Fluidised bed chemical vapour deposition of pyrolytic carbon

Pyrolytic carbon was deposited from acetylene and a mixture of acetylene/propylene on alumina particles at temperatures ranging from 1250 to 1450°C. The depositions were performed in a fluidised bed chemical vapour deposition (FBCVD) reactor at atmospheric pressure. Different techniques such as scanning electron microscopy (SEM), Raman spectroscopy and transmission electron microscopy (TEM) were applied to study the effect of deposition temperature, precursor concentration and flow rate. Difference in density and microstructure resulted from different types of products formed during the decomposition of the gas precursor and also depended whether formation of pyrolytic carbon occurred at the surface of the coated particles or in gases.