Synthesis and characterization of mullite (3Al2O3.2SiO2) sol by sol-gel route using inorganic salts

Sahar Sajjadi Milani; Mahdi Ghassemi Kakroudi; Nasser Pourmohammadi Vafa

doi:10.53063/synsint.2024.44235

Sahar Sajjadi Milani ¹
Mahdi Ghassemi Kakroudi ¹
Nasser Pourmohammadi Vafa ¹

¹ Department of Materials Science and Engineering, University of Tabriz, Tabriz, Iran

https://doi.org/10.53063/synsint.2024.44235

Abstract

Mullite, also referred to as 3Al₂O₃.2SiO₂, is recognized as the only chemically stable intermediate phase in the SiO₂–Al₂O₃ system, as indicated by mineralogical studies. Several synthesis techniques can be employed to obtain mullite. In this research, the synthesis of mullite particles is aimed to be achieved via the sol-gel route using inexpensive materials, specifically silica sol and aluminum nitrate hydrate [(Al(NO₃)₃.9H₂O] as sources for silica and alumina, respectively. The article is organized into two sections which describe and discuss the systematic synthesis of the mullite sol. The first section emphasizes the influence of the stoichiometric values of Al and Si elements on the formation of the mullite phase at 1200 °C. The effects of sintering temperature on the microstructure and composition of the synthesized mullite sol, with a 3:1 alumina-to-silica ratio, are discussed in the following section. This includes pH, density, solid content, particle size distribution, thermal analysis, phase evolution with temperature, nature of bonds, and microstructural analysis. The XRD results for the mullite sol with a 3:1 alumina-to-silica ratio show strong crystalline diffraction peaks of the mullite phase and the absence of a free silica phase at 1200 °C. The solution exhibits a clear, stable, and homogeneous appearance, with a density of 1.17 g/cm³, a pH ranging from 4 to 5, and a solid content of approximately 15%, measured after heating at 1000 °C for 2 h.

Downloads

Download data is not yet available.

Keywords: Mullite, Sol-gel, Inorganic route, Chemical synthesis

References

[1] L.S. Cividanes, T.M.B. Campos, L.A. Rodrigues, D.D. Brunelli, G.P. Thim, Review of mullite synthesis routes by sol–gel method, J. Sol-Gel Sci. Technol. 55 (2010) 111–125. https://doi.org/10.1007/s10971-010-2222-9.

[2] S. Sembiring, W. Simanjuntak, P. Manurung, D. Asmi, I.M. Low, Synthesis and characterisation of gel-derived mullite precursors from rice husk silica, Ceram. Int. 40 (2014) 7067–7072. https://doi.org/10.1016/j.ceramint.2013.12.038.

[3] P. Pialy, N. Tessier-Doyen, D. Njopwouo, J.P. Bonnet, Effects of densification and mullitization on the evolution of the elastic properties of a clay-based material during firing, J. Eur. Ceram. Soc. 29 (2009) 1579–1586. https://doi.org/10.1016/j.jeurceramsoc.2008.09.020.

[4] A. Abdullayev, D. Klimm, F. Kamutzki, A. Gurlo, M.F. Bekheet, AlF3-assisted flux growth of mullite whiskers and their application in fabrication of porous mullite-alumina monoliths, Open Ceram. 7 (2021) 100145. https://doi.org/10.1016/j.oceram.2021.100145.

[5] D. Das, N. Kayal, G.A. Marsola, D.G.Parra. Filho, M.D.M. Innocentini, Recycling of coal fly ash for fabrication of elongated mullite rod bonded porous SiC ceramic membrane and its application in filtration, J. Eur. Ceram. Soc. 40 (2020) 2163–2172. https://doi.org/10.1016/j.jeurceramsoc.2020.01.034.

[6] R. Baranwal, M.P. Villar, R. Garcia, R.M. Laine, Flame Spray Pyrolysis of Precursors as a Route to Nano-mullite Powder: Powder Characterization and Sintering Behavior, J. Am. Ceram. Soc. 54 (2001) 951–961. https://doi.org/10.1111/j.1151-2916.2001.tb00774.x.

[7] X. Song, Y. Ma, J. Wang, B. Liu, S. Yao, et al., Homogeneous and flexible mullite nanofibers fabricated by electrospinning through diphasic mullite sol–gel route, J. Mater. Sci. 53 (2018) 14871–14883. https://doi.org/10.1007/s10853-018-2667-8.

[8] N.M. Khalil, M.B. Hassan, E.M.M. Ewais, F.A. Saleh, Sintering, mechanical and refractory properties of MA spinel prepared via co-precipitation and sol–gel techniques, J. Alloys Compd. 496 (2010) 600–607. https://doi.org/10.1016/j.jallcom.2010.02.123.

[9] L.T. Jurado, R.M.A. Hernandec E. Rocha-Rangel, Sol-Gel Synthesis of Mullite Starting from Different Inorganic Precursors, J. Powder Technol. 2013 (2013) 268070. https://doi.org/10.1155/2013/268070.

[10] H. Tan, Y. Ding, J. Yang, Mullite fibers prepared from an inorganic sol–gel precursor, J. Sol–Gel Sci. Technol. 53 (2010) 378–38. https://doi.org/10.1007/s10971-009-2106-z.

[11] A. Jana, D. Ray, Synthesis and characterization of sol-gel derived monophasic mullite powder, Cerâmics. 66 (2020) 307–313. https://doi.org/10.1590/0366-69132020663792907.

[12] Y. Wang, H. Liu, H. Cheng, J. Wang , Densification behavior and microstructure of mullite obtained from diphasic, Ceram. Int. 40 (2014) 12789–12796. https://doi.org/10.1016/j.ceramint.2014.04.133.

[13] S.S. Milani, M.G. Kakroudi, N.P. Vafa, M.M. Mokhayer, S.H. Gharamaleki, Properties of alumina sol prepared via inorganic route, Ceram. Int. 46 (2020) 9492–9497. https://doi.org/10.1016/j.ceramint.2019.12.210.

[14] S.S. Milani, M.G. Kakroudi, N.P. Vafa, S. Rahro, F. Behboudi, Synthesis and characterization of MgAl2O4 spinel precursor sol prepared by inorganic salts, Ceram. Int. 47 (2021) 4813–4819. https://doi.org/10.1016/j.ceramint.2020.10.051.

[15] A.K. Singh, R. Sarkar, Nano mullite bonded refractory castable composition for high temperature applications, Ceram. Int. 42 (2016) 12937–12945. https://doi.org/10.1016/j.ceramint.2016.05.066.

[16] S. Mukhopadhyay, S. Ghosh, M.K. Mahapatra, R. Mazumder, P. Barick,et al., Easy-to-use mullite and spinel sols as bonding agents in a high-alumina based ultra low cement castable, Ceram. Int. 28 (2002) 719–729. https://doi.org/10.1016/S0272-8842(02)00034-2.

[17] A.K. Singh, R. Sarkar, Development of spinel sol bonded high pure alumina castable composition, Ceram. Int. 42 (2016) 17410–17419. https://doi.org/10.1016/j.ceramint.2016.08.041.

[18] P. Sultana, S. Das, B. Bagchi, A. Bhattacharya, R. Basu, P. Nandy, Effect of size of fly ash particle on enhancement of mullite content and glass formation, Indian Acad. Sci. 34 (2011) 1663–1670. https://doi.org/10.1007/s12034-011-0374-z.

[19] A. Saberi, F.Golestanifard, H. Sarpoolaky, M. Willert-porado, T. Gerdes, R. Simon, Chemical synthesis of nanocrystalline magnesium aluminate spinel via nitrate-citrate combustion route, J. Alloy Compd. 462 (2008) 142–146. https://doi.org/10.1016/j.jallcom.2007.07.101.

[20] S.Biamino, C.Badini, Combustion synthesis of lanthanum chromite starting from water solutions: Investigation of process mechanism by DTA–TGA–MS, J. Eur. Ceram. Soc. 24 (2004) 3021–3034. https://doi.org/10.1016/j.jeurceramsoc.2003.10.005.

[21] S.S. Milani, M.G. Kakroudi, M. Rezvani, The effects of processing technique on formation temperature of calcium aluminate magnesium (CaO.2MgO.8Al2O3), Cryst. Growth. 643 (2024) 17797. https://doi.org/10.1016/j.jcrysgro.2024.127797.

View more references

Cited By