Zinc Oxide
Pure Source Of Zinc
Formula: ZnO
| DENS - Density (Specific Gravity) |
5.6 |
Zinc oxide is a fluffy white to yellow white powder a very fine particle size coupled with high surface area. It is made using one of two processes that produce different densities. The French process vaporizes and oxidizes zinc metal, the American process smelts a coal/zinc sulfide mix and oxidizes the zinc fumes.
Ceramic grades normally employ a larger particle size.
It is soluble in strong alkalies and acids.
It can be an active flux in smaller amounts. It generally promotes crystalline effects and matteness/softness in greater amounts. If too much is used the glaze surface can become dry and the heavily crystalline surface can present problems with cutlery marking. Other surface defects like pitting, pinholing, blistering and crawling can also occur (because its fine particle size contributes to glaze shrinkage during drying and it pulls the glaze together during fusion). Calcined zinc oxides are available and apparently produce less glaze surface defect problems. You can calcine zinc on your own in a bisque kiln, fire it at around 815C. Calcining a mix of zinc and kaolin produces a more workable powder. However calcined zinc tends to rehydrate from atmospheric water (and get lumpy in the process).
Zinc oxide is thermally stable on its own to high temperatures, however in glazes it readily dissolves and acts as a flux. Zinc oxide sublimes at 1800C but it reduces to Zn metal in reduction firing and then boils at around 900C (either causing glaze defects or volatilizing into the atmosphere). Note that electric kilns with poor ventilation often have local reduction.
While it might seem that zinc would not be useful in reduction glazes, when zincless and zinc containing glazes are compared it is often clear that there is an effect (e.g. earlier melting). Thus some zinc has either remained or it has acted as a catalyst.
The use of zinc in glazes is limited by its price, its hostility to the development of certain colors and its tendency to make glazes more leachable in acids (although zinc itself is not considered a hazardous substance).
Zinc oxide is used in glass, frits, enamels and ferrites. Zinc oxide is also used in large quantities in the rubber and paint industries; in insulated wire, lubricants, and advanced ceramics.
Mechanisms
Out Bound Links
- (URLs - Technical inforamtion)
Zinc Oxide at Wikipedia
http://en.wikipedia.org/wiki/Zinc_oxide - (Hazards - General)
Zinc Compounds
The hazards of these materials in the ceramic indu... - (Minerals - Parent mineral)
Sphalerite
The main ore of zinc. - (Typecodes)
1: GNM - Generic Material
- (Typecodes)
1: FLS - Flux Source
- (MDT - Member)
Latin and South America
Latin America and South America. We are working on... - (MDT - Member)
Generic
Generic for building a completely custom MDT. Only... - (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, ... - (Temperatures - Unspecified)
Zinc oxide boils and volatilizes (850-950)
- (MDT - Member)
Africa
All of continental Africa. We are working on this ... - (MDT - Member)
New Zealand
We are working on this database and would apprecia... - (MDT - Member)
North America
The decision about what materials to include in th... - (MDT - Member)
Ron Roy
This is the traditional Ron Roy materials file. He... - (MDT - Member)
UK
We are working on this database and would apprecia... - (MDT - Member)
Crystal Glazes
These materials are specially defined for makers o... - (MDT - Member)
Enamel Industry
We are working on this database and would apprecia... - (MDT - Member)
Glass Industry
The materials included in this MDT were selected i...
In Bound Links
XML for Import into INSIGHT
<?xml version="1.0" encoding="UTF-8"?>
<material name="Zinc Oxide" descrip="Pure Source Of Zinc" searchkey="ZnO, Zincite" loi="0.00" casnumber="8051-03-4">
<oxides>
<oxide symbol="ZnO" name="Zinc Oxide" status="" percent="100.000" tolerance=""/>
</oxides>
</material> | 
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