الفهرس 
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Abstract
Anti-wear (AW) additive is a tribochemical active substance. The term tribchemical refers to the chemical action in a rubbing or abrasive contact that may affect and be affected by the rubbing or abrasive action. AW additive develops a reaction layer on the workpiece surface during the machining process.
This work presents various percentages of additives with mineral hydraulic oil (ISO-46) determines the proper concentration of AW additives in hydraulic oil.
Hydraulic oils were prepared by blending mineral oil with Zinc Dialkyl dithiophosphate (ZDDP) as additives which contain Zinc/Phosphorus Compounds additives. The tested additives are added to hydraulic oil ISO-46 at different concentrations, by proportions ranging from (0.5 to 1) wt % from the base oil to minimize the wear in the hydraulic system. Tests were carried out to investigate the friction and wear of steel lubricated by these additives using two sliding wear Test methods (Pin-on-Disc Wear Tester & Pin-On- Reciprocating Plate Wear Tester). devices were developed and used to analyze the dynamic friction and wear characteristics under various reciprocating sliding conditions to determine the sliding materials and hydraulic oils which have been applied to assess anti-wear additives in hydraulic oils, reveal the inherent weaknesses of such methods and we will apply a different proportions of AW additives (0%; 0.2 %; 0.4%; 0.6%; 0.8%; 1%) to determine the accurate required proportion.
The experiments of the present pin-on-Disc work reveal that the friction coefficient significantly increased as the applied load increased. The addition of the additive into hydraulic oil decreased the friction coefficient, where the lowest friction values were observed at 1.0 wt. % of the additive content. The same trend was observed when the test specimens were lubricated by relatively high-viscosity hydraulic oil. Besides, wear decreased with increasing additive content. The lowest values were measured for the 1.0 wt. % additive content. The viscosity improvement decreased the values of wear.
The decrease in friction and wear can be attributed to the decomposition products of the additive that work as solid lubricants. While increasing the viscosity enabled the oil to form a relatively thicker oil film between the sliding surfaces.
At the Pin-On- Reciprocating Plate wear test, the friction coefficient decreased as the additive content increased. the lowest values were observed at 0.6 wt. %. Further, an increase in additive content slightly increased friction. wear decreased with increasing additive content. the lowest wear values were observed at 1.0 wt. %. The reduction in friction and wear may be attributed to the protective film’s mechanism of action formed from the additive’s decomposition products. the film worked as a solid lubricant and decreased friction and wear. the anti-wear behaviour of the tested additive can be explained based on the formation of organometallic compounds, where their function depends on forming an iron sulfide layer on the sliding steel surfaces of relatively high hardness that resisted excessive wear. the tribological mechanism is discussed according to the scanning electron microscope (SEM) analytical data, inspecting the topography of the worn surfaces of the test specimens and steel counter-face by optical microscope confirmed the enhancing influence of the tested additive in reducing wear.
After doing experiments measure the wear of the specimen of the used material for the test (bearing steel), determine the friction then calculate the friction coefficient and draw the relation between them.
The results show that the dynamic frictional characteristics vary mainly depending on the additive concentration, a specific additive formulation induces a unique amplitude-dependent friction behaviour. in addition, the influence of different additives on the lubrication mechanism is investigated based on the instrumental analysis of the friction surface, which noted that the wear rate change with different weights and also with changes in the proportion of AW additives,
there is an additional parameter that effect on the wear like temperature, squeezing, viscosity, velocity and the system cleanliness, from the results of wear test, found that the suitable proportions of AW additives (0.6wt %) from mineral base hydraulic oil ISO 46.