomposition of chromic oxide in an rf argon plasma was studied using a new experimental system. Homogeneous and heterogeneous modes of reaction were compared, the overall process efficiency being substantially higher for the process carried out entirely in the vapor phase. Reaction products were collected along the reactor wall and studied by chemical methods as well as SEM, X-ray, and IR absorption. The collected powder was highly reactive, fine-grained, and of semiamorphous nature, the average particle size being well below 100 nm. Temperature profiles recorded below the coupling coil by spectroscopic methods were typical of an rf plasma, showing maxima slightly exceeding 5000 K, with the presence of off-axis peaks. Local Cr contents and concentration ratio η(Cr)/η(Cr2O3) in the plasma were determined from the deposition data obtained. A diffusion process was assumed for the wall-deposit buildup. The results obtained confirmed the advantages of using plasma vapor-phase systems, these being higher-efficiency processes and more reliable models than those obtained in the case of gas-solid plasma reactors, where solid particles are injected into the plasma. The thermal decomposition conversion of Cr2O3 into Cr was about 8 times higher in the homogeneous gas phase than in the plasma solid phase, all other conditions being equal.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00571274
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