Wettability of Ceramics with Molten Silicon at Temperatures Ranging from 1693 to 1773 K

Abstract

Wettability of ceramics with molten silicon have been determined with a sessile drop method. The contact angles between molten silicon and the oxide plates, such as SiO2(s), Al2O3(s), MgO(s) are in the range from 85° to 88°. Contact angle between SiO2(s) and Si(l) was further investigated from the meniscus shape of molten silicon in the vicinity of SiO2(s)–Si(l)-gas three phases boundary. The contact angle is 87° and close to the results obtained by the sessile drop method. At the interface between Si(l) and the BN substrate, a discontinuous Si3N4 layer is expected to form and the layer may prevent BN from dissolving into molten silicon. The BN substrate has large contact angle (around 145°) with molten silicon and the contamination by the BN substrate is so insignificant that the BN plate is regarded as the most suitable substrate for supporting a silicon drop in the surface tension measurement. Contact angle between molten silicon and BN decreases with increasing PO2 in argon atmosphere. Contact angle between molten silicon and Si3N4 is about 90°. Molten silicon spreads over the SiC plate and the contact angle was estimated to be 8°.