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Articles 121 - 150 of 3492

Full-Text Articles in Engineering Science and Materials

Significant Friction Reduction Of High-Intensity Pulsed Ion Beam Irradiated Wc-Ni Against Graphite Under Water Lubrication, Gaolong Zhang, Yuechang Wang, Ying Liu, Xiangfeng Liu, Yuming Wang Oct 2020

Significant Friction Reduction Of High-Intensity Pulsed Ion Beam Irradiated Wc-Ni Against Graphite Under Water Lubrication, Gaolong Zhang, Yuechang Wang, Ying Liu, Xiangfeng Liu, Yuming Wang

Friction

Two types of commercial WC-Ni samples were irradiated with the High-intensity pulsed ion beam (HIPIB). Both the surface characteristics and tribo-characteristics of the non-irradiated and irradiated WC-Ni samples, sliding against graphite under water lubrication, were compared. Quite low steady friction coefficients (approximately of 0.02) of the irradiated WC-Ni were observed. The surface topographies and components were investigated. The quite low friction of the irradiated WC-Ni samples was ascribed to the higher fluid retention capability of the latter and the tribofilm formed during sliding.


Metal-Containing Nanomaterials As Lubricant Additives: State-Of-The-Art And Future Development, Igor E. Uflyand, Vladimir A. Zhinzhilo, Victoria E. Burlakova Oct 2020

Metal-Containing Nanomaterials As Lubricant Additives: State-Of-The-Art And Future Development, Igor E. Uflyand, Vladimir A. Zhinzhilo, Victoria E. Burlakova

Friction

This review focuses on the effect of metal-containing nanomaterials on tribological performance in oil lubrication. The basic data on nanolubricants based on nanoparticles of metals, metal oxides, metal sulfides, nanocomposities, and rare-earth compounds are generalized. The influence of nanoparticle size, morphology, surface functionalization, and concentration on friction and wear is analyzed. The lubrication mechanisms of nanolubricants are discussed. The problems and prospects for the development of metal-containing nanomaterials as lubricant additives are considered. The bibliography includes articles published during the last five years.


Metal-Containing Nanomaterials As Lubricant Additives: State-Of-The-Art And Future Development, Igor E. Uflyand, Vladimir A. Zhinzhilo, Victoria E. Burlakova Oct 2020

Metal-Containing Nanomaterials As Lubricant Additives: State-Of-The-Art And Future Development, Igor E. Uflyand, Vladimir A. Zhinzhilo, Victoria E. Burlakova

Friction

This review focuses on the effect of metal-containing nanomaterials on tribological performance in oil lubrication. The basic data on nanolubricants based on nanoparticles of metals, metal oxides, metal sulfides, nanocomposities, and rare-earth compounds are generalized. The influence of nanoparticle size, morphology, surface functionalization, and concentration on friction and wear is analyzed. The lubrication mechanisms of nanolubricants are discussed. The problems and prospects for the development of metal-containing nanomaterials as lubricant additives are considered. The bibliography includes articles published during the last five years.


Experimental Study On The Tribo-Chemical Smoothening Process Between Self-Mated Silicon Carbide In A Water-Lubricated Surface-Contact Reciprocating Test, Le Jin, Herbert Scheerer, Georg Andersohn, Matthias Oechsner, Dieter Hellmann Oct 2020

Experimental Study On The Tribo-Chemical Smoothening Process Between Self-Mated Silicon Carbide In A Water-Lubricated Surface-Contact Reciprocating Test, Le Jin, Herbert Scheerer, Georg Andersohn, Matthias Oechsner, Dieter Hellmann

Friction

Silicon carbide (SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment. As well reported in the point-contact tests, this smoothening process works well due to the abundant water as oxidant. After this smoothening process, the tribo-surface is well polished, a closely mated tribo-gap naturally forms, and an ultra-low friction state is built. However, water in the tribo-gap could be insufficient in industrial applications, e.g., the seal gap in mechanical seals. In this study, the tribo-chemical smoothening behavior in such environment was researched. A surface-contact reciprocating test was used to simulate the aqueous environment where ...


Experimental Study On The Tribo-Chemical Smoothening Process Between Self-Mated Silicon Carbide In A Water-Lubricated Surface-Contact Reciprocating Test, Le Jin, Herbert Scheerer, Georg Andersohn, Matthias Oechsner, Dieter Hellmann Oct 2020

Experimental Study On The Tribo-Chemical Smoothening Process Between Self-Mated Silicon Carbide In A Water-Lubricated Surface-Contact Reciprocating Test, Le Jin, Herbert Scheerer, Georg Andersohn, Matthias Oechsner, Dieter Hellmann

Friction

Silicon carbide (SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment. As well reported in the point-contact tests, this smoothening process works well due to the abundant water as oxidant. After this smoothening process, the tribo-surface is well polished, a closely mated tribo-gap naturally forms, and an ultra-low friction state is built. However, water in the tribo-gap could be insufficient in industrial applications, e.g., the seal gap in mechanical seals. In this study, the tribo-chemical smoothening behavior in such environment was researched. A surface-contact reciprocating test was used to simulate the aqueous environment where ...


Water-Based Superlubricity In Vacuum, Chen Xiao, Jinjin Li, Lei Chen, Chenhui Zhang, Ningning Zhou, Tao Qing, Linmao Qian, Jiyang Zhang, Jianbin Luo Oct 2020

Water-Based Superlubricity In Vacuum, Chen Xiao, Jinjin Li, Lei Chen, Chenhui Zhang, Ningning Zhou, Tao Qing, Linmao Qian, Jiyang Zhang, Jianbin Luo

Friction

This study achieved water-based superlubricity with the lubrication of H3PO4 solution in vacuum (highest vacuum degree <10-4 torr) for the first time by performing a pre-running process in air before running in vacuum. The stable water-based superlubricity was sustainable in vacuum (0.02 torr) for 14 h until the test was stopped by the user for non-experimental factor. A further analysis suggested that the superlubricity may be attributed to the phosphoric acid-water network formed in air, which can efficiently lock water molecules in the liquid lubricating film even in vacuum owing to the strong hydrogen bond interaction ...


Water-Based Superlubricity In Vacuum, Chen Xiao, Jinjin Li, Lei Chen, Chenhui Zhang, Ningning Zhou, Tao Qing, Linmao Qian, Jiyang Zhang, Jianbin Luo Oct 2020

Water-Based Superlubricity In Vacuum, Chen Xiao, Jinjin Li, Lei Chen, Chenhui Zhang, Ningning Zhou, Tao Qing, Linmao Qian, Jiyang Zhang, Jianbin Luo

Friction

This study achieved water-based superlubricity with the lubrication of H3PO4 solution in vacuum (highest vacuum degree <10-4 torr) for the first time by performing a pre-running process in air before running in vacuum. The stable water-based superlubricity was sustainable in vacuum (0.02 torr) for 14 h until the test was stopped by the user for non-experimental factor. A further analysis suggested that the superlubricity may be attributed to the phosphoric acid-water network formed in air, which can efficiently lock water molecules in the liquid lubricating film even in vacuum owing to the strong hydrogen bond interaction. Such capability to lock water is strongly affected by the strength of hydrogen bond and environmental conditions. The realization of water-based superlubricity with H3PO4 solution in vacuum can lead to its application in space environment.


Tribological Performance Of Novel Nickel-Based Composite Coatings With Lubricant Particles, Ignacio Tudela, Andrew J. Cobley, Yi Zhang Oct 2020

Tribological Performance Of Novel Nickel-Based Composite Coatings With Lubricant Particles, Ignacio Tudela, Andrew J. Cobley, Yi Zhang

Friction

The present study is focused on the evaluation of the tribological performance of novel Ni/hBN and Ni/WS2 composite coatings electrodeposited from an additive-free Watts bath with the assistance of ultrasound. Lubricated and non-lubricated scratch tests were performed on both novel composite coatings and on standard Ni deposits used as a benchmark coating to have an initial idea of the effect of the presence of particles within the Ni matrix. Under lubricated conditions, the performance of the Ni/hBN composite coating was very similar to the benchmark Ni coating, whereas the Ni/WS2 behaved quite differently, as ...


Tribological Performance Of Novel Nickel-Based Composite Coatings With Lubricant Particles, Ignacio Tudela, Andrew J. Cobley, Yi Zhang Oct 2020

Tribological Performance Of Novel Nickel-Based Composite Coatings With Lubricant Particles, Ignacio Tudela, Andrew J. Cobley, Yi Zhang

Friction

The present study is focused on the evaluation of the tribological performance of novel Ni/hBN and Ni/WS2 composite coatings electrodeposited from an additive-free Watts bath with the assistance of ultrasound. Lubricated and non-lubricated scratch tests were performed on both novel composite coatings and on standard Ni deposits used as a benchmark coating to have an initial idea of the effect of the presence of particles within the Ni matrix. Under lubricated conditions, the performance of the Ni/hBN composite coating was very similar to the benchmark Ni coating, whereas the Ni/WS2 behaved quite differently, as the latter ...


Influence Of Alumina/Mwcnt Hybrid Nanoparticle Additives On Tribological Properties Of Lubricants In Turning Operations, Anuj Kumar Sharma, Jitendra Kumar Katiyar, Shubrajit Bhaumik, Sandipan Roy Oct 2020

Influence Of Alumina/Mwcnt Hybrid Nanoparticle Additives On Tribological Properties Of Lubricants In Turning Operations, Anuj Kumar Sharma, Jitendra Kumar Katiyar, Shubrajit Bhaumik, Sandipan Roy

Friction

A hybrid lubricant with improved thermal and tribological properties was developed by blending multiwalled carbon nanotubes (MWCNTs) with alumina-based nanoparticles into cutting fluid at fixed volumetric proportions (10:90). The hybrid cutting fluid was prepared in different volumetric concentrations (0.25, 0.75, and 1.25 vol%), and the tribological properties and contact angles were measured using pin-on-disc tribometry and goniometry, respectively. The study showed a reduction in wear and friction coefficient with increasing nanoparticle concentration. The cutting fluid performance was investigated using minimum quantity lubrication (MQL) in the turning of AISI 304 stainless steel. Regression models were developed for ...


Numerical Analysis Of Time-Varying Wear With Elastic Deformation In Line Contact, Wanglong Zhan, Ping Huang Oct 2020

Numerical Analysis Of Time-Varying Wear With Elastic Deformation In Line Contact, Wanglong Zhan, Ping Huang

Friction

Wear is an important factor for failures of mechanical components. Current research on wear is mainly focused on experiments while the numerical simulation of wear is hardly used owing to the complexities of the wear process. Explaining the effect of friction on the wear process is important, as it will lead to a deeper understanding of the evolution of wear. This study proposed a numerical method to expound the wear process in the contact between an elastic cylinder and a half-space simulating the ring-block tester. There are two difficulties during the calculation; one is that the contact shapes vary with ...


Numerical Analysis Of Time-Varying Wear With Elastic Deformation In Line Contact, Wanglong Zhan, Ping Huang Oct 2020

Numerical Analysis Of Time-Varying Wear With Elastic Deformation In Line Contact, Wanglong Zhan, Ping Huang

Friction

Wear is an important factor for failures of mechanical components. Current research on wear is mainly focused on experiments while the numerical simulation of wear is hardly used owing to the complexities of the wear process. Explaining the effect of friction on the wear process is important, as it will lead to a deeper understanding of the evolution of wear. This study proposed a numerical method to expound the wear process in the contact between an elastic cylinder and a half-space simulating the ring-block tester. There are two difficulties during the calculation; one is that the contact shapes vary with ...


Tribology Of Wc Reinforced Sic Ceramics: Influence Of Counterbody, Sandan Kumar Sharma, B. Venkata Manoj Kumar, Young-Wook Kim Oct 2020

Tribology Of Wc Reinforced Sic Ceramics: Influence Of Counterbody, Sandan Kumar Sharma, B. Venkata Manoj Kumar, Young-Wook Kim

Friction

Hot pressed silicon carbide (SiC) composites prepared with 0, 10, 30 or 50 wt% tungsten carbide (WC) are subjected to dry sliding wear against WC-Co and steel ball. In particular an attempt has been made to answer the following important questions: (i) How does the load (from 5 to 20 N) effect sliding wear behaviour of SiC-ceramics against WC-Co and steel counterbodies? (ii) Is there any effect of WC content on friction and wear characteristics of SiC ceramics? (iii) Does the dominant material removal mechanism of SiC ceramics change with the addition of WC or counterbody? (iv) What is the ...


Fundamental Theories And Basic Principles Of Triboelectric Effect: A Review, Shuaihang Pan, Zhinan Zhang Oct 2020

Fundamental Theories And Basic Principles Of Triboelectric Effect: A Review, Shuaihang Pan, Zhinan Zhang

Friction

Long-term observation of the triboelectric effect has not only proved the feasibility of many novel and useful tribo-devices (e.g., triboelectric nanogenerators), but also constantly motivated the exploration of its mysterious nature. In the pursuit of a comprehensive understanding of how the triboelectric process works, a more accurate description of the triboelectric effect and its related parameters and factors is urgently required. This review critically goes through the fundamental theories and basic principles governing the triboelectric process. By investigating the difference between each charging media, the electron, ion, and material transfer is discussed and the theoretical deduction in the past ...


The Viscosity At The Glass Transition Of A Liquid Lubricant, Scott Bair Oct 2020

The Viscosity At The Glass Transition Of A Liquid Lubricant, Scott Bair

Friction

In the classical study of elastohydrodynamic lubrication (EHL) which does not employ real, measurable viscosity in analysis, the possibility of a glass transition has not been considered in many years. Indeed, the two rheological assumptions of classical EHL, the Newtonian inlet and the equivalence of a traction curve to a flow curve, would not have persisted so long had the pressure dependence of the viscosity been accurately stated. With the recent appearance of viscosity obtained from viscometers in EHL analysis, the possibility of a glass transition in the contact should be reexamined, especially for the fragile traction fluids. This article ...


Active Control Of Friction By Transverse Oscillations, J. Benad, K. Nakano, V. L. Popov, M. Popov Oct 2020

Active Control Of Friction By Transverse Oscillations, J. Benad, K. Nakano, V. L. Popov, M. Popov

Friction

The present paper is devoted to a theoretical analysis of sliding friction under the influence of in-plane oscillations perpendicular to the sliding direction. Contrary to previous studies of this mode of active control of friction, we consider the influence of the stiffness of the tribological contact in detail and show that the contact stiffness plays a central role for small oscillation amplitudes. In the present paper we consider the case of a displacement-controlled system, where the contact stiffness is small compared to the stiffness of the measuring system. It is shown that in this case the macroscopic coefficient of friction ...


Experimental Rigs For Testing Components Of Advanced Industrial Applications, Enrico Ciulli Oct 2020

Experimental Rigs For Testing Components Of Advanced Industrial Applications, Enrico Ciulli

Friction

This paper presents experimental rigs of the Research Centre for the Mechanics of Turbomachinery of the Department of Civil and Industrial Engineering of the University of Pisa. Most of them were designed and constructed to allow investigations of real machine components and to furnish more realistic results than basic tribological test rigs.Tilting pad journal bearings, as well as gears and complete gearboxes for advanced industrial applications, can be tested using the rigs described in the paper. A novel test rig with a power rating of approximately 1 MW allows investigations of the static and dynamic characteristics of high-performance tilting ...


Tribological Application And Mechanism Of Epicuticular Wax, Xuwen Zhong, Yanqiu Xia, Xin Feng Oct 2020

Tribological Application And Mechanism Of Epicuticular Wax, Xuwen Zhong, Yanqiu Xia, Xin Feng

Friction

The plant cuticle is a complex mixture of omnipresent, commonly monofunctional, fatty acid derivatives and taxon-specific, generally bifunctional, specialty compounds. This study explored expanded applications for these substances. Four types of plant cuticles were distilled from leaves and the resulting lipid mixtures were analyzed using gas chromatography-mass spectrometry. These were then used as additives for a synthetic ester lubricant. A reciprocating friction and wear testing machine was utilized to investigate the resulting tribological properties. The worn surfaces of the lower discs were observed and analyzed using optical microscopy and time-of-flight secondary ion mass spectrometry. The results reveal that cuticular waxes ...


Development Of A Novel Cycling Impact–Sliding Wear Rig To Investigate The Complex Friction Motion, Zhenbing Cai, Zhiqiang Chen, Yang Sun, Jianying Jin, Jinfang Peng, Minhao Zhu Oct 2020

Development Of A Novel Cycling Impact–Sliding Wear Rig To Investigate The Complex Friction Motion, Zhenbing Cai, Zhiqiang Chen, Yang Sun, Jianying Jin, Jinfang Peng, Minhao Zhu

Friction

In many industrial devices, impact-sliding wear is caused by a variety of complex vibrations between the contacted interfaces. Under actual conditions, impact and sliding motions do not occur in only one direction, and different complex impact-sliding motions exist on the tribology surfaces. In this study, an impact-sliding wear test rig is developed to investigate the wear effect of different complex motions. Using this rig, multi-type impact-sliding wear effects are realized and measured, such as those derived from unidirectional, reciprocating, and multi-mode combination motions. These three types of impact–sliding wear running behavior are tested and the wear damage mechanism is ...


Oil-Soluble Ionic Liquids As Antiwear And Extreme Pressure Additives In Poly-Α-Olefin For Steel/Steel Contacts, Guowei Huang, Qiangliang Yu, Zhengfeng Ma, Meirong Cai, Feng Zhou, Weimin Liu Oct 2020

Oil-Soluble Ionic Liquids As Antiwear And Extreme Pressure Additives In Poly-Α-Olefin For Steel/Steel Contacts, Guowei Huang, Qiangliang Yu, Zhengfeng Ma, Meirong Cai, Feng Zhou, Weimin Liu

Friction

To enhance the lubricating and extreme pressure (EP) performance of base oils, two types of oil-soluble ionic liquids (ILs) with similar anion albeit dissimilar cations were synthesized. The physical properties of the prepared ILs were measured. The anticorrosion properties of ILs were assessed by conducting corrosion tests on steel discs and copper strips, which revealed the remarkable anticorrosion properties of the ILs in comparison with those of the commercial additive zinc dialkyldithiophosphate (ZDDP). The tribological properties of the two ILs as additives for poly-α-olefin-10 (PAO10) with various mass concentrations were investigated. The tribological test results indicate that these ILs as ...


Advances In Nonequilibrium Molecular Dynamics Simulations Of Lubricants And Additives, J. P. Ewen, D. M. Heyes, D. Dini Oct 2020

Advances In Nonequilibrium Molecular Dynamics Simulations Of Lubricants And Additives, J. P. Ewen, D. M. Heyes, D. Dini

Friction

Nonequilibrium molecular dynamics (NEMD) simulations have provided unique insights into the nanoscale behaviour of lubricants under shear. This review discusses the early history of NEMD and its progression from a tool to corroborate theories of the liquid state, to an instrument that can directly evaluate important fluid properties, towards a potential design tool in tribology. The key methodological advances which have allowed this evolution are also highlighted. This is followed by a summary of bulk and confined NEMD simulations of liquid lubricants and lubricant additives, as they have progressed from simple atomic fluids to ever more complex, realistic molecules. The ...


Evaluation Of Lubrication Performance Of Crank Pin Bearing In A Marine Diesel Engine, Suk Man Moon, Yong Joo Cho, Tae Wan Kim Oct 2020

Evaluation Of Lubrication Performance Of Crank Pin Bearing In A Marine Diesel Engine, Suk Man Moon, Yong Joo Cho, Tae Wan Kim

Friction

In this study, the lubrication performance of the crank pin bearing in a marine two–stroke diesel engine is evaluated to investigate the adhesional failure on the crank pin bearing. A numerical algorithm for the lubrication analysis considering motion analysis of the crank pin system is developed. The film pressure and thickness for three clearances and three lubricant temperatures are calculated. The results show that the lubricant temperature has a higher effect on film thickness than clearance. In terms of the film parameter, the operating condition that can result in solid–solid contact is investigated. We also suggest the desirable ...


Friction And Wear Of Sand-Contaminated Lubricated Sliding, Mohamed Ahmed Ramadan Oct 2020

Friction And Wear Of Sand-Contaminated Lubricated Sliding, Mohamed Ahmed Ramadan

Friction

This paper reports a test investigation of friction and wear responses from sand contaminated lubricated sliding. The influence of sand contaminants on wear and friction is characterized. Analyses are completed utilizing segments of piston ring sliding against the cylinder liner. Paraffin oil, with and without sand contaminants, is utilized. The effects of the concentration and particle size of sand are examined.Based on the observations in the present work, we found that friction and wear increase with sand concentration in the lube. Solid proposals ought to be considered, in order to enlighten the general population on the importance of changing ...


Numerical Modeling And Analysis Of Plasmonic Flying Head For Rotary Near-Field Lithography Technology, Yueqiang Hu, Yonggang Meng Oct 2020

Numerical Modeling And Analysis Of Plasmonic Flying Head For Rotary Near-Field Lithography Technology, Yueqiang Hu, Yonggang Meng

Friction

Rotary near-field lithography (RNFL) technology provides a route to overcome the diffraction limit with a high throughput and low cost for nanomanufacturing. Utilizing the advantage of the passive flying of a plasmonic head, RNFL can achieve a 10 m/s processing speed with a perfect near-field condition at dozens of nanometers. The flying performance of the plasmonic flying head (PFH) is the pivotal issue in the system. The linewidth has a strong correlation with the near-field gap, and the manufacturing uniformity is directly influenced by the dynamic performance. A more serious issue is that the unexpected contact between the PFH ...


Insight Into Tribological Problems Of Green Ship And Corresponding Research Progresses, Yuwei Sun, Xinping Yan, Chengqing Yuan, Xiuqin Bai Oct 2020

Insight Into Tribological Problems Of Green Ship And Corresponding Research Progresses, Yuwei Sun, Xinping Yan, Chengqing Yuan, Xiuqin Bai

Friction

The so-called “green ship” is being regarded as a potential solution to the problems that the shipping industry faces, such as energy conservation and environmental protection. Some new features, such as integrated renewable energy application, biomimetic materials, and antifriction and wear resistant coating have been accepted as the typical characteristics of a green ship, but the tribology problems involved in these domains have not been precisely redefined yet. Further, the related research work is generally focused on the technology or material itself, but not on the integration of the applicable object or green ship, marine environment, and tribological systematical analysis ...


Study On Frictional Behavior Of Carbon Nanotube Thin Films With Respect To Surface Condition, Youn-Hoo Hwang, Byung-Soo Myung, Hyun-Joon Kim Oct 2020

Study On Frictional Behavior Of Carbon Nanotube Thin Films With Respect To Surface Condition, Youn-Hoo Hwang, Byung-Soo Myung, Hyun-Joon Kim

Friction

In this work, tribological characteristics of thin films composed of entangled carbon nanotubes (CNTs) were investigated. The surface roughness of CNT thin films fabricated via a dip-coating process was controlled by squeezing during the process with an applied normal force ranging from 0 to 5 kgf. Raman spectra and scanning electron microscopy (SEM) images of the thin films were obtained to estimate the influence of the squeezing process on the crystallinity of the CNTs. The analysis revealed that squeezing could reduce surface roughness, while preserving the crystallinity of the CNTs. Moreover, the surface energy of the cover glass used to ...


Analysis Of The Coated And Textured Ring/Liner Conjunction Based On A Thermal Mixed Lubrication Model, Chunxing Gu, Xianghui Meng, Di Zhang Oct 2020

Analysis Of The Coated And Textured Ring/Liner Conjunction Based On A Thermal Mixed Lubrication Model, Chunxing Gu, Xianghui Meng, Di Zhang

Friction

For the ring/liner conjunction, well-designed surface texturing has been regarded as a potential means to improve its tribological performance, as well as the application of coating. However, so far most researchers focused on the one of these aspects. In this study, the combined effect of coating and texturing on the performance of ring/liner conjunction is numerically investigated. A thermal mixed lubrication model is presented. The effects of the coating’s thermal and mechanical properties on the tribological performance are studied under the cold and warm engine operating conditions. Along with the increasing coating thickness, the effects of the ...


Contribution Of Friction And Adhesion To The Reliable Attachment Of A Gecko To Smooth Inclines, Zhouyi Wang, Qiang Xing, Wenbo Wang, Aihong Ji, Zhendong Dai Oct 2020

Contribution Of Friction And Adhesion To The Reliable Attachment Of A Gecko To Smooth Inclines, Zhouyi Wang, Qiang Xing, Wenbo Wang, Aihong Ji, Zhendong Dai

Friction

Geckos’ ability to move on steep surfaces depends on their excellent adhesive structure, timely adjustments on locomotor behaviors, and elaborates control on reaction forces. However, it is still unclear how they can generate a sufficient driving force that is necessary for locomotion, while ensuring reliable adhesion on steep inclines. We measured the forces acting on each foot and recorded the contact states between feet and substrates when geckos encountered smooth inclination challenges ranging from 0° to 180°. The critical angles of the resultant force vectors of the front and hind-feet increased with respect to the incline angles. When the incline ...


Friction Characteristics Of Mechanically Exfoliated And Cvd- Grown Single-Layer Mos2, Dinh Le Cao Ky, Bien-Cuong Tran Khac, Chinh Tam Le, Yong Soo Kim, Koo-Hyun Chung Oct 2020

Friction Characteristics Of Mechanically Exfoliated And Cvd- Grown Single-Layer Mos2, Dinh Le Cao Ky, Bien-Cuong Tran Khac, Chinh Tam Le, Yong Soo Kim, Koo-Hyun Chung

Friction

In this work, the friction characteristics of single-layer MoS2 prepared with chemical vapor deposition (CVD) at three different temperatures were quantitatively investigated and compared to those of single-layer MoS2 prepared using mechanical exfoliation. The surface and crystalline qualities of the MoS2 specimens were characterized using an optical microscope, atomic force microscope (AFM), and Raman spectroscopy. The surfaces of the MoS2 specimens were generally flat and smooth. However, the Raman data showed that the crystalline qualities of CVD-grown single-layer MoS2 at 800 °C and 850 °C were relatively similar to those of mechanically exfoliated MoS2 ...


Effect Of Arc-Current And Spray Distance On Elastic Modulus And Fracture Toughness Of Plasma-Sprayed Chromium Oxide Coatings, Simanchal Kar, Partha Pratim Bandyopadhyay, Soumitra Paul Oct 2020

Effect Of Arc-Current And Spray Distance On Elastic Modulus And Fracture Toughness Of Plasma-Sprayed Chromium Oxide Coatings, Simanchal Kar, Partha Pratim Bandyopadhyay, Soumitra Paul

Friction

In this experimental study, chromium oxide powder was sprayed on a low-carbon steel substrate using the atmospheric plasma spray process. The current and standoff distances (SODs) were varied to study their effect on the fracture toughness of the coatings. Theoretically, as the arc current increases, the melting of the ceramic oxide should increase and this in turn should lead to the formation of a dense coating. However, it was observed that if the arc power is too high and because the particle size of the powder is small (approximately 30 µm), the particles tend to fly away from the plasma ...