Wear resistance of spark-deposited TiN, TiB2, and Mo coatings on 30KhGSA steel after exposure to focused solar radiation

Abstract

UDC 621.9.048The use of focused solar radiation to improve the mechanical properties of spark-deposited TiN, TiB 2 , and Mo coatings is studied. It is shown that the tribotechnical characteristics of sparkdeposited coatings improve after exposure to focused solar radiation over steel coatings after thermal treatment. Solar treatment of 30KhGSA steel leads to its strengthening-hardening with fine-grained annealed martensite being formed.The improvement in the tribotechnical properties of structural steel parts is important technically and economically. In aviation, the tribotechnical properties of 30KhGSA steel are improved mainly by placing a galvanic chromium coating over it. This method is advantageous as it provides high wear resistance, low friction coefficient, and corrosion resistance of the coating [1]. However, it is disadvantageous as the coating process is environmentally harmful, decreases fatigue characteristics, takes much time, and is expensive.Hence, electrospark alloying (ESA) needs to be used to improve the surface behavior of 30KhGSA steel. It is mainly intended to make an alloyed layer to be strongly bonded to the substrate. Equipment for ESA is simple and easy to operate. However, nonuniform rough coatings are one of its drawbacks (because of discrete discharge pulses) [2]. To improve the physical and technical properties of spark-deposited coatings (roughness, porosity), focused solar radiation (FSR) should be used [3]. For obtaining wear-resistant coatings, TiN and TiB 2 are promising materials. To decrease the brittleness of electrodes from these materials, Cr, Ni, Mo, and Al 2 O 3 additions are introduced [3].The objective of this paper is to study the use of FSR to improve the mechanical properties of sparkdeposited coatings.We examined the structure and properties of spark-deposited TiN-(Cr, Ni), TiN-(Ni, Mo), and TiB 2 -(Ni, Mo) coatings on 30KhGSA steel. All materials contained Al 2 O 3 . An EFI-46A unit was used for ESA at I = 1.5 A and C = 300 μF; the tribotechnical characteristics were determined using an MT-68 friction test machine in air at a sliding speed of V = 10 m/sec and a load of P = 0.5 MPa. We used 65G steel (HRC 50) as a counterface. An SGU-2