Enhancing the Corrosion Resistance of Low Pressure Cold Sprayed Metal Matrix Composite Coatings on AZ31B Mg Alloy through Friction Stir Processing

Thirumalaikumarasamy Duraisamy,Deepak Sampathkumar,Ashokkumar Mohankumar,Guruprasad Balachandran,Sathiyamoorthy Ranganathan,Murugan Kaliyamoorthy,Ramachandran Chidambaramseshadri,Thirumal Pattabi,Pradeep Raj Rajendran

doi:10.3390/coatings12020135

Thirumalaikumarasamy Duraisamy, Deepak Sampathkumar + Show 7 more

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https://doi.org/10.3390/coatings12020135

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Abstract

To improve the corrosion resistance of Mg alloy, Al alloy/alumina metal matrix composite (MMC) coatings were formed by low pressure cold spraying (LPCS) technology followed by post friction stir processing. The phase structure, microstructure, and corrosion properties of the cold-sprayed metal matrix composite coatings before and after friction stir processing were investigated. The effect of the friction stir process (FSP) on the corrosion characteristics of MMC coatings at 3.5 weight percent of NaCl solution was explored using a Tafel polarisation plot. Microstructural studies were examined to investigate the electrochemical behaviour of the cold spray (CS) and FSPed MMC coatings. The results demonstrated that an enhancement in corrosion protection of the MMC deposits occurred at the 1st and 2nd runs of FSP, with superior corrosion performance observed at the 2nd run of FSP. The enhanced surface state is the primary enhancement mechanism of the electrochemical properties of the FSPed MMC coatings. For the higher run of FSP (3rd run), the electrochemical performance of the specimens was lower owing to the amalgamate action of the enhanced surface state with the aggravated interface of interior deposits.

Highlights

Aluminium metal matrix composites (MCC) are actively employed in numerous fields like aerospace, marine, and automobile industries due to its great strength, excellent modulus of elasticity, and superior tribological properties [1,2,3]
Multiple runs of friction stir process (FSP) improved the rate of scattering and separation of alumina particles due to the high stir motion created by FSP
(ii) The matrix phase (Al alloy) dislocation density and micro strain are lowered after the friction stir technique

Summary

Introduction

Aluminium metal matrix composites (MCC) are actively employed in numerous fields like aerospace, marine, and automobile industries due to its great strength, excellent modulus of elasticity, and superior tribological properties [1,2,3]. MMCs produced using traditional processes such as liquid and powder metallurgy [2,4,5,6,7] and various thermal spray technologies [8,9] frequently have flaws like pores, larger grain size, weak bond strength, and undesired interfacial reaction products. The most developing technology is a solid-state coating method called “cold spray” (CS), which has been suggested to develop MMCs due to its lower processing temperature and high velocity capabilities [10,11,12,13,14]. Cold sprayed MMC coatings have less porosity and higher adhesive and cohesive strength among the metallic elements than cold sprayed raw metallic deposits [15,16]. The cohesive strength is lower among the ceramicmetal and ceramic-ceramic components, which may occur through cold sprayed MMC coatings. Significant cracks and micro or nano pores (unbounded regions) at these interfaces cause strong localised corrosion, which decreases the electrochemical performance of the deposits [17,18]

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