Oxidation, engine lubricants

These problems of engine lubrication can be overcome by using highly refined oil. The resistance to oxidation is further enhanced by the use of anti-oxidants. The addition of corrosion-inhibitors counters acidic materials produced by combustion at low engine temperatures. 

Finally, deactivation of the catalyst by poisoning elements should be mentioned. Precious metal based catalysts are poisoned by sulfur oxides which mainly originate from the combustion of sulfur-containing fuel constituents, by phosphorus and zinc which mainly originate from some additives in the engine lubricating oil, and by silicium which was sometimes present in some engine seals (Table 21). Also, traces of lead, present in the fuel because of contamination of the fuel supply chain, made an important contribution to the deactivation of the catalyst in the past. 

Aviation oils The bulk of aviation lubricant demand is for both military and civilian gas turbine lubricants. Hydrocarbon oils cannot meet the requirements placed on jet engine oils, primarily lubrication, oxidation and ageing stability. Type 1, the first generation of oils were diesters but over the last 30 years have lost ground to the more expensive polyol esters. Type 2. Some diesters are still used in less demanding applications such as for small private aircraft and turbo-prop engines. Type 2 aviation gas turbine lubricants are produced to a viscosity of 5 cSt at lOO C but for some military applications where low-temperature operability is vital, this is reduced to 3 cSt. 

This contribution presents the degradation reaction mechanisms and processes of lubricants and the factors influencing them. In addition, mechanisms by which antioxidants inhibit lubricant oxidation with respect to specific industrial and engine oil applications are suggested. 

Corrosion/oxidation Although corrosion and oxidation are two different properties, they are very much linked in the engine environment. The presence of construction metals in the lubrication system can catalyse lubricant oxidation and the products of lubricant oxidation can cause corrosion of some metals. Therefore, some methods determine these properties in the same test, for instance, Federal Test Method (FTM) 5308 [17], while others look at the oxidative stability... 

Besides food uses the original linoleic sunflower oil as well as HOSO are used in industrial applications because of their specific properties. For example, in view of the higher oxidative stability high-oleic sunflower oil is used as diesel and gasoline engine lubricant. Containing around 70% linoleic acid, sunflower oil is a semi-drying oil. Insofar as is economically feasible, sunflower oil may replace soybean oil in the manufacture of resins or carrier oils for paint and ink formulations. " ... 

Hazardous Decomp. Prods. CO, CO2, NOx NFPA Health 1, Flammability 1, Reactivity 0 Storage Store in cool, well-ventilated area keep away from ignition sources and naked flame Uses Synthetic flavoring agent in foods and pharmaceuticals oxidation-corrosion stabilizer for combustion engine lubricants sunscreen lotions... 

EIS has been used for general characterization of engine oils [2], studies of lubricants oxidation [5], and monitoring oil degradation due to its contamination by glycol [3], water [11], and soot [12]. The combination of EIS and multivariate data analysis can be used to simultaneously determine the amotmts of soot and diesel in engine oil [13] as well as the concentration and pH of an industrial cutting fluid [14]. 

Applications - Esters, both dibasic and polyol esters, are used as co-base stocks with PAO or other hydrocarbon base stocks in synthetic automotive engine lubricants and industrial lubricants. Polyol esters are used in aircraft tuibine oils due to their excellent thermal and oxidative stabilities, good lubricity, high VI and excellent low temperature properties (<-40°C). Esters are also used in synthetic compressor oils for ozone-ffiendly refngeration units. Because of their high biodegradability and low toxicity, esters are often the base oils of choice for many environmentally-aware... 

The effect of biodiesel fuel from Jatropha curcas oil in DI diesel engines on the components of the engine influenced by fuel before (injection pump, injector) and after the combustion process (piston crown, cylinder head) were studied (Reksowardojo et al., 2005a,c). The test bed procedure used was that commonly used for injection cleanliness evaluation adopted by World-Wide Fuel Charter (December 2002) (ACEA, 2002). Exhaust gas emissions such as nitrogen oxides (NO c), carbon monoxide (CO), brake-specific fuel consumption (BSFC), and engine lubricant before and after the test were also measured. 

Lubricants. Petroleum lubricants continue to be the mainstay for automotive, industrial, and process lubricants. Synthetic oils are used extensively in industry and for jet engines they, of course, are made from hydrocarbons. Since the viscosity index (a measure of the viscosity behavior of a lubricant with change in temperature) of lube oil fractions from different cmdes may vary from +140 to as low as —300, additional refining steps are needed. To improve the viscosity index (VI), lube oil fractions are subjected to solvent extraction, solvent dewaxing, solvent deasphalting, and hydrogenation. Furthermore, automotive lube oils typically contain about 12—14% additives. These additives maybe oxidation inhibitors to prevent formation of gum and varnish, corrosion inhibitors, or detergent dispersants, and viscosity index improvers. The United States consumption of lubricants is shown in Table 7. 

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