When material surfaces are in mechanical contact and slide against each other, complex microscopic interactions occur between the surfaces that lead to friction and wear. Factors that affect friction behaviors include a component or part’s materials, the topographical characteristics of the surfaces, and the surrounding conditions, such as temperature, atmosphere, and chemical and biological environment. Friction is a popular field of study across many different industries, ranging from aerospace and automotive systems to medical implants and devices. Typical areas of friction studies include:

In the United States, the direct and consequential economic loss due to friction and wear is estimated to be approximately 1% to 2% of the annual GDP. For example, in the automotive industry, friction between moving components can result in energy loss and reduced fuel efficiency. Roughly 10% of energy consumption in an automobile is caused by friction. The reduction of friction in engineered materials and surfaces of automotive components has been reported to improve fuel efficiency by 3% to 5%. Friction is also widely studied in the medical implants and devices industry, as the friction and wear of implant materials and devices in a human body can cause inflammation or even toxicity through the generation of wear debris. For instance, the US Food and Drug Administration (FDA) issued a special safety letter on Nov. 23, 2015, cautioning manufacturers on the issues with friction-reducing coatings on medical wires after examining 11 product recalls and 500 adverse event reports that included nine deaths. The FDA said in some cases slippery coatings flaked off due to friction and clogged the flow of blood.