| abstract |
There are described materials for use in the manufacture of cores, moulds and strongbacks, the cores, moulds or strongbacks comprising shaped and fired bodies of fused silica containing cristobalite homogeneously dispersed throughout. Such bodies are suitably made from a composition comprising fused silica powder and a devitrification aid containing an alkali metal compound in which the alkali metal compound is dispersed in the fused silica by adding it in an organic phase. n Such cores, moulds and strongbacks are particularly suitable for use in the high temperature casting of alloys, especially single crystal casting and the casting of directionally-solidified and eutectic alloys. |