Abstract:
Electrode blocks and multiple-piece assemblies are provided for electric, glass-melting furnaces to reduce the occurrence and extent of cracking which occurs in monolithic electrode blocks from thermal stresses induced by a high temperature gradient between such blocks or the block assembly and a fluid-cooled electrode and from thermal shock encountered in repositioning the electrode. An insert block of a high thermal stress and glass corrosion/erosion resistant refractory material is configured to receive an electrode assembly. A holder block, which may be of the same material or another material, including a material having less thermal stress strength or less glass corrosion/erosion resistance than the insert block material, has a passageway therethrough to receive at least part of the insert block with electrode assembly therethrough. Densified chromic oxide with zirconia is presently preferred as the insert block composition while fusion cast AZS is presently preferred for the holder block receiving the insert block.