**Section 3 Friction 147**  Chapter 9 **Friction in Automotive Engines 149**  H. Allmaier, C. Priestner, D.E. Sander and F.M. Reich Chapter 10 **Theories on Rock Cutting, Grinding and Polishing Mechanisms 185**  Irfan Celal Engin Chapter 11 **General Approach to Mechanochemistry and Its Relation to Tribochemistry 209**

Czesław Kajdas

VI Contents

**Section 3 Friction 147** 

Chapter 9 **Friction in Automotive Engines 149** 

Chapter 10 **Theories on Rock Cutting, Grinding** 

Irfan Celal Engin

Czesław Kajdas

**and Polishing Mechanisms 185** 

**and Its Relation to Tribochemistry 209** 

Chapter 11 **General Approach to Mechanochemistry** 

H. Allmaier, C. Priestner, D.E. Sander and F.M. Reich

Preface

Although the study of friction and wear caught the attention of many eminent scientists during the course of the past few centuries, consistent and sustained scientific investigation into friction and wear is a relatively recent phenomenon. Tribology is therefore a comparatively young science where rigorous analytical concepts have not yet been established to provide a clear guide to the complex characteristics of wear and friction. Much of the tribological research is applied or commercially orientated and already a wide range of wear-resistant or frictionreducing materials have been developed. The basic concept of tribology is that friction and wear are best controlled with a thin layer or intervening film of material separating sliding, rolling, and impacting bodies. There is almost no restriction on the type of material that can form such a film and some solids, liquids and gases are equally effective. If no film material is supplied then the process of wear itself may generate a substitute film. The aim of tribology is either to find the optimum film material for a given application or to predict the sequence of events when a sliding,

Chapters in this book describe the fundamental wear mechanisms operating in metallic and non- metallic materials together with some prognoses concerning the future developments of these materials. Two classes of materials with entirely different characteristics polymers and ceramics are discussed. Polymers can provide low friction and low wear coefficients but their use is limited to lower temperatures and consequently low speeds and loads. Ceramics are resistant to high temperatures and often have a good wear resistance but their applications are limited by poor friction coefficients, especially in unlubricated applications. Ceramics and polymers are surprisingly vulnerable to accelerated wear in the presence of corrosive reagents and care should be taken in the selection of materials that are appropriate for particular operating conditions. None of these materials meet current or future needs, and much effort is being expended to develop new materials and improve the properties of existing materials for new and future applications. The development of polymer and ceramic matrix composites reinforced by fibres, platelets, and

Very few tribology chapters exist and these are dated. They have focused on conventional tribology, traditional materials and matured industrial applications. The

rolling, impacting contact is left to generate its own intervening film.

particulates serves as an example of these efforts.
