High temperature interaction between Si–B alloys and Si3N4

Jian Meng Jiao,Kai Tang,Jafar Safarian,Bettina Grorud,Kathrine Sellevoll,Merete Tangstad

doi:10.1016/j.ceramint.2021.01.249

Abstract

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.

Highlights

Latent heat thermal energy storage (LHTES) is one of the most effi cient ways of storing thermal energy
Si–B alloys are proposed as Phase change materials (PCMs) due to the fact that Si (1230 kWh/m3) and B (2680 kWh/m3) are the elements of the highest latent heat of fusion compared to other metals and salt hydrates [1]
It is seen that SiB3, eutectic structure (Si + SiB3), and Si were observed in all the Si–B alloys

Summary

Introduction

Latent heat thermal energy storage (LHTES) is one of the most effi cient ways of storing thermal energy. Phase change materials (PCMs) offer state-of-the-art thermal energy storage due to high latent heat. PCM goes through a solid-liquid transformation to store en ergy in the form of latent heat. SiBn is formed in the B rich part with a peritectic reaction at 2020 ◦C, Liquid + B → SiBn. In the application of Si–B alloys in the thermal energy storage system, Si–B alloys store and release energy by phase changes between solid phases and a liquid phase. In the application of Si–B alloys in the thermal energy storage system, Si–B alloys store and release energy by phase changes between solid phases and a liquid phase It starts to melt at 1385 ◦C by absorbing a large amount of energy in the form of latent heat. Other wise, it is increased with the increase of B content at B content higher than 3.25 mass % (eutectic point)

Methods

Results

Conclusion