SAND FOR MAKING CASTING CERAMIC CORES Russian patent published in 1994 - IPC

FIELD: casting production. SUBSTANCE: sand, providing enhanced quality of a surface of cores with paraffin-based organic plasticizer due to practical elimination of such defects as gaseous bulges on the surface of cores and bubbles in a near-surface layer and maintaining high casting capability, contains (mass % ): refractory filler (70-88,2), organic plasticizing agent - (11,7-24), low-molecular silicon-organic rubber (0,1-6). In the result of combined presence in the core sand of the paraffin-based organic plasticizer and the low-molecular silicon-organic rubber, the last is being partially solved in the melt paraffin and after cooling it is being separated on boundaries of grains of the crystallized paraffin with formation of thin high-strength cohesion layers. EFFECT: lowered rejection of cores, caused by "bubble" and "bulge" defects. 1 cl, 2 tbl