Erosion-corrosion Resistance Research Articles

Dual Ni/Ni-Co electrodeposited coatings for improved erosion-corrosion behaviour

Industrial applications of hydrophobic metallic coatings are limited to durability of their surface structures against detrimental effects of the surrounding environments. In the present research, the life-long of the hierarchical structure of hydrophobic nickel coating in an erosive-corrosive solution was investigated. The effect of alloying with cobalt on strengthening the hierarchical structures was also investigated. In this regard, highly hydrophobic Ni/Ni, Ni-Co/Ni-Co, dual Ni/Ni-Co and dual Ni-Co/Ni coatings with rough hierarchical structures were electrodeposited. In situ electrochemical measurements were performed to investigate changes in corrosion resistance and hydrophobicity of the coatings with damage initiation to their morphology. Damage to the hierarchical structure of the coatings during erosion-corrosion tests was followed by a decrease in their real surface area in contact with solution and as a result an increase in the charge transfer resistance of the coatings. The Ni/Ni coating showed the highest increase of polarization resistance after erosion-corrosion test, and therefore, it had the lowest erosion-corrosion resistance. On the other hand, the Ni-Co/Ni experienced the lowest degradation during erosion-corrosion test, but it showed higher loss in water contact angle due to flattening of top Ni cones. Although, the coatings with second Ni-Co layer had more degradation, but they revealed less contact angle loss denoting better preservation of hierarchical structures and thus hydrophobicity.

Small punch creep testing of thermally sprayed Stellite 6 coating: A comparative study of as-received vs post-heat treatment

Thermally sprayed Stellite 6 coatings offer high wear and corrosion-erosion resistance at high temperature but the creep behaviour of such coatings is not well understood. In this paper, the microstructure and creep behaviour of a HVOF Stellite 6 coating was investigated. The coating was tested in the as-sprayed condition and after an isothermal heat-treatment of 1 h at 1050 °C. The as-sprayed coating comprised FCC Co-Cr-W solid solution with 2–3 wt% HCP phase, whereas the heat-treated coating comprised FCC Co-Cr-W solid solution, 11 wt% M23C6 carbides and 7 wt% M7C3 carbides. Small punch creep tests were conducted at 700 °C on the as-sprayed and heat-treated coatings. The heat-treated coating exhibited minimum steady-state strain rates approximately 2 orders of magnitude lower than the as-sprayed coating when tested at similar loads, leading to times to failure approximately two orders of magnitude longer for the heat-treated coating within the selected load range. Fracture analysis showed cracking along powder particle boundaries was the main mode of cracking in the as-sprayed coating whereas for the heat-treated coating, fracture along the carbide / matrix interface was the main fracture mechanism.

Chlorine-induced high-temperature corrosion and erosion-corrosion of HVAF and HVOF-sprayed amorphous Fe-based coatings

Chlorine-induced high-temperature corrosion and erosion-corrosion behavior of amorphous Fe-based coatings sprayed by high velocity air-fuel (HVAF) and high velocity oxy-fuel (HVOF) techniques were investigated. The coated specimens were first exposed to isothermal high-temperature corrosion at 600 °C in ambient air with and without KCl. The exposed specimens were then subjected to alumina erodent. The as-sprayed HVAF coating showed a more compact and uniform microstructure with a higher hardness leading to higher corrosion and erosion-corrosion resistance. After erosion, all the coatings similarly exhibited a combined brittle/ductile damage to surface oxide scale that previously formed in the corrosive environment. The corrosion and erosion-corrosion behavior of the coatings primarily relied on the uniformity of coatings' microstructure and distribution of alloying elements to form the protective oxide scale in the corrosive environment, which can resist against erodent in the erosive media.

The effect of low pH in erosion-corrosion resistance of high chromium cast irons and stainless steels

Corrosive wear is a form of material degradation that is known to occur on equipment and components that handle suspended solids in aqueous solutions. This surface deterioration process is generally enhanced when the fluids contain chlorides that are acidic in nature. Such environments are encountered in many applications, one such example being the minerals processing industry.High chromium white cast irons are widely used in many engineering applications as they extend the service life beyond that of stainless steels. In this work, the corrosive wear of austenitic stainless steel UNS S31600 and martensitic stainless steel UNS S42000 are compared with high chromium white cast irons (27WCI and 37WCI) by using a submerged jet technique at perpendicular incidence. The testing medium consisted of 3.5% NaCl liquid solution (pH 7 and pH 3) with suspended silica sand particles. The post-test methodology characterised the material loss within the directly impinged zone and turbulent zone where abrasive damage is involved. In neutral conditions, the presence of chromium carbides in white cast irons provided benefits, whilst in the acidic conditions, the austenitic structured materials (for stainless steels and white cast irons) suffered lower overall material loss compared with the martensitic structured materials.

Erosion Corrosion Study of HVOF Sprayed Thermal Sprayed Coatings on Boiler Tubes:A Review

Many industrial parts used in power generation industries fail due to erosion, corrosion, and abrasion causes huge economic losses. These problems can be overcomeby either changing the materialor changing the environment or by separating the material surface from the corrosive environment. The distinct investigations have been carried out to overcome the erosion problems and observedthat erosion resistant coatings have been gaining more importance in recent times. Among the different thermal spray coating techniques, High Velocity Oxy Fuel (HVOF)has emerged as an effective, advancedand rapidly developing processto produce dense coating at relatively low temp.withlow porosity (less than 1%). HVOF has been widely adopted by many industries due to its several advantages such as high micro-hardness, adhesion strength, and erosion-corrosion and wear resistance, flexibility, and cost effectiveness with homogenous coating. The main purpose of this review paper is to reviewprevious research in the field of high velocity Oxy-fuel (HVOF)sprayed coating,especially in context with Indian boilertubes. In addition,an attempt has been made to study their basic principles, merits, demerits, applications and comparison.

Slurry erosion–corrosion wear behavior in SiC-containing NaOH solutions of Mo2NiB2 cermets prepared by reactive sintering

The slurry flow unit, such as coal-mining industry, erosive wear and erosion-corrosion can cause high rates of material loss, particularly in the hydrotransport system where corrosive slurries are encountered. Stainless steel, Metal Matrix Composites (MMCs) and so on, comprising a ductile binder with a reinforcing hard phase, are seeing greater applications as coatings and hard facing for critical components, where there is a requirement for high durability. In this paper, the erosion-corrosion performance of Mo2NiB2-based cermets applied by the reaction sintering process is evaluated. Three cermets, with varying volume fraction of Mo2NiB2 phase range, all with a Ni binder, have been considered. The microstructure and properties of Mo2NiB2-based cermets are investigated and discussed. The influence of volume fraction of Mo2NiB2 phase on the erosion and erosion–corrosion resistance is researched under alkaline conditions. Results reveal that the increasing of boron percent along with Mo2NiB2 phase pile up. Meanwhile, the hardness has direct relationship with the volume fraction of Mo2NiB2. The Mo2NiB2 phase plays an important role in wear behavior. The effect of Mo2NiB2 phase volume fraction on erosion–corrosion only containing NaOH solution of Mo2NiB2-based cermets is different from that on erosion containing both NaOH solution and SiC. It is advantageous for the corrosion resistance to contain more Mo2NiB2 phase. In alkaline slurry impact, the cermets with less Mo2NiB2 phase deteriorate largely due to corrosion which decreases the mechanical properties and speeds up the total loss of material. In alkaline slurry with SiC particles, the weight gain is produced by the synergistic effect of erosion and corrosion on the contrary. When the volume fraction of Mo2NiB2 is low, corrosive production is the main cause of weight gain due to increasing interference between impinging and reflected erodent. The Mo2NiB2 phase is more, the corrosion resistance is higher and the corrosive production is much less.

A STUDY ON EROSION AND CORROSION BEHAVIOR OF Cr3C2-NiCr CERMET COATINGS

In this study, Cr3C2-25NiCr cermet coating samples were prepared by atmospheric plasma spraying (APS) technique on 410 stainless steel substrate with different plasma spraying parameters, namely, the plasma current (500 and 600 A), and the powder feed rate (10 and 30 g/min). The erosion-corrosion behaviour of the coatings was studied by electrochemical measurements, salt spray and erosion-corrosion tests. The electrochemical tests were performed in 3.5 wt.% NaCl solution. During the erosion-corrosion test, the samples were immersed in 3.5 wt.% NaCl solution containing 0.25 wt.% SiO2 particles with a rotational speed of 950 rpm for 72 hours. The obtained results showed that the plasma sprayed coating sample at the plasma current of 600 A and the powder feed rate of 10 g/min has a best erosion-corrosion resistance. Red rust spots did not appear on surface of this coating after 120 hours of salt spray test. It was much slower than on the others (after only 24 hours salt spray test). The weight loss of this coating during the erosion-corrosion test was lower than the remaining samples. These results are consistent with the results of electrochemical tests.

Cavitation and Erosion Corrosion Resistance of Nonleaded Alloys in Chlorinated Potable Water

The January 2014 Federal Reduction of Lead in Drinking Water Act reduced the lead content in brass used in water distribution operations and in premise plumbing from 8% to <0.25% Pb (termed “nonlea...

SiC Particulate Reinforced Aluminium Metal Matrix Composite

Al or Al alloy Metal Matrix Composites have wide range of applications i.e. aerospace, automobile etc. due to its lightweight, high tensile strength, high wear resistance. This review paper characterized the SiC particulate reinforced Al Metal Matrix Composites. The SiC particulates are dispersed in Al or Al alloy by liquid state processing route and solid-state processing route. Stir casting liquid processing route has been followed by no. of researchers due to its simplicity and low processing cost and at the time of reinforcement small amount of Mg is added to increase the wettability of SiC in molten Al or Al alloy. When Al or Al alloy reinforced with SiC, then its mechanical and tribological properties are enhanced. The effect of particle size, weight or volume fraction of the SiC on density, porosity, hardness, impact toughness, tensile strength, ductility, sliding wear resistance, slurry erosion resistance, erosion-corrosion resistance, corrosion resistance and fatigue strength of Al or Al alloy MMCs are reported. The effect of extrusion and machinability of the SiC particulate reinforced Al MMCs are also discussed in this review article.

Enhancing the cavitation erosion resistance of D8m-Ta5Si3 nanocrystalline coatings through Al alloying

To investigate the effects of Al alloying on the erosion-corrosion resistance of β-Ta5Si3, both a β-Ta5Si3 coating and an Al-alloyed β-Ta5(Si0.83Al0.17)3 coating were synthesized on a 316 substrate by the double cathode glow discharge technique. The phase constitution, composition and microstructure of the two coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The two coatings were composed of nearly rounded D8m-β-Ta5Si3 grains with an average size of ∼4 nm, and after the addition of Al, the preferred growth orientation for the β-Ta5Si3 coating changed from (4 0 0) to (0 0 2). The hardness, elastic modulus and contact damage resistance of the coatings were measured using a nanoindentation tester. The results showed that Al alloying improved the contact damage resistance of β-Ta5Si3 with only a slight decrease in hardness. The erosion-corrosion behavior of the two coatings was performed in a 3.5 wt% NaCl solution containing a 12 wt% concentration of silica sand under two phase slurry flow condition and in a 3.5 wt% NaCl solution under ultrasonic cavitation erosion conditions. This revealed that the Al alloyed β-Ta5Si3 has a higher resistance to both erosion-corrosion and ultrasonic cavitation erosion as compared to the binary β-Ta5Si3 coating.

Erosion-corrosion behavior of highly hydrophobic hierarchical nickel coatings

The effect of surface microstructure on erosion-corrosion resistance of hydrophobic rough and smooth nickel electrodeposited coatings was investigated using on site electrochemical impedance spectroscopy in dynamic solution of 3.5 wt.% NaCl + 40 wt.% sand. Atomic force microscopy (AFM) was used to track damage initiation at the surface of the coatings during erosion-corrosion. Changes in the hydrophobic behavior of the coatings during erosion-corrosion were recorded. It was observed that the rough nickel coating was not erosion resistant and about 65% of its initial average roughness was lost after 30 min of erosion-corrosion. This loss of roughness approached to about 80% after 1 h of erosion-corrosion. The water contact angle of the rough nickel coating after two weeks of storing in the air was about 131° which decreased to about 115° after 30 min of erosion-corrosion and to about 78° after 1 h of erosion-corrosion. However, during erosion-corrosion tests, the polarization resistance of the rough nickel coating was constantly higher than that of the smooth nickel coating notwithstanding the significant loss of its surface microstructural features.

The effect of disodium cocoamphodiacetate on corrosion-erosion resistance of steel in saline water

The inhibitory actions of disodium cocoamphodiacetate (zwitterionic surfactant, abbreviated as ZS) on the erosion-corrosion of API ×52 steel in sand-containing saline produced water (SSPW) were explored by using electrochemical techniques. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the steel surface. The results showed that the ZS reduced the effects of the erosion-corrosion of API ×52 steel in SSPW solution. The extent of ZS performance depends on ZS concentration, solution temperature, static and dynamic conditions. The nature of ZS surfactant (i.e. mixed type of inhibitor) was extracted from polarization curves. ZS is more effective in static condition than in dynamic condition. The maximum inhibition efficiency of ZS is 93.2% and 66.7% at static and dynamic conditions, respectively.

Nickel based coatings used for erosion-corrosion protection in a geothermal environment

Development of advanced coatings for corrosion protection for different technological application currently has a strong emphasis worldwide. Nickel alloy based coatings have for example been tested and studied for oil and gas industry application, but not so much for geothermal industry. This paper aims to reveal a study on the potential application of Nickel chromium-based coating, high-velocity oxygen fuel (HVOF) sprayed, for geothermal power plants components for corrosion-erosion and wear protection. Various tests and analysis were performed to assess the suitability of the coating for the geothermal environment. Microstructure and chemical composition of the coating was analyzed by optical and Secondary Electron Microscope (SEM) equipped Energy Dispersive X-Ray Spectroscopy (EDS). The mechanical properties of the coatings were evaluated through nano-indentation and adhesion tests. Hardness test of the coating was measured with a Vickers hardness tester, using 200 g load. The hardness value of the coating was high in comparison with the reference sample. Wear tests revealed that the sprayed layer had good adhesion and cohesion, and that the wear resistance improved by 12% compared to the reference sample. The samples were exposed to geothermal steam for thirty days to test the erosion-corrosion resistance. The coating was investigated before and after the corrosion test with visual, optical and electron microscopic analysis to investigate the corrosive effect of the geothermal steam. The results from the EDS analysis showed evidence of some minor erosion-corrosion damages at the surface of the coating as well as delamination and cracking of the coating.

On the Erosion–Corrosion Behavior of Active Screen Plasma Nitrided St52 Steel

In this work, samples of St52 steel were plasma nitrided using an iron screen, in an N2: H2 gas mixture ratio of 4 : 1, at 500 and 550°C for 5, 10 and 15 h. The X-ray diffraction and optical microscopy methods were used for structural characterization of the coatings. Results indicated that the coatings were composed of Fe2–3N and Fe4N phases growing at longer deposition times. Moreover, the Fe2–3N phase was decomposed to Fe4N after 10 h of plasma nitriding. The erosion–corrosion behavior of nitrided coatings and a bare substrate were studied in various impact angles: 30, 45, 60 and 90 degrees. Polarization curves of the coated and uncoated samples were recorded between–900 to 600 mV, as a function of the slurry impact angle. Results showed that an active screen plasma nitriding method significantly enhanced the erosion–corrosion resistance of the St52 steel. Moreover, an impact angle of 30° on the sample surface yielded a lower weightloss whereas increasing the impact angle up to 90° caused more weight-loss due to the brittle characteristic of iron nitride coatings. According to SEM micrographs, by increasing the impact angle up to 90°, the depth of the removed mass increased substantially.

Erosion-corrosion resistance of Reduced Activation Ferritic-Martensitic steels exposed to flowing liquid Lithium

In the framework of the IFMIF (International Fusion Materials Irradiation Facility) project, a lab scale plant named Lifus 6, designed and constructed in ENEA Brasimone Centre (Italy), has been employed for the evaluation of the resistance of Reduced Activation Ferritic-Martensitic (RAFM) steels to the erosion-corrosion mechanism exerted by flowing liquid Lithium. In this experimental campaign, Eurofer 97 and F82H specimens have been subjected to three different tests, defined by a Lithium temperature of 330 °C, a Nitrogen concentration in Lithium ≤30 wt ppm, a Lithium speed on the specimens surface of 15 m/s and by a duration respectively of 1222, 2000 and 4000 h. The assessment of the tests outcome has been made on the basis of the registered mass variation of each specimen, as well as its roughness alteration and its metallographic and compositional investigation. The analyses indicate the good resistance behavior of both the materials, which are characterized by corrosion rates <0.2 μm/year, very few and isolated corrosion items and only a small Chromium and Tungsten depletion in the alloy composition at the surface.

Evolution of the Corrosion Product Film and Its Effect on the Erosion–Corrosion Behavior of Two Commercial 90Cu–10Ni Tubes in Seawater

The composition and structural evolution of the corrosion product film of two commercial 90Cu–10Ni tubes, namely Tube A and Tube B, after being immersed in natural seawater for 1, 3, and 6 months were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, and its effect on the erosion–corrosion behavior of the tubes was determined through a rotating cylinder electrode system using various electrochemical techniques. For the freshly polished samples used as contrast samples, the flow velocity mainly enhanced the cathodic reaction at low flow velocities while both the anodic and the cathodic reactions were remarkably accelerated at higher flow velocities. The corrosion product films formed on the two commercial 90Cu–10Ni tubes after being immersed in seawater for up to 6 months are of a complex three-layer or multilayer structure. The structural evolution of the films is out of sync for the two tubes. A continuous residual substrate layer depleted of Ni was observed in the inner layer of the films on Tube B after 30, 90, and 180 days’ immersion, while it was observed in the film on Tube A only after 180 days’ immersion. The nature of the inner layer plays a crucial role in the erosion–corrosion resistance of the 90Cu–10Ni tubes at higher flow velocity. The film with a compact and continuous inner layer of Cu2O doped with Ni2+ and Ni3+ which bonds firmly with the substrate could survive and even get repaired with the increased flow velocity. The film on Tube B possessing a hollow and discontinuous inner layer composed of the residual substrate was degraded rapidly with increasing rotation speed in spite of its quite good resistance at the stagnant or lower speed conditions.

Exploring the Nickel–Graphene Nanocomposite Coatings for Superior Corrosion Resistance: Manipulating the Effect of Deposition Current Density on its Morphology, Mechanical Properties, and Erosion‐Corrosion Performance

The use of graphene‐based composite as anti‐corrosion and protective coatings for metallic materials is still a provocative topic worthy of debate. Nickel–graphene nanocomposite coatings have been successfully fabricated onto the mild steel by electrochemical co‐deposition technique. This research demonstrates the properties of nickel–graphene composite coatings influenced by different electrodeposition current densities. The effect of deposition current density on the; surface morphologies, composition, microstructures, grain sizes, mechanical, and electrochemical properties of the composite coatings are executed. The coarseness of deposited coatings increases with the increasing of deposition current density. The carbon content in the composite coatings increases first and then decreases by further increasing of current density. The improved mechanical properties and superior anti‐corrosion performance of composite coatings are obtained at the peak value of current density of 9 A dm−2. The incorporation of graphene sheets into nickel metal matrix lead to enhance the micro hardness, surface roughness, and adhesion strength of produced composite coatings. Furthermore, the presence of graphene in composite coating exhibits the reduced grain sizes and the enhanced erosion–corrosion resistance properties.

An AZ31 magnesium alloy coating for protecting polyimide from erosion-corrosion by atomic oxygen

A continuous and uniform AZ31 magnesium alloy coating was deposited by magnetron sputtering to protect flexible polyimide substrate (Kapton HN) from atomic oxygen (AO) erosion-corrosion in low earth orbit. The AO erosion yield of the coated Kapton was determined to be 8.87 × 10−26 cm3 atom−1 after exposure to AO fluence of 1.47 × 1021 atoms cm−2, about 34 times lower than that of blank Kapton. XPS analysis results showed that an oxide layer of MgO formed on the surface of the coating after AO exposure, which is the main reason for the enhanced AO erosion-corrosion resistance of the AZ31 Mg-alloy coating.

STUDY ON CORROSION RESISTANCE OF CARBON NANOTUBES REINFORCED Al2O3 COATING

This paper presents our research on the reinforcement with 1 % of carbon nanotubes (CNT) for a ceramic Al2O3 coating applied by air plasma spray (APS) on CT3 steel. The corrosion resistances of both CNTs reinforced and non-CNTs reinforced Al2O3 coatings were investigated by using different such techniques as: potentiodynamic polarization; electrochemical impedance spectroscopy (EIS); salt spray and erosion corrosion tests.The obtained results show positive effects of CNT to improve the corrosion protection of the Al2O3 coating: time of appearance of first rust points on the surface in the salt spray test increased from 2 hours for pure Al2O3 coating to 24 hours for the CNTs-Al2O3 one; the erosion-corrosion resistance of the CNTs-Al2O3 coating increased about 17 % in comparison with the one of the Al2O3 coating.

Ultrasonic cavitation erosion-corrosion behavior of friction stir processed stainless steel

Cavitation erosion remains the primary cause of material degradation in fluid machinery components operating at high speed. Micro-jets/shock waves caused by implosion of bubbles on material surface results in significant material loss and premature failure of the components. The presence of corrosive medium further exuberates this effect, causing rapid degradation. Here, we demonstrate a novel pathway to control cavitation erosion-corrosion by tailoring the surface properties using submerged friction stir processing (FSP), a severe plastic deformation process. FSP parameters were varied over wide range of strain-rates to generate tailored microstructures. High strain-rate processing resulted in nearly single phase fine grained structure while low strain-rate processing resulted in phase transformation in addition to grain refinement. As-received and processed samples were subjected to ultrasonic cavitation in distilled water as well as in corrosive environment of 3.5% NaCl solution. Individual roles of cavitation erosion, corrosion and their synergistic effects were analyzed. Depending on the microstructure, processed samples showed nearly 4–6 times higher cavitation erosion resistance compared to as-received alloy. Superior cavitation erosion-corrosion resistance of processed samples was attributed to surface strengthening, higher strain-hardening ability and quick passivation kinetics. The results of current study could be potentially transformative in designing robust materials for hydro-dynamic applications.