Corrosion Behavior of HVOF-Sprayed Fe-Based Alloy Coating in Various Solutions
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JMEPEG DOI: 10.1007/s11665-017-2590-1
Corrosion Behavior of HVOF-Sprayed Fe-Based Alloy Coating in Various Solutions Lei Qiao, Yuping Wu, Sheng Hong, Yujiao Qin, Wei Shi, and Gaiye Li (Submitted January 29, 2016; in revised form October 31, 2016)
A Fe-based amorphous/nanocrystalline coating was prepared by the high-velocity oxygen fuel (HVOF) spraying process. The coating was characterized by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. The corrosion resistances of the Fe-based coating and a reference electroplated hard chromium (EHC) coating were evaluated in a 3.5% NaCl solution, a 1 mol/L HCl solution and a 1 mol/L NaOH solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). All of the results indicated that the corrosion resistance of the Fe-based coating was superior to the resistance of the EHC coating in both the 3.5% NaCl solution and the 1 mol/L HCl solution due to the dense structure and fewer defects of the Fe-based coating. However, the corrosion resistance of the Fe-based coating was inferior to corrosion resistance of the EHC coating in the 1 mol/L NaOH solution. This could be ascribed to the drastic passivation of the EHC coating in an alkaline environment. Keywords
corrosion resistance, Fe-based amorphous/nanocrystalline, HVOF spraying
1. Introduction Due to their homogeneous composition and few crystal defects, amorphous coatings usually have both excellent mechanical properties and superior chemical performance. The lack of grains and grain boundaries results in their remarkable anti-corrosion properties (Ref 1-3). Among the various amorphous coatings, Fe-based amorphous coatings are well known for the combination of excellent corrosion behavior, outstanding wear resistance and relatively low cost (Ref 4–6). Due to these advantages, Fe-based amorphous coatings have shown promise for protecting engineering components from corrosion. Electric arc spraying (Ref 7, 8), plasma spraying (Ref 9) and high-velocity oxygen fuel (HVOF) spraying (Ref 10, 11) are common technologies for preparing coatings, among which the HVOF spraying technology is considered to be one of the most competitive thermal spray processes to prepare high-quality coatings. During the HVOF spraying process, the feedstock particles are injected into a high-velocity hot gas jet generated through the combustion of oxygen and a fuel gas such as kerosene. Due to the extremely high velocity (approximately
Lei Qiao, Yujiao Qin, Wei Shi, and Gaiye Li, College of Mechanics and Materials, Hohai University, 8 Focheng West Road, Nanjing 211100, PeopleÕs Republic of China; Yuping Wu, College of Mechanics and Materials, Hohai University, 8 Focheng West Road, Nanjing 211100, PeopleÕs Republic of China and Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016, PeopleÕs Republic of China; and Sheng Hong, College of Mechanics and Materials, Hohai University, 8 Focheng West Ro
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