Investigation of Erosion Corrosion Caused by Drinking Water in the Faucet with Computational Fluid Dynamics

In this study,the reason for erosion-corrosion of drinking or mains water in the faucet was investigated by computational fluid dynamics.Pipes used in homes,the service sector,and industry are responsible for transporting different types of fluids from one place to another.Considering the faucet design,the SolidWorks program was used for 3D studies.In-faucet flow analyses were performed using Ansys Fluent,a computational fluid dynamics program based on the finite volume method.In the analyses,lime particles were chosen.At the end of the analysis,the amount of erosion in the faucet was obtained.

Comparative study of mechanical, corrosion and erosion-corrosion properties of cast hyper-duplex and super-duplex stainless steels

Duplex stainless steels(DSSs)used in subsea structures and desalination industries require high corrosion and erosion resistance as well as excellent mechanical properties.The newly introduced cast duplex grade ASTM A8907 A has a unique composition and is expected to have a much better resistance to corrosion and erosion compared with the super-duplex grades 5 A and 6 A.This work is a comparative study of the mechanical properties,corrosion,and erosion-corrosion resistance of super-duplex grades 5 A and 6 A and the hyper-duplex grade 7 A.The three DSSs exhibited equiaxial austenite islands in the ferrite matrix and balanced phase ratios.The hardness of the grade 7 A was nearly 15%higher than those of the super-duplex grades,which is attributed to the effect of the higher contents of W and Mn in 7 A.The impact toughness of grade 7 A was found to be lower than those of the super-duplex grades due to the carbide precipitation resulting from the partial substitution of Mo with W.The oxide layer strengthening effect of rare earth elements and the higher pitting resistance equivalent number(PREN)of grade7 A resulted in higher corrosion resistance.The harder and more passive grade 7 A showed a 35%lower material loss during erosion-corrosion.

Erosion–corrosion behavior of SAF3207 hyper-duplex stainless steel

Polarization curves and mass losses of SAF3207 hyper-duplex stainless steel under various conditions were measured.The damaged surfaces after erosion–corrosion tests were characterized by scanning electron microscopy.The results showed that an increase in flow velocity could enhance the electrochemical corrosion and consequently decrease the passivation properties of the steel.The erosion–corrosion damage of the samples increased substantially when the flow velocity exceeded the critical value of 4 m·s^-1.The mass loss rate increased as the sand content increased,reaching a maximum at 7 wt%sand content,corresponding to the most severe electrochemical corrosion damage.When the sand content was increased further,however,the mass loss rate decreased and then tended stable.The mass loss was divided into incubation,sustained,and stationary periods,with a maximum mass loss rate of 12.97 g·h^-1·m^-2 after an erosion period of 2.5 h.The erosion–corrosion mechanism was investigated in detail.

Erosion and erosion-corrosion of Al-brass alloy: Effects of jet velocity, sand concentration and impingement angle on surface roughness

Effects of jet velocity,sand concentration and impingement angle on the surface roughness of Al-brass alloy were investigated after erosion and erosion?corrosion tests.The tests were performed using a jet impingement rig.The eroded surfaces were characterized using2-D and3-D surface profilometery and scanning electron microscopy(SEM).The results showed that there was an increase in the surface roughness of the erosion?corrosion samples as sand concentration was increased to1,5and10g/L at jet velocities of9,6and3m/s,respectively.However,the surface roughness decreased with a further increase in sand concentration.This decrease in the surface roughness was attributed to the higher work hardening of the surface,rebounding or blanketing effect and very high frequency of the impacts at the higher sand concentrations.The surface roughness increased as the jet velocity increased.The results also showed that the change in the surface roughness with impingement angle was not significant at two jet velocities of3and6m/s.However,at a higher jet velocity of9m/s,formation of ripples on the erosion surfaces at oblique angles resulted in a higher surface roughness as compared with the normal impingement angle.

Erosion-Corrosion Behaviors of High Velocity Arc Sprayed Fe-AlCr_3C_2 Coating

Iron aluminide intermetallic coatings were prepared from Fe-Al/Cr3C2 cored wires using High Velocity Are Spraying （ HVAS ） technology. Erosion and corrosion properties of HVAS sprayed Fe-Al/Cr3C2 coatings were investigated. Results show that the erosion at impingement angle of 30°is more than that of 90°. The erosion resistance of coatings was enhanced uith the inereaase of temperature. Coatings had a better erosion resislance than substrwles. The erosion changed from ductile behariors to brittle behaviors above 450℃ . At high temperature, the erosion resistances were superior to those at low temperwlure and roonl temperwlure. Cowlings had much higher corrosion properties than substrates. The temperature had a little effect on the corrosion resistance of coatings ; The corrosion losing of cowlings increased slowly with the increase of corrosion time. The HVAS-sprayed Fe-Al/Cr3C2 coatings exhibited a high bond strength and hardness.

Effect of Aging Temperature on Erosion-Corrosion Behavior of 17-4PH Stainless Steels in Dilute Sulphuric Acid Slurry

The effect of aging temperature on erosion corrosion （E-C） behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The effect of impact velocity on EC behavior of 17 4PH steels at different aging temperatures was analyzed. Surface micrographs of the specimens after E C test were observed by using scanning electron microscope （SEM）. The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 ℃ to 610℃, the hardness reached the highest value near the temperature 460℃. The characteristics of E-C for 17-4PH stainless steels at different aging temperatures were as follows： pure erosion （wear） was dominant, corrosion was subordinate and at the same time corrosion promoted erosion. The effect of aging temperature on E-C rate of 17-4PH steels was not significant at low impact velocity, but it was found that E-C resistance of 17-4PH steels aged near 460℃ was the most excellent due to the best precipitation strengthening effect of fine and dispersed e-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials.

Microstructures and erosion-corrosion behavior of Fe-B alloy containing chromium and nickel

The Fe-B alloy containing chromium and nickel was prepared, and the microstructure and erosioncorrosion behavior of the alloy were investigated by means of scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction analysis, Leica digital image analysis, a hardness tester and an erosioncorrosion tester. Cr28 white cast iron was used for comparison. Results show that the microstructures of both as-cast and heat-treated Fe-B alloys consist of austenite and borocarbide. The nickel and chromium elements are mainly distributed over the matrix and borocarbide, respectively. The hardness of the austenite matrix and the Rockwell hardness of heat-treated Fe-B alloy are higher than those of as-cast Fe-B alloy. In the erosioncorrosion test of the slurry, the erosion-corrosion weight loss of Fe-B alloy is lower than that of Cr28 white cast iron, indicating the Fe-B alloy displays higher erosion-corrosion resistance.

DEVELOPMENT OF NEW EROSION-CORROSION RESISTANT CUPRONICKEL ALLOYS

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Characterisation and Corrosion-Erosion Behaviour of Carbide based Thermal Spray Coatings

Thermal spraying has emerged as a suitable and effective surface engineering technology and is widely used to apply wear, erosion and corrosion protective coatings for various kinds of industrial applications. Cr3C2-based coatings have been applied to a wide range of industrial components. Cr3C2-NiCr coatings offer greater corrosion and oxidation resistance, also having a high melting point and maintaining high hardness, strength and wear resistance up to a maximum operating temperature of 900 °C. The corrosion resistance is provided by NiCr matrix while the wear resistance is mainly due to the carbide ceramic phase. This paper reviews the performance, developments and applications of Cr3C2-NiCr thermal spray coatings for corrosion/erosion-corrosion under different types of environments and outlines the characterization of Cr3C2-NiCr coatings with respect to their microstructure and mechanical properties, together with some brief characterisation work by the author for HVOF sprayed 75Cr3C2-25NiCr coating on T91 boiler steel.

Effect of preferential dissolution on erosion-corrosion for chromium steel in alkali slurry

An investigation was carried out concerning the effect of preferential dissolution on the erosion-corrosion for a chromium steel in 1 mol/L NaOH. Preliminary tests using a potentiodynamic technique were performed in order to establish the presence of preferential dissolution in the alkali solution with and without the alumina particles at different rotation speeds. For purposes of quantifying the observed phenomena a potentiostatic mass loss method was also used. The results show that the active peaks occur at potential between +0.4 and +0.5 V on the polarization curves, which indicates that there is a preferential dissolution for chromium steel under erosion-corrosion conditions and the ferrite phase acts as a sacrificial anode in favor of (Fe,Cr) 7C 3 phase. Addition of particles can promote the preferential dissolution at different rotation speeds. The combined effects of erosion-corrosion results in total mass loss rates to be greater than the sum effects of each process taken alone, thus showing a strong synergism between erosion and corrosion due to preferential dissolution.

Corrosion-erosion resistance of Zn-Al co-cementation coatings on carbon steels in aqueous media

A novel Zn Al co cementation coating was obtained by a pack cementation method. This coating possesses a two layered structure. The outer layer is mainly composed of Fe 2Al 5 and FeAl intermetallics with a small amount of Zn, and the inner layer consists of Zn, Fe and a small amount of Al. The corrosion erosion resistance of Zn Al co cementation coatings on carbon steel was studied by a rotary corrosion method in various NaCl and H 2S containing solutions and relevant SiO 2 containing media. The experimental results are compared with those of carbon steels and the sherardizing and aluminizing coatings, showing that the Zn Al co cementation coatings have excellent corrosion erosion resistance in various aqueous media.

Comparison and Analysis of Erosion-Corrosion Test Apparatus IJR and RCE

The test apparatus used for investigating erosion-corrosion in aqueous media, including the pipe flow loop, impinging jet, rotating disk and rotating cylinder rigs is reviewed. With combining the impinging jet rig and rotating cylinder electrode rig, the hydrodynamic characteristics of both rigs are analysed.

2D Materials as Protective Coating against Low and Middle Temperature (100°C - 300°C) Corrosion-Erosion in Waste to Energy Plant: Case of Graphene

The combustion of MSW contains several species which if liberated into the flue gas will participate in erosion-corrosion reactions with the alloy surface and with the oxide layers. Actually with the evolution of material science and the discovery of 2D materials, we can handle that situation as well as possible. The graphene as 2D material presents a lot of advantage due to it physical properties such: melting point, boiling point and thermal conductivity, which can help to manage the problem of low and middle temperature (100°C - 300°C) erosion-corrosion into the boiler wall of waste to energy. The aim of the study was focused on analyzing the resistance at low and middle temperature (100°C - 300°C) in the enclosed environment and the corrosion-erosion resistance abilities of the graphene sheet as the 2D protective coating material. This paper analyzed the possibility of using the graphene in the aggressive environment which is waste to energy boiler. The results obtained from this study after simulation using ANSYS software which is one of the best software for simulations showed that Graphene protects the furnace walls against corrosion-erosion for temperatures lower than 400°C and that in the presence of certain impurities such as: sodium (Na), sulfur (S), chloride (Cl) and Phos- phorous (P), Sodium Chloride (NaCl), Hydrogen Chloride (HCl), Dioxide of Carbone (CO2) and Dioxide of Sulfur (SO2).

Experimental and Numerical Investigation on Erosion Corrosion of the Air Cooler Tube Bundle in a Residue Hydrotreating Unit

Corrosion leakage occurred in the 14th tube bundle in the first row of a residual oil hydrotreating air cooler after operating for two years.The failure location was 0.5 m from the outlet header box.In this paper,the erosion corrosion of the air cooler tube bundle was investigated by experimental and numerical methods.Visual inspection,scanning electron microscopy(SEM),and X-ray diffraction(XRD)experiments were performed,and the failure morphology and material composition confirmed that the damage was caused by erosion corrosion.The shear stress transport k–ωturbulence model(SST-k–ω)was then used to investigate the flow and erosion corrosion characteristics,combined with mass transfer,corrosion rate,and ionization equilibrium models.The numerical simulation results revealed that the water phase volume fraction increased with flow and heat transfer in the fluid,which increased the mass flow rate and concentration of hydrogen sulfide.The mass transfer coefficient and corrosion rate were proposed as important parameters to characterize erosion corrosion.Moreover,the local concentration of wall shear stress was found to increase the risk of erosion corrosion.The predicted high-risk area was consistent with the actual failure area,which verified that this failure incident was attributable to erosion corrosion by the water phase.

Correlation between microstructure and corrosion and cavitation erosion behaviors of nickel aluminum bronze

The microstructure,corrosion and cavitation erosion(CE)behaviors of the as-cast and four different heat treated nickel aluminum bronzes(NABs)in 3.5 wt.%NaCl solution were investigated.The results show that after annealing,β′transformed into the eutectoid microstructure,and moreκIV precipitated fromα.Less eutectoid microstructure and moreβ′were obtained after normalizing.The quenched NAB mainly consisted ofαandβ′phases,and fine,acicularαandκphases precipitated insideβ′after subsequent aging.The largest proportion of the eutectoid microstructure,which underwent severe selective phase corrosion,was responsible for the lowest corrosion resistance of the annealed NAB.The quenched NAB possessed the most protective film and hence the highest corrosion resistance.The mechanical attack was primarily responsible for the CE damage for the as-cast,annealed and normarlized NABs.The quenched and quenched+aged NABs exhibited superior CE resistance because of the high hardness.The CE−corrosion synergy dominantly caused CE degradation,and it was largely attributed to corrosion-enhanced-CE.

Erosion–corrosion behavior of austenitic cast iron in an acidic slurry medium

A series of austenitic cast iron samples with different compositions were cast and a part of nickel in the samples was replaced by manganese for economic reason. Erosion–corrosion tests were conducted under 2wt% sulfuric acid and 15wt% quartz sand. The results show that the matrix of cast irons remains austenite after a portion of nickel is replaced with manganese.（Fe,Cr）3C is a common phase in the cast irons, and nickel is the main alloying element in high-nickel cast iron; whereas,（Fe,Mn）3C is observed with the increased manganese content in low-nickel cast iron. Under erosion–corrosion tests, the weight-loss rates of the cast irons increase with increasing time. Wear plays a more important role than corrosion in determining the weight loss. It is indicated that the processes of weight loss for the cast irons with high and low nickel contents are different. The erosion resistance of the cast iron containing 7.29wt% nickel and 6.94wt% manganese is equivalent to that of the cast iron containing 13.29wt% nickel.

Erosion and Corrosion of Mild Steel and Stainless Steel in Sodium Carbonate/Bicarbonate Solution Bearing Alumina Particle

With a rotating cylinder electrode apparatus,the polarization behaviors of the mild steel and the stainless steel 0Cr18Ni9 in NaHCO3(0.5M)+Na2CO3(0.5M)solution with and without erodent particles were investigated and compared.The results show that the rotation speed of cylinder hardly affects the polarization behavior of sample in solution without particles but exerts a great influence on that with particles.Increasing rotation speed,the free corrosion potential shifts to positive direction and the oxygen limiting current density increases.Both the mild steel and stainless steel 0Cr18Ni9 experience a significant increase of the mass loss by increasing erosion,and erosive wear was dominated by severe micro-plowing.The insufficient mechanical strength of both materials leads to a low resistance to particle removal.Increasing peripheral velocities of the rotating cylinder enhances the corrosion rate of the mild steel.The stainless steel 0Cr18Ni9,due to a high erosive wear,also suffers from similar erosion-corrosion damage,despite that its corrosion resistance is much higher than that of the mild steel.

Hot Corrosion &Erosion Problems in Coal Based Power Plants in India and Possible Solutions – A Review

Hot corrosion and erosion are recognized as serious problems in coal based power generation plants in India. The coal used in Indian power stations has large amounts of ash (about 50%) which contain abrasive mineral species such as hard quartz (up to 15%) which increase the erosion propensity of coal. Hot corrosion and erosion in boilers and related components are responsible for huge losses, both direct and indirect, in power generation. An understanding of these problems and thus to develop suitable protective system is essential for maximizing the utilization of such components. These problems can be prevented by either changing the material or altering the environment or by separating the component surface from the environment. Corrosion prevention by the use of coatings for separating material from the environment is gaining importance in surface engineering.

Corrosion of NiFe_2O_4-10NiO-based cermet inert anodes for aluminium electrolysis

NiFe2O4-10NiO-based cermet inert anodes for aluminium electrolysis were prepared and their properties were investigated in a lab-scale electrolysis cell. The results show that the inert anodes exhibit good performance during electrolysis in molten salt cryolite at 960 °C, but according to the analyses of phase compositions and microstructures through XRD, SEM/EDX and metallographic analysis, the metal in the anodes is preferentially corroded and many pores are produced on the anode surface after electrolysis. The preferential dissolution of Fe in the NiFe2O4 phase may lead to the non-uniform corrosion of NiFe2O4 grains. Moreover, a dense protective layer of NiFe2O4-NiAl2O4-FeAl2O4 is formed on the anode surface, which originates from the reaction of Al2O3 dissolved in the electrolyte with NiO or FeO, the annexation of NiFe2O4-NiAl2O4-FeAl2O4 to NiO and volume expansion. Thus, the dense NiFe2O4-NiAl2O4-FeAl2O4 layer inhibits the metal loss and ceramic-phase corrosion on the surface of the cermet inert anodes.

Effects of T6 heat treatment on mechanical, abrasive and erosive-corrosive wear properties of eutectic Al-Si alloy

The abrasive and erosive-corrosive properties of eutectic Al-Si （LM6） alloy were studied. Microstructural features of the alloy were altered by controlling the T6 heat treatment parameter, and their influence on hardness, strength and elongation, and response of the samples in erosion-corrosion and abrasion conditions were studied. Characteristics of the Al-Si alloy samples were compared with those of Al conventionally used in agricultural machineries. Fabrication of a typical component using the Al-Si alloy was also explored in order to understand the feasibility of using the alloy system for the envisaged applications. The study suggests the response of the samples in different conditions to be greatly influenced by parameters like chemical composition, microstructural features and applied load, traversal distance and test environment. The performance of even the as cast Al-Si alloy is far superior to that of the conventional Al samples, while the T6 heat treated Al-Si alloy shows improved performance. Accordingly, the as-cast as well as T6 heat treated Al-Si alloy has potential for applications in agriculture as a replacement for the conventionally used Al.