1. Nanotribology: definition and objectives

A tribological system consists of two contacting surfaces in relative motion. These two elements are usually referred to as first bodies. They can be similar, like cartilage-covered bones in joints, or different, like a pen rubbing against paper, or an eyelid sliding over a contact lens. The two surfaces in contact are separated by an interface generally referred to as the third body. This is the sliding region between the objects in contact, and the one that can undergo physico-chemical modifications compared to solid objects. It may be a liquid lubricant (tears or synovial fluid in joints) or a solid one (graphite, Teflon or molybdenum disulfide) added to facilitate sliding. The interface can also consist of wear particles or a transfer film deposited on the surfaces. The third body can reduce...