Multiply Alkylated Cyclopentane Research Articles

Probing the Conductive and Tribological Behaviors of Solid Additives in Multiply Alkylated Cyclopentanes for Sliding Electrical Contact.

Sliding electrical contacts need to be lubricated by conductive lubricants to perform low energy dissipation, high reliability, and long service life. This work studied the thermal stability, anti-corrosion capacity, and conductive, and tribological behaviors of several solid additives in multiply alkylated cyclopentanes (MACs), including carbon nanotubes (CNTs), multilayer graphene (MG), and silver microparticles. The results showed that all the additives possessed favorable thermal stability and corrosion resistance; in particular, CNTs and MG exhibited lower and more stable electrical contact resistance (ECR) and better lubricity abilities than Ag microparticles. Moreover, based on the characterization of the worn surfaces and the film thickness calculation, the favorable conductive and tribological properties of CNTs and MG were related to the high conductivity and specific structure of the additives and the good chemical inertness of MACs.

An investigation of tribochemical reaction kinetics from the perspective of tribo-oxidation

The tribochemical reaction rate of multiply alkylated cyclopentane (MAC) was studied from the perspective of tribo-oxidation. The activation energy of MAC oxidation reaction and respective decrease of activation energy owing to catalysis from iron and Fe3O4 were determined by means of auto-oxidative tests. The sum of the reduced activation energy due to iron and Fe3O4 was less than that in tribological test, which highlighted the crucial role of shear stress in accelerating tribo-oxidation reaction. Additionally, the experimental process was replicated by utilizing reactive molecular dynamics (MD) simulations. The simulation results revealed the significance of shear stress in tribo-oxidation reaction and the catalytic mechanism of iron, Fe3O4, and shear stress for promoting oxidation reaction was interpreted.

Ionic Liquids as Performance Ingredients in Space Lubricants.

Low vapor pressure and several other outstanding properties make room-temperature ionic liquids attractive candidates as lubricants for machine elements in space applications. Ensuring sufficient liquid lubricant supply under space conditions is challenging, and consequently, such tribological systems may operate in boundary lubrication conditions. Under such circumstances, effective lubrication requires the formation of adsorbed or chemically reacted boundary films to prevent excessive friction and wear. In this work, we evaluated hydrocarbon-mimicking ionic liquids, designated P-SiSO, as performance ingredients in multiply alkylated cyclopentane (MAC). The tribological properties under vacuum or various atmospheres (air, nitrogen, carbon dioxide) were measured and analyzed. Thermal vacuum outgassing and electric conductivity were meas- ured to evaluate ‘MAC & P-SiSO’ compatibility to the space environment, including the secondary effects of radiation. Heritage space lubricants—MAC and perfluoroalkyl polyethers (PFPE)—were employed as references. The results corroborate the beneficial lubricating performance of incorporating P-SiSO in MAC, under vacuum as well as under various atmospheres, and demonstrates the feasibility for use as a multifunctional additive in hydrocarbon base oils, for use in space exploration applications.

Effect of Accelerated Aging on the Chemical Signature and Performance of a Multiply-Alkylated Cyclopentane (MAC) Lubricant for Space Applications

The thermo-oxidative degradation of a multiply-alkylated cyclopentane (MAC) lubricant for space applications is investigated. Accelerated aging tests at temperature levels between 60 °C and 150 °C are performed and the aging behavior is investigated in detail with spectroscopic, mass spectrometric and chromatographic techniques as well as tribological testing on a ball-on-disk setup. The degree of oxidative aging of the MAC lubricant is monitored with the carbonyl index (CI), which is shown to be well-suited to monitor the degree of degradation of the lubricant. Gas chromatography/mass spectrometry (GC/MS) analysis is applied to identify 9-nonadecanone as the main volatile degradation product in all aged samples, suggesting a similar decomposition pathway at all tested temperatures. Size exclusion chromatography (SEC) is further applied to confirm the formation of higher molecular weight degradation products upon aging, affecting the viscosity of the lubricant. In the subsequent ball-on-disk tests, a good correlation of the performance loss with the FTIR measurements is seen and CI values of approx. 0.64 are regarded as threshold for the complete loss of performance at the selected test conditions. The determined CI values in dependence of the aging duration are further used to perform a time–temperature superposition (TTS) to acquire a master curve for accelerated aging. In the resulting Arrhenius plot, non-linear behavior is observed, highlighting the importance of a precise control of accelerated aging parameters for reliable lifetime estimations.

Study on the conductive and tribological properties of copper sliding electrical contacts lubricated by ionic liquids

Abstract To reduce energy dissipation, improve reliability and lifetime of sliding electrical contact, ionic liquids (ILs) and multiply-alkylated cyclopentanes (MACs) were employed to lubricate copper sliding electrical contacts. Their physical properties, electrical contact resistance (ECR) and tribological properties were investigated in detail. Standard deviation was introduced to evaluate the stability of conductive and tribological behaviors. Results show that ILs not only greatly lower the COF, ECR and wear volumes, but also make them more stable as compared with MACs. Based on the characterization and analysis of the lubricants and worn surfaces, the conductive and tribological behaviors of different lubricants under current-carrying friction are related to the nature of the lubricants and the protective film generated on the worn surfaces.

Tribological behaviors of fluid-lubricated DLC films under sliding and fretting conditions

To meet the ever–increasing performance requirements of mechanical equipment under various working conditions, lubrication schemes have been transformed from onefold to synergistic lubrication. Here we introduced the synergistic lubrication systems consisting of DLC film as anti–wear supporting layer and two high–performance fluids (ionic liquids (ILs) and multiply–alkylated cyclopentanes (MACs)) as lubricating layer, and their tribological properties were conducted under sliding and fretting conditions. Results show that ILs and MACs can improve the friction reduction and wear resistance of DLC film under sliding condition because a boundary lubrication film was formed by physical adsorption film and tribo–transfer film, which could minimize the shear and adhesion. Under fretting condition, the lubrication function of ILs and MACs is not superior to that under sliding condition partly because intact fluid-film has difficulty in formation on the fretting regime, and also partly because fretting conditions induce the transformation of fretting running regime from partial slip to gross slip.

Self-assembled monolayer of multiply-alkylated cyclopentenes on silicon via thiol-ene “click” reaction and its self-lubricating properties

Self-assembled monolayer (SAM) of multiply-alkylated cyclopentenes (MACEs), homologue of the famous hydrocarbon mobile lubricant multiply alkylated cyclopentanes (MACs), was fabricated as self-lubricating film on the surface of the thiol-functionalized silicon wafer (HS-Si) via facile thiol-ene “click” reaction, induced with UV-light or heating. The surface property analysis, including static contact angle and surface roughness, indicated the successful self-assembly. The microtribological tests of the different samples on a UMT-1 tribometer (CETR) in a ball-on-plate contact configuration showed that the SAMs possessed excellent self-lubricating property, in which the SAMH obtained via the heating-induced thiol-ene “click” reaction had the lower friction coefficient and longer tribological durability than the SAMUV one prepared under UV-irradiation. The proposed self-lubricating strategy is expected to be used in the lubrication of micro-/nano-electromechanical systems (MEMSs/NEMSs).

ボールねじの運転性能と宇宙用MAC系グリースの油膜形成挙動

ボールねじの運転性能と宇宙用MAC系グリースの油膜形成挙動

Tribological Behavior of AlCoCrFeNi(Ti0.5) High Entropy Alloys under Oil and MACs Lubrication

The tribological properties of AlCoCrFeNi and AlCoCrFeNiTi0.5 high entropy alloys under gear oil and multiply alkylated cyclopentanes (MACs) lubrication condition have been studied. The equiaxed crystal structure of AlCoCrFeNi alloy is obtained after heat-treatment. The AlCoCrFeNiTi0.5 alloy keeps dendrite structure. Under the gear oil with good lubrication action, AlCoCrFeNiTi0.5 alloy preserves better tribological properties than AlCoCrFeNi alloy. The delamination and crack behaviors tend to occur in the grain boundary of AlCoCrFeNi alloy and along the interdendrite region of AlCoCrFeNiTi0.5 alloy. Under the MACs with relatively poor lubrication action, the applied load slightly influences the wear behavior of AlCoCrFeNi alloy, but seriously impacts the wear mechanism of AlCoCrFeNiTi0.5 alloy. Compared with AlCoCrFeNi alloy, AlCoCrFeNiTi0.5 alloy keeps better wear-resistance at low applied load of 100 N, but preserves less wear-resistance at high applied load of 200 N.

Tribological performances of two ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium tetrafluoroborate) as nanolubricants on polyether-ether-ketone surface

This paper seeks to address the potential of using ionic liquids as nanolubricants on Polyether-ether-ketone (PEEK) surface. We characterize the tribological properties of two ionic liquids, namely1-ethyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium tetrafluoroborate. The tribological data are compared with those of perfluoropolyether (PFPE) and Multiply Alkylated Cyclopentanes (MAC) data obtained from previous study. Ionic liquids at lower concentration of 0.4wt% (in solution prior to deposition) showed lower wear lives as compared to those for PFPE and MAC. However, at higher concentration of 4wt%, these ionic liquids have the same wear lives as those of PFPE and MAC, but show considerably lower coefficients of friction. Mechanisms of nanolubrication for ionic lubricants vis-a-vis those of PFPE and MAC are explained.

Erratum to: Lithium-based ionic liquids as novel lubricant additives for multiply alkylated cyclopentanes (MACs)

Zenghong SONG, Yongmin LIANG, Mingjin FAN, Feng ZHOU, Weimin LIU 1 State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China 2 University of Chinese Academy of Sciences, Beijing 100049, China Received: 11 April 2013 / Revised: 31 May 2013 / Accepted: 14 June 2013 © The author(s) 2014. This article is published with open access at Springerlink.com

Fabrication and Tribological Study of Graphene Oxide/Multiply-Alkylated Cyclopentanes Multilayer Lubrication Films on Si Substrates

Multilayer films based on graphene oxide (GO) and multiply-alkylated cyclopentanes (MACs) have been fabricated successfully on silicon substrate via both self-assembled and dip-coating technologies. Given the excellent mechanical properties and frictional properties of GO, the resulting multilayer films composed of GO and MACs with excellent lubricating property are expected to possess improved comprehensive tribological performances. In the current paper, the surface morphology and chemical composition of the films were analyzed using water contact angle meter, X-ray photoelectron spectroscope, and atomic force microscope. A ball-on-plate tribometer was used to evaluate the tribological performances of the films. The results showed that the new multilayer films exhibited excellent load-carrying capacity and durability. Therefore, they are hoped to find promising applications in the lubrication of microelectromechanical systems.

Lithium-based ionic liquids as novel lubricant additives for multiply alkylated cyclopentanes (MACs)

Abstract Two lithium-based ionic liquids (ILs, L-C3N3, and L-P3N3) were synthesized and evaluated as novel lubricant additives for multiply alkylated cyclopentanes (MACs). They were found to be approximately 1.0% soluble in MACs at room temperature (RT), whereas traditional ILs, such as 1-ethyl-3-methylimidazolium tetrafluoroborate (L-B102), 1-hexyl-3-methylimidazolium hexafluorophosphate (L-P106), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (L-F102), could not be dissolved in this base oil. Friction tests indicated that these ILs exhibit excellent friction-reducing and anti-wear properties both at RT and at 100 °C. They can improve the tribological properties of MACs at RT to a greater extent than the commonly used lubricant zinc dialkyldithiophosphate (T204), even at a concentration of 0.1%. The load ramp test showed that MACs with L-C3N3 and L-P3N3 also exhibit high load-carrying capabilities. Scanning electron microscope (SEM) and X-ray photoelectron spectrometer (XPS) results indicated that physical adsorption and complex tribochemical reactions occurred between the ILs and metal surfaces during the sliding process, thereby forming a surface protective film that significantly contributed to the excellent tribological properties of the new ILs.

Fabrication and tribological properties of a multiply-alkylated cyclopentane/reduced graphene oxide composite ultrathin film

A composite thin film composed of multiply-alkylated cyclopentane (MAC) and reduced graphene oxide (rGO) is prepared on a silicon substrate. The rGO sheets were covalently assembled onto a silicon surface by mutilayer deposition. Meanwhile, MAC was synthesized as a hydrocarbon lubricant. The chemical composition, structure and morphology of the film were characterized utilizing the measurement tool of Raman spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy and film thickness with ellipsometric method, and by the means of high resolution transmission electron microscopy and atomic force microscopic analysis. Results show that the MAC/rGO composite thin films possess good load-carrying capabilities, adhesion resistance and anti-wear performance. This strategy can be applied to many other surfaces, such as metals, glass and semiconductors, by simply changing rGO assembly.

Rolling Bearing Performance and Film Formation Behavior of Four Multiply Alkylated Cyclopentane (MAC) Base Greases for Space Applications

Four multiply alkylated cyclopentane (MAC)-based greases, used for space applications, were used for rolling contact fatigue tests employing thrust ball bearings. These greases were R2000, ML, MU, and 5200 and were made from the same base oil 2001A. Each grease had a different thickener, which were sodium soap, Li soap, urea, and polytetrafluoroethylene (PTFE), respectively. The effect of the grease thickener on the ball bearings' fatigue life in vacuum and atmospheric environments was investigated via testing. For the greases R2000, MU, and ML it was found that the oil film formation in the experiments performed under vacuum conditions declined remarkably in comparison to under atmospheric conditions. For the 5200 grease, the oil film formation was almost the same as under atmospheric conditions. These results were supported by the occurrence of cage wear in the ball bearing fatigue tests. In the absence of sufficient films, high wear rates were measured.

Effect of Surface Oxide Layer of Steel on the Tribological Characteristics of Load-bearing Additives for Multiply-Alkylated Cyclopentane Oil under High Vacuum

The tribological performance of two types of additives—alkylated phenyl phosphate and lead naphthenate—dissolved in multiply-alkylated cyclopentane was evaluated under a high vacuum using two types of ball-on-disk tribometers: a reciprocating motion tribometer under mild loading conditions and a unidirectional rotating motion tribometer under heavy loading conditions. A ball and a flat disk made of SUS440C stainless steel were used as specimens for both tribometers. The surface of the as-received flat disk specimen was covered with a thick (>40 nm) oxide layer. For the examination of the effect of the surface oxide layer on the tribological performance of the liquid lubricants under a high vacuum, another specimen with an oxide layer (approx. 4 nm thick) was prepared. The alkylated phenyl phosphate additive showed better lubrication performance with the specimen with the thicker oxide layer, but the lead naphthenate additive showed superior performance with the thinner oxide layer specimen. It is also shown that these opposite tribological characteristics are explained by the hard and soft acids and bases principle.

Wear durability study on self-lubricating SU-8 composites with perfluoropolyther, multiply-alkylated cyclopentane and base oil as the fillers

Though SU-8 has become a useful material for micro-fabrication of MEMS/NEMS components using the micro-fabrication route, its poor tribological properties limit its wider applications. From our previous study [1], it was observed that adding PFPE lubricant to SU-8 possibly promoted chemical reaction between the molecules and helped in the boundary lubrication enhancing the wear durability of SU-8 by more than four orders of magnitude. For further investigation, another two different lubricants, a base oil and a multiply-alkylated cyclopentane (MAC) oil, were also added to SU-8. Both lubricants are hydrocarbons, chemically inert and have no polar reactive terminal groups unlike PFPE which has –OH polar terminal groups. SU-8+PFPE composite exhibited higher wear life than all SU-8 composites at all wt% of the lubricant content. Proper dispersion and possible chemical bonding of PFPE molecules with SU-8 are responsible for the superior tribological properties of SU-8+PFPE composite when compared with other SU-8 composites.

A Tribological Study of Multiply-Alkylated Cyclopentanes and Perfluoropolyether Lubricants for Application to Si-MEMS Devices

Lubrication of Micro-Electro-Mechanical Systems (MEMS) is a major constraint in MEMS applications, restricting the designs and practical usages of such devices. Possible lubricants and methods have been investigated in this paper, comparing perfluoropolyether (PFPE) lubricant with multiply-alkylated cyclopentanes (MACs). The effectiveness of both the lubricants in reducing friction and enhancing the wear life was investigated in a new method of MEMS lubrication known as Localised-Lubrication or “Loc-Lub.” Friction and wear tests were conducted in a flat-on-flat test geometry under a normal load of 50 g and a sliding velocity of 5 mm s−1 in reciprocation, with Si as the substrate. Further tests were conducted at higher loads, to compare wear durability between lubricants and methods. It was found that MACs have a propensity to remain cohesive during the tests due to higher surface tension and provide better friction and wear properties when tested under reciprocating sliding conditions, as a complete film is present between the two surfaces. The results show that MAC lubricant is more effective in extending the wear life and reducing friction under the tested conditions compared to PFPE.

In situ preparation of anti-corrosion ionic liquids as the lubricant additives in multiply-alkylated cyclopentanes

Methoxy tris-ethoxy methylene benzotriazole (BTAG3) was synthesized and has good solubility in multiply-alkylated cyclopentanes (MACs) only when equal molar ratios of lithium salts, LiBF4, LiPF6, LiSO3CF3 or LiTFSI, were co-added into MACs due to the formation of ionic liquids (ILs), [Li(BTAG3)]BF4, [Li(BTAG3)]PF6, [Li(BTAG3)]SO3CF3 and [Li(BTAG3)]TFSI. The as-synthesized ILs have better solubilities in MACs than the conventional imidazolium ILs, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (L-F108) and 1-butyl-3-methylimidazolium tetrafluoroborate (L-B104) or the unfunctionalized lithium-based IL, [Li(G3)]TFSI, which are insoluble in MACs. They were evaluated as anti-wear and anti-corrosion additive of MACs for steel–steel contact at room temperature (RT). It was found that the ILs possessed excellent friction-reducing and anti-wear properties in MACs compared with zinc dialkyldithiophosphate. Besides, the presence of benzotriazole means that these synthetic ILs have good anti-corrosion properties compared with the conventional IL, L-B104.

Chemical Degradation of a Multiply Alkylated Cyclopentane (MAC) Oil During Wear: Implications for Spacecraft Attitude Control System Bearings

The wear-induced chemical degradation process was examined using deliberately under-lubricated thrust ball bearings to create wear in a reasonable time frame. The liquid-phase products were analyzed using infrared spectroscopy and gel-permeation chromatography. Our results indicate that oil molecules react with the freshly created clean Fe surface produced during wear, and fragment into radicals by breaking C–C bonds. These free radicals produce alkenes, which can then be further attacked by radicals, leading to the formation of larger molecules (oligomers and eventually polymers). A side reaction, production of iron carboxylate salts, also occurred during wear. Additional experiments indicate that organic acids can be produced by radical reaction with the oxidized areas of the bearing surfaces and wear particles, and these acids can then attack the clean Fe surfaces created by wear to form iron carboxylate salts. We used our experimental results to estimate the amount of degradation likely to be produced in attitude control system bearing tests under conditions that produce wear and poor performance. We find that multiply alkylated cyclopentane (MAC) oil chemical degradation is an effect of wear, and is insufficient to be a cause of failure itself. Life predictions for MAC-lubricated attitude control system bearings must be based on predictions of oil transport and wear since failures are due to the failure of the lubrication system, not of the lubricant itself.