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Corrosion behavioral studies on AA7075 surface hybrid composites tailored through friction stir processing

Suganeswaran Kandasamy (Department of Mechatronics Engineeering, School of Building and Mechanical Sciences, Kongu Engineering College, Erode, India)
Parameshwaran Rathinasamy (Department of Mechatronics Engineeering, School of Building and Mechanical Sciences, Kongu Engineering College, Erode, India)
Nithyavathy Nagarajan (Department of Mechatronics Engineeering, School of Building and Mechanical Sciences, Kongu Engineering College, Erode, India)
Karthik Arumugam (Department of Nanosciene and Nanotechnology, KS Rangasamy College of Technology, Tichuchengode, India)
Rajasekar Rathanasamy (Department of Mechanical Engineeering, School of Building and Mechanical Sciences, Kongu Engineering College, Erode, India)
Gobinath Velu Kaliyannan (Department of Mechanical Engineeering, School of Building and Mechanical Sciences, Kongu Engineering College, Erode, India)

Anti-Corrosion Methods and Materials

ISSN: 0003-5599

Article publication date: 7 May 2020

Issue publication date: 11 June 2020

187

Abstract

Purpose

This paper aims to overcome the corrosion in AA7075 by incorporating the dual-reinforcements like Al2O3 and SiC through friction stir processing (FSP). In recent days, an automotive monocoque structure undergoes corrosion because of changes in environmental conditions.

Design/methodology/approach

Surface hybrid composites (SHCs) of AA7075 with different weight ratios of Al2O3 and SiC were fabricated at a rotating speed of 1000 rpm, traveling speed of 56 mm/min and tool tilt angle of 2º with two passes. Surface regions were observed using optical microscopy, and the potentiodynamic corrosion test was performed under a 3.5 per cent NaCl environment at room temperature. Then, the surface morphology analysis of corroded samples and their structural properties were also investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron dispersive spectroscopy (EDS).

Findings

Through FSP, an improved interface between the reinforced particles and the AA7075 base matrix was observed because of the severe plastic deformation. Potentiodynamic polarization tests confirmed that the AA7075 matrix with a higher concentration of Al2O3 and a lower concentration of SiC (Al2O3 – 75 per cent and SiC – 25 per cent) possesses a lower corrosion rate than other specimens. This result is because of the combined effect of stable passive film formation and the resistance produced by hard SiC particles. In addition, the formation of a stronger interface between the reinforcements and the base matrix impedes the NaCl solution attack. The SEM micrograph depicts the film crystallinity variations with an increase in Al2O3 content. Debonding between the layers was observed on increasing the SiC content in the base matrix. XRD shows the peaks of reinforcing elements that influence the corrosion behavior. These observations suggest that the AA7075 reinforced with a higher concentration of Al2O3 and a lower concentration of SiC through FSP affords a suitable solution for automotive monocoque applications.

Originality/value

The corrosion rate has been identified for AA7075 SHCs with various concentrations of Al2O3 and SiC and has been compared with that of the base metal and the friction stir processed specimen without reinforcement.

Keywords

Acknowledgements

The authors thank CSIR-CECRI Karaikudi for completing the morphological analysis of the specimens.

Citation

Kandasamy, S., Rathinasamy, P., Nagarajan, N., Arumugam, K., Rathanasamy, R. and Velu Kaliyannan, G. (2020), "Corrosion behavioral studies on AA7075 surface hybrid composites tailored through friction stir processing", Anti-Corrosion Methods and Materials, Vol. 67 No. 4, pp. 345-355. https://doi.org/10.1108/ACMM-11-2019-2215

Publisher

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Emerald Publishing Limited

Copyright © 2020, Emerald Publishing Limited

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