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

DoITPoMS Micrograph Library Full Record for Micrograph 194
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Full Record for Micrograph 194

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Micrograph no
194
Brief description
MgO-C Refractory Brick
Keywords
brick Link to MATTER Glossary entry for brick, carbon, ceramic Link to MATTER Glossary entry for ceramic, composite material Link to MATTER Glossary entry for composite material, graphite Link to MATTER Glossary entry for graphite, magnesia, refractory Link to MATTER Glossary entry for refractory
Categories
Ceramic, Composite
System
MgO-C
Composition
MgO 50-90, C 8-37 (wt%), remainder Al, Si metal addition
Standard codes
Reaction
Processing
Natural graphite flakes are mixed with MgO aggregate, metal powder and phenolic resin binder. Bricks are pressed and heated to cure and decompose the resin before in situ firing in reducing atmosphere. The metal additions getter oxygen forming ceramic phases at high temperature so protecting the carbon from oxidation and acting as a bond improving hot strength.
Applications
Linings of primary steelmaking furnaces, all areas of basic oxygen furnaces and at the slag line of electric arc furnaces.
Sample preparation
Polished and unetched.
Technique
Reflected light microscopy
Length bar
200 μm
Further information
This micrograph is of a specimen which has been pressed parallel with your nose (into the screen) during fabrication, with the bright graphite flakes appearing face on. Compare with micrograph 193.

The MgO grain is polycrystalline and porous. The anisometric microstructure means the brick properties are anisotropic and so the bricks orientation must be carefully controlled on installation. These are true composite materials using ceramic (MgO, natural graphite), metal (Si, Al additives), and polymer (phenolic resin) components.
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
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