Effect of aging reaction on the colloidal structures and antiwear property of overbased calcium alkyl-salicylate

The aging process of overbased calcium alkyl-salicylate was studied with FT-IR, freeze-etching electron microscopic observation and calcium distribution measurement. The results show that, when overbased calcium alkyl-salicylate are subjected to aging reaction, the size of colloidal particles in samples decreases, the relative content of calcium hydroxide in colloidal particles increases, the viscosity of samples decreases and the total basicity number of samples increases. The detergency and antiwear properties of aged samples are better than that of non-aged ones. The aging efficacy becomes worse if the water, methanol and residue of calcium hydroxide are removed from the reaction system. The primary aging mechanism was deduced according to the testing results.