超细镁铝尖晶石凝胶注模用浆料的制备

研究了在凝胶注模用超细镁铝尖晶石浆料的制备工艺中，粉体粒度、pH值、分散剂等对浆料流变性、Zeta电位、粘度和稳定性的影响及作用机理。实验结果表明:相同剪切速率下，随着粉体粒径的减小，浆料粘度变大，稳定性提高。当浆料中不添加分散剂时，超细镁铝尖晶石浆料在酸性条件中的Zeta电位绝对值比在碱性条件下高。添加分散剂后，等电位点对应pH值向酸性方向移动，且随固相含量的提高，制备低粘度浆料所需分散剂百分含量越低。pH值和分散剂含量均存在最佳范围，过高和过低，浆料的流变性和稳定性均会变差。Zeta电位绝对值的大小仅仅是影响浆料稳定性的一个方面，如果分散剂过量，即使浆料颗粒Zeta电位绝对值很大，浆料也会产生团聚和絮凝。

Preparation of ultra-fine magnesium aluminate spinel slurry for gelcasting forming

The effect of particle size, pH value and dispersant on the rheological properties, Zeta potential, viscosity and stability of slurry and its mechanism were studied. The experimental results show that the viscosity of slurry increases and the stability increases with the decrease of particle size at the same shear rate. When no dispersant is added in the slurry, the absolute value of Zeta potential of the ultra-fine magnesium aluminate spinel slurry under acidic condition is higher than that in alkaline condition. While, in the presence of dispersant, the pH value corresponding to the isoelectric point moves in an acidic direction, and the percentage of dispersant required for preparing low viscosity slurry decreases with the increase of solid content. pH value and dispersant content have the best range, if too high or too low, the rheological and stability of the slurry will be worse. The absolute value of the Zeta potential is just one aspect that affects the stability of the slurry, and if the dispersant is excessively large, even if the slurry particles Zeta potential absolute value is large, and the slurry will produce agglomeration and flocculation.