METHOD OF MANUFACTURE OF CORUNDUM CRUCIBLES FROM LOW-CEMENT REFRACTORY CONCRETE Russian patent published in 2001 - IPC

FIELD: metallurgical industry, particularly, technology of manufacture of corundum crucibles for melting of steels and high-temperature alloys in vacuum and open-top furnaces. SUBSTANCE: method includes preparation of combined grinding mixture including alumina, high-alumina cement and superplasticizer; preparation of low-cement refractory concrete by addition of synthetic corundum and water with subsequent mixing; manufacture of crucible semiproducts by vibratory casting and their curing, drying and firing. In preparation of mixture of combined grinding, first, alumina of GK-grade and superplasticizer are ground, then, high- alumina cement is added and combined grinding is continued. In preparation of concrete, added to mixture is synthetic corundum of 0.01- 3.5 mm fraction and grinding grains of synthetic corundum No. 50 with subsequent mixing with water. After vibratory casting, crucible semiproducts are cured in damp medium for, at lest, one day. Crucible semiproducts are dried for, at least, 12 h at temperature of 40-120 C, and firing at temperature of 1500-1550 C for 6-8 h. EFFECT: reduced percentage of rejects and cut down cost of products. 7 cl