Effects of ZrO sub 2 and ZrSiO sub 4 on the Structure of Fused Spinels, Forsterites, Mullites, and Corundum Refractories

摘要

From microscopic study of slides and visual examination of castings, following conclusions were drawn: ZrO sub 2 added to spinel, forsterite, mullite, and corundum sharply reduces the growth of crystals during crystallization of these phases from the melt; zircon limits crystal growth of the principal phase less than does ZrO sub 2 ; compositions with an average content of ZrO sub 2 (20 to 30%) or zircon (40 to 60%) develop dense monolithic, uniformly fine crystalline structures; castings with a considerable content of ZrO sub 2 (>30%) or zircon (>50%) exhibit high brittleness; fracture of the ingots chiefly has a zonal structure; addition of zirconium-containing materials changes the sample structure from glassy- and massively-crystalline to porcelain-like in form; and castings with a high content of ZrO sub 2 or zircon show intense blistering over the whole piece. 7 figures. (ERA citation 08:005683)