Enhanced Electrochemical and Tribological Properties of AZ91D Magnesium Alloy via Cold Spraying of Aluminum Alloy

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Enhanced Electrochemical and Tribological Properties of AZ91D Magnesium Alloy via Cold Spraying of Aluminum Alloy Sumera Siddique1,2 • Cheng-Xin Li3 • Ayrton A. Bernussi2,4 • Syed Wilayat Hussain5 Muhammad Yasir5



Submitted: 27 December 2018 / in revised form: 12 July 2019  ASM International 2019

Abstract Magnesium (Mg) alloys have remarkable physical and mechanical properties for various aerospace applications. However, the high corrosion susceptibility and low wear resistance of Mg alloys restrict their wider use. To overcome these problems, 6061 Al alloy coatings were fabricated via the cold spraying process on the AZ91D Mg alloy substrate and a detailed comparative study on the wear and corrosion properties was carried out. The microstructure analysis of the compact coatings revealed low porosity with no phase change during the deposition process. The coatings showed improved corrosion resistance up to seven times as confirmed by potentiodynamic polarization and electrochemical impedance spectroscopy measurements in 3.5 wt.% NaCl aqueous solution. The as-deposited coatings were also compared with commercial bulk alloys of similar composition for their suitability to industrial applications. The tribological behavior of the coatings and substrate was investigated using tribometer. The wear resistance of the coatings & Muhammad Yasir [email protected] 1

Department of Physics and Astronomy, Texas Tech University, Lubbock, TX 79409, USA

2

NanoTech Center, Texas Tech University, Lubbock, TX 79409, USA

3

State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, People’s Republic of China

4

Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX 79409, USA

5

Department of Materials Science and Engineering, Institute of Space Technology (IST), 1-Islamabad Highway, Islamabad 44000, Pakistan

improved more than two orders of magnitude as compared to the substrate. Abrasive and oxidative wear mechanisms were dominant in the coatings and substrate. The results showed that cold spraying of 6061 Al alloy on AZ91D Mg alloy could be an auspicious process to overcome the poor corrosion and wear resistance of this Mg alloy for practical industrial applications. Keywords cold-sprayed coatings  corrosion protection  magnesium alloy  wear resistance

Introduction Magnesium (Mg) alloys are excellent materials for a large range of applications. Their high damping capacity, low density, good specific strength and recyclability make them an appropriate candidate for the automotive/aerospace applications where these properties have great potential to reduce fuel consumption, thereby contributing to energy savings and reducing environmental impact (Ref 1-4). Although the surface properties of Mg alloys are acceptable for certain applications, their poor corrosion and wear resistance prevent the wider applications of these materials (Ref 5, 6). Therefore, the corrosion protec