pH值对包覆改性SiC料浆分散特性和流变性的影响

通过zeta电位、沉降实验、流变特性、粘度等测试表征pH值对包覆改性SiC料浆分散特性和流变性的影响。研究表明:以偶联剂作为基础层,有机聚电解质作为分散功能层的有机包覆改性SiC粉体主要通过静电空间位阻效应实现稳定分散,调节pH值可以控制接枝聚合物水解产物的解离方式,从而改变了颗粒表面的电荷种类和电荷密度,包覆改性粉体的流动特性也发生变化。调整料浆pH值约11可制备出固相体积分数达56％、表观粘度为568 MPa·s的稳定料浆。

EFFECT OF pH VALUE ON DISPERSIVE AND RHEOLOGICAL PROPERTIES OF COATED SiC SLURRY

Modified SiC fine powders was prepared by organics coating method. Organics polyelectrolyte as a dispersion functional layer was formed on the surface of SiC powders by chemical bonding and graft reaction. The coupling agent was used as bridge to connect the powders and the polyelectrolyte. The effect of pH value on the dispersion and rheologic behavior of the modified SiC powder were characterized by experiments of zeta potential, sedimentation, rheologic behavior and viscosity etc. Experimental results show that the stabilized dispersion of modified SiC powders is realized by the effect of static resistance among powder particles. The dissociation manner of polyacrylamide hydrolysate can be controlled by means of adjusting the pH value, which determines the charge type and charge density on the surface of particles, and resulting in the changes of rheologic behavior of the modified powder. The stable slurry with concentrated suspension of 56% (in volume) and the apparent viscosity of 568 MPa s can be obtained when pH value is about 11.