Molecular simulation and experimental characterization of the effect of hydroxides on the properties of hot hardening sodium silicate bonded ceramic sand

• Published in: Ceramics international 2023-08, Vol.49 (16), p.27327-27336
• Main Authors: Song, Lixing, Du, Xueshan, Li, Yiwei, Sun, Yufu
• Format: Article
• Language: English
• Subjects: Bonded bridge; Collapsibility; Sodium silicate; SSBCS; Strength
• ISSN: 0272-8842
• DOI: 10.1016/j.ceramint.2023.05.287

Although sodium silicate bonded sand (SSBS) has low cost, its strength and collapsibility are poor. Consequently, it is necessary to add modifiers to solve this problem. In this paper, the adsorption of hydroxides (NaOH, KOH, and LiOH) on the surface of sodium silicate was studied by density functional theory (DFT) calculations, and its effect on the properties of hot hardening sodium silicate bonded ceramic sand (SSBCS) was investigated by experimental characterization. The simulation results showed that the adsorption energy of LiOH on the surface of sodium silicate was the lowest and the modification effect was the best. When the optimal addition of LiOH was 0.2%, the instant strength (σ0) and 24 h strength (σ24h) of SSBS increased by 96.7% and 23.9% and the residual strength (σ800°C) decreased by 40.1%. The bonded bridge of SSBCS was smoother and tighter at room temperature, increasing instant strength and 24 h strength. During heating and cooling at 800 °C, there were some cracks and holes appeared on the surface of the bonded bridge, which improved the collapsibility of SSBCS.