Chemistry and kinetics of chemical vapour deposition of pyrocarbon: VII. Confirmation of the influence of the substrate surface area/reactor volume ratio

Abstract

Carbon deposition from a methane–hydrogen mixture (pCH4=17.5 kPa, pH2=2.5 kPa) was studied at an ambient pressure of about 100 kPa and a temperature of 1100°C, using deposition arrangements with surface area/reactor volume ratios, [AS/VR], of 10, 20, 40 and 80 cm−1. Steady-state deposition rates and corresponding compositions of the gas phase as a function of residence were determined. The deposition rates in mol/h increase with increasing [AS/VR] ratio at all investigated residence times up to 1 s. However, surface-related deposition rates in mol/m2h decreased. As the same results have been obtained in a preceding study using pure methane at a partial pressure of 10 kPa, it has been confirmed that all the kinetics can be determined by changing the [AS/VR] ratio.