Surface-sealed fired clay as moulding material for producing casting moulds

摘要

Mold base material particle comprises a refractory grain and surface of the refractory grain sealing substance, where the sealing substance is: an oxide comprising silicon dioxide, zirconium dioxide and/or aluminum oxide; and a hardened bonding agent, where the hardened bonding agent is a hardened phenolic resin. Independent claims are also included for: (1) a mold base material for producing a casting mold and casting core, comprising or consisting of a variety of molding material particles; (2) a mixture for sealing the surface of a refractory grains comprise a bonding agent, an inorganic material and/or a precursor material convertible to an inorganic material and optionally magnetic particle; (3) preparing a mold base material comprises providing the refractory grains, providing or producing the above mixture for sealing the surfaces of the refractory grains, applying the above mixture for sealing the surface of the refractory grains and hardening of the mixture for sealing the surface of the refractory grains applied on the refractory grains under forming the surface of the refractory grain sealing substance; (4) producing a hardened caster form or hardened caster core comprises providing the above mold base material, providing a casting binding agent, mixing of the mold base material with the casting binding agent, molding the mixture to casting mold or to the casting core, and hardening of casting binding agent in molded casting mold or in the molded casting core; and (5) separating the above mold base material from the mixture of the mold base material and non-magnetic mixture component comprises applying a magnetic field.