DEVELOPMENT OF METHODS FOR SURFACE HARDENING OF HARD ALLOY VK10KS

The results of studies of the VK10KS hard alloy after various surface treatments (using concentrated energy flows) are presented. The TiN + ZrN ion-plasma coating from separate titanium and zirconium cathodes was applied using the Kvant-6 installation. The zirconium alloy cathode was located in a chamber between two titanium alloy cathodes. Metallographically, after applying an ion-plasma coating of TiN + ZrN composition, a poorly etched layer with a thickness of 15 microns consisting of microlayers was revealed. The two phases (TiN and ZrN) found in the diffractograms in the coating confirm the micro-thickness of its structure, which will help to increase the adhesion of the coating itself with a carbide base. The boundary between the micro-layers of the coating will inhibit the growth of the crack. It was found that the introduction of zirconium TiN compound into the coating leads to an increase in nanohardness by 23% (up to 39 GPa). Electric spark treatment was carried out on the UR – 121 installation. It consists of erosion of the hardening electrode during spark discharge. At the same time, the erosion products are transferred to the part. A hard alloy VK6-OHM was used as the electrode. X-ray phase analysis revealed the presence on the surface of the hard alloy VK10KS of a newly formed phase with high hardness (divolfram carbide W₂C), which has a hardness greater than that of tungsten monocarbide WC. Nanoindentation of the VK10KS alloy after electric spark treatment showed an increase in surface hardness up to 22 GPa. A hardened surface layer consisting of titanium diboride TiB₂, carbides TiC, W2C with a nanohardness of 28 GPa was obtained by electroexplosive alloying (EVL) with titanium and boron on a hard alloy VK10KS. The essence of EVL is the accumulation of energy by a battery of pulse capacitors up to 10 kJ and its subsequent discharge within 100 microseconds through a conductor that experiences explosive destruction. At the same time, the treated surface is heated and saturated with explosion products, followed by self-quenching due to heat removal into the environment and deep into the material.

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