Effect of Pyrolusite on the Densification Behaviour of Alumina-kaolin System: Towards Sintered High Alumina Refractory Aggregate
1 Refractory Division, CSIR-Central Glass and Ceramic Research Institute, 700032 Kolkata/India
2 Materials Science Centre, Indian Institute of Technology, 721302 Kharagpur/India
Volume 6, Issue 1, Pages 61 - 68
In the present study, sintered high alumina aggregates have been produced by reaction sintering of a mixture of 85 mass-% calcined alumina and 15 mass-% kaolin with (coded as HA2) or without (coded as HA1) pyrolusite mineral addition. Pyrolusite of different concentration (1–5 mass-%) was gradually added to the above mix and compact samples produced by common ceramic processing were heated for densification at various temperature. The densification studies revealed that HA2 sample achieved 93 % densification (3,53 g/cm3) at 1450 °C in presence of pyrolusite while HA1 sample achieved 88 % densification (3,33 g/cm3) at 1650 °C without pyrolusite addition. The sintered aggregates were also subjected to pore size distribution, phase and microstructural evolution. Presence of well developed corundum and mullite crystals were found in HA1 whereas HA2 contain only corundum as major phase. Pyrolusite was found to promote grain growth and dissolution of secondary phaseat 1450 °C in HA2.
high alumina, pyrolusite, densification, refractory aggregate
 Tripathi, H.S.; Banerjee, G.: Effect of chemical composition on sintering and properties of Al2O3-SiO2 system. Ceram. Int. 25 (1999)  19–25  Tripathi, H.S., Das, S.K.; Banerjee, G.: Thermal shock behavior of high alumina aggregates derived from sillimanite beach sands with or without doping. Ceram. Int. 26 (2000) 1–6  Das, S.K.; Mandal, P.K.; Sarkar, R.: Effect of synthetic aggregate on alumina castables. Amer. Ceram. Soc. Bull. 82 (2003)  911–916  Kumar, S.; Das, S.K.; Daspoddar, P.K.: Synthesis of mullite aggregates from fly ash: Effect of thermo-mechanical behavior of low cement castable. Brit. Trans. Ceram. 103 (2004)  176– 180  Singh, K.K.; Chatterjee, B.: Development of refractory synthetic aggregate. Proc. of Int. Seminar on Refractories, Feb. 1992, 36–43  Gungor, A.; Celikeioglu O.; Sahin, S.: The physical and mechanical properties of aluminabased ultralow cement castable refractories; Ceramics Int. 38 (2012) 4189–4194  Kakroudi, M.G.; et al.: Effect of thermal treatment on damage mechanical behavior of refractory castables: Comparison between bauxite and andalusite aggregates. J. Europ. Ceram. Soc. 28 (2008) 2471–2478  Das, S.K.; Ghosh, A.; Banerjee, G.: Indian Refractories: Raw materials, production and research – An overview. refractories WORLDFORUM 2 (2010)  29–34  Singh, A.: Raw materials for Indian refractory industry. IRMA journal XXX (2008) 126–128  Ghosh, A.; et al.: Research on refractory raw materials at CGCRI: A review. Iron and steel review, 18 august 2009, 18–26  Aneziris, C.G.: Recent trends in refractories and development. Proc. of IREFCON 2008 Conf. Kolkata  Das, S.K.: New development of wear resistant high alumina aggregates for application in monolithic castable. Proc. of UNITECR 2011, Japan, 2-B2-15  Erkalfa, H.: et al.: The densification and microstructural development of Al2O3 with manganese oxide addition. J. Europ. Ceram. Soc. 15 (1995) 165–171  Rossi, G.; Burke, J.E.; Influence of additives on the microstructure of sintered Al2O3. J. Amer. Ceram. Soc. 56 (1973) 543–549  Keski, J.R.; Cutler, I.B.: Effect of manganese oxide on sintering of alumina. J. Amer. Ceram. Soc. 48 (1965)  653–654  Harmer, R.D.; Roberts, E.W.; Brook, R.J.: Rapid sintering of pure and doped α-Al2O3. Trans. Brit. Ceram. Soc. 78 (1979) 22–25  Smothers, W.J.; Reynolds, H.J.: Sintering and grain growth of alumina. J. Amer. Ceram. Soc. 37 (1954)  588–595  Das, S.K.; et al.: Alumina based ceramic compositions for wear resistant applications. Industrial Ceramics 13 (1993) [3/4] 155–158  Dörre, E.; Hübner, H.: Alumina. Processing, properties, and applications. Berlin, Heidelberg, New York, Tokyo 1984  Ray, A.K.; et al: Indentation hardness and fracture toughness of alumina based ceramics. Interceram 46 (1997)  184–187  Yan, W.; Li, N.; Han, B.: High strength, lightweight spinel refractories. Amer. Ceram. Soc. Bull. 84 (2005) 9201–9203
Göller Verlag GmbH