REFIRING OF CRISTOBALITE PORCELAIN

Cristobalite porcelain, used in the manufacture of electroporcelain in sulators, consists of cristobalite, quartz, and mullite phases in a gl assy matrix. To overcome certain manufacturing defects the insulators are sometimes refired. This paper describes the effect on various prop erties of refiring cristobalite porcelain. On refiring, some of the qu artz phase converts to cristobalite. Although this results in a slight improvement in flexural strength, refired samples were found to have a lower thermal shock resistance than once fired samples. In view of t his, it is concluded that refiring should be carried out at lower temp eratures to avoid deterioration in the quality of porcelain insulators . (C) 1996 The Institute of Materials.