Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Micrograph Library Full Record for Micrograph 150

Full Record for Micrograph 150

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Micrograph no
Brief description
Alumina-zirconia-silica (AZS) refractory brick
alumina Link to MATTER Glossary entry for alumina, aluminium Link to MATTER Glossary entry for aluminium, brick Link to MATTER Glossary entry for brick, ceramic Link to MATTER Glossary entry for ceramic, dendrite Link to MATTER Glossary entry for dendrite, eutectic Link to MATTER Glossary entry for eutectic, glass Link to MATTER Glossary entry for glass, oxygen Link to MATTER Glossary entry for oxygen, silica, silicon Link to MATTER Glossary entry for silicon, zirconia, zirconium
Al2O3 50, ZrO2 32, SiO2 15 (wt%), + trace alkalis
Standard codes
Melt oxide powders in electric arc furnace above 1800C , pour into moulds.
Liquid contact areas of glass tanks.
Sample preparation
Polished but unetched.
Reflected light microscopy
Length bar
300 μm
Further information
On cooling the ceramic liquid precipitates primary ZrO2 dendrites (white), grey corundum (Al2O3) and a ZrO2/Al2O3 eutectic while glass solidifies from the remaining liquid (slightly darker than the corundum). The composition of this glass is carefully controlled so that it is fluid enough to accommodate the tetragonal to monoclinic ZrO2 transition n heating the glass tank to use temperature. The AZS microstructure is carefully designed so that the alumina dissolves in the tank glass (soda-lime-silica, SLS) leaving a viscous alumina rich layer which protects the refractory. It can survive 12 years continuous use in direct contact with fluid, corrosive SLS liquid at temperatures up to 1500 °C.
Prof W E Lee
Department of Engineering Materials, University of Sheffield
Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales