The Microstructure Of Fused Cast Azs Materials Before, During And After Melting

A part of a solder block, placed in a float glass furnace near the hot spot area, was investigated to learn about changes in the microstructure during the production of the block, during the use for glass melting and after the shutdown of the furnace and cooling of the block. Besides the three phases after production (baddeleyite, corundum, vitreous phase) during use as a solder block mullite and secondary corundum as well as secondary zirconia may occur. Cooling down the used block after the furnace campaign sees the beginning of crystallisation of feldspars