Description of some refractory
Fireclays
Common fire clays contain 25 to 45% Al2O3 and 50- 80% SiO2. Clays with higher Al2O3 are higher alumina refractories.
Properties
- Porosity varies from 8 to 24% depending on the firing temperature.
- At high temperatures fire clay refractory combine with alkalis such as soda and potash.
- Cold crushing strength is 950 kg/cm2 at 20oC and decreases drastically at 800
 to 555 .
| |
Al2O3 (%) |
Refractoriness |
Medium duty |
30 - 32 |
1665oC |
High duty |
38 - 40 |
1700 - 1717oC |
Super duty |
42 – 45 |
1743 - 1763 oC |
|
Uses: Furnaces, regenerators, ovens, and kilns.
High alumina refractories:
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