Saint Petersburg Mining University, Saint Petersburg, Russia:

V. Yu. Bazhin, Head of the Chair for Automation of Technological Processes and Production, Doctor of Technical Sciences, Professor, e-mail: bazhin-alfoil@mail.ru
D. V. Gorlenkov, Associate Professor, Candidate of Technical Sciences, e-mail: denis.gorlenkov@gmail.com
V. G. Povarov, Professor, Doctor of Chemical Sciences
V. V. Vedernikov, Leading Researcher of the Mining Museum, Doctor of Historical Sciences, e-mail: vedernikov75@mail.ru

The article discusses the features of the physicochemical properties of some silver coins with a denomination of 1 ruble from the period of Nicholas II with characteristic features of minting, selected from the general collection, as well as the specifics of their manufacture, taking into account the processes of melting silver ore. The silver rubles of the Russian Empire of that time retained the fundamental features laid down by the masters of the coinage of Peter the Great. The role of V. P. Smirnov, the minzmeister of the St. Petersburg Mint, who was the last reconstructor of the Nikolaev silver ruble and made an outstanding contribution to the preservation of the Peter I coinage traditions, is shown. Archival data on the features of equipment operation during the production of the last silver rubles were studied. In order to identify the characteristic elements and features of the coins, silver rubles from the largest number of issues were selected for the study. A metallographic study was carried out, the distribution of impurities over the surface of the reverse and obverse of Nikolaev silver coins was studied when determining the Vickers microhardness on Thixomet equipment. The analysis of the chemical composition of the preliminary blank – silver discs was carried out. The novelty of the approach lies in the fact that the analysis of a large volume of microparticles formed during the processing of compounds (including intermetallic ones), which made it possible to determine the composition of inclusions in silver coins, in combination with thermodynamic modeling methods, enables to determine their nature, taking into account the whole variety of thermophysical, hydrodynamic, physical and chemical processes occurring in liquid and solidifying silver alloy. This may be the rationale for improving the technology of minting coins. The influence of impurities on the structure and properties of a silver coin for several authentic samples of 1898, 1899, 1901, 1912 has been established. The change in the content of impurities from obverse to reverse throughout the entire thickness of the silver ruble and blanks was studied, the level of segregation of elements was determined taking into account the hardness of the surface.

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