Optimization of key parameters influencing the sintering and densification of SiC/B4C ceramics as solar receiver materials

Solar receiver system plays a crucial role in determining the efficiency and long-term viability of sustainable energy solutions. This study addresses the challenge of achieving high densification in SiC/B4C composites system with the aim of producing high performance candidate suitable as solar receiver material for solar thermal applications. To optimize high performance and densification of this system, several controlling parameters have been investigated in terms of phase composition, sintering temperature, sintering time and additives. Hence, various SiC/B4C ceramic composites with varying B4C content (0‒50 wt. %) were prepared by pressureless sintering method at different temperatures (1600, 1700, and 1750 °C) and different time (2, 4, and 6 hrs), with a controlled heating rate of 10 °C/min without and with using sintering additives of 5 wt. % graphite and 5 wt. % MgO + Al2O3. The results indicated that increasing sintering time and/or temperature alone is not enough to densify the carbides system. However, increasing them with using sintering additives gave the best performance in terms of phase composition, densification and microstructure. Moreover, the enhancement of the densification behavior of the sintered composites with using the sintering additives of graphite and MgO + Al2O3 was more significant and pronounced at higher sintering temperatures. The highest density achieved was 2.48 g/cm³, approximately 77 % of the theoretical density with using 5 wt. % MgO + Al2O3 at sintering temperature of 1750 °C for 2 hrs. This improved behavior is attributed to the enhanced diffusivity and the liquid phase formation, as confirmed by X-ray diffraction (XRD) analysis and microstructural evaluation. The produced carbide ceramics is expected to be a promising solar receiver material. Ill. 14. Ref. 40. Tab. 2.