Silicon-Boron Alloys as New Ultra-High Temperature Phase-Change Materials: Solid/Liquid State Interaction with the h-BN Composite

• Published in: SILICON Vol. 12; no. 7; pp. 1639 - 1649
• Main Authors: Polkowski, Wojciech, Sobczak, Natalia, Bruzda, Grzegorz, Kudyba, Artur, Nowak, Rafal, Polkowska, Adelajda, Krzak, Izabela, Tchórz, Adam, Giuranno, Donatella
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.07.2020; Springer Nature B.V
• Subjects: Alloys; Boron; Boron alloys; Boron nitride; Chemistry; Chemistry and Materials Science; Energy storage; Environmental Chemistry; Eutectic alloys; Heat resistant alloys; High temperature; Inorganic Chemistry; Lasers; Latent heat; Materials Science; Melting; Optical Devices; Optics; Original Paper; Phase change materials; Photonics; Polymer Sciences; Refractories; Silicon; Solidification; Thermal cycling; Thermal energy; Ultrahigh temperature; Vessels; Wettability; AMADEUS project; Silicon-boron alloys; Hexagonal boron nitride; Sessile drop method; Latent heat thermal energy storage
• ISSN: 1876-990X; 1876-9918
• DOI: 10.1007/s12633-019-00256-9

Silicon-boron alloys have been recently pointed out as novel ultra-high temperature phase change materials for applications in Latent Heat Thermal Energy Storage (LHTES) and conversion systems. One of the emerging challenges related to the development of such devices is a selection of refractories applicable to build a vessel for storing molten Si-B alloys at high temperatures and under consecutive melting/solidification conditions. Previously, it has been documented that hexagonal boron nitride (h-BN) is the only one ceramic showing a non-wettability and limited reactivity with Si-B alloys at temperatures up to 1750 °C, what makes it a good candidate of the first selection for the predicted application. Nevertheless, pure h-BN shows a rather low mechanical strength that could affect a durability of the LHTES vessel. Therefore, the main purpose of this work was to examine high temperature behavior of commercial high strength h-BN composite having a nominal composition of h-BN-24ZrO 2 -6SiC (vol.%) in contact with a solid/liquid eutectic Si-3.2B alloy. Two types of sessile drop experiments were carried out: a step-contact heating up to 1750 °C, and a thermocycling at 1300 − 1450 °C composed of 15 cycles of the alloy melting/solidification. The obtained results showed a lack of wettability in the examined system at temperatures up to 1750 °C. The Si-3.2B alloy presented good repeatability of melting/solidification temperatures in consecutive thermal cycles, which was not affected by the interaction with the h-BN composite. However, due to reactions taking place between the composite’s components leading to structural degradation, it is not recommended to increase operational temperature of this material above 1450 °C.