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Carbonization is one of the main methods for comprehensive utilization of bituminous coal. Bituminous coal and its solid products from carbonization, namely char and coke, have complex pore structures, which can be characterized by fractals. We performed a study on the fractal structure of the solid products prepared from the bituminous coal of Shuiyu mine in Shanxi Province, China, at different carbonization temperatures (25°C∼1000°C) by synchrotron radiation small-angle X-ray scattering (SAXS). The results show that the bituminous coal has a surface fractal structure during the whole carbonization process. The variation of fractal dimension with carbonization temperature illustrates the different stages of the carbonization process. [ABSTRACT FROM AUTHOR]

Carbonisation is one of the important methods to improve the utilisation of coal. The structural composition of coal plays an important role in coal carbonisation. This work used small-angle X-ray scattering (SAXS) to investigate the pore structure of three kinds of raw coals with different carbon content derived from Xingtai City, Hebei Province, China. The structures of the corresponding cokes obtained through carbonisation at 1200°C were investigated by elemental analysis and SAXS. In addition, the gasification reaction of the three cokes (C1, C2, C3) with CO2 were studied by thermogravimetric analysis. The SAXS results indicate that the surface fractal dimension increases while the pore size decreases, and the pore distribution became wider after carbonisation. In addition, all coals and cokes present a positive deviation from Porod's law, indicating that there is a micro-fluctuation of electron density in the samples. Besides, it exhibites a negative correlation has been found between the degree of deviation from Porod's law and the carbon content. The gasification reactivity of cokes C1 and C3 in CO2 are higher than that of C2, indicating that the pore structures affect the gas reactivity of the three different metamorphic degree cokes in CO2. [ABSTRACT FROM AUTHOR]

The change in the fractal structure of anthracite mined in Jincheng, China, during high-temperature (1200°C) carbonisation was studied in situ by small-angle X-ray scattering (SAXS) at Beijing Synchrotron Radiation Facility (BSRF). The results show that, during carbonisation, the anthracite structure changes from a pore fractal to a surface fractal and then back to a pore fractal. With increase of temperature, the fractal dimension of the sample presents a trend of rise, decline, rise and decline again, which probably corresponds to the four stages of physical desorption, thermal decomposition, thermal condensation, and residual carbon aging in the process of carbonisation. The pore fractal exists in the initial and final stages, and the surface fractal exists in the middle two stages. [ABSTRACT FROM AUTHOR]

The changes in fractal structure during high-temperature (1200°C) carbonisation of a Chinese non-caking coal were studied in situ by synchrotron radiation small-angle X-ray scattering (SAXS). The results indicate that the raw coal, char and carbon residue possess a surface fractal structure, and a change in fractal dimension during carbonisation indicates that the process exhibits different stages. Changes in the fractal dimension and the various mechanisms during carbonisation are revealed and analysed. [ABSTRACT FROM AUTHOR]

Full-range strain hardening behaviour, containing the post-necking stage, is difficult to account for in detail. Hence, a Swift–Voce (S–V) model was used to describe the full-range stress–strain behaviour of 7050-T7451 aluminium alloy under uniaxial-tension, tension-with-notch and pure-shear processes with a hybrid experimental-numerical framework. Since the S–V model is not able to describe accurately the behaviour of Ti–6Al–4V alloy, a combined Swift and 4th degree polynomial (S-P4) model is proposed. Results indicate that the S–V model can successfully describe large-deformation behaviour of the 7050-T7451 aluminium alloy, and the S-P4 model can successfully describe that of the Ti–6Al–4V alloy based on careful designing process of the constitutive equation. [ABSTRACT FROM AUTHOR]