Nanocomposites and nanomaterials 

Improvement of wear resistance of materials for electric vehicles pantographs
Prikhna T.O.1, Podhurska V.Ya.2, Ostash O.P.2, Vasyliv B.D.2, Sverdun V.B.1, Karpets M.V.1, Serbeniuk T.B.1
1 Department of sintering technologies of ceramics, Institute for Superhard Materials of the NAS of Ukraine, 2 Avtozavodska str., Kyiv 04074, Ukraine. 

2 Department of Structural Fracture Mechanics of Materials, Karpenko Physico-Mechanical Institute of the NAS of Ukraine, 5 Naukova str., Lviv 79060, Ukraine.
E-mail: podhurskavika@gmail.com

In order to increase the durability and lifetime of the current collector of the trams, instead of the conventional pantograph materials, composites based on MAX-phase are proposed. Titanium aluminum carbide (Ti3AlC2), as one of the newly emerging MAX ternary compounds (Mn+1AXn, where M = early transition metal, A = group IIIA or IVA element, and X = C and/or N, n = 1–3), possesses the excellent performance of both metallic and ceramic characteristics, which has easy machining properties and good thermoconductivity, excellent oxidation resistance and thermal stability at high temperatures [1], and its electrical conductivity is roughly two orders of magnitude higher than that of graphite [2]. The Ti3AlC2 nano-laminates can easily shear over other materials and form a film on the Ti3AlC2 tribosurface owing to the hexagonal close packing structure of the MAX phases.
The wear of copper is significantly reduced when the composites based on Ti3AlC2 has a porous structure (obtained due to the reduction of the pressure of hot pressing from 30 to 15 MPa), as well as its saturation with a solution of glycerin. The glycerin film on the contact surface with copper increases the wear resistance of the copper counterbody in 6 times compared to the non-impregnated version (without glycerin) and, in 50 times, as compared with tribological pair aluminum alloy - copper, which simulates the interaction of the electrical contact of pantograph with wire of the catenary system used in Ukraine

1.	Radovich M., Barsoum M.W. MAX phases: bridging the gap between metals and ceramics // Amer. Ceram. Soc. Bull. – 2013. – 92, №3. – Р. 20–27.
2.	Ivasyshyn A., Ostash O., Prikhna T., Podhurska V., Basyuk T. Oxidation resistance of materials based on Ti3AlC2 nanolaminate at 600°C in air // Nanoscale Research Letters. 2016, 11: 358. DOI:10.1186/s11671-016-1571-x.