Analysis of Tribological Behavior of Carbon Nanotube Based Industrial Mineral Gear Oil 250 cSt Viscosity (original) (raw)
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The aim of the paper is to investigate the effect of size of multiwalled carbon nanotubes (MWCNTs) as additives for dispersion in gear oil to improve the tribological properties. Since long pristine MWCNTs tend to form clusters compromising dispersion stability, they are mildly processed in a ball mill to shorten the length and stabilized with a surfactant before dispersing in lubricant. Investigations are made to assess the effect of ball milling on the size and structure of MWCNTs using electron microscopy and Raman spectroscopy. The long and shortened MWCNTs are dispersed in EP 140 gear oil in 0.5% weight. The stability of the dispersed multiwalled carbon nanotubes is evaluated using light scattering techniques. The antiwear, antifriction, and extreme pressure properties of test oils are evaluated on a four-ball wear tester. It is found that ball milling of MWCNTs has a strong effect on the stability and tribological properties of the lubricant. From Raman spectroscopy, it is found that ball milling time of up to 10 hours did not produce any defects on the surface of MWCNTs. The stability of the lubricant and the antiwear, antifriction, and extreme pressure properties have improved significantly with dispersion shortened MWCNTs. Ball milling for longer periods produces defects on the surface of MWCNTs reducing their advantage as oil additives.
The working conditions in many industrial applications cause the tribo pair to operate in the mixed lubrication regime. Since the lubricant film thickness under these conditions is insufficient to separate the sliding tribo pair, therefore usage of lubricant with anti-wear additives is essential. The carbon nano-tubes (CNT) have recently emerged as lubricant additive having extraordinary tribological properties. In the present work, experiments have been conducted on block and disk test setup to determine the effect of using CNT as anti-wear additive in a commercial lubricant. Varying quantities of the CNT have been tried in the lubricant to conduct the wear tests. The wear of the block is quantified in terms of its weight loss after the test. The results of the wear tests are reported.
Journal of Materials Research and Technology, 2016
Since their discovery in 1991 carbon nanotubes (CNTs) have attracted much interest due to their remarkable mechanical, thermal, electrical, chemical and optical properties. In connection with their mechanical properties, CNTs have been studied in various forms for tribological applications including their use as lubricant additives for oil and water. In this work, the tribological properties of functionalized nanotubes (single and multi-walled) modified with carboxylic acid when used as lubricant additives at different concentrations (0.01, 0.05%) were studied under rolling-sliding conditions in a twin-disk testing machine. The tests were performed using 5% of creepage and pressures of 0.8 GPa and 1.1 GPa. The results indicated that the presence of carbon nanotubes leads to a decrease in both friction coefficient and wear rate for both systems studied (oil and water).
International Journal of Surface Science and Engineering
In the present study, the tribological performance of water-based emulsion (lubricant) was investigated by blending carbon fillers such as graphene nanoplatelets and multiwall carbon nanotubes using pin-on-disc tribometer. It was noticed that addition of GnP and MWCNT in water-based emulsion (conventional lubricant) increases the thermal conductivity and viscosity as compared to conventional lubricants. The nanolubricants were supplied with minimum quantity lubrication (MQL) technique at a constant flow rate and pressure in the sliding zone. The addition of 0.8 wt.% concentration of GnP showed 58.39% reduction in coefficient of friction and 61.80% reduction in wear depth compared to the conventional lubricant. Similarly, for 0.8 wt.% concentration of MWCNT showed 26.27% reduction in coefficient of friction and 47.35% reduction in wear depth compared to the conventional lubricant. The sliding surface micrographs were also investigated to explain the synergistic effect of nanoparticles.
Carbon nanotubes (CNTs) are used as a nanoadditive due to their unique properties and for improving the lubricant's properties. In this research, the effect of CNTs in different concentrations (0.1, 0.5, 1 and 2 wt%) on kinematic viscosity, pour point, flash point and thermal conductivity coefficient as four quality parameters which are effective in the functionality of oil is evaluated and compared against the standard Mobil gear 627 and paraffinic mineral oils. The samples were tested according to ASTM D-445, ASTM D-97 and ASTM D-92 standards, respectively. The results indicated that the thermal conductivity , flash point, pour point and kinematic viscosity of nanolubricants with low concentration of CNTs improved with respect to the base oil. Dispersion of CNTs as additive has improved the lubricant properties and operational characteristics of Mobil gear 627 and paraffinic mineral oils.
Preparation and evaluation of lubricating greases based on carbon nanotube.pdf
The paper aims to preparing nano grease based on Multiwall carbon nanotube (MWCNTs) as additives. In this respect, the rheological and tribological properties of prepared nano greases with different of carbon nanotube content were studied. The microstructure of prepared carbon nanotube and nanao-greases were examined by high resolution transmission electron microscope (HR-TEM). The rheological properties of these greases with and without carbon nanotube-particles were explored at different temperatures using a brokfield rheometer. The experimental results reveal that improvement in the thermal and mechanical stabilities in addition to improvement in the oil separation. Also, the apparent viscosity increases with the increase of carbon nanotube concentration. The rheological characteristics of the obtained greases fitted with Herschel-Bulkley mathematical model. Tribological properties of the prepared greases with and without carbon nano-tube were evaluated using Pin-on-Disc tribometer. It was concluded that the prepared nano-greases have been proved to have quite favorable lubricating performance by the tribology experiments compared with blank grease.
Tribological properties of dispersed carbon nanotubes in lubricant
This study examined the tribological properties of two lubricating oils, mobil gear 627 and paraffinic mineral oils, with multiwall carbon nanotubes (MWCNTs) nanoparticles used as additives with various concentrations (0.1, 0.5, 1, and 2 wt. %). The friction and wear experiments were performed using a four ball tribotester. The samples were tested for their antiwear, load carrying capacity and friction coefficients according to ASTM D-2783, ASTM D-2596 and ASTM D-5183 standards. The experimental results show that the addition of MWCNTs to base oils exhibit good friction-reduction and anti-wear properties. The wear test results show a decreased wear by 68 % and 39 % in the case of MWCNTs based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. Furthermore, the friction reduction results show a decrease of friction about 57 % and 49 % in the case of MWCNTs based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. The weld load of the base oil containing 1 % MWCNTs was found to be 400 kgf and 125 kgf as compared with base mobil gear 627 and paraffinic mineral oils, respectively Downloaded by [University of Nebraska, Lincoln] at 19:57 28 May 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 which got welded at 200 kgf and 100 kgf. The morphologies and typical element distribution of the worn surfaces were characterized by SEM and EDX. The SEM micrographs and EDX chemical analysis confirm the formation of atribolayer composed of the elements from the nanoparticles.
Tribological behaviour of calcium grease containing carbon nanotubes additives
Purpose – The purpose of this paper is to fabricate composite nanogrease for tribological applications. Multi-walled carbon nanotubes (MWCNTs) with a size 10 nm average diameter and 5 m in length were used as additives to calcium grease. Design/methodology/approach – The tribological four-ball machine was used to evaluate calcium grease with carbon nanotubes (CNTs) as an additive. The interaction between CNT and calcium grease (nanogrease) were studied by transmission electron microscopy and X-ray diffraction. Findings – MWCNTs composite nanogrease was manufactured for tribological applications. The effectiveness of the fabricated grease in improving the tribological performance at different concentrations and under different loads was tested. The results are summarized as follows. CNT nanoparticle additive dispersed in calcium grease significantly improve its anti-wear performance, reducing friction, increasing load-carrying capacity and extreme pressure (EP) property. The friction is reduced by about 50 per cent, the wear scar diameter (WSD) decreased to 32 per cent and the EP properties increases about 38 per cent, with only 3 wt.%. The modified grease with CNTs additives of 3 wt.% showed the most favorable results. Energy dispersive x-ray (EDX) analysis shows that C was present on the worn scar surface, with atomic concentration of about 22 per cent. The presence of C suggests that a lubricating film is likely formed because of the presence of CNTs and very likely prevented the steel-to-steel direct contact. Originality/value – The results indicated that a 3 wt.% of MWCNT nanogrease is an excellent antiwear, with EP and low friction coefficient. It was also found that the friction coefficient was reduced to about 50 per cent, the WSD decreased by about 32 per cent and the EP properties increased about 38 per cent. The mating surfaces were investigated with scanning electron microscopy and EDX. The results show that a boundary film mainly composed of CNTs, Cr and Fe was formed on the rubbed surfaces.
Tribological behaviour of calcium grease containing carbon nanotubes additives.pdf
Purpose -The purpose of this paper is to fabricate composite nanogrease for tribological applications. Multi-walled carbon nanotubes (MWCNTs) with a size 10 nm average diameter and 5 m in length were used as additives to calcium grease. Design/methodology/approach -The tribological four-ball machine was used to evaluate calcium grease with carbon nanotubes (CNTs) as an additive. The interaction between CNT and calcium grease (nanogrease) were studied by transmission electron microscopy and X-ray diffraction. Findings -MWCNTs composite nanogrease was manufactured for tribological applications. The effectiveness of the fabricated grease in improving the tribological performance at different concentrations and under different loads was tested. The results are summarized as follows. CNT nanoparticle additive dispersed in calcium grease significantly improve its anti-wear performance, reducing friction, increasing load-carrying capacity and extreme pressure (EP) property. The friction is reduced by about 50 per cent, the wear scar diameter (WSD) decreased to 32 per cent and the EP properties increases about 38 per cent, with only 3 wt.%. The modified grease with CNTs additives of 3 wt.% showed the most favorable results. Energy dispersive x-ray (EDX) analysis shows that C was present on the worn scar surface, with atomic concentration of about 22 per cent. The presence of C suggests that a lubricating film is likely formed because of the presence of CNTs and very likely prevented the steel-to-steel direct contact. Originality/value -The results indicated that a 3 wt.% of MWCNT nanogrease is an excellent antiwear, with EP and low friction coefficient. It was also found that the friction coefficient was reduced to about 50 per cent, the WSD decreased by about 32 per cent and the EP properties increased about 38 per cent. The mating surfaces were investigated with scanning electron microscopy and EDX. The results show that a boundary film mainly composed of CNTs, Cr and Fe was formed on the rubbed surfaces.