High Temperature Corrosion Behavior Research Articles

Microstructure, Hardness and High-Temperature Corrosion Behaviors in Sulfur-Containing Environment of Laser Cladding Y2O3/IN625 Composite Coating.

Water-cooled wall tubes are susceptible to high-temperature corrosion during service. Applying high-performance coatings via laser cladding on the tube surfaces can significantly enhance corrosion resistance and extend the service life of the tubes, providing substantial economic advantages. This paper prepared Y2O3/IN625 composite coating by means of high-speed laser cladding. Furthermore, the effects of Y2O3 addition on the microstructure evolution, hardness, as well as the high-temperature corrosion behaviors have been systematically investigated. The results show that Y2O3 addition can effectively refine the microstructure of the Inconel 625 coating, but the phase composition has little change. The coating's hardness can also be improved by about 7.7%, reaching about 300 HV. Compared to Inconel 625 coating, the Y2O3-added composited coating shows superior high-temperature corrosion resistance, with the corrosion mass gain decreased by about 36.6%. The denser and tightly bonded Cr-rich oxides layer can be formed adjacent to the coating surface, which plays a predominant role in improving the coating corrosion resistance.

Corrosion behavior and mechanism of Inconel 625 coatings in high-temperature acidic environments for waste incineration applications

This study explores the high-temperature corrosion behavior and mechanisms of laser-clad Inconel 625 coatings applied in waste incineration environments. Inconel 625 coatings were deposited on a substrate using laser cladding technology, and corrosion tests were performed in various high-temperature acidic environments. The coatings were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and laser confocal microscopy to investigate their microstructure, composition, and corrosion products. The findings indicate that corrosion weight gain was most pronounced in HCl environments at 800 °C and HBr environments at 600 °C, underscoring the critical influence of temperature and acidity on reaction kinetics. Moreover, the corrosion morphology was closely tied to the environment, with distinct patterns observed: pitting in HCl, nodular growth in H2SO4, and cracking and spalling in HF and HBr environments. High temperatures promoted oxidation reactions, resulting in the formation of a dense oxide layer predominantly composed of Cr2O3 and NiCr2O4, which offered some degree of protection. However, pitting and cracking in acidic environments suggested that the protective oxide layer's effectiveness was compromised under extreme conditions. This study provides a comprehensive understanding of the corrosion behavior and mechanisms of Inconel 625 coatings in various acidic environments and high temperatures within waste incineration applications. It offers valuable insights into the impact of temperature and different acidic media on corrosion rates and morphologies, laying the groundwork for predicting the service life and developing protective strategies for these materials in industrial settings.

Editorial on the Influence of Additive Manufacturing on the High-Temperature Corrosion Behaviour of Alloys

Editorial on the Influence of Additive Manufacturing on the High-Temperature Corrosion Behaviour of Alloys

Generation mechanism of Si–Y–B-Yb ceramics with enhanced water-oxygen corrosion resistance

This study systematically investigates the influence of preparation temperature on microstructure and generation mechanism of Si–Y–B-Yb ceramics as anti-corrosion matrix. Main phases of Si–Y–B-Yb ceramics are Y/YbB4, YSi2, and Si, where Y/YbB4 is derived from the reaction between YSi2 and YbB6. With increase in preparation temperature, open porosity of Si–Y–B-Yb ceramics gradually decreases, reaching 0.24 % at 1350 °C, and internal phases transform from a dispersed distribution to clearly defined boundary state. Based on this, high-temperature water-oxygen corrosion behavior of Si–Y–B-Yb ceramics is characterized in 50 vol% H2O+50 vol% O2 environment at 1250 °C for 100 h. In this corrosive environment, silicate phase appears on the surface of Si–Y–B-Yb ceramics. With prolonged corrosion time, silicate phase gradually forms more complete protective layer, hindering further corrosion by water-oxygen environment. These results demonstrate the feasibility of proposed Si–Y–B-Yb materials for corrosion protection.

High temperature corrosion behavior and mechanism of steel slag-based glass ceramic in the eutectic carbonates

Steel slag-based glass ceramic for thermal energy storage was first fabricated by quenching method, and then their high temperature corrosion behavior in the eutectic carbonates and related mechanism have been investigated using X-ray diffraction，Raman spectroscopy and scanning electron microscope techniques. The results show that holding time has a significant influence on the corrosion layer thickness at 800oC. As the holding time was extended, the thickness of the corrosion layer with obvious cracks tended to increase. Further EDS analyses disclosed that the divided corrosive layers along the extended directions of the cracks should be similar in both the compositions and microstructure. Based on these observations, the possible corrosion mechanism was discussed after defining phase structure of nonstoichiometric (Fe0.35Al0.20Mg0.44) Ca0.96(Fe0.08Si0.70Al0.20)2O6.12 as a combined system of CaMgSi2O6(Di)-CaFe3+AlSiO6(Es)-CaAl2Si2O8(An). Oxygen offered by the molten carbonates salt is regarded to play a critical role in the corrosion process. In an atmosphere rich in oxygen, both Na+ and K+ ions diffused into the diopside can replace Ca2+ and Mg2+, etc. resulting in polyhedral structural reorganization for electrical neutrality. On the other hand, the bonding stability of the cation-oxygen bonds in diopside was proved to be weaker than that in single oxides. These two aspects contribute to the continuous dissolution of Ca2+ and Mg2+, etc. in the molten carbonates salt.

Effect of shot peening on surface characteristics and high-temperature corrosion behaviour of super 13Cr martensitic stainless steel

Super 13Cr, as an economy stainless steel (SS) for oil country tubular goods, needs stable corrosion resistance in high-pressure and high-temperature (HPHT) downhole medium. Severe plastic deformation (SPD) are the surface modification technology to improve mechanical properties, fatigue behavior and corrosion resistance of metals, and shot peening (SP) has been the most widely used SPD process. However, there are quite limited studies about the microsutructure evolution, residual stress, and high-temperature corrosion behavior of SP-treated martensitic SS. In this study, super 13Cr martensitic SS was treated by SP with various air pressures and nozzle speeds. The surface characteristics and high-temperature corrosion behaviour in 3.17 mol/L K2HPO4 solution were investigated through finite element model analysis, characterization of residual stress and microstructure, as well as electrochemical and stress corrosion cracking (SCC) tests at 160 °C and 10 MPa. The results showed that SP-treated super 13Cr could generate high-level compressive residual stress and SPD microstucture, including nano-sized equiaxed grains, gradient lamellar structure and fragmented carbides. Increasing air pressure contributed to achieve uniform nanocrystalline, but tended to generate high dislocation density and surface defects. The improving effect of SP treatment at low air pressure of 0.15 MPa on passivation ability was limited, and high air pressure adversely impacted corrosion resistance. SP-treated specimens showed high SCC susceptibility, due to the introduction of more surface defects, high angle grain boundaries, and dislocations.

High-temperature corrosion testing of titanium beryllides in the presence of water vapor and oxygen

Beryllium-based intermetallics are promising materials for the blankets of future fusion reactors and have potential applications in other areas of the nuclear industry, such as fission reactor reflectors and space technology. Understanding the high-temperature corrosion behavior of these materials in a noble gas medium containing chemically active impurities is essential for evaluating their suitability and guiding their application.This study investigates the high-temperature corrosion of titanium beryllide Be12Ti in the form of plate and grinded samples, produced by JSC “Ulba Metallurgical Plant” (Ust-Kamenogorsk, Kazakhstan). The corrosion tests were conducted under non-isothermal vapor-gas mixture (Ar + D2O or Ar + H2O flowing atmospheres) purging conditions using thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), and mass-spectrometry of the gas phase.As a result of the corrosion tests, new experimental data on thermal effects have been obtained, describing the corrosion processes of Be12Ti samples across a wide range of temperatures and various heating rates in the presence of water vapor in the purge gas. The dependencies of sample mass change under heating conditions have been determined, and the characterization results of the samples before and after high-temperature corrosion tests are presented.Corrosion of titanium beryllides, both for Be12Ti plate and grinded samples, follows similar mechanisms. At around 500 °C, the mass of the samples begins to increase, and hydrogen isotopes are released. The test results indicate that corrosion of titanium beryllides with varying surface inhomogeneities proceeds similarly within the temperature range of 500–900 °C, showing a linear dependence on temperature.The results revealed significant insights into the oxidation mechanisms and the formation of corrosion products, which are crucial for optimizing the material's performance in fusion reactor environments.

High-temperature corrosion behavior of 316 H stainless steel in lead-bismuth eutectic containing cesium

The influence of Cs on the corrosion of 316 H stainless steel pipework when exposed to liquid lead–bismuth eutectic (LBE) coolant, specifically LBE containing 0.5 wt% Cs at high temperature, is investigated. The addition of Cs in LBE can significantly accelerate the corrosion of 316 H stainless steel. Cs in LBE first destroys the Cr2O3 film on the surface of the stainless steel and reacts with Cr23C6 enriched at grain boundaries. Finally, the reaction between Cs and FeCr2O4 creates pores in inner oxide layer (IOL), thus destroying the protection provided to 316 H stainless steel by the IOL.

High-temperature hot corrosion kinetics of PVD Ti1-xAlxN coatings on Nimonic c-263

The high-temperature hot corrosion (HTHC) behavior of Ti1-xAlxN-coated c-263 alloy was studied with- and without a Na2SO4/MgSO4 salt mixture at 850 °C in a SOx-rich atmosphere. In absence of the salt deposit, both, the bare c-263 alloy and cathodic arc evaporated Ti1-xAlxN specimens follow a quasi-cubic corrosion rate. However, when exposed to salt under identical conditions, the rates increase significantly, featuring a compounded parabolic-linear rate law for the c-263 alloy, and a parabolic-like rate behavior for Ti1-xAlxN-coated specimens. The rate-determining step of the HTHC mechanism was attributed to a nitride-to-oxide transformation, followed by a sequential fluxing of the formed oxides.

Experimental investigation on the high-temperature corrosion of 12Cr1MoVG boiler steel in waste-to-energy plants: Effects of superheater operating temperature and moisture

Waste-to-energy (WTE) technology via municipal solid waste incineration (MSWI) have developed very rapidly with the advantages of achievement on waste disposal and energy conversion. This technology is developing towards higher capacity and efficiency. Therefore, the operation parameters of WTE boilers must be improved. However, higher steam parameters means higher surface temperature of exchange tube in superheaters and reheaters in WTE boilers, resulting higher risk of engineering failure due to high-temperature corrosion. Additionally, the incineration of MSW releases flue gas with a high content of corrosive species and water vapor, which can cause severe high-temperature corrosion. This experimental investigation details the effect of surface temperature and water vapor concentration on the high-temperature corrosion behavior of 12Cr1MoVG boiler steel under an atmosphere mimicking MSWI. The corrosion test environment consists of high temperature, ash deposit and simulated flue gas of waste incineration according to a real WTE boiler. The experiment was conducted using a two-zone bench-scale tube furnace with a gas temperature of 600℃ and the sample temperatures of 380℃, 430℃, and 480℃. For the investigation of water vapor concentration effect, 18 % vol and 23 % vol were set up in this study. After 240 hours of exposure, the corrosion weight curves illustrated that the corrosion kinetics was highly dependent on the surface temperature of corrosion samples. Furthermore, an increase in water vapor concentration exacerbated the high-temperature corrosion. XRD analysis identified the corrosion products as metal chlorides and metal oxides. Cross-sectional SEM images and EDS analysis revealed that an increase in water vapor accelerated the corrosion rate of the steel samples due to chromium dilution behavior.

Tailored high-temperature corrosion behavior of Cr coatings using high power impulse magnetron sputtering on ZIRLO alloys for accident-tolerant fuel application

To further enhance the oxidation resistance of Zirconium alloys during Loss of Coolant Accident (LOCA), protective Cr coatings were deposited in synchronized pulse bias mode through high power impulse magnetron sputtering (HiPIMS). The results showed the weight gain of the Cr coatings with synchronized pulse bias was reduced by approximately 61.7 % compared to that of the Cr coatings without synchronized pulse bias after 90 min of steam oxidation at 1200 °C. This was mainly attributed to the formed intense (200) preferred orientation of the Cr coatings with synchronized pulse bias during deposition, accelerating the recrystallization growth of the residual Cr layer in a high-temperature steam environment, thereby reducing the rapid diffusion pathways for oxygen. Moreover, the synchronized pulse bias induced Cr grains refinement, favoring the formation of a more compact Cr2O3 scale, and therefore efficiently inhibiting the diffusion of external oxygen to the underlying alloy.

High-temperature creep and corrosion behavior of 316LN stainless steel in oxygen-saturated sodium

The high-temperature performance and sodium corrosion of in-core components are the main problems of liquid sodium-cooled reactors, and low-carbon nitrogen-controlled 316 stainless steel (316LN) is the main research and development direction of the main materials for the core of sodium-cooled fast reactors. In this work, the creep behavior of 316LN in oxygen-saturated liquid sodium at high temperatures (650 ℃, 700 ℃ and 750 ℃) was tested and compared with the results of creep tests in air at the same conditions. It is found that the creep life in the sodium environment is reduced by 63.44%, 67.93% and 40.07%, respectively. The specimens in oxygen-saturated sodium exhibit reduction in ductility, selective dissolution as well as oxidative corrosion. The corrosion mechanism of 316LN under external loading in oxygen-saturated sodium is illustrated.

Understanding the high-temperature corrosion behavior of zirconium alloy as cladding tubes: a review

Operated under extreme conditions, corrosion occurs between zirconium alloy cladding tubes and the coolant in the primary loop of pressurized water reactors (PWRs), contributing to a reduction in the effective metallic material thickness. Therefore, understanding the corrosion behavior of zirconium alloy is vital to both raising the burnup of PWR and the improvement of safety properties of these reactors. During the past decades, extensive investigation was conducted with various conditions, such as changing corrosion temperatures and alloying elements, but contradiction persists and universal conclusion remain elusive. In the present work, a variety of research results that focused on corrosion kinetics, microstructural evolution, and the influence of alloying elements were integrated and summarized, so that a valuable reference can be provided to further research.

Corrosion behaviors of Inconel 617 and Incoloy 800H in impure helium with different CO contents at high temperatures

The helium coolant of the very high-temperature gas-cooled reactor (VHTR) is expected to contain trace impurities, which will cause corrosion to superalloys at high temperatures. The high-temperature corrosion behaviors of Inconel 617 and Incoloy 800H were investigated in the impure helium with various CO levels. For Inconel 617, the microclimate reaction occurred at high temperatures, releasing large amounts of CO and destroying the oxide layer. The corrosion model was established according to the chemical thermodynamics theory, showing that the reaction temperature is related to the CO content. However, this corrosion behavior was not observed for Incoloy 800H. The corrosion difference between these alloys was analyzed in this study, indicating that the silicon oxide interlayer of Incoloy 800H may inhibit the microclimate reaction. Although the interlayer could attenuate the chemical destruction of the oxide layer, the adhesion may be reduced leading to thermal damage, which was proved by the experiment in this study. This research clarified the different corrosion mechanisms of these two alloys and provided guidance for the control scheme of CO content in the primary circuit of HTGR.

High temperature corrosion behavior of ADC12 aluminum alloy in oxalic acid solution

High temperature corrosion of ADC12 aluminum alloy in oxalic acid solution was investigated using weight loss, electrochemical measurements, surface technologies. The results showed that at room temperature, the aluminum alloy exhibited localized corrosion, while at high temperatures, it exhibited uniform corrosion. As the temperature rose from 30 °C to 90 °C, the rapid dissolution of its passivation film led to a 70.19% increase in the corrosion rate. After soaking for 72 h, its corrosion rate decreased by 74.35% because of the depletion of hydrogen ions and the accumulation of corrosion products. The corrosion products were mainly Al2O3 and aluminum oxalate.

High-temperature corrosion and carburization behaviour of austenitic stainless steels in impurity-added CO2 environments

The corrosion and carburization behaviour of four austenitic stainless steels were evaluated in CO2 and CO2+impurities (CH4, CO and O2) at 600 °C. Exposure to CO2, CO2+CH4, and CO2+CO environments showed poor corrosion resistance, especially in 316 grades with the spallation of Cr2O3 layer and breakaway corrosion. Conversely, materials showed improved corrosion resistance in CO2+O2 environment with thin Cr2O3 layer. TEM analysis of 316LN revealed carbon-accumulated layer at the Cr2O3–matrix interface for highly corrosive environments. The degradation of Cr2O3 adherency is correlated with the carbon-accumulated layer, resulting from the high carbon activity in CO2, CO2+CH4, and CO2+CO environments.

High-temperature corrosion behavior of the FeCrAl laser cladding coatings in waste-to-energy superheaters: Influence of Al content

Enhancing the high-temperature corrosion resistance of superheaters in waste-to-energy plants (WTE) is key to improving the efficiency of WTE power generation. The present study employed laser cladding technology to fabricate Fe-13Cr-xAl coatings, and characterized the microstructure, phase structure, and Vickers hardness of the coatings using OM, SEM, XRD, and a Vickers hardness tester. The study investigated the influence of high-temperature corrosion resistance of the coatings under simulated WTE flue gas conditions. This study found that: Al and Cr both exist in the form of solid solution atoms in the laser cladding coatings. The Vickers hardness of the coatings gradually increased with increasing Al content. When the Al content exceeds 10 %, cracks begin to appear in the coatings, and the number and size of cracks increase with increasing Al content. The Fe-13Cr-7Al coatings exhibit the best high-temperature corrosion resistance under simulated WTE flue gas conditions, and it can achieve ∼73 % of the high-temperature corrosion resistance of the Inconel 625 alloy laser cladding coatings. During high-temperature corrosion, phase separation occurs near the grain boundaries, resulting in chromium depletion zones, which promote intergranular corrosion of the coatings. During the process of high temperature corrosion, the reactions between Al, Cl, and S exhibit the lowest Gibbs free energy. The continuous consumption of Al effectively protects the Fe and Cr in the substrate. Additionally, the formation of aluminum oxide in the coating hinders the inward diffusion of Cl2, thereby beneficially impeding the progress of corrosion. Excessive Al contents in the coatings introduced cracks that served as channels for molten salt to penetrate the matrix, thereby reducing the high-temperature corrosion resistance of the coatings.

High-Temperature Corrosion Behavior of Fe-18Ni-12Cr-2.9Al and Fe-18Ni-12Cr-2.3Al-Nb-C Austenitic Steels Depending on Dissolved Oxygen Concentration in Static Liquid Pb at 700 °C

High-Temperature Corrosion Behavior of Fe-18Ni-12Cr-2.9Al and Fe-18Ni-12Cr-2.3Al-Nb-C Austenitic Steels Depending on Dissolved Oxygen Concentration in Static Liquid Pb at 700 °C

High-temperature corrosion of a Si3N4/W composite exposed to molten MgCl2-NaCl-KCl salts

The high-temperature corrosion behavior of a Si3N4/W composite under the molten MgCl2-NaCl-KCl salts has been investigated. It is suggested that the molten salts diffuse along the physical surface defects and enter the interior of adjacent Si3N4/W grains, leading to the 9.1% bending strength loss after 400 hours for corrosion. In air atmosphere, oxidation products WO2, WO3, and corrosion product MgWO4 caused a 34.3% bending strength decrease after 400 hours for corrosion. This study elucidates the high-temperature molten chloride salt corrosion mechanisms of the Si3N4/W composite material under two different atmospheres. The composite demonstrates relatively excellent corrosion resistance in service environments.

Phase stability and initial phase high-temperature corrosion behavior of non-stoichiometric lanthanum cerium oxide thermal barrier coatings

Three different compositions of lanthanum cerium oxide thermal barrier coatings with varied cerium oxide (1.8CeO2, 1.9CeO2 and 2.0CeO2) compositions were synthesized and plasma sprayed to achieve free-standing coatings. The phase stability studies showed that the coatings are stable at 1400 °C after 100 h. The high-temperature corrosion was performed in the presence of sulfate-vanadate (50 wt%Na2SO4+50 wt%V2O5) at 1000 °C for 4 h. The result depicts LaVO4 as the major corrosive product formed in all three compositions along with CeVO4, LaCeVO4 and CeO2. The hot corrosion test result gives information that the composition of CeO2 greatly influences the hot corrosion resistance. The increase in CeO2 percentage increases the resistance against the infiltration of molten sulfate-vanadate compounds. This investigation provides a feasible way to understand the coating composition for better hot corrosion resistance in sulfate-vanadate mixtures.