Alumina Hydrate

Disapore, Gibbsite, Bauxite

Chemistry

Al2O3

65.390

Volatiles

LOI

34.610

Links to Other Materials

Alumina - Parent
Calcined Alumina - Related
Tabular Alumina - Related
Cache

Hazards

Aluminosis

Miscellaneous

Family: Alumina
Region: North America
Mined At: Unspecified
Raw Mineral: No
Generic: Yes

Notes

Hydrated alumina contains significant water in its crystal structure. There are differing water contents depended on the type of alumina hydrate, but the main refined article of commerce in the market is known as gibbsite or alpha aluminum trihydroxide (Al2O3.3H2O with an LOI of 34%). It is processed from Bauxite ore (Al2O3.2H2O with an LOI of 25.0%) or Diaspore (Al2O3.H2O with an LOI of 14.3%). If you are unsure about the alumina hydrate you have in stock you can do a simple LOI test.

Hydrated aluminas are fine granular white powders that have good flow properties. As with any form of alumina, this material has a very high melting temperature. It can be useful in glazes as a source of aluminum oxide, however the powder must be very fine. The hydrated version of alumina stays in suspension better in glaze slurries and has better adhesive qualities. Also using hydrated alumina in glazes and glass can promote the fining operation of coalescing and removing finely dispersed gas bubbles. Small additions of fine alumina hydrate to a glaze can also enhance the color of Cr-Al pinks. Larger additions of fine material can impart matteness if the glaze is able to take it into solution (sourcing alumina from kaolin and frits may be more practical).

Properties

Glaze Opacifier - White
Alumina hydrate promotes opacity in enamels and glazes by generating gas bubbles in the glaze melt.

Data

Specific Gravity: 2.42
Melting Point (MP): 3000C D
Hardness (Moh): 2.5-3.5
Bulk Density g/cc: 1.4-1.7
Density (loose packed): 1.0-1.4
Surface Area (m2/gm): 0.1-0.15
Index of Refraction: 1.57

URLs

Alumina Manufacturing Process - http://www.qal.com.au/a_process/process3.html

Suppliers

Generic

Authors

Tony Hansen (Owner)

Pictures

Corundum On Feldspar

XML

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<oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="65.390" tolerance=""/>
</oxides>
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</volatiles>
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<hazard name="Aluminosis"/>
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<notes>
<note>Hydrated alumina&nbsp;contains significant water in its crystal structure. There are differing water contents depended on the type of alumina hydrate, but the main refined article of commerce in the market is known as gibbsite or alpha aluminum trihydroxide (Al2O3.3H2O with an LOI of 34%). It is processed from Bauxite ore (Al2O3.2H2O with an LOI of 25.0%) or Diaspore (Al2O3.H2O with an LOI of 14.3%). If you are unsure about the alumina hydrate you have in stock you can do a simple LOI test.<br />
<br />
Hydrated aluminas are fine granular white powders that have good flow properties. As with any form of alumina, this material has a very high melting temperature. It can be useful in glazes as a source of aluminum oxide, however the powder must be very fine. The hydrated version of alumina stays in suspension better in glaze slurries and has better adhesive qualities. Also using hydrated alumina in glazes and glass can promote the fining operation of coalescing and removing finely dispersed gas bubbles. Small additions of fine alumina hydrate to a glaze can also enhance the color of Cr-Al pinks. Larger additions of fine material can impart matteness if the glaze is able to take it into solution (sourcing alumina from kaolin and frits may be&nbsp;more practical).</note>
</notes>
<testdata>
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<testitem testname="3" value="3000C D"/>
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</testdata>
<pictures>
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</material>

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