Some properties of fused ceramic sand
Fused ceramic sand particles are spherical, with good fluidity and easy compaction. According to the statistics of the core making process, the main reason for the waste core of the sand core when using high-temperature coated sand for core making, core repair and transportation is the false shooting defect, and the waste core rate is high.
After using the high-strength coated sand process, the waste core rate of the false shooting sand core is greatly reduced, which effectively reduces the problem of sand core fracture caused by false shooting. Fused ceramic sand particles are round, standard spherical, with an angle coefficient ≤ 1.10, and the surface is free of edges, fluctuations and depressions, which is conducive to the formation of a complete adhesive film and bond bridge coated on the sand surface. The thermal expansion rate of fused ceramic sand under high temperature heating is lower than that of ordinary high temperature resistant coated sand. This performance effectively reduces the thermal expansion rate of sand core under high temperature pouring conditions, improves the strength of sand core, reduces core breaking defects, and prevents the occurrence of veins, sand sticking and other defects.
Specific conclusions obtained from fused ceramic sand experiment
(1) Adding proper amount of fused ceramic sand into ordinary high temperature resistant coated sand can improve the fluidity and permeability of coated sand and the compactness of sand core.
(2) The high-strength coated sand mixed with 40% Fused ceramic sand can not only improve the bending strength of the sand core at room temperature, but also improve the bending strength of the sand core at high temperature, prevent the drift fracture defects of the sand core due to the buoyancy of molten iron, especially reduce the core fracture problem caused by the small size of the sand core, reduce the occurrence of veins and sand sticking defects, and improve the quality of the casting cavity.
(3) Adding an appropriate amount of fused ceramic sand into the ordinary high temperature resistant coated sand can improve the fire resistance of the sand core, and by adjusting the curing temperature and curing time, the problem of "over curing" can be avoided on the premise of ensuring that the strength of the sand core meets the production requirements, so as to prevent the fracture of the sand core during high temperature pouring.