Mullite Refractories from Clay-Bauxite or Quartz-Bauxite Mixes

Abstract

Investigations were undertaken to study the properties of mullite refractories from Katni and Shevroy bauxites with addition of Jabalpur fire-clay or quartz. Mullite was estimated by chemical analysis and confirmed by X-ray and petrographic examination. Refractories hewing 80–90 per cent mullite could be prepared out of these mixes after firing at temperatures 1500°-1600°C. In spite of high mullite content the porosity of these refractories was very high (35–48 per cent) and the refractoriness under load particularly initial softening point (Ta) was rather low (1400°-1600°C). These may be due to incipient growth of mullite crystals and lack of inter-crystalline bond.