超速硬セメントを用いた流動砂の諸性質

抄録

  Fluid molding sand which was based on special super high early strength cement and included surface active agents and additives was investigated in order to establish fluid molding process having rapid hardening property, little temperature dependence, good stability of mold and excellent collapsibility after casting of metal.
  Surface active agent composed of ester of higher alcohol and sulfonic acid gave good fluidity to fluid sand and improved apparent specific gravity of mold. Surface stabilizer mainly composed of condenstion of β-naphtharin sulfonic acid and formalin, is effective for development of strength and fluidity of sand. Addition of accelerator composed of inorganic oxide (Q agent) gave high initial strength and the effect of the other accelerator composed of calcium aluminate (W agent) was more remarkablees pecially in low temperatures.
  Recommenced proportionings of fluid sand made of special super high early strength cement, water, sand, surface stabilizer, surface active agent and accelerators are established according to molding temerature although they are often influenced by the mechanical characteristics of the mixer. The collapsibility of molded sand depends mainly on the volume density and cement content of fluid sand. Though metal can be poured in the mold without any artificial drying, if it is necessary, drying under low temperature (below 150°C) is suitable in order to avoid drying contraction.