A Study on the Corrosion Inhibition of Fe-Based Amorphous/Nanocrystalline Coating Synthesized by High-Velocity Oxy-Fuel
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A Study on the Corrosion Inhibition of Fe-Based Amorphous/ Nanocrystalline Coating Synthesized by High-Velocity Oxy-Fuel Spraying in an Extreme Environment Sapan K. Nayak1 • Anil Kumar1 • Kuntal Sarkar2 • Abhishek Pathak2 Atanu Banerjee2 • Tapas Laha1
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Submitted: 15 May 2019 / in revised form: 9 August 2019 ASM International 2019
Abstract In this work, Fe-based (Fe-Cr-B-P-C) amorphous/nanocrystalline composite coatings were deposited by high-velocity oxy-fuel thermal spray method with varying powder feed rates and their behavior in saline environment was investigated. An SS316L coating with optimized parameters was also prepared for comparison purpose. The microstructural characterization of the composite coatings revealed the presence of embedded nanocrystalline phases in the amorphous matrix. The amorphicity of the coating increased, whereas the porosity content decreased gradually with the increment in feed rate during the spraying process. The combined effect of extent of devitrification and porosity content on the corrosion behavior of the various coatings was analyzed.
Potentiodynamic polarization and electrochemical impedance spectroscopy studies revealed that the Fe-based composite coatings exhibited significantly lower corrosion current density and higher polarization resistance than that of the mild steel substrate as well as SS316L coating. The enhanced corrosion resistance of the composite coatings is ascribed to the combined effect of lower porosity content and retained amorphous phase. In addition, the formation of chromium hydroxide along with some of the oxides and hydroxides of iron in the post-corroded coating samples aids in impeding the corrosive solution penetration, thereby increasing the corrosion inhibition efficiency of the composite coatings.
& Sapan K. Nayak [email protected] Tapas Laha [email protected] 1
Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721302, India
2
Research and Development Division, Tata Steel, Jamshedpur 831007, India
123
J Therm Spray Tech
Graphic Abstract
Keywords corrosion inhibition EIS Fe-based amorphous/nanocrystalline composite coating highvelocity oxy-fuel (HVOF) spraying polarization saline environment
Introduction Bulk metallic glasses (BMGs) exhibit a remarkable combination of mechanical and chemical properties, including superior strength, high hardness and outstanding wear and corrosion resistance attributed to their disordered and defectfree structure, i.e., absence of grain boundaries, slip system, etc. (Ref 1-3). Despite these appealing properties, the industrial application of BMGs is hindered gravely due to their inherent room temperature brittleness and strain softening (Ref 1, 4, 5). Alternately, the preparation of BMG composites with crystalline second phase has proved to be an effective approach to enhance its toughness owing to the hindrance to shear band propagation and promotion of multiple shear band formation caused by the crystalline phas
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