Symposium Organizers
Yasuhisa Ando National Institute of Advanced Industrial Science and Technology
Robert W. Carpick The University of Pennsylvania
Roland Bennewitz McGill University
W. Greg Sawyer University of Florida
T1: Interfacial Aging, Adhesion, and Friction
Session Chairs
Tuesday PM, March 25, 2008
Room 3006 (Moscone West)
9:00 AM - **T1.1
Crack-like Processes Within Frictional Motion - Is Slow Frictional Sliding Really a Slow Process?
Jay Fineberg 1 , Shmuel Rubinstein 1
1 The Racah Institute of Physics, Hebrew University, Jerusalem Israel
Show Abstract9:30 AM - **T1.2
High frame-rate Videography Indicates the Origin of Frictional Aging and Bifurcation Behavior in a Micromachine.
Maarten de Boer 1 , Alex Corwin 2
1 Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 2 Microsystems & Microfluidics Laboratory, GE Global Research, Niskayuna, New York, United States
Show Abstract10:00 AM - T1.3
Hysteresis in the Adhesion of Surface-Force Mediated Silicon Contacts with Nanoscale Roughness.
John Nguyen 1 , Kevin Turner 1
1 Mechanical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States
Show Abstract10:15 AM - T1.4
Nano-scale Tribological Behavior of Polycrystalline Silicon Structural Films in Ambient Air.
Daan Hein Alsem 1 , Ruben van der Hulst 2 , Eric Stach 3 , Michael Dugger 4 , Jeff de Hosson 2 , Robert Ritchie 5 6
1 Materials Sciences Division / National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 Department of Applied Physics, University of Groningen, Groningen Netherlands, 3 School of Materials Engineering / Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, United States, 4 Materials Science and Engineering Center, Sandia National Laboratories, Albuquerque, New Mexico, United States, 5 Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California, United States, 6 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractTribological properties associated with friction and wear are critical factors in the reliability of silicon nano- and microelectromechanical systems (NEMS/MEMS). Accordingly, it has become important to understand the nanomechanical processes associated with wear and friction in polysilicon. To address this issue, MEMS sidewall friction and wear devices (fabricated in the Sandia SUMMiT V(TM) process) were run in ambient air at uN normal loads. Dynamic friction coefficients measured as a function of number of wear cycles show an increase by a factor of two up to a steady-state regime. This increase is related to the evolution of the surface morphology and the roughness of the wearing surfaces (as measured by scanning and transmission electron microscopy and atomic force microscopy (AFM) respectively), and shows abrasive wear grooves being formed before reaching the steady-state friction regime. AFM was also utilized to quantify the volume of nano-scale wear as function of number of cycles and to calculate dimensionless wear coefficients, which (like the evolution of the surface roughness) show a slow decrease after a sharp increase as the number of wear cycles increases. These nano-scale wear coefficients are orders of magnitude smaller than macro-scale wear coefficients of abrasively worn polysilicon. All these measurements point to a dominating abrasive wear mechanism, governed by nano-scale debris particles created by fracture.
10:30 AM - **T1.5
Probing Molecular Assembly and Adhesion in Nanoscale Asperity-Asperity Contacts.
James Batteas 1
1 Department of Chemistry, Texas A&M University, College Station, Texas, United States
Show Abstract11:00 AM - T1: Interfacial
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T2: Nanotribology of Materials for Devices
Session Chairs
Tuesday PM, March 25, 2008
Room 3006 (Moscone West)
11:30 AM - **T2.1
Nanoscale Mechanisms for Single Asperity Sliding Wear.
Bernd Gotsmann 1 , Mark Lantz 1 , Rachel Cannara 1
1 IBM Research GmbH, IBM Zurich Research Laboratory, Rueschlikon Switzerland
Show Abstract12:00 PM - T2.2
Accelerated Molecular Dynamics Simulation of AFM Experiments Using the Bond-Boost Method.
Woo Kyun Kim 1 , Michael Falk 2
1 Mechanical Engineering, The University of Michigan, Ann Arbor, Michigan, United States, 2 Materials Science and Engineering, The University of Michigan, Ann Arbor, Michigan, United States
Show Abstract12:15 PM - T2.3
Nanoscale Wear-resistance of Platinum Silicide Tips.
Harish Bhaskaran 1 , Ute Drechsler 1 , Bernd Gotsmann 1 , Rachel Cannara 1 , Mark Lantz 1 , Michel Despont 1
1 , IBM Zurich Research Laboratory, Ruschlikon, Zurich, Switzerland
Show Abstract12:30 PM - T2.4
Nonlinear Viscoelastic Dynamics Of Nano-Confined Wetting Liquids.
Tai-de Li 1 , Elisa Riedo 1
1 , Georgia Tech, Atlanta, Georgia, United States
Show AbstractTuesday, March 25Transferred Poster T5.18 to T2.4 @ 11:30 AMNonlinear Viscoelastic Dynamics Of Nano-Confined Wetting Liquids. Tai-de Li
12:45 PM - T2.5
Compliant Low-Force Electrical Switching Using Metal Infiltrated Multi-Wall Nanotube Arrays.
Justin Bult 1 , Greg Sawyer 2 , Pulickel Ajayan 3 , Linda Schadler 1
1 Materials Science, Rensselaer Polytechnic Institute, Troy, New York, United States, 2 Mechanical Engineering, University of Florida, Gainesville, Florida, United States, 3 Mechanical Engineering, Rice University, Houston, Texas, United States
Show Abstract
Symposium Organizers
Yasuhisa Ando National Institute of Advanced Industrial Science and Technology
Robert W. Carpick The University of Pennsylvania
Roland Bennewitz McGill University
W. Greg Sawyer University of Florida
T5: Poster Session: Nanotribology
Session Chairs
Wednesday PM, March 26, 2008
Exhibit Hall (Moscone West)
1:00 AM - T5.1
Computational Investigation of Thermal Activation of Friction in Polytetrafluoroethylene.
Inkook Jang 1 3 , Peter Barry 1 , Scott Perry 1 , W. Gregory Sawyer 1 2 , Susan Sinnott 1 , Simon Phillpot 1
1 Material Science and Engineering, University of Florida, Gainesville, Florida, United States, 3 , Samsung Electronics Co., LTD, Hwang-City, Gyeonggi-Do, Korea (the Republic of), 2 Mechanical and Aerospace Engineering, Universitiy of Florida, Gainesville, Florida, United States
Show AbstractAtomic-scale simulations provide valuable insights into the mechanisms responsible for experimentally observed friction at the atomic or molecular scale. We use classical molecular dynamics simulations in conjunction with experimental data to determine the influence of material type, surface structure, and temperature on observed friction coefficients. While friction in solids is generally considered to be athermal, under certain conditions thermally activated behavior has been observed experimentally. Interestingly, both thermally activated and athermal friction have been experimentally observed in tribological studies of polytetrafluroethylene (PTFE) sliding surfaces. Here we explore the origins of these effects. We find that, by changing the relationship between the sliding direction and the polymer chain direction, the friction can be switched from a wear-free to a highly wearing friction mode. The simulations explore the relationship of these regimes to the thermally activated behavior.
1:00 AM - T5.10
Moisture Effects on Gold Nanowear.
Alex Volinsky 1 , Megan Pendergast 1 , Xiaolu Pang 2
1 Mechanical Engineering, University of South Florida, Tampa, Florida, United States, 2 Materials Physics and Chemistry, University of Science and Technology, Beijing, Beijing China
Show AbstractWater has pronounced effect on materials tribological and wear properties. We observed a substantially higher wear rate of single crystal and thin film gold at the nanoscale in the presence of water compared to ambient environmental conditions. Environmental wear tests were performed in AFM, and Hysitron Triboindenter. Details of wear testing at the nanoscale along with the possible mechanisms responsible for the higher wear rate in the presence of water are discussed.
1:00 AM - T5.11
Micromachined Lateral Force Sensors for Characterization of Microscale Surface Forces During Chemical Mechanical Polishing.
Douglas Gauthier 1 , Andrew Mueller 1 , Robert White 1 , Vincent Manno 1 , Chris Rogers 1 , Don Hooper 2 , Sriram Anjur 3 , Mansour Moinpour 2
1 Mechanical Engineering, Tufts University, Medford, Massachusetts, United States, 2 , Intel Corporation, Santa Clara, California, United States, 3 , Cabot Microelectronics, Aurora, Illinois, United States
Show AbstractThis paper describes the measurement of pad-wafer forces in situ during polishing. Micromachined structures have been fabricated for this purpose, and allow interrogation of the local pad-wafer surface forces during polishing with a spatial resolution of less than 100 μm and a temporal resolution of less than 1 ms. Forces in the dynamic range of 50-500 μN can be measured. Two types of micromachined shear stress sensors are described: (1) Polydimethylsiloxane (PDMS) post-like sensors (2) Silicon-on-glass floating element sensors. CMP experiments are conducted on a scaled down model of a silicon dioxide polishing platform. This is achieved using a Struers RotoPol-31 table top polisher with a 12" polishing platen. Downforces during processing are 0.6 to 1.4 psi and platen rotation rates are 30 to 60 rpm. Cab-O-Sperse SC1 fumed silica slurry is used at a 3 weight% solid loading, and polishing is accomplished using IC1000 X-Y grooved pads. Due to current experimental limitations, the pad is not conditioned during processing, nor is the wafer rotated.The PDMS post-like sensors consist of arrays of columns, each of which is 100µm in height and 30µm -100µm in diameter. These columns deflect due to the fluid and contact forces present during polishing. The columns are recessed into circular wells and their uppermost surfaces are coplanar with the wafer surface. When the PDMS wafer is placed under polishing conditions, the columns are designed to deflect between 5µm and 50µm. The deflections are viewed optically through the backside of the transparent glass/PDMS structure using high speed microscopy at 10,000 frames per second. Mechanical calibration of the post-like structures ex situ gives a linear force to deflection ratio of approximately 10 μN/μm over the 10 to 150 μN range. During polishing in a 3 wt % fumed silica slurry with 1 psi downforce and 30 rpm platen rotation, forces vary from less than 50 μN to as high as 375 μN. The force level is highly variable in time, with high-force events occurring with durations as short as 0.5 ms. At 30 rpm platen rotation rate, a linear increase in lateral microscale forces is observed as the downforce increases from 0.6 psi to 1.4 psi. Increasing platen rotation rate to 60 rpm decreases the observed microscale forces during high-force events from approximately 150 μN to approximately 70 μN. Detailed time vs. force information will be presented.Silicon on glass floating element sensors are also under development. These sensors are being designed to have the same dynamic range as the PDMS post-like sensors (50-500 μN), and will be approximately the same diameter (100 μm). These sensors, unlike the PDMS post-in-well sensors, will be suspended above a glass substrate using silicon flexures. Design, fabrication, and calibration of the floating element sensors is ongoing. Comparisons of the results for polishing PDMS posts and polishing silicon floating elements will be presented.
1:00 AM - T5.12
Friction Force Microscope with Electrochemical Control.
Aleksander Labuda 1 , William Paul 1 , Steve Kecani 1 , Roland Bennewitz 1
1 , McGill Univseristy, Montreal, Quebec, Canada
Show AbstractThe design of a high-resolution AFM for liquid environments will be presented. A novel construction of the liquid cell allows for a conventional AFM configuration (horizontal sample on piezotube) while avoiding the lowering the resonance frequency of the piezotube due to mass loading. The solution can be changed in situ via inlets and outlets to the cell. The liquid cell, cantilever holder, and inlet/outlet lines are made of materials compatible with electrochemical experiments, i.e. quartz, Teflon and PEEK. The exchange of solution and chemical purity allow for reliable electrochemical sample preparation, cleaning, or surface modification while imaging. This AFM is aimed toward tribological experiments and imaging on a molecular scale in liquids. We present results for high-resolution friction force microscopy on metal single crystals under electrochemical control. The influence of under potential deposition on friction is explored.
1:00 AM - T5.13
Using Scanned Probe Microscopy to Probe Nanoscale Electric Field Fluctuations.
Showkat Yazdanian 1 , Seppe Kuehn 1 , John Marohn 1
1 Chemistry, Cornell University, Ithaca, New York, United States
Show Abstract1:00 AM - T5.14
Energy Dissipation in the Mechanical-Diode Jump of a Nanoscale Contact.
Juan Jose Martinez 1 , Teresa Cuberes 1
1 Laboratory of Nanotechnology, University of Castilla-La Mancha, Almaden Spain
Show Abstract1:00 AM - T5.15
Combining AFM and Instrumented Indentation for Mechanical Characterization at the Nanoscale.
Flavio Bonilla 1 , Jason Cleveland 1 , Roger Proksch 1
1 Research & Development, Asylum Research, Santa Barbara, California, United States
Show Abstract1:00 AM - T5.16
Ultra-Thin Layer Activation a Potential Tool for Nano-wear Measurements.
Liviu Popa-Simil 1 , Claudiu Muntele 2
1 , LAVM LLC, Los Alamos, New Mexico, United States, 2 , CIM-AAMURI, Huntsville, Alabama, United States
Show Abstract1:00 AM - T5.2
Mechanical and Tribological Characterization of poly(p-xylylene) Nanostructured Thin Films.
Eric So 1 2 , Kathryn Wahl 1 , Melik Demirel 2
1 Code 6176, US Naval Research Laboratory, Washington, District of Columbia, United States, 2 College of Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States
Show Abstract1:00 AM - T5.3
Nanoscale Elastic and Tribological Properties of Poly(Acrylic Acid-co-Sodium Acrylate) Superabsorbent Gels.
Beatriz Talavera 1 , Juan Jose Martinez 1 , Francisca Santiago 1 , Teresa Cuberes 1
1 Laboratory of Nanotechnology, University of Castilla-La Mancha, Almaden Spain
Show Abstract1:00 AM - T5.4
Nanoparticle Liquids with Mixed Coronas for Reconfigurable RF MEMS Relay Switches.
Robert MacCuspie 1 2 , Andrea Elsen 1 , Steve Patton 1 , Shane Juhl 1 , Andrey Voevodin 1 , Steve Diamanti 1 2 , Richard Vaia 1
1 Nanostructured and Biological Materials Branch, Air Force Research Lab, Wright-Patterson AFB, Ohio, United States, 2 , National Research Council, Washington, District of Columbia, United States
Show AbstractNanoparticles assemblies exhibiting flowability in the absence of a solvent have applications from conductive lubricants to processing methods using greener chemistry (requiring zero VOC). In general, the unique rheological character is achieved with single component organic shells or coronas comprised of covalently attached anions stoichiometrically balanced by bulky organic cations. A systematic series of gold nanoparticle liquids with two-component coronas were synthesized using components hypothesized to increase conductivity while maintaining flowability. Detailed chemical characterization (such as FTIR and XPS) confirms purity and establishes relative affinity and exchange rate of the components. Conductivity measurements indicate that increased molar volume or terminal branching of the cation decreases electrical conductivity of the gold assembly. Mixing the components provides ability to maintain conductivity and modulate the rheological character. These nanoparticle liquids have been shown to increase the durability of electrical relays such as RF MEMS by over three orders of magnitude relative to bare gold contacts. Based on this example of using nanoparticle liquids as conductive lubricants, further electronic materials applications could be enabled by this class of material.
1:00 AM - T5.6
Nanoscale Wear Properties Of Ultrananocrystalline Diamond Atomic Force Microscope Probe Tips.
Jingjing Liu 1 , Jacob Notbohm 2 , John Carlisle 3 , Nicolaie Moldovan 3 , Kevin Turner 4 1 , Robert Carpick 5
1 Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin, United States, 2 Engineering physics, University of Wisconsin-Madison, Madison, Wisconsin, United States, 3 , Advanced Diamond Technologies, Inc, Romeoville, Illinois, United States, 4 Mechanical Engineering, University of Wisconsin-Madison , Madison, Wisconsin, United States, 5 Mechanical Engineering and Applied Mechanics, University of Wisconsin-Madison , Philadelphia, Pennsylvania, United States
Show AbstractWear at the nanoscale is a key limitation of conventional silicon and silicon nitride atomic force microscope (AFM) probe tips. Tip degradation induced by tip-sample interactions results in decreased resolution and uncertainty in almost all AFM measurements. The fabrication properties and wear behavior of ultrananocrystalline diamond (UNCD) have attracted significant attention because of its advantageous materials properties for AFM probe applications, such as ultra-high stiffness and hardness, low surface roughness, low macroscale friction coefficient and wear, and chemical inertness. In this paper, the nanoscale adhesion and wear behavior of UNCD, silicon, and silicon nitride probe tips on UNCD surfaces were studied through systematic AFM wear tests. These tests consisted of a series of contact mode AFM scans conducted over a fixed area on a UNCD surface in a controlled dry nitrogen environment. The applied normal load on the tip and the scanning speed were varied to investigate their influence on the adhesion and wear behavior of different tip materials. Over the course of wear tests, changes in tip behavior with the increasing sliding distance, applied load, and scanning speed were monitored by TEM imaging, pull-off force measurements, and tip radius estimation through a blind reconstruction process. We will discuss how the wear behavior of UNCD, silicon, and silicon nitride can be linked to their intrinsic materials properties under different scanning conditions through a nanoscale single asperity wear model based on shear assisted thermal activated atomic bond breaking.
1:00 AM - T5.7
Solid Lubrication with Carbon Onions at High Temperature in Vacuum.
Atsushi Hirata 1 , Shinji Saito 1
1 Department of Mechanical Sciences and Engineering, Tokyo Institute of Technology, Tokyo Japan
Show AbstractThe paper has examined solid lubricant properties at high temperatures up to 300 degree C in vacuum of carbon onions prepared by heat treatment of diamond clusters at 1700 degree C.The nanoscale carbon particles consisting of concentric graphitic multi-shells, so called carbon onions, are one of the fullerene-related materials together with C60 and carbon nanotubes. Owing to a surface structure of carbon onions that includes no defect when a graphene sheet of outermost surface of a carbon onion ideally forms a closed shell, intermolecular reactions of carbon onions with themselves and other materials in contact would be quite low. As this surface characteristic directly leads to low friction, carbon onions have been expected to be a promising solid lubricant and actually found to exhibit low friction and wear rates properties in both air and vacuum at room temperature.Carbon onions were prepared by heat treatment of diamond nanoparticles in size raging around 5 nm made by detonation of trinitrotoluene. Heating of a few ten milligrams of diamond nanoparticles contained in a graphite crucible was carried out using a high frequency induction furnace in an inert ambience. Carbon onions have been produced at 1700 degree C for several minutes. Carbon onions have been characterized by Raman spectroscopy, thermogravimetric analysis, transmission electron microscopy and friction measurement using a ball-on-disk tribometer. Friction was measured in vacuum at temperatures up to 300 degree C using a stainless steel ball and a silicon disk covered with the carbon onions.Raman spectrum taken from the carbon onions included D- and G- peaks that are typical for nanoscale graphitic structures. The carbon onions were oxidation-resistant up to approximately 550 degree C, which is similar behaviour to that of graphite having planar structure. TEM observation revealed that most of carbon onions are spherical in size of 5-10 nm, mixed with extremely small amount of large graphitic particles exceeding 100 nm.The relationship between sliding distance and variation of friction coefficients has been examined. As a result, it has been found that friction coefficients are below 0.05 and decrease with temperatures for sliding testing to about 0.02 at 300 degree C. The reduction of friction coefficients clearly occurred at higher than approximately 100 degree C, which would implies that surface absorbates such as water significantly influence the tribological property of carbon onions. In addition, the reduced friction coefficients at higher temperatures are more stable in terms of service life than at room temperature. A layer of carbon onions aggregating at the contact region on the ball surface was formed during all measurements at various temperatures and helped to protect the wear on both surfaces in contact.
1:00 AM - T5.9
In situ Study on Mechanical Properties and Structural Behavior of Atomic Layer Deposited Titania on Titanium Substrate.
Rynno Lohmus 1 , Irina Hussainova 2 , Silver Leinberg 1 , Jaan Aarik 1 , Ants Lõhmus 1
1 , Institute of Physics Univ of Tartu, Tartu Estonia, 2 , Institute of Materials Engineering, Tallinn Estonia
Show AbstractT4: Nanocontacts: From Atoms to Automobiles
Session Chairs
Wednesday PM, March 26, 2008
Room 3006 (Moscone West)
9:00 AM - **T4.1
Atomic-scale Friction: The Role of the Nano-tip.
Ernst Meyer 1 , Sabine Maier 1 2 , Enrico Gnecco 1 , Alexis Baratoff 1 , Thilo Glatzel 1 , Lars Zimmerli 1 , Roland Bennewitz 2
1 Institute of Physics, University of Basel, Basel Switzerland, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractAtomic-scale friction studies have shown that the transition from stick-slip to smooth sliding can be observed by the change of normal forces. The results can be interpreted in terms of an extended Tomlinson-model [1]. Recent theoretical analysis by Krylov and Frenken have shown that the role of the nano-tip is important [3]. New regimes of atomic friction were proposed [4]. The analysis of the cantilever deflection during the slip and the analysis of slip times is a crucial point for the understanding of the dynamics of this nano-tip. Another challenge in atomic friction is the control of friction. Recently, it has been shown that atomic stick-slip can be suppressed by small electrostatic forces of the nano-contacts. This phenomenon of dynamic superlubricity will be discussed in relation to possible technological applications.[1] A. Socoliuc et al., Phys. Rev. Lett. 92, 134301 (2004).[2] S.Yu. Krylov, J. A. Dijksman, W. A. van Loo, and J.W. M. Frenken, Phys. Rev. Lett. 97, 166103 (2006).[3] S. Y. Krylov and J.W.M. Frenken, New J. Phys. 9, 398 (2007).[4] A. Socoliuc et al., Science 313, 217 (2006).
9:30 AM - T4.2
The Dual Nature of Nanoscale Friction: Amontons' Law vs. Superlubricity.
Andre Schirmeisen 1 2 , Dirk Dietzel 2 3 , Tristan Monninghoff 2 , Claudia Ritter 4 , Udo Schwarz 4
1 Center for Nanotechnology (CeNTech), University of Muenster, Muenster Germany, 2 Institute of Physics, University of Muenster, Muenster Germany, 3 , Forschungszentrum Karlsruhe (FZK), Karlsruhe Germany, 4 Mechanical Engineering, Yale University, New Haven, Connecticut, United States
Show Abstract9:45 AM - T4.3
Hypofriction Property of a Grain Boundary in Gold Nanocrystals studied by Electron Microscopy and Atomistic Modeling.
Frederic Lancon 1 , Jia Ye 2 , Damien Caliste 1 , Tamara Radetic 2 , Andrew Minor 2 , Ulrich Dahmen 2
1 DRFMC, CEA-Grenoble, Grenoble France, 2 NCEM, LBNL, Berkeley, California, United States
Show AbstractTo study the relationship between incommensurability and low static friction coefficient, the 90° <110> tilt grain boundary of face centered cubic crystals is an ideal system that may be considered as the simplest 3D prototype of the 1D Frenkel-Kontorova model. Indeed, at this interface only one direction is incommensurate with the shortest interatomic distance of the crystal being the periodicity of one grain and √2 times this distance (i.e. the cubic cell parameter) being the periodicity of the other grain. This grain boundary has been studied previously by high resolution electron microscopy and atomistic modeling, and a theoretical prediction for an unpinned state has been proposed [Europhysics Letters, 49 (2000) 603].Here we present the results of a combined computational and experimental study of the deformation of such a grain boundary in gold. The experiments were performed using an in-situ nanoindentation holder in an electron microscope to deform individual nano-pillars containing a single incommensurate grain boundary. Prior to the experiment, simulations of gold nano-pillars were conducted to show its feasibility. Comparison with experimental observations shows encouraging agreement, including an nano-pillar asymmetry in the sliding behavior that is related to the stacking fault energy of gold.
10:00 AM - **T4.4
Effects of Roughness, Chemical Disorder and Plastic Deformation on Friction at the Nanoscale.
Mark Robbins 1 , Binquan Luan 1 2 , Shengfeng Cheng 1 , Judith Harrison 3
1 Physics and Astronomy, Johns Hopkins Univ., Baltimore, Maryland, United States, 2 Physics, University of Illinois, Urbana, Illinois, United States, 3 Chemistry, United States Naval Academy, Annapolis, Maryland, United States
Show Abstract10:30 AM - **T4.5
Friction and Lubrication: From Atomic-Scale Experiments to Devices.
Joost Frenken 1
1 Kamerlingh Onnes Laboratory, Leiden University, Leiden Netherlands
Show AbstractWe perform sensitive lateral force measurements with a dedicated Friction Force Microscope (FFM) [1], featuring a specialized lateral force sensor, the ‘Tribolever-TM’ [2]. With this instrument, lateral forces are recorded two-dimensionally, with a sensitivity down to the low picoNewton regime.Whereas the first measurements in this field have demonstrated lateral force patterns, related to stick-slip motion of the tip over the periodic, two-dimensional substrate, recent experiments and model calculations are revealing a multitude of hidden surprises. In particular, I will address lattice effects that can lead to superb slipperiness (‘superlubricity’) [3], thermal effects that can dramatically lower friction (‘thermolubricity’) [4] and multiple-mass-multiple-spring effects that can lead to a multitude of quite unexpected sliding dynamics [5-7].In addition to these FFM experiments, we are developing dedicated MEMS devices [8,9] to explore the role of these atomic-scale effects on the more macroscopic scale of practical, multi-asperity contacts. First results of this work will be presented.[1] M. Dienwiebel et al., Rev. Sci. Instrum. 76, 043704 (2005).[2] T. Zijlstra et al., Sensors and Actuators A: Physical 84, 18 (2000).[3] M. Dienwiebel et al., Phys.Rev.Lett. 92, 126101 (2004); ibid. Surf.Sci. 576, 197 (2005); G.S. Verhoeven et al., Phys.Rev. B 70, 165418 (2004).[4] S.Yu. Kryolov et al., Phys.Rev. E 71, 065101 (2005).[5] S.Yu. Krylov et al., Phys.Rev.Lett. 97, 166103 (2006).[6] D. Abel et al., Phys. Rev. Lett. 99, 166102 (2007).[7] S.Yu. Krylov and J.W.M. Frenken, New J. Phys. 9, 398 (2007).[8] W.M. van Spengen et al., J. Micromech. Microeng. 17, S91 (2007).[9] W.M. van Spengen and J.W.M. Frenken, Tribology Letters 28, 149 (2007).
11:00 AM - T4: Nanocontacts
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11:30 AM - T4.6
Kinetic Effects and the Mechanical Stability of Nanoasperity Contacts.
Adrian Mann 1
1 Materials Sci & Eng, Rutgers University, Piscataway, New Jersey, United States
Show Abstract11:45 AM - **T4.7
Can One Atomic Layer Change Adhesion, Adhesive Transfer and Friction?
Yue Qi 1
1 Materials & Processes Lab, General Motors, Warren, Michigan, United States
Show Abstract12:15 PM - **T4.8
Molecular Simulations for Automotive Tribology.
Hitoshi Washizu 1 , Shuzo Sanda 1 , Shi-aki Hyodo 1 , Toshihide Ohmori 1 , Noriaki Nishino 2 , Atsushi Suzuki 2
1 , Toyota Central R&D Labs., Inc., Nagakute, Aichi, Japan, 2 , Toyota Motor Corporation, Toyota Japan
Show AbstractFriction control of machine elements on a molecular level is a challenging subject in vehicle technology. We describe the molecular dynamics (MD) studies of friction in two significant lubrication regimes. As a case of elastohydrodynamic lubrication, we studied the dynamics of fluids which are used in the traction type continuously variable transmission. The traction MD simulations were performed of hydrocarbon fluids which have a characteristic structure, including an industrial lubricant, and compared with the experiments. The relation between the traction coefficients and molecular structure were then analyzed by focusing on the inter- and intramolecular interactions. The dynamic mechanism of the momentum transfer on layers of fluid molecules were analyzed by focusing on the intermolecular interactions and intramolecular interactions.In order to study the effect of the oil film thickness, we parallelized the MD simulator to calculate dynamics of a half million atoms on a teraflops machine. The mean traction coefficient of a oil film of submicron (430 nm) thickness was qualitatively comparable to the experimental value. The interfacial slip which have been found under a few nm film thickness were not found in the submicron film simulation under the realistic weak solid-fluid interactions. The no-slip boundary condition usually used in the continuous theories and simulations was verified from the atomistic level.The effect of pressure were also studied. A transition of the traction behavior was observed around 0.5 GPa to 1.0 GPa which corresponds to a change from the viscoelastic region to the plastic-elastic one which have been experimentally observed. This phase transition is related to a suppressed fluctuation of the molecular motion.For boundary lubrication, the mechanism of low friction of the diamond-like carbon containing silicon (DLC-Si) coating films which are used in the power-train components were studied. According to experimental analysis of the DLC-Si wear surface, the formation of Si-OH (silanol) have been detected using derivatization-XPS, and an adsorbed water layer of 1 nm to 4 nm thickness have been detected using spectroscopic ellipsometry. Then the role of the adsorbed water layer on the sliding Si-OH terminated surface were examined by MD. The stability and dynamic behavior of water molecules on hydrophilic (Si-OH) and hydrophobic (Si-H) silicon surfaces under a shear condition were studied. In contrast to the case of the Si-H surface from which the water layer is repelled and excluded from the surface, on the Si-OH surface, the stable water layer which was strongly combined with the surface due to the hydrogen bond network was found. This result suggests that water of a few nm film thickness on the Si-OH surface can act as a stable boundary lubrication film.
Symposium Organizers
Yasuhisa Ando National Institute of Advanced Industrial Science and Technology
Robert W. Carpick The University of Pennsylvania
Roland Bennewitz McGill University
W. Greg Sawyer University of Florida
T7: Physical Origins of Friction between Solids
Session Chairs
Thursday AM, March 27, 2008
Room 3006 (Moscone West)
9:30 AM - **T7.1
Electronic Contributions to Friction in Doped Semiconductors.
Miquel Salmeron 1
1 Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractFriction experiments using conductive AFM tips on highly doped semiconductor surfaces have shown a remarkable effect of bias voltage on the friction characteristics of the junction. On a low doping level n-type Si wafer patterned with p-type stripes of highly doped Boron (1018/cm3) we found that friction increases substantially on the p-regions when the bias produces accumulation of carriers. No such effect was observed on the poorly doped n-regions or in the p-regions when the bias produces depletion. A similar effect was more recently observed on highly doped GaAs. In both cases the increase in friction is proportional to the sliding velocity. The origin of the effect cannot be attributed to the generation of low energy electronic excitations such as creation of electron-hole pairs in the accumulation layer, or electron wind effects, charge dragging and ohmic losses. All these effects produce increases in friction that are several orders of magnitude lower that what is measured. We propose a different mechanism to explain the observations that is based on trapping of charge near the surface region. In this mechanism the strong band bending and the high concentration of charge carriers in accumulation populates traps in the gap of the semiconductor and on the thin oxide layer (approx. 1 nm thick) that is present on the surface. It is the electrostatic force from these trapped charges that produces a pull on the tip and thus and increase in friction force.
10:00 AM - T7.2
Atomic Structure and Friction of Ultrathin Solid Lubricants.
Tobin Filleter 1 , William Paul 1 , Roland Bennewitz 1
1 Physics, McGill University, Montreal, Quebec, Canada
Show AbstractThursday, March 27Transferred Poster T5.17 to T7.2 @ 9:00 amAtomic Structure and Friction of Ultrathin Solid Lubricants.Tobin Filleter
10:15 AM - **T7.3
Thermally Activated Friction.
Scott Perry 1
1 Materials Science And Engineering, University of Florida, Gainesville, Florida, United States
Show AbstractA number of tribological applications require operation over a temperature range from 150 to 400 K, or larger. These extreme conditions are often the motivation for variable temperature studies in tribology, but there is a paucity of relevant tribology data available for temperatures below 273 K. Over the range 300 K to 100 K the friction coefficient of various solid lubricants has recently been shown to increase with decreasing temperature. Molecular scale measurements of graphite and molybdenum disulfide employing an atomic force over a temperature range from 140 K to 750 K at a vacuum level of 2x10-10 torr identified an Arrhenius dependence of the friction and friction coefficient, with activation energies of 9.6 kJ/mol for graphite and 28.9 kJ/mol for MoS2. These molecular scale experiments were performed under conditions for which interfacial sliding was confirmed, interfacial wear was absent, and the role of adsorbed contaminants could be dismissed.
10:45 AM - T7.4
Effect of the Sliding Orientation and Temperature on the Tribological Properties of Polyethylene in Molecular Dynamics Simulations.
Patrick Chiu 1 , Seong Jun Heo 1 , Simon Phillpot 1 , Susan Sinnott 1
1 , University of Florida, Gainesville, Florida, United States
Show Abstract11:30 AM - **T7.5
Atomistic Simulations of Tribology at Sliding Molybdenum Disulfide Surfaces.
Tao Liang 1 , Simon Phillpot 1 , Scott Perry 1 , W. Sawyer 1 2 , Susan Sinnott 1
1 Materials Science & Engineering, University of Florida, Gainesville, Florida, United States, 2 Department of Aerospace and Mechanical Engineering, University of Florida, Gainesville, Florida, United States
Show Abstract12:00 PM - T7.6
Extension of Bond-order Potentials for Modeling Tribologically Relevant Materials.
Judith Harrison 1 , J. Schall 1 , Guangtu Gao 1 , M. Knippenberg 1 , Paul Mikulski 2
1 Chemistry, US Naval Academy, Annapolis, Maryland, United States, 2 Physics, US Naval Academy, Annapolis, Maryland, United States
Show Abstract12:15 PM - T7.7
Evaluating the Enviromental Boundaries of Ultrananocrystalline Diamond Thin Film Coatings.
Matthew Hamilton 1 , W. Sawyer 2 , David Grierson 3 , Andrew Konicek 4 , Robert Carpick 1
1 Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2 Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida, United States, 3 Engineering Physics, University of Wisconsin, Madison, Wisconsin, United States, 4 Physics Department, University of Wisconsin, Madison, Wisconsin, United States
Show Abstract12:30 PM - T7.8
Atomic-scale Friction Modulated by a Buried Interface.
Sabine Maier 1 2 , Enrico Gnecco 2 , Alexis Baratoff 2 , Roland Bennewitz 3 , Ernst Meyer 2
1 Materials Sciences Divison, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 Department of Physics, University of Basel, Basel Switzerland, 3 Department of Physics, McGill University, Montreal, Quebec, Canada
Show Abstract12:45 PM - T7.9
Nanoscale Friction Varied by Isotopic Shifting of Surface Vibrational Frequencies.
Robert Carpick 1 , Rachel Cannara 2 , Matthew Brukman 1 , Steven Baldelli 4 , Katherine Cimatu 4 , Anirudha Sumant 3
1 Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2 , IBM Zurich Research Laboratory, Ruschlikon Switzerland, 4 , University of Houston, Houston, Texas, United States, 3 , Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractFriction converts kinetic energy at sliding interfaces into lattice vibrations, but the detailed mechanisms of this process remain unresolved. Atomic force microscopy measurements reveal that changing the mass of the terminating atoms on a surface, and thus their vibrational frequencies, affects nanoscale friction substantially. We compared hydrogen- and deuterium-terminated single-crystal diamond and silicon surfaces, and in all cases the hydrogenated surface exhibited higher friction. This result implies that the lower natural frequency of chemisorbed deuterium reduces the rate at which the tip’s kinetic energy is dissipated. This discovery is consistent with a model describing energy transfer to adsorbates from a moving surface.