Study On The Mophology And Microstructure Of Carbonaceous Mesophase In The Development And Coking Process

The theory of development of carbonaceous mesophase is very important for thepreparation of high-performance carbonaceous products. Today, there are still manydisputable problems in this theory.In the thesis, MCMB were prepared from a coal tar pitch in a form of altering feedcomposition.adding with different sorts of light-composes. Yield variety, mophology,microtexture and microstructure characters of MCMB were assessed by varying theadding amount of additives(1# coal tar pitch and anthracene oil ). And the relevantcoking characters were assessed further to decide the easy or difficult to transform to theresultant coke and their physical nature. On the base of these, the problem of physicalqualitative changement is reviewed. Analyzing methods, such as Grain-Size Analysis,SEM, OM etc. were mainly used in the experiments. On the base of lots of experiments,the forming theory of carbonaceous mesophase was abundanted and perfected. A newtheory named by Building from Granular Basic Units (BGBU) providing by our lab wassupplemented and verified further.It was discovered that two kinds of additives(1# coal tar pitch and anthracene oil )changed the yields of MCMB in different levels, the cross section structure of MCMBbehaved different shapes, such as gourd shape, conch shape and so on. The natures ofgreen coke and difficuty changing from the relevant materal varied greatly. All theseresults were explained logically with the theory of BGBU after being supplemented. Inthe research process of physical qualitative changement, it was discovered that theextinction contour of MCMB complicated and a new kind of mosaic MCMB arisedafter being added with carbon black in dipping pitch. Yields of MCMB and theproportion of mosaic MCMB increased with the adding amount of additive carbonblack. It was concluded from cross section structure of MCMB that several kinds ofMCMB accreted in the producing system;The acting mechanism of green MCMB andgraphiting MCMB with same origin is different. The yields of secondary developmentof MCMB have improved greatly but its microstructure and mophology have not altered.The main reason lies in the green MCMB taken part in the process of development ofmesophase as crystal seeds. There is a polarized phenomenon arised among theMesocarbon microbeads due to the more crystal seeds and diversification of developingmodes of MCMB. In contrast, although the additive carbonizing MCMB also increasedthe yields of mesophase, the effect of it is leveled off to a value, which is not alteredwith the increase of carbonizing MCMB.The reason lies in the additive carbonizingMCMB only acted as an initiator to promote forming of liquid crystal when the LAMare supersaturated in the producing system. At the same time, the balance ofpolycondensation headed to produce more LAM as lots of LAM consumed in theprocess.In the process of analyzing the morphology and microstructure of MCMB underSEM, the unique technology of making SEM samples was explored, the theories in bothmolecular chemistry and supermolecule chemistry were combined to explain thephenomenions appeared in the experiments, so the forming theory of carbonaceousmesophase is abounded and perfected.