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Full Record for Micrograph 152
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- Micrograph no
- 152
- Brief description
- Barium Hexaferrite
- Keywords
- barium, barium hexaferrite, carbon, ceramic
, ferrite , granule, hard magnet , iron, oxygen - Categories
- Ceramic
- System
- BaO-Fe2O3
- Composition
- BaO . 6Fe2O3
- Standard codes
- Reaction
- Processing
- BaCO3 and Fe2O3 powders are calcined to form BaO.6Fe2O3 and then spray dried to produce granules or controlled spherical agglomerates which pack well during die pressing. After shape forming the green compact is fired at about 1250 °C.
- Applications
- Magnetically hard ferrites (confusingly the general name for magnetic ceramics) have strong permanent magnetisation. Uses are many but include mixing with plastic to provide a flexible strip seal around e.g. refrigerators and in electricity meters to support the rotor to reduce bearing wear.
- Sample preparation
- Polished but unetched.
- Technique
- Reflected light microscopy
- Length bar
- 100 μm
- Further information
- The porosity (dark) level is high since in use strength is not a priority. The original granule size (about 30 micrometre diameter) is easily visualised since extensive intergranular porosity is present.
- Contributor
- Prof W E Lee
- Organisation
- Department of Engineering Materials, University of Sheffield
- Date
- 10/05/02
- Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales