Wettability of Carbon (C), Silicon Carbide (SiC), and Silicon Nitride (Si3N4) with Liquid Silicon (Si)

Separation of the solid inclusions formed during the refining process is one of the major challenges associated with metallurgical refining of silicon (Si). Wettability of solid carbon (C), silicon carbide (SiC) and silicon nitride (Si3N4) substrates with liquid silicon was examined using sessile drop technique. This study was performed with the aim of finding the appropriate temperature for separating the above inclusions from liquid Si. Silicon of 6 N + purity was melted over each substrate and contact angle was measured in the temperature range of 1420°C to 1525°C in a slightly reducing atmosphere for each system. The contact angle for C-Si is 14° at 1420°C and reaches the value of 11° at 1520°C. In the same temperature range, the contact angle for SiC-Si system decreases from 46° to 37°. The effect of temperature on contact angle is more pronounced for Si3N4-Si system with a decline from 108° to 68° in the range of 1435–1525°C.