Physics and Chemistry of Micro-Nanotribology Jianbin Luo Yuanzhong Hu Shizhu Wen Editors Physics and Chemistry of Micro-Nanotribology Jianbin Luo, Yuanzhong Hu, and Shizhu Wen ASTM Stock Number: MONO7 ASTM International 100 Barr Harbor Drive PO Box C700 West Conshohocken, PA 19428–2959 Printed in the U.S.A. Library of Congress Cataloging-in-Publication Data Luo, Jianbin, 1961– Physics and chemistry of micro-nanotribology/Jianbin Luo, Yuanzhong Hu, Shizhu Wen. p. cm. “ASTM Stock Number: MONO7.” ISBN 978-0-8031-7006-3 1. Tribology. I. Hu, Yuanzhong, 1946– II. Wen, Shizhu, 1932– III. Title TJ1075.L825 2008 621.8’9—dc22 2008023825 Copyright © 2008 ASTM International, West Conshohocken, PA. All rights reserved. This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, with- out the written consent of the publisher. Photocopy Rights Authorization to photocopy items for internal, personal, or educational classroom use of specific clients, is granted by ASTM International provided that the appropriate fee is paid to ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428–2959, Tel: 610–832–9634; online:http://www.astm.org/ copyright/ The Society is not responsible, as a body, for the statements and opinions advanced in this publication. ASTM International does not endorse any products represented in this publication. Printed in City, State Month, Year ii Dedication This Monograph is dedicated to the 20 th anniversary of the State Key Laboratory of Tribology. Jianbin Luo Yuanzhong Hu Shizhu Wen iii Acknowledgment This book was brought to fruition by the efforts of many individuals. We would like to thank all of them, beginning with the editor and the publication staff of ASTM International, especially Dr. George Totten who has encouraged us to publish our research achievements in this monograph, and Kathy Dernoga and Monica Siperko who have given us guidance and assistance from the outset of the venture. In addition, we wish to convey appreciation to the authors who have devoted considerable time, energy, and resources to support this endeavor. We are also grateful to the reviewers of the various chapters who, through their suggestions, permit- ted good manuscripts to be made better. Finally, we are grateful for the support from government and industry through various research programs, including National Basic Research Program of China, National Natural Science Foundation of China, and international joint researches. Their support of our research activities has led to this publication. Jianbin Luo Yuanzhong Hu Shizhu Wen v Foreword THIS PUBLICATION, Physics and Chemistry of Micro-Nanotribology, was sponsored by Committee D02 on Petroleum Products and Lubricants. This is Monograph 7 in ASTM International’s manual series. vii Contents Preface xi Chapter 1: Introduction, Shizhu Wen, Jianbin Luo, and Yuanzhong Hu 1 The Measurement and Investigation of Thin Film Lubrication „TFL… 2 Surface Coatings 2 Applications of Micro/Nanotribology 3 Summary 4 Chapter 2: Measuring Techniques, Dan Guo, Jiangbin Luo, and Yuanzhong Hu 7 Introduction 7 Optical Measuring Techniques 8 Surface Force Apparatus 14 Scanning Probe Microscope 18 Nanoindentation and Nanoscratching 22 Other Measuring Techniques 26 Chapter 3: Thin Film Lubrication—Experimental Study, Jianbin Luo and Shizhu Wen 37 Introduction 37 Properties of Thin Film Lubrication 39 The Failure of Lubricant Film 53 Thin Film Lubrication of Ionic Liquids 54 Gas Bubble in Liquid Film under External Electric Field 55 Summary 60 Chapter 4: Thin Film Lubrication—Theoretical Modeling, Chaohui Zhang 63 Introduction 63 Spatial Average and Ensemble Average 64 Velocity Field of Lubricants with Ordered Molecules 65 Simulations via Micropolar Theory 67 Rheology and Viscosity Modification 72 Other Approaches Related to TFL Theories 74 Conclusions 77 Chapter 5: Molecule Films and Boundary Lubrication, Yuanzhong Hu 79 Introduction 79 Mechanisms of Boundary Lubrication 80 Properties of Boundary Films as Confined Liquid 82 Ordered Molecular Films 88 Discussions on Boundary Friction 93 Summary 94 Chapter 6: Gas Lubrication in Nano-Gap, Meng Yonggang 96 History of Gas Lubrication 96 Theory of Thin Film Gas Lubrication 97 Application of Gas Lubrication Theory 103 Summary 114 Chapter 7: Mixed Lubrication at Micro-scale, Wen-zhong Wang, Yuanzhong Hu, and Jianbin Luo 116 Introduction 116 Statistic Approach of Mixed Lubrication 116 A DML Model Proposed by the Present Authors 118 Validation of the DML Model 125 Performance of Mixed Lubrication—Numerical and Experimental Studies 130 Summary 144 [...]... distance The circuitry of the FFM is similar to that of the laserAFM, in the aspect of feedback circuit, driver circuit, and the amplifier circuit of the vertical electrical signal To facilitate the study of nanotribology, the unit of gain amplification of the electrical signal caused by lateral force, the unit of comparison and controlling of reference signal, and the unit of adjustment of the PZT were added... measurement 16 PHYSICS AND CHEMISTRY OF MICRO-NANOTRIBOLOGY Fig 16—A sketch of samples and fringes of FECO ͑a͒ Mica sheets, silver films, and the light path ͑b͒ Fringes before and after shift flected by the film, but a part of the light may penetrate the film, pass the gap, and arrive at the second silver film on the upper sample, where a similar process of reflection/ penetration occurs and the beam reflected... computer and compared with the signal from the PSD in order to change micro-load between the sample and the tip The information of attractive force and adhesive force between the sample and the tip can also be obtained by turning off the feedback unit by computer and charge voltage to the PZT The software of the FFM mainly consists of three parts: ͑1͒ the program of scanning, data collecting, and image... friction and impact process Subsequently, Heinicke ͓4͔ published his monograph in a book titled Tribochemistry, emphasizing an integration of tribology and chemistry Bio-tribology emerged in the 1970s and is another example of the integration of multi-scientific sub1 ject research that bridges tribology, biology, and iatrology In development, it integrated with bionics and nanotechnology, and created... measurement of friction force applied for the purpose of obtaining a real-time force curve during a process of approach and separation, although at the cost of reduction of resolution in the force measurement 3.2.4 Measurement of Lateral Forces A remarkable success of SFA in recent years has been found in applications to the field of tribology, particularly in the investigations of micro and nanotribology... load/contact-area relation 18 PHYSICS AND CHEMISTRY OF MICRO-NANOTRIBOLOGY Fig 20—Principle of scanning tunneling microscopy Fig 19—A schematic force curve as a function of film thickness for the liquid of linear chain molecules cant role in future studies of micro/nanotribology, biology, and other fields of surface science 4 Scanning Probe Microscope follows the JKR theory, and the friction between the... introduced by Meyer and Amer ͓49͔, where a laser is reflected from the back of the reflective AFM lever and onto a position-sensitive detector A schematic drawing of an AFM is in Fig 23 ͓47͔ A 20 PHYSICS AND CHEMISTRY OF MICRO-NANOTRIBOLOGY resonant frequency of a spring loaded with an effective mass m is: 0 = Fig 23—Schematic drawing of the atomic force microscope sharp tip at the end of a cantilever... control of the computer, the reflected beam deflected and changed the position on PSD due to the twist and deflection of the cantilever caused by changes of surface roughness, friction force, and adhesive force between the sample and the tip The extension and retraction of the PZT was feedback controlled by an electrical signal from the vertical direction of the PSD Thereby the surface morphologies of the... controlling system, and computer controlling system The stage system consists of four parts: the light reflection, preamplifier, driver of scanning, and step motor controller The part of light reflection consists of laser diode, lens, cantilever, PSD, and mechanical adjustment components The preamplifier consists of precision instrument amplifiers to receive and amplify the electrical signal of the PSD, and convert... driver of scanning refers to the cantilever, Fig 26—The system schematic diagram of FFM designed by Lu et al ͓9͔ 22 PHYSICS AND CHEMISTRY OF MICRO-NANOTRIBOLOGY Fig 27—The images of three-dimensional morphologies, ͑a͒ and lateral force ͑b͒ of Au film ͓9͔ which can move at three-dimensions by charge The step motor controller is used for moving the sample up and down It can be automatically turned off . nano- structured superhard coatings. Their superhardness and other mechanical properties are determined by a proper de- sign of microstructure. A typical example for nano- 2 PHYSICS AND CHEMISTRY OF MICRO-NANOTRIBOLOGY. this report as the sci- ence and technology of interacting surfaces in relative mo- tion and ofrelated subjects and practices.Thereport empha- sized the importance and a great potential power of tribology. theoretical devel- opment of boundary lubrication. Perfluoropolyethers ͑PFPE͒, particularly PFPE Z-DOL, is one of the synthetic lu- bricants that is widely applied due to its excellent perfor- mance,