Tribological Studies Of Thick Polytetrafluoroethylene Coatings Enhanced By Polydopamine And Nanoparticles, 2021 University of Arkansas, Fayetteville
Tribological Studies Of Thick Polytetrafluoroethylene Coatings Enhanced By Polydopamine And Nanoparticles, Sujan Kumar Ghosh
Graduate Theses and Dissertations
Polytetrafluoroethylene (PTFE) is a popular low friction solid lubricant with high chemical and thermal stability. Thick PTFE coatings have the potential for many tribological applications, such as replacing Tin-based Babbitt materials in journal bearings. However, the weak bonding strength to the substrate and the high wear rate of PTFE coatings are current limiting factors. The lack of understanding of their tribological properties and wear mechanisms in oil-lubricated conditions and how coating thickness affects the tribological performance further hindered the use of PTFE coatings. In this dissertation, polydopamine (PDA), a bio-inspired adhesive, is used as an underlayer for or as a ...
Design Of High Stability Superhydrophobic Surfaces, 2021 University of Windsor
Design Of High Stability Superhydrophobic Surfaces, Shuo Wang
In the recent two decades, superhydrophobic surfaces' properties and their potential applications have attracted much attention. With the main advantages of self-cleaning, anti-icing, and drag-reduction, the superhydrophobic surfaces can be applied to many industry fields. But the traditional fabrication methods developed in the last twenty years for the superhydrophobic surfaces were focusing on mimicking nature. Specifically, most of the fabrication methods were based on the micro, and nano-scale structure of plants and animals, which came with the problems that such weeny structure on the surfaces would be damaged easily in the practical application without the self-healing capability like the creatures ...
Thermomechanical Mechanisms That Cause Adhesion Of Aluminum High Pressure Die Castings To The Die, 2021 Michigan Technological University
Thermomechanical Mechanisms That Cause Adhesion Of Aluminum High Pressure Die Castings To The Die, Alex Monroe
Dissertations, Master's Theses and Master's Reports
In high pressure die casting (HPDC) of aluminum, cast material adhering to die is a significant defect. Adhesion occurs in two primary ways. The casting may stick preventing its removal from the die. Aluminum can also adhere to the die and buildup in local areas on the die surface with additional casting cycles. This second form of adhesion is called soldering. Lubricant is the best technology to control all forms of adhesion, but it comes at the cost of casting porosity, blisters, reduced die life, and increased die casting machine wear. New strategies to prevent adhesion are desired to eliminate ...
Pulse Reverse Current Electrodeposited Tio2 Doped Ni-W Coating, 2021 The University of Akron
Pulse Reverse Current Electrodeposited Tio2 Doped Ni-W Coating, Sydney Hughes
Williams Honors College, Honors Research Projects
Nickel-Tungsten (Ni-W) coatings via the pulse reverse current method have been under development as a potential replacement for typical Chromium/Cadmium coatings. To increase the effectiveness of Ni-W as a coating, dopants have been tested to decrease microcracks and pores and increase overall tribological performance. Previous research by Timken Engineered Surfaces Laboratory showed that Ni-W doped with TiO2 nanoparticles had a positive effect on coating performance. The purpose of this study was to determine the ideal solution parameters (i.e. TiO2 concentration, pH) to maximize the benefit of the dopant when samples are subjected to tribological testing. Here ...
One-Dimensional Lateral Force Anisotropy At The Atomic Scale In Sliding Single Molecules On A Surface, 2021 Old Dominion University
One-Dimensional Lateral Force Anisotropy At The Atomic Scale In Sliding Single Molecules On A Surface, Yuan Zhang, Daniel J. Trainer, Badri Narayanan, Yang Li, Anh T. Ngo, Sushila Khadka, Arnab Neogi, Brandon Fisher, Larry A. Curtiss, Subramanian K.R.S. Sankaranarayanan, Saw Wai Hla
Physics Faculty Publications
Using a q+ atomic force microscopy at low temperature, a sexiphenyl molecule is slid across an atomically flat Ag(111) surface along the direction parallel to its molecular axis and sideways to the axis. Despite identical contact area and underlying surface geometry, the lateral force required to move the molecule in the direction parallel to its molecular axis is found to be about half of that required to move it sideways. The origin of the lateral force anisotropy observed here is traced to the one-dimensional shape of the molecule, which is further confirmed by molecular dynamics simulations. We also demonstrate ...
Viscoelasticity Of Ptfe-Based Face Seals, 2021 University of Kentucky
Viscoelasticity Of Ptfe-Based Face Seals, Bo Tan
Theses and Dissertations--Mechanical Engineering
PTFE-based materials are widely used in areas of tribology, particularly in seal and bearing applications because of their outstanding self-lubricating properties. Often in dynamic seal applications there is a need for ultra-low mechanical friction loss between the sealing surfaces. Due to its extremely low friction coefficient, there is interest in employing Polytetrafluoroethylene (PTFE) materials in such applications. One challenging aspect of employing PTFE is that these materials are viscoelastic and plastic. This dissertation concentrates on the modeling of viscoelastic material response when used as mechanical face seals with a focus on PTFE-based materials. First, the viscoelastic characteristics are measured through ...
A Bibliometric Analysis Of Ultrasonic Vibration Assisted Turning, 2021 MIT School of Engineering, MIT ADT University
A Bibliometric Analysis Of Ultrasonic Vibration Assisted Turning, Govind S. Ghule, Sudarshan Sanap Prof. Dr.
Library Philosophy and Practice (e-journal)
Ultrasonic vibration-assisted turning (UVAT) is a new crossover in machining techniques which uses high frequency, low amplitude sound waves which are further superimposed on the cutting tool in traditional turning. This innovative technology is being utilized over the decades due to its conspicuous influence contrasted with traditional approach particularly in turning of hard-to-machine materials. This present paper analyses the past explores in the arena of ultrasonic vibration-assisted turning, by a far-reaching bibliometric investigation. The analysis is carried out by scrutinizing the studies through Science Direct and Scopus database to select the peer-reviewed papers. The advanced research tools like the word ...
Transformation Between Polar And Rectangular Coordinates Of Stiffness And Dampness Parameters In Hydrodynamic Journal Bearings, 2020 School of Mechanical Engineering, Hubei University of Arts and Science, Xiangyang 441053, China
Transformation Between Polar And Rectangular Coordinates Of Stiffness And Dampness Parameters In Hydrodynamic Journal Bearings, Zhuxin Tian, Yu Huang
The stiffness and dampness parameters of journal bearings are required in rectangular coordinates for analyzing the stability boundary and threshold speed of oil film bearings. On solving the Reynolds equation, the oil film force is always obtained in polar coordinates; thus, the stiffness and dampness parameters can be easily obtained in polar coordinates. Therefore, the transformation between the polar and rectangular coordinates of journal bearing stiffness and dampness parameters is discussed in this study.
A Finite Element Analysis (Fea) Approach To Simulate The Coefficient Of Friction Of A Brake System Starting From Material Friction Characterization, 2020 Brembo S.p.A., Stezzano (BG), Stezzano (BG) 24040, Italy
A Finite Element Analysis (Fea) Approach To Simulate The Coefficient Of Friction Of A Brake System Starting From Material Friction Characterization, Gabriele Riva, Francesco Varriale, Jens Wahlström
The coefficient of friction (COF) is one of the most important parameters to evaluate the performance of a brake system. To design proper brake systems, it is important to know the COF when estimating the brake force and resulting torque. It is challenging to simulate the COF since friction in disc brakes is a complex phenomenon that depends on several parameters such as sliding velocity, contact pressure, materials, and temperatures, etc. There is a lack of studies found in the literature focusing on simulation of the COF for a full brake system based on tribometer material characterization. The aim of ...
Grease Film Evolution In Rolling Elastohydrodynamic Lubrication Contacts, 2020 School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266250, China
Grease Film Evolution In Rolling Elastohydrodynamic Lubrication Contacts, Xinming Li, Feng Guo, Gerhard Poll, Yang Fei, Ping Yang
Although most rolling element bearings are grease lubricated, the underlying mechanisms of grease lubrication has not been fully explored. This study investigates grease film evolution with glass disc revolutions in rolling elastohydrodynamic lubrication (EHL) contacts. The evolution patterns of the grease films were highly related to the speed ranges and grease structures. The transference of thickener lumps, film thickness decay induced by starvation, and residual layer were recognized. The formation of an equilibrium film determined by the balance of lubricant loss and replenishment was analyzed. The primary mechanisms that dominate grease film formation in different lubricated contacts were clarified.
Tribological Behavior Of Ammonium-Based Protic Ionic Liquid As Lubricant Additive, 2020 Mechanical Engineering Department, Rochester Institute of Technology, New York 14623-5603, USA
Tribological Behavior Of Ammonium-Based Protic Ionic Liquid As Lubricant Additive, Hong Guo, Patricia Iglesias
In this study, the tribological behavior of an ammonium-based protic ionic liquid (PIL) as an additive in a base mineral oil (MO) is investigated on a steel-steel contact at room temperature and 100 °C. Tri-[bis(2-hydroxyethylammonium)] citrate (DCi) was synthesized in a simple and low-cost way, and the ionic structure of DCi was confirmed by proton nuclear magnetic resonance (1H NMR). The stability measurement of 1 wt% DCi to a MO was investigated, and the lubricating ability and anti-wear properties of DCi as an additive in MO were also examined using a custom-designed reciprocating ball-on-flat tribometer. Optical microscope ...
Influence Of Lubrication, Tool Steel Composition, And Topography On The High Temperature Tribological Behaviour Of Aluminium, 2020 Machine Elements, Luleå University of Technology, Luleå SE-97187, Sweden
Influence Of Lubrication, Tool Steel Composition, And Topography On The High Temperature Tribological Behaviour Of Aluminium, Justine Decrozant-Triquenaux, Leonardo Pelcastre, Braham Prakash, Jens Hardell
The use of high strength aluminium alloys, such as 6XXX and 7XXX series, is continuously increasing for automotive applications in view of their good strength-to-weight ratio. Their formability at room temperature is limited and they are thus often formed at high temperatures to enable production of complex geometries. Critical challenges during hot forming of aluminium are the occurrence of severe adhesion and material transfer onto the forming tools. This negatively affects the tool life and the quality of the produced parts. In general, the main mechanisms involved in the occurrence of material transfer of aluminium alloys at high temperature are ...
Modified Graphene As Novel Lubricating Additive With High Dispersion Stability In Oil, 2020 State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Modified Graphene As Novel Lubricating Additive With High Dispersion Stability In Oil, Pu Wu, Xinchun Chen, Chenhui Zhang, Jiping Zhang, Jianbin Luo, Jiyang Zhang
Graphene is a promising material as a lubricant additive for reducing friction and wear. Here, a dispersing method which combines chemical modification of graphene by octadecylamine and dicyclohexylcarbodiimide with a kind of effective dispersant has been successfully developed to achieve the remarkable dispersion stability of graphene in base oil. The stable dispersion time of modified graphene (0.5 wt%) with dispersant (1 wt%) in PAO-6 could be up to about 120 days, which was the longest time reported so far. At the same time, the lubricant exhibits a significant improvement of tribological performance for a steel ball to plate tribo-system ...
Electroadhesion Between A Flat Touchscreen And The Human Finger With Randomly Self-Affine Fractal Surface, 2020 Department of Physics, University of Tehran, Tehran 14395-547, Iran Department of Physics, Alzahra University, Tehran 1993891167, Iran
Electroadhesion Between A Flat Touchscreen And The Human Finger With Randomly Self-Affine Fractal Surface, M. Feshanjerdi
In this study, the effects of finger roughness on the electrostatic potential, electrostatic field, and average effective squeezing pressure between a human finger and a touchscreen are calculated by the perturbation method. This theory is an extension of an earlier work by Persson. It is found that an additional potential <ϕ(2)> will appear between the solids when the roughness effect is considered in calculating the perturbation potential. This additional potential is still proportional to the distance u¯ from the bottom surface. Therefore, the effect of the roughness increases the effective potential <ϕ> between the two solids. As a result, the average electrostatic ...ϕ>ϕ(2)>
Multiscale Analysis Of Friction Behavior At Fretting Interfaces, 2020 State Key Laboratory of Mechanical Systems and Vibrations, Shanghai Jiao Tong University, Shanghai 200240, China
Multiscale Analysis Of Friction Behavior At Fretting Interfaces, Zhinan Zhang, Shuaihang Pan, Nian Yin, Bin Shen, Jie Song
Friction behavior at fretting interfaces is of fundamental interest in tribology and is important in material applications. However, friction has contact intervals, which can accurately determine the friction characteristics of a material; however, this has not been thoroughly investigated. Moreover, the fretting process with regard to different interfacial configurations have also not been systematically evaluated. To bridge these research gaps, molecular dynamics (MD) simulations on Al-Al, diamond-diamond, and diamond-silicon fretting interfaces were performed while considering bidirectional forces. This paper also proposes new energy theories, bonding principles, nanoscale friction laws, and wear rate analyses. With these models, semi-quantitative analyses of coefficient ...
Tribological And Anti-Corrosion Performance Of Epoxy Resin Composite Coatings Reinforced With Differently Sized Cubic Boron Nitride (Cbn) Particles, 2020 Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China University of Chinese Academy of Sciences, Beijing 100049, China
Tribological And Anti-Corrosion Performance Of Epoxy Resin Composite Coatings Reinforced With Differently Sized Cubic Boron Nitride (Cbn) Particles, Zhiping Huang, Wenjie Zhao, Wenchao Zhao, Xiaojing Ci, Wentao Li
A series of high solid content (30 wt%) epoxy resin (EP) composite coatings reinforced with differently sized cubic boron nitride (CBN) particles were fabricated successfully on 304L stainless steel. Polydopamine (PDA) was used to improve the dispersibility of CBN particles in EP. The structural and morphological features of the CBN particles and the composite coatings were characterized by Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, a UMT-3 tribometer and surface profiler were used to investigate the tribological behaviors of the as-prepared composite coatings. Electrochemical impedance spectroscopy (EIS) and Tafel analysis were used to investigate the ...
A New Kind Of Resin-Based Wet Friction Material: Non-Woven Fabrics With Isotropic Fiber Networks As Preforms, 2020 State Key Laboratory of Solidification Processing, Shaanxi Province Key Laboratory of Fiber Reinforced Light Composite Materials, Northwestern Polytechnical University, Xi’an 710072, China
A New Kind Of Resin-Based Wet Friction Material: Non-Woven Fabrics With Isotropic Fiber Networks As Preforms, Yewei Fu, Le Zhou, Tao Yin, Zhongyao Luo, Hejin Li, Lehua Qi
As an alternative to short fibers, non-woven fabrics (NWFs) were made using different types of long fibers to optimize the performance of paper-based friction materials and their technology. In this investigation, the fillers and resin were impregnated into these NWFs to prepare three kinds of wet friction material. The tribological, mechanical, and thermal properties of the new wet friction material were studied. The results indicate that the dynamic friction coefficient of the new friction material is approximately 0.12 and the static friction coefficient is approximately 0.15; the better wear rate is 0.81334 × 10−14 m3·(N ...
Comparative Study On Corrosion Resistance And Lubrication Function Of Lithium Complex Grease And Polyurea Grease, 2020 Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China
Comparative Study On Corrosion Resistance And Lubrication Function Of Lithium Complex Grease And Polyurea Grease, Guanlin Ren, Pengfei Zhang, Xiangyuan Ye, Wen Li, Xiaoqiang Fan, Minhao Zhu
In this study, lithium complex grease (LCG) and polyurea grease (PUG) were synthesized using mineral oil (500SN) and polyalphaolefin (PAO40) as base oil, adsorbed onto lithium complex soap and polyurea as thickeners, respectively. The effects of grease formulation (thickener and base oil with different amounts (80, 85, and 90 wt%) on the corrosion resistance and lubrication function were investigated in detail. The results have verified that the as-prepared greases have good anti-corrosion ability, ascribed to good salt-spray resistance and sealing function. Furthermore, the increase in the amount of base oil reduces the friction of the contact interface to some extent ...
Effects Of Magnetic Ionic Liquid As A Lubricant On The Friction And Wear Behavior Of A Steel-Steel Sliding Contact Under Elevated Temperatures, 2020 Engineering Research Center for Nanomaterials, Henan University, Kaifeng 475004, China
Effects Of Magnetic Ionic Liquid As A Lubricant On The Friction And Wear Behavior Of A Steel-Steel Sliding Contact Under Elevated Temperatures, Jiajia Jia, Guangbin Yang, Chunli Zhang, Shengmao Zhang, Yujuan Zhang, Pingyu Zhang
A magnetic ionic liquid (abridged as MIL) [C6mim]5[Dy(SCN)8] was prepared and used as the magnetic lubricant of a steel-steel sliding pair. The tribological properties of the as-prepared MIL were evaluated with a commercially obtained magnetic fluid lubricant (abridged as MF; the mixture of dioctyl sebacate and Fe3O4, denoted as DIOS-Fe3O4) as a control. The lubrication mechanisms of the two types of magnetic lubricants were discussed in relation to worn surface analyses by SEM-EDS, XPS, and profilometry, as well as measurement of the electric contact resistance of the rubbed ...
The Correlation Between Friction Coefficient And Areal Topography Parameters For Aisi 304 Steel Sliding Against Aisi 52100 Steel, 2020 Department of Mechanical Engineering, Indian Institute of Technology, Patna 801103, India
The Correlation Between Friction Coefficient And Areal Topography Parameters For Aisi 304 Steel Sliding Against Aisi 52100 Steel, Deepak K. Prajapati, Mayank Tiwari
Dry wear experiments provide an insight detail on how severely contacting surfaces change under unlubricated sliding condition. The theory of dry sliding wear is used for understanding mixed-lubrication regime in which asperity interactions play a significant role in controlling of the friction coefficient (f). The purpose of this work is to study the tribological behavior of AISI 304 steel in contact with AISI 52100 steel during wear. Both materials are used in rolling element bearings commanly. Experiments are carried out using a pin-on-disc tribometer under dry friction condition. The areal (three dimensional, 3D) topography parameters are measured using a 3D ...