Study of the properties of coatings formed from nanostructured composite powders of the Ti/TiO2 system by microplasma spraying

With increasing operating speeds and contact loads of structural elements, it is necessary to increase the operational life of friction units, which can be ensured by improving the physical and mechanical properties of the contact surfaces. The paper presents the results of investigations of the properties of coatings formed from nanostructured composite powders of the Ti/TiO 2 system by microplasma spraying. Experimental data on the synthesis of nanostructured powders based on a titanium matrix reinforced with titanium dioxide nanopowders are presented. PTOM-1 titanium powder with a fraction of less than 90 μm and nanoscale titanium dioxide powder with a fraction of 80 – 200 nm were used as starting materials. Mixtures of starting materials with variable TiO 2 content were subjected to preliminary homogenization and subsequent mechanosynthesis. When studying the morphology of the synthesized powders, it was revealed that the shape of the particles is inherited from the matrix powder, and with an increase in the content of the reinforcing component, the surface of the composite powder is more densely reinforced with particles of TiO 2 nanopowder. The determination of the fractional composition showed that the maximum volume fraction of particles (62. 5 % wt.) it corresponds to a size of 10 – 40 μm. Scanning electron microscopy of transverse microspheres revealed that there are no through pores in all coatings. With an increase in the titanium dioxide content to 24 %, porosity increases significantly, and there is also a detachment of the coating material from the substrate. A study of the microhardness of the sprayed coatings showed that the hardest coating (on average 985 HV ) was obtained by spraying a synthesized powder with a titanium dioxide content of 16 % by weight. The results obtained can be used to extend the life of, for example, titanium alloy ball valves used in autoclaves for the mining industry.