Preparation, Microstructures, and Corrosion Resistance of Ni-Mo-P Ternary Amorphous Coating

• Published in: Journal of materials engineering and performance Vol. 32; no. 5; pp. 2476 - 2487
• Main Authors: Jia, Ya-Peng, Sun, Wan-Chang, Dong, Ya-Ru, Xiao, Yan, Liu, Jing-Pei, Zhang, Cong-Xiao
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2023
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Engineering Design; Materials Science; Quality Control; Reliability; Safety and Risk; Technical Article; Tribology; electroless plating; microstructures; AZ91D magnesium alloy; corrosion resistance; Ni-Mo-P composite coatings
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-022-07288-0

Protective Ni-Mo-P ternary composite coating was deposited on AZ91D magnesium alloy substrate by electroless plating with different concentrations of Na 2 MoO 4 . The effect of Na 2 MoO 4 concentration on deposition rate, microstructures, adhesion between the Ni-Mo-P coatings and the substrates, corrosion morphologies and corrosion resistance of Ni-Mo-P coatings were systematically investigated. Moreover, the growth and corrosion resistance mechanisms of the composite coatings were explored. The results revealed that the Ni-Mo-P coating possessed a uniform and dense structure, and the adhesion between the coating and the magnesium alloy substrate was improved. The x-ray pattern and EDS demonstrated that the Ni-Mo-P coating with the addition of 0.4 g/L Na 2 MoO 4 presented amorphous structural characteristics. Furthermore, when the concentration of Na 2 MoO 4 was 0.4 g/L, the Ni-Mo-P coating presented superior corrosion resistance, among which E corr was  − 0.26 V and I corr was 8.725 × 10 −3  A/cm 2 . In addition, the Ni-Mo-P composite coating was corroded slightly at this concentration, with the lowest corrosion rate of 0.68 g/m 2 ·h. The results were attributed to the addition of molybdenum elements to improve the amorphous degree for the coating, which improved the corrosion resistance for Ni-Mo-P composite coatings.