Study On Tribological Behavior Of Sulfurous Extreme Pressure And Antiwear Agent In Base Oil Of Environmental Compatible Lubricants

In recent years, with the rapid development of industry and the wide-using lubricants, the environmental pollution resulted from using lubricants has been more and more seriously. Since traditional lubricating oil with mineral oil taken as base oil often pollute the environment, which threaten human environment that is the human and other lives live. Along with the enhancement of the environmental protection and legislation, people all over the world pay close attention to the problem of the environmental pollution. In order to meet this need, many countries in the world request using biodegradable lubricants in their country and encourage researching it.There are a lot of differences in physical and chemical property, tribological behavior and biodegradability between mineral base lubricates and biodegradable lubricants. In order to develop it researcher must know these differences deeply. On the basis of studying these differences in this dissertation, rapeseed oil is selected as base oil, and sulfurous additives is taken as extreme pressure antiwear agent. By a lot of tests and modern surface analysis technology, the friction mechanism of sulfurous additives in rapeseed oil is studied extensively, and the responsibility and lubricating characteristics are studied systematically too. At the same time, the compatibility between sulfurous additives and other additives in rapeseed oil is analyzed.Through analyzing the biodegradable mechanism and the biodegradability of various lubricants, it shows that the construction and comprise of lubricants are the main decisive factors of its biodegradability. Analyzing the worn surface by modern surface analysis technology, it reveals the friction mechanisms of the rapeseed oil that it forms physical, chemical adhesion film and adhesion film of saponification by the tribochemical reaction between saturated fatty acid and friction surface. Because intensity and melting point of adhesion film of saponification are low, rapeseed oil only has antiwear ability under middle load, speed and temperature conditions. Through analyzing the tribological behavior, friction regular of the sulfurous additives in rapeseed oil and friction surface, the result shows that olefin sulfide has better load-carrying capacity and antiwear ability than that of sulfurous cottonseed oil at various load, friction time and additive amount. The antiwear property is that at low load and short friction time conditions, the polar radical regiment of olefin sulfide,sulfurous cottonseed oil and rapeseed oil form physical, chemical adhesion film and adhesion film of fatty acid saponification, and at high load and long friction time conditions the polar radical regiment invalidate, and sulfurous additives is decomposed, and ferric sulfide, ferric sulphate are produced by sulfurous additives reacting with surface of metal, and ferric oxide are produced on the surface of metal too. Because ferric sulfide has high anti-shear intensity, it has high load-carrying ability. A tribological model of olefin sulfide acted on rapeseed oil by ANN is established.Compatibility between ZDDP and olefin sulfide is studied by experimentation. The results show that the boundary film is formed because rapeseed oil takes place tribochemical reaction with additives, and ZDDP can modify the friction surface and form Fe-Zn sosoloid which increase the friction surface's anti-wear property and load-carrying capacity. In the compatibility of sulphur and phosphor, it can improve antiwear and extreme pressure capacity of lubricants, but the balance of content between the two kinds of additives should be noticed.Compatibility in the rapeseed oil with some other additives is investigated. In experimentation, ZDDP (T202) is selected as antioxidant and preservative, and alkylsalicylate (T109) is selected as detergent, and bis-succinmide (T152) is selected as ashless dispersant, ethylene propylene copolymer (T612) is selected as viscosity index improver. Compatibility between olefin sulfide, T202 and T109 is investigated, which shows that olefin sulfide has bad compatibility with T109 to load-carrying capacity. Compatibility between olefin sulfide, T202 and T152 is investigated, which shows that compatibility between olefin sulfide and T152 has synergism to load-carrying capacity. Compatibility between olefin sulfide, T202, T109, T152, and T612 is investigated, which shows T612 can reduce load-carrying capacity and improve antiwear property.