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ISSN 2664-2441 (Online)
ISSN 2073-9583 (Print)

Influence of activator on the structure and properties of chromium-alloyed titanium alloy VT6

Metalozn. obrobka met., 2022, vol. 28 (102), 52-57
https://doi.org/10.15407/mom2022.02.052

Loskutova T.V., Doctor of Technical Science, Associate Professor, losktv@ukr.net, ORCID: https://orcid.org/0000-0002-1894-8321
Pogrebova I.S., Doctor of Technical Science, Professor, ORCID: https://orcid.org/0000-0003-4247-3968
Kononenko Ya.A., Postgraduate
Kotlyar S.M., Candidate of Technical Science (Ph.D.), Associate Professor, s.kotlyar@kpi.ua, ORCID: https://orcid.org/0000-0002-8934-4189

National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine

УДК 621.785
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Summary

The influence of the amount of halogen-containing activator on the structure, composition and properties of diffusion layers, which are formed during the complex saturation of the titanium alloy VT6 with chromium and aluminum, is investigated. The coating was applied by powder method in chlorine under reduced pressure, at a temperature of 850 ° C for 4 hours in a saturating mixture consisting of powders of saturating metals (chromium, aluminum), inert backfill Al2O3 and activator. As the activator used NH4Cl, the amount of which varied in the range from 3 to 9 % of the mass. The optimal amount of activator in the saturating mixture is determined. The microstructure, chemical composition, thickness and microhardness of the obtained diffusion coatings were studied. It was found that when using 3% NH4Cl, the obtained coatings consist of three layers, dark gray, which are completely located on the surface and correspond to the phases based on TiAl, intermetallic with (Ti, V, Cr, Al) and Ti3Al. A transition zone based on α-Ti is formed directly under the coating. The microhardness of the obtained layers is quite high and is 5.1-9.6 GPa, the total thickness is 46.0-48.0 μm. Reducing the amount of activator leads to the formation of discontinuous surface layers of the coating, which will lead to differences in the properties of its surface layers. Increase - to the destruction of the surface layers of the coating and equipment directly during the chemical-thermal treatment.
Keywords: chromium, aluminum, titanium alloy, activator, diffusion coatings.

References

  1. Borisenok G. V., Vasilyev L. A., Voroshnin L. G. i dr. Khimiko – termicheskaya obrabotka metallov i splavov. Spravochnik (Chemical and heat treatment of metals and alloys. Handbook), Moscow: Metallurgiya, 1981, 424 p. [in Russian].
  2. Lakhtin Yu. M., Arzamasov Yu. M. Khimiko – termicheskaya obrabotka metallov (Chemical and heat treatment of metals), Moscow: Metallurgiya, 1985. – 256 p. [in Russian].
  3. Pokhmurskiy V. I., Dalisov V. B., Golubets V. M. Povysheniye dolgovechnosti detaley mashin s pomoshch'yu diffuzionnykh pokrytiy (Improving the durability of machine parts using diffusion coatings),  Kyiv: Naukova dumka, 1980, 188 p. [in Russian].
  4. Loskutov V.F., Khizhnyak V.G., Kunitskiy Yu.A. Diffuzionnyye karbidnyye pokrytiya (Diffusion Carbide Coatings), Kyiv: Tekhnika,1991, 168p. [in Russian].
  5. Lyakisheva N. P. Diagrammy sostoyaniya dvoynykh metallicheskikh sistem: sprav. in 3 T. (Diagrams of the state of binary metallic systems), Moscow: Mashinostroyeniye, 1997, Vol. 2, 676 p. [in Russian].
  6. Hwan Gyo Jung, Dong Ju Jung, Kyoo Young Kim, Surface and Coatings Technology, 2002, Vol. 154, pp. 75–81. [in English] https://doi.org/10.1016/S0257-8972(01)01716-9