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Bhushan, B. “Boundary Lubrication Studies Using Atomic Force/Friction .” Handbook of Micro/Nanotribology. Ed. Bharat Bhushan Boca Raton: CRC Press LLC, 1999 © 1999 by CRC Press LLC Boundary Lubrication Studies Using Atomic Force/Friction Force Microscopy Bharat Bhushan 8.1 8.2 8.3 8.4 Introduction Nanodeformation, Adhesive Forces, and Molecular Conformation Boundary Lubrication Studies Liquid Lubricants • LB and Self-Assembled Monolayers 8 Closure References 8.1 Introduction Boundary films are formed by physical adsorption, chemical adsorption, and chemical reaction. The physisorbed film can be either monomolecular or polymolecular thick. The chemisorbed films are monomolecular, but stoichiometric films formed by chemical reaction can have a large film thickness. In general, the stability and durability. | Bhushan R Boundary Lubrication Studies Using Atomic Force Friction . Handbook of Micro Nanotribology. Ed. Bharat Bhushan Boca Raton CRC Press LLC 1999 1999 by CRC Press LLC 8 Boundary Lubrication Studies Using Atomic Force Friction Force Microscopy Bharat Bhushan 8.1 Introduction 8.2 Nanodeformation Adhesive Forces and Molecular Conformation 8.3 Boundary Lubrication Studies Liquid Lubricants LB and Self-Assembled Monolayers 8.4 Closure References 8.1 Introduction Boundary films are formed by physical adsorption chemical adsorption and chemical reaction. The physisorbed film can be either monomolecular or polymolecular thick. The chemisorbed films are monomolecular but stoichiometric films formed by chemical reaction can have a large film thickness. In general the stability and durability of surface films decrease in the following order chemical reaction films chemisorbed films and physisorbed films. A good boundary lubricant should have a high degree of interaction between its molecules and the sliding surface. As a general rule liquids are good lubricants when they are polar and thus able to grip solid surfaces or be adsorbed . Polar lubricants contain reactive functional groups with low ionization potential or groups having high polarizability Bhushan 1993 . Boundary lubrication properties of lubricants are also dependent upon the molecular conformation and lubricant spreading Novotny et al. 1989 Novotny 1990 Mate and Novotny 1991 Mate 1992a . This chapter presents an overview of lubrication studies of polar and nonpolar lubricants and Langmuir-Blodgett and chemically grafted films using atomic force friction force microscopy. 8.2 Nanodeformation Adhesive Forces and Molecular Conformation Nanodeformation behavior of the bonded lubricant was studied using atomic force microscopy AFM by Blackman et al. 1990a . They used Si 100 substrate with about 1.5 nm of native oxide. Just prior to 1999 by CRC Press LLC Tip-Sample Separation Distance A FIGURE 8.1 Wire deflection
