ZDDP zinc dialkyl

ZDDP (zinc dialkyl dithiophos-phate or zinc diaryl dithiophos-phate)—widely used as an anti-wear agent in motor oils to protect heavily loaded parts, particularly the valve train mechanisms (such as the camshaft and cam followers) from excessive wear. It is also used as an anti-wear agent in hydraulic fluids and certain other products. ZDDP is also an effective oxidation inhibitor. Oils containing ZDDP should not be used in engines that employ silver alloy bearings. All car manufacturers now recommend the use of dialkyl ZDDP in motor oils for passenger car service. 

Tetraethyltin ZDDP, ZDTP Zinc dialkyl dithiophosphates... 

Decomposition of ZDDP takes place in the presence of oxygen, either coming from oxygen dissolved in engine oil or from peroxy radicals and hydroperoxides. Solution studies of the oxidation of zinc dialkyl dithiophosphates by peroxy radicals have shown that disulfides are major reaction products (Paddy et al., 1990 Rossi and Imparato, 1971 Willermet, 1998 Willermet et al., 1983 Willermetand Kandah, 1984). 

In a recent study four independent groups of investigators compared the wear performance of neutral and basic ZDDP neutral [(RO)2P(S)S]2Zn and basic [(R0)2PS2]6Zn40 forms of zinc dialkyl (or diaryl) dithiophosphate, primary di-isobutyl ZDDP, secondary di-isopropyl ZDDP, and aryl di(para-tert-octyl)phenyl ZDDP. 

The TBN values obtained for the fresh, unused, lubricating oil additive package components show results from conductometric and IP 177 (potentiometric) methods being 90% to 98 % and 85% to 90%, respectively, of the corresponding IP 276 (potentiometric) values. The TBN values for some selective products such as zinc dialkyl-dithiophosphate (ZDDP) was observed as an inflection point using the IP 276 (potentiometric) back titration method and also the conductometric method. 

Isobutanol use in the manufacture of zinc dialkyl dithiophosphates (ZDDP), anti-wear lube oil additives, represented 13 percent of domestic consumption. Other alcohols used in this application include methylamyl alcohol, primary amyl,alcohol, n-butanol, 2-ethylhexanol and isooctanol. 

Lubricating-oil consumption in modem engines is generally very low (0.1 liters per 1,(XX) km), and their contribution to catalyst deactivation is small. However, with the requirement for extended catalyst durability and extended drain periods for oils, there is considerable interest about the effect of the oil additives on catalyst life. The chief component of the oil that affects catalyst durability is phosphorus, which is usually present in the form of zinc dialkyl-dithiophosphate (ZDDP). Both combusted and uncombusted forms of ZDDP can reach the catalyst, resulting in different effects on activity depending on the temperature of operation. The level of phosphorus in the oil and the amount of alkaline earth metals present (such as calcium) can dictate the extent to which phosphorus can be deposited on the catalyst. However, studies have shown quite clearly that well-formulated lubricants and well-designed catalysts ensure that the antiwear properties of the oils are maintained and that catalyst-equipped vehicles meet the emission standards required [15,16]. 

P little Zn, and AIPO4 was detected. Phosphorous accumulated as a surface deposit on the outer edge of the washcoat, aged with zinc dialkyl dithiophosphate (ZDDP) and cresyl diphenyl phosphate (CDP). Using the CDP for aging the catalyst, they found that the aged catalyst had a P content of 6.51% P and a layer of 5 pm. 

Liu and Park " in their study on deactivated automotive catalysts in the presence of zinc dialkyl dithiophosphate (ZDDP) and Pb showed the formation of AIPO4 by reaction wit the support. The deactivation was due to several types of interaction with the alumina support, including the formation of an impervious layer on the washcoat or sintering of the y-alumina particles in the washcoat. 

In the boundary lubrication regime, the antiwear and Mction-reduction processes are associated to the build-up of a tribologic film resulting from the chemical reaction between oil additives and sliding surfaces in contact [1-3]. The case of zinc dialkyl dithiophosphate (ZDDP) additive has been extensively studied by analytical transmission electron microscopy (ATEM) and the morphology, nature, structure and tribologic properties of the tribochemical film were obtained [4-6], The Figures 4.1 and 4.2 summarize the main results. 

Figure 5.16 shows the variations of WSD values with the lubrication of LP containing the as-prepared bimetal alloy nanoparticles under different applied loads [19, 27,28]. The results of zinc dialkyl dithiophosphate (ZDDP, a commonly used commercial lubricating additive), Sn and In nanoparticles are also presented for comparison in Figure 5.16(a). It is clear that the In-Sn alloy nanoparticles displayed an excellent AW property under the applied load range... 

Figure 5.22 Variations of electrical contact resistance between tribo-pairs versus friction time (a) lubricated by pure LP, (b) lubricated by pure LP during the first 250 seconds, then adding a drop of LP containing 5 % zinc dialkyl dithiophosphate (ZDDP), (c) Cu nanoparticles and (d) Ag nanoparticles. Test condition a steel ball reciprocally rubbing against a steel plate at a frequency of 15 Hz and a normal load of 5 N at 25°C with the lubrication of a drop of oil. With kind permission from Springer Science and Business Media from Li et al. [6], (c) (2006) Springer Science and Business Media...

Traditional organic sulfur and phosphorus compounds, such as zinc dialkyl (or diaryl) dithiophosphate (ZDDP), tricresyl phosphate (TCP) and sulfurised isobutylene (SIB), have been proved to have good AW and EP properties and achieved wide application. However, these AW/EP additives are chemically more or less reactive, and have lower resistance to heat and oxidation than most modern base oils, and cannot be used to formulate oils for high-temperature applications. The more powerful EP additives usually have some corrosive effect... 

The basic form of ZDDP, Zn4[PS2(R0)2]60, has a structure in which the central oxygen atom is surrounded by four zinc atoms in tetrahedral geometry, and the six 0,0-dialkyl-dithionate groups are attached to the six edges of the tetrahedron (Armstrong et al., 1998). For the basic ZDDP, it was found that the lowest energy corresponds to the attack of the oxide ion on one of the sulfur atoms contained in the additive molecule. The attack induces the cleavage of the three bonds, namely two P-S bonds and one Zn-S bond. Overall, the relative stability of the three forms was found to increase in the order monomeric, dimeric, and basic. 

Additive Loss in Lubricants Additive loss is detrimental to the performance of lubricants. Some additive levels can be monitored by infrared spectroscopy. For instance, anti-wear additives, zinc dithio-dialkyl (diaryl) phosphate (ZDDP) and tri-cresyl phosphate (TCP) contain a common phosphate functional group that can be measured by infrared. The P-O-R (where R = alkyl/aryl) stretch shows a strong IR absorbance for all of these compounds and is used to trend the anti-wear level. The P-O-R stretch area is measured over the region of 1020-960 cm using the general baseline of 2000-600 cm. ... 

The only RR-based antioxidants are reaction products of sulfur or phosphorus pentasulfide with - terpenes (ot-pinene), resin oils and unsaturated esters. Reaction of alcohols (Cg) with phoshorus pentasulfide, followed by a reaction with zinc oxide yields salts of dialkyl dithiophosphoric acid (ZDDP), which are widely used, not only as antioxidants but also as corrosion inhibitors and extreme-pressure additives. Longer-chain alcohols enhance oil solubility. 

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