Thesis (M.Sc.)--Chulalongkorn University, 2010

This work explores the effect of the alkyl group of molybdenum ester additives on antiwear. The additives were synthesized by the reaction of diethanolamine, molybdenum salt and various fatty acids. The derived additive was then mixed with base oil and tested for wear property. The synthesized molybdate ester contained molybdenum about 2 wt%. The wear tests by Four-ball tester were as follows: 0:0.76, 20:0.64, 60:0.64, 120:0.66 and 200:0.44 (ppm of Mo:mm of wear scare diameter). The synthesized molybdenum esters exhibited antiwear property. The trend of wear scare diameter revealed the reversed proportional to the Mo content in blended oil. However the blended oil was split into 2 phases within few hours. By changing the formulations, base oil type, adding dispersant, the stability of blended oil could be maintained. The wear scare diameter of blended oils was increased with the addition of dispersants and synthesized molybdate esters.