The Preparation Of Base Oils With High Viscosity Index And Detecting Its Lubricating Properties

The development of transportation makes the diesel engines develop towards to high-speed and high-load, and improves transport efficiency and fuel economy. But high power density makes the moving parts bear high loads, friction increases, wearing and tearing increases. High-performance lubricants with low kinematic viscosity, high viscosity index and good film-forming properties are needed. Developing lubricants according to above requirements, and detecting its lubricating performance, will be helpful to reduce friction and improve the efficiency of diesel fuel.Study found that poly α-olefin (Poly Alpha Olefin, PAO) lubricant has regular molecular structure, a wide range of options for kinematic viscosity, high viscosity index, and good film-forming properties at high-temperature. So, PAO is potential to meet the performance requirements of lube oils for heavy duty diesel engines.In this paper, ionic liquid AlCl3/[Emim]Cl is used to catalyze a-olefin producing PAO base oils. Impact on the polymerization reaction is investigated in the aspects of catalyst molar ratio, catalyst dosage, reaction temperature, reaction time, water content and the type of raw material. The results show that choosing 1-decene as raw material, and the molar ratio of AICl3 and [Emim]Cl as 2:1, the amount of ionic liquid as 3g, the polymerization temperature as 60℃, polymerization time as 4h, the water content as 100ppm, the PAO base oils has a kinematic viscosity of 10.61cst at 100℃, a viscosity index of 144, a yield of 86.9%, and the oils’ comprehensive performance is good.Comparison is made for the film forming performance at low speed conditions and lubricating properties at high speed among the base oil of PAO, class Ⅰ and class Ⅱ. An original EHL tribometre is used to investigate the film forming performance of the base oil of PAO, class Ⅰ and class Ⅱ at low speed conditions. The results showed that under the conditions with load 0.24～0.43GPa and speed 0～5mm/s, the film forming performance of PAO oil is better than class Ⅰ and class Ⅱ base oils; The film thickness of each base oil became thinner with the increasing of contact stress, and thickener with the increasing of sliding speed. A high-speed and point-contact testing machine is used to detect the lubricating properties at high speed conditions among the base oil of PAO, class Ⅰ and class Ⅱ. The results showed that under the conditions with load 0.2～0.4GPa and slide roll ratio 0-0.4, the lubricating properties of PAO and class Ⅱ base oil are better than class Ⅰ; The friction coefficient of each base oil increases with the contact stress the slide roll ratio.