This study reports the effect of feedstock origin, residence time and heat treatment temperature on CO 2 and O 2 reactivities, nanostructure and carbon chemistry of chars prepared at 1300, 1600, 2400 and 2800 • C in a slow pyrolysis reactor. The structure of char was characterized by transmission electron microscopy and Raman spectroscopy. The CO 2 and O 2 reactivity of char was investigated by thermogravimetric analysis. Results showed that the ash composition and residence time influence the char reactivity less than the heat treatment temperature. The heat treatment temperature and copyrolysis of pinewood char with biooil decreased the CO 2 reactivity approaching that of metallurgical coke. Importantly from a technological standpoint,

No abstract

The growth morphology and growth rate of silicon carbide at the interface between crucibles made of graphite or of glassy carbon, and liquid silicon have been studied. The growth occurs slowly reaching a layer of -26 ~m on graphite and of -8 ~m on glassy carbon after 48 h at 1500~Silicon nitride performed well as crucible material only during short times up to 20 rain. Later the melt penetrated into the ceramic body leading to a disintegration of the crucible.

No abstract

This paper addresses a continuum-mechanical, bi-phasic, two-scale numerical model for casting and processing of metallic alloys. The solid and liquid physical states, which represents the solid and molten alloy, are formulated in the framework of the theory of porous media (TPM) including thermal coupling, finite plasticity superimposed by a secondary power creep law and visco-elasticity associated by Darcy's permeability for the solid and the liquid phase, respectively. In view of phase transition during solidification, a two-scale approach considering the phase-field on the micro-scale is proposed, where a double-well potential with two local minima for completely solid and liquid physical states is utilized. The finite element method based on the standard Gallerkin element formulation and the finite difference method was employed for the macro-scale and the micro-scale, respectively. Finally, the performance of the discussed model is demonstrated by the recalculation and validation of a solidification experiment.