On Water-soluble Alumina Sand Mold Bonded by Sodium Aluminate/CO₂

Abstract

Dust, noise and vibration principally are created in molding and mold-releasing “knock-out” operations in foundry shops which worsen the working atmosphere and pollute the environment.
To solve these problems, this study was performed to provide a water-soluble mold that can be easily hardened by using CO₂ gas and broken up with a water-spray after pouring.
(1) This water-soluble mold was produced, from a mixture of alumina sand and a small amount of sodium aluminate, and subsequently hardened by using CO₂ gas. This mold was disintegrated by water-spraying after pouring a molten cast iron.
(2) In this mold heated at high temperatures, other insoluble reaction substances except hardening reaction ones were not recognized and therefore showed sufficient water-solubility after heating.
(3) There was little additional residual stress increase in the cast iron produced in a water-soluble mold, even after being sprayed with water under A₁ transformation temperature. Consequently, it could be considered that the water-spraying treatment seldom caused any trouble for the cast iron quality.
(4) From the second result mentioned above, a recycling system of these mold materials seems to be possible by applying a method of synthesizing sodium aluminate from the used mold.