Grease thixotropy: evaluation of grease microstructure change due to shear and relaxation

2014 ◽  
Vol 66 (2) ◽  
pp. 223-237 ◽  
Author(s):  
Maciej Paszkowski ◽  
Sylwia Olsztyńska-Janus
Keyword(s):  
Qualitative Assessment ◽  
Structural Components ◽  
Lubricating Grease ◽  
Content Type ◽  
Base Oil ◽  
Force Microscopy ◽  
Atomic Force ◽  
Physicochemical Interactions ◽  
Lithium Soap ◽  
Mineral Base

Purpose – The thixotropy of lubricating grease thickened with lithium 12-hydroxystearate with mineral base oil was investigated. The thixotropy has a significant influence on the flow resistance and pressure drop in the structural components of lubrication systems, which is of major importance as today the latter are being centralized and automated. The paper aims to discuss these issues. Design/methodology/approach – Rheometer studies on thixotropy were carried out and the grease microstructure was visualized using atomic force microscopy (AFM). Total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used to study the physicochemical interactions which indicate the disintegration and recovery of the grease microstructure. Findings – A qualitative assessment of the physicochemical interactions between lithium soap floccules was made and a theory of the self-ordering effect of lithium 12-hydroxystearate associated molecules during shearing and their aggregation and flocculation during relaxation has been proposed. Originality/value – Because of the complexity of the disintegration and recovery of the lubricating grease thickener microstructure, there is still limited physical understanding of the mechanism of this process. Therefore, the present research was undertaken to identify the phenomena involved.

Corrosion inhibition behavior of four benzimidazole derivatives and benzotriazole on copper surface

2020 ◽  
Vol 67 (6) ◽  
pp. 565-574
Author(s):  
Lin Liu ◽  
Shuang Lu ◽  
Ya Qi Wu ◽  
Jin Yin Xie ◽  
Jinjuan Xing
Keyword(s):  
Electrochemical Measurement ◽  
Copper Surface ◽  
Molar Ratio ◽  
Benzimidazole Derivatives ◽  
Content Type ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Atomic Force ◽  
Mixture Concentration ◽  
Contact Angle Measurements

Purpose This paper aims to reduce environment pollution caused by benzotriazole. The authors chose one of the best inhibitors from 2-aminobenzimidazole, 2-methylbenzimidazol, 2-mercaptobenzimidazole and benzimidazole in combination with benzotriazole. Design/methodology/approach The electrochemical measurement indicated that 2-methylbenzimidazol had the best inhibition behavior. Then, it was mixed with benzotriazole. Techniques such as field emission scanning electron microscopy, atomic force microscopy, Raman spectroscopy and optical contact angle measurements were used. Findings The results showed that the inhibition efficiency was up to 99.98%, when the mixture concentration was 20 mmol/L and the molar ratio 1:1. Originality/value 1-benzotriazole was mixed with 2-methylbenzimidazol for the first time. During the exist of methyl, 2-methylbenzimidazol has the better inhibition; this point was ignored by researchers. Graphical abstract

Preparation and tribological properties of attapulgite – bentonite clay base grease

2014 ◽  
Vol 66 (4) ◽  
pp. 538-544 ◽  
Author(s):  
Tiedan Chen ◽  
Yanqiu Xia ◽  
Zhilu Liu ◽  
Zeyun Wang
Keyword(s):  
Tribological Properties ◽  
Bentonite Clay ◽  
Solid Particles ◽  
Lubricating Grease ◽  
Content Type ◽  
Base Oil ◽  
Dropping Point ◽  
Attapulgite Clay ◽  
Surface Modified ◽  
Base Grease

Purpose – The mixture of attapulgite and bentonite was used as a thickener, and polyalphaolefin was used as the base oil to prepare the new lubricating grease. Some solid particles such as Polytetrafluoroethene (PTFE), MoS2, nano-calcium carbonate and graphite were added in the new lubricating grease as anti-wear additives to investigate the tribological sensitivity. Design/methodology/approach – The new lubricating grease was evaluated by optimol-SRV reciprocating friction and wear tester, and the wear volumes were determined using a MicroXAM-3D. At the same time, the dropping point and the cone penetration were investigated and analyzed. The tribological properties of the new lubricating grease and the sensitivity of some solid lubricating additives to the new lubricating base grease were investigated; pure organic-bentonite and pure organic-attapulgite base grease were used as contrast. Findings – The new lubricating grease based on the surface-modified bentonite/attapulgite clay base grease was synthesized with a relatively high dropping point, and the mass ratio is 25/75 bentonite/attapulgite clay base grease, having a better tribological performance. MoS2 was used as an anti-wear additive that has good tribological sensitivity to the new lubricating base grease. Originality/value – The main innovative thought of this work lies in the mixture of attapulgite and bentonite used as thickener. A relevant report is not available at present.

Studies on ZDDP Anti-Wear Films Formed Under the Different Conditions by XANES Spectroscopy, Atomic Force Microscopy and 31P NMR

2007 ◽  
Author(s):  
Yue-Rong Li ◽  
Gavin Pereira ◽  
Masoud Kasrai ◽  
Peter R. Norton
Keyword(s):  
Atomic Force Microscopy ◽  
31P Nmr ◽  
Xanes Spectroscopy ◽  
Edge Structure ◽  
Base Oil ◽  
Force Microscopy ◽  
Atomic Force ◽  
Variable Chemical ◽  
Different Temperatures ◽  
X Ray Absorption

Antiwear (AW) films, generated from a mineral base oil containing zinc dialkyl dithiophosphate (ZDDP) additive, were extensively studied. These films were formed at various conditions such as different temperatures, various loads and rubbing times. The surface morphology of these films was investigated using atomic force microscopy (AFM) and the surface roughness of these films has been calculated from the images. X-ray absorption near edge structure (XANES) spectroscopy has been used to characterize the chemistry of these films. The intensity of phosphorus K-edge was also used to monitor the thickness of these films. Phosphorus L-edge spectra show that these films have slightly variable chemical natures. 31P Nuclear magnetic resonance (31P NMR) was used to study the ZDDP components in the residue oils. The spectra show that the primary and secondary ZDDP decompose quite differently at the various conditions. Tribological characteristics of these AW films were probed by measuring the coefficients of friction and the wear scar width of the counter faces.

Developing an electrochemical immunosensor for early diagnosis of hepatocellular carcinoma

Sensor Review ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abdulrahman Al-Shami ◽  
Rami Joseph Oweis ◽  
Mohamed Ghazi Al-Fandi
Keyword(s):  
Hepatocellular Carcinoma ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Electrochemical Immunosensor ◽  
Content Type ◽  
Force Microscopy ◽  
Promising Tool ◽  
Atomic Force ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Purpose This paper aims to report on the development of a novel electrochemical amperometric immunosensor to diagnose early hepatocellular carcinoma (HCC) by detecting the Midkine (MDK) biomarker. Design/methodology/approach Anti-Midkine antibodies were immobilized covalently through carbodiimides chemistry on carbon screen-printed electrodes modified with carboxylated multi-walled carbon nanotubes. The development process was characterized using cyclic voltammetry, electrochemical impedimetric spectroscopy, Fourier transform infrared spectroscopy and atomic force microscopy. Differential pulse voltammetry was used to investigate the immunosensor performance in detecting MDK antigen within the concentration range of 1 pg/ml to 100 ng/ml. Findings MDK immunosensor exhibited high sensitivity and linearity with a detection limit of 0.8 pg/ml and a correlation coefficient of 0.99. The biosensor also demonstrated high selectivity, stability and reproducibility. Originality/value The developed MDK immunosensor could be a promising tool to diagnose HCC and reduce the number of related deaths.

The effect of particle size on the dispersion and wear protection ability of MoS2 particles in polyalphaolefin and trimethylolpropane ester

2017 ◽  
Vol 232 (8) ◽  
pp. 987-998 ◽  
Author(s):  
M Gulzar ◽  
Khalid Mahmood ◽  
Rehan Zahid ◽  
Abdullah Alabdulkarem ◽  
HH Masjuki ◽  
...  
Keyword(s):  
Particle Size ◽  
Sliding Wear ◽  
Base Oil ◽  
Force Microscopy ◽  
Wear Protection ◽  
Atomic Force ◽  
Nominal Size ◽  
Load Carrying ◽  
Effect Of Particle Size ◽  
20 Nm

The effect of particle size and surfactant on dispersion stability and wear protection ability was experimentally evaluated for polyalphaolefin (PAO 10) and bio-based base oil (palm trimethylolpropane ester) added with molybdenum disulfide (MoS2) particles. Nanolubricants were developed by adding 1 wt% of MoS2 particles that varied in size. In addition to the variation in particle size, an anionic surfactant was also used to analyze its interaction with both types of nanoparticles for stable suspensions and for the related effects on the antiwear characteristics. The wear protection characteristics of the formulations were evaluated by four-ball extreme pressure tests and piston ring on cylinder sliding wear tests. The wear surfaces were analyzed by scanning electron microscopy along with an energy-dispersive X-ray and an atomic force microscopy. The MoS2 nanoparticles with a nominal size of 20 nm exhibited a better load-carrying capacity, while better sliding wear protection was provided by nanoparticles with a nominal size of 50 nm.

scholarly journals Study of the side gate junctionless transistor in accumulation region

2016 ◽  
Vol 33 (2) ◽  
pp. 61-67 ◽  
Author(s):  
Arash Dehzangi ◽  
Farhad Larki ◽  
Sawal Hamid Md Ali ◽  
Sabar Derita Hutagalung ◽  
Md Shabiul Islam ◽  
...  
Keyword(s):  
Electric Field ◽  
Drain Current ◽  
Silicon On Insulator ◽  
Valence Band Edge ◽  
Content Type ◽  
Force Microscopy ◽  
Atomic Force ◽  
Simulation Results ◽  
Accumulation Region ◽  
Tcad Sentaurus

Purpose The purpose of this paper is to analyse the operation of p-type side gate junctionless silicon transistor (SGJLT) in accumulation region through experimental measurements and 3-D TCAD simulation results. The variation of electric field components, carrier’s concentration and valence band edge energy towards the accumulation region is explored with the aim of finding the origin of SGJLT performance in the accumulation operational condition. Design/methodology/approach The device is fabricated by atomic force microscopy nanolithography on silicon-on-insulator wafer. The output and transfer characteristics of the device are obtained using 3-D Technology Computer Aided Design (TCAD) Sentaurus software and compared with experimental measurement results. The advantages of AFM nanolithography in contact mode and Silicon on Insulator (SOI) technology were implemented to fabricate a simple structure which exhibits the behaviour of field effect transistors. The device has 200-nm channel length, 100-nm gate gap and 4 μm for the distance between the source and drain contacts. The characteristics of the fabricated device were measured using an Agilent HP4156C semiconductor parameter analyzer (SPA). A 3-D TCAD Sentaurus tool is used as the simulation platform. The Boltzmann statistics is adopted because of the low doping concentration of the channel. Hydrodynamic model is taken to be as the main transport model for all simulations, and the quantum mechanical effects are ignored. A doping dependent Masetti mobility model was also included as well as an electric field dependent model with Shockley–Read–Hall (SRH) carrier recombination/generation. Findings We have obtained that the device is a normally on state device mainly because of the lack of work functional difference between the gate and the channel. Analysis of electric field components’ variation, carrier’s concentration and valence band edge energy reveals that increasing the negative gate voltage drives the device into accumulation region; however, it is unable to increase the drain current significantly. The positive slope of the hole quasi-Fermi level in the accumulation region presents mechanism of carriers’ movement from source to drain. The influence of electric field because of drain and gate voltage on charge distribution explains a low increasing of the drain current when the device operates in accumulation regime. Originality/value The proposed side gate junctionless transistors simplify the fabrication process, because of the lack of gate oxide and physical junctions, and implement the atomic force microscopy nanolithography for fabrication process. The optimized structure with lower gap between gate and channel and narrower channel would present the output characteristics near the ideal transistors for next generation of scaled-down devices in both accumulation and depletion region. The presented findings are verified through experimental measurements and simulation results.

Adhesive properties of S.S to PU and PVC leathers

2014 ◽  
Vol 26 (2) ◽  
pp. 108-117 ◽  
Author(s):  
Shouxiang Jiang ◽  
Dagang Miao ◽  
Diandong Zhao
Keyword(s):  
Electron Microscopy ◽  
Weight Loss ◽  
Bonding Strength ◽  
Design Methodology ◽  
Adhesive Properties ◽  
Content Type ◽  
Force Microscopy ◽  
Atomic Force ◽  
Scanning Electron ◽  
Better Than

Purpose – The purpose of this paper is to investigate the interfacial nanostructures and the adhesions of the stainless steel (S.S) coating to the polyurethane (PU) and polyvinyl chloride (PVC) leathers. Design/methodology/approach – PU leather and PVC leather deposit S.S nano-films on the surface of PU and PVC leathers in this study. The interfacial nanostructures were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The experimental results revealed that the surface roughness of the substrates had extremely important influence on the morphology of nano-films. The adhesions of the S.S coating to the PU and PVC leathers were investigated by the peel-off test. Findings – The results showed that the adhesive performance of the S.S nano-films coating on PVC leather was better than that on the substrate of PU leather. Moreover, a weight loss of per peeling force calculating formulation is proposed to determine the bonding strength between the S.S films and the substrates. Originality/value – In this paper, influence of different substrates on surface morphology of S.S coating was studied by SEM and AFM. Moreover, the weight loss of per peeling force calculating formulation was used to discuss the bonding strength between the S.S coating and the substrates. The research methods presented in this paper are of innovation significance to a certain extent.

Bearing torque characteristics of lithium soap greases with some synthetic base oils

2012 ◽  
Vol 226 (6) ◽  
pp. 575-583 ◽  
Author(s):  
Eri Oikawa ◽  
Noriyuki Inami ◽  
Michita Hokao ◽  
Atsushi Yokouchi ◽  
Joichi Sugimura
Keyword(s):  
Yield Stress ◽  
Ball Bearing ◽  
Test Apparatus ◽  
Lower Yield ◽  
Lower Yield Stress ◽  
Force Microscopy ◽  
Base Oils ◽  
Atomic Force ◽  
Deep Groove ◽  
Lithium Soap

This article describes the influence of rheological properties on the bearing torque characteristics of the lithium soap greases with five types of base oils. The greases used had different yield stress depending on the base oils even with the same thickener concentration. Measurement of bearing torque was conducted for a deep-groove radial ball bearing by using a bearing test apparatus. The bearings filled with greases initially exhibited high torque but showed gradual decrease in the torque with prolonged rotation, where the greases with higher yield stress showed larger normalized torque decrease. Observation of bearing after the rotation revealed a tendency that the greases with larger normalized torque decrease had been pushed aside in the raceway by channeling. This implied that the greases with higher yield stress tended to show channeling. On the other hand, the greases with lower yield stress circulated within the bearing by churning and showed smaller normalized torque decrease. These behaviors were explained in terms of the yield stress of the greases and the shear stress to entrain the greases into the contacts. Observation of grease structure was made with atomic force microscopy showed that the greases whose thickener network structure was distributed more densely had higher yield stress.

scholarly journals Quantifying the Importance of Galactofuranose in Aspergillus nidulans Hyphal Wall Surface Organization by Atomic Force Microscopy

2011 ◽  
Vol 10 (5) ◽  
pp. 646-653 ◽  
Author(s):  
Biplab C. Paul ◽  
Amira M. El-Ganiny ◽  
Mariam Abbas ◽  
Susan G. W. Kaminskyj ◽  
Tanya E. S. Dahms
Keyword(s):  
Atomic Force Microscopy ◽  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Wall Surface ◽  
Wild Type ◽  
Content Type ◽  
Force Microscopy ◽  
Double Deletion ◽  
Atomic Force ◽  
Viscoelastic Modulus

ABSTRACTThe fungal wall mediates cell-environment interactions. Galactofuranose (Galf), the five-member ring form of galactose, has a relatively low abundance inAspergilluswalls yet is important for fungal growth and fitness.Aspergillus nidulansstrains deleted for Galfbiosynthesis enzymes UgeA (UDP-glucose-4-epimerase) and UgmA (UDP-galactopyranose mutase) lacked immunolocalizable Galf, had growth and sporulation defects, and had abnormal wall architecture. We used atomic force microscopy and force spectroscopy to image and quantify cell wall viscoelasticity and surface adhesion ofugeAΔ andugmAΔ strains. We compared the results forugeAΔ andugmAΔ strains with the results for a wild-type strain (AAE1) and theugeBdeletion strain, which has wild-type growth and sporulation. Our results suggest that UgeA and UgmA are important for cell wall surface subunit organization and wall viscoelasticity. TheugeAΔ andugmAΔ strains had significantly larger surface subunits and lower cell wall viscoelastic moduli than those of AAE1 orugeBΔ hyphae. Double deletion strains (ugeAΔugeBΔ andugeAΔugmAΔ) had more-disorganized surface subunits than single deletion strains. Changes in wall surface structure correlated with changes in its viscoelastic modulus for both fixed and living hyphae. Wild-type walls had the largest viscoelastic modulus, while the walls of the double deletion strains had the smallest. TheugmAΔ strain and particularly theugeAΔugmAΔ double deletion strain were more adhesive to hydrophilic surfaces than the wild type, consistent with changes in wall viscoelasticity and surface organization. We propose that Galfis necessary for full maturation ofA. nidulanswalls during hyphal extension.

The role of drug as corrosion inhibitor for mild steel surface characterization by SEM, AFM, and FTIR

2016 ◽  
Vol 63 (4) ◽  
pp. 308-315 ◽  
Author(s):  
Md. Zaved Hossain Khan ◽  
Md. Abdul Aziz ◽  
Md. Rafiul Hasan ◽  
Md. Rashid Al-Mamun
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mild Steel ◽  
Steel Surface ◽  
Content Type ◽  
Mild Steel Surface ◽  
Force Microscopy ◽  
Corrosion Rates ◽  
Atomic Force ◽  
Scanning Electron

Purpose The purpose of this study is to understand the inhibitor behavior of specific drug against mild steel corrosion and their adsorption mechanism on the surface. Design/methodology/approach Corrosion rates are influenced by the formation of inhibitor aggregates at the mild steel surface. Detail surface characterizations of mild steel have been studied before and after adsorption of drugs in 1N HCl solution. Scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy were used to examine the effect of drug adsorption on steel surface. Findings Scanning electron microscopy analysis suggested that the metal had been protected from aggressive corrosion because of the addition of the inhibitors. Atomic force microscopy visualization confirmed the formation of protective layer on steel surface, resulting in the decrease in surface roughness with corrosion rates. The nature of metal surface has been analyzed by Fourier transform infrared spectroscopy. Originality/value The findings of this study will help us to understand the interaction of specific drugs with mild steel surface and their potential inhibition mechanism.

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