Alumina-Carbon Refractory Castables Containing Calcium-Aluminate Coatings on Graphite

H. Acharjee, A. Chakraborty, R. Halder, S. Mukhopadhyay, S. Moitra

Department of Chemical Technology,Ceramic Engin. Division, University of Calcutta/Kolkata – 700009/India


Volume 8, Issue 4, Pages 79 - 84


The physical properties namely bulk density, apparent porosity, cold crushing strength of carbon-containing high alumina based refractory castable containing both natural and modified graphites (94 % fixed carbon) have been evaluated within the temperature region 110–1500 °C. The densification behaviour of graphite-free and graphite-containing castable matrices has been characterized too by their thermal and thermomechanical characteristics up to 1500 °C. The role of coated graphite on improved performance of the refractory ceramics was explored by thermogravimetry, X-ray diffraction, microstructure and thermal shock resistance studies. It is suggested that the hydrophilic thin film containing calcium aluminate phases encouraged graphite retention in castable matrix.


graphite, calcium aluminate, refractory castable


[1] Stein, V.; Aneziris, C.G.: Low carbon carbon-bonded alumina refractories for structural components in steel technology. J. Ceram. Sci.Technol. 5 (2014) [2] 115–124 [2] Lee, W.E.; Zhang, S.: Improving the water-wettability and oxidation resistance of graphite using Al2O3/SiO2 sol-gel coatings. J. Europ. Ceram. Soc. 23 (2003) 1215–1221 [3] Zhang, S.; Liu, X.: Low temperature preparation of titanium carbide coatings on graphite flakes from molten salts. J. Amer. Ceram. Soc. 91 (2008) 667–670 [4] Rigaud, M.; et al.: Mechanical properties up to 1100 °C of Al2O3-MgO extended graphite pellet castables reinforced with steels. Ceram. Int. 35 (2009) 359–362 [5] Saberi, A.; et al.: Improving the quantity of nanocrystalline MgAl2O4 spinel coating on graphite by a prior oxidation reaction on the graphite surface. J. Europ. Ceram. Soc. 28 (2008) 2011–2017 [6] Yilmaz, S.; et al.: Synthesis and characterization of boehmitic alumina coated graphite by sol-gel method. Ceram. Int. 35 (2009) [5] 2029–2034 [7] Mukhopadhyay, S.; et al.: Spinel-coated graphite for carbon containing refractory castables. J. Amer. Ceram. Soc. 92 (2009) [8] 1895–1900 [8] Mukhopadhyay, S.: Nanoscale calcium aluminate coated graphite for improved performance of alumina based mono lithic refractory composite. Mater. Res. Bull. 48 (2013) 2583–2588 [9] Mukhopadhyay, S.: Improved sol-gel spinel (MgAl2O4) coatings on graphite for application in carbon containing high alumina castables. J. Sol-Gel Sci. Technol. 56 (2010) 66–74 [10] Dutta, S.; et al.: Significant improvement of refractoriness of Al2O3–C castables containing calcium aluminate nano-coatings on graphite. Ceram. Int. 40 (2014) 4407–4414 [11] Mukhopadhyay, S.; et al.: In depth studies on cementitious nanocoatings on graphite for its contribution in corrosion resistance of alumina based refractory composite. Ceram. Int. 41 (2015) 11999–12010 [12] Mukhopadhyay, S.; Dutta, S.: Comparison of solid state and sol-gel derived calcium aluminate coated graphite and characterization of prepared refractory composite. Ceram. Int. 38 (2012) 4997–5006 [13] Mukhopadhyay, S.; Das, G.; Biswas, I.: Nanostructured cementitious sol gel coating on graphite for application in monolithic refractory composites. Ceram. Int. 38 (2012) 1717–1724 [14] Goodrich, H.R.: Spalling and loss of compressive strength of firebrick. J. Amer. Ceram. Soc. 10 (1927) 784–794 [15] Mukhopadhyay, S.; et al.: Thermal and thermomechanical characteristics of monolithic refractory composite matrix containing surface-modified graphite. Ceram. Int. 42 (2016) 6015–6024 [16] Goktas, A.A.; Weinberg, M.C.: Preparation and crystallization of sol-gel calcia-alumina compositions. J. Amer. Ceram. Soc. 74 (1991) [5] 1066–1070 [17] Uberoi, M.; Risbud, S.S.: Processing of amorphous calcium aluminate powders at <900 °C. J. Amer. Ceram. Soc. 73 (1990) [6] 1768–1770 [18] Douy, A.; Gervais, M.: Crystallisation of Amorphous precursors in the calcia-alumina system: A differential scanning calorimetry study. J. Amer. Ceram. Soc. 83 (2000) 70–76 [19] Gulgun, M.A.; et al.: Chemical synthesis and characterization of calcium aluminate powders. J. Amer. Ceram. Soc. 77 (1994) 531–539 [20] Simonin, F.; et al.: Thermomechanical behavior of high-alumina refractory castables with synthetic spinel additions. J. Amer. Ceram. Soc. 83 (2000) [10] 2481–90


Göller Verlag GmbH