α-Al2O3微粉和SiO2微粉浆体的动电特性和流变行为研究

Investigations on Zeta potential and rheological behaviour of suspensions of ultrafine α-Al_2O_3 and SiO_2

研究了pH值不同时α-Al2O3微粉和SiO2微粉浆体ζ电位的变化,并分别测定了三聚磷酸钠、六偏磷酸钠和FDN3种分散剂在加入量(w)为0、0.1%、0.2%、0.3%、0.4%、0.5%时对固相质量分数为20%的α-Al2O3微粉和SiO2微粉浆体ζ电位的影响,以及3种分散剂对一定质量分数的3种浆体流变特性的影响。结果表明:1)α-Al2O3微粉浆体在强酸和强碱的条件下,ζ电位的绝对值都很大,而SiO2微粉浆体只有在靠近碱性的条件下才有利于浆体的分散稳定;2)α-Al2O3微粉浆体的等电点在pH值=7.56,SiO2微粉浆体的等电点在pH值为1～2之间;3)3种分散剂能显著提高α-Al2O3微粉浆体的ζ电位,而对两种SiO2微粉浆体的作用不大;4)3种分散剂能在一定程度上改善α-Al2O3微粉浆体和SiO2微粉浆体的流变特性,加入量在0.2%左右,其中,六偏磷酸钠较好。

Effects of pH values, dispersants （Sodium tripolyphosphate, Sodium hexametaphosphate and FDN） and their different additions （0,0. 1% ,0.2% ,0.3% ,0.4% and 0.5% ） on Zeta potential of the suspensions of ultrafine α-Al2O3 and microsilica commonly used in castables were investigated. Rheological behavior of the suspensions of α-Al2O3 and SiO2 with different additions of three types of the dispersants was also studied. The results show that： ]） On the conditions of strong acid and basic, Zeta potential of α-Al2O3 suspension are higher as 40 - 60 mV, but the SiO2 suspensions gets higher values of Zeta potential only within basic range;2） The isoelectric points （IEP） of the suspensions of α-Al2O3 and SiO2 are 7.56 and 1-2 of pH val- ue respectively; 3） The dispersants tested can change the Zeta potential of α-Al2O3 suspensions remark- ably, but that of two SiO2 suspensions is not sensitive to additions of dispersants; 4） The three dispersants can decrease viscosity of α-Al2O3 suspensions markedly, and about 0.2% addition of them is appropriate. Compared with the rest, sodium hexametaphosphate is more contributive to the decrease of viscosity of SiO2 suspensions.