Fluidized bed chemical vapor deposition of pyrolytic carbon – I. Effect of deposition conditions on microstructure

carbon，UK,E.Lopez-Honorato etc. SEM, TEM,Raman，XRD, Mercury porosimetry(Quantachrome

PoreMaster). acetylene, acetyene/propylene. 1250-1450. growth or nucleation mechanism.

raman spectroscopy of pyC cannot be applied for low texture pyCs. theories, a better

description.

1. pyrolytic carbon (PyC) composites, solid oxide fuel cells, heart valevs and coated

nuclear fuel particles.regained. special attention.

2. ample range of structures and properties. formation of PyC, liquid droplets model,

condensation, large hydrocarbon molecules. upholding their ideas. observations, theories.

 
3.recent literature, focused, type/concentration of molecules in the gas phase. initially

gas maturation, the evolution of the decomposition products of hydrocarbon pyrolysis

towards the formation of small linear molecules up to the synthesis of polycyclic aromatic

hydrocarbons (PAH), was the centre of attention of most work.

4.during studies. surface area/volume ratio. the ratio of linear (c2 or c3) to aromatic

molecules. gas maturation. main factor. controlling , addition of removal of five-member

ring molecules within the hexagonal structure of pyc.

5. the gas phase, paricipating in the formation of pyc/a liquid phase is present or not.

6.main parameters. hydrocarbon concentration, residence time, surface area/volume ratio and

temperature.

7.difficulty. latest models. difference, horiziontal, vertical hot wall CVD and FBCVD

machines. CVD, stationary, constant residence time or temperature. FBCVD, constantly

moving. close to the inlet nozzle, short residence times, lower temperatures and differnet

concentration of intermediate species. hot zone. middle section.  normally, conical shaped

nozzle with a single inlet hole. in this work, multi-hole gas distributor, a better gas

phase distribution. uniform gas phase distribution. coater. better properties and

uniformity.

8.200mm long graphite tube with 35 mm inner diameter. resistance graphite element. pyc

density , archimedes method. ethanol. Raman spectroscopy, Renishaw 1000 Raman system, 514nm

Ar-ion laser source. 50x. XRD. specimens, mortar and pestle. Texture, TEM, azimuthal

intensity scans. selected area electron diffraction patterns(SAED).Pt/Rh thremocouples,

different positions inside the crucible. the effect of propylene and acetylene addition on

the temperature was investigated at 1400 under the same conditions.

 the raman spectra of pyc, two first-order bands. 1360(D)1580(G),- related to the degree of ordering within the graphene layers. two second-order lines-the three-dimensional ordering along the crystallographic c-axis. D-degree of in-plane disorder in the graphitic structure. G(FWHM)-the level of graphitization of carbon samples.  graphitization-the decrease in the amount of random rotation or translation between adjacent garphene layers and the spacing between planes,therefore resembling more the orderly structure of graphite. ID/IG- the in-plane "crystal size"(La)-the diameter of a coherent domain for lattice fringes.