To understand the role of mullite powder synthesis method on the microstructural aspects and mechanical properties of the consolidated samples, this powder was prepared with two methods including sol–gel technique and direct reaction of alumina and kaolin (A–K mullite). The microstructural studies showed that the particle size of mullite powders synthesised with sol–gel method is lower than the mullite prepared from direct reaction. The spark plasma sintering (SPS) method was used for the consolidation of the samples. The scanning electron microscopy/energy-dispersive X-ray analysis showed that the samples prepared from sol–gel powder after the SPS process contain lower porosity and better compositional homogeneity compared with A–K mullite sample consolidated in a similar condition. The bending and hardness (H) tests results confirmed the better performance of sol–gel samples which is attributed to its lower porosity and better microstructural homogeneity.

References

1. 1)
  - 11. Mukhopadhyay, A., Basu, B.: ‘Consolidation–microstructure–property relationships in bulk nanoceramics and ceramic nanocomposites: a review’, Int. Mater. Rev., 2007, 52, (5), pp. 257–288 (doi: 10.1179/174328007X160281).
2. 2)
  - 8. Hillig, W.B., Musikant, S.: ‘Mullite by reactive hot pressing’ (United States Patents, 1987, Patent No. 4640904).
3. 3)
  - 7. Kong, L.B., Zhang, T.S., Chen, Y.Z., et al: ‘Microstructural composite mullite derived from oxides via a high-energy ball milling process’, Ceram. Int., 2004, 30, (7), pp. 1313–1317 (doi: 10.1016/j.ceramint.2003.12.022).
4. 4)
  - 1. Osendi, M.I., Baudín, C.: ‘Mechanical properties of mullite materials’, J. Eur. Ceram. Soc., 1996, 16, (2), pp. 217–224 (doi: 10.1016/0955-2219(95)00133-6).
5. 5)
  - 5. Brinker, C.J., Scherer, G.W.: ‘Sol–gel science: the physics and chemistry of sol–gel processing’ (New York, USA, Academic press, 1990).
6. 6)
  - 10. Zhang, G., Wang, Y., Fu, Z., et al: ‘Transparent mullite ceramic from single-phase gel by spark plasma sintering’, J. Eur. Ceram. Soc., 2009, 29, (13), pp. 2705–2711 (doi: 10.1016/j.jeurceramsoc.2009.04.012).
7. 7)
  - 2. Ebadzadeh, T.: ‘Formation of mullite from precursor powders: sintering, microstructure and mechanical properties’, Mater. Sci. Eng. A, 2003, 355, (1–2), pp. 56–61 (doi: 10.1016/S0921-5093(03)00049-2).
8. 8)
  - 14. Kamiya, H., Suzuki, H., Ichikawa, T., et al: ‘Densification of sol–gel-derived mullite ceramics after cold isostatic pressing up to 1 GPa’, J. Am. Ceram. Soc., 1998, 81, (1), pp. 173–179 (doi: 10.1111/j.1151-2916.1998.tb02310.x).
9. 9)
  - 3. Cividanes, L.S., Campos, T.M.B., Rodrigues, L.A., et al: ‘Review of mullite synthesis routes by sol–gel method’, J. Sol–Gel Sci. Technol., 2010, 55, (1), pp. 111–125 (doi: 10.1007/s10971-010-2222-9).
10. 10)
  - 12. Olevsky, E.A., Froyen, L.: ‘Impact of thermal diffusion on densification during SPS’, J. Am. Ceram. Soc., 2009, 92, (s1), pp. S122–S132 (doi: 10.1111/j.1551-2916.2008.02705.x).
11. 11)
  - 6. Amutharani, D., Gnanam, F.: ‘Low temperature pressureless sintering of sol–gel derived mullite’, Mater. Sci. Eng. A, 1999, 264, (1), pp. 254–261 (doi: 10.1016/S0921-5093(98)01094-6).
12. 12)
  - 15. Kimura, H.: ‘Science and new applications of electric discharge consolidation’, J. Jpn. Soc. Powder Powder Metall. (Japan), 1998, 45, (11), pp. 1050–1054 (doi: 10.2497/jjspm.45.1050).
13. 13)
  - 17. Figiel, P., Rozmus, M., Smuk, B.: ‘Properties of alumina ceramics obtained by conventional and non-conventional methods for sintering ceramics’, J. Achievements Mater. Manuf. Eng., 2011, 48, (1), pp. 29–34.
14. 14)
  - 13. Ismail, M., Nakai, Z., Sōmiya, S.: ‘Microstructure and mechanical properties of mullite prepared by the sol–gel method’, J. Am. Ceram. Soc., 1987, 70, (1), pp. C-7–C-8 (doi: 10.1111/j.1151-2916.1987.tb04857.x).
15. 15)
  - 16. Masao, T.: ‘Trends in advanced SPS spark plasma sintering systems and technology’, functionally gradient materials and unique synthetic processing methods from next generation of powder technology’, Soc. Powder Technol., Japan, 1993, 30, (11), pp. 790–804 (doi: 10.4164/sptj.30.11_790).
16. 16)
  - 9. Ghahremani, D., Ebadzadeh, T., Maghsodipour, A.: ‘Spark plasma sintering of mullite: relation between microstructure, properties and spark plasma sintering (SPS) parameters’, Ceram. Int., 2015, 41, (5), pp. 6409–6416 (doi: 10.1016/j.ceramint.2015.01.078).
17. 17)
  - 4. Janackovic, D., Jokanovic, V., Kostic-Gvozdenovic, L., et al: ‘Synthesis of mullite nanostructured spherical powder by ultrasonic spray pyrolysis’, Nanostruct. Mater., 1998, 10, (3), pp. 341–348 (doi: 10.1016/S0965-9773(98)00074-9).

Effect of mullite synthesis methods on the spark plasma sintering behaviour and mechanical properties

References

Related content