Siberian State Industrial University (Russian: Сибирский государственный индустриальный университет, abbreviated СибГИУ) is the oldest university in Novokuznetsk, Russia. It was established on June 23, 1930, to train professional personnel for the construction of the Kuznetsk Metallurgical Combine (Novokuznetsk Iron and Steel Plant). Prior to raising the status in 1994, it was named the Siberian Metallurgic Institute (SMI), then it was renamed the Siberian State Mining-Metallurgic Academy (SibGGMA). In 1998, the status of the university had risen to the level of the Technical University and it received the title of Siberian State Industrial University (SibSIU). The university is located in the central district of Novokuznetsk.Siberian State Industrial University has about 15,000 undergraduate, graduate, and doctoral students, and a faculty of about 1200, including 326 professors and 350 associate professors.
TiB2–Ag coatings are deposited by electroexplosive spraying on a copper surface for the first time. The idea of creating such coatings is based on the high properties of the initial materials used to form the coatings, namely, titanium diboride and silver. Silver is used to create a matrix with a high electrical conductivity, and titanium diboride, in turn, serves as a wear-resistant, hard, electroerosion-resistant filler for the matrix. Moreover, titanium diboride has a high electrical conductivity among other similar fillers, such as tungsten and molybdenum. The essence of the work is that TiB2–Ag coatings are deposited onto a copper target–substrate by electroexplosive spraying. Electroexplosive spraying is carried out using a silver foil and a titanium diboride powder under the conditions that ensure melting of the copper target–substrate. The deposited coatings are intended for use in electrical contact switching devices. Therefore, we study the following minimum basic properties necessary for the stable operation of electrical contacts in switching devices: microhardness, nanohardness, Young’s modulus, wear coefficient, friction coefficient, electrical conductivity, and switching wear resistance. The following main results have been obtained. The electrical conductivity of the TiB2–Ag coating is 62.0 MS/m. The coating withstands 7000 switching cycles during accelerated electroerosion resistance tests. The electrical resistance does not exceed 12.82 μΩ. The Vickers microhardness in the silver matrix of the coating is 0.251–0.265 GPa, and that at titanium diboride inclusions is 25–32 GPa. The nanohardness is H = 4.48 ± 0.76 GPa and Young’s modulus is E = 116 ± 29 GPa. Under dry sliding friction conditions, the wear parameter is 1.2 mm3/(N m) and the friction coefficient is 0.5. X-ray diffraction analysis demonstrates that the coating contains silver (a = 4.0779 Å, CSR = 42) and titanium diboride (a = 3.0535 Å, c = 3.2618 Å, CSR = 38). Scanning electron microscopy demonstrates that the coating 100–110 μm thick has a composite filled structure, which consists of a silver matrix with titanium diboride inclusions 1–20 μm in size. Transmission electron microscopy demonstrates that the main phase of the coating is silver or an Ag + Cu solid solution reinforced with titanium diboride nanoparticles.
The formation of micro- and nanostructures in titanium alloys subjected to combined processing, which includes exposure to heterogeneous plasma flows and subsequent surface modification by a low-energy high-current electron beam has been studied. The main mechanism of the formation of micro- and nanoscale structural-phase states under the action of plasma flows created by an electrical explosion of conductors is found to be a joint effect of the Kelvin–Helmholtz and Rayleigh–Taylor instabilities at the interface. The perturbation growth rate at an acceleration g = 5 × 109 m/s2 of the second layer and a transverse velocity of 0 m/s is shown to be maximal at a wavelength λm = 6.76 μm. If the second-layer velocity is u0 = 10 m/s, we have λm = 6.23 μm; at u0 = 50 m/s, λm = 1.24 μm. The mechanism of micro- and nanostructure formation during subsequent electron-beam treatment is a combined thermo-, evaporation, concentration-capillary, and thermoelectric instability. If the influence of the concentration gradient and thermoelectric and evaporation effects is not taken into account, the growth rate is shown to be maximal at a wavelength of 113 μm. When thermoelectric phenomena are taken into account, λm decreases to 48 μm. At a thermoelectric coefficient γ = 0.1 V/K, the growth rate is found to be maximal at λm = 0.3 μm.
Scanning and transmission electron microscopy techniques are used to analyze the structure, phases, and defective substructure of the “high-speed deposited R2M9 steel layer–30KhGSA steel (AISI 4140) substrate” system in the initial state, after high-temperature tempering, and electron-beam treatment.
The formation of TiB2–Ni–Ag coatings on a copper electrical contact by electroexplosive spraying followed by electron-beam treatment is studied, and the structure and properties of the coatings are investigated. The structure of the coatings consists of a matrix based on silver and nickel with TiB2, TiB, and TiNi inclusions. The microhardness, nanohardness, Young’s modulus, wear rate and friction coefficient of the coatings are determined, and electrical erosion resistance tests under arc erosion conditions are performed.
Electron microscopy and electron probe microanalysis are used to estimate the distribution of carbon atoms in cementite particles and defective substructure elements at distances up to 10 mm from the running surface along the central axis and the symmetry axis of the gage corner of differentially quenched long 100-meter rails after a passed gross tonnage of 1411 and 1770 mln t. Three mechanisms of cementite plate transformation have been analyzed. Extremely long-term rail operation is shown to be accompanied by a significant redistribution of carbon atoms in the surface layers up to 10 mm thick. In the initial state, the main amount of carbon atoms concentrates in cementite particles; after extremely long-term rail operation, carbon is also located on structure defects (dislocations, grain and subgrain boundaries), in the surface layer, and in the α-iron-based lattice. An increase in the passed tonnage from 1411 to 1770 mln t is accompanied by more noticeable motion of carbon atoms to structure defects in the gage corner compared to the running surface. The results are discussed using the concepts of bifurcation interstitial structural states in crystal lattice rotation zones and the mechanism of plastic distortion, as well as an analogy between extremely long-term operation and megaplastic deformation.
