scholarly journals Effect of Dispersant Concentration With Friction Modifiers and Anti-Wear Additives on the Tribofilm Composition and Boundary Friction

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
J. Umer ◽  
N. J. Morris ◽  
R. Rahmani ◽  
H. Rahnejat ◽  
S. Howell-Smith ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Cylinder Liner ◽  
Boundary Friction ◽  
Friction Modifiers ◽  
X Ray ◽  
Engine Oils ◽  
Low Viscosity ◽  
Reduced Viscosity ◽  
New Generation

Abstract To extend drain intervals and improve efficiency, new engine oils with increased dispersant concentration and reduced viscosity are required. Low viscosity engine oils can increase the prevalence of boundary friction at low temperature and increase its severity at higher temperatures. As a result, combinations of organic and inorganic friction modifiers (FM) will be used to reduce boundary friction across a range of temperatures, also preventing damage to vehicle catalysts. This paper presents an experimental case study of such a new generation of fully formulated engine lubricants with varying concentrations of polyisobutylene succinimide dispersant, organic, and inorganic FM. Representative conditions pertaining to those encountered at the top dead center reversal of the piston compression ring-cylinder liner contact are created, and the generated friction measured through use of a sliding-strip tribometry. Subsequently, X-ray photoelectron spectroscopy (XPS) is used to determine the composition of the formed surface tribofilms in order to explain the observed frictional characteristics. The key interactions and frictional behavior of the dispersant and friction modifiers are highlighted across a range of operating temperatures.

scholarly journals Synthesis of Heart/Dumbbell-Like CuO Functional Nanostructures for the Development of Uric Acid Biosensor

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1378 ◽  
Author(s):  
Zafar Ibupoto ◽  
Aneela Tahira ◽  
Hamid Raza ◽  
Gulzar Ali ◽  
Aftab Khand ◽  
...  
Keyword(s):  
Uric Acid ◽  
Photoelectron Spectroscopy ◽  
Lithium Ion ◽  
Nanostructured Material ◽  
Soft Template ◽  
X Ray ◽  
Growth Method ◽  
Enzyme Molecules ◽  
New Generation ◽  
Uric Acid Biosensor

It is always demanded to prepare a nanostructured material with prominent functional properties for the development of a new generation of devices. This study is focused on the synthesis of heart/dumbbell-like CuO nanostructures using a low-temperature aqueous chemical growth method with vitamin B12 as a soft template and growth directing agent. CuO nanostructures are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. CuO nanostructures are heart/dumbbell like in shape, exhibit high crystalline quality as demonstrated by XRD, and have no impurity as confirmed by XPS. Apparently, CuO material seems to be porous in structure, which can easily carry large amount of enzyme molecules, thus enhanced performance is shown for the determination of uric acid. The working linear range of the biosensor is 0.001 mM to 10 mM with a detection limit of 0.0005 mM and a sensitivity of 61.88 mV/decade. The presented uric acid biosensor is highly stable, repeatable, and reproducible. The analytical practicality of the proposed uric acid biosensor is also monitored. The fabrication methodology is inexpensive, simple, and scalable, which ensures the capitalization of the developed uric acid biosensor for commercialization. Also, CuO material can be used for various applications such as solar cells, lithium ion batteries, and supercapacitors.

scholarly journals Outstanding Nobility Observed in Cu5 Clusters Reveals the Key Role of Collective Quantum Effects

2021 ◽  
Author(s):  
David Buceta ◽  
Shahana Huseyinova ◽  
Miguel Cuerva ◽  
Héctor Lozano ◽  
Lisandro J. Giovanetti ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Metal Clusters ◽  
Bulk Material ◽  
Chemical Properties ◽  
Quantum Effects ◽  
High Concentration ◽  
X Ray ◽  
Potential Applications ◽  
New Generation

Subnanometer-sized metal clusters often feature a molecule-like electronic structure, which makes their physical and chemical properties significantly different from those of nanoparticles and bulk material. Considering potential applications, there is a major concern about their thermal stability and susceptibility towards oxidation. Cu clusters of only 5 atoms (Cu<sub>5</sub> clusters) are first synthesized in high concentration using a new-generation wet chemical method. Next, it is shown that, contrary to what is currently assumed, Cu<sub>5</sub> clusters display nobility, beyond resistance to irreversible oxidation, at a broad range of temperatures and oxygen pressures. The outstanding nobility arises from an unusual reversible oxidation which is observed by <i>in situ</i> X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy on Cu<sub>5</sub> clusters deposited onto highly oriented pyrolitic graphite at different oxygen pressures and up to 773 K. This atypical property is explained by a theoretical approach combining different state-of-the-art first principles theories. It reveals the essential role of collective quantum effects in the physical mechanism responsible for the nobility of Cu<sub>5</sub> clusters, encompassing a structural ‘breathing’ through concerted Cu–Cu elongations/contractions upon O<sub>2</sub> uptake/release, and collective charge transfer as well. A predictive phase diagram of their reversible oxidation states is also delivered, agreeing with the experimental observations. The collective quantum effects responsible of the observed nobility are expected to be general in subnanometer-sized metal clusters, pushing this new generation of materials to an upper level.

Characterizing Materials for Energy Generation Using X-ray Photoelectron Spectroscopy (XPS)

2011 ◽  
Vol 19 (2) ◽  
pp. 22-28 ◽  
Author(s):  
Tim Nunney ◽  
Richard White
Keyword(s):  
Photoelectron Spectroscopy ◽  
Energy Production ◽  
Thin Film Solar Cells ◽  
Materials Characterization ◽  
Environmentally Benign ◽  
Complex Materials ◽  
Initial Development ◽  
X Ray ◽  
Compositional Homogeneity ◽  
New Generation

In order to meet the challenges of more economical and environmentally benign energy production, a new generation of complex materials and devices are being developed, including thin film solar cells, fuel cells, and batteries. In all stages of development there is a requirement for materials characterization and analysis, from the initial development stages through to testing of the finished product. Most materials need to be analyzed for compositional homogeneity across surfaces and also for confirmation of film thickness and layer chemistry.

scholarly journals Biofunctionalisation of Gallium Arsenide with Neutravidin

2021 ◽  
Author(s):  
Barbara Santos Gomes ◽  
David Morgan ◽  
Wolfgang Langbein ◽  
Paola Borri ◽  
Francesco Masia
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Photoelectron Spectroscopy ◽  
Specific Binding ◽  
Gaas Surface ◽  
Biomolecular Recognition ◽  
Surface Characterisation ◽  
X Ray ◽  
High Affinity ◽  
Surface Functionalisation ◽  
New Generation

<div>We report a study presenting a physicochemical surface characterisation of the GaAs surface along the functionalisation with a high-affinity bioconjugation pair widely explored in the life</div><div>sciences: biotin and neutravidin. Combined X-ray photoelectron spectroscopy (XPS), wettability measurements and spectroscopic ellipsometry were used for a reliable characterisation of the surface functionalisation process. The results suggest that a film with a thickness lower than 10nm was formed, with a neutravidin to biotin ratio of 1:25 on the GaAs surface. Reduction of non-specific binding of the protein to the surface was achieved by optimising the protein buffer and rinsing steps. This study shows the feasibility of using GaAs as a platform for specific biomolecular recognition, paving the way to a new generation of optoelectronic biosensors.</div>

Effect of engine oil additives reduction on the tribofilm structure of a cylinder liner model surface

2019 ◽  
Vol 72 (4) ◽  
pp. 515-523
Author(s):  
Maria de Lourdes Miranda-Medina ◽  
Christian Tomastik ◽  
Tia Truglas ◽  
Heiko Groiss ◽  
Martin Jech
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Cylinder Liner ◽  
Engine Oil ◽  
Antiwear Additives ◽  
Content Type ◽  
X Ray ◽  
Underlying Mechanisms

Purpose The purpose of this paper is to provide a general picture for describing the formed tribofilm, including chemical and physical aspects in the micro-scale and the nano-scale. In a previous study, the durability of zinc dialkyl dithiophosphate (ZDDP) tribofilms on cylinder liner samples has been investigated in a tribometer model system by using fresh and aged fully formulated oils and replacing them with PAO8 without additives. Analyses of the derived tribofilms by means of X-ray photoelectron spectroscopy and scanning electron microscopy could give some hints about the underlying mechanisms of the tribofilm build-up and wear performance, but a final model has not been achieved. Design/methodology/approach Thus, characterisation of these tribofilms by means of focused ion beam-transmission electron microscopy (FIB-TEM) and energy dispersive X-ray spectroscopy is presented and a concluding model of the underlying mechanisms of tribofilm build-up is discussed in this paper. Findings For tribotests running first with fresh fully formulated engine oil, a rather homogeneous ZDDP-like tribofilm is found underneath a carbon rich tribofilm after changing to non-additivated PAO8. However, when the tests run first with aged fully formulated engine oil, no ZDDP-like tribofilm has been found after changing to non-additivated PAO8, but a wear protective carbon rich tribofilm. Originality/value The obtained results provide insights into the structure and durability of tribofilms. Carbon-based tribofilms are built up on the basis of non-additivated PAO8 because of the previously present ZDDP tribofilms, which suggests an alternative way to reducing the consumption of antiwear additives.

Tribological Properties of New Developed Nano Boric Acid Suspended as Additive in Engine Oil

2019 ◽  
Vol 823 ◽  
pp. 41-52
Author(s):  
Hakan Kaleli̇ ◽  
Selman Demi̇rtaş ◽  
Veli Uysal ◽  
Zulhicce Tanriseven
Keyword(s):  
Boric Acid ◽  
Photoelectron Spectroscopy ◽  
Friction And Wear ◽  
Piston Ring ◽  
Cylinder Liner ◽  
Engine Oil ◽  
Lubricating Oil ◽  
Chemical Compositions ◽  
X Ray ◽  
Liner System

It is well known that nanoparticles affect the interaction between lubricants and surfaces with various chemical compositions and different chemical and physical properties. In recent years, nanoparticles have started to play more important roles as lubricant additives for their potential in wear, friction and emission reduction and improving lubrication and fuel economy. Although nanolubricants are frequently used for friction tests, little is known about stability and degree of dispersion of these nanoparticles in viscous liquids. Most of them are unstable, agglomerate or aggregate which sediment over time. Boric acid (H3BO3) has always been a very important material due to its broad range of applications such as in medicine, cosmetics, automotive industry, metallurgy and also for miscellaneous purposes in other areas. Literature survey showed that friction between automobile engine parts could be greatly reduced using microscopic particles of boric acid.This study involves the new invention of successful suspension of nano boric acid (BA) additive added into 5W-40 fully synthetic commercial lubricating oil. This invention is confidential and realized by Murat ÖZAYMAN from Tribor ARGE Co. in Teknopark of YILDIZ Technical University in Istanbul-TURKEY. The particle size of BA is determined with (Transmission Electron Microscopy) (TEM). Backscattering and transmittance profiles proved that nano boric acid (BA) particles were in suspension in commercial engine oil. Suspended BA in engine oil is applied between piston ring and cylinder liner system in order to investigate their effect on friction and wear under boundary lubricated conditions. Simulation and measurement of friction and wear were conducted using a reciprocating tribometer. Surface analysis were performed using 3D digital optical microscope, Field Emission Scanning Electron Microscope (FESEM)/X-Ray, X-ray photoelectron spectroscopy (XPS) and Atomic Force Microscopy (AFM). Boron (B) from BA is well detected, mixed with other elements of additives and protected the surface under boundary lubrication conditions. The results indicate that BA can considerably improve the tribological performance of a piston ring and cylinder liner system under lubricated conditions. It has found that the friction coefficient is reduced with nano boric acid (BA) suspended engine oil and protected the surface mostly on cylinder liner mixing with other additives.

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