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Perspectives of improving physical and mechanical properties of thermal coatings by electropulse exposure

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Category: Geotechnical and mining mechanical engineering, machine building

Last Updated on 16 March 2017

Published on 16 March 2017

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Authors:

O.M.Dubovyi, Dr. Sc. (Tech.), Prof.,Admiral Makarov National University of Shipbuilding, Mykolaiv, Ukraine, e-mail:This email address is being protected from spambots. You need JavaScript enabled to view it.

O.V.Chechel, Cand. Sc. (Tech.),Frantsevich Institute for Problems of Materials Science of NAS of Ukraine, Kyiv, Ukraine

M.M.Bobrov, Cand. Sc. (Tech.),Admiral Makarov National University of Shipbuilding, Mykolaiv, Ukraine, e-mail:This email address is being protected from spambots. You need JavaScript enabled to view it.

Yu.Ye.Nedel'ko,Admiral Makarov National University of Shipbuilding, Mykolaiv, Ukraine, e-mail:This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract:

Purpose.To explore the possibility of raising the physical and mechanical properties of electric-arc and plasma sprayed coatings by electric pulse exposure (EPE) on high temperature heterophasic stream during deposition and subsequent pre-recrystallization heat treatment (PHT).

Methodology.Study of porous electric arc and plasma sprayed coating was carried out using a computer metallography. Vickers hardness was determined. The study of thermal properties of coatings was carried out by using a dynamic calorimeter. The bond strength of the coating was determined by “pulling the pin” on the witness samples. Determination of wear resistance of the resulting coatings was performed on the SMC-2 machine friction on a “roller-shoe” in the boundary lubrication conditions. The definition of regions of coherent x-ray scattering to estimate the size of the substructure of the coating material was carried out by X-ray analysis on a DRON-3.

Findings.The optimum amplitude and frequency parameters of EPE at electric arc spraying of Sv-08G2S wire (pulse frequency – 6.5 kHz, the amplitude – 5 kV) and PG-19M-01 powder plasma spraying (frequency – 5 kHz, the amplitude – 5 kV) were determined, which provide increased hardness (up to 35 %), density, bond strength (to 30 %) and the wear resistance of the coatings (1.5…1.7) by grinding and accelerating sprayed particles. The optimum temperature-time parameters of PHT that provide a further increase in the hardness of the coatings by grinding sub grain size to nanoscale inclusive were defined. The possibility of thermal stabilization poligonization substructure of coatings by plastic deformation was investigated.

Originality.The laws of EPE influence on the microstructure and mechanical properties (hardness, bond strength, thermal conductivity, wear resistance) of electric arc and plasma coatings were determined. The technology PHT sprayed coatings in the direction of increasing the exposure time due to subsequent plastic deformation was further developed.

Practical value.The application of research results obtained in the work, namely the definition of the scheme of the connection of high-voltage pulse, the optimal parameters of EPE during electric arc and plasma spraying and subsequent heat treatment provide the opportunity to expand the range of cheaper sprayed materials for the coatings of heavily loaded parts of mechanical engineering, electrical products and parts of the military-industrial complex.

References / Список літератури

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