UCAR metal-ceramic
LT-l is a combination of a metal matrix, chromium, and a pure ceramic phase,
aluminium oxide (alumina). It is composed 65% by volume of metallic phase and
35% by volume of ceramic phase. The material is slip cast, sintered, and then
oxidised. Although the exact nature of the bond between the phases is not known,
a physical-chemical bond may be formed through the sharing of oxygen by the chromium
and the alumina. There is no evidence of wetting or solution.
Slip casting is a process whereby finely divided solid constituents are put
into liquid vehicle to form a colloidal suspension called a "slip".
This slip or suspension is poured into a porous plaster mould. The mould absorbs
the liquid leaving the solids in the shape of the mould cavity.
Axial ID holes are obtained by drain casting which involves draining off the
excess 'slip" after the wall has built up to the desired thickness.
Properties
UCAR metal-ceramic
LT-l possesses several attractive properties.
1. Non-wetted by most molten metals and basic slags.
2. Good erosion resistance.
3. Good abrasion resistance.
4. Good oxidation resistance.
5. Good thermal conductivity.
6. High strength above the temperature at which most material melt or otherwise
fail.
7. Merchantable by most standard shop practices.
Recommended Applications
The following applications are suited to UCAR
metal-ceramic LT-l
1. Molten copper and brass to 1150°C intermittent and continuous immersions.
2. Corrosive SO2 and SO3 gas (to 1375°C) and SO3
and HF gas (to 1100°C).
3 Open hearth furnace checker chambers to 1350°C.
4. Steel mill soaking pits to 1375°C.
5. Pelletising charter of Taconite refining operation to 1150°C.
6. Molten zinc to 875°C.
7. Molten lead to 350°C.
8. Basic steels and slags to 1735°C (intermittent) and 1375°C (continuous)
in open hearth and general foundry practices.
9. Calcining kilns to 1200°C.
10. Barium titanate (barium oxide service) to 1200°C.
11. Magnesium oxide calcining kilns
12. Fluid bed cement process with severe corrosion and temperature to 1315°C
(fluid method of producing builders cement).
13. Gas and ethylene cracking atmosphere.
14. Atmosphere directly above burning sodium (975-1375°C)
15. Oil fired furnace chambers.
16. Atmosphere directly above molten glass in an open hearth glass furnace
17. Molten silver solder.
16. Molten tin.
19. Borax flux
20. Copper matte.
21. Boiling sulphuric acid - 97%.
22. Blast furnace stove dome and bustle pipes.
