Digitalfire Ceramic Materials Database

Alumina Hydrate

Formula: Al₂O₃.3H₂O

Chemistry %

Al2O3

65.39

Volatiles %

LOI

34.61

DENS - Density (Specific Gravity)	2.42
XREF - Index of Refraction	1.57
HMOH - Hardness (Moh)	2.5-3.5
DNLP - Density, loose packed (lbs/cu fut)	1.0-1.4
MLPT - Melting Point (MP)	3000C D
SAMG - Surface Area (m2/gm)	0.1-0.15
BDGC - Bulk Density g/cc (Packed)	1.4-1.7

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 alpha aluminum trihydroxide (with an LOI of 34%). 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 added 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).

Mechanisms

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

Out Bound Links

(URLs) Alumina Manufacturing Process
http://www.qal.com.au/a_process/process3.html
(Materials - Parent) Alumina - Al2O3
Aluminum Oxide
(Hazards - General) Alumina Toxicology
An overview of the hazards of alumina materials in...
(Typecodes) 1: GNM - Generic Material
(Typecodes) 1: ALM - Alumina
(MDT - Member) Glass Industry
The materials included in this MDT were selected i...
(MDT - Member) Crystal Glazes
These materials are specially defined for makers o...
(MDT - Member) UK
We are working on this database and would apprecia...
(MDT - Member) Ron Roy
This is the traditional Ron Roy materials file. He...
(Minerals - Parent mineral) Gibbsite
An ore of aluminum.
(Minerals - Parent mineral) Bauxite
The main ore from which alumina oxide products are...
(MDT - Member) North America
The decision about what materials to include in th...
(MDT - Member) New Zealand
We are working on this database and would apprecia...
(MDT - Member) Latin and South America
Latin America and South America. We are working on...
(MDT - Member) Europe
Countries of Eastern Europe and former Soviet Unio...
(MDT - Member) Australia
We are working on this database and would apprecia...
(MDT - Member) Asia
All of Asia including Turkey, Russia, Indosnesia, ...
(MDT - Member) Africa
All of continental Africa. We are working on this ...
(URLs) Data sheet for alumina trihydrate (fancy name for alumina hydrate)
http://www.akrochem.com/pdfs/fire/X-alumina%20trih...

In Bound Links

(Materials - Related) Calcined Alumina - Al2O3 - Aluminum oxide
Alumina Calcined, Calcnd Alum, Ground Alumina, Corundum
(Materials - Related) Tabular Alumina - Al2O3
(Materials - Parent) Pechiney Alumina
(Oxides - Material source) Al2O3 - Aluminum Oxide, Alumina

Pictures
Corundum On Feldspar

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