| abstract |
Filters for molten metals are open-porous porous materials that include particles of refractory material that are bonded to and embedded in each other by a carbon matrix that bonds the materials together. The filter is, for example, refractory particles such as refractory oxides, carbides or graphite, and carbon rich, for example organic (preferably aromatic) polymers that decompose to form carbon upon tar, pitch or pyrolysis. By forming the porous material from the binder, and then firing the porous material to form a carbon matrix into which the refractory particles are embedded. The porous material is preferably formed by coating a mesh of polyurethane foam with a binder and refractory particles and firing at a temperature of preferably 800 ° C. or lower. |