O’zbekistоn respublikasi оliy va o’rta maxsus ta`lim vazirligi

Lecture number 14.
Materials science in tribology.
The actual direction of increasing wear resistance is the creation and use of special tribotechnical materials in friction pairs. tribology adhesion electrification friction
19.1 Basic terms
Materials science is a science that studies the relationship between the structure and properties of materials, as well as their changes under external influences (thermal, mechanical, chemical, etc.). The task of tribological materials science is to find the optimal structure of materials from the point of view of tribology and technologies for processing friction surfaces in the manufacture and operation of friction pairs. The main provisions of tribological materials science are briefly outlined below.
The object of tribological materials science is two large classes of materials: friction and antifriction.
In most modern machines, friction plays a negative role, creating resistance to movement, to overcome which work must be done. One of the ways to combat friction is the creation of antifriction materials - materials with low values of the coefficient of friction.
At the same time, there are machines and mechanisms whose operating principle is based on the use of friction: brakes, friction gears, fastening devices, etc. In them, the working surfaces of the parts are lined with friction materials , which are characterized by an increased friction coefficient. A typical friction material is the material used for shoe soles.
It is customary to call friction materials with a friction coefficient f 0.2 and antifriction materials with f 0.2. There is a small group of materials that are used both as friction and anti-friction materials in different units of machines (Fig. 14.1). All tribological materials must be wear-resistant in order to provide an acceptable technical resource of friction pairs.
Over the past decades, the operating speeds and loads in machines have sharply increased, and the modes of operation of friction pairs have become tougher. In many cases, the traditional tribotechnical materials (cast iron, babbitt, bronze, etc.) that have been tested for centuries have turned out to be unsuitable for work in harsh conditions. There is a need for a new generation of tribological materials based on ceramics, metals and polymers, capable of operating under extreme loads, temperatures, vacuum, irradiation, etc.