Corrosion and erosion–corrosion behaviour of activated combustion high-velocity air fuel sprayed Fe-based amorphous coatings in chloride-containing solutions

Güney

J. Electrochem. Sci. Eng.

2022

High-velocity air fuel (HVAF) coating processes have advantages over conventional high-velocity oxygen fuel (HVOF) processes, resulting in coatings with superior properties. The present review first provides a concise overview of HVAF coatings, highlighting their advantages over HVOF coatings. Then, the fundamentals of solid particle, slurry, and cavitation erosion are briefly introduced. Finally, the performance of HVAF coatings for erosion-resistant applications is discussed in detail. The emerging research consistently reports HVAF-coatings having higher erosion resistance than HVOF-coatings, which is attributed to their elevated hardness and density and improved microstructural features that inhibit the surface damages caused by erosion. The dominant wear mechanisms are mainly functions of particle impact angle. For instance, the removal of the binder phase at high impact angles causes the accumulation of plastic strain on hard particles (e.g., WC particles) in the matrix, forming micro-cracks between the hard particles and the matrix, eventually decreasing the erosion resistance of HVAF coatings. The binder phase of HVAF-coatings significantly affects erosion resistance, primarily due to their inherent mechanical properties and bearing capacity of hard particles. Optimizing spraying parameters to tailor the microstructural characteristics of these coatings appears to be the key to enhancing their erosion resistance. The relationship between microstructural features and erosion mechanisms needs to be clarified to process coatings with tailored microstructural features for erosion-resistant applications.

Section: Hvaf Coatings Against Slurry Erosionsupporting

confidence: 89%

High-velocity air fuel coatings for steel for erosion-resistant applications

Güney

J. Electrochem. Sci. Eng.

2022

“…Furthermore, the replacement of pure oxygen in the HVOF process with air in the HVAF process, significantly reduces the oxide content in the coatings, which also is desirable in high performance coatings [27,30]. Several studies have been performed on HVAF sprayed Fe-based coatings [2,19,24,28,31,32]. The coatings have shown high corrosion resistance in different environments such as acid, alkaline, and chloride solutions.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of Corrosion Resistance for HVAF-Sprayed Fe- and Co-Based Coatings

2016

There is an increasing demand to replace Co-based coatings with cheap and environmentally friendly Fe-based coatings in corrosive environments. The main objective of this work was to evaluate whether Fe-based coatings could present a better corrosion performance than Co-based coatings. Therefore, two types of Fe-based and one type of Co-based coatings with chemical compositions (in wt %) of Fe-28Cr-16Ni-1.85C (FeNiCrC), Fe-17Cr-12Ni (FeNiCr), and Co-28Cr-1C (CoCrC) were produced by High Velocity Air Fuel (HVAF) spraying. The corrosion behavior of the coatings was studied comparatively by electrochemical tests in 3.5 wt % NaCl solution at 25˝C. The polarization test results showed that the FeCrNiC coating protected the underlying substrate better than the CoCrC coating, while the FeCrNi coating failed to hinder the penetration of corrosive ions. Electrochemical impedance spectroscopy (EIS) measurements revealed that the solution penetrated into the coating through defects, however the corrosion process slowed down due to clogging of the interconnected defects by corrosion products. Increasing the in-flight average particle temperature from 1400˝C to 1500˝C led to a denser coating with fewer defects which seemed to improve the corrosion resistance of the FeCrNiC coating. The high-alloyed Fe-based coatings had the best corrosion protection performance and can thus be recommended as a potential alternative to Co-based coatings.

“…The corrosion metal loss can be calculated from the integrated anodic charge, and the total metal loss can be measured from the weight loss of the same test sample. Anodic potentiostatic polarization is normally used to study the erosion-corrosion behavior of passive steels [15,38,42,70,[93][94][95][96][97][98][99][100]. The corrosion metal loss of the passive steel is always induced by the sand impingements, leading to local breakdown of the passive film.…”

Section: Electrochemical Techniques In Conjunction With Gravimetric Mmentioning

confidence: 99%

An Overview of Major Experimental Methods and Apparatus for Measuring and Investigating Erosion-Corrosion of Ferrous-Based Steels

Liu

Zhou

Wang

et al. 2020

Metals

This paper firstly provides an overview of major efforts made over the past several decades on developing the test apparatus for the study of erosion-corrosion of ferrous-based steels. The merits and the application range of the set-ups, i.e., rotating disc/cylinder electrode system, slurry jet impingement rig, and test flow loop, are introduced. Secondly, the advantages and limitations of both non-electrochemical and electrochemical methods used for the measurement of erosion-corrosion are presented. Thereafter, the interaction between erosion and corrosion using a cyclic erosion-corrosion method was introduced. The synergy between erosion and corrosion for the steels under the passive state were analyzed on the basis of the breakdown and restoration of the passive film. In addition, the difference between the obtained erosion-enhanced corrosion and the corrosion-enhanced erosion using different experimental methods for steels under active corrosion was discussed. Finally, the interaction between the localized corrosion and erosion was studied through the dynamic change of the local current distribution revealed by the wire beam electrode.