TITANIUM-DOPED POWDER COATINGS WITH A TiN LAYER ON 9KhS STEEL AND VK8 HARDMETAL SUBSTRATES

V.G.Khizhnyak,
 
T.V.Loskutova*,
 
G.Yu.Kalashnikov,
 
I.S.Pogrebova,
 
O.I.Dudka
 

National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, 37, Prosp. Peremohy, Kiev, 03056, Ukraine
losktv@bigmir.net
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2020, #09/10
http://www.materials.kiev.ua/article/3132

Abstract

The phase and chemical compositions, structure, and properties of titanium-doped coatings with a TiN layer on 9KhS steel and VK8 hardmetal substrates were studied. A TiN layer 5.0–5.5 μm thick was applied by the physical vapor deposition method. The alloys were doped with titanium in fusible containers in a mixture of powders consisting (wt.%) of 40.0 Ті, 5.0 Al, 5.0 Al2О3, and 5 NH4Cl at 1050 °C for 4 h. Multilayer coatings including Al2О3, 2Ti4O, TiC, and TiN formed on the 9KhS substrate and Al2О3, TiAlСO2, TiC, and TiN on the hardmetal substrate. The TiN layer completely inhibited the penetration of aluminum into the 9KhS substrate and of aluminum and oxygen into the VK8 hardmetal substrate. The coating on 9KhS steel had no Feα(Al) layer, and the coating on VK8 hardmetal had no area containing aluminum and oxygen. Individual layers in the coatings exhibited high microhardness: 35.6 GPa for the TiC layer on 9KhS steel, 29.0 GPa for the TiC layer on VK8 hardmetal, and 23.4–23.6 GPa for the TiN layer on both substrates. The cross-sectional structure of the coatings was virtually porousless, showing good adhesion between the individual layers and substrate, being characteristic of diffusion-hardened coatings. The wear resistance of the coated 8KhS steel was 6.9 times higher than that of the uncoated steel in dry sliding friction conditions. The coated 9KhS steel showed an extreme dependence of the wear on the sliding velocity. The mechanically fastened multifaceted hardmetal cutting tools with coatings demonstrated 8.3 times higher resistance than the uncoated tools tested by 40Kh13 steel cutting. The coatings developed can substantially increase the performance of 9KhS steel and VK8 hardmetal tools.


9KHS STEEL, BARRIER LAYER, COATINGS, HARDMETAL CUTTING TOOLS, MICROHARDNESS, TITANOALUMINIZING, WEAR RESISTANCE