Mullite
Calcined Mullite
Formula: 3Al2O3.2SiO2
| HMOH - Hardness (Moh) |
3.1 |
| MLPT - Melting Point (MP) |
1810C |
Mullite is a mineral of long interlocking needle-like crystal structure that is very resistant to thermal shock failure (has a low thermal expansion). It is also has a low thermal conductivity and is very refractory thus the theoretical formula (of 71.8% alumina and 28.2% silica)bears little resemblance to the real world material (we have provided a typical non-theoretical analysis). It is found rarely in nature, it is named after a deposit on the Isle of Mull in Scotland. However, it can be synthesized by calcining kyanite, bauxite or alumina/kaolin mixtures of proper Al2O3:SiO2 ratio.
On a scale of lowest to highest thermal expansions at 2000F (where fused silica is almost zero and quartz is 1.5%), mullite is about one third of the way. It has a lower expansion than fused alumina (0.9%) and stabilized zircon (0.8%).
Mullite crystals can also be formed within special purpose porcelains by incorporating similar minerals into the recipe and firing to the necessary temperature and heating curve to decompose them into mullite. These include andalusite (cone 13), kyanite (cone 12), sillimanite (cone 20). The resulting bodies display low thermal expansion and a useful in spark plugs, laboratory ware, etc. and in thermal shock resistant refractories.
Firing of ordinary stoneware bodies provides the necessary temperature and adequate kaolin to produce mullite crystals from the decomposition of kaolinite (kaolinite looses some silica and the remaining higher alumina reorients itself to a higher melting compound). The resulting lattice of crystals is potentially much stronger than the simple glass-weld bonds of low-fire ceramics.
The chemistry of mullite depends on the parent material. Impurities tend to be TiO2, Fe2O3, Na2O, K2O.
Mechanisms
Out Bound Links
- (URLs)
Overview
http://www.azom.com/details.asp?ArticleID=925 - (Materials - Related)
Kyanite - Al2O3.SiO2
Disthene, Cyanite
- (Materials - Related)
Pyrophyllite - Al2O3.4SiO2.H2O - A Soft Hydrous Aluminum Silicate
Pyrophillite
- (Materials - Related)
Calcined Alumina - Al2O3 - Aluminum oxide
Alumina Calcined, Calcnd Alum, Ground Alumina, Corundum
- (Typecodes)
1: REF - Refractory
- (Minerals - Mineral equivalent)
Mullite
A fibrous alumina silicate mineral of very low the... - (Typecodes)
1: GNM - Generic Material
- (Typecodes)
1: ALS - Aluminum Silicate
- (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 ... - (MDT - Member)
Latin and South America
Latin America and South America. We are working on... - (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...
In Bound Links
- (Materials - Related)
M70 Mullite - Needle shaped interwoven mullite
- (Materials - Parent)
Mulcoa 70 Mullite - Refractory Aggregate, Mulgrain 70, Mulcoa 70 Calcine
Mulcoa 70 Calcined Grog, Mulcoa 70 Calcined Mullite
- (Materials - Related)
Virginia Kyanite
- (Glossary - Unspecified)
Mineral
Ceramic minerals have a highly ordered atomic stru...
XML for Import into INSIGHT
<?xml version="1.0" encoding="UTF-8"?>
<material name="Mullite" descrip="Calcined Mullite" searchkey="Mulite" loi="0.00" casnumber="55964-99-3">
<oxides>
<oxide symbol="K2O" name="Potassium Oxide" status="" percent="0.200" tolerance=""/>
<oxide symbol="Na2O" name="Sodium Oxide, Soda" status="" percent="0.200" tolerance=""/>
<oxide symbol="TiO2" name="Titanium Dioxide, Titania" status="" percent="0.600" tolerance=""/>
<oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="57.000" tolerance=""/>
<oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="41.000" tolerance=""/>
<oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="1.000" tolerance=""/>
</oxides>
</material> | 
The future of ceramic recipe, material and physical testing record keeping is here.
Maintain your recipe database on-line
- Login to a private account or work with others in a group account (e.g. university).
- Nothing to install (access it using your web browser). It is always the latest version.
- Easy to import your existing data.
- As many side-by-side recipes as you want.
- Many ways to search and classify glaze and body recipes.
- Glaze and body recipes are robust, with units-of-measure, unlimited pictures with individual titles and descriptions.
- Add variations to a recipe; each with its own pictures, descriptions and name/code-number extensions.
- Recipes can link to typecodes, projects and firing schedules (all managed in their own areas).
- Standard reports and mix ticket reports with last-minute-totalling; variations report as if they are a complete recipe.
- Video tutorials, help system, contact form on every page, dedicated messaging and support ticket systems.
- It is an industrial-strength database system (unlimited capacity, fast, reliable, scalable).
Imports many file formats
- Glaze recipe formats supported: HyperGlaze, GlazeGhem, GlazeMaster, Matrix, INSIGHT XML recipes (single and multiple), INSIGHT SQLite DB files.
- Assign a batch number to imports, and later search by batch.
- Assign multiple typecodes to imported glaze and body batches (to classify) and search on these later.
- Prepend character sequences to glaze recipe names during import.
- Import the pictures and pair them to their corresponding records automatically.
- One click to automatically export the database to an SQLite DB database file and download it (for use with desktop INSIGHT or just as a backup).
- Export and import individual glaze recipes as text or XML.
Perfect for Education
- Ceramic study programs can now accumulate material, recipe and testing data year-after-year, students can login and together build a valuable ceramic glaze and body knowledge resource.
- Students already have internet connected devices, computers are not even needed in the class.
- The Reference Manager gives you quick access to the Digitalfire Ceramic Reference Database.
Learn more..
|
Watch the video or sign-up at http://insight-live.com.