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Technology of obtaining strengthening nanostructured electrospark coatings on aluminum alloys and their use in the repair of machine parts


Author: Iurcenco Evgheni
Degree:doctor of engineering
Speciality: 05.16.06 - Powder metallurgy, composite materials
Year:2016
Scientific adviser: Alexandru Dicusar
doctor habilitat, professor, Institute of Applied Physics of the ASM
Institution: Institute of Applied Physics of the ASM

Status

The thesis was presented on the 25 October, 2016
Approved by NCAA on the 28 December, 2016

Abstract

Adobe PDF document0.77 Mb / in romanian
Adobe PDF document0.71 Mb / in russian

Thesis

CZU 621.9.048.4

Adobe PDF document 6.00 Mb / in russian
183 pages


Keywords

электроискровая обработка, электроискровое легирование, алюминий, наноструктурирование, скорость износа, микро – и нанонити оксида олова, оксид алюминия

Summary

The dissertation is written in Russian, it consists of an introduction, four chapters, general conclusions, recommendations and list of references. The paper contains 139 pages of text, 54 images, 29 tables, the list of references which includes 188 ources.

Related publications: the results obtained were published in 19 scientific papers (10 articles, 7 scientific conference abstracts), 2 patents.

Area of research: - Electrophysical technology and surface engineering.

The purpose of the paper was to determine the rules of forming wear-resistant coatings of parts made of aluminum alloys through the use of electrospark doping (ESD) by tool electrodes, which are a mechanical mixture of a low-melting component in a hard-melting matrix, and on this basis – to develop technologies of restoring worn surfaces.

Scientific novelty and originality of the paper: It is determined that microdispersed particles including microwires and nanowires consisting of the low-melting component and its oxides produced during the transfer from the anode may be formed on the treated surface during the electrospark doping by electrodes which are a mechanical mixture of lowmelting component dispersed in the hard-melting component, thereby a nanocomposite having high wear resistance is obtained.

It is determined that in conditions of friction under low loads and relatively low speed microwires and nanowires of tin oxide play a crucial role in improving the wear resistance of coatings, and in conditions of friction under high load and high speed the role of microwires and nanowires levels off, and ESD treated matrix plays decisive role.

The possibility of obtaining ESD coatings with increased thickness through periodic application of the “barrier layers” on aluminum alloys is shown. The Al-Ni alloy has the best properties of “a barrier layer”, which allows to obtain a coating with thickness of up to 2 • m.

Scientific problem which was solved: The possibility of obtaining coatings with increased thickness through the use of ESD on the Al alloys was proved, that is a consequence of forming microwires and nanowires of low-melting component and its oxides during the process of ESD by tool electrodes made of Al alloy with a low-melting component (Sn, Pb). Object of research are the methods of formation and properties of the coatings obtained by ESD through the application on the matrix made of Д1alloy by tool electrodes made of Al-Sn alloys (AO20-1), Al-Pb, Al-Ni.

The theoretical significance of the work: we can regard the results obtained as a new way to produce microwires and nanowires in the coating using the ESD, as well as a basis for further development of manufacturing nanostructured wear-resistant surfaces.

Implementation and practical significance of the work: the results of the research can be accepted as a basis for manufacturing wear-resistant coatings of the surfaces made of aluminum alloys both with building-up of the worn-out layer and without it using electrospark doping by tool electrodes made of Al-Sn alloy (AO20-1).

The technology for repairing bearings seats for tractor body parts made of aluminum alloys has been developed on the basis of the research results and it was implemented in such enterprises as subsidiary company Moldavizolit RiO LLC, commercial manufacturing enterprisе Sovremennye Tehnologii LLC, Torgovy Proyekt in Tiraspol.