Physico-Technological Aspects of Work of Lubricant Films in the Tribosystem "Overhead Line – Current Collector Contact Strip"

Abstract

Purpose. The article aimed at comprehensive analysis of the processes occurring in the lubricant films of the friction surfaces of the tribosystem «overhead line -current collector contact strip» (OLCCCS) and identification of the features of such systems. Methodology. The systematic analysis was used as the main methodology for studying the physico-technological aspects of work of the lubricant films in the tribosystem «overhead line -current collector contact strip». Findings. The theory of electro-friction interaction is now at such a stage that is characterized by a large amount of accumulated empirical data, hypotheses and models that cannot adequately represent phenomena in a sliding, high-current electrical contact. The sliding electrical contact of the tribosystem «overhead line -current collector contact strip» during the operation is affected by many factors, one of which is the processes in the lubricating layers of the friction pair. The work leads to a new level of understanding of the peculiarities of the processes occurring in the lubricating layers and their effect on the work of a sliding, high-current electrical contact, which can become the guarantee of significant increase in the efficiency of such systems and, as a consequence, substantially increase the reliability and safety of the work of the electric stock. Originality. It is proposed to consider the processes of electro-friction interaction of electrical contacts from the position of synergy using the theory of fractals as the core one for the quantitative description of self-organizing structures. Practical value. Taking into account the empirical experience of operation of the tribosystem «overhead line -current collector contact strip» in combination with theoretical knowledge allows us to propose three possible directions for solving tribological problems in highcurrent sliding electrical contacts. They are: 1) change in contact geometry and surface topography, for example, the use of regular macrorelief of contact surfaces; 2) development of conductive composites which are characterised with self-lubrication, for example the use of composite materials containing solid conductive lubricants; 3) development of effective lubricants for electric high-current sliding contacts, which may require some complication of the component design.

Nanostructures in the Formation of the Properties of High-Current Sliding Electrical Contacts on the Electric Rolling Stock

“…But it is difficult to use the value of current density to predict the contact wear rate due to the diversity of current factors and the complex nature of their interaction with each other. Among the main factors of wear in the absence of electric sparking and arcing: oxidation of the metal element of a friction pair; oxidation of the composite element of a friction pair and weakening of its strength; increase in adhesion due to dissociation of water films or organic substances under the action of electric current; the occurrence of shock thermal stresses in dynamic contact through the uneven distribution of current density in it, a high coefficient of friction in the contact zone [8,9,10]. All factors can act simultaneously and their main cause is heat dissipation on the transitional contact resistance.…”