• Ultra low and negative expansion glass–ceramic materials produced from pyrophyllite and blast furnace slag

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    • Keywords

       

      Glass–ceramic; Li2O–Al2O3–SiO2; blast furnace slag; pyrophyllite.

    • Abstract

       

      Ultra low and negative expansion glass–ceramic materials have been obtained from pyrophyllite and blast furnace slag. The batch composition was modified with the addition of lithium carbonate, hydrated alumina, boric acid and nucleating agent (titania). The batch was melted at 1400°C followed by casting in the form of bars and annealed at 510°C for 4 h. The annealed specimens were subjected to heat treatment at predetermined temperatures selected from DTA study of the parent glass. Thermal expansion measurement and X-ray diffraction analysis revealed that the specimen nucleated at 545°C for 4 h and crystallized at 720°C for 2 h which resulted in negative coefficient of thermal expansion [(–) 9 to (–) 2 × 10$^{-7}/{}^\circ $C] over the temperature range (30–600°C) due to the formation of 𝛽-eucryptite while other heating schedule showed the formation of spodumene and lithium aluminium silicates. The samples showed excellent flexural strength value and varied in the range 120–200 MPa depending upon the phases present.

    • Author Affiliations

       

      S Mandal1 S Chakrabarti1 S Ghatak1 S K Das1

      1. Clay and Traditional Ceramics Division, Central Glass and Ceramic Research Institute, Kolkata 700 032, India
    • Dates

       
  • Bulletin of Materials Science | News

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