The influence of electric and thermal currents on the behavior of hydrogen in friction pairs

Abstract

Studies have shown that the main influence in brake friction pairs on the behavior of hydrogen is pulsed: specific loads, electric and thermal currents, as well as their gradients. With the growth of impulse specific loads, the electrical conductivity of the contact increases relatively quickly, which increases the thermal effect, but when the load is smoothly reset, it decreases much more slowly and does not coincide with the initial values. The magnitude and direction of the integral e.m.f depends on the physical and mechanical properties of the metals of the friction pair, on the speed and load modes of friction, and on many other factors that cause significant fluctuations and even inversion of this parameter. The effect of thermal current on the wear resistance of parts of friction pairs is related to the peculiarities of the course of relaxation, oxidation, diffusion and other processes that affect each other. Oxide films on the surface of contacting metals have semiconducting properties and high resistivity and can play the role of amplifiers of thermoelectric effects, which can cause the appearance of fairly significant eddy currents in the places of the greatest convergence of contact points and, due to the low thermal conductivity of oxides, contribute to localized discharge. Impulsive high-frequency mechanical oscillations in the friction zone are inseparable from thermoelectric relaxation processes, and these factors always jointly affect the spread of experimental values of wear resistance of parts.