High temperature interaction between Si–B alloys and Si3N4

Si3N4 is a candidate crucible material for Si–B alloys in high temperature thermal energy storage system. In this regard, the phase formation in the Si–B alloys and the interaction between the alloys and Si3N4 were investigated in an induction furnace at 1750 °C with the B addition of 2, 5, 8, and 11 mass %, respectively. Moreover, the wettability property of the Si-3.25B alloy (mass %) on Si3N4 substrate was examined at temperatures up to 1400 °C. The cross-sectional images and micro-analyses showed that BN precipitates were produced in the Si–B alloys and a BN layer was formed at the interface between the Si–B alloys and Si3N4. However, the amount of BN precipitates was negligible. Next, the equilibrium contact angle of liquid Si-3.25B alloy on Si3N4 substrate was determined to be 134 ± 1°, which indicates non-wetting behavior. The above results support that Si3N4 is a desirable refractory material for the high temperature thermal energy storage system.