Effect of electric arc spraying of Al-4.6Cu-1.5Mg coating and its plasma-electrolyte treatment on the corrosion resistance of Mg-8.5Al alloy in 3% NaCl

DOI: 10.62564/M4-HV1435

Halyna Veselivska, Volodymyr Hvozdets’kyi, Mykhailo Student, Khrystyna Zadorozhna

Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine


Since magnesium alloys, which are widely used in the automotive and aviation industries, have insufficient wear resistance and corrosion resistance, there is a need to improve their surface properties. The purpose of the study was to determine the effect of the Al-4.6Cu-1.5Mg aluminium electric arc coating (EAC) sputtered at an air jet pressure of 1.2 MPa and the synthesized plasma-electrolyte oxidized (PEO) layer on it on the structure and some characteristics of the Mg-8.5Al magnesium alloy. The microstructure of the coated samples was studied on an EVO 40XVP scanning electron microscope. X-ray phase analysis of the coating was performed in Cu-Kα radiation. The porosity of the PEO layers was determined by hydrostatic weighing. Microhardness was determined using a microhardness tester. The electrochemical characteristics in 3% NaCl of the obtained coatings were determined from the potentialdynamic polarization curves taken at a scanning speed of 1 mV/s. EAC with a thickness of ~ 250 μm on magnesium alloy have a typical lamellar structure and are porous. The lamellae are separated by thin Al2O3 oxide films. In the process of PEO, the electrolyte penetrates the EAC, accumulates in its pores, and the formation process occurs as if from its middle, the lamellae disappear and its porosity is reduced by half. This increases the microhardness of the coating. Electrochemical studies have shown that the PEO of an aluminium coating additionally increases its corrosion resistance in NaCl solution by more than an order of magnitude [1]. Thus, spraying coatings from aluminum alloys onto magnesium alloys, followed by PEO treatment, makes it possible to produce oxide ceramic coatings with properties on par with PEO coatings on aluminum alloys. This integrated approach makes it possible to create oxide ceramic coatings on other alloys that are not subject to PEO treatment, such as steels and cast irons.

Keywords
electric arc coating, plasma-electrolyte oxidation, corrosion resistance.

Acknowledgments
Not provided

References
[1] M. M. Student, I. B. Ivasenko, V. M. Posuvailo, H. H. Veselivs’ka, A. Yu. Pokhmurs’kyi, Ya. Ya. Sirak, V. M. Yus’kiv // Materials Science. – 2019. – 54, №6 – Р. 899–906.