Microstructure and nanohardness of Ag and Ni under friction in boundary lubrication

AbstractLaser surface texturing (LST) has been proven to improve the tribological performance of machine elements. The micro-scale patterns manufactured by LST may act as lubricant reservoirs, thus supplying oil when encountering insufficient lubrication. However, not many studies have investigated the use of LST in the boundary lubrication regime, likely due to concerns of higher contact stresses that can occur with the increasing surface roughness. This study aims to examine the influence of LST on the fatigue lifetime of thrust rolling bearings under boundary lubrication. A series of periodic patterns were produced on the thrust rolling bearings, using two geometrically different designs, namely cross and dimple patterns. Base oil ISO VG 100 mixed with 0.05 wt% P of zinc dialkyldithiophosphate (ZDDP) was supplied. The bearings with cross patterns reduce the wear loss by two orders of magnitude. The patterns not only retain lubricant in the textured pockets but also enhance the formation of an anti-wear tribofilm. The tribofilm generation may be improved by the higher contact stresses that occur when using the textured surface. Therefore, in contrast to the negative concerns, the ball bearings with cross patterns were instead found to increase the fatigue life by a factor of three.

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Pengaruh Penambahan Minyak Kelapa dan Sawit Terhadap Sifat Fisik dan Tribologi Pelumas SAE 40

Jurnal METTEK ◽

10.24843/mettek.2019.v05.i01.p01 ◽

2019 ◽

Vol 5 (1) ◽

pp. 1

Author(s):

Dedison Gasni ◽

KM Abdul Razak ◽

Ahmad Ridwan ◽

Muhammad Arif

Keyword(s):

Fatty Acids ◽

Coefficient Of Friction ◽

Tribological Properties ◽

Palm Oil ◽

Boundary Lubrication ◽

Viscosity Index ◽

Coconut Oil ◽

High Viscosity ◽

Mineral Oil ◽

Lubricating Oil

Penelitian ini bertujuan untuk mengetahui efek dari penambahan minyak kelapa dan sawit terhadap sifat fisik dan tribologi pelumas SAE 40. Vegetabel oil, seperti; minyak kelapa dan sawit, memiliki nilai viskositas indek yang tinggi dan sifat pelumasan yang baik terutama didaerah boundary lubrication jika dibandingkan dengan mineral oil (SAE 40). Hal ini disebabkan karena vegetabel oil memiliki kandungan fatty acids yang tidak dimiliki oleh mineral oil. Keunggulan lain dari minyak kelapa dan sawit adanya sifat yang ramah lingkungan karena mudah terurai di alam dan dapat diperbaharui. Pada penelitian ini sifat yang baik dari minyak kelapa dan sawit ini akan dimanfaatkan sebagai zat aditif pada minyak pelumas SAE 40. Pengujian dilakukan terhadap sifat fisik dan tribology dengan penambahan 5%, 10%, 15%, dan 20% berat dari minyak kelapa dan sawit ke dalam minyak pelumas SAE 40. Pengujian sifat fisik terdiri dari pengukuran viskositas pada temperatur 400C dan 1000C dan viskositas index. Pengujian sifat tribologi untuk menentukan keausan dan koefisien gesek berdasarkan ASTM G99 dengan menggunakan alat uji pin on disk. Dari hasil pengujian diperoleh bahwa dengan penambahan minyak kelapa dan sawit kedalam minyak pelumas SAE 40 terjadi peningkatan viskositas indeks. Peningkatan viskositas indeks sebanyak 17% dengan penambahan 20% minyak sawit. Terjadi perubahan sifat tribologi dengan penambahan minyak sawit, berupa penurunan keausan dan nilai koefisien gesek dibandingkan dengan penambahan minyak kelapa. This study aims to determine the effect of coconut and palm oils as additives to physical and tribological properties of SAE 40 lubricating oil . Vegetable oils, such as; coconut oil and palm oil, have high viscosity index and good lubrication properties, especially in boundary lubrication compared to mineral oil. This is due to vegetable oil having fatty acids that are not owned by mineral oil. The advantages of coconut oil and palm oil are environmentally friendly properties because they are biodegradable and renewable. In this study, the good properties of coconut and palm oils will be used as additives in SAE 40 lubricating oil. Tests are carried out on the physical and tribological properties with the addition of 5%, 10%, 15%, and 20% by weight of coconut and palm oils into SAE 40 lubricating oil. Physical properties testing consists of measuring viscosity at temperatures of 400C and 1000C and viscosity index. The tribological test is to determine wear and coefficient of friction based on ASTM G99 using a pin on disc test equipment. From the test results, it was found that coconut and palm oils as additives into SAE 40 lubricating oil could increase in viscosity index. The increase of the viscosity index was 17% by adding 20% of palm oil. There was a change of tribological properties in the form of decreasing on the wear and the coefficient of friction with the addition of palm oil compare to addition of coconut oil.

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Comparison Between the Action of Nano-Oxides and Conventional EP Additives in Boundary Lubrication

Lubricants ◽

10.3390/lubricants8050054 ◽

2020 ◽

Vol 8 (5) ◽

pp. 54

Author(s):

Valdicleide Silva Mello ◽

Marinalva Ferreira Trajano ◽

Ana Emilia Diniz Silva Guedes ◽

Salete Martins Alves

Keyword(s):

Friction Coefficient ◽

Boundary Lubrication ◽

Friction And Wear ◽

Film Formation ◽

Environmental Issues ◽

Protective Film ◽

Extreme Pressure ◽

Extreme Pressure Additives ◽

Environmental Requirements ◽

Lubrication Conditions

Additives are essential in lubricant development, improving their performance by the formation of a protective film, thus reducing friction and wear. Some such additives are extreme pressure additives. However, due to environmental issues, their use has been questioned because their composition includes sulfur, chlorine, and phosphorus. Nanoparticles have been demonstrated to be a suitable substitute for those additives. This paper aims to make a comparison of the tribological performance of conventional EP additives and oxides nanoparticles (copper and zinc) under boundary lubrication conditions. The additives (nanoparticles, ZDDP, and sulfur) were added to mineral and synthetic oils. The lubricant tribological properties were analyzed in the tribometer HFRR (high frequency reciprocating rig), and during the test, the friction coefficient and percentual of film formation were measured. The wear was analyzed by scanning electron microscopy. The results showed that the conventional EP additives have a good performance owing to their anti-wear and small friction coefficient in both lubricant bases. The oxides nanoparticles, when used as additives, can reduce the friction more effectively than conventional additives, and displayed similar behavior to the extreme pressure additives. Thus, the oxide nanoparticles are more environmentally suitable, and they can replace EP additives adapting the lubricant to current environmental requirements.

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A molecular dynamics simulation of boundary lubrication: The effect of n-alkanes chain length and normal load

Wear ◽

10.1016/j.wear.2013.01.052 ◽

2013 ◽

Vol 301 (1-2) ◽

pp. 62-69 ◽

Cited By ~ 30

Author(s):

Xuan Zheng ◽

Hongtao Zhu ◽

Buyung Kosasih ◽

A. Kiet Tieu

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Chain Length ◽

Boundary Lubrication ◽

Normal Load ◽

Dynamics Simulation

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Wear Behavior and Chemical Friction Modification in Binary-Additives System under Boundary-Lubrication Conditions

A S L E Transactions ◽

10.1080/05698198108983051 ◽

1981 ◽

Vol 24 (4) ◽

pp. 517-525 ◽

Cited By ~ 6

Author(s):

Masayuki Kagami ◽

Masataro Yagi ◽

Seiichiro Hironaka ◽

Toshio Sakurai

Keyword(s):

Boundary Lubrication ◽

Wear Behavior ◽

Lubrication Conditions

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Mechanism of Boundary Lubrication and the Edge Effect

Journal of Basic Engineering ◽

10.1115/1.3650662 ◽

1965 ◽

Vol 87 (3) ◽

pp. 735-739 ◽

Cited By ~ 9

Author(s):

Y. Tamai ◽

B. G. Rightmire

Keyword(s):

Thin Film ◽

Acid Solution ◽

Palmitic Acid ◽

Boundary Lubrication ◽

Frictional Resistance ◽

Copper Surface ◽

Bulk Liquid ◽

Attraction Force ◽

Thin Film Lubrication ◽

Film Lubrication

Experimental work was carried out on the boundary lubrication of a copper-copper couple with pure cetane, palmitic acid solution of cetane, and some other organic materials. The purpose was to get information about α and μlube, which appear in the friction equation: μ=αμsolid+(1−α)μlube, by using two different kinds of copper surface, a clean surface, and an oxidized surface. α was found to be small with palmitic acid solution, and the estimated shear strength of palmitic acid was high under the examined condition. α and μlube seemed to be properties which are independent of each other. α is closely related to the attraction force between the lubricant and the substrate, whereas μlube is related to the complexity of molecular structure of the lubricant. A comparison was made of bulk-liquid and thin-film lubrication. μlube was smaller in thin-film lubrication than it was in bulk-liquid lubrication. This suggests that the frictional resistance may be partly contributed by liquid in the edge space around the real contact.

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