在研究pH 值对Al2 O3/SiO2二元悬浮体系流变性的基础上,着重研究了分散途径对 PAA 分散的 Al2 O3-SiO2二元体系流变性的影响.实验表明,在无分散剂时,Al2 O3-SiO2二元混合体系流变特性随 pH 值的变化可为3段：在pH 值＜2．0以及pH 值＞9．0两个区域,悬浮液处于稳定分散状态；而当 pH 值介于2．0~9．0时,浆液产生严重的絮凝现象,且絮凝程度高于 Al2 O3和 SiO2各自的单元体系.在 pH 值介于2．0~9．0时,通过添加PAA可使Al2 O3-SiO2二元悬浮液达到稳定分散状态；pH 值为6．0时,采用普通添加方式 PAA 的最低添加量为0．8％(质量分数)；改变分散途径后,分散所需的PAA最低添加量可降低50％,仅为0．4％(质量分数).该结果表明,在Al2 O3-SiO2二元体系中,分散剂PAA在颗粒表面存在不均匀吸附现象,并且通过分散途径的设计,可有效地避免这种现象.另外,分散途径的设计可以提高PAA稳定分散的 Al2 O3-SiO2二元悬浮液的抗离子强度特性,同时又可降低固含量对浆液流变性能的影响.
The dispersion and stability of aqueous Al2 O3/SiO2 binary colloidal system were investigated at differ-ent pH values.Based on the above experiment,the rheological properties of the binary suspensions of Al2 O3-SiO2 containing PAA was tested by decentralized route.The experimental results show that in the absence of dispersant,the rheological properties of Al2 O3-SiO2 binary suspensions as a function of pH was divided into three sections.At pH<2.0 and pH>9.0,the binary suspension was well-dispersed.At pH=2.0-9.0,the binary suspension was strongly flocculated,and had higher degree of flocculation than the unary suspension.However, it was well-dispersed by adding PAA at pH 2.0-9.0.The minimum amount of PAA was 0.8wt% by using the common adding ways at pH=6.0.After changing the processing route,the minimum amount could be reduced by 50%,only 0.4wt%.The results show that a heterogeneous distribution of PAA on particle surface in the Al2 O3-SiO2 slurries,and the pheonmenon could be avoided by optimization of processing route.In addition, with the optimization of processing route containing PAA in Al2 O3-SiO2 binary suspensions,the system ob-tained superior anti-electrolyte performance.At the same time,effect of soild loading on rheological properties of slurries was moderated.
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