Preparation and thermal shock resistance of solar thermal storage ceramics from high calcium and high iron steel slag

Abstract

To guarantee the efficiency of solar thermal power generation, the solar thermal storage material is required to have excellent thermal shock resistance to withstand the process of long-term thermal cycles. In this study, solar thermal storage ceramics were prepared using high calcium and high iron steel slag as the main raw material, adding cordierite and using the pressureless sintering method. The effects of cordierite addition on the physical properties, phase composition, microstructure, thermal storage and thermal shock resistance of the samples were investigated by XRD, SEM and so on. The results show that the addition of cordierite promotes densification and improves thermal shock resistance. The optimal level of addition is 10 %. When the temperature is 1240 °C, the bulk density and bending strength of the B5 (10 wt% cordierite) are 3.03 g cm−3 and 92.52 MPa, respectively. The bending strength of B5 after 30 thermal shock cycles is 97.06 MPa, which is 4.91 % higher than that before 30 thermal shock cycles. The thermal storage density is 867.95 kJ kg−1. This work not only analyzes the feasibility of this material for high-temperature service but also provides a new way for high-value utilization of high calcium and high iron steel slag.