CERAMIC FLAME-RETARDANT MATERIAL, CRUCIBLE, AND METHOD FOR MANUFACTURING A CRUCIBLE Russian patent published in 2021 - IPC C04B35/505 C04B35/488 C04B35/626 

FIELD: ceramics.

SUBSTANCE: invention relates to the field of ceramic flame-retardant materials for manufacturing crucibles. The proposed ceramic flame-retardant material of a crucible comprises 14.8 to 45 wt.% of zirconium oxide, 6.8 to 8.54 wt.% of at least one rare earth metal oxide selected from the group: gadolinium, neodymium, samarium, lanthanum, praseodymium and dysprosium, yttrium oxide the rest. The material comprises yttrium oxide in the form of particles of two different fractions, wherein the smaller fraction is up to 0.5 mcm and the larger is 20 to 250 mcm, oxide of at least one rare earth metal (selected from the group: gadolinium, neodymium, samarium, lanthanum, praseodymium and dysprosium) in the form of particles of a fraction of up to 10.0 mcm, and zirconium oxide in the form of particles of two different fractions, wherein the smaller fraction is up to 10.0 mcm and the larger is 600 to 710 mcm. The components are mixed in three stages. At the first stage, a sintering additive is produced, consisting of powders of fine fractions of zirconium oxide, yttrium oxide and oxide a rare earth metal; at the second stage, said additive is mixed dry with granular powders of zirconium oxide and yttrium oxide, resulting in a dry ceramic charge; at the third stage, said charge is mixed with a suspension containing yttrium oxide particles. The resulting plastic mass is moulded and dried for 12 to 25 hours producing a crucible preform further subjected to high temperature sintering at a temperature from 1,650 to 1,750°C for 3 to 5 hours.

EFFECT: ensured resistance of the material of the crucible to the influence of melts of high temperature reactive zirconium-containing alloys and alloys of the chromium-molybdenum-iron system at temperatures up to 1,820 and 2,050°C, respectively, increased heat resistance of the crucible, and increased accuracy of moulding the crucible.

4 cl, 6 tbl, 7 ex