Full Record for Micrograph 190

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Micrograph no: 190
Brief description: Aluminous Electrical Porcelain
Keywords: ceramic , clay, 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 1300ÂºC 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-NonCommercial-ShareAlike 4.0 International