Structure and Properties of Aluminum Alloys Modified with Silicon Carbide by Laser Surface Treatment
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STRUCTURE AND PROPERTIES OF ALUMINUM ALLOYS MODIFIED WITH SILICON CARBIDE BY LASER SURFACE TREATMENT H. V. Pokhmurs’ka,1 M. M. Student,2 N. R. Chervins’ka,2 Kh. R. Smetana,2 A. Wank,3 T. Hoenig,3 and H. Podlesak 3
UDC 620.197
We study the structure and properties of AA6082 and AA7075 aluminum alloys modified with particles of Si C with the help of a laser. It is shown that the wear resistance of alloys laser reinforced with Si C in the case of friction against an abrasive wheel is 30–75 times higher than for nonmodified alloys. On the basis of the data of electrochemical investigations, it is shown that, for AA7075 alloy, the influence of its structural heterogeneity on the variation of corrosion potentials decreases as the corrosion activity of the medium increases. We measured the values of corrosion currents of the surfaces of alloys in various corrosive solutions.
High specific strength, technological efficiency, and relatively low cost of production promote the extensive use of aluminum alloys. However, their low tribological characteristics and wear resistance somewhat restrict the possibilities of their application. Therefore, in recent years, significant attention is given to the development of various methods of their surface hardening. As one of new promising technologies for the improvement of the tribological properties of these alloys, one can mention their laser surface modification with solid particles [1–5]. This type of treatment increases their structural heterogeneity, which should affect the corrosion resistance of modified alloys. In what follows, we consider the influence of laser reinforcement of the surfaces of AA7075 and AA6082 alloys (analogs of V95 and AD35 alloys) with particles of silicon carbide on their structure, abrasive resistance, and corrosion resistance. Materials and Experimental Procedure The procedure of laser reinforcement of the surface was performed for plates 100 × 100 × 10 mm in size made of AA6082 and AA7075 alloys (Table 1). The specimens of required sizes were cut out from the plates to measure their wear resistance, electrochemical, and other characteristics. Particles of silicon carbide ∼ 80 μm in size were introduced by a jet of argon in the surface layer of the specimens melted by an Nd : YAG laser [1]. The surface of the plate was repeatedly treated by moving the laser beam with a power of 2 kW and a diameter of 2–3 mm with a velocity of 17–25 mm / sec and different degrees of overlapping. Prior to laser modification, some specimens were heated to 170 or 266°C. The zone of melted metal was protected against oxidation with argon. The abrasive resistance of the specimen surfaces was measured by using two procedures, namely, in the process of friction against a rigidly fixed abrasive (abrasive wheel) and against an abrasive whose particles are not rigidly fixed (sand). 1 Pidstryhach Institute for Applied Problems in Mechanics and Mathematics, Ukrainian Academy of Sciences, Lviv. 2 Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, Lviv. 3 Techni
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