Kinetics Of Graphitization Research Articles

Kinetics of graphitization of a 1600°C pyrocarbon deposit

Kinetics of graphitization of a 1600°C pyrocarbon deposit

Kinetics of graphitization of thin films of amorphous carbon: V I Zalina et al, Neorg Mater, 7 (10), 1971, 1702–1705 ( in Russian)

Kinetics of graphitization of thin films of amorphous carbon: V I Zalina et al, Neorg Mater, 7 (10), 1971, 1702–1705 ( in Russian)

103. Kinetics of graphitization

103. Kinetics of graphitization

Kinetics of graphitization—II. Pre-exponential factors

In the preceding article on kinetics of graphitization it has been demonstrated that for three typical cokes used industrially, the activation energy for graphitization is the same and is equal to 230 ± 15 kcals/mol. However, in contrast to work done elsewhere, it is shown that systematic differences in respective rates of graphitization of various cokes, do become manifest and can be interpreted by focussing the attention on the ‘structural envoronments’ of calcined cokes themselves. It is shown that differences in the rate of graphitization of various cokes are due to differences in pre-exponential factor. The ‘anisotropy’ of calcined cokes which can be determined by X-ray methods is qualitatively correlated to the rate or ease of graphitization (pre-exponential factor); the rate of graphitization increasing with the ‘anisotropy’ of the calcined coke.

87. Electron microscopy and diffraction studies of kinetics of graphitization

87. Electron microscopy and diffraction studies of kinetics of graphitization

Kinetics of graphitization-I. Activation energies

A new approach to the study of the kinetics of graphitization has been developed. By following the graphitization process as a continuous function of the extent of transformation for three typical cokes used industrially, it is shown that graphitization has a single valued activation energy of 230 ± 15 kcals/mol in the temperature ranges studied. The activation energy is the same for the three cokes studied. It is shown that graphitization of cokes is merely a growth process and not a nucleation and growth process. The rate controlling mechanism for graphitization is most probably a vacancy mechanism.

The influence of high temperature plastic deformation on the kinetics of graphitization of pyrolytic carbons

T he effects of high temperature deformation on the isothermal graphitization vs. time characteristics of a substrate- nucleated pyrolytic carbon have been investigated by comparing the x-ray structures of deformed and undeformed samples which had identical heat treatment histories. The deformation was performed in tension parallel to the substrate and in compression parallel or perpendicular to the substrate. In all cases graphitization was enhanced by plastic deformation. The effect appeared to have two components: (1) An immediate and direct influence of the deformation process, and (2) a residual effect due to deformation-induced microstructural changes. Possible mechanisms are discussed and it is concluded that the phenomena result primarily from stress-assisted bond-breaking.

Effect of Pre-Heat-Treatment on Kinetics of Graphitization

Effect of Pre-Heat-Treatment on Kinetics of Graphitization

64. On the kinetics of graphitization

64. On the kinetics of graphitization

Kinetics of Graphitization of a Petroleum Coke

Crystal structure, activation energy and heat treatment temperatures for petroleum coke and a pyrolytic carbon, showing lack of temperature dependence to degree of graphitization

The kinetics of graphitization in steel at subcritical temperatures

The determination of the graphitization reaction curves (the amount of graphite as a function of graphitization time) was carried out by means of a dilatometric method. It was established, that the reaction follows a sigmoidal curve and the amount of graphite is time dependent according to the equation y = 1 − exp − ( Kt n ) where K is the reaction rate constant and n is the exponent of the reaction. The nucleation and growth curves of the graphite were also determined after various preliminary heat treatments. It was established, that the reaction exponent n depends on the controlling factor of the process (1.5 < n < 3 at all temperatures). Three extreme cases were isolated: 1. (i) When the rate of nucleation per unit volume decreases with time, and the radial growth of the graphite nodule is proportional to the square root of time, then n = 2. In this case the growth of the nodules is controlled by diffusion only 2. (ii) When the rate of nucleation per unit volume decreases with time, and the radial growth of the graphite nodules is directly proportional to time, then n = 3. In this case the growth of the nodules is controlled by the breakdown of the carbide, 3. (iii) When the rate of nucleation per unit volume is zero, in other words, if all the nuclei already exist and the radial growth is proportional to the square root of time, then n = 1.5.