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

DoITPoMS Micrograph Library Full Record for Micrograph 190

Full Record for Micrograph 190

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Micrograph no
190
Brief description
Aluminous Electrical Porcelain
Keywords
ceramic Link to MATTER Glossary entry for ceramic, clay, feldspar Link to MATTER Glossary entry for feldspar, grain and bond, insulator, porcelain, quartz, vitreous
Categories
Ceramic
System
Triaxial (i.e. clay/flux/filler) porcelain
Composition
Ball clay 30 , china clay 10, potash feldspar 20, silica sand 20, calcined alumina 20 (wt%)
Standard codes
Reaction
Processing
Fired at approx 1300ºC to induce vitrification or substantial melting.
Applications
Used for electrical insulators.
Sample preparation
Polished and etched 3 min in 5% HF solution.
Technique
Scanning electron microscopy (SEM)
Length bar
10 μm
Further information
The microstructure of porcelain is surprisingly complex. Quartz silica grains (Q) are beginning to dissolve and show solution rims (R) of glassy material. The alumina particles are not dissolving at this firing temperature. The relicts of the starting clays contain fine primary mullite in glass (P) while feldspar relicts contain elongated secondary mullite needles.
Contributor
Prof W E Lee
Organisation
Department of Engineering Materials, University of Sheffield
Date
02/09/02
Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales