Tribology

Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear. Tribology is highly interdisciplinary. It draws on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. People who work in the field of tribology are referred to as tribologists. Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear. Tribology is highly interdisciplinary. It draws on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. People who work in the field of tribology are referred to as tribologists. The word tribology derives from the Greek root τριβ- of the verb τρίβω, tribo, 'I rub' in classic Greek, and the suffix -logy from -λογία, -logia 'study of', 'knowledge of'. Peter Jost coined the word in 1966, in the eponymous report which highlighted the cost of friction, wear and corrosion to the UK economy. Despite the relatively recent naming of the field of tribology, quantitative studies of friction can be traced as far back as 1493, when Leonardo da Vinci first noted the two fundamental ‘laws’ of friction. According to da Vinci, frictional resistance was the same for two different objects of the same weight but making contact over different widths and lengths. He also observed that the force needed to overcome friction doubles as weight doubles. However, da Vinci's findings remained unpublished in his notebooks. The two fundamental ‘laws’ of friction were first published (in 1699) by Guillaume Amontons, with whose name they are now usually associated, they state that: Although not universally applicable, these simple statements hold for a surprisingly wide range of systems. These laws were further developed by Charles-Augustin de Coulomb (in 1785), who noticed that static friction force may depend on the contact time and sliding (kinetic) friction may depend on sliding velocity, normal force and contact area. In 1798, Charles Hatchett and Henry Cavendish carried out the first reliable test on frictional wear. In a study commissioned by the Privy Council of the UK, they used a simple reciprocating machine to evaluate the wear rate of gold coins. They found that coins with grit between them wore at a faster rate compared to self-mated coins. In 1860, Theodor Reye proposed Reye's hypothesis . In 1953, John Frederick Archard developed the Archard equation which describes sliding wear and is based on the theory of asperity contact. Other pioneers of tribology research are Australian physicist Frank Philip Bowden and British physicist David Tabor, both of Cavendish Laboratory. Together they wrote the seminal textbook The Friction and Lubrication of Solids (Part I originally published in 1950 and Part II in 1964). Michael J. Neale was another leader in the field during the mid-to-late 1900's. He specialized in solving problems in machine design by applying his knowledge of tribology. Neale was respected as an educator with a gift for integrating theoretical work with his own practical experience to produce easy-to-understand design guides. The Tribology Handbook, which he first edited in 1973 and updated in 1995, is still used around the world and forms the basis of numerous training courses for engineering designers. Duncan Dowson surveyed the history of tribology in his 1997 book History of Tribology (2nd edition). This covers developments from prehistory, through early civilizations (Mesopotamia, ancient Egypt) and highlights the key developments up to the end of the twentieth century. The term tribology became widely used following The Jost Report published in 1966. The report highlighted the huge cost of friction, wear and corrosion to the UK economy (1.1-1.4% of GDP). As a result, the UK government established several national centres to address tribological problems. Since then the term has diffused into the international community, with many specialists now identifying as 'tribologists'.