水基涂料常用悬浮剂流变及触变性研究

Research on common suspending agents on rheological and thixotropic properties of water based coatings

选择具有优异流变和触变性的悬浮剂有利于流涂控制,可以有效提高铸件的质量。文章研究了钠基膨润土、锂基膨润土、羟甲基纤维素CMC以及凹凸棒土水悬浮液的流变及触变性。结果表明:质量分数≤10.5%的钠基膨润土水悬浮液呈现带有屈服值的塑性流体特征,质量分数为12.5%的钠基膨润土水悬浮液呈现带有屈服值的假塑性流体特征,且触变性随悬浮液浓度的增加而增加;锂基膨润土水悬浮液呈现塑性流体的基本特征,具有触变性,且其受悬浮液浓度的影响较小;CMC水悬浮液呈现假塑性流体的基本特征,触变性小;凹凸棒土水悬浮液呈现带有屈服值的假塑性流体特征,其剪切应力-速率曲线逆时针方向形成封闭的环,且随凹凸棒土水悬浮液浓度的增加封闭环的面积增加。

The selection of suspending agent with excellent rheology and thixotropy is beneficial to flow coating control and can effectively improve the quality of castings.The rheology and thixotropy of Na bentonite,Li bentonite,CMC and attapulgite aqueous suspension were studied.The results show that the sodium bentonite suspension with mass fraction≤10.5%presents the plastic fluid characteristic with yield value,and the sodium bentonite water suspension with 12.5%mass fraction presents the pseudoplastic fluid characteristic with yield value,and the thixotropy increases with the increase of suspension concentration.The thixotropy of Li based bentonite suspension is less affected by the concentration of suspension.CMC aqueous suspension has the basic characteristics of pseudoplastic fluid,and its thixotropy is small.Attapulgite water suspension has the characteristics of pseudoplastic fluid with yield value.The shear stress rate curve forms a closed loop in the anticlockwise direction,and the area of the closed loop increases with the increase of the concentration of attapulgite water suspension.