Influence of Chemical and Physical Contaminants on the Antiwear Performance of Model Automotive Engine Oil

Abstract

The antiwear performance of simulated used-engine-oil that contained a chemical contaminant (degraded zinc dialkyldithiophosphate (ZnDTP)) was studied with and without physical contamination (carbon black) using a four-ball tribometer. By reacting with cumene hydroperoxide, sec-C6-ZnDTP was degraded and produced many compounds containing both phosphorous and sulphur. The simulated used-oils were found to promote wear. This wear was considered to be due to corrosive wear by the excess reaction of surfaces with the sulphur contained in the degraded compounds. Carbon black was used to model carbon soot, which is another key substance of degraded engine oils, especially in diesel engines, to study the synergism between chemical contamination (ZnDTP degradation) and physical contamination (carbon soot contamination). Carbon black increased wear irrespective of the level of ZnDTP degradation, and the acceleration was much greater in the degraded oils. The wear acceleration by carbon black was observed even when the antiwear film from ZnDTP was already present on the surface. It was suggested that the wear acceleration by carbon black was due to abrasion.

The effects of diesel contaminants on tribological performance on sliding steel on steel contacts

“…where cor is the corrosive wear, abr the abrasive wear from abrasives on the rubbing surfaces, and b a constant. However, the greatest influence is observed for soot contamination, which is believed to be related to its abrasive nature [45][46][47][48]. It is also believed that at increasing levels of soot contamination, increasingly large soot agglomerates are produced, as the dispersant is less able to effectively separate (disperse) the particles allowing them to approach and coalesce into large clusters and at very high concentrations, suspension of the soot particles begins to be a major issue.…”

Enzymatic Synthesis of a Polyol Ester from Levulinic Acid and Trimethylolpropane and Its Tribological Behavior as Potential Biolubricant Basestock

“…Masabumi et al investigated the tribochemical wear using smooth and flat surface and found the partial tribochemical reaction between metal material and lubricant. The reaction had a negative effect on tribological behaviors of biolubricant [ 16 ]. The above results showed that the TMP-tri-LA ester has huge application potential in biolubricant preparation.…”

Particle extrusion in elastohydrodynamic line contacts: Dynamic forces and energy consumption

“…elastic modulus at room temperature F normal force on the particle (equation 22) F max maximum normal force on the particle along its path (equation (24)) F mean mean normal force on the particle along its path (equation (26)) G p shear modulus of the particle G 1 , G 2 shear modulus of a contact solid h local film thickness of the undisturbed EHD contact h c central film thickness of the undisturbed EHD contact h M undisturbed film thickness at the coordinates of the centre of the particle (Figure 1) h 0 final average thickness of the extruded particle " h 1 , " h 2 micro-hardness of a contact surface (equation 14)…”

“…5,6 The majority of studies are experimental. They cover the surface abrasion, indentation, erosion and scuffing by metallic particles of various sizes, hardness and toughness, mainly for sliding surfaces as in journal and sliding bearings in general, [7][8][9][10][11][12][13][14][15][16][17][18] spur gears, 19,20 engine cylinders and piston rings, [21][22][23][24][25][26][27][28] rails 29,30 and magnetic recording discs. 31 A large group of experimental and theoretical studies deals with the contact fatigue and life expectancy of debris-dented rolling contacts as in ball and roller bearings.…”