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Evaluation of biodiesel carbon soot particles as lubricant additives in soybean oil
Published in Binoy K. Saikia, Advances in Applied Chemistry and Industrial Catalysis, 2022
Hongzhi Luo, Chuan Li, Zhilin Fang, Lei Cheng, Xiaoju Chen, Xuanxuan Wang, Qiaoen He, Jiale Fu, Qiuting Zhao, Qing Qiao, Xue Liang
Figure 7 presents Raman mapping of the worn scars on the disks lubricated with diverse oil samples. When BCSPs were introduced to the soybean oil, the Raman signals of D peak and G peak of worn scars were considerably improved and the distribution area was enlarged, according to Raman maps and spectra on the disk scars. This is due to the formation of more carbon tribofilm forming on the worn surface during friction, which protects the contact surfaces of friction pairs. The corresponding tribological mechanisms are presented below, based on the aforementioned characteristics and analysis. Soybean oil with BCSPs contains spherical particles that have rolling impacts on rubbing surfaces and are better at improving lubrication performance than soybean without BCSPs (Zhao et al. 2021). Furthermore, BCSPs could be absorbed on the worn surface during the friction process and participate in the tribofilm. The tribofilm played a crucial role in minimizing friction and preventing wear.
CNTS as New Emerging Lubricant Additives for Enhancing Energy Efficiency
Published in Ann Rose Abraham, Soney C. George, A. K. Haghi, Carbon Nanotubes, 2023
Avinash V. Borgaonkar, Shital B. Potdar
The developed tribofilms on the contacting surfaces govern tribological behaviors of the contacting surfaces. This development of the film is initialized due to chemical reaction between the substrate material, base oil, and the additives under the set operating conditions.46 The formation of a durable tribofilm with addition of Mo, S, and P elements reduces the friction, wear, and seizure for MoS2 nanoparticles dispersed lubricant.35,58Figure 7.4 illustrates the tribofilm development, which protects the surfaces from crack propagation by reducing friction between the contacting asperities.
Formation of Tribofilms from Surfactants with Different Degrees of Ethoxylation on Steel Surfaces in the Boundary Lubrication Regime
Published in Girma Biresaw, K.L. Mittal, Surfactants in Tribology, 2017
F. Quintero, J.M. González, J. de Vicente Álvarez, J.E. Arellano, S. Rosales, Girma Biresaw, K.L. Mittal
The lubrication regimes for surfactant mixture A with xanthan and glycerin viscosity modifiers were found to be boundary and boundary dry, respectively (Table 9.8). The tribological performance of these mixtures depends on its ability to form tribofilm with suitable tribological properties between the contact surfaces. The effectiveness of this layer or bilayer on the tribopair depends on the shear resistance capacity (continuous or oscillatory) and the reordering ability of the surfactant molecules at the interface [47–49].
Tribological and Lubrication Performances of Nano-WO3 and CaWO4 Contained in Water-Based Fluid for Steel Strip during Hot Forming
Published in Tribology Transactions, 2022
It is considered that the nanoparticles can enter the contact area of the friction pair and form a protective tribofilm during the friction process. The formation of a tribofilm is mainly due to the physical deposition and tribochemical reaction at the friction interface. The tribological properties of molybdenum diselenide (MoSe2) nanoparticles as lubricant additives were studied using a spherical disc tribometer (11). Molybdenum (Mo) and selenium (Se) elements were found on the friction surface, indicating that nanoparticles formed a tribofilm. Roy et al. (12) studied the wear behavior of copper oxide (CuO) and tungsten carbide (WC) nanofluids under boundary lubrication in a rolling contact fatigue test. CuO exhibited better resistance to micropitting and wear by filling the cracks, and WC formed a tribofilm to protect the metal surface. Shaonan et al. (8) reported that GO-TiO2 nanoparticles were synthesized and used as water-based lubricant additives for cold-rolled steel. A tribofilm with a thickness of about 28 nm was obtained by calculation and surface chemical analysis. However, there are few studies on the application of nanofluids in metalworking, such as thermal deformation. The mechanism of hot rolling lubrication, especially the formation and structure of the friction film, need further study. In addition, pure metal materials are generally more chemically active than metallic compounds (9, 12).
An overall review on the tribological, thermal and rheological properties of nanolubricants
Published in Tribology - Materials, Surfaces & Interfaces, 2021
Wani Khalid Shafi, M. S. Charoo
Silver is another softer metallic nanoparticles widely used in nanolubricants. Silver nanoparticles increase the tribological properties either by forming a tribofilm or by getting pressed on the tribopairs, thereby, introducing a smoother layer on the friction pairs, which gets sheared easily. Prabu et al. [106] introduced surface modified silver nanoparticles in mineral oil and studied its effect on the extreme pressure and anti-wear properties for cutting fluid applications. Silver nanoparticles are surface modified with CTAB (Cetyl Trimethyl Ammonium bromide) and are 10–20 nm in size. It is observed that the load wear index of oil increase with increase in the concentration of nanoparticles. Minimum wear scar diameter is observed at 2 wt.% silver concentrations with load wear index equal to 744.9 N. The addition of silver nanoparticles decreases the wear scar diameter by 13% and is attributed to the protective film formation on the tribosurfaces. Kumar et al. [67] studied the properties of Polyalphaolefin oil mixed with surface modified silver nanoparticles. Three different samples of silver nanoparticles are synthesized where two samples are surface modified by 4-(tert-butyl)benzylthiol, and are denoted as NP-TBBT-1 (1–3 nm) and NP-TBBT-2 (4–5 nm). Third silver sample (NP-C12) is modified with dodecanethiol and is 3–6 nm in size. The NP-TBBT-2 and NP-C12 brings maximum improvement in frictional coefficient and wear by 35% and 85% respectively in boundary lubricating conditions. The reduction in the friction and wear is attributed to the tribofilm formation of thickness 50–100 nm.
Tribological Improvement Using Ionic Liquids as Additives in Synthetic and Bio-Based Lubricants for Steel–Steel Contacts
Published in Tribology Transactions, 2020
A. Z. Syahir, N. W. M. Zulkifli, H. H. Masjuki, M. A. Kalam, M. H. Harith, M. N. A. M. Yusoff, Z. M. Zulfattah, M. Jamshaid
Bio-based lubricants contain triglyceride molecules, which means that they have a higher polarity than mineral oils. Higher polarity means that they have a higher affinity to metallic surfaces (Prado, et al. (4)). Due to this special property, vegetable oils and their derivatives show superior tribological performance and therefore are suitable for lubrication applications. Oils containing polar groups such as esters and carboxylic acids have a greater tendency to adsorb and react with metallic surfaces, resulting in boundary lubrication effects (Schmidt, et al. (5)). It is well known that a lubricating film or tribofilm with strong surface attraction and enough cohesive interaction among lubricant molecules can effectively reduce friction and wear on interacting surfaces. Such a tribofilm must be able to withstand severe variations in temperature and shear degradation and sustain boundary-lubricating properties during operation in order to maintain low friction and wear. However, the physicochemical properties and lubrication performance of bio-based materials are affected by their free fatty acid composition (Syahir, et al. (3); Silitonga, et al. (6)).