STRUCTURE, MECHANICAL AND TRIBOLOGICAL PROPERTIES OF TI-CR-C-NI-FE COMPOSITE COATINGS

Abstract

Here we discuss the use of composite cermet SHS electrodes from materials based on titanium carbide, chromium carbide, and nichrome obtained by SHS extrusion for the electrospark deposition of Ti-Cr-C-Ni-Fe composite coatings on metal substrates made of high-speed steel R6M5. Four electrospark alloying modes are considered which correspond to electric discharge energies of 0.2, 0.3, 0.6, and 1.0 J. The plotted experimental curves of the total anode erosion and the total cathode weight gain on the alloying time have a classical form. The effect of the electrospark alloying modes on the structure, mechanical (hardness) and tribological properties of the obtained composite coatings is studied. It is shown that the coating consists mainly of a matrix based on two Cr-Ni-Fe-Csolid and Fe0.7Ni0.3 phases and reinforcement complex carbide Ti0.8Cr0.2C particles, the size of which decreases to less than 100 nm with proximity to the substrate. The hardness of the resulting composite coatings is 10.6-13.5 GPa. The major fraction of carbide particles in the SHS electrode melts during electrospark alloying, and with increasing discharge energy the number of transferred grains in the solid phase increases by a factor of up to 9. Depending on the discharge energy of electrospark alloying, we determine the transfer coefficients of the SHS electrode, the run-in areas of the resulting coatings, and the amount of wear of the coating and counterbody.