CVD in Hot Wall Reactors—The Interaction Between Homogeneous Gas-Phase and Heterogeneous Surface Reactions

Abstract

The paper is concerned with chemical vapor deposition in hot wall reactors and in particular with the interaction of homogeneous gas-phase and heterogeneous surface reactions. Based on model considerations it is shown that this interaction has a tremendous influence on the deposition chemistry and kinetics in all cases in which the precursor gas undergoes complex gasphase reactions. The decisive parameter determining the interaction is given by the ratio of free volume of the deposition space and size of the surface area of the substrate; it is termed the "third parameter" of chemical vapor deposition. Predictions from the model are experimentally confirmed using results on chemical vapor deposition of pyrolytic carbon from methane. The importance of this "third parameter" of chemical vapor deposition in investigations of kinetics and for technical processes of chemical vapor deposition and infiltration is discussed in the conclusion.

Modeling and simulation of materials synthesis: Chemical vapor deposition and infiltration of pyrolytic carbon

“…A qualitative picture of the complex reaction mechanism of CVD of pyrolytic carbon from light hydrocarbons was proposed by Hüttinger et al [17]. In the present work, we couple a multi-step chemical vapor deposition model with a heterogeneous surface reaction model of hydrogen inhibition of carbon deposition.…”

Nano-structure of Carbons Deposited from CH4 Blowing to and Injecting into Molten Slag

“…The carbon deposition reaction is complex phenomennon. Hüttinger and co-workers have shown the mechanism and kinetics of chemical vapor infiltration of pyrocarbon 2,3) in an alumina pore. Kashiwaya, et al 4) has presented a mechanism of carbon infiltration phenomenon cooperated with a reduction reaction of iron ore.…”

“…5) Similarly, the carbon deposition reaction from CO gas, 2CO(g) = C + CO 2 (g) ........................ (2) which is an opposite reaction of the gasification reaction, also produced a filamentous carbon on the surface of metallic iron. 6) Generally, the filamentous carbon has a catalyst (iron carbide) on the tip of the fiber and grown from the catalyst.…”

Modelling chemical vapour infiltration of pyrolytic carbon as moving boundary problem

“…Formally, gaseous carbon is deposited on the surface of a porous substrate due to the complex interaction of homogeneous gas phase and heterogeneous surface reactions (Hüttinger, 1998). Additionally, convection and diffusion also have a significant influence on the deposition of pyrolytic carbon on the substrate (Middleman, 1989).…”

“…Recently, reduced reaction schemes for describing the gas phase chemistry in chemical vapour deposition (CVD) of pyrolytic carbon from methane were published and compared with experimental results (Hüttinger, 1998;Benzinger et al, 1996;Becker and Hüttinger, 1998). They include composition reactions in the gas phase yielding intermediate gas phase species as well as several reactions for carbon formation from different gas phase species.…”