INTERATOMIC INTERACTIONS ON THE SURFACES OF METAL-POLYMER TRIBOCOUPLING

Tribology, which originated as the science of processes in macroscopic objects, thanks to advances in quantum chemistry and the development of experimental physics of X-ray photoelectron and Auger electron spectroscopy (XPS and AES), should now extend studies to micro- and nanolevels. It is necessary to examine in more detail interatomic interactions on the friction surfaces of both antifriction and friction couplings.

The objective of the article is to present the results of studies of segregation phenomena of alloying and impurity elements in the tribosystem «wheel-brake shoes», based on finite-element method, X-ray photoelectron and Auger spectroscopy, modelling, mathematical computations and simulation.

Considering regularities of the impact of temperature and thermal gradient on tribomechanical, triboelectric and tribochemical processes within the contact area of «polymer – metal», generalized recommendations on the selection of filling and strengthening elements became available.

For anti-friction composite polymeric materials the main criterion of minimizing the coefficient of friction and high wear resistance is the ability to spontaneously form on the friction surface a bilayer film that combines lubricating properties and high adhesion due to bipolar tribocharging of its composites.

For friction materials the main criterion to avoid increased wear and transfer of metal on the conjugate plastic surface is the reduction of the degree of hydrogenation of the metal counterface by establishing the optimum temperature gradient and positive tribocharging.

The solution of related non-stationary thermoelastic problem of brake disc-pad showed that the maximum temperature within all the thickness of the disk is located not on the surface but at depth. It was established experimentally that the maximum concentration of hydrogen in the disc coincides with the maximum temperature.

The binding energy of atoms of different elements to the surface of the grain is a periodic function of the atomic numbers of the elements. This may serve as a theoretical basis for predicting the strength properties of steel with a different composition of alloying and impurity elements.

The obtained results indicate the promising application of XPS, AES and quantum chemistry in solving tribological tasks.

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