Effect of Magnetic Field on Structure of Copper-Containing Polymer Composites for Stationary Friction Units A. G. Anisovich1), S. N. Bukharov2), V. K. Merinov2), V. P. Sergienko2)

. The effect of preliminary treatment with a pulsed magnetic field on a composite mixture of powders (polytetrafluoroethylene, stabilized copper powder, basalt fiber, dispersed inorganic friction additive) for obtaining pressed polymer friction materials is investigated. An experimental device IMI-I was used for processing. The magnetic field strength, number of pul-ses and their polarity were varied. The change in the surface structure of a composite material after pressing, cutting, as well as the surface after friction tests was studied using the method of optical microscopy. A significant effect of the magnetic field on the structure of the samples was found. The homogeneity of the free surface increases, porosity decreases, the morphology changes significantly and the ability of phase visualization increases. A change in the cut surface formed by the tool when cutting a ring blank into individual samples is noted. Treatment in a magnetic field leads to the formation of a less developed surface relief; the effect is intensified with an increase in the number of pulses from two to four, as well as with an increase in the field strength. The morphology of the friction surface changes significantly: the treatment helps to reduce the differences between the peripheral region and the center of the sample. Transfer films are formed much less intensively. The polymer phase does not demonstrate the presence of viscous areas. The phase composition and change in static displacements of atoms from equilibrium positions were studied by X-ray structural analysis. It was found that the phase composition of the material does not change under the influence of magnetic treatment. It is shown that preliminary treatment of the composite mixture with a magnetic field affects the static displacements of atoms from equilibrium positions in the copper phase. Treatment in a magnetic field helps to form an equilibrium structure of copper due to improvement of the crystal lattice. It was found that the effect of exposure depends to the greatest extent on the number of pulses and their polarity. The use of a unipolar pulse is the most effective.