Formation characteristics of sodium calcium silicate compounds based on the solid-state reaction. Issue 18 (15th September 2022)

• Record Type: Journal Article
• Authors: Pei, Jiannan; Pan, Xiaolin; Xu, Dezhuang; Zhang, Caiwei; Yu, Haiyan; Tu, Ganfeng
• Is Part Of: Ceramics international. Volume 48:Issue 18(2022)
• Page Start: 25958
• Page End: 25967
• Publication Date: 2022-09-15
• Subjects: Sodium calcium silicate -- Calcination -- Formation thermodynamics -- Crystal structure -- Stability; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.05.275
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: The formation thermodynamics, phase transition and stability of sodium calcium silicate compounds under different calcination parameters in the Na2 O–CaO–SiO2 system were studied using XRD, FTIR and SEM-EDS methods. As the Na2 O/SiO2 ratio increases from 0.3 to 0.7 when the CaO/SiO2 ratio is 1.0, the formation sequence of sodium calcium silicate compounds is Na2 Ca3 Si2 O8 →Na6 Ca3 Si6 O18 →Na2 Ca2 Si2 O7 →Na2 CaSiO4 ; as the CaO/SiO2 ratio increases from 0.3 to 1.2 when the Na2 O/SiO2 ratio is 0.5, the formation sequence is Na6 Ca3 Si6 O18 →Na2 Ca2 Si2 O7 →Na2 Ca3 Si2 O8 . As the most stable sodium calcium silicate compound, Na6 Ca3 Si6 O18 forms by the solid-state reaction of preformed Na2 SiO3 with CaO and SiO2, while increasing the calcination temperature and holding time can promote its crystal stability. The decomposition of Na6 Ca3 Si6 O18 in sodium aluminate solution follows the mixed control of the film diffusion and chemical reaction, and the corresponding activation energy is between 40 and 41 kJ/mol.