Mineral transition and formation mechanism of calcium aluminate compounds in CaO-Al₂O₃-Na₂O system during high-temperature sintering

Abstract

The mineral transition and formation mechanism of calcium aluminate compounds in CaO-Al₂O₃-Na₂O system during the high-temperature sintering process were systematically investigated using DSC-TG, XRD, SEM-EDS, FTIR, and Raman spectra, and the crystal structure of Na₄Ca₃(AlO₂)₁₀ was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na₄Ca₃(AlO₂)₁₀, CaOAl₂O₃, and 12CaO·7Al₂O₃, and the content of Na₄Ca₃(AlO₂)₁₀ could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na₄Ca₃(AlO₂)₁₀ occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na₄Ca₃(AlO₂)₁₀ was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na₄Ca₃(AlO₂)₁₀ was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol.

Keywords

calcium aluminate / sodium oxide / crystal structure / formation kinetics / sintering

References

[1] Lee NK, Koh KT, Park SH, Ryu GS. Microstructural investigation of calcium aluminate cement-based ultra-high performance concrete (UHPC) exposed to high temperatures. Cem. Concr. Res., 2017, 102, 109.

[2] Zhang YY, Lu W, Qi YH, Zou ZS. Recovery of iron and calcium aluminate slag from high-ferrous bauxite by high-temperature reduction and smelting process. Int. J. Miner. Metall. Mater., 2016, 23(8): 881.

[3] Parreira RM, Andrade TL, Luz AP, Pandolfelli VC, Oliveira IR. Calcium aluminate cement-based compositions for biomaterial applications. Ceram. Int., 2016, 42(10): 11732.

[4] Chen JH, Chen HY, Yan MW, Cao Z, Mi WJ. Formation mechanism of calcium hexaluminate. Int. J. Miner. Metall. Mater., 2016, 23(10): 1225.

[5] Hallstedl B. Assessment of the CaO−Al₂O₃ syseem. J. Am. Ceram. Soc., 1990, 73(1): 15.

[6] Pan XL, Zhang D, Wu Y, Yu HY. Synthesis and characterization of calcium aluminate compounds from gehlenite by high-temperature solid-state reaction. Ceram. Int, 2018, 44(12): 13544.

[7] Verweij H, Saris CMPM. Phase formation in the system Na₂O·Al₂O₃−CaO·A1₂O₃−Al₂O₃ at 1200 °C in air. J. Am. Ceram. Soc., 1986, 69(2): 94.

[8] Zhang D, Zhang W, Sun HL, Wang B. Mineral transition mechanism of calcium aluminate with sodium doping during high-temperature sintering reaction. J. Alloys Compd., 2019, 771, 195.

[9] Yang J, Wang Q, Zhang JQ, Ostrovski O, Zhang C, Cai DX. Effect of Al₂O₃/(B₂O₃ + Na₂O) ratio on CaO−Al₂O₃-based mold fluxes: Melting property, viscosity, heat transfer, and structure. Metall. Mater. Trans. B, 2019, 50(6): 2794.

[10] Shen J, Gong L, Li QX. Structure and antibacterial property of Na₂O doped C₁₂A₇. Chin. J. Inorg. Chem., 2011, 27(2): 353.

[11] Ostrowski C, Żelazny J. Solid solutions of calcium aluminates C₃A, C₁₂A₇ and CA with sodium oxide. J. Therm. Anal. Calorim., 2004, 75(3): 867.

[12] Yu HY, Pan XL, Wang B, Zhang W, Sun HL, Bi SW. Effect of Na₂O on the formation of calcium aluminates in CaO−Al₂O₃−SiO₂ system. Trans. Nonferrous Met. Soc. China, 2012, 22(12): 3108.

[13] Zhang D, Pan XL, Yu HY, Zhai YC. Mineral transition of calcium aluminate clinker during high-temperature sintering with low-lime dosage. J. Mater. Sci. Technol, 2015, 31(12): 1244.

[14] Tian YP, Pan XL, Yu HY, Tu GF. Formation mechanism of calcium aluminate compounds based on high-temperature solid-state reaction. J. Alloys Compd., 2016, 670, 96.

[15] McMillan P, Piriou B. Raman spectroscopy of calcium aluminate glasses and crystals. J. Non-Cryst. Solids, 1983, 55(2): 221.

[16] Kajihara K, Matsuishi S, Hayashi K, Hirano M, Hosono H. Vibrational dynamics and oxygen diffusion in a nanoporous oxide ion conductor 12CaO·7Al₂O₃ studied by ¹⁸O labeling and micro-Raman spectroscopy. J. Phys. Chem. C, 2007, 111(40): 14855.

[17] McMillan P, Piriou B, Navrotsky A. A Raman-spectroscopic study of glasses along the joins silica-calcium aluminate, silica-sodium aluminate, and silica-potassium aluminate. Geochim. Cosmochim. Acta, 1982, 46(11): 2021.

[18] Meiszterics A, Rosta L, Peterlik H, Rohonczy J, Kubuki S, Henits P, Sinkó K. Structural characterization of gel-derived calcium silicate systems. J. Phys. Chem. A, 2010, 114(38): 10403.

[19] Zhang L, Lan R, Petit CTG, Tao SW. Durability study of an intermediate temperature fuel cell based on an oxide-carbonate composite electrolyte. Int. J. Hydrogen Energy, 2010, 35(13): 6934.

[20] Legodi MA, de Waal D, Potgieter JH, Potgieter SS. Rapid determination of CaCO₃ in mixtures utilising FT-IR spectroscopy. Miner. Eng., 2001, 14(9): 1107.

[21] Vyazovkin S, Wight CA. Isothermal and non-isothermal kinetics of thermally stimulated reactions of solids. Int. Rev. Phys. Chem., 1998, 17(3): 407.

[22] Zuzjaková Š, Zeman P, Kos Š. Non-isothermal kinetics of phase transformations in magnetron sputtered alumina films with metastable structure. Thermochim. Acta, 2013, 572, 85.

[23] Cran MJ, Gray SR, Scheirs J, Bigger SW. Non-isothermal depolymerisation kinetics of poly(ethylene oxide). Polym. Degrad Stab., 2011, 96(8): 1497.

[24] Sava BA, Elisa M, Bartha C, Iordanescu R, Feraru I, Plapcianu C, Patrascu R. Non-isothermal free-models kinetic analysis on crystallization of europium-doped phosphate glasses. Ceram. Int., 2014, 40(8): 12387.