Friction Behavior of Electric-Spark Coatings Under the Conditions of Boundary Lubrication
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FRICTION BEHAVIOR OF ELECTRIC-SPARK COATINGS UNDER THE CONDITIONS OF BOUNDARY LUBRICATION V. М. Holubets,1 V. М. Dovhunyk,2,3 M. І. Pashechko,4 S. А. Kornii,2 and Yu. S. Shpulyar1
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We study the friction characteristics of “disk–shoe (segment)” friction couples of 45 steel with applied electric-spark coatings. Their wear resistance under the conditions of boundary lubrication and the morphology of the surface layers or secondary structures formed on the counterbody in the course of friction are analyzed. Keywords: electric-spark coatings, wear resistance, friction coefficient, morphology, elemental analysis.
Introduction For increasing the durability and reliability of machine parts, it is customary to use various technological methods of modification of the metal surfaces of friction couples [1–5]. Among methods of this kind, we can especially mention the electric-spark alloying (ESA), which enables one to change the properties of the surface of intact metal as a result of the formation on this surface of a new material with different structure and chemical composition. Numerous research works are devoted to the investigation of the wear resistance of electric-spark coatings (ESC). As electrodes for ESA, it is customary to use various materials: hard alloys on the basis of tungsten and titanium with additions of carbon (VK-20U, ТК-15 К6U), ferrochromium, white cast iron, etc., and also powder wires (PW). The sizes of worn articles are, as a rule, restored with the help of electrodes made of materials whose physicomechanical characteristics are close to the characteristics of the original material. In the literature, one can find numerous attempts to create low-cost electrode materials from eutectic alloys [6, 7], PW [8, 9], and combined electrodes [8]. In this connection, complex technologies of ESA [7, 10] and combined alloying of the friction surfaces with ferrochromium in combination with graphite [11] prove to be quite promising. However, the tribological behavior of the ESC formed by using the ESA technology from PW is now poorly studied. Therefore, the aim of the present work is to analyze the efficiency of ESA of 45 steel with the use of titanium-based T15K6 hard alloys and PW as electrodes, determine the rational technological conditions of application of the ESC, and analyze their tribological characteristics under the conditions of boundary lubrication. 1 2 3 4
National Forestry Engineering University of Ukraine, Lviv, Ukraine.
Karpenko Physicomechanical Institute, Ukrainian National Academy of Sciences, Lviv, Ukraine. Corresponding author; e-mail: [email protected]. Lublin Polytechnic Institute, Lublin, Poland.
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 56, No. 1, pp. 47–52, January–February, 2020. Original article submitted July 30, 2019. 1068-820X/20/5601–0043
© 2020
Springer Science+Business Media, LLC
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V. М. HOLUBETS, V. М. DOVHUNYK, M. І. PASHECHKO, S. А. KORNII,
AND
YU. S. SHPULYAR
Experimental Procedure We study specimens in the form of a “disk
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