|Monthly Tech-Tip |
Alternate Names: Mulcoa 70 Calcined Grog, Mulcoa 70 Calcined Mullite
Description: Refractory Aggregate, Mulgrain 70, Mulcoa 70 Calcine
This material is produced from calcined mullite that is precisely sized through a series of screens and blended to obtain a series of coarse to fine sizes. During screening the grains are de-dusted. The product is used mainly for stucco and investment casting, in ceramics its main application is as a low expansion grog for bodies.
Mulcoa 47 and Mulcoa 60 are alternate products, these numbers refer to the approximate alumina content. Mulcoa 70 is thus the highest in alumina and therefore highest in mullite mineral (87%) and the lowest in glass. Mulcoa 47 is 65% mullite and 20% glass and 15% cristobalite (the others have no cristobalite).
Mulcoa 70 is the most refractory, Mulcoa 60 is 37 PCE and Mulcoa 47 is 35 PCE. Mulcoa 47 has a reheat change of 0.8% at 2800F and 3.1% at 2910F, Mulcoa 60 is zero for both.
Various grades for each are available in the following U.S.S. Sieve Mesh sizes:
10x18, 14x28, 16x30, 22S, 35S, 50S, 60S, 20x50, 35x80, 50x100, 60x200, 300S, 200 IC-C, 325 IC-C
A fibrous alumina silicate mineral of very low thermal expansion. Mullite is formed within porcelain
Mulcoa 60 Calcine Grog
Mulcoa 47 Calcine Grog
Granular materials intended to impart raw and fired structural strength or thermal expansion properties to bodies or deliver special speckling effects in glazes.
Calcining is simply firing a ceramic material to create a powder of new physical properties. Often it is done to kill the plasticity or burn away the hydrates, carbonates, sulfates of a clay or refractory material.
In the ceramic industry, these are the bricks used to build kilns. This term grows out of their ability to withstand high temperatures that would melt or deform structural bricks.
|Bulk Density g/cc (Packed)||2.88|
|Pyrometric Cone Equivalent||39|
|Reheat Change||0% at 2800F, 0% at 2910F|
|By Tony Hansen|
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