Lubrication By Diamond And Diamondlike Carbon Coatings

This book highlights some of the most important structural, chemical, mechanical and tribological characteristics of DLC films. It is particularly dedicated to the fundamental tribological issues that impact the performance and durability of these coatings. The book provides reliable and up-to-date information on available industrial DLC coatings and includes clear definitions and descriptions of various DLC films and their properties.

Diamond-like carbons (DLCs) display a number of attractive properties that make them versatile coating materials for a variety of applications, including extremely high hardness values, very low friction properties, very low gas permeability, good biocompatibility, and very high electrical resistivity, among others. Further research into this material is required to produce hydrogen-free DLC films and to synthesize it together with other materials, thereby obtaining better film properties. Diamond-Like Carbon Coatings: Technologies and Applications examines emerging manufacturing technologies for DLCs with the aim of improving their properties for use in practical applications. Discusses DLC coatings used in mechanical, manufacturing, and medical applications Details recent developments in the novel synthesis of DLC films Covers advances in understanding of chemical, structural, physical, mechanical, and tribological properties for modern material processing Highlights methods to yield longer service life Considers prospects for future applications of emerging DLC technologies This work is aimed at materials science and engineering researchers, advanced students, and industry professionals.

We observe unexpected wear increase on a steel surface that rubbed against diamond-like carbon (DLC) coatings only when lubricated by phosphate-based antiwear additives. Contrary to the literature hypothesis of a competition between zinc dialkyldithiophosphate produced tribofilms and DLC-induced carbon transfer, here a new wear mechanism based on carbon-catalyzed tribochemical interactions supported by surface characterization is proposed.

This Ph.D. thesis studies individual and synergistic contributions of the Anti-Wear (Zinc dialkyldithiophosphate, ZDDP), Friction-Modifier (Glycerol isostearate, GIS) and Automotive additive package to the friction of the steel and DLC contacts across a broad range of boundary-lubrication contact conditions. A design-of-experiments was used to enable broad-range experimental matrix and Elastic-net regression technique was used to develop friction models and friction maps depending on the most relevant contact parameters, namely pressure, roughness, speed, and temperature. Moreover, obtained models are based on the experimental parameters and their interactions whose statistical significance has been undoubtedly proven. The major conclusion is that statistically identified interactions of the experimental parameters show which of the parameters interfere and compete in their influence on the coefficient of friction, hence, which of the investigated parameters must be simultaneously considered if proper conclusions are to be made. What is more, it is shown that single parameter investigations of the boundary lubrication regime do not reveal true properties of the contact/lubricant combination in the whole range of the boundary lubrication regime.

Elasto-Hydrodynamic Lubrication deals with the mechanism of elasto-hydrodynamic lubrication, that is, the lubrication regime in operation over the small areas where machine components are in nominal point or line contact. The lubrication of rigid contacts is discussed, along with the effects of high pressure on the lubricant and bounding solids. The governing equations for the solution of elasto-hydrodynamic problems are presented. Comprised of 13 chapters, this volume begins with an overview of elasto-hydrodynamic lubrication and representation of contacts by cylinders, followed by a discussion on equations relevant to lubrication, including the Reynolds equation. The reader is then introduced to lubrication of rigid cylinders; the importance of film thickness in highly loaded rigid contacts; the elasticity of solids in contact; and the theory of elasto-hydrodynamic lubrication. Subsequent chapters focus on apparatus and measurements of film thickness and film shape; friction and viscosity; and lubrication of gears and roller bearings. This book will be of interest to tribologists.