Examination of the interaction between liquid silicon and bulk silicon carbide

• The dissolution and growth of SiC crystals in the presence of molten silicon.
• The formation of a SiC layer at the surface of molten silicon.
• The influence of temperature and thermal gradients on these processes.
• The influence of the nature of the sample on these processes.

Little information is available about the evolution of SiC in the presence of molten silicon. In this context, two kinds of experiments relative to the interaction between SiC substrates and molten Si were performed between 1450 and 1600 °C with: (1) dense α-SiC bars and (2) dense α-SiC pellets coated with a β-SiC layer deposited by CVD. The results obtained indicate that an important crystal growth occurs in any cases. Large and facetted SiC crystals have grown on the surface of the SiC substrates and on the whole surface of molten silicon. These crystals are formed by dissolution-growth mechanism of SiC substrates with kinetics depending on the temperature. Low thermal gradients within the samples and between the inner parts and/or the surface of the samples could noticeably promote the evolution of the system by generating a carbon flux. The interaction between molten silicon and SiC is of importance because it could have some effects on the physical and chemical properties of the materials. It is well known that large grains are deleterious for mechanical properties.