Influences of experiment factors on the concretion hardening time

compressive strength at room temperature

flowing radius and foaming capacity in the process of producing gypsum slurry were investigated. The results show that the concretion hardening time of gypsum slurry is proportional to the ratio of water to powder

and the compressive strength of gypsum slurry is improved with adding quartz powder

kaolin

diatomite

sodium chloride and anhydrous magnesium sulfate at room temperature. With the water temperature increases

the concretion hardening time

compressive strength at room temperature

flowing radius and foaming capacity of gypsum slurry exhibit the trend of first decrease and then decrease. Foaming gypsum mold with 80% foaming rate can be made in hard water environment by adding sodium dodecyl sulfate as the vesicant. The foaming of vesicant is inadequate under lower stirring speed and time

while bubbles are easily broken away at high speed stirring and time. The desirable mixing process parameters are 2 000 r/min and 4 min. Foaming gypsum mold was produced based on the optimized process parameter

and then thermal baking was conducted. ZL114A alloy castings were poured at 715 ℃. The results reveal that the parts meet the actual requirements together with broken absence of the foaming gypsum mold in the process of baking.