David W. Johnson is the Chair of the Chemistry Department at the University of Dayton. He received a Ph.D in chemistry at Illinois Institute of Technology in 1983, completing his research in inorganic chemistry. He has been on the faculty at the University of Dayton teaching primarily analytical chemistry since 1984. He has led an active research program focused on the chemistry of lubricants, lubricant additives and lubricated surfaces in aerospace and refrigeration applications.
Tribology is an interdisciplinary area that studies the reduction of friction between moving parts combining chemistry, physics and engineering disciplines. Lubricants are typically substances used to reduce friction. This book contains two sections: the first section examines the chemistry of lubricants and additives, while the second section looks at the lubrication of different types of materials.
Go to the bookPart of the book: Current Issues and Future Direction in Kidney Transplantation
The lubricant systems used in turbine engine applications are discussed with respect to the particular problems associated with aircraft applications. After initially describing the relevant specifications, the typical basestocks are described along with some common degradation schemes. The additive systems, including antioxidants, anti-foaming agents, and anti-wear additives needed to achieve the typical specifications, are described along with their mechanism of action and degradation mechanisms. The methods used for the monitoring of lubricant health, including in-line and offline methods, are also discussed. Finally, future changes in specifications, basestocks, and additives are discussed with respect to new, high-performance bearing materials.
Part of the book: Recent Progress in Some Aircraft Technologies
Phosphate esters, thiophosphate esters and metal thiophosphates have been used as lubricant additives for over 50 years. Recently, phosphorus‐containing ionic liquids have emerged as a new class of lubricant additives. While the use of phosphorus compounds has been extensive, a detailed knowledge of how they work has been a much more recent development. In this chapter, the use of phosphate esters, thiophosphate esters, metal thiophosphates and phosphorus‐containing ionic liquids as antiwear or extreme pressure additives is discussed. The primary emphasis will be on how they form a protective film, which is both durable and reduces friction. The first part of the chapter discusses the use of alkyl phosphates, triaryl phosphates and metal‐containing thiophosphate esters with primarily iron‐ and steel‐based bearing materials. The second part of the chapter examines phosphorus‐containing ionic liquids and the challenges posed by new bearing materials with different surface chemistries.
Part of the book: Advances in Tribology
The application of mass spectrometric techniques for the analysis of the complex mixtures inherent in fuel and lubricant samples will be examined. These samples because they are naturally complex mixtures, typically requires either very high resolution mass spectrometry or one of the hyphenated techniques gas chromatography‐mass spectrometry(GC‐MS) or liquid chromatography‐mass spectrometry (LC‐MS). Some fuel problems that can be addressed through mass spectrometry are associated with the changes in composition and degradation of fuels as they age, including the analysis of both major hydrocarbon components non‐polar components and minor polar components will be described. The properties and composition of natural and major classes of synthetic lubricants, the presence of additives and the problems that develop as the lubricant is used such as additive depletion, thermal and oxidative degradation and lubricant contamination have also been examined using mass spectrometric techniques.
Part of the book: Mass Spectrometry
Modern aviation requires reliable and safe sources of fuel which means fuel is frequently stored for extended periods. In addition, as fuel is used, new fuel is added which is not always compatible with the fuel in the tank. The incompatibility and long-term storage leads to a number of problems that will be addressed in this chapter. Some of the possible changes over time include formation of biofilms, deposit formation, water incorporation and additive depletion. The chemistry and biochemistry of each of these areas will be discussed along with how they might be prevented. New areas of research on low temperature oxidation of trace fuel components and the prevention of bacterial growth will be presented. Other problems are related to the reaction of trace components in the fuel which can lead to oxidation and deposit formation. Trace components also vary based on fuel source and lead to problems in compatibility of different fuels. In addition some of the reactions of fuel additives will be discussed.
Part of the book: Flight Physics
Modern ester based synthetic lubricants have been used in various formulations with anti-oxidants, phosphorus based anti-wear additives and other additives for many years. The physical and chemical properties of both the basestock and additives are known to change through use. Basestocks are normally thought to degrade through various mechanisms, while additive can either degrade or are used as they react when they complete the function that they are added for. In this chapter, the composition of modern turbine engine lubricants and the mechanisms by which the lubricants degrade over time will be examined. Potential changes in bearing materials being evaluated for future engines and the effects of possible new ionic liquids based additives will be will be discussed as they relate to currently used additives. Also included will be a discussion of effects of degradation on the lubricant properties, how the changes affect turbine engines and how the changes can impact human health. These new materials introduce a number of new possible degradation schemes that must be evaluated before the materials enter wide-spread use.
Part of the book: Aerospace Engineering