抄録
In this paper, the auther presents the effects of conditions in hardening the sand mould by CO2 process to the compresive strength and the permeability of the mould. The conditions considered are, the grain-size of silica sand, adding-amount of water glass, blowing time of CO2, length of time after blowing, as well as the multiple use of molding sand.
The results obtained are as follows:
(1) The finer grain of silica used, the greater compresive strength and the smaller permeability of the mould are obtained.
(2) If the JIS-No.1 water glass is chosen as on adding agent, the mould has the maximum compresive strength when 4 to 5 % water glass is added. However, if JIS-No.2 or No.3 water glass is chosen, the compresive strength of mould increases along with the increase of the blowing time.
(3) Along with the time after blowing of CO2, the compresive strength of mould treated strength of the mould treated with No.2 or No.3 water glass, shows no remarkable change.
(4) Multiple use of the same sand causes the decrease of both compresive strength and permeabilility of the mould.
