Effect of Pyrolusite on the Densification Behaviour of Alumina-kaolin System: Towards Sintered High Alumina Refractory Aggregate
1 Materials Science Centre, Indian Institute of Technology, 721302 Kharagpur/India
2 Refractory Division, CSIR-Central Glass and Ceramic Research Institute, 700032 Kolkata/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
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