“…It seems, that such kind of pyrocarbon coating could be the result of volatile matter deposition only, unlike the carbon deposits on the walls of coke oven. These latter ones are formed from gaseous products as well as from fine particles of coal and mineral matter, and finally are the low ash content mixtures of pyrolytic carbon and chars (Nakagawa et al, 1998) which, according to Zymla and Hottard (2007), are composed of very weakly crystallized carbon forms.…”