Gases from heated green sands and two core sands were analyzed in this study. The measured gases included the volume percent of O_2. CO_2, CO, H_2, CH_4 and C_n H_m. Molten gray irons and heated steel bars were used to heat the green sands and core sands. Gases were sucked into sampling burettes and collected during the period of gas evolution. The measured gases showed a marked decrease in O_2 to as low as 8 vol% in the early two minutes after sands had heated, followed by a gradual increase to about 20 vol% in six minutes. Sand ingredients, mulling time and the order of adding clay and seacoal were found to be significant factors in determining the volume percent of measured gases. Low initial %O_2 and maximum total reducing gases of CO + H_2 + CH_4 at 21 vol% were observed when 10% sodium bentonite (Na-B) plus 3.33% seacoal had mulled for 65 minutes. Reducing the mulling time to 15 minutes was found to result in higher initial O_2 up to 16 vol%, and greatly reduced total reducing gases to 8%. The addition of cellulose raised initial oxygen and lowered the reducing gases. Dextrine plus 3.33% seacoal with short mulling resulted in low O_2 and equivalent total reducing gases as the dextrine free mixtures. With only 1% seacoal, initial %O_2 was high and the total reducing gases were low. The heated core sands showed that high residual O_2 at 16-18 vol% and low total reducing gases occurred throughout gas evolution. Graphical analysis explained that high initial %O_2 was accompanied by low %CO_2 and low percent total reducing gases. Surface qualities of poured castings were compared and affected by the varying constituents and mulling conditions of green sands.
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