Publication: Investigation of strontium phosphate coating pre-treatment on corrosion behaviour of zinc phosphate coating on magnesium alloy
Date
2024-02
Authors
Nurul Nadzirah binti Ismail
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Abstract
Magnesium alloys (Mg) are widely used in various industrial applications due to their lightweight properties, but their susceptibility to corrosion poses significant challenges for long-trem reliability. Surface pre-treatment method, which is strontium phosphate (Sr-P) pre-treatment, have emerged as promising strategies for improving the corrosion resistance of Mg alloys. In this study, the effectiveness of Sr-P pre-treatment on Mg alloy surfaces was systematically investigated, with focus on its impact on zinc phosphate (Zn-P) coating deposition and corrosion behaviour. The Zn-P coating was applied to a pre-treated Mg surface at varying Sr-P pre-treatment time (2, 5, and 15-minute) and concentration (0.1, 0.2, and 0.5 M), followed by detailed characterization and corrosion testing. The study employed a combination of experimental techniques, including SEM-EDS analysis, gravimetric analysis, immersion tests, polarization and EIS, to evaluate coating characteristics and corrosion performance. Results revealed that Sr-P pre-treatment significantly enhanced the adhension, coverage and corrosion resistance of zinc phosphate coatings on Mg alloy surfaces. Additionally, the study identified the optimal pre-treatment conditions, with a 2-minute pre-treatment time and a concentration of 0.1 M Sr-P solutions, yielding the lowest icorr value (59.93 μA/cm2) and highest Rct value (6881.90 Ω), along with the best coating coverage and corrosion protection.