采用K型热电偶、多通道温度记录仪、游标卡尺和扫描电镜(SEM)对发泡石膏铸型热烘烤过程温度、尺寸与组织变化进行了试验研究.结果表明,热烘烤过程中铸型内部各点均滞后于工艺温度,各点温差曲线随升温温度与保温时间增加呈逐渐上升趋势.高温下随着发泡石膏铸型内部自由结晶水的脱失与晶型转变反应发生,铸型一维长度方向尺寸先连续下降后略有上升;石膏晶粒形状发生了由细针状逐渐过渡为短粗圆柱状或薄片状,再转变为细针状的变化过程.

By taking thermal baking process of foaming gypsum mold as a research object, the temperature variation, dimensional changing, and organizational transformation of the foaming gypsum mold in the overall thermal baking process were studied using K-type thermocouple, multi-channel temperature logger, vernier caliper, and Scanning Electron Microscopy (SEM), respectively. The results indicate that the temperatures of the internal points lag behind the process temperature entirely; the temperature difference curve of internal point gradually rises with the increase of heating temperature and the time for keeping warm. By the slough off of the internal free crystal water and the corresponding crystal transformation of gypsum, one-dimensional size in the length direction of mold first continuously declines and then increases slightly, the shape of gypsum grain changes from acicular shape to bulky cylindrical or lamellar appearance, subsequently transformating to needle morphology shape.