Additives extreme-pressure improver

In the other market areas, lead naphthenates are used on a limited basis in extreme pressure additives for lubricating oils and greases. Sodium and potassium naphthenates are used in emulsiftable oils, where they have the advantage over fatty acid soaps of having improved disinfectant properties. Catalyst uses include cobalt naphthenate as a cross-linking catalyst in adhesives (52) and manganese naphthenate as an oxidation catalyst (35). Metal naphthenates are also being used in the hydroconversion of heavy petroleum fractions (53,54) and bitumens (55). 

Lubrication Additive. Cerium fluoride, CeF, can be used as an additive to lubricant formulations to improve extreme pressure and antiwear behavior (43). The white soHd has a crystal stmcture that can be pictured as [CeF] layers separated by [F] atom sheets, a layer stmcture analogous to that of M0S2, a material that CeF resembles in properties. 

Ethers, esters, amides and imidazolidines containing an epithio group are said to be effective in enhancing the antiwear and extreme pressure peiformance of lubricants. Other uses of thiiranes are as follows fuel gas odorant (2-methylthiirane), improvement of antistatic and wetting properties of fibers and films [poly(ethyleneglycol) ethers of 2-hydroxymethyl thiirane], inhibition of alkene metathesis (2-methylthiirane), stabilizers for poly(thiirane) (halogen adducts of thiiranes), enhancement of respiration of tobacco leaves (thiirane), tobacco additives to reduce nicotine and to reduce phenol levels in smoke [2-(methoxymethyl)thiirane], stabilizers for trichloroethylene and 1,1,1-trichloroethane (2-methylthiirane, 2-hydroxymethylthiirane) and stabilizers for organic compounds (0,0-dialkyldithiophosphate esters of 2-mercaptomethylthiirane). The product of the reaction of aniline with thiirane is reported to be useful in the flotation of zinc sulfide. 

The zinc. salts of these acids are extensively used as additives to lubricating oils to improve their extreme-pressure properties. The compounds also act as antioxidants, corrosion inhibitors and detergents. Short-chain dialkyl dithiophosphates and their sodium and ammonium salts are used as flotation agents for zinc and lead sulfide ores. The methyl and ethyl derivatives (RO)2P(S)SH and (RO)2P(S)CI are of particular interest in the large-scale manufacture of pesticides such as parathion, malathion, dimethylparathion, etc. For example parathion. which first went into production as an insecticide in Germany in 1947. is made by the following reaction sequence ... 

The performance of soluble oils is made possible not only by their high specific heat and thermal conductivity but by their low viscosity, which permits good penetration into the very fine clearances around the cutting zone. Consequently, these fluids are used mainly where cooling is the primary requirement. Lubricating properties can be improved by polar additives, which are agents that enhance the oiliness or anti-friction characteristics. Further improvements can be effected by EP (extreme-pressure) additives, which are usually compounds of sulfur or chlorine. 

A) Surface protective additives (i) antiwear (AW)/extreme-pressure (or temperature) improver (EP), (ii) anticorrosion and rust inhibitor, (iii) detergent and dispersant, and (iv) friction modifier. Examples of protective additives are listed in Table 2.4. 

Haltner and Oliver found that several metallic sulphides brought about an improvement in the load-carrying capacity when mixed with molybdenum disulphide. The sulphides included stannic and stannous sulphides, lead sulphide, ferrous suiphide and cuprous and cupric sulphides, and in a standard test procedure there was up to a ten-fold increase in load-carrying capacity. They speculated that the action of the added sulphides was similar to that of extreme-pressure additives in liquid lubricants. This would imply the formation of some protective film on the substrate surface. Pardee later suggested that the effective mechanism was more likely to be oxidation inhibition. An alternative would seem to be the possibility that certain sulphides can act as an additional source of sulphur to form sulphide on the substrate surface, and thus improve adhesion of the molybdenum disulphide, as discussed in the previous chapter. 

Cerium Fluoride can be used as an additive to lubricant formulations to improve extreme-pressure[19]. In addition, this fluoride has been proposed as a high temperature lubricant. 

In the majority of cases, chemical additives are used to enhance the properties of base oils to improve such characteristics as oxidation resistance (ASTM D-2893, ASTM D-4742,ASTM D-5846) change in viscosity (ASTM D-445, IP 71) with temperature, low-temperature flow properties as derived from the pour point (ASTM D-97, ASTM D-5853, ASTM D-5949, ASTM D-5950, ASTM D-5985, IP 15) and fluidity measurements (ASTM D-6351), emulsifying ability (ASTM D-2711), extreme pressure (ASTM D-2782, ASTM D-2783, ASTM D-3233, IP 240), antiwear and frictional properties (ASTM D-5183, ASTM D-6425), and corrosion resistance (ASTM D-4636). The selection of components for lubricating oil formulation requires knowledge of the most suitable crude sources for the base oils, the type of refining required, the types of additive necessary, and the possible effects of the interactions of these components on the properties of the finished lubricating oil. 

Modern lubricants are formulated from a range of base fluids and chemical additives. The base fluid has several functions but it is primarily the lubricant which provides the fluid layer to separate moving surfaces. It also removes heat and wear particles whilst minimizing friction. Many properties of the lubricant are enhanced or created by the addition of special chemical additives to the base fluid, as described in later chapters. For example, stability to oxidation and degradation in an engine oil is improved by the addition of antioxidants whilst extreme pressure, EP, anti-wear properties needed in gear lubrication are created by the addition of special additives. The base fluid acts as the carrier for these additives and therefore must be able to maintain them in solution under all normal working conditions. 

API GL-I. Lubricants intended for manual transmissions operating under such mild conditions that straight petroleum or refined petroleum oil may be used satisfactorily. Oxidation and rust inhibitors, defoamers and pour point depressants may be used to improve the characteristics of these lubricants. Eriction modifiers and extreme pressure additives may not be used. 

Anti-wear additives are but one of a number of additive types formulated into base oils - there are also anti-oxidants. Chapter 4, and anti-acid, detergents anddis-persants. Chapter 7, lubricity, anti-wear, extreme pressure, pour point depressants, anti-rust and anti-foam additives. Chapter 6. Viscosity index improvers, VIIs, are high-molecular weight polymers which alter the temperature dependence of the base oil viscosity. Chapter 5. Taken altogether, the additive mass percentage of a formulated lubricant can be as high as 15-20%, a veritable chemical soup but one which is very carefully formulated and tested. The additives are often multi-functional, thus some VII compounds have a pour point depressant function. Chapters 5 and 6. Some anti-oxidants have anti-wear and also anti-acid functionality. Chapters 4, 6 and 3. Given these cross-interactions, formulation of a final lubricant product is a complex and skilled activity. Chapters 8-13. 

Bis(dithio)thiadiazoles (e.g., 524)113,515 and bis(thiosulfenamides)516 are employed as corrosion inhibitors in lubricants. The antiwear and extreme-pressure properties of lubricating greases are improved by the addition of (polymeric) 3,5-dimercapto-l,2,4-thiadiazole,517 2,4-dialky 1-1,2,4-thiadiazo-... 

The results of the tests demonstrated that the boron-containing thiophosphite derivative is in fact a high performance and multi-fimctional water soluble lubricant additive that was able to remarkably improve the extreme pressure, friction reduction, anti-wear, anticorrosion, and the rust inhibiting properties of the base liquid when added at a low concentration, smaller than 3%. 

Additive tribology functions are clearly antiwear, anti-fatigue, anti-seizure (also known as anti-scoring, anti-scuffing and extreme pressure, EP) and friction modifiers. Rheology modifiers such as polymeric viscosity index improvers and pour point depressants can also impact the tribology function when temperature and shear rate are varied. 

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