Aluminosilicate

The Aluminosilicates fill the gap between the important end members of the series, i.e. Silica and Alumina. They generally have lower working temperatures but they have the advantage of good thermal cycling capabilities and a good strength.

SILLIMANITE has the benefit of a very good thermal shock resistance but it has a poor erosion resistance in contact with metals.  It is therefore used in non-critical positions such as crucible outer sleeves or as containers for powder calcination.

MULLITE products have a greater alumina content and can be used in the air-melting of steels; it is better suited to acidic slags.  The material is used for one-shot applications, such as with pouring cups. and also support struts.

MULLITE F80 maximises the possibilites of a mullite material.  It is made from fused grain to enhance its thermal shock resistance and has an alumina boosted matrix for better erosion resistance.  It is well suited to use as a transfer ladle. SC MULLITE is a slip cast grade used for crucible sleeves and special shapes with a smooth finish.

Alternatively, if pre-heat problems limit the life of a ladle then an effective solution would be the FS60 product.  This is based on FUSED SILICA to confer an excellent thermal shock resistance; erosion resistance is maintained at a good level by alumina additions. Also suited to fire assay crucibles.