Highly effective friction modifiers from nano-sized materials

Abstract

Synthesis and the tribological properties of oil-soluble friction modifiers made from surface-modified (lyophilized) nanoparticles of molybdenum trisulfide (nano-MoS 3 ) are described. The synergistic effect of nano-MoS 3 and zinc dialkyldithiophosphate (ZnDDP) is demonstrated. Addition of the latter is effective at high temperatures and low concentrations.The increase in the price of crude and petroleum products has made it necessary to conserve sources of energy. One of the fundamental methods of reducing fuel consumption is to decreases losses to friction in machines and mechanisms by reducing the friction coefficient in contact of metal surfaces.During operation of parts in conditions of boundary or mixed friction, oil-soluble friction modifiers based on molybdenum compounds, of which molybdenum dialkyldithiophosphates and dialkyldithiocarbamates are the best known, are the most promising [1]. The basic drawbacks of these compounds as lube oil additives include the relatively complicated methods of synthesizing them with toxic reagents and the comparatively high price. Recent studies demonstrated the important prospects for use of inorganic nanoparticles as additives that improve the tribological properties of lubricants [2]. For example, a method of obtaining oil-soluble surfacemodified (lyophilized) nanoparticles of molybdenum trisulfide MoS 3 through water-in-oil microemulsions and the antifriction properties of oil compositions with this additive were communicated in [3][4][5].We report the results of a study of the tribological properties of nanoparticles of MoS 3 obtained by thermal decomposition of ammonium dithiomolybdate in a hot amphiphilic matrix at 100-160°C [6,7]. The proposed method of synthesis is distinguished by comparative simplicity and processability; combined with an important decrease in the cost of the product, these attributes enhance the prospects for its practical use. Tetraalkylammonium salts were used as the amphiphilic matrix. The exchange reaction takes place in the first stage of synthesis:

A review of recent developments of friction modifiers for liquid lubricants (2007–present)

“…So, surface modification was proposed to improve the solubility in nonpolar hydrocarbon oils. The synergistic effect of surface-modified nanoparticles of molybdenum trisulfide (nano-MoS 3 ) and ZDDP was demonstrated [21].…”

“…In the last few years, it has been proposed in many patents and articles that the derivatives of alcohol (7,8), ether (9), ester (19,20), mercaptocarboxylate (21,22), thioester (23) and carboxylate (24,25) are useful friction modifiers in lubricants ( Fig. 4) [62][63][64][65][66][67][68][69][70][71][72][73].…”

“…Due to the (9), ester (10)(11)(12)(13)(14)(15)(16)(17)(18), ketone (19,20), mercaptocarboxylate (21,22), thioester (23) and carboxylate (24,25).…”

Improved frictional behavior of SiC derived carbon coating using MoS3 as a solid lubricant

“…On one hand, MoS 3 can be synthesized by liquid-phase reaction in ambient environment [14], which is suitable for the synthesis of the CDC-based composites. On the other hand, MoS 3 possesses good lubricating behaviors [15][16][17]. Lince et al [18] demonstrated that MoS 3 exhibited excellent lubricating ability, which is identical to the well-known MoS 2 solid lubricant.…”

Tribological Properties of Automotive Lubricant SAE 20W-40 Containing Nano-Al2O3 particles

“…The addition of nano-sized lubricant additives as friction modifier is beneficial because it might reduce the use of phosphorus containing additives. Phosphorus containing additives are not environment friendly [12]. Additionally, NPs can easily enter fine asperities where micro-sized particles cannot reach.…”