In addition to the above general physical and chemical properties, each lubricant product should also have a characterization of its use characteristics of the special physical and chemical properties. The higher the quality requirements, or the specificity of the strong oil, its special physical and chemical properties of the more prominent.
The test methods that reflect these special physical and chemical properties are briefly described as follows:
(1) Oxidation stability Oxidation stability of lubricating oil anti-aging properties, some of the longer life of industrial lubricants have this indicator requirements, and thus become a special performance of these kinds of oil requirements. There are many methods to determine the oxidation stability of oil products, basically, there is a certain amount of oil in the presence of air (or oxygen) and metal catalysts, at a certain temperature oxidation of some time, and then the determination of the acid value of oil, viscosity changes and sediment production. All lubricants have different automatic oxidation tendencies depending on their chemical composition and external conditions.
With the use of the process of oxidation, and thus gradually generated some aldehydes, ketones, acids and gum, asphaltene and other substances, oxidation stability is to inhibit the use of oil products such as the production of material performance.
(2) Thermal stability Thermal stability indicates the high temperature resistance of oil, that is, the resistance of lubricating oil to thermal decomposition, i.e. thermal decomposition temperature. Some high quality anti-wear hydraulic oil, compressor oil and so on have put forward the requirement of thermal stability. The thermal stability of oil is mainly dependent on the composition of base oil, many additives with lower decomposition temperature have adverse effects on oil stability, and antioxidants can not obviously improve the thermal stability of oil products.