Abstract:

According to SH/T 0619，the water separation properties of HVIⅡ-10，HVI750，HVI150BS base oils for marine diesel engine lubricant were determined after the addition of the same composite additive. The relationships between water separation and oil/water interfacial tension as well as interfacial shear viscosity were then investigated. The results show that the water separation abilities become worse in the order of HVIⅡ-10，HVI750，HVI150BS, the interfacial tension lowers and the interfacial shear viscosity rise in the same order. It is found that the more aromatics and resins in the base oils, the poorer the water separation property. The additive reduces the interfacial tension and increases the interfacial shear viscosity of the system, resulting in more stable emulsion. The shear viscosity decreases as the shear rate increases. It is concluded that the lower the interfacial tension, the higher the interfacial shear viscosity, the greater the stability of the emulsion, and the poorer the water separation.

Key words: marine diesel oil, base oil, water separation property, interfacial tension, interfacial shear viscosity