Capillary infiltration of hexadecane in packed SiC powder and in SiC/SiC preforms: Pore description and calculation of molten Si infiltration

A SiC/SiC Si composite can be synthesised by molten silicon infiltration in a SiC preform impregnated with a slurry of SiC powder. The kinetics of molten silicon infiltration in such a porous material are unknown, and the experimental measurement is complex. The calculation of the rise kinetics for a liquid in a porous material is possible by applying the Washburn modified equation with an accurate description of the pores. The monitoring of the mass and front height variations during hexadecane infiltration in a submicronic SiC packed powder and in a preform filled with a SiC powder was used to characterize the porosity. In the case of a fibrous preform, the residual porosity is composed of inter grain pores and cracks formed during the drying of the slurry. The results of this study suggest that the liquid progresses first in the inter-grain porosity of the powder. The rise kinetics of molten silicon into a preform were then evaluated by calculation based on the pore description obtained from hexadecane capillary infiltration experiments. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.