硅灰石膏型材料的流变行为及其性能

Rheological Behavior and Properties of Thaumasite Mold Composites

水固比0.45的硅灰石膏型材料悬浮体在10〜180s^-1范围内显示剪切变稀的流变特征,满足浇注成形的要求。建立的悬浮体流变模型η=40480(γ+77.01)^-1与试验值吻合,其流变行为符合幂律模型的特征。随着悬浮体的可操作时间从10 min增加到50 min时,在98 s^-1剪切速率下的表观粘度从248 mPa·s增大到441 mPa·s,呈线性缓慢增长,仍保持着假塑性流体特征,其稳定性能够满足浇注工艺的要求。材料浇注后的抗折强度为2.1 MPa,具有均匀一致的显微结构。使用试验表明,材料满足铝合金精密铸造的性能要求。

The thaumasite mold composite suspension with a water-solid ratio of 0.45 exhibited shear thinning characteristic in a range of shear rate from 10 s-1 to 180 s-1, which is satisfactory for the casting process. Rheological model of the suspension, as shown by: η=40480(γ+77.01)-1, has been simulated using the MatLab software, revealing that the suspension characteristics agree with the power-law rheological model. With increasing the working time of suspensions from 10 min to 50 min,the bulk viscosity increased from 248 mPa·s to 441 mPa·s at 98 s-1 shear rate, showing slow linear growth, and pseudo plastic fluid characteristics were still maintained, with a satisfactory stability for the casting process. Furthermore, the composite has a more uniform microstructure and a flexural strength of 2.1 MPa. The application testing shows that the properties of the composite can meet the requirements of the aluminum alloy precision casting process.