Study On Improving Technology And Performance Of Gypsum Mold

The article studies on optimizing the gypsum general process, contrasting the performance of gypsum adding chloride, oxides and three kinds of phosphate, adopting the innovative technology process of dry ball milling and hydrothermal method, measuring the gypsum mold performance ex. initial set time, final set time, water absorption and flexural strength. The results show that:after adding chloride and oxide,the impact of initial setting and final set time is not big, but the times extend. With the cationic valence increasing of chloride, the gypsum mold’s water absorption increases, but the flexural strength is the close to adding the low cationic valence’s,when adding MgO the flexural strength reduce the minimum value, water absorption increases high percentage, the results shows the performance of adding oxide chloride gypsum mold is better than adding chloride. When adding the same amount of three kinds of phosphate, the best of the effect of delayed coagulation is (NaPO3)6, the flexural strength of mold is higher. The process of dry ball milling can greatly improve the water absorption of mold, Furthermore, the water absorption of gypsum molds made by the pre-grinded gypsum powders was increased by42.0percent in the case of2hours’grinding time. The process of hydrothermal method can improve the water absorption and flexural strength.the more reactiving time and the higher reactiving temperature, the more performance promoting, but the reaction time of hydrothermal is limited with gypsum initial set time. XRD and SEM were employed to characterize the phase compositions and microstructures of gypsum powders. The results show:the crystalling phase is still CaSO4(0.5)·H2O after milling. along with the increasing of the milling time, lattice distortion coefficient increases, gypsum crystal orientation is upset, it’s help for the interweaving of crystal. when adding (NaPO3)6,the shape of gypsum crystal is columnar, the area of interweaving of crystal increases, which is help for increasing the flexural strength. After Hydrothermal method, the crystalling phase isl CaSO4·(H2O)2rather than CaSO4·2H2O. Through calculation using jade, the higher Reacting temperature, the higher Crystallization degree.gypsum mold in modern ceramics production has an important position, if improving the performance of the gypsum mold can enhance the enterprise the production efficiency, higher quality and low cost, the process and performance data in the paper are help for producting.