Effect Of Antiwear Additives Research Articles

The Influence of Steel Composition on the Formation and Effectiveness of Anti-wear Films in Tribological Contacts

The effectiveness of antiwear additives in laboratory tests is commonly evaluated using specimens made of AISI 52100 through-hardened bearing steel. However, many lubricated machine components are made of steels with significantly different material compositions, which raises an important practical question of whether the performance of antiwear additives with these other steel types is different from that established with AISI 52100. To help answer this question, this paper investigates the influence of steel composition on the formation and effectiveness of antiwear films. Four steels that are commonly used in tribological applications, namely AISI 52100 through-hardened bearing steel, 16MnCr5 case-carburised gear steel, M2 high speed steel and 440C stainless steel are tested in rolling-sliding, ball-on-disc contacts lubricated with three custom-made oils, one containing ZDDP and two containing different types of ashless antiwear additives. The relative effectiveness of their boundary films was assessed by measuring their thickness and associated wear and friction over 12 h of rubbing at two specimen roughness levels. For ZDDP it was found that the formation of antiwear film was not significantly influenced by steel composition or specimen surface roughness. A similar tribofilm thickness, final tribofilm roughness and friction was observed with all four steels. No measurable wear was observed. By contrast, for the ashless antiwear additives the thickness and effectiveness of their tribofilms was strongly influenced by steel composition, particularly at higher roughness levels. The exact trends in film thickness vs steel relationship depended on the specific chemistry of the ashless additive (ester-based or acid-based) but in general, relative to AISI 52100 steel, M2 steel promoted ashless tribofilm formation whilst 440C retarded ashless tribofilm formation. This behaviour is attributed to the presence of different alloying elements and the ability of the additives to extract metal cations from the rubbing surfaces to support the growth of a tribofilm. In all cases ZDDP films were thicker and rougher, and produced higher friction than those formed by the ashless additives. However, unlike ZDDP, ashless blends generally produced significant wear, particularly with 16MnCr5 and M2 steels. The results indicate that to ensure reliable performance of a given machine component, the chemistry of an ashless antiwear additive should be matched with the types of steel present in the lubricated machine.

Effects of antiwear additives in the base oil on the tribological performance of hydrogen-free DLC coating

Purpose – The purpose of this study is to investigate the effects of zinc dialkyl dithiophophates (ZDDP) and ash-less triphenyl phosphorothionate (TPPT) on hydrogen-free diamond-like carbon (DLC) coatings. For many years, ZDDP have traditionally been used in engine oils as antiwear (AW) and extreme pressure (EP) additives. However, additives containing sulfated ash, phosphorus and sulfur (SAPS) have a detrimental effect on the exhaust after-treatment device found on modern vehicles. Besides the automotive industry, DLC is also used in hydraulic applications where zinc-free and ash-less hydraulic fluids have gradually gained popularity in recent years. Design/methodology/approach – The tribological tests were performed using a disk-on-cylinder tribometer, where the stationary hydrogen-free DLC-coated steel disk formed a line contact with an uncoated rotating steel shaft under lubricated conditions. Findings – It was found that TPPT and ZDDP separately at a concentration of 1.0 wt% increased the amount of friction of the base oil by approximately four times. TPPT appeared more effective than ZDDP in minimizing wear on the DLC-coated surface. Also, primary ZDDP seemed to have a more detrimental effect on the DLC-coated surface compared to a mixture of primary and secondary ZDDP. With regard to surface roughness of the hydrogen-free DLC-coated surface, the values corresponding to a lubricant containing TPPT were lower than those obtained for a lubricant with ZDDP and a lubricant without any additive. Originality/value – This is the first report on the effects of ZDDP and ash-less TPPT on the tribology of hydrogen-free DLC coatings.

A suitable method for journal bearing wear measurement

Purpose – Ideally, there is no wear in hydrodynamic lubrication regime. A small amount of wear occurs during start and stop of the machines and the amount of wear is so small that it is difficult to measure with accuracy. Various wear measuring techniques have been used where out-of-roundness was found to be the most reliable method of measuring small wear quantities in journal bearings. This technique was further developed to achieve higher accuracy in measuring small wear quantities. The method proved to be reliable as well as inexpensive. The paper aims to discuss these issues. Design/methodology/approach – In an experimental study, the effect of antiwear additives was studied on journal bearings lubricated with oil containing solid contaminants. The test duration was too long and the wear quantities achieved were too small. To minimise the test duration, short tests of about 90 min duration were conducted and wear was measured recording changes in variety of parameters related to weight, geometry and wear debris. The out-of-roundness was found to be the most effective method. This method was further refined by enlarging the out-of-roundness traces on a photocopier. The method was proved to be reliable and inexpensive. Findings – Study revealed that the most commonly used wear measurement techniques such as weight loss, roughness changes and change in particle count were not adequate for measuring small wear quantities in journal bearings. Out-of-roundness method with some refinements was found to be one of the most reliable methods for measuring small wear quantities in journal bearings working in hydrodynamic lubrication regime. By enlarging the out-of-roundness traces and determining the worn area of the bearing cross-section, weight loss in bearings was calculated, which was repeatable and reliable. Research limitations/implications – This research is a basic in nature where a rudimentary solution has been developed for measuring small wear quantities in rotary devices such as journal bearings. The method requires enlarging traces on a photocopier and determining the shape of the worn area on an out-of-roundness trace on a transparency, which is a simple but a crude method. This may require an automated procedure to determine the weight loss from the out-of-roundness traces directly. This method can be very useful in reducing test duration and measuring wear quantities with higher precision in situations where wear quantities are very small. Practical implications – This research provides a reliable method of measuring wear of circular geometry. The Talyrond equipment used for measuring the change in out-of-roundness due to wear of bearings indicates that this equipment has high potential to be used as a wear measuring device also. Measurement of weight loss from the traces is an enhanced capability of this equipment and this research may lead to the development of a modified version of Talyrond type of equipment for wear measurements in circular machine components. Originality/value – Wear measurement in hydrodynamic bearings requires long duration tests to achieve adequate wear quantities. Out-of-roundness is one of the geometrical parameters that changes with progression of wear in a circular shape components. Thus, out-of-roundness is found to be an effective wear measuring parameter that relates to change in geometry. Method of increasing the sensitivity and enlargement of out-of-roundness traces is original work through which area of worn cross-section can be determined and weight loss can be derived for materials of known density with higher precision.

Synergistic effect of antiwear additives and antioxidants in vegetable oil

AbstractCertain vegetable oils have been recognised as promising candidates for environmentally friendly lubricants. Their lubricity can be optimised using antiwear additives. However, decomposition of the additives, accompanied by auto‐oxidation of the vegetable oils, has been found to occur. In other words, the antiwear additives may degrade in vegetable oils, and give less oxidative stability. In order to understand the mechanism, oxidation testing of a vegetable oil was performed by monitoring the peroxide value (POV). It was observed that POV increases as soon as oxidation starts. The value reached 1400–1500 ppm within 50 h of reaction time. Then it decreased to an equilibrium value of 400–500 ppm within 200 h. Antioxidants to prevent peroxide generation were examined. Phenolic antioxidants and zinc dialkyldithiocar‐bamate exhibited good results with regard to preventing peroxide generation, whereas aromatic amines gave poor results. A synergistic effect that prevents the decomposition of the antiwear additives was found.

Effect of Anti-Wear Additives on Seizure Resistance of Vegetable Oils in Four-Ball Test

Effect of Anti-Wear Additives on Seizure Resistance of Vegetable Oils in Four-Ball Test

817 四球試験における植物油の耐焼付き性能に及ぼす耐摩耗添加剤の影響

817 四球試験における植物油の耐焼付き性能に及ぼす耐摩耗添加剤の影響

Effects of antiwear additives on the friction and wear of Si3N4/steel sliding contacts

Si3N4-based ceramics have been used for machining cast iron at very high speeds. However, they have been found to be unsuitable for machining steel because of the severe wear of the ceramic cutting tools, which is thought to be mainly caused by the chemical dissolution of the ceramic in the chip at the high temperatures reached at the cutting edge. In this paper, a simulation test was carried out on a pin-on-disk tribometer in order to investigate the effects of two antiwear additives on the friction and wear of Si3N4/1045 steel sliding contacts. Sliding speeds 1.6 m s−1 and 3.2 m s−1 were used, respectively, the selected test load was 117.6 N. The test results show that lubricants containing antiwear additives used in this lest could greatly reduce the friction coefficient and wear rate of Si3N4 ceramics. Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction spectroscopy were used for the analyses of the worn surfaces. Tribochemical reactions about the additives occurred on the frictional surfaces, the tribochemical films formed on the rubbing surfaces improved the boundary lubrication conditions of the sliding contacts, the interdiffusion and adhesion between the rubbing surfaces were prevented or were greatly reduced.

The Effect of Antiwear Additives in Synthetic Base Oils.

The Effect of Antiwear Additives in Synthetic Base Oils.

Effects of anti-wear additives on friction and wear properties of Cr 2O 3 coating

The effects of some anti-wear additives on the friction and wear behaviour of plasma-sprayed Cr 2O 3 coating were investigated using a block-on-ring tester at ambient conditions. The results show that zinc dialkyldithiophosphate (ZDDP), tricesyl phosphate (TCP) and tributyl phosphate (TBP) significantly reduce the wear of Cr 2O 3 coating lubricated by paraffin oil. Additive concentrations as well as sliding time have great influence on the wear. The friction coefficient varies slightly with test conditions. The analysis by XPS of worn surfaces indicates that the wear resistance of these additives is due to the formation of tribochemical reaction films by reacting with Cr 2O 3 coatings.

ビッカースＶ１０４Ｃベーンポンプによる高含水流体の摩耗防止性能評価

The Vickers V1044C Vane Pump Test has been widely applied to estimate the anti-wearp roperties of hydraulic fluids such as mineral oils and various fire-resistan ftluids. This paper studies the applicability of these test methods regarding high-water content fluids (HWCF). A s a result of this work, it wasr evealedth at the test pressuref or high-waterc ontent fluidso f the present state of the art should be low, namely 10-20 bar. Therefore, the special feature of this test, in which it simulates, though not satisfactorily the actual function of fluid powere lements, is thus lost for usual high-water content fluids. This test was able to show, however, the effects of anti-wear additives. Therefore, the test procedure itself maybe used to estimate the effect as an anti-wear agent when a high-water content fluids is finally developed.

Effectiveness of antiwear additives in polymethacrylate-compounded oils

Effectiveness of antiwear additives in polymethacrylate-compounded oils

Measuring electron work function to evaluate the effectiveness of antiwear additives

1. A method has been described for evaluating the adsorption properties of oils by measuring electron work function. 2. Using a series of oils containing additives, a connection has been shown between their adsorption properties, as determined by measuring the electron work function, and antiwear properties.

Effectiveness of antiwear additives and the temperature at which they interact with a rubbing surface

1. It has been established by thermogravimetric analysis that the additives that were studied may be classified in two groups based on the nature of their interaction with iron. Additives of the first group are subjected to partial decomposition, and only then do the decomposition products interact with iron; additives of the second group react directly with iron. 2. The thermogravimetric results agree well with those from friction experiments in a KT-2 tester on the same additives.

The effect of anti-wear additives on the lubrication properties of corrosion preventive oils : C. J. Quilty and P. Martin, Lubrication Eng. 25 (6) (1969) 240–245 ; 4 figs., 2 tables, 14 refs.

The effect of anti-wear additives on the lubrication properties of corrosion preventive oils : C. J. Quilty and P. Martin, Lubrication Eng. 25 (6) (1969) 240–245 ; 4 figs., 2 tables, 14 refs.

Effect of antiwear additives on stability of organosilicon fluids in rolling friction

1. When antiwear additives are used in lubricants for rolling-contact bearings, favorable effects due solely to antiwear action cannot be obtained unless boundary-lubrication conditions are achieved in the bearing; as a rule, this occurs only at high loads and high temperatures, with slow rotation or oscillating motion, or with combinations of these conditions. 2. Apart from their antiwear action, antiwear additives affect the stability of oils in a rolling-friction zone. Here the amount and nature of the effect (increase or decrease in stability) depends on the operating temperature and the chemical composition of the additive. 3. The selection of additives for rolling-contact bearing lubricants should be based on evaluations of their effects on both the antiwear properties of the lubricants and the stability of the lubricants in the rolling-friction zone.