Tribology on the Small Scale: A Bottom Up Approach to Friction, Lubrication, and Wear

Abstract

Friction, lubrication and wear interactions between materials make considerable differences to how efficient our engines are, whether or not we ski downhill faster than others, or whether the shoes that we are wearing give us sufficient grip to successfully navigate the marble floors of buildings. Traditionally, tribologists have focussed on the macroscopic issues of tribological problems, looking at the design of components, the viscosity of oils and the mechanical properties of surfaces to understand how components interact to give the desired friction and wear properties. However, in the last twenty years there has been an increasing realization that the processes that are controlling these macroscopic interactions are determined by what happens on the atomic and microscopic scale. Further, with the advent of nano- and micro-electro mechanical systems (NEMs and MEMs), macroscopic scale tribological interactions do not influence the tribology of these devices in the same way, and capillary forces and van der Waal's forces play an increased role in determining whether these devices function successfully.This book aims to fill a gap in the area of tribology textbooks by addressing the important advances that have been made in our understanding of the science of nano- and micro-scale tribological interactions. The book is aimed at advanced undergraduate and graduate level students on engineering programmes, academics and scientists interested in atomic and microscopic scale tribological interactions, and engineers and scientists who are not tribologists per se but work in technologies (such as NEMs/MEMs) where tribology is of importance. Whilst the target audience appears to be largely engineers, the book should have wider appeal to physicists, chemists and modellers with interests in tribological interactions. The book consists of twelve chapters with an introduction to the general significance of tribology and a brief history of modern tribology, followed by more detailed coverage of characterization and quantification of surface roughness. There is then a discussion of the mechanical properties of surfaces, and an introduction to contact mechanics. This follows a similar structure to traditional tribology textbooks but there are some nice examples and illustrations of how this relates to small scale tribology, with reference to recording heads on laser textured disk surfaces for example. The origins of friction are then discussed, with a detailed section on stick-slip interactions which are particularly significant in tribological interactions at the small scale.Chapters 5–8 then deviate from the more traditional tribology textbooks and cover surface energies and capillary forces, surface forces and their physical origins, and the measurement of these forces by the surface force apparatus and atomic force microscope. Surface forces at the small scale and capillary forces are extremely important in the successful functioning of small scale nano- or micro-electro mechanical systems, and there is a good discussion of the origin of these forces and how they can be understood, measured and controlled.The final chapters are devoted to lubrication, and atomistic origins of friction and wear. Traditional lubrication theories are initially outlined followed by detailed examples of boundary lubrication and capillary forces in tribology at the micro-scale. There are some nice examples of the importance of lubricant chemistry on sliding forces. Overall I found this book to be well-written and very readable with some very nice examples of why all this fundamental background is of importance in practical applications. The book is well-presented and it should be accessible to its target audience, particularly since the cost is reasonable. Each chapter ends with a set of selected references to allow more detailed study of particular topics if desired. There is a comprehensive index at the end of the book. I will recommend it to my students on courses on tribology and surface engineering.